Merge branch 'mh/simplify-cache-tree-find'
[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         ALLOC_GROW(diffstat->files, diffstat->nr + 1, diffstat->alloc);
1365         diffstat->files[diffstat->nr++] = x;
1366         if (name_b) {
1367                 x->from_name = xstrdup(name_a);
1368                 x->name = xstrdup(name_b);
1369                 x->is_renamed = 1;
1370         }
1371         else {
1372                 x->from_name = NULL;
1373                 x->name = xstrdup(name_a);
1374         }
1375         return x;
1376 }
1377
1378 static void diffstat_consume(void *priv, char *line, unsigned long len)
1379 {
1380         struct diffstat_t *diffstat = priv;
1381         struct diffstat_file *x = diffstat->files[diffstat->nr - 1];
1382
1383         if (line[0] == '+')
1384                 x->added++;
1385         else if (line[0] == '-')
1386                 x->deleted++;
1387 }
1388
1389 const char mime_boundary_leader[] = "------------";
1390
1391 static int scale_linear(int it, int width, int max_change)
1392 {
1393         if (!it)
1394                 return 0;
1395         /*
1396          * make sure that at least one '-' or '+' is printed if
1397          * there is any change to this path. The easiest way is to
1398          * scale linearly as if the alloted width is one column shorter
1399          * than it is, and then add 1 to the result.
1400          */
1401         return 1 + (it * (width - 1) / max_change);
1402 }
1403
1404 static void show_name(FILE *file,
1405                       const char *prefix, const char *name, int len)
1406 {
1407         fprintf(file, " %s%-*s |", prefix, len, name);
1408 }
1409
1410 static void show_graph(FILE *file, char ch, int cnt, const char *set, const char *reset)
1411 {
1412         if (cnt <= 0)
1413                 return;
1414         fprintf(file, "%s", set);
1415         while (cnt--)
1416                 putc(ch, file);
1417         fprintf(file, "%s", reset);
1418 }
1419
1420 static void fill_print_name(struct diffstat_file *file)
1421 {
1422         char *pname;
1423
1424         if (file->print_name)
1425                 return;
1426
1427         if (!file->is_renamed) {
1428                 struct strbuf buf = STRBUF_INIT;
1429                 if (quote_c_style(file->name, &buf, NULL, 0)) {
1430                         pname = strbuf_detach(&buf, NULL);
1431                 } else {
1432                         pname = file->name;
1433                         strbuf_release(&buf);
1434                 }
1435         } else {
1436                 pname = pprint_rename(file->from_name, file->name);
1437         }
1438         file->print_name = pname;
1439 }
1440
1441 int print_stat_summary(FILE *fp, int files, int insertions, int deletions)
1442 {
1443         struct strbuf sb = STRBUF_INIT;
1444         int ret;
1445
1446         if (!files) {
1447                 assert(insertions == 0 && deletions == 0);
1448                 return fprintf(fp, "%s\n", " 0 files changed");
1449         }
1450
1451         strbuf_addf(&sb,
1452                     (files == 1) ? " %d file changed" : " %d files changed",
1453                     files);
1454
1455         /*
1456          * For binary diff, the caller may want to print "x files
1457          * changed" with insertions == 0 && deletions == 0.
1458          *
1459          * Not omitting "0 insertions(+), 0 deletions(-)" in this case
1460          * is probably less confusing (i.e skip over "2 files changed
1461          * but nothing about added/removed lines? Is this a bug in Git?").
1462          */
1463         if (insertions || deletions == 0) {
1464                 /*
1465                  * TRANSLATORS: "+" in (+) is a line addition marker;
1466                  * do not translate it.
1467                  */
1468                 strbuf_addf(&sb,
1469                             (insertions == 1) ? ", %d insertion(+)" : ", %d insertions(+)",
1470                             insertions);
1471         }
1472
1473         if (deletions || insertions == 0) {
1474                 /*
1475                  * TRANSLATORS: "-" in (-) is a line removal marker;
1476                  * do not translate it.
1477                  */
1478                 strbuf_addf(&sb,
1479                             (deletions == 1) ? ", %d deletion(-)" : ", %d deletions(-)",
1480                             deletions);
1481         }
1482         strbuf_addch(&sb, '\n');
1483         ret = fputs(sb.buf, fp);
1484         strbuf_release(&sb);
1485         return ret;
1486 }
1487
1488 static void show_stats(struct diffstat_t *data, struct diff_options *options)
1489 {
1490         int i, len, add, del, adds = 0, dels = 0;
1491         uintmax_t max_change = 0, max_len = 0;
1492         int total_files = data->nr, count;
1493         int width, name_width, graph_width, number_width = 0, bin_width = 0;
1494         const char *reset, *add_c, *del_c;
1495         const char *line_prefix = "";
1496         int extra_shown = 0;
1497
1498         if (data->nr == 0)
1499                 return;
1500
1501         line_prefix = diff_line_prefix(options);
1502         count = options->stat_count ? options->stat_count : data->nr;
1503
1504         reset = diff_get_color_opt(options, DIFF_RESET);
1505         add_c = diff_get_color_opt(options, DIFF_FILE_NEW);
1506         del_c = diff_get_color_opt(options, DIFF_FILE_OLD);
1507
1508         /*
1509          * Find the longest filename and max number of changes
1510          */
1511         for (i = 0; (i < count) && (i < data->nr); i++) {
1512                 struct diffstat_file *file = data->files[i];
1513                 uintmax_t change = file->added + file->deleted;
1514
1515                 if (!file->is_interesting && (change == 0)) {
1516                         count++; /* not shown == room for one more */
1517                         continue;
1518                 }
1519                 fill_print_name(file);
1520                 len = strlen(file->print_name);
1521                 if (max_len < len)
1522                         max_len = len;
1523
1524                 if (file->is_unmerged) {
1525                         /* "Unmerged" is 8 characters */
1526                         bin_width = bin_width < 8 ? 8 : bin_width;
1527                         continue;
1528                 }
1529                 if (file->is_binary) {
1530                         /* "Bin XXX -> YYY bytes" */
1531                         int w = 14 + decimal_width(file->added)
1532                                 + decimal_width(file->deleted);
1533                         bin_width = bin_width < w ? w : bin_width;
1534                         /* Display change counts aligned with "Bin" */
1535                         number_width = 3;
1536                         continue;
1537                 }
1538
1539                 if (max_change < change)
1540                         max_change = change;
1541         }
1542         count = i; /* where we can stop scanning in data->files[] */
1543
1544         /*
1545          * We have width = stat_width or term_columns() columns total.
1546          * We want a maximum of min(max_len, stat_name_width) for the name part.
1547          * We want a maximum of min(max_change, stat_graph_width) for the +- part.
1548          * We also need 1 for " " and 4 + decimal_width(max_change)
1549          * for " | NNNN " and one the empty column at the end, altogether
1550          * 6 + decimal_width(max_change).
1551          *
1552          * If there's not enough space, we will use the smaller of
1553          * stat_name_width (if set) and 5/8*width for the filename,
1554          * and the rest for constant elements + graph part, but no more
1555          * than stat_graph_width for the graph part.
1556          * (5/8 gives 50 for filename and 30 for the constant parts + graph
1557          * for the standard terminal size).
1558          *
1559          * In other words: stat_width limits the maximum width, and
1560          * stat_name_width fixes the maximum width of the filename,
1561          * and is also used to divide available columns if there
1562          * aren't enough.
1563          *
1564          * Binary files are displayed with "Bin XXX -> YYY bytes"
1565          * instead of the change count and graph. This part is treated
1566          * similarly to the graph part, except that it is not
1567          * "scaled". If total width is too small to accommodate the
1568          * guaranteed minimum width of the filename part and the
1569          * separators and this message, this message will "overflow"
1570          * making the line longer than the maximum width.
1571          */
1572
1573         if (options->stat_width == -1)
1574                 width = term_columns() - options->output_prefix_length;
1575         else
1576                 width = options->stat_width ? options->stat_width : 80;
1577         number_width = decimal_width(max_change) > number_width ?
1578                 decimal_width(max_change) : number_width;
1579
1580         if (options->stat_graph_width == -1)
1581                 options->stat_graph_width = diff_stat_graph_width;
1582
1583         /*
1584          * Guarantee 3/8*16==6 for the graph part
1585          * and 5/8*16==10 for the filename part
1586          */
1587         if (width < 16 + 6 + number_width)
1588                 width = 16 + 6 + number_width;
1589
1590         /*
1591          * First assign sizes that are wanted, ignoring available width.
1592          * strlen("Bin XXX -> YYY bytes") == bin_width, and the part
1593          * starting from "XXX" should fit in graph_width.
1594          */
1595         graph_width = max_change + 4 > bin_width ? max_change : bin_width - 4;
1596         if (options->stat_graph_width &&
1597             options->stat_graph_width < graph_width)
1598                 graph_width = options->stat_graph_width;
1599
1600         name_width = (options->stat_name_width > 0 &&
1601                       options->stat_name_width < max_len) ?
1602                 options->stat_name_width : max_len;
1603
1604         /*
1605          * Adjust adjustable widths not to exceed maximum width
1606          */
1607         if (name_width + number_width + 6 + graph_width > width) {
1608                 if (graph_width > width * 3/8 - number_width - 6) {
1609                         graph_width = width * 3/8 - number_width - 6;
1610                         if (graph_width < 6)
1611                                 graph_width = 6;
1612                 }
1613
1614                 if (options->stat_graph_width &&
1615                     graph_width > options->stat_graph_width)
1616                         graph_width = options->stat_graph_width;
1617                 if (name_width > width - number_width - 6 - graph_width)
1618                         name_width = width - number_width - 6 - graph_width;
1619                 else
1620                         graph_width = width - number_width - 6 - name_width;
1621         }
1622
1623         /*
1624          * From here name_width is the width of the name area,
1625          * and graph_width is the width of the graph area.
1626          * max_change is used to scale graph properly.
1627          */
1628         for (i = 0; i < count; i++) {
1629                 const char *prefix = "";
1630                 struct diffstat_file *file = data->files[i];
1631                 char *name = file->print_name;
1632                 uintmax_t added = file->added;
1633                 uintmax_t deleted = file->deleted;
1634                 int name_len;
1635
1636                 if (!file->is_interesting && (added + deleted == 0))
1637                         continue;
1638
1639                 /*
1640                  * "scale" the filename
1641                  */
1642                 len = name_width;
1643                 name_len = strlen(name);
1644                 if (name_width < name_len) {
1645                         char *slash;
1646                         prefix = "...";
1647                         len -= 3;
1648                         name += name_len - len;
1649                         slash = strchr(name, '/');
1650                         if (slash)
1651                                 name = slash;
1652                 }
1653
1654                 if (file->is_binary) {
1655                         fprintf(options->file, "%s", line_prefix);
1656                         show_name(options->file, prefix, name, len);
1657                         fprintf(options->file, " %*s", number_width, "Bin");
1658                         if (!added && !deleted) {
1659                                 putc('\n', options->file);
1660                                 continue;
1661                         }
1662                         fprintf(options->file, " %s%"PRIuMAX"%s",
1663                                 del_c, deleted, reset);
1664                         fprintf(options->file, " -> ");
1665                         fprintf(options->file, "%s%"PRIuMAX"%s",
1666                                 add_c, added, reset);
1667                         fprintf(options->file, " bytes");
1668                         fprintf(options->file, "\n");
1669                         continue;
1670                 }
1671                 else if (file->is_unmerged) {
1672                         fprintf(options->file, "%s", line_prefix);
1673                         show_name(options->file, prefix, name, len);
1674                         fprintf(options->file, " Unmerged\n");
1675                         continue;
1676                 }
1677
1678                 /*
1679                  * scale the add/delete
1680                  */
1681                 add = added;
1682                 del = deleted;
1683
1684                 if (graph_width <= max_change) {
1685                         int total = scale_linear(add + del, graph_width, max_change);
1686                         if (total < 2 && add && del)
1687                                 /* width >= 2 due to the sanity check */
1688                                 total = 2;
1689                         if (add < del) {
1690                                 add = scale_linear(add, graph_width, max_change);
1691                                 del = total - add;
1692                         } else {
1693                                 del = scale_linear(del, graph_width, max_change);
1694                                 add = total - del;
1695                         }
1696                 }
1697                 fprintf(options->file, "%s", line_prefix);
1698                 show_name(options->file, prefix, name, len);
1699                 fprintf(options->file, " %*"PRIuMAX"%s",
1700                         number_width, added + deleted,
1701                         added + deleted ? " " : "");
1702                 show_graph(options->file, '+', add, add_c, reset);
1703                 show_graph(options->file, '-', del, del_c, reset);
1704                 fprintf(options->file, "\n");
1705         }
1706
1707         for (i = 0; i < data->nr; i++) {
1708                 struct diffstat_file *file = data->files[i];
1709                 uintmax_t added = file->added;
1710                 uintmax_t deleted = file->deleted;
1711
1712                 if (file->is_unmerged ||
1713                     (!file->is_interesting && (added + deleted == 0))) {
1714                         total_files--;
1715                         continue;
1716                 }
1717
1718                 if (!file->is_binary) {
1719                         adds += added;
1720                         dels += deleted;
1721                 }
1722                 if (i < count)
1723                         continue;
1724                 if (!extra_shown)
1725                         fprintf(options->file, "%s ...\n", line_prefix);
1726                 extra_shown = 1;
1727         }
1728         fprintf(options->file, "%s", line_prefix);
1729         print_stat_summary(options->file, total_files, adds, dels);
1730 }
1731
1732 static void show_shortstats(struct diffstat_t *data, struct diff_options *options)
1733 {
1734         int i, adds = 0, dels = 0, total_files = data->nr;
1735
1736         if (data->nr == 0)
1737                 return;
1738
1739         for (i = 0; i < data->nr; i++) {
1740                 int added = data->files[i]->added;
1741                 int deleted= data->files[i]->deleted;
1742
1743                 if (data->files[i]->is_unmerged ||
1744                     (!data->files[i]->is_interesting && (added + deleted == 0))) {
1745                         total_files--;
1746                 } else if (!data->files[i]->is_binary) { /* don't count bytes */
1747                         adds += added;
1748                         dels += deleted;
1749                 }
1750         }
1751         fprintf(options->file, "%s", diff_line_prefix(options));
1752         print_stat_summary(options->file, total_files, adds, dels);
1753 }
1754
1755 static void show_numstat(struct diffstat_t *data, struct diff_options *options)
1756 {
1757         int i;
1758
1759         if (data->nr == 0)
1760                 return;
1761
1762         for (i = 0; i < data->nr; i++) {
1763                 struct diffstat_file *file = data->files[i];
1764
1765                 fprintf(options->file, "%s", diff_line_prefix(options));
1766
1767                 if (file->is_binary)
1768                         fprintf(options->file, "-\t-\t");
1769                 else
1770                         fprintf(options->file,
1771                                 "%"PRIuMAX"\t%"PRIuMAX"\t",
1772                                 file->added, file->deleted);
1773                 if (options->line_termination) {
1774                         fill_print_name(file);
1775                         if (!file->is_renamed)
1776                                 write_name_quoted(file->name, options->file,
1777                                                   options->line_termination);
1778                         else {
1779                                 fputs(file->print_name, options->file);
1780                                 putc(options->line_termination, options->file);
1781                         }
1782                 } else {
1783                         if (file->is_renamed) {
1784                                 putc('\0', options->file);
1785                                 write_name_quoted(file->from_name, options->file, '\0');
1786                         }
1787                         write_name_quoted(file->name, options->file, '\0');
1788                 }
1789         }
1790 }
1791
1792 struct dirstat_file {
1793         const char *name;
1794         unsigned long changed;
1795 };
1796
1797 struct dirstat_dir {
1798         struct dirstat_file *files;
1799         int alloc, nr, permille, cumulative;
1800 };
1801
1802 static long gather_dirstat(struct diff_options *opt, struct dirstat_dir *dir,
1803                 unsigned long changed, const char *base, int baselen)
1804 {
1805         unsigned long this_dir = 0;
1806         unsigned int sources = 0;
1807         const char *line_prefix = diff_line_prefix(opt);
1808
1809         while (dir->nr) {
1810                 struct dirstat_file *f = dir->files;
1811                 int namelen = strlen(f->name);
1812                 unsigned long this;
1813                 char *slash;
1814
1815                 if (namelen < baselen)
1816                         break;
1817                 if (memcmp(f->name, base, baselen))
1818                         break;
1819                 slash = strchr(f->name + baselen, '/');
1820                 if (slash) {
1821                         int newbaselen = slash + 1 - f->name;
1822                         this = gather_dirstat(opt, dir, changed, f->name, newbaselen);
1823                         sources++;
1824                 } else {
1825                         this = f->changed;
1826                         dir->files++;
1827                         dir->nr--;
1828                         sources += 2;
1829                 }
1830                 this_dir += this;
1831         }
1832
1833         /*
1834          * We don't report dirstat's for
1835          *  - the top level
1836          *  - or cases where everything came from a single directory
1837          *    under this directory (sources == 1).
1838          */
1839         if (baselen && sources != 1) {
1840                 if (this_dir) {
1841                         int permille = this_dir * 1000 / changed;
1842                         if (permille >= dir->permille) {
1843                                 fprintf(opt->file, "%s%4d.%01d%% %.*s\n", line_prefix,
1844                                         permille / 10, permille % 10, baselen, base);
1845                                 if (!dir->cumulative)
1846                                         return 0;
1847                         }
1848                 }
1849         }
1850         return this_dir;
1851 }
1852
1853 static int dirstat_compare(const void *_a, const void *_b)
1854 {
1855         const struct dirstat_file *a = _a;
1856         const struct dirstat_file *b = _b;
1857         return strcmp(a->name, b->name);
1858 }
1859
1860 static void show_dirstat(struct diff_options *options)
1861 {
1862         int i;
1863         unsigned long changed;
1864         struct dirstat_dir dir;
1865         struct diff_queue_struct *q = &diff_queued_diff;
1866
1867         dir.files = NULL;
1868         dir.alloc = 0;
1869         dir.nr = 0;
1870         dir.permille = options->dirstat_permille;
1871         dir.cumulative = DIFF_OPT_TST(options, DIRSTAT_CUMULATIVE);
1872
1873         changed = 0;
1874         for (i = 0; i < q->nr; i++) {
1875                 struct diff_filepair *p = q->queue[i];
1876                 const char *name;
1877                 unsigned long copied, added, damage;
1878                 int content_changed;
1879
1880                 name = p->two->path ? p->two->path : p->one->path;
1881
1882                 if (p->one->sha1_valid && p->two->sha1_valid)
1883                         content_changed = hashcmp(p->one->sha1, p->two->sha1);
1884                 else
1885                         content_changed = 1;
1886
1887                 if (!content_changed) {
1888                         /*
1889                          * The SHA1 has not changed, so pre-/post-content is
1890                          * identical. We can therefore skip looking at the
1891                          * file contents altogether.
