Merge branch 'nd/reject-empty-shallow-request'
[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 #include "cache.h"
15 #include "config.h"
16 #include "builtin.h"
17 #include "run-command.h"
18 #include "exec-cmd.h"
19 #include "parse-options.h"
20 #include "argv-array.h"
21 #include "strbuf.h"
22 #include "lockfile.h"
23 #include "dir.h"
24
25 static char *diff_gui_tool;
26 static int trust_exit_code;
27
28 static const char *const builtin_difftool_usage[] = {
29         N_("git difftool [<options>] [<commit> [<commit>]] [--] [<path>...]"),
30         NULL
31 };
32
33 static int difftool_config(const char *var, const char *value, void *cb)
34 {
35         if (!strcmp(var, "diff.guitool")) {
36                 diff_gui_tool = xstrdup(value);
37                 return 0;
38         }
39
40         if (!strcmp(var, "difftool.trustexitcode")) {
41                 trust_exit_code = git_config_bool(var, value);
42                 return 0;
43         }
44
45         return git_default_config(var, value, cb);
46 }
47
48 static int print_tool_help(void)
49 {
50         const char *argv[] = { "mergetool", "--tool-help=diff", NULL };
51         return run_command_v_opt(argv, RUN_GIT_CMD);
52 }
53
54 static int parse_index_info(char *p, int *mode1, int *mode2,
55                             struct object_id *oid1, struct object_id *oid2,
56                             char *status)
57 {
58         if (*p != ':')
59                 return error("expected ':', got '%c'", *p);
60         *mode1 = (int)strtol(p + 1, &p, 8);
61         if (*p != ' ')
62                 return error("expected ' ', got '%c'", *p);
63         *mode2 = (int)strtol(p + 1, &p, 8);
64         if (*p != ' ')
65                 return error("expected ' ', got '%c'", *p);
66         if (get_oid_hex(++p, oid1))
67                 return error("expected object ID, got '%s'", p + 1);
68         p += GIT_SHA1_HEXSZ;
69         if (*p != ' ')
70                 return error("expected ' ', got '%c'", *p);
71         if (get_oid_hex(++p, oid2))
72                 return error("expected object ID, got '%s'", p + 1);
73         p += GIT_SHA1_HEXSZ;
74         if (*p != ' ')
75                 return error("expected ' ', got '%c'", *p);
76         *status = *++p;
77         if (!*status)
78                 return error("missing status");
79         if (p[1] && !isdigit(p[1]))
80                 return error("unexpected trailer: '%s'", p + 1);
81         return 0;
82 }
83
84 /*
85  * Remove any trailing slash from $workdir
86  * before starting to avoid double slashes in symlink targets.
87  */
88 static void add_path(struct strbuf *buf, size_t base_len, const char *path)
89 {
90         strbuf_setlen(buf, base_len);
91         if (buf->len && buf->buf[buf->len - 1] != '/')
92                 strbuf_addch(buf, '/');
93         strbuf_addstr(buf, path);
94 }
95
96 /*
97  * Determine whether we can simply reuse the file in the worktree.
98  */
99 static int use_wt_file(const char *workdir, const char *name,
100                        struct object_id *oid)
101 {
102         struct strbuf buf = STRBUF_INIT;
103         struct stat st;
104         int use = 0;
105
106         strbuf_addstr(&buf, workdir);
107         add_path(&buf, buf.len, name);
108
109         if (!lstat(buf.buf, &st) && !S_ISLNK(st.st_mode)) {
110                 struct object_id wt_oid;
111                 int fd = open(buf.buf, O_RDONLY);
112
113                 if (fd >= 0 &&
114                     !index_fd(&wt_oid, fd, &st, OBJ_BLOB, name, 0)) {
115                         if (is_null_oid(oid)) {
116                                 oidcpy(oid, &wt_oid);
117                                 use = 1;
118                         } else if (!oidcmp(oid, &wt_oid))
119                                 use = 1;
120                 }
121         }
122
123         strbuf_release(&buf);
124
125         return use;
126 }
127
128 struct working_tree_entry {
129         struct hashmap_entry entry;
130         char path[FLEX_ARRAY];
131 };
132
133 static int working_tree_entry_cmp(const void *unused_cmp_data,
134                                   const void *entry,
135                                   const void *entry_or_key,
136                                   const void *unused_keydata)
137 {
138         const struct working_tree_entry *a = entry;
139         const struct working_tree_entry *b = entry_or_key;
140         return strcmp(a->path, b->path);
141 }
142
143 /*
144  * The `left` and `right` entries hold paths for the symlinks hashmap,
145  * and a SHA-1 surrounded by brief text for submodules.
