git.oblomov.eu Git - git/blob - diff.c

   1 /*
   2  * Copyright (C) 2005 Junio C Hamano
   3  */
   4 #include "cache.h"
   5 #include "tempfile.h"
   6 #include "quote.h"
   7 #include "diff.h"
   8 #include "diffcore.h"
   9 #include "delta.h"
  10 #include "xdiff-interface.h"
  11 #include "color.h"
  12 #include "attr.h"
  13 #include "run-command.h"
  14 #include "utf8.h"
  15 #include "userdiff.h"
  16 #include "submodule-config.h"
  17 #include "submodule.h"
  18 #include "ll-merge.h"
  19 #include "string-list.h"
  20 #include "argv-array.h"
  21 #include "graph.h"
  22
  23 #ifdef NO_FAST_WORKING_DIRECTORY
  24 #define FAST_WORKING_DIRECTORY 0
  25 #else
  26 #define FAST_WORKING_DIRECTORY 1
  27 #endif
  28
  29 static int diff_detect_rename_default;
  30 static int diff_indent_heuristic; /* experimental */
  31 static int diff_rename_limit_default = 400;
  32 static int diff_suppress_blank_empty;
  33 static int diff_use_color_default = -1;
  34 static int diff_context_default = 3;
  35 static int diff_interhunk_context_default;
  36 static const char *diff_word_regex_cfg;
  37 static const char *external_diff_cmd_cfg;
  38 static const char *diff_order_file_cfg;
  39 int diff_auto_refresh_index = 1;
  40 static int diff_mnemonic_prefix;
  41 static int diff_no_prefix;
  42 static int diff_stat_graph_width;
  43 static int diff_dirstat_permille_default = 30;
  44 static struct diff_options default_diff_options;
  45 static long diff_algorithm;
  46 static unsigned ws_error_highlight_default = WSEH_NEW;
  47
  48 static char diff_colors[][COLOR_MAXLEN] = {
  49         GIT_COLOR_RESET,
  50         GIT_COLOR_NORMAL,       /* CONTEXT */
  51         GIT_COLOR_BOLD,         /* METAINFO */
  52         GIT_COLOR_CYAN,         /* FRAGINFO */
  53         GIT_COLOR_RED,          /* OLD */
  54         GIT_COLOR_GREEN,        /* NEW */
  55         GIT_COLOR_YELLOW,       /* COMMIT */
  56         GIT_COLOR_BG_RED,       /* WHITESPACE */
  57         GIT_COLOR_NORMAL,       /* FUNCINFO */
  58 };
  59
  60 static NORETURN void die_want_option(const char *option_name)
  61 {
  62         die(_("option '%s' requires a value"), option_name);
  63 }
  64
  65 static int parse_diff_color_slot(const char *var)
  66 {
  67         if (!strcasecmp(var, "context") || !strcasecmp(var, "plain"))
  68                 return DIFF_CONTEXT;
  69         if (!strcasecmp(var, "meta"))
  70                 return DIFF_METAINFO;
  71         if (!strcasecmp(var, "frag"))
  72                 return DIFF_FRAGINFO;
  73         if (!strcasecmp(var, "old"))
  74                 return DIFF_FILE_OLD;
  75         if (!strcasecmp(var, "new"))
  76                 return DIFF_FILE_NEW;
  77         if (!strcasecmp(var, "commit"))
  78                 return DIFF_COMMIT;
  79         if (!strcasecmp(var, "whitespace"))
  80                 return DIFF_WHITESPACE;
  81         if (!strcasecmp(var, "func"))
  82                 return DIFF_FUNCINFO;
  83         return -1;
  84 }
  85
  86 static int parse_dirstat_params(struct diff_options *options, const char *params_string,
  87                                 struct strbuf *errmsg)
  88 {
  89         char *params_copy = xstrdup(params_string);
  90         struct string_list params = STRING_LIST_INIT_NODUP;
  91         int ret = 0;
  92         int i;
  93
  94         if (*params_copy)
  95                 string_list_split_in_place(&params, params_copy, ',', -1);
  96         for (i = 0; i < params.nr; i++) {
  97                 const char *p = params.items[i].string;
  98                 if (!strcmp(p, "changes")) {
  99                         DIFF_OPT_CLR(options, DIRSTAT_BY_LINE);
 100                         DIFF_OPT_CLR(options, DIRSTAT_BY_FILE);
 101                 } else if (!strcmp(p, "lines")) {
 102                         DIFF_OPT_SET(options, DIRSTAT_BY_LINE);
 103                         DIFF_OPT_CLR(options, DIRSTAT_BY_FILE);
 104                 } else if (!strcmp(p, "files")) {
 105                         DIFF_OPT_CLR(options, DIRSTAT_BY_LINE);
 106                         DIFF_OPT_SET(options, DIRSTAT_BY_FILE);
 107                 } else if (!strcmp(p, "noncumulative")) {
 108                         DIFF_OPT_CLR(options, DIRSTAT_CUMULATIVE);
 109                 } else if (!strcmp(p, "cumulative")) {
 110                         DIFF_OPT_SET(options, DIRSTAT_CUMULATIVE);
 111                 } else if (isdigit(*p)) {
 112                         char *end;
 113                         int permille = strtoul(p, &end, 10) * 10;
 114                         if (*end == '.' && isdigit(*++end)) {
 115                                 /* only use first digit */
 116                                 permille += *end - '0';
 117                                 /* .. and ignore any further digits */
 118                                 while (isdigit(*++end))
 119                                         ; /* nothing */
 120                         }
 121                         if (!*end)
 122                                 options->dirstat_permille = permille;
 123                         else {
 124                                 strbuf_addf(errmsg, _("  Failed to parse dirstat cut-off percentage '%s'\n"),
 125                                             p);
 126                                 ret++;
 127                         }
 128                 } else {
 129                         strbuf_addf(errmsg, _("  Unknown dirstat parameter '%s'\n"), p);
 130                         ret++;
 131                 }
 132
 133         }
 134         string_list_clear(&params, 0);
 135         free(params_copy);
 136         return ret;
 137 }
 138
 139 static int parse_submodule_params(struct diff_options *options, const char *value)
 140 {
 141         if (!strcmp(value, "log"))
 142                 options->submodule_format = DIFF_SUBMODULE_LOG;
 143         else if (!strcmp(value, "short"))
 144                 options->submodule_format = DIFF_SUBMODULE_SHORT;
 145         else if (!strcmp(value, "diff"))
 146                 options->submodule_format = DIFF_SUBMODULE_INLINE_DIFF;
 147         else
 148                 return -1;
 149         return 0;
 150 }
 151
 152 static int git_config_rename(const char *var, const char *value)
 153 {
 154         if (!value)
 155                 return DIFF_DETECT_RENAME;
 156         if (!strcasecmp(value, "copies") || !strcasecmp(value, "copy"))
 157                 return  DIFF_DETECT_COPY;
 158         return git_config_bool(var,value) ? DIFF_DETECT_RENAME : 0;
 159 }
 160
 161 long parse_algorithm_value(const char *value)
 162 {
 163         if (!value)
 164                 return -1;
 165         else if (!strcasecmp(value, "myers") || !strcasecmp(value, "default"))
 166                 return 0;
 167         else if (!strcasecmp(value, "minimal"))
 168                 return XDF_NEED_MINIMAL;
 169         else if (!strcasecmp(value, "patience"))
 170                 return XDF_PATIENCE_DIFF;
 171         else if (!strcasecmp(value, "histogram"))
 172                 return XDF_HISTOGRAM_DIFF;
 173         return -1;
 174 }
 175
 176 static int parse_one_token(const char **arg, const char *token)
 177 {
 178         const char *rest;
 179         if (skip_prefix(*arg, token, &rest) && (!*rest || *rest == ',')) {
 180                 *arg = rest;
 181                 return 1;
 182         }
 183         return 0;
 184 }
 185
 186 static int parse_ws_error_highlight(const char *arg)
 187 {
 188         const char *orig_arg = arg;
 189         unsigned val = 0;
 190
 191         while (*arg) {
 192                 if (parse_one_token(&arg, "none"))
 193                         val = 0;
 194                 else if (parse_one_token(&arg, "default"))
 195                         val = WSEH_NEW;
 196                 else if (parse_one_token(&arg, "all"))
 197                         val = WSEH_NEW | WSEH_OLD | WSEH_CONTEXT;
 198                 else if (parse_one_token(&arg, "new"))
 199                         val |= WSEH_NEW;
 200                 else if (parse_one_token(&arg, "old"))
 201                         val |= WSEH_OLD;
 202                 else if (parse_one_token(&arg, "context"))
 203                         val |= WSEH_CONTEXT;
 204                 else {
 205                         return -1 - (int)(arg - orig_arg);
 206                 }
 207                 if (*arg)
 208                         arg++;
 209         }
 210         return val;
 211 }
 212
 213 /*
 214  * These are to give UI layer defaults.
 215  * The core-level commands such as git-diff-files should
 216  * never be affected by the setting of diff.renames
 217  * the user happens to have in the configuration file.
 218  */
 219 void init_diff_ui_defaults(void)
 220 {
 221         diff_detect_rename_default = 1;
 222 }
 223
 224 int git_diff_heuristic_config(const char *var, const char *value, void *cb)
 225 {
 226         if (!strcmp(var, "diff.indentheuristic"))
 227                 diff_indent_heuristic = git_config_bool(var, value);
 228         return 0;
 229 }
 230
 231 int git_diff_ui_config(const char *var, const char *value, void *cb)
 232 {
 233         if (!strcmp(var, "diff.color") || !strcmp(var, "color.diff")) {
 234                 diff_use_color_default = git_config_colorbool(var, value);
 235                 return 0;
 236         }
 237         if (!strcmp(var, "diff.context")) {
 238                 diff_context_default = git_config_int(var, value);
 239                 if (diff_context_default < 0)
 240                         return -1;
 241                 return 0;
 242         }
 243         if (!strcmp(var, "diff.interhunkcontext")) {
 244                 diff_interhunk_context_default = git_config_int(var, value);
 245                 if (diff_interhunk_context_default < 0)
 246                         return -1;
 247                 return 0;
 248         }
 249         if (!strcmp(var, "diff.renames")) {
 250                 diff_detect_rename_default = git_config_rename(var, value);
 251                 return 0;
 252         }
 253         if (!strcmp(var, "diff.autorefreshindex")) {
 254                 diff_auto_refresh_index = git_config_bool(var, value);
 255                 return 0;
 256         }
 257         if (!strcmp(var, "diff.mnemonicprefix")) {
 258                 diff_mnemonic_prefix = git_config_bool(var, value);
 259                 return 0;
 260         }
 261         if (!strcmp(var, "diff.noprefix")) {
 262                 diff_no_prefix = git_config_bool(var, value);
 263                 return 0;
 264         }
 265         if (!strcmp(var, "diff.statgraphwidth")) {
 266                 diff_stat_graph_width = git_config_int(var, value);
 267                 return 0;
 268         }
 269         if (!strcmp(var, "diff.external"))
 270                 return git_config_string(&external_diff_cmd_cfg, var, value);
 271         if (!strcmp(var, "diff.wordregex"))
 272                 return git_config_string(&diff_word_regex_cfg, var, value);
 273         if (!strcmp(var, "diff.orderfile"))
 274                 return git_config_pathname(&diff_order_file_cfg, var, value);
 275
 276         if (!strcmp(var, "diff.ignoresubmodules"))
 277                 handle_ignore_submodules_arg(&default_diff_options, value);
 278
 279         if (!strcmp(var, "diff.submodule")) {
 280                 if (parse_submodule_params(&default_diff_options, value))
 281                         warning(_("Unknown value for 'diff.submodule' config variable: '%s'"),
 282                                 value);
 283                 return 0;
 284         }
 285
 286         if (!strcmp(var, "diff.algorithm")) {
 287                 diff_algorithm = parse_algorithm_value(value);
 288                 if (diff_algorithm < 0)
 289                         return -1;
 290                 return 0;
 291         }
 292
 293         if (git_diff_heuristic_config(var, value, cb) < 0)
 294                 return -1;
 295
 296         if (!strcmp(var, "diff.wserrorhighlight")) {
 297                 int val = parse_ws_error_highlight(value);
 298                 if (val < 0)
 299                         return -1;
 300                 ws_error_highlight_default = val;
 301                 return 0;
 302         }
 303
 304         if (git_color_config(var, value, cb) < 0)
 305                 return -1;
 306
 307         return git_diff_basic_config(var, value, cb);
 308 }
 309
 310 int git_diff_basic_config(const char *var, const char *value, void *cb)
 311 {
 312         const char *name;
 313
 314         if (!strcmp(var, "diff.renamelimit")) {
 315                 diff_rename_limit_default = git_config_int(var, value);
 316                 return 0;
 317         }
 318
 319         if (userdiff_config(var, value) < 0)
 320                 return -1;
 321
 322         if (skip_prefix(var, "diff.color.", &name) ||
 323             skip_prefix(var, "color.diff.", &name)) {
 324                 int slot = parse_diff_color_slot(name);
 325                 if (slot < 0)
 326                         return 0;
 327                 if (!value)
 328                         return config_error_nonbool(var);
 329                 return color_parse(value, diff_colors[slot]);
 330         }
 331
 332         /* like GNU diff's --suppress-blank-empty option  */
 333         if (!strcmp(var, "diff.suppressblankempty") ||
 334                         /* for backwards compatibility */
 335                         !strcmp(var, "diff.suppress-blank-empty")) {
 336                 diff_suppress_blank_empty = git_config_bool(var, value);
 337                 return 0;
 338         }
 339
 340         if (!strcmp(var, "diff.dirstat")) {
 341                 struct strbuf errmsg = STRBUF_INIT;
 342                 default_diff_options.dirstat_permille = diff_dirstat_permille_default;
 343                 if (parse_dirstat_params(&default_diff_options, value, &errmsg))
 344                         warning(_("Found errors in 'diff.dirstat' config variable:\n%s"),
 345                                 errmsg.buf);
 346                 strbuf_release(&errmsg);
 347                 diff_dirstat_permille_default = default_diff_options.dirstat_permille;
 348                 return 0;
 349         }
 350
 351         if (starts_with(var, "submodule."))
 352                 return parse_submodule_config_option(var, value);
 353
 354         return git_default_config(var, value, cb);
 355 }
 356
 357 static char *quote_two(const char *one, const char *two)
 358 {
 359         int need_one = quote_c_style(one, NULL, NULL, 1);
 360         int need_two = quote_c_style(two, NULL, NULL, 1);
 361         struct strbuf res = STRBUF_INIT;
 362
 363         if (need_one + need_two) {
 364                 strbuf_addch(&res, '"');
 365                 quote_c_style(one, &res, NULL, 1);
 366                 quote_c_style(two, &res, NULL, 1);
 367                 strbuf_addch(&res, '"');
 368         } else {
 369                 strbuf_addstr(&res, one);
 370                 strbuf_addstr(&res, two);
 371         }
 372         return strbuf_detach(&res, NULL);
 373 }
 374
 375 static const char *external_diff(void)
 376 {
 377         static const char *external_diff_cmd = NULL;
 378         static int done_preparing = 0;
 379
 380         if (done_preparing)
 381                 return external_diff_cmd;
 382         external_diff_cmd = getenv("GIT_EXTERNAL_DIFF");
 383         if (!external_diff_cmd)
 384                 external_diff_cmd = external_diff_cmd_cfg;
 385         done_preparing = 1;
 386         return external_diff_cmd;
 387 }
 388
 389 /*
 390  * Keep track of files used for diffing. Sometimes such an entry
 391  * refers to a temporary file, sometimes to an existing file, and
 392  * sometimes to "/dev/null".
 393  */
 394 static struct diff_tempfile {
 395         /*
 396          * filename external diff should read from, or NULL if this
 397          * entry is currently not in use:
 398          */
 399         const char *name;
 400
 401         char hex[GIT_SHA1_HEXSZ + 1];
 402         char mode[10];
 403
 404         /*
 405          * If this diff_tempfile instance refers to a temporary file,
 406          * this tempfile object is used to manage its lifetime.
 407          */
 408         struct tempfile tempfile;
 409 } diff_temp[2];
 410
 411 typedef unsigned long (*sane_truncate_fn)(char *line, unsigned long len);
 412
 413 struct emit_callback {
 414         int color_diff;
 415         unsigned ws_rule;
 416         int blank_at_eof_in_preimage;
 417         int blank_at_eof_in_postimage;
 418         int lno_in_preimage;
 419         int lno_in_postimage;
 420         sane_truncate_fn truncate;
 421         const char **label_path;
 422         struct diff_words_data *diff_words;
 423         struct diff_options *opt;
 424         struct strbuf *header;
 425 };
 426
 427 static int count_lines(const char *data, int size)
 428 {
 429         int count, ch, completely_empty = 1, nl_just_seen = 0;
 430         count = 0;
 431         while (0 < size--) {
 432                 ch = *data++;
 433                 if (ch == '\n') {
 434                         count++;
 435                         nl_just_seen = 1;
 436                         completely_empty = 0;
 437                 }
 438                 else {
 439                         nl_just_seen = 0;
 440                         completely_empty = 0;
 441                 }
 442         }
 443         if (completely_empty)
 444                 return 0;
 445         if (!nl_just_seen)
 446                 count++; /* no trailing newline */
 447         return count;
 448 }
 449
 450 static int fill_mmfile(mmfile_t *mf, struct diff_filespec *one)
 451 {
 452         if (!DIFF_FILE_VALID(one)) {
 453                 mf->ptr = (char *)""; /* does not matter */
 454                 mf->size = 0;
 455                 return 0;
 456         }
 457         else if (diff_populate_filespec(one, 0))
 458                 return -1;
 459
 460         mf->ptr = one->data;
 461         mf->size = one->size;
 462         return 0;
 463 }
 464
 465 /* like fill_mmfile, but only for size, so we can avoid retrieving blob */
 466 static unsigned long diff_filespec_size(struct diff_filespec *one)
 467 {
 468         if (!DIFF_FILE_VALID(one))
 469                 return 0;
 470         diff_populate_filespec(one, CHECK_SIZE_ONLY);
 471         return one->size;
 472 }
 473
 474 static int count_trailing_blank(mmfile_t *mf, unsigned ws_rule)
 475 {
 476         char *ptr = mf->ptr;
 477         long size = mf->size;
 478         int cnt = 0;
 479
 480         if (!size)
 481                 return cnt;
 482         ptr += size - 1; /* pointing at the very end */
 483         if (*ptr != '\n')
 484                 ; /* incomplete line */
 485         else
 486                 ptr--; /* skip the last LF */
 487         while (mf->ptr < ptr) {
 488                 char *prev_eol;
 489                 for (prev_eol = ptr; mf->ptr <= prev_eol; prev_eol--)
 490                         if (*prev_eol == '\n')
 491                                 break;
 492                 if (!ws_blank_line(prev_eol + 1, ptr - prev_eol, ws_rule))
 493                         break;
 494                 cnt++;
 495                 ptr = prev_eol - 1;
 496         }
 497         return cnt;
 498 }
 499
 500 static void check_blank_at_eof(mmfile_t *mf1, mmfile_t *mf2,
 501                                struct emit_callback *ecbdata)
 502 {
 503         int l1, l2, at;
 504         unsigned ws_rule = ecbdata->ws_rule;
 505         l1 = count_trailing_blank(mf1, ws_rule);
 506         l2 = count_trailing_blank(mf2, ws_rule);
 507         if (l2 <= l1) {
 508                 ecbdata->blank_at_eof_in_preimage = 0;
 509                 ecbdata->blank_at_eof_in_postimage = 0;
 510                 return;
 511         }
 512         at = count_lines(mf1->ptr, mf1->size);
 513         ecbdata->blank_at_eof_in_preimage = (at - l1) + 1;
 514
 515         at = count_lines(mf2->ptr, mf2->size);
 516         ecbdata->blank_at_eof_in_postimage = (at - l2) + 1;
 517 }
 518
 519 static void emit_line_0(struct diff_options *o, const char *set, const char *reset,
 520                         int first, const char *line, int len)
 521 {
 522         int has_trailing_newline, has_trailing_carriage_return;
 523         int nofirst;
 524         FILE *file = o->file;
 525
 526         fputs(diff_line_prefix(o), file);
 527
 528         if (len == 0) {
 529                 has_trailing_newline = (first == '\n');
 530                 has_trailing_carriage_return = (!has_trailing_newline &&
 531                                                 (first == '\r'));
 532                 nofirst = has_trailing_newline || has_trailing_carriage_return;
 533         } else {
 534                 has_trailing_newline = (len > 0 && line[len-1] == '\n');
 535                 if (has_trailing_newline)
 536                         len--;
 537                 has_trailing_carriage_return = (len > 0 && line[len-1] == '\r');
 538                 if (has_trailing_carriage_return)
 539                         len--;
 540                 nofirst = 0;
 541         }
 542
 543         if (len || !nofirst) {
 544                 fputs(set, file);
 545                 if (!nofirst)
 546                         fputc(first, file);
 547                 fwrite(line, len, 1, file);
 548                 fputs(reset, file);
 549         }
 550         if (has_trailing_carriage_return)
 551                 fputc('\r', file);
 552         if (has_trailing_newline)
 553                 fputc('\n', file);
 554 }
 555
 556 static void emit_line(struct diff_options *o, const char *set, const char *reset,
 557                       const char *line, int len)
 558 {
 559         emit_line_0(o, set, reset, line[0], line+1, len-1);
 560 }
 561
 562 static int new_blank_line_at_eof(struct emit_callback *ecbdata, const char *line, int len)
 563 {
 564         if (!((ecbdata->ws_rule & WS_BLANK_AT_EOF) &&
 565               ecbdata->blank_at_eof_in_preimage &&
 566               ecbdata->blank_at_eof_in_postimage &&
 567               ecbdata->blank_at_eof_in_preimage <= ecbdata->lno_in_preimage &&
 568               ecbdata->blank_at_eof_in_postimage <= ecbdata->lno_in_postimage))
 569                 return 0;
 570         return ws_blank_line(line, len, ecbdata->ws_rule);
 571 }
 572
 573 static void emit_line_checked(const char *reset,
 574                               struct emit_callback *ecbdata,
 575                               const char *line, int len,
 576                               enum color_diff color,
 577                               unsigned ws_error_highlight,
 578                               char sign)
 579 {
 580         const char *set = diff_get_color(ecbdata->color_diff, color);
 581         const char *ws = NULL;
 582
 583         if (ecbdata->opt->ws_error_highlight & ws_error_highlight) {
 584                 ws = diff_get_color(ecbdata->color_diff, DIFF_WHITESPACE);
 585                 if (!*ws)
 586                         ws = NULL;
 587         }
 588
 589         if (!ws)
 590                 emit_line_0(ecbdata->opt, set, reset, sign, line, len);
 591         else if (sign == '+' && new_blank_line_at_eof(ecbdata, line, len))
 592                 /* Blank line at EOF - paint '+' as well */
 593                 emit_line_0(ecbdata->opt, ws, reset, sign, line, len);
 594         else {
 595                 /* Emit just the prefix, then the rest. */
 596                 emit_line_0(ecbdata->opt, set, reset, sign, "", 0);
 597                 ws_check_emit(line, len, ecbdata->ws_rule,
 598                               ecbdata->opt->file, set, reset, ws);
 599         }
 600 }
 601
 602 static void emit_add_line(const char *reset,
 603                           struct emit_callback *ecbdata,
 604                           const char *line, int len)
 605 {
 606         emit_line_checked(reset, ecbdata, line, len,
 607                           DIFF_FILE_NEW, WSEH_NEW, '+');
 608 }
 609
 610 static void emit_del_line(const char *reset,
 611                           struct emit_callback *ecbdata,
 612                           const char *line, int len)
 613 {
 614         emit_line_checked(reset, ecbdata, line, len,
 615                           DIFF_FILE_OLD, WSEH_OLD, '-');
 616 }
 617
 618 static void emit_context_line(const char *reset,
 619                               struct emit_callback *ecbdata,
 620                               const char *line, int len)
 621 {
 622         emit_line_checked(reset, ecbdata, line, len,
 623                           DIFF_CONTEXT, WSEH_CONTEXT, ' ');
 624 }
 625
 626 static void emit_hunk_header(struct emit_callback *ecbdata,
 627                              const char *line, int len)
 628 {
 629         const char *context = diff_get_color(ecbdata->color_diff, DIFF_CONTEXT);
 630         const char *frag = diff_get_color(ecbdata->color_diff, DIFF_FRAGINFO);
 631         const char *func = diff_get_color(ecbdata->color_diff, DIFF_FUNCINFO);
 632         const char *reset = diff_get_color(ecbdata->color_diff, DIFF_RESET);
 633         static const char atat[2] = { '@', '@' };
 634         const char *cp, *ep;
 635         struct strbuf msgbuf = STRBUF_INIT;
 636         int org_len = len;
 637         int i = 1;
 638
 639         /*
 640          * As a hunk header must begin with "@@ -<old>, +<new> @@",
 641          * it always is at least 10 bytes long.
