Merge branch 'jt/push-avoid-lazy-fetch'
[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 struct hashmap_entry *eptr,
129                                   const struct hashmap_entry *entry_or_key,
130                                   const void *unused_keydata)
131 {
132         const struct working_tree_entry *a, *b;
133
134         a = container_of(eptr, const struct working_tree_entry, entry);
135         b = container_of(entry_or_key, const struct working_tree_entry, entry);
136
137         return strcmp(a->path, b->path);
138 }
139
140 /*
141  * The `left` and `right` entries hold paths for the symlinks hashmap,
142  * and a SHA-1 surrounded by brief text for submodules.
143  */
144 struct pair_entry {
145         struct hashmap_entry entry;
146         char left[PATH_MAX], right[PATH_MAX];
147         const char path[FLEX_ARRAY];
148 };
149
150 static int pair_cmp(const void *unused_cmp_data,
151                     const struct hashmap_entry *eptr,
152                     const struct hashmap_entry *entry_or_key,
153                     const void *unused_keydata)
154 {
155         const struct pair_entry *a, *b;
156
157         a = container_of(eptr, const struct pair_entry, entry);
158         b = container_of(entry_or_key, const struct pair_entry, entry);
159
160         return strcmp(a->path, b->path);
161 }
162
163 static void add_left_or_right(struct hashmap *map, const char *path,
164                               const char *content, int is_right)
165 {
166         struct pair_entry *e, *existing;
167
168         FLEX_ALLOC_STR(e, path, path);
169         hashmap_entry_init(&e->entry, strhash(path));
170         existing = hashmap_get_entry(map, e, entry, NULL);
171         if (existing) {
172                 free(e);
173                 e = existing;
174         } else {
175                 e->left[0] = e->right[0] = '\0';
176                 hashmap_add(map, &e->entry);
177         }
178         strlcpy(is_right ? e->right : e->left, content, PATH_MAX);
179 }
180
181 struct path_entry {
182         struct hashmap_entry entry;
183         char path[FLEX_ARRAY];
184 };
185
186 static int path_entry_cmp(const void *unused_cmp_data,
187                           const struct hashmap_entry *eptr,
188                           const struct hashmap_entry *entry_or_key,
189                           const void *key)
190 {
191         const struct path_entry *a, *b;
192
193         a = container_of(eptr, const struct path_entry, entry);
194         b = container_of(entry_or_key, const struct path_entry, entry);
195
196         return strcmp(a->path, key ? key : b->path);
197 }
198
199 static void changed_files(struct hashmap *result, const char *index_path,
200                           const char *workdir)
201 {
202         struct child_process update_index = CHILD_PROCESS_INIT;
203         struct child_process diff_files = CHILD_PROCESS_INIT;
204         struct strbuf index_env = STRBUF_INIT, buf = STRBUF_INIT;
205         const char *git_dir = absolute_path(get_git_dir()), *env[] = {
206                 NULL, NULL
207         };
208         FILE *fp;
209
210         strbuf_addf(&index_env, "GIT_INDEX_FILE=%s", index_path);
211         env[0] = index_env.buf;
212
213         argv_array_pushl(&update_index.args,
214                          "--git-dir", git_dir, "--work-tree", workdir,
215                          "update-index", "--really-refresh", "-q",
216                          "--unmerged", NULL);
217         update_index.no_stdin = 1;
218         update_index.no_stdout = 1;
219         update_index.no_stderr = 1;
220         update_index.git_cmd = 1;
221         update_index.use_shell = 0;
222         update_index.clean_on_exit = 1;
223         update_index.dir = workdir;
224         update_index.env = env;
225         /* Ignore any errors of update-index */
226         run_command(&update_index);
227
228         argv_array_pushl(&diff_files.args,
229                          "--git-dir", git_dir, "--work-tree", workdir,
230                          "diff-files", "--name-only", "-z", NULL);
231         diff_files.no_stdin = 1;
232         diff_files.git_cmd = 1;
233         diff_files.use_shell = 0;
234         diff_files.clean_on_exit = 1;
235         diff_files.out = -1;
236         diff_files.dir = workdir;
237         diff_files.env = env;
238         if (start_command(&diff_files))
239                 die("could not obtain raw diff");
240         fp = xfdopen(diff_files.out, "r");
241         while (!strbuf_getline_nul(&buf, fp)) {
242                 struct path_entry *entry;
243                 FLEX_ALLOC_STR(entry, path, buf.buf);
244                 hashmap_entry_init(&entry->entry, strhash(buf.buf));
245                 hashmap_add(result, &entry->entry);