1892                          */
1893                         damage = 0;
1894                         goto found_damage;
1895                 }
1896
1897                 if (DIFF_OPT_TST(options, DIRSTAT_BY_FILE)) {
1898                         /*
1899                          * In --dirstat-by-file mode, we don't really need to
1900                          * look at the actual file contents at all.
1901                          * The fact that the SHA1 changed is enough for us to
1902                          * add this file to the list of results
1903                          * (with each file contributing equal damage).
1904                          */
1905                         damage = 1;
1906                         goto found_damage;
1907                 }
1908
1909                 if (DIFF_FILE_VALID(p->one) && DIFF_FILE_VALID(p->two)) {
1910                         diff_populate_filespec(p->one, 0);
1911                         diff_populate_filespec(p->two, 0);
1912                         diffcore_count_changes(p->one, p->two, NULL, NULL, 0,
1913                                                &copied, &added);
1914                         diff_free_filespec_data(p->one);
1915                         diff_free_filespec_data(p->two);
1916                 } else if (DIFF_FILE_VALID(p->one)) {
1917                         diff_populate_filespec(p->one, 1);
1918                         copied = added = 0;
1919                         diff_free_filespec_data(p->one);
1920                 } else if (DIFF_FILE_VALID(p->two)) {
1921                         diff_populate_filespec(p->two, 1);
1922                         copied = 0;
1923                         added = p->two->size;
1924                         diff_free_filespec_data(p->two);
1925                 } else
1926                         continue;
1927
1928                 /*
1929                  * Original minus copied is the removed material,
1930                  * added is the new material.  They are both damages
1931                  * made to the preimage.
1932                  * If the resulting damage is zero, we know that
1933                  * diffcore_count_changes() considers the two entries to
1934                  * be identical, but since content_changed is true, we
1935                  * know that there must have been _some_ kind of change,
1936                  * so we force all entries to have damage > 0.
1937                  */
1938                 damage = (p->one->size - copied) + added;
1939                 if (!damage)
1940                         damage = 1;
1941
1942 found_damage:
1943                 ALLOC_GROW(dir.files, dir.nr + 1, dir.alloc);
1944                 dir.files[dir.nr].name = name;
1945                 dir.files[dir.nr].changed = damage;
1946                 changed += damage;
1947                 dir.nr++;
1948         }
1949
1950         /* This can happen even with many files, if everything was renames */
1951         if (!changed)
1952                 return;
1953
1954         /* Show all directories with more than x% of the changes */
1955         qsort(dir.files, dir.nr, sizeof(dir.files[0]), dirstat_compare);
1956         gather_dirstat(options, &dir, changed, "", 0);
1957 }
1958
1959 static void show_dirstat_by_line(struct diffstat_t *data, struct diff_options *options)
1960 {
1961         int i;
1962         unsigned long changed;
1963         struct dirstat_dir dir;
1964
1965         if (data->nr == 0)
1966                 return;
1967
1968         dir.files = NULL;
1969         dir.alloc = 0;
1970         dir.nr = 0;
1971         dir.permille = options->dirstat_permille;
1972         dir.cumulative = DIFF_OPT_TST(options, DIRSTAT_CUMULATIVE);
1973
1974         changed = 0;
1975         for (i = 0; i < data->nr; i++) {
1976                 struct diffstat_file *file = data->files[i];
1977                 unsigned long damage = file->added + file->deleted;
1978                 if (file->is_binary)
1979                         /*
1980                          * binary files counts bytes, not lines. Must find some
1981                          * way to normalize binary bytes vs. textual lines.
1982                          * The following heuristic assumes that there are 64
1983                          * bytes per "line".
1984                          * This is stupid and ugly, but very cheap...
1985                          */
1986                         damage = (damage + 63) / 64;
1987                 ALLOC_GROW(dir.files, dir.nr + 1, dir.alloc);
1988                 dir.files[dir.nr].name = file->name;
1989                 dir.files[dir.nr].changed = damage;
1990                 changed += damage;
1991                 dir.nr++;
1992         }
1993
1994         /* This can happen even with many files, if everything was renames */
1995         if (!changed)
1996                 return;
1997
1998         /* Show all directories with more than x% of the changes */
1999         qsort(dir.files, dir.nr, sizeof(dir.files[0]), dirstat_compare);
2000         gather_dirstat(options, &dir, changed, "", 0);
2001 }
2002
2003 static void free_diffstat_info(struct diffstat_t *diffstat)
2004 {
2005         int i;
2006         for (i = 0; i < diffstat->nr; i++) {
2007                 struct diffstat_file *f = diffstat->files[i];
2008                 if (f->name != f->print_name)
2009                         free(f->print_name);
2010                 free(f->name);
2011                 free(f->from_name);
2012                 free(f);
2013         }
2014         free(diffstat->files);
2015 }
2016
2017 struct checkdiff_t {
2018         const char *filename;
2019         int lineno;
2020         int conflict_marker_size;
2021         struct diff_options *o;
2022         unsigned ws_rule;
2023         unsigned status;
2024 };
2025
2026 static int is_conflict_marker(const char *line, int marker_size, unsigned long len)
2027 {
2028         char firstchar;
2029         int cnt;
2030
2031         if (len < marker_size + 1)
2032                 return 0;
2033         firstchar = line[0];
2034         switch (firstchar) {
2035         case '=': case '>': case '<': case '|':
2036                 break;
2037         default:
2038                 return 0;
2039         }
2040         for (cnt = 1; cnt < marker_size; cnt++)
2041                 if (line[cnt] != firstchar)
2042                         return 0;
2043         /* line[1] thru line[marker_size-1] are same as firstchar */
2044         if (len < marker_size + 1 || !isspace(line[marker_size]))
2045                 return 0;
2046         return 1;
2047 }
2048
2049 static void checkdiff_consume(void *priv, char *line, unsigned long len)
2050 {
2051         struct checkdiff_t *data = priv;
2052         int marker_size = data->conflict_marker_size;
2053         const char *ws = diff_get_color(data->o->use_color, DIFF_WHITESPACE);
2054         const char *reset = diff_get_color(data->o->use_color, DIFF_RESET);
2055         const char *set = diff_get_color(data->o->use_color, DIFF_FILE_NEW);
2056         char *err;
2057         const char *line_prefix;
2058
2059         assert(data->o);
2060         line_prefix = diff_line_prefix(data->o);
2061
2062         if (line[0] == '+') {
2063                 unsigned bad;
2064                 data->lineno++;
2065                 if (is_conflict_marker(line + 1, marker_size, len - 1)) {
2066                         data->status |= 1;
2067                         fprintf(data->o->file,
2068                                 "%s%s:%d: leftover conflict marker\n",
2069                                 line_prefix, data->filename, data->lineno);
2070                 }
2071                 bad = ws_check(line + 1, len - 1, data->ws_rule);
2072                 if (!bad)
2073                         return;
2074                 data->status |= bad;
2075                 err = whitespace_error_string(bad);
2076                 fprintf(data->o->file, "%s%s:%d: %s.\n",
2077                         line_prefix, data->filename, data->lineno, err);
2078                 free(err);
2079                 emit_line(data->o, set, reset, line, 1);
2080                 ws_check_emit(line + 1, len - 1, data->ws_rule,
2081                               data->o->file, set, reset, ws);
2082         } else if (line[0] == ' ') {
2083                 data->lineno++;
2084         } else if (line[0] == '@') {
2085                 char *plus = strchr(line, '+');
2086                 if (plus)
2087                         data->lineno = strtol(plus, NULL, 10) - 1;
2088                 else
2089                         die("invalid diff");
2090         }
2091 }
2092
2093 static unsigned char *deflate_it(char *data,
2094                                  unsigned long size,
2095                                  unsigned long *result_size)
2096 {
2097         int bound;
2098         unsigned char *deflated;
2099         git_zstream stream;
2100
2101         memset(&stream, 0, sizeof(stream));
2102         git_deflate_init(&stream, zlib_compression_level);
2103         bound = git_deflate_bound(&stream, size);
2104         deflated = xmalloc(bound);
2105         stream.next_out = deflated;
2106         stream.avail_out = bound;
2107
2108         stream.next_in = (unsigned char *)data;
2109         stream.avail_in = size;
2110         while (git_deflate(&stream, Z_FINISH) == Z_OK)
2111                 ; /* nothing */
2112         git_deflate_end(&stream);
2113         *result_size = stream.total_out;
2114         return deflated;
2115 }
2116
2117 static void emit_binary_diff_body(FILE *file, mmfile_t *one, mmfile_t *two,
2118                                   const char *prefix)
2119 {
2120         void *cp;
2121         void *delta;
2122         void *deflated;
2123         void *data;
2124         unsigned long orig_size;
2125         unsigned long delta_size;
2126         unsigned long deflate_size;
2127         unsigned long data_size;
2128
2129         /* We could do deflated delta, or we could do just deflated two,
2130          * whichever is smaller.
2131          */
2132         delta = NULL;
2133         deflated = deflate_it(two->ptr, two->size, &deflate_size);
2134         if (one->size && two->size) {
2135                 delta = diff_delta(one->ptr, one->size,
2136                                    two->ptr, two->size,
2137                                    &delta_size, deflate_size);
2138                 if (delta) {
2139                         void *to_free = delta;
2140                         orig_size = delta_size;
2141                         delta = deflate_it(delta, delta_size, &delta_size);
2142                         free(to_free);
2143                 }
2144         }
2145
2146         if (delta && delta_size < deflate_size) {
2147                 fprintf(file, "%sdelta %lu\n", prefix, orig_size);
2148                 free(deflated);
2149                 data = delta;
2150                 data_size = delta_size;
2151         }
2152         else {
2153                 fprintf(file, "%sliteral %lu\n", prefix, two->size);
2154                 free(delta);
2155                 data = deflated;
2156                 data_size = deflate_size;
2157         }
2158
2159         /* emit data encoded in base85 */
2160         cp = data;
2161         while (data_size) {
2162                 int bytes = (52 < data_size) ? 52 : data_size;
2163                 char line[70];
2164                 data_size -= bytes;
2165                 if (bytes <= 26)
2166                         line[0] = bytes + 'A' - 1;
2167                 else
2168                         line[0] = bytes - 26 + 'a' - 1;
2169                 encode_85(line + 1, cp, bytes);
2170                 cp = (char *) cp + bytes;
2171                 fprintf(file, "%s", prefix);
2172                 fputs(line, file);
2173                 fputc('\n', file);
2174         }
2175         fprintf(file, "%s\n", prefix);
2176         free(data);
2177 }
2178
2179 static void emit_binary_diff(FILE *file, mmfile_t *one, mmfile_t *two,
2180                              const char *prefix)
2181 {
2182         fprintf(file, "%sGIT binary patch\n", prefix);
2183         emit_binary_diff_body(file, one, two, prefix);
2184         emit_binary_diff_body(file, two, one, prefix);
2185 }
2186
2187 int diff_filespec_is_binary(struct diff_filespec *one)
2188 {
2189         if (one->is_binary == -1) {
2190                 diff_filespec_load_driver(one);
2191                 if (one->driver->binary != -1)
2192                         one->is_binary = one->driver->binary;
2193                 else {
2194                         if (!one->data && DIFF_FILE_VALID(one))
2195                                 diff_populate_filespec(one, 0);
2196                         if (one->data)
2197                                 one->is_binary = buffer_is_binary(one->data,
2198                                                 one->size);
2199                         if (one->is_binary == -1)
2200                                 one->is_binary = 0;
2201                 }
2202         }
2203         return one->is_binary;
2204 }
2205
2206 static const struct userdiff_funcname *diff_funcname_pattern(struct diff_filespec *one)
2207 {
2208         diff_filespec_load_driver(one);
2209         return one->driver->funcname.pattern ? &one->driver->funcname : NULL;
2210 }
2211
2212 void diff_set_mnemonic_prefix(struct diff_options *options, const char *a, const char *b)
2213 {
2214         if (!options->a_prefix)
2215                 options->a_prefix = a;
2216         if (!options->b_prefix)
2217                 options->b_prefix = b;
2218 }
2219
2220 struct userdiff_driver *get_textconv(struct diff_filespec *one)
2221 {
2222         if (!DIFF_FILE_VALID(one))
2223                 return NULL;
2224
2225         diff_filespec_load_driver(one);
2226         return userdiff_get_textconv(one->driver);
2227 }
2228
2229 static void builtin_diff(const char *name_a,
2230                          const char *name_b,
2231                          struct diff_filespec *one,
2232                          struct diff_filespec *two,
2233                          const char *xfrm_msg,
2234                          int must_show_header,
2235                          struct diff_options *o,
2236                          int complete_rewrite)
2237 {
2238         mmfile_t mf1, mf2;
2239         const char *lbl[2];
2240         char *a_one, *b_two;
2241         const char *meta = diff_get_color_opt(o, DIFF_METAINFO);
2242         const char *reset = diff_get_color_opt(o, DIFF_RESET);
2243         const char *a_prefix, *b_prefix;
2244         struct userdiff_driver *textconv_one = NULL;
2245         struct userdiff_driver *textconv_two = NULL;
2246         struct strbuf header = STRBUF_INIT;
2247         const char *line_prefix = diff_line_prefix(o);
2248
2249         if (DIFF_OPT_TST(o, SUBMODULE_LOG) &&
2250                         (!one->mode || S_ISGITLINK(one->mode)) &&
2251                         (!two->mode || S_ISGITLINK(two->mode))) {
2252                 const char *del = diff_get_color_opt(o, DIFF_FILE_OLD);
2253                 const char *add = diff_get_color_opt(o, DIFF_FILE_NEW);
2254                 show_submodule_summary(o->file, one->path ? one->path : two->path,
2255                                 line_prefix,
2256                                 one->sha1, two->sha1, two->dirty_submodule,
2257                                 meta, del, add, reset);
2258                 return;
2259         }
2260
2261         if (DIFF_OPT_TST(o, ALLOW_TEXTCONV)) {
2262                 textconv_one = get_textconv(one);
2263                 textconv_two = get_textconv(two);
2264         }
2265
2266         diff_set_mnemonic_prefix(o, "a/", "b/");
2267         if (DIFF_OPT_TST(o, REVERSE_DIFF)) {
2268                 a_prefix = o->b_prefix;
2269                 b_prefix = o->a_prefix;
2270         } else {
2271                 a_prefix = o->a_prefix;
2272                 b_prefix = o->b_prefix;
2273         }
2274
2275         /* Never use a non-valid filename anywhere if at all possible */
2276         name_a = DIFF_FILE_VALID(one) ? name_a : name_b;
2277         name_b = DIFF_FILE_VALID(two) ? name_b : name_a;
2278
2279         a_one = quote_two(a_prefix, name_a + (*name_a == '/'));
2280         b_two = quote_two(b_prefix, name_b + (*name_b == '/'));
2281         lbl[0] = DIFF_FILE_VALID(one) ? a_one : "/dev/null";
2282         lbl[1] = DIFF_FILE_VALID(two) ? b_two : "/dev/null";
2283         strbuf_addf(&header, "%s%sdiff --git %s %s%s\n", line_prefix, meta, a_one, b_two, reset);
2284         if (lbl[0][0] == '/') {
2285                 /* /dev/null */
2286                 strbuf_addf(&header, "%s%snew file mode %06o%s\n", line_prefix, meta, two->mode, reset);
2287                 if (xfrm_msg)
2288                         strbuf_addstr(&header, xfrm_msg);
2289                 must_show_header = 1;
2290         }
2291         else if (lbl[1][0] == '/') {
2292                 strbuf_addf(&header, "%s%sdeleted file mode %06o%s\n", line_prefix, meta, one->mode, reset);
2293                 if (xfrm_msg)
2294                         strbuf_addstr(&header, xfrm_msg);
2295                 must_show_header = 1;
2296         }
2297         else {
2298                 if (one->mode != two->mode) {
2299                         strbuf_addf(&header, "%s%sold mode %06o%s\n", line_prefix, meta, one->mode, reset);
2300                         strbuf_addf(&header, "%s%snew mode %06o%s\n", line_prefix, meta, two->mode, reset);
2301                         must_show_header = 1;
2302                 }
2303                 if (xfrm_msg)
2304                         strbuf_addstr(&header, xfrm_msg);
2305
2306                 /*
2307                  * we do not run diff between different kind
2308                  * of objects.