 642          */
 643         if (len < 10 ||
 644             memcmp(line, atat, 2) ||
 645             !(ep = memmem(line + 2, len - 2, atat, 2))) {
 646                 emit_line(ecbdata->opt, context, reset, line, len);
 647                 return;
 648         }
 649         ep += 2; /* skip over @@ */
 650
 651         /* The hunk header in fraginfo color */
 652         strbuf_addstr(&msgbuf, frag);
 653         strbuf_add(&msgbuf, line, ep - line);
 654         strbuf_addstr(&msgbuf, reset);
 655
 656         /*
 657          * trailing "\r\n"
 658          */
 659         for ( ; i < 3; i++)
 660                 if (line[len - i] == '\r' || line[len - i] == '\n')
 661                         len--;
 662
 663         /* blank before the func header */
 664         for (cp = ep; ep - line < len; ep++)
 665                 if (*ep != ' ' && *ep != '\t')
 666                         break;
 667         if (ep != cp) {
 668                 strbuf_addstr(&msgbuf, context);
 669                 strbuf_add(&msgbuf, cp, ep - cp);
 670                 strbuf_addstr(&msgbuf, reset);
 671         }
 672
 673         if (ep < line + len) {
 674                 strbuf_addstr(&msgbuf, func);
 675                 strbuf_add(&msgbuf, ep, line + len - ep);
 676                 strbuf_addstr(&msgbuf, reset);
 677         }
 678
 679         strbuf_add(&msgbuf, line + len, org_len - len);
 680         emit_line(ecbdata->opt, "", "", msgbuf.buf, msgbuf.len);
 681         strbuf_release(&msgbuf);
 682 }
 683
 684 static struct diff_tempfile *claim_diff_tempfile(void) {
 685         int i;
 686         for (i = 0; i < ARRAY_SIZE(diff_temp); i++)
 687                 if (!diff_temp[i].name)
 688                         return diff_temp + i;
 689         die("BUG: diff is failing to clean up its tempfiles");
 690 }
 691
 692 static void remove_tempfile(void)
 693 {
 694         int i;
 695         for (i = 0; i < ARRAY_SIZE(diff_temp); i++) {
 696                 if (is_tempfile_active(&diff_temp[i].tempfile))
 697                         delete_tempfile(&diff_temp[i].tempfile);
 698                 diff_temp[i].name = NULL;
 699         }
 700 }
 701
 702 static void print_line_count(FILE *file, int count)
 703 {
 704         switch (count) {
 705         case 0:
 706                 fprintf(file, "0,0");
 707                 break;
 708         case 1:
 709                 fprintf(file, "1");
 710                 break;
 711         default:
 712                 fprintf(file, "1,%d", count);
 713                 break;
 714         }
 715 }
 716
 717 static void emit_rewrite_lines(struct emit_callback *ecb,
 718                                int prefix, const char *data, int size)
 719 {
 720         const char *endp = NULL;
 721         static const char *nneof = " No newline at end of file\n";
 722         const char *reset = diff_get_color(ecb->color_diff, DIFF_RESET);
 723
 724         while (0 < size) {
 725                 int len;
 726
 727                 endp = memchr(data, '\n', size);
 728                 len = endp ? (endp - data + 1) : size;
 729                 if (prefix != '+') {
 730                         ecb->lno_in_preimage++;
 731                         emit_del_line(reset, ecb, data, len);
 732                 } else {
 733                         ecb->lno_in_postimage++;
 734                         emit_add_line(reset, ecb, data, len);
 735                 }
 736                 size -= len;
 737                 data += len;
 738         }
 739         if (!endp) {
 740                 const char *context = diff_get_color(ecb->color_diff,
 741                                                      DIFF_CONTEXT);
 742                 putc('\n', ecb->opt->file);
 743                 emit_line_0(ecb->opt, context, reset, '\\',
 744                             nneof, strlen(nneof));
 745         }
 746 }
 747
 748 static void emit_rewrite_diff(const char *name_a,
 749                               const char *name_b,
 750                               struct diff_filespec *one,
 751                               struct diff_filespec *two,
 752                               struct userdiff_driver *textconv_one,
 753                               struct userdiff_driver *textconv_two,
 754                               struct diff_options *o)
 755 {
 756         int lc_a, lc_b;
 757         const char *name_a_tab, *name_b_tab;
 758         const char *metainfo = diff_get_color(o->use_color, DIFF_METAINFO);
 759         const char *fraginfo = diff_get_color(o->use_color, DIFF_FRAGINFO);
 760         const char *reset = diff_get_color(o->use_color, DIFF_RESET);
 761         static struct strbuf a_name = STRBUF_INIT, b_name = STRBUF_INIT;
 762         const char *a_prefix, *b_prefix;
 763         char *data_one, *data_two;
 764         size_t size_one, size_two;
 765         struct emit_callback ecbdata;
 766         const char *line_prefix = diff_line_prefix(o);
 767
 768         if (diff_mnemonic_prefix && DIFF_OPT_TST(o, REVERSE_DIFF)) {
 769                 a_prefix = o->b_prefix;
 770                 b_prefix = o->a_prefix;
 771         } else {
 772                 a_prefix = o->a_prefix;
 773                 b_prefix = o->b_prefix;
 774         }
 775
 776         name_a += (*name_a == '/');
 777         name_b += (*name_b == '/');
 778         name_a_tab = strchr(name_a, ' ') ? "\t" : "";
 779         name_b_tab = strchr(name_b, ' ') ? "\t" : "";
 780
 781         strbuf_reset(&a_name);
 782         strbuf_reset(&b_name);
 783         quote_two_c_style(&a_name, a_prefix, name_a, 0);
 784         quote_two_c_style(&b_name, b_prefix, name_b, 0);
 785
 786         size_one = fill_textconv(textconv_one, one, &data_one);
 787         size_two = fill_textconv(textconv_two, two, &data_two);
 788
 789         memset(&ecbdata, 0, sizeof(ecbdata));
 790         ecbdata.color_diff = want_color(o->use_color);
 791         ecbdata.ws_rule = whitespace_rule(name_b);
 792         ecbdata.opt = o;
 793         if (ecbdata.ws_rule & WS_BLANK_AT_EOF) {
 794                 mmfile_t mf1, mf2;
 795                 mf1.ptr = (char *)data_one;
 796                 mf2.ptr = (char *)data_two;
 797                 mf1.size = size_one;
 798                 mf2.size = size_two;
 799                 check_blank_at_eof(&mf1, &mf2, &ecbdata);
 800         }
 801         ecbdata.lno_in_preimage = 1;
 802         ecbdata.lno_in_postimage = 1;
 803
 804         lc_a = count_lines(data_one, size_one);
 805         lc_b = count_lines(data_two, size_two);
 806         fprintf(o->file,
 807                 "%s%s--- %s%s%s\n%s%s+++ %s%s%s\n%s%s@@ -",
 808                 line_prefix, metainfo, a_name.buf, name_a_tab, reset,
 809                 line_prefix, metainfo, b_name.buf, name_b_tab, reset,
 810                 line_prefix, fraginfo);
 811         if (!o->irreversible_delete)
 812                 print_line_count(o->file, lc_a);
 813         else
 814                 fprintf(o->file, "?,?");
 815         fprintf(o->file, " +");
 816         print_line_count(o->file, lc_b);
 817         fprintf(o->file, " @@%s\n", reset);
 818         if (lc_a && !o->irreversible_delete)
 819                 emit_rewrite_lines(&ecbdata, '-', data_one, size_one);
 820         if (lc_b)
 821                 emit_rewrite_lines(&ecbdata, '+', data_two, size_two);
 822         if (textconv_one)
 823                 free((char *)data_one);
 824         if (textconv_two)
 825                 free((char *)data_two);
 826 }
 827
 828 struct diff_words_buffer {
 829         mmfile_t text;
 830         long alloc;
 831         struct diff_words_orig {
 832                 const char *begin, *end;
 833         } *orig;
 834         int orig_nr, orig_alloc;
 835 };
 836
 837 static void diff_words_append(char *line, unsigned long len,
 838                 struct diff_words_buffer *buffer)
 839 {
 840         ALLOC_GROW(buffer->text.ptr, buffer->text.size + len, buffer->alloc);
 841         line++;
 842         len--;
 843         memcpy(buffer->text.ptr + buffer->text.size, line, len);
 844         buffer->text.size += len;
 845         buffer->text.ptr[buffer->text.size] = '\0';
 846 }
 847
 848 struct diff_words_style_elem {
 849         const char *prefix;
 850         const char *suffix;
 851         const char *color; /* NULL; filled in by the setup code if
 852                             * color is enabled */
 853 };
 854
 855 struct diff_words_style {
 856         enum diff_words_type type;
 857         struct diff_words_style_elem new, old, ctx;
 858         const char *newline;
 859 };
 860
 861 static struct diff_words_style diff_words_styles[] = {
 862         { DIFF_WORDS_PORCELAIN, {"+", "\n"}, {"-", "\n"}, {" ", "\n"}, "~\n" },
 863         { DIFF_WORDS_PLAIN, {"{+", "+}"}, {"[-", "-]"}, {"", ""}, "\n" },
 864         { DIFF_WORDS_COLOR, {"", ""}, {"", ""}, {"", ""}, "\n" }
 865 };
 866
 867 struct diff_words_data {
 868         struct diff_words_buffer minus, plus;
 869         const char *current_plus;
 870         int last_minus;
 871         struct diff_options *opt;
 872         regex_t *word_regex;
 873         enum diff_words_type type;
 874         struct diff_words_style *style;
 875 };
 876
 877 static int fn_out_diff_words_write_helper(FILE *fp,
 878                                           struct diff_words_style_elem *st_el,
 879                                           const char *newline,
 880                                           size_t count, const char *buf,
 881                                           const char *line_prefix)
 882 {
 883         int print = 0;
 884
 885         while (count) {
 886                 char *p = memchr(buf, '\n', count);
 887                 if (print)
 888                         fputs(line_prefix, fp);
 889                 if (p != buf) {
 890                         if (st_el->color && fputs(st_el->color, fp) < 0)
 891                                 return -1;
 892                         if (fputs(st_el->prefix, fp) < 0 ||
 893                             fwrite(buf, p ? p - buf : count, 1, fp) != 1 ||
 894                             fputs(st_el->suffix, fp) < 0)
 895                                 return -1;
 896                         if (st_el->color && *st_el->color
 897                             && fputs(GIT_COLOR_RESET, fp) < 0)
 898                                 return -1;
 899                 }
 900                 if (!p)
 901                         return 0;
 902                 if (fputs(newline, fp) < 0)
 903                         return -1;
 904                 count -= p + 1 - buf;
 905                 buf = p + 1;
 906                 print = 1;
 907         }
 908         return 0;
 909 }
 910
 911 /*
 912  * '--color-words' algorithm can be described as:
 913  *
 914  *   1. collect a the minus/plus lines of a diff hunk, divided into
 915  *      minus-lines and plus-lines;
 916  *
 917  *   2. break both minus-lines and plus-lines into words and
 918  *      place them into two mmfile_t with one word for each line;
 919  *
 920  *   3. use xdiff to run diff on the two mmfile_t to get the words level diff;
 921  *
 922  * And for the common parts of the both file, we output the plus side text.
 923  * diff_words->current_plus is used to trace the current position of the plus file
 924  * which printed. diff_words->last_minus is used to trace the last minus word
 925  * printed.
 926  *
 927  * For '--graph' to work with '--color-words', we need to output the graph prefix
 928  * on each line of color words output. Generally, there are two conditions on
 929  * which we should output the prefix.
 930  *
 931  *   1. diff_words->last_minus == 0 &&
 932  *      diff_words->current_plus == diff_words->plus.text.ptr
 933  *
 934  *      that is: the plus text must start as a new line, and if there is no minus
 935  *      word printed, a graph prefix must be printed.
 936  *
 937  *   2. diff_words->current_plus > diff_words->plus.text.ptr &&
 938  *      *(diff_words->current_plus - 1) == '\n'
 939  *
 940  *      that is: a graph prefix must be printed following a '\n'
 941  */
 942 static int color_words_output_graph_prefix(struct diff_words_data *diff_words)
 943 {
 944         if ((diff_words->last_minus == 0 &&
 945                 diff_words->current_plus == diff_words->plus.text.ptr) ||
 946                 (diff_words->current_plus > diff_words->plus.text.ptr &&
 947                 *(diff_words->current_plus - 1) == '\n')) {
 948                 return 1;
 949         } else {
 950                 return 0;
 951         }
 952 }
 953
 954 static void fn_out_diff_words_aux(void *priv, char *line, unsigned long len)
 955 {
 956         struct diff_words_data *diff_words = priv;
 957         struct diff_words_style *style = diff_words->style;
 958         int minus_first, minus_len, plus_first, plus_len;
 959         const char *minus_begin, *minus_end, *plus_begin, *plus_end;
 960         struct diff_options *opt = diff_words->opt;
 961         const char *line_prefix;
 962
 963         if (line[0] != '@' || parse_hunk_header(line, len,
 964                         &minus_first, &minus_len, &plus_first, &plus_len))
 965                 return;
 966
 967         assert(opt);
 968         line_prefix = diff_line_prefix(opt);
 969
 970         /* POSIX requires that first be decremented by one if len == 0... */
 971         if (minus_len) {
 972                 minus_begin = diff_words->minus.orig[minus_first].begin;
 973                 minus_end =
 974                         diff_words->minus.orig[minus_first + minus_len - 1].end;
 975         } else
 976                 minus_begin = minus_end =
 977                         diff_words->minus.orig[minus_first].end;
 978
 979         if (plus_len) {
 980                 plus_begin = diff_words->plus.orig[plus_first].begin;
 981                 plus_end = diff_words->plus.orig[plus_first + plus_len - 1].end;
 982         } else
 983                 plus_begin = plus_end = diff_words->plus.orig[plus_first].end;
 984
 985         if (color_words_output_graph_prefix(diff_words)) {
 986                 fputs(line_prefix, diff_words->opt->file);
 987         }
 988         if (diff_words->current_plus != plus_begin) {
 989                 fn_out_diff_words_write_helper(diff_words->opt->file,
 990                                 &style->ctx, style->newline,
 991                                 plus_begin - diff_words->current_plus,
 992                                 diff_words->current_plus, line_prefix);
 993                 if (*(plus_begin - 1) == '\n')
 994                         fputs(line_prefix, diff_words->opt->file);
 995         }
 996         if (minus_begin != minus_end) {
 997                 fn_out_diff_words_write_helper(diff_words->opt->file,
 998                                 &style->old, style->newline,
 999                                 minus_end - minus_begin, minus_begin,
1000                                 line_prefix);
1001         }
1002         if (plus_begin != plus_end) {
1003                 fn_out_diff_words_write_helper(diff_words->opt->file,
1004                                 &style->new, style->newline,
1005                                 plus_end - plus_begin, plus_begin,
1006                                 line_prefix);
1007         }
1008
1009         diff_words->current_plus = plus_end;
1010         diff_words->last_minus = minus_first;
1011 }
1012
1013 /* This function starts looking at *begin, and returns 0 iff a word was found. */
1014 static int find_word_boundaries(mmfile_t *buffer, regex_t *word_regex,
1015                 int *begin, int *end)
1016 {
1017         if (word_regex && *begin < buffer->size) {
1018                 regmatch_t match[1];
1019                 if (!regexec_buf(word_regex, buffer->ptr + *begin,
1020                                  buffer->size - *begin, 1, match, 0)) {
1021                         char *p = memchr(buffer->ptr + *begin + match[0].rm_so,
1022                                         '\n', match[0].rm_eo - match[0].rm_so);
1023                         *end = p ? p - buffer->ptr : match[0].rm_eo + *begin;
1024                         *begin += match[0].rm_so;
1025                         return *begin >= *end;
1026                 }
1027                 return -1;
1028         }
1029
1030         /* find the next word */
1031         while (*begin < buffer->size && isspace(buffer->ptr[*begin]))
1032                 (*begin)++;
1033         if (*begin >= buffer->size)
1034                 return -1;
1035
1036         /* find the end of the word */
1037         *end = *begin + 1;
1038         while (*end < buffer->size && !isspace(buffer->ptr[*end]))
1039                 (*end)++;
1040
1041         return 0;
1042 }
1043
1044 /*
1045  * This function splits the words in buffer->text, stores the list with
1046  * newline separator into out, and saves the offsets of the original words
1047  * in buffer->orig.
1048  */
1049 static void diff_words_fill(struct diff_words_buffer *buffer, mmfile_t *out,
1050                 regex_t *word_regex)
1051 {
1052         int i, j;
1053         long alloc = 0;
1054
1055         out->size = 0;
1056         out->ptr = NULL;
1057
1058         /* fake an empty "0th" word */
1059         ALLOC_GROW(buffer->orig, 1, buffer->orig_alloc);
1060         buffer->orig[0].begin = buffer->orig[0].end = buffer->text.ptr;
1061         buffer->orig_nr = 1;
1062
1063         for (i = 0; i < buffer->text.size; i++) {
1064                 if (find_word_boundaries(&buffer->text, word_regex, &i, &j))
1065                         return;
1066
1067                 /* store original boundaries */
1068                 ALLOC_GROW(buffer->orig, buffer->orig_nr + 1,
1069                                 buffer->orig_alloc);
1070                 buffer->orig[buffer->orig_nr].begin = buffer->text.ptr + i;
1071                 buffer->orig[buffer->orig_nr].end = buffer->text.ptr + j;
1072                 buffer->orig_nr++;
1073
1074                 /* store one word */
1075                 ALLOC_GROW(out->ptr, out->size + j - i + 1, alloc);
1076                 memcpy(out->ptr + out->size, buffer->text.ptr + i, j - i);
1077                 out->ptr[out->size + j - i] = '\n';
1078                 out->size += j - i + 1;
1079
1080                 i = j - 1;
1081         }
1082 }
1083
1084 /* this executes the word diff on the accumulated buffers */
1085 static void diff_words_show(struct diff_words_data *diff_words)
1086 {
1087         xpparam_t xpp;
1088         xdemitconf_t xecfg;
1089         mmfile_t minus, plus;
1090         struct diff_words_style *style = diff_words->style;
1091
1092         struct diff_options *opt = diff_words->opt;
1093         const char *line_prefix;
1094
1095         assert(opt);
1096         line_prefix = diff_line_prefix(opt);
1097
1098         /* special case: only removal */
1099         if (!diff_words->plus.text.size) {
1100                 fputs(line_prefix, diff_words->opt->file);
1101                 fn_out_diff_words_write_helper(diff_words->opt->file,
1102                         &style->old, style->newline,
1103                         diff_words->minus.text.size,
1104                         diff_words->minus.text.ptr, line_prefix);
1105                 diff_words->minus.text.size = 0;
1106                 return;
1107         }
1108
1109         diff_words->current_plus = diff_words->plus.text.ptr;
1110         diff_words->last_minus = 0;
1111
1112         memset(&xpp, 0, sizeof(xpp));
1113         memset(&xecfg, 0, sizeof(xecfg));
1114         diff_words_fill(&diff_words->minus, &minus, diff_words->word_regex);
1115         diff_words_fill(&diff_words->plus, &plus, diff_words->word_regex);
1116         xpp.flags = 0;
1117         /* as only the hunk header will be parsed, we need a 0-context */
1118         xecfg.ctxlen = 0;
1119         if (xdi_diff_outf(&minus, &plus, fn_out_diff_words_aux, diff_words,
1120                           &xpp, &xecfg))
1121                 die("unable to generate word diff");
1122         free(minus.ptr);
1123         free(plus.ptr);
1124         if (diff_words->current_plus != diff_words->plus.text.ptr +
1125                         diff_words->plus.text.size) {
1126                 if (color_words_output_graph_prefix(diff_words))
1127                         fputs(line_prefix, diff_words->opt->file);
1128                 fn_out_diff_words_write_helper(diff_words->opt->file,
1129                         &style->ctx, style->newline,
1130                         diff_words->plus.text.ptr + diff_words->plus.text.size
1131                         - diff_words->current_plus, diff_words->current_plus,
1132                         line_prefix);
1133         }
1134         diff_words->minus.text.size = diff_words->plus.text.size = 0;
1135 }
1136
1137 /* In "color-words" mode, show word-diff of words accumulated in the buffer */
1138 static void diff_words_flush(struct emit_callback *ecbdata)
1139 {
1140         if (ecbdata->diff_words->minus.text.size ||
1141             ecbdata->diff_words->plus.text.size)
1142                 diff_words_show(ecbdata->diff_words);
1143 }
1144
1145 static void diff_filespec_load_driver(struct diff_filespec *one)
1146 {
1147         /* Use already-loaded driver */
1148         if (one->driver)
1149                 return;
1150
1151         if (S_ISREG(one->mode))
1152                 one->driver = userdiff_find_by_path(one->path);
1153
1154         /* Fallback to default settings */
1155         if (!one->driver)
1156                 one->driver = userdiff_find_by_name("default");
1157 }
1158
1159 static const char *userdiff_word_regex(struct diff_filespec *one)
1160 {
1161         diff_filespec_load_driver(one);
1162         return one->driver->word_regex;
1163 }
1164
1165 static void init_diff_words_data(struct emit_callback *ecbdata,
1166                                  struct diff_options *orig_opts,
1167                                  struct diff_filespec *one,
1168                                  struct diff_filespec *two)
1169 {
1170         int i;
1171         struct diff_options *o = xmalloc(sizeof(struct diff_options));
1172         memcpy(o, orig_opts, sizeof(struct diff_options));
1173
1174         ecbdata->diff_words =
1175                 xcalloc(1, sizeof(struct diff_words_data));
1176         ecbdata->diff_words->type = o->word_diff;
1177         ecbdata->diff_words->opt = o;
1178         if (!o->word_regex)
1179                 o->word_regex = userdiff_word_regex(one);
1180         if (!o->word_regex)
1181                 o->word_regex = userdiff_word_regex(two);
1182         if (!o->word_regex)
1183                 o->word_regex = diff_word_regex_cfg;
1184         if (o->word_regex) {
1185                 ecbdata->diff_words->word_regex = (regex_t *)
1186                         xmalloc(sizeof(regex_t));
1187                 if (regcomp(ecbdata->diff_words->word_regex,
1188                             o->word_regex,
1189                             REG_EXTENDED | REG_NEWLINE))
1190                         die ("Invalid regular expression: %s",
1191                              o->word_regex);
1192         }
1193         for (i = 0; i < ARRAY_SIZE(diff_words_styles); i++) {
1194                 if (o->word_diff == diff_words_styles[i].type) {
1195                         ecbdata->diff_words->style =
1196                                 &diff_words_styles[i];
1197                         break;
1198                 }
1199         }
1200         if (want_color(o->use_color)) {
1201                 struct diff_words_style *st = ecbdata->diff_words->style;
1202                 st->old.color = diff_get_color_opt(o, DIFF_FILE_OLD);
1203                 st->new.color = diff_get_color_opt(o, DIFF_FILE_NEW);
1204                 st->ctx.color = diff_get_color_opt(o, DIFF_CONTEXT);
1205         }
1206 }
1207
1208 static void free_diff_words_data(struct emit_callback *ecbdata)
1209 {
1210         if (ecbdata->diff_words) {
1211                 diff_words_flush(ecbdata);
1212                 free (ecbdata->diff_words->opt);
1213                 free (ecbdata->diff_words->minus.text.ptr);
1214                 free (ecbdata->diff_words->minus.orig);
1215                 free (ecbdata->diff_words->plus.text.ptr);
1216                 free (ecbdata->diff_words->plus.orig);
1217                 if (ecbdata->diff_words->word_regex) {
1218                         regfree(ecbdata->diff_words->word_regex);
1219                         free(ecbdata->diff_words->word_regex);
1220                 }
1221                 free(ecbdata->diff_words);
1222                 ecbdata->diff_words = NULL;
1223         }
1224 }
1225
1226 const char *diff_get_color(int diff_use_color, enum color_diff ix)
1227 {
1228         if (want_color(diff_use_color))
1229                 return diff_colors[ix];
1230         return "";
1231 }
1232
1233 const char *diff_line_prefix(struct diff_options *opt)
1234 {
1235         struct strbuf *msgbuf;
1236         if (!opt->output_prefix)
1237                 return "";
1238
1239         msgbuf = opt->output_prefix(opt, opt->output_prefix_data);
1240         return msgbuf->buf;
1241 }
1242
1243 static unsigned long sane_truncate_line(struct emit_callback *ecb, char *line, unsigned long len)
1244 {
1245         const char *cp;
1246         unsigned long allot;
1247         size_t l = len;
1248
1249         if (ecb->truncate)
1250                 return ecb->truncate(line, len);
1251         cp = line;
1252         allot = l;
1253         while (0 < l) {
1254                 (void) utf8_width(&cp, &l);
1255                 if (!cp)
1256                         break; /* truncated in the middle? */
1257         }
1258         return allot - l;
1259 }
1260
1261 static void find_lno(const char *line, struct emit_callback *ecbdata)
1262 {
1263         const char *p;
1264         ecbdata->lno_in_preimage = 0;
1265         ecbdata->lno_in_postimage = 0;
1266         p = strchr(line, '-');
1267         if (!p)
1268                 return; /* cannot happen */
1269         ecbdata->lno_in_preimage = strtol(p + 1, NULL, 10);
1270         p = strchr(p, '+');
1271         if (!p)
1272                 return; /* cannot happen */
1273         ecbdata->lno_in_postimage = strtol(p + 1, NULL, 10);
1274 }
1275
1276 static void fn_out_consume(void *priv, char *line, unsigned long len)
1277 {
1278         struct emit_callback *ecbdata = priv;
1279         const char *meta = diff_get_color(ecbdata->color_diff, DIFF_METAINFO);
1280         const char *context = diff_get_color(ecbdata->color_diff, DIFF_CONTEXT);
1281         const char *reset = diff_get_color(ecbdata->color_diff, DIFF_RESET);
1282         struct diff_options *o = ecbdata->opt;
1283         const char *line_prefix = diff_line_prefix(o);
1284
1285         o->found_changes = 1;
1286
1287         if (ecbdata->header) {
1288                 fprintf(o->file, "%s", ecbdata->header->buf);
1289                 strbuf_reset(ecbdata->header);
1290                 ecbdata->header = NULL;
1291         }
1292
1293         if (ecbdata->label_path[0]) {
1294                 const char *name_a_tab, *name_b_tab;
1295
1296                 name_a_tab = strchr(ecbdata->label_path[0], ' ') ? "\t" : "";
1297                 name_b_tab = strchr(ecbdata->label_path[1], ' ') ? "\t" : "";
1298
1299                 fprintf(o->file, "%s%s--- %s%s%s\n",
1300                         line_prefix, meta, ecbdata->label_path[0], reset, name_a_tab);
1301                 fprintf(o->file, "%s%s+++ %s%s%s\n",
1302                         line_prefix, meta, ecbdata->label_path[1], reset, name_b_tab);
1303                 ecbdata->label_path[0] = ecbdata->label_path[1] = NULL;
1304         }
1305
1306         if (diff_suppress_blank_empty
1307             && len == 2 && line[0] == ' ' && line[1] == '\n') {
1308                 line[0] = '\n';
1309                 len = 1;
1310         }
1311
1312         if (line[0] == '@') {
1313                 if (ecbdata->diff_words)
1314                         diff_words_flush(ecbdata);
1315                 len = sane_truncate_line(ecbdata, line, len);
1316                 find_lno(line, ecbdata);
1317                 emit_hunk_header(ecbdata, line, len);
1318                 if (line[len-1] != '\n')
1319                         putc('\n', o->file);
1320                 return;
1321         }
1322
1323         if (ecbdata->diff_words) {
1324                 if (line[0] == '-') {
1325                         diff_words_append(line, len,
1326                                           &ecbdata->diff_words->minus);
1327                         return;
1328                 } else if (line[0] == '+') {
1329                         diff_words_append(line, len,
1330                                           &ecbdata->diff_words->plus);
1331                         return;
1332                 } else if (starts_with(line, "\\ ")) {
1333                         /*
1334                          * Eat the "no newline at eof" marker as if we
1335                          * saw a "+" or "-" line with nothing on it,
1336                          * and return without diff_words_flush() to
1337                          * defer processing. If this is the end of
1338                          * preimage, more "+" lines may come after it.
