Merge branch 'tg/push-all-in-mirror-forbidden'
[git] / builtin / difftool.c
1 /*
2  * "git difftool" builtin command
3  *
4  * This is a wrapper around the GIT_EXTERNAL_DIFF-compatible
5  * git-difftool--helper script.
6  *
7  * This script exports GIT_EXTERNAL_DIFF and GIT_PAGER for use by git.
8  * The GIT_DIFF* variables are exported for use by git-difftool--helper.
9  *
10  * Any arguments that are unknown to this script are forwarded to 'git diff'.
11  *
12  * Copyright (C) 2016 Johannes Schindelin
13  */
14 #define USE_THE_INDEX_COMPATIBILITY_MACROS
15 #include "cache.h"
16 #include "config.h"
17 #include "builtin.h"
18 #include "run-command.h"
19 #include "exec-cmd.h"
20 #include "parse-options.h"
21 #include "argv-array.h"
22 #include "strbuf.h"
23 #include "lockfile.h"
24 #include "object-store.h"
25 #include "dir.h"
26
27 static int trust_exit_code;
28
29 static const char *const builtin_difftool_usage[] = {
30         N_("git difftool [<options>] [<commit> [<commit>]] [--] [<path>...]"),
31         NULL
32 };
33
34 static int difftool_config(const char *var, const char *value, void *cb)
35 {
36         if (!strcmp(var, "difftool.trustexitcode")) {
37                 trust_exit_code = git_config_bool(var, value);
38                 return 0;
39         }
40
41         return git_default_config(var, value, cb);
42 }
43
44 static int print_tool_help(void)
45 {
46         const char *argv[] = { "mergetool", "--tool-help=diff", NULL };
47         return run_command_v_opt(argv, RUN_GIT_CMD);
48 }
49
50 static int parse_index_info(char *p, int *mode1, int *mode2,
51                             struct object_id *oid1, struct object_id *oid2,
52                             char *status)
53 {
54         if (*p != ':')
55                 return error("expected ':', got '%c'", *p);
56         *mode1 = (int)strtol(p + 1, &p, 8);
57         if (*p != ' ')
58                 return error("expected ' ', got '%c'", *p);
59         *mode2 = (int)strtol(p + 1, &p, 8);
60         if (*p != ' ')
61                 return error("expected ' ', got '%c'", *p);
62         if (parse_oid_hex(++p, oid1, (const char **)&p))
63                 return error("expected object ID, got '%s'", p);
64         if (*p != ' ')
65                 return error("expected ' ', got '%c'", *p);
66         if (parse_oid_hex(++p, oid2, (const char **)&p))
67                 return error("expected object ID, got '%s'", p);
68         if (*p != ' ')
69                 return error("expected ' ', got '%c'", *p);
70         *status = *++p;
71         if (!*status)
72                 return error("missing status");
73         if (p[1] && !isdigit(p[1]))
74                 return error("unexpected trailer: '%s'", p + 1);
75         return 0;
76 }
77
78 /*
79  * Remove any trailing slash from $workdir
80  * before starting to avoid double slashes in symlink targets.
81  */
82 static void add_path(struct strbuf *buf, size_t base_len, const char *path)
83 {
84         strbuf_setlen(buf, base_len);
85         if (buf->len && buf->buf[buf->len - 1] != '/')
86                 strbuf_addch(buf, '/');
87         strbuf_addstr(buf, path);
88 }
89
90 /*
91  * Determine whether we can simply reuse the file in the worktree.
92  */
93 static int use_wt_file(const char *workdir, const char *name,
94                        struct object_id *oid)
95 {
96         struct strbuf buf = STRBUF_INIT;
97         struct stat st;
98         int use = 0;
99
100         strbuf_addstr(&buf, workdir);
101         add_path(&buf, buf.len, name);
102
103         if (!lstat(buf.buf, &st) && !S_ISLNK(st.st_mode)) {
104                 struct object_id wt_oid;
105                 int fd = open(buf.buf, O_RDONLY);
106
107                 if (fd >= 0 &&
108                     !index_fd(&the_index, &wt_oid, fd, &st, OBJ_BLOB, name, 0)) {
109                         if (is_null_oid(oid)) {
110                                 oidcpy(oid, &wt_oid);
111                                 use = 1;
112                         } else if (oideq(oid, &wt_oid))
113                                 use = 1;
114                 }
115         }
116
117         strbuf_release(&buf);
118
119         return use;
120 }
121
122 struct working_tree_entry {
123         struct hashmap_entry entry;
124         char path[FLEX_ARRAY];
125 };
126
127 static int working_tree_entry_cmp(const void *unused_cmp_data,
128                                   const void *entry,
129                                   const void *entry_or_key,
130                                   const void *unused_keydata)
131 {
132         const struct working_tree_entry *a = entry;
133         const struct working_tree_entry *b = entry_or_key;
134         return strcmp(a->path, b->path);
135 }
136
137 /*
138  * The `left` and `right` entries hold paths for the symlinks hashmap,
139  * and a SHA-1 surrounded by brief text for submodules.