146  */
147 struct pair_entry {
148         struct hashmap_entry entry;
149         char left[PATH_MAX], right[PATH_MAX];
150         const char path[FLEX_ARRAY];
151 };
152
153 static int pair_cmp(const void *unused_cmp_data,
154                     const void *entry,
155                     const void *entry_or_key,
156                     const void *unused_keydata)
157 {
158         const struct pair_entry *a = entry;
159         const struct pair_entry *b = entry_or_key;
160
161         return strcmp(a->path, b->path);
162 }
163
164 static void add_left_or_right(struct hashmap *map, const char *path,
165                               const char *content, int is_right)
166 {
167         struct pair_entry *e, *existing;
168
169         FLEX_ALLOC_STR(e, path, path);
170         hashmap_entry_init(e, strhash(path));
171         existing = hashmap_get(map, e, NULL);
172         if (existing) {
173                 free(e);
174                 e = existing;
175         } else {
176                 e->left[0] = e->right[0] = '\0';
177                 hashmap_add(map, e);
178         }
179         strlcpy(is_right ? e->right : e->left, content, PATH_MAX);
180 }
181
182 struct path_entry {
183         struct hashmap_entry entry;
184         char path[FLEX_ARRAY];
185 };
186
187 static int path_entry_cmp(const void *unused_cmp_data,
188                           const void *entry,
189                           const void *entry_or_key,
190                           const void *key)
191 {
192         const struct path_entry *a = entry;
193         const struct path_entry *b = entry_or_key;
194
195         return strcmp(a->path, key ? key : b->path);
196 }
197
198 static void changed_files(struct hashmap *result, const char *index_path,
199                           const char *workdir)
200 {
201         struct child_process update_index = CHILD_PROCESS_INIT;
202         struct child_process diff_files = CHILD_PROCESS_INIT;
203         struct strbuf index_env = STRBUF_INIT, buf = STRBUF_INIT;
204         const char *git_dir = absolute_path(get_git_dir()), *env[] = {
205                 NULL, NULL
206         };
207         FILE *fp;
208
209         strbuf_addf(&index_env, "GIT_INDEX_FILE=%s", index_path);
210         env[0] = index_env.buf;
211
212         argv_array_pushl(&update_index.args,
213                          "--git-dir", git_dir, "--work-tree", workdir,
214                          "update-index", "--really-refresh", "-q",
215                          "--unmerged", NULL);
216         update_index.no_stdin = 1;
217         update_index.no_stdout = 1;
218         update_index.no_stderr = 1;
219         update_index.git_cmd = 1;
220         update_index.use_shell = 0;
221         update_index.clean_on_exit = 1;
222         update_index.dir = workdir;
223         update_index.env = env;
224         /* Ignore any errors of update-index */
225         run_command(&update_index);
226
227         argv_array_pushl(&diff_files.args,
228                          "--git-dir", git_dir, "--work-tree", workdir,
229                          "diff-files", "--name-only", "-z", NULL);
230         diff_files.no_stdin = 1;
231         diff_files.git_cmd = 1;
232         diff_files.use_shell = 0;
233         diff_files.clean_on_exit = 1;
234         diff_files.out = -1;
235         diff_files.dir = workdir;
236         diff_files.env = env;
237         if (start_command(&diff_files))
238                 die("could not obtain raw diff");
239         fp = xfdopen(diff_files.out, "r");
240         while (!strbuf_getline_nul(&buf, fp)) {
241                 struct path_entry *entry;
242                 FLEX_ALLOC_STR(entry, path, buf.buf);
243                 hashmap_entry_init(entry, strhash(buf.buf));
244                 hashmap_add(result, entry);
245         }
246         fclose(fp);
247         if (finish_command(&diff_files))
248                 die("diff-files did not exit properly");
249         strbuf_release(&index_env);
250         strbuf_release(&buf);
251 }
252
253 static NORETURN void exit_cleanup(const char *tmpdir, int exit_code)
254 {
255         struct strbuf buf = STRBUF_INIT;
256         strbuf_addstr(&buf, tmpdir);
257         remove_dir_recursively(&buf, 0);
258         if (exit_code)
259                 warning(_("failed: %d"), exit_code);
260         exit(exit_code);
261 }
262
263 static int ensure_leading_directories(char *path)
264 {
265         switch (safe_create_leading_directories(path)) {
266                 case SCLD_OK:
267                 case SCLD_EXISTS:
268                         return 0;
269                 default:
270                         return error(_("could not create leading directories "
271                                        "of '%s'"), path);
272         }
273 }
274
275 /*
276  * Unconditional writing of a plain regular file is what
277  * "git difftool --dir-diff" wants to do for symlinks.  We are preparing two
278  * temporary directories to be fed to a Git-unaware tool that knows how to
279  * show a diff of two directories (e.g. "diff -r A B").