2309                  */
2310                 if ((one->mode ^ two->mode) & S_IFMT)
2311                         goto free_ab_and_return;
2312                 if (complete_rewrite &&
2313                     (textconv_one || !diff_filespec_is_binary(one)) &&
2314                     (textconv_two || !diff_filespec_is_binary(two))) {
2315                         fprintf(o->file, "%s", header.buf);
2316                         strbuf_reset(&header);
2317                         emit_rewrite_diff(name_a, name_b, one, two,
2318                                                 textconv_one, textconv_two, o);
2319                         o->found_changes = 1;
2320                         goto free_ab_and_return;
2321                 }
2322         }
2323
2324         if (o->irreversible_delete && lbl[1][0] == '/') {
2325                 fprintf(o->file, "%s", header.buf);
2326                 strbuf_reset(&header);
2327                 goto free_ab_and_return;
2328         } else if (!DIFF_OPT_TST(o, TEXT) &&
2329             ( (!textconv_one && diff_filespec_is_binary(one)) ||
2330               (!textconv_two && diff_filespec_is_binary(two)) )) {
2331                 if (fill_mmfile(&mf1, one) < 0 || fill_mmfile(&mf2, two) < 0)
2332                         die("unable to read files to diff");
2333                 /* Quite common confusing case */
2334                 if (mf1.size == mf2.size &&
2335                     !memcmp(mf1.ptr, mf2.ptr, mf1.size)) {
2336                         if (must_show_header)
2337                                 fprintf(o->file, "%s", header.buf);
2338                         goto free_ab_and_return;
2339                 }
2340                 fprintf(o->file, "%s", header.buf);
2341                 strbuf_reset(&header);
2342                 if (DIFF_OPT_TST(o, BINARY))
2343                         emit_binary_diff(o->file, &mf1, &mf2, line_prefix);
2344                 else
2345                         fprintf(o->file, "%sBinary files %s and %s differ\n",
2346                                 line_prefix, lbl[0], lbl[1]);
2347                 o->found_changes = 1;
2348         } else {
2349                 /* Crazy xdl interfaces.. */
2350                 const char *diffopts = getenv("GIT_DIFF_OPTS");
2351                 xpparam_t xpp;
2352                 xdemitconf_t xecfg;
2353                 struct emit_callback ecbdata;
2354                 const struct userdiff_funcname *pe;
2355
2356                 if (must_show_header) {
2357                         fprintf(o->file, "%s", header.buf);
2358                         strbuf_reset(&header);
2359                 }
2360
2361                 mf1.size = fill_textconv(textconv_one, one, &mf1.ptr);
2362                 mf2.size = fill_textconv(textconv_two, two, &mf2.ptr);
2363
2364                 pe = diff_funcname_pattern(one);
2365                 if (!pe)
2366                         pe = diff_funcname_pattern(two);
2367
2368                 memset(&xpp, 0, sizeof(xpp));
2369                 memset(&xecfg, 0, sizeof(xecfg));
2370                 memset(&ecbdata, 0, sizeof(ecbdata));
2371                 ecbdata.label_path = lbl;
2372                 ecbdata.color_diff = want_color(o->use_color);
2373                 ecbdata.found_changesp = &o->found_changes;
2374                 ecbdata.ws_rule = whitespace_rule(name_b);
2375                 if (ecbdata.ws_rule & WS_BLANK_AT_EOF)
2376                         check_blank_at_eof(&mf1, &mf2, &ecbdata);
2377                 ecbdata.opt = o;
2378                 ecbdata.header = header.len ? &header : NULL;
2379                 xpp.flags = o->xdl_opts;
2380                 xecfg.ctxlen = o->context;
2381                 xecfg.interhunkctxlen = o->interhunkcontext;
2382                 xecfg.flags = XDL_EMIT_FUNCNAMES;
2383                 if (DIFF_OPT_TST(o, FUNCCONTEXT))
2384                         xecfg.flags |= XDL_EMIT_FUNCCONTEXT;
2385                 if (pe)
2386                         xdiff_set_find_func(&xecfg, pe->pattern, pe->cflags);
2387                 if (!diffopts)
2388                         ;
2389                 else if (starts_with(diffopts, "--unified="))
2390                         xecfg.ctxlen = strtoul(diffopts + 10, NULL, 10);
2391                 else if (starts_with(diffopts, "-u"))
2392                         xecfg.ctxlen = strtoul(diffopts + 2, NULL, 10);
2393                 if (o->word_diff)
2394                         init_diff_words_data(&ecbdata, o, one, two);
2395                 xdi_diff_outf(&mf1, &mf2, fn_out_consume, &ecbdata,
2396                               &xpp, &xecfg);
2397                 if (o->word_diff)
2398                         free_diff_words_data(&ecbdata);
2399                 if (textconv_one)
2400                         free(mf1.ptr);
2401                 if (textconv_two)
2402                         free(mf2.ptr);
2403                 xdiff_clear_find_func(&xecfg);
2404         }
2405
2406  free_ab_and_return:
2407         strbuf_release(&header);
2408         diff_free_filespec_data(one);
2409         diff_free_filespec_data(two);
2410         free(a_one);
2411         free(b_two);
2412         return;
2413 }
2414
2415 static void builtin_diffstat(const char *name_a, const char *name_b,
2416                              struct diff_filespec *one,
2417                              struct diff_filespec *two,
2418                              struct diffstat_t *diffstat,
2419                              struct diff_options *o,
2420                              struct diff_filepair *p)
2421 {
2422         mmfile_t mf1, mf2;
2423         struct diffstat_file *data;
2424         int same_contents;
2425         int complete_rewrite = 0;
2426
2427         if (!DIFF_PAIR_UNMERGED(p)) {
2428                 if (p->status == DIFF_STATUS_MODIFIED && p->score)
2429                         complete_rewrite = 1;
2430         }
2431
2432         data = diffstat_add(diffstat, name_a, name_b);
2433         data->is_interesting = p->status != DIFF_STATUS_UNKNOWN;
2434
2435         if (!one || !two) {
2436                 data->is_unmerged = 1;
2437                 return;
2438         }
2439
2440         same_contents = !hashcmp(one->sha1, two->sha1);
2441
2442         if (diff_filespec_is_binary(one) || diff_filespec_is_binary(two)) {
2443                 data->is_binary = 1;
2444                 if (same_contents) {
2445                         data->added = 0;
2446                         data->deleted = 0;
2447                 } else {
2448                         data->added = diff_filespec_size(two);
2449                         data->deleted = diff_filespec_size(one);
2450                 }
2451         }
2452
2453         else if (complete_rewrite) {
2454                 diff_populate_filespec(one, 0);
2455                 diff_populate_filespec(two, 0);
2456                 data->deleted = count_lines(one->data, one->size);
2457                 data->added = count_lines(two->data, two->size);
2458         }
2459
2460         else if (!same_contents) {
2461                 /* Crazy xdl interfaces.. */
2462                 xpparam_t xpp;
2463                 xdemitconf_t xecfg;
2464
2465                 if (fill_mmfile(&mf1, one) < 0 || fill_mmfile(&mf2, two) < 0)
2466                         die("unable to read files to diff");
2467
2468                 memset(&xpp, 0, sizeof(xpp));
2469                 memset(&xecfg, 0, sizeof(xecfg));
2470                 xpp.flags = o->xdl_opts;
2471                 xecfg.ctxlen = o->context;
2472                 xecfg.interhunkctxlen = o->interhunkcontext;
2473                 xdi_diff_outf(&mf1, &mf2, diffstat_consume, diffstat,
2474                               &xpp, &xecfg);
2475         }
2476
2477         diff_free_filespec_data(one);
2478         diff_free_filespec_data(two);
2479 }
2480
2481 static void builtin_checkdiff(const char *name_a, const char *name_b,
2482                               const char *attr_path,
2483                               struct diff_filespec *one,
2484                               struct diff_filespec *two,
2485                               struct diff_options *o)
2486 {
2487         mmfile_t mf1, mf2;
2488         struct checkdiff_t data;
2489
2490         if (!two)
2491                 return;
2492
2493         memset(&data, 0, sizeof(data));
2494         data.filename = name_b ? name_b : name_a;
2495         data.lineno = 0;
2496         data.o = o;
2497         data.ws_rule = whitespace_rule(attr_path);
2498         data.conflict_marker_size = ll_merge_marker_size(attr_path);
2499
2500         if (fill_mmfile(&mf1, one) < 0 || fill_mmfile(&mf2, two) < 0)
2501                 die("unable to read files to diff");
2502
2503         /*
2504          * All the other codepaths check both sides, but not checking
2505          * the "old" side here is deliberate.  We are checking the newly
2506          * introduced changes, and as long as the "new" side is text, we
2507          * can and should check what it introduces.
2508          */
2509         if (diff_filespec_is_binary(two))
2510                 goto free_and_return;
2511         else {
2512                 /* Crazy xdl interfaces.. */
2513                 xpparam_t xpp;
2514                 xdemitconf_t xecfg;
2515
2516                 memset(&xpp, 0, sizeof(xpp));
2517                 memset(&xecfg, 0, sizeof(xecfg));
2518                 xecfg.ctxlen = 1; /* at least one context line */
2519                 xpp.flags = 0;
2520                 xdi_diff_outf(&mf1, &mf2, checkdiff_consume, &data,
2521                               &xpp, &xecfg);
2522
2523                 if (data.ws_rule & WS_BLANK_AT_EOF) {
2524                         struct emit_callback ecbdata;
2525                         int blank_at_eof;
2526
2527                         ecbdata.ws_rule = data.ws_rule;
2528                         check_blank_at_eof(&mf1, &mf2, &ecbdata);
2529                         blank_at_eof = ecbdata.blank_at_eof_in_postimage;
2530
2531                         if (blank_at_eof) {
2532                                 static char *err;
2533                                 if (!err)
2534                                         err = whitespace_error_string(WS_BLANK_AT_EOF);
2535                                 fprintf(o->file, "%s:%d: %s.\n",
2536                                         data.filename, blank_at_eof, err);
2537                                 data.status = 1; /* report errors */
2538                         }
2539                 }
2540         }
2541  free_and_return:
2542         diff_free_filespec_data(one);
2543         diff_free_filespec_data(two);
2544         if (data.status)
2545                 DIFF_OPT_SET(o, CHECK_FAILED);
2546 }
2547
2548 struct diff_filespec *alloc_filespec(const char *path)
2549 {
2550         int namelen = strlen(path);
2551         struct diff_filespec *spec = xmalloc(sizeof(*spec) + namelen + 1);
2552
2553         memset(spec, 0, sizeof(*spec));
2554         spec->path = (char *)(spec + 1);
2555         memcpy(spec->path, path, namelen+1);
2556         spec->count = 1;
2557         spec->is_binary = -1;
2558         return spec;
2559 }
2560
2561 void free_filespec(struct diff_filespec *spec)
2562 {
2563         if (!--spec->count) {
2564                 diff_free_filespec_data(spec);
2565                 free(spec);
2566         }
2567 }
2568
2569 void fill_filespec(struct diff_filespec *spec, const unsigned char *sha1,
2570                    int sha1_valid, unsigned short mode)
2571 {
2572         if (mode) {
2573                 spec->mode = canon_mode(mode);
2574                 hashcpy(spec->sha1, sha1);
2575                 spec->sha1_valid = sha1_valid;
2576         }
2577 }
2578
2579 /*
2580  * Given a name and sha1 pair, if the index tells us the file in
2581  * the work tree has that object contents, return true, so that
2582  * prepare_temp_file() does not have to inflate and extract.
2583  */
2584 static int reuse_worktree_file(const char *name, const unsigned char *sha1, int want_file)
2585 {
2586         const struct cache_entry *ce;
2587         struct stat st;
2588         int pos, len;
2589
2590         /*
2591          * We do not read the cache ourselves here, because the
2592          * benchmark with my previous version that always reads cache
2593          * shows that it makes things worse for diff-tree comparing
2594          * two linux-2.6 kernel trees in an already checked out work
2595          * tree.  This is because most diff-tree comparisons deal with
2596          * only a small number of files, while reading the cache is
2597          * expensive for a large project, and its cost outweighs the
2598          * savings we get by not inflating the object to a temporary
2599          * file.  Practically, this code only helps when we are used
2600          * by diff-cache --cached, which does read the cache before
2601          * calling us.
2602          */
2603         if (!active_cache)
2604                 return 0;
2605
2606         /* We want to avoid the working directory if our caller
2607          * doesn't need the data in a normal file, this system
2608          * is rather slow with its stat/open/mmap/close syscalls,
2609          * and the object is contained in a pack file.  The pack
2610          * is probably already open and will be faster to obtain
2611          * the data through than the working directory.  Loose
2612          * objects however would tend to be slower as they need
2613          * to be individually opened and inflated.
2614          */
2615         if (!FAST_WORKING_DIRECTORY && !want_file && has_sha1_pack(sha1))
2616                 return 0;
2617
2618         len = strlen(name);
2619         pos = cache_name_pos(name, len);
2620         if (pos < 0)
2621                 return 0;
2622         ce = active_cache[pos];
2623
2624         /*
2625          * This is not the sha1 we are looking for, or
2626          * unreusable because it is not a regular file.
2627          */
2628         if (hashcmp(sha1, ce->sha1) || !S_ISREG(ce->ce_mode))
2629                 return 0;
2630
2631         /*
2632          * If ce is marked as "assume unchanged", there is no
2633          * guarantee that work tree matches what we are looking for.
2634          */
2635         if ((ce->ce_flags & CE_VALID) || ce_skip_worktree(ce))
2636                 return 0;
2637
2638         /*
2639          * If ce matches the file in the work tree, we can reuse it.
2640          */
2641         if (ce_uptodate(ce) ||
2642             (!lstat(name, &st) && !ce_match_stat(ce, &st, 0)))
2643                 return 1;
2644
2645         return 0;
2646 }
2647
2648 static int diff_populate_gitlink(struct diff_filespec *s, int size_only)
2649 {
2650         int len;
2651         char *data = xmalloc(100), *dirty = "";
2652
2653         /* Are we looking at the work tree? */
2654         if (s->dirty_submodule)
2655                 dirty = "-dirty";
2656
2657         len = snprintf(data, 100,
2658                        "Subproject commit %s%s\n", sha1_to_hex(s->sha1), dirty);
2659         s->data = data;
2660         s->size = len;
2661         s->should_free = 1;
2662         if (size_only) {
2663                 s->data = NULL;
2664                 free(data);
2665         }
2666         return 0;
2667 }
2668
2669 /*
2670  * While doing rename detection and pickaxe operation, we may need to
2671  * grab the data for the blob (or file) for our own in-core comparison.
2672  * diff_filespec has data and size fields for this purpose.
2673  */
2674 int diff_populate_filespec(struct diff_filespec *s, int size_only)
2675 {
2676         int err = 0;
2677         /*
2678          * demote FAIL to WARN to allow inspecting the situation
2679          * instead of refusing.
2680          */
2681         enum safe_crlf crlf_warn = (safe_crlf == SAFE_CRLF_FAIL
2682                                     ? SAFE_CRLF_WARN
2683                                     : safe_crlf);
2684
2685         if (!DIFF_FILE_VALID(s))
2686                 die("internal error: asking to populate invalid file.");
2687         if (S_ISDIR(s->mode))
2688                 return -1;
2689
2690         if (s->data)
2691                 return 0;
2692
2693         if (size_only && 0 < s->size)
2694                 return 0;
2695
2696         if (S_ISGITLINK(s->mode))
2697                 return diff_populate_gitlink(s, size_only);
2698
2699         if (!s->sha1_valid ||
2700             reuse_worktree_file(s->path, s->sha1, 0)) {
2701                 struct strbuf buf = STRBUF_INIT;
2702                 struct stat st;
2703                 int fd;
2704
2705                 if (lstat(s->path, &st) < 0) {
2706                         if (errno == ENOENT) {
2707                         err_empty:
2708                                 err = -1;
2709                         empty:
2710                                 s->data = (char *)"";
2711                                 s->size = 0;
2712                                 return err;
2713                         }
2714                 }
2715                 s->size = xsize_t(st.st_size);
2716                 if (!s->size)
2717                         goto empty;
2718                 if (S_ISLNK(st.st_mode)) {
2719                         struct strbuf sb = STRBUF_INIT;
2720
2721                         if (strbuf_readlink(&sb, s->path, s->size))
2722                                 goto err_empty;
2723                         s->size = sb.len;
2724                         s->data = strbuf_detach(&sb, NULL);
2725                         s->should_free = 1;
2726                         return 0;
2727                 }
2728                 if (size_only)
2729                         return 0;
2730                 fd = open(s->path, O_RDONLY);
2731                 if (fd < 0)
2732                         goto err_empty;
2733                 s->data = xmmap(NULL, s->size, PROT_READ, MAP_PRIVATE, fd, 0);
2734                 close(fd);
2735                 s->should_munmap = 1;
2736
2737                 /*
2738                  * Convert from working tree format to canonical git format
2739                  */
2740                 if (convert_to_git(s->path, s->data, s->size, &buf, crlf_warn)) {
2741                         size_t size = 0;
2742                         munmap(s->data, s->size);
2743                         s->should_munmap = 0;
2744                         s->data = strbuf_detach(&buf, &size);
2745                         s->size = size;
2746                         s->should_free = 1;
2747                 }
2748         }
2749         else {
2750                 enum object_type type;
2751                 if (size_only) {
2752                         type = sha1_object_info(s->sha1, &s->size);
2753                         if (type < 0)
2754                                 die("unable to read %s", sha1_to_hex(s->sha1));
2755                 } else {
2756                         s->data = read_sha1_file(s->sha1, &type, &s->size);
2757                         if (!s->data)
2758                                 die("unable to read %s", sha1_to_hex(s->sha1));
2759                         s->should_free = 1;
2760                 }
2761         }
2762         return 0;
2763 }
2764
2765 void diff_free_filespec_blob(struct diff_filespec *s)
2766 {
2767         if (s->should_free)
2768                 free(s->data);
2769         else if (s->should_munmap)
2770                 munmap(s->data, s->size);
2771
2772         if (s->should_free || s->should_munmap) {
2773                 s->should_free = s->should_munmap = 0;
2774                 s->data = NULL;
2775         }
2776 }
2777
2778 void diff_free_filespec_data(struct diff_filespec *s)
2779 {
2780         diff_free_filespec_blob(s);
2781         free(s->cnt_data);
2782         s->cnt_data = NULL;
2783 }
2784
2785 static void prep_temp_blob(const char *path, struct diff_tempfile *temp,
2786                            void *blob,
2787                            unsigned long size,
2788                            const unsigned char *sha1,
2789                            int mode)
2790 {
2791         int fd;
2792         struct strbuf buf = STRBUF_INIT;
2793         struct strbuf template = STRBUF_INIT;
2794         char *path_dup = xstrdup(path);
2795         const char *base = basename(path_dup);
2796
2797         /* Generate "XXXXXX_basename.ext" */
2798         strbuf_addstr(&template, "XXXXXX_");
2799         strbuf_addstr(&template, base);
2800
2801         fd = git_mkstemps(temp->tmp_path, PATH_MAX, template.buf,
2802                         strlen(base) + 1);
2803         if (fd < 0)
2804                 die_errno("unable to create temp-file");
2805         if (convert_to_working_tree(path,
2806                         (const char *)blob, (size_t)size, &buf)) {
2807                 blob = buf.buf;
2808                 size = buf.len;
2809         }
2810         if (write_in_full(fd, blob, size) != size)
2811                 die_errno("unable to write temp-file");
2812         close(fd);
2813         temp->name = temp->tmp_path;
2814         strcpy(temp->hex, sha1_to_hex(sha1));
2815         temp->hex[40] = 0;
2816         sprintf(temp->mode, "%06o", mode);
2817         strbuf_release(&buf);
2818         strbuf_release(&template);
2819         free(path_dup);
2820 }
2821
2822 static struct diff_tempfile *prepare_temp_file(const char *name,
2823                 struct diff_filespec *one)
2824 {
2825         struct diff_tempfile *temp = claim_diff_tempfile();
2826
2827         if (!DIFF_FILE_VALID(one)) {
2828         not_a_valid_file:
2829                 /* A '-' entry produces this for file-2, and
2830                  * a '+' entry produces this for file-1.
