Document git-patch-id a bit better.
[git.git] / diff.c
1 /*
2  * Copyright (C) 2005 Junio C Hamano
3  */
4 #include <sys/types.h>
5 #include <sys/wait.h>
6 #include <signal.h>
7 #include "cache.h"
8 #include "quote.h"
9 #include "diff.h"
10 #include "diffcore.h"
11
12 static const char *diff_opts = "-pu";
13
14 static int use_size_cache;
15
16 static char *quote_one(const char *str)
17 {
18         int needlen;
19         char *xp;
20
21         if (!str)
22                 return NULL;
23         needlen = quote_c_style(str, NULL, NULL, 0);
24         if (!needlen)
25                 return strdup(str);
26         xp = xmalloc(needlen + 1);
27         quote_c_style(str, xp, NULL, 0);
28         return xp;
29 }
30
31 static char *quote_two(const char *one, const char *two)
32 {
33         int need_one = quote_c_style(one, NULL, NULL, 1);
34         int need_two = quote_c_style(two, NULL, NULL, 1);
35         char *xp;
36
37         if (need_one + need_two) {
38                 if (!need_one) need_one = strlen(one);
39                 if (!need_two) need_one = strlen(two);
40
41                 xp = xmalloc(need_one + need_two + 3);
42                 xp[0] = '"';
43                 quote_c_style(one, xp + 1, NULL, 1);
44                 quote_c_style(two, xp + need_one + 1, NULL, 1);
45                 strcpy(xp + need_one + need_two + 1, "\"");
46                 return xp;
47         }
48         need_one = strlen(one);
49         need_two = strlen(two);
50         xp = xmalloc(need_one + need_two + 1);
51         strcpy(xp, one);
52         strcpy(xp + need_one, two);
53         return xp;
54 }
55
56 static const char *external_diff(void)
57 {
58         static const char *external_diff_cmd = NULL;
59         static int done_preparing = 0;
60         const char *env_diff_opts;
61
62         if (done_preparing)
63                 return external_diff_cmd;
64
65         /*
66          * Default values above are meant to match the
67          * Linux kernel development style.  Examples of
68          * alternative styles you can specify via environment
69          * variables are:
70          *
71          * GIT_DIFF_OPTS="-c";
72          */
73         external_diff_cmd = getenv("GIT_EXTERNAL_DIFF");
74
75         /* In case external diff fails... */
76         env_diff_opts = getenv("GIT_DIFF_OPTS");
77         if (env_diff_opts) diff_opts = env_diff_opts;
78
79         done_preparing = 1;
80         return external_diff_cmd;
81 }
82
83 #define TEMPFILE_PATH_LEN               50
84
85 static struct diff_tempfile {
86         const char *name; /* filename external diff should read from */
87         char hex[41];
88         char mode[10];
89         char tmp_path[TEMPFILE_PATH_LEN];
90 } diff_temp[2];
91
92 static int count_lines(const char *filename)
93 {
94         FILE *in;
95         int count, ch, completely_empty = 1, nl_just_seen = 0;
96         in = fopen(filename, "r");
97         count = 0;
98         while ((ch = fgetc(in)) != EOF)
99                 if (ch == '\n') {
100                         count++;
101                         nl_just_seen = 1;
102                         completely_empty = 0;
103                 }
104                 else {
105                         nl_just_seen = 0;
106                         completely_empty = 0;
107                 }
108         fclose(in);
109         if (completely_empty)
110                 return 0;
111         if (!nl_just_seen)
112                 count++; /* no trailing newline */
113         return count;
114 }
115
116 static void print_line_count(int count)
117 {
118         switch (count) {
119         case 0:
120                 printf("0,0");
121                 break;
122         case 1:
123                 printf("1");
124                 break;
125         default:
126                 printf("1,%d", count);
127                 break;
128         }
129 }
130
131 static void copy_file(int prefix, const char *filename)
132 {
133         FILE *in;
134         int ch, nl_just_seen = 1;
135         in = fopen(filename, "r");
136         while ((ch = fgetc(in)) != EOF) {
137                 if (nl_just_seen)
138                         putchar(prefix);
139                 putchar(ch);
140                 if (ch == '\n')
141                         nl_just_seen = 1;
142                 else
143                         nl_just_seen = 0;
144         }
145         fclose(in);
146         if (!nl_just_seen)
147                 printf("\n\\ No newline at end of file\n");
148 }
149
150 static void emit_rewrite_diff(const char *name_a,
151                               const char *name_b,
152                               struct diff_tempfile *temp)
153 {
154         /* Use temp[i].name as input, name_a and name_b as labels */
155         int lc_a, lc_b;
156         lc_a = count_lines(temp[0].name);
157         lc_b = count_lines(temp[1].name);
158         printf("--- %s\n+++ %s\n@@ -", name_a, name_b);
159         print_line_count(lc_a);
160         printf(" +");
161         print_line_count(lc_b);
162         printf(" @@\n");
163         if (lc_a)
164                 copy_file('-', temp[0].name);
165         if (lc_b)
166                 copy_file('+', temp[1].name);
167 }
168
169 static void builtin_diff(const char *name_a,
170                          const char *name_b,
171                          struct diff_tempfile *temp,
172                          const char *xfrm_msg,
173                          int complete_rewrite)
174 {
175         int i, next_at, cmd_size;
176         const char *const diff_cmd = "diff -L%s -L%s";
177         const char *const diff_arg  = "-- %s %s||:"; /* "||:" is to return 0 */
178         const char *input_name_sq[2];
179         const char *label_path[2];
180         char *cmd;
181
182         /* diff_cmd and diff_arg have 4 %s in total which makes
183          * the sum of these strings 8 bytes larger than required.
184          * we use 2 spaces around diff-opts, and we need to count
185          * terminating NUL; we used to subtract 5 here, but we do not
186          * care about small leaks in this subprocess that is about
187          * to exec "diff" anymore.
