Merge branch 'kw/fsmonitor-watchman-racefix'

[git] / diff.c

/*
 * Copyright (C) 2005 Junio C Hamano
 */
#include "cache.h"
#include "config.h"
#include "tempfile.h"
#include "quote.h"
#include "diff.h"
#include "diffcore.h"
#include "delta.h"
#include "xdiff-interface.h"
#include "color.h"
#include "attr.h"
#include "run-command.h"
#include "utf8.h"
#include "object-store.h"
#include "userdiff.h"
#include "submodule-config.h"
#include "submodule.h"
#include "hashmap.h"
#include "ll-merge.h"
#include "string-list.h"
#include "argv-array.h"
#include "graph.h"
#include "packfile.h"
#include "parse-options.h"
#include "help.h"
#include "promisor-remote.h"

#ifdef NO_FAST_WORKING_DIRECTORY
#define FAST_WORKING_DIRECTORY 0
#else
#define FAST_WORKING_DIRECTORY 1
#endif

static int diff_detect_rename_default;
static int diff_indent_heuristic = 1;
static int diff_rename_limit_default = 400;
static int diff_suppress_blank_empty;
static int diff_use_color_default = -1;
static int diff_color_moved_default;
static int diff_color_moved_ws_default;
static int diff_context_default = 3;
static int diff_interhunk_context_default;
static const char *diff_word_regex_cfg;
static const char *external_diff_cmd_cfg;
static const char *diff_order_file_cfg;
int diff_auto_refresh_index = 1;
static int diff_mnemonic_prefix;
static int diff_no_prefix;
static int diff_stat_graph_width;
static int diff_dirstat_permille_default = 30;
static struct diff_options default_diff_options;
static long diff_algorithm;
static unsigned ws_error_highlight_default = WSEH_NEW;

static char diff_colors[][COLOR_MAXLEN] = {
        GIT_COLOR_RESET,
        GIT_COLOR_NORMAL,       /* CONTEXT */
        GIT_COLOR_BOLD,         /* METAINFO */
        GIT_COLOR_CYAN,         /* FRAGINFO */
        GIT_COLOR_RED,          /* OLD */
        GIT_COLOR_GREEN,        /* NEW */
        GIT_COLOR_YELLOW,       /* COMMIT */
        GIT_COLOR_BG_RED,       /* WHITESPACE */
        GIT_COLOR_NORMAL,       /* FUNCINFO */
        GIT_COLOR_BOLD_MAGENTA, /* OLD_MOVED */
        GIT_COLOR_BOLD_BLUE,    /* OLD_MOVED ALTERNATIVE */
        GIT_COLOR_FAINT,        /* OLD_MOVED_DIM */
        GIT_COLOR_FAINT_ITALIC, /* OLD_MOVED_ALTERNATIVE_DIM */
        GIT_COLOR_BOLD_CYAN,    /* NEW_MOVED */
        GIT_COLOR_BOLD_YELLOW,  /* NEW_MOVED ALTERNATIVE */
        GIT_COLOR_FAINT,        /* NEW_MOVED_DIM */
        GIT_COLOR_FAINT_ITALIC, /* NEW_MOVED_ALTERNATIVE_DIM */
        GIT_COLOR_FAINT,        /* CONTEXT_DIM */
        GIT_COLOR_FAINT_RED,    /* OLD_DIM */
        GIT_COLOR_FAINT_GREEN,  /* NEW_DIM */
        GIT_COLOR_BOLD,         /* CONTEXT_BOLD */
        GIT_COLOR_BOLD_RED,     /* OLD_BOLD */
        GIT_COLOR_BOLD_GREEN,   /* NEW_BOLD */
};

static const char *color_diff_slots[] = {
        [DIFF_CONTEXT]                = "context",
        [DIFF_METAINFO]               = "meta",
        [DIFF_FRAGINFO]               = "frag",
        [DIFF_FILE_OLD]               = "old",
        [DIFF_FILE_NEW]               = "new",
        [DIFF_COMMIT]                 = "commit",
        [DIFF_WHITESPACE]             = "whitespace",
        [DIFF_FUNCINFO]               = "func",
        [DIFF_FILE_OLD_MOVED]         = "oldMoved",
        [DIFF_FILE_OLD_MOVED_ALT]     = "oldMovedAlternative",
        [DIFF_FILE_OLD_MOVED_DIM]     = "oldMovedDimmed",
        [DIFF_FILE_OLD_MOVED_ALT_DIM] = "oldMovedAlternativeDimmed",
        [DIFF_FILE_NEW_MOVED]         = "newMoved",
        [DIFF_FILE_NEW_MOVED_ALT]     = "newMovedAlternative",
        [DIFF_FILE_NEW_MOVED_DIM]     = "newMovedDimmed",
        [DIFF_FILE_NEW_MOVED_ALT_DIM] = "newMovedAlternativeDimmed",
        [DIFF_CONTEXT_DIM]            = "contextDimmed",
        [DIFF_FILE_OLD_DIM]           = "oldDimmed",
        [DIFF_FILE_NEW_DIM]           = "newDimmed",
        [DIFF_CONTEXT_BOLD]           = "contextBold",
        [DIFF_FILE_OLD_BOLD]          = "oldBold",
        [DIFF_FILE_NEW_BOLD]          = "newBold",
};

define_list_config_array_extra(color_diff_slots, {"plain"});

static int parse_diff_color_slot(const char *var)
{
        if (!strcasecmp(var, "plain"))
                return DIFF_CONTEXT;
        return LOOKUP_CONFIG(color_diff_slots, var);
}

static int parse_dirstat_params(struct diff_options *options, const char *params_string,
                                struct strbuf *errmsg)
{
        char *params_copy = xstrdup(params_string);
        struct string_list params = STRING_LIST_INIT_NODUP;
        int ret = 0;
        int i;

        if (*params_copy)
                string_list_split_in_place(&params, params_copy, ',', -1);
        for (i = 0; i < params.nr; i++) {
                const char *p = params.items[i].string;
                if (!strcmp(p, "changes")) {
                        options->flags.dirstat_by_line = 0;
                        options->flags.dirstat_by_file = 0;
                } else if (!strcmp(p, "lines")) {
                        options->flags.dirstat_by_line = 1;
                        options->flags.dirstat_by_file = 0;
                } else if (!strcmp(p, "files")) {
                        options->flags.dirstat_by_line = 0;
                        options->flags.dirstat_by_file = 1;
                } else if (!strcmp(p, "noncumulative")) {
                        options->flags.dirstat_cumulative = 0;
                } else if (!strcmp(p, "cumulative")) {
                        options->flags.dirstat_cumulative = 1;
                } else if (isdigit(*p)) {
                        char *end;
                        int permille = strtoul(p, &end, 10) * 10;
                        if (*end == '.' && isdigit(*++end)) {
                                /* only use first digit */
                                permille += *end - '0';
                                /* .. and ignore any further digits */
                                while (isdigit(*++end))
                                        ; /* nothing */
                        }
                        if (!*end)
                                options->dirstat_permille = permille;
                        else {
                                strbuf_addf(errmsg, _("  Failed to parse dirstat cut-off percentage '%s'\n"),
                                            p);
                                ret++;
                        }
                } else {
                        strbuf_addf(errmsg, _("  Unknown dirstat parameter '%s'\n"), p);
                        ret++;
                }

        }
        string_list_clear(&params, 0);
        free(params_copy);
        return ret;
}

static int parse_submodule_params(struct diff_options *options, const char *value)
{
        if (!strcmp(value, "log"))
                options->submodule_format = DIFF_SUBMODULE_LOG;
        else if (!strcmp(value, "short"))
                options->submodule_format = DIFF_SUBMODULE_SHORT;
        else if (!strcmp(value, "diff"))
                options->submodule_format = DIFF_SUBMODULE_INLINE_DIFF;
        /*
         * Please update $__git_diff_submodule_formats in
         * git-completion.bash when you add new formats.
         */
        else
                return -1;
        return 0;
}

int git_config_rename(const char *var, const char *value)
{
        if (!value)
                return DIFF_DETECT_RENAME;
        if (!strcasecmp(value, "copies") || !strcasecmp(value, "copy"))
                return  DIFF_DETECT_COPY;
        return git_config_bool(var,value) ? DIFF_DETECT_RENAME : 0;
}

long parse_algorithm_value(const char *value)
{
        if (!value)
                return -1;
        else if (!strcasecmp(value, "myers") || !strcasecmp(value, "default"))
                return 0;
        else if (!strcasecmp(value, "minimal"))
                return XDF_NEED_MINIMAL;
        else if (!strcasecmp(value, "patience"))
                return XDF_PATIENCE_DIFF;
        else if (!strcasecmp(value, "histogram"))
                return XDF_HISTOGRAM_DIFF;
        /*
         * Please update $__git_diff_algorithms in git-completion.bash
         * when you add new algorithms.
         */
        return -1;
}

static int parse_one_token(const char **arg, const char *token)
{
        const char *rest;
        if (skip_prefix(*arg, token, &rest) && (!*rest || *rest == ',')) {
                *arg = rest;
                return 1;
        }
        return 0;
}

static int parse_ws_error_highlight(const char *arg)
{
        const char *orig_arg = arg;
        unsigned val = 0;

        while (*arg) {
                if (parse_one_token(&arg, "none"))
                        val = 0;
                else if (parse_one_token(&arg, "default"))
                        val = WSEH_NEW;
                else if (parse_one_token(&arg, "all"))
                        val = WSEH_NEW | WSEH_OLD | WSEH_CONTEXT;
                else if (parse_one_token(&arg, "new"))
                        val |= WSEH_NEW;
                else if (parse_one_token(&arg, "old"))
                        val |= WSEH_OLD;
                else if (parse_one_token(&arg, "context"))
                        val |= WSEH_CONTEXT;
                else {
                        return -1 - (int)(arg - orig_arg);
                }
                if (*arg)
                        arg++;
        }
        return val;
}

/*
 * These are to give UI layer defaults.
 * The core-level commands such as git-diff-files should
 * never be affected by the setting of diff.renames
 * the user happens to have in the configuration file.
 */
void init_diff_ui_defaults(void)
{
        diff_detect_rename_default = DIFF_DETECT_RENAME;
}

int git_diff_heuristic_config(const char *var, const char *value, void *cb)
{
        if (!strcmp(var, "diff.indentheuristic"))
                diff_indent_heuristic = git_config_bool(var, value);
        return 0;
}

static int parse_color_moved(const char *arg)
{
        switch (git_parse_maybe_bool(arg)) {
        case 0:
                return COLOR_MOVED_NO;
        case 1:
                return COLOR_MOVED_DEFAULT;
        default:
                break;
        }

        if (!strcmp(arg, "no"))
                return COLOR_MOVED_NO;
        else if (!strcmp(arg, "plain"))
                return COLOR_MOVED_PLAIN;
        else if (!strcmp(arg, "blocks"))
                return COLOR_MOVED_BLOCKS;
        else if (!strcmp(arg, "zebra"))
                return COLOR_MOVED_ZEBRA;
        else if (!strcmp(arg, "default"))
                return COLOR_MOVED_DEFAULT;
        else if (!strcmp(arg, "dimmed-zebra"))
                return COLOR_MOVED_ZEBRA_DIM;
        else if (!strcmp(arg, "dimmed_zebra"))
                return COLOR_MOVED_ZEBRA_DIM;
        else
                return error(_("color moved setting must be one of 'no', 'default', 'blocks', 'zebra', 'dimmed-zebra', 'plain'"));
}

static unsigned parse_color_moved_ws(const char *arg)
{
        int ret = 0;
        struct string_list l = STRING_LIST_INIT_DUP;
        struct string_list_item *i;

        string_list_split(&l, arg, ',', -1);

        for_each_string_list_item(i, &l) {
                struct strbuf sb = STRBUF_INIT;
                strbuf_addstr(&sb, i->string);
                strbuf_trim(&sb);

                if (!strcmp(sb.buf, "no"))
                        ret = 0;
                else if (!strcmp(sb.buf, "ignore-space-change"))
                        ret |= XDF_IGNORE_WHITESPACE_CHANGE;
                else if (!strcmp(sb.buf, "ignore-space-at-eol"))
                        ret |= XDF_IGNORE_WHITESPACE_AT_EOL;
                else if (!strcmp(sb.buf, "ignore-all-space"))
                        ret |= XDF_IGNORE_WHITESPACE;
                else if (!strcmp(sb.buf, "allow-indentation-change"))
                        ret |= COLOR_MOVED_WS_ALLOW_INDENTATION_CHANGE;
                else {
                        ret |= COLOR_MOVED_WS_ERROR;
                        error(_("unknown color-moved-ws mode '%s', possible values are 'ignore-space-change', 'ignore-space-at-eol', 'ignore-all-space', 'allow-indentation-change'"), sb.buf);
                }

                strbuf_release(&sb);
        }

        if ((ret & COLOR_MOVED_WS_ALLOW_INDENTATION_CHANGE) &&
            (ret & XDF_WHITESPACE_FLAGS)) {
                error(_("color-moved-ws: allow-indentation-change cannot be combined with other whitespace modes"));
                ret |= COLOR_MOVED_WS_ERROR;
        }

        string_list_clear(&l, 0);

        return ret;
}

int git_diff_ui_config(const char *var, const char *value, void *cb)
{
        if (!strcmp(var, "diff.color") || !strcmp(var, "color.diff")) {
                diff_use_color_default = git_config_colorbool(var, value);
                return 0;
        }
        if (!strcmp(var, "diff.colormoved")) {
                int cm = parse_color_moved(value);
                if (cm < 0)
                        return -1;
                diff_color_moved_default = cm;
                return 0;
        }
        if (!strcmp(var, "diff.colormovedws")) {
                unsigned cm = parse_color_moved_ws(value);
                if (cm & COLOR_MOVED_WS_ERROR)
                        return -1;
                diff_color_moved_ws_default = cm;
                return 0;
        }
        if (!strcmp(var, "diff.context")) {
                diff_context_default = git_config_int(var, value);
                if (diff_context_default < 0)
                        return -1;
                return 0;
        }
        if (!strcmp(var, "diff.interhunkcontext")) {
                diff_interhunk_context_default = git_config_int(var, value);
                if (diff_interhunk_context_default < 0)
                        return -1;
                return 0;
        }
        if (!strcmp(var, "diff.renames")) {
                diff_detect_rename_default = git_config_rename(var, value);
                return 0;
        }
        if (!strcmp(var, "diff.autorefreshindex")) {
                diff_auto_refresh_index = git_config_bool(var, value);
                return 0;
        }
        if (!strcmp(var, "diff.mnemonicprefix")) {
                diff_mnemonic_prefix = git_config_bool(var, value);
                return 0;
        }
        if (!strcmp(var, "diff.noprefix")) {
                diff_no_prefix = git_config_bool(var, value);
                return 0;
        }
        if (!strcmp(var, "diff.statgraphwidth")) {
                diff_stat_graph_width = git_config_int(var, value);
                return 0;
        }
        if (!strcmp(var, "diff.external"))
                return git_config_string(&external_diff_cmd_cfg, var, value);
        if (!strcmp(var, "diff.wordregex"))
                return git_config_string(&diff_word_regex_cfg, var, value);
        if (!strcmp(var, "diff.orderfile"))
                return git_config_pathname(&diff_order_file_cfg, var, value);

        if (!strcmp(var, "diff.ignoresubmodules"))
                handle_ignore_submodules_arg(&default_diff_options, value);

        if (!strcmp(var, "diff.submodule")) {
                if (parse_submodule_params(&default_diff_options, value))
                        warning(_("Unknown value for 'diff.submodule' config variable: '%s'"),
                                value);
                return 0;
        }

        if (!strcmp(var, "diff.algorithm")) {
                diff_algorithm = parse_algorithm_value(value);
                if (diff_algorithm < 0)
                        return -1;
                return 0;
        }

        if (!strcmp(var, "diff.wserrorhighlight")) {
                int val = parse_ws_error_highlight(value);
                if (val < 0)
                        return -1;
                ws_error_highlight_default = val;
                return 0;
        }

        if (git_color_config(var, value, cb) < 0)
                return -1;

        return git_diff_basic_config(var, value, cb);
}

int git_diff_basic_config(const char *var, const char *value, void *cb)
{
        const char *name;

        if (!strcmp(var, "diff.renamelimit")) {
                diff_rename_limit_default = git_config_int(var, value);
                return 0;
        }

        if (userdiff_config(var, value) < 0)
                return -1;

        if (skip_prefix(var, "diff.color.", &name) ||
            skip_prefix(var, "color.diff.", &name)) {
                int slot = parse_diff_color_slot(name);
                if (slot < 0)
                        return 0;
                if (!value)
                        return config_error_nonbool(var);
                return color_parse(value, diff_colors[slot]);
        }

        /* like GNU diff's --suppress-blank-empty option  */
        if (!strcmp(var, "diff.suppressblankempty") ||
                        /* for backwards compatibility */
                        !strcmp(var, "diff.suppress-blank-empty")) {
                diff_suppress_blank_empty = git_config_bool(var, value);
                return 0;
        }

        if (!strcmp(var, "diff.dirstat")) {
                struct strbuf errmsg = STRBUF_INIT;
                default_diff_options.dirstat_permille = diff_dirstat_permille_default;
                if (parse_dirstat_params(&default_diff_options, value, &errmsg))
                        warning(_("Found errors in 'diff.dirstat' config variable:\n%s"),
                                errmsg.buf);
                strbuf_release(&errmsg);
                diff_dirstat_permille_default = default_diff_options.dirstat_permille;
                return 0;
        }

        if (git_diff_heuristic_config(var, value, cb) < 0)
                return -1;

        return git_default_config(var, value, cb);
}

static char *quote_two(const char *one, const char *two)
{
        int need_one = quote_c_style(one, NULL, NULL, 1);
        int need_two = quote_c_style(two, NULL, NULL, 1);
        struct strbuf res = STRBUF_INIT;

        if (need_one + need_two) {
                strbuf_addch(&res, '"');
                quote_c_style(one, &res, NULL, 1);
                quote_c_style(two, &res, NULL, 1);
                strbuf_addch(&res, '"');
        } else {
                strbuf_addstr(&res, one);
                strbuf_addstr(&res, two);
        }
        return strbuf_detach(&res, NULL);
}

static const char *external_diff(void)
{
        static const char *external_diff_cmd = NULL;
        static int done_preparing = 0;

        if (done_preparing)
                return external_diff_cmd;
        external_diff_cmd = xstrdup_or_null(getenv("GIT_EXTERNAL_DIFF"));
        if (!external_diff_cmd)
                external_diff_cmd = external_diff_cmd_cfg;
        done_preparing = 1;
        return external_diff_cmd;
}

/*
 * Keep track of files used for diffing. Sometimes such an entry
 * refers to a temporary file, sometimes to an existing file, and
 * sometimes to "/dev/null".
 */
static struct diff_tempfile {
        /*
         * filename external diff should read from, or NULL if this
         * entry is currently not in use:
         */
        const char *name;

        char hex[GIT_MAX_HEXSZ + 1];
        char mode[10];

        /*
         * If this diff_tempfile instance refers to a temporary file,
         * this tempfile object is used to manage its lifetime.
         */
        struct tempfile *tempfile;
} diff_temp[2];

struct emit_callback {
        int color_diff;
        unsigned ws_rule;
        int blank_at_eof_in_preimage;
        int blank_at_eof_in_postimage;
        int lno_in_preimage;
        int lno_in_postimage;
        const char **label_path;
        struct diff_words_data *diff_words;
        struct diff_options *opt;
        struct strbuf *header;
};

static int count_lines(const char *data, int size)
{
        int count, ch, completely_empty = 1, nl_just_seen = 0;
        count = 0;
        while (0 < size--) {
                ch = *data++;
                if (ch == '\n') {
                        count++;
                        nl_just_seen = 1;
                        completely_empty = 0;
                }
                else {
                        nl_just_seen = 0;
                        completely_empty = 0;
                }
        }
        if (completely_empty)
                return 0;
        if (!nl_just_seen)
                count++; /* no trailing newline */
        return count;
}

static int fill_mmfile(struct repository *r, mmfile_t *mf,
                       struct diff_filespec *one)
{
        if (!DIFF_FILE_VALID(one)) {
                mf->ptr = (char *)""; /* does not matter */
                mf->size = 0;
                return 0;
        }
        else if (diff_populate_filespec(r, one, 0))
                return -1;

        mf->ptr = one->data;
        mf->size = one->size;
        return 0;
}

/* like fill_mmfile, but only for size, so we can avoid retrieving blob */
static unsigned long diff_filespec_size(struct repository *r,
                                        struct diff_filespec *one)
{
        if (!DIFF_FILE_VALID(one))
                return 0;
        diff_populate_filespec(r, one, CHECK_SIZE_ONLY);
        return one->size;
}

static int count_trailing_blank(mmfile_t *mf, unsigned ws_rule)
{
        char *ptr = mf->ptr;
        long size = mf->size;
        int cnt = 0;

        if (!size)
                return cnt;
        ptr += size - 1; /* pointing at the very end */
        if (*ptr != '\n')
                ; /* incomplete line */
        else
                ptr--; /* skip the last LF */
        while (mf->ptr < ptr) {
                char *prev_eol;
                for (prev_eol = ptr; mf->ptr <= prev_eol; prev_eol--)
                        if (*prev_eol == '\n')
                                break;
                if (!ws_blank_line(prev_eol + 1, ptr - prev_eol, ws_rule))
                        break;
                cnt++;
                ptr = prev_eol - 1;
        }
        return cnt;
}

static void check_blank_at_eof(mmfile_t *mf1, mmfile_t *mf2,
                               struct emit_callback *ecbdata)
{
        int l1, l2, at;
        unsigned ws_rule = ecbdata->ws_rule;
        l1 = count_trailing_blank(mf1, ws_rule);
        l2 = count_trailing_blank(mf2, ws_rule);
        if (l2 <= l1) {
                ecbdata->blank_at_eof_in_preimage = 0;
                ecbdata->blank_at_eof_in_postimage = 0;
                return;
        }
        at = count_lines(mf1->ptr, mf1->size);
        ecbdata->blank_at_eof_in_preimage = (at - l1) + 1;

        at = count_lines(mf2->ptr, mf2->size);
        ecbdata->blank_at_eof_in_postimage = (at - l2) + 1;
}

static void emit_line_0(struct diff_options *o,
                        const char *set_sign, const char *set, unsigned reverse, const char *reset,
                        int first, const char *line, int len)
{
        int has_trailing_newline, has_trailing_carriage_return;
        int needs_reset = 0; /* at the end of the line */
        FILE *file = o->file;

        fputs(diff_line_prefix(o), file);

        has_trailing_newline = (len > 0 && line[len-1] == '\n');
        if (has_trailing_newline)
                len--;

        has_trailing_carriage_return = (len > 0 && line[len-1] == '\r');
        if (has_trailing_carriage_return)
                len--;

        if (!len && !first)
                goto end_of_line;

        if (reverse && want_color(o->use_color)) {
                fputs(GIT_COLOR_REVERSE, file);
                needs_reset = 1;
        }

        if (set_sign) {
                fputs(set_sign, file);
                needs_reset = 1;
        }

        if (first)
                fputc(first, file);

        if (!len)
                goto end_of_line;

        if (set) {
                if (set_sign && set != set_sign)
                        fputs(reset, file);
                fputs(set, file);
                needs_reset = 1;
        }
        fwrite(line, len, 1, file);
        needs_reset = 1; /* 'line' may contain color codes. */

end_of_line:
        if (needs_reset)
                fputs(reset, file);
        if (has_trailing_carriage_return)
                fputc('\r', file);
        if (has_trailing_newline)
                fputc('\n', file);
}

static void emit_line(struct diff_options *o, const char *set, const char *reset,
                      const char *line, int len)
{
        emit_line_0(o, set, NULL, 0, reset, 0, line, len);
}

enum diff_symbol {
        DIFF_SYMBOL_BINARY_DIFF_HEADER,
        DIFF_SYMBOL_BINARY_DIFF_HEADER_DELTA,
        DIFF_SYMBOL_BINARY_DIFF_HEADER_LITERAL,
        DIFF_SYMBOL_BINARY_DIFF_BODY,
        DIFF_SYMBOL_BINARY_DIFF_FOOTER,
        DIFF_SYMBOL_STATS_SUMMARY_NO_FILES,
        DIFF_SYMBOL_STATS_SUMMARY_ABBREV,
        DIFF_SYMBOL_STATS_SUMMARY_INSERTS_DELETES,
        DIFF_SYMBOL_STATS_LINE,
        DIFF_SYMBOL_WORD_DIFF,
        DIFF_SYMBOL_STAT_SEP,
        DIFF_SYMBOL_SUMMARY,
        DIFF_SYMBOL_SUBMODULE_ADD,
        DIFF_SYMBOL_SUBMODULE_DEL,
        DIFF_SYMBOL_SUBMODULE_UNTRACKED,
        DIFF_SYMBOL_SUBMODULE_MODIFIED,
        DIFF_SYMBOL_SUBMODULE_HEADER,
        DIFF_SYMBOL_SUBMODULE_ERROR,
        DIFF_SYMBOL_SUBMODULE_PIPETHROUGH,
        DIFF_SYMBOL_REWRITE_DIFF,
        DIFF_SYMBOL_BINARY_FILES,
        DIFF_SYMBOL_HEADER,
        DIFF_SYMBOL_FILEPAIR_PLUS,
        DIFF_SYMBOL_FILEPAIR_MINUS,
        DIFF_SYMBOL_WORDS_PORCELAIN,
        DIFF_SYMBOL_WORDS,
        DIFF_SYMBOL_CONTEXT,
        DIFF_SYMBOL_CONTEXT_INCOMPLETE,
        DIFF_SYMBOL_PLUS,
        DIFF_SYMBOL_MINUS,
        DIFF_SYMBOL_NO_LF_EOF,
        DIFF_SYMBOL_CONTEXT_FRAGINFO,
        DIFF_SYMBOL_CONTEXT_MARKER,
        DIFF_SYMBOL_SEPARATOR
};
/*
 * Flags for content lines:
 * 0..12 are whitespace rules
 * 13-15 are WSEH_NEW | WSEH_OLD | WSEH_CONTEXT
 * 16 is marking if the line is blank at EOF
 */
#define DIFF_SYMBOL_CONTENT_BLANK_LINE_EOF      (1<<16)
#define DIFF_SYMBOL_MOVED_LINE                  (1<<17)
#define DIFF_SYMBOL_MOVED_LINE_ALT              (1<<18)
#define DIFF_SYMBOL_MOVED_LINE_UNINTERESTING    (1<<19)
#define DIFF_SYMBOL_CONTENT_WS_MASK (WSEH_NEW | WSEH_OLD | WSEH_CONTEXT | WS_RULE_MASK)

/*
 * This struct is used when we need to buffer the output of the diff output.
 *
 * NEEDSWORK: Instead of storing a copy of the line, add an offset pointer
 * into the pre/post image file. This pointer could be a union with the
 * line pointer. By storing an offset into the file instead of the literal line,
 * we can decrease the memory footprint for the buffered output. At first we
 * may want to only have indirection for the content lines, but we could also
 * enhance the state for emitting prefabricated lines, e.g. the similarity
 * score line or hunk/file headers would only need to store a number or path
 * and then the output can be constructed later on depending on state.
 */
struct emitted_diff_symbol {
        const char *line;
        int len;
        int flags;
        int indent_off;   /* Offset to first non-whitespace character */
        int indent_width; /* The visual width of the indentation */
        enum diff_symbol s;
};
#define EMITTED_DIFF_SYMBOL_INIT {NULL}

struct emitted_diff_symbols {
        struct emitted_diff_symbol *buf;
        int nr, alloc;
};
#define EMITTED_DIFF_SYMBOLS_INIT {NULL, 0, 0}

static void append_emitted_diff_symbol(struct diff_options *o,
                                       struct emitted_diff_symbol *e)
{
        struct emitted_diff_symbol *f;

        ALLOC_GROW(o->emitted_symbols->buf,
                   o->emitted_symbols->nr + 1,
                   o->emitted_symbols->alloc);
        f = &o->emitted_symbols->buf[o->emitted_symbols->nr++];

        memcpy(f, e, sizeof(struct emitted_diff_symbol));
        f->line = e->line ? xmemdupz(e->line, e->len) : NULL;
}

struct moved_entry {
        struct hashmap_entry ent;
        const struct emitted_diff_symbol *es;
        struct moved_entry *next_line;
};

struct moved_block {
        struct moved_entry *match;
        int wsd; /* The whitespace delta of this block */
};

static void moved_block_clear(struct moved_block *b)
{
        memset(b, 0, sizeof(*b));
}

#define INDENT_BLANKLINE INT_MIN

static void fill_es_indent_data(struct emitted_diff_symbol *es)
{
        unsigned int off = 0, i;
        int width = 0, tab_width = es->flags & WS_TAB_WIDTH_MASK;
        const char *s = es->line;
        const int len = es->len;

        /* skip any \v \f \r at start of indentation */
        while (s[off] == '\f' || s[off] == '\v' ||
               (s[off] == '\r' && off < len - 1))
                off++;

        /* calculate the visual width of indentation */
        while(1) {
                if (s[off] == ' ') {
                        width++;
                        off++;
                } else if (s[off] == '\t') {
                        width += tab_width - (width % tab_width);
                        while (s[++off] == '\t')
                                width += tab_width;
                } else {
                        break;
                }
        }

