summaryrefslogtreecommitdiff
path: root/builtin/difftool.c
blob: f2d4d1e0f806d423ac5477a2a93c65d755b8547f (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
/*
 * "git difftool" builtin command
 *
 * This is a wrapper around the GIT_EXTERNAL_DIFF-compatible
 * git-difftool--helper script.
 *
 * This script exports GIT_EXTERNAL_DIFF and GIT_PAGER for use by git.
 * The GIT_DIFF* variables are exported for use by git-difftool--helper.
 *
 * Any arguments that are unknown to this script are forwarded to 'git diff'.
 *
 * Copyright (C) 2016 Johannes Schindelin
 */
#define USE_THE_INDEX_COMPATIBILITY_MACROS
#include "cache.h"
#include "config.h"
#include "builtin.h"
#include "run-command.h"
#include "exec-cmd.h"
#include "parse-options.h"
#include "argv-array.h"
#include "strbuf.h"
#include "lockfile.h"
#include "object-store.h"
#include "dir.h"
 
static int trust_exit_code;
 
static const char *const builtin_difftool_usage[] = {
	N_("git difftool [<options>] [<commit> [<commit>]] [--] [<path>...]"),
	NULL
};
 
static int difftool_config(const char *var, const char *value, void *cb)
{
	if (!strcmp(var, "difftool.trustexitcode")) {
		trust_exit_code = git_config_bool(var, value);
		return 0;
	}
 
	return git_default_config(var, value, cb);
}
 
static int print_tool_help(void)
{
	const char *argv[] = { "mergetool", "--tool-help=diff", NULL };
	return run_command_v_opt(argv, RUN_GIT_CMD);
}
 
static int parse_index_info(char *p, int *mode1, int *mode2,
			    struct object_id *oid1, struct object_id *oid2,
			    char *status)
{
	if (*p != ':')
		return error("expected ':', got '%c'", *p);
	*mode1 = (int)strtol(p + 1, &p, 8);
	if (*p != ' ')
		return error("expected ' ', got '%c'", *p);
	*mode2 = (int)strtol(p + 1, &p, 8);
	if (*p != ' ')
		return error("expected ' ', got '%c'", *p);
	if (parse_oid_hex(++p, oid1, (const char **)&p))
		return error("expected object ID, got '%s'", p);
	if (*p != ' ')
		return error("expected ' ', got '%c'", *p);
	if (parse_oid_hex(++p, oid2, (const char **)&p))
		return error("expected object ID, got '%s'", p);
	if (*p != ' ')
		return error("expected ' ', got '%c'", *p);
	*status = *++p;
	if (!*status)
		return error("missing status");
	if (p[1] && !isdigit(p[1]))
		return error("unexpected trailer: '%s'", p + 1);
	return 0;
}
 
/*
 * Remove any trailing slash from $workdir
 * before starting to avoid double slashes in symlink targets.
 */
static void add_path(struct strbuf *buf, size_t base_len, const char *path)
{
	strbuf_setlen(buf, base_len);
	if (buf->len && buf->buf[buf->len - 1] != '/')
		strbuf_addch(buf, '/');
	strbuf_addstr(buf, path);
}
 
/*
 * Determine whether we can simply reuse the file in the worktree.
 */
static int use_wt_file(const char *workdir, const char *name,
		       struct object_id *oid)
{
	struct strbuf buf = STRBUF_INIT;
	struct stat st;
	int use = 0;
 
	strbuf_addstr(&buf, workdir);
	add_path(&buf, buf.len, name);
 
	if (!lstat(buf.buf, &st) && !S_ISLNK(st.st_mode)) {
		struct object_id wt_oid;
		int fd = open(buf.buf, O_RDONLY);
 
		if (fd >= 0 &&
		    !index_fd(&the_index, &wt_oid, fd, &st, OBJ_BLOB, name, 0)) {
			if (is_null_oid(oid)) {
				oidcpy(oid, &wt_oid);
				use = 1;
			} else if (oideq(oid, &wt_oid))
				use = 1;
		}
	}
 
