Merge branch 'jh/note-trees-record-blobs'
[git] / diff.c
1 /*
2  * Copyright (C) 2005 Junio C Hamano
3  */
4 #include "cache.h"
5 #include "quote.h"
6 #include "diff.h"
7 #include "diffcore.h"
8 #include "delta.h"
9 #include "xdiff-interface.h"
10 #include "color.h"
11 #include "attr.h"
12 #include "run-command.h"
13 #include "utf8.h"
14 #include "userdiff.h"
15 #include "sigchain.h"
16 #include "submodule.h"
17 #include "ll-merge.h"
18 #include "string-list.h"
19
20 #ifdef NO_FAST_WORKING_DIRECTORY
21 #define FAST_WORKING_DIRECTORY 0
22 #else
23 #define FAST_WORKING_DIRECTORY 1
24 #endif
25
26 static int diff_detect_rename_default;
27 static int diff_rename_limit_default = 400;
28 static int diff_suppress_blank_empty;
29 static int diff_use_color_default = -1;
30 static int diff_context_default = 3;
31 static const char *diff_word_regex_cfg;
32 static const char *external_diff_cmd_cfg;
33 static const char *diff_order_file_cfg;
34 int diff_auto_refresh_index = 1;
35 static int diff_mnemonic_prefix;
36 static int diff_no_prefix;
37 static int diff_stat_graph_width;
38 static int diff_dirstat_permille_default = 30;
39 static struct diff_options default_diff_options;
40 static long diff_algorithm;
41
42 static char diff_colors[][COLOR_MAXLEN] = {
43         GIT_COLOR_RESET,
44         GIT_COLOR_NORMAL,       /* PLAIN */
45         GIT_COLOR_BOLD,         /* METAINFO */
46         GIT_COLOR_CYAN,         /* FRAGINFO */
47         GIT_COLOR_RED,          /* OLD */
48         GIT_COLOR_GREEN,        /* NEW */
49         GIT_COLOR_YELLOW,       /* COMMIT */
50         GIT_COLOR_BG_RED,       /* WHITESPACE */
51         GIT_COLOR_NORMAL,       /* FUNCINFO */
52 };
53
54 static int parse_diff_color_slot(const char *var, int ofs)
55 {
56         if (!strcasecmp(var+ofs, "plain"))
57                 return DIFF_PLAIN;
58         if (!strcasecmp(var+ofs, "meta"))
59                 return DIFF_METAINFO;
60         if (!strcasecmp(var+ofs, "frag"))
61                 return DIFF_FRAGINFO;
62         if (!strcasecmp(var+ofs, "old"))
63                 return DIFF_FILE_OLD;
64         if (!strcasecmp(var+ofs, "new"))
65                 return DIFF_FILE_NEW;
66         if (!strcasecmp(var+ofs, "commit"))
67                 return DIFF_COMMIT;
68         if (!strcasecmp(var+ofs, "whitespace"))
69                 return DIFF_WHITESPACE;
70         if (!strcasecmp(var+ofs, "func"))
71                 return DIFF_FUNCINFO;
72         return -1;
73 }
74
75 static int parse_dirstat_params(struct diff_options *options, const char *params_string,
76                                 struct strbuf *errmsg)
77 {
78         char *params_copy = xstrdup(params_string);
79         struct string_list params = STRING_LIST_INIT_NODUP;
80         int ret = 0;
81         int i;
82
83         if (*params_copy)
84                 string_list_split_in_place(&params, params_copy, ',', -1);
85         for (i = 0; i < params.nr; i++) {
86                 const char *p = params.items[i].string;
87                 if (!strcmp(p, "changes")) {
88                         DIFF_OPT_CLR(options, DIRSTAT_BY_LINE);
89                         DIFF_OPT_CLR(options, DIRSTAT_BY_FILE);
90                 } else if (!strcmp(p, "lines")) {
91                         DIFF_OPT_SET(options, DIRSTAT_BY_LINE);
92                         DIFF_OPT_CLR(options, DIRSTAT_BY_FILE);
93                 } else if (!strcmp(p, "files")) {
94                         DIFF_OPT_CLR(options, DIRSTAT_BY_LINE);
95                         DIFF_OPT_SET(options, DIRSTAT_BY_FILE);
96                 } else if (!strcmp(p, "noncumulative")) {
97                         DIFF_OPT_CLR(options, DIRSTAT_CUMULATIVE);
98                 } else if (!strcmp(p, "cumulative")) {
99                         DIFF_OPT_SET(options, DIRSTAT_CUMULATIVE);
100                 } else if (isdigit(*p)) {
101                         char *end;
102                         int permille = strtoul(p, &end, 10) * 10;
103                         if (*end == '.' && isdigit(*++end)) {
104                                 /* only use first digit */
105                                 permille += *end - '0';
106                                 /* .. and ignore any further digits */
107                                 while (isdigit(*++end))
108                                         ; /* nothing */
109                         }
110                         if (!*end)
111                                 options->dirstat_permille = permille;
112                         else {
113                                 strbuf_addf(errmsg, _("  Failed to parse dirstat cut-off percentage '%s'\n"),
114                                             p);
115                                 ret++;
116                         }
117                 } else {
118                         strbuf_addf(errmsg, _("  Unknown dirstat parameter '%s'\n"), p);
119                         ret++;
120                 }
121
122         }
123         string_list_clear(&params, 0);
124         free(params_copy);
125         return ret;
126 }
127
128 static int parse_submodule_params(struct diff_options *options, const char *value)
129 {
130         if (!strcmp(value, "log"))
131                 DIFF_OPT_SET(options, SUBMODULE_LOG);
132         else if (!strcmp(value, "short"))
133                 DIFF_OPT_CLR(options, SUBMODULE_LOG);
134         else
135                 return -1;
136         return 0;
137 }
138
139 static int git_config_rename(const char *var, const char *value)
140 {
141         if (!value)
142                 return DIFF_DETECT_RENAME;
143         if (!strcasecmp(value, "copies") || !strcasecmp(value, "copy"))
144                 return  DIFF_DETECT_COPY;
145         return git_config_bool(var,value) ? DIFF_DETECT_RENAME : 0;
146 }
147
148 long parse_algorithm_value(const char *value)
149 {
150         if (!value)
151                 return -1;
152         else if (!strcasecmp(value, "myers") || !strcasecmp(value, "default"))
153                 return 0;
154         else if (!strcasecmp(value, "minimal"))
155                 return XDF_NEED_MINIMAL;
156         else if (!strcasecmp(value, "patience"))
157                 return XDF_PATIENCE_DIFF;
158         else if (!strcasecmp(value, "histogram"))
159                 return XDF_HISTOGRAM_DIFF;
160         return -1;
161 }
162
163 /*
164  * These are to give UI layer defaults.
165  * The core-level commands such as git-diff-files should
166  * never be affected by the setting of diff.renames
167  * the user happens to have in the configuration file.
168  */
169 int git_diff_ui_config(const char *var, const char *value, void *cb)
170 {
171         if (!strcmp(var, "diff.color") || !strcmp(var, "color.diff")) {
172                 diff_use_color_default = git_config_colorbool(var, value);
173                 return 0;
174         }
175         if (!strcmp(var, "diff.context")) {
176                 diff_context_default = git_config_int(var, value);
177                 if (diff_context_default < 0)
178                         return -1;
179                 return 0;
180         }
181         if (!strcmp(var, "diff.renames")) {
182                 diff_detect_rename_default = git_config_rename(var, value);
183                 return 0;
184         }
185         if (!strcmp(var, "diff.autorefreshindex")) {
186                 diff_auto_refresh_index = git_config_bool(var, value);
187                 return 0;
188         }
189         if (!strcmp(var, "diff.mnemonicprefix")) {
190                 diff_mnemonic_prefix = git_config_bool(var, value);
191                 return 0;
192         }
193         if (!strcmp(var, "diff.noprefix")) {
194                 diff_no_prefix = git_config_bool(var, value);
195                 return 0;
196         }
197         if (!strcmp(var, "diff.statgraphwidth")) {
198                 diff_stat_graph_width = git_config_int(var, value);
199                 return 0;
200         }
201         if (!strcmp(var, "diff.external"))
202                 return git_config_string(&external_diff_cmd_cfg, var, value);
203         if (!strcmp(var, "diff.wordregex"))
204                 return git_config_string(&diff_word_regex_cfg, var, value);
205         if (!strcmp(var, "diff.orderfile"))
206                 return git_config_pathname(&diff_order_file_cfg, var, value);
207
208         if (!strcmp(var, "diff.ignoresubmodules"))
209                 handle_ignore_submodules_arg(&default_diff_options, value);
210
211         if (!strcmp(var, "diff.submodule")) {
212                 if (parse_submodule_params(&default_diff_options, value))
213                         warning(_("Unknown value for 'diff.submodule' config variable: '%s'"),
214                                 value);
215                 return 0;
216         }
217
218         if (!strcmp(var, "diff.algorithm")) {
219                 diff_algorithm = parse_algorithm_value(value);
220                 if (diff_algorithm < 0)
221                         return -1;
222                 return 0;
223         }
224
225         if (git_color_config(var, value, cb) < 0)
226                 return -1;
227
228         return git_diff_basic_config(var, value, cb);
229 }
230
231 int git_diff_basic_config(const char *var, const char *value, void *cb)
232 {
233         if (!strcmp(var, "diff.renamelimit")) {
234                 diff_rename_limit_default = git_config_int(var, value);
235                 return 0;
236         }
237
238         if (userdiff_config(var, value) < 0)
239                 return -1;
240
241         if (starts_with(var, "diff.color.") || starts_with(var, "color.diff.")) {
242                 int slot = parse_diff_color_slot(var, 11);
243                 if (slot < 0)
244                         return 0;
245                 if (!value)
246                         return config_error_nonbool(var);
247                 color_parse(value, var, diff_colors[slot]);
248                 return 0;
249         }
250
251         /* like GNU diff's --suppress-blank-empty option  */
252         if (!strcmp(var, "diff.suppressblankempty") ||
253                         /* for backwards compatibility */
254                         !strcmp(var, "diff.suppress-blank-empty")) {
255                 diff_suppress_blank_empty = git_config_bool(var, value);
256                 return 0;
257         }
258
259         if (!strcmp(var, "diff.dirstat")) {
260                 struct strbuf errmsg = STRBUF_INIT;
261                 default_diff_options.dirstat_permille = diff_dirstat_permille_default;
262                 if (parse_dirstat_params(&default_diff_options, value, &errmsg))
263                         warning(_("Found errors in 'diff.dirstat' config variable:\n%s"),
264                                 errmsg.buf);
265                 strbuf_release(&errmsg);
266                 diff_dirstat_permille_default = default_diff_options.dirstat_permille;
267                 return 0;
268         }
269
270         if (starts_with(var, "submodule."))
271                 return parse_submodule_config_option(var, value);
272
273         return git_default_config(var, value, cb);
274 }
275
276 static char *quote_two(const char *one, const char *two)
277 {
278         int need_one = quote_c_style(one, NULL, NULL, 1);
279         int need_two = quote_c_style(two, NULL, NULL, 1);
280         struct strbuf res = STRBUF_INIT;
281
282         if (need_one + need_two) {
283                 strbuf_addch(&res, '"');
284                 quote_c_style(one, &res, NULL, 1);
285                 quote_c_style(two, &res, NULL, 1);
286                 strbuf_addch(&res, '"');
287         } else {
288                 strbuf_addstr(&res, one);
289                 strbuf_addstr(&res, two);
290         }
291         return strbuf_detach(&res, NULL);
292 }
293
294 static const char *external_diff(void)
295 {
296         static const char *external_diff_cmd = NULL;
297         static int done_preparing = 0;
298
299         if (done_preparing)
300                 return external_diff_cmd;
301         external_diff_cmd = getenv("GIT_EXTERNAL_DIFF");
302         if (!external_diff_cmd)
303                 external_diff_cmd = external_diff_cmd_cfg;
304         done_preparing = 1;
305         return external_diff_cmd;
306 }
307
308 static struct diff_tempfile {
309         const char *name; /* filename external diff should read from */
310         char hex[41];
311         char mode[10];
312         char tmp_path[PATH_MAX];
313 } diff_temp[2];
314
315 typedef unsigned long (*sane_truncate_fn)(char *line, unsigned long len);
316
317 struct emit_callback {
318         int color_diff;
319         unsigned ws_rule;
320         int blank_at_eof_in_preimage;
321         int blank_at_eof_in_postimage;
322         int lno_in_preimage;
323         int lno_in_postimage;
324         sane_truncate_fn truncate;
325         const char **label_path;
326         struct diff_words_data *diff_words;
327         struct diff_options *opt;
328         int *found_changesp;
329         struct strbuf *header;
330 };
331
332 static int count_lines(const char *data, int size)
333 {
334         int count, ch, completely_empty = 1, nl_just_seen = 0;
335         count = 0;
336         while (0 < size--) {
337                 ch = *data++;
338                 if (ch == '\n') {
339                         count++;
340                         nl_just_seen = 1;
341                         completely_empty = 0;
342                 }
343                 else {
344                         nl_just_seen = 0;
345                         completely_empty = 0;
346                 }
347         }
348         if (completely_empty)
349                 return 0;
350         if (!nl_just_seen)
351                 count++; /* no trailing newline */
352         return count;
353 }
354
355 static int fill_mmfile(mmfile_t *mf, struct diff_filespec *one)
356 {
357         if (!DIFF_FILE_VALID(one)) {
358                 mf->ptr = (char *)""; /* does not matter */
359                 mf->size = 0;
360                 return 0;
361         }
362         else if (diff_populate_filespec(one, 0))
363                 return -1;
364
365         mf->ptr = one->data;
366         mf->size = one->size;
367         return 0;
368 }
369
370 /* like fill_mmfile, but only for size, so we can avoid retrieving blob */
371 static unsigned long diff_filespec_size(struct diff_filespec *one)
372 {
373         if (!DIFF_FILE_VALID(one))
374                 return 0;
375         diff_populate_filespec(one, 1);
376         return one->size;
377 }
378
379 static int count_trailing_blank(mmfile_t *mf, unsigned ws_rule)
380 {
381         char *ptr = mf->ptr;
382         long size = mf->size;
383         int cnt = 0;
384
385         if (!size)
386                 return cnt;
387         ptr += size - 1; /* pointing at the very end */
388         if (*ptr != '\n')
389                 ; /* incomplete line */
390         else
391                 ptr--; /* skip the last LF */
392         while (mf->ptr < ptr) {
393                 char *prev_eol;
394                 for (prev_eol = ptr; mf->ptr <= prev_eol; prev_eol--)
395                         if (*prev_eol == '\n')
396                                 break;
397                 if (!ws_blank_line(prev_eol + 1, ptr - prev_eol, ws_rule))
398                         break;
399                 cnt++;
400                 ptr = prev_eol - 1;
401         }
402         return cnt;
403 }
404
405 static void check_blank_at_eof(mmfile_t *mf1, mmfile_t *mf2,
406                                struct emit_callback *ecbdata)
407 {
408         int l1, l2, at;
409         unsigned ws_rule = ecbdata->ws_rule;
410         l1 = count_trailing_blank(mf1, ws_rule);
411         l2 = count_trailing_blank(mf2, ws_rule);
412         if (l2 <= l1) {
413                 ecbdata->blank_at_eof_in_preimage = 0;
414                 ecbdata->blank_at_eof_in_postimage = 0;
415                 return;
416         }
417         at = count_lines(mf1->ptr, mf1->size);
418         ecbdata->blank_at_eof_in_preimage = (at - l1) + 1;
419
420         at = count_lines(mf2->ptr, mf2->size);
421         ecbdata->blank_at_eof_in_postimage = (at - l2) + 1;
422 }
423
424 static void emit_line_0(struct diff_options *o, const char *set, const char *reset,
425                         int first, const char *line, int len)
426 {
427         int has_trailing_newline, has_trailing_carriage_return;
428         int nofirst;
429         FILE *file = o->file;
430
431         fputs(diff_line_prefix(o), file);
432
433         if (len == 0) {
434                 has_trailing_newline = (first == '\n');
435                 has_trailing_carriage_return = (!has_trailing_newline &&
436                                                 (first == '\r'));
437                 nofirst = has_trailing_newline || has_trailing_carriage_return;
438         } else {
439                 has_trailing_newline = (len > 0 && line[len-1] == '\n');
440                 if (has_trailing_newline)
441                         len--;
442                 has_trailing_carriage_return = (len > 0 && line[len-1] == '\r');
443                 if (has_trailing_carriage_return)
444                         len--;
445                 nofirst = 0;
446         }
447
448         if (len || !nofirst) {
449                 fputs(set, file);
450                 if (!nofirst)
451                         fputc(first, file);
452                 fwrite(line, len, 1, file);
453                 fputs(reset, file);
454         }
455         if (has_trailing_carriage_return)
456                 fputc('\r', file);
457         if (has_trailing_newline)
458                 fputc('\n', file);
459 }
460
461 static void emit_line(struct diff_options *o, const char *set, const char *reset,
462                       const char *line, int len)
463 {
464         emit_line_0(o, set, reset, line[0], line+1, len-1);
465 }
466
467 static int new_blank_line_at_eof(struct emit_callback *ecbdata, const char *line, int len)
468 {
469         if (!((ecbdata->ws_rule & WS_BLANK_AT_EOF) &&
470               ecbdata->blank_at_eof_in_preimage &&
471               ecbdata->blank_at_eof_in_postimage &&
472               ecbdata->blank_at_eof_in_preimage <= ecbdata->lno_in_preimage &&
473               ecbdata->blank_at_eof_in_postimage <= ecbdata->lno_in_postimage))
474                 return 0;
475         return ws_blank_line(line, len, ecbdata->ws_rule);
476 }
477
478 static void emit_add_line(const char *reset,
479                           struct emit_callback *ecbdata,
480                           const char *line, int len)
481 {
482         const char *ws = diff_get_color(ecbdata->color_diff, DIFF_WHITESPACE);
483         const char *set = diff_get_color(ecbdata->color_diff, DIFF_FILE_NEW);
484
485         if (!*ws)
486                 emit_line_0(ecbdata->opt, set, reset, '+', line, len);
487         else if (new_blank_line_at_eof(ecbdata, line, len))
488                 /* Blank line at EOF - paint '+' as well */
489                 emit_line_0(ecbdata->opt, ws, reset, '+', line, len);
490         else {
491                 /* Emit just the prefix, then the rest. */
492                 emit_line_0(ecbdata->opt, set, reset, '+', "", 0);
493                 ws_check_emit(line, len, ecbdata->ws_rule,
494                               ecbdata->opt->file, set, reset, ws);
495         }
496 }
497
498 static void emit_hunk_header(struct emit_callback *ecbdata,
499                              const char *line, int len)
500 {
501         const char *plain = diff_get_color(ecbdata->color_diff, DIFF_PLAIN);
502         const char *frag = diff_get_color(ecbdata->color_diff, DIFF_FRAGINFO);
503         const char *func = diff_get_color(ecbdata->color_diff, DIFF_FUNCINFO);
504         const char *reset = diff_get_color(ecbdata->color_diff, DIFF_RESET);
505         static const char atat[2] = { '@', '@' };
506         const char *cp, *ep;
507         struct strbuf msgbuf = STRBUF_INIT;
508         int org_len = len;
509         int i = 1;
510
511         /*
512          * As a hunk header must begin with "@@ -<old>, +<new> @@",
513          * it always is at least 10 bytes long.
