Merge branch 'nd/fopen-errors'
[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 "builtin.h"
16 #include "run-command.h"
17 #include "exec_cmd.h"
18 #include "parse-options.h"
19 #include "argv-array.h"
20 #include "strbuf.h"
21 #include "lockfile.h"
22 #include "dir.h"
23
24 static char *diff_gui_tool;
25 static int trust_exit_code;
26
27 static const char *const builtin_difftool_usage[] = {
28         N_("git difftool [<options>] [<commit> [<commit>]] [--] [<path>...]"),
29         NULL
30 };
31
32 static int difftool_config(const char *var, const char *value, void *cb)
33 {
34         if (!strcmp(var, "diff.guitool")) {
35                 diff_gui_tool = xstrdup(value);
36                 return 0;
37         }
38
39         if (!strcmp(var, "difftool.trustexitcode")) {
40                 trust_exit_code = git_config_bool(var, value);
41                 return 0;
42         }
43
44         return git_default_config(var, value, cb);
45 }
46
47 static int print_tool_help(void)
48 {
49         const char *argv[] = { "mergetool", "--tool-help=diff", NULL };
50         return run_command_v_opt(argv, RUN_GIT_CMD);
51 }
52
53 static int parse_index_info(char *p, int *mode1, int *mode2,
54                             struct object_id *oid1, struct object_id *oid2,
55                             char *status)
56 {
57         if (*p != ':')
58                 return error("expected ':', got '%c'", *p);
59         *mode1 = (int)strtol(p + 1, &p, 8);
60         if (*p != ' ')
61                 return error("expected ' ', got '%c'", *p);
62         *mode2 = (int)strtol(p + 1, &p, 8);
63         if (*p != ' ')
64                 return error("expected ' ', got '%c'", *p);
65         if (get_oid_hex(++p, oid1))
66                 return error("expected object ID, got '%s'", p + 1);
67         p += GIT_SHA1_HEXSZ;
68         if (*p != ' ')
69                 return error("expected ' ', got '%c'", *p);
70         if (get_oid_hex(++p, oid2))
71                 return error("expected object ID, got '%s'", p + 1);
72         p += GIT_SHA1_HEXSZ;
73         if (*p != ' ')
74                 return error("expected ' ', got '%c'", *p);
75         *status = *++p;
76         if (!*status)
77                 return error("missing status");
78         if (p[1] && !isdigit(p[1]))
79                 return error("unexpected trailer: '%s'", p + 1);
80         return 0;
81 }
82
83 /*
84  * Remove any trailing slash from $workdir
85  * before starting to avoid double slashes in symlink targets.
86  */
87 static void add_path(struct strbuf *buf, size_t base_len, const char *path)
88 {
89         strbuf_setlen(buf, base_len);
90         if (buf->len && buf->buf[buf->len - 1] != '/')
91                 strbuf_addch(buf, '/');
92         strbuf_addstr(buf, path);
93 }
94
95 /*
96  * Determine whether we can simply reuse the file in the worktree.
97  */
98 static int use_wt_file(const char *workdir, const char *name,
99                        struct object_id *oid)
100 {
101         struct strbuf buf = STRBUF_INIT;
102         struct stat st;
103         int use = 0;
104
105         strbuf_addstr(&buf, workdir);
106         add_path(&buf, buf.len, name);
107
108         if (!lstat(buf.buf, &st) && !S_ISLNK(st.st_mode)) {
109                 struct object_id wt_oid;
110                 int fd = open(buf.buf, O_RDONLY);
111
112                 if (fd >= 0 &&
113                     !index_fd(wt_oid.hash, fd, &st, OBJ_BLOB, name, 0)) {
114                         if (is_null_oid(oid)) {
115                                 oidcpy(oid, &wt_oid);
116                                 use = 1;
117                         } else if (!oidcmp(oid, &wt_oid))
118                                 use = 1;
119                 }
120         }
121
122         strbuf_release(&buf);
123
124         return use;
125 }
126
127 struct working_tree_entry {
128         struct hashmap_entry entry;
129         char path[FLEX_ARRAY];
130 };
131
132 static int working_tree_entry_cmp(struct working_tree_entry *a,
133                                   struct working_tree_entry *b, void *keydata)
134 {
135         return strcmp(a->path, b->path);
136 }
137
138 /*
139  * The `left` and `right` entries hold paths for the symlinks hashmap,
140  * and a SHA-1 surrounded by brief text for submodules.