        /* check if this line is blank */
        for (i = off; i < len; i++)
                if (!isspace(s[i]))
                    break;

        if (i == len) {
                es->indent_width = INDENT_BLANKLINE;
                es->indent_off = len;
        } else {
                es->indent_off = off;
                es->indent_width = width;
        }
}

static int compute_ws_delta(const struct emitted_diff_symbol *a,
                            const struct emitted_diff_symbol *b,
                            int *out)
{
        int a_len = a->len,
            b_len = b->len,
            a_off = a->indent_off,
            a_width = a->indent_width,
            b_off = b->indent_off,
            b_width = b->indent_width;
        int delta;

        if (a_width == INDENT_BLANKLINE && b_width == INDENT_BLANKLINE) {
                *out = INDENT_BLANKLINE;
                return 1;
        }

        if (a->s == DIFF_SYMBOL_PLUS)
                delta = a_width - b_width;
        else
                delta = b_width - a_width;

        if (a_len - a_off != b_len - b_off ||
            memcmp(a->line + a_off, b->line + b_off, a_len - a_off))
                return 0;

        *out = delta;

        return 1;
}

static int cmp_in_block_with_wsd(const struct diff_options *o,
                                 const struct moved_entry *cur,
                                 const struct moved_entry *match,
                                 struct moved_block *pmb,
                                 int n)
{
        struct emitted_diff_symbol *l = &o->emitted_symbols->buf[n];
        int al = cur->es->len, bl = match->es->len, cl = l->len;
        const char *a = cur->es->line,
                   *b = match->es->line,
                   *c = l->line;
        int a_off = cur->es->indent_off,
            a_width = cur->es->indent_width,
            c_off = l->indent_off,
            c_width = l->indent_width;
        int delta;

        /*
         * We need to check if 'cur' is equal to 'match'.  As those
         * are from the same (+/-) side, we do not need to adjust for
         * indent changes. However these were found using fuzzy
         * matching so we do have to check if they are equal. Here we
         * just check the lengths. We delay calling memcmp() to check
         * the contents until later as if the length comparison for a
         * and c fails we can avoid the call all together.
         */
        if (al != bl)
                return 1;

        /* If 'l' and 'cur' are both blank then they match. */
        if (a_width == INDENT_BLANKLINE && c_width == INDENT_BLANKLINE)
                return 0;

        /*
         * The indent changes of the block are known and stored in pmb->wsd;
         * however we need to check if the indent changes of the current line
         * match those of the current block and that the text of 'l' and 'cur'
         * after the indentation match.
         */
        if (cur->es->s == DIFF_SYMBOL_PLUS)
                delta = a_width - c_width;
        else
                delta = c_width - a_width;

        /*
         * If the previous lines of this block were all blank then set its
         * whitespace delta.
         */
        if (pmb->wsd == INDENT_BLANKLINE)
                pmb->wsd = delta;

        return !(delta == pmb->wsd && al - a_off == cl - c_off &&
                 !memcmp(a, b, al) && !
                 memcmp(a + a_off, c + c_off, al - a_off));
}

static int moved_entry_cmp(const void *hashmap_cmp_fn_data,
                           const struct hashmap_entry *eptr,
                           const struct hashmap_entry *entry_or_key,
                           const void *keydata)
{
        const struct diff_options *diffopt = hashmap_cmp_fn_data;
        const struct moved_entry *a, *b;
        unsigned flags = diffopt->color_moved_ws_handling
                         & XDF_WHITESPACE_FLAGS;

        a = container_of(eptr, const struct moved_entry, ent);
        b = container_of(entry_or_key, const struct moved_entry, ent);

        if (diffopt->color_moved_ws_handling &
            COLOR_MOVED_WS_ALLOW_INDENTATION_CHANGE)
                /*
                 * As there is not specific white space config given,
                 * we'd need to check for a new block, so ignore all
                 * white space. The setup of the white space
                 * configuration for the next block is done else where
                 */
                flags |= XDF_IGNORE_WHITESPACE;

        return !xdiff_compare_lines(a->es->line, a->es->len,
                                    b->es->line, b->es->len,
                                    flags);
}

static struct moved_entry *prepare_entry(struct diff_options *o,
                                         int line_no)
{
        struct moved_entry *ret = xmalloc(sizeof(*ret));
        struct emitted_diff_symbol *l = &o->emitted_symbols->buf[line_no];
        unsigned flags = o->color_moved_ws_handling & XDF_WHITESPACE_FLAGS;
        unsigned int hash = xdiff_hash_string(l->line, l->len, flags);

        hashmap_entry_init(&ret->ent, hash);
        ret->es = l;
        ret->next_line = NULL;

        return ret;
}

static void add_lines_to_move_detection(struct diff_options *o,
                                        struct hashmap *add_lines,
                                        struct hashmap *del_lines)
{
        struct moved_entry *prev_line = NULL;

        int n;
        for (n = 0; n < o->emitted_symbols->nr; n++) {
                struct hashmap *hm;
                struct moved_entry *key;

                switch (o->emitted_symbols->buf[n].s) {
                case DIFF_SYMBOL_PLUS:
                        hm = add_lines;
                        break;
                case DIFF_SYMBOL_MINUS:
                        hm = del_lines;
                        break;
                default:
                        prev_line = NULL;
                        continue;
                }

                if (o->color_moved_ws_handling &
                    COLOR_MOVED_WS_ALLOW_INDENTATION_CHANGE)
                        fill_es_indent_data(&o->emitted_symbols->buf[n]);
                key = prepare_entry(o, n);
                if (prev_line && prev_line->es->s == o->emitted_symbols->buf[n].s)
                        prev_line->next_line = key;

                hashmap_add(hm, &key->ent);
                prev_line = key;
        }
}

static void pmb_advance_or_null(struct diff_options *o,
                                struct moved_entry *match,
                                struct hashmap *hm,
                                struct moved_block *pmb,
                                int pmb_nr)
{
        int i;
        for (i = 0; i < pmb_nr; i++) {
                struct moved_entry *prev = pmb[i].match;
                struct moved_entry *cur = (prev && prev->next_line) ?
                                prev->next_line : NULL;
                if (cur && !hm->cmpfn(o, &cur->ent, &match->ent, NULL)) {
                        pmb[i].match = cur;
                } else {
                        pmb[i].match = NULL;
                }
        }
}

static void pmb_advance_or_null_multi_match(struct diff_options *o,
                                            struct moved_entry *match,
                                            struct hashmap *hm,
                                            struct moved_block *pmb,
                                            int pmb_nr, int n)
{
        int i;
        char *got_match = xcalloc(1, pmb_nr);

        hashmap_for_each_entry_from(hm, match, ent) {
                for (i = 0; i < pmb_nr; i++) {
                        struct moved_entry *prev = pmb[i].match;
                        struct moved_entry *cur = (prev && prev->next_line) ?
                                        prev->next_line : NULL;
                        if (!cur)
                                continue;
                        if (!cmp_in_block_with_wsd(o, cur, match, &pmb[i], n))
                                got_match[i] |= 1;
                }
        }

        for (i = 0; i < pmb_nr; i++) {
                if (got_match[i]) {
                        /* Advance to the next line */
                        pmb[i].match = pmb[i].match->next_line;
                } else {
                        moved_block_clear(&pmb[i]);
                }
        }

        free(got_match);
}

static int shrink_potential_moved_blocks(struct moved_block *pmb,
                                         int pmb_nr)
{
        int lp, rp;

        /* Shrink the set of potential block to the remaining running */
        for (lp = 0, rp = pmb_nr - 1; lp <= rp;) {
                while (lp < pmb_nr && pmb[lp].match)
                        lp++;
                /* lp points at the first NULL now */

                while (rp > -1 && !pmb[rp].match)
                        rp--;
                /* rp points at the last non-NULL */

                if (lp < pmb_nr && rp > -1 && lp < rp) {
                        pmb[lp] = pmb[rp];
                        memset(&pmb[rp], 0, sizeof(pmb[rp]));
                        rp--;
                        lp++;
                }
        }

        /* Remember the number of running sets */
        return rp + 1;
}

/*
 * If o->color_moved is COLOR_MOVED_PLAIN, this function does nothing.
 *
 * Otherwise, if the last block has fewer alphanumeric characters than
 * COLOR_MOVED_MIN_ALNUM_COUNT, unset DIFF_SYMBOL_MOVED_LINE on all lines in
 * that block.
 *
 * The last block consists of the (n - block_length)'th line up to but not
 * including the nth line.
 *
 * Returns 0 if the last block is empty or is unset by this function, non zero
 * otherwise.
 *
 * NEEDSWORK: This uses the same heuristic as blame_entry_score() in blame.c.
 * Think of a way to unify them.
 */
static int adjust_last_block(struct diff_options *o, int n, int block_length)
{
        int i, alnum_count = 0;
        if (o->color_moved == COLOR_MOVED_PLAIN)
                return block_length;
        for (i = 1; i < block_length + 1; i++) {
                const char *c = o->emitted_symbols->buf[n - i].line;
                for (; *c; c++) {
                        if (!isalnum(*c))
                                continue;
                        alnum_count++;
                        if (alnum_count >= COLOR_MOVED_MIN_ALNUM_COUNT)
                                return 1;
                }
        }
        for (i = 1; i < block_length + 1; i++)
                o->emitted_symbols->buf[n - i].flags &= ~DIFF_SYMBOL_MOVED_LINE;
        return 0;
}

/* Find blocks of moved code, delegate actual coloring decision to helper */
static void mark_color_as_moved(struct diff_options *o,
                                struct hashmap *add_lines,
                                struct hashmap *del_lines)
{
        struct moved_block *pmb = NULL; /* potentially moved blocks */
        int pmb_nr = 0, pmb_alloc = 0;
        int n, flipped_block = 0, block_length = 0;


        for (n = 0; n < o->emitted_symbols->nr; n++) {
                struct hashmap *hm = NULL;
                struct moved_entry *key;
                struct moved_entry *match = NULL;
                struct emitted_diff_symbol *l = &o->emitted_symbols->buf[n];
                enum diff_symbol last_symbol = 0;

                switch (l->s) {
                case DIFF_SYMBOL_PLUS:
                        hm = del_lines;
                        key = prepare_entry(o, n);
                        match = hashmap_get_entry(hm, key, ent, NULL);
                        free(key);
                        break;
                case DIFF_SYMBOL_MINUS:
                        hm = add_lines;
                        key = prepare_entry(o, n);
                        match = hashmap_get_entry(hm, key, ent, NULL);
                        free(key);
                        break;
                default:
                        flipped_block = 0;
                }

                if (!match) {
                        int i;

                        adjust_last_block(o, n, block_length);
                        for(i = 0; i < pmb_nr; i++)
                                moved_block_clear(&pmb[i]);
                        pmb_nr = 0;
                        block_length = 0;
                        flipped_block = 0;
                        last_symbol = l->s;
                        continue;
                }

                if (o->color_moved == COLOR_MOVED_PLAIN) {
                        last_symbol = l->s;
                        l->flags |= DIFF_SYMBOL_MOVED_LINE;
                        continue;
                }

                if (o->color_moved_ws_handling &
                    COLOR_MOVED_WS_ALLOW_INDENTATION_CHANGE)
                        pmb_advance_or_null_multi_match(o, match, hm, pmb, pmb_nr, n);
                else
                        pmb_advance_or_null(o, match, hm, pmb, pmb_nr);

                pmb_nr = shrink_potential_moved_blocks(pmb, pmb_nr);

                if (pmb_nr == 0) {
                        /*
                         * The current line is the start of a new block.
                         * Setup the set of potential blocks.
                         */
                        hashmap_for_each_entry_from(hm, match, ent) {
                                ALLOC_GROW(pmb, pmb_nr + 1, pmb_alloc);
                                if (o->color_moved_ws_handling &
                                    COLOR_MOVED_WS_ALLOW_INDENTATION_CHANGE) {
                                        if (compute_ws_delta(l, match->es,
                                                             &pmb[pmb_nr].wsd))
                                                pmb[pmb_nr++].match = match;
                                } else {
                                        pmb[pmb_nr].wsd = 0;
                                        pmb[pmb_nr++].match = match;
                                }
                        }

                        if (adjust_last_block(o, n, block_length) &&
                            pmb_nr && last_symbol != l->s)
                                flipped_block = (flipped_block + 1) % 2;
                        else
                                flipped_block = 0;

                        block_length = 0;
                }

                if (pmb_nr) {
                        block_length++;
                        l->flags |= DIFF_SYMBOL_MOVED_LINE;
                        if (flipped_block && o->color_moved != COLOR_MOVED_BLOCKS)
                                l->flags |= DIFF_SYMBOL_MOVED_LINE_ALT;
                }
                last_symbol = l->s;
        }
        adjust_last_block(o, n, block_length);

        for(n = 0; n < pmb_nr; n++)
                moved_block_clear(&pmb[n]);
        free(pmb);
}

#define DIFF_SYMBOL_MOVED_LINE_ZEBRA_MASK \
  (DIFF_SYMBOL_MOVED_LINE | DIFF_SYMBOL_MOVED_LINE_ALT)
static void dim_moved_lines(struct diff_options *o)
{
        int n;
        for (n = 0; n < o->emitted_symbols->nr; n++) {
                struct emitted_diff_symbol *prev = (n != 0) ?
                                &o->emitted_symbols->buf[n - 1] : NULL;
                struct emitted_diff_symbol *l = &o->emitted_symbols->buf[n];
                struct emitted_diff_symbol *next =
                                (n < o->emitted_symbols->nr - 1) ?
                                &o->emitted_symbols->buf[n + 1] : NULL;

                /* Not a plus or minus line? */
                if (l->s != DIFF_SYMBOL_PLUS && l->s != DIFF_SYMBOL_MINUS)
                        continue;

                /* Not a moved line? */
                if (!(l->flags & DIFF_SYMBOL_MOVED_LINE))
                        continue;

                /*
                 * If prev or next are not a plus or minus line,
                 * pretend they don't exist
                 */
                if (prev && prev->s != DIFF_SYMBOL_PLUS &&
                            prev->s != DIFF_SYMBOL_MINUS)
                        prev = NULL;
                if (next && next->s != DIFF_SYMBOL_PLUS &&
                            next->s != DIFF_SYMBOL_MINUS)
                        next = NULL;

                /* Inside a block? */
                if ((prev &&
                    (prev->flags & DIFF_SYMBOL_MOVED_LINE_ZEBRA_MASK) ==
                    (l->flags & DIFF_SYMBOL_MOVED_LINE_ZEBRA_MASK)) &&
                    (next &&
                    (next->flags & DIFF_SYMBOL_MOVED_LINE_ZEBRA_MASK) ==
                    (l->flags & DIFF_SYMBOL_MOVED_LINE_ZEBRA_MASK))) {
                        l->flags |= DIFF_SYMBOL_MOVED_LINE_UNINTERESTING;
                        continue;
                }

                /* Check if we are at an interesting bound: */
                if (prev && (prev->flags & DIFF_SYMBOL_MOVED_LINE) &&
                    (prev->flags & DIFF_SYMBOL_MOVED_LINE_ALT) !=
                       (l->flags & DIFF_SYMBOL_MOVED_LINE_ALT))
                        continue;
                if (next && (next->flags & DIFF_SYMBOL_MOVED_LINE) &&
                    (next->flags & DIFF_SYMBOL_MOVED_LINE_ALT) !=
                       (l->flags & DIFF_SYMBOL_MOVED_LINE_ALT))
                        continue;

                /*
                 * The boundary to prev and next are not interesting,
                 * so this line is not interesting as a whole
                 */
                l->flags |= DIFF_SYMBOL_MOVED_LINE_UNINTERESTING;
        }
}

static void emit_line_ws_markup(struct diff_options *o,
                                const char *set_sign, const char *set,
                                const char *reset,
                                int sign_index, const char *line, int len,
                                unsigned ws_rule, int blank_at_eof)
{
        const char *ws = NULL;
        int sign = o->output_indicators[sign_index];

        if (o->ws_error_highlight & ws_rule) {
                ws = diff_get_color_opt(o, DIFF_WHITESPACE);
                if (!*ws)
                        ws = NULL;
        }

        if (!ws && !set_sign)
                emit_line_0(o, set, NULL, 0, reset, sign, line, len);
        else if (!ws) {
                emit_line_0(o, set_sign, set, !!set_sign, reset, sign, line, len);
        } else if (blank_at_eof)
                /* Blank line at EOF - paint '+' as well */
                emit_line_0(o, ws, NULL, 0, reset, sign, line, len);
        else {
                /* Emit just the prefix, then the rest. */
                emit_line_0(o, set_sign ? set_sign : set, NULL, !!set_sign, reset,
                            sign, "", 0);
                ws_check_emit(line, len, ws_rule,
                              o->file, set, reset, ws);
        }
}

static void emit_diff_symbol_from_struct(struct diff_options *o,
                                         struct emitted_diff_symbol *eds)
{
        static const char *nneof = " No newline at end of file\n";
        const char *context, *reset, *set, *set_sign, *meta, *fraginfo;
        struct strbuf sb = STRBUF_INIT;

        enum diff_symbol s = eds->s;
        const char *line = eds->line;
        int len = eds->len;
        unsigned flags = eds->flags;

        switch (s) {
        case DIFF_SYMBOL_NO_LF_EOF:
                context = diff_get_color_opt(o, DIFF_CONTEXT);
                reset = diff_get_color_opt(o, DIFF_RESET);
                putc('\n', o->file);
                emit_line_0(o, context, NULL, 0, reset, '\\',
                            nneof, strlen(nneof));
                break;
        case DIFF_SYMBOL_SUBMODULE_HEADER:
        case DIFF_SYMBOL_SUBMODULE_ERROR:
        case DIFF_SYMBOL_SUBMODULE_PIPETHROUGH:
        case DIFF_SYMBOL_STATS_SUMMARY_INSERTS_DELETES:
        case DIFF_SYMBOL_SUMMARY:
        case DIFF_SYMBOL_STATS_LINE:
        case DIFF_SYMBOL_BINARY_DIFF_BODY:
        case DIFF_SYMBOL_CONTEXT_FRAGINFO:
                emit_line(o, "", "", line, len);
                break;
        case DIFF_SYMBOL_CONTEXT_INCOMPLETE:
        case DIFF_SYMBOL_CONTEXT_MARKER:
                context = diff_get_color_opt(o, DIFF_CONTEXT);
                reset = diff_get_color_opt(o, DIFF_RESET);
                emit_line(o, context, reset, line, len);
                break;
        case DIFF_SYMBOL_SEPARATOR:
                fprintf(o->file, "%s%c",
                        diff_line_prefix(o),
                        o->line_termination);
                break;
        case DIFF_SYMBOL_CONTEXT:
                set = diff_get_color_opt(o, DIFF_CONTEXT);
                reset = diff_get_color_opt(o, DIFF_RESET);
                set_sign = NULL;
                if (o->flags.dual_color_diffed_diffs) {
                        char c = !len ? 0 : line[0];

                        if (c == '+')
                                set = diff_get_color_opt(o, DIFF_FILE_NEW);
                        else if (c == '@')
                                set = diff_get_color_opt(o, DIFF_FRAGINFO);
                        else if (c == '-')
                                set = diff_get_color_opt(o, DIFF_FILE_OLD);
                }
                emit_line_ws_markup(o, set_sign, set, reset,
                                    OUTPUT_INDICATOR_CONTEXT, line, len,
                                    flags & (DIFF_SYMBOL_CONTENT_WS_MASK), 0);
                break;
        case DIFF_SYMBOL_PLUS:
                switch (flags & (DIFF_SYMBOL_MOVED_LINE |
                                 DIFF_SYMBOL_MOVED_LINE_ALT |
                                 DIFF_SYMBOL_MOVED_LINE_UNINTERESTING)) {
                case DIFF_SYMBOL_MOVED_LINE |
                     DIFF_SYMBOL_MOVED_LINE_ALT |
                     DIFF_SYMBOL_MOVED_LINE_UNINTERESTING:
                        set = diff_get_color_opt(o, DIFF_FILE_NEW_MOVED_ALT_DIM);
                        break;
                case DIFF_SYMBOL_MOVED_LINE |
                     DIFF_SYMBOL_MOVED_LINE_ALT:
                        set = diff_get_color_opt(o, DIFF_FILE_NEW_MOVED_ALT);
                        break;
                case DIFF_SYMBOL_MOVED_LINE |
                     DIFF_SYMBOL_MOVED_LINE_UNINTERESTING:
                        set = diff_get_color_opt(o, DIFF_FILE_NEW_MOVED_DIM);
                        break;
                case DIFF_SYMBOL_MOVED_LINE:
                        set = diff_get_color_opt(o, DIFF_FILE_NEW_MOVED);
                        break;
                default:
                        set = diff_get_color_opt(o, DIFF_FILE_NEW);
                }
                reset = diff_get_color_opt(o, DIFF_RESET);
                if (!o->flags.dual_color_diffed_diffs)
                        set_sign = NULL;
                else {
                        char c = !len ? 0 : line[0];

                        set_sign = set;
                        if (c == '-')
                                set = diff_get_color_opt(o, DIFF_FILE_OLD_BOLD);
                        else if (c == '@')
                                set = diff_get_color_opt(o, DIFF_FRAGINFO);
                        else if (c == '+')
                                set = diff_get_color_opt(o, DIFF_FILE_NEW_BOLD);
                        else
                                set = diff_get_color_opt(o, DIFF_CONTEXT_BOLD);
                        flags &= ~DIFF_SYMBOL_CONTENT_WS_MASK;
                }
                emit_line_ws_markup(o, set_sign, set, reset,
                                    OUTPUT_INDICATOR_NEW, line, len,
                                    flags & DIFF_SYMBOL_CONTENT_WS_MASK,
                                    flags & DIFF_SYMBOL_CONTENT_BLANK_LINE_EOF);
                break;
        case DIFF_SYMBOL_MINUS:
                switch (flags & (DIFF_SYMBOL_MOVED_LINE |
                                 DIFF_SYMBOL_MOVED_LINE_ALT |
                                 DIFF_SYMBOL_MOVED_LINE_UNINTERESTING)) {
                case DIFF_SYMBOL_MOVED_LINE |
                     DIFF_SYMBOL_MOVED_LINE_ALT |
                     DIFF_SYMBOL_MOVED_LINE_UNINTERESTING:
                        set = diff_get_color_opt(o, DIFF_FILE_OLD_MOVED_ALT_DIM);
                        break;
                case DIFF_SYMBOL_MOVED_LINE |
                     DIFF_SYMBOL_MOVED_LINE_ALT:
                        set = diff_get_color_opt(o, DIFF_FILE_OLD_MOVED_ALT);
                        break;
                case DIFF_SYMBOL_MOVED_LINE |
                     DIFF_SYMBOL_MOVED_LINE_UNINTERESTING:
                        set = diff_get_color_opt(o, DIFF_FILE_OLD_MOVED_DIM);
                        break;
                case DIFF_SYMBOL_MOVED_LINE:
                        set = diff_get_color_opt(o, DIFF_FILE_OLD_MOVED);
                        break;
                default:
                        set = diff_get_color_opt(o, DIFF_FILE_OLD);
                }
                reset = diff_get_color_opt(o, DIFF_RESET);
                if (!o->flags.dual_color_diffed_diffs)
                        set_sign = NULL;
                else {
                        char c = !len ? 0 : line[0];

                        set_sign = set;
                        if (c == '+')
                                set = diff_get_color_opt(o, DIFF_FILE_NEW_DIM);
                        else if (c == '@')
                                set = diff_get_color_opt(o, DIFF_FRAGINFO);
                        else if (c == '-')
                                set = diff_get_color_opt(o, DIFF_FILE_OLD_DIM);
                        else
                                set = diff_get_color_opt(o, DIFF_CONTEXT_DIM);
                }
                emit_line_ws_markup(o, set_sign, set, reset,
                                    OUTPUT_INDICATOR_OLD, line, len,
                                    flags & DIFF_SYMBOL_CONTENT_WS_MASK, 0);
                break;
        case DIFF_SYMBOL_WORDS_PORCELAIN:
                context = diff_get_color_opt(o, DIFF_CONTEXT);
                reset = diff_get_color_opt(o, DIFF_RESET);
                emit_line(o, context, reset, line, len);
                fputs("~\n", o->file);
                break;
        case DIFF_SYMBOL_WORDS:
                context = diff_get_color_opt(o, DIFF_CONTEXT);
                reset = diff_get_color_opt(o, DIFF_RESET);
                /*
                 * Skip the prefix character, if any.  With
                 * diff_suppress_blank_empty, there may be
                 * none.
                 */
                if (line[0] != '\n') {
                        line++;
                        len--;
                }
                emit_line(o, context, reset, line, len);
                break;
        case DIFF_SYMBOL_FILEPAIR_PLUS:
                meta = diff_get_color_opt(o, DIFF_METAINFO);
                reset = diff_get_color_opt(o, DIFF_RESET);
                fprintf(o->file, "%s%s+++ %s%s%s\n", diff_line_prefix(o), meta,
                        line, reset,
                        strchr(line, ' ') ? "\t" : "");
                break;
        case DIFF_SYMBOL_FILEPAIR_MINUS:
                meta = diff_get_color_opt(o, DIFF_METAINFO);
                reset = diff_get_color_opt(o, DIFF_RESET);
                fprintf(o->file, "%s%s--- %s%s%s\n", diff_line_prefix(o), meta,
                        line, reset,
                        strchr(line, ' ') ? "\t" : "");
                break;
        case DIFF_SYMBOL_BINARY_FILES:
        case DIFF_SYMBOL_HEADER:
                fprintf(o->file, "%s", line);
                break;
        case DIFF_SYMBOL_BINARY_DIFF_HEADER:
                fprintf(o->file, "%sGIT binary patch\n", diff_line_prefix(o));
                break;
        case DIFF_SYMBOL_BINARY_DIFF_HEADER_DELTA:
                fprintf(o->file, "%sdelta %s\n", diff_line_prefix(o), line);
                break;
        case DIFF_SYMBOL_BINARY_DIFF_HEADER_LITERAL:
                fprintf(o->file, "%sliteral %s\n", diff_line_prefix(o), line);
                break;
        case DIFF_SYMBOL_BINARY_DIFF_FOOTER:
                fputs(diff_line_prefix(o), o->file);
                fputc('\n', o->file);
                break;
        case DIFF_SYMBOL_REWRITE_DIFF:
                fraginfo = diff_get_color(o->use_color, DIFF_FRAGINFO);
                reset = diff_get_color_opt(o, DIFF_RESET);
                emit_line(o, fraginfo, reset, line, len);
                break;
        case DIFF_SYMBOL_SUBMODULE_ADD:
                set = diff_get_color_opt(o, DIFF_FILE_NEW);
                reset = diff_get_color_opt(o, DIFF_RESET);
                emit_line(o, set, reset, line, len);
                break;
        case DIFF_SYMBOL_SUBMODULE_DEL:
                set = diff_get_color_opt(o, DIFF_FILE_OLD);
                reset = diff_get_color_opt(o, DIFF_RESET);
                emit_line(o, set, reset, line, len);
                break;
        case DIFF_SYMBOL_SUBMODULE_UNTRACKED:
                fprintf(o->file, "%sSubmodule %s contains untracked content\n",
                        diff_line_prefix(o), line);
                break;
        case DIFF_SYMBOL_SUBMODULE_MODIFIED:
                fprintf(o->file, "%sSubmodule %s contains modified content\n",
                        diff_line_prefix(o), line);
                break;
        case DIFF_SYMBOL_STATS_SUMMARY_NO_FILES:
                emit_line(o, "", "", " 0 files changed\n",
                          strlen(" 0 files changed\n"));
                break;
        case DIFF_SYMBOL_STATS_SUMMARY_ABBREV:
                emit_line(o, "", "", " ...\n", strlen(" ...\n"));
                break;
        case DIFF_SYMBOL_WORD_DIFF:
                fprintf(o->file, "%.*s", len, line);
                break;
        case DIFF_SYMBOL_STAT_SEP:
                fputs(o->stat_sep, o->file);
                break;
        default:
                BUG("unknown diff symbol");
        }
        strbuf_release(&sb);
}

static void emit_diff_symbol(struct diff_options *o, enum diff_symbol s,
                             const char *line, int len, unsigned flags)
{
        struct emitted_diff_symbol e = {line, len, flags, 0, 0, s};

        if (o->emitted_symbols)
                append_emitted_diff_symbol(o, &e);
        else
                emit_diff_symbol_from_struct(o, &e);
}

void diff_emit_submodule_del(struct diff_options *o, const char *line)
{
        emit_diff_symbol(o, DIFF_SYMBOL_SUBMODULE_DEL, line, strlen(line), 0);
}

void diff_emit_submodule_add(struct diff_options *o, const char *line)
{
        emit_diff_symbol(o, DIFF_SYMBOL_SUBMODULE_ADD, line, strlen(line), 0);
}

void diff_emit_submodule_untracked(struct diff_options *o, const char *path)
{
        emit_diff_symbol(o, DIFF_SYMBOL_SUBMODULE_UNTRACKED,
                         path, strlen(path), 0);
}

void diff_emit_submodule_modified(struct diff_options *o, const char *path)
{
        emit_diff_symbol(o, DIFF_SYMBOL_SUBMODULE_MODIFIED,
                         path, strlen(path), 0);
}

void diff_emit_submodule_header(struct diff_options *o, const char *header)
{
        emit_diff_symbol(o, DIFF_SYMBOL_SUBMODULE_HEADER,
                         header, strlen(header), 0);
}

void diff_emit_submodule_error(struct diff_options *o, const char *err)
{
        emit_diff_symbol(o, DIFF_SYMBOL_SUBMODULE_ERROR, err, strlen(err), 0);
}

void diff_emit_submodule_pipethrough(struct diff_options *o,
                                     const char *line, int len)
{
        emit_diff_symbol(o, DIFF_SYMBOL_SUBMODULE_PIPETHROUGH, line, len, 0);
}

static int new_blank_line_at_eof(struct emit_callback *ecbdata, const char *line, int len)
{
        if (!((ecbdata->ws_rule & WS_BLANK_AT_EOF) &&
              ecbdata->blank_at_eof_in_preimage &&
              ecbdata->blank_at_eof_in_postimage &&
              ecbdata->blank_at_eof_in_preimage <= ecbdata->lno_in_preimage &&
              ecbdata->blank_at_eof_in_postimage <= ecbdata->lno_in_postimage))
                return 0;
        return ws_blank_line(line, len, ecbdata->ws_rule);
}

static void emit_add_line(struct emit_callback *ecbdata,
                          const char *line, int len)
{
        unsigned flags = WSEH_NEW | ecbdata->ws_rule;
        if (new_blank_line_at_eof(ecbdata, line, len))
                flags |= DIFF_SYMBOL_CONTENT_BLANK_LINE_EOF;

        emit_diff_symbol(ecbdata->opt, DIFF_SYMBOL_PLUS, line, len, flags);
}

static void emit_del_line(struct emit_callback *ecbdata,
                          const char *line, int len)
{
        unsigned flags = WSEH_OLD | ecbdata->ws_rule;
        emit_diff_symbol(ecbdata->opt, DIFF_SYMBOL_MINUS, line, len, flags);
}

static void emit_context_line(struct emit_callback *ecbdata,
                              const char *line, int len)
{
        unsigned flags = WSEH_CONTEXT | ecbdata->ws_rule;
        emit_diff_symbol(ecbdata->opt, DIFF_SYMBOL_CONTEXT, line, len, flags);
}

static void emit_hunk_header(struct emit_callback *ecbdata,
                             const char *line, int len)
{
        const char *context = diff_get_color(ecbdata->color_diff, DIFF_CONTEXT);
        const char *frag = diff_get_color(ecbdata->color_diff, DIFF_FRAGINFO);
        const char *func = diff_get_color(ecbdata->color_diff, DIFF_FUNCINFO);
        const char *reset = diff_get_color(ecbdata->color_diff, DIFF_RESET);
        const char *reverse = ecbdata->color_diff ? GIT_COLOR_REVERSE : "";
        static const char atat[2] = { '@', '@' };
        const char *cp, *ep;
        struct strbuf msgbuf = STRBUF_INIT;
        int org_len = len;
        int i = 1;