	strbuf_release(&buf);
 
	return use;
}
 
struct working_tree_entry {
	struct hashmap_entry entry;
	char path[FLEX_ARRAY];
};
 
static int working_tree_entry_cmp(const void *unused_cmp_data,
				  const struct hashmap_entry *eptr,
				  const struct hashmap_entry *entry_or_key,
				  const void *unused_keydata)
{
	const struct working_tree_entry *a, *b;
 
	a = container_of(eptr, const struct working_tree_entry, entry);
	b = container_of(entry_or_key, const struct working_tree_entry, entry);
 
	return strcmp(a->path, b->path);
}
 
/*
 * The `left` and `right` entries hold paths for the symlinks hashmap,
 * and a SHA-1 surrounded by brief text for submodules.
 */
struct pair_entry {
	struct hashmap_entry entry;
	char left[PATH_MAX], right[PATH_MAX];
	const char path[FLEX_ARRAY];
};
 
static int pair_cmp(const void *unused_cmp_data,
		    const struct hashmap_entry *eptr,
		    const struct hashmap_entry *entry_or_key,
		    const void *unused_keydata)
{
	const struct pair_entry *a, *b;
 
	a = container_of(eptr, const struct pair_entry, entry);
	b = container_of(entry_or_key, const struct pair_entry, entry);
 
	return strcmp(a->path, b->path);
}
 
static void add_left_or_right(struct hashmap *map, const char *path,
			      const char *content, int is_right)
{
	struct pair_entry *e, *existing;
 
	FLEX_ALLOC_STR(e, path, path);
	hashmap_entry_init(&e->entry, strhash(path));
	existing = hashmap_get_entry(map, e, NULL, struct pair_entry, entry);
	if (existing) {
		free(e);
		e = existing;
	} else {
		e->left[0] = e->right[0] = '\0';
		hashmap_add(map, &e->entry);
	}
	strlcpy(is_right ? e->right : e->left, content, PATH_MAX);
}
 
struct path_entry {
	struct hashmap_entry entry;
	char path[FLEX_ARRAY];
};
 
static int path_entry_cmp(const void *unused_cmp_data,
			  const struct hashmap_entry *eptr,
			  const struct hashmap_entry *entry_or_key,
			  const void *key)
{
	const struct path_entry *a, *b;
 
	a = container_of(eptr, const struct path_entry, entry);
	b = container_of(entry_or_key, const struct path_entry, entry);
 
	return strcmp(a->path, key ? key : b->path);
}
 
static void changed_files(struct hashmap *result, const char *index_path,
			  const char *workdir)
{
	struct child_process update_index = CHILD_PROCESS_INIT;
	struct child_process diff_files = CHILD_PROCESS_INIT;
	struct strbuf index_env = STRBUF_INIT, buf = STRBUF_INIT;
	const char *git_dir = absolute_path(get_git_dir()), *env[] = {
		NULL, NULL
	};
	FILE *fp;
 
	strbuf_addf(&index_env, "GIT_INDEX_FILE=%s", index_path);
	env[0] = index_env.buf;
 
	argv_array_pushl(&update_index.args,
			 "--git-dir", git_dir, "--work-tree", workdir,
			 "update-index", "--really-refresh", "-q",
			 "--unmerged", NULL);
	update_index.no_stdin = 1;
	update_index.no_stdout = 1;
	update_index.no_stderr = 1;
	update_index.git_cmd = 1;
	update_index.use_shell = 0;
	update_index.clean_on_exit = 1;
	update_index.dir = workdir;
	update_index.env = env;
	/* Ignore any errors of update-index */
	run_command(&update_index);
 