140  */
141 struct pair_entry {
142         struct hashmap_entry entry;
143         char left[PATH_MAX], right[PATH_MAX];
144         const char path[FLEX_ARRAY];
145 };
146
147 static int pair_cmp(const void *unused_cmp_data,
148                     const void *entry,
149                     const void *entry_or_key,
150                     const void *unused_keydata)
151 {
152         const struct pair_entry *a = entry;
153         const struct pair_entry *b = entry_or_key;
154
155         return strcmp(a->path, b->path);
156 }
157
158 static void add_left_or_right(struct hashmap *map, const char *path,
159                               const char *content, int is_right)
160 {
161         struct pair_entry *e, *existing;
162
163         FLEX_ALLOC_STR(e, path, path);
164         hashmap_entry_init(e, strhash(path));
165         existing = hashmap_get(map, e, NULL);
166         if (existing) {
167                 free(e);
168                 e = existing;
169         } else {
170                 e->left[0] = e->right[0] = '\0';
171                 hashmap_add(map, e);
172         }
173         strlcpy(is_right ? e->right : e->left, content, PATH_MAX);
174 }
175
176 struct path_entry {
177         struct hashmap_entry entry;
178         char path[FLEX_ARRAY];
179 };
180
181 static int path_entry_cmp(const void *unused_cmp_data,
182                           const void *entry,
183                           const void *entry_or_key,
184                           const void *key)
185 {
186         const struct path_entry *a = entry;
187         const struct path_entry *b = entry_or_key;
188
189         return strcmp(a->path, key ? key : b->path);
190 }
191
192 static void changed_files(struct hashmap *result, const char *index_path,
193                           const char *workdir)
194 {
195         struct child_process update_index = CHILD_PROCESS_INIT;
196         struct child_process diff_files = CHILD_PROCESS_INIT;
197         struct strbuf index_env = STRBUF_INIT, buf = STRBUF_INIT;
198         const char *git_dir = absolute_path(get_git_dir()), *env[] = {
199                 NULL, NULL
200         };
201         FILE *fp;
202
203         strbuf_addf(&index_env, "GIT_INDEX_FILE=%s", index_path);
204         env[0] = index_env.buf;
205
206         argv_array_pushl(&update_index.args,
207                          "--git-dir", git_dir, "--work-tree", workdir,
208                          "update-index", "--really-refresh", "-q",
209                          "--unmerged", NULL);
210         update_index.no_stdin = 1;
211         update_index.no_stdout = 1;
212         update_index.no_stderr = 1;
213         update_index.git_cmd = 1;
214         update_index.use_shell = 0;
215         update_index.clean_on_exit = 1;
216         update_index.dir = workdir;
217         update_index.env = env;
218         /* Ignore any errors of update-index */
219         run_command(&update_index);
220
221         argv_array_pushl(&diff_files.args,
222                          "--git-dir", git_dir, "--work-tree", workdir,
223                          "diff-files", "--name-only", "-z", NULL);
224         diff_files.no_stdin = 1;
225         diff_files.git_cmd = 1;
226         diff_files.use_shell = 0;
227         diff_files.clean_on_exit = 1;
228         diff_files.out = -1;
229         diff_files.dir = workdir;
230         diff_files.env = env;
231         if (start_command(&diff_files))
232                 die("could not obtain raw diff");
233         fp = xfdopen(diff_files.out, "r");
234         while (!strbuf_getline_nul(&buf, fp)) {
235                 struct path_entry *entry;
236                 FLEX_ALLOC_STR(entry, path, buf.buf);
237                 hashmap_entry_init(entry, strhash(buf.buf));
238                 hashmap_add(result, entry);
239         }
240         fclose(fp);
241         if (finish_command(&diff_files))
242                 die("diff-files did not exit properly");
243         strbuf_release(&index_env);
244         strbuf_release(&buf);
245 }
246
247 static NORETURN void exit_cleanup(const char *tmpdir, int exit_code)
248 {
249         struct strbuf buf = STRBUF_INIT;
250         strbuf_addstr(&buf, tmpdir);
251         remove_dir_recursively(&buf, 0);
252         if (exit_code)
253                 warning(_("failed: %d"), exit_code);
254         exit(exit_code);
255 }
256
257 static int ensure_leading_directories(char *path)
258 {
259         switch (safe_create_leading_directories(path)) {
260                 case SCLD_OK:
261                 case SCLD_EXISTS:
262                         return 0;
263                 default:
264                         return error(_("could not create leading directories "
265                                        "of '%s'"), path);
266         }
267 }
268
269 /*
270  * Unconditional writing of a plain regular file is what
271  * "git difftool --dir-diff" wants to do for symlinks.  We are preparing two
272  * temporary directories to be fed to a Git-unaware tool that knows how to
273  * show a diff of two directories (e.g. "diff -r A B").