188          */
189         cmd_size = (strlen(diff_cmd) + strlen(diff_opts) + strlen(diff_arg)
190                     + 128);
191
192         for (i = 0; i < 2; i++) {
193                 input_name_sq[i] = sq_quote(temp[i].name);
194                 if (!strcmp(temp[i].name, "/dev/null"))
195                         label_path[i] = "/dev/null";
196                 else if (!i)
197                         label_path[i] = sq_quote(quote_two("a/", name_a));
198                 else
199                         label_path[i] = sq_quote(quote_two("b/", name_b));
200                 cmd_size += (strlen(label_path[i]) + strlen(input_name_sq[i]));
201         }
202
203         cmd = xmalloc(cmd_size);
204
205         next_at = 0;
206         next_at += snprintf(cmd+next_at, cmd_size-next_at,
207                             diff_cmd, label_path[0], label_path[1]);
208         next_at += snprintf(cmd+next_at, cmd_size-next_at,
209                             " %s ", diff_opts);
210         next_at += snprintf(cmd+next_at, cmd_size-next_at,
211                             diff_arg, input_name_sq[0], input_name_sq[1]);
212
213         printf("diff --git %s %s\n",
214                quote_two("a/", name_a), quote_two("b/", name_b));
215         if (label_path[0][0] == '/') {
216                 /* dev/null */
217                 printf("new file mode %s\n", temp[1].mode);
218                 if (xfrm_msg && xfrm_msg[0])
219                         puts(xfrm_msg);
220         }
221         else if (label_path[1][0] == '/') {
222                 printf("deleted file mode %s\n", temp[0].mode);
223                 if (xfrm_msg && xfrm_msg[0])
224                         puts(xfrm_msg);
225         }
226         else {
227                 if (strcmp(temp[0].mode, temp[1].mode)) {
228                         printf("old mode %s\n", temp[0].mode);
229                         printf("new mode %s\n", temp[1].mode);
230                 }
231                 if (xfrm_msg && xfrm_msg[0])
232                         puts(xfrm_msg);
233                 if (strncmp(temp[0].mode, temp[1].mode, 3))
234                         /* we do not run diff between different kind
235                          * of objects.
236                          */
237                         exit(0);
238                 if (complete_rewrite) {
239                         fflush(NULL);
240                         emit_rewrite_diff(name_a, name_b, temp);
241                         exit(0);
242                 }
243         }
244         fflush(NULL);
245         execlp("/bin/sh","sh", "-c", cmd, NULL);
246 }
247
248 struct diff_filespec *alloc_filespec(const char *path)
249 {
250         int namelen = strlen(path);
251         struct diff_filespec *spec = xmalloc(sizeof(*spec) + namelen + 1);
252
253         memset(spec, 0, sizeof(*spec));
254         spec->path = (char *)(spec + 1);
255         memcpy(spec->path, path, namelen+1);
256         return spec;
257 }
258
259 void fill_filespec(struct diff_filespec *spec, const unsigned char *sha1,
260                    unsigned short mode)
261 {
262         if (mode) {
263                 spec->mode = DIFF_FILE_CANON_MODE(mode);
264                 memcpy(spec->sha1, sha1, 20);
265                 spec->sha1_valid = !!memcmp(sha1, null_sha1, 20);
266         }
267 }
268
269 /*
270  * Given a name and sha1 pair, if the dircache tells us the file in
271  * the work tree has that object contents, return true, so that
272  * prepare_temp_file() does not have to inflate and extract.
273  */
274 static int work_tree_matches(const char *name, const unsigned char *sha1)
275 {
276         struct cache_entry *ce;
277         struct stat st;
278         int pos, len;
279
280         /* We do not read the cache ourselves here, because the
281          * benchmark with my previous version that always reads cache
282          * shows that it makes things worse for diff-tree comparing
283          * two linux-2.6 kernel trees in an already checked out work
284          * tree.  This is because most diff-tree comparisons deal with
285          * only a small number of files, while reading the cache is
286          * expensive for a large project, and its cost outweighs the
287          * savings we get by not inflating the object to a temporary
288          * file.  Practically, this code only helps when we are used
289          * by diff-cache --cached, which does read the cache before
290          * calling us.
291          */
292         if (!active_cache)
293                 return 0;
294
295         len = strlen(name);
296         pos = cache_name_pos(name, len);
297         if (pos < 0)
298                 return 0;
299         ce = active_cache[pos];
300         if ((lstat(name, &st) < 0) ||
301             !S_ISREG(st.st_mode) || /* careful! */
302             ce_match_stat(ce, &st) ||
303             memcmp(sha1, ce->sha1, 20))
304                 return 0;
305         /* we return 1 only when we can stat, it is a regular file,
306          * stat information matches, and sha1 recorded in the cache
307          * matches.  I.e. we know the file in the work tree really is
308          * the same as the <name, sha1> pair.
309          */
310         return 1;
311 }
312
313 static struct sha1_size_cache {
314         unsigned char sha1[20];
315         unsigned long size;
316 } **sha1_size_cache;
317 static int sha1_size_cache_nr, sha1_size_cache_alloc;
318
319 static struct sha1_size_cache *locate_size_cache(unsigned char *sha1,
320                                                  int find_only,
321                                                  unsigned long size)
322 {
323         int first, last;
324         struct sha1_size_cache *e;
325
326         first = 0;
327         last = sha1_size_cache_nr;
328         while (last > first) {
329                 int cmp, next = (last + first) >> 1;
330                 e = sha1_size_cache[next];
331                 cmp = memcmp(e->sha1, sha1, 20);
332                 if (!cmp)
333                         return e;
334                 if (cmp < 0) {
335                         last = next;
336                         continue;
337                 }
338                 first = next+1;
339         }
340         /* not found */
341         if (find_only)
342                 return NULL;
343         /* insert to make it at "first" */
344         if (sha1_size_cache_alloc <= sha1_size_cache_nr) {
345                 sha1_size_cache_alloc = alloc_nr(sha1_size_cache_alloc);
346                 sha1_size_cache = xrealloc(sha1_size_cache,
347                                            sha1_size_cache_alloc *
348                                            sizeof(*sha1_size_cache));
349         }
350         sha1_size_cache_nr++;
351         if (first < sha1_size_cache_nr)
352                 memmove(sha1_size_cache + first + 1, sha1_size_cache + first,
353                         (sha1_size_cache_nr - first - 1) *
354                         sizeof(*sha1_size_cache));
355         e = xmalloc(sizeof(struct sha1_size_cache));
356         sha1_size_cache[first] = e;
357         memcpy(e->sha1, sha1, 20);
358         e->size = size;
359         return e;
360 }
361
362 /*
363  * While doing rename detection and pickaxe operation, we may need to
364  * grab the data for the blob (or file) for our own in-core comparison.