        /*
         * As a hunk header must begin with "@@ -<old>, +<new> @@",
         * it always is at least 10 bytes long.
         */
        if (len < 10 ||
            memcmp(line, atat, 2) ||
            !(ep = memmem(line + 2, len - 2, atat, 2))) {
                emit_diff_symbol(ecbdata->opt,
                                 DIFF_SYMBOL_CONTEXT_MARKER, line, len, 0);
                return;
        }
        ep += 2; /* skip over @@ */

        /* The hunk header in fraginfo color */
        if (ecbdata->opt->flags.dual_color_diffed_diffs)
                strbuf_addstr(&msgbuf, reverse);
        strbuf_addstr(&msgbuf, frag);
        if (ecbdata->opt->flags.suppress_hunk_header_line_count)
                strbuf_add(&msgbuf, atat, sizeof(atat));
        else
                strbuf_add(&msgbuf, line, ep - line);
        strbuf_addstr(&msgbuf, reset);

        /*
         * trailing "\r\n"
         */
        for ( ; i < 3; i++)
                if (line[len - i] == '\r' || line[len - i] == '\n')
                        len--;

        /* blank before the func header */
        for (cp = ep; ep - line < len; ep++)
                if (*ep != ' ' && *ep != '\t')
                        break;
        if (ep != cp) {
                strbuf_addstr(&msgbuf, context);
                strbuf_add(&msgbuf, cp, ep - cp);
                strbuf_addstr(&msgbuf, reset);
        }

        if (ep < line + len) {
                strbuf_addstr(&msgbuf, func);
                strbuf_add(&msgbuf, ep, line + len - ep);
                strbuf_addstr(&msgbuf, reset);
        }

        strbuf_add(&msgbuf, line + len, org_len - len);
        strbuf_complete_line(&msgbuf);
        emit_diff_symbol(ecbdata->opt,
                         DIFF_SYMBOL_CONTEXT_FRAGINFO, msgbuf.buf, msgbuf.len, 0);
        strbuf_release(&msgbuf);
}

static struct diff_tempfile *claim_diff_tempfile(void)
{
        int i;
        for (i = 0; i < ARRAY_SIZE(diff_temp); i++)
                if (!diff_temp[i].name)
                        return diff_temp + i;
        BUG("diff is failing to clean up its tempfiles");
}

static void remove_tempfile(void)
{
        int i;
        for (i = 0; i < ARRAY_SIZE(diff_temp); i++) {
                if (is_tempfile_active(diff_temp[i].tempfile))
                        delete_tempfile(&diff_temp[i].tempfile);
                diff_temp[i].name = NULL;
        }
}

static void add_line_count(struct strbuf *out, int count)
{
        switch (count) {
        case 0:
                strbuf_addstr(out, "0,0");
                break;
        case 1:
                strbuf_addstr(out, "1");
                break;
        default:
                strbuf_addf(out, "1,%d", count);
                break;
        }
}

static void emit_rewrite_lines(struct emit_callback *ecb,
                               int prefix, const char *data, int size)
{
        const char *endp = NULL;

        while (0 < size) {
                int len;

                endp = memchr(data, '\n', size);
                len = endp ? (endp - data + 1) : size;
                if (prefix != '+') {
                        ecb->lno_in_preimage++;
                        emit_del_line(ecb, data, len);
                } else {
                        ecb->lno_in_postimage++;
                        emit_add_line(ecb, data, len);
                }
                size -= len;
                data += len;
        }
        if (!endp)
                emit_diff_symbol(ecb->opt, DIFF_SYMBOL_NO_LF_EOF, NULL, 0, 0);
}

static void emit_rewrite_diff(const char *name_a,
                              const char *name_b,
                              struct diff_filespec *one,
                              struct diff_filespec *two,
                              struct userdiff_driver *textconv_one,
                              struct userdiff_driver *textconv_two,
                              struct diff_options *o)
{
        int lc_a, lc_b;
        static struct strbuf a_name = STRBUF_INIT, b_name = STRBUF_INIT;
        const char *a_prefix, *b_prefix;
        char *data_one, *data_two;
        size_t size_one, size_two;
        struct emit_callback ecbdata;
        struct strbuf out = STRBUF_INIT;

        if (diff_mnemonic_prefix && o->flags.reverse_diff) {
                a_prefix = o->b_prefix;
                b_prefix = o->a_prefix;
        } else {
                a_prefix = o->a_prefix;
                b_prefix = o->b_prefix;
        }

        name_a += (*name_a == '/');
        name_b += (*name_b == '/');

        strbuf_reset(&a_name);
        strbuf_reset(&b_name);
        quote_two_c_style(&a_name, a_prefix, name_a, 0);
        quote_two_c_style(&b_name, b_prefix, name_b, 0);

        size_one = fill_textconv(o->repo, textconv_one, one, &data_one);
        size_two = fill_textconv(o->repo, textconv_two, two, &data_two);

        memset(&ecbdata, 0, sizeof(ecbdata));
        ecbdata.color_diff = want_color(o->use_color);
        ecbdata.ws_rule = whitespace_rule(o->repo->index, name_b);
        ecbdata.opt = o;
        if (ecbdata.ws_rule & WS_BLANK_AT_EOF) {
                mmfile_t mf1, mf2;
                mf1.ptr = (char *)data_one;
                mf2.ptr = (char *)data_two;
                mf1.size = size_one;
                mf2.size = size_two;
                check_blank_at_eof(&mf1, &mf2, &ecbdata);
        }
        ecbdata.lno_in_preimage = 1;
        ecbdata.lno_in_postimage = 1;

        lc_a = count_lines(data_one, size_one);
        lc_b = count_lines(data_two, size_two);

        emit_diff_symbol(o, DIFF_SYMBOL_FILEPAIR_MINUS,
                         a_name.buf, a_name.len, 0);
        emit_diff_symbol(o, DIFF_SYMBOL_FILEPAIR_PLUS,
                         b_name.buf, b_name.len, 0);

        strbuf_addstr(&out, "@@ -");
        if (!o->irreversible_delete)
                add_line_count(&out, lc_a);
        else
                strbuf_addstr(&out, "?,?");
        strbuf_addstr(&out, " +");
        add_line_count(&out, lc_b);
        strbuf_addstr(&out, " @@\n");
        emit_diff_symbol(o, DIFF_SYMBOL_REWRITE_DIFF, out.buf, out.len, 0);
        strbuf_release(&out);

        if (lc_a && !o->irreversible_delete)
                emit_rewrite_lines(&ecbdata, '-', data_one, size_one);
        if (lc_b)
                emit_rewrite_lines(&ecbdata, '+', data_two, size_two);
        if (textconv_one)
                free((char *)data_one);
        if (textconv_two)
                free((char *)data_two);
}

struct diff_words_buffer {
        mmfile_t text;
        unsigned long alloc;
        struct diff_words_orig {
                const char *begin, *end;
        } *orig;
        int orig_nr, orig_alloc;
};

static void diff_words_append(char *line, unsigned long len,
                struct diff_words_buffer *buffer)
{
        ALLOC_GROW(buffer->text.ptr, buffer->text.size + len, buffer->alloc);
        line++;
        len--;
        memcpy(buffer->text.ptr + buffer->text.size, line, len);
        buffer->text.size += len;
        buffer->text.ptr[buffer->text.size] = '\0';
}

struct diff_words_style_elem {
        const char *prefix;
        const char *suffix;
        const char *color; /* NULL; filled in by the setup code if
                            * color is enabled */
};

struct diff_words_style {
        enum diff_words_type type;
        struct diff_words_style_elem new_word, old_word, ctx;
        const char *newline;
};

static struct diff_words_style diff_words_styles[] = {
        { DIFF_WORDS_PORCELAIN, {"+", "\n"}, {"-", "\n"}, {" ", "\n"}, "~\n" },
        { DIFF_WORDS_PLAIN, {"{+", "+}"}, {"[-", "-]"}, {"", ""}, "\n" },
        { DIFF_WORDS_COLOR, {"", ""}, {"", ""}, {"", ""}, "\n" }
};

struct diff_words_data {
        struct diff_words_buffer minus, plus;
        const char *current_plus;
        int last_minus;
        struct diff_options *opt;
        regex_t *word_regex;
        enum diff_words_type type;
        struct diff_words_style *style;
};

static int fn_out_diff_words_write_helper(struct diff_options *o,
                                          struct diff_words_style_elem *st_el,
                                          const char *newline,
                                          size_t count, const char *buf)
{
        int print = 0;
        struct strbuf sb = STRBUF_INIT;

        while (count) {
                char *p = memchr(buf, '\n', count);
                if (print)
                        strbuf_addstr(&sb, diff_line_prefix(o));

                if (p != buf) {
                        const char *reset = st_el->color && *st_el->color ?
                                            GIT_COLOR_RESET : NULL;
                        if (st_el->color && *st_el->color)
                                strbuf_addstr(&sb, st_el->color);
                        strbuf_addstr(&sb, st_el->prefix);
                        strbuf_add(&sb, buf, p ? p - buf : count);
                        strbuf_addstr(&sb, st_el->suffix);
                        if (reset)
                                strbuf_addstr(&sb, reset);
                }
                if (!p)
                        goto out;

                strbuf_addstr(&sb, newline);
                count -= p + 1 - buf;
                buf = p + 1;
                print = 1;
                if (count) {
                        emit_diff_symbol(o, DIFF_SYMBOL_WORD_DIFF,
                                         sb.buf, sb.len, 0);
                        strbuf_reset(&sb);
                }
        }

out:
        if (sb.len)
                emit_diff_symbol(o, DIFF_SYMBOL_WORD_DIFF,
                                 sb.buf, sb.len, 0);
        strbuf_release(&sb);
        return 0;
}

/*
 * '--color-words' algorithm can be described as:
 *
 *   1. collect the minus/plus lines of a diff hunk, divided into
 *      minus-lines and plus-lines;
 *
 *   2. break both minus-lines and plus-lines into words and
 *      place them into two mmfile_t with one word for each line;
 *
 *   3. use xdiff to run diff on the two mmfile_t to get the words level diff;
 *
 * And for the common parts of the both file, we output the plus side text.
 * diff_words->current_plus is used to trace the current position of the plus file
 * which printed. diff_words->last_minus is used to trace the last minus word
 * printed.
 *
 * For '--graph' to work with '--color-words', we need to output the graph prefix
 * on each line of color words output. Generally, there are two conditions on
 * which we should output the prefix.
 *
 *   1. diff_words->last_minus == 0 &&
 *      diff_words->current_plus == diff_words->plus.text.ptr
 *
 *      that is: the plus text must start as a new line, and if there is no minus
 *      word printed, a graph prefix must be printed.
 *
 *   2. diff_words->current_plus > diff_words->plus.text.ptr &&
 *      *(diff_words->current_plus - 1) == '\n'
 *
 *      that is: a graph prefix must be printed following a '\n'
 */
static int color_words_output_graph_prefix(struct diff_words_data *diff_words)
{
        if ((diff_words->last_minus == 0 &&
                diff_words->current_plus == diff_words->plus.text.ptr) ||
                (diff_words->current_plus > diff_words->plus.text.ptr &&
                *(diff_words->current_plus - 1) == '\n')) {
                return 1;
        } else {
                return 0;
        }
}

static void fn_out_diff_words_aux(void *priv,
                                  long minus_first, long minus_len,
                                  long plus_first, long plus_len,
                                  const char *func, long funclen)
{
        struct diff_words_data *diff_words = priv;
        struct diff_words_style *style = diff_words->style;
        const char *minus_begin, *minus_end, *plus_begin, *plus_end;
        struct diff_options *opt = diff_words->opt;
        const char *line_prefix;

        assert(opt);
        line_prefix = diff_line_prefix(opt);

        /* POSIX requires that first be decremented by one if len == 0... */
        if (minus_len) {
                minus_begin = diff_words->minus.orig[minus_first].begin;
                minus_end =
                        diff_words->minus.orig[minus_first + minus_len - 1].end;
        } else
                minus_begin = minus_end =
                        diff_words->minus.orig[minus_first].end;

        if (plus_len) {
                plus_begin = diff_words->plus.orig[plus_first].begin;
                plus_end = diff_words->plus.orig[plus_first + plus_len - 1].end;
        } else
                plus_begin = plus_end = diff_words->plus.orig[plus_first].end;

        if (color_words_output_graph_prefix(diff_words)) {
                fputs(line_prefix, diff_words->opt->file);
        }
        if (diff_words->current_plus != plus_begin) {
                fn_out_diff_words_write_helper(diff_words->opt,
                                &style->ctx, style->newline,
                                plus_begin - diff_words->current_plus,
                                diff_words->current_plus);
        }
        if (minus_begin != minus_end) {
                fn_out_diff_words_write_helper(diff_words->opt,
                                &style->old_word, style->newline,
                                minus_end - minus_begin, minus_begin);
        }
        if (plus_begin != plus_end) {
                fn_out_diff_words_write_helper(diff_words->opt,
                                &style->new_word, style->newline,
                                plus_end - plus_begin, plus_begin);
        }

        diff_words->current_plus = plus_end;
        diff_words->last_minus = minus_first;
}

/* This function starts looking at *begin, and returns 0 iff a word was found. */
static int find_word_boundaries(mmfile_t *buffer, regex_t *word_regex,
                int *begin, int *end)
{
        if (word_regex && *begin < buffer->size) {
                regmatch_t match[1];
                if (!regexec_buf(word_regex, buffer->ptr + *begin,
                                 buffer->size - *begin, 1, match, 0)) {
                        char *p = memchr(buffer->ptr + *begin + match[0].rm_so,
                                        '\n', match[0].rm_eo - match[0].rm_so);
                        *end = p ? p - buffer->ptr : match[0].rm_eo + *begin;
                        *begin += match[0].rm_so;
                        return *begin >= *end;
                }
                return -1;
        }

        /* find the next word */
        while (*begin < buffer->size && isspace(buffer->ptr[*begin]))
                (*begin)++;
        if (*begin >= buffer->size)
                return -1;

        /* find the end of the word */
        *end = *begin + 1;
        while (*end < buffer->size && !isspace(buffer->ptr[*end]))
                (*end)++;

        return 0;
}

/*
 * This function splits the words in buffer->text, stores the list with
 * newline separator into out, and saves the offsets of the original words
 * in buffer->orig.
 */
static void diff_words_fill(struct diff_words_buffer *buffer, mmfile_t *out,
                regex_t *word_regex)
{
        int i, j;
        long alloc = 0;

        out->size = 0;
        out->ptr = NULL;

        /* fake an empty "0th" word */
        ALLOC_GROW(buffer->orig, 1, buffer->orig_alloc);
        buffer->orig[0].begin = buffer->orig[0].end = buffer->text.ptr;
        buffer->orig_nr = 1;

        for (i = 0; i < buffer->text.size; i++) {
                if (find_word_boundaries(&buffer->text, word_regex, &i, &j))
                        return;

                /* store original boundaries */
                ALLOC_GROW(buffer->orig, buffer->orig_nr + 1,
                                buffer->orig_alloc);
                buffer->orig[buffer->orig_nr].begin = buffer->text.ptr + i;
                buffer->orig[buffer->orig_nr].end = buffer->text.ptr + j;
                buffer->orig_nr++;

                /* store one word */
                ALLOC_GROW(out->ptr, out->size + j - i + 1, alloc);
                memcpy(out->ptr + out->size, buffer->text.ptr + i, j - i);
                out->ptr[out->size + j - i] = '\n';
                out->size += j - i + 1;

                i = j - 1;
        }
}

/* this executes the word diff on the accumulated buffers */
static void diff_words_show(struct diff_words_data *diff_words)
{
        xpparam_t xpp;
        xdemitconf_t xecfg;
        mmfile_t minus, plus;
        struct diff_words_style *style = diff_words->style;

        struct diff_options *opt = diff_words->opt;
        const char *line_prefix;

        assert(opt);
        line_prefix = diff_line_prefix(opt);

        /* special case: only removal */
        if (!diff_words->plus.text.size) {
                emit_diff_symbol(diff_words->opt, DIFF_SYMBOL_WORD_DIFF,
                                 line_prefix, strlen(line_prefix), 0);
                fn_out_diff_words_write_helper(diff_words->opt,
                        &style->old_word, style->newline,
                        diff_words->minus.text.size,
                        diff_words->minus.text.ptr);
                diff_words->minus.text.size = 0;
                return;
        }

        diff_words->current_plus = diff_words->plus.text.ptr;
        diff_words->last_minus = 0;

        memset(&xpp, 0, sizeof(xpp));
        memset(&xecfg, 0, sizeof(xecfg));
        diff_words_fill(&diff_words->minus, &minus, diff_words->word_regex);
        diff_words_fill(&diff_words->plus, &plus, diff_words->word_regex);
        xpp.flags = 0;
        /* as only the hunk header will be parsed, we need a 0-context */
        xecfg.ctxlen = 0;
        if (xdi_diff_outf(&minus, &plus, fn_out_diff_words_aux, NULL,
                          diff_words, &xpp, &xecfg))
                die("unable to generate word diff");
        free(minus.ptr);
        free(plus.ptr);
        if (diff_words->current_plus != diff_words->plus.text.ptr +
                        diff_words->plus.text.size) {
                if (color_words_output_graph_prefix(diff_words))
                        emit_diff_symbol(diff_words->opt, DIFF_SYMBOL_WORD_DIFF,
                                         line_prefix, strlen(line_prefix), 0);
                fn_out_diff_words_write_helper(diff_words->opt,
                        &style->ctx, style->newline,
                        diff_words->plus.text.ptr + diff_words->plus.text.size
                        - diff_words->current_plus, diff_words->current_plus);
        }
        diff_words->minus.text.size = diff_words->plus.text.size = 0;
}

/* In "color-words" mode, show word-diff of words accumulated in the buffer */
static void diff_words_flush(struct emit_callback *ecbdata)
{
        struct diff_options *wo = ecbdata->diff_words->opt;

        if (ecbdata->diff_words->minus.text.size ||
            ecbdata->diff_words->plus.text.size)
                diff_words_show(ecbdata->diff_words);

        if (wo->emitted_symbols) {
                struct diff_options *o = ecbdata->opt;
                struct emitted_diff_symbols *wol = wo->emitted_symbols;
                int i;

                /*
                 * NEEDSWORK:
                 * Instead of appending each, concat all words to a line?
                 */
                for (i = 0; i < wol->nr; i++)
                        append_emitted_diff_symbol(o, &wol->buf[i]);

                for (i = 0; i < wol->nr; i++)
                        free((void *)wol->buf[i].line);

                wol->nr = 0;
        }
}

static void diff_filespec_load_driver(struct diff_filespec *one,
                                      struct index_state *istate)
{
        /* Use already-loaded driver */
        if (one->driver)
                return;

        if (S_ISREG(one->mode))
                one->driver = userdiff_find_by_path(istate, one->path);

        /* Fallback to default settings */
        if (!one->driver)
                one->driver = userdiff_find_by_name("default");
}

static const char *userdiff_word_regex(struct diff_filespec *one,
                                       struct index_state *istate)
{
        diff_filespec_load_driver(one, istate);
        return one->driver->word_regex;
}

static void init_diff_words_data(struct emit_callback *ecbdata,
                                 struct diff_options *orig_opts,
                                 struct diff_filespec *one,
                                 struct diff_filespec *two)
{
        int i;
        struct diff_options *o = xmalloc(sizeof(struct diff_options));
        memcpy(o, orig_opts, sizeof(struct diff_options));

        ecbdata->diff_words =
                xcalloc(1, sizeof(struct diff_words_data));
        ecbdata->diff_words->type = o->word_diff;
        ecbdata->diff_words->opt = o;

        if (orig_opts->emitted_symbols)
                o->emitted_symbols =
                        xcalloc(1, sizeof(struct emitted_diff_symbols));

        if (!o->word_regex)
                o->word_regex = userdiff_word_regex(one, o->repo->index);
        if (!o->word_regex)
                o->word_regex = userdiff_word_regex(two, o->repo->index);
        if (!o->word_regex)
                o->word_regex = diff_word_regex_cfg;
        if (o->word_regex) {
                ecbdata->diff_words->word_regex = (regex_t *)
                        xmalloc(sizeof(regex_t));
                if (regcomp(ecbdata->diff_words->word_regex,
                            o->word_regex,
                            REG_EXTENDED | REG_NEWLINE))
                        die("invalid regular expression: %s",
                            o->word_regex);
        }
        for (i = 0; i < ARRAY_SIZE(diff_words_styles); i++) {
                if (o->word_diff == diff_words_styles[i].type) {
                        ecbdata->diff_words->style =
                                &diff_words_styles[i];
                        break;
                }
        }
        if (want_color(o->use_color)) {
                struct diff_words_style *st = ecbdata->diff_words->style;
                st->old_word.color = diff_get_color_opt(o, DIFF_FILE_OLD);
                st->new_word.color = diff_get_color_opt(o, DIFF_FILE_NEW);
                st->ctx.color = diff_get_color_opt(o, DIFF_CONTEXT);
        }
}

static void free_diff_words_data(struct emit_callback *ecbdata)
{
        if (ecbdata->diff_words) {
                diff_words_flush(ecbdata);
                free (ecbdata->diff_words->opt->emitted_symbols);
                free (ecbdata->diff_words->opt);
                free (ecbdata->diff_words->minus.text.ptr);
                free (ecbdata->diff_words->minus.orig);
                free (ecbdata->diff_words->plus.text.ptr);
                free (ecbdata->diff_words->plus.orig);
                if (ecbdata->diff_words->word_regex) {
                        regfree(ecbdata->diff_words->word_regex);
                        free(ecbdata->diff_words->word_regex);
                }
                FREE_AND_NULL(ecbdata->diff_words);
        }
}

const char *diff_get_color(int diff_use_color, enum color_diff ix)
{
        if (want_color(diff_use_color))
                return diff_colors[ix];
        return "";
}

const char *diff_line_prefix(struct diff_options *opt)
{
        struct strbuf *msgbuf;
        if (!opt->output_prefix)
                return "";

        msgbuf = opt->output_prefix(opt, opt->output_prefix_data);
        return msgbuf->buf;
}

static unsigned long sane_truncate_line(char *line, unsigned long len)
{
        const char *cp;
        unsigned long allot;
        size_t l = len;

        cp = line;
        allot = l;
        while (0 < l) {
                (void) utf8_width(&cp, &l);
                if (!cp)
                        break; /* truncated in the middle? */
        }
        return allot - l;
}

static void find_lno(const char *line, struct emit_callback *ecbdata)
{
        const char *p;
        ecbdata->lno_in_preimage = 0;
        ecbdata->lno_in_postimage = 0;
        p = strchr(line, '-');
        if (!p)
                return; /* cannot happen */
        ecbdata->lno_in_preimage = strtol(p + 1, NULL, 10);
        p = strchr(p, '+');
        if (!p)
                return; /* cannot happen */
        ecbdata->lno_in_postimage = strtol(p + 1, NULL, 10);
}

static void fn_out_consume(void *priv, char *line, unsigned long len)
{
        struct emit_callback *ecbdata = priv;
        struct diff_options *o = ecbdata->opt;

        o->found_changes = 1;

        if (ecbdata->header) {
                emit_diff_symbol(o, DIFF_SYMBOL_HEADER,
                                 ecbdata->header->buf, ecbdata->header->len, 0);
                strbuf_reset(ecbdata->header);
                ecbdata->header = NULL;
        }

        if (ecbdata->label_path[0]) {
                emit_diff_symbol(o, DIFF_SYMBOL_FILEPAIR_MINUS,
                                 ecbdata->label_path[0],
                                 strlen(ecbdata->label_path[0]), 0);
                emit_diff_symbol(o, DIFF_SYMBOL_FILEPAIR_PLUS,
                                 ecbdata->label_path[1],
                                 strlen(ecbdata->label_path[1]), 0);
                ecbdata->label_path[0] = ecbdata->label_path[1] = NULL;
        }

        if (diff_suppress_blank_empty
            && len == 2 && line[0] == ' ' && line[1] == '\n') {
                line[0] = '\n';
                len = 1;
        }

        if (line[0] == '@') {
                if (ecbdata->diff_words)
                        diff_words_flush(ecbdata);
                len = sane_truncate_line(line, len);
                find_lno(line, ecbdata);
                emit_hunk_header(ecbdata, line, len);
                return;
        }

        if (ecbdata->diff_words) {
                enum diff_symbol s =
                        ecbdata->diff_words->type == DIFF_WORDS_PORCELAIN ?
                        DIFF_SYMBOL_WORDS_PORCELAIN : DIFF_SYMBOL_WORDS;
                if (line[0] == '-') {
                        diff_words_append(line, len,
                                          &ecbdata->diff_words->minus);
                        return;
                } else if (line[0] == '+') {
                        diff_words_append(line, len,
                                          &ecbdata->diff_words->plus);
                        return;
                } else if (starts_with(line, "\\ ")) {
                        /*
                         * Eat the "no newline at eof" marker as if we
                         * saw a "+" or "-" line with nothing on it,
                         * and return without diff_words_flush() to
                         * defer processing. If this is the end of
                         * preimage, more "+" lines may come after it.
                         */
                        return;
                }
                diff_words_flush(ecbdata);
                emit_diff_symbol(o, s, line, len, 0);
                return;
        }

        switch (line[0]) {
        case '+':
                ecbdata->lno_in_postimage++;
                emit_add_line(ecbdata, line + 1, len - 1);
                break;
        case '-':
                ecbdata->lno_in_preimage++;
                emit_del_line(ecbdata, line + 1, len - 1);
                break;
        case ' ':
                ecbdata->lno_in_postimage++;
                ecbdata->lno_in_preimage++;
                emit_context_line(ecbdata, line + 1, len - 1);
                break;
        default:
                /* incomplete line at the end */
                ecbdata->lno_in_preimage++;
                emit_diff_symbol(o, DIFF_SYMBOL_CONTEXT_INCOMPLETE,
                                 line, len, 0);
                break;
        }
}

static void pprint_rename(struct strbuf *name, const char *a, const char *b)
{
        const char *old_name = a;
        const char *new_name = b;
        int pfx_length, sfx_length;
        int pfx_adjust_for_slash;
        int len_a = strlen(a);
        int len_b = strlen(b);
        int a_midlen, b_midlen;
        int qlen_a = quote_c_style(a, NULL, NULL, 0);
        int qlen_b = quote_c_style(b, NULL, NULL, 0);

        if (qlen_a || qlen_b) {
                quote_c_style(a, name, NULL, 0);
                strbuf_addstr(name, " => ");
                quote_c_style(b, name, NULL, 0);
                return;
        }

        /* Find common prefix */
        pfx_length = 0;
        while (*old_name && *new_name && *old_name == *new_name) {
                if (*old_name == '/')
                        pfx_length = old_name - a + 1;
                old_name++;
                new_name++;
        }

        /* Find common suffix */
        old_name = a + len_a;
        new_name = b + len_b;
        sfx_length = 0;
        /*
         * If there is a common prefix, it must end in a slash.  In
         * that case we let this loop run 1 into the prefix to see the
         * same slash.
         *
         * If there is no common prefix, we cannot do this as it would
         * underrun the input strings.
         */
        pfx_adjust_for_slash = (pfx_length ? 1 : 0);
        while (a + pfx_length - pfx_adjust_for_slash <= old_name &&
               b + pfx_length - pfx_adjust_for_slash <= new_name &&
               *old_name == *new_name) {
                if (*old_name == '/')
                        sfx_length = len_a - (old_name - a);
                old_name--;
                new_name--;
        }