274  *
275  * Because the tool is Git-unaware, if a symbolic link appears in either of
276  * these temporary directories, it will try to dereference and show the
277  * difference of the target of the symbolic link, which is not what we want,
278  * as the goal of the dir-diff mode is to produce an output that is logically
279  * equivalent to what "git diff" produces.
280  *
281  * Most importantly, we want to get textual comparison of the result of the
282  * readlink(2).  get_symlink() provides that---it returns the contents of
283  * the symlink that gets written to a regular file to force the external tool
284  * to compare the readlink(2) result as text, even on a filesystem that is
285  * capable of doing a symbolic link.
286  */
287 static char *get_symlink(const struct object_id *oid, const char *path)
288 {
289         char *data;
290         if (is_null_oid(oid)) {
291                 /* The symlink is unknown to Git so read from the filesystem */
292                 struct strbuf link = STRBUF_INIT;
293                 if (has_symlinks) {
294                         if (strbuf_readlink(&link, path, strlen(path)))
295                                 die(_("could not read symlink %s"), path);
296                 } else if (strbuf_read_file(&link, path, 128))
297                         die(_("could not read symlink file %s"), path);
298
299                 data = strbuf_detach(&link, NULL);
300         } else {
301                 enum object_type type;
302                 unsigned long size;
303                 data = read_object_file(oid, &type, &size);
304                 if (!data)
305                         die(_("could not read object %s for symlink %s"),
306                                 oid_to_hex(oid), path);
307         }
308
309         return data;
310 }
311
312 static int checkout_path(unsigned mode, struct object_id *oid,
313                          const char *path, const struct checkout *state)
314 {
315         struct cache_entry *ce;
316         int ret;
317
318         ce = make_transient_cache_entry(mode, oid, path, 0);
319         ret = checkout_entry(ce, state, NULL, NULL);
320
321         discard_cache_entry(ce);
322         return ret;
323 }
324
325 static int run_dir_diff(const char *extcmd, int symlinks, const char *prefix,
326                         int argc, const char **argv)
327 {
328         char tmpdir[PATH_MAX];
329         struct strbuf info = STRBUF_INIT, lpath = STRBUF_INIT;
330         struct strbuf rpath = STRBUF_INIT, buf = STRBUF_INIT;
331         struct strbuf ldir = STRBUF_INIT, rdir = STRBUF_INIT;
332         struct strbuf wtdir = STRBUF_INIT;
333         char *lbase_dir, *rbase_dir;
334         size_t ldir_len, rdir_len, wtdir_len;
335         const char *workdir, *tmp;
336         int ret = 0, i;
337         FILE *fp;
338         struct hashmap working_tree_dups, submodules, symlinks2;
339         struct hashmap_iter iter;
340         struct pair_entry *entry;
341         struct index_state wtindex;
342         struct checkout lstate, rstate;
343         int rc, flags = RUN_GIT_CMD, err = 0;
344         struct child_process child = CHILD_PROCESS_INIT;
345         const char *helper_argv[] = { "difftool--helper", NULL, NULL, NULL };
346         struct hashmap wt_modified, tmp_modified;
347         int indices_loaded = 0;
348
349         workdir = get_git_work_tree();
350
351         /* Setup temp directories */
352         tmp = getenv("TMPDIR");
353         xsnprintf(tmpdir, sizeof(tmpdir), "%s/git-difftool.XXXXXX", tmp ? tmp : "/tmp");
354         if (!mkdtemp(tmpdir))
355                 return error("could not create '%s'", tmpdir);
356         strbuf_addf(&ldir, "%s/left/", tmpdir);
357         strbuf_addf(&rdir, "%s/right/", tmpdir);
358         strbuf_addstr(&wtdir, workdir);
359         if (!wtdir.len || !is_dir_sep(wtdir.buf[wtdir.len - 1]))
360                 strbuf_addch(&wtdir, '/');
361         mkdir(ldir.buf, 0700);
362         mkdir(rdir.buf, 0700);
363
364         memset(&wtindex, 0, sizeof(wtindex));
365
366         memset(&lstate, 0, sizeof(lstate));
367         lstate.base_dir = lbase_dir = xstrdup(ldir.buf);
368         lstate.base_dir_len = ldir.len;
369         lstate.force = 1;
370         memset(&rstate, 0, sizeof(rstate));
371         rstate.base_dir = rbase_dir = xstrdup(rdir.buf);
372         rstate.base_dir_len = rdir.len;
373         rstate.force = 1;
374
375         ldir_len = ldir.len;
376         rdir_len = rdir.len;
377         wtdir_len = wtdir.len;
378
379         hashmap_init(&working_tree_dups, working_tree_entry_cmp, NULL, 0);
380         hashmap_init(&submodules, pair_cmp, NULL, 0);
381         hashmap_init(&symlinks2, pair_cmp, NULL, 0);
382
383         child.no_stdin = 1;