365  * diff_filespec has data and size fields for this purpose.
366  */
367 int diff_populate_filespec(struct diff_filespec *s, int size_only)
368 {
369         int err = 0;
370         if (!DIFF_FILE_VALID(s))
371                 die("internal error: asking to populate invalid file.");
372         if (S_ISDIR(s->mode))
373                 return -1;
374
375         if (!use_size_cache)
376                 size_only = 0;
377
378         if (s->data)
379                 return err;
380         if (!s->sha1_valid ||
381             work_tree_matches(s->path, s->sha1)) {
382                 struct stat st;
383                 int fd;
384                 if (lstat(s->path, &st) < 0) {
385                         if (errno == ENOENT) {
386                         err_empty:
387                                 err = -1;
388                         empty:
389                                 s->data = "";
390                                 s->size = 0;
391                                 return err;
392                         }
393                 }
394                 s->size = st.st_size;
395                 if (!s->size)
396                         goto empty;
397                 if (size_only)
398                         return 0;
399                 if (S_ISLNK(st.st_mode)) {
400                         int ret;
401                         s->data = xmalloc(s->size);
402                         s->should_free = 1;
403                         ret = readlink(s->path, s->data, s->size);
404                         if (ret < 0) {
405                                 free(s->data);
406                                 goto err_empty;
407                         }
408                         return 0;
409                 }
410                 fd = open(s->path, O_RDONLY);
411                 if (fd < 0)
412                         goto err_empty;
413                 s->data = mmap(NULL, s->size, PROT_READ, MAP_PRIVATE, fd, 0);
414                 close(fd);
415                 if (s->data == MAP_FAILED)
416                         goto err_empty;
417                 s->should_munmap = 1;
418         }
419         else {
420                 char type[20];
421                 struct sha1_size_cache *e;
422
423                 if (size_only) {
424                         e = locate_size_cache(s->sha1, 1, 0);
425                         if (e) {
426                                 s->size = e->size;
427                                 return 0;
428                         }
429                         if (!sha1_object_info(s->sha1, type, &s->size))
430                                 locate_size_cache(s->sha1, 0, s->size);
431                 }
432                 else {
433                         s->data = read_sha1_file(s->sha1, type, &s->size);
434                         s->should_free = 1;
435                 }
436         }
437         return 0;
438 }
439
440 void diff_free_filespec_data(struct diff_filespec *s)
441 {
442         if (s->should_free)
443                 free(s->data);
444         else if (s->should_munmap)
445                 munmap(s->data, s->size);
446         s->should_free = s->should_munmap = 0;
447         s->data = NULL;
448 }
449
450 static void prep_temp_blob(struct diff_tempfile *temp,
451                            void *blob,
452                            unsigned long size,
453                            const unsigned char *sha1,
454                            int mode)
455 {
456         int fd;
457
458         fd = git_mkstemp(temp->tmp_path, TEMPFILE_PATH_LEN, ".diff_XXXXXX");
459         if (fd < 0)
460                 die("unable to create temp-file");
461         if (write(fd, blob, size) != size)
462                 die("unable to write temp-file");
463         close(fd);
464         temp->name = temp->tmp_path;
465         strcpy(temp->hex, sha1_to_hex(sha1));
466         temp->hex[40] = 0;
467         sprintf(temp->mode, "%06o", mode);
468 }
469
470 static void prepare_temp_file(const char *name,
471                               struct diff_tempfile *temp,
472                               struct diff_filespec *one)
473 {
474         if (!DIFF_FILE_VALID(one)) {
475         not_a_valid_file:
476                 /* A '-' entry produces this for file-2, and
477                  * a '+' entry produces this for file-1.
478                  */
479                 temp->name = "/dev/null";
480                 strcpy(temp->hex, ".");
481                 strcpy(temp->mode, ".");
482                 return;
483         }
484
485         if (!one->sha1_valid ||
486             work_tree_matches(name, one->sha1)) {
487                 struct stat st;
488                 if (lstat(name, &st) < 0) {
489                         if (errno == ENOENT)
490                                 goto not_a_valid_file;
491                         die("stat(%s): %s", name, strerror(errno));
492                 }
493                 if (S_ISLNK(st.st_mode)) {
494                         int ret;
495                         char *buf, buf_[1024];
496                         buf = ((sizeof(buf_) < st.st_size) ?
497                                xmalloc(st.st_size) : buf_);
498                         ret = readlink(name, buf, st.st_size);
499                         if (ret < 0)
500                                 die("readlink(%s)", name);
501                         prep_temp_blob(temp, buf, st.st_size,
502                                        (one->sha1_valid ?
503                                         one->sha1 : null_sha1),
504                                        (one->sha1_valid ?
505                                         one->mode : S_IFLNK));
506                 }
507                 else {
508                         /* we can borrow from the file in the work tree */
509                         temp->name = name;
510                         if (!one->sha1_valid)
511                                 strcpy(temp->hex, sha1_to_hex(null_sha1));
512                         else
513                                 strcpy(temp->hex, sha1_to_hex(one->sha1));
514                         /* Even though we may sometimes borrow the
515                          * contents from the work tree, we always want
516                          * one->mode.  mode is trustworthy even when
517                          * !(one->sha1_valid), as long as
518                          * DIFF_FILE_VALID(one).