280  *
281  * Because the tool is Git-unaware, if a symbolic link appears in either of
282  * these temporary directories, it will try to dereference and show the
283  * difference of the target of the symbolic link, which is not what we want,
284  * as the goal of the dir-diff mode is to produce an output that is logically
285  * equivalent to what "git diff" produces.
286  *
287  * Most importantly, we want to get textual comparison of the result of the
288  * readlink(2).  get_symlink() provides that---it returns the contents of
289  * the symlink that gets written to a regular file to force the external tool
290  * to compare the readlink(2) result as text, even on a filesystem that is
291  * capable of doing a symbolic link.
292  */
293 static char *get_symlink(const struct object_id *oid, const char *path)
294 {
295         char *data;
296         if (is_null_oid(oid)) {
297                 /* The symlink is unknown to Git so read from the filesystem */
298                 struct strbuf link = STRBUF_INIT;
299                 if (has_symlinks) {
300                         if (strbuf_readlink(&link, path, strlen(path)))
301                                 die(_("could not read symlink %s"), path);
302                 } else if (strbuf_read_file(&link, path, 128))
303                         die(_("could not read symlink file %s"), path);
304
305                 data = strbuf_detach(&link, NULL);
306         } else {
307                 enum object_type type;
308                 unsigned long size;
309                 data = read_object_file(oid, &type, &size);
310                 if (!data)
311                         die(_("could not read object %s for symlink %s"),
312                                 oid_to_hex(oid), path);
313         }
314
315         return data;
316 }
317
318 static int checkout_path(unsigned mode, struct object_id *oid,
319                          const char *path, const struct checkout *state)
320 {
321         struct cache_entry *ce;
322         int ret;
323
324         ce = make_cache_entry(mode, oid->hash, path, 0, 0);
325         ret = checkout_entry(ce, state, NULL);
326
327         free(ce);
328         return ret;
329 }
330
331 static int run_dir_diff(const char *extcmd, int symlinks, const char *prefix,
332                         int argc, const char **argv)
333 {
334         char tmpdir[PATH_MAX];
335         struct strbuf info = STRBUF_INIT, lpath = STRBUF_INIT;
336         struct strbuf rpath = STRBUF_INIT, buf = STRBUF_INIT;
337         struct strbuf ldir = STRBUF_INIT, rdir = STRBUF_INIT;
338         struct strbuf wtdir = STRBUF_INIT;
339         char *lbase_dir, *rbase_dir;
340         size_t ldir_len, rdir_len, wtdir_len;
341         const char *workdir, *tmp;
342         int ret = 0, i;
343         FILE *fp;
344         struct hashmap working_tree_dups, submodules, symlinks2;
345         struct hashmap_iter iter;
346         struct pair_entry *entry;
347         struct index_state wtindex;
348         struct checkout lstate, rstate;
349         int rc, flags = RUN_GIT_CMD, err = 0;
350         struct child_process child = CHILD_PROCESS_INIT;
351         const char *helper_argv[] = { "difftool--helper", NULL, NULL, NULL };
352         struct hashmap wt_modified, tmp_modified;
353         int indices_loaded = 0;
354
355         workdir = get_git_work_tree();
356
357         /* Setup temp directories */
358         tmp = getenv("TMPDIR");
359         xsnprintf(tmpdir, sizeof(tmpdir), "%s/git-difftool.XXXXXX", tmp ? tmp : "/tmp");
360         if (!mkdtemp(tmpdir))
361                 return error("could not create '%s'", tmpdir);
362         strbuf_addf(&ldir, "%s/left/", tmpdir);
363         strbuf_addf(&rdir, "%s/right/", tmpdir);
364         strbuf_addstr(&wtdir, workdir);
365         if (!wtdir.len || !is_dir_sep(wtdir.buf[wtdir.len - 1]))
366                 strbuf_addch(&wtdir, '/');
367         mkdir(ldir.buf, 0700);
368         mkdir(rdir.buf, 0700);
369
370         memset(&wtindex, 0, sizeof(wtindex));
371
372         memset(&lstate, 0, sizeof(lstate));
373         lstate.base_dir = lbase_dir = xstrdup(ldir.buf);
374         lstate.base_dir_len = ldir.len;
375         lstate.force = 1;
376         memset(&rstate, 0, sizeof(rstate));
377         rstate.base_dir = rbase_dir = xstrdup(rdir.buf);