1339                          */
1340                         return;
1341                 }
1342                 diff_words_flush(ecbdata);
1343                 if (ecbdata->diff_words->type == DIFF_WORDS_PORCELAIN) {
1344                         emit_line(o, context, reset, line, len);
1345                         fputs("~\n", o->file);
1346                 } else {
1347                         /*
1348                          * Skip the prefix character, if any.  With
1349                          * diff_suppress_blank_empty, there may be
1350                          * none.
1351                          */
1352                         if (line[0] != '\n') {
1353                               line++;
1354                               len--;
1355                         }
1356                         emit_line(o, context, reset, line, len);
1357                 }
1358                 return;
1359         }
1360
1361         switch (line[0]) {
1362         case '+':
1363                 ecbdata->lno_in_postimage++;
1364                 emit_add_line(reset, ecbdata, line + 1, len - 1);
1365                 break;
1366         case '-':
1367                 ecbdata->lno_in_preimage++;
1368                 emit_del_line(reset, ecbdata, line + 1, len - 1);
1369                 break;
1370         case ' ':
1371                 ecbdata->lno_in_postimage++;
1372                 ecbdata->lno_in_preimage++;
1373                 emit_context_line(reset, ecbdata, line + 1, len - 1);
1374                 break;
1375         default:
1376                 /* incomplete line at the end */
1377                 ecbdata->lno_in_preimage++;
1378                 emit_line(o, diff_get_color(ecbdata->color_diff, DIFF_CONTEXT),
1379                           reset, line, len);
1380                 break;
1381         }
1382 }
1383
1384 static char *pprint_rename(const char *a, const char *b)
1385 {
1386         const char *old = a;
1387         const char *new = b;
1388         struct strbuf name = STRBUF_INIT;
1389         int pfx_length, sfx_length;
1390         int pfx_adjust_for_slash;
1391         int len_a = strlen(a);
1392         int len_b = strlen(b);
1393         int a_midlen, b_midlen;
1394         int qlen_a = quote_c_style(a, NULL, NULL, 0);
1395         int qlen_b = quote_c_style(b, NULL, NULL, 0);
1396
1397         if (qlen_a || qlen_b) {
1398                 quote_c_style(a, &name, NULL, 0);
1399                 strbuf_addstr(&name, " => ");
1400                 quote_c_style(b, &name, NULL, 0);
1401                 return strbuf_detach(&name, NULL);
1402         }
1403
1404         /* Find common prefix */
1405         pfx_length = 0;
1406         while (*old && *new && *old == *new) {
1407                 if (*old == '/')
1408                         pfx_length = old - a + 1;
1409                 old++;
1410                 new++;
1411         }
1412
1413         /* Find common suffix */
1414         old = a + len_a;
1415         new = b + len_b;
1416         sfx_length = 0;
1417         /*
1418          * If there is a common prefix, it must end in a slash.  In
1419          * that case we let this loop run 1 into the prefix to see the
1420          * same slash.
1421          *
1422          * If there is no common prefix, we cannot do this as it would
1423          * underrun the input strings.
1424          */
1425         pfx_adjust_for_slash = (pfx_length ? 1 : 0);
1426         while (a + pfx_length - pfx_adjust_for_slash <= old &&
1427                b + pfx_length - pfx_adjust_for_slash <= new &&
1428                *old == *new) {
1429                 if (*old == '/')
1430                         sfx_length = len_a - (old - a);
1431                 old--;
1432                 new--;
1433         }
1434
1435         /*
1436          * pfx{mid-a => mid-b}sfx
1437          * {pfx-a => pfx-b}sfx
1438          * pfx{sfx-a => sfx-b}
1439          * name-a => name-b
1440          */
1441         a_midlen = len_a - pfx_length - sfx_length;
1442         b_midlen = len_b - pfx_length - sfx_length;
1443         if (a_midlen < 0)
1444                 a_midlen = 0;
1445         if (b_midlen < 0)
1446                 b_midlen = 0;
1447
1448         strbuf_grow(&name, pfx_length + a_midlen + b_midlen + sfx_length + 7);
1449         if (pfx_length + sfx_length) {
1450                 strbuf_add(&name, a, pfx_length);
1451                 strbuf_addch(&name, '{');
1452         }
1453         strbuf_add(&name, a + pfx_length, a_midlen);
1454         strbuf_addstr(&name, " => ");
1455         strbuf_add(&name, b + pfx_length, b_midlen);
1456         if (pfx_length + sfx_length) {
1457                 strbuf_addch(&name, '}');
1458                 strbuf_add(&name, a + len_a - sfx_length, sfx_length);
1459         }
1460         return strbuf_detach(&name, NULL);
1461 }
1462
1463 struct diffstat_t {
1464         int nr;
1465         int alloc;
1466         struct diffstat_file {
1467                 char *from_name;
1468                 char *name;
1469                 char *print_name;
1470                 unsigned is_unmerged:1;
1471                 unsigned is_binary:1;
1472                 unsigned is_renamed:1;
1473                 unsigned is_interesting:1;
1474                 uintmax_t added, deleted;
1475         } **files;
1476 };
1477
1478 static struct diffstat_file *diffstat_add(struct diffstat_t *diffstat,
1479                                           const char *name_a,
1480                                           const char *name_b)
1481 {
1482         struct diffstat_file *x;
1483         x = xcalloc(1, sizeof(*x));
1484         ALLOC_GROW(diffstat->files, diffstat->nr + 1, diffstat->alloc);
1485         diffstat->files[diffstat->nr++] = x;
1486         if (name_b) {
1487                 x->from_name = xstrdup(name_a);
1488                 x->name = xstrdup(name_b);
1489                 x->is_renamed = 1;
1490         }
1491         else {
1492                 x->from_name = NULL;
1493                 x->name = xstrdup(name_a);
1494         }
1495         return x;
1496 }
1497
1498 static void diffstat_consume(void *priv, char *line, unsigned long len)
1499 {
1500         struct diffstat_t *diffstat = priv;
1501         struct diffstat_file *x = diffstat->files[diffstat->nr - 1];
1502
1503         if (line[0] == '+')
1504                 x->added++;
1505         else if (line[0] == '-')
1506                 x->deleted++;
1507 }
1508
1509 const char mime_boundary_leader[] = "------------";
1510
1511 static int scale_linear(int it, int width, int max_change)
1512 {
1513         if (!it)
1514                 return 0;
1515         /*
1516          * make sure that at least one '-' or '+' is printed if
1517          * there is any change to this path. The easiest way is to
1518          * scale linearly as if the alloted width is one column shorter
1519          * than it is, and then add 1 to the result.
1520          */
1521         return 1 + (it * (width - 1) / max_change);
1522 }
1523
1524 static void show_name(FILE *file,
1525                       const char *prefix, const char *name, int len)
1526 {
1527         fprintf(file, " %s%-*s |", prefix, len, name);
1528 }
1529
1530 static void show_graph(FILE *file, char ch, int cnt, const char *set, const char *reset)
1531 {
1532         if (cnt <= 0)
1533                 return;
1534         fprintf(file, "%s", set);
1535         while (cnt--)
1536                 putc(ch, file);
1537         fprintf(file, "%s", reset);
1538 }
1539
1540 static void fill_print_name(struct diffstat_file *file)
1541 {
1542         char *pname;
1543
1544         if (file->print_name)
1545                 return;
1546
1547         if (!file->is_renamed) {
1548                 struct strbuf buf = STRBUF_INIT;
1549                 if (quote_c_style(file->name, &buf, NULL, 0)) {
1550                         pname = strbuf_detach(&buf, NULL);
1551                 } else {
1552                         pname = file->name;
1553                         strbuf_release(&buf);
1554                 }
1555         } else {
1556                 pname = pprint_rename(file->from_name, file->name);
1557         }
1558         file->print_name = pname;
1559 }
1560
1561 int print_stat_summary(FILE *fp, int files, int insertions, int deletions)
1562 {
1563         struct strbuf sb = STRBUF_INIT;
1564         int ret;
1565
1566         if (!files) {
1567                 assert(insertions == 0 && deletions == 0);
1568                 return fprintf(fp, "%s\n", " 0 files changed");
1569         }
1570
1571         strbuf_addf(&sb,
1572                     (files == 1) ? " %d file changed" : " %d files changed",
1573                     files);
1574
1575         /*
1576          * For binary diff, the caller may want to print "x files
1577          * changed" with insertions == 0 && deletions == 0.
1578          *
1579          * Not omitting "0 insertions(+), 0 deletions(-)" in this case
1580          * is probably less confusing (i.e skip over "2 files changed
1581          * but nothing about added/removed lines? Is this a bug in Git?").
1582          */
1583         if (insertions || deletions == 0) {
1584                 strbuf_addf(&sb,
1585                             (insertions == 1) ? ", %d insertion(+)" : ", %d insertions(+)",
1586                             insertions);
1587         }
1588
1589         if (deletions || insertions == 0) {
1590                 strbuf_addf(&sb,
1591                             (deletions == 1) ? ", %d deletion(-)" : ", %d deletions(-)",
1592                             deletions);
1593         }
1594         strbuf_addch(&sb, '\n');
1595         ret = fputs(sb.buf, fp);
1596         strbuf_release(&sb);
1597         return ret;
1598 }
1599
1600 static void show_stats(struct diffstat_t *data, struct diff_options *options)
1601 {
1602         int i, len, add, del, adds = 0, dels = 0;
1603         uintmax_t max_change = 0, max_len = 0;
1604         int total_files = data->nr, count;
1605         int width, name_width, graph_width, number_width = 0, bin_width = 0;
1606         const char *reset, *add_c, *del_c;
1607         const char *line_prefix = "";
1608         int extra_shown = 0;
1609
1610         if (data->nr == 0)
1611                 return;
1612
1613         line_prefix = diff_line_prefix(options);
1614         count = options->stat_count ? options->stat_count : data->nr;
1615
1616         reset = diff_get_color_opt(options, DIFF_RESET);
1617         add_c = diff_get_color_opt(options, DIFF_FILE_NEW);
1618         del_c = diff_get_color_opt(options, DIFF_FILE_OLD);
1619
1620         /*
1621          * Find the longest filename and max number of changes
1622          */
1623         for (i = 0; (i < count) && (i < data->nr); i++) {
1624                 struct diffstat_file *file = data->files[i];
1625                 uintmax_t change = file->added + file->deleted;
1626
1627                 if (!file->is_interesting && (change == 0)) {
1628                         count++; /* not shown == room for one more */
1629                         continue;
1630                 }
1631                 fill_print_name(file);
1632                 len = strlen(file->print_name);
1633                 if (max_len < len)
1634                         max_len = len;
1635
1636                 if (file->is_unmerged) {
1637                         /* "Unmerged" is 8 characters */
1638                         bin_width = bin_width < 8 ? 8 : bin_width;
1639                         continue;
1640                 }
1641                 if (file->is_binary) {
1642                         /* "Bin XXX -> YYY bytes" */
1643                         int w = 14 + decimal_width(file->added)
1644                                 + decimal_width(file->deleted);
1645                         bin_width = bin_width < w ? w : bin_width;
1646                         /* Display change counts aligned with "Bin" */
1647                         number_width = 3;
1648                         continue;
1649                 }
1650
1651                 if (max_change < change)
1652                         max_change = change;
1653         }
1654         count = i; /* where we can stop scanning in data->files[] */
1655
1656         /*
1657          * We have width = stat_width or term_columns() columns total.
1658          * We want a maximum of min(max_len, stat_name_width) for the name part.
1659          * We want a maximum of min(max_change, stat_graph_width) for the +- part.
1660          * We also need 1 for " " and 4 + decimal_width(max_change)
1661          * for " | NNNN " and one the empty column at the end, altogether
1662          * 6 + decimal_width(max_change).
1663          *
1664          * If there's not enough space, we will use the smaller of
1665          * stat_name_width (if set) and 5/8*width for the filename,
1666          * and the rest for constant elements + graph part, but no more
1667          * than stat_graph_width for the graph part.
1668          * (5/8 gives 50 for filename and 30 for the constant parts + graph
1669          * for the standard terminal size).
1670          *
1671          * In other words: stat_width limits the maximum width, and
1672          * stat_name_width fixes the maximum width of the filename,
1673          * and is also used to divide available columns if there
1674          * aren't enough.
1675          *
1676          * Binary files are displayed with "Bin XXX -> YYY bytes"
1677          * instead of the change count and graph. This part is treated
1678          * similarly to the graph part, except that it is not
1679          * "scaled". If total width is too small to accommodate the
1680          * guaranteed minimum width of the filename part and the
1681          * separators and this message, this message will "overflow"
1682          * making the line longer than the maximum width.
1683          */
1684
1685         if (options->stat_width == -1)
1686                 width = term_columns() - strlen(line_prefix);
1687         else
1688                 width = options->stat_width ? options->stat_width : 80;
1689         number_width = decimal_width(max_change) > number_width ?
1690                 decimal_width(max_change) : number_width;
1691
1692         if (options->stat_graph_width == -1)
1693                 options->stat_graph_width = diff_stat_graph_width;
1694
1695         /*
1696          * Guarantee 3/8*16==6 for the graph part
1697          * and 5/8*16==10 for the filename part
1698          */
1699         if (width < 16 + 6 + number_width)
1700                 width = 16 + 6 + number_width;
1701
1702         /*
1703          * First assign sizes that are wanted, ignoring available width.
1704          * strlen("Bin XXX -> YYY bytes") == bin_width, and the part
1705          * starting from "XXX" should fit in graph_width.
1706          */
1707         graph_width = max_change + 4 > bin_width ? max_change : bin_width - 4;
1708         if (options->stat_graph_width &&
1709             options->stat_graph_width < graph_width)
1710                 graph_width = options->stat_graph_width;
1711
1712         name_width = (options->stat_name_width > 0 &&
1713                       options->stat_name_width < max_len) ?
1714                 options->stat_name_width : max_len;
1715
1716         /*
1717          * Adjust adjustable widths not to exceed maximum width
1718          */
1719         if (name_width + number_width + 6 + graph_width > width) {
1720                 if (graph_width > width * 3/8 - number_width - 6) {
1721                         graph_width = width * 3/8 - number_width - 6;
1722                         if (graph_width < 6)
1723                                 graph_width = 6;
1724                 }
1725
1726                 if (options->stat_graph_width &&
1727                     graph_width > options->stat_graph_width)
1728                         graph_width = options->stat_graph_width;
1729                 if (name_width > width - number_width - 6 - graph_width)
1730                         name_width = width - number_width - 6 - graph_width;
1731                 else
1732                         graph_width = width - number_width - 6 - name_width;
1733         }
1734
1735         /*
1736          * From here name_width is the width of the name area,
1737          * and graph_width is the width of the graph area.
1738          * max_change is used to scale graph properly.
1739          */
1740         for (i = 0; i < count; i++) {
1741                 const char *prefix = "";
1742                 struct diffstat_file *file = data->files[i];
1743                 char *name = file->print_name;
1744                 uintmax_t added = file->added;
1745                 uintmax_t deleted = file->deleted;
1746                 int name_len;
1747
1748                 if (!file->is_interesting && (added + deleted == 0))
1749                         continue;
1750
1751                 /*
1752                  * "scale" the filename
1753                  */
1754                 len = name_width;
1755                 name_len = strlen(name);
1756                 if (name_width < name_len) {
1757                         char *slash;
1758                         prefix = "...";
1759                         len -= 3;
1760                         name += name_len - len;
1761                         slash = strchr(name, '/');
1762                         if (slash)
1763                                 name = slash;
1764                 }
1765
1766                 if (file->is_binary) {
1767                         fprintf(options->file, "%s", line_prefix);
1768                         show_name(options->file, prefix, name, len);
1769                         fprintf(options->file, " %*s", number_width, "Bin");
1770                         if (!added && !deleted) {
1771                                 putc('\n', options->file);
1772                                 continue;
1773                         }
1774                         fprintf(options->file, " %s%"PRIuMAX"%s",
1775                                 del_c, deleted, reset);
1776                         fprintf(options->file, " -> ");
1777                         fprintf(options->file, "%s%"PRIuMAX"%s",
1778                                 add_c, added, reset);
1779                         fprintf(options->file, " bytes");
1780                         fprintf(options->file, "\n");
1781                         continue;
1782                 }
1783                 else if (file->is_unmerged) {
1784                         fprintf(options->file, "%s", line_prefix);
1785                         show_name(options->file, prefix, name, len);
1786                         fprintf(options->file, " Unmerged\n");
1787                         continue;
1788                 }
1789
1790                 /*
1791                  * scale the add/delete
1792                  */
1793                 add = added;
1794                 del = deleted;
1795
1796                 if (graph_width <= max_change) {
1797                         int total = scale_linear(add + del, graph_width, max_change);
1798                         if (total < 2 && add && del)
1799                                 /* width >= 2 due to the sanity check */
1800                                 total = 2;
1801                         if (add < del) {
1802                                 add = scale_linear(add, graph_width, max_change);
1803                                 del = total - add;
1804                         } else {
1805                                 del = scale_linear(del, graph_width, max_change);
1806                                 add = total - del;
1807                         }
1808                 }
1809                 fprintf(options->file, "%s", line_prefix);
1810                 show_name(options->file, prefix, name, len);
1811                 fprintf(options->file, " %*"PRIuMAX"%s",
1812                         number_width, added + deleted,
1813                         added + deleted ? " " : "");
1814                 show_graph(options->file, '+', add, add_c, reset);
1815                 show_graph(options->file, '-', del, del_c, reset);
1816                 fprintf(options->file, "\n");
1817         }
1818
1819         for (i = 0; i < data->nr; i++) {
1820                 struct diffstat_file *file = data->files[i];
1821                 uintmax_t added = file->added;
1822                 uintmax_t deleted = file->deleted;
1823
1824                 if (file->is_unmerged ||
1825                     (!file->is_interesting && (added + deleted == 0))) {
1826                         total_files--;
1827                         continue;
1828                 }
1829
1830                 if (!file->is_binary) {
1831                         adds += added;
1832                         dels += deleted;
1833                 }
1834                 if (i < count)
1835                         continue;
1836                 if (!extra_shown)
1837                         fprintf(options->file, "%s ...\n", line_prefix);
1838                 extra_shown = 1;
1839         }
1840         fprintf(options->file, "%s", line_prefix);
1841         print_stat_summary(options->file, total_files, adds, dels);
1842 }
1843
1844 static void show_shortstats(struct diffstat_t *data, struct diff_options *options)
1845 {
1846         int i, adds = 0, dels = 0, total_files = data->nr;
1847
1848         if (data->nr == 0)
1849                 return;
1850
1851         for (i = 0; i < data->nr; i++) {
1852                 int added = data->files[i]->added;
1853                 int deleted= data->files[i]->deleted;
1854
1855                 if (data->files[i]->is_unmerged ||
1856                     (!data->files[i]->is_interesting && (added + deleted == 0))) {
1857                         total_files--;
1858                 } else if (!data->files[i]->is_binary) { /* don't count bytes */
1859                         adds += added;
1860                         dels += deleted;
1861                 }
1862         }
1863         fprintf(options->file, "%s", diff_line_prefix(options));
1864         print_stat_summary(options->file, total_files, adds, dels);
1865 }
1866
1867 static void show_numstat(struct diffstat_t *data, struct diff_options *options)
1868 {
1869         int i;
1870
1871         if (data->nr == 0)
1872                 return;
1873
1874         for (i = 0; i < data->nr; i++) {
1875                 struct diffstat_file *file = data->files[i];
1876
1877                 fprintf(options->file, "%s", diff_line_prefix(options));
1878
1879                 if (file->is_binary)
1880                         fprintf(options->file, "-\t-\t");
1881                 else
1882                         fprintf(options->file,
1883                                 "%"PRIuMAX"\t%"PRIuMAX"\t",
1884                                 file->added, file->deleted);
1885                 if (options->line_termination) {
1886                         fill_print_name(file);
1887                         if (!file->is_renamed)
1888                                 write_name_quoted(file->name, options->file,
1889                                                   options->line_termination);
1890                         else {
1891                                 fputs(file->print_name, options->file);
1892                                 putc(options->line_termination, options->file);
1893                         }
1894                 } else {
1895                         if (file->is_renamed) {
1896                                 putc('\0', options->file);
1897                                 write_name_quoted(file->from_name, options->file, '\0');
1898                         }
1899                         write_name_quoted(file->name, options->file, '\0');
1900                 }
1901         }
1902 }
1903
1904 struct dirstat_file {
1905         const char *name;
1906         unsigned long changed;
1907 };
1908
1909 struct dirstat_dir {
1910         struct dirstat_file *files;
1911         int alloc, nr, permille, cumulative;
1912 };
1913
1914 static long gather_dirstat(struct diff_options *opt, struct dirstat_dir *dir,
1915                 unsigned long changed, const char *base, int baselen)
1916 {
1917         unsigned long this_dir = 0;
1918         unsigned int sources = 0;
1919         const char *line_prefix = diff_line_prefix(opt);
1920
1921         while (dir->nr) {
1922                 struct dirstat_file *f = dir->files;
1923                 int namelen = strlen(f->name);
1924                 unsigned long this;
1925                 char *slash;
1926
1927                 if (namelen < baselen)
1928                         break;
1929                 if (memcmp(f->name, base, baselen))
1930                         break;
1931                 slash = strchr(f->name + baselen, '/');
1932                 if (slash) {
1933                         int newbaselen = slash + 1 - f->name;
1934                         this = gather_dirstat(opt, dir, changed, f->name, newbaselen);
1935                         sources++;
1936                 } else {
1937                         this = f->changed;
1938                         dir->files++;
1939                         dir->nr--;
1940                         sources += 2;
1941                 }
1942                 this_dir += this;
1943         }
1944
1945         /*
1946          * We don't report dirstat's for
1947          *  - the top level
1948          *  - or cases where everything came from a single directory
1949          *    under this directory (sources == 1).
1950          */
1951         if (baselen && sources != 1) {
1952                 if (this_dir) {
1953                         int permille = this_dir * 1000 / changed;
1954                         if (permille >= dir->permille) {
1955                                 fprintf(opt->file, "%s%4d.%01d%% %.*s\n", line_prefix,
1956                                         permille / 10, permille % 10, baselen, base);
1957                                 if (!dir->cumulative)
1958                                         return 0;
1959                         }
1960                 }
1961         }
1962         return this_dir;
1963 }
1964
1965 static int dirstat_compare(const void *_a, const void *_b)
1966 {
1967         const struct dirstat_file *a = _a;
1968         const struct dirstat_file *b = _b;
1969         return strcmp(a->name, b->name);
1970 }
1971
1972 static void show_dirstat(struct diff_options *options)
1973 {
1974         int i;
1975         unsigned long changed;
1976         struct dirstat_dir dir;
1977         struct diff_queue_struct *q = &diff_queued_diff;
1978
1979         dir.files = NULL;
1980         dir.alloc = 0;
1981         dir.nr = 0;
1982         dir.permille = options->dirstat_permille;
1983         dir.cumulative = DIFF_OPT_TST(options, DIRSTAT_CUMULATIVE);
1984
1985         changed = 0;
1986         for (i = 0; i < q->nr; i++) {
1987                 struct diff_filepair *p = q->queue[i];
1988                 const char *name;
1989                 unsigned long copied, added, damage;
1990                 int content_changed;
1991
1992                 name = p->two->path ? p->two->path : p->one->path;
1993
1994                 if (p->one->oid_valid && p->two->oid_valid)
1995                         content_changed = oidcmp(&p->one->oid, &p->two->oid);
1996                 else
1997                         content_changed = 1;
1998
1999                 if (!content_changed) {
2000                         /*
2001                          * The SHA1 has not changed, so pre-/post-content is
2002                          * identical. We can therefore skip looking at the
2003                          * file contents altogether.
2004                          */
2005                         damage = 0;
2006                         goto found_damage;
2007                 }
2008
2009                 if (DIFF_OPT_TST(options, DIRSTAT_BY_FILE)) {
2010                         /*
2011                          * In --dirstat-by-file mode, we don't really need to
2012                          * look at the actual file contents at all.
2013                          * The fact that the SHA1 changed is enough for us to
2014                          * add this file to the list of results
2015                          * (with each file contributing equal damage).
2016                          */
2017                         damage = 1;
2018                         goto found_damage;
2019                 }
2020
2021                 if (DIFF_FILE_VALID(p->one) && DIFF_FILE_VALID(p->two)) {
2022                         diff_populate_filespec(p->one, 0);
2023                         diff_populate_filespec(p->two, 0);
2024                         diffcore_count_changes(p->one, p->two, NULL, NULL,
2025                                                &copied, &added);
2026                         diff_free_filespec_data(p->one);
2027                         diff_free_filespec_data(p->two);
2028                 } else if (DIFF_FILE_VALID(p->one)) {
2029                         diff_populate_filespec(p->one, CHECK_SIZE_ONLY);
2030                         copied = added = 0;
2031                         diff_free_filespec_data(p->one);
2032                 } else if (DIFF_FILE_VALID(p->two)) {
2033                         diff_populate_filespec(p->two, CHECK_SIZE_ONLY);
2034                         copied = 0;
2035                         added = p->two->size;
2036                         diff_free_filespec_data(p->two);
2037                 } else
2038                         continue;
2039
2040                 /*
2041                  * Original minus copied is the removed material,
2042                  * added is the new material.  They are both damages
2043                  * made to the preimage.