2831                  */
2832                 temp->name = "/dev/null";
2833                 strcpy(temp->hex, ".");
2834                 strcpy(temp->mode, ".");
2835                 return temp;
2836         }
2837
2838         if (!remove_tempfile_installed) {
2839                 atexit(remove_tempfile);
2840                 sigchain_push_common(remove_tempfile_on_signal);
2841                 remove_tempfile_installed = 1;
2842         }
2843
2844         if (!S_ISGITLINK(one->mode) &&
2845             (!one->sha1_valid ||
2846              reuse_worktree_file(name, one->sha1, 1))) {
2847                 struct stat st;
2848                 if (lstat(name, &st) < 0) {
2849                         if (errno == ENOENT)
2850                                 goto not_a_valid_file;
2851                         die_errno("stat(%s)", name);
2852                 }
2853                 if (S_ISLNK(st.st_mode)) {
2854                         struct strbuf sb = STRBUF_INIT;
2855                         if (strbuf_readlink(&sb, name, st.st_size) < 0)
2856                                 die_errno("readlink(%s)", name);
2857                         prep_temp_blob(name, temp, sb.buf, sb.len,
2858                                        (one->sha1_valid ?
2859                                         one->sha1 : null_sha1),
2860                                        (one->sha1_valid ?
2861                                         one->mode : S_IFLNK));
2862                         strbuf_release(&sb);
2863                 }
2864                 else {
2865                         /* we can borrow from the file in the work tree */
2866                         temp->name = name;
2867                         if (!one->sha1_valid)
2868                                 strcpy(temp->hex, sha1_to_hex(null_sha1));
2869                         else
2870                                 strcpy(temp->hex, sha1_to_hex(one->sha1));
2871                         /* Even though we may sometimes borrow the
2872                          * contents from the work tree, we always want
2873                          * one->mode.  mode is trustworthy even when
2874                          * !(one->sha1_valid), as long as
2875                          * DIFF_FILE_VALID(one).
2876                          */
2877                         sprintf(temp->mode, "%06o", one->mode);
2878                 }
2879                 return temp;
2880         }
2881         else {
2882                 if (diff_populate_filespec(one, 0))
2883                         die("cannot read data blob for %s", one->path);
2884                 prep_temp_blob(name, temp, one->data, one->size,
2885                                one->sha1, one->mode);
2886         }
2887         return temp;
2888 }
2889
2890 /* An external diff command takes:
2891  *
2892  * diff-cmd name infile1 infile1-sha1 infile1-mode \
2893  *               infile2 infile2-sha1 infile2-mode [ rename-to ]
2894  *
2895  */
2896 static void run_external_diff(const char *pgm,
2897                               const char *name,
2898                               const char *other,
2899                               struct diff_filespec *one,
2900                               struct diff_filespec *two,
2901                               const char *xfrm_msg,
2902                               int complete_rewrite,
2903                               struct diff_options *o)
2904 {
2905         const char *spawn_arg[10];
2906         int retval;
2907         const char **arg = &spawn_arg[0];
2908         struct diff_queue_struct *q = &diff_queued_diff;
2909         const char *env[3] = { NULL };
2910         char env_counter[50];
2911         char env_total[50];
2912
2913         if (one && two) {
2914                 struct diff_tempfile *temp_one, *temp_two;
2915                 const char *othername = (other ? other : name);
2916                 temp_one = prepare_temp_file(name, one);
2917                 temp_two = prepare_temp_file(othername, two);
2918                 *arg++ = pgm;
2919                 *arg++ = name;
2920                 *arg++ = temp_one->name;
2921                 *arg++ = temp_one->hex;
2922                 *arg++ = temp_one->mode;
2923                 *arg++ = temp_two->name;
2924                 *arg++ = temp_two->hex;
2925                 *arg++ = temp_two->mode;
2926                 if (other) {
2927                         *arg++ = other;
2928                         *arg++ = xfrm_msg;
2929                 }
2930         } else {
2931                 *arg++ = pgm;
2932                 *arg++ = name;
2933         }
2934         *arg = NULL;
2935         fflush(NULL);
2936
2937         env[0] = env_counter;
2938         snprintf(env_counter, sizeof(env_counter), "GIT_DIFF_PATH_COUNTER=%d",
2939                  ++o->diff_path_counter);
2940         env[1] = env_total;
2941         snprintf(env_total, sizeof(env_total), "GIT_DIFF_PATH_TOTAL=%d", q->nr);
2942
2943         retval = run_command_v_opt_cd_env(spawn_arg, RUN_USING_SHELL, NULL, env);
2944         remove_tempfile();
2945         if (retval) {
2946                 fprintf(stderr, "external diff died, stopping at %s.\n", name);
2947                 exit(1);
2948         }
2949 }
2950
2951 static int similarity_index(struct diff_filepair *p)
2952 {
2953         return p->score * 100 / MAX_SCORE;
2954 }
2955
2956 static void fill_metainfo(struct strbuf *msg,
2957                           const char *name,
2958                           const char *other,
2959                           struct diff_filespec *one,
2960                           struct diff_filespec *two,
2961                           struct diff_options *o,
2962                           struct diff_filepair *p,
2963                           int *must_show_header,
2964                           int use_color)
2965 {
2966         const char *set = diff_get_color(use_color, DIFF_METAINFO);
2967         const char *reset = diff_get_color(use_color, DIFF_RESET);
2968         const char *line_prefix = diff_line_prefix(o);
2969
2970         *must_show_header = 1;
2971         strbuf_init(msg, PATH_MAX * 2 + 300);
2972         switch (p->status) {
2973         case DIFF_STATUS_COPIED:
2974                 strbuf_addf(msg, "%s%ssimilarity index %d%%",
2975                             line_prefix, set, similarity_index(p));
2976                 strbuf_addf(msg, "%s\n%s%scopy from ",
2977                             reset,  line_prefix, set);
2978                 quote_c_style(name, msg, NULL, 0);
2979                 strbuf_addf(msg, "%s\n%s%scopy to ", reset, line_prefix, set);
2980                 quote_c_style(other, msg, NULL, 0);
2981                 strbuf_addf(msg, "%s\n", reset);
2982                 break;
2983         case DIFF_STATUS_RENAMED:
2984                 strbuf_addf(msg, "%s%ssimilarity index %d%%",
2985                             line_prefix, set, similarity_index(p));
2986                 strbuf_addf(msg, "%s\n%s%srename from ",
2987                             reset, line_prefix, set);
2988                 quote_c_style(name, msg, NULL, 0);
2989                 strbuf_addf(msg, "%s\n%s%srename to ",
2990                             reset, line_prefix, set);
2991                 quote_c_style(other, msg, NULL, 0);
2992                 strbuf_addf(msg, "%s\n", reset);
2993                 break;
2994         case DIFF_STATUS_MODIFIED:
2995                 if (p->score) {
2996                         strbuf_addf(msg, "%s%sdissimilarity index %d%%%s\n",
2997                                     line_prefix,
2998                                     set, similarity_index(p), reset);
2999                         break;
3000                 }
3001                 /* fallthru */
3002         default:
3003                 *must_show_header = 0;
3004         }
3005         if (one && two && hashcmp(one->sha1, two->sha1)) {
3006                 int abbrev = DIFF_OPT_TST(o, FULL_INDEX) ? 40 : DEFAULT_ABBREV;
3007
3008                 if (DIFF_OPT_TST(o, BINARY)) {
3009                         mmfile_t mf;
3010                         if ((!fill_mmfile(&mf, one) && diff_filespec_is_binary(one)) ||
3011                             (!fill_mmfile(&mf, two) && diff_filespec_is_binary(two)))
3012                                 abbrev = 40;
3013                 }
3014                 strbuf_addf(msg, "%s%sindex %s..", line_prefix, set,
3015                             find_unique_abbrev(one->sha1, abbrev));
3016                 strbuf_addstr(msg, find_unique_abbrev(two->sha1, abbrev));
3017                 if (one->mode == two->mode)
3018                         strbuf_addf(msg, " %06o", one->mode);
3019                 strbuf_addf(msg, "%s\n", reset);
3020         }
3021 }
3022
3023 static void run_diff_cmd(const char *pgm,
3024                          const char *name,
3025                          const char *other,
3026                          const char *attr_path,
3027                          struct diff_filespec *one,
3028                          struct diff_filespec *two,
3029                          struct strbuf *msg,
3030                          struct diff_options *o,
3031                          struct diff_filepair *p)
3032 {
3033         const char *xfrm_msg = NULL;
3034         int complete_rewrite = (p->status == DIFF_STATUS_MODIFIED) && p->score;
3035         int must_show_header = 0;
3036
3037
3038         if (DIFF_OPT_TST(o, ALLOW_EXTERNAL)) {
3039                 struct userdiff_driver *drv = userdiff_find_by_path(attr_path);
3040                 if (drv && drv->external)
3041                         pgm = drv->external;
3042         }
3043
3044         if (msg) {
3045                 /*
3046                  * don't use colors when the header is intended for an
3047                  * external diff driver
3048                  */
3049                 fill_metainfo(msg, name, other, one, two, o, p,
3050                               &must_show_header,
3051                               want_color(o->use_color) && !pgm);
3052                 xfrm_msg = msg->len ? msg->buf : NULL;
3053         }
3054
3055         if (pgm) {
3056                 run_external_diff(pgm, name, other, one, two, xfrm_msg,
3057                                   complete_rewrite, o);
3058                 return;
3059         }
3060         if (one && two)
3061                 builtin_diff(name, other ? other : name,
3062                              one, two, xfrm_msg, must_show_header,
3063                              o, complete_rewrite);
3064         else
3065                 fprintf(o->file, "* Unmerged path %s\n", name);
3066 }
3067
3068 static void diff_fill_sha1_info(struct diff_filespec *one)
3069 {
3070         if (DIFF_FILE_VALID(one)) {
3071                 if (!one->sha1_valid) {
3072                         struct stat st;
3073                         if (one->is_stdin) {
3074                                 hashcpy(one->sha1, null_sha1);
3075                                 return;
3076                         }
3077                         if (lstat(one->path, &st) < 0)
3078                                 die_errno("stat '%s'", one->path);
3079                         if (index_path(one->sha1, one->path, &st, 0))
3080                                 die("cannot hash %s", one->path);
3081                 }
3082         }
3083         else
3084                 hashclr(one->sha1);
3085 }
3086
3087 static void strip_prefix(int prefix_length, const char **namep, const char **otherp)
3088 {
3089         /* Strip the prefix but do not molest /dev/null and absolute paths */
3090         if (*namep && **namep != '/') {
3091                 *namep += prefix_length;
3092                 if (**namep == '/')
3093                         ++*namep;
3094         }
3095         if (*otherp && **otherp != '/') {
3096                 *otherp += prefix_length;
3097                 if (**otherp == '/')
3098                         ++*otherp;
3099         }
3100 }
3101
3102 static void run_diff(struct diff_filepair *p, struct diff_options *o)
3103 {
3104         const char *pgm = external_diff();
3105         struct strbuf msg;
3106         struct diff_filespec *one = p->one;
3107         struct diff_filespec *two = p->two;
3108         const char *name;
3109         const char *other;
3110         const char *attr_path;
3111
3112         name  = p->one->path;
3113         other = (strcmp(name, p->two->path) ? p->two->path : NULL);
3114         attr_path = name;
3115         if (o->prefix_length)
3116                 strip_prefix(o->prefix_length, &name, &other);
3117
3118         if (!DIFF_OPT_TST(o, ALLOW_EXTERNAL))
3119                 pgm = NULL;
3120
3121         if (DIFF_PAIR_UNMERGED(p)) {
3122                 run_diff_cmd(pgm, name, NULL, attr_path,
3123                              NULL, NULL, NULL, o, p);
3124                 return;
3125         }
3126
3127         diff_fill_sha1_info(one);
3128         diff_fill_sha1_info(two);
3129
3130         if (!pgm &&
3131             DIFF_FILE_VALID(one) && DIFF_FILE_VALID(two) &&
3132             (S_IFMT & one->mode) != (S_IFMT & two->mode)) {
3133                 /*
3134                  * a filepair that changes between file and symlink
3135                  * needs to be split into deletion and creation.
3136                  */
3137                 struct diff_filespec *null = alloc_filespec(two->path);
3138                 run_diff_cmd(NULL, name, other, attr_path,
3139                              one, null, &msg, o, p);
3140                 free(null);
3141                 strbuf_release(&msg);
3142
3143                 null = alloc_filespec(one->path);
3144                 run_diff_cmd(NULL, name, other, attr_path,
3145                              null, two, &msg, o, p);
3146                 free(null);
3147         }
3148         else
3149                 run_diff_cmd(pgm, name, other, attr_path,
3150                              one, two, &msg, o, p);
3151
3152         strbuf_release(&msg);
3153 }
3154
3155 static void run_diffstat(struct diff_filepair *p, struct diff_options *o,
3156                          struct diffstat_t *diffstat)
3157 {
3158         const char *name;
3159         const char *other;
3160
3161         if (DIFF_PAIR_UNMERGED(p)) {
3162                 /* unmerged */
3163                 builtin_diffstat(p->one->path, NULL, NULL, NULL, diffstat, o, p);
3164                 return;
3165         }
3166
3167         name = p->one->path;
3168         other = (strcmp(name, p->two->path) ? p->two->path : NULL);
3169
3170         if (o->prefix_length)
3171                 strip_prefix(o->prefix_length, &name, &other);
3172
3173         diff_fill_sha1_info(p->one);
3174         diff_fill_sha1_info(p->two);
3175
3176         builtin_diffstat(name, other, p->one, p->two, diffstat, o, p);
3177 }
3178
3179 static void run_checkdiff(struct diff_filepair *p, struct diff_options *o)
3180 {
3181         const char *name;
3182         const char *other;
3183         const char *attr_path;
3184
3185         if (DIFF_PAIR_UNMERGED(p)) {
3186                 /* unmerged */
3187                 return;
3188         }
3189
3190         name = p->one->path;
3191         other = (strcmp(name, p->two->path) ? p->two->path : NULL);
3192         attr_path = other ? other : name;
3193
3194         if (o->prefix_length)
3195                 strip_prefix(o->prefix_length, &name, &other);
3196
3197         diff_fill_sha1_info(p->one);
3198         diff_fill_sha1_info(p->two);
3199
3200         builtin_checkdiff(name, other, attr_path, p->one, p->two, o);
3201 }
3202
3203 void diff_setup(struct diff_options *options)
3204 {
3205         memcpy(options, &default_diff_options, sizeof(*options));
3206
3207         options->file = stdout;
3208
3209         options->line_termination = '\n';
3210         options->break_opt = -1;
3211         options->rename_limit = -1;
3212         options->dirstat_permille = diff_dirstat_permille_default;
3213         options->context = diff_context_default;
3214         DIFF_OPT_SET(options, RENAME_EMPTY);
3215
3216         options->change = diff_change;
3217         options->add_remove = diff_addremove;
3218         options->use_color = diff_use_color_default;
3219         options->detect_rename = diff_detect_rename_default;
3220         options->xdl_opts |= diff_algorithm;
3221
3222         options->orderfile = diff_order_file_cfg;
3223
3224         if (diff_no_prefix) {
3225                 options->a_prefix = options->b_prefix = "";
3226         } else if (!diff_mnemonic_prefix) {
3227                 options->a_prefix = "a/";
3228                 options->b_prefix = "b/";
3229         }
3230 }
3231
3232 void diff_setup_done(struct diff_options *options)
3233 {
3234         int count = 0;
3235
3236         if (options->set_default)
3237                 options->set_default(options);
3238
3239         if (options->output_format & DIFF_FORMAT_NAME)
3240                 count++;
3241         if (options->output_format & DIFF_FORMAT_NAME_STATUS)
3242                 count++;
3243         if (options->output_format & DIFF_FORMAT_CHECKDIFF)
3244                 count++;
3245         if (options->output_format & DIFF_FORMAT_NO_OUTPUT)
3246                 count++;
3247         if (count > 1)
3248                 die("--name-only, --name-status, --check and -s are mutually exclusive");
3249
3250         /*
3251          * Most of the time we can say "there are changes"
3252          * only by checking if there are changed paths, but
3253          * --ignore-whitespace* options force us to look
3254          * inside contents.