514          */
515         if (len < 10 ||
516             memcmp(line, atat, 2) ||
517             !(ep = memmem(line + 2, len - 2, atat, 2))) {
518                 emit_line(ecbdata->opt, plain, reset, line, len);
519                 return;
520         }
521         ep += 2; /* skip over @@ */
522
523         /* The hunk header in fraginfo color */
524         strbuf_add(&msgbuf, frag, strlen(frag));
525         strbuf_add(&msgbuf, line, ep - line);
526         strbuf_add(&msgbuf, reset, strlen(reset));
527
528         /*
529          * trailing "\r\n"
530          */
531         for ( ; i < 3; i++)
532                 if (line[len - i] == '\r' || line[len - i] == '\n')
533                         len--;
534
535         /* blank before the func header */
536         for (cp = ep; ep - line < len; ep++)
537                 if (*ep != ' ' && *ep != '\t')
538                         break;
539         if (ep != cp) {
540                 strbuf_add(&msgbuf, plain, strlen(plain));
541                 strbuf_add(&msgbuf, cp, ep - cp);
542                 strbuf_add(&msgbuf, reset, strlen(reset));
543         }
544
545         if (ep < line + len) {
546                 strbuf_add(&msgbuf, func, strlen(func));
547                 strbuf_add(&msgbuf, ep, line + len - ep);
548                 strbuf_add(&msgbuf, reset, strlen(reset));
549         }
550
551         strbuf_add(&msgbuf, line + len, org_len - len);
552         emit_line(ecbdata->opt, "", "", msgbuf.buf, msgbuf.len);
553         strbuf_release(&msgbuf);
554 }
555
556 static struct diff_tempfile *claim_diff_tempfile(void) {
557         int i;
558         for (i = 0; i < ARRAY_SIZE(diff_temp); i++)
559                 if (!diff_temp[i].name)
560                         return diff_temp + i;
561         die("BUG: diff is failing to clean up its tempfiles");
562 }
563
564 static int remove_tempfile_installed;
565
566 static void remove_tempfile(void)
567 {
568         int i;
569         for (i = 0; i < ARRAY_SIZE(diff_temp); i++) {
570                 if (diff_temp[i].name == diff_temp[i].tmp_path)
571                         unlink_or_warn(diff_temp[i].name);
572                 diff_temp[i].name = NULL;
573         }
574 }
575
576 static void remove_tempfile_on_signal(int signo)
577 {
578         remove_tempfile();
579         sigchain_pop(signo);
580         raise(signo);
581 }
582
583 static void print_line_count(FILE *file, int count)
584 {
585         switch (count) {
586         case 0:
587                 fprintf(file, "0,0");
588                 break;
589         case 1:
590                 fprintf(file, "1");
591                 break;
592         default:
593                 fprintf(file, "1,%d", count);
594                 break;
595         }
596 }
597
598 static void emit_rewrite_lines(struct emit_callback *ecb,
599                                int prefix, const char *data, int size)
600 {
601         const char *endp = NULL;
602         static const char *nneof = " No newline at end of file\n";
603         const char *old = diff_get_color(ecb->color_diff, DIFF_FILE_OLD);
604         const char *reset = diff_get_color(ecb->color_diff, DIFF_RESET);
605
606         while (0 < size) {
607                 int len;
608
609                 endp = memchr(data, '\n', size);
610                 len = endp ? (endp - data + 1) : size;
611                 if (prefix != '+') {
612                         ecb->lno_in_preimage++;
613                         emit_line_0(ecb->opt, old, reset, '-',
614                                     data, len);
615                 } else {
616                         ecb->lno_in_postimage++;
617                         emit_add_line(reset, ecb, data, len);
618                 }
619                 size -= len;
620                 data += len;
621         }
622         if (!endp) {
623                 const char *plain = diff_get_color(ecb->color_diff,
624                                                    DIFF_PLAIN);
625                 putc('\n', ecb->opt->file);
626                 emit_line_0(ecb->opt, plain, reset, '\\',
627                             nneof, strlen(nneof));
628         }
629 }
630
631 static void emit_rewrite_diff(const char *name_a,
632                               const char *name_b,
633                               struct diff_filespec *one,
634                               struct diff_filespec *two,
635                               struct userdiff_driver *textconv_one,
636                               struct userdiff_driver *textconv_two,
637                               struct diff_options *o)
638 {
639         int lc_a, lc_b;
640         const char *name_a_tab, *name_b_tab;
641         const char *metainfo = diff_get_color(o->use_color, DIFF_METAINFO);
642         const char *fraginfo = diff_get_color(o->use_color, DIFF_FRAGINFO);
643         const char *reset = diff_get_color(o->use_color, DIFF_RESET);
644         static struct strbuf a_name = STRBUF_INIT, b_name = STRBUF_INIT;
645         const char *a_prefix, *b_prefix;
646         char *data_one, *data_two;
647         size_t size_one, size_two;
648         struct emit_callback ecbdata;
649         const char *line_prefix = diff_line_prefix(o);
650
651         if (diff_mnemonic_prefix && DIFF_OPT_TST(o, REVERSE_DIFF)) {
652                 a_prefix = o->b_prefix;
653                 b_prefix = o->a_prefix;
654         } else {
655                 a_prefix = o->a_prefix;
656                 b_prefix = o->b_prefix;
657         }
658
659         name_a += (*name_a == '/');
660         name_b += (*name_b == '/');
661         name_a_tab = strchr(name_a, ' ') ? "\t" : "";
662         name_b_tab = strchr(name_b, ' ') ? "\t" : "";
663
664         strbuf_reset(&a_name);
665         strbuf_reset(&b_name);
666         quote_two_c_style(&a_name, a_prefix, name_a, 0);
667         quote_two_c_style(&b_name, b_prefix, name_b, 0);
668
669         size_one = fill_textconv(textconv_one, one, &data_one);
670         size_two = fill_textconv(textconv_two, two, &data_two);
671
672         memset(&ecbdata, 0, sizeof(ecbdata));
673         ecbdata.color_diff = want_color(o->use_color);
674         ecbdata.found_changesp = &o->found_changes;
675         ecbdata.ws_rule = whitespace_rule(name_b);
676         ecbdata.opt = o;
677         if (ecbdata.ws_rule & WS_BLANK_AT_EOF) {
678                 mmfile_t mf1, mf2;
679                 mf1.ptr = (char *)data_one;
680                 mf2.ptr = (char *)data_two;
681                 mf1.size = size_one;
682                 mf2.size = size_two;
683                 check_blank_at_eof(&mf1, &mf2, &ecbdata);
684         }
685         ecbdata.lno_in_preimage = 1;
686         ecbdata.lno_in_postimage = 1;
687
688         lc_a = count_lines(data_one, size_one);
689         lc_b = count_lines(data_two, size_two);
690         fprintf(o->file,
691                 "%s%s--- %s%s%s\n%s%s+++ %s%s%s\n%s%s@@ -",
692                 line_prefix, metainfo, a_name.buf, name_a_tab, reset,
693                 line_prefix, metainfo, b_name.buf, name_b_tab, reset,
694                 line_prefix, fraginfo);
695         if (!o->irreversible_delete)
696                 print_line_count(o->file, lc_a);
697         else
698                 fprintf(o->file, "?,?");
699         fprintf(o->file, " +");
700         print_line_count(o->file, lc_b);
701         fprintf(o->file, " @@%s\n", reset);
702         if (lc_a && !o->irreversible_delete)
703                 emit_rewrite_lines(&ecbdata, '-', data_one, size_one);
704         if (lc_b)
705                 emit_rewrite_lines(&ecbdata, '+', data_two, size_two);
706         if (textconv_one)
707                 free((char *)data_one);
708         if (textconv_two)
709                 free((char *)data_two);
710 }
711
712 struct diff_words_buffer {
713         mmfile_t text;
714         long alloc;
715         struct diff_words_orig {
716                 const char *begin, *end;
717         } *orig;
718         int orig_nr, orig_alloc;
719 };
720
721 static void diff_words_append(char *line, unsigned long len,
722                 struct diff_words_buffer *buffer)
723 {
724         ALLOC_GROW(buffer->text.ptr, buffer->text.size + len, buffer->alloc);
725         line++;
726         len--;
727         memcpy(buffer->text.ptr + buffer->text.size, line, len);
728         buffer->text.size += len;
729         buffer->text.ptr[buffer->text.size] = '\0';
730 }
731
732 struct diff_words_style_elem {
733         const char *prefix;
734         const char *suffix;
735         const char *color; /* NULL; filled in by the setup code if
736                             * color is enabled */
737 };
738
739 struct diff_words_style {
740         enum diff_words_type type;
741         struct diff_words_style_elem new, old, ctx;
742         const char *newline;
743 };
744
745 static struct diff_words_style diff_words_styles[] = {
746         { DIFF_WORDS_PORCELAIN, {"+", "\n"}, {"-", "\n"}, {" ", "\n"}, "~\n" },
747         { DIFF_WORDS_PLAIN, {"{+", "+}"}, {"[-", "-]"}, {"", ""}, "\n" },
748         { DIFF_WORDS_COLOR, {"", ""}, {"", ""}, {"", ""}, "\n" }
749 };
750
751 struct diff_words_data {
752         struct diff_words_buffer minus, plus;
753         const char *current_plus;
754         int last_minus;
755         struct diff_options *opt;
756         regex_t *word_regex;
757         enum diff_words_type type;
758         struct diff_words_style *style;
759 };
760
761 static int fn_out_diff_words_write_helper(FILE *fp,
762                                           struct diff_words_style_elem *st_el,
763                                           const char *newline,
764                                           size_t count, const char *buf,
765                                           const char *line_prefix)
766 {
767         int print = 0;
768
769         while (count) {
770                 char *p = memchr(buf, '\n', count);
771                 if (print)
772                         fputs(line_prefix, fp);
773                 if (p != buf) {
774                         if (st_el->color && fputs(st_el->color, fp) < 0)
775                                 return -1;
776                         if (fputs(st_el->prefix, fp) < 0 ||
777                             fwrite(buf, p ? p - buf : count, 1, fp) != 1 ||
778                             fputs(st_el->suffix, fp) < 0)
779                                 return -1;
780                         if (st_el->color && *st_el->color
781                             && fputs(GIT_COLOR_RESET, fp) < 0)
782                                 return -1;
783                 }
784                 if (!p)
785                         return 0;
786                 if (fputs(newline, fp) < 0)
787                         return -1;
788                 count -= p + 1 - buf;
789                 buf = p + 1;
790                 print = 1;
791         }
792         return 0;
793 }
794
795 /*
796  * '--color-words' algorithm can be described as:
797  *
798  *   1. collect a the minus/plus lines of a diff hunk, divided into
799  *      minus-lines and plus-lines;
800  *
801  *   2. break both minus-lines and plus-lines into words and
802  *      place them into two mmfile_t with one word for each line;
803  *
804  *   3. use xdiff to run diff on the two mmfile_t to get the words level diff;
805  *
806  * And for the common parts of the both file, we output the plus side text.
807  * diff_words->current_plus is used to trace the current position of the plus file
808  * which printed. diff_words->last_minus is used to trace the last minus word
809  * printed.
810  *
811  * For '--graph' to work with '--color-words', we need to output the graph prefix
812  * on each line of color words output. Generally, there are two conditions on
813  * which we should output the prefix.
814  *
815  *   1. diff_words->last_minus == 0 &&
816  *      diff_words->current_plus == diff_words->plus.text.ptr
817  *
818  *      that is: the plus text must start as a new line, and if there is no minus
819  *      word printed, a graph prefix must be printed.
820  *
821  *   2. diff_words->current_plus > diff_words->plus.text.ptr &&
822  *      *(diff_words->current_plus - 1) == '\n'
823  *
824  *      that is: a graph prefix must be printed following a '\n'
825  */
826 static int color_words_output_graph_prefix(struct diff_words_data *diff_words)
827 {
828         if ((diff_words->last_minus == 0 &&
829                 diff_words->current_plus == diff_words->plus.text.ptr) ||
830                 (diff_words->current_plus > diff_words->plus.text.ptr &&
831                 *(diff_words->current_plus - 1) == '\n')) {
832                 return 1;
833         } else {
834                 return 0;
835         }
836 }
837
838 static void fn_out_diff_words_aux(void *priv, char *line, unsigned long len)
839 {
840         struct diff_words_data *diff_words = priv;
841         struct diff_words_style *style = diff_words->style;
842         int minus_first, minus_len, plus_first, plus_len;
843         const char *minus_begin, *minus_end, *plus_begin, *plus_end;
844         struct diff_options *opt = diff_words->opt;
845         const char *line_prefix;
846
847         if (line[0] != '@' || parse_hunk_header(line, len,
848                         &minus_first, &minus_len, &plus_first, &plus_len))
849                 return;
850
851         assert(opt);
852         line_prefix = diff_line_prefix(opt);
853
854         /* POSIX requires that first be decremented by one if len == 0... */
855         if (minus_len) {
856                 minus_begin = diff_words->minus.orig[minus_first].begin;
857                 minus_end =
858                         diff_words->minus.orig[minus_first + minus_len - 1].end;
859         } else
860                 minus_begin = minus_end =
861                         diff_words->minus.orig[minus_first].end;
862
863         if (plus_len) {
864                 plus_begin = diff_words->plus.orig[plus_first].begin;
865                 plus_end = diff_words->plus.orig[plus_first + plus_len - 1].end;
866         } else
867                 plus_begin = plus_end = diff_words->plus.orig[plus_first].end;
868
869         if (color_words_output_graph_prefix(diff_words)) {
870                 fputs(line_prefix, diff_words->opt->file);
871         }
872         if (diff_words->current_plus != plus_begin) {
873                 fn_out_diff_words_write_helper(diff_words->opt->file,
874                                 &style->ctx, style->newline,
875                                 plus_begin - diff_words->current_plus,
876                                 diff_words->current_plus, line_prefix);
877                 if (*(plus_begin - 1) == '\n')
878                         fputs(line_prefix, diff_words->opt->file);
879         }
880         if (minus_begin != minus_end) {
881                 fn_out_diff_words_write_helper(diff_words->opt->file,
882                                 &style->old, style->newline,
883                                 minus_end - minus_begin, minus_begin,
884                                 line_prefix);
885         }
886         if (plus_begin != plus_end) {
887                 fn_out_diff_words_write_helper(diff_words->opt->file,
888                                 &style->new, style->newline,
889                                 plus_end - plus_begin, plus_begin,
890                                 line_prefix);
891         }
892
893         diff_words->current_plus = plus_end;
894         diff_words->last_minus = minus_first;
895 }
896
897 /* This function starts looking at *begin, and returns 0 iff a word was found. */
898 static int find_word_boundaries(mmfile_t *buffer, regex_t *word_regex,
899                 int *begin, int *end)
900 {
901         if (word_regex && *begin < buffer->size) {
902                 regmatch_t match[1];
903                 if (!regexec(word_regex, buffer->ptr + *begin, 1, match, 0)) {
904                         char *p = memchr(buffer->ptr + *begin + match[0].rm_so,
905                                         '\n', match[0].rm_eo - match[0].rm_so);
906                         *end = p ? p - buffer->ptr : match[0].rm_eo + *begin;
907                         *begin += match[0].rm_so;
908                         return *begin >= *end;
909                 }
910                 return -1;
911         }
912
913         /* find the next word */
914         while (*begin < buffer->size && isspace(buffer->ptr[*begin]))
915                 (*begin)++;
916         if (*begin >= buffer->size)
917                 return -1;
918
919         /* find the end of the word */
920         *end = *begin + 1;
921         while (*end < buffer->size && !isspace(buffer->ptr[*end]))
922                 (*end)++;
923
924         return 0;
925 }
926
927 /*
928  * This function splits the words in buffer->text, stores the list with
929  * newline separator into out, and saves the offsets of the original words
930  * in buffer->orig.
931  */
932 static void diff_words_fill(struct diff_words_buffer *buffer, mmfile_t *out,
933                 regex_t *word_regex)
934 {
935         int i, j;
936         long alloc = 0;
937
938         out->size = 0;
939         out->ptr = NULL;
940
941         /* fake an empty "0th" word */
942         ALLOC_GROW(buffer->orig, 1, buffer->orig_alloc);
943         buffer->orig[0].begin = buffer->orig[0].end = buffer->text.ptr;
944         buffer->orig_nr = 1;
945
946         for (i = 0; i < buffer->text.size; i++) {
947                 if (find_word_boundaries(&buffer->text, word_regex, &i, &j))
948                         return;
949
950                 /* store original boundaries */
951                 ALLOC_GROW(buffer->orig, buffer->orig_nr + 1,
952                                 buffer->orig_alloc);
953                 buffer->orig[buffer->orig_nr].begin = buffer->text.ptr + i;
954                 buffer->orig[buffer->orig_nr].end = buffer->text.ptr + j;
955                 buffer->orig_nr++;
956
957                 /* store one word */
958                 ALLOC_GROW(out->ptr, out->size + j - i + 1, alloc);
959                 memcpy(out->ptr + out->size, buffer->text.ptr + i, j - i);
960                 out->ptr[out->size + j - i] = '\n';
961                 out->size += j - i + 1;
962
963                 i = j - 1;
964         }
965 }
966
967 /* this executes the word diff on the accumulated buffers */
968 static void diff_words_show(struct diff_words_data *diff_words)
969 {
970         xpparam_t xpp;
971         xdemitconf_t xecfg;
972         mmfile_t minus, plus;
973         struct diff_words_style *style = diff_words->style;
974
975         struct diff_options *opt = diff_words->opt;
976         const char *line_prefix;
977
978         assert(opt);
979         line_prefix = diff_line_prefix(opt);
980
981         /* special case: only removal */
982         if (!diff_words->plus.text.size) {
983                 fputs(line_prefix, diff_words->opt->file);
984                 fn_out_diff_words_write_helper(diff_words->opt->file,
985                         &style->old, style->newline,
986                         diff_words->minus.text.size,
987                         diff_words->minus.text.ptr, line_prefix);
988                 diff_words->minus.text.size = 0;
989                 return;
990         }
991
992         diff_words->current_plus = diff_words->plus.text.ptr;
993         diff_words->last_minus = 0;
994
995         memset(&xpp, 0, sizeof(xpp));
996         memset(&xecfg, 0, sizeof(xecfg));
997         diff_words_fill(&diff_words->minus, &minus, diff_words->word_regex);
998         diff_words_fill(&diff_words->plus, &plus, diff_words->word_regex);
999         xpp.flags = 0;
1000         /* as only the hunk header will be parsed, we need a 0-context */
1001         xecfg.ctxlen = 0;
1002         xdi_diff_outf(&minus, &plus, fn_out_diff_words_aux, diff_words,
1003                       &xpp, &xecfg);
1004         free(minus.ptr);
1005         free(plus.ptr);
1006         if (diff_words->current_plus != diff_words->plus.text.ptr +
1007                         diff_words->plus.text.size) {
1008                 if (color_words_output_graph_prefix(diff_words))
1009                         fputs(line_prefix, diff_words->opt->file);
1010                 fn_out_diff_words_write_helper(diff_words->opt->file,
1011                         &style->ctx, style->newline,
1012                         diff_words->plus.text.ptr + diff_words->plus.text.size
1013                         - diff_words->current_plus, diff_words->current_plus,
1014                         line_prefix);
1015         }
1016         diff_words->minus.text.size = diff_words->plus.text.size = 0;
1017 }
1018
1019 /* In "color-words" mode, show word-diff of words accumulated in the buffer */
1020 static void diff_words_flush(struct emit_callback *ecbdata)
1021 {
1022         if (ecbdata->diff_words->minus.text.size ||
1023             ecbdata->diff_words->plus.text.size)
1024                 diff_words_show(ecbdata->diff_words);
1025 }
1026
1027 static void diff_filespec_load_driver(struct diff_filespec *one)
1028 {
1029         /* Use already-loaded driver */
1030         if (one->driver)
1031                 return;
1032
1033         if (S_ISREG(one->mode))
1034                 one->driver = userdiff_find_by_path(one->path);
1035
1036         /* Fallback to default settings */
1037         if (!one->driver)
1038                 one->driver = userdiff_find_by_name("default");
1039 }
1040
1041 static const char *userdiff_word_regex(struct diff_filespec *one)
1042 {
1043         diff_filespec_load_driver(one);
1044         return one->driver->word_regex;
1045 }
1046
1047 static void init_diff_words_data(struct emit_callback *ecbdata,
1048                                  struct diff_options *orig_opts,
1049                                  struct diff_filespec *one,
1050                                  struct diff_filespec *two)
1051 {
1052         int i;
1053         struct diff_options *o = xmalloc(sizeof(struct diff_options));
1054         memcpy(o, orig_opts, sizeof(struct diff_options));
1055
1056         ecbdata->diff_words =
1057                 xcalloc(1, sizeof(struct diff_words_data));
1058         ecbdata->diff_words->type = o->word_diff;
1059         ecbdata->diff_words->opt = o;
1060         if (!o->word_regex)
1061                 o->word_regex = userdiff_word_regex(one);
1062         if (!o->word_regex)
1063                 o->word_regex = userdiff_word_regex(two);
1064         if (!o->word_regex)
1065                 o->word_regex = diff_word_regex_cfg;
1066         if (o->word_regex) {
1067                 ecbdata->diff_words->word_regex = (regex_t *)
1068                         xmalloc(sizeof(regex_t));
1069                 if (regcomp(ecbdata->diff_words->word_regex,
1070                             o->word_regex,
1071                             REG_EXTENDED | REG_NEWLINE))
1072                         die ("Invalid regular expression: %s",
1073                              o->word_regex);
1074         }
1075         for (i = 0; i < ARRAY_SIZE(diff_words_styles); i++) {
1076                 if (o->word_diff == diff_words_styles[i].type) {
1077                         ecbdata->diff_words->style =
1078                                 &diff_words_styles[i];
1079                         break;
1080                 }
1081         }
1082         if (want_color(o->use_color)) {
1083                 struct diff_words_style *st = ecbdata->diff_words->style;
1084                 st->old.color = diff_get_color_opt(o, DIFF_FILE_OLD);
1085                 st->new.color = diff_get_color_opt(o, DIFF_FILE_NEW);
1086                 st->ctx.color = diff_get_color_opt(o, DIFF_PLAIN);
1087         }
1088 }
1089
1090 static void free_diff_words_data(struct emit_callback *ecbdata)
1091 {
1092         if (ecbdata->diff_words) {
1093                 diff_words_flush(ecbdata);
1094                 free (ecbdata->diff_words->opt);
1095                 free (ecbdata->diff_words->minus.text.ptr);
1096                 free (ecbdata->diff_words->minus.orig);
1097                 free (ecbdata->diff_words->plus.text.ptr);
1098                 free (ecbdata->diff_words->plus.orig);
1099                 if (ecbdata->diff_words->word_regex) {
1100                         regfree(ecbdata->diff_words->word_regex);
1101                         free(ecbdata->diff_words->word_regex);
1102                 }
1103                 free(ecbdata->diff_words);
1104                 ecbdata->diff_words = NULL;
1105         }
1106 }
1107
1108 const char *diff_get_color(int diff_use_color, enum color_diff ix)
1109 {
1110         if (want_color(diff_use_color))
1111                 return diff_colors[ix];
1112         return "";
1113 }
1114
1115 const char *diff_line_prefix(struct diff_options *opt)
1116 {
1117         struct strbuf *msgbuf;
1118         if (!opt->output_prefix)
1119                 return "";
1120
1121         msgbuf = opt->output_prefix(opt, opt->output_prefix_data);
1122         return msgbuf->buf;
1123 }
1124
1125 static unsigned long sane_truncate_line(struct emit_callback *ecb, char *line, unsigned long len)
1126 {
1127         const char *cp;
1128         unsigned long allot;
1129         size_t l = len;
1130
1131         if (ecb->truncate)
1132                 return ecb->truncate(line, len);
1133         cp = line;
1134         allot = l;
1135         while (0 < l) {
1136                 (void) utf8_width(&cp, &l);
1137                 if (!cp)
1138                         break; /* truncated in the middle? */
1139         }
1140         return allot - l;
1141 }
1142
1143 static void find_lno(const char *line, struct emit_callback *ecbdata)
1144 {
1145         const char *p;
1146         ecbdata->lno_in_preimage = 0;
1147         ecbdata->lno_in_postimage = 0;
1148         p = strchr(line, '-');
1149         if (!p)
1150                 return; /* cannot happen */
1151         ecbdata->lno_in_preimage = strtol(p + 1, NULL, 10);
1152         p = strchr(p, '+');
1153         if (!p)
1154                 return; /* cannot happen */
1155         ecbdata->lno_in_postimage = strtol(p + 1, NULL, 10);
1156 }
1157
1158 static void fn_out_consume(void *priv, char *line, unsigned long len)
1159 {
1160         struct emit_callback *ecbdata = priv;
1161         const char *meta = diff_get_color(ecbdata->color_diff, DIFF_METAINFO);
1162         const char *plain = diff_get_color(ecbdata->color_diff, DIFF_PLAIN);
1163         const char *reset = diff_get_color(ecbdata->color_diff, DIFF_RESET);
1164         struct diff_options *o = ecbdata->opt;
1165         const char *line_prefix = diff_line_prefix(o);
1166
1167         if (ecbdata->header) {
1168                 fprintf(ecbdata->opt->file, "%s", ecbdata->header->buf);
1169                 strbuf_reset(ecbdata->header);
1170                 ecbdata->header = NULL;
1171         }
1172         *(ecbdata->found_changesp) = 1;
1173
1174         if (ecbdata->label_path[0]) {
1175                 const char *name_a_tab, *name_b_tab;
1176
1177                 name_a_tab = strchr(ecbdata->label_path[0], ' ') ? "\t" : "";
1178                 name_b_tab = strchr(ecbdata->label_path[1], ' ') ? "\t" : "";
1179
1180                 fprintf(ecbdata->opt->file, "%s%s--- %s%s%s\n",
1181                         line_prefix, meta, ecbdata->label_path[0], reset, name_a_tab);
1182                 fprintf(ecbdata->opt->file, "%s%s+++ %s%s%s\n",
1183                         line_prefix, meta, ecbdata->label_path[1], reset, name_b_tab);
1184                 ecbdata->label_path[0] = ecbdata->label_path[1] = NULL;
1185         }
1186
1187         if (diff_suppress_blank_empty
1188             && len == 2 && line[0] == ' ' && line[1] == '\n') {
1189                 line[0] = '\n';
1190                 len = 1;
1191         }
1192
1193         if (line[0] == '@') {
1194                 if (ecbdata->diff_words)
1195                         diff_words_flush(ecbdata);
1196                 len = sane_truncate_line(ecbdata, line, len);
1197                 find_lno(line, ecbdata);
1198                 emit_hunk_header(ecbdata, line, len);
1199                 if (line[len-1] != '\n')
1200                         putc('\n', ecbdata->opt->file);
1201                 return;
1202         }
1203
1204         if (len < 1) {
1205                 emit_line(ecbdata->opt, reset, reset, line, len);
1206                 if (ecbdata->diff_words
1207                     && ecbdata->diff_words->type == DIFF_WORDS_PORCELAIN)
1208                         fputs("~\n", ecbdata->opt->file);
1209                 return;
1210         }
1211
1212         if (ecbdata->diff_words) {
1213                 if (line[0] == '-') {
1214                         diff_words_append(line, len,
1215                                           &ecbdata->diff_words->minus);
1216                         return;
1217                 } else if (line[0] == '+') {
1218                         diff_words_append(line, len,
1219                                           &ecbdata->diff_words->plus);
1220                         return;
1221                 } else if (starts_with(line, "\\ ")) {
1222                         /*
1223                          * Eat the "no newline at eof" marker as if we
1224                          * saw a "+" or "-" line with nothing on it,
1225                          * and return without diff_words_flush() to
1226                          * defer processing. If this is the end of
1227                          * preimage, more "+" lines may come after it.
1228                          */
1229                         return;
1230                 }
1231                 diff_words_flush(ecbdata);
1232                 if (ecbdata->diff_words->type == DIFF_WORDS_PORCELAIN) {
1233                         emit_line(ecbdata->opt, plain, reset, line, len);
1234                         fputs("~\n", ecbdata->opt->file);
1235                 } else {
1236                         /*
1237                          * Skip the prefix character, if any.  With
1238                          * diff_suppress_blank_empty, there may be
1239                          * none.
1240                          */
1241                         if (line[0] != '\n') {
1242                               line++;
1243                               len--;
1244                         }
1245                         emit_line(ecbdata->opt, plain, reset, line, len);
1246                 }
1247                 return;
1248         }
1249
1250         if (line[0] != '+') {
1251                 const char *color =
1252                         diff_get_color(ecbdata->color_diff,
1253                                        line[0] == '-' ? DIFF_FILE_OLD : DIFF_PLAIN);
1254                 ecbdata->lno_in_preimage++;
1255                 if (line[0] == ' ')
1256                         ecbdata->lno_in_postimage++;
1257                 emit_line(ecbdata->opt, color, reset, line, len);
1258         } else {
1259                 ecbdata->lno_in_postimage++;
1260                 emit_add_line(reset, ecbdata, line + 1, len - 1);
1261         }
1262 }
1263
1264 static char *pprint_rename(const char *a, const char *b)
1265 {
1266         const char *old = a;
1267         const char *new = b;
1268         struct strbuf name = STRBUF_INIT;
1269         int pfx_length, sfx_length;
1270         int pfx_adjust_for_slash;
1271         int len_a = strlen(a);
1272         int len_b = strlen(b);
1273         int a_midlen, b_midlen;
1274         int qlen_a = quote_c_style(a, NULL, NULL, 0);
1275         int qlen_b = quote_c_style(b, NULL, NULL, 0);
1276
1277         if (qlen_a || qlen_b) {
1278                 quote_c_style(a, &name, NULL, 0);
1279                 strbuf_addstr(&name, " => ");
1280                 quote_c_style(b, &name, NULL, 0);
1281                 return strbuf_detach(&name, NULL);
1282         }
1283
1284         /* Find common prefix */
1285         pfx_length = 0;
1286         while (*old && *new && *old == *new) {
1287                 if (*old == '/')
1288                         pfx_length = old - a + 1;
1289                 old++;
1290                 new++;
1291         }
1292
1293         /* Find common suffix */
1294         old = a + len_a;
1295         new = b + len_b;
1296         sfx_length = 0;
1297         /*
1298          * If there is a common prefix, it must end in a slash.  In
1299          * that case we let this loop run 1 into the prefix to see the
1300          * same slash.