        /*
         * pfx{mid-a => mid-b}sfx
         * {pfx-a => pfx-b}sfx
         * pfx{sfx-a => sfx-b}
         * name-a => name-b
         */
        a_midlen = len_a - pfx_length - sfx_length;
        b_midlen = len_b - pfx_length - sfx_length;
        if (a_midlen < 0)
                a_midlen = 0;
        if (b_midlen < 0)
                b_midlen = 0;

        strbuf_grow(name, pfx_length + a_midlen + b_midlen + sfx_length + 7);
        if (pfx_length + sfx_length) {
                strbuf_add(name, a, pfx_length);
                strbuf_addch(name, '{');
        }
        strbuf_add(name, a + pfx_length, a_midlen);
        strbuf_addstr(name, " => ");
        strbuf_add(name, b + pfx_length, b_midlen);
        if (pfx_length + sfx_length) {
                strbuf_addch(name, '}');
                strbuf_add(name, a + len_a - sfx_length, sfx_length);
        }
}

static struct diffstat_file *diffstat_add(struct diffstat_t *diffstat,
                                          const char *name_a,
                                          const char *name_b)
{
        struct diffstat_file *x;
        x = xcalloc(1, sizeof(*x));
        ALLOC_GROW(diffstat->files, diffstat->nr + 1, diffstat->alloc);
        diffstat->files[diffstat->nr++] = x;
        if (name_b) {
                x->from_name = xstrdup(name_a);
                x->name = xstrdup(name_b);
                x->is_renamed = 1;
        }
        else {
                x->from_name = NULL;
                x->name = xstrdup(name_a);
        }
        return x;
}

static void diffstat_consume(void *priv, char *line, unsigned long len)
{
        struct diffstat_t *diffstat = priv;
        struct diffstat_file *x = diffstat->files[diffstat->nr - 1];

        if (line[0] == '+')
                x->added++;
        else if (line[0] == '-')
                x->deleted++;
}

const char mime_boundary_leader[] = "------------";

static int scale_linear(int it, int width, int max_change)
{
        if (!it)
                return 0;
        /*
         * make sure that at least one '-' or '+' is printed if
         * there is any change to this path. The easiest way is to
         * scale linearly as if the allotted width is one column shorter
         * than it is, and then add 1 to the result.
         */
        return 1 + (it * (width - 1) / max_change);
}

static void show_graph(struct strbuf *out, char ch, int cnt,
                       const char *set, const char *reset)
{
        if (cnt <= 0)
                return;
        strbuf_addstr(out, set);
        strbuf_addchars(out, ch, cnt);
        strbuf_addstr(out, reset);
}

static void fill_print_name(struct diffstat_file *file)
{
        struct strbuf pname = STRBUF_INIT;

        if (file->print_name)
                return;

        if (file->is_renamed)
                pprint_rename(&pname, file->from_name, file->name);
        else
                quote_c_style(file->name, &pname, NULL, 0);

        if (file->comments)
                strbuf_addf(&pname, " (%s)", file->comments);

        file->print_name = strbuf_detach(&pname, NULL);
}

static void print_stat_summary_inserts_deletes(struct diff_options *options,
                int files, int insertions, int deletions)
{
        struct strbuf sb = STRBUF_INIT;

        if (!files) {
                assert(insertions == 0 && deletions == 0);
                emit_diff_symbol(options, DIFF_SYMBOL_STATS_SUMMARY_NO_FILES,
                                 NULL, 0, 0);
                return;
        }

        strbuf_addf(&sb,
                    (files == 1) ? " %d file changed" : " %d files changed",
                    files);

        /*
         * For binary diff, the caller may want to print "x files
         * changed" with insertions == 0 && deletions == 0.
         *
         * Not omitting "0 insertions(+), 0 deletions(-)" in this case
         * is probably less confusing (i.e skip over "2 files changed
         * but nothing about added/removed lines? Is this a bug in Git?").
         */
        if (insertions || deletions == 0) {
                strbuf_addf(&sb,
                            (insertions == 1) ? ", %d insertion(+)" : ", %d insertions(+)",
                            insertions);
        }

        if (deletions || insertions == 0) {
                strbuf_addf(&sb,
                            (deletions == 1) ? ", %d deletion(-)" : ", %d deletions(-)",
                            deletions);
        }
        strbuf_addch(&sb, '\n');
        emit_diff_symbol(options, DIFF_SYMBOL_STATS_SUMMARY_INSERTS_DELETES,
                         sb.buf, sb.len, 0);
        strbuf_release(&sb);
}

void print_stat_summary(FILE *fp, int files,
                        int insertions, int deletions)
{
        struct diff_options o;
        memset(&o, 0, sizeof(o));
        o.file = fp;

        print_stat_summary_inserts_deletes(&o, files, insertions, deletions);
}

static void show_stats(struct diffstat_t *data, struct diff_options *options)
{
        int i, len, add, del, adds = 0, dels = 0;
        uintmax_t max_change = 0, max_len = 0;
        int total_files = data->nr, count;
        int width, name_width, graph_width, number_width = 0, bin_width = 0;
        const char *reset, *add_c, *del_c;
        int extra_shown = 0;
        const char *line_prefix = diff_line_prefix(options);
        struct strbuf out = STRBUF_INIT;

        if (data->nr == 0)
                return;

        count = options->stat_count ? options->stat_count : data->nr;

        reset = diff_get_color_opt(options, DIFF_RESET);
        add_c = diff_get_color_opt(options, DIFF_FILE_NEW);
        del_c = diff_get_color_opt(options, DIFF_FILE_OLD);

        /*
         * Find the longest filename and max number of changes
         */
        for (i = 0; (i < count) && (i < data->nr); i++) {
                struct diffstat_file *file = data->files[i];
                uintmax_t change = file->added + file->deleted;

                if (!file->is_interesting && (change == 0)) {
                        count++; /* not shown == room for one more */
                        continue;
                }
                fill_print_name(file);
                len = strlen(file->print_name);
                if (max_len < len)
                        max_len = len;

                if (file->is_unmerged) {
                        /* "Unmerged" is 8 characters */
                        bin_width = bin_width < 8 ? 8 : bin_width;
                        continue;
                }
                if (file->is_binary) {
                        /* "Bin XXX -> YYY bytes" */
                        int w = 14 + decimal_width(file->added)
                                + decimal_width(file->deleted);
                        bin_width = bin_width < w ? w : bin_width;
                        /* Display change counts aligned with "Bin" */
                        number_width = 3;
                        continue;
                }

                if (max_change < change)
                        max_change = change;
        }
        count = i; /* where we can stop scanning in data->files[] */

        /*
         * We have width = stat_width or term_columns() columns total.
         * We want a maximum of min(max_len, stat_name_width) for the name part.
         * We want a maximum of min(max_change, stat_graph_width) for the +- part.
         * We also need 1 for " " and 4 + decimal_width(max_change)
         * for " | NNNN " and one the empty column at the end, altogether
         * 6 + decimal_width(max_change).
         *
         * If there's not enough space, we will use the smaller of
         * stat_name_width (if set) and 5/8*width for the filename,
         * and the rest for constant elements + graph part, but no more
         * than stat_graph_width for the graph part.
         * (5/8 gives 50 for filename and 30 for the constant parts + graph
         * for the standard terminal size).
         *
         * In other words: stat_width limits the maximum width, and
         * stat_name_width fixes the maximum width of the filename,
         * and is also used to divide available columns if there
         * aren't enough.
         *
         * Binary files are displayed with "Bin XXX -> YYY bytes"
         * instead of the change count and graph. This part is treated
         * similarly to the graph part, except that it is not
         * "scaled". If total width is too small to accommodate the
         * guaranteed minimum width of the filename part and the
         * separators and this message, this message will "overflow"
         * making the line longer than the maximum width.
         */

        if (options->stat_width == -1)
                width = term_columns() - strlen(line_prefix);
        else
                width = options->stat_width ? options->stat_width : 80;
        number_width = decimal_width(max_change) > number_width ?
                decimal_width(max_change) : number_width;

        if (options->stat_graph_width == -1)
                options->stat_graph_width = diff_stat_graph_width;

        /*
         * Guarantee 3/8*16==6 for the graph part
         * and 5/8*16==10 for the filename part
         */
        if (width < 16 + 6 + number_width)
                width = 16 + 6 + number_width;

        /*
         * First assign sizes that are wanted, ignoring available width.
         * strlen("Bin XXX -> YYY bytes") == bin_width, and the part
         * starting from "XXX" should fit in graph_width.
         */
        graph_width = max_change + 4 > bin_width ? max_change : bin_width - 4;
        if (options->stat_graph_width &&
            options->stat_graph_width < graph_width)
                graph_width = options->stat_graph_width;

        name_width = (options->stat_name_width > 0 &&
                      options->stat_name_width < max_len) ?
                options->stat_name_width : max_len;

        /*
         * Adjust adjustable widths not to exceed maximum width
         */
        if (name_width + number_width + 6 + graph_width > width) {
                if (graph_width > width * 3/8 - number_width - 6) {
                        graph_width = width * 3/8 - number_width - 6;
                        if (graph_width < 6)
                                graph_width = 6;
                }

                if (options->stat_graph_width &&
                    graph_width > options->stat_graph_width)
                        graph_width = options->stat_graph_width;
                if (name_width > width - number_width - 6 - graph_width)
                        name_width = width - number_width - 6 - graph_width;
                else
                        graph_width = width - number_width - 6 - name_width;
        }

        /*
         * From here name_width is the width of the name area,
         * and graph_width is the width of the graph area.
         * max_change is used to scale graph properly.
         */
        for (i = 0; i < count; i++) {
                const char *prefix = "";
                struct diffstat_file *file = data->files[i];
                char *name = file->print_name;
                uintmax_t added = file->added;
                uintmax_t deleted = file->deleted;
                int name_len;

                if (!file->is_interesting && (added + deleted == 0))
                        continue;

                /*
                 * "scale" the filename
                 */
                len = name_width;
                name_len = strlen(name);
                if (name_width < name_len) {
                        char *slash;
                        prefix = "...";
                        len -= 3;
                        name += name_len - len;
                        slash = strchr(name, '/');
                        if (slash)
                                name = slash;
                }

                if (file->is_binary) {
                        strbuf_addf(&out, " %s%-*s |", prefix, len, name);
                        strbuf_addf(&out, " %*s", number_width, "Bin");
                        if (!added && !deleted) {
                                strbuf_addch(&out, '\n');
                                emit_diff_symbol(options, DIFF_SYMBOL_STATS_LINE,
                                                 out.buf, out.len, 0);
                                strbuf_reset(&out);
                                continue;
                        }
                        strbuf_addf(&out, " %s%"PRIuMAX"%s",
                                del_c, deleted, reset);
                        strbuf_addstr(&out, " -> ");
                        strbuf_addf(&out, "%s%"PRIuMAX"%s",
                                add_c, added, reset);
                        strbuf_addstr(&out, " bytes\n");
                        emit_diff_symbol(options, DIFF_SYMBOL_STATS_LINE,
                                         out.buf, out.len, 0);
                        strbuf_reset(&out);
                        continue;
                }
                else if (file->is_unmerged) {
                        strbuf_addf(&out, " %s%-*s |", prefix, len, name);
                        strbuf_addstr(&out, " Unmerged\n");
                        emit_diff_symbol(options, DIFF_SYMBOL_STATS_LINE,
                                         out.buf, out.len, 0);
                        strbuf_reset(&out);
                        continue;
                }

                /*
                 * scale the add/delete
                 */
                add = added;
                del = deleted;

                if (graph_width <= max_change) {
                        int total = scale_linear(add + del, graph_width, max_change);
                        if (total < 2 && add && del)
                                /* width >= 2 due to the sanity check */
                                total = 2;
                        if (add < del) {
                                add = scale_linear(add, graph_width, max_change);
                                del = total - add;
                        } else {
                                del = scale_linear(del, graph_width, max_change);
                                add = total - del;
                        }
                }
                strbuf_addf(&out, " %s%-*s |", prefix, len, name);
                strbuf_addf(&out, " %*"PRIuMAX"%s",
                        number_width, added + deleted,
                        added + deleted ? " " : "");
                show_graph(&out, '+', add, add_c, reset);
                show_graph(&out, '-', del, del_c, reset);
                strbuf_addch(&out, '\n');
                emit_diff_symbol(options, DIFF_SYMBOL_STATS_LINE,
                                 out.buf, out.len, 0);
                strbuf_reset(&out);
        }

        for (i = 0; i < data->nr; i++) {
                struct diffstat_file *file = data->files[i];
                uintmax_t added = file->added;
                uintmax_t deleted = file->deleted;

                if (file->is_unmerged ||
                    (!file->is_interesting && (added + deleted == 0))) {
                        total_files--;
                        continue;
                }

                if (!file->is_binary) {
                        adds += added;
                        dels += deleted;
                }
                if (i < count)
                        continue;
                if (!extra_shown)
                        emit_diff_symbol(options,
                                         DIFF_SYMBOL_STATS_SUMMARY_ABBREV,
                                         NULL, 0, 0);
                extra_shown = 1;
        }

        print_stat_summary_inserts_deletes(options, total_files, adds, dels);
        strbuf_release(&out);
}

static void show_shortstats(struct diffstat_t *data, struct diff_options *options)
{
        int i, adds = 0, dels = 0, total_files = data->nr;

        if (data->nr == 0)
                return;

        for (i = 0; i < data->nr; i++) {
                int added = data->files[i]->added;
                int deleted = data->files[i]->deleted;

                if (data->files[i]->is_unmerged ||
                    (!data->files[i]->is_interesting && (added + deleted == 0))) {
                        total_files--;
                } else if (!data->files[i]->is_binary) { /* don't count bytes */
                        adds += added;
                        dels += deleted;
                }
        }
        print_stat_summary_inserts_deletes(options, total_files, adds, dels);
}

static void show_numstat(struct diffstat_t *data, struct diff_options *options)
{
        int i;

        if (data->nr == 0)
                return;

        for (i = 0; i < data->nr; i++) {
                struct diffstat_file *file = data->files[i];

                fprintf(options->file, "%s", diff_line_prefix(options));

                if (file->is_binary)
                        fprintf(options->file, "-\t-\t");
                else
                        fprintf(options->file,
                                "%"PRIuMAX"\t%"PRIuMAX"\t",
                                file->added, file->deleted);
                if (options->line_termination) {
                        fill_print_name(file);
                        if (!file->is_renamed)
                                write_name_quoted(file->name, options->file,
                                                  options->line_termination);
                        else {
                                fputs(file->print_name, options->file);
                                putc(options->line_termination, options->file);
                        }
                } else {
                        if (file->is_renamed) {
                                putc('\0', options->file);
                                write_name_quoted(file->from_name, options->file, '\0');
                        }
                        write_name_quoted(file->name, options->file, '\0');
                }
        }
}

struct dirstat_file {
        const char *name;
        unsigned long changed;
};

struct dirstat_dir {
        struct dirstat_file *files;
        int alloc, nr, permille, cumulative;
};

static long gather_dirstat(struct diff_options *opt, struct dirstat_dir *dir,
                unsigned long changed, const char *base, int baselen)
{
        unsigned long sum_changes = 0;
        unsigned int sources = 0;
        const char *line_prefix = diff_line_prefix(opt);

        while (dir->nr) {
                struct dirstat_file *f = dir->files;
                int namelen = strlen(f->name);
                unsigned long changes;
                char *slash;

                if (namelen < baselen)
                        break;
                if (memcmp(f->name, base, baselen))
                        break;
                slash = strchr(f->name + baselen, '/');
                if (slash) {
                        int newbaselen = slash + 1 - f->name;
                        changes = gather_dirstat(opt, dir, changed, f->name, newbaselen);
                        sources++;
                } else {
                        changes = f->changed;
                        dir->files++;
                        dir->nr--;
                        sources += 2;
                }
                sum_changes += changes;
        }

        /*
         * We don't report dirstat's for
         *  - the top level
         *  - or cases where everything came from a single directory
         *    under this directory (sources == 1).
         */
        if (baselen && sources != 1) {
                if (sum_changes) {
                        int permille = sum_changes * 1000 / changed;
                        if (permille >= dir->permille) {
                                fprintf(opt->file, "%s%4d.%01d%% %.*s\n", line_prefix,
                                        permille / 10, permille % 10, baselen, base);
                                if (!dir->cumulative)
                                        return 0;
                        }
                }
        }
        return sum_changes;
}

static int dirstat_compare(const void *_a, const void *_b)
{
        const struct dirstat_file *a = _a;
        const struct dirstat_file *b = _b;
        return strcmp(a->name, b->name);
}

static void show_dirstat(struct diff_options *options)
{
        int i;
        unsigned long changed;
        struct dirstat_dir dir;
        struct diff_queue_struct *q = &diff_queued_diff;

        dir.files = NULL;
        dir.alloc = 0;
        dir.nr = 0;
        dir.permille = options->dirstat_permille;
        dir.cumulative = options->flags.dirstat_cumulative;

        changed = 0;
        for (i = 0; i < q->nr; i++) {
                struct diff_filepair *p = q->queue[i];
                const char *name;
                unsigned long copied, added, damage;

                name = p->two->path ? p->two->path : p->one->path;

                if (p->one->oid_valid && p->two->oid_valid &&
                    oideq(&p->one->oid, &p->two->oid)) {
                        /*
                         * The SHA1 has not changed, so pre-/post-content is
                         * identical. We can therefore skip looking at the
                         * file contents altogether.
                         */
                        damage = 0;
                        goto found_damage;
                }

                if (options->flags.dirstat_by_file) {
                        /*
                         * In --dirstat-by-file mode, we don't really need to
                         * look at the actual file contents at all.
                         * The fact that the SHA1 changed is enough for us to
                         * add this file to the list of results
                         * (with each file contributing equal damage).
                         */
                        damage = 1;
                        goto found_damage;
                }

                if (DIFF_FILE_VALID(p->one) && DIFF_FILE_VALID(p->two)) {
                        diff_populate_filespec(options->repo, p->one, 0);
                        diff_populate_filespec(options->repo, p->two, 0);
                        diffcore_count_changes(options->repo,
                                               p->one, p->two, NULL, NULL,
                                               &copied, &added);
                        diff_free_filespec_data(p->one);
                        diff_free_filespec_data(p->two);
                } else if (DIFF_FILE_VALID(p->one)) {
                        diff_populate_filespec(options->repo, p->one, CHECK_SIZE_ONLY);
                        copied = added = 0;
                        diff_free_filespec_data(p->one);
                } else if (DIFF_FILE_VALID(p->two)) {
                        diff_populate_filespec(options->repo, p->two, CHECK_SIZE_ONLY);
                        copied = 0;
                        added = p->two->size;
                        diff_free_filespec_data(p->two);
                } else
                        continue;

                /*
                 * Original minus copied is the removed material,
                 * added is the new material.  They are both damages
                 * made to the preimage.
                 * If the resulting damage is zero, we know that
                 * diffcore_count_changes() considers the two entries to
                 * be identical, but since the oid changed, we
                 * know that there must have been _some_ kind of change,
                 * so we force all entries to have damage > 0.
                 */
                damage = (p->one->size - copied) + added;
                if (!damage)
                        damage = 1;

found_damage:
                ALLOC_GROW(dir.files, dir.nr + 1, dir.alloc);
                dir.files[dir.nr].name = name;
                dir.files[dir.nr].changed = damage;
                changed += damage;
                dir.nr++;
        }

        /* This can happen even with many files, if everything was renames */
        if (!changed)
                return;

        /* Show all directories with more than x% of the changes */
        QSORT(dir.files, dir.nr, dirstat_compare);
        gather_dirstat(options, &dir, changed, "", 0);
}

static void show_dirstat_by_line(struct diffstat_t *data, struct diff_options *options)
{
        int i;
        unsigned long changed;
        struct dirstat_dir dir;

        if (data->nr == 0)
                return;

        dir.files = NULL;
        dir.alloc = 0;
        dir.nr = 0;
        dir.permille = options->dirstat_permille;
        dir.cumulative = options->flags.dirstat_cumulative;

        changed = 0;
        for (i = 0; i < data->nr; i++) {
                struct diffstat_file *file = data->files[i];
                unsigned long damage = file->added + file->deleted;
                if (file->is_binary)
                        /*
                         * binary files counts bytes, not lines. Must find some
                         * way to normalize binary bytes vs. textual lines.
                         * The following heuristic assumes that there are 64
                         * bytes per "line".
                         * This is stupid and ugly, but very cheap...
                         */
                        damage = DIV_ROUND_UP(damage, 64);
                ALLOC_GROW(dir.files, dir.nr + 1, dir.alloc);
                dir.files[dir.nr].name = file->name;
                dir.files[dir.nr].changed = damage;
                changed += damage;
                dir.nr++;
        }

        /* This can happen even with many files, if everything was renames */
        if (!changed)
                return;

        /* Show all directories with more than x% of the changes */
        QSORT(dir.files, dir.nr, dirstat_compare);
        gather_dirstat(options, &dir, changed, "", 0);
}

void free_diffstat_info(struct diffstat_t *diffstat)
{
        int i;
        for (i = 0; i < diffstat->nr; i++) {
                struct diffstat_file *f = diffstat->files[i];
                free(f->print_name);
                free(f->name);
                free(f->from_name);
                free(f);
        }
        free(diffstat->files);
}

struct checkdiff_t {
        const char *filename;
        int lineno;
        int conflict_marker_size;
        struct diff_options *o;
        unsigned ws_rule;
        unsigned status;
};

static int is_conflict_marker(const char *line, int marker_size, unsigned long len)
{
        char firstchar;
        int cnt;

        if (len < marker_size + 1)
                return 0;
        firstchar = line[0];
        switch (firstchar) {
        case '=': case '>': case '<': case '|':
                break;
        default:
                return 0;
        }
        for (cnt = 1; cnt < marker_size; cnt++)
                if (line[cnt] != firstchar)
                        return 0;
        /* line[1] through line[marker_size-1] are same as firstchar */
        if (len < marker_size + 1 || !isspace(line[marker_size]))
                return 0;
        return 1;
}

static void checkdiff_consume_hunk(void *priv,
                                   long ob, long on, long nb, long nn,
                                   const char *func, long funclen)

{
        struct checkdiff_t *data = priv;
        data->lineno = nb - 1;
}

static void checkdiff_consume(void *priv, char *line, unsigned long len)
{
        struct checkdiff_t *data = priv;
        int marker_size = data->conflict_marker_size;
        const char *ws = diff_get_color(data->o->use_color, DIFF_WHITESPACE);
        const char *reset = diff_get_color(data->o->use_color, DIFF_RESET);
        const char *set = diff_get_color(data->o->use_color, DIFF_FILE_NEW);
        char *err;
        const char *line_prefix;

        assert(data->o);
        line_prefix = diff_line_prefix(data->o);

        if (line[0] == '+') {
                unsigned bad;
                data->lineno++;
                if (is_conflict_marker(line + 1, marker_size, len - 1)) {
                        data->status |= 1;
                        fprintf(data->o->file,
                                "%s%s:%d: leftover conflict marker\n",
                                line_prefix, data->filename, data->lineno);
                }
                bad = ws_check(line + 1, len - 1, data->ws_rule);
                if (!bad)
                        return;
                data->status |= bad;
                err = whitespace_error_string(bad);
                fprintf(data->o->file, "%s%s:%d: %s.\n",
                        line_prefix, data->filename, data->lineno, err);
                free(err);
                emit_line(data->o, set, reset, line, 1);
                ws_check_emit(line + 1, len - 1, data->ws_rule,
                              data->o->file, set, reset, ws);
        } else if (line[0] == ' ') {
                data->lineno++;
        }
}

static unsigned char *deflate_it(char *data,
                                 unsigned long size,
                                 unsigned long *result_size)
{
        int bound;
        unsigned char *deflated;
        git_zstream stream;

        git_deflate_init(&stream, zlib_compression_level);
        bound = git_deflate_bound(&stream, size);
        deflated = xmalloc(bound);
        stream.next_out = deflated;
        stream.avail_out = bound;

        stream.next_in = (unsigned char *)data;
        stream.avail_in = size;
        while (git_deflate(&stream, Z_FINISH) == Z_OK)
                ; /* nothing */
        git_deflate_end(&stream);
        *result_size = stream.total_out;
        return deflated;
}

static void emit_binary_diff_body(struct diff_options *o,
                                  mmfile_t *one, mmfile_t *two)
{
        void *cp;
        void *delta;
        void *deflated;
        void *data;
        unsigned long orig_size;
        unsigned long delta_size;
        unsigned long deflate_size;
        unsigned long data_size;

        /* We could do deflated delta, or we could do just deflated two,
         * whichever is smaller.
         */
        delta = NULL;
        deflated = deflate_it(two->ptr, two->size, &deflate_size);
        if (one->size && two->size) {
                delta = diff_delta(one->ptr, one->size,
                                   two->ptr, two->size,
                                   &delta_size, deflate_size);
                if (delta) {
                        void *to_free = delta;
                        orig_size = delta_size;
                        delta = deflate_it(delta, delta_size, &delta_size);
                        free(to_free);
                }
        }

        if (delta && delta_size < deflate_size) {
                char *s = xstrfmt("%"PRIuMAX , (uintmax_t)orig_size);
                emit_diff_symbol(o, DIFF_SYMBOL_BINARY_DIFF_HEADER_DELTA,
                                 s, strlen(s), 0);
                free(s);
                free(deflated);
                data = delta;
                data_size = delta_size;
        } else {
                char *s = xstrfmt("%lu", two->size);
                emit_diff_symbol(o, DIFF_SYMBOL_BINARY_DIFF_HEADER_LITERAL,
                                 s, strlen(s), 0);
                free(s);
                free(delta);
                data = deflated;
                data_size = deflate_size;
        }

        /* emit data encoded in base85 */
        cp = data;
        while (data_size) {
                int len;
                int bytes = (52 < data_size) ? 52 : data_size;
                char line[71];
                data_size -= bytes;
                if (bytes <= 26)
                        line[0] = bytes + 'A' - 1;
                else
                        line[0] = bytes - 26 + 'a' - 1;
                encode_85(line + 1, cp, bytes);
                cp = (char *) cp + bytes;

                len = strlen(line);
                line[len++] = '\n';
                line[len] = '\0';

                emit_diff_symbol(o, DIFF_SYMBOL_BINARY_DIFF_BODY,
                                 line, len, 0);
        }
        emit_diff_symbol(o, DIFF_SYMBOL_BINARY_DIFF_FOOTER, NULL, 0, 0);
        free(data);
}

static void emit_binary_diff(struct diff_options *o,
                             mmfile_t *one, mmfile_t *two)
{
        emit_diff_symbol(o, DIFF_SYMBOL_BINARY_DIFF_HEADER, NULL, 0, 0);
        emit_binary_diff_body(o, one, two);
        emit_binary_diff_body(o, two, one);
}

int diff_filespec_is_binary(struct repository *r,
                            struct diff_filespec *one)
{
        if (one->is_binary == -1) {
                diff_filespec_load_driver(one, r->index);
                if (one->driver->binary != -1)
                        one->is_binary = one->driver->binary;
                else {
                        if (!one->data && DIFF_FILE_VALID(one))
                                diff_populate_filespec(r, one, CHECK_BINARY);
                        if (one->is_binary == -1 && one->data)
                                one->is_binary = buffer_is_binary(one->data,
                                                one->size);
                        if (one->is_binary == -1)
                                one->is_binary = 0;
                }
        }
        return one->is_binary;
}

static const struct userdiff_funcname *
diff_funcname_pattern(struct diff_options *o, struct diff_filespec *one)
{
        diff_filespec_load_driver(one, o->repo->index);
        return one->driver->funcname.pattern ? &one->driver->funcname : NULL;
}

void diff_set_mnemonic_prefix(struct diff_options *options, const char *a, const char *b)
{
        if (!options->a_prefix)
                options->a_prefix = a;
        if (!options->b_prefix)
                options->b_prefix = b;
}

struct userdiff_driver *get_textconv(struct repository *r,
                                     struct diff_filespec *one)
{
        if (!DIFF_FILE_VALID(one))
                return NULL;

        diff_filespec_load_driver(one, r->index);
        return userdiff_get_textconv(r, one->driver);
}

static void builtin_diff(const char *name_a,
                         const char *name_b,
                         struct diff_filespec *one,
                         struct diff_filespec *two,
                         const char *xfrm_msg,
                         int must_show_header,
                         struct diff_options *o,
                         int complete_rewrite)
{
        mmfile_t mf1, mf2;
        const char *lbl[2];
        char *a_one, *b_two;
        const char *meta = diff_get_color_opt(o, DIFF_METAINFO);
        const char *reset = diff_get_color_opt(o, DIFF_RESET);
        const char *a_prefix, *b_prefix;
        struct userdiff_driver *textconv_one = NULL;
        struct userdiff_driver *textconv_two = NULL;
        struct strbuf header = STRBUF_INIT;
        const char *line_prefix = diff_line_prefix(o);

        diff_set_mnemonic_prefix(o, "a/", "b/");
        if (o->flags.reverse_diff) {
                a_prefix = o->b_prefix;
                b_prefix = o->a_prefix;
        } else {
                a_prefix = o->a_prefix;
                b_prefix = o->b_prefix;
        }

        if (o->submodule_format == DIFF_SUBMODULE_LOG &&
            (!one->mode || S_ISGITLINK(one->mode)) &&
            (!two->mode || S_ISGITLINK(two->mode))) {
                show_submodule_summary(o, one->path ? one->path : two->path,
                                &one->oid, &two->oid,
                                two->dirty_submodule);
                return;
        } else if (o->submodule_format == DIFF_SUBMODULE_INLINE_DIFF &&
                   (!one->mode || S_ISGITLINK(one->mode)) &&
                   (!two->mode || S_ISGITLINK(two->mode))) {
                show_submodule_inline_diff(o, one->path ? one->path : two->path,
                                &one->oid, &two->oid,
                                two->dirty_submodule);
                return;
        }

        if (o->flags.allow_textconv) {
                textconv_one = get_textconv(o->repo, one);
                textconv_two = get_textconv(o->repo, two);
        }