3255          */
3256
3257         if (DIFF_XDL_TST(options, IGNORE_WHITESPACE) ||
3258             DIFF_XDL_TST(options, IGNORE_WHITESPACE_CHANGE) ||
3259             DIFF_XDL_TST(options, IGNORE_WHITESPACE_AT_EOL))
3260                 DIFF_OPT_SET(options, DIFF_FROM_CONTENTS);
3261         else
3262                 DIFF_OPT_CLR(options, DIFF_FROM_CONTENTS);
3263
3264         if (DIFF_OPT_TST(options, FIND_COPIES_HARDER))
3265                 options->detect_rename = DIFF_DETECT_COPY;
3266
3267         if (!DIFF_OPT_TST(options, RELATIVE_NAME))
3268                 options->prefix = NULL;
3269         if (options->prefix)
3270                 options->prefix_length = strlen(options->prefix);
3271         else
3272                 options->prefix_length = 0;
3273
3274         if (options->output_format & (DIFF_FORMAT_NAME |
3275                                       DIFF_FORMAT_NAME_STATUS |
3276                                       DIFF_FORMAT_CHECKDIFF |
3277                                       DIFF_FORMAT_NO_OUTPUT))
3278                 options->output_format &= ~(DIFF_FORMAT_RAW |
3279                                             DIFF_FORMAT_NUMSTAT |
3280                                             DIFF_FORMAT_DIFFSTAT |
3281                                             DIFF_FORMAT_SHORTSTAT |
3282                                             DIFF_FORMAT_DIRSTAT |
3283                                             DIFF_FORMAT_SUMMARY |
3284                                             DIFF_FORMAT_PATCH);
3285
3286         /*
3287          * These cases always need recursive; we do not drop caller-supplied
3288          * recursive bits for other formats here.
3289          */
3290         if (options->output_format & (DIFF_FORMAT_PATCH |
3291                                       DIFF_FORMAT_NUMSTAT |
3292                                       DIFF_FORMAT_DIFFSTAT |
3293                                       DIFF_FORMAT_SHORTSTAT |
3294                                       DIFF_FORMAT_DIRSTAT |
3295                                       DIFF_FORMAT_SUMMARY |
3296                                       DIFF_FORMAT_CHECKDIFF))
3297                 DIFF_OPT_SET(options, RECURSIVE);
3298         /*
3299          * Also pickaxe would not work very well if you do not say recursive
3300          */
3301         if (options->pickaxe)
3302                 DIFF_OPT_SET(options, RECURSIVE);
3303         /*
3304          * When patches are generated, submodules diffed against the work tree
3305          * must be checked for dirtiness too so it can be shown in the output
3306          */
3307         if (options->output_format & DIFF_FORMAT_PATCH)
3308                 DIFF_OPT_SET(options, DIRTY_SUBMODULES);
3309
3310         if (options->detect_rename && options->rename_limit < 0)
3311                 options->rename_limit = diff_rename_limit_default;
3312         if (options->setup & DIFF_SETUP_USE_CACHE) {
3313                 if (!active_cache)
3314                         /* read-cache does not die even when it fails
3315                          * so it is safe for us to do this here.  Also
3316                          * it does not smudge active_cache or active_nr
3317                          * when it fails, so we do not have to worry about
3318                          * cleaning it up ourselves either.
3319                          */
3320                         read_cache();
3321         }
3322         if (options->abbrev <= 0 || 40 < options->abbrev)
3323                 options->abbrev = 40; /* full */
3324
3325         /*
3326          * It does not make sense to show the first hit we happened
3327          * to have found.  It does not make sense not to return with
3328          * exit code in such a case either.
3329          */
3330         if (DIFF_OPT_TST(options, QUICK)) {
3331                 options->output_format = DIFF_FORMAT_NO_OUTPUT;
3332                 DIFF_OPT_SET(options, EXIT_WITH_STATUS);
3333         }
3334
3335         options->diff_path_counter = 0;
3336 }
3337
3338 static int opt_arg(const char *arg, int arg_short, const char *arg_long, int *val)
3339 {
3340         char c, *eq;
3341         int len;
3342
3343         if (*arg != '-')
3344                 return 0;
3345         c = *++arg;
3346         if (!c)
3347                 return 0;
3348         if (c == arg_short) {
3349                 c = *++arg;
3350                 if (!c)
3351                         return 1;
3352                 if (val && isdigit(c)) {
3353                         char *end;
3354                         int n = strtoul(arg, &end, 10);
3355                         if (*end)
3356                                 return 0;
3357                         *val = n;
3358                         return 1;
3359                 }
3360                 return 0;
3361         }
3362         if (c != '-')
3363                 return 0;
3364         arg++;
3365         eq = strchr(arg, '=');
3366         if (eq)
3367                 len = eq - arg;
3368         else
3369                 len = strlen(arg);
3370         if (!len || strncmp(arg, arg_long, len))
3371                 return 0;
3372         if (eq) {
3373                 int n;
3374                 char *end;
3375                 if (!isdigit(*++eq))
3376                         return 0;
3377                 n = strtoul(eq, &end, 10);
3378                 if (*end)
3379                         return 0;
3380                 *val = n;
3381         }
3382         return 1;
3383 }
3384
3385 static int diff_scoreopt_parse(const char *opt);
3386
3387 static inline int short_opt(char opt, const char **argv,
3388                             const char **optarg)
3389 {
3390         const char *arg = argv[0];
3391         if (arg[0] != '-' || arg[1] != opt)
3392                 return 0;
3393         if (arg[2] != '\0') {
3394                 *optarg = arg + 2;
3395                 return 1;
3396         }
3397         if (!argv[1])
3398                 die("Option '%c' requires a value", opt);
3399         *optarg = argv[1];
3400         return 2;
3401 }
3402
3403 int parse_long_opt(const char *opt, const char **argv,
3404                    const char **optarg)
3405 {
3406         const char *arg = argv[0];
3407         if (arg[0] != '-' || arg[1] != '-')
3408                 return 0;
3409         arg += strlen("--");
3410         if (!starts_with(arg, opt))
3411                 return 0;
3412         arg += strlen(opt);
3413         if (*arg == '=') { /* stuck form: --option=value */
3414                 *optarg = arg + 1;
3415                 return 1;
3416         }
3417         if (*arg != '\0')
3418                 return 0;
3419         /* separate form: --option value */
3420         if (!argv[1])
3421                 die("Option '--%s' requires a value", opt);
3422         *optarg = argv[1];
3423         return 2;
3424 }
3425
3426 static int stat_opt(struct diff_options *options, const char **av)
3427 {
3428         const char *arg = av[0];
3429         char *end;
3430         int width = options->stat_width;
3431         int name_width = options->stat_name_width;
3432         int graph_width = options->stat_graph_width;
3433         int count = options->stat_count;
3434         int argcount = 1;
3435
3436         arg += strlen("--stat");
3437         end = (char *)arg;
3438
3439         switch (*arg) {
3440         case '-':
3441                 if (starts_with(arg, "-width")) {
3442                         arg += strlen("-width");
3443                         if (*arg == '=')
3444                                 width = strtoul(arg + 1, &end, 10);
3445                         else if (!*arg && !av[1])
3446                                 die("Option '--stat-width' requires a value");
3447                         else if (!*arg) {
3448                                 width = strtoul(av[1], &end, 10);
3449                                 argcount = 2;
3450                         }
3451                 } else if (starts_with(arg, "-name-width")) {
3452                         arg += strlen("-name-width");
3453                         if (*arg == '=')
3454                                 name_width = strtoul(arg + 1, &end, 10);
3455                         else if (!*arg && !av[1])
3456                                 die("Option '--stat-name-width' requires a value");
3457                         else if (!*arg) {
3458                                 name_width = strtoul(av[1], &end, 10);
3459                                 argcount = 2;
3460                         }
3461                 } else if (starts_with(arg, "-graph-width")) {
3462                         arg += strlen("-graph-width");
3463                         if (*arg == '=')
3464                                 graph_width = strtoul(arg + 1, &end, 10);
3465                         else if (!*arg && !av[1])
3466                                 die("Option '--stat-graph-width' requires a value");
3467                         else if (!*arg) {
3468                                 graph_width = strtoul(av[1], &end, 10);
3469                                 argcount = 2;
3470                         }
3471                 } else if (starts_with(arg, "-count")) {
3472                         arg += strlen("-count");
3473                         if (*arg == '=')
3474                                 count = strtoul(arg + 1, &end, 10);
3475                         else if (!*arg && !av[1])
3476                                 die("Option '--stat-count' requires a value");
3477                         else if (!*arg) {
3478                                 count = strtoul(av[1], &end, 10);
3479                                 argcount = 2;
3480                         }
3481                 }
3482                 break;
3483         case '=':
3484                 width = strtoul(arg+1, &end, 10);
3485                 if (*end == ',')
3486                         name_width = strtoul(end+1, &end, 10);
3487                 if (*end == ',')
3488                         count = strtoul(end+1, &end, 10);
3489         }
3490
3491         /* Important! This checks all the error cases! */
3492         if (*end)
3493                 return 0;
3494         options->output_format |= DIFF_FORMAT_DIFFSTAT;
3495         options->stat_name_width = name_width;
3496         options->stat_graph_width = graph_width;
3497         options->stat_width = width;
3498         options->stat_count = count;
3499         return argcount;
3500 }
3501
3502 static int parse_dirstat_opt(struct diff_options *options, const char *params)
3503 {
3504         struct strbuf errmsg = STRBUF_INIT;
3505         if (parse_dirstat_params(options, params, &errmsg))
3506                 die(_("Failed to parse --dirstat/-X option parameter:\n%s"),
3507                     errmsg.buf);
3508         strbuf_release(&errmsg);
3509         /*
3510          * The caller knows a dirstat-related option is given from the command
3511          * line; allow it to say "return this_function();"
3512          */
3513         options->output_format |= DIFF_FORMAT_DIRSTAT;
3514         return 1;
3515 }
3516
3517 static int parse_submodule_opt(struct diff_options *options, const char *value)
3518 {
3519         if (parse_submodule_params(options, value))
3520                 die(_("Failed to parse --submodule option parameter: '%s'"),
3521                         value);
3522         return 1;
3523 }
3524
3525 static const char diff_status_letters[] = {
3526         DIFF_STATUS_ADDED,
3527         DIFF_STATUS_COPIED,
3528         DIFF_STATUS_DELETED,
3529         DIFF_STATUS_MODIFIED,
3530         DIFF_STATUS_RENAMED,
3531         DIFF_STATUS_TYPE_CHANGED,
3532         DIFF_STATUS_UNKNOWN,
3533         DIFF_STATUS_UNMERGED,
3534         DIFF_STATUS_FILTER_AON,
3535         DIFF_STATUS_FILTER_BROKEN,
3536         '\0',
3537 };
3538
3539 static unsigned int filter_bit['Z' + 1];
3540
3541 static void prepare_filter_bits(void)
3542 {
3543         int i;
3544
3545         if (!filter_bit[DIFF_STATUS_ADDED]) {
3546                 for (i = 0; diff_status_letters[i]; i++)
3547                         filter_bit[(int) diff_status_letters[i]] = (1 << i);
3548         }
3549 }
3550
3551 static unsigned filter_bit_tst(char status, const struct diff_options *opt)
3552 {
3553         return opt->filter & filter_bit[(int) status];
3554 }
3555
3556 static int parse_diff_filter_opt(const char *optarg, struct diff_options *opt)
3557 {
3558         int i, optch;
3559
3560         prepare_filter_bits();
3561
3562         /*
3563          * If there is a negation e.g. 'd' in the input, and we haven't
3564          * initialized the filter field with another --diff-filter, start
3565          * from full set of bits, except for AON.
3566          */
3567         if (!opt->filter) {
3568                 for (i = 0; (optch = optarg[i]) != '\0'; i++) {
3569                         if (optch < 'a' || 'z' < optch)
3570                                 continue;
3571                         opt->filter = (1 << (ARRAY_SIZE(diff_status_letters) - 1)) - 1;
3572                         opt->filter &= ~filter_bit[DIFF_STATUS_FILTER_AON];
3573                         break;
3574                 }
3575         }
3576
3577         for (i = 0; (optch = optarg[i]) != '\0'; i++) {
3578                 unsigned int bit;
3579                 int negate;
3580
3581                 if ('a' <= optch && optch <= 'z') {
3582                         negate = 1;
3583                         optch = toupper(optch);
3584                 } else {
3585                         negate = 0;
3586                 }
3587
3588                 bit = (0 <= optch && optch <= 'Z') ? filter_bit[optch] : 0;
3589                 if (!bit)
3590                         return optarg[i];
3591                 if (negate)
3592                         opt->filter &= ~bit;
3593                 else
3594                         opt->filter |= bit;
3595         }
3596         return 0;
3597 }
3598
3599 static void enable_patch_output(int *fmt) {
3600         *fmt &= ~DIFF_FORMAT_NO_OUTPUT;
3601         *fmt |= DIFF_FORMAT_PATCH;
3602 }
3603
3604 int diff_opt_parse(struct diff_options *options, const char **av, int ac)
3605 {
3606         const char *arg = av[0];
3607         const char *optarg;
3608         int argcount;
3609
3610         /* Output format options */
3611         if (!strcmp(arg, "-p") || !strcmp(arg, "-u") || !strcmp(arg, "--patch")
3612             || opt_arg(arg, 'U', "unified", &options->context))
3613                 enable_patch_output(&options->output_format);
3614         else if (!strcmp(arg, "--raw"))
3615                 options->output_format |= DIFF_FORMAT_RAW;
3616         else if (!strcmp(arg, "--patch-with-raw")) {
3617                 enable_patch_output(&options->output_format);
3618                 options->output_format |= DIFF_FORMAT_RAW;
3619         } else if (!strcmp(arg, "--numstat"))
3620                 options->output_format |= DIFF_FORMAT_NUMSTAT;
3621         else if (!strcmp(arg, "--shortstat"))
3622                 options->output_format |= DIFF_FORMAT_SHORTSTAT;
3623         else if (!strcmp(arg, "-X") || !strcmp(arg, "--dirstat"))
3624                 return parse_dirstat_opt(options, "");
3625         else if (starts_with(arg, "-X"))
3626                 return parse_dirstat_opt(options, arg + 2);
3627         else if (starts_with(arg, "--dirstat="))
3628                 return parse_dirstat_opt(options, arg + 10);
3629         else if (!strcmp(arg, "--cumulative"))
3630                 return parse_dirstat_opt(options, "cumulative");
3631         else if (!strcmp(arg, "--dirstat-by-file"))
3632                 return parse_dirstat_opt(options, "files");
3633         else if (starts_with(arg, "--dirstat-by-file=")) {
3634                 parse_dirstat_opt(options, "files");
3635                 return parse_dirstat_opt(options, arg + 18);
3636         }
3637         else if (!strcmp(arg, "--check"))
3638                 options->output_format |= DIFF_FORMAT_CHECKDIFF;
3639         else if (!strcmp(arg, "--summary"))
3640                 options->output_format |= DIFF_FORMAT_SUMMARY;
3641         else if (!strcmp(arg, "--patch-with-stat")) {
3642                 enable_patch_output(&options->output_format);
3643                 options->output_format |= DIFF_FORMAT_DIFFSTAT;
3644         } else if (!strcmp(arg, "--name-only"))
3645                 options->output_format |= DIFF_FORMAT_NAME;
3646         else if (!strcmp(arg, "--name-status"))
3647                 options->output_format |= DIFF_FORMAT_NAME_STATUS;
3648         else if (!strcmp(arg, "-s") || !strcmp(arg, "--no-patch"))
3649                 options->output_format |= DIFF_FORMAT_NO_OUTPUT;
3650         else if (starts_with(arg, "--stat"))
3651                 /* --stat, --stat-width, --stat-name-width, or --stat-count */
3652                 return stat_opt(options, av);
3653
3654         /* renames options */
3655         else if (starts_with(arg, "-B") || starts_with(arg, "--break-rewrites=") ||
3656                  !strcmp(arg, "--break-rewrites")) {
3657                 if ((options->break_opt = diff_scoreopt_parse(arg)) == -1)
3658                         return error("invalid argument to -B: %s", arg+2);
3659         }
3660         else if (starts_with(arg, "-M") || starts_with(arg, "--find-renames=") ||
3661                  !strcmp(arg, "--find-renames")) {
3662                 if ((options->rename_score = diff_scoreopt_parse(arg)) == -1)
3663                         return error("invalid argument to -M: %s", arg+2);
3664                 options->detect_rename = DIFF_DETECT_RENAME;
3665         }
3666         else if (!strcmp(arg, "-D") || !strcmp(arg, "--irreversible-delete")) {
3667                 options->irreversible_delete = 1;
3668         }
3669         else if (starts_with(arg, "-C") || starts_with(arg, "--find-copies=") ||
3670                  !strcmp(arg, "--find-copies")) {