2044                  * If the resulting damage is zero, we know that
2045                  * diffcore_count_changes() considers the two entries to
2046                  * be identical, but since content_changed is true, we
2047                  * know that there must have been _some_ kind of change,
2048                  * so we force all entries to have damage > 0.
2049                  */
2050                 damage = (p->one->size - copied) + added;
2051                 if (!damage)
2052                         damage = 1;
2053
2054 found_damage:
2055                 ALLOC_GROW(dir.files, dir.nr + 1, dir.alloc);
2056                 dir.files[dir.nr].name = name;
2057                 dir.files[dir.nr].changed = damage;
2058                 changed += damage;
2059                 dir.nr++;
2060         }
2061
2062         /* This can happen even with many files, if everything was renames */
2063         if (!changed)
2064                 return;
2065
2066         /* Show all directories with more than x% of the changes */
2067         QSORT(dir.files, dir.nr, dirstat_compare);
2068         gather_dirstat(options, &dir, changed, "", 0);
2069 }
2070
2071 static void show_dirstat_by_line(struct diffstat_t *data, struct diff_options *options)
2072 {
2073         int i;
2074         unsigned long changed;
2075         struct dirstat_dir dir;
2076
2077         if (data->nr == 0)
2078                 return;
2079
2080         dir.files = NULL;
2081         dir.alloc = 0;
2082         dir.nr = 0;
2083         dir.permille = options->dirstat_permille;
2084         dir.cumulative = DIFF_OPT_TST(options, DIRSTAT_CUMULATIVE);
2085
2086         changed = 0;
2087         for (i = 0; i < data->nr; i++) {
2088                 struct diffstat_file *file = data->files[i];
2089                 unsigned long damage = file->added + file->deleted;
2090                 if (file->is_binary)
2091                         /*
2092                          * binary files counts bytes, not lines. Must find some
2093                          * way to normalize binary bytes vs. textual lines.
2094                          * The following heuristic assumes that there are 64
2095                          * bytes per "line".
2096                          * This is stupid and ugly, but very cheap...
2097                          */
2098                         damage = (damage + 63) / 64;
2099                 ALLOC_GROW(dir.files, dir.nr + 1, dir.alloc);
2100                 dir.files[dir.nr].name = file->name;
2101                 dir.files[dir.nr].changed = damage;
2102                 changed += damage;
2103                 dir.nr++;
2104         }
2105
2106         /* This can happen even with many files, if everything was renames */
2107         if (!changed)
2108                 return;
2109
2110         /* Show all directories with more than x% of the changes */
2111         QSORT(dir.files, dir.nr, dirstat_compare);
2112         gather_dirstat(options, &dir, changed, "", 0);
2113 }
2114
2115 static void free_diffstat_info(struct diffstat_t *diffstat)
2116 {
2117         int i;
2118         for (i = 0; i < diffstat->nr; i++) {
2119                 struct diffstat_file *f = diffstat->files[i];
2120                 if (f->name != f->print_name)
2121                         free(f->print_name);
2122                 free(f->name);
2123                 free(f->from_name);
2124                 free(f);
2125         }
2126         free(diffstat->files);
2127 }
2128
2129 struct checkdiff_t {
2130         const char *filename;
2131         int lineno;
2132         int conflict_marker_size;
2133         struct diff_options *o;
2134         unsigned ws_rule;
2135         unsigned status;
2136 };
2137
2138 static int is_conflict_marker(const char *line, int marker_size, unsigned long len)
2139 {
2140         char firstchar;
2141         int cnt;
2142
2143         if (len < marker_size + 1)
2144                 return 0;
2145         firstchar = line[0];
2146         switch (firstchar) {
2147         case '=': case '>': case '<': case '|':
2148                 break;
2149         default:
2150                 return 0;
2151         }
2152         for (cnt = 1; cnt < marker_size; cnt++)
2153                 if (line[cnt] != firstchar)
2154                         return 0;
2155         /* line[1] thru line[marker_size-1] are same as firstchar */
2156         if (len < marker_size + 1 || !isspace(line[marker_size]))
2157                 return 0;
2158         return 1;
2159 }
2160
2161 static void checkdiff_consume(void *priv, char *line, unsigned long len)
2162 {
2163         struct checkdiff_t *data = priv;
2164         int marker_size = data->conflict_marker_size;
2165         const char *ws = diff_get_color(data->o->use_color, DIFF_WHITESPACE);
2166         const char *reset = diff_get_color(data->o->use_color, DIFF_RESET);
2167         const char *set = diff_get_color(data->o->use_color, DIFF_FILE_NEW);
2168         char *err;
2169         const char *line_prefix;
2170
2171         assert(data->o);
2172         line_prefix = diff_line_prefix(data->o);
2173
2174         if (line[0] == '+') {
2175                 unsigned bad;
2176                 data->lineno++;
2177                 if (is_conflict_marker(line + 1, marker_size, len - 1)) {
2178                         data->status |= 1;
2179                         fprintf(data->o->file,
2180                                 "%s%s:%d: leftover conflict marker\n",
2181                                 line_prefix, data->filename, data->lineno);
2182                 }
2183                 bad = ws_check(line + 1, len - 1, data->ws_rule);
2184                 if (!bad)
2185                         return;
2186                 data->status |= bad;
2187                 err = whitespace_error_string(bad);
2188                 fprintf(data->o->file, "%s%s:%d: %s.\n",
2189                         line_prefix, data->filename, data->lineno, err);
2190                 free(err);
2191                 emit_line(data->o, set, reset, line, 1);
2192                 ws_check_emit(line + 1, len - 1, data->ws_rule,
2193                               data->o->file, set, reset, ws);
2194         } else if (line[0] == ' ') {
2195                 data->lineno++;
2196         } else if (line[0] == '@') {
2197                 char *plus = strchr(line, '+');
2198                 if (plus)
2199                         data->lineno = strtol(plus, NULL, 10) - 1;
2200                 else
2201                         die("invalid diff");
2202         }
2203 }
2204
2205 static unsigned char *deflate_it(char *data,
2206                                  unsigned long size,
2207                                  unsigned long *result_size)
2208 {
2209         int bound;
2210         unsigned char *deflated;
2211         git_zstream stream;
2212
2213         git_deflate_init(&stream, zlib_compression_level);
2214         bound = git_deflate_bound(&stream, size);
2215         deflated = xmalloc(bound);
2216         stream.next_out = deflated;
2217         stream.avail_out = bound;
2218
2219         stream.next_in = (unsigned char *)data;
2220         stream.avail_in = size;
2221         while (git_deflate(&stream, Z_FINISH) == Z_OK)
2222                 ; /* nothing */
2223         git_deflate_end(&stream);
2224         *result_size = stream.total_out;
2225         return deflated;
2226 }
2227
2228 static void emit_binary_diff_body(FILE *file, mmfile_t *one, mmfile_t *two,
2229                                   const char *prefix)
2230 {
2231         void *cp;
2232         void *delta;
2233         void *deflated;
2234         void *data;
2235         unsigned long orig_size;
2236         unsigned long delta_size;
2237         unsigned long deflate_size;
2238         unsigned long data_size;
2239
2240         /* We could do deflated delta, or we could do just deflated two,
2241          * whichever is smaller.
2242          */
2243         delta = NULL;
2244         deflated = deflate_it(two->ptr, two->size, &deflate_size);
2245         if (one->size && two->size) {
2246                 delta = diff_delta(one->ptr, one->size,
2247                                    two->ptr, two->size,
2248                                    &delta_size, deflate_size);
2249                 if (delta) {
2250                         void *to_free = delta;
2251                         orig_size = delta_size;
2252                         delta = deflate_it(delta, delta_size, &delta_size);
2253                         free(to_free);
2254                 }
2255         }
2256
2257         if (delta && delta_size < deflate_size) {
2258                 fprintf(file, "%sdelta %lu\n", prefix, orig_size);
2259                 free(deflated);
2260                 data = delta;
2261                 data_size = delta_size;
2262         }
2263         else {
2264                 fprintf(file, "%sliteral %lu\n", prefix, two->size);
2265                 free(delta);
2266                 data = deflated;
2267                 data_size = deflate_size;
2268         }
2269
2270         /* emit data encoded in base85 */
2271         cp = data;
2272         while (data_size) {
2273                 int bytes = (52 < data_size) ? 52 : data_size;
2274                 char line[70];
2275                 data_size -= bytes;
2276                 if (bytes <= 26)
2277                         line[0] = bytes + 'A' - 1;
2278                 else
2279                         line[0] = bytes - 26 + 'a' - 1;
2280                 encode_85(line + 1, cp, bytes);
2281                 cp = (char *) cp + bytes;
2282                 fprintf(file, "%s", prefix);
2283                 fputs(line, file);
2284                 fputc('\n', file);
2285         }
2286         fprintf(file, "%s\n", prefix);
2287         free(data);
2288 }
2289
2290 static void emit_binary_diff(FILE *file, mmfile_t *one, mmfile_t *two,
2291                              const char *prefix)
2292 {
2293         fprintf(file, "%sGIT binary patch\n", prefix);
2294         emit_binary_diff_body(file, one, two, prefix);
2295         emit_binary_diff_body(file, two, one, prefix);
2296 }
2297
2298 int diff_filespec_is_binary(struct diff_filespec *one)
2299 {
2300         if (one->is_binary == -1) {
2301                 diff_filespec_load_driver(one);
2302                 if (one->driver->binary != -1)
2303                         one->is_binary = one->driver->binary;
2304                 else {
2305                         if (!one->data && DIFF_FILE_VALID(one))
2306                                 diff_populate_filespec(one, CHECK_BINARY);
2307                         if (one->is_binary == -1 && one->data)
2308                                 one->is_binary = buffer_is_binary(one->data,
2309                                                 one->size);
2310                         if (one->is_binary == -1)
2311                                 one->is_binary = 0;
2312                 }
2313         }
2314         return one->is_binary;
2315 }
2316
2317 static const struct userdiff_funcname *diff_funcname_pattern(struct diff_filespec *one)
2318 {
2319         diff_filespec_load_driver(one);
2320         return one->driver->funcname.pattern ? &one->driver->funcname : NULL;
2321 }
2322
2323 void diff_set_mnemonic_prefix(struct diff_options *options, const char *a, const char *b)
2324 {
2325         if (!options->a_prefix)
2326                 options->a_prefix = a;
2327         if (!options->b_prefix)
2328                 options->b_prefix = b;
2329 }
2330
2331 struct userdiff_driver *get_textconv(struct diff_filespec *one)
2332 {
2333         if (!DIFF_FILE_VALID(one))
2334                 return NULL;
2335
2336         diff_filespec_load_driver(one);
2337         return userdiff_get_textconv(one->driver);
2338 }
2339
2340 static void builtin_diff(const char *name_a,
2341                          const char *name_b,
2342                          struct diff_filespec *one,
2343                          struct diff_filespec *two,
2344                          const char *xfrm_msg,
2345                          int must_show_header,
2346                          struct diff_options *o,
2347                          int complete_rewrite)
2348 {
2349         mmfile_t mf1, mf2;
2350         const char *lbl[2];
2351         char *a_one, *b_two;
2352         const char *meta = diff_get_color_opt(o, DIFF_METAINFO);
2353         const char *reset = diff_get_color_opt(o, DIFF_RESET);
2354         const char *a_prefix, *b_prefix;
2355         struct userdiff_driver *textconv_one = NULL;
2356         struct userdiff_driver *textconv_two = NULL;
2357         struct strbuf header = STRBUF_INIT;
2358         const char *line_prefix = diff_line_prefix(o);
2359
2360         diff_set_mnemonic_prefix(o, "a/", "b/");
2361         if (DIFF_OPT_TST(o, REVERSE_DIFF)) {
2362                 a_prefix = o->b_prefix;
2363                 b_prefix = o->a_prefix;
2364         } else {
2365                 a_prefix = o->a_prefix;
2366                 b_prefix = o->b_prefix;
2367         }
2368
2369         if (o->submodule_format == DIFF_SUBMODULE_LOG &&
2370             (!one->mode || S_ISGITLINK(one->mode)) &&
2371             (!two->mode || S_ISGITLINK(two->mode))) {
2372                 const char *del = diff_get_color_opt(o, DIFF_FILE_OLD);
2373                 const char *add = diff_get_color_opt(o, DIFF_FILE_NEW);
2374                 show_submodule_summary(o->file, one->path ? one->path : two->path,
2375                                 line_prefix,
2376                                 &one->oid, &two->oid,
2377                                 two->dirty_submodule,
2378                                 meta, del, add, reset);
2379                 return;
2380         } else if (o->submodule_format == DIFF_SUBMODULE_INLINE_DIFF &&
2381                    (!one->mode || S_ISGITLINK(one->mode)) &&
2382                    (!two->mode || S_ISGITLINK(two->mode))) {
2383                 const char *del = diff_get_color_opt(o, DIFF_FILE_OLD);
2384                 const char *add = diff_get_color_opt(o, DIFF_FILE_NEW);
2385                 show_submodule_inline_diff(o->file, one->path ? one->path : two->path,
2386                                 line_prefix,
2387                                 &one->oid, &two->oid,
2388                                 two->dirty_submodule,
2389                                 meta, del, add, reset, o);
2390                 return;
2391         }
2392
2393         if (DIFF_OPT_TST(o, ALLOW_TEXTCONV)) {
2394                 textconv_one = get_textconv(one);
2395                 textconv_two = get_textconv(two);
2396         }
2397
2398         /* Never use a non-valid filename anywhere if at all possible */
2399         name_a = DIFF_FILE_VALID(one) ? name_a : name_b;
2400         name_b = DIFF_FILE_VALID(two) ? name_b : name_a;
2401
2402         a_one = quote_two(a_prefix, name_a + (*name_a == '/'));
2403         b_two = quote_two(b_prefix, name_b + (*name_b == '/'));
2404         lbl[0] = DIFF_FILE_VALID(one) ? a_one : "/dev/null";
2405         lbl[1] = DIFF_FILE_VALID(two) ? b_two : "/dev/null";
2406         strbuf_addf(&header, "%s%sdiff --git %s %s%s\n", line_prefix, meta, a_one, b_two, reset);
2407         if (lbl[0][0] == '/') {
2408                 /* /dev/null */
2409                 strbuf_addf(&header, "%s%snew file mode %06o%s\n", line_prefix, meta, two->mode, reset);
2410                 if (xfrm_msg)
2411                         strbuf_addstr(&header, xfrm_msg);
2412                 must_show_header = 1;
2413         }
2414         else if (lbl[1][0] == '/') {
2415                 strbuf_addf(&header, "%s%sdeleted file mode %06o%s\n", line_prefix, meta, one->mode, reset);
2416                 if (xfrm_msg)
2417                         strbuf_addstr(&header, xfrm_msg);
2418                 must_show_header = 1;
2419         }
2420         else {
2421                 if (one->mode != two->mode) {
2422                         strbuf_addf(&header, "%s%sold mode %06o%s\n", line_prefix, meta, one->mode, reset);
2423                         strbuf_addf(&header, "%s%snew mode %06o%s\n", line_prefix, meta, two->mode, reset);
2424                         must_show_header = 1;
2425                 }
2426                 if (xfrm_msg)
2427                         strbuf_addstr(&header, xfrm_msg);
2428
2429                 /*
2430                  * we do not run diff between different kind
2431                  * of objects.
2432                  */
2433                 if ((one->mode ^ two->mode) & S_IFMT)
2434                         goto free_ab_and_return;
2435                 if (complete_rewrite &&
2436                     (textconv_one || !diff_filespec_is_binary(one)) &&
2437                     (textconv_two || !diff_filespec_is_binary(two))) {
2438                         fprintf(o->file, "%s", header.buf);
2439                         strbuf_reset(&header);
2440                         emit_rewrite_diff(name_a, name_b, one, two,
2441                                                 textconv_one, textconv_two, o);
2442                         o->found_changes = 1;
2443                         goto free_ab_and_return;
2444                 }
2445         }
2446
2447         if (o->irreversible_delete && lbl[1][0] == '/') {
2448                 fprintf(o->file, "%s", header.buf);
2449                 strbuf_reset(&header);
2450                 goto free_ab_and_return;
2451         } else if (!DIFF_OPT_TST(o, TEXT) &&
2452             ( (!textconv_one && diff_filespec_is_binary(one)) ||
2453               (!textconv_two && diff_filespec_is_binary(two)) )) {
2454                 if (!one->data && !two->data &&
2455                     S_ISREG(one->mode) && S_ISREG(two->mode) &&
2456                     !DIFF_OPT_TST(o, BINARY)) {
2457                         if (!oidcmp(&one->oid, &two->oid)) {
2458                                 if (must_show_header)
2459                                         fprintf(o->file, "%s", header.buf);
2460                                 goto free_ab_and_return;
2461                         }
2462                         fprintf(o->file, "%s", header.buf);
2463                         fprintf(o->file, "%sBinary files %s and %s differ\n",
2464                                 line_prefix, lbl[0], lbl[1]);
2465                         goto free_ab_and_return;
2466                 }
2467                 if (fill_mmfile(&mf1, one) < 0 || fill_mmfile(&mf2, two) < 0)
2468                         die("unable to read files to diff");
2469                 /* Quite common confusing case */
2470                 if (mf1.size == mf2.size &&
2471                     !memcmp(mf1.ptr, mf2.ptr, mf1.size)) {
2472                         if (must_show_header)
2473                                 fprintf(o->file, "%s", header.buf);
2474                         goto free_ab_and_return;
2475                 }
2476                 fprintf(o->file, "%s", header.buf);
2477                 strbuf_reset(&header);
2478                 if (DIFF_OPT_TST(o, BINARY))
2479                         emit_binary_diff(o->file, &mf1, &mf2, line_prefix);
2480                 else
2481                         fprintf(o->file, "%sBinary files %s and %s differ\n",
2482                                 line_prefix, lbl[0], lbl[1]);
2483                 o->found_changes = 1;
2484         } else {
2485                 /* Crazy xdl interfaces.. */
2486                 const char *diffopts = getenv("GIT_DIFF_OPTS");
2487                 const char *v;
2488                 xpparam_t xpp;
2489                 xdemitconf_t xecfg;
2490                 struct emit_callback ecbdata;
2491                 const struct userdiff_funcname *pe;
2492
2493                 if (must_show_header) {
2494                         fprintf(o->file, "%s", header.buf);
2495                         strbuf_reset(&header);
2496                 }
2497
2498                 mf1.size = fill_textconv(textconv_one, one, &mf1.ptr);
2499                 mf2.size = fill_textconv(textconv_two, two, &mf2.ptr);
2500
2501                 pe = diff_funcname_pattern(one);
2502                 if (!pe)
2503                         pe = diff_funcname_pattern(two);
2504
2505                 memset(&xpp, 0, sizeof(xpp));
2506                 memset(&xecfg, 0, sizeof(xecfg));
2507                 memset(&ecbdata, 0, sizeof(ecbdata));
2508                 ecbdata.label_path = lbl;
2509                 ecbdata.color_diff = want_color(o->use_color);
2510                 ecbdata.ws_rule = whitespace_rule(name_b);
2511                 if (ecbdata.ws_rule & WS_BLANK_AT_EOF)
2512                         check_blank_at_eof(&mf1, &mf2, &ecbdata);
2513                 ecbdata.opt = o;
2514                 ecbdata.header = header.len ? &header : NULL;
2515                 xpp.flags = o->xdl_opts;
2516                 xecfg.ctxlen = o->context;
2517                 xecfg.interhunkctxlen = o->interhunkcontext;
2518                 xecfg.flags = XDL_EMIT_FUNCNAMES;
2519                 if (DIFF_OPT_TST(o, FUNCCONTEXT))
2520                         xecfg.flags |= XDL_EMIT_FUNCCONTEXT;
2521                 if (pe)
2522                         xdiff_set_find_func(&xecfg, pe->pattern, pe->cflags);
2523                 if (!diffopts)
2524                         ;
2525                 else if (skip_prefix(diffopts, "--unified=", &v))
2526                         xecfg.ctxlen = strtoul(v, NULL, 10);
2527                 else if (skip_prefix(diffopts, "-u", &v))
2528                         xecfg.ctxlen = strtoul(v, NULL, 10);
2529                 if (o->word_diff)
2530                         init_diff_words_data(&ecbdata, o, one, two);
2531                 if (xdi_diff_outf(&mf1, &mf2, fn_out_consume, &ecbdata,
2532                                   &xpp, &xecfg))
2533                         die("unable to generate diff for %s", one->path);
2534                 if (o->word_diff)
2535                         free_diff_words_data(&ecbdata);
2536                 if (textconv_one)
2537                         free(mf1.ptr);
2538                 if (textconv_two)
2539                         free(mf2.ptr);
2540                 xdiff_clear_find_func(&xecfg);
2541         }
2542
2543  free_ab_and_return:
2544         strbuf_release(&header);
2545         diff_free_filespec_data(one);
2546         diff_free_filespec_data(two);
2547         free(a_one);
2548         free(b_two);
2549         return;
2550 }
2551
2552 static void builtin_diffstat(const char *name_a, const char *name_b,
2553                              struct diff_filespec *one,
2554                              struct diff_filespec *two,
2555                              struct diffstat_t *diffstat,
2556                              struct diff_options *o,
2557                              struct diff_filepair *p)
2558 {
2559         mmfile_t mf1, mf2;
2560         struct diffstat_file *data;
2561         int same_contents;
2562         int complete_rewrite = 0;
2563
2564         if (!DIFF_PAIR_UNMERGED(p)) {
2565                 if (p->status == DIFF_STATUS_MODIFIED && p->score)
2566                         complete_rewrite = 1;
2567         }
2568
2569         data = diffstat_add(diffstat, name_a, name_b);
2570         data->is_interesting = p->status != DIFF_STATUS_UNKNOWN;
2571
2572         if (!one || !two) {
2573                 data->is_unmerged = 1;
2574                 return;
2575         }
2576
2577         same_contents = !oidcmp(&one->oid, &two->oid);
2578
2579         if (diff_filespec_is_binary(one) || diff_filespec_is_binary(two)) {
2580                 data->is_binary = 1;
2581                 if (same_contents) {
2582                         data->added = 0;
2583                         data->deleted = 0;
2584                 } else {
2585                         data->added = diff_filespec_size(two);
2586                         data->deleted = diff_filespec_size(one);
2587                 }
2588         }
2589
2590         else if (complete_rewrite) {
2591                 diff_populate_filespec(one, 0);
2592                 diff_populate_filespec(two, 0);
2593                 data->deleted = count_lines(one->data, one->size);
2594                 data->added = count_lines(two->data, two->size);
2595         }
2596
2597         else if (!same_contents) {
2598                 /* Crazy xdl interfaces.. */
2599                 xpparam_t xpp;
2600                 xdemitconf_t xecfg;
2601
2602                 if (fill_mmfile(&mf1, one) < 0 || fill_mmfile(&mf2, two) < 0)
2603                         die("unable to read files to diff");
2604
2605                 memset(&xpp, 0, sizeof(xpp));
2606                 memset(&xecfg, 0, sizeof(xecfg));
2607                 xpp.flags = o->xdl_opts;
2608                 xecfg.ctxlen = o->context;
2609                 xecfg.interhunkctxlen = o->interhunkcontext;
2610                 if (xdi_diff_outf(&mf1, &mf2, diffstat_consume, diffstat,
2611                                   &xpp, &xecfg))
2612                         die("unable to generate diffstat for %s", one->path);
2613         }
2614
2615         diff_free_filespec_data(one);
2616         diff_free_filespec_data(two);
2617 }
2618
2619 static void builtin_checkdiff(const char *name_a, const char *name_b,
2620                               const char *attr_path,
2621                               struct diff_filespec *one,
2622                               struct diff_filespec *two,
2623                               struct diff_options *o)
2624 {
2625         mmfile_t mf1, mf2;
2626         struct checkdiff_t data;
2627
2628         if (!two)
2629                 return;
2630
2631         memset(&data, 0, sizeof(data));
2632         data.filename = name_b ? name_b : name_a;
2633         data.lineno = 0;
2634         data.o = o;
2635         data.ws_rule = whitespace_rule(attr_path);
2636         data.conflict_marker_size = ll_merge_marker_size(attr_path);
2637
2638         if (fill_mmfile(&mf1, one) < 0 || fill_mmfile(&mf2, two) < 0)
2639                 die("unable to read files to diff");
2640
2641         /*
2642          * All the other codepaths check both sides, but not checking
2643          * the "old" side here is deliberate.  We are checking the newly
2644          * introduced changes, and as long as the "new" side is text, we
2645          * can and should check what it introduces.