141  */
142 struct pair_entry {
143         struct hashmap_entry entry;
144         char left[PATH_MAX], right[PATH_MAX];
145         const char path[FLEX_ARRAY];
146 };
147
148 static int pair_cmp(struct pair_entry *a, struct pair_entry *b, void *keydata)
149 {
150         return strcmp(a->path, b->path);
151 }
152
153 static void add_left_or_right(struct hashmap *map, const char *path,
154                               const char *content, int is_right)
155 {
156         struct pair_entry *e, *existing;
157
158         FLEX_ALLOC_STR(e, path, path);
159         hashmap_entry_init(e, strhash(path));
160         existing = hashmap_get(map, e, NULL);
161         if (existing) {
162                 free(e);
163                 e = existing;
164         } else {
165                 e->left[0] = e->right[0] = '\0';
166                 hashmap_add(map, e);
167         }
168         strlcpy(is_right ? e->right : e->left, content, PATH_MAX);
169 }
170
171 struct path_entry {
172         struct hashmap_entry entry;
173         char path[FLEX_ARRAY];
174 };
175
176 static int path_entry_cmp(struct path_entry *a, struct path_entry *b, void *key)
177 {
178         return strcmp(a->path, key ? key : b->path);
179 }
180
181 static void changed_files(struct hashmap *result, const char *index_path,
182                           const char *workdir)
183 {
184         struct child_process update_index = CHILD_PROCESS_INIT;
185         struct child_process diff_files = CHILD_PROCESS_INIT;
186         struct strbuf index_env = STRBUF_INIT, buf = STRBUF_INIT;
187         const char *git_dir = absolute_path(get_git_dir()), *env[] = {
188                 NULL, NULL
189         };
190         FILE *fp;
191
192         strbuf_addf(&index_env, "GIT_INDEX_FILE=%s", index_path);
193         env[0] = index_env.buf;
194
195         argv_array_pushl(&update_index.args,
196                          "--git-dir", git_dir, "--work-tree", workdir,
197                          "update-index", "--really-refresh", "-q",
198                          "--unmerged", NULL);
199         update_index.no_stdin = 1;
200         update_index.no_stdout = 1;
201         update_index.no_stderr = 1;
202         update_index.git_cmd = 1;
203         update_index.use_shell = 0;
204         update_index.clean_on_exit = 1;
205         update_index.dir = workdir;
206         update_index.env = env;
207         /* Ignore any errors of update-index */
208         run_command(&update_index);
209
210         argv_array_pushl(&diff_files.args,
211                          "--git-dir", git_dir, "--work-tree", workdir,
212                          "diff-files", "--name-only", "-z", NULL);
213         diff_files.no_stdin = 1;
214         diff_files.git_cmd = 1;
215         diff_files.use_shell = 0;
216         diff_files.clean_on_exit = 1;
217         diff_files.out = -1;
218         diff_files.dir = workdir;
219         diff_files.env = env;
220         if (start_command(&diff_files))
221                 die("could not obtain raw diff");
222         fp = xfdopen(diff_files.out, "r");
223         while (!strbuf_getline_nul(&buf, fp)) {
224                 struct path_entry *entry;
225                 FLEX_ALLOC_STR(entry, path, buf.buf);
226                 hashmap_entry_init(entry, strhash(buf.buf));
227                 hashmap_add(result, entry);
228         }
229         fclose(fp);
230         if (finish_command(&diff_files))
231                 die("diff-files did not exit properly");
232         strbuf_release(&index_env);
233         strbuf_release(&buf);
234 }
235
236 static NORETURN void exit_cleanup(const char *tmpdir, int exit_code)
237 {
238         struct strbuf buf = STRBUF_INIT;
239         strbuf_addstr(&buf, tmpdir);
240         remove_dir_recursively(&buf, 0);
241         if (exit_code)
242                 warning(_("failed: %d"), exit_code);
243         exit(exit_code);
244 }
245
246 static int ensure_leading_directories(char *path)
247 {
248         switch (safe_create_leading_directories(path)) {
249                 case SCLD_OK:
250                 case SCLD_EXISTS:
251                         return 0;
252                 default:
253                         return error(_("could not create leading directories "
254                                        "of '%s'"), path);
255         }
256 }
257
258 /*
259  * Unconditional writing of a plain regular file is what
260  * "git difftool --dir-diff" wants to do for symlinks.  We are preparing two
261  * temporary directories to be fed to a Git-unaware tool that knows how to
262  * show a diff of two directories (e.g. "diff -r A B").