1301          *
1302          * If there is no common prefix, we cannot do this as it would
1303          * underrun the input strings.
1304          */
1305         pfx_adjust_for_slash = (pfx_length ? 1 : 0);
1306         while (a + pfx_length - pfx_adjust_for_slash <= old &&
1307                b + pfx_length - pfx_adjust_for_slash <= new &&
1308                *old == *new) {
1309                 if (*old == '/')
1310                         sfx_length = len_a - (old - a);
1311                 old--;
1312                 new--;
1313         }
1314
1315         /*
1316          * pfx{mid-a => mid-b}sfx
1317          * {pfx-a => pfx-b}sfx
1318          * pfx{sfx-a => sfx-b}
1319          * name-a => name-b
1320          */
1321         a_midlen = len_a - pfx_length - sfx_length;
1322         b_midlen = len_b - pfx_length - sfx_length;
1323         if (a_midlen < 0)
1324                 a_midlen = 0;
1325         if (b_midlen < 0)
1326                 b_midlen = 0;
1327
1328         strbuf_grow(&name, pfx_length + a_midlen + b_midlen + sfx_length + 7);
1329         if (pfx_length + sfx_length) {
1330                 strbuf_add(&name, a, pfx_length);
1331                 strbuf_addch(&name, '{');
1332         }
1333         strbuf_add(&name, a + pfx_length, a_midlen);
1334         strbuf_addstr(&name, " => ");
1335         strbuf_add(&name, b + pfx_length, b_midlen);
1336         if (pfx_length + sfx_length) {
1337                 strbuf_addch(&name, '}');
1338                 strbuf_add(&name, a + len_a - sfx_length, sfx_length);
1339         }
1340         return strbuf_detach(&name, NULL);
1341 }
1342
1343 struct diffstat_t {
1344         int nr;
1345         int alloc;
1346         struct diffstat_file {
1347                 char *from_name;
1348                 char *name;
1349                 char *print_name;
1350                 unsigned is_unmerged:1;
1351                 unsigned is_binary:1;
1352                 unsigned is_renamed:1;
1353                 unsigned is_interesting:1;
1354                 uintmax_t added, deleted;
1355         } **files;
1356 };
1357
1358 static struct diffstat_file *diffstat_add(struct diffstat_t *diffstat,
1359                                           const char *name_a,
1360                                           const char *name_b)
1361 {
1362         struct diffstat_file *x;
1363         x = xcalloc(sizeof (*x), 1);
1364         if (diffstat->nr == diffstat->alloc) {
1365                 diffstat->alloc = alloc_nr(diffstat->alloc);
1366                 diffstat->files = xrealloc(diffstat->files,
1367                                 diffstat->alloc * sizeof(x));
1368         }
1369         diffstat->files[diffstat->nr++] = x;
1370         if (name_b) {
1371                 x->from_name = xstrdup(name_a);
1372                 x->name = xstrdup(name_b);
1373                 x->is_renamed = 1;
1374         }
1375         else {
1376                 x->from_name = NULL;
1377                 x->name = xstrdup(name_a);
1378         }
1379         return x;
1380 }
1381
1382 static void diffstat_consume(void *priv, char *line, unsigned long len)
1383 {
1384         struct diffstat_t *diffstat = priv;
1385         struct diffstat_file *x = diffstat->files[diffstat->nr - 1];
1386
1387         if (line[0] == '+')
1388                 x->added++;
1389         else if (line[0] == '-')
1390                 x->deleted++;
1391 }
1392
1393 const char mime_boundary_leader[] = "------------";
1394
1395 static int scale_linear(int it, int width, int max_change)
1396 {
1397         if (!it)
1398                 return 0;
1399         /*
1400          * make sure that at least one '-' or '+' is printed if
1401          * there is any change to this path. The easiest way is to
1402          * scale linearly as if the alloted width is one column shorter
1403          * than it is, and then add 1 to the result.
1404          */
1405         return 1 + (it * (width - 1) / max_change);
1406 }
1407
1408 static void show_name(FILE *file,
1409                       const char *prefix, const char *name, int len)
1410 {
1411         fprintf(file, " %s%-*s |", prefix, len, name);
1412 }
1413
1414 static void show_graph(FILE *file, char ch, int cnt, const char *set, const char *reset)
1415 {
1416         if (cnt <= 0)
1417                 return;
1418         fprintf(file, "%s", set);
1419         while (cnt--)
1420                 putc(ch, file);
1421         fprintf(file, "%s", reset);
1422 }
1423
1424 static void fill_print_name(struct diffstat_file *file)
1425 {
1426         char *pname;
1427
1428         if (file->print_name)
1429                 return;
1430
1431         if (!file->is_renamed) {
1432                 struct strbuf buf = STRBUF_INIT;
1433                 if (quote_c_style(file->name, &buf, NULL, 0)) {
1434                         pname = strbuf_detach(&buf, NULL);
1435                 } else {
1436                         pname = file->name;
1437                         strbuf_release(&buf);
1438                 }
1439         } else {
1440                 pname = pprint_rename(file->from_name, file->name);
1441         }
1442         file->print_name = pname;
1443 }
1444
1445 int print_stat_summary(FILE *fp, int files, int insertions, int deletions)
1446 {
1447         struct strbuf sb = STRBUF_INIT;
1448         int ret;
1449
1450         if (!files) {
1451                 assert(insertions == 0 && deletions == 0);
1452                 return fprintf(fp, "%s\n", " 0 files changed");
1453         }
1454
1455         strbuf_addf(&sb,
1456                     (files == 1) ? " %d file changed" : " %d files changed",
1457                     files);
1458
1459         /*
1460          * For binary diff, the caller may want to print "x files
1461          * changed" with insertions == 0 && deletions == 0.
1462          *
1463          * Not omitting "0 insertions(+), 0 deletions(-)" in this case
1464          * is probably less confusing (i.e skip over "2 files changed
1465          * but nothing about added/removed lines? Is this a bug in Git?").
1466          */
1467         if (insertions || deletions == 0) {
1468                 /*
1469                  * TRANSLATORS: "+" in (+) is a line addition marker;
1470                  * do not translate it.
1471                  */
1472                 strbuf_addf(&sb,
1473                             (insertions == 1) ? ", %d insertion(+)" : ", %d insertions(+)",
1474                             insertions);
1475         }
1476
1477         if (deletions || insertions == 0) {
1478                 /*
1479                  * TRANSLATORS: "-" in (-) is a line removal marker;
1480                  * do not translate it.
1481                  */
1482                 strbuf_addf(&sb,
1483                             (deletions == 1) ? ", %d deletion(-)" : ", %d deletions(-)",
1484                             deletions);
1485         }
1486         strbuf_addch(&sb, '\n');
1487         ret = fputs(sb.buf, fp);
1488         strbuf_release(&sb);
1489         return ret;
1490 }
1491
1492 static void show_stats(struct diffstat_t *data, struct diff_options *options)
1493 {
1494         int i, len, add, del, adds = 0, dels = 0;
1495         uintmax_t max_change = 0, max_len = 0;
1496         int total_files = data->nr, count;
1497         int width, name_width, graph_width, number_width = 0, bin_width = 0;
1498         const char *reset, *add_c, *del_c;
1499         const char *line_prefix = "";
1500         int extra_shown = 0;
1501
1502         if (data->nr == 0)
1503                 return;
1504
1505         line_prefix = diff_line_prefix(options);
1506         count = options->stat_count ? options->stat_count : data->nr;
1507
1508         reset = diff_get_color_opt(options, DIFF_RESET);
1509         add_c = diff_get_color_opt(options, DIFF_FILE_NEW);
1510         del_c = diff_get_color_opt(options, DIFF_FILE_OLD);
1511
1512         /*
1513          * Find the longest filename and max number of changes
1514          */
1515         for (i = 0; (i < count) && (i < data->nr); i++) {
1516                 struct diffstat_file *file = data->files[i];
1517                 uintmax_t change = file->added + file->deleted;
1518
1519                 if (!file->is_interesting && (change == 0)) {
1520                         count++; /* not shown == room for one more */
1521                         continue;
1522                 }
1523                 fill_print_name(file);
1524                 len = strlen(file->print_name);
1525                 if (max_len < len)
1526                         max_len = len;
1527
1528                 if (file->is_unmerged) {
1529                         /* "Unmerged" is 8 characters */
1530                         bin_width = bin_width < 8 ? 8 : bin_width;
1531                         continue;
1532                 }
1533                 if (file->is_binary) {
1534                         /* "Bin XXX -> YYY bytes" */
1535                         int w = 14 + decimal_width(file->added)
1536                                 + decimal_width(file->deleted);
1537                         bin_width = bin_width < w ? w : bin_width;
1538                         /* Display change counts aligned with "Bin" */
1539                         number_width = 3;
1540                         continue;
1541                 }
1542
1543                 if (max_change < change)
1544                         max_change = change;
1545         }
1546         count = i; /* where we can stop scanning in data->files[] */
1547
1548         /*
1549          * We have width = stat_width or term_columns() columns total.
1550          * We want a maximum of min(max_len, stat_name_width) for the name part.
1551          * We want a maximum of min(max_change, stat_graph_width) for the +- part.
1552          * We also need 1 for " " and 4 + decimal_width(max_change)
1553          * for " | NNNN " and one the empty column at the end, altogether
1554          * 6 + decimal_width(max_change).
1555          *
1556          * If there's not enough space, we will use the smaller of
1557          * stat_name_width (if set) and 5/8*width for the filename,
1558          * and the rest for constant elements + graph part, but no more
1559          * than stat_graph_width for the graph part.
1560          * (5/8 gives 50 for filename and 30 for the constant parts + graph
1561          * for the standard terminal size).
1562          *
1563          * In other words: stat_width limits the maximum width, and
1564          * stat_name_width fixes the maximum width of the filename,
1565          * and is also used to divide available columns if there
1566          * aren't enough.
1567          *
1568          * Binary files are displayed with "Bin XXX -> YYY bytes"
1569          * instead of the change count and graph. This part is treated
1570          * similarly to the graph part, except that it is not
1571          * "scaled". If total width is too small to accommodate the
1572          * guaranteed minimum width of the filename part and the
1573          * separators and this message, this message will "overflow"
1574          * making the line longer than the maximum width.
1575          */
1576
1577         if (options->stat_width == -1)
1578                 width = term_columns() - options->output_prefix_length;
1579         else
1580                 width = options->stat_width ? options->stat_width : 80;
1581         number_width = decimal_width(max_change) > number_width ?
1582                 decimal_width(max_change) : number_width;
1583
1584         if (options->stat_graph_width == -1)
1585                 options->stat_graph_width = diff_stat_graph_width;
1586
1587         /*
1588          * Guarantee 3/8*16==6 for the graph part
1589          * and 5/8*16==10 for the filename part
1590          */
1591         if (width < 16 + 6 + number_width)
1592                 width = 16 + 6 + number_width;
1593
1594         /*
1595          * First assign sizes that are wanted, ignoring available width.
1596          * strlen("Bin XXX -> YYY bytes") == bin_width, and the part
1597          * starting from "XXX" should fit in graph_width.
1598          */
1599         graph_width = max_change + 4 > bin_width ? max_change : bin_width - 4;
1600         if (options->stat_graph_width &&
1601             options->stat_graph_width < graph_width)
1602                 graph_width = options->stat_graph_width;
1603
1604         name_width = (options->stat_name_width > 0 &&
1605                       options->stat_name_width < max_len) ?
1606                 options->stat_name_width : max_len;
1607
1608         /*
1609          * Adjust adjustable widths not to exceed maximum width
1610          */
1611         if (name_width + number_width + 6 + graph_width > width) {
1612                 if (graph_width > width * 3/8 - number_width - 6) {
1613                         graph_width = width * 3/8 - number_width - 6;
1614                         if (graph_width < 6)
1615                                 graph_width = 6;
1616                 }
1617
1618                 if (options->stat_graph_width &&
1619                     graph_width > options->stat_graph_width)
1620                         graph_width = options->stat_graph_width;
1621                 if (name_width > width - number_width - 6 - graph_width)
1622                         name_width = width - number_width - 6 - graph_width;
1623                 else
1624                         graph_width = width - number_width - 6 - name_width;
1625         }
1626
1627         /*
1628          * From here name_width is the width of the name area,
1629          * and graph_width is the width of the graph area.
1630          * max_change is used to scale graph properly.
1631          */
1632         for (i = 0; i < count; i++) {
1633                 const char *prefix = "";
1634                 struct diffstat_file *file = data->files[i];
1635                 char *name = file->print_name;
1636                 uintmax_t added = file->added;
1637                 uintmax_t deleted = file->deleted;
1638                 int name_len;
1639
1640                 if (!file->is_interesting && (added + deleted == 0))
1641                         continue;
1642
1643                 /*
1644                  * "scale" the filename
1645                  */
1646                 len = name_width;
1647                 name_len = strlen(name);
1648                 if (name_width < name_len) {
1649                         char *slash;
1650                         prefix = "...";
1651                         len -= 3;
1652                         name += name_len - len;
1653                         slash = strchr(name, '/');
1654                         if (slash)
1655                                 name = slash;
1656                 }
1657
1658                 if (file->is_binary) {
1659                         fprintf(options->file, "%s", line_prefix);
1660                         show_name(options->file, prefix, name, len);
1661                         fprintf(options->file, " %*s", number_width, "Bin");
1662                         if (!added && !deleted) {
1663                                 putc('\n', options->file);
1664                                 continue;
1665                         }
1666                         fprintf(options->file, " %s%"PRIuMAX"%s",
1667                                 del_c, deleted, reset);
1668                         fprintf(options->file, " -> ");
1669                         fprintf(options->file, "%s%"PRIuMAX"%s",
1670                                 add_c, added, reset);
1671                         fprintf(options->file, " bytes");
1672                         fprintf(options->file, "\n");
1673                         continue;
1674                 }
1675                 else if (file->is_unmerged) {
1676                         fprintf(options->file, "%s", line_prefix);
1677                         show_name(options->file, prefix, name, len);
1678                         fprintf(options->file, " Unmerged\n");
1679                         continue;
1680                 }
1681
1682                 /*
1683                  * scale the add/delete
1684                  */
1685                 add = added;
1686                 del = deleted;
1687
1688                 if (graph_width <= max_change) {
1689                         int total = scale_linear(add + del, graph_width, max_change);
1690                         if (total < 2 && add && del)
1691                                 /* width >= 2 due to the sanity check */
1692                                 total = 2;
1693                         if (add < del) {
1694                                 add = scale_linear(add, graph_width, max_change);
1695                                 del = total - add;
1696                         } else {
1697                                 del = scale_linear(del, graph_width, max_change);
1698                                 add = total - del;
1699                         }
1700                 }
1701                 fprintf(options->file, "%s", line_prefix);
1702                 show_name(options->file, prefix, name, len);
1703                 fprintf(options->file, " %*"PRIuMAX"%s",
1704                         number_width, added + deleted,
1705                         added + deleted ? " " : "");
1706                 show_graph(options->file, '+', add, add_c, reset);
1707                 show_graph(options->file, '-', del, del_c, reset);
1708                 fprintf(options->file, "\n");
1709         }
1710
1711         for (i = 0; i < data->nr; i++) {
1712                 struct diffstat_file *file = data->files[i];
1713                 uintmax_t added = file->added;
1714                 uintmax_t deleted = file->deleted;
1715
1716                 if (file->is_unmerged ||
1717                     (!file->is_interesting && (added + deleted == 0))) {
1718                         total_files--;
1719                         continue;
1720                 }
1721
1722                 if (!file->is_binary) {
1723                         adds += added;
1724                         dels += deleted;
1725                 }
1726                 if (i < count)
1727                         continue;
1728                 if (!extra_shown)
1729                         fprintf(options->file, "%s ...\n", line_prefix);
1730                 extra_shown = 1;
1731         }
1732         fprintf(options->file, "%s", line_prefix);
1733         print_stat_summary(options->file, total_files, adds, dels);
1734 }
1735
1736 static void show_shortstats(struct diffstat_t *data, struct diff_options *options)
1737 {
1738         int i, adds = 0, dels = 0, total_files = data->nr;
1739
1740         if (data->nr == 0)
1741                 return;
1742
1743         for (i = 0; i < data->nr; i++) {
1744                 int added = data->files[i]->added;
1745                 int deleted= data->files[i]->deleted;
1746
1747                 if (data->files[i]->is_unmerged ||
1748                     (!data->files[i]->is_interesting && (added + deleted == 0))) {
1749                         total_files--;
1750                 } else if (!data->files[i]->is_binary) { /* don't count bytes */
1751                         adds += added;
1752                         dels += deleted;
1753                 }
1754         }
1755         fprintf(options->file, "%s", diff_line_prefix(options));
1756         print_stat_summary(options->file, total_files, adds, dels);
1757 }
1758
1759 static void show_numstat(struct diffstat_t *data, struct diff_options *options)
1760 {
1761         int i;
1762
1763         if (data->nr == 0)
1764                 return;
1765
1766         for (i = 0; i < data->nr; i++) {
1767                 struct diffstat_file *file = data->files[i];
1768
1769                 fprintf(options->file, "%s", diff_line_prefix(options));
1770
1771                 if (file->is_binary)
1772                         fprintf(options->file, "-\t-\t");
1773                 else
1774                         fprintf(options->file,
1775                                 "%"PRIuMAX"\t%"PRIuMAX"\t",
1776                                 file->added, file->deleted);
1777                 if (options->line_termination) {
1778                         fill_print_name(file);
1779                         if (!file->is_renamed)
1780                                 write_name_quoted(file->name, options->file,
1781                                                   options->line_termination);
1782                         else {
1783                                 fputs(file->print_name, options->file);
1784                                 putc(options->line_termination, options->file);
1785                         }
1786                 } else {
1787                         if (file->is_renamed) {
1788                                 putc('\0', options->file);
1789                                 write_name_quoted(file->from_name, options->file, '\0');
1790                         }
1791                         write_name_quoted(file->name, options->file, '\0');
1792                 }
1793         }
1794 }
1795
1796 struct dirstat_file {
1797         const char *name;
1798         unsigned long changed;
1799 };
1800
1801 struct dirstat_dir {
1802         struct dirstat_file *files;
1803         int alloc, nr, permille, cumulative;
1804 };
1805
1806 static long gather_dirstat(struct diff_options *opt, struct dirstat_dir *dir,
1807                 unsigned long changed, const char *base, int baselen)
1808 {
1809         unsigned long this_dir = 0;
1810         unsigned int sources = 0;
1811         const char *line_prefix = diff_line_prefix(opt);
1812
1813         while (dir->nr) {
1814                 struct dirstat_file *f = dir->files;
1815                 int namelen = strlen(f->name);
1816                 unsigned long this;
1817                 char *slash;
1818
1819                 if (namelen < baselen)
1820                         break;
1821                 if (memcmp(f->name, base, baselen))
1822                         break;
1823                 slash = strchr(f->name + baselen, '/');
1824                 if (slash) {
1825                         int newbaselen = slash + 1 - f->name;
1826                         this = gather_dirstat(opt, dir, changed, f->name, newbaselen);
1827                         sources++;
1828                 } else {
1829                         this = f->changed;
1830                         dir->files++;
1831                         dir->nr--;
1832                         sources += 2;
1833                 }
1834                 this_dir += this;
1835         }
1836
1837         /*
1838          * We don't report dirstat's for
1839          *  - the top level
1840          *  - or cases where everything came from a single directory
1841          *    under this directory (sources == 1).
1842          */
1843         if (baselen && sources != 1) {
1844                 if (this_dir) {
1845                         int permille = this_dir * 1000 / changed;
1846                         if (permille >= dir->permille) {
1847                                 fprintf(opt->file, "%s%4d.%01d%% %.*s\n", line_prefix,
1848                                         permille / 10, permille % 10, baselen, base);
1849                                 if (!dir->cumulative)
1850                                         return 0;
1851                         }
1852                 }
1853         }
1854         return this_dir;
1855 }
1856
1857 static int dirstat_compare(const void *_a, const void *_b)
1858 {
1859         const struct dirstat_file *a = _a;
1860         const struct dirstat_file *b = _b;
1861         return strcmp(a->name, b->name);
1862 }
1863
1864 static void show_dirstat(struct diff_options *options)
1865 {
1866         int i;
1867         unsigned long changed;
1868         struct dirstat_dir dir;
1869         struct diff_queue_struct *q = &diff_queued_diff;
1870
1871         dir.files = NULL;
1872         dir.alloc = 0;
1873         dir.nr = 0;
1874         dir.permille = options->dirstat_permille;
1875         dir.cumulative = DIFF_OPT_TST(options, DIRSTAT_CUMULATIVE);
1876
1877         changed = 0;
1878         for (i = 0; i < q->nr; i++) {
1879                 struct diff_filepair *p = q->queue[i];
1880                 const char *name;
1881                 unsigned long copied, added, damage;
1882                 int content_changed;
1883
1884                 name = p->two->path ? p->two->path : p->one->path;
1885
1886                 if (p->one->sha1_valid && p->two->sha1_valid)
1887                         content_changed = hashcmp(p->one->sha1, p->two->sha1);
1888                 else
1889                         content_changed = 1;
1890
1891                 if (!content_changed) {
1892                         /*
1893                          * The SHA1 has not changed, so pre-/post-content is
1894                          * identical. We can therefore skip looking at the
1895                          * file contents altogether.
1896                          */
1897                         damage = 0;
1898                         goto found_damage;
1899                 }
1900
1901                 if (DIFF_OPT_TST(options, DIRSTAT_BY_FILE)) {
1902                         /*
1903                          * In --dirstat-by-file mode, we don't really need to
1904                          * look at the actual file contents at all.
1905                          * The fact that the SHA1 changed is enough for us to
1906                          * add this file to the list of results
1907                          * (with each file contributing equal damage).
1908                          */
1909                         damage = 1;
1910                         goto found_damage;
1911                 }
1912
1913                 if (DIFF_FILE_VALID(p->one) && DIFF_FILE_VALID(p->two)) {
1914                         diff_populate_filespec(p->one, 0);
1915                         diff_populate_filespec(p->two, 0);
1916                         diffcore_count_changes(p->one, p->two, NULL, NULL, 0,
1917                                                &copied, &added);
1918                         diff_free_filespec_data(p->one);
1919                         diff_free_filespec_data(p->two);
1920                 } else if (DIFF_FILE_VALID(p->one)) {
1921                         diff_populate_filespec(p->one, 1);
1922                         copied = added = 0;
1923                         diff_free_filespec_data(p->one);
1924                 } else if (DIFF_FILE_VALID(p->two)) {
1925                         diff_populate_filespec(p->two, 1);
1926                         copied = 0;
1927                         added = p->two->size;
1928                         diff_free_filespec_data(p->two);
1929                 } else
1930                         continue;
1931
1932                 /*
1933                  * Original minus copied is the removed material,
1934                  * added is the new material.  They are both damages
1935                  * made to the preimage.
1936                  * If the resulting damage is zero, we know that
1937                  * diffcore_count_changes() considers the two entries to
1938                  * be identical, but since content_changed is true, we
1939                  * know that there must have been _some_ kind of change,
1940                  * so we force all entries to have damage > 0.