2646          */
2647         if (diff_filespec_is_binary(two))
2648                 goto free_and_return;
2649         else {
2650                 /* Crazy xdl interfaces.. */
2651                 xpparam_t xpp;
2652                 xdemitconf_t xecfg;
2653
2654                 memset(&xpp, 0, sizeof(xpp));
2655                 memset(&xecfg, 0, sizeof(xecfg));
2656                 xecfg.ctxlen = 1; /* at least one context line */
2657                 xpp.flags = 0;
2658                 if (xdi_diff_outf(&mf1, &mf2, checkdiff_consume, &data,
2659                                   &xpp, &xecfg))
2660                         die("unable to generate checkdiff for %s", one->path);
2661
2662                 if (data.ws_rule & WS_BLANK_AT_EOF) {
2663                         struct emit_callback ecbdata;
2664                         int blank_at_eof;
2665
2666                         ecbdata.ws_rule = data.ws_rule;
2667                         check_blank_at_eof(&mf1, &mf2, &ecbdata);
2668                         blank_at_eof = ecbdata.blank_at_eof_in_postimage;
2669
2670                         if (blank_at_eof) {
2671                                 static char *err;
2672                                 if (!err)
2673                                         err = whitespace_error_string(WS_BLANK_AT_EOF);
2674                                 fprintf(o->file, "%s:%d: %s.\n",
2675                                         data.filename, blank_at_eof, err);
2676                                 data.status = 1; /* report errors */
2677                         }
2678                 }
2679         }
2680  free_and_return:
2681         diff_free_filespec_data(one);
2682         diff_free_filespec_data(two);
2683         if (data.status)
2684                 DIFF_OPT_SET(o, CHECK_FAILED);
2685 }
2686
2687 struct diff_filespec *alloc_filespec(const char *path)
2688 {
2689         struct diff_filespec *spec;
2690
2691         FLEXPTR_ALLOC_STR(spec, path, path);
2692         spec->count = 1;
2693         spec->is_binary = -1;
2694         return spec;
2695 }
2696
2697 void free_filespec(struct diff_filespec *spec)
2698 {
2699         if (!--spec->count) {
2700                 diff_free_filespec_data(spec);
2701                 free(spec);
2702         }
2703 }
2704
2705 void fill_filespec(struct diff_filespec *spec, const unsigned char *sha1,
2706                    int sha1_valid, unsigned short mode)
2707 {
2708         if (mode) {
2709                 spec->mode = canon_mode(mode);
2710                 hashcpy(spec->oid.hash, sha1);
2711                 spec->oid_valid = sha1_valid;
2712         }
2713 }
2714
2715 /*
2716  * Given a name and sha1 pair, if the index tells us the file in
2717  * the work tree has that object contents, return true, so that
2718  * prepare_temp_file() does not have to inflate and extract.
2719  */
2720 static int reuse_worktree_file(const char *name, const unsigned char *sha1, int want_file)
2721 {
2722         const struct cache_entry *ce;
2723         struct stat st;
2724         int pos, len;
2725
2726         /*
2727          * We do not read the cache ourselves here, because the
2728          * benchmark with my previous version that always reads cache
2729          * shows that it makes things worse for diff-tree comparing
2730          * two linux-2.6 kernel trees in an already checked out work
2731          * tree.  This is because most diff-tree comparisons deal with
2732          * only a small number of files, while reading the cache is
2733          * expensive for a large project, and its cost outweighs the
2734          * savings we get by not inflating the object to a temporary
2735          * file.  Practically, this code only helps when we are used
2736          * by diff-cache --cached, which does read the cache before
2737          * calling us.
2738          */
2739         if (!active_cache)
2740                 return 0;
2741
2742         /* We want to avoid the working directory if our caller
2743          * doesn't need the data in a normal file, this system
2744          * is rather slow with its stat/open/mmap/close syscalls,
2745          * and the object is contained in a pack file.  The pack
2746          * is probably already open and will be faster to obtain
2747          * the data through than the working directory.  Loose
2748          * objects however would tend to be slower as they need
2749          * to be individually opened and inflated.
2750          */
2751         if (!FAST_WORKING_DIRECTORY && !want_file && has_sha1_pack(sha1))
2752                 return 0;
2753
2754         /*
2755          * Similarly, if we'd have to convert the file contents anyway, that
2756          * makes the optimization not worthwhile.
2757          */
2758         if (!want_file && would_convert_to_git(name))
2759                 return 0;
2760
2761         len = strlen(name);
2762         pos = cache_name_pos(name, len);
2763         if (pos < 0)
2764                 return 0;
2765         ce = active_cache[pos];
2766
2767         /*
2768          * This is not the sha1 we are looking for, or
2769          * unreusable because it is not a regular file.
2770          */
2771         if (hashcmp(sha1, ce->oid.hash) || !S_ISREG(ce->ce_mode))
2772                 return 0;
2773
2774         /*
2775          * If ce is marked as "assume unchanged", there is no
2776          * guarantee that work tree matches what we are looking for.
2777          */
2778         if ((ce->ce_flags & CE_VALID) || ce_skip_worktree(ce))
2779                 return 0;
2780
2781         /*
2782          * If ce matches the file in the work tree, we can reuse it.
2783          */
2784         if (ce_uptodate(ce) ||
2785             (!lstat(name, &st) && !ce_match_stat(ce, &st, 0)))
2786                 return 1;
2787
2788         return 0;
2789 }
2790
2791 static int diff_populate_gitlink(struct diff_filespec *s, int size_only)
2792 {
2793         struct strbuf buf = STRBUF_INIT;
2794         char *dirty = "";
2795
2796         /* Are we looking at the work tree? */
2797         if (s->dirty_submodule)
2798                 dirty = "-dirty";
2799
2800         strbuf_addf(&buf, "Subproject commit %s%s\n",
2801                     oid_to_hex(&s->oid), dirty);
2802         s->size = buf.len;
2803         if (size_only) {
2804                 s->data = NULL;
2805                 strbuf_release(&buf);
2806         } else {
2807                 s->data = strbuf_detach(&buf, NULL);
2808                 s->should_free = 1;
2809         }
2810         return 0;
2811 }
2812
2813 /*
2814  * While doing rename detection and pickaxe operation, we may need to
2815  * grab the data for the blob (or file) for our own in-core comparison.
2816  * diff_filespec has data and size fields for this purpose.
2817  */
2818 int diff_populate_filespec(struct diff_filespec *s, unsigned int flags)
2819 {
2820         int size_only = flags & CHECK_SIZE_ONLY;
2821         int err = 0;
2822         /*
2823          * demote FAIL to WARN to allow inspecting the situation
2824          * instead of refusing.
2825          */
2826         enum safe_crlf crlf_warn = (safe_crlf == SAFE_CRLF_FAIL
2827                                     ? SAFE_CRLF_WARN
2828                                     : safe_crlf);
2829
2830         if (!DIFF_FILE_VALID(s))
2831                 die("internal error: asking to populate invalid file.");
2832         if (S_ISDIR(s->mode))
2833                 return -1;
2834
2835         if (s->data)
2836                 return 0;
2837
2838         if (size_only && 0 < s->size)
2839                 return 0;
2840
2841         if (S_ISGITLINK(s->mode))
2842                 return diff_populate_gitlink(s, size_only);
2843
2844         if (!s->oid_valid ||
2845             reuse_worktree_file(s->path, s->oid.hash, 0)) {
2846                 struct strbuf buf = STRBUF_INIT;
2847                 struct stat st;
2848                 int fd;
2849
2850                 if (lstat(s->path, &st) < 0) {
2851                         if (errno == ENOENT) {
2852                         err_empty:
2853                                 err = -1;
2854                         empty:
2855                                 s->data = (char *)"";
2856                                 s->size = 0;
2857                                 return err;
2858                         }
2859                 }
2860                 s->size = xsize_t(st.st_size);
2861                 if (!s->size)
2862                         goto empty;
2863                 if (S_ISLNK(st.st_mode)) {
2864                         struct strbuf sb = STRBUF_INIT;
2865
2866                         if (strbuf_readlink(&sb, s->path, s->size))
2867                                 goto err_empty;
2868                         s->size = sb.len;
2869                         s->data = strbuf_detach(&sb, NULL);
2870                         s->should_free = 1;
2871                         return 0;
2872                 }
2873                 if (size_only)
2874                         return 0;
2875                 if ((flags & CHECK_BINARY) &&
2876                     s->size > big_file_threshold && s->is_binary == -1) {
2877                         s->is_binary = 1;
2878                         return 0;
2879                 }
2880                 fd = open(s->path, O_RDONLY);
2881                 if (fd < 0)
2882                         goto err_empty;
2883                 s->data = xmmap(NULL, s->size, PROT_READ, MAP_PRIVATE, fd, 0);
2884                 close(fd);
2885                 s->should_munmap = 1;
2886
2887                 /*
2888                  * Convert from working tree format to canonical git format
2889                  */
2890                 if (convert_to_git(s->path, s->data, s->size, &buf, crlf_warn)) {
2891                         size_t size = 0;
2892                         munmap(s->data, s->size);
2893                         s->should_munmap = 0;
2894                         s->data = strbuf_detach(&buf, &size);
2895                         s->size = size;
2896                         s->should_free = 1;
2897                 }
2898         }
2899         else {
2900                 enum object_type type;
2901                 if (size_only || (flags & CHECK_BINARY)) {
2902                         type = sha1_object_info(s->oid.hash, &s->size);
2903                         if (type < 0)
2904                                 die("unable to read %s",
2905                                     oid_to_hex(&s->oid));
2906                         if (size_only)
2907                                 return 0;
2908                         if (s->size > big_file_threshold && s->is_binary == -1) {
2909                                 s->is_binary = 1;
2910                                 return 0;
2911                         }
2912                 }
2913                 s->data = read_sha1_file(s->oid.hash, &type, &s->size);
2914                 if (!s->data)
2915                         die("unable to read %s", oid_to_hex(&s->oid));
2916                 s->should_free = 1;
2917         }
2918         return 0;
2919 }
2920
2921 void diff_free_filespec_blob(struct diff_filespec *s)
2922 {
2923         if (s->should_free)
2924                 free(s->data);
2925         else if (s->should_munmap)
2926                 munmap(s->data, s->size);
2927
2928         if (s->should_free || s->should_munmap) {
2929                 s->should_free = s->should_munmap = 0;
2930                 s->data = NULL;
2931         }
2932 }
2933
2934 void diff_free_filespec_data(struct diff_filespec *s)
2935 {
2936         diff_free_filespec_blob(s);
2937         free(s->cnt_data);
2938         s->cnt_data = NULL;
2939 }
2940
2941 static void prep_temp_blob(const char *path, struct diff_tempfile *temp,
2942                            void *blob,
2943                            unsigned long size,
2944                            const struct object_id *oid,
2945                            int mode)
2946 {
2947         int fd;
2948         struct strbuf buf = STRBUF_INIT;
2949         struct strbuf template = STRBUF_INIT;
2950         char *path_dup = xstrdup(path);
2951         const char *base = basename(path_dup);
2952
2953         /* Generate "XXXXXX_basename.ext" */
2954         strbuf_addstr(&template, "XXXXXX_");
2955         strbuf_addstr(&template, base);
2956
2957         fd = mks_tempfile_ts(&temp->tempfile, template.buf, strlen(base) + 1);
2958         if (fd < 0)
2959                 die_errno("unable to create temp-file");
2960         if (convert_to_working_tree(path,
2961                         (const char *)blob, (size_t)size, &buf)) {
2962                 blob = buf.buf;
2963                 size = buf.len;
2964         }
2965         if (write_in_full(fd, blob, size) != size)
2966                 die_errno("unable to write temp-file");
2967         close_tempfile(&temp->tempfile);
2968         temp->name = get_tempfile_path(&temp->tempfile);
2969         oid_to_hex_r(temp->hex, oid);
2970         xsnprintf(temp->mode, sizeof(temp->mode), "%06o", mode);
2971         strbuf_release(&buf);
2972         strbuf_release(&template);
2973         free(path_dup);
2974 }
2975
2976 static struct diff_tempfile *prepare_temp_file(const char *name,
2977                 struct diff_filespec *one)
2978 {
2979         struct diff_tempfile *temp = claim_diff_tempfile();
2980
2981         if (!DIFF_FILE_VALID(one)) {
2982         not_a_valid_file:
2983                 /* A '-' entry produces this for file-2, and
2984                  * a '+' entry produces this for file-1.
2985                  */
2986                 temp->name = "/dev/null";
2987                 xsnprintf(temp->hex, sizeof(temp->hex), ".");
2988                 xsnprintf(temp->mode, sizeof(temp->mode), ".");
2989                 return temp;
2990         }
2991
2992         if (!S_ISGITLINK(one->mode) &&
2993             (!one->oid_valid ||
2994              reuse_worktree_file(name, one->oid.hash, 1))) {
2995                 struct stat st;
2996                 if (lstat(name, &st) < 0) {
2997                         if (errno == ENOENT)
2998                                 goto not_a_valid_file;
2999                         die_errno("stat(%s)", name);
3000                 }
3001                 if (S_ISLNK(st.st_mode)) {
3002                         struct strbuf sb = STRBUF_INIT;
3003                         if (strbuf_readlink(&sb, name, st.st_size) < 0)
3004                                 die_errno("readlink(%s)", name);
3005                         prep_temp_blob(name, temp, sb.buf, sb.len,
3006                                        (one->oid_valid ?
3007                                         &one->oid : &null_oid),
3008                                        (one->oid_valid ?
3009                                         one->mode : S_IFLNK));
3010                         strbuf_release(&sb);
3011                 }
3012                 else {
3013                         /* we can borrow from the file in the work tree */
3014                         temp->name = name;
3015                         if (!one->oid_valid)
3016                                 sha1_to_hex_r(temp->hex, null_sha1);
3017                         else
3018                                 sha1_to_hex_r(temp->hex, one->oid.hash);
3019                         /* Even though we may sometimes borrow the
3020                          * contents from the work tree, we always want
3021                          * one->mode.  mode is trustworthy even when
3022                          * !(one->sha1_valid), as long as
3023                          * DIFF_FILE_VALID(one).
3024                          */
3025                         xsnprintf(temp->mode, sizeof(temp->mode), "%06o", one->mode);
3026                 }
3027                 return temp;
3028         }
3029         else {
3030                 if (diff_populate_filespec(one, 0))
3031                         die("cannot read data blob for %s", one->path);
3032                 prep_temp_blob(name, temp, one->data, one->size,
3033                                &one->oid, one->mode);
3034         }
3035         return temp;
3036 }
3037
3038 static void add_external_diff_name(struct argv_array *argv,
3039                                    const char *name,
3040                                    struct diff_filespec *df)
3041 {
3042         struct diff_tempfile *temp = prepare_temp_file(name, df);
3043         argv_array_push(argv, temp->name);
3044         argv_array_push(argv, temp->hex);
3045         argv_array_push(argv, temp->mode);
3046 }
3047
3048 /* An external diff command takes:
3049  *
3050  * diff-cmd name infile1 infile1-sha1 infile1-mode \
3051  *               infile2 infile2-sha1 infile2-mode [ rename-to ]
3052  *
3053  */
3054 static void run_external_diff(const char *pgm,
3055                               const char *name,
3056                               const char *other,
3057                               struct diff_filespec *one,
3058                               struct diff_filespec *two,
3059                               const char *xfrm_msg,
3060                               int complete_rewrite,
3061                               struct diff_options *o)
3062 {
3063         struct argv_array argv = ARGV_ARRAY_INIT;
3064         struct argv_array env = ARGV_ARRAY_INIT;
3065         struct diff_queue_struct *q = &diff_queued_diff;
3066
3067         argv_array_push(&argv, pgm);
3068         argv_array_push(&argv, name);
3069
3070         if (one && two) {
3071                 add_external_diff_name(&argv, name, one);
3072                 if (!other)
3073                         add_external_diff_name(&argv, name, two);
3074                 else {
3075                         add_external_diff_name(&argv, other, two);
3076                         argv_array_push(&argv, other);
3077                         argv_array_push(&argv, xfrm_msg);
3078                 }
3079         }
3080
3081         argv_array_pushf(&env, "GIT_DIFF_PATH_COUNTER=%d", ++o->diff_path_counter);
3082         argv_array_pushf(&env, "GIT_DIFF_PATH_TOTAL=%d", q->nr);
3083
3084         if (run_command_v_opt_cd_env(argv.argv, RUN_USING_SHELL, NULL, env.argv))
3085                 die(_("external diff died, stopping at %s"), name);
3086
3087         remove_tempfile();
3088         argv_array_clear(&argv);
3089         argv_array_clear(&env);
3090 }
3091
3092 static int similarity_index(struct diff_filepair *p)
3093 {
3094         return p->score * 100 / MAX_SCORE;
3095 }
3096
3097 static const char *diff_abbrev_oid(const struct object_id *oid, int abbrev)
3098 {
3099         if (startup_info->have_repository)
3100                 return find_unique_abbrev(oid->hash, abbrev);
3101         else {
3102                 char *hex = oid_to_hex(oid);
3103                 if (abbrev < 0)
3104                         abbrev = FALLBACK_DEFAULT_ABBREV;
3105                 if (abbrev > GIT_SHA1_HEXSZ)
3106                         die("BUG: oid abbreviation out of range: %d", abbrev);
3107                 if (abbrev)
3108                         hex[abbrev] = '\0';
3109                 return hex;
3110         }
3111 }
3112
3113 static void fill_metainfo(struct strbuf *msg,
3114                           const char *name,
3115                           const char *other,
3116                           struct diff_filespec *one,
3117                           struct diff_filespec *two,
3118                           struct diff_options *o,
3119                           struct diff_filepair *p,
3120                           int *must_show_header,
3121                           int use_color)
3122 {
3123         const char *set = diff_get_color(use_color, DIFF_METAINFO);
3124         const char *reset = diff_get_color(use_color, DIFF_RESET);
3125         const char *line_prefix = diff_line_prefix(o);
3126
3127         *must_show_header = 1;
3128         strbuf_init(msg, PATH_MAX * 2 + 300);
3129         switch (p->status) {
3130         case DIFF_STATUS_COPIED:
3131                 strbuf_addf(msg, "%s%ssimilarity index %d%%",
3132                             line_prefix, set, similarity_index(p));
3133                 strbuf_addf(msg, "%s\n%s%scopy from ",
3134                             reset,  line_prefix, set);
3135                 quote_c_style(name, msg, NULL, 0);
3136                 strbuf_addf(msg, "%s\n%s%scopy to ", reset, line_prefix, set);
3137                 quote_c_style(other, msg, NULL, 0);
3138                 strbuf_addf(msg, "%s\n", reset);
3139                 break;
3140         case DIFF_STATUS_RENAMED:
3141                 strbuf_addf(msg, "%s%ssimilarity index %d%%",
3142                             line_prefix, set, similarity_index(p));
3143                 strbuf_addf(msg, "%s\n%s%srename from ",
3144                             reset, line_prefix, set);
3145                 quote_c_style(name, msg, NULL, 0);
3146                 strbuf_addf(msg, "%s\n%s%srename to ",
3147                             reset, line_prefix, set);
3148                 quote_c_style(other, msg, NULL, 0);
3149                 strbuf_addf(msg, "%s\n", reset);
3150                 break;
3151         case DIFF_STATUS_MODIFIED:
3152                 if (p->score) {
3153                         strbuf_addf(msg, "%s%sdissimilarity index %d%%%s\n",
3154                                     line_prefix,
3155                                     set, similarity_index(p), reset);
3156                         break;
3157                 }
3158                 /* fallthru */
3159         default:
3160                 *must_show_header = 0;
3161         }
3162         if (one && two && oidcmp(&one->oid, &two->oid)) {
3163                 int abbrev = DIFF_OPT_TST(o, FULL_INDEX) ? 40 : DEFAULT_ABBREV;
3164
3165                 if (DIFF_OPT_TST(o, BINARY)) {
3166                         mmfile_t mf;
3167                         if ((!fill_mmfile(&mf, one) && diff_filespec_is_binary(one)) ||
3168                             (!fill_mmfile(&mf, two) && diff_filespec_is_binary(two)))
3169                                 abbrev = 40;
3170                 }
3171                 strbuf_addf(msg, "%s%sindex %s..%s", line_prefix, set,
3172                             diff_abbrev_oid(&one->oid, abbrev),
3173                             diff_abbrev_oid(&two->oid, abbrev));
3174                 if (one->mode == two->mode)
3175                         strbuf_addf(msg, " %06o", one->mode);
3176                 strbuf_addf(msg, "%s\n", reset);
3177         }
3178 }
3179
3180 static void run_diff_cmd(const char *pgm,
3181                          const char *name,
3182                          const char *other,
3183                          const char *attr_path,
3184                          struct diff_filespec *one,
3185                          struct diff_filespec *two,
3186                          struct strbuf *msg,
3187                          struct diff_options *o,
3188                          struct diff_filepair *p)
3189 {
3190         const char *xfrm_msg = NULL;
3191         int complete_rewrite = (p->status == DIFF_STATUS_MODIFIED) && p->score;
3192         int must_show_header = 0;
3193
3194
3195         if (DIFF_OPT_TST(o, ALLOW_EXTERNAL)) {
3196                 struct userdiff_driver *drv = userdiff_find_by_path(attr_path);
3197                 if (drv && drv->external)
3198                         pgm = drv->external;
3199         }
3200
3201         if (msg) {
3202                 /*
3203                  * don't use colors when the header is intended for an
3204                  * external diff driver
3205                  */
3206                 fill_metainfo(msg, name, other, one, two, o, p,
3207                               &must_show_header,
3208                               want_color(o->use_color) && !pgm);
3209                 xfrm_msg = msg->len ? msg->buf : NULL;
3210         }
3211
3212         if (pgm) {
3213                 run_external_diff(pgm, name, other, one, two, xfrm_msg,
3214                                   complete_rewrite, o);
3215                 return;
3216         }
3217         if (one && two)
3218                 builtin_diff(name, other ? other : name,
3219                              one, two, xfrm_msg, must_show_header,
3220                              o, complete_rewrite);
3221         else
3222                 fprintf(o->file, "* Unmerged path %s\n", name);
3223 }
3224
3225 static void diff_fill_sha1_info(struct diff_filespec *one)
3226 {
3227         if (DIFF_FILE_VALID(one)) {
3228                 if (!one->oid_valid) {
3229                         struct stat st;
3230                         if (one->is_stdin) {
3231                                 oidclr(&one->oid);
3232                                 return;
3233                         }
3234                         if (lstat(one->path, &st) < 0)
3235                                 die_errno("stat '%s'", one->path);
3236                         if (index_path(one->oid.hash, one->path, &st, 0))
3237                                 die("cannot hash %s", one->path);
3238                 }
3239         }
3240         else
3241                 oidclr(&one->oid);
3242 }
3243
3244 static void strip_prefix(int prefix_length, const char **namep, const char **otherp)
3245 {
3246         /* Strip the prefix but do not molest /dev/null and absolute paths */
3247         if (*namep && **namep != '/') {
3248                 *namep += prefix_length;
3249                 if (**namep == '/')
3250                         ++*namep;
3251         }
3252         if (*otherp && **otherp != '/') {
3253                 *otherp += prefix_length;
3254                 if (**otherp == '/')
3255                         ++*otherp;
3256         }
3257 }
3258
3259 static void run_diff(struct diff_filepair *p, struct diff_options *o)
3260 {
3261         const char *pgm = external_diff();
3262         struct strbuf msg;
3263         struct diff_filespec *one = p->one;
3264         struct diff_filespec *two = p->two;
3265         const char *name;
3266         const char *other;
3267         const char *attr_path;
3268
3269         name  = p->one->path;
3270         other = (strcmp(name, p->two->path) ? p->two->path : NULL);
3271         attr_path = name;
3272         if (o->prefix_length)
3273                 strip_prefix(o->prefix_length, &name, &other);
3274
3275         if (!DIFF_OPT_TST(o, ALLOW_EXTERNAL))
3276                 pgm = NULL;
3277
3278         if (DIFF_PAIR_UNMERGED(p)) {
3279                 run_diff_cmd(pgm, name, NULL, attr_path,
3280                              NULL, NULL, NULL, o, p);
3281                 return;
3282         }
3283
3284         diff_fill_sha1_info(one);
3285         diff_fill_sha1_info(two);
3286
3287         if (!pgm &&
3288             DIFF_FILE_VALID(one) && DIFF_FILE_VALID(two) &&
3289             (S_IFMT & one->mode) != (S_IFMT & two->mode)) {
3290                 /*
3291                  * a filepair that changes between file and symlink
3292                  * needs to be split into deletion and creation.
3293                  */
3294                 struct diff_filespec *null = alloc_filespec(two->path);
3295                 run_diff_cmd(NULL, name, other, attr_path,
3296                              one, null, &msg, o, p);
3297                 free(null);
3298                 strbuf_release(&msg);
3299
3300                 null = alloc_filespec(one->path);
3301                 run_diff_cmd(NULL, name, other, attr_path,
3302                              null, two, &msg, o, p);
3303                 free(null);
3304         }
3305         else
3306                 run_diff_cmd(pgm, name, other, attr_path,
3307                              one, two, &msg, o, p);
3308
3309         strbuf_release(&msg);
3310 }
3311
3312 static void run_diffstat(struct diff_filepair *p, struct diff_options *o,
3313                          struct diffstat_t *diffstat)
3314 {
3315         const char *name;
3316         const char *other;
3317
3318         if (DIFF_PAIR_UNMERGED(p)) {
3319                 /* unmerged */
3320                 builtin_diffstat(p->one->path, NULL, NULL, NULL, diffstat, o, p);
3321                 return;
3322         }
3323
3324         name = p->one->path;
3325         other = (strcmp(name, p->two->path) ? p->two->path : NULL);
3326
3327         if (o->prefix_length)
3328                 strip_prefix(o->prefix_length, &name, &other);
3329
3330         diff_fill_sha1_info(p->one);
3331         diff_fill_sha1_info(p->two);
3332
3333         builtin_diffstat(name, other, p->one, p->two, diffstat, o, p);
3334 }
3335
3336 static void run_checkdiff(struct diff_filepair *p, struct diff_options *o)
3337 {
3338         const char *name;
3339         const char *other;
3340         const char *attr_path;
3341
3342         if (DIFF_PAIR_UNMERGED(p)) {
3343                 /* unmerged */
3344                 return;
3345         }
3346
3347         name = p->one->path;
3348         other = (strcmp(name, p->two->path) ? p->two->path : NULL);
3349         attr_path = other ? other : name;
3350
3351         if (o->prefix_length)
3352                 strip_prefix(o->prefix_length, &name, &other);
3353
3354         diff_fill_sha1_info(p->one);
3355         diff_fill_sha1_info(p->two);
3356
3357         builtin_checkdiff(name, other, attr_path, p->one, p->two, o);
3358 }
3359
3360 void diff_setup(struct diff_options *options)
3361 {
3362         memcpy(options, &default_diff_options, sizeof(*options));
3363
3364         options->file = stdout;
3365
3366         options->abbrev = DEFAULT_ABBREV;
3367         options->line_termination = '\n';
3368         options->break_opt = -1;
3369         options->rename_limit = -1;
3370         options->dirstat_permille = diff_dirstat_permille_default;
3371         options->context = diff_context_default;
3372         options->interhunkcontext = diff_interhunk_context_default;
3373         options->ws_error_highlight = ws_error_highlight_default;
3374         DIFF_OPT_SET(options, RENAME_EMPTY);
3375
3376         /* pathchange left =NULL by default */
3377         options->change = diff_change;
3378         options->add_remove = diff_addremove;
3379         options->use_color = diff_use_color_default;
3380         options->detect_rename = diff_detect_rename_default;
3381         options->xdl_opts |= diff_algorithm;
3382         if (diff_indent_heuristic)
3383                 DIFF_XDL_SET(options, INDENT_HEURISTIC);
3384
3385         options->orderfile = diff_order_file_cfg;
3386
3387         if (diff_no_prefix) {
3388                 options->a_prefix = options->b_prefix = "";
3389         } else if (!diff_mnemonic_prefix) {
3390                 options->a_prefix = "a/";
3391                 options->b_prefix = "b/";
3392         }
3393 }
3394
3395 void diff_setup_done(struct diff_options *options)
3396 {
3397         int count = 0;
3398
3399         if (options->set_default)
3400                 options->set_default(options);
3401
3402         if (options->output_format & DIFF_FORMAT_NAME)
3403                 count++;
3404         if (options->output_format & DIFF_FORMAT_NAME_STATUS)
3405                 count++;
3406         if (options->output_format & DIFF_FORMAT_CHECKDIFF)
3407                 count++;
3408         if (options->output_format & DIFF_FORMAT_NO_OUTPUT)
3409                 count++;
3410         if (count > 1)
3411                 die(_("--name-only, --name-status, --check and -s are mutually exclusive"));
3412
3413         /*
3414          * Most of the time we can say "there are changes"
3415          * only by checking if there are changed paths, but
3416          * --ignore-whitespace* options force us to look
3417          * inside contents.