378         rstate.base_dir_len = rdir.len;
379         rstate.force = 1;
380
381         ldir_len = ldir.len;
382         rdir_len = rdir.len;
383         wtdir_len = wtdir.len;
384
385         hashmap_init(&working_tree_dups, working_tree_entry_cmp, NULL, 0);
386         hashmap_init(&submodules, pair_cmp, NULL, 0);
387         hashmap_init(&symlinks2, pair_cmp, NULL, 0);
388
389         child.no_stdin = 1;
390         child.git_cmd = 1;
391         child.use_shell = 0;
392         child.clean_on_exit = 1;
393         child.dir = prefix;
394         child.out = -1;
395         argv_array_pushl(&child.args, "diff", "--raw", "--no-abbrev", "-z",
396                          NULL);
397         for (i = 0; i < argc; i++)
398                 argv_array_push(&child.args, argv[i]);
399         if (start_command(&child))
400                 die("could not obtain raw diff");
401         fp = xfdopen(child.out, "r");
402
403         /* Build index info for left and right sides of the diff */
404         i = 0;
405         while (!strbuf_getline_nul(&info, fp)) {
406                 int lmode, rmode;
407                 struct object_id loid, roid;
408                 char status;
409                 const char *src_path, *dst_path;
410
411                 if (starts_with(info.buf, "::"))
412                         die(N_("combined diff formats('-c' and '--cc') are "
413                                "not supported in\n"
414                                "directory diff mode('-d' and '--dir-diff')."));
415
416                 if (parse_index_info(info.buf, &lmode, &rmode, &loid, &roid,
417                                      &status))
418                         break;
419                 if (strbuf_getline_nul(&lpath, fp))
420                         break;
421                 src_path = lpath.buf;
422
423                 i++;
424                 if (status != 'C' && status != 'R') {
425                         dst_path = src_path;
426                 } else {
427                         if (strbuf_getline_nul(&rpath, fp))
428                                 break;
429                         dst_path = rpath.buf;
430                 }
431
432                 if (S_ISGITLINK(lmode) || S_ISGITLINK(rmode)) {
433                         strbuf_reset(&buf);
434                         strbuf_addf(&buf, "Subproject commit %s",
435                                     oid_to_hex(&loid));
436                         add_left_or_right(&submodules, src_path, buf.buf, 0);
437                         strbuf_reset(&buf);
438                         strbuf_addf(&buf, "Subproject commit %s",
439                                     oid_to_hex(&roid));
440                         if (!oidcmp(&loid, &roid))
441                                 strbuf_addstr(&buf, "-dirty");
442                         add_left_or_right(&submodules, dst_path, buf.buf, 1);
443                         continue;
444                 }
445
446                 if (S_ISLNK(lmode)) {
447                         char *content = get_symlink(&loid, src_path);
448                         add_left_or_right(&symlinks2, src_path, content, 0);
449                         free(content);
450                 }
451
452                 if (S_ISLNK(rmode)) {
453                         char *content = get_symlink(&roid, dst_path);
454                         add_left_or_right(&symlinks2, dst_path, content, 1);
455                         free(content);
456                 }
457
458                 if (lmode && status != 'C') {
459                         if (checkout_path(lmode, &loid, src_path, &lstate)) {
460                                 ret = error("could not write '%s'", src_path);
461                                 goto finish;
462                         }
463                 }
464
465                 if (rmode && !S_ISLNK(rmode)) {
466                         struct working_tree_entry *entry;
467
468                         /* Avoid duplicate working_tree entries */
469                         FLEX_ALLOC_STR(entry, path, dst_path);
470                         hashmap_entry_init(entry, strhash(dst_path));
471                         if (hashmap_get(&working_tree_dups, entry, NULL)) {
472                                 free(entry);
473                                 continue;