1941                  */
1942                 damage = (p->one->size - copied) + added;
1943                 if (!damage)
1944                         damage = 1;
1945
1946 found_damage:
1947                 ALLOC_GROW(dir.files, dir.nr + 1, dir.alloc);
1948                 dir.files[dir.nr].name = name;
1949                 dir.files[dir.nr].changed = damage;
1950                 changed += damage;
1951                 dir.nr++;
1952         }
1953
1954         /* This can happen even with many files, if everything was renames */
1955         if (!changed)
1956                 return;
1957
1958         /* Show all directories with more than x% of the changes */
1959         qsort(dir.files, dir.nr, sizeof(dir.files[0]), dirstat_compare);
1960         gather_dirstat(options, &dir, changed, "", 0);
1961 }
1962
1963 static void show_dirstat_by_line(struct diffstat_t *data, struct diff_options *options)
1964 {
1965         int i;
1966         unsigned long changed;
1967         struct dirstat_dir dir;
1968
1969         if (data->nr == 0)
1970                 return;
1971
1972         dir.files = NULL;
1973         dir.alloc = 0;
1974         dir.nr = 0;
1975         dir.permille = options->dirstat_permille;
1976         dir.cumulative = DIFF_OPT_TST(options, DIRSTAT_CUMULATIVE);
1977
1978         changed = 0;
1979         for (i = 0; i < data->nr; i++) {
1980                 struct diffstat_file *file = data->files[i];
1981                 unsigned long damage = file->added + file->deleted;
1982                 if (file->is_binary)
1983                         /*
1984                          * binary files counts bytes, not lines. Must find some
1985                          * way to normalize binary bytes vs. textual lines.
1986                          * The following heuristic assumes that there are 64
1987                          * bytes per "line".
1988                          * This is stupid and ugly, but very cheap...
1989                          */
1990                         damage = (damage + 63) / 64;
1991                 ALLOC_GROW(dir.files, dir.nr + 1, dir.alloc);
1992                 dir.files[dir.nr].name = file->name;
1993                 dir.files[dir.nr].changed = damage;
1994                 changed += damage;
1995                 dir.nr++;
1996         }
1997
1998         /* This can happen even with many files, if everything was renames */
1999         if (!changed)
2000                 return;
2001
2002         /* Show all directories with more than x% of the changes */
2003         qsort(dir.files, dir.nr, sizeof(dir.files[0]), dirstat_compare);
2004         gather_dirstat(options, &dir, changed, "", 0);
2005 }
2006
2007 static void free_diffstat_info(struct diffstat_t *diffstat)
2008 {
2009         int i;
2010         for (i = 0; i < diffstat->nr; i++) {
2011                 struct diffstat_file *f = diffstat->files[i];
2012                 if (f->name != f->print_name)
2013                         free(f->print_name);
2014                 free(f->name);
2015                 free(f->from_name);
2016                 free(f);
2017         }
2018         free(diffstat->files);
2019 }
2020
2021 struct checkdiff_t {
2022         const char *filename;
2023         int lineno;
2024         int conflict_marker_size;
2025         struct diff_options *o;
2026         unsigned ws_rule;
2027         unsigned status;
2028 };
2029
2030 static int is_conflict_marker(const char *line, int marker_size, unsigned long len)
2031 {
2032         char firstchar;
2033         int cnt;
2034
2035         if (len < marker_size + 1)
2036                 return 0;
2037         firstchar = line[0];
2038         switch (firstchar) {
2039         case '=': case '>': case '<': case '|':
2040                 break;
2041         default:
2042                 return 0;
2043         }
2044         for (cnt = 1; cnt < marker_size; cnt++)
2045                 if (line[cnt] != firstchar)
2046                         return 0;
2047         /* line[1] thru line[marker_size-1] are same as firstchar */
2048         if (len < marker_size + 1 || !isspace(line[marker_size]))
2049                 return 0;
2050         return 1;
2051 }
2052
2053 static void checkdiff_consume(void *priv, char *line, unsigned long len)
2054 {
2055         struct checkdiff_t *data = priv;
2056         int marker_size = data->conflict_marker_size;
2057         const char *ws = diff_get_color(data->o->use_color, DIFF_WHITESPACE);
2058         const char *reset = diff_get_color(data->o->use_color, DIFF_RESET);
2059         const char *set = diff_get_color(data->o->use_color, DIFF_FILE_NEW);
2060         char *err;
2061         const char *line_prefix;
2062
2063         assert(data->o);
2064         line_prefix = diff_line_prefix(data->o);
2065
2066         if (line[0] == '+') {
2067                 unsigned bad;
2068                 data->lineno++;
2069                 if (is_conflict_marker(line + 1, marker_size, len - 1)) {
2070                         data->status |= 1;
2071                         fprintf(data->o->file,
2072                                 "%s%s:%d: leftover conflict marker\n",
2073                                 line_prefix, data->filename, data->lineno);
2074                 }
2075                 bad = ws_check(line + 1, len - 1, data->ws_rule);
2076                 if (!bad)
2077                         return;
2078                 data->status |= bad;
2079                 err = whitespace_error_string(bad);
2080                 fprintf(data->o->file, "%s%s:%d: %s.\n",
2081                         line_prefix, data->filename, data->lineno, err);
2082                 free(err);
2083                 emit_line(data->o, set, reset, line, 1);
2084                 ws_check_emit(line + 1, len - 1, data->ws_rule,
2085                               data->o->file, set, reset, ws);
2086         } else if (line[0] == ' ') {
2087                 data->lineno++;
2088         } else if (line[0] == '@') {
2089                 char *plus = strchr(line, '+');
2090                 if (plus)
2091                         data->lineno = strtol(plus, NULL, 10) - 1;
2092                 else
2093                         die("invalid diff");
2094         }
2095 }
2096
2097 static unsigned char *deflate_it(char *data,
2098                                  unsigned long size,
2099                                  unsigned long *result_size)
2100 {
2101         int bound;
2102         unsigned char *deflated;
2103         git_zstream stream;
2104
2105         memset(&stream, 0, sizeof(stream));
2106         git_deflate_init(&stream, zlib_compression_level);
2107         bound = git_deflate_bound(&stream, size);
2108         deflated = xmalloc(bound);
2109         stream.next_out = deflated;
2110         stream.avail_out = bound;
2111
2112         stream.next_in = (unsigned char *)data;
2113         stream.avail_in = size;
2114         while (git_deflate(&stream, Z_FINISH) == Z_OK)
2115                 ; /* nothing */
2116         git_deflate_end(&stream);
2117         *result_size = stream.total_out;
2118         return deflated;
2119 }
2120
2121 static void emit_binary_diff_body(FILE *file, mmfile_t *one, mmfile_t *two,
2122                                   const char *prefix)
2123 {
2124         void *cp;
2125         void *delta;
2126         void *deflated;
2127         void *data;
2128         unsigned long orig_size;
2129         unsigned long delta_size;
2130         unsigned long deflate_size;
2131         unsigned long data_size;
2132
2133         /* We could do deflated delta, or we could do just deflated two,
2134          * whichever is smaller.
2135          */
2136         delta = NULL;
2137         deflated = deflate_it(two->ptr, two->size, &deflate_size);
2138         if (one->size && two->size) {
2139                 delta = diff_delta(one->ptr, one->size,
2140                                    two->ptr, two->size,
2141                                    &delta_size, deflate_size);
2142                 if (delta) {
2143                         void *to_free = delta;
2144                         orig_size = delta_size;
2145                         delta = deflate_it(delta, delta_size, &delta_size);
2146                         free(to_free);
2147                 }
2148         }
2149
2150         if (delta && delta_size < deflate_size) {
2151                 fprintf(file, "%sdelta %lu\n", prefix, orig_size);
2152                 free(deflated);
2153                 data = delta;
2154                 data_size = delta_size;
2155         }
2156         else {
2157                 fprintf(file, "%sliteral %lu\n", prefix, two->size);
2158                 free(delta);
2159                 data = deflated;
2160                 data_size = deflate_size;
2161         }
2162
2163         /* emit data encoded in base85 */
2164         cp = data;
2165         while (data_size) {
2166                 int bytes = (52 < data_size) ? 52 : data_size;
2167                 char line[70];
2168                 data_size -= bytes;
2169                 if (bytes <= 26)
2170                         line[0] = bytes + 'A' - 1;
2171                 else
2172                         line[0] = bytes - 26 + 'a' - 1;
2173                 encode_85(line + 1, cp, bytes);
2174                 cp = (char *) cp + bytes;
2175                 fprintf(file, "%s", prefix);
2176                 fputs(line, file);
2177                 fputc('\n', file);
2178         }
2179         fprintf(file, "%s\n", prefix);
2180         free(data);
2181 }
2182
2183 static void emit_binary_diff(FILE *file, mmfile_t *one, mmfile_t *two,
2184                              const char *prefix)
2185 {
2186         fprintf(file, "%sGIT binary patch\n", prefix);
2187         emit_binary_diff_body(file, one, two, prefix);
2188         emit_binary_diff_body(file, two, one, prefix);
2189 }
2190
2191 int diff_filespec_is_binary(struct diff_filespec *one)
2192 {
2193         if (one->is_binary == -1) {
2194                 diff_filespec_load_driver(one);
2195                 if (one->driver->binary != -1)
2196                         one->is_binary = one->driver->binary;
2197                 else {
2198                         if (!one->data && DIFF_FILE_VALID(one))
2199                                 diff_populate_filespec(one, 0);
2200                         if (one->data)
2201                                 one->is_binary = buffer_is_binary(one->data,
2202                                                 one->size);
2203                         if (one->is_binary == -1)
2204                                 one->is_binary = 0;
2205                 }
2206         }
2207         return one->is_binary;
2208 }
2209
2210 static const struct userdiff_funcname *diff_funcname_pattern(struct diff_filespec *one)
2211 {
2212         diff_filespec_load_driver(one);
2213         return one->driver->funcname.pattern ? &one->driver->funcname : NULL;
2214 }
2215
2216 void diff_set_mnemonic_prefix(struct diff_options *options, const char *a, const char *b)
2217 {
2218         if (!options->a_prefix)
2219                 options->a_prefix = a;
2220         if (!options->b_prefix)
2221                 options->b_prefix = b;
2222 }
2223
2224 struct userdiff_driver *get_textconv(struct diff_filespec *one)
2225 {
2226         if (!DIFF_FILE_VALID(one))
2227                 return NULL;
2228
2229         diff_filespec_load_driver(one);
2230         return userdiff_get_textconv(one->driver);
2231 }
2232
2233 static void builtin_diff(const char *name_a,
2234                          const char *name_b,
2235                          struct diff_filespec *one,
2236                          struct diff_filespec *two,
2237                          const char *xfrm_msg,
2238                          int must_show_header,
2239                          struct diff_options *o,
2240                          int complete_rewrite)
2241 {
2242         mmfile_t mf1, mf2;
2243         const char *lbl[2];
2244         char *a_one, *b_two;
2245         const char *meta = diff_get_color_opt(o, DIFF_METAINFO);
2246         const char *reset = diff_get_color_opt(o, DIFF_RESET);
2247         const char *a_prefix, *b_prefix;
2248         struct userdiff_driver *textconv_one = NULL;
2249         struct userdiff_driver *textconv_two = NULL;
2250         struct strbuf header = STRBUF_INIT;
2251         const char *line_prefix = diff_line_prefix(o);
2252
2253         if (DIFF_OPT_TST(o, SUBMODULE_LOG) &&
2254                         (!one->mode || S_ISGITLINK(one->mode)) &&
2255                         (!two->mode || S_ISGITLINK(two->mode))) {
2256                 const char *del = diff_get_color_opt(o, DIFF_FILE_OLD);
2257                 const char *add = diff_get_color_opt(o, DIFF_FILE_NEW);
2258                 show_submodule_summary(o->file, one->path ? one->path : two->path,
2259                                 line_prefix,
2260                                 one->sha1, two->sha1, two->dirty_submodule,
2261                                 meta, del, add, reset);
2262                 return;
2263         }
2264
2265         if (DIFF_OPT_TST(o, ALLOW_TEXTCONV)) {
2266                 textconv_one = get_textconv(one);
2267                 textconv_two = get_textconv(two);
2268         }
2269
2270         diff_set_mnemonic_prefix(o, "a/", "b/");
2271         if (DIFF_OPT_TST(o, REVERSE_DIFF)) {
2272                 a_prefix = o->b_prefix;
2273                 b_prefix = o->a_prefix;
2274         } else {
2275                 a_prefix = o->a_prefix;
2276                 b_prefix = o->b_prefix;
2277         }
2278
2279         /* Never use a non-valid filename anywhere if at all possible */
2280         name_a = DIFF_FILE_VALID(one) ? name_a : name_b;
2281         name_b = DIFF_FILE_VALID(two) ? name_b : name_a;
2282
2283         a_one = quote_two(a_prefix, name_a + (*name_a == '/'));
2284         b_two = quote_two(b_prefix, name_b + (*name_b == '/'));
2285         lbl[0] = DIFF_FILE_VALID(one) ? a_one : "/dev/null";
2286         lbl[1] = DIFF_FILE_VALID(two) ? b_two : "/dev/null";
2287         strbuf_addf(&header, "%s%sdiff --git %s %s%s\n", line_prefix, meta, a_one, b_two, reset);
2288         if (lbl[0][0] == '/') {
2289                 /* /dev/null */
2290                 strbuf_addf(&header, "%s%snew file mode %06o%s\n", line_prefix, meta, two->mode, reset);
2291                 if (xfrm_msg)
2292                         strbuf_addstr(&header, xfrm_msg);
2293                 must_show_header = 1;
2294         }
2295         else if (lbl[1][0] == '/') {
2296                 strbuf_addf(&header, "%s%sdeleted file mode %06o%s\n", line_prefix, meta, one->mode, reset);
2297                 if (xfrm_msg)
2298                         strbuf_addstr(&header, xfrm_msg);
2299                 must_show_header = 1;
2300         }
2301         else {
2302                 if (one->mode != two->mode) {
2303                         strbuf_addf(&header, "%s%sold mode %06o%s\n", line_prefix, meta, one->mode, reset);
2304                         strbuf_addf(&header, "%s%snew mode %06o%s\n", line_prefix, meta, two->mode, reset);
2305                         must_show_header = 1;
2306                 }
2307                 if (xfrm_msg)
2308                         strbuf_addstr(&header, xfrm_msg);
2309
2310                 /*
2311                  * we do not run diff between different kind
2312                  * of objects.
2313                  */
2314                 if ((one->mode ^ two->mode) & S_IFMT)
2315                         goto free_ab_and_return;
2316                 if (complete_rewrite &&
2317                     (textconv_one || !diff_filespec_is_binary(one)) &&
2318                     (textconv_two || !diff_filespec_is_binary(two))) {
2319                         fprintf(o->file, "%s", header.buf);
2320                         strbuf_reset(&header);
2321                         emit_rewrite_diff(name_a, name_b, one, two,
2322                                                 textconv_one, textconv_two, o);
2323                         o->found_changes = 1;
2324                         goto free_ab_and_return;
2325                 }
2326         }
2327
2328         if (o->irreversible_delete && lbl[1][0] == '/') {
2329                 fprintf(o->file, "%s", header.buf);
2330                 strbuf_reset(&header);
2331                 goto free_ab_and_return;
2332         } else if (!DIFF_OPT_TST(o, TEXT) &&
2333             ( (!textconv_one && diff_filespec_is_binary(one)) ||
2334               (!textconv_two && diff_filespec_is_binary(two)) )) {
2335                 if (fill_mmfile(&mf1, one) < 0 || fill_mmfile(&mf2, two) < 0)
2336                         die("unable to read files to diff");
2337                 /* Quite common confusing case */
2338                 if (mf1.size == mf2.size &&
2339                     !memcmp(mf1.ptr, mf2.ptr, mf1.size)) {
2340                         if (must_show_header)
2341                                 fprintf(o->file, "%s", header.buf);
2342                         goto free_ab_and_return;
2343                 }
2344                 fprintf(o->file, "%s", header.buf);
2345                 strbuf_reset(&header);
2346                 if (DIFF_OPT_TST(o, BINARY))
2347                         emit_binary_diff(o->file, &mf1, &mf2, line_prefix);
2348                 else
2349                         fprintf(o->file, "%sBinary files %s and %s differ\n",
2350                                 line_prefix, lbl[0], lbl[1]);
2351                 o->found_changes = 1;
2352         } else {
2353                 /* Crazy xdl interfaces.. */
2354                 const char *diffopts = getenv("GIT_DIFF_OPTS");
2355                 xpparam_t xpp;
2356                 xdemitconf_t xecfg;
2357                 struct emit_callback ecbdata;
2358                 const struct userdiff_funcname *pe;
2359
2360                 if (must_show_header) {
2361                         fprintf(o->file, "%s", header.buf);
2362                         strbuf_reset(&header);
2363                 }
2364
2365                 mf1.size = fill_textconv(textconv_one, one, &mf1.ptr);
2366                 mf2.size = fill_textconv(textconv_two, two, &mf2.ptr);
2367
2368                 pe = diff_funcname_pattern(one);
2369                 if (!pe)
2370                         pe = diff_funcname_pattern(two);
2371
2372                 memset(&xpp, 0, sizeof(xpp));
2373                 memset(&xecfg, 0, sizeof(xecfg));
2374                 memset(&ecbdata, 0, sizeof(ecbdata));
2375                 ecbdata.label_path = lbl;
2376                 ecbdata.color_diff = want_color(o->use_color);
2377                 ecbdata.found_changesp = &o->found_changes;
2378                 ecbdata.ws_rule = whitespace_rule(name_b);
2379                 if (ecbdata.ws_rule & WS_BLANK_AT_EOF)
2380                         check_blank_at_eof(&mf1, &mf2, &ecbdata);
2381                 ecbdata.opt = o;
2382                 ecbdata.header = header.len ? &header : NULL;
2383                 xpp.flags = o->xdl_opts;
2384                 xecfg.ctxlen = o->context;
2385                 xecfg.interhunkctxlen = o->interhunkcontext;
2386                 xecfg.flags = XDL_EMIT_FUNCNAMES;
2387                 if (DIFF_OPT_TST(o, FUNCCONTEXT))
2388                         xecfg.flags |= XDL_EMIT_FUNCCONTEXT;
2389                 if (pe)
2390                         xdiff_set_find_func(&xecfg, pe->pattern, pe->cflags);
2391                 if (!diffopts)
2392                         ;
2393                 else if (starts_with(diffopts, "--unified="))
2394                         xecfg.ctxlen = strtoul(diffopts + 10, NULL, 10);
2395                 else if (starts_with(diffopts, "-u"))
2396                         xecfg.ctxlen = strtoul(diffopts + 2, NULL, 10);
2397                 if (o->word_diff)
2398                         init_diff_words_data(&ecbdata, o, one, two);
2399                 xdi_diff_outf(&mf1, &mf2, fn_out_consume, &ecbdata,
2400                               &xpp, &xecfg);
2401                 if (o->word_diff)
2402                         free_diff_words_data(&ecbdata);
2403                 if (textconv_one)
2404                         free(mf1.ptr);
2405                 if (textconv_two)
2406                         free(mf2.ptr);
2407                 xdiff_clear_find_func(&xecfg);
2408         }
2409
2410  free_ab_and_return:
2411         strbuf_release(&header);
2412         diff_free_filespec_data(one);
2413         diff_free_filespec_data(two);
2414         free(a_one);
2415         free(b_two);
2416         return;
2417 }
2418
2419 static void builtin_diffstat(const char *name_a, const char *name_b,
2420                              struct diff_filespec *one,
2421                              struct diff_filespec *two,
2422                              struct diffstat_t *diffstat,
2423                              struct diff_options *o,
2424                              struct diff_filepair *p)
2425 {
2426         mmfile_t mf1, mf2;
2427         struct diffstat_file *data;
2428         int same_contents;
2429         int complete_rewrite = 0;
2430
2431         if (!DIFF_PAIR_UNMERGED(p)) {
2432                 if (p->status == DIFF_STATUS_MODIFIED && p->score)
2433                         complete_rewrite = 1;
2434         }
2435
2436         data = diffstat_add(diffstat, name_a, name_b);
2437         data->is_interesting = p->status != DIFF_STATUS_UNKNOWN;
2438
2439         if (!one || !two) {
2440                 data->is_unmerged = 1;
2441                 return;
2442         }
2443
2444         same_contents = !hashcmp(one->sha1, two->sha1);
2445
2446         if (diff_filespec_is_binary(one) || diff_filespec_is_binary(two)) {
2447                 data->is_binary = 1;
2448                 if (same_contents) {
2449                         data->added = 0;
2450                         data->deleted = 0;
2451                 } else {
2452                         data->added = diff_filespec_size(two);
2453                         data->deleted = diff_filespec_size(one);
2454                 }
2455         }
2456
2457         else if (complete_rewrite) {
2458                 diff_populate_filespec(one, 0);
2459                 diff_populate_filespec(two, 0);
2460                 data->deleted = count_lines(one->data, one->size);
2461                 data->added = count_lines(two->data, two->size);
2462         }
2463
2464         else if (!same_contents) {
2465                 /* Crazy xdl interfaces.. */
2466                 xpparam_t xpp;
2467                 xdemitconf_t xecfg;
2468
2469                 if (fill_mmfile(&mf1, one) < 0 || fill_mmfile(&mf2, two) < 0)
2470                         die("unable to read files to diff");
2471
2472                 memset(&xpp, 0, sizeof(xpp));
2473                 memset(&xecfg, 0, sizeof(xecfg));
2474                 xpp.flags = o->xdl_opts;
2475                 xecfg.ctxlen = o->context;
2476                 xecfg.interhunkctxlen = o->interhunkcontext;
2477                 xdi_diff_outf(&mf1, &mf2, diffstat_consume, diffstat,
2478                               &xpp, &xecfg);
2479         }
2480
2481         diff_free_filespec_data(one);
2482         diff_free_filespec_data(two);
2483 }
2484
2485 static void builtin_checkdiff(const char *name_a, const char *name_b,
2486                               const char *attr_path,
2487                               struct diff_filespec *one,
2488                               struct diff_filespec *two,
2489                               struct diff_options *o)
2490 {
2491         mmfile_t mf1, mf2;
2492         struct checkdiff_t data;
2493
2494         if (!two)
2495                 return;
2496
2497         memset(&data, 0, sizeof(data));
2498         data.filename = name_b ? name_b : name_a;
2499         data.lineno = 0;
2500         data.o = o;
2501         data.ws_rule = whitespace_rule(attr_path);
2502         data.conflict_marker_size = ll_merge_marker_size(attr_path);
2503
2504         if (fill_mmfile(&mf1, one) < 0 || fill_mmfile(&mf2, two) < 0)
2505                 die("unable to read files to diff");
2506
2507         /*
2508          * All the other codepaths check both sides, but not checking
2509          * the "old" side here is deliberate.  We are checking the newly
2510          * introduced changes, and as long as the "new" side is text, we
2511          * can and should check what it introduces.
2512          */
2513         if (diff_filespec_is_binary(two))
2514                 goto free_and_return;
2515         else {
2516                 /* Crazy xdl interfaces.. */
2517                 xpparam_t xpp;
2518                 xdemitconf_t xecfg;
2519
2520                 memset(&xpp, 0, sizeof(xpp));
2521                 memset(&xecfg, 0, sizeof(xecfg));
2522                 xecfg.ctxlen = 1; /* at least one context line */
2523                 xpp.flags = 0;
2524                 xdi_diff_outf(&mf1, &mf2, checkdiff_consume, &data,
2525                               &xpp, &xecfg);
2526
2527                 if (data.ws_rule & WS_BLANK_AT_EOF) {
2528                         struct emit_callback ecbdata;
2529                         int blank_at_eof;
2530
2531                         ecbdata.ws_rule = data.ws_rule;
2532                         check_blank_at_eof(&mf1, &mf2, &ecbdata);
2533                         blank_at_eof = ecbdata.blank_at_eof_in_postimage;
2534
2535                         if (blank_at_eof) {
2536                                 static char *err;
2537                                 if (!err)
2538                                         err = whitespace_error_string(WS_BLANK_AT_EOF);
2539                                 fprintf(o->file, "%s:%d: %s.\n",
2540                                         data.filename, blank_at_eof, err);
2541                                 data.status = 1; /* report errors */
2542                         }
2543                 }
2544         }
2545  free_and_return:
2546         diff_free_filespec_data(one);
2547         diff_free_filespec_data(two);
2548         if (data.status)
2549                 DIFF_OPT_SET(o, CHECK_FAILED);
2550 }
2551
2552 struct diff_filespec *alloc_filespec(const char *path)
2553 {
2554         int namelen = strlen(path);
2555         struct diff_filespec *spec = xmalloc(sizeof(*spec) + namelen + 1);
2556
2557         memset(spec, 0, sizeof(*spec));
2558         spec->path = (char *)(spec + 1);
2559         memcpy(spec->path, path, namelen+1);
2560         spec->count = 1;
2561         spec->is_binary = -1;
2562         return spec;
2563 }
2564
2565 void free_filespec(struct diff_filespec *spec)
2566 {
2567         if (!--spec->count) {
2568                 diff_free_filespec_data(spec);
2569                 free(spec);
2570         }
2571 }
2572
2573 void fill_filespec(struct diff_filespec *spec, const unsigned char *sha1,
2574                    int sha1_valid, unsigned short mode)
2575 {
2576         if (mode) {
2577                 spec->mode = canon_mode(mode);
2578                 hashcpy(spec->sha1, sha1);
2579                 spec->sha1_valid = sha1_valid;
2580         }
2581 }
2582
2583 /*
2584  * Given a name and sha1 pair, if the index tells us the file in
2585  * the work tree has that object contents, return true, so that
2586  * prepare_temp_file() does not have to inflate and extract.