3418          */
3419
3420         if (DIFF_XDL_TST(options, IGNORE_WHITESPACE) ||
3421             DIFF_XDL_TST(options, IGNORE_WHITESPACE_CHANGE) ||
3422             DIFF_XDL_TST(options, IGNORE_WHITESPACE_AT_EOL))
3423                 DIFF_OPT_SET(options, DIFF_FROM_CONTENTS);
3424         else
3425                 DIFF_OPT_CLR(options, DIFF_FROM_CONTENTS);
3426
3427         if (DIFF_OPT_TST(options, FIND_COPIES_HARDER))
3428                 options->detect_rename = DIFF_DETECT_COPY;
3429
3430         if (!DIFF_OPT_TST(options, RELATIVE_NAME))
3431                 options->prefix = NULL;
3432         if (options->prefix)
3433                 options->prefix_length = strlen(options->prefix);
3434         else
3435                 options->prefix_length = 0;
3436
3437         if (options->output_format & (DIFF_FORMAT_NAME |
3438                                       DIFF_FORMAT_NAME_STATUS |
3439                                       DIFF_FORMAT_CHECKDIFF |
3440                                       DIFF_FORMAT_NO_OUTPUT))
3441                 options->output_format &= ~(DIFF_FORMAT_RAW |
3442                                             DIFF_FORMAT_NUMSTAT |
3443                                             DIFF_FORMAT_DIFFSTAT |
3444                                             DIFF_FORMAT_SHORTSTAT |
3445                                             DIFF_FORMAT_DIRSTAT |
3446                                             DIFF_FORMAT_SUMMARY |
3447                                             DIFF_FORMAT_PATCH);
3448
3449         /*
3450          * These cases always need recursive; we do not drop caller-supplied
3451          * recursive bits for other formats here.
3452          */
3453         if (options->output_format & (DIFF_FORMAT_PATCH |
3454                                       DIFF_FORMAT_NUMSTAT |
3455                                       DIFF_FORMAT_DIFFSTAT |
3456                                       DIFF_FORMAT_SHORTSTAT |
3457                                       DIFF_FORMAT_DIRSTAT |
3458                                       DIFF_FORMAT_SUMMARY |
3459                                       DIFF_FORMAT_CHECKDIFF))
3460                 DIFF_OPT_SET(options, RECURSIVE);
3461         /*
3462          * Also pickaxe would not work very well if you do not say recursive
3463          */
3464         if (options->pickaxe)
3465                 DIFF_OPT_SET(options, RECURSIVE);
3466         /*
3467          * When patches are generated, submodules diffed against the work tree
3468          * must be checked for dirtiness too so it can be shown in the output
3469          */
3470         if (options->output_format & DIFF_FORMAT_PATCH)
3471                 DIFF_OPT_SET(options, DIRTY_SUBMODULES);
3472
3473         if (options->detect_rename && options->rename_limit < 0)
3474                 options->rename_limit = diff_rename_limit_default;
3475         if (options->setup & DIFF_SETUP_USE_CACHE) {
3476                 if (!active_cache)
3477                         /* read-cache does not die even when it fails
3478                          * so it is safe for us to do this here.  Also
3479                          * it does not smudge active_cache or active_nr
3480                          * when it fails, so we do not have to worry about
3481                          * cleaning it up ourselves either.
3482                          */
3483                         read_cache();
3484         }
3485         if (40 < options->abbrev)
3486                 options->abbrev = 40; /* full */
3487
3488         /*
3489          * It does not make sense to show the first hit we happened
3490          * to have found.  It does not make sense not to return with
3491          * exit code in such a case either.
3492          */
3493         if (DIFF_OPT_TST(options, QUICK)) {
3494                 options->output_format = DIFF_FORMAT_NO_OUTPUT;
3495                 DIFF_OPT_SET(options, EXIT_WITH_STATUS);
3496         }
3497
3498         options->diff_path_counter = 0;
3499
3500         if (DIFF_OPT_TST(options, FOLLOW_RENAMES) && options->pathspec.nr != 1)
3501                 die(_("--follow requires exactly one pathspec"));
3502 }
3503
3504 static int opt_arg(const char *arg, int arg_short, const char *arg_long, int *val)
3505 {
3506         char c, *eq;
3507         int len;
3508
3509         if (*arg != '-')
3510                 return 0;
3511         c = *++arg;
3512         if (!c)
3513                 return 0;
3514         if (c == arg_short) {
3515                 c = *++arg;
3516                 if (!c)
3517                         return 1;
3518                 if (val && isdigit(c)) {
3519                         char *end;
3520                         int n = strtoul(arg, &end, 10);
3521                         if (*end)
3522                                 return 0;
3523                         *val = n;
3524                         return 1;
3525                 }
3526                 return 0;
3527         }
3528         if (c != '-')
3529                 return 0;
3530         arg++;
3531         eq = strchrnul(arg, '=');
3532         len = eq - arg;
3533         if (!len || strncmp(arg, arg_long, len))
3534                 return 0;
3535         if (*eq) {
3536                 int n;
3537                 char *end;
3538                 if (!isdigit(*++eq))
3539                         return 0;
3540                 n = strtoul(eq, &end, 10);
3541                 if (*end)
3542                         return 0;
3543                 *val = n;
3544         }
3545         return 1;
3546 }
3547
3548 static int diff_scoreopt_parse(const char *opt);
3549
3550 static inline int short_opt(char opt, const char **argv,
3551                             const char **optarg)
3552 {
3553         const char *arg = argv[0];
3554         if (arg[0] != '-' || arg[1] != opt)
3555                 return 0;
3556         if (arg[2] != '\0') {
3557                 *optarg = arg + 2;
3558                 return 1;
3559         }
3560         if (!argv[1])
3561                 die("Option '%c' requires a value", opt);
3562         *optarg = argv[1];
3563         return 2;
3564 }
3565
3566 int parse_long_opt(const char *opt, const char **argv,
3567                    const char **optarg)
3568 {
3569         const char *arg = argv[0];
3570         if (!skip_prefix(arg, "--", &arg))
3571                 return 0;
3572         if (!skip_prefix(arg, opt, &arg))
3573                 return 0;
3574         if (*arg == '=') { /* stuck form: --option=value */
3575                 *optarg = arg + 1;
3576                 return 1;
3577         }
3578         if (*arg != '\0')
3579                 return 0;
3580         /* separate form: --option value */
3581         if (!argv[1])
3582                 die("Option '--%s' requires a value", opt);
3583         *optarg = argv[1];
3584         return 2;
3585 }
3586
3587 static int stat_opt(struct diff_options *options, const char **av)
3588 {
3589         const char *arg = av[0];
3590         char *end;
3591         int width = options->stat_width;
3592         int name_width = options->stat_name_width;
3593         int graph_width = options->stat_graph_width;
3594         int count = options->stat_count;
3595         int argcount = 1;
3596
3597         if (!skip_prefix(arg, "--stat", &arg))
3598                 die("BUG: stat option does not begin with --stat: %s", arg);
3599         end = (char *)arg;
3600
3601         switch (*arg) {
3602         case '-':
3603                 if (skip_prefix(arg, "-width", &arg)) {
3604                         if (*arg == '=')
3605                                 width = strtoul(arg + 1, &end, 10);
3606                         else if (!*arg && !av[1])
3607                                 die_want_option("--stat-width");
3608                         else if (!*arg) {
3609                                 width = strtoul(av[1], &end, 10);
3610                                 argcount = 2;
3611                         }
3612                 } else if (skip_prefix(arg, "-name-width", &arg)) {
3613                         if (*arg == '=')
3614                                 name_width = strtoul(arg + 1, &end, 10);
3615                         else if (!*arg && !av[1])
3616                                 die_want_option("--stat-name-width");
3617                         else if (!*arg) {
3618                                 name_width = strtoul(av[1], &end, 10);
3619                                 argcount = 2;
3620                         }
3621                 } else if (skip_prefix(arg, "-graph-width", &arg)) {
3622                         if (*arg == '=')
3623                                 graph_width = strtoul(arg + 1, &end, 10);
3624                         else if (!*arg && !av[1])
3625                                 die_want_option("--stat-graph-width");
3626                         else if (!*arg) {
3627                                 graph_width = strtoul(av[1], &end, 10);
3628                                 argcount = 2;
3629                         }
3630                 } else if (skip_prefix(arg, "-count", &arg)) {
3631                         if (*arg == '=')
3632                                 count = strtoul(arg + 1, &end, 10);
3633                         else if (!*arg && !av[1])
3634                                 die_want_option("--stat-count");
3635                         else if (!*arg) {
3636                                 count = strtoul(av[1], &end, 10);
3637                                 argcount = 2;
3638                         }
3639                 }
3640                 break;
3641         case '=':
3642                 width = strtoul(arg+1, &end, 10);
3643                 if (*end == ',')
3644                         name_width = strtoul(end+1, &end, 10);
3645                 if (*end == ',')
3646                         count = strtoul(end+1, &end, 10);
3647         }
3648
3649         /* Important! This checks all the error cases! */
3650         if (*end)
3651                 return 0;
3652         options->output_format |= DIFF_FORMAT_DIFFSTAT;
3653         options->stat_name_width = name_width;
3654         options->stat_graph_width = graph_width;
3655         options->stat_width = width;
3656         options->stat_count = count;
3657         return argcount;
3658 }
3659
3660 static int parse_dirstat_opt(struct diff_options *options, const char *params)
3661 {
3662         struct strbuf errmsg = STRBUF_INIT;
3663         if (parse_dirstat_params(options, params, &errmsg))
3664                 die(_("Failed to parse --dirstat/-X option parameter:\n%s"),
3665                     errmsg.buf);
3666         strbuf_release(&errmsg);
3667         /*
3668          * The caller knows a dirstat-related option is given from the command
3669          * line; allow it to say "return this_function();"
3670          */
3671         options->output_format |= DIFF_FORMAT_DIRSTAT;
3672         return 1;
3673 }
3674
3675 static int parse_submodule_opt(struct diff_options *options, const char *value)
3676 {
3677         if (parse_submodule_params(options, value))
3678                 die(_("Failed to parse --submodule option parameter: '%s'"),
3679                         value);
3680         return 1;
3681 }
3682
3683 static const char diff_status_letters[] = {
3684         DIFF_STATUS_ADDED,
3685         DIFF_STATUS_COPIED,
3686         DIFF_STATUS_DELETED,
3687         DIFF_STATUS_MODIFIED,
3688         DIFF_STATUS_RENAMED,
3689         DIFF_STATUS_TYPE_CHANGED,
3690         DIFF_STATUS_UNKNOWN,
3691         DIFF_STATUS_UNMERGED,
3692         DIFF_STATUS_FILTER_AON,
3693         DIFF_STATUS_FILTER_BROKEN,
3694         '\0',
3695 };
3696
3697 static unsigned int filter_bit['Z' + 1];
3698
3699 static void prepare_filter_bits(void)
3700 {
3701         int i;
3702
3703         if (!filter_bit[DIFF_STATUS_ADDED]) {
3704                 for (i = 0; diff_status_letters[i]; i++)
3705                         filter_bit[(int) diff_status_letters[i]] = (1 << i);
3706         }
3707 }
3708
3709 static unsigned filter_bit_tst(char status, const struct diff_options *opt)
3710 {
3711         return opt->filter & filter_bit[(int) status];
3712 }
3713
3714 static int parse_diff_filter_opt(const char *optarg, struct diff_options *opt)
3715 {
3716         int i, optch;
3717
3718         prepare_filter_bits();
3719
3720         /*
3721          * If there is a negation e.g. 'd' in the input, and we haven't
3722          * initialized the filter field with another --diff-filter, start
3723          * from full set of bits, except for AON.
3724          */
3725         if (!opt->filter) {
3726                 for (i = 0; (optch = optarg[i]) != '\0'; i++) {
3727                         if (optch < 'a' || 'z' < optch)
3728                                 continue;
3729                         opt->filter = (1 << (ARRAY_SIZE(diff_status_letters) - 1)) - 1;
3730                         opt->filter &= ~filter_bit[DIFF_STATUS_FILTER_AON];
3731                         break;
3732                 }
3733         }
3734
3735         for (i = 0; (optch = optarg[i]) != '\0'; i++) {
3736                 unsigned int bit;
3737                 int negate;
3738
3739                 if ('a' <= optch && optch <= 'z') {
3740                         negate = 1;
3741                         optch = toupper(optch);
3742                 } else {
3743                         negate = 0;
3744                 }
3745
3746                 bit = (0 <= optch && optch <= 'Z') ? filter_bit[optch] : 0;
3747                 if (!bit)
3748                         return optarg[i];
3749                 if (negate)
3750                         opt->filter &= ~bit;
3751                 else
3752                         opt->filter |= bit;
3753         }
3754         return 0;
3755 }
3756
3757 static void enable_patch_output(int *fmt) {
3758         *fmt &= ~DIFF_FORMAT_NO_OUTPUT;
3759         *fmt |= DIFF_FORMAT_PATCH;
3760 }
3761
3762 static int parse_ws_error_highlight_opt(struct diff_options *opt, const char *arg)
3763 {
3764         int val = parse_ws_error_highlight(arg);
3765
3766         if (val < 0) {
3767                 error("unknown value after ws-error-highlight=%.*s",
3768                       -1 - val, arg);
3769                 return 0;
3770         }
3771         opt->ws_error_highlight = val;
3772         return 1;
3773 }
3774
3775 int diff_opt_parse(struct diff_options *options,
3776                    const char **av, int ac, const char *prefix)
3777 {
3778         const char *arg = av[0];
3779         const char *optarg;
3780         int argcount;
3781
3782         if (!prefix)
3783                 prefix = "";
3784
3785         /* Output format options */
3786         if (!strcmp(arg, "-p") || !strcmp(arg, "-u") || !strcmp(arg, "--patch")
3787             || opt_arg(arg, 'U', "unified", &options->context))
3788                 enable_patch_output(&options->output_format);
3789         else if (!strcmp(arg, "--raw"))
3790                 options->output_format |= DIFF_FORMAT_RAW;
3791         else if (!strcmp(arg, "--patch-with-raw")) {
3792                 enable_patch_output(&options->output_format);
3793                 options->output_format |= DIFF_FORMAT_RAW;
3794         } else if (!strcmp(arg, "--numstat"))
3795                 options->output_format |= DIFF_FORMAT_NUMSTAT;
3796         else if (!strcmp(arg, "--shortstat"))
3797                 options->output_format |= DIFF_FORMAT_SHORTSTAT;
3798         else if (!strcmp(arg, "-X") || !strcmp(arg, "--dirstat"))
3799                 return parse_dirstat_opt(options, "");
3800         else if (skip_prefix(arg, "-X", &arg))
3801                 return parse_dirstat_opt(options, arg);
3802         else if (skip_prefix(arg, "--dirstat=", &arg))
3803                 return parse_dirstat_opt(options, arg);
3804         else if (!strcmp(arg, "--cumulative"))
3805                 return parse_dirstat_opt(options, "cumulative");
3806         else if (!strcmp(arg, "--dirstat-by-file"))
3807                 return parse_dirstat_opt(options, "files");
3808         else if (skip_prefix(arg, "--dirstat-by-file=", &arg)) {
3809                 parse_dirstat_opt(options, "files");
3810                 return parse_dirstat_opt(options, arg);
3811         }
3812         else if (!strcmp(arg, "--check"))
3813                 options->output_format |= DIFF_FORMAT_CHECKDIFF;
3814         else if (!strcmp(arg, "--summary"))
3815                 options->output_format |= DIFF_FORMAT_SUMMARY;
3816         else if (!strcmp(arg, "--patch-with-stat")) {
3817                 enable_patch_output(&options->output_format);
3818                 options->output_format |= DIFF_FORMAT_DIFFSTAT;
3819         } else if (!strcmp(arg, "--name-only"))
3820                 options->output_format |= DIFF_FORMAT_NAME;
3821         else if (!strcmp(arg, "--name-status"))
3822                 options->output_format |= DIFF_FORMAT_NAME_STATUS;
3823         else if (!strcmp(arg, "-s") || !strcmp(arg, "--no-patch"))
3824                 options->output_format |= DIFF_FORMAT_NO_OUTPUT;
3825         else if (starts_with(arg, "--stat"))
3826                 /* --stat, --stat-width, --stat-name-width, or --stat-count */
3827                 return stat_opt(options, av);
3828
3829         /* renames options */
3830         else if (starts_with(arg, "-B") || starts_with(arg, "--break-rewrites=") ||
3831                  !strcmp(arg, "--break-rewrites")) {
3832                 if ((options->break_opt = diff_scoreopt_parse(arg)) == -1)
3833                         return error("invalid argument to -B: %s", arg+2);
3834         }
3835         else if (starts_with(arg, "-M") || starts_with(arg, "--find-renames=") ||
3836                  !strcmp(arg, "--find-renames")) {
3837                 if ((options->rename_score = diff_scoreopt_parse(arg)) == -1)
3838                         return error("invalid argument to -M: %s", arg+2);
3839                 options->detect_rename = DIFF_DETECT_RENAME;
3840         }
3841         else if (!strcmp(arg, "-D") || !strcmp(arg, "--irreversible-delete")) {
3842                 options->irreversible_delete = 1;
3843         }
3844         else if (starts_with(arg, "-C") || starts_with(arg, "--find-copies=") ||
3845                  !strcmp(arg, "--find-copies")) {
3846                 if (options->detect_rename == DIFF_DETECT_COPY)
3847                         DIFF_OPT_SET(options, FIND_COPIES_HARDER);
3848                 if ((options->rename_score = diff_scoreopt_parse(arg)) == -1)
3849                         return error("invalid argument to -C: %s", arg+2);
3850                 options->detect_rename = DIFF_DETECT_COPY;
3851         }
3852         else if (!strcmp(arg, "--no-renames"))
3853                 options->detect_rename = 0;
3854         else if (!strcmp(arg, "--rename-empty"))
3855                 DIFF_OPT_SET(options, RENAME_EMPTY);
3856         else if (!strcmp(arg, "--no-rename-empty"))
3857                 DIFF_OPT_CLR(options, RENAME_EMPTY);
3858         else if (!strcmp(arg, "--relative"))
3859                 DIFF_OPT_SET(options, RELATIVE_NAME);
3860         else if (skip_prefix(arg, "--relative=", &arg)) {
3861                 DIFF_OPT_SET(options, RELATIVE_NAME);
3862                 options->prefix = arg;
3863         }
3864
3865         /* xdiff options */
3866         else if (!strcmp(arg, "--minimal"))
3867                 DIFF_XDL_SET(options, NEED_MINIMAL);
3868         else if (!strcmp(arg, "--no-minimal"))
3869                 DIFF_XDL_CLR(options, NEED_MINIMAL);
3870         else if (!strcmp(arg, "-w") || !strcmp(arg, "--ignore-all-space"))
3871                 DIFF_XDL_SET(options, IGNORE_WHITESPACE);
3872         else if (!strcmp(arg, "-b") || !strcmp(arg, "--ignore-space-change"))
3873                 DIFF_XDL_SET(options, IGNORE_WHITESPACE_CHANGE);
3874         else if (!strcmp(arg, "--ignore-space-at-eol"))
3875                 DIFF_XDL_SET(options, IGNORE_WHITESPACE_AT_EOL);
3876         else if (!strcmp(arg, "--ignore-blank-lines"))
3877                 DIFF_XDL_SET(options, IGNORE_BLANK_LINES);
3878         else if (!strcmp(arg, "--indent-heuristic"))
3879                 DIFF_XDL_SET(options, INDENT_HEURISTIC);
3880         else if (!strcmp(arg, "--no-indent-heuristic"))
3881                 DIFF_XDL_CLR(options, INDENT_HEURISTIC);
3882         else if (!strcmp(arg, "--patience"))
3883                 options->xdl_opts = DIFF_WITH_ALG(options, PATIENCE_DIFF);
3884         else if (!strcmp(arg, "--histogram"))
3885                 options->xdl_opts = DIFF_WITH_ALG(options, HISTOGRAM_DIFF);
3886         else if ((argcount = parse_long_opt("diff-algorithm", av, &optarg))) {
3887                 long value = parse_algorithm_value(optarg);
3888                 if (value < 0)
3889                         return error("option diff-algorithm accepts \"myers\", "
3890                                      "\"minimal\", \"patience\" and \"histogram\"");
3891                 /* clear out previous settings */
3892                 DIFF_XDL_CLR(options, NEED_MINIMAL);
3893                 options->xdl_opts &= ~XDF_DIFF_ALGORITHM_MASK;
3894                 options->xdl_opts |= value;
3895                 return argcount;
3896         }
3897
3898         /* flags options */
3899         else if (!strcmp(arg, "--binary")) {
3900                 enable_patch_output(&options->output_format);
3901                 DIFF_OPT_SET(options, BINARY);
3902         }
3903         else if (!strcmp(arg, "--full-index"))
3904                 DIFF_OPT_SET(options, FULL_INDEX);
3905         else if (!strcmp(arg, "-a") || !strcmp(arg, "--text"))
3906                 DIFF_OPT_SET(options, TEXT);
3907         else if (!strcmp(arg, "-R"))
3908                 DIFF_OPT_SET(options, REVERSE_DIFF);
3909         else if (!strcmp(arg, "--find-copies-harder"))
3910                 DIFF_OPT_SET(options, FIND_COPIES_HARDER);
3911         else if (!strcmp(arg, "--follow"))
3912                 DIFF_OPT_SET(options, FOLLOW_RENAMES);
3913         else if (!strcmp(arg, "--no-follow")) {
3914                 DIFF_OPT_CLR(options, FOLLOW_RENAMES);
3915                 DIFF_OPT_CLR(options, DEFAULT_FOLLOW_RENAMES);
3916         } else if (!strcmp(arg, "--color"))
3917                 options->use_color = 1;
3918         else if (skip_prefix(arg, "--color=", &arg)) {
3919                 int value = git_config_colorbool(NULL, arg);
3920                 if (value < 0)
3921                         return error("option `color' expects \"always\", \"auto\", or \"never\"");
3922                 options->use_color = value;
3923         }
3924         else if (!strcmp(arg, "--no-color"))
3925                 options->use_color = 0;
3926         else if (!strcmp(arg, "--color-words")) {
3927                 options->use_color = 1;
3928                 options->word_diff = DIFF_WORDS_COLOR;
3929         }
3930         else if (skip_prefix(arg, "--color-words=", &arg)) {
3931                 options->use_color = 1;
3932                 options->word_diff = DIFF_WORDS_COLOR;
3933                 options->word_regex = arg;
3934         }
3935         else if (!strcmp(arg, "--word-diff")) {
3936                 if (options->word_diff == DIFF_WORDS_NONE)
3937                         options->word_diff = DIFF_WORDS_PLAIN;
3938         }
3939         else if (skip_prefix(arg, "--word-diff=", &arg)) {
3940                 if (!strcmp(arg, "plain"))
3941                         options->word_diff = DIFF_WORDS_PLAIN;
3942                 else if (!strcmp(arg, "color")) {
3943                         options->use_color = 1;
3944                         options->word_diff = DIFF_WORDS_COLOR;
3945                 }
3946                 else if (!strcmp(arg, "porcelain"))
3947                         options->word_diff = DIFF_WORDS_PORCELAIN;
3948                 else if (!strcmp(arg, "none"))
3949                         options->word_diff = DIFF_WORDS_NONE;
3950                 else
3951                         die("bad --word-diff argument: %s", arg);
3952         }
3953         else if ((argcount = parse_long_opt("word-diff-regex", av, &optarg))) {
3954                 if (options->word_diff == DIFF_WORDS_NONE)
3955                         options->word_diff = DIFF_WORDS_PLAIN;
3956                 options->word_regex = optarg;
3957                 return argcount;
3958         }
3959         else if (!strcmp(arg, "--exit-code"))
3960                 DIFF_OPT_SET(options, EXIT_WITH_STATUS);
3961         else if (!strcmp(arg, "--quiet"))
3962                 DIFF_OPT_SET(options, QUICK);
3963         else if (!strcmp(arg, "--ext-diff"))
3964                 DIFF_OPT_SET(options, ALLOW_EXTERNAL);
3965         else if (!strcmp(arg, "--no-ext-diff"))
3966                 DIFF_OPT_CLR(options, ALLOW_EXTERNAL);
3967         else if (!strcmp(arg, "--textconv"))
3968                 DIFF_OPT_SET(options, ALLOW_TEXTCONV);
3969         else if (!strcmp(arg, "--no-textconv"))
3970                 DIFF_OPT_CLR(options, ALLOW_TEXTCONV);
3971         else if (!strcmp(arg, "--ignore-submodules")) {
3972                 DIFF_OPT_SET(options, OVERRIDE_SUBMODULE_CONFIG);
3973                 handle_ignore_submodules_arg(options, "all");
3974         } else if (skip_prefix(arg, "--ignore-submodules=", &arg)) {
3975                 DIFF_OPT_SET(options, OVERRIDE_SUBMODULE_CONFIG);
3976                 handle_ignore_submodules_arg(options, arg);
3977         } else if (!strcmp(arg, "--submodule"))
3978                 options->submodule_format = DIFF_SUBMODULE_LOG;
3979         else if (skip_prefix(arg, "--submodule=", &arg))
3980                 return parse_submodule_opt(options, arg);
3981         else if (skip_prefix(arg, "--ws-error-highlight=", &arg))
3982                 return parse_ws_error_highlight_opt(options, arg);
3983         else if (!strcmp(arg, "--ita-invisible-in-index"))
3984                 options->ita_invisible_in_index = 1;
3985         else if (!strcmp(arg, "--ita-visible-in-index"))
3986                 options->ita_invisible_in_index = 0;
3987
3988         /* misc options */
3989         else if (!strcmp(arg, "-z"))
3990                 options->line_termination = 0;
3991         else if ((argcount = short_opt('l', av, &optarg))) {
3992                 options->rename_limit = strtoul(optarg, NULL, 10);
3993                 return argcount;
3994         }
3995         else if ((argcount = short_opt('S', av, &optarg))) {
3996                 options->pickaxe = optarg;
3997                 options->pickaxe_opts |= DIFF_PICKAXE_KIND_S;
3998                 return argcount;
3999         } else if ((argcount = short_opt('G', av, &optarg))) {
4000                 options->pickaxe = optarg;
4001                 options->pickaxe_opts |= DIFF_PICKAXE_KIND_G;
4002                 return argcount;
4003         }
4004         else if (!strcmp(arg, "--pickaxe-all"))
4005                 options->pickaxe_opts |= DIFF_PICKAXE_ALL;
4006         else if (!strcmp(arg, "--pickaxe-regex"))
4007                 options->pickaxe_opts |= DIFF_PICKAXE_REGEX;
4008         else if ((argcount = short_opt('O', av, &optarg))) {
4009                 const char *path = prefix_filename(prefix, strlen(prefix), optarg);
4010                 options->orderfile = xstrdup(path);
4011                 return argcount;
4012         }
4013         else if ((argcount = parse_long_opt("diff-filter", av, &optarg))) {
4014                 int offending = parse_diff_filter_opt(optarg, options);
4015                 if (offending)
4016                         die("unknown change class '%c' in --diff-filter=%s",
4017                             offending, optarg);
4018                 return argcount;
4019         }
4020         else if (!strcmp(arg, "--no-abbrev"))
4021                 options->abbrev = 0;
4022         else if (!strcmp(arg, "--abbrev"))
4023                 options->abbrev = DEFAULT_ABBREV;
4024         else if (skip_prefix(arg, "--abbrev=", &arg)) {
4025                 options->abbrev = strtoul(arg, NULL, 10);
4026                 if (options->abbrev < MINIMUM_ABBREV)
4027                         options->abbrev = MINIMUM_ABBREV;
4028                 else if (40 < options->abbrev)
4029                         options->abbrev = 40;
4030         }
4031         else if ((argcount = parse_long_opt("src-prefix", av, &optarg))) {
4032                 options->a_prefix = optarg;
4033                 return argcount;
4034         }
4035         else if ((argcount = parse_long_opt("line-prefix", av, &optarg))) {
4036                 options->line_prefix = optarg;
4037                 options->line_prefix_length = strlen(options->line_prefix);
4038                 graph_setup_line_prefix(options);
4039                 return argcount;
4040         }
4041         else if ((argcount = parse_long_opt("dst-prefix", av, &optarg))) {
4042                 options->b_prefix = optarg;
4043                 return argcount;
4044         }
4045         else if (!strcmp(arg, "--no-prefix"))
4046                 options->a_prefix = options->b_prefix = "";
4047         else if (opt_arg(arg, '\0', "inter-hunk-context",
4048                          &options->interhunkcontext))
4049                 ;
4050         else if (!strcmp(arg, "-W"))
4051                 DIFF_OPT_SET(options, FUNCCONTEXT);
4052         else if (!strcmp(arg, "--function-context"))
4053                 DIFF_OPT_SET(options, FUNCCONTEXT);
4054         else if (!strcmp(arg, "--no-function-context"))
4055                 DIFF_OPT_CLR(options, FUNCCONTEXT);
4056         else if ((argcount = parse_long_opt("output", av, &optarg))) {
4057                 const char *path = prefix_filename(prefix, strlen(prefix), optarg);
4058                 options->file = fopen(path, "w");
4059                 if (!options->file)
4060                         die_errno("Could not open '%s'", path);
4061                 options->close_file = 1;
4062                 if (options->use_color != GIT_COLOR_ALWAYS)
4063                         options->use_color = GIT_COLOR_NEVER;
4064                 return argcount;
4065         } else
4066                 return 0;
4067         return 1;
4068 }
4069
4070 int parse_rename_score(const char **cp_p)
4071 {
4072         unsigned long num, scale;
4073         int ch, dot;
4074         const char *cp = *cp_p;
4075
4076         num = 0;
4077         scale = 1;
4078         dot = 0;
4079         for (;;) {
4080                 ch = *cp;
4081                 if ( !dot && ch == '.' ) {
4082                         scale = 1;
4083                         dot = 1;
4084                 } else if ( ch == '%' ) {
4085                         scale = dot ? scale*100 : 100;
4086                         cp++;   /* % is always at the end */
4087                         break;
4088                 } else if ( ch >= '0' && ch <= '9' ) {
4089                         if ( scale < 100000 ) {
4090                                 scale *= 10;
4091                                 num = (num*10) + (ch-'0');
4092                         }
4093                 } else {
4094                         break;
4095                 }
4096                 cp++;
4097         }
4098         *cp_p = cp;
4099
4100         /* user says num divided by scale and we say internally that
4101          * is MAX_SCORE * num / scale.