263  *
264  * Because the tool is Git-unaware, if a symbolic link appears in either of
265  * these temporary directories, it will try to dereference and show the
266  * difference of the target of the symbolic link, which is not what we want,
267  * as the goal of the dir-diff mode is to produce an output that is logically
268  * equivalent to what "git diff" produces.
269  *
270  * Most importantly, we want to get textual comparison of the result of the
271  * readlink(2).  get_symlink() provides that---it returns the contents of
272  * the symlink that gets written to a regular file to force the external tool
273  * to compare the readlink(2) result as text, even on a filesystem that is
274  * capable of doing a symbolic link.
275  */
276 static char *get_symlink(const struct object_id *oid, const char *path)
277 {
278         char *data;
279         if (is_null_oid(oid)) {
280                 /* The symlink is unknown to Git so read from the filesystem */
281                 struct strbuf link = STRBUF_INIT;
282                 if (has_symlinks) {
283                         if (strbuf_readlink(&link, path, strlen(path)))
284                                 die(_("could not read symlink %s"), path);
285                 } else if (strbuf_read_file(&link, path, 128))
286                         die(_("could not read symlink file %s"), path);
287
288                 data = strbuf_detach(&link, NULL);
289         } else {
290                 enum object_type type;
291                 unsigned long size;
292                 data = read_sha1_file(oid->hash, &type, &size);
293                 if (!data)
294                         die(_("could not read object %s for symlink %s"),
295                                 oid_to_hex(oid), path);
296         }
297
298         return data;
299 }
300
301 static int checkout_path(unsigned mode, struct object_id *oid,
302                          const char *path, const struct checkout *state)
303 {
304         struct cache_entry *ce;
305         int ret;
306
307         ce = make_cache_entry(mode, oid->hash, path, 0, 0);
308         ret = checkout_entry(ce, state, NULL);
309
310         free(ce);
311         return ret;
312 }
313
314 static int run_dir_diff(const char *extcmd, int symlinks, const char *prefix,
315                         int argc, const char **argv)
316 {
317         char tmpdir[PATH_MAX];
318         struct strbuf info = STRBUF_INIT, lpath = STRBUF_INIT;
319         struct strbuf rpath = STRBUF_INIT, buf = STRBUF_INIT;
320         struct strbuf ldir = STRBUF_INIT, rdir = STRBUF_INIT;
321         struct strbuf wtdir = STRBUF_INIT;
322         char *lbase_dir, *rbase_dir;
323         size_t ldir_len, rdir_len, wtdir_len;
324         const char *workdir, *tmp;
325         int ret = 0, i;
326         FILE *fp;
327         struct hashmap working_tree_dups, submodules, symlinks2;
328         struct hashmap_iter iter;
329         struct pair_entry *entry;
330         struct index_state wtindex;
331         struct checkout lstate, rstate;
332         int rc, flags = RUN_GIT_CMD, err = 0;
333         struct child_process child = CHILD_PROCESS_INIT;
334         const char *helper_argv[] = { "difftool--helper", NULL, NULL, NULL };
335         struct hashmap wt_modified, tmp_modified;
336         int indices_loaded = 0;
337
338         workdir = get_git_work_tree();
339
340         /* Setup temp directories */
341         tmp = getenv("TMPDIR");
342         xsnprintf(tmpdir, sizeof(tmpdir), "%s/git-difftool.XXXXXX", tmp ? tmp : "/tmp");
343         if (!mkdtemp(tmpdir))
344                 return error("could not create '%s'", tmpdir);
345         strbuf_addf(&ldir, "%s/left/", tmpdir);
346         strbuf_addf(&rdir, "%s/right/", tmpdir);
347         strbuf_addstr(&wtdir, workdir);
348         if (!wtdir.len || !is_dir_sep(wtdir.buf[wtdir.len - 1]))
349                 strbuf_addch(&wtdir, '/');
350         mkdir(ldir.buf, 0700);
351         mkdir(rdir.buf, 0700);
352
353         memset(&wtindex, 0, sizeof(wtindex));
354
355         memset(&lstate, 0, sizeof(lstate));
356         lstate.base_dir = lbase_dir = xstrdup(ldir.buf);
357         lstate.base_dir_len = ldir.len;
358         lstate.force = 1;
359         memset(&rstate, 0, sizeof(rstate));
360         rstate.base_dir = rbase_dir = xstrdup(rdir.buf);
361         rstate.base_dir_len = rdir.len;
362         rstate.force = 1;
363
364         ldir_len = ldir.len;
365         rdir_len = rdir.len;
366         wtdir_len = wtdir.len;
367
368         hashmap_init(&working_tree_dups,
369                      (hashmap_cmp_fn)working_tree_entry_cmp, 0);
370         hashmap_init(&submodules, (hashmap_cmp_fn)pair_cmp, 0);
371         hashmap_init(&symlinks2, (hashmap_cmp_fn)pair_cmp, 0);
372