3671                 if (options->detect_rename == DIFF_DETECT_COPY)
3672                         DIFF_OPT_SET(options, FIND_COPIES_HARDER);
3673                 if ((options->rename_score = diff_scoreopt_parse(arg)) == -1)
3674                         return error("invalid argument to -C: %s", arg+2);
3675                 options->detect_rename = DIFF_DETECT_COPY;
3676         }
3677         else if (!strcmp(arg, "--no-renames"))
3678                 options->detect_rename = 0;
3679         else if (!strcmp(arg, "--rename-empty"))
3680                 DIFF_OPT_SET(options, RENAME_EMPTY);
3681         else if (!strcmp(arg, "--no-rename-empty"))
3682                 DIFF_OPT_CLR(options, RENAME_EMPTY);
3683         else if (!strcmp(arg, "--relative"))
3684                 DIFF_OPT_SET(options, RELATIVE_NAME);
3685         else if (starts_with(arg, "--relative=")) {
3686                 DIFF_OPT_SET(options, RELATIVE_NAME);
3687                 options->prefix = arg + 11;
3688         }
3689
3690         /* xdiff options */
3691         else if (!strcmp(arg, "--minimal"))
3692                 DIFF_XDL_SET(options, NEED_MINIMAL);
3693         else if (!strcmp(arg, "--no-minimal"))
3694                 DIFF_XDL_CLR(options, NEED_MINIMAL);
3695         else if (!strcmp(arg, "-w") || !strcmp(arg, "--ignore-all-space"))
3696                 DIFF_XDL_SET(options, IGNORE_WHITESPACE);
3697         else if (!strcmp(arg, "-b") || !strcmp(arg, "--ignore-space-change"))
3698                 DIFF_XDL_SET(options, IGNORE_WHITESPACE_CHANGE);
3699         else if (!strcmp(arg, "--ignore-space-at-eol"))
3700                 DIFF_XDL_SET(options, IGNORE_WHITESPACE_AT_EOL);
3701         else if (!strcmp(arg, "--ignore-blank-lines"))
3702                 DIFF_XDL_SET(options, IGNORE_BLANK_LINES);
3703         else if (!strcmp(arg, "--patience"))
3704                 options->xdl_opts = DIFF_WITH_ALG(options, PATIENCE_DIFF);
3705         else if (!strcmp(arg, "--histogram"))
3706                 options->xdl_opts = DIFF_WITH_ALG(options, HISTOGRAM_DIFF);
3707         else if ((argcount = parse_long_opt("diff-algorithm", av, &optarg))) {
3708                 long value = parse_algorithm_value(optarg);
3709                 if (value < 0)
3710                         return error("option diff-algorithm accepts \"myers\", "
3711                                      "\"minimal\", \"patience\" and \"histogram\"");
3712                 /* clear out previous settings */
3713                 DIFF_XDL_CLR(options, NEED_MINIMAL);
3714                 options->xdl_opts &= ~XDF_DIFF_ALGORITHM_MASK;
3715                 options->xdl_opts |= value;
3716                 return argcount;
3717         }
3718
3719         /* flags options */
3720         else if (!strcmp(arg, "--binary")) {
3721                 enable_patch_output(&options->output_format);
3722                 DIFF_OPT_SET(options, BINARY);
3723         }
3724         else if (!strcmp(arg, "--full-index"))
3725                 DIFF_OPT_SET(options, FULL_INDEX);
3726         else if (!strcmp(arg, "-a") || !strcmp(arg, "--text"))
3727                 DIFF_OPT_SET(options, TEXT);
3728         else if (!strcmp(arg, "-R"))
3729                 DIFF_OPT_SET(options, REVERSE_DIFF);
3730         else if (!strcmp(arg, "--find-copies-harder"))
3731                 DIFF_OPT_SET(options, FIND_COPIES_HARDER);
3732         else if (!strcmp(arg, "--follow"))
3733                 DIFF_OPT_SET(options, FOLLOW_RENAMES);
3734         else if (!strcmp(arg, "--no-follow"))
3735                 DIFF_OPT_CLR(options, FOLLOW_RENAMES);
3736         else if (!strcmp(arg, "--color"))
3737                 options->use_color = 1;
3738         else if (starts_with(arg, "--color=")) {
3739                 int value = git_config_colorbool(NULL, arg+8);
3740                 if (value < 0)
3741                         return error("option `color' expects \"always\", \"auto\", or \"never\"");
3742                 options->use_color = value;
3743         }
3744         else if (!strcmp(arg, "--no-color"))
3745                 options->use_color = 0;
3746         else if (!strcmp(arg, "--color-words")) {
3747                 options->use_color = 1;
3748                 options->word_diff = DIFF_WORDS_COLOR;
3749         }
3750         else if (starts_with(arg, "--color-words=")) {
3751                 options->use_color = 1;
3752                 options->word_diff = DIFF_WORDS_COLOR;
3753                 options->word_regex = arg + 14;
3754         }
3755         else if (!strcmp(arg, "--word-diff")) {
3756                 if (options->word_diff == DIFF_WORDS_NONE)
3757                         options->word_diff = DIFF_WORDS_PLAIN;
3758         }
3759         else if (starts_with(arg, "--word-diff=")) {
3760                 const char *type = arg + 12;
3761                 if (!strcmp(type, "plain"))
3762                         options->word_diff = DIFF_WORDS_PLAIN;
3763                 else if (!strcmp(type, "color")) {
3764                         options->use_color = 1;
3765                         options->word_diff = DIFF_WORDS_COLOR;
3766                 }
3767                 else if (!strcmp(type, "porcelain"))
3768                         options->word_diff = DIFF_WORDS_PORCELAIN;
3769                 else if (!strcmp(type, "none"))
3770                         options->word_diff = DIFF_WORDS_NONE;
3771                 else
3772                         die("bad --word-diff argument: %s", type);
3773         }
3774         else if ((argcount = parse_long_opt("word-diff-regex", av, &optarg))) {
3775                 if (options->word_diff == DIFF_WORDS_NONE)
3776                         options->word_diff = DIFF_WORDS_PLAIN;
3777                 options->word_regex = optarg;
3778                 return argcount;
3779         }
3780         else if (!strcmp(arg, "--exit-code"))
3781                 DIFF_OPT_SET(options, EXIT_WITH_STATUS);
3782         else if (!strcmp(arg, "--quiet"))
3783                 DIFF_OPT_SET(options, QUICK);
3784         else if (!strcmp(arg, "--ext-diff"))
3785                 DIFF_OPT_SET(options, ALLOW_EXTERNAL);
3786         else if (!strcmp(arg, "--no-ext-diff"))
3787                 DIFF_OPT_CLR(options, ALLOW_EXTERNAL);
3788         else if (!strcmp(arg, "--textconv"))
3789                 DIFF_OPT_SET(options, ALLOW_TEXTCONV);
3790         else if (!strcmp(arg, "--no-textconv"))
3791                 DIFF_OPT_CLR(options, ALLOW_TEXTCONV);
3792         else if (!strcmp(arg, "--ignore-submodules")) {
3793                 DIFF_OPT_SET(options, OVERRIDE_SUBMODULE_CONFIG);
3794                 handle_ignore_submodules_arg(options, "all");
3795         } else if (starts_with(arg, "--ignore-submodules=")) {
3796                 DIFF_OPT_SET(options, OVERRIDE_SUBMODULE_CONFIG);
3797                 handle_ignore_submodules_arg(options, arg + 20);
3798         } else if (!strcmp(arg, "--submodule"))
3799                 DIFF_OPT_SET(options, SUBMODULE_LOG);
3800         else if (starts_with(arg, "--submodule="))
3801                 return parse_submodule_opt(options, arg + 12);
3802
3803         /* misc options */
3804         else if (!strcmp(arg, "-z"))
3805                 options->line_termination = 0;
3806         else if ((argcount = short_opt('l', av, &optarg))) {
3807                 options->rename_limit = strtoul(optarg, NULL, 10);
3808                 return argcount;
3809         }
3810         else if ((argcount = short_opt('S', av, &optarg))) {
3811                 options->pickaxe = optarg;
3812                 options->pickaxe_opts |= DIFF_PICKAXE_KIND_S;
3813                 return argcount;
3814         } else if ((argcount = short_opt('G', av, &optarg))) {
3815                 options->pickaxe = optarg;
3816                 options->pickaxe_opts |= DIFF_PICKAXE_KIND_G;
3817                 return argcount;
3818         }
3819         else if (!strcmp(arg, "--pickaxe-all"))
3820                 options->pickaxe_opts |= DIFF_PICKAXE_ALL;
3821         else if (!strcmp(arg, "--pickaxe-regex"))
3822                 options->pickaxe_opts |= DIFF_PICKAXE_REGEX;
3823         else if ((argcount = short_opt('O', av, &optarg))) {
3824                 options->orderfile = optarg;
3825                 return argcount;
3826         }
3827         else if ((argcount = parse_long_opt("diff-filter", av, &optarg))) {
3828                 int offending = parse_diff_filter_opt(optarg, options);
3829                 if (offending)
3830                         die("unknown change class '%c' in --diff-filter=%s",
3831                             offending, optarg);
3832                 return argcount;
3833         }
3834         else if (!strcmp(arg, "--abbrev"))
3835                 options->abbrev = DEFAULT_ABBREV;
3836         else if (starts_with(arg, "--abbrev=")) {
3837                 options->abbrev = strtoul(arg + 9, NULL, 10);
3838                 if (options->abbrev < MINIMUM_ABBREV)
3839                         options->abbrev = MINIMUM_ABBREV;
3840                 else if (40 < options->abbrev)
3841                         options->abbrev = 40;
3842         }
3843         else if ((argcount = parse_long_opt("src-prefix", av, &optarg))) {
3844                 options->a_prefix = optarg;
3845                 return argcount;
3846         }
3847         else if ((argcount = parse_long_opt("dst-prefix", av, &optarg))) {
3848                 options->b_prefix = optarg;
3849                 return argcount;
3850         }
3851         else if (!strcmp(arg, "--no-prefix"))
3852                 options->a_prefix = options->b_prefix = "";
3853         else if (opt_arg(arg, '\0', "inter-hunk-context",
3854                          &options->interhunkcontext))
3855                 ;
3856         else if (!strcmp(arg, "-W"))
3857                 DIFF_OPT_SET(options, FUNCCONTEXT);
3858         else if (!strcmp(arg, "--function-context"))
3859                 DIFF_OPT_SET(options, FUNCCONTEXT);
3860         else if (!strcmp(arg, "--no-function-context"))
3861                 DIFF_OPT_CLR(options, FUNCCONTEXT);
3862         else if ((argcount = parse_long_opt("output", av, &optarg))) {
3863                 options->file = fopen(optarg, "w");
3864                 if (!options->file)
3865                         die_errno("Could not open '%s'", optarg);
3866                 options->close_file = 1;
3867                 return argcount;
3868         } else
3869                 return 0;
3870         return 1;
3871 }
3872
3873 int parse_rename_score(const char **cp_p)
3874 {
3875         unsigned long num, scale;
3876         int ch, dot;
3877         const char *cp = *cp_p;
3878
3879         num = 0;
3880         scale = 1;
3881         dot = 0;
3882         for (;;) {
3883                 ch = *cp;
3884                 if ( !dot && ch == '.' ) {
3885                         scale = 1;
3886                         dot = 1;
3887                 } else if ( ch == '%' ) {
3888                         scale = dot ? scale*100 : 100;
3889                         cp++;   /* % is always at the end */
3890                         break;
3891                 } else if ( ch >= '0' && ch <= '9' ) {
3892                         if ( scale < 100000 ) {
3893                                 scale *= 10;
3894                                 num = (num*10) + (ch-'0');
3895                         }
3896                 } else {
3897                         break;
3898                 }
3899                 cp++;
3900         }
3901         *cp_p = cp;
3902
3903         /* user says num divided by scale and we say internally that
3904          * is MAX_SCORE * num / scale.
3905          */
3906         return (int)((num >= scale) ? MAX_SCORE : (MAX_SCORE * num / scale));
3907 }
3908
3909 static int diff_scoreopt_parse(const char *opt)
3910 {
3911         int opt1, opt2, cmd;
3912
3913         if (*opt++ != '-')
3914                 return -1;
3915         cmd = *opt++;
3916         if (cmd == '-') {
3917                 /* convert the long-form arguments into short-form versions */
3918                 if (starts_with(opt, "break-rewrites")) {
3919                         opt += strlen("break-rewrites");
3920                         if (*opt == 0 || *opt++ == '=')
3921                                 cmd = 'B';
3922                 } else if (starts_with(opt, "find-copies")) {
3923                         opt += strlen("find-copies");
3924                         if (*opt == 0 || *opt++ == '=')
3925                                 cmd = 'C';
3926                 } else if (starts_with(opt, "find-renames")) {
3927                         opt += strlen("find-renames");
3928                         if (*opt == 0 || *opt++ == '=')
3929                                 cmd = 'M';
3930                 }
3931         }
3932         if (cmd != 'M' && cmd != 'C' && cmd != 'B')
3933                 return -1; /* that is not a -M, -C nor -B option */
3934
3935         opt1 = parse_rename_score(&opt);
3936         if (cmd != 'B')
3937                 opt2 = 0;
3938         else {
3939                 if (*opt == 0)
3940                         opt2 = 0;
3941                 else if (*opt != '/')
3942                         return -1; /* we expect -B80/99 or -B80 */
3943                 else {
3944                         opt++;
3945                         opt2 = parse_rename_score(&opt);
3946                 }
3947         }
3948         if (*opt != 0)
3949                 return -1;
3950         return opt1 | (opt2 << 16);
3951 }
3952
3953 struct diff_queue_struct diff_queued_diff;
3954
3955 void diff_q(struct diff_queue_struct *queue, struct diff_filepair *dp)
3956 {
3957         ALLOC_GROW(queue->queue, queue->nr + 1, queue->alloc);
3958         queue->queue[queue->nr++] = dp;
3959 }
3960
3961 struct diff_filepair *diff_queue(struct diff_queue_struct *queue,
3962                                  struct diff_filespec *one,
3963                                  struct diff_filespec *two)
3964 {
3965         struct diff_filepair *dp = xcalloc(1, sizeof(*dp));
3966         dp->one = one;
3967         dp->two = two;
3968         if (queue)
3969                 diff_q(queue, dp);
3970         return dp;
3971 }
3972
3973 void diff_free_filepair(struct diff_filepair *p)
3974 {
3975         free_filespec(p->one);
3976         free_filespec(p->two);
3977         free(p);
3978 }
3979
3980 /* This is different from find_unique_abbrev() in that
3981  * it stuffs the result with dots for alignment.
3982  */
3983 const char *diff_unique_abbrev(const unsigned char *sha1, int len)
3984 {
3985         int abblen;
3986         const char *abbrev;
3987         if (len == 40)
3988                 return sha1_to_hex(sha1);
3989
3990         abbrev = find_unique_abbrev(sha1, len);
3991         abblen = strlen(abbrev);
3992         if (abblen < 37) {
3993                 static char hex[41];
3994                 if (len < abblen && abblen <= len + 2)
3995                         sprintf(hex, "%s%.*s", abbrev, len+3-abblen, "..");
3996                 else
3997                         sprintf(hex, "%s...", abbrev);
3998                 return hex;
3999         }
4000         return sha1_to_hex(sha1);
4001 }
4002
4003 static void diff_flush_raw(struct diff_filepair *p, struct diff_options *opt)
4004 {
4005         int line_termination = opt->line_termination;
4006         int inter_name_termination = line_termination ? '\t' : '\0';
4007
4008         fprintf(opt->file, "%s", diff_line_prefix(opt));
4009         if (!(opt->output_format & DIFF_FORMAT_NAME_STATUS)) {
4010                 fprintf(opt->file, ":%06o %06o %s ", p->one->mode, p->two->mode,
4011                         diff_unique_abbrev(p->one->sha1, opt->abbrev));
4012                 fprintf(opt->file, "%s ", diff_unique_abbrev(p->two->sha1, opt->abbrev));
4013         }
4014         if (p->score) {
4015                 fprintf(opt->file, "%c%03d%c", p->status, similarity_index(p),
4016                         inter_name_termination);
4017         } else {
4018                 fprintf(opt->file, "%c%c", p->status, inter_name_termination);
4019         }
4020
4021         if (p->status == DIFF_STATUS_COPIED ||
4022             p->status == DIFF_STATUS_RENAMED) {
4023                 const char *name_a, *name_b;
4024                 name_a = p->one->path;
4025                 name_b = p->two->path;
4026                 strip_prefix(opt->prefix_length, &name_a, &name_b);
4027                 write_name_quoted(name_a, opt->file, inter_name_termination);
4028                 write_name_quoted(name_b, opt->file, line_termination);
4029         } else {
4030                 const char *name_a, *name_b;
4031                 name_a = p->one->mode ? p->one->path : p->two->path;
4032                 name_b = NULL;
4033                 strip_prefix(opt->prefix_length, &name_a, &name_b);
4034                 write_name_quoted(name_a, opt->file, line_termination);
4035         }
4036 }
4037
4038 int diff_unmodified_pair(struct diff_filepair *p)
4039 {
4040         /* This function is written stricter than necessary to support
4041          * the currently implemented transformers, but the idea is to
4042          * let transformers to produce diff_filepairs any way they want,
4043          * and filter and clean them up here before producing the output.
4044          */
4045         struct diff_filespec *one = p->one, *two = p->two;
4046
4047         if (DIFF_PAIR_UNMERGED(p))
4048                 return 0; /* unmerged is interesting */
4049
4050         /* deletion, addition, mode or type change
4051          * and rename are all interesting.
4052          */
4053         if (DIFF_FILE_VALID(one) != DIFF_FILE_VALID(two) ||
4054             DIFF_PAIR_MODE_CHANGED(p) ||
4055             strcmp(one->path, two->path))
4056                 return 0;
4057
4058         /* both are valid and point at the same path.  that is, we are
4059          * dealing with a change.