384         child.git_cmd = 1;
385         child.use_shell = 0;
386         child.clean_on_exit = 1;
387         child.dir = prefix;
388         child.out = -1;
389         argv_array_pushl(&child.args, "diff", "--raw", "--no-abbrev", "-z",
390                          NULL);
391         for (i = 0; i < argc; i++)
392                 argv_array_push(&child.args, argv[i]);
393         if (start_command(&child))
394                 die("could not obtain raw diff");
395         fp = xfdopen(child.out, "r");
396
397         /* Build index info for left and right sides of the diff */
398         i = 0;
399         while (!strbuf_getline_nul(&info, fp)) {
400                 int lmode, rmode;
401                 struct object_id loid, roid;
402                 char status;
403                 const char *src_path, *dst_path;
404
405                 if (starts_with(info.buf, "::"))
406                         die(N_("combined diff formats('-c' and '--cc') are "
407                                "not supported in\n"
408                                "directory diff mode('-d' and '--dir-diff')."));
409
410                 if (parse_index_info(info.buf, &lmode, &rmode, &loid, &roid,
411                                      &status))
412                         break;
413                 if (strbuf_getline_nul(&lpath, fp))
414                         break;
415                 src_path = lpath.buf;
416
417                 i++;
418                 if (status != 'C' && status != 'R') {
419                         dst_path = src_path;
420                 } else {
421                         if (strbuf_getline_nul(&rpath, fp))
422                                 break;
423                         dst_path = rpath.buf;
424                 }
425
426                 if (S_ISGITLINK(lmode) || S_ISGITLINK(rmode)) {
427                         strbuf_reset(&buf);
428                         strbuf_addf(&buf, "Subproject commit %s",
429                                     oid_to_hex(&loid));
430                         add_left_or_right(&submodules, src_path, buf.buf, 0);
431                         strbuf_reset(&buf);
432                         strbuf_addf(&buf, "Subproject commit %s",
433                                     oid_to_hex(&roid));
434                         if (oideq(&loid, &roid))
435                                 strbuf_addstr(&buf, "-dirty");
436                         add_left_or_right(&submodules, dst_path, buf.buf, 1);
437                         continue;
438                 }
439
440                 if (S_ISLNK(lmode)) {
441                         char *content = get_symlink(&loid, src_path);
442                         add_left_or_right(&symlinks2, src_path, content, 0);
443                         free(content);
444                 }
445
446                 if (S_ISLNK(rmode)) {
447                         char *content = get_symlink(&roid, dst_path);
448                         add_left_or_right(&symlinks2, dst_path, content, 1);
449                         free(content);
450                 }
451
452                 if (lmode && status != 'C') {
453                         if (checkout_path(lmode, &loid, src_path, &lstate)) {
454                                 ret = error("could not write '%s'", src_path);
455                                 goto finish;
456                         }
457                 }
458
459                 if (rmode && !S_ISLNK(rmode)) {
460                         struct working_tree_entry *entry;
461
462                         /* Avoid duplicate working_tree entries */
463                         FLEX_ALLOC_STR(entry, path, dst_path);
464                         hashmap_entry_init(entry, strhash(dst_path));
465                         if (hashmap_get(&working_tree_dups, entry, NULL)) {
466                                 free(entry);
467                                 continue;
468                         }
469                         hashmap_add(&working_tree_dups, entry);
470
471                         if (!use_wt_file(workdir, dst_path, &roid)) {
472                                 if (checkout_path(rmode, &roid, dst_path,
473                                                   &rstate)) {
474                                         ret = error("could not write '%s'",
475                                                     dst_path);
476                                         goto finish;
477                                 }
478                         } else if (!is_null_oid(&roid)) {
479                                 /*
480                                  * Changes in the working tree need special
481                                  * treatment since they are not part of the
482                                  * index.