373         child.no_stdin = 1;
374         child.git_cmd = 1;
375         child.use_shell = 0;
376         child.clean_on_exit = 1;
377         child.dir = prefix;
378         child.out = -1;
379         argv_array_pushl(&child.args, "diff", "--raw", "--no-abbrev", "-z",
380                          NULL);
381         for (i = 0; i < argc; i++)
382                 argv_array_push(&child.args, argv[i]);
383         if (start_command(&child))
384                 die("could not obtain raw diff");
385         fp = xfdopen(child.out, "r");
386
387         /* Build index info for left and right sides of the diff */
388         i = 0;
389         while (!strbuf_getline_nul(&info, fp)) {
390                 int lmode, rmode;
391                 struct object_id loid, roid;
392                 char status;
393                 const char *src_path, *dst_path;
394
395                 if (starts_with(info.buf, "::"))
396                         die(N_("combined diff formats('-c' and '--cc') are "
397                                "not supported in\n"
398                                "directory diff mode('-d' and '--dir-diff')."));
399
400                 if (parse_index_info(info.buf, &lmode, &rmode, &loid, &roid,
401                                      &status))
402                         break;
403                 if (strbuf_getline_nul(&lpath, fp))
404                         break;
405                 src_path = lpath.buf;
406
407                 i++;
408                 if (status != 'C' && status != 'R') {
409                         dst_path = src_path;
410                 } else {
411                         if (strbuf_getline_nul(&rpath, fp))
412                                 break;
413                         dst_path = rpath.buf;
414                 }
415
416                 if (S_ISGITLINK(lmode) || S_ISGITLINK(rmode)) {
417                         strbuf_reset(&buf);
418                         strbuf_addf(&buf, "Subproject commit %s",
419                                     oid_to_hex(&loid));
420                         add_left_or_right(&submodules, src_path, buf.buf, 0);
421                         strbuf_reset(&buf);
422                         strbuf_addf(&buf, "Subproject commit %s",
423                                     oid_to_hex(&roid));
424                         if (!oidcmp(&loid, &roid))
425                                 strbuf_addstr(&buf, "-dirty");
426                         add_left_or_right(&submodules, dst_path, buf.buf, 1);
427                         continue;
428                 }
429
430                 if (S_ISLNK(lmode)) {
431                         char *content = get_symlink(&loid, src_path);
432                         add_left_or_right(&symlinks2, src_path, content, 0);
433                         free(content);
434                 }
435
436                 if (S_ISLNK(rmode)) {
437                         char *content = get_symlink(&roid, dst_path);
438                         add_left_or_right(&symlinks2, dst_path, content, 1);
439                         free(content);
440                 }
441
442                 if (lmode && status != 'C') {
443                         if (checkout_path(lmode, &loid, src_path, &lstate)) {
444                                 ret = error("could not write '%s'", src_path);
445                                 goto finish;
446                         }
447                 }
448
449                 if (rmode && !S_ISLNK(rmode)) {
450                         struct working_tree_entry *entry;
451
452                         /* Avoid duplicate working_tree entries */
453                         FLEX_ALLOC_STR(entry, path, dst_path);
454                         hashmap_entry_init(entry, strhash(dst_path));
455                         if (hashmap_get(&working_tree_dups, entry, NULL)) {
456                                 free(entry);
457                                 continue;
458                         }
459                         hashmap_add(&working_tree_dups, entry);
460
461                         if (!use_wt_file(workdir, dst_path, &roid)) {
462                                 if (checkout_path(rmode, &roid, dst_path,
463                                                   &rstate)) {
464                                         ret = error("could not write '%s'",
465                                                     dst_path);
466                                         goto finish;
467                                 }
468                         } else if (!is_null_oid(&roid)) {
469                                 /*
470                                  * Changes in the working tree need special
471                                  * treatment since they are not part of the
472                                  * index.