474                         }
475                         hashmap_add(&working_tree_dups, entry);
476
477                         if (!use_wt_file(workdir, dst_path, &roid)) {
478                                 if (checkout_path(rmode, &roid, dst_path,
479                                                   &rstate)) {
480                                         ret = error("could not write '%s'",
481                                                     dst_path);
482                                         goto finish;
483                                 }
484                         } else if (!is_null_oid(&roid)) {
485                                 /*
486                                  * Changes in the working tree need special
487                                  * treatment since they are not part of the
488                                  * index.
489                                  */
490                                 struct cache_entry *ce2 =
491                                         make_cache_entry(rmode, roid.hash,
492                                                          dst_path, 0, 0);
493
494                                 add_index_entry(&wtindex, ce2,
495                                                 ADD_CACHE_JUST_APPEND);
496
497                                 add_path(&rdir, rdir_len, dst_path);
498                                 if (ensure_leading_directories(rdir.buf)) {
499                                         ret = error("could not create "
500                                                     "directory for '%s'",
501                                                     dst_path);
502                                         goto finish;
503                                 }
504                                 add_path(&wtdir, wtdir_len, dst_path);
505                                 if (symlinks) {
506                                         if (symlink(wtdir.buf, rdir.buf)) {
507                                                 ret = error_errno("could not symlink '%s' to '%s'", wtdir.buf, rdir.buf);
508                                                 goto finish;
509                                         }
510                                 } else {
511                                         struct stat st;
512                                         if (stat(wtdir.buf, &st))
513                                                 st.st_mode = 0644;
514                                         if (copy_file(rdir.buf, wtdir.buf,
515                                                       st.st_mode)) {
516                                                 ret = error("could not copy '%s' to '%s'", wtdir.buf, rdir.buf);
517                                                 goto finish;
518                                         }
519                                 }
520                         }
521                 }
522         }
523
524         fclose(fp);
525         fp = NULL;
526         if (finish_command(&child)) {
527                 ret = error("error occurred running diff --raw");
528                 goto finish;
529         }
530
531         if (!i)
532                 goto finish;
533
534         /*
535          * Changes to submodules require special treatment.This loop writes a
536          * temporary file to both the left and right directories to show the
537          * change in the recorded SHA1 for the submodule.
538          */
539         hashmap_iter_init(&submodules, &iter);
540         while ((entry = hashmap_iter_next(&iter))) {
541                 if (*entry->left) {
542                         add_path(&ldir, ldir_len, entry->path);
543                         ensure_leading_directories(ldir.buf);
544                         write_file(ldir.buf, "%s", entry->left);
545                 }
546                 if (*entry->right) {
547                         add_path(&rdir, rdir_len, entry->path);
548                         ensure_leading_directories(rdir.buf);
549                         write_file(rdir.buf, "%s", entry->right);
550                 }
551         }
552
553         /*
554          * Symbolic links require special treatment.The standard "git diff"
555          * shows only the link itself, not the contents of the link target.
556          * This loop replicates that behavior.