519                          */
520                         sprintf(temp->mode, "%06o", one->mode);
521                 }
522                 return;
523         }
524         else {
525                 if (diff_populate_filespec(one, 0))
526                         die("cannot read data blob for %s", one->path);
527                 prep_temp_blob(temp, one->data, one->size,
528                                one->sha1, one->mode);
529         }
530 }
531
532 static void remove_tempfile(void)
533 {
534         int i;
535
536         for (i = 0; i < 2; i++)
537                 if (diff_temp[i].name == diff_temp[i].tmp_path) {
538                         unlink(diff_temp[i].name);
539                         diff_temp[i].name = NULL;
540                 }
541 }
542
543 static void remove_tempfile_on_signal(int signo)
544 {
545         remove_tempfile();
546 }
547
548 /* An external diff command takes:
549  *
550  * diff-cmd name infile1 infile1-sha1 infile1-mode \
551  *               infile2 infile2-sha1 infile2-mode [ rename-to ]
552  *
553  */
554 static void run_external_diff(const char *pgm,
555                               const char *name,
556                               const char *other,
557                               struct diff_filespec *one,
558                               struct diff_filespec *two,
559                               const char *xfrm_msg,
560                               int complete_rewrite)
561 {
562         struct diff_tempfile *temp = diff_temp;
563         pid_t pid;
564         int status;
565         static int atexit_asked = 0;
566         const char *othername;
567
568         othername = (other? other : name);
569         if (one && two) {
570                 prepare_temp_file(name, &temp[0], one);
571                 prepare_temp_file(othername, &temp[1], two);
572                 if (! atexit_asked &&
573                     (temp[0].name == temp[0].tmp_path ||
574                      temp[1].name == temp[1].tmp_path)) {
575                         atexit_asked = 1;
576                         atexit(remove_tempfile);
577                 }
578                 signal(SIGINT, remove_tempfile_on_signal);
579         }
580
581         fflush(NULL);
582         pid = fork();
583         if (pid < 0)
584                 die("unable to fork");
585         if (!pid) {
586                 if (pgm) {
587                         if (one && two) {
588                                 const char *exec_arg[10];
589                                 const char **arg = &exec_arg[0];
590                                 *arg++ = pgm;
591                                 *arg++ = name;
592                                 *arg++ = temp[0].name;
593                                 *arg++ = temp[0].hex;
594                                 *arg++ = temp[0].mode;
595                                 *arg++ = temp[1].name;
596                                 *arg++ = temp[1].hex;
597                                 *arg++ = temp[1].mode;
598                                 if (other) {
599                                         *arg++ = other;
600                                         *arg++ = xfrm_msg;
601                                 }
602                                 *arg = NULL;
603                                 execvp(pgm, (char *const*) exec_arg);
604                         }
605                         else
606                                 execlp(pgm, pgm, name, NULL);
607                 }
608                 /*
609                  * otherwise we use the built-in one.
610                  */
611                 if (one && two)
612                         builtin_diff(name, othername, temp, xfrm_msg,
613                                      complete_rewrite);
614                 else
615                         printf("* Unmerged path %s\n", name);
616                 exit(0);
617         }
618         if (waitpid(pid, &status, 0) < 0 ||
619             !WIFEXITED(status) || WEXITSTATUS(status)) {
620                 /* Earlier we did not check the exit status because
621                  * diff exits non-zero if files are different, and
622                  * we are not interested in knowing that.  It was a
623                  * mistake which made it harder to quit a diff-*
624                  * session that uses the git-apply-patch-script as
625                  * the GIT_EXTERNAL_DIFF.  A custom GIT_EXTERNAL_DIFF
626                  * should also exit non-zero only when it wants to
627                  * abort the entire diff-* session.
628                  */
629                 remove_tempfile();
630                 fprintf(stderr, "external diff died, stopping at %s.\n", name);
631                 exit(1);
632         }
633         remove_tempfile();
634 }
635
636 static void diff_fill_sha1_info(struct diff_filespec *one)
637 {
638         if (DIFF_FILE_VALID(one)) {
639                 if (!one->sha1_valid) {
640                         struct stat st;
641                         if (stat(one->path, &st) < 0)
642                                 die("stat %s", one->path);
643                         if (index_path(one->sha1, one->path, &st, 0))
644                                 die("cannot hash %s\n", one->path);
645                 }
646         }
647         else
648                 memset(one->sha1, 0, 20);
649 }
650
651 static void run_diff(struct diff_filepair *p)
652 {
653         const char *pgm = external_diff();
654         char msg[PATH_MAX*2+300], *xfrm_msg;
655         struct diff_filespec *one;
656         struct diff_filespec *two;
657         const char *name;
658         const char *other;
659         char *name_munged, *other_munged;
660         int complete_rewrite = 0;
661         int len;
662
663         if (DIFF_PAIR_UNMERGED(p)) {
664                 /* unmerged */
665                 run_external_diff(pgm, p->one->path, NULL, NULL, NULL, NULL,
666                                   0);
667                 return;
668         }
669
670         name = p->one->path;
671         other = (strcmp(name, p->two->path) ? p->two->path : NULL);
672         name_munged = quote_one(name);
673         other_munged = quote_one(other);
674         one = p->one; two = p->two;
675
676         diff_fill_sha1_info(one);
677         diff_fill_sha1_info(two);
678
679         len = 0;
680         switch (p->status) {
681         case DIFF_STATUS_COPIED:
682                 len += snprintf(msg + len, sizeof(msg) - len,
683                                 "similarity index %d%%\n"
684                                 "copy from %s\n"
685                                 "copy to %s\n",
686                                 (int)(0.5 + p->score * 100.0/MAX_SCORE),
687                                 name_munged, other_munged);
688                 break;
689         case DIFF_STATUS_RENAMED:
690                 len += snprintf(msg + len, sizeof(msg) - len,
691                                 "similarity index %d%%\n"
692                                 "rename from %s\n"
693                                 "rename to %s\n",
694                                 (int)(0.5 + p->score * 100.0/MAX_SCORE),
695                                 name_munged, other_munged);
696                 break;
697         case DIFF_STATUS_MODIFIED:
698                 if (p->score) {
699                         len += snprintf(msg + len, sizeof(msg) - len,
700                                         "dissimilarity index %d%%\n",
701                                         (int)(0.5 + p->score *
702                                               100.0/MAX_SCORE));
703                         complete_rewrite = 1;
704                         break;
705                 }
706                 /* fallthru */
707         default:
708                 /* nothing */
709                 ;
710         }
711
712         if (memcmp(one->sha1, two->sha1, 20)) {
713                 char one_sha1[41];
714                 memcpy(one_sha1, sha1_to_hex(one->sha1), 41);
715
716                 len += snprintf(msg + len, sizeof(msg) - len,
717                                 "index %.7s..%.7s", one_sha1,
718                                 sha1_to_hex(two->sha1));
719                 if (one->mode == two->mode)
720                         len += snprintf(msg + len, sizeof(msg) - len,
721                                         " %06o", one->mode);
722                 len += snprintf(msg + len, sizeof(msg) - len, "\n");
723         }
724
725         if (len)
726                 msg[--len] = 0;
727         xfrm_msg = len ? msg : NULL;
728
729         if (!pgm &&
730             DIFF_FILE_VALID(one) && DIFF_FILE_VALID(two) &&
731             (S_IFMT & one->mode) != (S_IFMT & two->mode)) {
732                 /* a filepair that changes between file and symlink
733                  * needs to be split into deletion and creation.