	argv_array_pushl(&diff_files.args,
			 "--git-dir", git_dir, "--work-tree", workdir,
			 "diff-files", "--name-only", "-z", NULL);
	diff_files.no_stdin = 1;
	diff_files.git_cmd = 1;
	diff_files.use_shell = 0;
	diff_files.clean_on_exit = 1;
	diff_files.out = -1;
	diff_files.dir = workdir;
	diff_files.env = env;
	if (start_command(&diff_files))
		die("could not obtain raw diff");
	fp = xfdopen(diff_files.out, "r");
	while (!strbuf_getline_nul(&buf, fp)) {
		struct path_entry *entry;
		FLEX_ALLOC_STR(entry, path, buf.buf);
		hashmap_entry_init(&entry->entry, strhash(buf.buf));
		hashmap_add(result, &entry->entry);
	}
	fclose(fp);
	if (finish_command(&diff_files))
		die("diff-files did not exit properly");
	strbuf_release(&index_env);
	strbuf_release(&buf);
}
 
static NORETURN void exit_cleanup(const char *tmpdir, int exit_code)
{
	struct strbuf buf = STRBUF_INIT;
	strbuf_addstr(&buf, tmpdir);
	remove_dir_recursively(&buf, 0);
	if (exit_code)
		warning(_("failed: %d"), exit_code);
	exit(exit_code);
}
 
static int ensure_leading_directories(char *path)
{
	switch (safe_create_leading_directories(path)) {
		case SCLD_OK:
		case SCLD_EXISTS:
			return 0;
		default:
			return error(_("could not create leading directories "
				       "of '%s'"), path);
	}
}
 
/*
 * Unconditional writing of a plain regular file is what
 * "git difftool --dir-diff" wants to do for symlinks.  We are preparing two
 * temporary directories to be fed to a Git-unaware tool that knows how to
 * show a diff of two directories (e.g. "diff -r A B").
 *
 * Because the tool is Git-unaware, if a symbolic link appears in either of
 * these temporary directories, it will try to dereference and show the
 * difference of the target of the symbolic link, which is not what we want,
 * as the goal of the dir-diff mode is to produce an output that is logically
 * equivalent to what "git diff" produces.
 *
 * Most importantly, we want to get textual comparison of the result of the
 * readlink(2).  get_symlink() provides that---it returns the contents of
 * the symlink that gets written to a regular file to force the external tool
 * to compare the readlink(2) result as text, even on a filesystem that is
 * capable of doing a symbolic link.
 */
static char *get_symlink(const struct object_id *oid, const char *path)
{
	char *data;
	if (is_null_oid(oid)) {
		/* The symlink is unknown to Git so read from the filesystem */
		struct strbuf link = STRBUF_INIT;
		if (has_symlinks) {
			if (strbuf_readlink(&link, path, strlen(path)))
				die(_("could not read symlink %s"), path);
		} else if (strbuf_read_file(&link, path, 128))
			die(_("could not read symlink file %s"), path);
 
		data = strbuf_detach(&link, NULL);
	} else {
		enum object_type type;
		unsigned long size;
		data = read_object_file(oid, &type, &size);
		if (!data)
			die(_("could not read object %s for symlink %s"),
				oid_to_hex(oid), path);
	}
 
	return data;
}
 
static int checkout_path(unsigned mode, struct object_id *oid,
			 const char *path, const struct checkout *state)
{
	struct cache_entry *ce;
	int ret;
 
	ce = make_transient_cache_entry(mode, oid, path, 0);
	ret = checkout_entry(ce, state, NULL, NULL);
 
	discard_cache_entry(ce);
	return ret;
}
 
static int run_dir_diff(const char *extcmd, int symlinks, const char *prefix,
			int argc, const char **argv)
{
	char tmpdir[PATH_MAX];
	struct strbuf info = STRBUF_INIT, lpath = STRBUF_INIT;
	struct strbuf rpath = STRBUF_INIT, buf = STRBUF_INIT;
	struct strbuf ldir = STRBUF_INIT, rdir = STRBUF_INIT;
	struct strbuf wtdir = STRBUF_INIT;
	char *lbase_dir, *rbase_dir;
	size_t ldir_len, rdir_len, wtdir_len;
	const char *workdir, *tmp;
	int ret = 0, i;
	FILE *fp;
	struct hashmap working_tree_dups, submodules, symlinks2;
	struct hashmap_iter iter;
	struct pair_entry *entry;
	struct index_state wtindex;
	struct checkout lstate, rstate;
	int rc, flags = RUN_GIT_CMD, err = 0;
	struct child_process child = CHILD_PROCESS_INIT;
	const char *helper_argv[] = { "difftool--helper", NULL, NULL, NULL };
	struct hashmap wt_modified, tmp_modified;
	int indices_loaded = 0;
 
	workdir = get_git_work_tree();
 