557          */
558         hashmap_iter_init(&symlinks2, &iter);
559         while ((entry = hashmap_iter_next(&iter))) {
560                 if (*entry->left) {
561                         add_path(&ldir, ldir_len, entry->path);
562                         ensure_leading_directories(ldir.buf);
563                         write_file(ldir.buf, "%s", entry->left);
564                 }
565                 if (*entry->right) {
566                         add_path(&rdir, rdir_len, entry->path);
567                         ensure_leading_directories(rdir.buf);
568                         write_file(rdir.buf, "%s", entry->right);
569                 }
570         }
571
572         strbuf_release(&buf);
573
574         strbuf_setlen(&ldir, ldir_len);
575         helper_argv[1] = ldir.buf;
576         strbuf_setlen(&rdir, rdir_len);
577         helper_argv[2] = rdir.buf;
578
579         if (extcmd) {
580                 helper_argv[0] = extcmd;
581                 flags = 0;
582         } else
583                 setenv("GIT_DIFFTOOL_DIRDIFF", "true", 1);
584         rc = run_command_v_opt(helper_argv, flags);
585
586         /*
587          * If the diff includes working copy files and those
588          * files were modified during the diff, then the changes
589          * should be copied back to the working tree.
590          * Do not copy back files when symlinks are used and the
591          * external tool did not replace the original link with a file.
592          *
593          * These hashes are loaded lazily since they aren't needed
594          * in the common case of --symlinks and the difftool updating
595          * files through the symlink.
596          */
597         hashmap_init(&wt_modified, path_entry_cmp, NULL, wtindex.cache_nr);
598         hashmap_init(&tmp_modified, path_entry_cmp, NULL, wtindex.cache_nr);
599
600         for (i = 0; i < wtindex.cache_nr; i++) {
601                 struct hashmap_entry dummy;
602                 const char *name = wtindex.cache[i]->name;
603                 struct stat st;
604
605                 add_path(&rdir, rdir_len, name);
606                 if (lstat(rdir.buf, &st))
607                         continue;
608
609                 if ((symlinks && S_ISLNK(st.st_mode)) || !S_ISREG(st.st_mode))
610                         continue;
611
612                 if (!indices_loaded) {
613                         struct lock_file lock = LOCK_INIT;
614                         strbuf_reset(&buf);
615                         strbuf_addf(&buf, "%s/wtindex", tmpdir);
616                         if (hold_lock_file_for_update(&lock, buf.buf, 0) < 0 ||
617                             write_locked_index(&wtindex, &lock, COMMIT_LOCK)) {
618                                 ret = error("could not write %s", buf.buf);
619                                 goto finish;
620                         }
621                         changed_files(&wt_modified, buf.buf, workdir);
622                         strbuf_setlen(&rdir, rdir_len);
623                         changed_files(&tmp_modified, buf.buf, rdir.buf);
624                         add_path(&rdir, rdir_len, name);
625                         indices_loaded = 1;
626                 }
627
628                 hashmap_entry_init(&dummy, strhash(name));
629                 if (hashmap_get(&tmp_modified, &dummy, name)) {
630                         add_path(&wtdir, wtdir_len, name);
631                         if (hashmap_get(&wt_modified, &dummy, name)) {
632                                 warning(_("both files modified: '%s' and '%s'."),
633                                         wtdir.buf, rdir.buf);
634                                 warning(_("working tree file has been left."));
635                                 warning("%s", "");
636                                 err = 1;
637                         } else if (unlink(wtdir.buf) ||
638                                    copy_file(wtdir.buf, rdir.buf, st.st_mode))
639                                 warning_errno(_("could not copy '%s' to '%s'"),
640                                               rdir.buf, wtdir.buf);
641                 }
642         }
643
644         if (err) {
645                 warning(_("temporary files exist in '%s'."), tmpdir);
646                 warning(_("you may want to cleanup or recover these."));
647                 exit(1);
648         } else
649                 exit_cleanup(tmpdir, rc);
650
651 finish:
652         if (fp)
653                 fclose(fp);
654
655         free(lbase_dir);
656         free(rbase_dir);