246         }
247         fclose(fp);
248         if (finish_command(&diff_files))
249                 die("diff-files did not exit properly");
250         strbuf_release(&index_env);
251         strbuf_release(&buf);
252 }
253
254 static NORETURN void exit_cleanup(const char *tmpdir, int exit_code)
255 {
256         struct strbuf buf = STRBUF_INIT;
257         strbuf_addstr(&buf, tmpdir);
258         remove_dir_recursively(&buf, 0);
259         if (exit_code)
260                 warning(_("failed: %d"), exit_code);
261         exit(exit_code);
262 }
263
264 static int ensure_leading_directories(char *path)
265 {
266         switch (safe_create_leading_directories(path)) {
267                 case SCLD_OK:
268                 case SCLD_EXISTS:
269                         return 0;
270                 default:
271                         return error(_("could not create leading directories "
272                                        "of '%s'"), path);
273         }
274 }
275
276 /*
277  * Unconditional writing of a plain regular file is what
278  * "git difftool --dir-diff" wants to do for symlinks.  We are preparing two
279  * temporary directories to be fed to a Git-unaware tool that knows how to
280  * show a diff of two directories (e.g. "diff -r A B").
281  *
282  * Because the tool is Git-unaware, if a symbolic link appears in either of
283  * these temporary directories, it will try to dereference and show the
284  * difference of the target of the symbolic link, which is not what we want,
285  * as the goal of the dir-diff mode is to produce an output that is logically
286  * equivalent to what "git diff" produces.
287  *
288  * Most importantly, we want to get textual comparison of the result of the
289  * readlink(2).  get_symlink() provides that---it returns the contents of
290  * the symlink that gets written to a regular file to force the external tool
291  * to compare the readlink(2) result as text, even on a filesystem that is
292  * capable of doing a symbolic link.
293  */
294 static char *get_symlink(const struct object_id *oid, const char *path)
295 {
296         char *data;
297         if (is_null_oid(oid)) {
298                 /* The symlink is unknown to Git so read from the filesystem */
299                 struct strbuf link = STRBUF_INIT;
300                 if (has_symlinks) {
301                         if (strbuf_readlink(&link, path, strlen(path)))
302                                 die(_("could not read symlink %s"), path);
303                 } else if (strbuf_read_file(&link, path, 128))
304                         die(_("could not read symlink file %s"), path);
305
306                 data = strbuf_detach(&link, NULL);
307         } else {
308                 enum object_type type;
309                 unsigned long size;
310                 data = read_object_file(oid, &type, &size);
311                 if (!data)
312                         die(_("could not read object %s for symlink %s"),
313                                 oid_to_hex(oid), path);
314         }
315
316         return data;
317 }
318
319 static int checkout_path(unsigned mode, struct object_id *oid,
320                          const char *path, const struct checkout *state)
321 {
322         struct cache_entry *ce;
323         int ret;
324
325         ce = make_transient_cache_entry(mode, oid, path, 0);
326         ret = checkout_entry(ce, state, NULL, NULL);
327
328         discard_cache_entry(ce);
329         return ret;
330 }
331
332 static int run_dir_diff(const char *extcmd, int symlinks, const char *prefix,
333                         int argc, const char **argv)
334 {
335         char tmpdir[PATH_MAX];
336         struct strbuf info = STRBUF_INIT, lpath = STRBUF_INIT;
337         struct strbuf rpath = STRBUF_INIT, buf = STRBUF_INIT;
338         struct strbuf ldir = STRBUF_INIT, rdir = STRBUF_INIT;
339         struct strbuf wtdir = STRBUF_INIT;
340         char *lbase_dir, *rbase_dir;
341         size_t ldir_len, rdir_len, wtdir_len;
342         const char *workdir, *tmp;
343         int ret = 0, i;
344         FILE *fp;
345         struct hashmap working_tree_dups, submodules, symlinks2;
346         struct hashmap_iter iter;
347         struct pair_entry *entry;
348         struct index_state wtindex;
349         struct checkout lstate, rstate;
350         int rc, flags = RUN_GIT_CMD, err = 0;
351         struct child_process child = CHILD_PROCESS_INIT;
352         const char *helper_argv[] = { "difftool--helper", NULL, NULL, NULL };
353         struct hashmap wt_modified, tmp_modified;
354         int indices_loaded = 0;
355
356         workdir = get_git_work_tree();
357
358         /* Setup temp directories */
359         tmp = getenv("TMPDIR");