        /* Never use a non-valid filename anywhere if at all possible */
        name_a = DIFF_FILE_VALID(one) ? name_a : name_b;
        name_b = DIFF_FILE_VALID(two) ? name_b : name_a;

        a_one = quote_two(a_prefix, name_a + (*name_a == '/'));
        b_two = quote_two(b_prefix, name_b + (*name_b == '/'));
        lbl[0] = DIFF_FILE_VALID(one) ? a_one : "/dev/null";
        lbl[1] = DIFF_FILE_VALID(two) ? b_two : "/dev/null";
        strbuf_addf(&header, "%s%sdiff --git %s %s%s\n", line_prefix, meta, a_one, b_two, reset);
        if (lbl[0][0] == '/') {
                /* /dev/null */
                strbuf_addf(&header, "%s%snew file mode %06o%s\n", line_prefix, meta, two->mode, reset);
                if (xfrm_msg)
                        strbuf_addstr(&header, xfrm_msg);
                must_show_header = 1;
        }
        else if (lbl[1][0] == '/') {
                strbuf_addf(&header, "%s%sdeleted file mode %06o%s\n", line_prefix, meta, one->mode, reset);
                if (xfrm_msg)
                        strbuf_addstr(&header, xfrm_msg);
                must_show_header = 1;
        }
        else {
                if (one->mode != two->mode) {
                        strbuf_addf(&header, "%s%sold mode %06o%s\n", line_prefix, meta, one->mode, reset);
                        strbuf_addf(&header, "%s%snew mode %06o%s\n", line_prefix, meta, two->mode, reset);
                        must_show_header = 1;
                }
                if (xfrm_msg)
                        strbuf_addstr(&header, xfrm_msg);

                /*
                 * we do not run diff between different kind
                 * of objects.
                 */
                if ((one->mode ^ two->mode) & S_IFMT)
                        goto free_ab_and_return;
                if (complete_rewrite &&
                    (textconv_one || !diff_filespec_is_binary(o->repo, one)) &&
                    (textconv_two || !diff_filespec_is_binary(o->repo, two))) {
                        emit_diff_symbol(o, DIFF_SYMBOL_HEADER,
                                         header.buf, header.len, 0);
                        strbuf_reset(&header);
                        emit_rewrite_diff(name_a, name_b, one, two,
                                          textconv_one, textconv_two, o);
                        o->found_changes = 1;
                        goto free_ab_and_return;
                }
        }

        if (o->irreversible_delete && lbl[1][0] == '/') {
                emit_diff_symbol(o, DIFF_SYMBOL_HEADER, header.buf,
                                 header.len, 0);
                strbuf_reset(&header);
                goto free_ab_and_return;
        } else if (!o->flags.text &&
                   ( (!textconv_one && diff_filespec_is_binary(o->repo, one)) ||
                     (!textconv_two && diff_filespec_is_binary(o->repo, two)) )) {
                struct strbuf sb = STRBUF_INIT;
                if (!one->data && !two->data &&
                    S_ISREG(one->mode) && S_ISREG(two->mode) &&
                    !o->flags.binary) {
                        if (oideq(&one->oid, &two->oid)) {
                                if (must_show_header)
                                        emit_diff_symbol(o, DIFF_SYMBOL_HEADER,
                                                         header.buf, header.len,
                                                         0);
                                goto free_ab_and_return;
                        }
                        emit_diff_symbol(o, DIFF_SYMBOL_HEADER,
                                         header.buf, header.len, 0);
                        strbuf_addf(&sb, "%sBinary files %s and %s differ\n",
                                    diff_line_prefix(o), lbl[0], lbl[1]);
                        emit_diff_symbol(o, DIFF_SYMBOL_BINARY_FILES,
                                         sb.buf, sb.len, 0);
                        strbuf_release(&sb);
                        goto free_ab_and_return;
                }
                if (fill_mmfile(o->repo, &mf1, one) < 0 ||
                    fill_mmfile(o->repo, &mf2, two) < 0)
                        die("unable to read files to diff");
                /* Quite common confusing case */
                if (mf1.size == mf2.size &&
                    !memcmp(mf1.ptr, mf2.ptr, mf1.size)) {
                        if (must_show_header)
                                emit_diff_symbol(o, DIFF_SYMBOL_HEADER,
                                                 header.buf, header.len, 0);
                        goto free_ab_and_return;
                }
                emit_diff_symbol(o, DIFF_SYMBOL_HEADER, header.buf, header.len, 0);
                strbuf_reset(&header);
                if (o->flags.binary)
                        emit_binary_diff(o, &mf1, &mf2);
                else {
                        strbuf_addf(&sb, "%sBinary files %s and %s differ\n",
                                    diff_line_prefix(o), lbl[0], lbl[1]);
                        emit_diff_symbol(o, DIFF_SYMBOL_BINARY_FILES,
                                         sb.buf, sb.len, 0);
                        strbuf_release(&sb);
                }
                o->found_changes = 1;
        } else {
                /* Crazy xdl interfaces.. */
                const char *diffopts;
                const char *v;
                xpparam_t xpp;
                xdemitconf_t xecfg;
                struct emit_callback ecbdata;
                const struct userdiff_funcname *pe;

                if (must_show_header) {
                        emit_diff_symbol(o, DIFF_SYMBOL_HEADER,
                                         header.buf, header.len, 0);
                        strbuf_reset(&header);
                }

                mf1.size = fill_textconv(o->repo, textconv_one, one, &mf1.ptr);
                mf2.size = fill_textconv(o->repo, textconv_two, two, &mf2.ptr);

                pe = diff_funcname_pattern(o, one);
                if (!pe)
                        pe = diff_funcname_pattern(o, two);

                memset(&xpp, 0, sizeof(xpp));
                memset(&xecfg, 0, sizeof(xecfg));
                memset(&ecbdata, 0, sizeof(ecbdata));
                if (o->flags.suppress_diff_headers)
                        lbl[0] = NULL;
                ecbdata.label_path = lbl;
                ecbdata.color_diff = want_color(o->use_color);
                ecbdata.ws_rule = whitespace_rule(o->repo->index, name_b);
                if (ecbdata.ws_rule & WS_BLANK_AT_EOF)
                        check_blank_at_eof(&mf1, &mf2, &ecbdata);
                ecbdata.opt = o;
                if (header.len && !o->flags.suppress_diff_headers)
                        ecbdata.header = &header;
                xpp.flags = o->xdl_opts;
                xpp.anchors = o->anchors;
                xpp.anchors_nr = o->anchors_nr;
                xecfg.ctxlen = o->context;
                xecfg.interhunkctxlen = o->interhunkcontext;
                xecfg.flags = XDL_EMIT_FUNCNAMES;
                if (o->flags.funccontext)
                        xecfg.flags |= XDL_EMIT_FUNCCONTEXT;
                if (pe)
                        xdiff_set_find_func(&xecfg, pe->pattern, pe->cflags);

                diffopts = getenv("GIT_DIFF_OPTS");
                if (!diffopts)
                        ;
                else if (skip_prefix(diffopts, "--unified=", &v))
                        xecfg.ctxlen = strtoul(v, NULL, 10);
                else if (skip_prefix(diffopts, "-u", &v))
                        xecfg.ctxlen = strtoul(v, NULL, 10);

                if (o->word_diff)
                        init_diff_words_data(&ecbdata, o, one, two);
                if (xdi_diff_outf(&mf1, &mf2, NULL, fn_out_consume,
                                  &ecbdata, &xpp, &xecfg))
                        die("unable to generate diff for %s", one->path);
                if (o->word_diff)
                        free_diff_words_data(&ecbdata);
                if (textconv_one)
                        free(mf1.ptr);
                if (textconv_two)
                        free(mf2.ptr);
                xdiff_clear_find_func(&xecfg);
        }

 free_ab_and_return:
        strbuf_release(&header);
        diff_free_filespec_data(one);
        diff_free_filespec_data(two);
        free(a_one);
        free(b_two);
        return;
}

static char *get_compact_summary(const struct diff_filepair *p, int is_renamed)
{
        if (!is_renamed) {
                if (p->status == DIFF_STATUS_ADDED) {
                        if (S_ISLNK(p->two->mode))
                                return "new +l";
                        else if ((p->two->mode & 0777) == 0755)
                                return "new +x";
                        else
                                return "new";
                } else if (p->status == DIFF_STATUS_DELETED)
                        return "gone";
        }
        if (S_ISLNK(p->one->mode) && !S_ISLNK(p->two->mode))
                return "mode -l";
        else if (!S_ISLNK(p->one->mode) && S_ISLNK(p->two->mode))
                return "mode +l";
        else if ((p->one->mode & 0777) == 0644 &&
                 (p->two->mode & 0777) == 0755)
                return "mode +x";
        else if ((p->one->mode & 0777) == 0755 &&
                 (p->two->mode & 0777) == 0644)
                return "mode -x";
        return NULL;
}

static void builtin_diffstat(const char *name_a, const char *name_b,
                             struct diff_filespec *one,
                             struct diff_filespec *two,
                             struct diffstat_t *diffstat,
                             struct diff_options *o,
                             struct diff_filepair *p)
{
        mmfile_t mf1, mf2;
        struct diffstat_file *data;
        int same_contents;
        int complete_rewrite = 0;

        if (!DIFF_PAIR_UNMERGED(p)) {
                if (p->status == DIFF_STATUS_MODIFIED && p->score)
                        complete_rewrite = 1;
        }

        data = diffstat_add(diffstat, name_a, name_b);
        data->is_interesting = p->status != DIFF_STATUS_UNKNOWN;
        if (o->flags.stat_with_summary)
                data->comments = get_compact_summary(p, data->is_renamed);

        if (!one || !two) {
                data->is_unmerged = 1;
                return;
        }

        same_contents = oideq(&one->oid, &two->oid);

        if (diff_filespec_is_binary(o->repo, one) ||
            diff_filespec_is_binary(o->repo, two)) {
                data->is_binary = 1;
                if (same_contents) {
                        data->added = 0;
                        data->deleted = 0;
                } else {
                        data->added = diff_filespec_size(o->repo, two);
                        data->deleted = diff_filespec_size(o->repo, one);
                }
        }

        else if (complete_rewrite) {
                diff_populate_filespec(o->repo, one, 0);
                diff_populate_filespec(o->repo, two, 0);
                data->deleted = count_lines(one->data, one->size);
                data->added = count_lines(two->data, two->size);
        }

        else if (!same_contents) {
                /* Crazy xdl interfaces.. */
                xpparam_t xpp;
                xdemitconf_t xecfg;

                if (fill_mmfile(o->repo, &mf1, one) < 0 ||
                    fill_mmfile(o->repo, &mf2, two) < 0)
                        die("unable to read files to diff");

                memset(&xpp, 0, sizeof(xpp));
                memset(&xecfg, 0, sizeof(xecfg));
                xpp.flags = o->xdl_opts;
                xpp.anchors = o->anchors;
                xpp.anchors_nr = o->anchors_nr;
                xecfg.ctxlen = o->context;
                xecfg.interhunkctxlen = o->interhunkcontext;
                if (xdi_diff_outf(&mf1, &mf2, discard_hunk_line,
                                  diffstat_consume, diffstat, &xpp, &xecfg))
                        die("unable to generate diffstat for %s", one->path);
        }

        diff_free_filespec_data(one);
        diff_free_filespec_data(two);
}

static void builtin_checkdiff(const char *name_a, const char *name_b,
                              const char *attr_path,
                              struct diff_filespec *one,
                              struct diff_filespec *two,
                              struct diff_options *o)
{
        mmfile_t mf1, mf2;
        struct checkdiff_t data;

        if (!two)
                return;

        memset(&data, 0, sizeof(data));
        data.filename = name_b ? name_b : name_a;
        data.lineno = 0;
        data.o = o;
        data.ws_rule = whitespace_rule(o->repo->index, attr_path);
        data.conflict_marker_size = ll_merge_marker_size(o->repo->index, attr_path);

        if (fill_mmfile(o->repo, &mf1, one) < 0 ||
            fill_mmfile(o->repo, &mf2, two) < 0)
                die("unable to read files to diff");

        /*
         * All the other codepaths check both sides, but not checking
         * the "old" side here is deliberate.  We are checking the newly
         * introduced changes, and as long as the "new" side is text, we
         * can and should check what it introduces.
         */
        if (diff_filespec_is_binary(o->repo, two))
                goto free_and_return;
        else {
                /* Crazy xdl interfaces.. */
                xpparam_t xpp;
                xdemitconf_t xecfg;

                memset(&xpp, 0, sizeof(xpp));
                memset(&xecfg, 0, sizeof(xecfg));
                xecfg.ctxlen = 1; /* at least one context line */
                xpp.flags = 0;
                if (xdi_diff_outf(&mf1, &mf2, checkdiff_consume_hunk,
                                  checkdiff_consume, &data,
                                  &xpp, &xecfg))
                        die("unable to generate checkdiff for %s", one->path);

                if (data.ws_rule & WS_BLANK_AT_EOF) {
                        struct emit_callback ecbdata;
                        int blank_at_eof;

                        ecbdata.ws_rule = data.ws_rule;
                        check_blank_at_eof(&mf1, &mf2, &ecbdata);
                        blank_at_eof = ecbdata.blank_at_eof_in_postimage;

                        if (blank_at_eof) {
                                static char *err;
                                if (!err)
                                        err = whitespace_error_string(WS_BLANK_AT_EOF);
                                fprintf(o->file, "%s:%d: %s.\n",
                                        data.filename, blank_at_eof, err);
                                data.status = 1; /* report errors */
                        }
                }
        }
 free_and_return:
        diff_free_filespec_data(one);
        diff_free_filespec_data(two);
        if (data.status)
                o->flags.check_failed = 1;
}

struct diff_filespec *alloc_filespec(const char *path)
{
        struct diff_filespec *spec;

        FLEXPTR_ALLOC_STR(spec, path, path);
        spec->count = 1;
        spec->is_binary = -1;
        return spec;
}

void free_filespec(struct diff_filespec *spec)
{
        if (!--spec->count) {
                diff_free_filespec_data(spec);
                free(spec);
        }
}

void fill_filespec(struct diff_filespec *spec, const struct object_id *oid,
                   int oid_valid, unsigned short mode)
{
        if (mode) {
                spec->mode = canon_mode(mode);
                oidcpy(&spec->oid, oid);
                spec->oid_valid = oid_valid;
        }
}

/*
 * Given a name and sha1 pair, if the index tells us the file in
 * the work tree has that object contents, return true, so that
 * prepare_temp_file() does not have to inflate and extract.
 */
static int reuse_worktree_file(struct index_state *istate,
                               const char *name,
                               const struct object_id *oid,
                               int want_file)
{
        const struct cache_entry *ce;
        struct stat st;
        int pos, len;

        /*
         * We do not read the cache ourselves here, because the
         * benchmark with my previous version that always reads cache
         * shows that it makes things worse for diff-tree comparing
         * two linux-2.6 kernel trees in an already checked out work
         * tree.  This is because most diff-tree comparisons deal with
         * only a small number of files, while reading the cache is
         * expensive for a large project, and its cost outweighs the
         * savings we get by not inflating the object to a temporary
         * file.  Practically, this code only helps when we are used
         * by diff-cache --cached, which does read the cache before
         * calling us.
         */
        if (!istate->cache)
                return 0;

        /* We want to avoid the working directory if our caller
         * doesn't need the data in a normal file, this system
         * is rather slow with its stat/open/mmap/close syscalls,
         * and the object is contained in a pack file.  The pack
         * is probably already open and will be faster to obtain
         * the data through than the working directory.  Loose
         * objects however would tend to be slower as they need
         * to be individually opened and inflated.
         */
        if (!FAST_WORKING_DIRECTORY && !want_file && has_object_pack(oid))
                return 0;

        /*
         * Similarly, if we'd have to convert the file contents anyway, that
         * makes the optimization not worthwhile.
         */
        if (!want_file && would_convert_to_git(istate, name))
                return 0;

        len = strlen(name);
        pos = index_name_pos(istate, name, len);
        if (pos < 0)
                return 0;
        ce = istate->cache[pos];

        /*
         * This is not the sha1 we are looking for, or
         * unreusable because it is not a regular file.
         */
        if (!oideq(oid, &ce->oid) || !S_ISREG(ce->ce_mode))
                return 0;

        /*
         * If ce is marked as "assume unchanged", there is no
         * guarantee that work tree matches what we are looking for.
         */
        if ((ce->ce_flags & CE_VALID) || ce_skip_worktree(ce))
                return 0;

        /*
         * If ce matches the file in the work tree, we can reuse it.
         */
        if (ce_uptodate(ce) ||
            (!lstat(name, &st) && !ie_match_stat(istate, ce, &st, 0)))
                return 1;

        return 0;
}

static int diff_populate_gitlink(struct diff_filespec *s, int size_only)
{
        struct strbuf buf = STRBUF_INIT;
        char *dirty = "";

        /* Are we looking at the work tree? */
        if (s->dirty_submodule)
                dirty = "-dirty";

        strbuf_addf(&buf, "Subproject commit %s%s\n",
                    oid_to_hex(&s->oid), dirty);
        s->size = buf.len;
        if (size_only) {
                s->data = NULL;
                strbuf_release(&buf);
        } else {
                s->data = strbuf_detach(&buf, NULL);
                s->should_free = 1;
        }
        return 0;
}

/*
 * While doing rename detection and pickaxe operation, we may need to
 * grab the data for the blob (or file) for our own in-core comparison.
 * diff_filespec has data and size fields for this purpose.
 */
int diff_populate_filespec(struct repository *r,
                           struct diff_filespec *s,
                           unsigned int flags)
{
        int size_only = flags & CHECK_SIZE_ONLY;
        int err = 0;
        int conv_flags = global_conv_flags_eol;
        /*
         * demote FAIL to WARN to allow inspecting the situation
         * instead of refusing.
         */
        if (conv_flags & CONV_EOL_RNDTRP_DIE)
                conv_flags = CONV_EOL_RNDTRP_WARN;

        if (!DIFF_FILE_VALID(s))
                die("internal error: asking to populate invalid file.");
        if (S_ISDIR(s->mode))
                return -1;

        if (s->data)
                return 0;

        if (size_only && 0 < s->size)
                return 0;

        if (S_ISGITLINK(s->mode))
                return diff_populate_gitlink(s, size_only);

        if (!s->oid_valid ||
            reuse_worktree_file(r->index, s->path, &s->oid, 0)) {
                struct strbuf buf = STRBUF_INIT;
                struct stat st;
                int fd;

                if (lstat(s->path, &st) < 0) {
                err_empty:
                        err = -1;
                empty:
                        s->data = (char *)"";
                        s->size = 0;
                        return err;
                }
                s->size = xsize_t(st.st_size);
                if (!s->size)
                        goto empty;
                if (S_ISLNK(st.st_mode)) {
                        struct strbuf sb = STRBUF_INIT;

                        if (strbuf_readlink(&sb, s->path, s->size))
                                goto err_empty;
                        s->size = sb.len;
                        s->data = strbuf_detach(&sb, NULL);
                        s->should_free = 1;
                        return 0;
                }

                /*
                 * Even if the caller would be happy with getting
                 * only the size, we cannot return early at this
                 * point if the path requires us to run the content
                 * conversion.
                 */
                if (size_only && !would_convert_to_git(r->index, s->path))
                        return 0;

                /*
                 * Note: this check uses xsize_t(st.st_size) that may
                 * not be the true size of the blob after it goes
                 * through convert_to_git().  This may not strictly be
                 * correct, but the whole point of big_file_threshold
                 * and is_binary check being that we want to avoid
                 * opening the file and inspecting the contents, this
                 * is probably fine.
                 */
                if ((flags & CHECK_BINARY) &&
                    s->size > big_file_threshold && s->is_binary == -1) {
                        s->is_binary = 1;
                        return 0;
                }
                fd = open(s->path, O_RDONLY);
                if (fd < 0)
                        goto err_empty;
                s->data = xmmap(NULL, s->size, PROT_READ, MAP_PRIVATE, fd, 0);
                close(fd);
                s->should_munmap = 1;

                /*
                 * Convert from working tree format to canonical git format
                 */
                if (convert_to_git(r->index, s->path, s->data, s->size, &buf, conv_flags)) {
                        size_t size = 0;
                        munmap(s->data, s->size);
                        s->should_munmap = 0;
                        s->data = strbuf_detach(&buf, &size);
                        s->size = size;
                        s->should_free = 1;
                }
        }
        else {
                enum object_type type;
                if (size_only || (flags & CHECK_BINARY)) {
                        type = oid_object_info(r, &s->oid, &s->size);
                        if (type < 0)
                                die("unable to read %s",
                                    oid_to_hex(&s->oid));
                        if (size_only)
                                return 0;
                        if (s->size > big_file_threshold && s->is_binary == -1) {
                                s->is_binary = 1;
                                return 0;
                        }
                }
                s->data = read_object_file(&s->oid, &type, &s->size);
                if (!s->data)
                        die("unable to read %s", oid_to_hex(&s->oid));
                s->should_free = 1;
        }
        return 0;
}

void diff_free_filespec_blob(struct diff_filespec *s)
{
        if (s->should_free)
                free(s->data);
        else if (s->should_munmap)
                munmap(s->data, s->size);

        if (s->should_free || s->should_munmap) {
                s->should_free = s->should_munmap = 0;
                s->data = NULL;
        }
}

void diff_free_filespec_data(struct diff_filespec *s)
{
        diff_free_filespec_blob(s);
        FREE_AND_NULL(s->cnt_data);
}

static void prep_temp_blob(struct index_state *istate,
                           const char *path, struct diff_tempfile *temp,
                           void *blob,
                           unsigned long size,
                           const struct object_id *oid,
                           int mode)
{
        struct strbuf buf = STRBUF_INIT;
        struct strbuf tempfile = STRBUF_INIT;
        char *path_dup = xstrdup(path);
        const char *base = basename(path_dup);

        /* Generate "XXXXXX_basename.ext" */
        strbuf_addstr(&tempfile, "XXXXXX_");
        strbuf_addstr(&tempfile, base);

        temp->tempfile = mks_tempfile_ts(tempfile.buf, strlen(base) + 1);
        if (!temp->tempfile)
                die_errno("unable to create temp-file");
        if (convert_to_working_tree(istate, path,
                        (const char *)blob, (size_t)size, &buf)) {
                blob = buf.buf;
                size = buf.len;
        }
        if (write_in_full(temp->tempfile->fd, blob, size) < 0 ||
            close_tempfile_gently(temp->tempfile))
                die_errno("unable to write temp-file");
        temp->name = get_tempfile_path(temp->tempfile);
        oid_to_hex_r(temp->hex, oid);
        xsnprintf(temp->mode, sizeof(temp->mode), "%06o", mode);
        strbuf_release(&buf);
        strbuf_release(&tempfile);
        free(path_dup);
}

static struct diff_tempfile *prepare_temp_file(struct repository *r,
                                               const char *name,
                                               struct diff_filespec *one)
{
        struct diff_tempfile *temp = claim_diff_tempfile();

        if (!DIFF_FILE_VALID(one)) {
        not_a_valid_file:
                /* A '-' entry produces this for file-2, and
                 * a '+' entry produces this for file-1.
                 */
                temp->name = "/dev/null";
                xsnprintf(temp->hex, sizeof(temp->hex), ".");
                xsnprintf(temp->mode, sizeof(temp->mode), ".");
                return temp;
        }

        if (!S_ISGITLINK(one->mode) &&
            (!one->oid_valid ||
             reuse_worktree_file(r->index, name, &one->oid, 1))) {
                struct stat st;
                if (lstat(name, &st) < 0) {
                        if (errno == ENOENT)
                                goto not_a_valid_file;
                        die_errno("stat(%s)", name);
                }
                if (S_ISLNK(st.st_mode)) {
                        struct strbuf sb = STRBUF_INIT;
                        if (strbuf_readlink(&sb, name, st.st_size) < 0)
                                die_errno("readlink(%s)", name);
                        prep_temp_blob(r->index, name, temp, sb.buf, sb.len,
                                       (one->oid_valid ?
                                        &one->oid : &null_oid),
                                       (one->oid_valid ?
                                        one->mode : S_IFLNK));
                        strbuf_release(&sb);
                }
                else {
                        /* we can borrow from the file in the work tree */
                        temp->name = name;
                        if (!one->oid_valid)
                                oid_to_hex_r(temp->hex, &null_oid);
                        else
                                oid_to_hex_r(temp->hex, &one->oid);
                        /* Even though we may sometimes borrow the
                         * contents from the work tree, we always want
                         * one->mode.  mode is trustworthy even when
                         * !(one->oid_valid), as long as
                         * DIFF_FILE_VALID(one).
                         */
                        xsnprintf(temp->mode, sizeof(temp->mode), "%06o", one->mode);
                }
                return temp;
        }
        else {
                if (diff_populate_filespec(r, one, 0))
                        die("cannot read data blob for %s", one->path);
                prep_temp_blob(r->index, name, temp,
                               one->data, one->size,
                               &one->oid, one->mode);
        }
        return temp;
}

static void add_external_diff_name(struct repository *r,
                                   struct argv_array *argv,
                                   const char *name,
                                   struct diff_filespec *df)
{
        struct diff_tempfile *temp = prepare_temp_file(r, name, df);
        argv_array_push(argv, temp->name);
        argv_array_push(argv, temp->hex);
        argv_array_push(argv, temp->mode);
}

/* An external diff command takes:
 *
 * diff-cmd name infile1 infile1-sha1 infile1-mode \
 *               infile2 infile2-sha1 infile2-mode [ rename-to ]
 *
 */
static void run_external_diff(const char *pgm,
                              const char *name,
                              const char *other,
                              struct diff_filespec *one,
                              struct diff_filespec *two,
                              const char *xfrm_msg,
                              struct diff_options *o)
{
        struct argv_array argv = ARGV_ARRAY_INIT;
        struct argv_array env = ARGV_ARRAY_INIT;
        struct diff_queue_struct *q = &diff_queued_diff;

        argv_array_push(&argv, pgm);
        argv_array_push(&argv, name);

        if (one && two) {
                add_external_diff_name(o->repo, &argv, name, one);
                if (!other)
                        add_external_diff_name(o->repo, &argv, name, two);
                else {
                        add_external_diff_name(o->repo, &argv, other, two);
                        argv_array_push(&argv, other);
                        argv_array_push(&argv, xfrm_msg);
                }
        }

        argv_array_pushf(&env, "GIT_DIFF_PATH_COUNTER=%d", ++o->diff_path_counter);
        argv_array_pushf(&env, "GIT_DIFF_PATH_TOTAL=%d", q->nr);

        diff_free_filespec_data(one);
        diff_free_filespec_data(two);
        if (run_command_v_opt_cd_env(argv.argv, RUN_USING_SHELL, NULL, env.argv))
                die(_("external diff died, stopping at %s"), name);

        remove_tempfile();
        argv_array_clear(&argv);
        argv_array_clear(&env);
}

static int similarity_index(struct diff_filepair *p)
{
        return p->score * 100 / MAX_SCORE;
}

static const char *diff_abbrev_oid(const struct object_id *oid, int abbrev)
{
        if (startup_info->have_repository)
                return find_unique_abbrev(oid, abbrev);
        else {
                char *hex = oid_to_hex(oid);
                if (abbrev < 0)
                        abbrev = FALLBACK_DEFAULT_ABBREV;
                if (abbrev > the_hash_algo->hexsz)
                        BUG("oid abbreviation out of range: %d", abbrev);
                if (abbrev)
                        hex[abbrev] = '\0';
                return hex;
        }
}

static void fill_metainfo(struct strbuf *msg,
                          const char *name,
                          const char *other,
                          struct diff_filespec *one,
                          struct diff_filespec *two,
                          struct diff_options *o,
                          struct diff_filepair *p,
                          int *must_show_header,
                          int use_color)
{
        const char *set = diff_get_color(use_color, DIFF_METAINFO);
        const char *reset = diff_get_color(use_color, DIFF_RESET);
        const char *line_prefix = diff_line_prefix(o);