	/* Setup temp directories */
	tmp = getenv("TMPDIR");
	xsnprintf(tmpdir, sizeof(tmpdir), "%s/git-difftool.XXXXXX", tmp ? tmp : "/tmp");
	if (!mkdtemp(tmpdir))
		return error("could not create '%s'", tmpdir);
	strbuf_addf(&ldir, "%s/left/", tmpdir);
	strbuf_addf(&rdir, "%s/right/", tmpdir);
	strbuf_addstr(&wtdir, workdir);
	if (!wtdir.len || !is_dir_sep(wtdir.buf[wtdir.len - 1]))
		strbuf_addch(&wtdir, '/');
	mkdir(ldir.buf, 0700);
	mkdir(rdir.buf, 0700);
 
	memset(&wtindex, 0, sizeof(wtindex));
 
	memset(&lstate, 0, sizeof(lstate));
	lstate.base_dir = lbase_dir = xstrdup(ldir.buf);
	lstate.base_dir_len = ldir.len;
	lstate.force = 1;
	memset(&rstate, 0, sizeof(rstate));
	rstate.base_dir = rbase_dir = xstrdup(rdir.buf);
	rstate.base_dir_len = rdir.len;
	rstate.force = 1;
 
	ldir_len = ldir.len;
	rdir_len = rdir.len;
	wtdir_len = wtdir.len;
 
	hashmap_init(&working_tree_dups, working_tree_entry_cmp, NULL, 0);
	hashmap_init(&submodules, pair_cmp, NULL, 0);
	hashmap_init(&symlinks2, pair_cmp, NULL, 0);
 
	child.no_stdin = 1;
	child.git_cmd = 1;
	child.use_shell = 0;
	child.clean_on_exit = 1;
	child.dir = prefix;
	child.out = -1;
	argv_array_pushl(&child.args, "diff", "--raw", "--no-abbrev", "-z",
			 NULL);
	for (i = 0; i < argc; i++)
		argv_array_push(&child.args, argv[i]);
	if (start_command(&child))
		die("could not obtain raw diff");
	fp = xfdopen(child.out, "r");
 
	/* Build index info for left and right sides of the diff */
	i = 0;
	while (!strbuf_getline_nul(&info, fp)) {
		int lmode, rmode;
		struct object_id loid, roid;
		char status;
		const char *src_path, *dst_path;
 
		if (starts_with(info.buf, "::"))
			die(N_("combined diff formats('-c' and '--cc') are "
			       "not supported in\n"
			       "directory diff mode('-d' and '--dir-diff')."));
 
		if (parse_index_info(info.buf, &lmode, &rmode, &loid, &roid,
				     &status))
			break;
		if (strbuf_getline_nul(&lpath, fp))
			break;
		src_path = lpath.buf;
 
		i++;
		if (status != 'C' && status != 'R') {
			dst_path = src_path;
		} else {
			if (strbuf_getline_nul(&rpath, fp))
				break;
			dst_path = rpath.buf;
		}
 
		if (S_ISGITLINK(lmode) || S_ISGITLINK(rmode)) {
			strbuf_reset(&buf);
			strbuf_addf(&buf, "Subproject commit %s",
				    oid_to_hex(&loid));
			add_left_or_right(&submodules, src_path, buf.buf, 0);
			strbuf_reset(&buf);
			strbuf_addf(&buf, "Subproject commit %s",
				    oid_to_hex(&roid));
			if (oideq(&loid, &roid))
				strbuf_addstr(&buf, "-dirty");
			add_left_or_right(&submodules, dst_path, buf.buf, 1);
			continue;
		}
 