483                                  */
484                                 struct cache_entry *ce2 =
485                                         make_cache_entry(&wtindex, rmode, &roid,
486                                                          dst_path, 0, 0);
487
488                                 add_index_entry(&wtindex, ce2,
489                                                 ADD_CACHE_JUST_APPEND);
490
491                                 add_path(&rdir, rdir_len, dst_path);
492                                 if (ensure_leading_directories(rdir.buf)) {
493                                         ret = error("could not create "
494                                                     "directory for '%s'",
495                                                     dst_path);
496                                         goto finish;
497                                 }
498                                 add_path(&wtdir, wtdir_len, dst_path);
499                                 if (symlinks) {
500                                         if (symlink(wtdir.buf, rdir.buf)) {
501                                                 ret = error_errno("could not symlink '%s' to '%s'", wtdir.buf, rdir.buf);
502                                                 goto finish;
503                                         }
504                                 } else {
505                                         struct stat st;
506                                         if (stat(wtdir.buf, &st))
507                                                 st.st_mode = 0644;
508                                         if (copy_file(rdir.buf, wtdir.buf,
509                                                       st.st_mode)) {
510                                                 ret = error("could not copy '%s' to '%s'", wtdir.buf, rdir.buf);
511                                                 goto finish;
512                                         }
513                                 }
514                         }
515                 }
516         }
517
518         fclose(fp);
519         fp = NULL;
520         if (finish_command(&child)) {
521                 ret = error("error occurred running diff --raw");
522                 goto finish;
523         }
524
525         if (!i)
526                 goto finish;
527
528         /*
529          * Changes to submodules require special treatment.This loop writes a
530          * temporary file to both the left and right directories to show the
531          * change in the recorded SHA1 for the submodule.
532          */
533         hashmap_iter_init(&submodules, &iter);
534         while ((entry = hashmap_iter_next(&iter))) {
535                 if (*entry->left) {
536                         add_path(&ldir, ldir_len, entry->path);
537                         ensure_leading_directories(ldir.buf);
538                         write_file(ldir.buf, "%s", entry->left);
539                 }
540                 if (*entry->right) {
541                         add_path(&rdir, rdir_len, entry->path);
542                         ensure_leading_directories(rdir.buf);
543                         write_file(rdir.buf, "%s", entry->right);
544                 }
545         }
546
547         /*
548          * Symbolic links require special treatment.The standard "git diff"
549          * shows only the link itself, not the contents of the link target.
550          * This loop replicates that behavior.