473                                  */
474                                 struct cache_entry *ce2 =
475                                         make_cache_entry(rmode, roid.hash,
476                                                          dst_path, 0, 0);
477
478                                 add_index_entry(&wtindex, ce2,
479                                                 ADD_CACHE_JUST_APPEND);
480
481                                 add_path(&rdir, rdir_len, dst_path);
482                                 if (ensure_leading_directories(rdir.buf)) {
483                                         ret = error("could not create "
484                                                     "directory for '%s'",
485                                                     dst_path);
486                                         goto finish;
487                                 }
488                                 add_path(&wtdir, wtdir_len, dst_path);
489                                 if (symlinks) {
490                                         if (symlink(wtdir.buf, rdir.buf)) {
491                                                 ret = error_errno("could not symlink '%s' to '%s'", wtdir.buf, rdir.buf);
492                                                 goto finish;
493                                         }
494                                 } else {
495                                         struct stat st;
496                                         if (stat(wtdir.buf, &st))
497                                                 st.st_mode = 0644;
498                                         if (copy_file(rdir.buf, wtdir.buf,
499                                                       st.st_mode)) {
500                                                 ret = error("could not copy '%s' to '%s'", wtdir.buf, rdir.buf);
501                                                 goto finish;
502                                         }
503                                 }
504                         }
505                 }
506         }
507
508         fclose(fp);
509         fp = NULL;
510         if (finish_command(&child)) {
511                 ret = error("error occurred running diff --raw");
512                 goto finish;
513         }
514
515         if (!i)
516                 goto finish;
517
518         /*
519          * Changes to submodules require special treatment.This loop writes a
520          * temporary file to both the left and right directories to show the
521          * change in the recorded SHA1 for the submodule.
522          */
523         hashmap_iter_init(&submodules, &iter);
524         while ((entry = hashmap_iter_next(&iter))) {
525                 if (*entry->left) {
526                         add_path(&ldir, ldir_len, entry->path);
527                         ensure_leading_directories(ldir.buf);
528                         write_file(ldir.buf, "%s", entry->left);
529                 }
530                 if (*entry->right) {
531                         add_path(&rdir, rdir_len, entry->path);
532                         ensure_leading_directories(rdir.buf);
533                         write_file(rdir.buf, "%s", entry->right);
534                 }
535         }
536
537         /*
538          * Symbolic links require special treatment.The standard "git diff"
539          * shows only the link itself, not the contents of the link target.
540          * This loop replicates that behavior.
541          */
542         hashmap_iter_init(&symlinks2, &iter);
543         while ((entry = hashmap_iter_next(&iter))) {
544                 if (*entry->left) {
545                         add_path(&ldir, ldir_len, entry->path);
546                         ensure_leading_directories(ldir.buf);
547                         write_file(ldir.buf, "%s", entry->left);
548                 }
549                 if (*entry->right) {
550                         add_path(&rdir, rdir_len, entry->path);
551                         ensure_leading_directories(rdir.buf);
552                         write_file(rdir.buf, "%s", entry->right);
553                 }
554         }
555
556         strbuf_release(&buf);
557
558         strbuf_setlen(&ldir, ldir_len);
559         helper_argv[1] = ldir.buf;
560         strbuf_setlen(&rdir, rdir_len);
561         helper_argv[2] = rdir.buf;
562
563         if (extcmd) {
564                 helper_argv[0] = extcmd;
565                 flags = 0;
566         } else
567                 setenv("GIT_DIFFTOOL_DIRDIFF", "true", 1);
568         rc = run_command_v_opt(helper_argv, flags);
569
570         /*
571          * If the diff includes working copy files and those
572          * files were modified during the diff, then the changes
573          * should be copied back to the working tree.