657         strbuf_release(&ldir);
658         strbuf_release(&rdir);
659         strbuf_release(&wtdir);
660         strbuf_release(&buf);
661
662         return ret;
663 }
664
665 static int run_file_diff(int prompt, const char *prefix,
666                          int argc, const char **argv)
667 {
668         struct argv_array args = ARGV_ARRAY_INIT;
669         const char *env[] = {
670                 "GIT_PAGER=", "GIT_EXTERNAL_DIFF=git-difftool--helper", NULL,
671                 NULL
672         };
673         int ret = 0, i;
674
675         if (prompt > 0)
676                 env[2] = "GIT_DIFFTOOL_PROMPT=true";
677         else if (!prompt)
678                 env[2] = "GIT_DIFFTOOL_NO_PROMPT=true";
679
680
681         argv_array_push(&args, "diff");
682         for (i = 0; i < argc; i++)
683                 argv_array_push(&args, argv[i]);
684         ret = run_command_v_opt_cd_env(args.argv, RUN_GIT_CMD, prefix, env);
685         exit(ret);
686 }
687
688 int cmd_difftool(int argc, const char **argv, const char *prefix)
689 {
690         int use_gui_tool = 0, dir_diff = 0, prompt = -1, symlinks = 0,
691             tool_help = 0;
692         static char *difftool_cmd = NULL, *extcmd = NULL;
693         struct option builtin_difftool_options[] = {
694                 OPT_BOOL('g', "gui", &use_gui_tool,
695                          N_("use `diff.guitool` instead of `diff.tool`")),
696                 OPT_BOOL('d', "dir-diff", &dir_diff,
697                          N_("perform a full-directory diff")),
698                 OPT_SET_INT_F('y', "no-prompt", &prompt,
699                         N_("do not prompt before launching a diff tool"),
700                         0, PARSE_OPT_NONEG),
701                 OPT_SET_INT_F(0, "prompt", &prompt, NULL,
702                         1, PARSE_OPT_NONEG | PARSE_OPT_HIDDEN),
703                 OPT_BOOL(0, "symlinks", &symlinks,
704                          N_("use symlinks in dir-diff mode")),
705                 OPT_STRING('t', "tool", &difftool_cmd, N_("<tool>"),
706                            N_("use the specified diff tool")),
707                 OPT_BOOL(0, "tool-help", &tool_help,
708                          N_("print a list of diff tools that may be used with "
709                             "`--tool`")),
710                 OPT_BOOL(0, "trust-exit-code", &trust_exit_code,
711                          N_("make 'git-difftool' exit when an invoked diff "
712                             "tool returns a non - zero exit code")),
713                 OPT_STRING('x', "extcmd", &extcmd, N_("<command>"),
714                            N_("specify a custom command for viewing diffs")),
715                 OPT_END()
716         };
717
718         git_config(difftool_config, NULL);
719         symlinks = has_symlinks;
720
721         argc = parse_options(argc, argv, prefix, builtin_difftool_options,
722                              builtin_difftool_usage, PARSE_OPT_KEEP_UNKNOWN |
723                              PARSE_OPT_KEEP_DASHDASH);
724
725         if (tool_help)
726                 return print_tool_help();
727
728         /* NEEDSWORK: once we no longer spawn anything, remove this */
729         setenv(GIT_DIR_ENVIRONMENT, absolute_path(get_git_dir()), 1);
730         setenv(GIT_WORK_TREE_ENVIRONMENT, absolute_path(get_git_work_tree()), 1);
731
732         if (use_gui_tool && diff_gui_tool && *diff_gui_tool)
733                 setenv("GIT_DIFF_TOOL", diff_gui_tool, 1);
734         else if (difftool_cmd) {
735                 if (*difftool_cmd)
736                         setenv("GIT_DIFF_TOOL", difftool_cmd, 1);
737                 else
738                         die(_("no <tool> given for --tool=<tool>"));
739         }
740
741         if (extcmd) {
742                 if (*extcmd)
743                         setenv("GIT_DIFFTOOL_EXTCMD", extcmd, 1);
744                 else
745                         die(_("no <cmd> given for --extcmd=<cmd>"));
746         }
747
748         setenv("GIT_DIFFTOOL_TRUST_EXIT_CODE",
749                trust_exit_code ? "true" : "false", 1);
750
751         /*
752          * In directory diff mode, 'git-difftool--helper' is called once
753          * to compare the a / b directories. In file diff mode, 'git diff'
754          * will invoke a separate instance of 'git-difftool--helper' for
755          * each file that changed.
756          */
757         if (dir_diff)
758                 return run_dir_diff(extcmd, symlinks, prefix, argc, argv);
759         return run_file_diff(prompt, prefix, argc, argv);
760 }