4102          */
4103         return (int)((num >= scale) ? MAX_SCORE : (MAX_SCORE * num / scale));
4104 }
4105
4106 static int diff_scoreopt_parse(const char *opt)
4107 {
4108         int opt1, opt2, cmd;
4109
4110         if (*opt++ != '-')
4111                 return -1;
4112         cmd = *opt++;
4113         if (cmd == '-') {
4114                 /* convert the long-form arguments into short-form versions */
4115                 if (skip_prefix(opt, "break-rewrites", &opt)) {
4116                         if (*opt == 0 || *opt++ == '=')
4117                                 cmd = 'B';
4118                 } else if (skip_prefix(opt, "find-copies", &opt)) {
4119                         if (*opt == 0 || *opt++ == '=')
4120                                 cmd = 'C';
4121                 } else if (skip_prefix(opt, "find-renames", &opt)) {
4122                         if (*opt == 0 || *opt++ == '=')
4123                                 cmd = 'M';
4124                 }
4125         }
4126         if (cmd != 'M' && cmd != 'C' && cmd != 'B')
4127                 return -1; /* that is not a -M, -C, or -B option */
4128
4129         opt1 = parse_rename_score(&opt);
4130         if (cmd != 'B')
4131                 opt2 = 0;
4132         else {
4133                 if (*opt == 0)
4134                         opt2 = 0;
4135                 else if (*opt != '/')
4136                         return -1; /* we expect -B80/99 or -B80 */
4137                 else {
4138                         opt++;
4139                         opt2 = parse_rename_score(&opt);
4140                 }
4141         }
4142         if (*opt != 0)
4143                 return -1;
4144         return opt1 | (opt2 << 16);
4145 }
4146
4147 struct diff_queue_struct diff_queued_diff;
4148
4149 void diff_q(struct diff_queue_struct *queue, struct diff_filepair *dp)
4150 {
4151         ALLOC_GROW(queue->queue, queue->nr + 1, queue->alloc);
4152         queue->queue[queue->nr++] = dp;
4153 }
4154
4155 struct diff_filepair *diff_queue(struct diff_queue_struct *queue,
4156                                  struct diff_filespec *one,
4157                                  struct diff_filespec *two)
4158 {
4159         struct diff_filepair *dp = xcalloc(1, sizeof(*dp));
4160         dp->one = one;
4161         dp->two = two;
4162         if (queue)
4163                 diff_q(queue, dp);
4164         return dp;
4165 }
4166
4167 void diff_free_filepair(struct diff_filepair *p)
4168 {
4169         free_filespec(p->one);
4170         free_filespec(p->two);
4171         free(p);
4172 }
4173
4174 const char *diff_aligned_abbrev(const struct object_id *oid, int len)
4175 {
4176         int abblen;
4177         const char *abbrev;
4178
4179         if (len == GIT_SHA1_HEXSZ)
4180                 return oid_to_hex(oid);
4181
4182         abbrev = diff_abbrev_oid(oid, len);
4183         abblen = strlen(abbrev);
4184
4185         /*
4186          * In well-behaved cases, where the abbbreviated result is the
4187          * same as the requested length, append three dots after the
4188          * abbreviation (hence the whole logic is limited to the case
4189          * where abblen < 37); when the actual abbreviated result is a
4190          * bit longer than the requested length, we reduce the number
4191          * of dots so that they match the well-behaved ones.  However,
4192          * if the actual abbreviation is longer than the requested
4193          * length by more than three, we give up on aligning, and add
4194          * three dots anyway, to indicate that the output is not the
4195          * full object name.  Yes, this may be suboptimal, but this
4196          * appears only in "diff --raw --abbrev" output and it is not
4197          * worth the effort to change it now.  Note that this would
4198          * likely to work fine when the automatic sizing of default
4199          * abbreviation length is used--we would be fed -1 in "len" in
4200          * that case, and will end up always appending three-dots, but
4201          * the automatic sizing is supposed to give abblen that ensures
4202          * uniqueness across all objects (statistically speaking).
4203          */
4204         if (abblen < GIT_SHA1_HEXSZ - 3) {
4205                 static char hex[GIT_SHA1_HEXSZ + 1];
4206                 if (len < abblen && abblen <= len + 2)
4207                         xsnprintf(hex, sizeof(hex), "%s%.*s", abbrev, len+3-abblen, "..");
4208                 else
4209                         xsnprintf(hex, sizeof(hex), "%s...", abbrev);
4210                 return hex;
4211         }
4212
4213         return oid_to_hex(oid);
4214 }
4215
4216 static void diff_flush_raw(struct diff_filepair *p, struct diff_options *opt)
4217 {
4218         int line_termination = opt->line_termination;
4219         int inter_name_termination = line_termination ? '\t' : '\0';
4220
4221         fprintf(opt->file, "%s", diff_line_prefix(opt));
4222         if (!(opt->output_format & DIFF_FORMAT_NAME_STATUS)) {
4223                 fprintf(opt->file, ":%06o %06o %s ", p->one->mode, p->two->mode,
4224                         diff_aligned_abbrev(&p->one->oid, opt->abbrev));
4225                 fprintf(opt->file, "%s ",
4226                         diff_aligned_abbrev(&p->two->oid, opt->abbrev));
4227         }
4228         if (p->score) {
4229                 fprintf(opt->file, "%c%03d%c", p->status, similarity_index(p),
4230                         inter_name_termination);
4231         } else {
4232                 fprintf(opt->file, "%c%c", p->status, inter_name_termination);
4233         }
4234
4235         if (p->status == DIFF_STATUS_COPIED ||
4236             p->status == DIFF_STATUS_RENAMED) {
4237                 const char *name_a, *name_b;
4238                 name_a = p->one->path;
4239                 name_b = p->two->path;
4240                 strip_prefix(opt->prefix_length, &name_a, &name_b);
4241                 write_name_quoted(name_a, opt->file, inter_name_termination);
4242                 write_name_quoted(name_b, opt->file, line_termination);
4243         } else {
4244                 const char *name_a, *name_b;
4245                 name_a = p->one->mode ? p->one->path : p->two->path;
4246                 name_b = NULL;
4247                 strip_prefix(opt->prefix_length, &name_a, &name_b);
4248                 write_name_quoted(name_a, opt->file, line_termination);
4249         }
4250 }
4251
4252 int diff_unmodified_pair(struct diff_filepair *p)
4253 {
4254         /* This function is written stricter than necessary to support
4255          * the currently implemented transformers, but the idea is to
4256          * let transformers to produce diff_filepairs any way they want,
4257          * and filter and clean them up here before producing the output.
4258          */
4259         struct diff_filespec *one = p->one, *two = p->two;
4260
4261         if (DIFF_PAIR_UNMERGED(p))
4262                 return 0; /* unmerged is interesting */
4263
4264         /* deletion, addition, mode or type change
4265          * and rename are all interesting.
4266          */
4267         if (DIFF_FILE_VALID(one) != DIFF_FILE_VALID(two) ||
4268             DIFF_PAIR_MODE_CHANGED(p) ||
4269             strcmp(one->path, two->path))
4270                 return 0;
4271
4272         /* both are valid and point at the same path.  that is, we are
4273          * dealing with a change.
4274          */
4275         if (one->oid_valid && two->oid_valid &&
4276             !oidcmp(&one->oid, &two->oid) &&
4277             !one->dirty_submodule && !two->dirty_submodule)
4278                 return 1; /* no change */
4279         if (!one->oid_valid && !two->oid_valid)
4280                 return 1; /* both look at the same file on the filesystem. */
4281         return 0;
4282 }
4283
4284 static void diff_flush_patch(struct diff_filepair *p, struct diff_options *o)
4285 {
4286         if (diff_unmodified_pair(p))
4287                 return;
4288
4289         if ((DIFF_FILE_VALID(p->one) && S_ISDIR(p->one->mode)) ||
4290             (DIFF_FILE_VALID(p->two) && S_ISDIR(p->two->mode)))
4291                 return; /* no tree diffs in patch format */
4292
4293         run_diff(p, o);
4294 }
4295
4296 static void diff_flush_stat(struct diff_filepair *p, struct diff_options *o,
4297                             struct diffstat_t *diffstat)
4298 {
4299         if (diff_unmodified_pair(p))
4300                 return;
4301
4302         if ((DIFF_FILE_VALID(p->one) && S_ISDIR(p->one->mode)) ||
4303             (DIFF_FILE_VALID(p->two) && S_ISDIR(p->two->mode)))
4304                 return; /* no useful stat for tree diffs */
4305
4306         run_diffstat(p, o, diffstat);
4307 }
4308
4309 static void diff_flush_checkdiff(struct diff_filepair *p,
4310                 struct diff_options *o)
4311 {
4312         if (diff_unmodified_pair(p))
4313                 return;
4314
4315         if ((DIFF_FILE_VALID(p->one) && S_ISDIR(p->one->mode)) ||
4316             (DIFF_FILE_VALID(p->two) && S_ISDIR(p->two->mode)))
4317                 return; /* nothing to check in tree diffs */
4318
4319         run_checkdiff(p, o);
4320 }
4321
4322 int diff_queue_is_empty(void)
4323 {
4324         struct diff_queue_struct *q = &diff_queued_diff;
4325         int i;
4326         for (i = 0; i < q->nr; i++)
4327                 if (!diff_unmodified_pair(q->queue[i]))
4328                         return 0;
4329         return 1;
4330 }
4331
4332 #if DIFF_DEBUG
4333 void diff_debug_filespec(struct diff_filespec *s, int x, const char *one)
4334 {
4335         fprintf(stderr, "queue[%d] %s (%s) %s %06o %s\n",
4336                 x, one ? one : "",
4337                 s->path,
4338                 DIFF_FILE_VALID(s) ? "valid" : "invalid",
4339                 s->mode,
4340                 s->oid_valid ? oid_to_hex(&s->oid) : "");
4341         fprintf(stderr, "queue[%d] %s size %lu\n",
4342                 x, one ? one : "",
4343                 s->size);
4344 }
4345
4346 void diff_debug_filepair(const struct diff_filepair *p, int i)
4347 {
4348         diff_debug_filespec(p->one, i, "one");
4349         diff_debug_filespec(p->two, i, "two");
4350         fprintf(stderr, "score %d, status %c rename_used %d broken %d\n",
4351                 p->score, p->status ? p->status : '?',
4352                 p->one->rename_used, p->broken_pair);
4353 }
4354
4355 void diff_debug_queue(const char *msg, struct diff_queue_struct *q)
4356 {
4357         int i;
4358         if (msg)
4359                 fprintf(stderr, "%s\n", msg);
4360         fprintf(stderr, "q->nr = %d\n", q->nr);
4361         for (i = 0; i < q->nr; i++) {
4362                 struct diff_filepair *p = q->queue[i];
4363                 diff_debug_filepair(p, i);
4364         }
4365 }
4366 #endif
4367
4368 static void diff_resolve_rename_copy(void)
4369 {
4370         int i;
4371         struct diff_filepair *p;
4372         struct diff_queue_struct *q = &diff_queued_diff;
4373
4374         diff_debug_queue("resolve-rename-copy", q);
4375
4376         for (i = 0; i < q->nr; i++) {
4377                 p = q->queue[i];
4378                 p->status = 0; /* undecided */
4379                 if (DIFF_PAIR_UNMERGED(p))
4380                         p->status = DIFF_STATUS_UNMERGED;
4381                 else if (!DIFF_FILE_VALID(p->one))
4382                         p->status = DIFF_STATUS_ADDED;
4383                 else if (!DIFF_FILE_VALID(p->two))
4384                         p->status = DIFF_STATUS_DELETED;
4385                 else if (DIFF_PAIR_TYPE_CHANGED(p))
4386                         p->status = DIFF_STATUS_TYPE_CHANGED;
4387
4388                 /* from this point on, we are dealing with a pair
4389                  * whose both sides are valid and of the same type, i.e.
4390                  * either in-place edit or rename/copy edit.
4391                  */
4392                 else if (DIFF_PAIR_RENAME(p)) {
4393                         /*
4394                          * A rename might have re-connected a broken
4395                          * pair up, causing the pathnames to be the
4396                          * same again. If so, that's not a rename at
4397                          * all, just a modification..
4398                          *
4399                          * Otherwise, see if this source was used for
4400                          * multiple renames, in which case we decrement
4401                          * the count, and call it a copy.
4402                          */
4403                         if (!strcmp(p->one->path, p->two->path))
4404                                 p->status = DIFF_STATUS_MODIFIED;
4405                         else if (--p->one->rename_used > 0)
4406                                 p->status = DIFF_STATUS_COPIED;
4407                         else
4408                                 p->status = DIFF_STATUS_RENAMED;
4409                 }
4410                 else if (oidcmp(&p->one->oid, &p->two->oid) ||
4411                          p->one->mode != p->two->mode ||
4412                          p->one->dirty_submodule ||
4413                          p->two->dirty_submodule ||
4414                          is_null_oid(&p->one->oid))
4415                         p->status = DIFF_STATUS_MODIFIED;
4416                 else {
4417                         /* This is a "no-change" entry and should not
4418                          * happen anymore, but prepare for broken callers.