2587  */
2588 static int reuse_worktree_file(const char *name, const unsigned char *sha1, int want_file)
2589 {
2590         const struct cache_entry *ce;
2591         struct stat st;
2592         int pos, len;
2593
2594         /*
2595          * We do not read the cache ourselves here, because the
2596          * benchmark with my previous version that always reads cache
2597          * shows that it makes things worse for diff-tree comparing
2598          * two linux-2.6 kernel trees in an already checked out work
2599          * tree.  This is because most diff-tree comparisons deal with
2600          * only a small number of files, while reading the cache is
2601          * expensive for a large project, and its cost outweighs the
2602          * savings we get by not inflating the object to a temporary
2603          * file.  Practically, this code only helps when we are used
2604          * by diff-cache --cached, which does read the cache before
2605          * calling us.
2606          */
2607         if (!active_cache)
2608                 return 0;
2609
2610         /* We want to avoid the working directory if our caller
2611          * doesn't need the data in a normal file, this system
2612          * is rather slow with its stat/open/mmap/close syscalls,
2613          * and the object is contained in a pack file.  The pack
2614          * is probably already open and will be faster to obtain
2615          * the data through than the working directory.  Loose
2616          * objects however would tend to be slower as they need
2617          * to be individually opened and inflated.
2618          */
2619         if (!FAST_WORKING_DIRECTORY && !want_file && has_sha1_pack(sha1))
2620                 return 0;
2621
2622         len = strlen(name);
2623         pos = cache_name_pos(name, len);
2624         if (pos < 0)
2625                 return 0;
2626         ce = active_cache[pos];
2627
2628         /*
2629          * This is not the sha1 we are looking for, or
2630          * unreusable because it is not a regular file.
2631          */
2632         if (hashcmp(sha1, ce->sha1) || !S_ISREG(ce->ce_mode))
2633                 return 0;
2634
2635         /*
2636          * If ce is marked as "assume unchanged", there is no
2637          * guarantee that work tree matches what we are looking for.
2638          */
2639         if ((ce->ce_flags & CE_VALID) || ce_skip_worktree(ce))
2640                 return 0;
2641
2642         /*
2643          * If ce matches the file in the work tree, we can reuse it.
2644          */
2645         if (ce_uptodate(ce) ||
2646             (!lstat(name, &st) && !ce_match_stat(ce, &st, 0)))
2647                 return 1;
2648
2649         return 0;
2650 }
2651
2652 static int diff_populate_gitlink(struct diff_filespec *s, int size_only)
2653 {
2654         int len;
2655         char *data = xmalloc(100), *dirty = "";
2656
2657         /* Are we looking at the work tree? */
2658         if (s->dirty_submodule)
2659                 dirty = "-dirty";
2660
2661         len = snprintf(data, 100,
2662                        "Subproject commit %s%s\n", sha1_to_hex(s->sha1), dirty);
2663         s->data = data;
2664         s->size = len;
2665         s->should_free = 1;
2666         if (size_only) {
2667                 s->data = NULL;
2668                 free(data);
2669         }
2670         return 0;
2671 }
2672
2673 /*
2674  * While doing rename detection and pickaxe operation, we may need to
2675  * grab the data for the blob (or file) for our own in-core comparison.
2676  * diff_filespec has data and size fields for this purpose.
2677  */
2678 int diff_populate_filespec(struct diff_filespec *s, int size_only)
2679 {
2680         int err = 0;
2681         /*
2682          * demote FAIL to WARN to allow inspecting the situation
2683          * instead of refusing.
2684          */
2685         enum safe_crlf crlf_warn = (safe_crlf == SAFE_CRLF_FAIL
2686                                     ? SAFE_CRLF_WARN
2687                                     : safe_crlf);
2688
2689         if (!DIFF_FILE_VALID(s))
2690                 die("internal error: asking to populate invalid file.");
2691         if (S_ISDIR(s->mode))
2692                 return -1;
2693
2694         if (s->data)
2695                 return 0;
2696
2697         if (size_only && 0 < s->size)
2698                 return 0;
2699
2700         if (S_ISGITLINK(s->mode))
2701                 return diff_populate_gitlink(s, size_only);
2702
2703         if (!s->sha1_valid ||
2704             reuse_worktree_file(s->path, s->sha1, 0)) {
2705                 struct strbuf buf = STRBUF_INIT;
2706                 struct stat st;
2707                 int fd;
2708
2709                 if (lstat(s->path, &st) < 0) {
2710                         if (errno == ENOENT) {
2711                         err_empty:
2712                                 err = -1;
2713                         empty:
2714                                 s->data = (char *)"";
2715                                 s->size = 0;
2716                                 return err;
2717                         }
2718                 }
2719                 s->size = xsize_t(st.st_size);
2720                 if (!s->size)
2721                         goto empty;
2722                 if (S_ISLNK(st.st_mode)) {
2723                         struct strbuf sb = STRBUF_INIT;
2724
2725                         if (strbuf_readlink(&sb, s->path, s->size))
2726                                 goto err_empty;
2727                         s->size = sb.len;
2728                         s->data = strbuf_detach(&sb, NULL);
2729                         s->should_free = 1;
2730                         return 0;
2731                 }
2732                 if (size_only)
2733                         return 0;
2734                 fd = open(s->path, O_RDONLY);
2735                 if (fd < 0)
2736                         goto err_empty;
2737                 s->data = xmmap(NULL, s->size, PROT_READ, MAP_PRIVATE, fd, 0);
2738                 close(fd);
2739                 s->should_munmap = 1;
2740
2741                 /*
2742                  * Convert from working tree format to canonical git format
2743                  */
2744                 if (convert_to_git(s->path, s->data, s->size, &buf, crlf_warn)) {
2745                         size_t size = 0;
2746                         munmap(s->data, s->size);
2747                         s->should_munmap = 0;
2748                         s->data = strbuf_detach(&buf, &size);
2749                         s->size = size;
2750                         s->should_free = 1;
2751                 }
2752         }
2753         else {
2754                 enum object_type type;
2755                 if (size_only) {
2756                         type = sha1_object_info(s->sha1, &s->size);
2757                         if (type < 0)
2758                                 die("unable to read %s", sha1_to_hex(s->sha1));
2759                 } else {
2760                         s->data = read_sha1_file(s->sha1, &type, &s->size);
2761                         if (!s->data)
2762                                 die("unable to read %s", sha1_to_hex(s->sha1));
2763                         s->should_free = 1;
2764                 }
2765         }
2766         return 0;
2767 }
2768
2769 void diff_free_filespec_blob(struct diff_filespec *s)
2770 {
2771         if (s->should_free)
2772                 free(s->data);
2773         else if (s->should_munmap)
2774                 munmap(s->data, s->size);
2775
2776         if (s->should_free || s->should_munmap) {
2777                 s->should_free = s->should_munmap = 0;
2778                 s->data = NULL;
2779         }
2780 }
2781
2782 void diff_free_filespec_data(struct diff_filespec *s)
2783 {
2784         diff_free_filespec_blob(s);
2785         free(s->cnt_data);
2786         s->cnt_data = NULL;
2787 }
2788
2789 static void prep_temp_blob(const char *path, struct diff_tempfile *temp,
2790                            void *blob,
2791                            unsigned long size,
2792                            const unsigned char *sha1,
2793                            int mode)
2794 {
2795         int fd;
2796         struct strbuf buf = STRBUF_INIT;
2797         struct strbuf template = STRBUF_INIT;
2798         char *path_dup = xstrdup(path);
2799         const char *base = basename(path_dup);
2800
2801         /* Generate "XXXXXX_basename.ext" */
2802         strbuf_addstr(&template, "XXXXXX_");
2803         strbuf_addstr(&template, base);
2804
2805         fd = git_mkstemps(temp->tmp_path, PATH_MAX, template.buf,
2806                         strlen(base) + 1);
2807         if (fd < 0)
2808                 die_errno("unable to create temp-file");
2809         if (convert_to_working_tree(path,
2810                         (const char *)blob, (size_t)size, &buf)) {
2811                 blob = buf.buf;
2812                 size = buf.len;
2813         }
2814         if (write_in_full(fd, blob, size) != size)
2815                 die_errno("unable to write temp-file");
2816         close(fd);
2817         temp->name = temp->tmp_path;
2818         strcpy(temp->hex, sha1_to_hex(sha1));
2819         temp->hex[40] = 0;
2820         sprintf(temp->mode, "%06o", mode);
2821         strbuf_release(&buf);
2822         strbuf_release(&template);
2823         free(path_dup);
2824 }
2825
2826 static struct diff_tempfile *prepare_temp_file(const char *name,
2827                 struct diff_filespec *one)
2828 {
2829         struct diff_tempfile *temp = claim_diff_tempfile();
2830
2831         if (!DIFF_FILE_VALID(one)) {
2832         not_a_valid_file:
2833                 /* A '-' entry produces this for file-2, and
2834                  * a '+' entry produces this for file-1.
2835                  */
2836                 temp->name = "/dev/null";
2837                 strcpy(temp->hex, ".");
2838                 strcpy(temp->mode, ".");
2839                 return temp;
2840         }
2841
2842         if (!remove_tempfile_installed) {
2843                 atexit(remove_tempfile);
2844                 sigchain_push_common(remove_tempfile_on_signal);
2845                 remove_tempfile_installed = 1;
2846         }
2847
2848         if (!S_ISGITLINK(one->mode) &&
2849             (!one->sha1_valid ||
2850              reuse_worktree_file(name, one->sha1, 1))) {
2851                 struct stat st;
2852                 if (lstat(name, &st) < 0) {
2853                         if (errno == ENOENT)
2854                                 goto not_a_valid_file;
2855                         die_errno("stat(%s)", name);
2856                 }
2857                 if (S_ISLNK(st.st_mode)) {
2858                         struct strbuf sb = STRBUF_INIT;
2859                         if (strbuf_readlink(&sb, name, st.st_size) < 0)
2860                                 die_errno("readlink(%s)", name);
2861                         prep_temp_blob(name, temp, sb.buf, sb.len,
2862                                        (one->sha1_valid ?
2863                                         one->sha1 : null_sha1),
2864                                        (one->sha1_valid ?
2865                                         one->mode : S_IFLNK));
2866                         strbuf_release(&sb);
2867                 }
2868                 else {
2869                         /* we can borrow from the file in the work tree */
2870                         temp->name = name;
2871                         if (!one->sha1_valid)
2872                                 strcpy(temp->hex, sha1_to_hex(null_sha1));
2873                         else
2874                                 strcpy(temp->hex, sha1_to_hex(one->sha1));
2875                         /* Even though we may sometimes borrow the
2876                          * contents from the work tree, we always want
2877                          * one->mode.  mode is trustworthy even when
2878                          * !(one->sha1_valid), as long as
2879                          * DIFF_FILE_VALID(one).
2880                          */
2881                         sprintf(temp->mode, "%06o", one->mode);
2882                 }
2883                 return temp;
2884         }
2885         else {
2886                 if (diff_populate_filespec(one, 0))
2887                         die("cannot read data blob for %s", one->path);
2888                 prep_temp_blob(name, temp, one->data, one->size,
2889                                one->sha1, one->mode);
2890         }
2891         return temp;
2892 }
2893
2894 /* An external diff command takes:
2895  *
2896  * diff-cmd name infile1 infile1-sha1 infile1-mode \
2897  *               infile2 infile2-sha1 infile2-mode [ rename-to ]
2898  *
2899  */
2900 static void run_external_diff(const char *pgm,
2901                               const char *name,
2902                               const char *other,
2903                               struct diff_filespec *one,
2904                               struct diff_filespec *two,
2905                               const char *xfrm_msg,
2906                               int complete_rewrite,
2907                               struct diff_options *o)
2908 {
2909         const char *spawn_arg[10];
2910         int retval;
2911         const char **arg = &spawn_arg[0];
2912         struct diff_queue_struct *q = &diff_queued_diff;
2913         const char *env[3] = { NULL };
2914         char env_counter[50];
2915         char env_total[50];
2916
2917         if (one && two) {
2918                 struct diff_tempfile *temp_one, *temp_two;
2919                 const char *othername = (other ? other : name);
2920                 temp_one = prepare_temp_file(name, one);
2921                 temp_two = prepare_temp_file(othername, two);
2922                 *arg++ = pgm;
2923                 *arg++ = name;
2924                 *arg++ = temp_one->name;
2925                 *arg++ = temp_one->hex;
2926                 *arg++ = temp_one->mode;
2927                 *arg++ = temp_two->name;
2928                 *arg++ = temp_two->hex;
2929                 *arg++ = temp_two->mode;
2930                 if (other) {
2931                         *arg++ = other;
2932                         *arg++ = xfrm_msg;
2933                 }
2934         } else {
2935                 *arg++ = pgm;
2936                 *arg++ = name;
2937         }
2938         *arg = NULL;
2939         fflush(NULL);
2940
2941         env[0] = env_counter;
2942         snprintf(env_counter, sizeof(env_counter), "GIT_DIFF_PATH_COUNTER=%d",
2943                  ++o->diff_path_counter);
2944         env[1] = env_total;
2945         snprintf(env_total, sizeof(env_total), "GIT_DIFF_PATH_TOTAL=%d", q->nr);
2946
2947         retval = run_command_v_opt_cd_env(spawn_arg, RUN_USING_SHELL, NULL, env);
2948         remove_tempfile();
2949         if (retval) {
2950                 fprintf(stderr, "external diff died, stopping at %s.\n", name);
2951                 exit(1);
2952         }
2953 }
2954
2955 static int similarity_index(struct diff_filepair *p)
2956 {
2957         return p->score * 100 / MAX_SCORE;
2958 }
2959
2960 static void fill_metainfo(struct strbuf *msg,
2961                           const char *name,
2962                           const char *other,
2963                           struct diff_filespec *one,
2964                           struct diff_filespec *two,
2965                           struct diff_options *o,
2966                           struct diff_filepair *p,
2967                           int *must_show_header,
2968                           int use_color)
2969 {
2970         const char *set = diff_get_color(use_color, DIFF_METAINFO);
2971         const char *reset = diff_get_color(use_color, DIFF_RESET);
2972         const char *line_prefix = diff_line_prefix(o);
2973
2974         *must_show_header = 1;
2975         strbuf_init(msg, PATH_MAX * 2 + 300);
2976         switch (p->status) {
2977         case DIFF_STATUS_COPIED:
2978                 strbuf_addf(msg, "%s%ssimilarity index %d%%",
2979                             line_prefix, set, similarity_index(p));
2980                 strbuf_addf(msg, "%s\n%s%scopy from ",
2981                             reset,  line_prefix, set);
2982                 quote_c_style(name, msg, NULL, 0);
2983                 strbuf_addf(msg, "%s\n%s%scopy to ", reset, line_prefix, set);
2984                 quote_c_style(other, msg, NULL, 0);
2985                 strbuf_addf(msg, "%s\n", reset);
2986                 break;
2987         case DIFF_STATUS_RENAMED:
2988                 strbuf_addf(msg, "%s%ssimilarity index %d%%",
2989                             line_prefix, set, similarity_index(p));
2990                 strbuf_addf(msg, "%s\n%s%srename from ",
2991                             reset, line_prefix, set);
2992                 quote_c_style(name, msg, NULL, 0);
2993                 strbuf_addf(msg, "%s\n%s%srename to ",
2994                             reset, line_prefix, set);
2995                 quote_c_style(other, msg, NULL, 0);
2996                 strbuf_addf(msg, "%s\n", reset);
2997                 break;
2998         case DIFF_STATUS_MODIFIED:
2999                 if (p->score) {
3000                         strbuf_addf(msg, "%s%sdissimilarity index %d%%%s\n",
3001                                     line_prefix,
3002                                     set, similarity_index(p), reset);
3003                         break;
3004                 }
3005                 /* fallthru */
3006         default:
3007                 *must_show_header = 0;
3008         }
3009         if (one && two && hashcmp(one->sha1, two->sha1)) {
3010                 int abbrev = DIFF_OPT_TST(o, FULL_INDEX) ? 40 : DEFAULT_ABBREV;
3011
3012                 if (DIFF_OPT_TST(o, BINARY)) {
3013                         mmfile_t mf;
3014                         if ((!fill_mmfile(&mf, one) && diff_filespec_is_binary(one)) ||
3015                             (!fill_mmfile(&mf, two) && diff_filespec_is_binary(two)))
3016                                 abbrev = 40;
3017                 }
3018                 strbuf_addf(msg, "%s%sindex %s..", line_prefix, set,
3019                             find_unique_abbrev(one->sha1, abbrev));
3020                 strbuf_addstr(msg, find_unique_abbrev(two->sha1, abbrev));
3021                 if (one->mode == two->mode)
3022                         strbuf_addf(msg, " %06o", one->mode);
3023                 strbuf_addf(msg, "%s\n", reset);
3024         }
3025 }
3026
3027 static void run_diff_cmd(const char *pgm,
3028                          const char *name,
3029                          const char *other,
3030                          const char *attr_path,
3031                          struct diff_filespec *one,
3032                          struct diff_filespec *two,
3033                          struct strbuf *msg,
3034                          struct diff_options *o,
3035                          struct diff_filepair *p)
3036 {
3037         const char *xfrm_msg = NULL;
3038         int complete_rewrite = (p->status == DIFF_STATUS_MODIFIED) && p->score;
3039         int must_show_header = 0;
3040
3041
3042         if (DIFF_OPT_TST(o, ALLOW_EXTERNAL)) {
3043                 struct userdiff_driver *drv = userdiff_find_by_path(attr_path);
3044                 if (drv && drv->external)
3045                         pgm = drv->external;
3046         }
3047
3048         if (msg) {
3049                 /*
3050                  * don't use colors when the header is intended for an
3051                  * external diff driver
3052                  */
3053                 fill_metainfo(msg, name, other, one, two, o, p,
3054                               &must_show_header,
3055                               want_color(o->use_color) && !pgm);
3056                 xfrm_msg = msg->len ? msg->buf : NULL;
3057         }
3058
3059         if (pgm) {
3060                 run_external_diff(pgm, name, other, one, two, xfrm_msg,
3061                                   complete_rewrite, o);
3062                 return;
3063         }
3064         if (one && two)
3065                 builtin_diff(name, other ? other : name,
3066                              one, two, xfrm_msg, must_show_header,
3067                              o, complete_rewrite);
3068         else
3069                 fprintf(o->file, "* Unmerged path %s\n", name);
3070 }
3071
3072 static void diff_fill_sha1_info(struct diff_filespec *one)
3073 {
3074         if (DIFF_FILE_VALID(one)) {
3075                 if (!one->sha1_valid) {
3076                         struct stat st;
3077                         if (one->is_stdin) {
3078                                 hashcpy(one->sha1, null_sha1);
3079                                 return;
3080                         }
3081                         if (lstat(one->path, &st) < 0)
3082                                 die_errno("stat '%s'", one->path);
3083                         if (index_path(one->sha1, one->path, &st, 0))
3084                                 die("cannot hash %s", one->path);
3085                 }
3086         }
3087         else
3088                 hashclr(one->sha1);
3089 }
3090
3091 static void strip_prefix(int prefix_length, const char **namep, const char **otherp)
3092 {
3093         /* Strip the prefix but do not molest /dev/null and absolute paths */
3094         if (*namep && **namep != '/') {
3095                 *namep += prefix_length;
3096                 if (**namep == '/')
3097                         ++*namep;
3098         }
3099         if (*otherp && **otherp != '/') {
3100                 *otherp += prefix_length;
3101                 if (**otherp == '/')
3102                         ++*otherp;
3103         }
3104 }
3105
3106 static void run_diff(struct diff_filepair *p, struct diff_options *o)
3107 {
3108         const char *pgm = external_diff();
3109         struct strbuf msg;
3110         struct diff_filespec *one = p->one;
3111         struct diff_filespec *two = p->two;
3112         const char *name;
3113         const char *other;
3114         const char *attr_path;
3115
3116         name  = p->one->path;
3117         other = (strcmp(name, p->two->path) ? p->two->path : NULL);
3118         attr_path = name;
3119         if (o->prefix_length)
3120                 strip_prefix(o->prefix_length, &name, &other);
3121
3122         if (!DIFF_OPT_TST(o, ALLOW_EXTERNAL))
3123                 pgm = NULL;
3124
3125         if (DIFF_PAIR_UNMERGED(p)) {
3126                 run_diff_cmd(pgm, name, NULL, attr_path,
3127                              NULL, NULL, NULL, o, p);
3128                 return;
3129         }
3130
3131         diff_fill_sha1_info(one);
3132         diff_fill_sha1_info(two);
3133
3134         if (!pgm &&
3135             DIFF_FILE_VALID(one) && DIFF_FILE_VALID(two) &&
3136             (S_IFMT & one->mode) != (S_IFMT & two->mode)) {
3137                 /*
3138                  * a filepair that changes between file and symlink
3139                  * needs to be split into deletion and creation.
3140                  */
3141                 struct diff_filespec *null = alloc_filespec(two->path);
3142                 run_diff_cmd(NULL, name, other, attr_path,
3143                              one, null, &msg, o, p);
3144                 free(null);
3145                 strbuf_release(&msg);
3146
3147                 null = alloc_filespec(one->path);
3148                 run_diff_cmd(NULL, name, other, attr_path,
3149                              null, two, &msg, o, p);
3150                 free(null);
3151         }
3152         else
3153                 run_diff_cmd(pgm, name, other, attr_path,
3154                              one, two, &msg, o, p);
3155
3156         strbuf_release(&msg);
3157 }
3158
3159 static void run_diffstat(struct diff_filepair *p, struct diff_options *o,
3160                          struct diffstat_t *diffstat)
3161 {
3162         const char *name;
3163         const char *other;
3164
3165         if (DIFF_PAIR_UNMERGED(p)) {
3166                 /* unmerged */
3167                 builtin_diffstat(p->one->path, NULL, NULL, NULL, diffstat, o, p);
3168                 return;
3169         }
3170
3171         name = p->one->path;
3172         other = (strcmp(name, p->two->path) ? p->two->path : NULL);
3173
3174         if (o->prefix_length)
3175                 strip_prefix(o->prefix_length, &name, &other);
3176
3177         diff_fill_sha1_info(p->one);
3178         diff_fill_sha1_info(p->two);
3179
3180         builtin_diffstat(name, other, p->one, p->two, diffstat, o, p);
3181 }
3182
3183 static void run_checkdiff(struct diff_filepair *p, struct diff_options *o)
3184 {
3185         const char *name;
3186         const char *other;
3187         const char *attr_path;
3188
3189         if (DIFF_PAIR_UNMERGED(p)) {
3190                 /* unmerged */
3191                 return;
3192         }
3193
3194         name = p->one->path;
3195         other = (strcmp(name, p->two->path) ? p->two->path : NULL);
3196         attr_path = other ? other : name;
3197
3198         if (o->prefix_length)
3199                 strip_prefix(o->prefix_length, &name, &other);
3200
3201         diff_fill_sha1_info(p->one);
3202         diff_fill_sha1_info(p->two);
3203
3204         builtin_checkdiff(name, other, attr_path, p->one, p->two, o);
3205 }
3206
3207 void diff_setup(struct diff_options *options)
3208 {
3209         memcpy(options, &default_diff_options, sizeof(*options));
3210
3211         options->file = stdout;
3212
3213         options->line_termination = '\n';
3214         options->break_opt = -1;
3215         options->rename_limit = -1;
3216         options->dirstat_permille = diff_dirstat_permille_default;
3217         options->context = diff_context_default;
3218         DIFF_OPT_SET(options, RENAME_EMPTY);
3219
3220         options->change = diff_change;
3221         options->add_remove = diff_addremove;
3222         options->use_color = diff_use_color_default;
3223         options->detect_rename = diff_detect_rename_default;
3224         options->xdl_opts |= diff_algorithm;
3225
3226         options->orderfile = diff_order_file_cfg;
3227
3228         if (diff_no_prefix) {
3229                 options->a_prefix = options->b_prefix = "";
3230         } else if (!diff_mnemonic_prefix) {
3231                 options->a_prefix = "a/";
3232                 options->b_prefix = "b/";
3233         }
3234 }
3235
3236 void diff_setup_done(struct diff_options *options)
3237 {
3238         int count = 0;
3239
3240         if (options->set_default)
3241                 options->set_default(options);
3242
3243         if (options->output_format & DIFF_FORMAT_NAME)
3244                 count++;
3245         if (options->output_format & DIFF_FORMAT_NAME_STATUS)
3246                 count++;
3247         if (options->output_format & DIFF_FORMAT_CHECKDIFF)
3248                 count++;
3249         if (options->output_format & DIFF_FORMAT_NO_OUTPUT)
3250                 count++;
3251         if (count > 1)
3252                 die("--name-only, --name-status, --check and -s are mutually exclusive");
3253
3254         /*
3255          * Most of the time we can say "there are changes"
3256          * only by checking if there are changed paths, but
3257          * --ignore-whitespace* options force us to look
3258          * inside contents.