734                  */
735                 struct diff_filespec *null = alloc_filespec(two->path);
736                 run_external_diff(NULL, name, other, one, null, xfrm_msg, 0);
737                 free(null);
738                 null = alloc_filespec(one->path);
739                 run_external_diff(NULL, name, other, null, two, xfrm_msg, 0);
740                 free(null);
741         }
742         else
743                 run_external_diff(pgm, name, other, one, two, xfrm_msg,
744                                   complete_rewrite);
745
746         free(name_munged);
747         free(other_munged);
748 }
749
750 void diff_setup(struct diff_options *options)
751 {
752         memset(options, 0, sizeof(*options));
753         options->output_format = DIFF_FORMAT_RAW;
754         options->line_termination = '\n';
755         options->break_opt = -1;
756         options->rename_limit = -1;
757
758         options->change = diff_change;
759         options->add_remove = diff_addremove;
760 }
761
762 int diff_setup_done(struct diff_options *options)
763 {
764         if ((options->find_copies_harder || 0 <= options->rename_limit) &&
765             options->detect_rename != DIFF_DETECT_COPY)
766                 return -1;
767         if (options->setup & DIFF_SETUP_USE_CACHE) {
768                 if (!active_cache)
769                         /* read-cache does not die even when it fails
770                          * so it is safe for us to do this here.  Also
771                          * it does not smudge active_cache or active_nr
772                          * when it fails, so we do not have to worry about
773                          * cleaning it up oufselves either.
774                          */
775                         read_cache();
776         }
777         if (options->setup & DIFF_SETUP_USE_SIZE_CACHE)
778                 use_size_cache = 1;
779
780         return 0;
781 }
782
783 int diff_opt_parse(struct diff_options *options, const char **av, int ac)
784 {
785         const char *arg = av[0];
786         if (!strcmp(arg, "-p") || !strcmp(arg, "-u"))
787                 options->output_format = DIFF_FORMAT_PATCH;
788         else if (!strcmp(arg, "-z"))
789                 options->line_termination = 0;
790         else if (!strncmp(arg, "-l", 2))
791                 options->rename_limit = strtoul(arg+2, NULL, 10);
792         else if (!strcmp(arg, "--name-only"))
793                 options->output_format = DIFF_FORMAT_NAME;
794         else if (!strcmp(arg, "--name-status"))
795                 options->output_format = DIFF_FORMAT_NAME_STATUS;
796         else if (!strcmp(arg, "-R"))
797                 options->reverse_diff = 1;
798         else if (!strncmp(arg, "-S", 2))
799                 options->pickaxe = arg + 2;
800         else if (!strcmp(arg, "-s"))
801                 options->output_format = DIFF_FORMAT_NO_OUTPUT;
802         else if (!strncmp(arg, "-O", 2))
803                 options->orderfile = arg + 2;
804         else if (!strncmp(arg, "--diff-filter=", 14))
805                 options->filter = arg + 14;
806         else if (!strcmp(arg, "--pickaxe-all"))
807                 options->pickaxe_opts = DIFF_PICKAXE_ALL;
808         else if (!strncmp(arg, "-B", 2)) {
809                 if ((options->break_opt =
810                      diff_scoreopt_parse(arg)) == -1)
811                         return -1;
812         }
813         else if (!strncmp(arg, "-M", 2)) {
814                 if ((options->rename_score =
815                      diff_scoreopt_parse(arg)) == -1)
816                         return -1;
817                 options->detect_rename = DIFF_DETECT_RENAME;
818         }
819         else if (!strncmp(arg, "-C", 2)) {
820                 if ((options->rename_score =
821                      diff_scoreopt_parse(arg)) == -1)
822                         return -1;
823                 options->detect_rename = DIFF_DETECT_COPY;
824         }
825         else if (!strcmp(arg, "--find-copies-harder"))
826                 options->find_copies_harder = 1;
827         else
828                 return 0;
829         return 1;
830 }
831
832 static int parse_num(const char **cp_p)
833 {
834         int num, scale, ch, cnt;
835         const char *cp = *cp_p;
836
837         cnt = num = 0;
838         scale = 1;
839         while ('0' <= (ch = *cp) && ch <= '9') {
840                 if (cnt++ < 5) {
841                         /* We simply ignore more than 5 digits precision. */
842                         scale *= 10;
843                         num = num * 10 + ch - '0';
844                 }
845                 cp++;
846         }
847         *cp_p = cp;
848
849         /* user says num divided by scale and we say internally that
850          * is MAX_SCORE * num / scale.