        *must_show_header = 1;
        strbuf_init(msg, PATH_MAX * 2 + 300);
        switch (p->status) {
        case DIFF_STATUS_COPIED:
                strbuf_addf(msg, "%s%ssimilarity index %d%%",
                            line_prefix, set, similarity_index(p));
                strbuf_addf(msg, "%s\n%s%scopy from ",
                            reset,  line_prefix, set);
                quote_c_style(name, msg, NULL, 0);
                strbuf_addf(msg, "%s\n%s%scopy to ", reset, line_prefix, set);
                quote_c_style(other, msg, NULL, 0);
                strbuf_addf(msg, "%s\n", reset);
                break;
        case DIFF_STATUS_RENAMED:
                strbuf_addf(msg, "%s%ssimilarity index %d%%",
                            line_prefix, set, similarity_index(p));
                strbuf_addf(msg, "%s\n%s%srename from ",
                            reset, line_prefix, set);
                quote_c_style(name, msg, NULL, 0);
                strbuf_addf(msg, "%s\n%s%srename to ",
                            reset, line_prefix, set);
                quote_c_style(other, msg, NULL, 0);
                strbuf_addf(msg, "%s\n", reset);
                break;
        case DIFF_STATUS_MODIFIED:
                if (p->score) {
                        strbuf_addf(msg, "%s%sdissimilarity index %d%%%s\n",
                                    line_prefix,
                                    set, similarity_index(p), reset);
                        break;
                }
                /* fallthru */
        default:
                *must_show_header = 0;
        }
        if (one && two && !oideq(&one->oid, &two->oid)) {
                const unsigned hexsz = the_hash_algo->hexsz;
                int abbrev = o->flags.full_index ? hexsz : DEFAULT_ABBREV;

                if (o->flags.binary) {
                        mmfile_t mf;
                        if ((!fill_mmfile(o->repo, &mf, one) &&
                             diff_filespec_is_binary(o->repo, one)) ||
                            (!fill_mmfile(o->repo, &mf, two) &&
                             diff_filespec_is_binary(o->repo, two)))
                                abbrev = hexsz;
                }
                strbuf_addf(msg, "%s%sindex %s..%s", line_prefix, set,
                            diff_abbrev_oid(&one->oid, abbrev),
                            diff_abbrev_oid(&two->oid, abbrev));
                if (one->mode == two->mode)
                        strbuf_addf(msg, " %06o", one->mode);
                strbuf_addf(msg, "%s\n", reset);
        }
}

static void run_diff_cmd(const char *pgm,
                         const char *name,
                         const char *other,
                         const char *attr_path,
                         struct diff_filespec *one,
                         struct diff_filespec *two,
                         struct strbuf *msg,
                         struct diff_options *o,
                         struct diff_filepair *p)
{
        const char *xfrm_msg = NULL;
        int complete_rewrite = (p->status == DIFF_STATUS_MODIFIED) && p->score;
        int must_show_header = 0;


        if (o->flags.allow_external) {
                struct userdiff_driver *drv;

                drv = userdiff_find_by_path(o->repo->index, attr_path);
                if (drv && drv->external)
                        pgm = drv->external;
        }

        if (msg) {
                /*
                 * don't use colors when the header is intended for an
                 * external diff driver
                 */
                fill_metainfo(msg, name, other, one, two, o, p,
                              &must_show_header,
                              want_color(o->use_color) && !pgm);
                xfrm_msg = msg->len ? msg->buf : NULL;
        }

        if (pgm) {
                run_external_diff(pgm, name, other, one, two, xfrm_msg, o);
                return;
        }
        if (one && two)
                builtin_diff(name, other ? other : name,
                             one, two, xfrm_msg, must_show_header,
                             o, complete_rewrite);
        else
                fprintf(o->file, "* Unmerged path %s\n", name);
}

static void diff_fill_oid_info(struct diff_filespec *one, struct index_state *istate)
{
        if (DIFF_FILE_VALID(one)) {
                if (!one->oid_valid) {
                        struct stat st;
                        if (one->is_stdin) {
                                oidclr(&one->oid);
                                return;
                        }
                        if (lstat(one->path, &st) < 0)
                                die_errno("stat '%s'", one->path);
                        if (index_path(istate, &one->oid, one->path, &st, 0))
                                die("cannot hash %s", one->path);
                }
        }
        else
                oidclr(&one->oid);
}

static void strip_prefix(int prefix_length, const char **namep, const char **otherp)
{
        /* Strip the prefix but do not molest /dev/null and absolute paths */
        if (*namep && !is_absolute_path(*namep)) {
                *namep += prefix_length;
                if (**namep == '/')
                        ++*namep;
        }
        if (*otherp && !is_absolute_path(*otherp)) {
                *otherp += prefix_length;
                if (**otherp == '/')
                        ++*otherp;
        }
}

static void run_diff(struct diff_filepair *p, struct diff_options *o)
{
        const char *pgm = external_diff();
        struct strbuf msg;
        struct diff_filespec *one = p->one;
        struct diff_filespec *two = p->two;
        const char *name;
        const char *other;
        const char *attr_path;

        name  = one->path;
        other = (strcmp(name, two->path) ? two->path : NULL);
        attr_path = name;
        if (o->prefix_length)
                strip_prefix(o->prefix_length, &name, &other);

        if (!o->flags.allow_external)
                pgm = NULL;

        if (DIFF_PAIR_UNMERGED(p)) {
                run_diff_cmd(pgm, name, NULL, attr_path,
                             NULL, NULL, NULL, o, p);
                return;
        }

        diff_fill_oid_info(one, o->repo->index);
        diff_fill_oid_info(two, o->repo->index);

        if (!pgm &&
            DIFF_FILE_VALID(one) && DIFF_FILE_VALID(two) &&
            (S_IFMT & one->mode) != (S_IFMT & two->mode)) {
                /*
                 * a filepair that changes between file and symlink
                 * needs to be split into deletion and creation.
                 */
                struct diff_filespec *null = alloc_filespec(two->path);
                run_diff_cmd(NULL, name, other, attr_path,
                             one, null, &msg,
                             o, p);
                free(null);
                strbuf_release(&msg);

                null = alloc_filespec(one->path);
                run_diff_cmd(NULL, name, other, attr_path,
                             null, two, &msg, o, p);
                free(null);
        }
        else
                run_diff_cmd(pgm, name, other, attr_path,
                             one, two, &msg, o, p);

        strbuf_release(&msg);
}

static void run_diffstat(struct diff_filepair *p, struct diff_options *o,
                         struct diffstat_t *diffstat)
{
        const char *name;
        const char *other;

        if (DIFF_PAIR_UNMERGED(p)) {
                /* unmerged */
                builtin_diffstat(p->one->path, NULL, NULL, NULL,
                                 diffstat, o, p);
                return;
        }

        name = p->one->path;
        other = (strcmp(name, p->two->path) ? p->two->path : NULL);

        if (o->prefix_length)
                strip_prefix(o->prefix_length, &name, &other);

        diff_fill_oid_info(p->one, o->repo->index);
        diff_fill_oid_info(p->two, o->repo->index);

        builtin_diffstat(name, other, p->one, p->two,
                         diffstat, o, p);
}

static void run_checkdiff(struct diff_filepair *p, struct diff_options *o)
{
        const char *name;
        const char *other;
        const char *attr_path;

        if (DIFF_PAIR_UNMERGED(p)) {
                /* unmerged */
                return;
        }

        name = p->one->path;
        other = (strcmp(name, p->two->path) ? p->two->path : NULL);
        attr_path = other ? other : name;

        if (o->prefix_length)
                strip_prefix(o->prefix_length, &name, &other);

        diff_fill_oid_info(p->one, o->repo->index);
        diff_fill_oid_info(p->two, o->repo->index);

        builtin_checkdiff(name, other, attr_path, p->one, p->two, o);
}

static void prep_parse_options(struct diff_options *options);

void repo_diff_setup(struct repository *r, struct diff_options *options)
{
        memcpy(options, &default_diff_options, sizeof(*options));

        options->file = stdout;
        options->repo = r;

        options->output_indicators[OUTPUT_INDICATOR_NEW] = '+';
        options->output_indicators[OUTPUT_INDICATOR_OLD] = '-';
        options->output_indicators[OUTPUT_INDICATOR_CONTEXT] = ' ';
        options->abbrev = DEFAULT_ABBREV;
        options->line_termination = '\n';
        options->break_opt = -1;
        options->rename_limit = -1;
        options->dirstat_permille = diff_dirstat_permille_default;
        options->context = diff_context_default;
        options->interhunkcontext = diff_interhunk_context_default;
        options->ws_error_highlight = ws_error_highlight_default;
        options->flags.rename_empty = 1;
        options->objfind = NULL;

        /* pathchange left =NULL by default */
        options->change = diff_change;
        options->add_remove = diff_addremove;
        options->use_color = diff_use_color_default;
        options->detect_rename = diff_detect_rename_default;
        options->xdl_opts |= diff_algorithm;
        if (diff_indent_heuristic)
                DIFF_XDL_SET(options, INDENT_HEURISTIC);

        options->orderfile = diff_order_file_cfg;

        if (diff_no_prefix) {
                options->a_prefix = options->b_prefix = "";
        } else if (!diff_mnemonic_prefix) {
                options->a_prefix = "a/";
                options->b_prefix = "b/";
        }

        options->color_moved = diff_color_moved_default;
        options->color_moved_ws_handling = diff_color_moved_ws_default;

        prep_parse_options(options);
}

void diff_setup_done(struct diff_options *options)
{
        unsigned check_mask = DIFF_FORMAT_NAME |
                              DIFF_FORMAT_NAME_STATUS |
                              DIFF_FORMAT_CHECKDIFF |
                              DIFF_FORMAT_NO_OUTPUT;
        /*
         * This must be signed because we're comparing against a potentially
         * negative value.
         */
        const int hexsz = the_hash_algo->hexsz;

        if (options->set_default)
                options->set_default(options);

        if (HAS_MULTI_BITS(options->output_format & check_mask))
                die(_("--name-only, --name-status, --check and -s are mutually exclusive"));

        if (HAS_MULTI_BITS(options->pickaxe_opts & DIFF_PICKAXE_KINDS_MASK))
                die(_("-G, -S and --find-object are mutually exclusive"));

        /*
         * Most of the time we can say "there are changes"
         * only by checking if there are changed paths, but
         * --ignore-whitespace* options force us to look
         * inside contents.
         */

        if ((options->xdl_opts & XDF_WHITESPACE_FLAGS))
                options->flags.diff_from_contents = 1;
        else
                options->flags.diff_from_contents = 0;

        if (options->flags.find_copies_harder)
                options->detect_rename = DIFF_DETECT_COPY;

        if (!options->flags.relative_name)
                options->prefix = NULL;
        if (options->prefix)
                options->prefix_length = strlen(options->prefix);
        else
                options->prefix_length = 0;

        if (options->output_format & (DIFF_FORMAT_NAME |
                                      DIFF_FORMAT_NAME_STATUS |
                                      DIFF_FORMAT_CHECKDIFF |
                                      DIFF_FORMAT_NO_OUTPUT))
                options->output_format &= ~(DIFF_FORMAT_RAW |
                                            DIFF_FORMAT_NUMSTAT |
                                            DIFF_FORMAT_DIFFSTAT |
                                            DIFF_FORMAT_SHORTSTAT |
                                            DIFF_FORMAT_DIRSTAT |
                                            DIFF_FORMAT_SUMMARY |
                                            DIFF_FORMAT_PATCH);

        /*
         * These cases always need recursive; we do not drop caller-supplied
         * recursive bits for other formats here.
         */
        if (options->output_format & (DIFF_FORMAT_PATCH |
                                      DIFF_FORMAT_NUMSTAT |
                                      DIFF_FORMAT_DIFFSTAT |
                                      DIFF_FORMAT_SHORTSTAT |
                                      DIFF_FORMAT_DIRSTAT |
                                      DIFF_FORMAT_SUMMARY |
                                      DIFF_FORMAT_CHECKDIFF))
                options->flags.recursive = 1;
        /*
         * Also pickaxe would not work very well if you do not say recursive
         */
        if (options->pickaxe_opts & DIFF_PICKAXE_KINDS_MASK)
                options->flags.recursive = 1;
        /*
         * When patches are generated, submodules diffed against the work tree
         * must be checked for dirtiness too so it can be shown in the output
         */
        if (options->output_format & DIFF_FORMAT_PATCH)
                options->flags.dirty_submodules = 1;

        if (options->detect_rename && options->rename_limit < 0)
                options->rename_limit = diff_rename_limit_default;
        if (hexsz < options->abbrev)
                options->abbrev = hexsz; /* full */

        /*
         * It does not make sense to show the first hit we happened
         * to have found.  It does not make sense not to return with
         * exit code in such a case either.
         */
        if (options->flags.quick) {
                options->output_format = DIFF_FORMAT_NO_OUTPUT;
                options->flags.exit_with_status = 1;
        }

        options->diff_path_counter = 0;

        if (options->flags.follow_renames && options->pathspec.nr != 1)
                die(_("--follow requires exactly one pathspec"));

        if (!options->use_color || external_diff())
                options->color_moved = 0;

        FREE_AND_NULL(options->parseopts);
}

int parse_long_opt(const char *opt, const char **argv,
                   const char **optarg)
{
        const char *arg = argv[0];
        if (!skip_prefix(arg, "--", &arg))
                return 0;
        if (!skip_prefix(arg, opt, &arg))
                return 0;
        if (*arg == '=') { /* stuck form: --option=value */
                *optarg = arg + 1;
                return 1;
        }
        if (*arg != '\0')
                return 0;
        /* separate form: --option value */
        if (!argv[1])
                die("Option '--%s' requires a value", opt);
        *optarg = argv[1];
        return 2;
}

static int diff_opt_stat(const struct option *opt, const char *value, int unset)
{
        struct diff_options *options = opt->value;
        int width = options->stat_width;
        int name_width = options->stat_name_width;
        int graph_width = options->stat_graph_width;
        int count = options->stat_count;
        char *end;

        BUG_ON_OPT_NEG(unset);

        if (!strcmp(opt->long_name, "stat")) {
                if (value) {
                        width = strtoul(value, &end, 10);
                        if (*end == ',')
                                name_width = strtoul(end+1, &end, 10);
                        if (*end == ',')
                                count = strtoul(end+1, &end, 10);
                        if (*end)
                                return error(_("invalid --stat value: %s"), value);
                }
        } else if (!strcmp(opt->long_name, "stat-width")) {
                width = strtoul(value, &end, 10);
                if (*end)
                        return error(_("%s expects a numerical value"),
                                     opt->long_name);
        } else if (!strcmp(opt->long_name, "stat-name-width")) {
                name_width = strtoul(value, &end, 10);
                if (*end)
                        return error(_("%s expects a numerical value"),
                                     opt->long_name);
        } else if (!strcmp(opt->long_name, "stat-graph-width")) {
                graph_width = strtoul(value, &end, 10);
                if (*end)
                        return error(_("%s expects a numerical value"),
                                     opt->long_name);
        } else if (!strcmp(opt->long_name, "stat-count")) {
                count = strtoul(value, &end, 10);
                if (*end)
                        return error(_("%s expects a numerical value"),
                                     opt->long_name);
        } else
                BUG("%s should not get here", opt->long_name);

        options->output_format |= DIFF_FORMAT_DIFFSTAT;
        options->stat_name_width = name_width;
        options->stat_graph_width = graph_width;
        options->stat_width = width;
        options->stat_count = count;
        return 0;
}

static int parse_dirstat_opt(struct diff_options *options, const char *params)
{
        struct strbuf errmsg = STRBUF_INIT;
        if (parse_dirstat_params(options, params, &errmsg))
                die(_("Failed to parse --dirstat/-X option parameter:\n%s"),
                    errmsg.buf);
        strbuf_release(&errmsg);
        /*
         * The caller knows a dirstat-related option is given from the command
         * line; allow it to say "return this_function();"
         */
        options->output_format |= DIFF_FORMAT_DIRSTAT;
        return 1;
}

static const char diff_status_letters[] = {
        DIFF_STATUS_ADDED,
        DIFF_STATUS_COPIED,
        DIFF_STATUS_DELETED,
        DIFF_STATUS_MODIFIED,
        DIFF_STATUS_RENAMED,
        DIFF_STATUS_TYPE_CHANGED,
        DIFF_STATUS_UNKNOWN,
        DIFF_STATUS_UNMERGED,
        DIFF_STATUS_FILTER_AON,
        DIFF_STATUS_FILTER_BROKEN,
        '\0',
};

static unsigned int filter_bit['Z' + 1];

static void prepare_filter_bits(void)
{
        int i;

        if (!filter_bit[DIFF_STATUS_ADDED]) {
                for (i = 0; diff_status_letters[i]; i++)
                        filter_bit[(int) diff_status_letters[i]] = (1 << i);
        }
}

static unsigned filter_bit_tst(char status, const struct diff_options *opt)
{
        return opt->filter & filter_bit[(int) status];
}

unsigned diff_filter_bit(char status)
{
        prepare_filter_bits();
        return filter_bit[(int) status];
}

static int diff_opt_diff_filter(const struct option *option,
                                const char *optarg, int unset)
{
        struct diff_options *opt = option->value;
        int i, optch;

        BUG_ON_OPT_NEG(unset);
        prepare_filter_bits();

        /*
         * If there is a negation e.g. 'd' in the input, and we haven't
         * initialized the filter field with another --diff-filter, start
         * from full set of bits, except for AON.
         */
        if (!opt->filter) {
                for (i = 0; (optch = optarg[i]) != '\0'; i++) {
                        if (optch < 'a' || 'z' < optch)
                                continue;
                        opt->filter = (1 << (ARRAY_SIZE(diff_status_letters) - 1)) - 1;
                        opt->filter &= ~filter_bit[DIFF_STATUS_FILTER_AON];
                        break;
                }
        }

        for (i = 0; (optch = optarg[i]) != '\0'; i++) {
                unsigned int bit;
                int negate;

                if ('a' <= optch && optch <= 'z') {
                        negate = 1;
                        optch = toupper(optch);
                } else {
                        negate = 0;
                }

                bit = (0 <= optch && optch <= 'Z') ? filter_bit[optch] : 0;
                if (!bit)
                        return error(_("unknown change class '%c' in --diff-filter=%s"),
                                     optarg[i], optarg);
                if (negate)
                        opt->filter &= ~bit;
                else
                        opt->filter |= bit;
        }
        return 0;
}

static void enable_patch_output(int *fmt)
{
        *fmt &= ~DIFF_FORMAT_NO_OUTPUT;
        *fmt |= DIFF_FORMAT_PATCH;
}

static int diff_opt_ws_error_highlight(const struct option *option,
                                       const char *arg, int unset)
{
        struct diff_options *opt = option->value;
        int val = parse_ws_error_highlight(arg);

        BUG_ON_OPT_NEG(unset);
        if (val < 0)
                return error(_("unknown value after ws-error-highlight=%.*s"),
                             -1 - val, arg);
        opt->ws_error_highlight = val;
        return 0;
}

static int diff_opt_find_object(const struct option *option,
                                const char *arg, int unset)
{
        struct diff_options *opt = option->value;
        struct object_id oid;

        BUG_ON_OPT_NEG(unset);
        if (get_oid(arg, &oid))
                return error(_("unable to resolve '%s'"), arg);

        if (!opt->objfind)
                opt->objfind = xcalloc(1, sizeof(*opt->objfind));

        opt->pickaxe_opts |= DIFF_PICKAXE_KIND_OBJFIND;
        opt->flags.recursive = 1;
        opt->flags.tree_in_recursive = 1;
        oidset_insert(opt->objfind, &oid);
        return 0;
}

static int diff_opt_anchored(const struct option *opt,
                             const char *arg, int unset)
{
        struct diff_options *options = opt->value;

        BUG_ON_OPT_NEG(unset);
        options->xdl_opts = DIFF_WITH_ALG(options, PATIENCE_DIFF);
        ALLOC_GROW(options->anchors, options->anchors_nr + 1,
                   options->anchors_alloc);
        options->anchors[options->anchors_nr++] = xstrdup(arg);
        return 0;
}

static int diff_opt_binary(const struct option *opt,
                           const char *arg, int unset)
{
        struct diff_options *options = opt->value;

        BUG_ON_OPT_NEG(unset);
        BUG_ON_OPT_ARG(arg);
        enable_patch_output(&options->output_format);
        options->flags.binary = 1;
        return 0;
}

static int diff_opt_break_rewrites(const struct option *opt,
                                   const char *arg, int unset)
{
        int *break_opt = opt->value;
        int opt1, opt2;

        BUG_ON_OPT_NEG(unset);
        if (!arg)
                arg = "";
        opt1 = parse_rename_score(&arg);
        if (*arg == 0)
                opt2 = 0;
        else if (*arg != '/')
                return error(_("%s expects <n>/<m> form"), opt->long_name);
        else {
                arg++;
                opt2 = parse_rename_score(&arg);
        }
        if (*arg != 0)
                return error(_("%s expects <n>/<m> form"), opt->long_name);
        *break_opt = opt1 | (opt2 << 16);
        return 0;
}

static int diff_opt_char(const struct option *opt,
                         const char *arg, int unset)
{
        char *value = opt->value;

        BUG_ON_OPT_NEG(unset);
        if (arg[1])
                return error(_("%s expects a character, got '%s'"),
                             opt->long_name, arg);
        *value = arg[0];
        return 0;
}

static int diff_opt_color_moved(const struct option *opt,
                                const char *arg, int unset)
{
        struct diff_options *options = opt->value;

        if (unset) {
                options->color_moved = COLOR_MOVED_NO;
        } else if (!arg) {
                if (diff_color_moved_default)
                        options->color_moved = diff_color_moved_default;
                if (options->color_moved == COLOR_MOVED_NO)
                        options->color_moved = COLOR_MOVED_DEFAULT;
        } else {
                int cm = parse_color_moved(arg);
                if (cm < 0)
                        return error(_("bad --color-moved argument: %s"), arg);
                options->color_moved = cm;
        }
        return 0;
}

static int diff_opt_color_moved_ws(const struct option *opt,
                                   const char *arg, int unset)
{
        struct diff_options *options = opt->value;
        unsigned cm;

        if (unset) {
                options->color_moved_ws_handling = 0;
                return 0;
        }

        cm = parse_color_moved_ws(arg);
        if (cm & COLOR_MOVED_WS_ERROR)
                return error(_("invalid mode '%s' in --color-moved-ws"), arg);
        options->color_moved_ws_handling = cm;
        return 0;
}

static int diff_opt_color_words(const struct option *opt,
                                const char *arg, int unset)
{
        struct diff_options *options = opt->value;

        BUG_ON_OPT_NEG(unset);
        options->use_color = 1;
        options->word_diff = DIFF_WORDS_COLOR;
        options->word_regex = arg;
        return 0;
}

static int diff_opt_compact_summary(const struct option *opt,
                                    const char *arg, int unset)
{
        struct diff_options *options = opt->value;

        BUG_ON_OPT_ARG(arg);
        if (unset) {
                options->flags.stat_with_summary = 0;
        } else {
                options->flags.stat_with_summary = 1;
                options->output_format |= DIFF_FORMAT_DIFFSTAT;
        }
        return 0;
}

static int diff_opt_diff_algorithm(const struct option *opt,
                                   const char *arg, int unset)
{
        struct diff_options *options = opt->value;
        long value = parse_algorithm_value(arg);

        BUG_ON_OPT_NEG(unset);
        if (value < 0)
                return error(_("option diff-algorithm accepts \"myers\", "
                               "\"minimal\", \"patience\" and \"histogram\""));

        /* clear out previous settings */
        DIFF_XDL_CLR(options, NEED_MINIMAL);
        options->xdl_opts &= ~XDF_DIFF_ALGORITHM_MASK;
        options->xdl_opts |= value;
        return 0;
}

static int diff_opt_dirstat(const struct option *opt,
                            const char *arg, int unset)
{
        struct diff_options *options = opt->value;

        BUG_ON_OPT_NEG(unset);
        if (!strcmp(opt->long_name, "cumulative")) {
                if (arg)
                        BUG("how come --cumulative take a value?");
                arg = "cumulative";
        } else if (!strcmp(opt->long_name, "dirstat-by-file"))
                parse_dirstat_opt(options, "files");
        parse_dirstat_opt(options, arg ? arg : "");
        return 0;
}

static int diff_opt_find_copies(const struct option *opt,
                                const char *arg, int unset)
{
        struct diff_options *options = opt->value;

        BUG_ON_OPT_NEG(unset);
        if (!arg)
                arg = "";
        options->rename_score = parse_rename_score(&arg);
        if (*arg != 0)
                return error(_("invalid argument to %s"), opt->long_name);

        if (options->detect_rename == DIFF_DETECT_COPY)
                options->flags.find_copies_harder = 1;
        else
                options->detect_rename = DIFF_DETECT_COPY;

        return 0;
}

static int diff_opt_find_renames(const struct option *opt,
                                 const char *arg, int unset)
{
        struct diff_options *options = opt->value;

        BUG_ON_OPT_NEG(unset);
        if (!arg)
                arg = "";
        options->rename_score = parse_rename_score(&arg);
        if (*arg != 0)
                return error(_("invalid argument to %s"), opt->long_name);

        options->detect_rename = DIFF_DETECT_RENAME;
        return 0;
}

static int diff_opt_follow(const struct option *opt,
                           const char *arg, int unset)
{
        struct diff_options *options = opt->value;

        BUG_ON_OPT_ARG(arg);
        if (unset) {
                options->flags.follow_renames = 0;
                options->flags.default_follow_renames = 0;
        } else {
                options->flags.follow_renames = 1;
        }
        return 0;
}

static int diff_opt_ignore_submodules(const struct option *opt,
                                      const char *arg, int unset)
{
        struct diff_options *options = opt->value;

        BUG_ON_OPT_NEG(unset);
        if (!arg)
                arg = "all";
        options->flags.override_submodule_config = 1;
        handle_ignore_submodules_arg(options, arg);
        return 0;
}

static int diff_opt_line_prefix(const struct option *opt,
                                const char *optarg, int unset)
{
        struct diff_options *options = opt->value;

        BUG_ON_OPT_NEG(unset);
        options->line_prefix = optarg;
        options->line_prefix_length = strlen(options->line_prefix);
        graph_setup_line_prefix(options);
        return 0;
}

static int diff_opt_no_prefix(const struct option *opt,
                              const char *optarg, int unset)
{
        struct diff_options *options = opt->value;

        BUG_ON_OPT_NEG(unset);
        BUG_ON_OPT_ARG(optarg);
        options->a_prefix = "";
        options->b_prefix = "";
        return 0;
}

static enum parse_opt_result diff_opt_output(struct parse_opt_ctx_t *ctx,
                                             const struct option *opt,
                                             const char *arg, int unset)
{
        struct diff_options *options = opt->value;
        char *path;

        BUG_ON_OPT_NEG(unset);
        path = prefix_filename(ctx->prefix, arg);
        options->file = xfopen(path, "w");
        options->close_file = 1;
        if (options->use_color != GIT_COLOR_ALWAYS)
                options->use_color = GIT_COLOR_NEVER;
        free(path);
        return 0;
}

static int diff_opt_patience(const struct option *opt,
                             const char *arg, int unset)
{
        struct diff_options *options = opt->value;
        int i;

        BUG_ON_OPT_NEG(unset);
        BUG_ON_OPT_ARG(arg);
        options->xdl_opts = DIFF_WITH_ALG(options, PATIENCE_DIFF);
        /*
         * Both --patience and --anchored use PATIENCE_DIFF
         * internally, so remove any anchors previously
         * specified.
         */
        for (i = 0; i < options->anchors_nr; i++)
                free(options->anchors[i]);
        options->anchors_nr = 0;
        return 0;
}

static int diff_opt_pickaxe_regex(const struct option *opt,
                                  const char *arg, int unset)
{
        struct diff_options *options = opt->value;

        BUG_ON_OPT_NEG(unset);
        options->pickaxe = arg;
        options->pickaxe_opts |= DIFF_PICKAXE_KIND_G;
        return 0;
}

static int diff_opt_pickaxe_string(const struct option *opt,
                                   const char *arg, int unset)
{
        struct diff_options *options = opt->value;

        BUG_ON_OPT_NEG(unset);
        options->pickaxe = arg;
        options->pickaxe_opts |= DIFF_PICKAXE_KIND_S;
        return 0;
}

static int diff_opt_relative(const struct option *opt,
                             const char *arg, int unset)
{
        struct diff_options *options = opt->value;

        BUG_ON_OPT_NEG(unset);
        options->flags.relative_name = 1;
        if (arg)
                options->prefix = arg;
        return 0;
}

static int diff_opt_submodule(const struct option *opt,
                              const char *arg, int unset)
{
        struct diff_options *options = opt->value;

        BUG_ON_OPT_NEG(unset);
        if (!arg)
                arg = "log";
        if (parse_submodule_params(options, arg))
                return error(_("failed to parse --submodule option parameter: '%s'"),
                             arg);
        return 0;
}

static int diff_opt_textconv(const struct option *opt,
                             const char *arg, int unset)
{
        struct diff_options *options = opt->value;

        BUG_ON_OPT_ARG(arg);
        if (unset) {
                options->flags.allow_textconv = 0;
        } else {
                options->flags.allow_textconv = 1;
                options->flags.textconv_set_via_cmdline = 1;
        }
        return 0;
}

static int diff_opt_unified(const struct option *opt,
                            const char *arg, int unset)
{
        struct diff_options *options = opt->value;
        char *s;

        BUG_ON_OPT_NEG(unset);

        if (arg) {
                options->context = strtol(arg, &s, 10);
                if (*s)
                        return error(_("%s expects a numerical value"), "--unified");
        }
        enable_patch_output(&options->output_format);

        return 0;
}

static int diff_opt_word_diff(const struct option *opt,
                              const char *arg, int unset)
{
        struct diff_options *options = opt->value;

        BUG_ON_OPT_NEG(unset);
        if (arg) {
                if (!strcmp(arg, "plain"))
                        options->word_diff = DIFF_WORDS_PLAIN;
                else if (!strcmp(arg, "color")) {
                        options->use_color = 1;
                        options->word_diff = DIFF_WORDS_COLOR;
                }
                else if (!strcmp(arg, "porcelain"))
                        options->word_diff = DIFF_WORDS_PORCELAIN;
                else if (!strcmp(arg, "none"))
                        options->word_diff = DIFF_WORDS_NONE;
                else
                        return error(_("bad --word-diff argument: %s"), arg);
        } else {
                if (options->word_diff == DIFF_WORDS_NONE)
                        options->word_diff = DIFF_WORDS_PLAIN;
        }
        return 0;
}

static int diff_opt_word_diff_regex(const struct option *opt,
                                    const char *arg, int unset)
{
        struct diff_options *options = opt->value;