		if (S_ISLNK(lmode)) {
			char *content = get_symlink(&loid, src_path);
			add_left_or_right(&symlinks2, src_path, content, 0);
			free(content);
		}
 
		if (S_ISLNK(rmode)) {
			char *content = get_symlink(&roid, dst_path);
			add_left_or_right(&symlinks2, dst_path, content, 1);
			free(content);
		}
 
		if (lmode && status != 'C') {
			if (checkout_path(lmode, &loid, src_path, &lstate)) {
				ret = error("could not write '%s'", src_path);
				goto finish;
			}
		}
 
		if (rmode && !S_ISLNK(rmode)) {
			struct working_tree_entry *entry;
 
			/* Avoid duplicate working_tree entries */
			FLEX_ALLOC_STR(entry, path, dst_path);
			hashmap_entry_init(&entry->entry, strhash(dst_path));
			if (hashmap_get(&working_tree_dups, &entry->entry,
					NULL)) {
				free(entry);
				continue;
			}
			hashmap_add(&working_tree_dups, &entry->entry);
 
			if (!use_wt_file(workdir, dst_path, &roid)) {
				if (checkout_path(rmode, &roid, dst_path,
						  &rstate)) {
					ret = error("could not write '%s'",
						    dst_path);
					goto finish;
				}
			} else if (!is_null_oid(&roid)) {
				/*
				 * Changes in the working tree need special
				 * treatment since they are not part of the
				 * index.
				 */
				struct cache_entry *ce2 =
					make_cache_entry(&wtindex, rmode, &roid,
							 dst_path, 0, 0);
 
				add_index_entry(&wtindex, ce2,
						ADD_CACHE_JUST_APPEND);
 
				add_path(&rdir, rdir_len, dst_path);
				if (ensure_leading_directories(rdir.buf)) {
					ret = error("could not create "
						    "directory for '%s'",
						    dst_path);
					goto finish;
				}
				add_path(&wtdir, wtdir_len, dst_path);
				if (symlinks) {
					if (symlink(wtdir.buf, rdir.buf)) {
						ret = error_errno("could not symlink '%s' to '%s'", wtdir.buf, rdir.buf);
						goto finish;
					}
				} else {
					struct stat st;
					if (stat(wtdir.buf, &st))
						st.st_mode = 0644;
					if (copy_file(rdir.buf, wtdir.buf,
						      st.st_mode)) {
						ret = error("could not copy '%s' to '%s'", wtdir.buf, rdir.buf);
						goto finish;
					}
				}
			}
		}
	}
 
	fclose(fp);
	fp = NULL;
	if (finish_command(&child)) {
		ret = error("error occurred running diff --raw");
		goto finish;
	}
 
	if (!i)
		goto finish;
 
	/*
	 * Changes to submodules require special treatment.This loop writes a
	 * temporary file to both the left and right directories to show the
	 * change in the recorded SHA1 for the submodule.
	 */
	hashmap_for_each_entry(&submodules, &iter, entry,
				entry /* member name */) {
		if (*entry->left) {
			add_path(&ldir, ldir_len, entry->path);
			ensure_leading_directories(ldir.buf);
			write_file(ldir.buf, "%s", entry->left);
		}
		if (*entry->right) {
			add_path(&rdir, rdir_len, entry->path);
			ensure_leading_directories(rdir.buf);
			write_file(rdir.buf, "%s", entry->right);
		}
	}
 
	/*
	 * Symbolic links require special treatment.The standard "git diff"
	 * shows only the link itself, not the contents of the link target.
	 * This loop replicates that behavior.
	 */
	hashmap_for_each_entry(&symlinks2, &iter, entry,
				entry /* member name */) {
		if (*entry->left) {
			add_path(&ldir, ldir_len, entry->path);
			ensure_leading_directories(ldir.buf);
			write_file(ldir.buf, "%s", entry->left);
		}
		if (*entry->right) {
			add_path(&rdir, rdir_len, entry->path);
			ensure_leading_directories(rdir.buf);
			write_file(rdir.buf, "%s", entry->right);
		}
	}
 
	strbuf_release(&buf);
 
	strbuf_setlen(&ldir, ldir_len);
	helper_argv[1] = ldir.buf;
	strbuf_setlen(&rdir, rdir_len);
	helper_argv[2] = rdir.buf;
 
	if (extcmd) {
		helper_argv[0] = extcmd;
		flags = 0;
	} else
		setenv("GIT_DIFFTOOL_DIRDIFF", "true", 1);
	rc = run_command_v_opt(helper_argv, flags);
 