3259          */
3260
3261         if (DIFF_XDL_TST(options, IGNORE_WHITESPACE) ||
3262             DIFF_XDL_TST(options, IGNORE_WHITESPACE_CHANGE) ||
3263             DIFF_XDL_TST(options, IGNORE_WHITESPACE_AT_EOL))
3264                 DIFF_OPT_SET(options, DIFF_FROM_CONTENTS);
3265         else
3266                 DIFF_OPT_CLR(options, DIFF_FROM_CONTENTS);
3267
3268         if (DIFF_OPT_TST(options, FIND_COPIES_HARDER))
3269                 options->detect_rename = DIFF_DETECT_COPY;
3270
3271         if (!DIFF_OPT_TST(options, RELATIVE_NAME))
3272                 options->prefix = NULL;
3273         if (options->prefix)
3274                 options->prefix_length = strlen(options->prefix);
3275         else
3276                 options->prefix_length = 0;
3277
3278         if (options->output_format & (DIFF_FORMAT_NAME |
3279                                       DIFF_FORMAT_NAME_STATUS |
3280                                       DIFF_FORMAT_CHECKDIFF |
3281                                       DIFF_FORMAT_NO_OUTPUT))
3282                 options->output_format &= ~(DIFF_FORMAT_RAW |
3283                                             DIFF_FORMAT_NUMSTAT |
3284                                             DIFF_FORMAT_DIFFSTAT |
3285                                             DIFF_FORMAT_SHORTSTAT |
3286                                             DIFF_FORMAT_DIRSTAT |
3287                                             DIFF_FORMAT_SUMMARY |
3288                                             DIFF_FORMAT_PATCH);
3289
3290         /*
3291          * These cases always need recursive; we do not drop caller-supplied
3292          * recursive bits for other formats here.
3293          */
3294         if (options->output_format & (DIFF_FORMAT_PATCH |
3295                                       DIFF_FORMAT_NUMSTAT |
3296                                       DIFF_FORMAT_DIFFSTAT |
3297                                       DIFF_FORMAT_SHORTSTAT |
3298                                       DIFF_FORMAT_DIRSTAT |
3299                                       DIFF_FORMAT_SUMMARY |
3300                                       DIFF_FORMAT_CHECKDIFF))
3301                 DIFF_OPT_SET(options, RECURSIVE);
3302         /*
3303          * Also pickaxe would not work very well if you do not say recursive
3304          */
3305         if (options->pickaxe)
3306                 DIFF_OPT_SET(options, RECURSIVE);
3307         /*
3308          * When patches are generated, submodules diffed against the work tree
3309          * must be checked for dirtiness too so it can be shown in the output
3310          */
3311         if (options->output_format & DIFF_FORMAT_PATCH)
3312                 DIFF_OPT_SET(options, DIRTY_SUBMODULES);
3313
3314         if (options->detect_rename && options->rename_limit < 0)
3315                 options->rename_limit = diff_rename_limit_default;
3316         if (options->setup & DIFF_SETUP_USE_CACHE) {
3317                 if (!active_cache)
3318                         /* read-cache does not die even when it fails
3319                          * so it is safe for us to do this here.  Also
3320                          * it does not smudge active_cache or active_nr
3321                          * when it fails, so we do not have to worry about
3322                          * cleaning it up ourselves either.
3323                          */
3324                         read_cache();
3325         }
3326         if (options->abbrev <= 0 || 40 < options->abbrev)
3327                 options->abbrev = 40; /* full */
3328
3329         /*
3330          * It does not make sense to show the first hit we happened
3331          * to have found.  It does not make sense not to return with
3332          * exit code in such a case either.
3333          */
3334         if (DIFF_OPT_TST(options, QUICK)) {
3335                 options->output_format = DIFF_FORMAT_NO_OUTPUT;
3336                 DIFF_OPT_SET(options, EXIT_WITH_STATUS);
3337         }
3338
3339         options->diff_path_counter = 0;
3340 }
3341
3342 static int opt_arg(const char *arg, int arg_short, const char *arg_long, int *val)
3343 {
3344         char c, *eq;
3345         int len;
3346
3347         if (*arg != '-')
3348                 return 0;
3349         c = *++arg;
3350         if (!c)
3351                 return 0;
3352         if (c == arg_short) {
3353                 c = *++arg;
3354                 if (!c)
3355                         return 1;
3356                 if (val && isdigit(c)) {
3357                         char *end;
3358                         int n = strtoul(arg, &end, 10);
3359                         if (*end)
3360                                 return 0;
3361                         *val = n;
3362                         return 1;
3363                 }
3364                 return 0;
3365         }
3366         if (c != '-')
3367                 return 0;
3368         arg++;
3369         eq = strchr(arg, '=');
3370         if (eq)
3371                 len = eq - arg;
3372         else
3373                 len = strlen(arg);
3374         if (!len || strncmp(arg, arg_long, len))
3375                 return 0;
3376         if (eq) {
3377                 int n;
3378                 char *end;
3379                 if (!isdigit(*++eq))
3380                         return 0;
3381                 n = strtoul(eq, &end, 10);
3382                 if (*end)
3383                         return 0;
3384                 *val = n;
3385         }
3386         return 1;
3387 }
3388
3389 static int diff_scoreopt_parse(const char *opt);
3390
3391 static inline int short_opt(char opt, const char **argv,
3392                             const char **optarg)
3393 {
3394         const char *arg = argv[0];
3395         if (arg[0] != '-' || arg[1] != opt)
3396                 return 0;
3397         if (arg[2] != '\0') {
3398                 *optarg = arg + 2;
3399                 return 1;
3400         }
3401         if (!argv[1])
3402                 die("Option '%c' requires a value", opt);
3403         *optarg = argv[1];
3404         return 2;
3405 }
3406
3407 int parse_long_opt(const char *opt, const char **argv,
3408                    const char **optarg)
3409 {
3410         const char *arg = argv[0];
3411         if (arg[0] != '-' || arg[1] != '-')
3412                 return 0;
3413         arg += strlen("--");
3414         if (!starts_with(arg, opt))
3415                 return 0;
3416         arg += strlen(opt);
3417         if (*arg == '=') { /* stuck form: --option=value */
3418                 *optarg = arg + 1;
3419                 return 1;
3420         }
3421         if (*arg != '\0')
3422                 return 0;
3423         /* separate form: --option value */
3424         if (!argv[1])
3425                 die("Option '--%s' requires a value", opt);
3426         *optarg = argv[1];
3427         return 2;
3428 }
3429
3430 static int stat_opt(struct diff_options *options, const char **av)
3431 {
3432         const char *arg = av[0];
3433         char *end;
3434         int width = options->stat_width;
3435         int name_width = options->stat_name_width;
3436         int graph_width = options->stat_graph_width;
3437         int count = options->stat_count;
3438         int argcount = 1;
3439
3440         arg += strlen("--stat");
3441         end = (char *)arg;
3442
3443         switch (*arg) {
3444         case '-':
3445                 if (starts_with(arg, "-width")) {
3446                         arg += strlen("-width");
3447                         if (*arg == '=')
3448                                 width = strtoul(arg + 1, &end, 10);
3449                         else if (!*arg && !av[1])
3450                                 die("Option '--stat-width' requires a value");
3451                         else if (!*arg) {
3452                                 width = strtoul(av[1], &end, 10);
3453                                 argcount = 2;
3454                         }
3455                 } else if (starts_with(arg, "-name-width")) {
3456                         arg += strlen("-name-width");
3457                         if (*arg == '=')
3458                                 name_width = strtoul(arg + 1, &end, 10);
3459                         else if (!*arg && !av[1])
3460                                 die("Option '--stat-name-width' requires a value");
3461                         else if (!*arg) {
3462                                 name_width = strtoul(av[1], &end, 10);
3463                                 argcount = 2;
3464                         }
3465                 } else if (starts_with(arg, "-graph-width")) {
3466                         arg += strlen("-graph-width");
3467                         if (*arg == '=')
3468                                 graph_width = strtoul(arg + 1, &end, 10);
3469                         else if (!*arg && !av[1])
3470                                 die("Option '--stat-graph-width' requires a value");
3471                         else if (!*arg) {
3472                                 graph_width = strtoul(av[1], &end, 10);
3473                                 argcount = 2;
3474                         }
3475                 } else if (starts_with(arg, "-count")) {
3476                         arg += strlen("-count");
3477                         if (*arg == '=')
3478                                 count = strtoul(arg + 1, &end, 10);
3479                         else if (!*arg && !av[1])
3480                                 die("Option '--stat-count' requires a value");
3481                         else if (!*arg) {
3482                                 count = strtoul(av[1], &end, 10);
3483                                 argcount = 2;
3484                         }
3485                 }
3486                 break;
3487         case '=':
3488                 width = strtoul(arg+1, &end, 10);
3489                 if (*end == ',')
3490                         name_width = strtoul(end+1, &end, 10);
3491                 if (*end == ',')
3492                         count = strtoul(end+1, &end, 10);
3493         }
3494
3495         /* Important! This checks all the error cases! */
3496         if (*end)
3497                 return 0;
3498         options->output_format |= DIFF_FORMAT_DIFFSTAT;
3499         options->stat_name_width = name_width;
3500         options->stat_graph_width = graph_width;
3501         options->stat_width = width;
3502         options->stat_count = count;
3503         return argcount;
3504 }
3505
3506 static int parse_dirstat_opt(struct diff_options *options, const char *params)
3507 {
3508         struct strbuf errmsg = STRBUF_INIT;
3509         if (parse_dirstat_params(options, params, &errmsg))
3510                 die(_("Failed to parse --dirstat/-X option parameter:\n%s"),
3511                     errmsg.buf);
3512         strbuf_release(&errmsg);
3513         /*
3514          * The caller knows a dirstat-related option is given from the command
3515          * line; allow it to say "return this_function();"
3516          */
3517         options->output_format |= DIFF_FORMAT_DIRSTAT;
3518         return 1;
3519 }
3520
3521 static int parse_submodule_opt(struct diff_options *options, const char *value)
3522 {
3523         if (parse_submodule_params(options, value))
3524                 die(_("Failed to parse --submodule option parameter: '%s'"),
3525                         value);
3526         return 1;
3527 }
3528
3529 static const char diff_status_letters[] = {
3530         DIFF_STATUS_ADDED,
3531         DIFF_STATUS_COPIED,
3532         DIFF_STATUS_DELETED,
3533         DIFF_STATUS_MODIFIED,
3534         DIFF_STATUS_RENAMED,
3535         DIFF_STATUS_TYPE_CHANGED,
3536         DIFF_STATUS_UNKNOWN,
3537         DIFF_STATUS_UNMERGED,
3538         DIFF_STATUS_FILTER_AON,
3539         DIFF_STATUS_FILTER_BROKEN,
3540         '\0',
3541 };
3542
3543 static unsigned int filter_bit['Z' + 1];
3544
3545 static void prepare_filter_bits(void)
3546 {
3547         int i;
3548
3549         if (!filter_bit[DIFF_STATUS_ADDED]) {
3550                 for (i = 0; diff_status_letters[i]; i++)
3551                         filter_bit[(int) diff_status_letters[i]] = (1 << i);
3552         }
3553 }
3554
3555 static unsigned filter_bit_tst(char status, const struct diff_options *opt)
3556 {
3557         return opt->filter & filter_bit[(int) status];
3558 }
3559
3560 static int parse_diff_filter_opt(const char *optarg, struct diff_options *opt)
3561 {
3562         int i, optch;
3563
3564         prepare_filter_bits();
3565
3566         /*
3567          * If there is a negation e.g. 'd' in the input, and we haven't
3568          * initialized the filter field with another --diff-filter, start
3569          * from full set of bits, except for AON.
3570          */
3571         if (!opt->filter) {
3572                 for (i = 0; (optch = optarg[i]) != '\0'; i++) {
3573                         if (optch < 'a' || 'z' < optch)
3574                                 continue;
3575                         opt->filter = (1 << (ARRAY_SIZE(diff_status_letters) - 1)) - 1;
3576                         opt->filter &= ~filter_bit[DIFF_STATUS_FILTER_AON];
3577                         break;
3578                 }
3579         }
3580
3581         for (i = 0; (optch = optarg[i]) != '\0'; i++) {
3582                 unsigned int bit;
3583                 int negate;
3584
3585                 if ('a' <= optch && optch <= 'z') {
3586                         negate = 1;
3587                         optch = toupper(optch);
3588                 } else {
3589                         negate = 0;
3590                 }
3591
3592                 bit = (0 <= optch && optch <= 'Z') ? filter_bit[optch] : 0;
3593                 if (!bit)
3594                         return optarg[i];
3595                 if (negate)
3596                         opt->filter &= ~bit;
3597                 else
3598                         opt->filter |= bit;
3599         }
3600         return 0;
3601 }
3602
3603 static void enable_patch_output(int *fmt) {
3604         *fmt &= ~DIFF_FORMAT_NO_OUTPUT;
3605         *fmt |= DIFF_FORMAT_PATCH;
3606 }
3607
3608 int diff_opt_parse(struct diff_options *options, const char **av, int ac)
3609 {
3610         const char *arg = av[0];
3611         const char *optarg;
3612         int argcount;
3613
3614         /* Output format options */
3615         if (!strcmp(arg, "-p") || !strcmp(arg, "-u") || !strcmp(arg, "--patch")
3616             || opt_arg(arg, 'U', "unified", &options->context))
3617                 enable_patch_output(&options->output_format);
3618         else if (!strcmp(arg, "--raw"))
3619                 options->output_format |= DIFF_FORMAT_RAW;
3620         else if (!strcmp(arg, "--patch-with-raw")) {
3621                 enable_patch_output(&options->output_format);
3622                 options->output_format |= DIFF_FORMAT_RAW;
3623         } else if (!strcmp(arg, "--numstat"))
3624                 options->output_format |= DIFF_FORMAT_NUMSTAT;
3625         else if (!strcmp(arg, "--shortstat"))
3626                 options->output_format |= DIFF_FORMAT_SHORTSTAT;
3627         else if (!strcmp(arg, "-X") || !strcmp(arg, "--dirstat"))
3628                 return parse_dirstat_opt(options, "");
3629         else if (starts_with(arg, "-X"))
3630                 return parse_dirstat_opt(options, arg + 2);
3631         else if (starts_with(arg, "--dirstat="))
3632                 return parse_dirstat_opt(options, arg + 10);
3633         else if (!strcmp(arg, "--cumulative"))
3634                 return parse_dirstat_opt(options, "cumulative");
3635         else if (!strcmp(arg, "--dirstat-by-file"))
3636                 return parse_dirstat_opt(options, "files");
3637         else if (starts_with(arg, "--dirstat-by-file=")) {
3638                 parse_dirstat_opt(options, "files");
3639                 return parse_dirstat_opt(options, arg + 18);
3640         }
3641         else if (!strcmp(arg, "--check"))
3642                 options->output_format |= DIFF_FORMAT_CHECKDIFF;
3643         else if (!strcmp(arg, "--summary"))
3644                 options->output_format |= DIFF_FORMAT_SUMMARY;
3645         else if (!strcmp(arg, "--patch-with-stat")) {
3646                 enable_patch_output(&options->output_format);
3647                 options->output_format |= DIFF_FORMAT_DIFFSTAT;
3648         } else if (!strcmp(arg, "--name-only"))
3649                 options->output_format |= DIFF_FORMAT_NAME;
3650         else if (!strcmp(arg, "--name-status"))
3651                 options->output_format |= DIFF_FORMAT_NAME_STATUS;
3652         else if (!strcmp(arg, "-s") || !strcmp(arg, "--no-patch"))
3653                 options->output_format |= DIFF_FORMAT_NO_OUTPUT;
3654         else if (starts_with(arg, "--stat"))
3655                 /* --stat, --stat-width, --stat-name-width, or --stat-count */
3656                 return stat_opt(options, av);
3657
3658         /* renames options */
3659         else if (starts_with(arg, "-B") || starts_with(arg, "--break-rewrites=") ||
3660                  !strcmp(arg, "--break-rewrites")) {
3661                 if ((options->break_opt = diff_scoreopt_parse(arg)) == -1)
3662                         return error("invalid argument to -B: %s", arg+2);
3663         }
3664         else if (starts_with(arg, "-M") || starts_with(arg, "--find-renames=") ||
3665                  !strcmp(arg, "--find-renames")) {
3666                 if ((options->rename_score = diff_scoreopt_parse(arg)) == -1)
3667                         return error("invalid argument to -M: %s", arg+2);
3668                 options->detect_rename = DIFF_DETECT_RENAME;
3669         }
3670         else if (!strcmp(arg, "-D") || !strcmp(arg, "--irreversible-delete")) {
3671                 options->irreversible_delete = 1;
3672         }
3673         else if (starts_with(arg, "-C") || starts_with(arg, "--find-copies=") ||
3674                  !strcmp(arg, "--find-copies")) {
3675                 if (options->detect_rename == DIFF_DETECT_COPY)
3676                         DIFF_OPT_SET(options, FIND_COPIES_HARDER);
3677                 if ((options->rename_score = diff_scoreopt_parse(arg)) == -1)
3678                         return error("invalid argument to -C: %s", arg+2);
3679                 options->detect_rename = DIFF_DETECT_COPY;
3680         }
3681         else if (!strcmp(arg, "--no-renames"))
3682                 options->detect_rename = 0;
3683         else if (!strcmp(arg, "--rename-empty"))
3684                 DIFF_OPT_SET(options, RENAME_EMPTY);
3685         else if (!strcmp(arg, "--no-rename-empty"))
3686                 DIFF_OPT_CLR(options, RENAME_EMPTY);
3687         else if (!strcmp(arg, "--relative"))
3688                 DIFF_OPT_SET(options, RELATIVE_NAME);
3689         else if (starts_with(arg, "--relative=")) {
3690                 DIFF_OPT_SET(options, RELATIVE_NAME);
3691                 options->prefix = arg + 11;
3692         }
3693
3694         /* xdiff options */
3695         else if (!strcmp(arg, "--minimal"))
3696                 DIFF_XDL_SET(options, NEED_MINIMAL);
3697         else if (!strcmp(arg, "--no-minimal"))
3698                 DIFF_XDL_CLR(options, NEED_MINIMAL);
3699         else if (!strcmp(arg, "-w") || !strcmp(arg, "--ignore-all-space"))
3700                 DIFF_XDL_SET(options, IGNORE_WHITESPACE);
3701         else if (!strcmp(arg, "-b") || !strcmp(arg, "--ignore-space-change"))
3702                 DIFF_XDL_SET(options, IGNORE_WHITESPACE_CHANGE);
3703         else if (!strcmp(arg, "--ignore-space-at-eol"))
3704                 DIFF_XDL_SET(options, IGNORE_WHITESPACE_AT_EOL);
3705         else if (!strcmp(arg, "--ignore-blank-lines"))
3706                 DIFF_XDL_SET(options, IGNORE_BLANK_LINES);
3707         else if (!strcmp(arg, "--patience"))
3708                 options->xdl_opts = DIFF_WITH_ALG(options, PATIENCE_DIFF);
3709         else if (!strcmp(arg, "--histogram"))
3710                 options->xdl_opts = DIFF_WITH_ALG(options, HISTOGRAM_DIFF);
3711         else if ((argcount = parse_long_opt("diff-algorithm", av, &optarg))) {
3712                 long value = parse_algorithm_value(optarg);
3713                 if (value < 0)
3714                         return error("option diff-algorithm accepts \"myers\", "
3715                                      "\"minimal\", \"patience\" and \"histogram\"");
3716                 /* clear out previous settings */
3717                 DIFF_XDL_CLR(options, NEED_MINIMAL);
3718                 options->xdl_opts &= ~XDF_DIFF_ALGORITHM_MASK;
3719                 options->xdl_opts |= value;
3720                 return argcount;
3721         }
3722
3723         /* flags options */
3724         else if (!strcmp(arg, "--binary")) {
3725                 enable_patch_output(&options->output_format);
3726                 DIFF_OPT_SET(options, BINARY);
3727         }
3728         else if (!strcmp(arg, "--full-index"))
3729                 DIFF_OPT_SET(options, FULL_INDEX);
3730         else if (!strcmp(arg, "-a") || !strcmp(arg, "--text"))
3731                 DIFF_OPT_SET(options, TEXT);
3732         else if (!strcmp(arg, "-R"))
3733                 DIFF_OPT_SET(options, REVERSE_DIFF);
3734         else if (!strcmp(arg, "--find-copies-harder"))
3735                 DIFF_OPT_SET(options, FIND_COPIES_HARDER);
3736         else if (!strcmp(arg, "--follow"))
3737                 DIFF_OPT_SET(options, FOLLOW_RENAMES);
3738         else if (!strcmp(arg, "--no-follow"))
3739                 DIFF_OPT_CLR(options, FOLLOW_RENAMES);
3740         else if (!strcmp(arg, "--color"))
3741                 options->use_color = 1;
3742         else if (starts_with(arg, "--color=")) {
3743                 int value = git_config_colorbool(NULL, arg+8);
3744                 if (value < 0)
3745                         return error("option `color' expects \"always\", \"auto\", or \"never\"");
3746                 options->use_color = value;
3747         }
3748         else if (!strcmp(arg, "--no-color"))
3749                 options->use_color = 0;
3750         else if (!strcmp(arg, "--color-words")) {
3751                 options->use_color = 1;
3752                 options->word_diff = DIFF_WORDS_COLOR;
3753         }
3754         else if (starts_with(arg, "--color-words=")) {
3755                 options->use_color = 1;
3756                 options->word_diff = DIFF_WORDS_COLOR;
3757                 options->word_regex = arg + 14;
3758         }
3759         else if (!strcmp(arg, "--word-diff")) {
3760                 if (options->word_diff == DIFF_WORDS_NONE)
3761                         options->word_diff = DIFF_WORDS_PLAIN;
3762         }
3763         else if (starts_with(arg, "--word-diff=")) {
3764                 const char *type = arg + 12;
3765                 if (!strcmp(type, "plain"))
3766                         options->word_diff = DIFF_WORDS_PLAIN;
3767                 else if (!strcmp(type, "color")) {
3768                         options->use_color = 1;
3769                         options->word_diff = DIFF_WORDS_COLOR;
3770                 }
3771                 else if (!strcmp(type, "porcelain"))
3772                         options->word_diff = DIFF_WORDS_PORCELAIN;
3773                 else if (!strcmp(type, "none"))
3774                         options->word_diff = DIFF_WORDS_NONE;
3775                 else
3776                         die("bad --word-diff argument: %s", type);
3777         }
3778         else if ((argcount = parse_long_opt("word-diff-regex", av, &optarg))) {
3779                 if (options->word_diff == DIFF_WORDS_NONE)
3780                         options->word_diff = DIFF_WORDS_PLAIN;
3781                 options->word_regex = optarg;
3782                 return argcount;
3783         }
3784         else if (!strcmp(arg, "--exit-code"))
3785                 DIFF_OPT_SET(options, EXIT_WITH_STATUS);
3786         else if (!strcmp(arg, "--quiet"))
3787                 DIFF_OPT_SET(options, QUICK);
3788         else if (!strcmp(arg, "--ext-diff"))
3789                 DIFF_OPT_SET(options, ALLOW_EXTERNAL);
3790         else if (!strcmp(arg, "--no-ext-diff"))
3791                 DIFF_OPT_CLR(options, ALLOW_EXTERNAL);
3792         else if (!strcmp(arg, "--textconv"))
3793                 DIFF_OPT_SET(options, ALLOW_TEXTCONV);
3794         else if (!strcmp(arg, "--no-textconv"))
3795                 DIFF_OPT_CLR(options, ALLOW_TEXTCONV);
3796         else if (!strcmp(arg, "--ignore-submodules")) {
3797                 DIFF_OPT_SET(options, OVERRIDE_SUBMODULE_CONFIG);
3798                 handle_ignore_submodules_arg(options, "all");
3799         } else if (starts_with(arg, "--ignore-submodules=")) {
3800                 DIFF_OPT_SET(options, OVERRIDE_SUBMODULE_CONFIG);
3801                 handle_ignore_submodules_arg(options, arg + 20);
3802         } else if (!strcmp(arg, "--submodule"))
3803                 DIFF_OPT_SET(options, SUBMODULE_LOG);
3804         else if (starts_with(arg, "--submodule="))
3805                 return parse_submodule_opt(options, arg + 12);
3806
3807         /* misc options */
3808         else if (!strcmp(arg, "-z"))
3809                 options->line_termination = 0;
3810         else if ((argcount = short_opt('l', av, &optarg))) {
3811                 options->rename_limit = strtoul(optarg, NULL, 10);
3812                 return argcount;
3813         }
3814         else if ((argcount = short_opt('S', av, &optarg))) {
3815                 options->pickaxe = optarg;
3816                 options->pickaxe_opts |= DIFF_PICKAXE_KIND_S;
3817                 return argcount;
3818         } else if ((argcount = short_opt('G', av, &optarg))) {
3819                 options->pickaxe = optarg;
3820                 options->pickaxe_opts |= DIFF_PICKAXE_KIND_G;
3821                 return argcount;
3822         }
3823         else if (!strcmp(arg, "--pickaxe-all"))
3824                 options->pickaxe_opts |= DIFF_PICKAXE_ALL;
3825         else if (!strcmp(arg, "--pickaxe-regex"))
3826                 options->pickaxe_opts |= DIFF_PICKAXE_REGEX;
3827         else if ((argcount = short_opt('O', av, &optarg))) {
3828                 options->orderfile = optarg;
3829                 return argcount;
3830         }
3831         else if ((argcount = parse_long_opt("diff-filter", av, &optarg))) {
3832                 int offending = parse_diff_filter_opt(optarg, options);
3833                 if (offending)
3834                         die("unknown change class '%c' in --diff-filter=%s",
3835                             offending, optarg);
3836                 return argcount;
3837         }
3838         else if (!strcmp(arg, "--abbrev"))
3839                 options->abbrev = DEFAULT_ABBREV;
3840         else if (starts_with(arg, "--abbrev=")) {
3841                 options->abbrev = strtoul(arg + 9, NULL, 10);
3842                 if (options->abbrev < MINIMUM_ABBREV)
3843                         options->abbrev = MINIMUM_ABBREV;
3844                 else if (40 < options->abbrev)
3845                         options->abbrev = 40;
3846         }
3847         else if ((argcount = parse_long_opt("src-prefix", av, &optarg))) {
3848                 options->a_prefix = optarg;
3849                 return argcount;
3850         }
3851         else if ((argcount = parse_long_opt("dst-prefix", av, &optarg))) {
3852                 options->b_prefix = optarg;
3853                 return argcount;
3854         }
3855         else if (!strcmp(arg, "--no-prefix"))
3856                 options->a_prefix = options->b_prefix = "";
3857         else if (opt_arg(arg, '\0', "inter-hunk-context",
3858                          &options->interhunkcontext))
3859                 ;
3860         else if (!strcmp(arg, "-W"))
3861                 DIFF_OPT_SET(options, FUNCCONTEXT);
3862         else if (!strcmp(arg, "--function-context"))
3863                 DIFF_OPT_SET(options, FUNCCONTEXT);
3864         else if (!strcmp(arg, "--no-function-context"))
3865                 DIFF_OPT_CLR(options, FUNCCONTEXT);
3866         else if ((argcount = parse_long_opt("output", av, &optarg))) {
3867                 options->file = fopen(optarg, "w");
3868                 if (!options->file)
3869                         die_errno("Could not open '%s'", optarg);
3870                 options->close_file = 1;
3871                 return argcount;
3872         } else
3873                 return 0;
3874         return 1;
3875 }
3876
3877 int parse_rename_score(const char **cp_p)
3878 {
3879         unsigned long num, scale;
3880         int ch, dot;
3881         const char *cp = *cp_p;
3882
3883         num = 0;
3884         scale = 1;
3885         dot = 0;
3886         for (;;) {
3887                 ch = *cp;
3888                 if ( !dot && ch == '.' ) {
3889                         scale = 1;
3890                         dot = 1;
3891                 } else if ( ch == '%' ) {
3892                         scale = dot ? scale*100 : 100;
3893                         cp++;   /* % is always at the end */
3894                         break;
3895                 } else if ( ch >= '0' && ch <= '9' ) {
3896                         if ( scale < 100000 ) {
3897                                 scale *= 10;
3898                                 num = (num*10) + (ch-'0');
3899                         }
3900                 } else {
3901                         break;
3902                 }
3903                 cp++;
3904         }
3905         *cp_p = cp;
3906
3907         /* user says num divided by scale and we say internally that
3908          * is MAX_SCORE * num / scale.