360         xsnprintf(tmpdir, sizeof(tmpdir), "%s/git-difftool.XXXXXX", tmp ? tmp : "/tmp");
361         if (!mkdtemp(tmpdir))
362                 return error("could not create '%s'", tmpdir);
363         strbuf_addf(&ldir, "%s/left/", tmpdir);
364         strbuf_addf(&rdir, "%s/right/", tmpdir);
365         strbuf_addstr(&wtdir, workdir);
366         if (!wtdir.len || !is_dir_sep(wtdir.buf[wtdir.len - 1]))
367                 strbuf_addch(&wtdir, '/');
368         mkdir(ldir.buf, 0700);
369         mkdir(rdir.buf, 0700);
370
371         memset(&wtindex, 0, sizeof(wtindex));
372
373         memset(&lstate, 0, sizeof(lstate));
374         lstate.base_dir = lbase_dir = xstrdup(ldir.buf);
375         lstate.base_dir_len = ldir.len;
376         lstate.force = 1;
377         memset(&rstate, 0, sizeof(rstate));
378         rstate.base_dir = rbase_dir = xstrdup(rdir.buf);
379         rstate.base_dir_len = rdir.len;
380         rstate.force = 1;
381
382         ldir_len = ldir.len;
383         rdir_len = rdir.len;
384         wtdir_len = wtdir.len;
385
386         hashmap_init(&working_tree_dups, working_tree_entry_cmp, NULL, 0);
387         hashmap_init(&submodules, pair_cmp, NULL, 0);
388         hashmap_init(&symlinks2, pair_cmp, NULL, 0);
389
390         child.no_stdin = 1;
391         child.git_cmd = 1;
392         child.use_shell = 0;
393         child.clean_on_exit = 1;
394         child.dir = prefix;
395         child.out = -1;
396         argv_array_pushl(&child.args, "diff", "--raw", "--no-abbrev", "-z",
397                          NULL);
398         for (i = 0; i < argc; i++)
399                 argv_array_push(&child.args, argv[i]);
400         if (start_command(&child))
401                 die("could not obtain raw diff");
402         fp = xfdopen(child.out, "r");
403
404         /* Build index info for left and right sides of the diff */
405         i = 0;
406         while (!strbuf_getline_nul(&info, fp)) {
407                 int lmode, rmode;
408                 struct object_id loid, roid;
409                 char status;
410                 const char *src_path, *dst_path;
411
412                 if (starts_with(info.buf, "::"))
413                         die(N_("combined diff formats('-c' and '--cc') are "
414                                "not supported in\n"
415                                "directory diff mode('-d' and '--dir-diff')."));
416
417                 if (parse_index_info(info.buf, &lmode, &rmode, &loid, &roid,
418                                      &status))
419                         break;
420                 if (strbuf_getline_nul(&lpath, fp))
421                         break;
422                 src_path = lpath.buf;
423
424                 i++;
425                 if (status != 'C' && status != 'R') {
426                         dst_path = src_path;
427                 } else {
428                         if (strbuf_getline_nul(&rpath, fp))
429                                 break;
430                         dst_path = rpath.buf;
431                 }
432
433                 if (S_ISGITLINK(lmode) || S_ISGITLINK(rmode)) {
434                         strbuf_reset(&buf);
435                         strbuf_addf(&buf, "Subproject commit %s",
436                                     oid_to_hex(&loid));
437                         add_left_or_right(&submodules, src_path, buf.buf, 0);
438                         strbuf_reset(&buf);
439                         strbuf_addf(&buf, "Subproject commit %s",
440                                     oid_to_hex(&roid));
441                         if (oideq(&loid, &roid))
442                                 strbuf_addstr(&buf, "-dirty");
443                         add_left_or_right(&submodules, dst_path, buf.buf, 1);
444                         continue;
445                 }
446
447                 if (S_ISLNK(lmode)) {
448                         char *content = get_symlink(&loid, src_path);
449                         add_left_or_right(&symlinks2, src_path, content, 0);
450                         free(content);
451                 }
452
453                 if (S_ISLNK(rmode)) {
454                         char *content = get_symlink(&roid, dst_path);
455                         add_left_or_right(&symlinks2, dst_path, content, 1);
456                         free(content);
457                 }
458
459                 if (lmode && status != 'C') {
460                         if (checkout_path(lmode, &loid, src_path, &lstate)) {
461                                 ret = error("could not write '%s'", src_path);
462                                 goto finish;
463                         }
464                 }
465
466                 if (rmode && !S_ISLNK(rmode)) {
467                         struct working_tree_entry *entry;
468