	/*
	 * If the diff includes working copy files and those
	 * files were modified during the diff, then the changes
	 * should be copied back to the working tree.
	 * Do not copy back files when symlinks are used and the
	 * external tool did not replace the original link with a file.
	 *
	 * These hashes are loaded lazily since they aren't needed
	 * in the common case of --symlinks and the difftool updating
	 * files through the symlink.
	 */
	hashmap_init(&wt_modified, path_entry_cmp, NULL, wtindex.cache_nr);
	hashmap_init(&tmp_modified, path_entry_cmp, NULL, wtindex.cache_nr);
 
	for (i = 0; i < wtindex.cache_nr; i++) {
		struct hashmap_entry dummy;
		const char *name = wtindex.cache[i]->name;
		struct stat st;
 
		add_path(&rdir, rdir_len, name);
		if (lstat(rdir.buf, &st))
			continue;
 
		if ((symlinks && S_ISLNK(st.st_mode)) || !S_ISREG(st.st_mode))
			continue;
 
		if (!indices_loaded) {
			struct lock_file lock = LOCK_INIT;
			strbuf_reset(&buf);
			strbuf_addf(&buf, "%s/wtindex", tmpdir);
			if (hold_lock_file_for_update(&lock, buf.buf, 0) < 0 ||
			    write_locked_index(&wtindex, &lock, COMMIT_LOCK)) {
				ret = error("could not write %s", buf.buf);
				goto finish;
			}
			changed_files(&wt_modified, buf.buf, workdir);
			strbuf_setlen(&rdir, rdir_len);
			changed_files(&tmp_modified, buf.buf, rdir.buf);
			add_path(&rdir, rdir_len, name);
			indices_loaded = 1;
		}
 
		hashmap_entry_init(&dummy, strhash(name));
		if (hashmap_get(&tmp_modified, &dummy, name)) {
			add_path(&wtdir, wtdir_len, name);
			if (hashmap_get(&wt_modified, &dummy, name)) {
				warning(_("both files modified: '%s' and '%s'."),
					wtdir.buf, rdir.buf);
				warning(_("working tree file has been left."));
				warning("%s", "");
				err = 1;
			} else if (unlink(wtdir.buf) ||
				   copy_file(wtdir.buf, rdir.buf, st.st_mode))
				warning_errno(_("could not copy '%s' to '%s'"),
					      rdir.buf, wtdir.buf);
		}
	}
 
	if (err) {
		warning(_("temporary files exist in '%s'."), tmpdir);
		warning(_("you may want to cleanup or recover these."));
		exit(1);
	} else
		exit_cleanup(tmpdir, rc);
 
finish:
	if (fp)
		fclose(fp);
 
	free(lbase_dir);
	free(rbase_dir);
	strbuf_release(&ldir);
	strbuf_release(&rdir);
	strbuf_release(&wtdir);
	strbuf_release(&buf);
 
	return ret;
}
 
static int run_file_diff(int prompt, const char *prefix,
			 int argc, const char **argv)
{
	struct argv_array args = ARGV_ARRAY_INIT;
	const char *env[] = {
		"GIT_PAGER=", "GIT_EXTERNAL_DIFF=git-difftool--helper", NULL,
		NULL
	};
	int ret = 0, i;
 
	if (prompt > 0)
		env[2] = "GIT_DIFFTOOL_PROMPT=true";
	else if (!prompt)
		env[2] = "GIT_DIFFTOOL_NO_PROMPT=true";
 