551          */
552         hashmap_iter_init(&symlinks2, &iter);
553         while ((entry = hashmap_iter_next(&iter))) {
554                 if (*entry->left) {
555                         add_path(&ldir, ldir_len, entry->path);
556                         ensure_leading_directories(ldir.buf);
557                         write_file(ldir.buf, "%s", entry->left);
558                 }
559                 if (*entry->right) {
560                         add_path(&rdir, rdir_len, entry->path);
561                         ensure_leading_directories(rdir.buf);
562                         write_file(rdir.buf, "%s", entry->right);
563                 }
564         }
565
566         strbuf_release(&buf);
567
568         strbuf_setlen(&ldir, ldir_len);
569         helper_argv[1] = ldir.buf;
570         strbuf_setlen(&rdir, rdir_len);
571         helper_argv[2] = rdir.buf;
572
573         if (extcmd) {
574                 helper_argv[0] = extcmd;
575                 flags = 0;
576         } else
577                 setenv("GIT_DIFFTOOL_DIRDIFF", "true", 1);
578         rc = run_command_v_opt(helper_argv, flags);
579
580         /*
581          * If the diff includes working copy files and those
582          * files were modified during the diff, then the changes
583          * should be copied back to the working tree.
584          * Do not copy back files when symlinks are used and the
585          * external tool did not replace the original link with a file.
586          *
587          * These hashes are loaded lazily since they aren't needed
588          * in the common case of --symlinks and the difftool updating
589          * files through the symlink.
590          */
591         hashmap_init(&wt_modified, path_entry_cmp, NULL, wtindex.cache_nr);
592         hashmap_init(&tmp_modified, path_entry_cmp, NULL, wtindex.cache_nr);
593
594         for (i = 0; i < wtindex.cache_nr; i++) {
595                 struct hashmap_entry dummy;
596                 const char *name = wtindex.cache[i]->name;
597                 struct stat st;
598
599                 add_path(&rdir, rdir_len, name);
600                 if (lstat(rdir.buf, &st))
601                         continue;
602
603                 if ((symlinks && S_ISLNK(st.st_mode)) || !S_ISREG(st.st_mode))
604                         continue;
605
606                 if (!indices_loaded) {
607                         struct lock_file lock = LOCK_INIT;
608                         strbuf_reset(&buf);
609                         strbuf_addf(&buf, "%s/wtindex", tmpdir);
610                         if (hold_lock_file_for_update(&lock, buf.buf, 0) < 0 ||
611                             write_locked_index(&wtindex, &lock, COMMIT_LOCK)) {
612                                 ret = error("could not write %s", buf.buf);
613                                 goto finish;
614                         }
615                         changed_files(&wt_modified, buf.buf, workdir);
616                         strbuf_setlen(&rdir, rdir_len);
617                         changed_files(&tmp_modified, buf.buf, rdir.buf);
618                         add_path(&rdir, rdir_len, name);
619                         indices_loaded = 1;
620                 }
621
622                 hashmap_entry_init(&dummy, strhash(name));
623                 if (hashmap_get(&tmp_modified, &dummy, name)) {
624                         add_path(&wtdir, wtdir_len, name);
625                         if (hashmap_get(&wt_modified, &dummy, name)) {
626                                 warning(_("both files modified: '%s' and '%s'."),
627                                         wtdir.buf, rdir.buf);
628                                 warning(_("working tree file has been left."));
629                                 warning("%s", "");
630                                 err = 1;
631                         } else if (unlink(wtdir.buf) ||
632                                    copy_file(wtdir.buf, rdir.buf, st.st_mode))
633                                 warning_errno(_("could not copy '%s' to '%s'"),
634                                               rdir.buf, wtdir.buf);
635                 }
636         }
637
638         if (err) {
639                 warning(_("temporary files exist in '%s'."), tmpdir);
640                 warning(_("you may want to cleanup or recover these."));
641                 exit(1);
642         } else
643                 exit_cleanup(tmpdir, rc);
644
645 finish:
646         if (fp)
647                 fclose(fp);
648
649         free(lbase_dir);
650         free(rbase_dir);
651         strbuf_release(&ldir);
652         strbuf_release(&rdir);
653         strbuf_release(&wtdir);
654         strbuf_release(&buf);
655
656         return ret;
657 }
658
659 static int run_file_diff(int prompt, const char *prefix,