4060          */
4061         if (one->sha1_valid && two->sha1_valid &&
4062             !hashcmp(one->sha1, two->sha1) &&
4063             !one->dirty_submodule && !two->dirty_submodule)
4064                 return 1; /* no change */
4065         if (!one->sha1_valid && !two->sha1_valid)
4066                 return 1; /* both look at the same file on the filesystem. */
4067         return 0;
4068 }
4069
4070 static void diff_flush_patch(struct diff_filepair *p, struct diff_options *o)
4071 {
4072         if (diff_unmodified_pair(p))
4073                 return;
4074
4075         if ((DIFF_FILE_VALID(p->one) && S_ISDIR(p->one->mode)) ||
4076             (DIFF_FILE_VALID(p->two) && S_ISDIR(p->two->mode)))
4077                 return; /* no tree diffs in patch format */
4078
4079         run_diff(p, o);
4080 }
4081
4082 static void diff_flush_stat(struct diff_filepair *p, struct diff_options *o,
4083                             struct diffstat_t *diffstat)
4084 {
4085         if (diff_unmodified_pair(p))
4086                 return;
4087
4088         if ((DIFF_FILE_VALID(p->one) && S_ISDIR(p->one->mode)) ||
4089             (DIFF_FILE_VALID(p->two) && S_ISDIR(p->two->mode)))
4090                 return; /* no useful stat for tree diffs */
4091
4092         run_diffstat(p, o, diffstat);
4093 }
4094
4095 static void diff_flush_checkdiff(struct diff_filepair *p,
4096                 struct diff_options *o)
4097 {
4098         if (diff_unmodified_pair(p))
4099                 return;
4100
4101         if ((DIFF_FILE_VALID(p->one) && S_ISDIR(p->one->mode)) ||
4102             (DIFF_FILE_VALID(p->two) && S_ISDIR(p->two->mode)))
4103                 return; /* nothing to check in tree diffs */
4104
4105         run_checkdiff(p, o);
4106 }
4107
4108 int diff_queue_is_empty(void)
4109 {
4110         struct diff_queue_struct *q = &diff_queued_diff;
4111         int i;
4112         for (i = 0; i < q->nr; i++)
4113                 if (!diff_unmodified_pair(q->queue[i]))
4114                         return 0;
4115         return 1;
4116 }
4117
4118 #if DIFF_DEBUG
4119 void diff_debug_filespec(struct diff_filespec *s, int x, const char *one)
4120 {
4121         fprintf(stderr, "queue[%d] %s (%s) %s %06o %s\n",
4122                 x, one ? one : "",
4123                 s->path,
4124                 DIFF_FILE_VALID(s) ? "valid" : "invalid",
4125                 s->mode,
4126                 s->sha1_valid ? sha1_to_hex(s->sha1) : "");
4127         fprintf(stderr, "queue[%d] %s size %lu\n",
4128                 x, one ? one : "",
4129                 s->size);
4130 }
4131
4132 void diff_debug_filepair(const struct diff_filepair *p, int i)
4133 {
4134         diff_debug_filespec(p->one, i, "one");
4135         diff_debug_filespec(p->two, i, "two");
4136         fprintf(stderr, "score %d, status %c rename_used %d broken %d\n",
4137                 p->score, p->status ? p->status : '?',
4138                 p->one->rename_used, p->broken_pair);
4139 }
4140
4141 void diff_debug_queue(const char *msg, struct diff_queue_struct *q)
4142 {
4143         int i;
4144         if (msg)
4145                 fprintf(stderr, "%s\n", msg);
4146         fprintf(stderr, "q->nr = %d\n", q->nr);
4147         for (i = 0; i < q->nr; i++) {
4148                 struct diff_filepair *p = q->queue[i];
4149                 diff_debug_filepair(p, i);
4150         }
4151 }
4152 #endif
4153
4154 static void diff_resolve_rename_copy(void)
4155 {
4156         int i;
4157         struct diff_filepair *p;
4158         struct diff_queue_struct *q = &diff_queued_diff;
4159
4160         diff_debug_queue("resolve-rename-copy", q);
4161
4162         for (i = 0; i < q->nr; i++) {
4163                 p = q->queue[i];
4164                 p->status = 0; /* undecided */
4165                 if (DIFF_PAIR_UNMERGED(p))
4166                         p->status = DIFF_STATUS_UNMERGED;
4167                 else if (!DIFF_FILE_VALID(p->one))
4168                         p->status = DIFF_STATUS_ADDED;
4169                 else if (!DIFF_FILE_VALID(p->two))
4170                         p->status = DIFF_STATUS_DELETED;
4171                 else if (DIFF_PAIR_TYPE_CHANGED(p))
4172                         p->status = DIFF_STATUS_TYPE_CHANGED;
4173
4174                 /* from this point on, we are dealing with a pair
4175                  * whose both sides are valid and of the same type, i.e.
4176                  * either in-place edit or rename/copy edit.
4177                  */
4178                 else if (DIFF_PAIR_RENAME(p)) {
4179                         /*
4180                          * A rename might have re-connected a broken
4181                          * pair up, causing the pathnames to be the
4182                          * same again. If so, that's not a rename at
4183                          * all, just a modification..
4184                          *
4185                          * Otherwise, see if this source was used for
4186                          * multiple renames, in which case we decrement
4187                          * the count, and call it a copy.
4188                          */
4189                         if (!strcmp(p->one->path, p->two->path))
4190                                 p->status = DIFF_STATUS_MODIFIED;
4191                         else if (--p->one->rename_used > 0)
4192                                 p->status = DIFF_STATUS_COPIED;
4193                         else
4194                                 p->status = DIFF_STATUS_RENAMED;
4195                 }
4196                 else if (hashcmp(p->one->sha1, p->two->sha1) ||
4197                          p->one->mode != p->two->mode ||
4198                          p->one->dirty_submodule ||
4199                          p->two->dirty_submodule ||
4200                          is_null_sha1(p->one->sha1))
4201                         p->status = DIFF_STATUS_MODIFIED;
4202                 else {
4203                         /* This is a "no-change" entry and should not
4204                          * happen anymore, but prepare for broken callers.
4205                          */
4206                         error("feeding unmodified %s to diffcore",
4207                               p->one->path);
4208                         p->status = DIFF_STATUS_UNKNOWN;
4209                 }
4210         }
4211         diff_debug_queue("resolve-rename-copy done", q);
4212 }
4213
4214 static int check_pair_status(struct diff_filepair *p)
4215 {
4216         switch (p->status) {
4217         case DIFF_STATUS_UNKNOWN:
4218                 return 0;
4219         case 0:
4220                 die("internal error in diff-resolve-rename-copy");
4221         default:
4222                 return 1;
4223         }
4224 }
4225
4226 static void flush_one_pair(struct diff_filepair *p, struct diff_options *opt)
4227 {
4228         int fmt = opt->output_format;
4229
4230         if (fmt & DIFF_FORMAT_CHECKDIFF)
4231                 diff_flush_checkdiff(p, opt);
4232         else if (fmt & (DIFF_FORMAT_RAW | DIFF_FORMAT_NAME_STATUS))
4233                 diff_flush_raw(p, opt);
4234         else if (fmt & DIFF_FORMAT_NAME) {
4235                 const char *name_a, *name_b;
4236                 name_a = p->two->path;
4237                 name_b = NULL;
4238                 strip_prefix(opt->prefix_length, &name_a, &name_b);
4239                 write_name_quoted(name_a, opt->file, opt->line_termination);
4240         }
4241 }
4242
4243 static void show_file_mode_name(FILE *file, const char *newdelete, struct diff_filespec *fs)
4244 {
4245         if (fs->mode)
4246                 fprintf(file, " %s mode %06o ", newdelete, fs->mode);
4247         else
4248                 fprintf(file, " %s ", newdelete);
4249         write_name_quoted(fs->path, file, '\n');
4250 }
4251
4252
4253 static void show_mode_change(FILE *file, struct diff_filepair *p, int show_name,
4254                 const char *line_prefix)
4255 {
4256         if (p->one->mode && p->two->mode && p->one->mode != p->two->mode) {
4257                 fprintf(file, "%s mode change %06o => %06o%c", line_prefix, p->one->mode,
4258                         p->two->mode, show_name ? ' ' : '\n');
4259                 if (show_name) {
4260                         write_name_quoted(p->two->path, file, '\n');
4261                 }
4262         }
4263 }
4264
4265 static void show_rename_copy(FILE *file, const char *renamecopy, struct diff_filepair *p,
4266                         const char *line_prefix)
4267 {
4268         char *names = pprint_rename(p->one->path, p->two->path);
4269
4270         fprintf(file, " %s %s (%d%%)\n", renamecopy, names, similarity_index(p));
4271         free(names);
4272         show_mode_change(file, p, 0, line_prefix);
4273 }
4274
4275 static void diff_summary(struct diff_options *opt, struct diff_filepair *p)
4276 {
4277         FILE *file = opt->file;
4278         const char *line_prefix = diff_line_prefix(opt);
4279
4280         switch(p->status) {
4281         case DIFF_STATUS_DELETED:
4282                 fputs(line_prefix, file);
4283                 show_file_mode_name(file, "delete", p->one);
4284                 break;
4285         case DIFF_STATUS_ADDED:
4286                 fputs(line_prefix, file);
4287                 show_file_mode_name(file, "create", p->two);
4288                 break;
4289         case DIFF_STATUS_COPIED:
4290                 fputs(line_prefix, file);
4291                 show_rename_copy(file, "copy", p, line_prefix);
4292                 break;
4293         case DIFF_STATUS_RENAMED:
4294                 fputs(line_prefix, file);
4295                 show_rename_copy(file, "rename", p, line_prefix);
4296                 break;
4297         default:
4298                 if (p->score) {
4299                         fprintf(file, "%s rewrite ", line_prefix);
4300                         write_name_quoted(p->two->path, file, ' ');
4301                         fprintf(file, "(%d%%)\n", similarity_index(p));
4302                 }
4303                 show_mode_change(file, p, !p->score, line_prefix);
4304                 break;
4305         }
4306 }
4307
4308 struct patch_id_t {
4309         git_SHA_CTX *ctx;
4310         int patchlen;
4311 };
4312
4313 static int remove_space(char *line, int len)
4314 {
4315         int i;
4316         char *dst = line;
4317         unsigned char c;
4318
4319         for (i = 0; i < len; i++)
4320                 if (!isspace((c = line[i])))
4321                         *dst++ = c;
4322
4323         return dst - line;
4324 }
4325
4326 static void patch_id_consume(void *priv, char *line, unsigned long len)
4327 {
4328         struct patch_id_t *data = priv;
4329         int new_len;
4330
4331         /* Ignore line numbers when computing the SHA1 of the patch */
4332         if (starts_with(line, "@@ -"))
4333                 return;
4334
4335         new_len = remove_space(line, len);
4336
4337         git_SHA1_Update(data->ctx, line, new_len);
4338         data->patchlen += new_len;
4339 }
4340
4341 /* returns 0 upon success, and writes result into sha1 */
4342 static int diff_get_patch_id(struct diff_options *options, unsigned char *sha1)
4343 {
4344         struct diff_queue_struct *q = &diff_queued_diff;
4345         int i;
4346         git_SHA_CTX ctx;
4347         struct patch_id_t data;
4348         char buffer[PATH_MAX * 4 + 20];
4349
4350         git_SHA1_Init(&ctx);
4351         memset(&data, 0, sizeof(struct patch_id_t));
4352         data.ctx = &ctx;
4353
4354         for (i = 0; i < q->nr; i++) {
4355                 xpparam_t xpp;
4356                 xdemitconf_t xecfg;
4357                 mmfile_t mf1, mf2;
4358                 struct diff_filepair *p = q->queue[i];
4359                 int len1, len2;
4360
4361                 memset(&xpp, 0, sizeof(xpp));
4362                 memset(&xecfg, 0, sizeof(xecfg));
4363                 if (p->status == 0)
4364                         return error("internal diff status error");
4365                 if (p->status == DIFF_STATUS_UNKNOWN)
4366                         continue;
4367                 if (diff_unmodified_pair(p))
4368                         continue;
4369                 if ((DIFF_FILE_VALID(p->one) && S_ISDIR(p->one->mode)) ||
4370                     (DIFF_FILE_VALID(p->two) && S_ISDIR(p->two->mode)))
4371                         continue;
4372                 if (DIFF_PAIR_UNMERGED(p))
4373                         continue;
4374
4375                 diff_fill_sha1_info(p->one);
4376                 diff_fill_sha1_info(p->two);
4377                 if (fill_mmfile(&mf1, p->one) < 0 ||
4378                                 fill_mmfile(&mf2, p->two) < 0)
4379                         return error("unable to read files to diff");
4380
4381                 len1 = remove_space(p->one->path, strlen(p->one->path));
4382                 len2 = remove_space(p->two->path, strlen(p->two->path));
4383                 if (p->one->mode == 0)
4384                         len1 = snprintf(buffer, sizeof(buffer),
4385                                         "diff--gita/%.*sb/%.*s"
4386                                         "newfilemode%06o"
4387                                         "---/dev/null"
4388                                         "+++b/%.*s",
4389                                         len1, p->one->path,
4390                                         len2, p->two->path,
4391                                         p->two->mode,
4392                                         len2, p->two->path);
4393                 else if (p->two->mode == 0)
4394                         len1 = snprintf(buffer, sizeof(buffer),
4395                                         "diff--gita/%.*sb/%.*s"
4396                                         "deletedfilemode%06o"
4397                                         "---a/%.*s"
4398                                         "+++/dev/null",
4399                                         len1, p->one->path,
4400                                         len2, p->two->path,
4401                                         p->one->mode,
4402                                         len1, p->one->path);
4403                 else
4404                         len1 = snprintf(buffer, sizeof(buffer),
4405                                         "diff--gita/%.*sb/%.*s"
4406                                         "---a/%.*s"
4407                                         "+++b/%.*s",
4408                                         len1, p->one->path,
4409                                         len2, p->two->path,
4410                                         len1, p->one->path,
4411                                         len2, p->two->path);
4412                 git_SHA1_Update(&ctx, buffer, len1);
4413
4414                 if (diff_filespec_is_binary(p->one) ||
4415                     diff_filespec_is_binary(p->two)) {
4416                         git_SHA1_Update(&ctx, sha1_to_hex(p->one->sha1), 40);
4417                         git_SHA1_Update(&ctx, sha1_to_hex(p->two->sha1), 40);
4418                         continue;
4419                 }
4420
4421                 xpp.flags = 0;
4422                 xecfg.ctxlen = 3;
4423                 xecfg.flags = 0;
4424                 xdi_diff_outf(&mf1, &mf2, patch_id_consume, &data,
4425                               &xpp, &xecfg);
4426         }
4427
4428         git_SHA1_Final(sha1, &ctx);
4429         return 0;
4430 }
4431
4432 int diff_flush_patch_id(struct diff_options *options, unsigned char *sha1)
4433 {
4434         struct diff_queue_struct *q = &diff_queued_diff;
4435         int i;
4436         int result = diff_get_patch_id(options, sha1);
4437
4438         for (i = 0; i < q->nr; i++)
4439                 diff_free_filepair(q->queue[i]);
4440
4441         free(q->queue);
4442         DIFF_QUEUE_CLEAR(q);
4443
4444         return result;
4445 }
4446
4447 static int is_summary_empty(const struct diff_queue_struct *q)
4448 {
4449         int i;
4450
4451         for (i = 0; i < q->nr; i++) {
4452                 const struct diff_filepair *p = q->queue[i];
4453
4454                 switch (p->status) {
4455                 case DIFF_STATUS_DELETED:
4456                 case DIFF_STATUS_ADDED:
4457                 case DIFF_STATUS_COPIED:
4458                 case DIFF_STATUS_RENAMED:
4459                         return 0;
4460                 default:
4461                         if (p->score)
4462                                 return 0;
4463                         if (p->one->mode && p->two->mode &&
4464                             p->one->mode != p->two->mode)
4465                                 return 0;
4466                         break;
4467                 }
4468         }
4469         return 1;
4470 }
4471
4472 static const char rename_limit_warning[] =
4473 "inexact rename detection was skipped due to too many files.";
4474
4475 static const char degrade_cc_to_c_warning[] =
4476 "only found copies from modified paths due to too many files.";
4477
4478 static const char rename_limit_advice[] =
4479 "you may want to set your %s variable to at least "
4480 "%d and retry the command.";
4481
4482 void diff_warn_rename_limit(const char *varname, int needed, int degraded_cc)
4483 {
4484         if (degraded_cc)
4485                 warning(degrade_cc_to_c_warning);
4486         else if (needed)
4487                 warning(rename_limit_warning);
4488         else
4489                 return;
4490         if (0 < needed && needed < 32767)
4491                 warning(rename_limit_advice, varname, needed);
4492 }
4493
4494 void diff_flush(struct diff_options *options)
4495 {
4496         struct diff_queue_struct *q = &diff_queued_diff;
4497         int i, output_format = options->output_format;
4498         int separator = 0;
4499         int dirstat_by_line = 0;
4500
4501         /*
4502          * Order: raw, stat, summary, patch
4503          * or:    name/name-status/checkdiff (other bits clear)
4504          */
4505         if (!q->nr)
4506                 goto free_queue;
4507
4508         if (output_format & (DIFF_FORMAT_RAW |
4509                              DIFF_FORMAT_NAME |
4510                              DIFF_FORMAT_NAME_STATUS |
4511                              DIFF_FORMAT_CHECKDIFF)) {
4512                 for (i = 0; i < q->nr; i++) {
4513                         struct diff_filepair *p = q->queue[i];
4514                         if (check_pair_status(p))
4515                                 flush_one_pair(p, options);
4516                 }
4517                 separator++;
4518         }
4519
4520         if (output_format & DIFF_FORMAT_DIRSTAT && DIFF_OPT_TST(options, DIRSTAT_BY_LINE))
4521                 dirstat_by_line = 1;
4522
4523         if (output_format & (DIFF_FORMAT_DIFFSTAT|DIFF_FORMAT_SHORTSTAT|DIFF_FORMAT_NUMSTAT) ||
4524             dirstat_by_line) {
4525                 struct diffstat_t diffstat;
4526
4527                 memset(&diffstat, 0, sizeof(struct diffstat_t));
4528                 for (i = 0; i < q->nr; i++) {
4529                         struct diff_filepair *p = q->queue[i];
4530                         if (check_pair_status(p))
4531                                 diff_flush_stat(p, options, &diffstat);
4532                 }
4533                 if (output_format & DIFF_FORMAT_NUMSTAT)
4534                         show_numstat(&diffstat, options);
4535                 if (output_format & DIFF_FORMAT_DIFFSTAT)
4536                         show_stats(&diffstat, options);
4537                 if (output_format & DIFF_FORMAT_SHORTSTAT)
4538                         show_shortstats(&diffstat, options);
4539                 if (output_format & DIFF_FORMAT_DIRSTAT)
4540                         show_dirstat_by_line(&diffstat, options);
4541                 free_diffstat_info(&diffstat);
4542                 separator++;
4543         }
4544         if ((output_format & DIFF_FORMAT_DIRSTAT) && !dirstat_by_line)
4545                 show_dirstat(options);
4546
4547         if (output_format & DIFF_FORMAT_SUMMARY && !is_summary_empty(q)) {
4548                 for (i = 0; i < q->nr; i++) {
4549                         diff_summary(options, q->queue[i]);
4550                 }
4551                 separator++;
4552         }
4553
4554         if (output_format & DIFF_FORMAT_NO_OUTPUT &&
4555             DIFF_OPT_TST(options, EXIT_WITH_STATUS) &&
4556             DIFF_OPT_TST(options, DIFF_FROM_CONTENTS)) {
4557                 /*
4558                  * run diff_flush_patch for the exit status. setting
4559                  * options->file to /dev/null should be safe, because we
4560                  * aren't supposed to produce any output anyway.