        BUG_ON_OPT_NEG(unset);
        if (options->word_diff == DIFF_WORDS_NONE)
                options->word_diff = DIFF_WORDS_PLAIN;
        options->word_regex = arg;
        return 0;
}

static void prep_parse_options(struct diff_options *options)
{
        struct option parseopts[] = {
                OPT_GROUP(N_("Diff output format options")),
                OPT_BITOP('p', "patch", &options->output_format,
                          N_("generate patch"),
                          DIFF_FORMAT_PATCH, DIFF_FORMAT_NO_OUTPUT),
                OPT_BIT_F('s', "no-patch", &options->output_format,
                          N_("suppress diff output"),
                          DIFF_FORMAT_NO_OUTPUT, PARSE_OPT_NONEG),
                OPT_BITOP('u', NULL, &options->output_format,
                          N_("generate patch"),
                          DIFF_FORMAT_PATCH, DIFF_FORMAT_NO_OUTPUT),
                OPT_CALLBACK_F('U', "unified", options, N_("<n>"),
                               N_("generate diffs with <n> lines context"),
                               PARSE_OPT_NONEG | PARSE_OPT_OPTARG, diff_opt_unified),
                OPT_BOOL('W', "function-context", &options->flags.funccontext,
                         N_("generate diffs with <n> lines context")),
                OPT_BIT_F(0, "raw", &options->output_format,
                          N_("generate the diff in raw format"),
                          DIFF_FORMAT_RAW, PARSE_OPT_NONEG),
                OPT_BITOP(0, "patch-with-raw", &options->output_format,
                          N_("synonym for '-p --raw'"),
                          DIFF_FORMAT_PATCH | DIFF_FORMAT_RAW,
                          DIFF_FORMAT_NO_OUTPUT),
                OPT_BITOP(0, "patch-with-stat", &options->output_format,
                          N_("synonym for '-p --stat'"),
                          DIFF_FORMAT_PATCH | DIFF_FORMAT_DIFFSTAT,
                          DIFF_FORMAT_NO_OUTPUT),
                OPT_BIT_F(0, "numstat", &options->output_format,
                          N_("machine friendly --stat"),
                          DIFF_FORMAT_NUMSTAT, PARSE_OPT_NONEG),
                OPT_BIT_F(0, "shortstat", &options->output_format,
                          N_("output only the last line of --stat"),
                          DIFF_FORMAT_SHORTSTAT, PARSE_OPT_NONEG),
                OPT_CALLBACK_F('X', "dirstat", options, N_("<param1,param2>..."),
                               N_("output the distribution of relative amount of changes for each sub-directory"),
                               PARSE_OPT_NONEG | PARSE_OPT_OPTARG,
                               diff_opt_dirstat),
                OPT_CALLBACK_F(0, "cumulative", options, NULL,
                               N_("synonym for --dirstat=cumulative"),
                               PARSE_OPT_NONEG | PARSE_OPT_NOARG,
                               diff_opt_dirstat),
                OPT_CALLBACK_F(0, "dirstat-by-file", options, N_("<param1,param2>..."),
                               N_("synonym for --dirstat=files,param1,param2..."),
                               PARSE_OPT_NONEG | PARSE_OPT_OPTARG,
                               diff_opt_dirstat),
                OPT_BIT_F(0, "check", &options->output_format,
                          N_("warn if changes introduce conflict markers or whitespace errors"),
                          DIFF_FORMAT_CHECKDIFF, PARSE_OPT_NONEG),
                OPT_BIT_F(0, "summary", &options->output_format,
                          N_("condensed summary such as creations, renames and mode changes"),
                          DIFF_FORMAT_SUMMARY, PARSE_OPT_NONEG),
                OPT_BIT_F(0, "name-only", &options->output_format,
                          N_("show only names of changed files"),
                          DIFF_FORMAT_NAME, PARSE_OPT_NONEG),
                OPT_BIT_F(0, "name-status", &options->output_format,
                          N_("show only names and status of changed files"),
                          DIFF_FORMAT_NAME_STATUS, PARSE_OPT_NONEG),
                OPT_CALLBACK_F(0, "stat", options, N_("<width>[,<name-width>[,<count>]]"),
                               N_("generate diffstat"),
                               PARSE_OPT_NONEG | PARSE_OPT_OPTARG, diff_opt_stat),
                OPT_CALLBACK_F(0, "stat-width", options, N_("<width>"),
                               N_("generate diffstat with a given width"),
                               PARSE_OPT_NONEG, diff_opt_stat),
                OPT_CALLBACK_F(0, "stat-name-width", options, N_("<width>"),
                               N_("generate diffstat with a given name width"),
                               PARSE_OPT_NONEG, diff_opt_stat),
                OPT_CALLBACK_F(0, "stat-graph-width", options, N_("<width>"),
                               N_("generate diffstat with a given graph width"),
                               PARSE_OPT_NONEG, diff_opt_stat),
                OPT_CALLBACK_F(0, "stat-count", options, N_("<count>"),
                               N_("generate diffstat with limited lines"),
                               PARSE_OPT_NONEG, diff_opt_stat),
                OPT_CALLBACK_F(0, "compact-summary", options, NULL,
                               N_("generate compact summary in diffstat"),
                               PARSE_OPT_NOARG, diff_opt_compact_summary),
                OPT_CALLBACK_F(0, "binary", options, NULL,
                               N_("output a binary diff that can be applied"),
                               PARSE_OPT_NONEG | PARSE_OPT_NOARG, diff_opt_binary),
                OPT_BOOL(0, "full-index", &options->flags.full_index,
                         N_("show full pre- and post-image object names on the \"index\" lines")),
                OPT_COLOR_FLAG(0, "color", &options->use_color,
                               N_("show colored diff")),
                OPT_CALLBACK_F(0, "ws-error-highlight", options, N_("<kind>"),
                               N_("highlight whitespace errors in the 'context', 'old' or 'new' lines in the diff"),
                               PARSE_OPT_NONEG, diff_opt_ws_error_highlight),
                OPT_SET_INT('z', NULL, &options->line_termination,
                            N_("do not munge pathnames and use NULs as output field terminators in --raw or --numstat"),
                            0),
                OPT__ABBREV(&options->abbrev),
                OPT_STRING_F(0, "src-prefix", &options->a_prefix, N_("<prefix>"),
                             N_("show the given source prefix instead of \"a/\""),
                             PARSE_OPT_NONEG),
                OPT_STRING_F(0, "dst-prefix", &options->b_prefix, N_("<prefix>"),
                             N_("show the given destination prefix instead of \"b/\""),
                             PARSE_OPT_NONEG),
                OPT_CALLBACK_F(0, "line-prefix", options, N_("<prefix>"),
                               N_("prepend an additional prefix to every line of output"),
                               PARSE_OPT_NONEG, diff_opt_line_prefix),
                OPT_CALLBACK_F(0, "no-prefix", options, NULL,
                               N_("do not show any source or destination prefix"),
                               PARSE_OPT_NONEG | PARSE_OPT_NOARG, diff_opt_no_prefix),
                OPT_INTEGER_F(0, "inter-hunk-context", &options->interhunkcontext,
                              N_("show context between diff hunks up to the specified number of lines"),
                              PARSE_OPT_NONEG),
                OPT_CALLBACK_F(0, "output-indicator-new",
                               &options->output_indicators[OUTPUT_INDICATOR_NEW],
                               N_("<char>"),
                               N_("specify the character to indicate a new line instead of '+'"),
                               PARSE_OPT_NONEG, diff_opt_char),
                OPT_CALLBACK_F(0, "output-indicator-old",
                               &options->output_indicators[OUTPUT_INDICATOR_OLD],
                               N_("<char>"),
                               N_("specify the character to indicate an old line instead of '-'"),
                               PARSE_OPT_NONEG, diff_opt_char),
                OPT_CALLBACK_F(0, "output-indicator-context",
                               &options->output_indicators[OUTPUT_INDICATOR_CONTEXT],
                               N_("<char>"),
                               N_("specify the character to indicate a context instead of ' '"),
                               PARSE_OPT_NONEG, diff_opt_char),

                OPT_GROUP(N_("Diff rename options")),
                OPT_CALLBACK_F('B', "break-rewrites", &options->break_opt, N_("<n>[/<m>]"),
                               N_("break complete rewrite changes into pairs of delete and create"),
                               PARSE_OPT_NONEG | PARSE_OPT_OPTARG,
                               diff_opt_break_rewrites),
                OPT_CALLBACK_F('M', "find-renames", options, N_("<n>"),
                               N_("detect renames"),
                               PARSE_OPT_NONEG | PARSE_OPT_OPTARG,
                               diff_opt_find_renames),
                OPT_SET_INT_F('D', "irreversible-delete", &options->irreversible_delete,
                              N_("omit the preimage for deletes"),
                              1, PARSE_OPT_NONEG),
                OPT_CALLBACK_F('C', "find-copies", options, N_("<n>"),
                               N_("detect copies"),
                               PARSE_OPT_NONEG | PARSE_OPT_OPTARG,
                               diff_opt_find_copies),
                OPT_BOOL(0, "find-copies-harder", &options->flags.find_copies_harder,
                         N_("use unmodified files as source to find copies")),
                OPT_SET_INT_F(0, "no-renames", &options->detect_rename,
                              N_("disable rename detection"),
                              0, PARSE_OPT_NONEG),
                OPT_BOOL(0, "rename-empty", &options->flags.rename_empty,
                         N_("use empty blobs as rename source")),
                OPT_CALLBACK_F(0, "follow", options, NULL,
                               N_("continue listing the history of a file beyond renames"),
                               PARSE_OPT_NOARG, diff_opt_follow),
                OPT_INTEGER('l', NULL, &options->rename_limit,
                            N_("prevent rename/copy detection if the number of rename/copy targets exceeds given limit")),

                OPT_GROUP(N_("Diff algorithm options")),
                OPT_BIT(0, "minimal", &options->xdl_opts,
                        N_("produce the smallest possible diff"),
                        XDF_NEED_MINIMAL),
                OPT_BIT_F('w', "ignore-all-space", &options->xdl_opts,
                          N_("ignore whitespace when comparing lines"),
                          XDF_IGNORE_WHITESPACE, PARSE_OPT_NONEG),
                OPT_BIT_F('b', "ignore-space-change", &options->xdl_opts,
                          N_("ignore changes in amount of whitespace"),
                          XDF_IGNORE_WHITESPACE_CHANGE, PARSE_OPT_NONEG),
                OPT_BIT_F(0, "ignore-space-at-eol", &options->xdl_opts,
                          N_("ignore changes in whitespace at EOL"),
                          XDF_IGNORE_WHITESPACE_AT_EOL, PARSE_OPT_NONEG),
                OPT_BIT_F(0, "ignore-cr-at-eol", &options->xdl_opts,
                          N_("ignore carrier-return at the end of line"),
                          XDF_IGNORE_CR_AT_EOL, PARSE_OPT_NONEG),
                OPT_BIT_F(0, "ignore-blank-lines", &options->xdl_opts,
                          N_("ignore changes whose lines are all blank"),
                          XDF_IGNORE_BLANK_LINES, PARSE_OPT_NONEG),
                OPT_BIT(0, "indent-heuristic", &options->xdl_opts,
                        N_("heuristic to shift diff hunk boundaries for easy reading"),
                        XDF_INDENT_HEURISTIC),
                OPT_CALLBACK_F(0, "patience", options, NULL,
                               N_("generate diff using the \"patience diff\" algorithm"),
                               PARSE_OPT_NONEG | PARSE_OPT_NOARG,
                               diff_opt_patience),
                OPT_BITOP(0, "histogram", &options->xdl_opts,
                          N_("generate diff using the \"histogram diff\" algorithm"),
                          XDF_HISTOGRAM_DIFF, XDF_DIFF_ALGORITHM_MASK),
                OPT_CALLBACK_F(0, "diff-algorithm", options, N_("<algorithm>"),
                               N_("choose a diff algorithm"),
                               PARSE_OPT_NONEG, diff_opt_diff_algorithm),
                OPT_CALLBACK_F(0, "anchored", options, N_("<text>"),
                               N_("generate diff using the \"anchored diff\" algorithm"),
                               PARSE_OPT_NONEG, diff_opt_anchored),
                OPT_CALLBACK_F(0, "word-diff", options, N_("<mode>"),
                               N_("show word diff, using <mode> to delimit changed words"),
                               PARSE_OPT_NONEG | PARSE_OPT_OPTARG, diff_opt_word_diff),
                OPT_CALLBACK_F(0, "word-diff-regex", options, N_("<regex>"),
                               N_("use <regex> to decide what a word is"),
                               PARSE_OPT_NONEG, diff_opt_word_diff_regex),
                OPT_CALLBACK_F(0, "color-words", options, N_("<regex>"),
                               N_("equivalent to --word-diff=color --word-diff-regex=<regex>"),
                               PARSE_OPT_NONEG | PARSE_OPT_OPTARG, diff_opt_color_words),
                OPT_CALLBACK_F(0, "color-moved", options, N_("<mode>"),
                               N_("moved lines of code are colored differently"),
                               PARSE_OPT_OPTARG, diff_opt_color_moved),
                OPT_CALLBACK_F(0, "color-moved-ws", options, N_("<mode>"),
                               N_("how white spaces are ignored in --color-moved"),
                               0, diff_opt_color_moved_ws),

                OPT_GROUP(N_("Other diff options")),
                OPT_CALLBACK_F(0, "relative", options, N_("<prefix>"),
                               N_("when run from subdir, exclude changes outside and show relative paths"),
                               PARSE_OPT_NONEG | PARSE_OPT_OPTARG,
                               diff_opt_relative),
                OPT_BOOL('a', "text", &options->flags.text,
                         N_("treat all files as text")),
                OPT_BOOL('R', NULL, &options->flags.reverse_diff,
                         N_("swap two inputs, reverse the diff")),
                OPT_BOOL(0, "exit-code", &options->flags.exit_with_status,
                         N_("exit with 1 if there were differences, 0 otherwise")),
                OPT_BOOL(0, "quiet", &options->flags.quick,
                         N_("disable all output of the program")),
                OPT_BOOL(0, "ext-diff", &options->flags.allow_external,
                         N_("allow an external diff helper to be executed")),
                OPT_CALLBACK_F(0, "textconv", options, NULL,
                               N_("run external text conversion filters when comparing binary files"),
                               PARSE_OPT_NOARG, diff_opt_textconv),
                OPT_CALLBACK_F(0, "ignore-submodules", options, N_("<when>"),
                               N_("ignore changes to submodules in the diff generation"),
                               PARSE_OPT_NONEG | PARSE_OPT_OPTARG,
                               diff_opt_ignore_submodules),
                OPT_CALLBACK_F(0, "submodule", options, N_("<format>"),
                               N_("specify how differences in submodules are shown"),
                               PARSE_OPT_NONEG | PARSE_OPT_OPTARG,
                               diff_opt_submodule),
                OPT_SET_INT_F(0, "ita-invisible-in-index", &options->ita_invisible_in_index,
                              N_("hide 'git add -N' entries from the index"),
                              1, PARSE_OPT_NONEG),
                OPT_SET_INT_F(0, "ita-visible-in-index", &options->ita_invisible_in_index,
                              N_("treat 'git add -N' entries as real in the index"),
                              0, PARSE_OPT_NONEG),
                OPT_CALLBACK_F('S', NULL, options, N_("<string>"),
                               N_("look for differences that change the number of occurrences of the specified string"),
                               0, diff_opt_pickaxe_string),
                OPT_CALLBACK_F('G', NULL, options, N_("<regex>"),
                               N_("look for differences that change the number of occurrences of the specified regex"),
                               0, diff_opt_pickaxe_regex),
                OPT_BIT_F(0, "pickaxe-all", &options->pickaxe_opts,
                          N_("show all changes in the changeset with -S or -G"),
                          DIFF_PICKAXE_ALL, PARSE_OPT_NONEG),
                OPT_BIT_F(0, "pickaxe-regex", &options->pickaxe_opts,
                          N_("treat <string> in -S as extended POSIX regular expression"),
                          DIFF_PICKAXE_REGEX, PARSE_OPT_NONEG),
                OPT_FILENAME('O', NULL, &options->orderfile,
                             N_("control the order in which files appear in the output")),
                OPT_CALLBACK_F(0, "find-object", options, N_("<object-id>"),
                               N_("look for differences that change the number of occurrences of the specified object"),
                               PARSE_OPT_NONEG, diff_opt_find_object),
                OPT_CALLBACK_F(0, "diff-filter", options, N_("[(A|C|D|M|R|T|U|X|B)...[*]]"),
                               N_("select files by diff type"),
                               PARSE_OPT_NONEG, diff_opt_diff_filter),
                { OPTION_CALLBACK, 0, "output", options, N_("<file>"),
                  N_("Output to a specific file"),
                  PARSE_OPT_NONEG, NULL, 0, diff_opt_output },

                OPT_END()
        };

        ALLOC_ARRAY(options->parseopts, ARRAY_SIZE(parseopts));
        memcpy(options->parseopts, parseopts, sizeof(parseopts));
}

int diff_opt_parse(struct diff_options *options,
                   const char **av, int ac, const char *prefix)
{
        if (!prefix)
                prefix = "";

        ac = parse_options(ac, av, prefix, options->parseopts, NULL,
                           PARSE_OPT_KEEP_DASHDASH |
                           PARSE_OPT_KEEP_UNKNOWN |
                           PARSE_OPT_NO_INTERNAL_HELP |
                           PARSE_OPT_ONE_SHOT |
                           PARSE_OPT_STOP_AT_NON_OPTION);

        return ac;
}

int parse_rename_score(const char **cp_p)
{
        unsigned long num, scale;
        int ch, dot;
        const char *cp = *cp_p;

        num = 0;
        scale = 1;
        dot = 0;
        for (;;) {
                ch = *cp;
                if ( !dot && ch == '.' ) {
                        scale = 1;
                        dot = 1;
                } else if ( ch == '%' ) {
                        scale = dot ? scale*100 : 100;
                        cp++;   /* % is always at the end */
                        break;
                } else if ( ch >= '0' && ch <= '9' ) {
                        if ( scale < 100000 ) {
                                scale *= 10;
                                num = (num*10) + (ch-'0');
                        }
                } else {
                        break;
                }
                cp++;
        }
        *cp_p = cp;

        /* user says num divided by scale and we say internally that
         * is MAX_SCORE * num / scale.
         */
        return (int)((num >= scale) ? MAX_SCORE : (MAX_SCORE * num / scale));
}

struct diff_queue_struct diff_queued_diff;

void diff_q(struct diff_queue_struct *queue, struct diff_filepair *dp)
{
        ALLOC_GROW(queue->queue, queue->nr + 1, queue->alloc);
        queue->queue[queue->nr++] = dp;
}

struct diff_filepair *diff_queue(struct diff_queue_struct *queue,
                                 struct diff_filespec *one,
                                 struct diff_filespec *two)
{
        struct diff_filepair *dp = xcalloc(1, sizeof(*dp));
        dp->one = one;
        dp->two = two;
        if (queue)
                diff_q(queue, dp);
        return dp;
}

void diff_free_filepair(struct diff_filepair *p)
{
        free_filespec(p->one);
        free_filespec(p->two);
        free(p);
}

const char *diff_aligned_abbrev(const struct object_id *oid, int len)
{
        int abblen;
        const char *abbrev;

        /* Do we want all 40 hex characters? */
        if (len == the_hash_algo->hexsz)
                return oid_to_hex(oid);

        /* An abbreviated value is fine, possibly followed by an ellipsis. */
        abbrev = diff_abbrev_oid(oid, len);

        if (!print_sha1_ellipsis())
                return abbrev;

        abblen = strlen(abbrev);

        /*
         * In well-behaved cases, where the abbreviated result is the
         * same as the requested length, append three dots after the
         * abbreviation (hence the whole logic is limited to the case
         * where abblen < 37); when the actual abbreviated result is a
         * bit longer than the requested length, we reduce the number
         * of dots so that they match the well-behaved ones.  However,
         * if the actual abbreviation is longer than the requested
         * length by more than three, we give up on aligning, and add
         * three dots anyway, to indicate that the output is not the
         * full object name.  Yes, this may be suboptimal, but this
         * appears only in "diff --raw --abbrev" output and it is not
         * worth the effort to change it now.  Note that this would
         * likely to work fine when the automatic sizing of default
         * abbreviation length is used--we would be fed -1 in "len" in
         * that case, and will end up always appending three-dots, but
         * the automatic sizing is supposed to give abblen that ensures
         * uniqueness across all objects (statistically speaking).
         */
        if (abblen < the_hash_algo->hexsz - 3) {
                static char hex[GIT_MAX_HEXSZ + 1];
                if (len < abblen && abblen <= len + 2)
                        xsnprintf(hex, sizeof(hex), "%s%.*s", abbrev, len+3-abblen, "..");
                else
                        xsnprintf(hex, sizeof(hex), "%s...", abbrev);
                return hex;
        }

        return oid_to_hex(oid);
}

static void diff_flush_raw(struct diff_filepair *p, struct diff_options *opt)
{
        int line_termination = opt->line_termination;
        int inter_name_termination = line_termination ? '\t' : '\0';

        fprintf(opt->file, "%s", diff_line_prefix(opt));
        if (!(opt->output_format & DIFF_FORMAT_NAME_STATUS)) {
                fprintf(opt->file, ":%06o %06o %s ", p->one->mode, p->two->mode,
                        diff_aligned_abbrev(&p->one->oid, opt->abbrev));
                fprintf(opt->file, "%s ",
                        diff_aligned_abbrev(&p->two->oid, opt->abbrev));
        }
        if (p->score) {
                fprintf(opt->file, "%c%03d%c", p->status, similarity_index(p),
                        inter_name_termination);
        } else {
                fprintf(opt->file, "%c%c", p->status, inter_name_termination);
        }

        if (p->status == DIFF_STATUS_COPIED ||
            p->status == DIFF_STATUS_RENAMED) {
                const char *name_a, *name_b;
                name_a = p->one->path;
                name_b = p->two->path;
                strip_prefix(opt->prefix_length, &name_a, &name_b);
                write_name_quoted(name_a, opt->file, inter_name_termination);
                write_name_quoted(name_b, opt->file, line_termination);
        } else {
                const char *name_a, *name_b;
                name_a = p->one->mode ? p->one->path : p->two->path;
                name_b = NULL;
                strip_prefix(opt->prefix_length, &name_a, &name_b);
                write_name_quoted(name_a, opt->file, line_termination);
        }
}

int diff_unmodified_pair(struct diff_filepair *p)
{
        /* This function is written stricter than necessary to support
         * the currently implemented transformers, but the idea is to
         * let transformers to produce diff_filepairs any way they want,
         * and filter and clean them up here before producing the output.
         */
        struct diff_filespec *one = p->one, *two = p->two;

        if (DIFF_PAIR_UNMERGED(p))
                return 0; /* unmerged is interesting */

        /* deletion, addition, mode or type change
         * and rename are all interesting.
         */
        if (DIFF_FILE_VALID(one) != DIFF_FILE_VALID(two) ||
            DIFF_PAIR_MODE_CHANGED(p) ||
            strcmp(one->path, two->path))
                return 0;

        /* both are valid and point at the same path.  that is, we are
         * dealing with a change.
         */
        if (one->oid_valid && two->oid_valid &&
            oideq(&one->oid, &two->oid) &&
            !one->dirty_submodule && !two->dirty_submodule)
                return 1; /* no change */
        if (!one->oid_valid && !two->oid_valid)
                return 1; /* both look at the same file on the filesystem. */
        return 0;
}

static void diff_flush_patch(struct diff_filepair *p, struct diff_options *o)
{
        if (diff_unmodified_pair(p))
                return;

        if ((DIFF_FILE_VALID(p->one) && S_ISDIR(p->one->mode)) ||
            (DIFF_FILE_VALID(p->two) && S_ISDIR(p->two->mode)))
                return; /* no tree diffs in patch format */

        run_diff(p, o);
}

static void diff_flush_stat(struct diff_filepair *p, struct diff_options *o,
                            struct diffstat_t *diffstat)
{
        if (diff_unmodified_pair(p))
                return;

        if ((DIFF_FILE_VALID(p->one) && S_ISDIR(p->one->mode)) ||
            (DIFF_FILE_VALID(p->two) && S_ISDIR(p->two->mode)))
                return; /* no useful stat for tree diffs */

        run_diffstat(p, o, diffstat);
}

static void diff_flush_checkdiff(struct diff_filepair *p,
                struct diff_options *o)
{
        if (diff_unmodified_pair(p))
                return;

        if ((DIFF_FILE_VALID(p->one) && S_ISDIR(p->one->mode)) ||
            (DIFF_FILE_VALID(p->two) && S_ISDIR(p->two->mode)))
                return; /* nothing to check in tree diffs */

        run_checkdiff(p, o);
}

int diff_queue_is_empty(void)
{
        struct diff_queue_struct *q = &diff_queued_diff;
        int i;
        for (i = 0; i < q->nr; i++)
                if (!diff_unmodified_pair(q->queue[i]))
                        return 0;
        return 1;
}

#if DIFF_DEBUG
void diff_debug_filespec(struct diff_filespec *s, int x, const char *one)
{
        fprintf(stderr, "queue[%d] %s (%s) %s %06o %s\n",
                x, one ? one : "",
                s->path,
                DIFF_FILE_VALID(s) ? "valid" : "invalid",
                s->mode,
                s->oid_valid ? oid_to_hex(&s->oid) : "");
        fprintf(stderr, "queue[%d] %s size %lu\n",
                x, one ? one : "",
                s->size);
}

void diff_debug_filepair(const struct diff_filepair *p, int i)
{
        diff_debug_filespec(p->one, i, "one");
        diff_debug_filespec(p->two, i, "two");
        fprintf(stderr, "score %d, status %c rename_used %d broken %d\n",
                p->score, p->status ? p->status : '?',
                p->one->rename_used, p->broken_pair);
}

void diff_debug_queue(const char *msg, struct diff_queue_struct *q)
{
        int i;
        if (msg)
                fprintf(stderr, "%s\n", msg);
        fprintf(stderr, "q->nr = %d\n", q->nr);
        for (i = 0; i < q->nr; i++) {
                struct diff_filepair *p = q->queue[i];
                diff_debug_filepair(p, i);
        }
}
#endif

static void diff_resolve_rename_copy(void)
{
        int i;
        struct diff_filepair *p;
        struct diff_queue_struct *q = &diff_queued_diff;

        diff_debug_queue("resolve-rename-copy", q);

        for (i = 0; i < q->nr; i++) {
                p = q->queue[i];
                p->status = 0; /* undecided */
                if (DIFF_PAIR_UNMERGED(p))
                        p->status = DIFF_STATUS_UNMERGED;
                else if (!DIFF_FILE_VALID(p->one))
                        p->status = DIFF_STATUS_ADDED;
                else if (!DIFF_FILE_VALID(p->two))
                        p->status = DIFF_STATUS_DELETED;
                else if (DIFF_PAIR_TYPE_CHANGED(p))
                        p->status = DIFF_STATUS_TYPE_CHANGED;

                /* from this point on, we are dealing with a pair
                 * whose both sides are valid and of the same type, i.e.
                 * either in-place edit or rename/copy edit.
                 */
                else if (DIFF_PAIR_RENAME(p)) {
                        /*
                         * A rename might have re-connected a broken
                         * pair up, causing the pathnames to be the
                         * same again. If so, that's not a rename at
                         * all, just a modification..
                         *
                         * Otherwise, see if this source was used for
                         * multiple renames, in which case we decrement
                         * the count, and call it a copy.
                         */
                        if (!strcmp(p->one->path, p->two->path))
                                p->status = DIFF_STATUS_MODIFIED;
                        else if (--p->one->rename_used > 0)
                                p->status = DIFF_STATUS_COPIED;
                        else
                                p->status = DIFF_STATUS_RENAMED;
                }
                else if (!oideq(&p->one->oid, &p->two->oid) ||
                         p->one->mode != p->two->mode ||
                         p->one->dirty_submodule ||
                         p->two->dirty_submodule ||
                         is_null_oid(&p->one->oid))
                        p->status = DIFF_STATUS_MODIFIED;
                else {
                        /* This is a "no-change" entry and should not
                         * happen anymore, but prepare for broken callers.
                         */
                        error("feeding unmodified %s to diffcore",
                              p->one->path);
                        p->status = DIFF_STATUS_UNKNOWN;
                }
        }
        diff_debug_queue("resolve-rename-copy done", q);
}

static int check_pair_status(struct diff_filepair *p)
{
        switch (p->status) {
        case DIFF_STATUS_UNKNOWN:
                return 0;
        case 0:
                die("internal error in diff-resolve-rename-copy");
        default:
                return 1;
        }
}

static void flush_one_pair(struct diff_filepair *p, struct diff_options *opt)
{
        int fmt = opt->output_format;

        if (fmt & DIFF_FORMAT_CHECKDIFF)
                diff_flush_checkdiff(p, opt);
        else if (fmt & (DIFF_FORMAT_RAW | DIFF_FORMAT_NAME_STATUS))
                diff_flush_raw(p, opt);
        else if (fmt & DIFF_FORMAT_NAME) {
                const char *name_a, *name_b;
                name_a = p->two->path;
                name_b = NULL;
                strip_prefix(opt->prefix_length, &name_a, &name_b);
                fprintf(opt->file, "%s", diff_line_prefix(opt));
                write_name_quoted(name_a, opt->file, opt->line_termination);
        }
}

static void show_file_mode_name(struct diff_options *opt, const char *newdelete, struct diff_filespec *fs)
{
        struct strbuf sb = STRBUF_INIT;
        if (fs->mode)
                strbuf_addf(&sb, " %s mode %06o ", newdelete, fs->mode);
        else
                strbuf_addf(&sb, " %s ", newdelete);

        quote_c_style(fs->path, &sb, NULL, 0);
        strbuf_addch(&sb, '\n');
        emit_diff_symbol(opt, DIFF_SYMBOL_SUMMARY,
                         sb.buf, sb.len, 0);
        strbuf_release(&sb);
}

static void show_mode_change(struct diff_options *opt, struct diff_filepair *p,
                int show_name)
{
        if (p->one->mode && p->two->mode && p->one->mode != p->two->mode) {
                struct strbuf sb = STRBUF_INIT;
                strbuf_addf(&sb, " mode change %06o => %06o",
                            p->one->mode, p->two->mode);
                if (show_name) {
                        strbuf_addch(&sb, ' ');
                        quote_c_style(p->two->path, &sb, NULL, 0);
                }
                strbuf_addch(&sb, '\n');
                emit_diff_symbol(opt, DIFF_SYMBOL_SUMMARY,
                                 sb.buf, sb.len, 0);
                strbuf_release(&sb);
        }
}

static void show_rename_copy(struct diff_options *opt, const char *renamecopy,
                struct diff_filepair *p)
{
        struct strbuf sb = STRBUF_INIT;
        struct strbuf names = STRBUF_INIT;

        pprint_rename(&names, p->one->path, p->two->path);
        strbuf_addf(&sb, " %s %s (%d%%)\n",
                    renamecopy, names.buf, similarity_index(p));
        strbuf_release(&names);
        emit_diff_symbol(opt, DIFF_SYMBOL_SUMMARY,
                                 sb.buf, sb.len, 0);
        show_mode_change(opt, p, 0);
        strbuf_release(&sb);
}

static void diff_summary(struct diff_options *opt, struct diff_filepair *p)
{
        switch(p->status) {
        case DIFF_STATUS_DELETED:
                show_file_mode_name(opt, "delete", p->one);
                break;
        case DIFF_STATUS_ADDED:
                show_file_mode_name(opt, "create", p->two);
                break;
        case DIFF_STATUS_COPIED:
                show_rename_copy(opt, "copy", p);
                break;
        case DIFF_STATUS_RENAMED:
                show_rename_copy(opt, "rename", p);
                break;
        default:
                if (p->score) {
                        struct strbuf sb = STRBUF_INIT;
                        strbuf_addstr(&sb, " rewrite ");
                        quote_c_style(p->two->path, &sb, NULL, 0);
                        strbuf_addf(&sb, " (%d%%)\n", similarity_index(p));
                        emit_diff_symbol(opt, DIFF_SYMBOL_SUMMARY,
                                         sb.buf, sb.len, 0);
                        strbuf_release(&sb);
                }
                show_mode_change(opt, p, !p->score);
                break;
        }
}

struct patch_id_t {
        git_hash_ctx *ctx;
        int patchlen;
};

static int remove_space(char *line, int len)
{
        int i;
        char *dst = line;
        unsigned char c;

        for (i = 0; i < len; i++)
                if (!isspace((c = line[i])))
                        *dst++ = c;

        return dst - line;
}

void flush_one_hunk(struct object_id *result, git_hash_ctx *ctx)
{
        unsigned char hash[GIT_MAX_RAWSZ];
        unsigned short carry = 0;
        int i;

        the_hash_algo->final_fn(hash, ctx);
        the_hash_algo->init_fn(ctx);
        /* 20-byte sum, with carry */
        for (i = 0; i < the_hash_algo->rawsz; ++i) {
                carry += result->hash[i] + hash[i];
                result->hash[i] = carry;
                carry >>= 8;
        }
}

static void patch_id_consume(void *priv, char *line, unsigned long len)
{
        struct patch_id_t *data = priv;
        int new_len;

        new_len = remove_space(line, len);

        the_hash_algo->update_fn(data->ctx, line, new_len);
        data->patchlen += new_len;
}

static void patch_id_add_string(git_hash_ctx *ctx, const char *str)
{
        the_hash_algo->update_fn(ctx, str, strlen(str));
}

static void patch_id_add_mode(git_hash_ctx *ctx, unsigned mode)
{
        /* large enough for 2^32 in octal */
        char buf[12];
        int len = xsnprintf(buf, sizeof(buf), "%06o", mode);
        the_hash_algo->update_fn(ctx, buf, len);
}