851          */
852         return (MAX_SCORE * num / scale);
853 }
854
855 int diff_scoreopt_parse(const char *opt)
856 {
857         int opt1, opt2, cmd;
858
859         if (*opt++ != '-')
860                 return -1;
861         cmd = *opt++;
862         if (cmd != 'M' && cmd != 'C' && cmd != 'B')
863                 return -1; /* that is not a -M, -C nor -B option */
864
865         opt1 = parse_num(&opt);
866         if (cmd != 'B')
867                 opt2 = 0;
868         else {
869                 if (*opt == 0)
870                         opt2 = 0;
871                 else if (*opt != '/')
872                         return -1; /* we expect -B80/99 or -B80 */
873                 else {
874                         opt++;
875                         opt2 = parse_num(&opt);
876                 }
877         }
878         if (*opt != 0)
879                 return -1;
880         return opt1 | (opt2 << 16);
881 }
882
883 struct diff_queue_struct diff_queued_diff;
884
885 void diff_q(struct diff_queue_struct *queue, struct diff_filepair *dp)
886 {
887         if (queue->alloc <= queue->nr) {
888                 queue->alloc = alloc_nr(queue->alloc);
889                 queue->queue = xrealloc(queue->queue,
890                                         sizeof(dp) * queue->alloc);
891         }
892         queue->queue[queue->nr++] = dp;
893 }
894
895 struct diff_filepair *diff_queue(struct diff_queue_struct *queue,
896                                  struct diff_filespec *one,
897                                  struct diff_filespec *two)
898 {
899         struct diff_filepair *dp = xmalloc(sizeof(*dp));
900         dp->one = one;
901         dp->two = two;
902         dp->score = 0;
903         dp->status = 0;
904         dp->source_stays = 0;
905         dp->broken_pair = 0;
906         if (queue)
907                 diff_q(queue, dp);
908         return dp;
909 }
910
911 void diff_free_filepair(struct diff_filepair *p)
912 {
913         diff_free_filespec_data(p->one);
914         diff_free_filespec_data(p->two);
915         free(p->one);
916         free(p->two);
917         free(p);
918 }
919
920 static void diff_flush_raw(struct diff_filepair *p,
921                            int line_termination,
922                            int inter_name_termination,
923                            int output_format)
924 {
925         int two_paths;
926         char status[10];
927         const char *path_one, *path_two;
928
929         path_one = p->one->path;
930         path_two = p->two->path;
931         if (line_termination) {
932                 path_one = quote_one(path_one);
933                 path_two = quote_one(path_two);
934         }
935
936         if (p->score)
937                 sprintf(status, "%c%03d", p->status,
938                         (int)(0.5 + p->score * 100.0/MAX_SCORE));
939         else {
940                 status[0] = p->status;
941                 status[1] = 0;
942         }
943         switch (p->status) {
944         case DIFF_STATUS_COPIED:
945         case DIFF_STATUS_RENAMED:
946                 two_paths = 1;
947                 break;
948         case DIFF_STATUS_ADDED:
949         case DIFF_STATUS_DELETED:
950                 two_paths = 0;
951                 break;
952         default:
953                 two_paths = 0;
954                 break;
955         }
956         if (output_format != DIFF_FORMAT_NAME_STATUS) {
957                 printf(":%06o %06o %s ",
958                        p->one->mode, p->two->mode, sha1_to_hex(p->one->sha1));
959                 printf("%s ", sha1_to_hex(p->two->sha1));
960         }
961         printf("%s%c%s", status, inter_name_termination, path_one);
962         if (two_paths)
963                 printf("%c%s", inter_name_termination, path_two);
964         putchar(line_termination);
965         if (path_one != p->one->path)
966                 free((void*)path_one);
967         if (path_two != p->two->path)
968                 free((void*)path_two);
969 }
970
971 static void diff_flush_name(struct diff_filepair *p,
972                             int inter_name_termination,
973                             int line_termination)
974 {
975         char *path = p->two->path;
976
977         if (line_termination)
978                 path = quote_one(p->two->path);
979         else
980                 path = p->two->path;
981         printf("%s%c", path, line_termination);
982         if (p->two->path != path)
983                 free(path);
984 }
985
986 int diff_unmodified_pair(struct diff_filepair *p)
987 {
988         /* This function is written stricter than necessary to support
989          * the currently implemented transformers, but the idea is to
990          * let transformers to produce diff_filepairs any way they want,
991          * and filter and clean them up here before producing the output.
992          */
993         struct diff_filespec *one, *two;
994
995         if (DIFF_PAIR_UNMERGED(p))
996                 return 0; /* unmerged is interesting */
997
998         one = p->one;
999         two = p->two;
1000
1001         /* deletion, addition, mode or type change
1002          * and rename are all interesting.
1003          */
1004         if (DIFF_FILE_VALID(one) != DIFF_FILE_VALID(two) ||
1005             DIFF_PAIR_MODE_CHANGED(p) ||
1006             strcmp(one->path, two->path))
1007                 return 0;
1008
1009         /* both are valid and point at the same path.  that is, we are
1010          * dealing with a change.