4561                  */
4562                 if (options->close_file)
4563                         fclose(options->file);
4564                 options->file = fopen("/dev/null", "w");
4565                 if (!options->file)
4566                         die_errno("Could not open /dev/null");
4567                 options->close_file = 1;
4568                 for (i = 0; i < q->nr; i++) {
4569                         struct diff_filepair *p = q->queue[i];
4570                         if (check_pair_status(p))
4571                                 diff_flush_patch(p, options);
4572                         if (options->found_changes)
4573                                 break;
4574                 }
4575         }
4576
4577         if (output_format & DIFF_FORMAT_PATCH) {
4578                 if (separator) {
4579                         fprintf(options->file, "%s%c",
4580                                 diff_line_prefix(options),
4581                                 options->line_termination);
4582                         if (options->stat_sep) {
4583                                 /* attach patch instead of inline */
4584                                 fputs(options->stat_sep, options->file);
4585                         }
4586                 }
4587
4588                 for (i = 0; i < q->nr; i++) {
4589                         struct diff_filepair *p = q->queue[i];
4590                         if (check_pair_status(p))
4591                                 diff_flush_patch(p, options);
4592                 }
4593         }
4594
4595         if (output_format & DIFF_FORMAT_CALLBACK)
4596                 options->format_callback(q, options, options->format_callback_data);
4597
4598         for (i = 0; i < q->nr; i++)
4599                 diff_free_filepair(q->queue[i]);
4600 free_queue:
4601         free(q->queue);
4602         DIFF_QUEUE_CLEAR(q);
4603         if (options->close_file)
4604                 fclose(options->file);
4605
4606         /*
4607          * Report the content-level differences with HAS_CHANGES;
4608          * diff_addremove/diff_change does not set the bit when
4609          * DIFF_FROM_CONTENTS is in effect (e.g. with -w).
4610          */
4611         if (DIFF_OPT_TST(options, DIFF_FROM_CONTENTS)) {
4612                 if (options->found_changes)
4613                         DIFF_OPT_SET(options, HAS_CHANGES);
4614                 else
4615                         DIFF_OPT_CLR(options, HAS_CHANGES);
4616         }
4617 }
4618
4619 static int match_filter(const struct diff_options *options, const struct diff_filepair *p)
4620 {
4621         return (((p->status == DIFF_STATUS_MODIFIED) &&
4622                  ((p->score &&
4623                    filter_bit_tst(DIFF_STATUS_FILTER_BROKEN, options)) ||
4624                   (!p->score &&
4625                    filter_bit_tst(DIFF_STATUS_MODIFIED, options)))) ||
4626                 ((p->status != DIFF_STATUS_MODIFIED) &&
4627                  filter_bit_tst(p->status, options)));
4628 }
4629
4630 static void diffcore_apply_filter(struct diff_options *options)
4631 {
4632         int i;
4633         struct diff_queue_struct *q = &diff_queued_diff;
4634         struct diff_queue_struct outq;
4635
4636         DIFF_QUEUE_CLEAR(&outq);
4637
4638         if (!options->filter)
4639                 return;
4640
4641         if (filter_bit_tst(DIFF_STATUS_FILTER_AON, options)) {
4642                 int found;
4643                 for (i = found = 0; !found && i < q->nr; i++) {
4644                         if (match_filter(options, q->queue[i]))
4645                                 found++;
4646                 }
4647                 if (found)
4648                         return;
4649
4650                 /* otherwise we will clear the whole queue
4651                  * by copying the empty outq at the end of this
4652                  * function, but first clear the current entries
4653                  * in the queue.
4654                  */
4655                 for (i = 0; i < q->nr; i++)
4656                         diff_free_filepair(q->queue[i]);
4657         }
4658         else {
4659                 /* Only the matching ones */
4660                 for (i = 0; i < q->nr; i++) {
4661                         struct diff_filepair *p = q->queue[i];
4662                         if (match_filter(options, p))
4663                                 diff_q(&outq, p);
4664                         else
4665                                 diff_free_filepair(p);
4666                 }
4667         }
4668         free(q->queue);
4669         *q = outq;
4670 }
4671
4672 /* Check whether two filespecs with the same mode and size are identical */
4673 static int diff_filespec_is_identical(struct diff_filespec *one,
4674                                       struct diff_filespec *two)
4675 {
4676         if (S_ISGITLINK(one->mode))
4677                 return 0;
4678         if (diff_populate_filespec(one, 0))
4679                 return 0;
4680         if (diff_populate_filespec(two, 0))
4681                 return 0;
4682         return !memcmp(one->data, two->data, one->size);
4683 }
4684
4685 static int diff_filespec_check_stat_unmatch(struct diff_filepair *p)
4686 {
4687         if (p->done_skip_stat_unmatch)
4688                 return p->skip_stat_unmatch_result;
4689
4690         p->done_skip_stat_unmatch = 1;
4691         p->skip_stat_unmatch_result = 0;
4692         /*
4693          * 1. Entries that come from stat info dirtiness
4694          *    always have both sides (iow, not create/delete),
4695          *    one side of the object name is unknown, with
4696          *    the same mode and size.  Keep the ones that
4697          *    do not match these criteria.  They have real
4698          *    differences.
4699          *
4700          * 2. At this point, the file is known to be modified,
4701          *    with the same mode and size, and the object
4702          *    name of one side is unknown.  Need to inspect
4703          *    the identical contents.
4704          */
4705         if (!DIFF_FILE_VALID(p->one) || /* (1) */
4706             !DIFF_FILE_VALID(p->two) ||
4707             (p->one->sha1_valid && p->two->sha1_valid) ||
4708             (p->one->mode != p->two->mode) ||
4709             diff_populate_filespec(p->one, 1) ||
4710             diff_populate_filespec(p->two, 1) ||
4711             (p->one->size != p->two->size) ||
4712             !diff_filespec_is_identical(p->one, p->two)) /* (2) */
4713                 p->skip_stat_unmatch_result = 1;
4714         return p->skip_stat_unmatch_result;
4715 }
4716
4717 static void diffcore_skip_stat_unmatch(struct diff_options *diffopt)
4718 {
4719         int i;
4720         struct diff_queue_struct *q = &diff_queued_diff;
4721         struct diff_queue_struct outq;
4722         DIFF_QUEUE_CLEAR(&outq);
4723
4724         for (i = 0; i < q->nr; i++) {
4725                 struct diff_filepair *p = q->queue[i];
4726
4727                 if (diff_filespec_check_stat_unmatch(p))
4728                         diff_q(&outq, p);
4729                 else {
4730                         /*
4731                          * The caller can subtract 1 from skip_stat_unmatch
4732                          * to determine how many paths were dirty only
4733                          * due to stat info mismatch.
4734                          */
4735                         if (!DIFF_OPT_TST(diffopt, NO_INDEX))
4736                                 diffopt->skip_stat_unmatch++;
4737                         diff_free_filepair(p);
4738                 }
4739         }
4740         free(q->queue);
4741         *q = outq;
4742 }
4743
4744 static int diffnamecmp(const void *a_, const void *b_)
4745 {
4746         const struct diff_filepair *a = *((const struct diff_filepair **)a_);
4747         const struct diff_filepair *b = *((const struct diff_filepair **)b_);
4748         const char *name_a, *name_b;
4749
4750         name_a = a->one ? a->one->path : a->two->path;
4751         name_b = b->one ? b->one->path : b->two->path;
4752         return strcmp(name_a, name_b);
4753 }
4754
4755 void diffcore_fix_diff_index(struct diff_options *options)
4756 {
4757         struct diff_queue_struct *q = &diff_queued_diff;
4758         qsort(q->queue, q->nr, sizeof(q->queue[0]), diffnamecmp);
4759 }
4760
4761 void diffcore_std(struct diff_options *options)
4762 {
4763         if (options->skip_stat_unmatch)
4764                 diffcore_skip_stat_unmatch(options);
4765         if (!options->found_follow) {
4766                 /* See try_to_follow_renames() in tree-diff.c */
4767                 if (options->break_opt != -1)
4768                         diffcore_break(options->break_opt);
4769                 if (options->detect_rename)
4770                         diffcore_rename(options);
4771                 if (options->break_opt != -1)
4772                         diffcore_merge_broken();
4773         }
4774         if (options->pickaxe)
4775                 diffcore_pickaxe(options);
4776         if (options->orderfile)
4777                 diffcore_order(options->orderfile);
4778         if (!options->found_follow)
4779                 /* See try_to_follow_renames() in tree-diff.c */
4780                 diff_resolve_rename_copy();
4781         diffcore_apply_filter(options);
4782
4783         if (diff_queued_diff.nr && !DIFF_OPT_TST(options, DIFF_FROM_CONTENTS))
4784                 DIFF_OPT_SET(options, HAS_CHANGES);
4785         else
4786                 DIFF_OPT_CLR(options, HAS_CHANGES);
4787
4788         options->found_follow = 0;
4789 }
4790
4791 int diff_result_code(struct diff_options *opt, int status)
4792 {
4793         int result = 0;
4794
4795         diff_warn_rename_limit("diff.renameLimit",
4796                                opt->needed_rename_limit,
4797                                opt->degraded_cc_to_c);
4798         if (!DIFF_OPT_TST(opt, EXIT_WITH_STATUS) &&
4799             !(opt->output_format & DIFF_FORMAT_CHECKDIFF))
4800                 return status;
4801         if (DIFF_OPT_TST(opt, EXIT_WITH_STATUS) &&
4802             DIFF_OPT_TST(opt, HAS_CHANGES))
4803                 result |= 01;
4804         if ((opt->output_format & DIFF_FORMAT_CHECKDIFF) &&
4805             DIFF_OPT_TST(opt, CHECK_FAILED))
4806                 result |= 02;
4807         return result;
4808 }
4809
4810 int diff_can_quit_early(struct diff_options *opt)
4811 {
4812         return (DIFF_OPT_TST(opt, QUICK) &&
4813                 !opt->filter &&
4814                 DIFF_OPT_TST(opt, HAS_CHANGES));
4815 }
4816
4817 /*
4818  * Shall changes to this submodule be ignored?
4819  *
4820  * Submodule changes can be configured to be ignored separately for each path,
4821  * but that configuration can be overridden from the command line.
4822  */
4823 static int is_submodule_ignored(const char *path, struct diff_options *options)
4824 {
4825         int ignored = 0;
4826         unsigned orig_flags = options->flags;
4827         if (!DIFF_OPT_TST(options, OVERRIDE_SUBMODULE_CONFIG))
4828                 set_diffopt_flags_from_submodule_config(options, path);
4829         if (DIFF_OPT_TST(options, IGNORE_SUBMODULES))
4830                 ignored = 1;
4831         options->flags = orig_flags;
4832         return ignored;
4833 }
4834
4835 void diff_addremove(struct diff_options *options,
4836                     int addremove, unsigned mode,
4837                     const unsigned char *sha1,
4838                     int sha1_valid,
4839                     const char *concatpath, unsigned dirty_submodule)
4840 {
4841         struct diff_filespec *one, *two;
4842
4843         if (S_ISGITLINK(mode) && is_submodule_ignored(concatpath, options))
4844                 return;
4845
4846         /* This may look odd, but it is a preparation for
4847          * feeding "there are unchanged files which should
4848          * not produce diffs, but when you are doing copy
4849          * detection you would need them, so here they are"
4850          * entries to the diff-core.  They will be prefixed
4851          * with something like '=' or '*' (I haven't decided
4852          * which but should not make any difference).
4853          * Feeding the same new and old to diff_change()
4854          * also has the same effect.
4855          * Before the final output happens, they are pruned after
4856          * merged into rename/copy pairs as appropriate.
4857          */
4858         if (DIFF_OPT_TST(options, REVERSE_DIFF))
4859                 addremove = (addremove == '+' ? '-' :
4860                              addremove == '-' ? '+' : addremove);
4861
4862         if (options->prefix &&
4863             strncmp(concatpath, options->prefix, options->prefix_length))
4864                 return;
4865
4866         one = alloc_filespec(concatpath);
4867         two = alloc_filespec(concatpath);
4868
4869         if (addremove != '+')
4870                 fill_filespec(one, sha1, sha1_valid, mode);
4871         if (addremove != '-') {
4872                 fill_filespec(two, sha1, sha1_valid, mode);
4873                 two->dirty_submodule = dirty_submodule;
4874         }
4875
4876         diff_queue(&diff_queued_diff, one, two);
4877         if (!DIFF_OPT_TST(options, DIFF_FROM_CONTENTS))
4878                 DIFF_OPT_SET(options, HAS_CHANGES);
4879 }
4880
4881 void diff_change(struct diff_options *options,
4882                  unsigned old_mode, unsigned new_mode,
4883                  const unsigned char *old_sha1,
4884                  const unsigned char *new_sha1,
4885                  int old_sha1_valid, int new_sha1_valid,
4886                  const char *concatpath,
4887                  unsigned old_dirty_submodule, unsigned new_dirty_submodule)
4888 {
4889         struct diff_filespec *one, *two;
4890         struct diff_filepair *p;
4891
4892         if (S_ISGITLINK(old_mode) && S_ISGITLINK(new_mode) &&
4893             is_submodule_ignored(concatpath, options))
4894                 return;
4895
4896         if (DIFF_OPT_TST(options, REVERSE_DIFF)) {
4897                 unsigned tmp;
4898                 const unsigned char *tmp_c;
4899                 tmp = old_mode; old_mode = new_mode; new_mode = tmp;
4900                 tmp_c = old_sha1; old_sha1 = new_sha1; new_sha1 = tmp_c;
4901                 tmp = old_sha1_valid; old_sha1_valid = new_sha1_valid;
4902                         new_sha1_valid = tmp;
4903                 tmp = old_dirty_submodule; old_dirty_submodule = new_dirty_submodule;
4904                         new_dirty_submodule = tmp;
4905         }
4906
4907         if (options->prefix &&
4908             strncmp(concatpath, options->prefix, options->prefix_length))
4909                 return;
4910
4911         one = alloc_filespec(concatpath);
4912         two = alloc_filespec(concatpath);
4913         fill_filespec(one, old_sha1, old_sha1_valid, old_mode);
4914         fill_filespec(two, new_sha1, new_sha1_valid, new_mode);
4915         one->dirty_submodule = old_dirty_submodule;
4916         two->dirty_submodule = new_dirty_submodule;
4917         p = diff_queue(&diff_queued_diff, one, two);
4918
4919         if (DIFF_OPT_TST(options, DIFF_FROM_CONTENTS))
4920                 return;
4921
4922         if (DIFF_OPT_TST(options, QUICK) && options->skip_stat_unmatch &&
4923             !diff_filespec_check_stat_unmatch(p))
4924                 return;
4925
4926         DIFF_OPT_SET(options, HAS_CHANGES);
4927 }
4928
4929 struct diff_filepair *diff_unmerge(struct diff_options *options, const char *path)
4930 {
4931         struct diff_filepair *pair;
4932         struct diff_filespec *one, *two;
4933
4934         if (options->prefix &&
4935             strncmp(path, options->prefix, options->prefix_length))
4936                 return NULL;
4937
4938         one = alloc_filespec(path);
4939         two = alloc_filespec(path);
4940         pair = diff_queue(&diff_queued_diff, one, two);
4941         pair->is_unmerged = 1;
4942         return pair;
4943 }
4944
4945 static char *run_textconv(const char *pgm, struct diff_filespec *spec,
4946                 size_t *outsize)
4947 {
4948         struct diff_tempfile *temp;
4949         const char *argv[3];
4950         const char **arg = argv;
4951         struct child_process child;
4952         struct strbuf buf = STRBUF_INIT;
4953         int err = 0;
4954
4955         temp = prepare_temp_file(spec->path, spec);
4956         *arg++ = pgm;
4957         *arg++ = temp->name;
4958         *arg = NULL;
4959
4960         memset(&child, 0, sizeof(child));
4961         child.use_shell = 1;
4962         child.argv = argv;
4963         child.out = -1;
4964         if (start_command(&child)) {
4965                 remove_tempfile();
4966                 return NULL;
4967         }
4968
4969         if (strbuf_read(&buf, child.out, 0) < 0)
4970                 err = error("error reading from textconv command '%s'", pgm);
4971         close(child.out);
4972
4973         if (finish_command(&child) || err) {
4974                 strbuf_release(&buf);
4975                 remove_tempfile();
4976                 return NULL;
4977         }
4978         remove_tempfile();
4979
4980         return strbuf_detach(&buf, outsize);
4981 }
4982
4983 size_t fill_textconv(struct userdiff_driver *driver,
4984                      struct diff_filespec *df,
4985                      char **outbuf)
4986 {
4987         size_t size;
4988
4989         if (!driver || !driver->textconv) {
4990                 if (!DIFF_FILE_VALID(df)) {
4991                         *outbuf = "";
4992                         return 0;
4993                 }
4994                 if (diff_populate_filespec(df, 0))
4995                         die("unable to read files to diff");
4996                 *outbuf = df->data;
4997                 return df->size;
4998         }
4999
5000         if (driver->textconv_cache && df->sha1_valid) {
5001                 *outbuf = notes_cache_get(driver->textconv_cache, df->sha1,
5002                                           &size);
5003                 if (*outbuf)
5004                         return size;
5005         }
5006
5007         *outbuf = run_textconv(driver->textconv, df, &size);
5008         if (!*outbuf)
5009                 die("unable to read files to diff");
5010
5011         if (driver->textconv_cache && df->sha1_valid) {
5012                 /* ignore errors, as we might be in a readonly repository */
5013                 notes_cache_put(driver->textconv_cache, df->sha1, *outbuf,
5014                                 size);
5015                 /*
5016                  * we could save up changes and flush them all at the end,
5017                  * but we would need an extra call after all diffing is done.
5018                  * Since generating a cache entry is the slow path anyway,
5019                  * this extra overhead probably isn't a big deal.
5020                  */
5021                 notes_cache_write(driver->textconv_cache);
5022         }
5023
5024         return size;
5025 }
5026
5027 void setup_diff_pager(struct diff_options *opt)
5028 {
5029         /*
5030          * If the user asked for our exit code, then either they want --quiet
5031          * or --exit-code. We should definitely not bother with a pager in the
5032          * former case, as we will generate no output. Since we still properly
5033          * report our exit code even when a pager is run, we _could_ run a
5034          * pager with --exit-code. But since we have not done so historically,
5035          * and because it is easy to find people oneline advising "git diff
5036          * --exit-code" in hooks and other scripts, we do not do so.
5037          */
5038         if (!DIFF_OPT_TST(opt, EXIT_WITH_STATUS) &&
5039             check_pager_config("diff") != 0)
5040                 setup_pager();
5041 }