3909          */
3910         return (int)((num >= scale) ? MAX_SCORE : (MAX_SCORE * num / scale));
3911 }
3912
3913 static int diff_scoreopt_parse(const char *opt)
3914 {
3915         int opt1, opt2, cmd;
3916
3917         if (*opt++ != '-')
3918                 return -1;
3919         cmd = *opt++;
3920         if (cmd == '-') {
3921                 /* convert the long-form arguments into short-form versions */
3922                 if (starts_with(opt, "break-rewrites")) {
3923                         opt += strlen("break-rewrites");
3924                         if (*opt == 0 || *opt++ == '=')
3925                                 cmd = 'B';
3926                 } else if (starts_with(opt, "find-copies")) {
3927                         opt += strlen("find-copies");
3928                         if (*opt == 0 || *opt++ == '=')
3929                                 cmd = 'C';
3930                 } else if (starts_with(opt, "find-renames")) {
3931                         opt += strlen("find-renames");
3932                         if (*opt == 0 || *opt++ == '=')
3933                                 cmd = 'M';
3934                 }
3935         }
3936         if (cmd != 'M' && cmd != 'C' && cmd != 'B')
3937                 return -1; /* that is not a -M, -C nor -B option */
3938
3939         opt1 = parse_rename_score(&opt);
3940         if (cmd != 'B')
3941                 opt2 = 0;
3942         else {
3943                 if (*opt == 0)
3944                         opt2 = 0;
3945                 else if (*opt != '/')
3946                         return -1; /* we expect -B80/99 or -B80 */
3947                 else {
3948                         opt++;
3949                         opt2 = parse_rename_score(&opt);
3950                 }
3951         }
3952         if (*opt != 0)
3953                 return -1;
3954         return opt1 | (opt2 << 16);
3955 }
3956
3957 struct diff_queue_struct diff_queued_diff;
3958
3959 void diff_q(struct diff_queue_struct *queue, struct diff_filepair *dp)
3960 {
3961         if (queue->alloc <= queue->nr) {
3962                 queue->alloc = alloc_nr(queue->alloc);
3963                 queue->queue = xrealloc(queue->queue,
3964                                         sizeof(dp) * queue->alloc);
3965         }
3966         queue->queue[queue->nr++] = dp;
3967 }
3968
3969 struct diff_filepair *diff_queue(struct diff_queue_struct *queue,
3970                                  struct diff_filespec *one,
3971                                  struct diff_filespec *two)
3972 {
3973         struct diff_filepair *dp = xcalloc(1, sizeof(*dp));
3974         dp->one = one;
3975         dp->two = two;
3976         if (queue)
3977                 diff_q(queue, dp);
3978         return dp;
3979 }
3980
3981 void diff_free_filepair(struct diff_filepair *p)
3982 {
3983         free_filespec(p->one);
3984         free_filespec(p->two);
3985         free(p);
3986 }
3987
3988 /* This is different from find_unique_abbrev() in that
3989  * it stuffs the result with dots for alignment.
3990  */
3991 const char *diff_unique_abbrev(const unsigned char *sha1, int len)
3992 {
3993         int abblen;
3994         const char *abbrev;
3995         if (len == 40)
3996                 return sha1_to_hex(sha1);
3997
3998         abbrev = find_unique_abbrev(sha1, len);
3999         abblen = strlen(abbrev);
4000         if (abblen < 37) {
4001                 static char hex[41];
4002                 if (len < abblen && abblen <= len + 2)
4003                         sprintf(hex, "%s%.*s", abbrev, len+3-abblen, "..");
4004                 else
4005                         sprintf(hex, "%s...", abbrev);
4006                 return hex;
4007         }
4008         return sha1_to_hex(sha1);
4009 }
4010
4011 static void diff_flush_raw(struct diff_filepair *p, struct diff_options *opt)
4012 {
4013         int line_termination = opt->line_termination;
4014         int inter_name_termination = line_termination ? '\t' : '\0';
4015
4016         fprintf(opt->file, "%s", diff_line_prefix(opt));
4017         if (!(opt->output_format & DIFF_FORMAT_NAME_STATUS)) {
4018                 fprintf(opt->file, ":%06o %06o %s ", p->one->mode, p->two->mode,
4019                         diff_unique_abbrev(p->one->sha1, opt->abbrev));
4020                 fprintf(opt->file, "%s ", diff_unique_abbrev(p->two->sha1, opt->abbrev));
4021         }
4022         if (p->score) {
4023                 fprintf(opt->file, "%c%03d%c", p->status, similarity_index(p),
4024                         inter_name_termination);
4025         } else {
4026                 fprintf(opt->file, "%c%c", p->status, inter_name_termination);
4027         }
4028
4029         if (p->status == DIFF_STATUS_COPIED ||
4030             p->status == DIFF_STATUS_RENAMED) {
4031                 const char *name_a, *name_b;
4032                 name_a = p->one->path;
4033                 name_b = p->two->path;
4034                 strip_prefix(opt->prefix_length, &name_a, &name_b);
4035                 write_name_quoted(name_a, opt->file, inter_name_termination);
4036                 write_name_quoted(name_b, opt->file, line_termination);
4037         } else {
4038                 const char *name_a, *name_b;
4039                 name_a = p->one->mode ? p->one->path : p->two->path;
4040                 name_b = NULL;
4041                 strip_prefix(opt->prefix_length, &name_a, &name_b);
4042                 write_name_quoted(name_a, opt->file, line_termination);
4043         }
4044 }
4045
4046 int diff_unmodified_pair(struct diff_filepair *p)
4047 {
4048         /* This function is written stricter than necessary to support
4049          * the currently implemented transformers, but the idea is to
4050          * let transformers to produce diff_filepairs any way they want,
4051          * and filter and clean them up here before producing the output.
4052          */
4053         struct diff_filespec *one = p->one, *two = p->two;
4054
4055         if (DIFF_PAIR_UNMERGED(p))
4056                 return 0; /* unmerged is interesting */
4057
4058         /* deletion, addition, mode or type change
4059          * and rename are all interesting.
4060          */
4061         if (DIFF_FILE_VALID(one) != DIFF_FILE_VALID(two) ||
4062             DIFF_PAIR_MODE_CHANGED(p) ||
4063             strcmp(one->path, two->path))
4064                 return 0;
4065
4066         /* both are valid and point at the same path.  that is, we are
4067          * dealing with a change.
4068          */
4069         if (one->sha1_valid && two->sha1_valid &&
4070             !hashcmp(one->sha1, two->sha1) &&
4071             !one->dirty_submodule && !two->dirty_submodule)
4072                 return 1; /* no change */
4073         if (!one->sha1_valid && !two->sha1_valid)
4074                 return 1; /* both look at the same file on the filesystem. */
4075         return 0;
4076 }
4077
4078 static void diff_flush_patch(struct diff_filepair *p, struct diff_options *o)
4079 {
4080         if (diff_unmodified_pair(p))
4081                 return;
4082
4083         if ((DIFF_FILE_VALID(p->one) && S_ISDIR(p->one->mode)) ||
4084             (DIFF_FILE_VALID(p->two) && S_ISDIR(p->two->mode)))
4085                 return; /* no tree diffs in patch format */
4086
4087         run_diff(p, o);
4088 }
4089
4090 static void diff_flush_stat(struct diff_filepair *p, struct diff_options *o,
4091                             struct diffstat_t *diffstat)
4092 {
4093         if (diff_unmodified_pair(p))
4094                 return;
4095
4096         if ((DIFF_FILE_VALID(p->one) && S_ISDIR(p->one->mode)) ||
4097             (DIFF_FILE_VALID(p->two) && S_ISDIR(p->two->mode)))
4098                 return; /* no useful stat for tree diffs */
4099
4100         run_diffstat(p, o, diffstat);
4101 }
4102
4103 static void diff_flush_checkdiff(struct diff_filepair *p,
4104                 struct diff_options *o)
4105 {
4106         if (diff_unmodified_pair(p))
4107                 return;
4108
4109         if ((DIFF_FILE_VALID(p->one) && S_ISDIR(p->one->mode)) ||
4110             (DIFF_FILE_VALID(p->two) && S_ISDIR(p->two->mode)))
4111                 return; /* nothing to check in tree diffs */
4112
4113         run_checkdiff(p, o);
4114 }
4115
4116 int diff_queue_is_empty(void)
4117 {
4118         struct diff_queue_struct *q = &diff_queued_diff;
4119         int i;
4120         for (i = 0; i < q->nr; i++)
4121                 if (!diff_unmodified_pair(q->queue[i]))
4122                         return 0;
4123         return 1;
4124 }
4125
4126 #if DIFF_DEBUG
4127 void diff_debug_filespec(struct diff_filespec *s, int x, const char *one)
4128 {
4129         fprintf(stderr, "queue[%d] %s (%s) %s %06o %s\n",
4130                 x, one ? one : "",
4131                 s->path,
4132                 DIFF_FILE_VALID(s) ? "valid" : "invalid",
4133                 s->mode,
4134                 s->sha1_valid ? sha1_to_hex(s->sha1) : "");
4135         fprintf(stderr, "queue[%d] %s size %lu\n",
4136                 x, one ? one : "",
4137                 s->size);
4138 }
4139
4140 void diff_debug_filepair(const struct diff_filepair *p, int i)
4141 {
4142         diff_debug_filespec(p->one, i, "one");
4143         diff_debug_filespec(p->two, i, "two");
4144         fprintf(stderr, "score %d, status %c rename_used %d broken %d\n",
4145                 p->score, p->status ? p->status : '?',
4146                 p->one->rename_used, p->broken_pair);
4147 }
4148
4149 void diff_debug_queue(const char *msg, struct diff_queue_struct *q)
4150 {
4151         int i;
4152         if (msg)
4153                 fprintf(stderr, "%s\n", msg);
4154         fprintf(stderr, "q->nr = %d\n", q->nr);
4155         for (i = 0; i < q->nr; i++) {
4156                 struct diff_filepair *p = q->queue[i];
4157                 diff_debug_filepair(p, i);
4158         }
4159 }
4160 #endif
4161
4162 static void diff_resolve_rename_copy(void)
4163 {
4164         int i;
4165         struct diff_filepair *p;
4166         struct diff_queue_struct *q = &diff_queued_diff;
4167
4168         diff_debug_queue("resolve-rename-copy", q);
4169
4170         for (i = 0; i < q->nr; i++) {
4171                 p = q->queue[i];
4172                 p->status = 0; /* undecided */
4173                 if (DIFF_PAIR_UNMERGED(p))
4174                         p->status = DIFF_STATUS_UNMERGED;
4175                 else if (!DIFF_FILE_VALID(p->one))
4176                         p->status = DIFF_STATUS_ADDED;
4177                 else if (!DIFF_FILE_VALID(p->two))
4178                         p->status = DIFF_STATUS_DELETED;
4179                 else if (DIFF_PAIR_TYPE_CHANGED(p))
4180                         p->status = DIFF_STATUS_TYPE_CHANGED;
4181
4182                 /* from this point on, we are dealing with a pair
4183                  * whose both sides are valid and of the same type, i.e.
4184                  * either in-place edit or rename/copy edit.
4185                  */
4186                 else if (DIFF_PAIR_RENAME(p)) {
4187                         /*
4188                          * A rename might have re-connected a broken
4189                          * pair up, causing the pathnames to be the
4190                          * same again. If so, that's not a rename at
4191                          * all, just a modification..
4192                          *
4193                          * Otherwise, see if this source was used for
4194                          * multiple renames, in which case we decrement
4195                          * the count, and call it a copy.
4196                          */
4197                         if (!strcmp(p->one->path, p->two->path))
4198                                 p->status = DIFF_STATUS_MODIFIED;
4199                         else if (--p->one->rename_used > 0)
4200                                 p->status = DIFF_STATUS_COPIED;
4201                         else
4202                                 p->status = DIFF_STATUS_RENAMED;
4203                 }
4204                 else if (hashcmp(p->one->sha1, p->two->sha1) ||
4205                          p->one->mode != p->two->mode ||
4206                          p->one->dirty_submodule ||
4207                          p->two->dirty_submodule ||
4208                          is_null_sha1(p->one->sha1))
4209                         p->status = DIFF_STATUS_MODIFIED;
4210                 else {
4211                         /* This is a "no-change" entry and should not
4212                          * happen anymore, but prepare for broken callers.
4213                          */
4214                         error("feeding unmodified %s to diffcore",
4215                               p->one->path);
4216                         p->status = DIFF_STATUS_UNKNOWN;
4217                 }
4218         }
4219         diff_debug_queue("resolve-rename-copy done", q);
4220 }
4221
4222 static int check_pair_status(struct diff_filepair *p)
4223 {
4224         switch (p->status) {
4225         case DIFF_STATUS_UNKNOWN:
4226                 return 0;
4227         case 0:
4228                 die("internal error in diff-resolve-rename-copy");
4229         default:
4230                 return 1;
4231         }
4232 }
4233
4234 static void flush_one_pair(struct diff_filepair *p, struct diff_options *opt)
4235 {
4236         int fmt = opt->output_format;
4237
4238         if (fmt & DIFF_FORMAT_CHECKDIFF)
4239                 diff_flush_checkdiff(p, opt);
4240         else if (fmt & (DIFF_FORMAT_RAW | DIFF_FORMAT_NAME_STATUS))
4241                 diff_flush_raw(p, opt);
4242         else if (fmt & DIFF_FORMAT_NAME) {
4243                 const char *name_a, *name_b;
4244                 name_a = p->two->path;
4245                 name_b = NULL;
4246                 strip_prefix(opt->prefix_length, &name_a, &name_b);
4247                 write_name_quoted(name_a, opt->file, opt->line_termination);
4248         }
4249 }
4250
4251 static void show_file_mode_name(FILE *file, const char *newdelete, struct diff_filespec *fs)
4252 {
4253         if (fs->mode)
4254                 fprintf(file, " %s mode %06o ", newdelete, fs->mode);
4255         else
4256                 fprintf(file, " %s ", newdelete);
4257         write_name_quoted(fs->path, file, '\n');
4258 }
4259
4260
4261 static void show_mode_change(FILE *file, struct diff_filepair *p, int show_name,
4262                 const char *line_prefix)
4263 {
4264         if (p->one->mode && p->two->mode && p->one->mode != p->two->mode) {
4265                 fprintf(file, "%s mode change %06o => %06o%c", line_prefix, p->one->mode,
4266                         p->two->mode, show_name ? ' ' : '\n');
4267                 if (show_name) {
4268                         write_name_quoted(p->two->path, file, '\n');
4269                 }
4270         }
4271 }
4272
4273 static void show_rename_copy(FILE *file, const char *renamecopy, struct diff_filepair *p,
4274                         const char *line_prefix)
4275 {
4276         char *names = pprint_rename(p->one->path, p->two->path);
4277
4278         fprintf(file, " %s %s (%d%%)\n", renamecopy, names, similarity_index(p));
4279         free(names);
4280         show_mode_change(file, p, 0, line_prefix);
4281 }
4282
4283 static void diff_summary(struct diff_options *opt, struct diff_filepair *p)
4284 {
4285         FILE *file = opt->file;
4286         const char *line_prefix = diff_line_prefix(opt);
4287
4288         switch(p->status) {
4289         case DIFF_STATUS_DELETED:
4290                 fputs(line_prefix, file);
4291                 show_file_mode_name(file, "delete", p->one);
4292                 break;
4293         case DIFF_STATUS_ADDED:
4294                 fputs(line_prefix, file);
4295                 show_file_mode_name(file, "create", p->two);
4296                 break;
4297         case DIFF_STATUS_COPIED:
4298                 fputs(line_prefix, file);
4299                 show_rename_copy(file, "copy", p, line_prefix);
4300                 break;
4301         case DIFF_STATUS_RENAMED:
4302                 fputs(line_prefix, file);
4303                 show_rename_copy(file, "rename", p, line_prefix);
4304                 break;
4305         default:
4306                 if (p->score) {
4307                         fprintf(file, "%s rewrite ", line_prefix);
4308                         write_name_quoted(p->two->path, file, ' ');
4309                         fprintf(file, "(%d%%)\n", similarity_index(p));
4310                 }
4311                 show_mode_change(file, p, !p->score, line_prefix);
4312                 break;
4313         }
4314 }
4315
4316 struct patch_id_t {
4317         git_SHA_CTX *ctx;
4318         int patchlen;
4319 };
4320
4321 static int remove_space(char *line, int len)
4322 {
4323         int i;
4324         char *dst = line;
4325         unsigned char c;
4326
4327         for (i = 0; i < len; i++)
4328                 if (!isspace((c = line[i])))
4329                         *dst++ = c;
4330
4331         return dst - line;
4332 }
4333
4334 static void patch_id_consume(void *priv, char *line, unsigned long len)
4335 {
4336         struct patch_id_t *data = priv;
4337         int new_len;
4338
4339         /* Ignore line numbers when computing the SHA1 of the patch */
4340         if (starts_with(line, "@@ -"))
4341                 return;
4342
4343         new_len = remove_space(line, len);
4344
4345         git_SHA1_Update(data->ctx, line, new_len);
4346         data->patchlen += new_len;
4347 }
4348
4349 /* returns 0 upon success, and writes result into sha1 */
4350 static int diff_get_patch_id(struct diff_options *options, unsigned char *sha1)
4351 {
4352         struct diff_queue_struct *q = &diff_queued_diff;
4353         int i;
4354         git_SHA_CTX ctx;
4355         struct patch_id_t data;
4356         char buffer[PATH_MAX * 4 + 20];
4357
4358         git_SHA1_Init(&ctx);
4359         memset(&data, 0, sizeof(struct patch_id_t));
4360         data.ctx = &ctx;
4361
4362         for (i = 0; i < q->nr; i++) {
4363                 xpparam_t xpp;
4364                 xdemitconf_t xecfg;
4365                 mmfile_t mf1, mf2;
4366                 struct diff_filepair *p = q->queue[i];
4367                 int len1, len2;
4368
4369                 memset(&xpp, 0, sizeof(xpp));
4370                 memset(&xecfg, 0, sizeof(xecfg));
4371                 if (p->status == 0)
4372                         return error("internal diff status error");
4373                 if (p->status == DIFF_STATUS_UNKNOWN)
4374                         continue;
4375                 if (diff_unmodified_pair(p))
4376                         continue;
4377                 if ((DIFF_FILE_VALID(p->one) && S_ISDIR(p->one->mode)) ||
4378                     (DIFF_FILE_VALID(p->two) && S_ISDIR(p->two->mode)))
4379                         continue;
4380                 if (DIFF_PAIR_UNMERGED(p))
4381                         continue;
4382
4383                 diff_fill_sha1_info(p->one);
4384                 diff_fill_sha1_info(p->two);
4385                 if (fill_mmfile(&mf1, p->one) < 0 ||
4386                                 fill_mmfile(&mf2, p->two) < 0)
4387                         return error("unable to read files to diff");
4388
4389                 len1 = remove_space(p->one->path, strlen(p->one->path));
4390                 len2 = remove_space(p->two->path, strlen(p->two->path));
4391                 if (p->one->mode == 0)
4392                         len1 = snprintf(buffer, sizeof(buffer),
4393                                         "diff--gita/%.*sb/%.*s"
4394                                         "newfilemode%06o"
4395                                         "---/dev/null"
4396                                         "+++b/%.*s",
4397                                         len1, p->one->path,
4398                                         len2, p->two->path,
4399                                         p->two->mode,
4400                                         len2, p->two->path);
4401                 else if (p->two->mode == 0)
4402                         len1 = snprintf(buffer, sizeof(buffer),
4403                                         "diff--gita/%.*sb/%.*s"
4404                                         "deletedfilemode%06o"
4405                                         "---a/%.*s"
4406                                         "+++/dev/null",
4407                                         len1, p->one->path,
4408                                         len2, p->two->path,
4409                                         p->one->mode,
4410                                         len1, p->one->path);
4411                 else
4412                         len1 = snprintf(buffer, sizeof(buffer),
4413                                         "diff--gita/%.*sb/%.*s"
4414                                         "---a/%.*s"
4415                                         "+++b/%.*s",
4416                                         len1, p->one->path,
4417                                         len2, p->two->path,
4418                                         len1, p->one->path,
4419                                         len2, p->two->path);
4420                 git_SHA1_Update(&ctx, buffer, len1);
4421
4422                 if (diff_filespec_is_binary(p->one) ||
4423                     diff_filespec_is_binary(p->two)) {
4424                         git_SHA1_Update(&ctx, sha1_to_hex(p->one->sha1), 40);
4425                         git_SHA1_Update(&ctx, sha1_to_hex(p->two->sha1), 40);
4426                         continue;
4427                 }
4428
4429                 xpp.flags = 0;
4430                 xecfg.ctxlen = 3;
4431                 xecfg.flags = 0;
4432                 xdi_diff_outf(&mf1, &mf2, patch_id_consume, &data,
4433                               &xpp, &xecfg);
4434         }
4435
4436         git_SHA1_Final(sha1, &ctx);
4437         return 0;
4438 }
4439
4440 int diff_flush_patch_id(struct diff_options *options, unsigned char *sha1)
4441 {
4442         struct diff_queue_struct *q = &diff_queued_diff;
4443         int i;
4444         int result = diff_get_patch_id(options, sha1);
4445
4446         for (i = 0; i < q->nr; i++)
4447                 diff_free_filepair(q->queue[i]);
4448
4449         free(q->queue);
4450         DIFF_QUEUE_CLEAR(q);
4451
4452         return result;
4453 }
4454
4455 static int is_summary_empty(const struct diff_queue_struct *q)
4456 {
4457         int i;
4458
4459         for (i = 0; i < q->nr; i++) {
4460                 const struct diff_filepair *p = q->queue[i];
4461
4462                 switch (p->status) {
4463                 case DIFF_STATUS_DELETED:
4464                 case DIFF_STATUS_ADDED:
4465                 case DIFF_STATUS_COPIED:
4466                 case DIFF_STATUS_RENAMED:
4467                         return 0;
4468                 default:
4469                         if (p->score)
4470                                 return 0;
4471                         if (p->one->mode && p->two->mode &&
4472                             p->one->mode != p->two->mode)
4473                                 return 0;
4474                         break;
4475                 }
4476         }
4477         return 1;
4478 }
4479
4480 static const char rename_limit_warning[] =
4481 "inexact rename detection was skipped due to too many files.";
4482
4483 static const char degrade_cc_to_c_warning[] =
4484 "only found copies from modified paths due to too many files.";
4485
4486 static const char rename_limit_advice[] =
4487 "you may want to set your %s variable to at least "
4488 "%d and retry the command.";
4489
4490 void diff_warn_rename_limit(const char *varname, int needed, int degraded_cc)
4491 {
4492         if (degraded_cc)
4493                 warning(degrade_cc_to_c_warning);
4494         else if (needed)
4495                 warning(rename_limit_warning);
4496         else
4497                 return;
4498         if (0 < needed && needed < 32767)
4499                 warning(rename_limit_advice, varname, needed);
4500 }
4501
4502 void diff_flush(struct diff_options *options)
4503 {
4504         struct diff_queue_struct *q = &diff_queued_diff;
4505         int i, output_format = options->output_format;
4506         int separator = 0;
4507         int dirstat_by_line = 0;
4508
4509         /*
4510          * Order: raw, stat, summary, patch
4511          * or:    name/name-status/checkdiff (other bits clear)
4512          */
4513         if (!q->nr)
4514                 goto free_queue;
4515
4516         if (output_format & (DIFF_FORMAT_RAW |
4517                              DIFF_FORMAT_NAME |
4518                              DIFF_FORMAT_NAME_STATUS |
4519                              DIFF_FORMAT_CHECKDIFF)) {
4520                 for (i = 0; i < q->nr; i++) {
4521                         struct diff_filepair *p = q->queue[i];
4522                         if (check_pair_status(p))
4523                                 flush_one_pair(p, options);
4524                 }
4525                 separator++;
4526         }
4527
4528         if (output_format & DIFF_FORMAT_DIRSTAT && DIFF_OPT_TST(options, DIRSTAT_BY_LINE))
4529                 dirstat_by_line = 1;
4530
4531         if (output_format & (DIFF_FORMAT_DIFFSTAT|DIFF_FORMAT_SHORTSTAT|DIFF_FORMAT_NUMSTAT) ||
4532             dirstat_by_line) {
4533                 struct diffstat_t diffstat;
4534
4535                 memset(&diffstat, 0, sizeof(struct diffstat_t));
4536                 for (i = 0; i < q->nr; i++) {
4537                         struct diff_filepair *p = q->queue[i];
4538                         if (check_pair_status(p))
4539                                 diff_flush_stat(p, options, &diffstat);
4540                 }
4541                 if (output_format & DIFF_FORMAT_NUMSTAT)
4542                         show_numstat(&diffstat, options);
4543                 if (output_format & DIFF_FORMAT_DIFFSTAT)
4544                         show_stats(&diffstat, options);
4545                 if (output_format & DIFF_FORMAT_SHORTSTAT)
4546                         show_shortstats(&diffstat, options);
4547                 if (output_format & DIFF_FORMAT_DIRSTAT)
4548                         show_dirstat_by_line(&diffstat, options);
4549                 free_diffstat_info(&diffstat);
4550                 separator++;
4551         }
4552         if ((output_format & DIFF_FORMAT_DIRSTAT) && !dirstat_by_line)
4553                 show_dirstat(options);
4554
4555         if (output_format & DIFF_FORMAT_SUMMARY && !is_summary_empty(q)) {
4556                 for (i = 0; i < q->nr; i++) {
4557                         diff_summary(options, q->queue[i]);
4558                 }
4559                 separator++;
4560         }
4561
4562         if (output_format & DIFF_FORMAT_NO_OUTPUT &&
4563             DIFF_OPT_TST(options, EXIT_WITH_STATUS) &&
4564             DIFF_OPT_TST(options, DIFF_FROM_CONTENTS)) {
4565                 /*
4566                  * run diff_flush_patch for the exit status. setting
4567                  * options->file to /dev/null should be safe, because we
4568                  * aren't supposed to produce any output anyway.