1011          */
1012         if (one->sha1_valid && two->sha1_valid &&
1013             !memcmp(one->sha1, two->sha1, sizeof(one->sha1)))
1014                 return 1; /* no change */
1015         if (!one->sha1_valid && !two->sha1_valid)
1016                 return 1; /* both look at the same file on the filesystem. */
1017         return 0;
1018 }
1019
1020 static void diff_flush_patch(struct diff_filepair *p)
1021 {
1022         if (diff_unmodified_pair(p))
1023                 return;
1024
1025         if ((DIFF_FILE_VALID(p->one) && S_ISDIR(p->one->mode)) ||
1026             (DIFF_FILE_VALID(p->two) && S_ISDIR(p->two->mode)))
1027                 return; /* no tree diffs in patch format */ 
1028
1029         run_diff(p);
1030 }
1031
1032 int diff_queue_is_empty(void)
1033 {
1034         struct diff_queue_struct *q = &diff_queued_diff;
1035         int i;
1036         for (i = 0; i < q->nr; i++)
1037                 if (!diff_unmodified_pair(q->queue[i]))
1038                         return 0;
1039         return 1;
1040 }
1041
1042 #if DIFF_DEBUG
1043 void diff_debug_filespec(struct diff_filespec *s, int x, const char *one)
1044 {
1045         fprintf(stderr, "queue[%d] %s (%s) %s %06o %s\n",
1046                 x, one ? one : "",
1047                 s->path,
1048                 DIFF_FILE_VALID(s) ? "valid" : "invalid",
1049                 s->mode,
1050                 s->sha1_valid ? sha1_to_hex(s->sha1) : "");
1051         fprintf(stderr, "queue[%d] %s size %lu flags %d\n",
1052                 x, one ? one : "",
1053                 s->size, s->xfrm_flags);
1054 }
1055
1056 void diff_debug_filepair(const struct diff_filepair *p, int i)
1057 {
1058         diff_debug_filespec(p->one, i, "one");
1059         diff_debug_filespec(p->two, i, "two");
1060         fprintf(stderr, "score %d, status %c stays %d broken %d\n",
1061                 p->score, p->status ? p->status : '?',
1062                 p->source_stays, p->broken_pair);
1063 }
1064
1065 void diff_debug_queue(const char *msg, struct diff_queue_struct *q)
1066 {
1067         int i;
1068         if (msg)
1069                 fprintf(stderr, "%s\n", msg);
1070         fprintf(stderr, "q->nr = %d\n", q->nr);
1071         for (i = 0; i < q->nr; i++) {
1072                 struct diff_filepair *p = q->queue[i];
1073                 diff_debug_filepair(p, i);
1074         }
1075 }
1076 #endif
1077
1078 static void diff_resolve_rename_copy(void)
1079 {
1080         int i, j;
1081         struct diff_filepair *p, *pp;
1082         struct diff_queue_struct *q = &diff_queued_diff;
1083
1084         diff_debug_queue("resolve-rename-copy", q);
1085
1086         for (i = 0; i < q->nr; i++) {
1087                 p = q->queue[i];
1088                 p->status = 0; /* undecided */
1089                 if (DIFF_PAIR_UNMERGED(p))
1090                         p->status = DIFF_STATUS_UNMERGED;
1091                 else if (!DIFF_FILE_VALID(p->one))
1092                         p->status = DIFF_STATUS_ADDED;
1093                 else if (!DIFF_FILE_VALID(p->two))
1094                         p->status = DIFF_STATUS_DELETED;
1095                 else if (DIFF_PAIR_TYPE_CHANGED(p))
1096                         p->status = DIFF_STATUS_TYPE_CHANGED;
1097
1098                 /* from this point on, we are dealing with a pair
1099                  * whose both sides are valid and of the same type, i.e.
1100                  * either in-place edit or rename/copy edit.
1101                  */
1102                 else if (DIFF_PAIR_RENAME(p)) {
1103                         if (p->source_stays) {
1104                                 p->status = DIFF_STATUS_COPIED;
1105                                 continue;
1106                         }
1107                         /* See if there is some other filepair that
1108                          * copies from the same source as us.  If so
1109                          * we are a copy.  Otherwise we are either a
1110                          * copy if the path stays, or a rename if it
1111                          * does not, but we already handled "stays" case.
1112                          */
1113                         for (j = i + 1; j < q->nr; j++) {
1114                                 pp = q->queue[j];
1115                                 if (strcmp(pp->one->path, p->one->path))
1116                                         continue; /* not us */
1117                                 if (!DIFF_PAIR_RENAME(pp))
1118                                         continue; /* not a rename/copy */
1119                                 /* pp is a rename/copy from the same source */
1120                                 p->status = DIFF_STATUS_COPIED;
1121                                 break;
1122                         }
1123                         if (!p->status)
1124                                 p->status = DIFF_STATUS_RENAMED;
1125                 }
1126                 else if (memcmp(p->one->sha1, p->two->sha1, 20) ||
1127                          p->one->mode != p->two->mode)
1128                         p->status = DIFF_STATUS_MODIFIED;
1129                 else {
1130                         /* This is a "no-change" entry and should not
1131                          * happen anymore, but prepare for broken callers.
1132                          */
1133                         error("feeding unmodified %s to diffcore",
1134                               p->one->path);
1135                         p->status = DIFF_STATUS_UNKNOWN;
1136                 }
1137         }
1138         diff_debug_queue("resolve-rename-copy done", q);
1139 }
1140
1141 void diff_flush(struct diff_options *options)
1142 {
1143         struct diff_queue_struct *q = &diff_queued_diff;
1144         int i;
1145         int inter_name_termination = '\t';
1146         int diff_output_format = options->output_format;
1147         int line_termination = options->line_termination;
1148
1149         if (!line_termination)
1150                 inter_name_termination = 0;
1151
1152         for (i = 0; i < q->nr; i++) {
1153                 struct diff_filepair *p = q->queue[i];
1154                 if ((diff_output_format == DIFF_FORMAT_NO_OUTPUT) ||
1155                     (p->status == DIFF_STATUS_UNKNOWN))
1156                         continue;
1157                 if (p->status == 0)
1158                         die("internal error in diff-resolve-rename-copy");
1159                 switch (diff_output_format) {
1160                 case DIFF_FORMAT_PATCH:
1161                         diff_flush_patch(p);
1162                         break;
1163                 case DIFF_FORMAT_RAW:
1164                 case DIFF_FORMAT_NAME_STATUS:
1165                         diff_flush_raw(p, line_termination,
1166                                        inter_name_termination,
1167                                        diff_output_format);
1168                         break;
1169                 case DIFF_FORMAT_NAME:
1170                         diff_flush_name(p,
1171                                         inter_name_termination,
1172                                         line_termination);
1173                         break;
1174                 }
1175                 diff_free_filepair(q->queue[i]);
1176         }
1177         free(q->queue);
1178         q->queue = NULL;
1179         q->nr = q->alloc = 0;
1180 }
1181
1182 static void diffcore_apply_filter(const char *filter)
1183 {
1184         int i;
1185         struct diff_queue_struct *q = &diff_queued_diff;
1186         struct diff_queue_struct outq;
1187         outq.queue = NULL;
1188         outq.nr = outq.alloc = 0;
1189
1190         if (!filter)
1191                 return;
1192
1193         if (strchr(filter, DIFF_STATUS_FILTER_AON)) {
1194                 int found;
1195                 for (i = found = 0; !found && i < q->nr; i++) {
1196                         struct diff_filepair *p = q->queue[i];
1197                         if (((p->status == DIFF_STATUS_MODIFIED) &&
1198                              ((p->score &&
1199                                strchr(filter, DIFF_STATUS_FILTER_BROKEN)) ||
1200                               (!p->score &&
1201                                strchr(filter, DIFF_STATUS_MODIFIED)))) ||
1202                             ((p->status != DIFF_STATUS_MODIFIED) &&
1203                              strchr(filter, p->status)))
1204                                 found++;
1205                 }
1206                 if (found)
1207                         return;
1208
1209                 /* otherwise we will clear the whole queue
1210                  * by copying the empty outq at the end of this
1211                  * function, but first clear the current entries
1212                  * in the queue.