469                         /* Avoid duplicate working_tree entries */
470                         FLEX_ALLOC_STR(entry, path, dst_path);
471                         hashmap_entry_init(&entry->entry, strhash(dst_path));
472                         if (hashmap_get(&working_tree_dups, &entry->entry,
473                                         NULL)) {
474                                 free(entry);
475                                 continue;
476                         }
477                         hashmap_add(&working_tree_dups, &entry->entry);
478
479                         if (!use_wt_file(workdir, dst_path, &roid)) {
480                                 if (checkout_path(rmode, &roid, dst_path,
481                                                   &rstate)) {
482                                         ret = error("could not write '%s'",
483                                                     dst_path);
484                                         goto finish;
485                                 }
486                         } else if (!is_null_oid(&roid)) {
487                                 /*
488                                  * Changes in the working tree need special
489                                  * treatment since they are not part of the
490                                  * index.
491                                  */
492                                 struct cache_entry *ce2 =
493                                         make_cache_entry(&wtindex, rmode, &roid,
494                                                          dst_path, 0, 0);
495
496                                 add_index_entry(&wtindex, ce2,
497                                                 ADD_CACHE_JUST_APPEND);
498
499                                 add_path(&rdir, rdir_len, dst_path);
500                                 if (ensure_leading_directories(rdir.buf)) {
501                                         ret = error("could not create "
502                                                     "directory for '%s'",
503                                                     dst_path);
504                                         goto finish;
505                                 }
506                                 add_path(&wtdir, wtdir_len, dst_path);
507                                 if (symlinks) {
508                                         if (symlink(wtdir.buf, rdir.buf)) {
509                                                 ret = error_errno("could not symlink '%s' to '%s'", wtdir.buf, rdir.buf);
510                                                 goto finish;
511                                         }
512                                 } else {
513                                         struct stat st;
514                                         if (stat(wtdir.buf, &st))
515                                                 st.st_mode = 0644;
516                                         if (copy_file(rdir.buf, wtdir.buf,
517                                                       st.st_mode)) {
518                                                 ret = error("could not copy '%s' to '%s'", wtdir.buf, rdir.buf);
519                                                 goto finish;
520                                         }
521                                 }
522                         }
523                 }
524         }
525
526         fclose(fp);
527         fp = NULL;
528         if (finish_command(&child)) {
529                 ret = error("error occurred running diff --raw");
530                 goto finish;
531         }
532
533         if (!i)
534                 goto finish;
535
536         /*
537          * Changes to submodules require special treatment.This loop writes a
538          * temporary file to both the left and right directories to show the
539          * change in the recorded SHA1 for the submodule.
540          */
541         hashmap_for_each_entry(&submodules, &iter, entry,
542                                 entry /* member name */) {
543                 if (*entry->left) {
544                         add_path(&ldir, ldir_len, entry->path);
545                         ensure_leading_directories(ldir.buf);
546                         write_file(ldir.buf, "%s", entry->left);
547                 }
548                 if (*entry->right) {
549                         add_path(&rdir, rdir_len, entry->path);
550                         ensure_leading_directories(rdir.buf);
551                         write_file(rdir.buf, "%s", entry->right);
552                 }
553         }
554
555         /*
556          * Symbolic links require special treatment.The standard "git diff"
557          * shows only the link itself, not the contents of the link target.
558          * This loop replicates that behavior.