 
	argv_array_push(&args, "diff");
	for (i = 0; i < argc; i++)
		argv_array_push(&args, argv[i]);
	ret = run_command_v_opt_cd_env(args.argv, RUN_GIT_CMD, prefix, env);
	exit(ret);
}
 
int cmd_difftool(int argc, const char **argv, const char *prefix)
{
	int use_gui_tool = 0, dir_diff = 0, prompt = -1, symlinks = 0,
	    tool_help = 0, no_index = 0;
	static char *difftool_cmd = NULL, *extcmd = NULL;
	struct option builtin_difftool_options[] = {
		OPT_BOOL('g', "gui", &use_gui_tool,
			 N_("use `diff.guitool` instead of `diff.tool`")),
		OPT_BOOL('d', "dir-diff", &dir_diff,
			 N_("perform a full-directory diff")),
		OPT_SET_INT_F('y', "no-prompt", &prompt,
			N_("do not prompt before launching a diff tool"),
			0, PARSE_OPT_NONEG),
		OPT_SET_INT_F(0, "prompt", &prompt, NULL,
			1, PARSE_OPT_NONEG | PARSE_OPT_HIDDEN),
		OPT_BOOL(0, "symlinks", &symlinks,
			 N_("use symlinks in dir-diff mode")),
		OPT_STRING('t', "tool", &difftool_cmd, N_("tool"),
			   N_("use the specified diff tool")),
		OPT_BOOL(0, "tool-help", &tool_help,
			 N_("print a list of diff tools that may be used with "
			    "`--tool`")),
		OPT_BOOL(0, "trust-exit-code", &trust_exit_code,
			 N_("make 'git-difftool' exit when an invoked diff "
			    "tool returns a non - zero exit code")),
		OPT_STRING('x', "extcmd", &extcmd, N_("command"),
			   N_("specify a custom command for viewing diffs")),
		OPT_ARGUMENT("no-index", &no_index, N_("passed to `diff`")),
		OPT_END()
	};
 
	git_config(difftool_config, NULL);
	symlinks = has_symlinks;
 
	argc = parse_options(argc, argv, prefix, builtin_difftool_options,
			     builtin_difftool_usage, PARSE_OPT_KEEP_UNKNOWN |
			     PARSE_OPT_KEEP_DASHDASH);
 
	if (tool_help)
		return print_tool_help();
 
	if (!no_index && !startup_info->have_repository)
		die(_("difftool requires worktree or --no-index"));
 
	if (!no_index){
		setup_work_tree();
		setenv(GIT_DIR_ENVIRONMENT, absolute_path(get_git_dir()), 1);
		setenv(GIT_WORK_TREE_ENVIRONMENT, absolute_path(get_git_work_tree()), 1);
	} else if (dir_diff)
		die(_("--dir-diff is incompatible with --no-index"));
 
	if (use_gui_tool + !!difftool_cmd + !!extcmd > 1)
		die(_("--gui, --tool and --extcmd are mutually exclusive"));
 
	if (use_gui_tool)
		setenv("GIT_MERGETOOL_GUI", "true", 1);
	else if (difftool_cmd) {
		if (*difftool_cmd)
			setenv("GIT_DIFF_TOOL", difftool_cmd, 1);
		else
			die(_("no <tool> given for --tool=<tool>"));
	}
 
	if (extcmd) {
		if (*extcmd)
			setenv("GIT_DIFFTOOL_EXTCMD", extcmd, 1);
		else
			die(_("no <cmd> given for --extcmd=<cmd>"));
	}
 
	setenv("GIT_DIFFTOOL_TRUST_EXIT_CODE",
	       trust_exit_code ? "true" : "false", 1);
 
	/*
	 * In directory diff mode, 'git-difftool--helper' is called once
	 * to compare the a / b directories. In file diff mode, 'git diff'
	 * will invoke a separate instance of 'git-difftool--helper' for
	 * each file that changed.
	 */
	if (dir_diff)
		return run_dir_diff(extcmd, symlinks, prefix, argc, argv);
	return run_file_diff(prompt, prefix, argc, argv);
}