/* returns 0 upon success, and writes result into oid */
static int diff_get_patch_id(struct diff_options *options, struct object_id *oid, int diff_header_only, int stable)
{
        struct diff_queue_struct *q = &diff_queued_diff;
        int i;
        git_hash_ctx ctx;
        struct patch_id_t data;

        the_hash_algo->init_fn(&ctx);
        memset(&data, 0, sizeof(struct patch_id_t));
        data.ctx = &ctx;
        oidclr(oid);

        for (i = 0; i < q->nr; i++) {
                xpparam_t xpp;
                xdemitconf_t xecfg;
                mmfile_t mf1, mf2;
                struct diff_filepair *p = q->queue[i];
                int len1, len2;

                memset(&xpp, 0, sizeof(xpp));
                memset(&xecfg, 0, sizeof(xecfg));
                if (p->status == 0)
                        return error("internal diff status error");
                if (p->status == DIFF_STATUS_UNKNOWN)
                        continue;
                if (diff_unmodified_pair(p))
                        continue;
                if ((DIFF_FILE_VALID(p->one) && S_ISDIR(p->one->mode)) ||
                    (DIFF_FILE_VALID(p->two) && S_ISDIR(p->two->mode)))
                        continue;
                if (DIFF_PAIR_UNMERGED(p))
                        continue;

                diff_fill_oid_info(p->one, options->repo->index);
                diff_fill_oid_info(p->two, options->repo->index);

                len1 = remove_space(p->one->path, strlen(p->one->path));
                len2 = remove_space(p->two->path, strlen(p->two->path));
                patch_id_add_string(&ctx, "diff--git");
                patch_id_add_string(&ctx, "a/");
                the_hash_algo->update_fn(&ctx, p->one->path, len1);
                patch_id_add_string(&ctx, "b/");
                the_hash_algo->update_fn(&ctx, p->two->path, len2);

                if (p->one->mode == 0) {
                        patch_id_add_string(&ctx, "newfilemode");
                        patch_id_add_mode(&ctx, p->two->mode);
                        patch_id_add_string(&ctx, "---/dev/null");
                        patch_id_add_string(&ctx, "+++b/");
                        the_hash_algo->update_fn(&ctx, p->two->path, len2);
                } else if (p->two->mode == 0) {
                        patch_id_add_string(&ctx, "deletedfilemode");
                        patch_id_add_mode(&ctx, p->one->mode);
                        patch_id_add_string(&ctx, "---a/");
                        the_hash_algo->update_fn(&ctx, p->one->path, len1);
                        patch_id_add_string(&ctx, "+++/dev/null");
                } else {
                        patch_id_add_string(&ctx, "---a/");
                        the_hash_algo->update_fn(&ctx, p->one->path, len1);
                        patch_id_add_string(&ctx, "+++b/");
                        the_hash_algo->update_fn(&ctx, p->two->path, len2);
                }

                if (diff_header_only)
                        continue;

                if (fill_mmfile(options->repo, &mf1, p->one) < 0 ||
                    fill_mmfile(options->repo, &mf2, p->two) < 0)
                        return error("unable to read files to diff");

                if (diff_filespec_is_binary(options->repo, p->one) ||
                    diff_filespec_is_binary(options->repo, p->two)) {
                        the_hash_algo->update_fn(&ctx, oid_to_hex(&p->one->oid),
                                        the_hash_algo->hexsz);
                        the_hash_algo->update_fn(&ctx, oid_to_hex(&p->two->oid),
                                        the_hash_algo->hexsz);
                        continue;
                }

                xpp.flags = 0;
                xecfg.ctxlen = 3;
                xecfg.flags = 0;
                if (xdi_diff_outf(&mf1, &mf2, discard_hunk_line,
                                  patch_id_consume, &data, &xpp, &xecfg))
                        return error("unable to generate patch-id diff for %s",
                                     p->one->path);

                if (stable)
                        flush_one_hunk(oid, &ctx);
        }

        if (!stable)
                the_hash_algo->final_fn(oid->hash, &ctx);

        return 0;
}

int diff_flush_patch_id(struct diff_options *options, struct object_id *oid, int diff_header_only, int stable)
{
        struct diff_queue_struct *q = &diff_queued_diff;
        int i;
        int result = diff_get_patch_id(options, oid, diff_header_only, stable);

        for (i = 0; i < q->nr; i++)
                diff_free_filepair(q->queue[i]);

        free(q->queue);
        DIFF_QUEUE_CLEAR(q);

        return result;
}

static int is_summary_empty(const struct diff_queue_struct *q)
{
        int i;

        for (i = 0; i < q->nr; i++) {
                const struct diff_filepair *p = q->queue[i];

                switch (p->status) {
                case DIFF_STATUS_DELETED:
                case DIFF_STATUS_ADDED:
                case DIFF_STATUS_COPIED:
                case DIFF_STATUS_RENAMED:
                        return 0;
                default:
                        if (p->score)
                                return 0;
                        if (p->one->mode && p->two->mode &&
                            p->one->mode != p->two->mode)
                                return 0;
                        break;
                }
        }
        return 1;
}

static const char rename_limit_warning[] =
N_("inexact rename detection was skipped due to too many files.");

static const char degrade_cc_to_c_warning[] =
N_("only found copies from modified paths due to too many files.");

static const char rename_limit_advice[] =
N_("you may want to set your %s variable to at least "
   "%d and retry the command.");

void diff_warn_rename_limit(const char *varname, int needed, int degraded_cc)
{
        fflush(stdout);
        if (degraded_cc)
                warning(_(degrade_cc_to_c_warning));
        else if (needed)
                warning(_(rename_limit_warning));
        else
                return;
        if (0 < needed)
                warning(_(rename_limit_advice), varname, needed);
}

static void diff_flush_patch_all_file_pairs(struct diff_options *o)
{
        int i;
        static struct emitted_diff_symbols esm = EMITTED_DIFF_SYMBOLS_INIT;
        struct diff_queue_struct *q = &diff_queued_diff;

        if (WSEH_NEW & WS_RULE_MASK)
                BUG("WS rules bit mask overlaps with diff symbol flags");

        if (o->color_moved)
                o->emitted_symbols = &esm;

        for (i = 0; i < q->nr; i++) {
                struct diff_filepair *p = q->queue[i];
                if (check_pair_status(p))
                        diff_flush_patch(p, o);
        }

        if (o->emitted_symbols) {
                if (o->color_moved) {
                        struct hashmap add_lines, del_lines;

                        if (o->color_moved_ws_handling &
                            COLOR_MOVED_WS_ALLOW_INDENTATION_CHANGE)
                                o->color_moved_ws_handling |= XDF_IGNORE_WHITESPACE;

                        hashmap_init(&del_lines, moved_entry_cmp, o, 0);
                        hashmap_init(&add_lines, moved_entry_cmp, o, 0);

                        add_lines_to_move_detection(o, &add_lines, &del_lines);
                        mark_color_as_moved(o, &add_lines, &del_lines);
                        if (o->color_moved == COLOR_MOVED_ZEBRA_DIM)
                                dim_moved_lines(o);

                        hashmap_free_entries(&add_lines, struct moved_entry,
                                                ent);
                        hashmap_free_entries(&del_lines, struct moved_entry,
                                                ent);
                }

                for (i = 0; i < esm.nr; i++)
                        emit_diff_symbol_from_struct(o, &esm.buf[i]);

                for (i = 0; i < esm.nr; i++)
                        free((void *)esm.buf[i].line);
                esm.nr = 0;

                o->emitted_symbols = NULL;
        }
}

void diff_flush(struct diff_options *options)
{
        struct diff_queue_struct *q = &diff_queued_diff;
        int i, output_format = options->output_format;
        int separator = 0;
        int dirstat_by_line = 0;

        /*
         * Order: raw, stat, summary, patch
         * or:    name/name-status/checkdiff (other bits clear)
         */
        if (!q->nr)
                goto free_queue;

        if (output_format & (DIFF_FORMAT_RAW |
                             DIFF_FORMAT_NAME |
                             DIFF_FORMAT_NAME_STATUS |
                             DIFF_FORMAT_CHECKDIFF)) {
                for (i = 0; i < q->nr; i++) {
                        struct diff_filepair *p = q->queue[i];
                        if (check_pair_status(p))
                                flush_one_pair(p, options);
                }
                separator++;
        }

        if (output_format & DIFF_FORMAT_DIRSTAT && options->flags.dirstat_by_line)
                dirstat_by_line = 1;

        if (output_format & (DIFF_FORMAT_DIFFSTAT|DIFF_FORMAT_SHORTSTAT|DIFF_FORMAT_NUMSTAT) ||
            dirstat_by_line) {
                struct diffstat_t diffstat;

                compute_diffstat(options, &diffstat, q);
                if (output_format & DIFF_FORMAT_NUMSTAT)
                        show_numstat(&diffstat, options);
                if (output_format & DIFF_FORMAT_DIFFSTAT)
                        show_stats(&diffstat, options);
                if (output_format & DIFF_FORMAT_SHORTSTAT)
                        show_shortstats(&diffstat, options);
                if (output_format & DIFF_FORMAT_DIRSTAT && dirstat_by_line)
                        show_dirstat_by_line(&diffstat, options);
                free_diffstat_info(&diffstat);
                separator++;
        }
        if ((output_format & DIFF_FORMAT_DIRSTAT) && !dirstat_by_line)
                show_dirstat(options);

        if (output_format & DIFF_FORMAT_SUMMARY && !is_summary_empty(q)) {
                for (i = 0; i < q->nr; i++) {
                        diff_summary(options, q->queue[i]);
                }
                separator++;
        }

        if (output_format & DIFF_FORMAT_NO_OUTPUT &&
            options->flags.exit_with_status &&
            options->flags.diff_from_contents) {
                /*
                 * run diff_flush_patch for the exit status. setting
                 * options->file to /dev/null should be safe, because we
                 * aren't supposed to produce any output anyway.
                 */
                if (options->close_file)
                        fclose(options->file);
                options->file = xfopen("/dev/null", "w");
                options->close_file = 1;
                options->color_moved = 0;
                for (i = 0; i < q->nr; i++) {
                        struct diff_filepair *p = q->queue[i];
                        if (check_pair_status(p))
                                diff_flush_patch(p, options);
                        if (options->found_changes)
                                break;
                }
        }

        if (output_format & DIFF_FORMAT_PATCH) {
                if (separator) {
                        emit_diff_symbol(options, DIFF_SYMBOL_SEPARATOR, NULL, 0, 0);
                        if (options->stat_sep)
                                /* attach patch instead of inline */
                                emit_diff_symbol(options, DIFF_SYMBOL_STAT_SEP,
                                                 NULL, 0, 0);
                }

                diff_flush_patch_all_file_pairs(options);
        }

        if (output_format & DIFF_FORMAT_CALLBACK)
                options->format_callback(q, options, options->format_callback_data);

        for (i = 0; i < q->nr; i++)
                diff_free_filepair(q->queue[i]);
free_queue:
        free(q->queue);
        DIFF_QUEUE_CLEAR(q);
        if (options->close_file)
                fclose(options->file);

        /*
         * Report the content-level differences with HAS_CHANGES;
         * diff_addremove/diff_change does not set the bit when
         * DIFF_FROM_CONTENTS is in effect (e.g. with -w).
         */
        if (options->flags.diff_from_contents) {
                if (options->found_changes)
                        options->flags.has_changes = 1;
                else
                        options->flags.has_changes = 0;
        }
}

static int match_filter(const struct diff_options *options, const struct diff_filepair *p)
{
        return (((p->status == DIFF_STATUS_MODIFIED) &&
                 ((p->score &&
                   filter_bit_tst(DIFF_STATUS_FILTER_BROKEN, options)) ||
                  (!p->score &&
                   filter_bit_tst(DIFF_STATUS_MODIFIED, options)))) ||
                ((p->status != DIFF_STATUS_MODIFIED) &&
                 filter_bit_tst(p->status, options)));
}

static void diffcore_apply_filter(struct diff_options *options)
{
        int i;
        struct diff_queue_struct *q = &diff_queued_diff;
        struct diff_queue_struct outq;

        DIFF_QUEUE_CLEAR(&outq);

        if (!options->filter)
                return;

        if (filter_bit_tst(DIFF_STATUS_FILTER_AON, options)) {
                int found;
                for (i = found = 0; !found && i < q->nr; i++) {
                        if (match_filter(options, q->queue[i]))
                                found++;
                }
                if (found)
                        return;

                /* otherwise we will clear the whole queue
                 * by copying the empty outq at the end of this
                 * function, but first clear the current entries
                 * in the queue.
                 */
                for (i = 0; i < q->nr; i++)
                        diff_free_filepair(q->queue[i]);
        }
        else {
                /* Only the matching ones */
                for (i = 0; i < q->nr; i++) {
                        struct diff_filepair *p = q->queue[i];
                        if (match_filter(options, p))
                                diff_q(&outq, p);
                        else
                                diff_free_filepair(p);
                }
        }
        free(q->queue);
        *q = outq;
}

/* Check whether two filespecs with the same mode and size are identical */
static int diff_filespec_is_identical(struct repository *r,
                                      struct diff_filespec *one,
                                      struct diff_filespec *two)
{
        if (S_ISGITLINK(one->mode))
                return 0;
        if (diff_populate_filespec(r, one, 0))
                return 0;
        if (diff_populate_filespec(r, two, 0))
                return 0;
        return !memcmp(one->data, two->data, one->size);
}

static int diff_filespec_check_stat_unmatch(struct repository *r,
                                            struct diff_filepair *p)
{
        if (p->done_skip_stat_unmatch)
                return p->skip_stat_unmatch_result;

        p->done_skip_stat_unmatch = 1;
        p->skip_stat_unmatch_result = 0;
        /*
         * 1. Entries that come from stat info dirtiness
         *    always have both sides (iow, not create/delete),
         *    one side of the object name is unknown, with
         *    the same mode and size.  Keep the ones that
         *    do not match these criteria.  They have real
         *    differences.
         *
         * 2. At this point, the file is known to be modified,
         *    with the same mode and size, and the object
         *    name of one side is unknown.  Need to inspect
         *    the identical contents.
         */
        if (!DIFF_FILE_VALID(p->one) || /* (1) */
            !DIFF_FILE_VALID(p->two) ||
            (p->one->oid_valid && p->two->oid_valid) ||
            (p->one->mode != p->two->mode) ||
            diff_populate_filespec(r, p->one, CHECK_SIZE_ONLY) ||
            diff_populate_filespec(r, p->two, CHECK_SIZE_ONLY) ||
            (p->one->size != p->two->size) ||
            !diff_filespec_is_identical(r, p->one, p->two)) /* (2) */
                p->skip_stat_unmatch_result = 1;
        return p->skip_stat_unmatch_result;
}

static void diffcore_skip_stat_unmatch(struct diff_options *diffopt)
{
        int i;
        struct diff_queue_struct *q = &diff_queued_diff;
        struct diff_queue_struct outq;
        DIFF_QUEUE_CLEAR(&outq);

        for (i = 0; i < q->nr; i++) {
                struct diff_filepair *p = q->queue[i];

                if (diff_filespec_check_stat_unmatch(diffopt->repo, p))
                        diff_q(&outq, p);
                else {
                        /*
                         * The caller can subtract 1 from skip_stat_unmatch
                         * to determine how many paths were dirty only
                         * due to stat info mismatch.
                         */
                        if (!diffopt->flags.no_index)
                                diffopt->skip_stat_unmatch++;
                        diff_free_filepair(p);
                }
        }
        free(q->queue);
        *q = outq;
}

static int diffnamecmp(const void *a_, const void *b_)
{
        const struct diff_filepair *a = *((const struct diff_filepair **)a_);
        const struct diff_filepair *b = *((const struct diff_filepair **)b_);
        const char *name_a, *name_b;

        name_a = a->one ? a->one->path : a->two->path;
        name_b = b->one ? b->one->path : b->two->path;
        return strcmp(name_a, name_b);
}

void diffcore_fix_diff_index(void)
{
        struct diff_queue_struct *q = &diff_queued_diff;
        QSORT(q->queue, q->nr, diffnamecmp);
}

static void add_if_missing(struct repository *r,
                           struct oid_array *to_fetch,
                           const struct diff_filespec *filespec)
{
        if (filespec && filespec->oid_valid &&
            !S_ISGITLINK(filespec->mode) &&
            oid_object_info_extended(r, &filespec->oid, NULL,
                                     OBJECT_INFO_FOR_PREFETCH))
                oid_array_append(to_fetch, &filespec->oid);
}

void diffcore_std(struct diff_options *options)
{
        if (options->repo == the_repository && has_promisor_remote()) {
                /*
                 * Prefetch the diff pairs that are about to be flushed.
                 */
                int i;
                struct diff_queue_struct *q = &diff_queued_diff;
                struct oid_array to_fetch = OID_ARRAY_INIT;

                for (i = 0; i < q->nr; i++) {
                        struct diff_filepair *p = q->queue[i];
                        add_if_missing(options->repo, &to_fetch, p->one);
                        add_if_missing(options->repo, &to_fetch, p->two);
                }
                if (to_fetch.nr)
                        /*
                         * NEEDSWORK: Consider deduplicating the OIDs sent.
                         */
                        promisor_remote_get_direct(options->repo,
                                                   to_fetch.oid, to_fetch.nr);
                oid_array_clear(&to_fetch);
        }

        /* NOTE please keep the following in sync with diff_tree_combined() */
        if (options->skip_stat_unmatch)
                diffcore_skip_stat_unmatch(options);
        if (!options->found_follow) {
                /* See try_to_follow_renames() in tree-diff.c */
                if (options->break_opt != -1)
                        diffcore_break(options->repo,
                                       options->break_opt);
                if (options->detect_rename)
                        diffcore_rename(options);
                if (options->break_opt != -1)
                        diffcore_merge_broken();
        }
        if (options->pickaxe_opts & DIFF_PICKAXE_KINDS_MASK)
                diffcore_pickaxe(options);
        if (options->orderfile)
                diffcore_order(options->orderfile);
        if (!options->found_follow)
                /* See try_to_follow_renames() in tree-diff.c */
                diff_resolve_rename_copy();
        diffcore_apply_filter(options);

        if (diff_queued_diff.nr && !options->flags.diff_from_contents)
                options->flags.has_changes = 1;
        else
                options->flags.has_changes = 0;

        options->found_follow = 0;
}

int diff_result_code(struct diff_options *opt, int status)
{
        int result = 0;

        diff_warn_rename_limit("diff.renameLimit",
                               opt->needed_rename_limit,
                               opt->degraded_cc_to_c);
        if (!opt->flags.exit_with_status &&
            !(opt->output_format & DIFF_FORMAT_CHECKDIFF))
                return status;
        if (opt->flags.exit_with_status &&
            opt->flags.has_changes)
                result |= 01;
        if ((opt->output_format & DIFF_FORMAT_CHECKDIFF) &&
            opt->flags.check_failed)
                result |= 02;
        return result;
}

int diff_can_quit_early(struct diff_options *opt)
{
        return (opt->flags.quick &&
                !opt->filter &&
                opt->flags.has_changes);
}

/*
 * Shall changes to this submodule be ignored?
 *
 * Submodule changes can be configured to be ignored separately for each path,
 * but that configuration can be overridden from the command line.
 */
static int is_submodule_ignored(const char *path, struct diff_options *options)
{
        int ignored = 0;
        struct diff_flags orig_flags = options->flags;
        if (!options->flags.override_submodule_config)
                set_diffopt_flags_from_submodule_config(options, path);
        if (options->flags.ignore_submodules)
                ignored = 1;
        options->flags = orig_flags;
        return ignored;
}

void compute_diffstat(struct diff_options *options,
                      struct diffstat_t *diffstat,
                      struct diff_queue_struct *q)
{
        int i;

        memset(diffstat, 0, sizeof(struct diffstat_t));
        for (i = 0; i < q->nr; i++) {
                struct diff_filepair *p = q->queue[i];
                if (check_pair_status(p))
                        diff_flush_stat(p, options, diffstat);
        }
}

void diff_addremove(struct diff_options *options,
                    int addremove, unsigned mode,
                    const struct object_id *oid,
                    int oid_valid,
                    const char *concatpath, unsigned dirty_submodule)
{
        struct diff_filespec *one, *two;

        if (S_ISGITLINK(mode) && is_submodule_ignored(concatpath, options))
                return;

        /* This may look odd, but it is a preparation for
         * feeding "there are unchanged files which should
         * not produce diffs, but when you are doing copy
         * detection you would need them, so here they are"
         * entries to the diff-core.  They will be prefixed
         * with something like '=' or '*' (I haven't decided
         * which but should not make any difference).
         * Feeding the same new and old to diff_change()
         * also has the same effect.
         * Before the final output happens, they are pruned after
         * merged into rename/copy pairs as appropriate.
         */
        if (options->flags.reverse_diff)
                addremove = (addremove == '+' ? '-' :
                             addremove == '-' ? '+' : addremove);

        if (options->prefix &&
            strncmp(concatpath, options->prefix, options->prefix_length))
                return;

        one = alloc_filespec(concatpath);
        two = alloc_filespec(concatpath);

        if (addremove != '+')
                fill_filespec(one, oid, oid_valid, mode);
        if (addremove != '-') {
                fill_filespec(two, oid, oid_valid, mode);
                two->dirty_submodule = dirty_submodule;
        }

        diff_queue(&diff_queued_diff, one, two);
        if (!options->flags.diff_from_contents)
                options->flags.has_changes = 1;
}

void diff_change(struct diff_options *options,
                 unsigned old_mode, unsigned new_mode,
                 const struct object_id *old_oid,
                 const struct object_id *new_oid,
                 int old_oid_valid, int new_oid_valid,
                 const char *concatpath,
                 unsigned old_dirty_submodule, unsigned new_dirty_submodule)
{
        struct diff_filespec *one, *two;
        struct diff_filepair *p;

        if (S_ISGITLINK(old_mode) && S_ISGITLINK(new_mode) &&
            is_submodule_ignored(concatpath, options))
                return;

        if (options->flags.reverse_diff) {
                SWAP(old_mode, new_mode);
                SWAP(old_oid, new_oid);
                SWAP(old_oid_valid, new_oid_valid);
                SWAP(old_dirty_submodule, new_dirty_submodule);
        }

        if (options->prefix &&
            strncmp(concatpath, options->prefix, options->prefix_length))
                return;

        one = alloc_filespec(concatpath);
        two = alloc_filespec(concatpath);
        fill_filespec(one, old_oid, old_oid_valid, old_mode);
        fill_filespec(two, new_oid, new_oid_valid, new_mode);
        one->dirty_submodule = old_dirty_submodule;
        two->dirty_submodule = new_dirty_submodule;
        p = diff_queue(&diff_queued_diff, one, two);

        if (options->flags.diff_from_contents)
                return;

        if (options->flags.quick && options->skip_stat_unmatch &&
            !diff_filespec_check_stat_unmatch(options->repo, p))
                return;

        options->flags.has_changes = 1;
}

struct diff_filepair *diff_unmerge(struct diff_options *options, const char *path)
{
        struct diff_filepair *pair;
        struct diff_filespec *one, *two;

        if (options->prefix &&
            strncmp(path, options->prefix, options->prefix_length))
                return NULL;

        one = alloc_filespec(path);
        two = alloc_filespec(path);
        pair = diff_queue(&diff_queued_diff, one, two);
        pair->is_unmerged = 1;
        return pair;
}

static char *run_textconv(struct repository *r,
                          const char *pgm,
                          struct diff_filespec *spec,
                          size_t *outsize)
{
        struct diff_tempfile *temp;
        const char *argv[3];
        const char **arg = argv;
        struct child_process child = CHILD_PROCESS_INIT;
        struct strbuf buf = STRBUF_INIT;
        int err = 0;

        temp = prepare_temp_file(r, spec->path, spec);
        *arg++ = pgm;
        *arg++ = temp->name;
        *arg = NULL;

        child.use_shell = 1;
        child.argv = argv;
        child.out = -1;
        if (start_command(&child)) {
                remove_tempfile();
                return NULL;
        }

        if (strbuf_read(&buf, child.out, 0) < 0)
                err = error("error reading from textconv command '%s'", pgm);
        close(child.out);

        if (finish_command(&child) || err) {
                strbuf_release(&buf);
                remove_tempfile();
                return NULL;
        }
        remove_tempfile();

        return strbuf_detach(&buf, outsize);
}

size_t fill_textconv(struct repository *r,
                     struct userdiff_driver *driver,
                     struct diff_filespec *df,
                     char **outbuf)
{
        size_t size;

        if (!driver) {
                if (!DIFF_FILE_VALID(df)) {
                        *outbuf = "";
                        return 0;
                }
                if (diff_populate_filespec(r, df, 0))
                        die("unable to read files to diff");
                *outbuf = df->data;
                return df->size;
        }

        if (!driver->textconv)
                BUG("fill_textconv called with non-textconv driver");

        if (driver->textconv_cache && df->oid_valid) {
                *outbuf = notes_cache_get(driver->textconv_cache,
                                          &df->oid,
                                          &size);
                if (*outbuf)
                        return size;
        }

        *outbuf = run_textconv(r, driver->textconv, df, &size);
        if (!*outbuf)
                die("unable to read files to diff");

        if (driver->textconv_cache && df->oid_valid) {
                /* ignore errors, as we might be in a readonly repository */
                notes_cache_put(driver->textconv_cache, &df->oid, *outbuf,
                                size);
                /*
                 * we could save up changes and flush them all at the end,
                 * but we would need an extra call after all diffing is done.
                 * Since generating a cache entry is the slow path anyway,
                 * this extra overhead probably isn't a big deal.
                 */
                notes_cache_write(driver->textconv_cache);
        }

        return size;
}

int textconv_object(struct repository *r,
                    const char *path,
                    unsigned mode,
                    const struct object_id *oid,
                    int oid_valid,
                    char **buf,
                    unsigned long *buf_size)
{
        struct diff_filespec *df;
        struct userdiff_driver *textconv;

        df = alloc_filespec(path);
        fill_filespec(df, oid, oid_valid, mode);
        textconv = get_textconv(r, df);
        if (!textconv) {
                free_filespec(df);
                return 0;
        }

        *buf_size = fill_textconv(r, textconv, df, buf);
        free_filespec(df);
        return 1;
}

void setup_diff_pager(struct diff_options *opt)
{
        /*
         * If the user asked for our exit code, then either they want --quiet
         * or --exit-code. We should definitely not bother with a pager in the
         * former case, as we will generate no output. Since we still properly
         * report our exit code even when a pager is run, we _could_ run a
         * pager with --exit-code. But since we have not done so historically,
         * and because it is easy to find people oneline advising "git diff
         * --exit-code" in hooks and other scripts, we do not do so.
         */
        if (!opt->flags.exit_with_status &&
            check_pager_config("diff") != 0)
                setup_pager();
}