1213                  */
1214                 for (i = 0; i < q->nr; i++)
1215                         diff_free_filepair(q->queue[i]);
1216         }
1217         else {
1218                 /* Only the matching ones */
1219                 for (i = 0; i < q->nr; i++) {
1220                         struct diff_filepair *p = q->queue[i];
1221
1222                         if (((p->status == DIFF_STATUS_MODIFIED) &&
1223                              ((p->score &&
1224                                strchr(filter, DIFF_STATUS_FILTER_BROKEN)) ||
1225                               (!p->score &&
1226                                strchr(filter, DIFF_STATUS_MODIFIED)))) ||
1227                             ((p->status != DIFF_STATUS_MODIFIED) &&
1228                              strchr(filter, p->status)))
1229                                 diff_q(&outq, p);
1230                         else
1231                                 diff_free_filepair(p);
1232                 }
1233         }
1234         free(q->queue);
1235         *q = outq;
1236 }
1237
1238 void diffcore_std(struct diff_options *options)
1239 {
1240         if (options->paths && options->paths[0])
1241                 diffcore_pathspec(options->paths);
1242         if (options->break_opt != -1)
1243                 diffcore_break(options->break_opt);
1244         if (options->detect_rename)
1245                 diffcore_rename(options);
1246         if (options->break_opt != -1)
1247                 diffcore_merge_broken();
1248         if (options->pickaxe)
1249                 diffcore_pickaxe(options->pickaxe, options->pickaxe_opts);
1250         if (options->orderfile)
1251                 diffcore_order(options->orderfile);
1252         diff_resolve_rename_copy();
1253         diffcore_apply_filter(options->filter);
1254 }
1255
1256
1257 void diffcore_std_no_resolve(struct diff_options *options)
1258 {
1259         if (options->pickaxe)
1260                 diffcore_pickaxe(options->pickaxe, options->pickaxe_opts);
1261         if (options->orderfile)
1262                 diffcore_order(options->orderfile);
1263         diffcore_apply_filter(options->filter);
1264 }
1265
1266 void diff_addremove(struct diff_options *options,
1267                     int addremove, unsigned mode,
1268                     const unsigned char *sha1,
1269                     const char *base, const char *path)
1270 {
1271         char concatpath[PATH_MAX];
1272         struct diff_filespec *one, *two;
1273
1274         /* This may look odd, but it is a preparation for
1275          * feeding "there are unchanged files which should
1276          * not produce diffs, but when you are doing copy
1277          * detection you would need them, so here they are"
1278          * entries to the diff-core.  They will be prefixed
1279          * with something like '=' or '*' (I haven't decided
1280          * which but should not make any difference).
1281          * Feeding the same new and old to diff_change() 
1282          * also has the same effect.
1283          * Before the final output happens, they are pruned after
1284          * merged into rename/copy pairs as appropriate.
1285          */
1286         if (options->reverse_diff)
1287                 addremove = (addremove == '+' ? '-' :
1288                              addremove == '-' ? '+' : addremove);
1289
1290         if (!path) path = "";
1291         sprintf(concatpath, "%s%s", base, path);
1292         one = alloc_filespec(concatpath);
1293         two = alloc_filespec(concatpath);
1294
1295         if (addremove != '+')
1296                 fill_filespec(one, sha1, mode);
1297         if (addremove != '-')
1298                 fill_filespec(two, sha1, mode);
1299
1300         diff_queue(&diff_queued_diff, one, two);
1301 }
1302
1303 void diff_change(struct diff_options *options,
1304                  unsigned old_mode, unsigned new_mode,
1305                  const unsigned char *old_sha1,
1306                  const unsigned char *new_sha1,
1307                  const char *base, const char *path) 
1308 {
1309         char concatpath[PATH_MAX];
1310         struct diff_filespec *one, *two;
1311
1312         if (options->reverse_diff) {
1313                 unsigned tmp;
1314                 const unsigned char *tmp_c;
1315                 tmp = old_mode; old_mode = new_mode; new_mode = tmp;
1316                 tmp_c = old_sha1; old_sha1 = new_sha1; new_sha1 = tmp_c;
1317         }
1318         if (!path) path = "";
1319         sprintf(concatpath, "%s%s", base, path);
1320         one = alloc_filespec(concatpath);
1321         two = alloc_filespec(concatpath);
1322         fill_filespec(one, old_sha1, old_mode);
1323         fill_filespec(two, new_sha1, new_mode);
1324
1325         diff_queue(&diff_queued_diff, one, two);
1326 }
1327
1328 void diff_unmerge(struct diff_options *options,
1329                   const char *path)
1330 {
1331         struct diff_filespec *one, *two;
1332         one = alloc_filespec(path);
1333         two = alloc_filespec(path);
1334         diff_queue(&diff_queued_diff, one, two);
1335 }