559          */
560         hashmap_for_each_entry(&symlinks2, &iter, entry,
561                                 entry /* member name */) {
562                 if (*entry->left) {
563                         add_path(&ldir, ldir_len, entry->path);
564                         ensure_leading_directories(ldir.buf);
565                         write_file(ldir.buf, "%s", entry->left);
566                 }
567                 if (*entry->right) {
568                         add_path(&rdir, rdir_len, entry->path);
569                         ensure_leading_directories(rdir.buf);
570                         write_file(rdir.buf, "%s", entry->right);
571                 }
572         }
573
574         strbuf_release(&buf);
575
576         strbuf_setlen(&ldir, ldir_len);
577         helper_argv[1] = ldir.buf;
578         strbuf_setlen(&rdir, rdir_len);
579         helper_argv[2] = rdir.buf;
580
581         if (extcmd) {
582                 helper_argv[0] = extcmd;
583                 flags = 0;
584         } else
585                 setenv("GIT_DIFFTOOL_DIRDIFF", "true", 1);
586         rc = run_command_v_opt(helper_argv, flags);
587
588         /*
589          * If the diff includes working copy files and those
590          * files were modified during the diff, then the changes
591          * should be copied back to the working tree.
592          * Do not copy back files when symlinks are used and the
593          * external tool did not replace the original link with a file.
594          *
595          * These hashes are loaded lazily since they aren't needed
596          * in the common case of --symlinks and the difftool updating
597          * files through the symlink.
598          */
599         hashmap_init(&wt_modified, path_entry_cmp, NULL, wtindex.cache_nr);
600         hashmap_init(&tmp_modified, path_entry_cmp, NULL, wtindex.cache_nr);
601
602         for (i = 0; i < wtindex.cache_nr; i++) {
603                 struct hashmap_entry dummy;
604                 const char *name = wtindex.cache[i]->name;
605                 struct stat st;
606
607                 add_path(&rdir, rdir_len, name);
608                 if (lstat(rdir.buf, &st))
609                         continue;
610
611                 if ((symlinks && S_ISLNK(st.st_mode)) || !S_ISREG(st.st_mode))
612                         continue;
613
614                 if (!indices_loaded) {
615                         struct lock_file lock = LOCK_INIT;
616                         strbuf_reset(&buf);
617                         strbuf_addf(&buf, "%s/wtindex", tmpdir);
618                         if (hold_lock_file_for_update(&lock, buf.buf, 0) < 0 ||
619                             write_locked_index(&wtindex, &lock, COMMIT_LOCK)) {
620                                 ret = error("could not write %s", buf.buf);
621                                 goto finish;
622                         }
623                         changed_files(&wt_modified, buf.buf, workdir);
624                         strbuf_setlen(&rdir, rdir_len);
625                         changed_files(&tmp_modified, buf.buf, rdir.buf);
626                         add_path(&rdir, rdir_len, name);
627                         indices_loaded = 1;
628                 }
629
630                 hashmap_entry_init(&dummy, strhash(name));
631                 if (hashmap_get(&tmp_modified, &dummy, name)) {
632                         add_path(&wtdir, wtdir_len, name);
633                         if (hashmap_get(&wt_modified, &dummy, name)) {
634                                 warning(_("both files modified: '%s' and '%s'."),
635                                         wtdir.buf, rdir.buf);
636                                 warning(_("working tree file has been left."));
637                                 warning("%s", "");
638                                 err = 1;
639                         } else if (unlink(wtdir.buf) ||
640                                    copy_file(wtdir.buf, rdir.buf, st.st_mode))
641                                 warning_errno(_("could not copy '%s' to '%s'"),
642                                               rdir.buf, wtdir.buf);
643                 }
644         }
645
646         if (err) {
647                 warning(_("temporary files exist in '%s'."), tmpdir);
648                 warning(_("you may want to cleanup or recover these."));
649                 exit(1);
650         } else
651                 exit_cleanup(tmpdir, rc);
652
653 finish:
654         if (fp)
655                 fclose(fp);
656
657         free(lbase_dir);
658         free(rbase_dir);
659         strbuf_release(&ldir);
660         strbuf_release(&rdir);
661         strbuf_release(&wtdir);
662         strbuf_release(&buf);
663
664         return ret;
665 }
666
667 static int run_file_diff(int prompt, const char *prefix,