574          * Do not copy back files when symlinks are used and the
575          * external tool did not replace the original link with a file.
576          *
577          * These hashes are loaded lazily since they aren't needed
578          * in the common case of --symlinks and the difftool updating
579          * files through the symlink.
580          */
581         hashmap_init(&wt_modified, (hashmap_cmp_fn)path_entry_cmp,
582                      wtindex.cache_nr);
583         hashmap_init(&tmp_modified, (hashmap_cmp_fn)path_entry_cmp,
584                      wtindex.cache_nr);
585
586         for (i = 0; i < wtindex.cache_nr; i++) {
587                 struct hashmap_entry dummy;
588                 const char *name = wtindex.cache[i]->name;
589                 struct stat st;
590
591                 add_path(&rdir, rdir_len, name);
592                 if (lstat(rdir.buf, &st))
593                         continue;
594
595                 if ((symlinks && S_ISLNK(st.st_mode)) || !S_ISREG(st.st_mode))
596                         continue;
597
598                 if (!indices_loaded) {
599                         static struct lock_file lock;
600                         strbuf_reset(&buf);
601                         strbuf_addf(&buf, "%s/wtindex", tmpdir);
602                         if (hold_lock_file_for_update(&lock, buf.buf, 0) < 0 ||
603                             write_locked_index(&wtindex, &lock, COMMIT_LOCK)) {
604                                 ret = error("could not write %s", buf.buf);
605                                 rollback_lock_file(&lock);
606                                 goto finish;
607                         }
608                         changed_files(&wt_modified, buf.buf, workdir);
609                         strbuf_setlen(&rdir, rdir_len);
610                         changed_files(&tmp_modified, buf.buf, rdir.buf);
611                         add_path(&rdir, rdir_len, name);
612                         indices_loaded = 1;
613                 }
614
615                 hashmap_entry_init(&dummy, strhash(name));
616                 if (hashmap_get(&tmp_modified, &dummy, name)) {
617                         add_path(&wtdir, wtdir_len, name);
618                         if (hashmap_get(&wt_modified, &dummy, name)) {
619                                 warning(_("both files modified: '%s' and '%s'."),
620                                         wtdir.buf, rdir.buf);
621                                 warning(_("working tree file has been left."));
622                                 warning("%s", "");
623                                 err = 1;
624                         } else if (unlink(wtdir.buf) ||
625                                    copy_file(wtdir.buf, rdir.buf, st.st_mode))
626                                 warning_errno(_("could not copy '%s' to '%s'"),
627                                               rdir.buf, wtdir.buf);
628                 }
629         }
630
631         if (err) {
632                 warning(_("temporary files exist in '%s'."), tmpdir);
633                 warning(_("you may want to cleanup or recover these."));
634                 exit(1);
635         } else
636                 exit_cleanup(tmpdir, rc);
637
638 finish:
639         if (fp)
640                 fclose(fp);
641
642         free(lbase_dir);
643         free(rbase_dir);
644         strbuf_release(&ldir);
645         strbuf_release(&rdir);
646         strbuf_release(&wtdir);
647         strbuf_release(&buf);
648
649         return ret;
650 }
651
652 static int run_file_diff(int prompt, const char *prefix,
653                          int argc, const char **argv)
654 {
655         struct argv_array args = ARGV_ARRAY_INIT;
656         const char *env[] = {
657                 "GIT_PAGER=", "GIT_EXTERNAL_DIFF=git-difftool--helper", NULL,
658                 NULL
659         };
660         int ret = 0, i;
661
662         if (prompt > 0)
663                 env[2] = "GIT_DIFFTOOL_PROMPT=true";
664         else if (!prompt)