660                          int argc, const char **argv)
661 {
662         struct argv_array args = ARGV_ARRAY_INIT;
663         const char *env[] = {
664                 "GIT_PAGER=", "GIT_EXTERNAL_DIFF=git-difftool--helper", NULL,
665                 NULL
666         };
667         int ret = 0, i;
668
669         if (prompt > 0)
670                 env[2] = "GIT_DIFFTOOL_PROMPT=true";
671         else if (!prompt)
672                 env[2] = "GIT_DIFFTOOL_NO_PROMPT=true";
673
674
675         argv_array_push(&args, "diff");
676         for (i = 0; i < argc; i++)
677                 argv_array_push(&args, argv[i]);
678         ret = run_command_v_opt_cd_env(args.argv, RUN_GIT_CMD, prefix, env);
679         exit(ret);
680 }
681
682 int cmd_difftool(int argc, const char **argv, const char *prefix)
683 {
684         int use_gui_tool = 0, dir_diff = 0, prompt = -1, symlinks = 0,
685             tool_help = 0, no_index = 0;
686         static char *difftool_cmd = NULL, *extcmd = NULL;
687         struct option builtin_difftool_options[] = {
688                 OPT_BOOL('g', "gui", &use_gui_tool,
689                          N_("use `diff.guitool` instead of `diff.tool`")),
690                 OPT_BOOL('d', "dir-diff", &dir_diff,
691                          N_("perform a full-directory diff")),
692                 OPT_SET_INT_F('y', "no-prompt", &prompt,
693                         N_("do not prompt before launching a diff tool"),
694                         0, PARSE_OPT_NONEG),
695                 OPT_SET_INT_F(0, "prompt", &prompt, NULL,
696                         1, PARSE_OPT_NONEG | PARSE_OPT_HIDDEN),
697                 OPT_BOOL(0, "symlinks", &symlinks,
698                          N_("use symlinks in dir-diff mode")),
699                 OPT_STRING('t', "tool", &difftool_cmd, N_("tool"),
700                            N_("use the specified diff tool")),
701                 OPT_BOOL(0, "tool-help", &tool_help,
702                          N_("print a list of diff tools that may be used with "
703                             "`--tool`")),
704                 OPT_BOOL(0, "trust-exit-code", &trust_exit_code,
705                          N_("make 'git-difftool' exit when an invoked diff "
706                             "tool returns a non - zero exit code")),
707                 OPT_STRING('x', "extcmd", &extcmd, N_("command"),
708                            N_("specify a custom command for viewing diffs")),
709                 OPT_ARGUMENT("no-index", &no_index, N_("passed to `diff`")),
710                 OPT_END()
711         };
712
713         git_config(difftool_config, NULL);
714         symlinks = has_symlinks;
715
716         argc = parse_options(argc, argv, prefix, builtin_difftool_options,
717                              builtin_difftool_usage, PARSE_OPT_KEEP_UNKNOWN |
718                              PARSE_OPT_KEEP_DASHDASH);
719
720         if (tool_help)
721                 return print_tool_help();
722
723         if (!no_index && !startup_info->have_repository)
724                 die(_("difftool requires worktree or --no-index"));
725
726         if (!no_index){
727                 setup_work_tree();
728                 setenv(GIT_DIR_ENVIRONMENT, absolute_path(get_git_dir()), 1);
729                 setenv(GIT_WORK_TREE_ENVIRONMENT, absolute_path(get_git_work_tree()), 1);
730         } else if (dir_diff)
731                 die(_("--dir-diff is incompatible with --no-index"));
732
733         if (use_gui_tool + !!difftool_cmd + !!extcmd > 1)
734                 die(_("--gui, --tool and --extcmd are mutually exclusive"));
735
736         if (use_gui_tool)
737                 setenv("GIT_MERGETOOL_GUI", "true", 1);
738         else if (difftool_cmd) {
739                 if (*difftool_cmd)
740                         setenv("GIT_DIFF_TOOL", difftool_cmd, 1);
741                 else
742                         die(_("no <tool> given for --tool=<tool>"));
743         }
744
745         if (extcmd) {
746                 if (*extcmd)
747                         setenv("GIT_DIFFTOOL_EXTCMD", extcmd, 1);
748                 else
749                         die(_("no <cmd> given for --extcmd=<cmd>"));
750         }
751
752         setenv("GIT_DIFFTOOL_TRUST_EXIT_CODE",
753                trust_exit_code ? "true" : "false", 1);
754
755         /*
756          * In directory diff mode, 'git-difftool--helper' is called once
757          * to compare the a / b directories. In file diff mode, 'git diff'
758          * will invoke a separate instance of 'git-difftool--helper' for
759          * each file that changed.
760          */
761         if (dir_diff)
762                 return run_dir_diff(extcmd, symlinks, prefix, argc, argv);
763         return run_file_diff(prompt, prefix, argc, argv);
764 }