4419                          */
4420                         error("feeding unmodified %s to diffcore",
4421                               p->one->path);
4422                         p->status = DIFF_STATUS_UNKNOWN;
4423                 }
4424         }
4425         diff_debug_queue("resolve-rename-copy done", q);
4426 }
4427
4428 static int check_pair_status(struct diff_filepair *p)
4429 {
4430         switch (p->status) {
4431         case DIFF_STATUS_UNKNOWN:
4432                 return 0;
4433         case 0:
4434                 die("internal error in diff-resolve-rename-copy");
4435         default:
4436                 return 1;
4437         }
4438 }
4439
4440 static void flush_one_pair(struct diff_filepair *p, struct diff_options *opt)
4441 {
4442         int fmt = opt->output_format;
4443
4444         if (fmt & DIFF_FORMAT_CHECKDIFF)
4445                 diff_flush_checkdiff(p, opt);
4446         else if (fmt & (DIFF_FORMAT_RAW | DIFF_FORMAT_NAME_STATUS))
4447                 diff_flush_raw(p, opt);
4448         else if (fmt & DIFF_FORMAT_NAME) {
4449                 const char *name_a, *name_b;
4450                 name_a = p->two->path;
4451                 name_b = NULL;
4452                 strip_prefix(opt->prefix_length, &name_a, &name_b);
4453                 write_name_quoted(name_a, opt->file, opt->line_termination);
4454         }
4455 }
4456
4457 static void show_file_mode_name(FILE *file, const char *newdelete, struct diff_filespec *fs)
4458 {
4459         if (fs->mode)
4460                 fprintf(file, " %s mode %06o ", newdelete, fs->mode);
4461         else
4462                 fprintf(file, " %s ", newdelete);
4463         write_name_quoted(fs->path, file, '\n');
4464 }
4465
4466
4467 static void show_mode_change(FILE *file, struct diff_filepair *p, int show_name,
4468                 const char *line_prefix)
4469 {
4470         if (p->one->mode && p->two->mode && p->one->mode != p->two->mode) {
4471                 fprintf(file, "%s mode change %06o => %06o%c", line_prefix, p->one->mode,
4472                         p->two->mode, show_name ? ' ' : '\n');
4473                 if (show_name) {
4474                         write_name_quoted(p->two->path, file, '\n');
4475                 }
4476         }
4477 }
4478
4479 static void show_rename_copy(FILE *file, const char *renamecopy, struct diff_filepair *p,
4480                         const char *line_prefix)
4481 {
4482         char *names = pprint_rename(p->one->path, p->two->path);
4483
4484         fprintf(file, " %s %s (%d%%)\n", renamecopy, names, similarity_index(p));
4485         free(names);
4486         show_mode_change(file, p, 0, line_prefix);
4487 }
4488
4489 static void diff_summary(struct diff_options *opt, struct diff_filepair *p)
4490 {
4491         FILE *file = opt->file;
4492         const char *line_prefix = diff_line_prefix(opt);
4493
4494         switch(p->status) {
4495         case DIFF_STATUS_DELETED:
4496                 fputs(line_prefix, file);
4497                 show_file_mode_name(file, "delete", p->one);
4498                 break;
4499         case DIFF_STATUS_ADDED:
4500                 fputs(line_prefix, file);
4501                 show_file_mode_name(file, "create", p->two);
4502                 break;
4503         case DIFF_STATUS_COPIED:
4504                 fputs(line_prefix, file);
4505                 show_rename_copy(file, "copy", p, line_prefix);
4506                 break;
4507         case DIFF_STATUS_RENAMED:
4508                 fputs(line_prefix, file);
4509                 show_rename_copy(file, "rename", p, line_prefix);
4510                 break;
4511         default:
4512                 if (p->score) {
4513                         fprintf(file, "%s rewrite ", line_prefix);
4514                         write_name_quoted(p->two->path, file, ' ');
4515                         fprintf(file, "(%d%%)\n", similarity_index(p));
4516                 }
4517                 show_mode_change(file, p, !p->score, line_prefix);
4518                 break;
4519         }
4520 }
4521
4522 struct patch_id_t {
4523         git_SHA_CTX *ctx;
4524         int patchlen;
4525 };
4526
4527 static int remove_space(char *line, int len)
4528 {
4529         int i;
4530         char *dst = line;
4531         unsigned char c;
4532
4533         for (i = 0; i < len; i++)
4534                 if (!isspace((c = line[i])))
4535                         *dst++ = c;
4536
4537         return dst - line;
4538 }
4539
4540 static void patch_id_consume(void *priv, char *line, unsigned long len)
4541 {
4542         struct patch_id_t *data = priv;
4543         int new_len;
4544
4545         /* Ignore line numbers when computing the SHA1 of the patch */
4546         if (starts_with(line, "@@ -"))
4547                 return;
4548
4549         new_len = remove_space(line, len);
4550
4551         git_SHA1_Update(data->ctx, line, new_len);
4552         data->patchlen += new_len;
4553 }
4554
4555 /* returns 0 upon success, and writes result into sha1 */
4556 static int diff_get_patch_id(struct diff_options *options, unsigned char *sha1, int diff_header_only)
4557 {
4558         struct diff_queue_struct *q = &diff_queued_diff;
4559         int i;
4560         git_SHA_CTX ctx;
4561         struct patch_id_t data;
4562         char buffer[PATH_MAX * 4 + 20];
4563
4564         git_SHA1_Init(&ctx);
4565         memset(&data, 0, sizeof(struct patch_id_t));
4566         data.ctx = &ctx;
4567
4568         for (i = 0; i < q->nr; i++) {
4569                 xpparam_t xpp;
4570                 xdemitconf_t xecfg;
4571                 mmfile_t mf1, mf2;
4572                 struct diff_filepair *p = q->queue[i];
4573                 int len1, len2;
4574
4575                 memset(&xpp, 0, sizeof(xpp));
4576                 memset(&xecfg, 0, sizeof(xecfg));
4577                 if (p->status == 0)
4578                         return error("internal diff status error");
4579                 if (p->status == DIFF_STATUS_UNKNOWN)
4580                         continue;
4581                 if (diff_unmodified_pair(p))
4582                         continue;
4583                 if ((DIFF_FILE_VALID(p->one) && S_ISDIR(p->one->mode)) ||
4584                     (DIFF_FILE_VALID(p->two) && S_ISDIR(p->two->mode)))
4585                         continue;
4586                 if (DIFF_PAIR_UNMERGED(p))
4587                         continue;
4588
4589                 diff_fill_sha1_info(p->one);
4590                 diff_fill_sha1_info(p->two);
4591
4592                 len1 = remove_space(p->one->path, strlen(p->one->path));
4593                 len2 = remove_space(p->two->path, strlen(p->two->path));
4594                 if (p->one->mode == 0)
4595                         len1 = snprintf(buffer, sizeof(buffer),
4596                                         "diff--gita/%.*sb/%.*s"
4597                                         "newfilemode%06o"
4598                                         "---/dev/null"
4599                                         "+++b/%.*s",
4600                                         len1, p->one->path,
4601                                         len2, p->two->path,
4602                                         p->two->mode,
4603                                         len2, p->two->path);
4604                 else if (p->two->mode == 0)
4605                         len1 = snprintf(buffer, sizeof(buffer),
4606                                         "diff--gita/%.*sb/%.*s"
4607                                         "deletedfilemode%06o"
4608                                         "---a/%.*s"
4609                                         "+++/dev/null",
4610                                         len1, p->one->path,
4611                                         len2, p->two->path,
4612                                         p->one->mode,
4613                                         len1, p->one->path);
4614                 else
4615                         len1 = snprintf(buffer, sizeof(buffer),
4616                                         "diff--gita/%.*sb/%.*s"
4617                                         "---a/%.*s"
4618                                         "+++b/%.*s",
4619                                         len1, p->one->path,
4620                                         len2, p->two->path,
4621                                         len1, p->one->path,
4622                                         len2, p->two->path);
4623                 git_SHA1_Update(&ctx, buffer, len1);
4624
4625                 if (diff_header_only)
4626                         continue;
4627
4628                 if (fill_mmfile(&mf1, p->one) < 0 ||
4629                     fill_mmfile(&mf2, p->two) < 0)
4630                         return error("unable to read files to diff");
4631
4632                 if (diff_filespec_is_binary(p->one) ||
4633                     diff_filespec_is_binary(p->two)) {
4634                         git_SHA1_Update(&ctx, oid_to_hex(&p->one->oid),
4635                                         40);
4636                         git_SHA1_Update(&ctx, oid_to_hex(&p->two->oid),
4637                                         40);
4638                         continue;
4639                 }
4640
4641                 xpp.flags = 0;
4642                 xecfg.ctxlen = 3;
4643                 xecfg.flags = 0;
4644                 if (xdi_diff_outf(&mf1, &mf2, patch_id_consume, &data,
4645                                   &xpp, &xecfg))
4646                         return error("unable to generate patch-id diff for %s",
4647                                      p->one->path);
4648         }
4649
4650         git_SHA1_Final(sha1, &ctx);
4651         return 0;
4652 }
4653
4654 int diff_flush_patch_id(struct diff_options *options, unsigned char *sha1, int diff_header_only)
4655 {
4656         struct diff_queue_struct *q = &diff_queued_diff;
4657         int i;
4658         int result = diff_get_patch_id(options, sha1, diff_header_only);
4659
4660         for (i = 0; i < q->nr; i++)
4661                 diff_free_filepair(q->queue[i]);
4662
4663         free(q->queue);
4664         DIFF_QUEUE_CLEAR(q);
4665
4666         return result;
4667 }
4668
4669 static int is_summary_empty(const struct diff_queue_struct *q)
4670 {
4671         int i;
4672
4673         for (i = 0; i < q->nr; i++) {
4674                 const struct diff_filepair *p = q->queue[i];
4675
4676                 switch (p->status) {
4677                 case DIFF_STATUS_DELETED:
4678                 case DIFF_STATUS_ADDED:
4679                 case DIFF_STATUS_COPIED:
4680                 case DIFF_STATUS_RENAMED:
4681                         return 0;
4682                 default:
4683                         if (p->score)
4684                                 return 0;
4685                         if (p->one->mode && p->two->mode &&
4686                             p->one->mode != p->two->mode)
4687                                 return 0;
4688                         break;
4689                 }
4690         }
4691         return 1;
4692 }
4693
4694 static const char rename_limit_warning[] =
4695 N_("inexact rename detection was skipped due to too many files.");
4696
4697 static const char degrade_cc_to_c_warning[] =
4698 N_("only found copies from modified paths due to too many files.");
4699
4700 static const char rename_limit_advice[] =
4701 N_("you may want to set your %s variable to at least "
4702    "%d and retry the command.");
4703
4704 void diff_warn_rename_limit(const char *varname, int needed, int degraded_cc)
4705 {
4706         if (degraded_cc)
4707                 warning(_(degrade_cc_to_c_warning));
4708         else if (needed)
4709                 warning(_(rename_limit_warning));
4710         else
4711                 return;
4712         if (0 < needed && needed < 32767)
4713                 warning(_(rename_limit_advice), varname, needed);
4714 }
4715
4716 void diff_flush(struct diff_options *options)
4717 {
4718         struct diff_queue_struct *q = &diff_queued_diff;
4719         int i, output_format = options->output_format;
4720         int separator = 0;
4721         int dirstat_by_line = 0;
4722
4723         /*
4724          * Order: raw, stat, summary, patch
4725          * or:    name/name-status/checkdiff (other bits clear)
4726          */
4727         if (!q->nr)
4728                 goto free_queue;
4729
4730         if (output_format & (DIFF_FORMAT_RAW |
4731                              DIFF_FORMAT_NAME |
4732                              DIFF_FORMAT_NAME_STATUS |
4733                              DIFF_FORMAT_CHECKDIFF)) {
4734                 for (i = 0; i < q->nr; i++) {
4735                         struct diff_filepair *p = q->queue[i];
4736                         if (check_pair_status(p))
4737                                 flush_one_pair(p, options);
4738                 }
4739                 separator++;
4740         }
4741
4742         if (output_format & DIFF_FORMAT_DIRSTAT && DIFF_OPT_TST(options, DIRSTAT_BY_LINE))
4743                 dirstat_by_line = 1;
4744
4745         if (output_format & (DIFF_FORMAT_DIFFSTAT|DIFF_FORMAT_SHORTSTAT|DIFF_FORMAT_NUMSTAT) ||
4746             dirstat_by_line) {
4747                 struct diffstat_t diffstat;
4748
4749                 memset(&diffstat, 0, sizeof(struct diffstat_t));
4750                 for (i = 0; i < q->nr; i++) {
4751                         struct diff_filepair *p = q->queue[i];
4752                         if (check_pair_status(p))
4753                                 diff_flush_stat(p, options, &diffstat);
4754                 }
4755                 if (output_format & DIFF_FORMAT_NUMSTAT)
4756                         show_numstat(&diffstat, options);
4757                 if (output_format & DIFF_FORMAT_DIFFSTAT)
4758                         show_stats(&diffstat, options);
4759                 if (output_format & DIFF_FORMAT_SHORTSTAT)
4760                         show_shortstats(&diffstat, options);
4761                 if (output_format & DIFF_FORMAT_DIRSTAT && dirstat_by_line)
4762                         show_dirstat_by_line(&diffstat, options);
4763                 free_diffstat_info(&diffstat);
4764                 separator++;
4765         }
4766         if ((output_format & DIFF_FORMAT_DIRSTAT) && !dirstat_by_line)
4767                 show_dirstat(options);
4768
4769         if (output_format & DIFF_FORMAT_SUMMARY && !is_summary_empty(q)) {
4770                 for (i = 0; i < q->nr; i++) {
4771                         diff_summary(options, q->queue[i]);
4772                 }
4773                 separator++;
4774         }
4775
4776         if (output_format & DIFF_FORMAT_NO_OUTPUT &&
4777             DIFF_OPT_TST(options, EXIT_WITH_STATUS) &&
4778             DIFF_OPT_TST(options, DIFF_FROM_CONTENTS)) {
4779                 /*
4780                  * run diff_flush_patch for the exit status. setting
4781                  * options->file to /dev/null should be safe, because we
4782                  * aren't supposed to produce any output anyway.
4783                  */
4784                 if (options->close_file)
4785                         fclose(options->file);
4786                 options->file = fopen("/dev/null", "w");
4787                 if (!options->file)
4788                         die_errno("Could not open /dev/null");
4789                 options->close_file = 1;
4790                 for (i = 0; i < q->nr; i++) {
4791                         struct diff_filepair *p = q->queue[i];
4792                         if (check_pair_status(p))
4793                                 diff_flush_patch(p, options);
4794                         if (options->found_changes)
4795                                 break;
4796                 }
4797         }
4798
4799         if (output_format & DIFF_FORMAT_PATCH) {
4800                 if (separator) {
4801                         fprintf(options->file, "%s%c",
4802                                 diff_line_prefix(options),
4803                                 options->line_termination);
4804                         if (options->stat_sep) {
4805                                 /* attach patch instead of inline */
4806                                 fputs(options->stat_sep, options->file);
4807                         }
4808                 }
4809
4810                 for (i = 0; i < q->nr; i++) {
4811                         struct diff_filepair *p = q->queue[i];
4812                         if (check_pair_status(p))
4813                                 diff_flush_patch(p, options);
4814                 }
4815         }
4816
4817         if (output_format & DIFF_FORMAT_CALLBACK)
4818                 options->format_callback(q, options, options->format_callback_data);
4819
4820         for (i = 0; i < q->nr; i++)
4821                 diff_free_filepair(q->queue[i]);
4822 free_queue:
4823         free(q->queue);
4824         DIFF_QUEUE_CLEAR(q);
4825         if (options->close_file)
4826                 fclose(options->file);
4827
4828         /*
4829          * Report the content-level differences with HAS_CHANGES;
4830          * diff_addremove/diff_change does not set the bit when
4831          * DIFF_FROM_CONTENTS is in effect (e.g. with -w).
4832          */
4833         if (DIFF_OPT_TST(options, DIFF_FROM_CONTENTS)) {
4834                 if (options->found_changes)
4835                         DIFF_OPT_SET(options, HAS_CHANGES);
4836                 else
4837                         DIFF_OPT_CLR(options, HAS_CHANGES);
4838         }
4839 }
4840
4841 static int match_filter(const struct diff_options *options, const struct diff_filepair *p)
4842 {
4843         return (((p->status == DIFF_STATUS_MODIFIED) &&
4844                  ((p->score &&
4845                    filter_bit_tst(DIFF_STATUS_FILTER_BROKEN, options)) ||
4846                   (!p->score &&
4847                    filter_bit_tst(DIFF_STATUS_MODIFIED, options)))) ||
4848                 ((p->status != DIFF_STATUS_MODIFIED) &&
4849                  filter_bit_tst(p->status, options)));
4850 }
4851
4852 static void diffcore_apply_filter(struct diff_options *options)
4853 {
4854         int i;
4855         struct diff_queue_struct *q = &diff_queued_diff;
4856         struct diff_queue_struct outq;
4857
4858         DIFF_QUEUE_CLEAR(&outq);
4859
4860         if (!options->filter)
4861                 return;
4862
4863         if (filter_bit_tst(DIFF_STATUS_FILTER_AON, options)) {
4864                 int found;
4865                 for (i = found = 0; !found && i < q->nr; i++) {
4866                         if (match_filter(options, q->queue[i]))
4867                                 found++;
4868                 }
4869                 if (found)
4870                         return;
4871
4872                 /* otherwise we will clear the whole queue
4873                  * by copying the empty outq at the end of this
4874                  * function, but first clear the current entries
4875                  * in the queue.
4876                  */
4877                 for (i = 0; i < q->nr; i++)
4878                         diff_free_filepair(q->queue[i]);
4879         }
4880         else {
4881                 /* Only the matching ones */
4882                 for (i = 0; i < q->nr; i++) {
4883                         struct diff_filepair *p = q->queue[i];
4884                         if (match_filter(options, p))
4885                                 diff_q(&outq, p);
4886                         else
4887                                 diff_free_filepair(p);
4888                 }
4889         }
4890         free(q->queue);
4891         *q = outq;
4892 }
4893
4894 /* Check whether two filespecs with the same mode and size are identical */
4895 static int diff_filespec_is_identical(struct diff_filespec *one,
4896                                       struct diff_filespec *two)
4897 {
4898         if (S_ISGITLINK(one->mode))
4899                 return 0;
4900         if (diff_populate_filespec(one, 0))
4901                 return 0;
4902         if (diff_populate_filespec(two, 0))
4903                 return 0;
4904         return !memcmp(one->data, two->data, one->size);
4905 }
4906
4907 static int diff_filespec_check_stat_unmatch(struct diff_filepair *p)
4908 {
4909         if (p->done_skip_stat_unmatch)
4910                 return p->skip_stat_unmatch_result;
4911
4912         p->done_skip_stat_unmatch = 1;
4913         p->skip_stat_unmatch_result = 0;
4914         /*
4915          * 1. Entries that come from stat info dirtiness
4916          *    always have both sides (iow, not create/delete),
4917          *    one side of the object name is unknown, with
4918          *    the same mode and size.  Keep the ones that
4919          *    do not match these criteria.  They have real
4920          *    differences.
4921          *
4922          * 2. At this point, the file is known to be modified,
4923          *    with the same mode and size, and the object
4924          *    name of one side is unknown.  Need to inspect
4925          *    the identical contents.
4926          */
4927         if (!DIFF_FILE_VALID(p->one) || /* (1) */
4928             !DIFF_FILE_VALID(p->two) ||
4929             (p->one->oid_valid && p->two->oid_valid) ||
4930             (p->one->mode != p->two->mode) ||
4931             diff_populate_filespec(p->one, CHECK_SIZE_ONLY) ||
4932             diff_populate_filespec(p->two, CHECK_SIZE_ONLY) ||
4933             (p->one->size != p->two->size) ||
4934             !diff_filespec_is_identical(p->one, p->two)) /* (2) */
4935                 p->skip_stat_unmatch_result = 1;
4936         return p->skip_stat_unmatch_result;
4937 }
4938
4939 static void diffcore_skip_stat_unmatch(struct diff_options *diffopt)
4940 {
4941         int i;
4942         struct diff_queue_struct *q = &diff_queued_diff;
4943         struct diff_queue_struct outq;
4944         DIFF_QUEUE_CLEAR(&outq);
4945
4946         for (i = 0; i < q->nr; i++) {
4947                 struct diff_filepair *p = q->queue[i];
4948
4949                 if (diff_filespec_check_stat_unmatch(p))
4950                         diff_q(&outq, p);
4951                 else {
4952                         /*
4953                          * The caller can subtract 1 from skip_stat_unmatch
4954                          * to determine how many paths were dirty only
4955                          * due to stat info mismatch.
4956                          */
4957                         if (!DIFF_OPT_TST(diffopt, NO_INDEX))
4958                                 diffopt->skip_stat_unmatch++;
4959                         diff_free_filepair(p);
4960                 }
4961         }
4962         free(q->queue);
4963         *q = outq;
4964 }
4965
4966 static int diffnamecmp(const void *a_, const void *b_)
4967 {
4968         const struct diff_filepair *a = *((const struct diff_filepair **)a_);
4969         const struct diff_filepair *b = *((const struct diff_filepair **)b_);
4970         const char *name_a, *name_b;
4971
4972         name_a = a->one ? a->one->path : a->two->path;
4973         name_b = b->one ? b->one->path : b->two->path;
4974         return strcmp(name_a, name_b);
4975 }
4976
4977 void diffcore_fix_diff_index(struct diff_options *options)
4978 {
4979         struct diff_queue_struct *q = &diff_queued_diff;
4980         QSORT(q->queue, q->nr, diffnamecmp);
4981 }
4982
4983 void diffcore_std(struct diff_options *options)
4984 {
4985         /* NOTE please keep the following in sync with diff_tree_combined() */
4986         if (options->skip_stat_unmatch)
4987                 diffcore_skip_stat_unmatch(options);
4988         if (!options->found_follow) {
4989                 /* See try_to_follow_renames() in tree-diff.c */
4990                 if (options->break_opt != -1)
4991                         diffcore_break(options->break_opt);
4992                 if (options->detect_rename)
4993                         diffcore_rename(options);
4994                 if (options->break_opt != -1)
4995                         diffcore_merge_broken();
4996         }
4997         if (options->pickaxe)
4998                 diffcore_pickaxe(options);
4999         if (options->orderfile)
5000                 diffcore_order(options->orderfile);
5001         if (!options->found_follow)
5002                 /* See try_to_follow_renames() in tree-diff.c */
5003                 diff_resolve_rename_copy();
5004         diffcore_apply_filter(options);
5005
5006         if (diff_queued_diff.nr && !DIFF_OPT_TST(options, DIFF_FROM_CONTENTS))
5007                 DIFF_OPT_SET(options, HAS_CHANGES);
5008         else
5009                 DIFF_OPT_CLR(options, HAS_CHANGES);
5010
5011         options->found_follow = 0;
5012 }
5013
5014 int diff_result_code(struct diff_options *opt, int status)
5015 {
5016         int result = 0;
5017
5018         diff_warn_rename_limit("diff.renameLimit",
5019                                opt->needed_rename_limit,
5020                                opt->degraded_cc_to_c);
5021         if (!DIFF_OPT_TST(opt, EXIT_WITH_STATUS) &&
5022             !(opt->output_format & DIFF_FORMAT_CHECKDIFF))
5023                 return status;
5024         if (DIFF_OPT_TST(opt, EXIT_WITH_STATUS) &&
5025             DIFF_OPT_TST(opt, HAS_CHANGES))
5026                 result |= 01;
5027         if ((opt->output_format & DIFF_FORMAT_CHECKDIFF) &&
5028             DIFF_OPT_TST(opt, CHECK_FAILED))
5029                 result |= 02;
5030         return result;
5031 }
5032
5033 int diff_can_quit_early(struct diff_options *opt)
5034 {
5035         return (DIFF_OPT_TST(opt, QUICK) &&
5036                 !opt->filter &&
5037                 DIFF_OPT_TST(opt, HAS_CHANGES));
5038 }
5039
5040 /*
5041  * Shall changes to this submodule be ignored?
5042  *
5043  * Submodule changes can be configured to be ignored separately for each path,
5044  * but that configuration can be overridden from the command line.
5045  */
5046 static int is_submodule_ignored(const char *path, struct diff_options *options)
5047 {
5048         int ignored = 0;
5049         unsigned orig_flags = options->flags;
5050         if (!DIFF_OPT_TST(options, OVERRIDE_SUBMODULE_CONFIG))
5051                 set_diffopt_flags_from_submodule_config(options, path);
5052         if (DIFF_OPT_TST(options, IGNORE_SUBMODULES))
5053                 ignored = 1;
5054         options->flags = orig_flags;
5055         return ignored;
5056 }
5057
5058 void diff_addremove(struct diff_options *options,
5059                     int addremove, unsigned mode,
5060                     const unsigned char *sha1,
5061                     int sha1_valid,
5062                     const char *concatpath, unsigned dirty_submodule)
5063 {
5064         struct diff_filespec *one, *two;
5065
5066         if (S_ISGITLINK(mode) && is_submodule_ignored(concatpath, options))
5067                 return;
5068
5069         /* This may look odd, but it is a preparation for
5070          * feeding "there are unchanged files which should
5071          * not produce diffs, but when you are doing copy
5072          * detection you would need them, so here they are"
5073          * entries to the diff-core.  They will be prefixed
5074          * with something like '=' or '*' (I haven't decided
5075          * which but should not make any difference).
5076          * Feeding the same new and old to diff_change()
5077          * also has the same effect.
5078          * Before the final output happens, they are pruned after
5079          * merged into rename/copy pairs as appropriate.
5080          */
5081         if (DIFF_OPT_TST(options, REVERSE_DIFF))
5082                 addremove = (addremove == '+' ? '-' :
5083                              addremove == '-' ? '+' : addremove);
5084
5085         if (options->prefix &&
5086             strncmp(concatpath, options->prefix, options->prefix_length))
5087                 return;
5088
5089         one = alloc_filespec(concatpath);
5090         two = alloc_filespec(concatpath);
5091
5092         if (addremove != '+')
5093                 fill_filespec(one, sha1, sha1_valid, mode);
5094         if (addremove != '-') {
5095                 fill_filespec(two, sha1, sha1_valid, mode);
5096                 two->dirty_submodule = dirty_submodule;
5097         }
5098
5099         diff_queue(&diff_queued_diff, one, two);
5100         if (!DIFF_OPT_TST(options, DIFF_FROM_CONTENTS))
5101                 DIFF_OPT_SET(options, HAS_CHANGES);
5102 }
5103
5104 void diff_change(struct diff_options *options,
5105                  unsigned old_mode, unsigned new_mode,
5106                  const unsigned char *old_sha1,
5107                  const unsigned char *new_sha1,
5108                  int old_sha1_valid, int new_sha1_valid,
5109                  const char *concatpath,
5110                  unsigned old_dirty_submodule, unsigned new_dirty_submodule)
5111 {
5112         struct diff_filespec *one, *two;
5113         struct diff_filepair *p;
5114
5115         if (S_ISGITLINK(old_mode) && S_ISGITLINK(new_mode) &&
5116             is_submodule_ignored(concatpath, options))
5117                 return;
5118
5119         if (DIFF_OPT_TST(options, REVERSE_DIFF)) {
5120                 unsigned tmp;
5121                 const unsigned char *tmp_c;
5122                 tmp = old_mode; old_mode = new_mode; new_mode = tmp;
5123                 tmp_c = old_sha1; old_sha1 = new_sha1; new_sha1 = tmp_c;
5124                 tmp = old_sha1_valid; old_sha1_valid = new_sha1_valid;
5125                         new_sha1_valid = tmp;
5126                 tmp = old_dirty_submodule; old_dirty_submodule = new_dirty_submodule;
5127                         new_dirty_submodule = tmp;
5128         }
5129
5130         if (options->prefix &&
5131             strncmp(concatpath, options->prefix, options->prefix_length))
5132                 return;
5133
5134         one = alloc_filespec(concatpath);
5135         two = alloc_filespec(concatpath);
5136         fill_filespec(one, old_sha1, old_sha1_valid, old_mode);
5137         fill_filespec(two, new_sha1, new_sha1_valid, new_mode);
5138         one->dirty_submodule = old_dirty_submodule;
5139         two->dirty_submodule = new_dirty_submodule;
5140         p = diff_queue(&diff_queued_diff, one, two);
5141
5142         if (DIFF_OPT_TST(options, DIFF_FROM_CONTENTS))
5143                 return;
5144
5145         if (DIFF_OPT_TST(options, QUICK) && options->skip_stat_unmatch &&
5146             !diff_filespec_check_stat_unmatch(p))
5147                 return;
5148
5149         DIFF_OPT_SET(options, HAS_CHANGES);
5150 }
5151
5152 struct diff_filepair *diff_unmerge(struct diff_options *options, const char *path)
5153 {
5154         struct diff_filepair *pair;
5155         struct diff_filespec *one, *two;
5156
5157         if (options->prefix &&
5158             strncmp(path, options->prefix, options->prefix_length))
5159                 return NULL;
5160
5161         one = alloc_filespec(path);
5162         two = alloc_filespec(path);
5163         pair = diff_queue(&diff_queued_diff, one, two);
5164         pair->is_unmerged = 1;
5165         return pair;
5166 }
5167
5168 static char *run_textconv(const char *pgm, struct diff_filespec *spec,
5169                 size_t *outsize)
5170 {
5171         struct diff_tempfile *temp;
5172         const char *argv[3];
5173         const char **arg = argv;
5174         struct child_process child = CHILD_PROCESS_INIT;
5175         struct strbuf buf = STRBUF_INIT;
5176         int err = 0;
5177
5178         temp = prepare_temp_file(spec->path, spec);
5179         *arg++ = pgm;
5180         *arg++ = temp->name;
5181         *arg = NULL;
5182
5183         child.use_shell = 1;
5184         child.argv = argv;
5185         child.out = -1;
5186         if (start_command(&child)) {
5187                 remove_tempfile();
5188                 return NULL;
5189         }
5190
5191         if (strbuf_read(&buf, child.out, 0) < 0)
5192                 err = error("error reading from textconv command '%s'", pgm);
5193         close(child.out);
5194
5195         if (finish_command(&child) || err) {
5196                 strbuf_release(&buf);
5197                 remove_tempfile();
5198                 return NULL;
5199         }
5200         remove_tempfile();
5201
5202         return strbuf_detach(&buf, outsize);
5203 }
5204
5205 size_t fill_textconv(struct userdiff_driver *driver,
5206                      struct diff_filespec *df,
5207                      char **outbuf)
5208 {
5209         size_t size;
5210
5211         if (!driver) {
5212                 if (!DIFF_FILE_VALID(df)) {
5213                         *outbuf = "";
5214                         return 0;
5215                 }
5216                 if (diff_populate_filespec(df, 0))
5217                         die("unable to read files to diff");
5218                 *outbuf = df->data;
5219                 return df->size;
5220         }
5221
5222         if (!driver->textconv)
5223                 die("BUG: fill_textconv called with non-textconv driver");
5224
5225         if (driver->textconv_cache && df->oid_valid) {
5226                 *outbuf = notes_cache_get(driver->textconv_cache,
5227                                           df->oid.hash,
5228                                           &size);
5229                 if (*outbuf)
5230                         return size;
5231         }
5232
5233         *outbuf = run_textconv(driver->textconv, df, &size);
5234         if (!*outbuf)
5235                 die("unable to read files to diff");
5236
5237         if (driver->textconv_cache && df->oid_valid) {
5238                 /* ignore errors, as we might be in a readonly repository */
5239                 notes_cache_put(driver->textconv_cache, df->oid.hash, *outbuf,
5240                                 size);
5241                 /*
5242                  * we could save up changes and flush them all at the end,
5243                  * but we would need an extra call after all diffing is done.
5244                  * Since generating a cache entry is the slow path anyway,
5245                  * this extra overhead probably isn't a big deal.
5246                  */
5247                 notes_cache_write(driver->textconv_cache);
5248         }
5249
5250         return size;
5251 }
5252
5253 void setup_diff_pager(struct diff_options *opt)
5254 {
5255         /*
5256          * If the user asked for our exit code, then either they want --quiet
5257          * or --exit-code. We should definitely not bother with a pager in the
5258          * former case, as we will generate no output. Since we still properly
5259          * report our exit code even when a pager is run, we _could_ run a
5260          * pager with --exit-code. But since we have not done so historically,
5261          * and because it is easy to find people oneline advising "git diff
5262          * --exit-code" in hooks and other scripts, we do not do so.
5263          */
5264         if (!DIFF_OPT_TST(opt, EXIT_WITH_STATUS) &&
5265             check_pager_config("diff") != 0)
5266                 setup_pager();
5267 }