665                 env[2] = "GIT_DIFFTOOL_NO_PROMPT=true";
666
667
668         argv_array_push(&args, "diff");
669         for (i = 0; i < argc; i++)
670                 argv_array_push(&args, argv[i]);
671         ret = run_command_v_opt_cd_env(args.argv, RUN_GIT_CMD, prefix, env);
672         exit(ret);
673 }
674
675 int cmd_difftool(int argc, const char **argv, const char *prefix)
676 {
677         int use_gui_tool = 0, dir_diff = 0, prompt = -1, symlinks = 0,
678             tool_help = 0;
679         static char *difftool_cmd = NULL, *extcmd = NULL;
680         struct option builtin_difftool_options[] = {
681                 OPT_BOOL('g', "gui", &use_gui_tool,
682                          N_("use `diff.guitool` instead of `diff.tool`")),
683                 OPT_BOOL('d', "dir-diff", &dir_diff,
684                          N_("perform a full-directory diff")),
685                 { OPTION_SET_INT, 'y', "no-prompt", &prompt, NULL,
686                         N_("do not prompt before launching a diff tool"),
687                         PARSE_OPT_NOARG | PARSE_OPT_NONEG, NULL, 0},
688                 { OPTION_SET_INT, 0, "prompt", &prompt, NULL, NULL,
689                         PARSE_OPT_NOARG | PARSE_OPT_NONEG | PARSE_OPT_HIDDEN,
690                         NULL, 1 },
691                 OPT_BOOL(0, "symlinks", &symlinks,
692                          N_("use symlinks in dir-diff mode")),
693                 OPT_STRING('t', "tool", &difftool_cmd, N_("<tool>"),
694                            N_("use the specified diff tool")),
695                 OPT_BOOL(0, "tool-help", &tool_help,
696                          N_("print a list of diff tools that may be used with "
697                             "`--tool`")),
698                 OPT_BOOL(0, "trust-exit-code", &trust_exit_code,
699                          N_("make 'git-difftool' exit when an invoked diff "
700                             "tool returns a non - zero exit code")),
701                 OPT_STRING('x', "extcmd", &extcmd, N_("<command>"),
702                            N_("specify a custom command for viewing diffs")),
703                 OPT_END()
704         };
705
706         git_config(difftool_config, NULL);
707         symlinks = has_symlinks;
708
709         argc = parse_options(argc, argv, prefix, builtin_difftool_options,
710                              builtin_difftool_usage, PARSE_OPT_KEEP_UNKNOWN |
711                              PARSE_OPT_KEEP_DASHDASH);
712
713         if (tool_help)
714                 return print_tool_help();
715
716         /* NEEDSWORK: once we no longer spawn anything, remove this */
717         setenv(GIT_DIR_ENVIRONMENT, absolute_path(get_git_dir()), 1);
718         setenv(GIT_WORK_TREE_ENVIRONMENT, absolute_path(get_git_work_tree()), 1);
719
720         if (use_gui_tool && diff_gui_tool && *diff_gui_tool)
721                 setenv("GIT_DIFF_TOOL", diff_gui_tool, 1);
722         else if (difftool_cmd) {
723                 if (*difftool_cmd)
724                         setenv("GIT_DIFF_TOOL", difftool_cmd, 1);
725                 else
726                         die(_("no <tool> given for --tool=<tool>"));
727         }
728
729         if (extcmd) {
730                 if (*extcmd)
731                         setenv("GIT_DIFFTOOL_EXTCMD", extcmd, 1);
732                 else
733                         die(_("no <cmd> given for --extcmd=<cmd>"));
734         }
735
736         setenv("GIT_DIFFTOOL_TRUST_EXIT_CODE",
737                trust_exit_code ? "true" : "false", 1);
738
739         /*
740          * In directory diff mode, 'git-difftool--helper' is called once
741          * to compare the a / b directories. In file diff mode, 'git diff'
742          * will invoke a separate instance of 'git-difftool--helper' for
743          * each file that changed.
744          */
745         if (dir_diff)
746                 return run_dir_diff(extcmd, symlinks, prefix, argc, argv);
747         return run_file_diff(prompt, prefix, argc, argv);
748 }