668                          int argc, const char **argv)
669 {
670         struct argv_array args = ARGV_ARRAY_INIT;
671         const char *env[] = {
672                 "GIT_PAGER=", "GIT_EXTERNAL_DIFF=git-difftool--helper", NULL,
673                 NULL
674         };
675         int ret = 0, i;
676
677         if (prompt > 0)
678                 env[2] = "GIT_DIFFTOOL_PROMPT=true";
679         else if (!prompt)
680                 env[2] = "GIT_DIFFTOOL_NO_PROMPT=true";
681
682
683         argv_array_push(&args, "diff");
684         for (i = 0; i < argc; i++)
685                 argv_array_push(&args, argv[i]);
686         ret = run_command_v_opt_cd_env(args.argv, RUN_GIT_CMD, prefix, env);
687         exit(ret);
688 }
689
690 int cmd_difftool(int argc, const char **argv, const char *prefix)
691 {
692         int use_gui_tool = 0, dir_diff = 0, prompt = -1, symlinks = 0,
693             tool_help = 0, no_index = 0;
694         static char *difftool_cmd = NULL, *extcmd = NULL;
695         struct option builtin_difftool_options[] = {
696                 OPT_BOOL('g', "gui", &use_gui_tool,
697                          N_("use `diff.guitool` instead of `diff.tool`")),
698                 OPT_BOOL('d', "dir-diff", &dir_diff,
699                          N_("perform a full-directory diff")),
700                 OPT_SET_INT_F('y', "no-prompt", &prompt,
701                         N_("do not prompt before launching a diff tool"),
702                         0, PARSE_OPT_NONEG),
703                 OPT_SET_INT_F(0, "prompt", &prompt, NULL,
704                         1, PARSE_OPT_NONEG | PARSE_OPT_HIDDEN),
705                 OPT_BOOL(0, "symlinks", &symlinks,
706                          N_("use symlinks in dir-diff mode")),
707                 OPT_STRING('t', "tool", &difftool_cmd, N_("tool"),
708                            N_("use the specified diff tool")),
709                 OPT_BOOL(0, "tool-help", &tool_help,
710                          N_("print a list of diff tools that may be used with "
711                             "`--tool`")),
712                 OPT_BOOL(0, "trust-exit-code", &trust_exit_code,
713                          N_("make 'git-difftool' exit when an invoked diff "
714                             "tool returns a non - zero exit code")),
715                 OPT_STRING('x', "extcmd", &extcmd, N_("command"),
716                            N_("specify a custom command for viewing diffs")),
717                 OPT_ARGUMENT("no-index", &no_index, N_("passed to `diff`")),
718                 OPT_END()
719         };
720
721         git_config(difftool_config, NULL);
722         symlinks = has_symlinks;
723
724         argc = parse_options(argc, argv, prefix, builtin_difftool_options,
725                              builtin_difftool_usage, PARSE_OPT_KEEP_UNKNOWN |
726                              PARSE_OPT_KEEP_DASHDASH);
727
728         if (tool_help)
729                 return print_tool_help();
730
731         if (!no_index && !startup_info->have_repository)
732                 die(_("difftool requires worktree or --no-index"));
733
734         if (!no_index){
735                 setup_work_tree();
736                 setenv(GIT_DIR_ENVIRONMENT, absolute_path(get_git_dir()), 1);
737                 setenv(GIT_WORK_TREE_ENVIRONMENT, absolute_path(get_git_work_tree()), 1);
738         } else if (dir_diff)
739                 die(_("--dir-diff is incompatible with --no-index"));
740
741         if (use_gui_tool + !!difftool_cmd + !!extcmd > 1)
742                 die(_("--gui, --tool and --extcmd are mutually exclusive"));
743
744         if (use_gui_tool)
745                 setenv("GIT_MERGETOOL_GUI", "true", 1);
746         else if (difftool_cmd) {
747                 if (*difftool_cmd)
748                         setenv("GIT_DIFF_TOOL", difftool_cmd, 1);
749                 else
750                         die(_("no <tool> given for --tool=<tool>"));
751         }
752
753         if (extcmd) {
754                 if (*extcmd)
755                         setenv("GIT_DIFFTOOL_EXTCMD", extcmd, 1);
756                 else
757                         die(_("no <cmd> given for --extcmd=<cmd>"));
758         }
759
760         setenv("GIT_DIFFTOOL_TRUST_EXIT_CODE",
761                trust_exit_code ? "true" : "false", 1);
762
763         /*
764          * In directory diff mode, 'git-difftool--helper' is called once
765          * to compare the a / b directories. In file diff mode, 'git diff'
766          * will invoke a separate instance of 'git-difftool--helper' for
767          * each file that changed.
768          */
769         if (dir_diff)
770                 return run_dir_diff(extcmd, symlinks, prefix, argc, argv);
771         return run_file_diff(prompt, prefix, argc, argv);
772 }