4569                  */
4570                 if (options->close_file)
4571                         fclose(options->file);
4572                 options->file = fopen("/dev/null", "w");
4573                 if (!options->file)
4574                         die_errno("Could not open /dev/null");
4575                 options->close_file = 1;
4576                 for (i = 0; i < q->nr; i++) {
4577                         struct diff_filepair *p = q->queue[i];
4578                         if (check_pair_status(p))
4579                                 diff_flush_patch(p, options);
4580                         if (options->found_changes)
4581                                 break;
4582                 }
4583         }
4584
4585         if (output_format & DIFF_FORMAT_PATCH) {
4586                 if (separator) {
4587                         fprintf(options->file, "%s%c",
4588                                 diff_line_prefix(options),
4589                                 options->line_termination);
4590                         if (options->stat_sep) {
4591                                 /* attach patch instead of inline */
4592                                 fputs(options->stat_sep, options->file);
4593                         }
4594                 }
4595
4596                 for (i = 0; i < q->nr; i++) {
4597                         struct diff_filepair *p = q->queue[i];
4598                         if (check_pair_status(p))
4599                                 diff_flush_patch(p, options);
4600                 }
4601         }
4602
4603         if (output_format & DIFF_FORMAT_CALLBACK)
4604                 options->format_callback(q, options, options->format_callback_data);
4605
4606         for (i = 0; i < q->nr; i++)
4607                 diff_free_filepair(q->queue[i]);
4608 free_queue:
4609         free(q->queue);
4610         DIFF_QUEUE_CLEAR(q);
4611         if (options->close_file)
4612                 fclose(options->file);
4613
4614         /*
4615          * Report the content-level differences with HAS_CHANGES;
4616          * diff_addremove/diff_change does not set the bit when
4617          * DIFF_FROM_CONTENTS is in effect (e.g. with -w).
4618          */
4619         if (DIFF_OPT_TST(options, DIFF_FROM_CONTENTS)) {
4620                 if (options->found_changes)
4621                         DIFF_OPT_SET(options, HAS_CHANGES);
4622                 else
4623                         DIFF_OPT_CLR(options, HAS_CHANGES);
4624         }
4625 }
4626
4627 static int match_filter(const struct diff_options *options, const struct diff_filepair *p)
4628 {
4629         return (((p->status == DIFF_STATUS_MODIFIED) &&
4630                  ((p->score &&
4631                    filter_bit_tst(DIFF_STATUS_FILTER_BROKEN, options)) ||
4632                   (!p->score &&
4633                    filter_bit_tst(DIFF_STATUS_MODIFIED, options)))) ||
4634                 ((p->status != DIFF_STATUS_MODIFIED) &&
4635                  filter_bit_tst(p->status, options)));
4636 }
4637
4638 static void diffcore_apply_filter(struct diff_options *options)
4639 {
4640         int i;
4641         struct diff_queue_struct *q = &diff_queued_diff;
4642         struct diff_queue_struct outq;
4643
4644         DIFF_QUEUE_CLEAR(&outq);
4645
4646         if (!options->filter)
4647                 return;
4648
4649         if (filter_bit_tst(DIFF_STATUS_FILTER_AON, options)) {
4650                 int found;
4651                 for (i = found = 0; !found && i < q->nr; i++) {
4652                         if (match_filter(options, q->queue[i]))
4653                                 found++;
4654                 }
4655                 if (found)
4656                         return;
4657
4658                 /* otherwise we will clear the whole queue
4659                  * by copying the empty outq at the end of this
4660                  * function, but first clear the current entries
4661                  * in the queue.
4662                  */
4663                 for (i = 0; i < q->nr; i++)
4664                         diff_free_filepair(q->queue[i]);
4665         }
4666         else {
4667                 /* Only the matching ones */
4668                 for (i = 0; i < q->nr; i++) {
4669                         struct diff_filepair *p = q->queue[i];
4670                         if (match_filter(options, p))
4671                                 diff_q(&outq, p);
4672                         else
4673                                 diff_free_filepair(p);
4674                 }
4675         }
4676         free(q->queue);
4677         *q = outq;
4678 }
4679
4680 /* Check whether two filespecs with the same mode and size are identical */
4681 static int diff_filespec_is_identical(struct diff_filespec *one,
4682                                       struct diff_filespec *two)
4683 {
4684         if (S_ISGITLINK(one->mode))
4685                 return 0;
4686         if (diff_populate_filespec(one, 0))
4687                 return 0;
4688         if (diff_populate_filespec(two, 0))
4689                 return 0;
4690         return !memcmp(one->data, two->data, one->size);
4691 }
4692
4693 static int diff_filespec_check_stat_unmatch(struct diff_filepair *p)
4694 {
4695         if (p->done_skip_stat_unmatch)
4696                 return p->skip_stat_unmatch_result;
4697
4698         p->done_skip_stat_unmatch = 1;
4699         p->skip_stat_unmatch_result = 0;
4700         /*
4701          * 1. Entries that come from stat info dirtiness
4702          *    always have both sides (iow, not create/delete),
4703          *    one side of the object name is unknown, with
4704          *    the same mode and size.  Keep the ones that
4705          *    do not match these criteria.  They have real
4706          *    differences.
4707          *
4708          * 2. At this point, the file is known to be modified,
4709          *    with the same mode and size, and the object
4710          *    name of one side is unknown.  Need to inspect
4711          *    the identical contents.
4712          */
4713         if (!DIFF_FILE_VALID(p->one) || /* (1) */
4714             !DIFF_FILE_VALID(p->two) ||
4715             (p->one->sha1_valid && p->two->sha1_valid) ||
4716             (p->one->mode != p->two->mode) ||
4717             diff_populate_filespec(p->one, 1) ||
4718             diff_populate_filespec(p->two, 1) ||
4719             (p->one->size != p->two->size) ||
4720             !diff_filespec_is_identical(p->one, p->two)) /* (2) */
4721                 p->skip_stat_unmatch_result = 1;
4722         return p->skip_stat_unmatch_result;
4723 }
4724
4725 static void diffcore_skip_stat_unmatch(struct diff_options *diffopt)
4726 {
4727         int i;
4728         struct diff_queue_struct *q = &diff_queued_diff;
4729         struct diff_queue_struct outq;
4730         DIFF_QUEUE_CLEAR(&outq);
4731
4732         for (i = 0; i < q->nr; i++) {
4733                 struct diff_filepair *p = q->queue[i];
4734
4735                 if (diff_filespec_check_stat_unmatch(p))
4736                         diff_q(&outq, p);
4737                 else {
4738                         /*
4739                          * The caller can subtract 1 from skip_stat_unmatch
4740                          * to determine how many paths were dirty only
4741                          * due to stat info mismatch.
4742                          */
4743                         if (!DIFF_OPT_TST(diffopt, NO_INDEX))
4744                                 diffopt->skip_stat_unmatch++;
4745                         diff_free_filepair(p);
4746                 }
4747         }
4748         free(q->queue);
4749         *q = outq;
4750 }
4751
4752 static int diffnamecmp(const void *a_, const void *b_)
4753 {
4754         const struct diff_filepair *a = *((const struct diff_filepair **)a_);
4755         const struct diff_filepair *b = *((const struct diff_filepair **)b_);
4756         const char *name_a, *name_b;
4757
4758         name_a = a->one ? a->one->path : a->two->path;
4759         name_b = b->one ? b->one->path : b->two->path;
4760         return strcmp(name_a, name_b);
4761 }
4762
4763 void diffcore_fix_diff_index(struct diff_options *options)
4764 {
4765         struct diff_queue_struct *q = &diff_queued_diff;
4766         qsort(q->queue, q->nr, sizeof(q->queue[0]), diffnamecmp);
4767 }
4768
4769 void diffcore_std(struct diff_options *options)
4770 {
4771         if (options->skip_stat_unmatch)
4772                 diffcore_skip_stat_unmatch(options);
4773         if (!options->found_follow) {
4774                 /* See try_to_follow_renames() in tree-diff.c */
4775                 if (options->break_opt != -1)
4776                         diffcore_break(options->break_opt);
4777                 if (options->detect_rename)
4778                         diffcore_rename(options);
4779                 if (options->break_opt != -1)
4780                         diffcore_merge_broken();
4781         }
4782         if (options->pickaxe)
4783                 diffcore_pickaxe(options);
4784         if (options->orderfile)
4785                 diffcore_order(options->orderfile);
4786         if (!options->found_follow)
4787                 /* See try_to_follow_renames() in tree-diff.c */
4788                 diff_resolve_rename_copy();
4789         diffcore_apply_filter(options);
4790
4791         if (diff_queued_diff.nr && !DIFF_OPT_TST(options, DIFF_FROM_CONTENTS))
4792                 DIFF_OPT_SET(options, HAS_CHANGES);
4793         else
4794                 DIFF_OPT_CLR(options, HAS_CHANGES);
4795
4796         options->found_follow = 0;
4797 }
4798
4799 int diff_result_code(struct diff_options *opt, int status)
4800 {
4801         int result = 0;
4802
4803         diff_warn_rename_limit("diff.renameLimit",
4804                                opt->needed_rename_limit,
4805                                opt->degraded_cc_to_c);
4806         if (!DIFF_OPT_TST(opt, EXIT_WITH_STATUS) &&
4807             !(opt->output_format & DIFF_FORMAT_CHECKDIFF))
4808                 return status;
4809         if (DIFF_OPT_TST(opt, EXIT_WITH_STATUS) &&
4810             DIFF_OPT_TST(opt, HAS_CHANGES))
4811                 result |= 01;
4812         if ((opt->output_format & DIFF_FORMAT_CHECKDIFF) &&
4813             DIFF_OPT_TST(opt, CHECK_FAILED))
4814                 result |= 02;
4815         return result;
4816 }
4817
4818 int diff_can_quit_early(struct diff_options *opt)
4819 {
4820         return (DIFF_OPT_TST(opt, QUICK) &&
4821                 !opt->filter &&
4822                 DIFF_OPT_TST(opt, HAS_CHANGES));
4823 }
4824
4825 /*
4826  * Shall changes to this submodule be ignored?
4827  *
4828  * Submodule changes can be configured to be ignored separately for each path,
4829  * but that configuration can be overridden from the command line.
4830  */
4831 static int is_submodule_ignored(const char *path, struct diff_options *options)
4832 {
4833         int ignored = 0;
4834         unsigned orig_flags = options->flags;
4835         if (!DIFF_OPT_TST(options, OVERRIDE_SUBMODULE_CONFIG))
4836                 set_diffopt_flags_from_submodule_config(options, path);
4837         if (DIFF_OPT_TST(options, IGNORE_SUBMODULES))
4838                 ignored = 1;
4839         options->flags = orig_flags;
4840         return ignored;
4841 }
4842
4843 void diff_addremove(struct diff_options *options,
4844                     int addremove, unsigned mode,
4845                     const unsigned char *sha1,
4846                     int sha1_valid,
4847                     const char *concatpath, unsigned dirty_submodule)
4848 {
4849         struct diff_filespec *one, *two;
4850
4851         if (S_ISGITLINK(mode) && is_submodule_ignored(concatpath, options))
4852                 return;
4853
4854         /* This may look odd, but it is a preparation for
4855          * feeding "there are unchanged files which should
4856          * not produce diffs, but when you are doing copy
4857          * detection you would need them, so here they are"
4858          * entries to the diff-core.  They will be prefixed
4859          * with something like '=' or '*' (I haven't decided
4860          * which but should not make any difference).
4861          * Feeding the same new and old to diff_change()
4862          * also has the same effect.
4863          * Before the final output happens, they are pruned after
4864          * merged into rename/copy pairs as appropriate.
4865          */
4866         if (DIFF_OPT_TST(options, REVERSE_DIFF))
4867                 addremove = (addremove == '+' ? '-' :
4868                              addremove == '-' ? '+' : addremove);
4869
4870         if (options->prefix &&
4871             strncmp(concatpath, options->prefix, options->prefix_length))
4872                 return;
4873
4874         one = alloc_filespec(concatpath);
4875         two = alloc_filespec(concatpath);
4876
4877         if (addremove != '+')
4878                 fill_filespec(one, sha1, sha1_valid, mode);
4879         if (addremove != '-') {
4880                 fill_filespec(two, sha1, sha1_valid, mode);
4881                 two->dirty_submodule = dirty_submodule;
4882         }
4883
4884         diff_queue(&diff_queued_diff, one, two);
4885         if (!DIFF_OPT_TST(options, DIFF_FROM_CONTENTS))
4886                 DIFF_OPT_SET(options, HAS_CHANGES);
4887 }
4888
4889 void diff_change(struct diff_options *options,
4890                  unsigned old_mode, unsigned new_mode,
4891                  const unsigned char *old_sha1,
4892                  const unsigned char *new_sha1,
4893                  int old_sha1_valid, int new_sha1_valid,
4894                  const char *concatpath,
4895                  unsigned old_dirty_submodule, unsigned new_dirty_submodule)
4896 {
4897         struct diff_filespec *one, *two;
4898         struct diff_filepair *p;
4899
4900         if (S_ISGITLINK(old_mode) && S_ISGITLINK(new_mode) &&
4901             is_submodule_ignored(concatpath, options))
4902                 return;
4903
4904         if (DIFF_OPT_TST(options, REVERSE_DIFF)) {
4905                 unsigned tmp;
4906                 const unsigned char *tmp_c;
4907                 tmp = old_mode; old_mode = new_mode; new_mode = tmp;
4908                 tmp_c = old_sha1; old_sha1 = new_sha1; new_sha1 = tmp_c;
4909                 tmp = old_sha1_valid; old_sha1_valid = new_sha1_valid;
4910                         new_sha1_valid = tmp;
4911                 tmp = old_dirty_submodule; old_dirty_submodule = new_dirty_submodule;
4912                         new_dirty_submodule = tmp;
4913         }
4914
4915         if (options->prefix &&
4916             strncmp(concatpath, options->prefix, options->prefix_length))
4917                 return;
4918
4919         one = alloc_filespec(concatpath);
4920         two = alloc_filespec(concatpath);
4921         fill_filespec(one, old_sha1, old_sha1_valid, old_mode);
4922         fill_filespec(two, new_sha1, new_sha1_valid, new_mode);
4923         one->dirty_submodule = old_dirty_submodule;
4924         two->dirty_submodule = new_dirty_submodule;
4925         p = diff_queue(&diff_queued_diff, one, two);
4926
4927         if (DIFF_OPT_TST(options, DIFF_FROM_CONTENTS))
4928                 return;
4929
4930         if (DIFF_OPT_TST(options, QUICK) && options->skip_stat_unmatch &&
4931             !diff_filespec_check_stat_unmatch(p))
4932                 return;
4933
4934         DIFF_OPT_SET(options, HAS_CHANGES);
4935 }
4936
4937 struct diff_filepair *diff_unmerge(struct diff_options *options, const char *path)
4938 {
4939         struct diff_filepair *pair;
4940         struct diff_filespec *one, *two;
4941
4942         if (options->prefix &&
4943             strncmp(path, options->prefix, options->prefix_length))
4944                 return NULL;
4945
4946         one = alloc_filespec(path);
4947         two = alloc_filespec(path);
4948         pair = diff_queue(&diff_queued_diff, one, two);
4949         pair->is_unmerged = 1;
4950         return pair;
4951 }
4952
4953 static char *run_textconv(const char *pgm, struct diff_filespec *spec,
4954                 size_t *outsize)
4955 {
4956         struct diff_tempfile *temp;
4957         const char *argv[3];
4958         const char **arg = argv;
4959         struct child_process child;
4960         struct strbuf buf = STRBUF_INIT;
4961         int err = 0;
4962
4963         temp = prepare_temp_file(spec->path, spec);
4964         *arg++ = pgm;
4965         *arg++ = temp->name;
4966         *arg = NULL;
4967
4968         memset(&child, 0, sizeof(child));
4969         child.use_shell = 1;
4970         child.argv = argv;
4971         child.out = -1;
4972         if (start_command(&child)) {
4973                 remove_tempfile();
4974                 return NULL;
4975         }
4976
4977         if (strbuf_read(&buf, child.out, 0) < 0)
4978                 err = error("error reading from textconv command '%s'", pgm);
4979         close(child.out);
4980
4981         if (finish_command(&child) || err) {
4982                 strbuf_release(&buf);
4983                 remove_tempfile();
4984                 return NULL;
4985         }
4986         remove_tempfile();
4987
4988         return strbuf_detach(&buf, outsize);
4989 }
4990
4991 size_t fill_textconv(struct userdiff_driver *driver,
4992                      struct diff_filespec *df,
4993                      char **outbuf)
4994 {
4995         size_t size;
4996
4997         if (!driver || !driver->textconv) {
4998                 if (!DIFF_FILE_VALID(df)) {
4999                         *outbuf = "";
5000                         return 0;
5001                 }
5002                 if (diff_populate_filespec(df, 0))
5003                         die("unable to read files to diff");
5004                 *outbuf = df->data;
5005                 return df->size;
5006         }
5007
5008         if (driver->textconv_cache && df->sha1_valid) {
5009                 *outbuf = notes_cache_get(driver->textconv_cache, df->sha1,
5010                                           &size);
5011                 if (*outbuf)
5012                         return size;
5013         }
5014
5015         *outbuf = run_textconv(driver->textconv, df, &size);
5016         if (!*outbuf)
5017                 die("unable to read files to diff");
5018
5019         if (driver->textconv_cache && df->sha1_valid) {
5020                 /* ignore errors, as we might be in a readonly repository */
5021                 notes_cache_put(driver->textconv_cache, df->sha1, *outbuf,
5022                                 size);
5023                 /*
5024                  * we could save up changes and flush them all at the end,
5025                  * but we would need an extra call after all diffing is done.
5026                  * Since generating a cache entry is the slow path anyway,
5027                  * this extra overhead probably isn't a big deal.
5028                  */
5029                 notes_cache_write(driver->textconv_cache);
5030         }
5031
5032         return size;
5033 }
5034
5035 void setup_diff_pager(struct diff_options *opt)
5036 {
5037         /*
5038          * If the user asked for our exit code, then either they want --quiet
5039          * or --exit-code. We should definitely not bother with a pager in the
5040          * former case, as we will generate no output. Since we still properly
5041          * report our exit code even when a pager is run, we _could_ run a
5042          * pager with --exit-code. But since we have not done so historically,
5043          * and because it is easy to find people oneline advising "git diff
5044          * --exit-code" in hooks and other scripts, we do not do so.
5045          */
5046         if (!DIFF_OPT_TST(opt, EXIT_WITH_STATUS) &&
5047             check_pager_config("diff") != 0)
5048                 setup_pager();
5049 }