summaryrefslogtreecommitdiff
path: root/setup.c
blob: 3439ec6d815f823ed853251c9afa94d14d78556a (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
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
#include "cache.h"
#include "dir.h"
#include "string-list.h"

static int inside_git_dir = -1;
static int inside_work_tree = -1;
static int work_tree_config_is_bogus;
static struct string_list unknown_extensions = STRING_LIST_INIT_DUP;

static struct startup_info the_startup_info;
struct startup_info *startup_info = &the_startup_info;

/*
 * The input parameter must contain an absolute path, and it must already be
 * normalized.
 *
 * Find the part of an absolute path that lies inside the work tree by
 * dereferencing symlinks outside the work tree, for example:
 * /dir1/repo/dir2/file   (work tree is /dir1/repo)      -> dir2/file
 * /dir/file              (work tree is /)               -> dir/file
 * /dir/symlink1/symlink2 (symlink1 points to work tree) -> symlink2
 * /dir/repolink/file     (repolink points to /dir/repo) -> file
 * /dir/repo              (exactly equal to work tree)   -> (empty string)
 */
static int abspath_part_inside_repo(char *path)
{
	size_t len;
	size_t wtlen;
	char *path0;
	int off;
	const char *work_tree = get_git_work_tree();

	if (!work_tree)
		return -1;
	wtlen = strlen(work_tree);
	len = strlen(path);
	off = offset_1st_component(path);

	/* check if work tree is already the prefix */
	if (wtlen <= len && !strncmp(path, work_tree, wtlen)) {
		if (path[wtlen] == '/') {
			memmove(path, path + wtlen + 1, len - wtlen);
			return 0;
		} else if (path[wtlen - 1] == '/' || path[wtlen] == '\0') {
			/* work tree is the root, or the whole path */
			memmove(path, path + wtlen, len - wtlen + 1);
			return 0;
		}
		/* work tree might match beginning of a symlink to work tree */
		off = wtlen;
	}
	path0 = path;
	path += off;

	/* check each '/'-terminated level */
	while (*path) {
		path++;
		if (*path == '/') {
			*path = '\0';
			if (strcmp(real_path(path0), work_tree) == 0) {
				memmove(path0, path + 1, len - (path - path0));
				return 0;
			}
			*path = '/';
		}
	}

	/* check whole path */
	if (strcmp(real_path(path0), work_tree) == 0) {
		*path0 = '\0';
		return 0;
	}

	return -1;
}

/*
 * Normalize "path", prepending the "prefix" for relative paths. If
 * remaining_prefix is not NULL, return the actual prefix still
 * remains in the path. For example, prefix = sub1/sub2/ and path is
 *
 *  foo          -> sub1/sub2/foo  (full prefix)
 *  ../foo       -> sub1/foo       (remaining prefix is sub1/)
 *  ../../bar    -> bar            (no remaining prefix)
 *  ../../sub1/sub2/foo -> sub1/sub2/foo (but no remaining prefix)
 *  `pwd`/../bar -> sub1/bar       (no remaining prefix)
 */
char *prefix_path_gently(const char *prefix, int len,
			 int *remaining_prefix, const char *path)
{
	const char *orig = path;
	char *sanitized;
	if (is_absolute_path(orig)) {
		sanitized = xmallocz(strlen(path));
		if (remaining_prefix)
			*remaining_prefix = 0;
		if (normalize_path_copy_len(sanitized, path, remaining_prefix)) {
			free(sanitized);
			return NULL;
		}
		if (abspath_part_inside_repo(sanitized)) {
			free(sanitized);
			return NULL;
		}
	} else {
		sanitized = xstrfmt("%.*s%s", len, prefix, path);
		if (remaining_prefix)
			*remaining_prefix = len;
		if (normalize_path_copy_len(sanitized, sanitized, remaining_prefix)) {
			free(sanitized);
			return NULL;
		}
	}
	return sanitized;
}

char *prefix_path(const char *prefix, int len, const char *path)
{
	char *r = prefix_path_gently(prefix, len, NULL, path);
	if (!r)
		die("'%s' is outside repository", path);
	return r;
}

int path_inside_repo(const char *prefix, const char *path)
{
	int len = prefix ? strlen(prefix) : 0;
	char *r = prefix_path_gently(prefix, len, NULL, path);
	if (r) {
		free(r);
		return 1;
	}
	return 0;
}

int check_filename(const char *prefix, const char *arg)
{
	const char *name;
	struct stat st;

	if (starts_with(arg, ":/")) {
		if (arg[2] == '\0') /* ":/" is root dir, always exists */
			return 1;
		name = arg + 2;
	} else if (prefix)
		name = prefix_filename(prefix, strlen(prefix), arg);
	else
		name = arg;
	if (!lstat(name, &st))
		return 1; /* file exists */
	if (errno == ENOENT || errno == ENOTDIR)
		return 0; /* file does not exist */
	die_errno("failed to stat '%s'", arg);
}

static void NORETURN die_verify_filename(const char *prefix,
					 const char *arg,
					 int diagnose_misspelt_rev)
{
	if (!diagnose_misspelt_rev)
		die("%s: no such path in the working tree.\n"
		    "Use 'git <command> -- <path>...' to specify paths that do not exist locally.",
		    arg);
	/*
	 * Saying "'(icase)foo' does not exist in the index" when the
	 * user gave us ":(icase)foo" is just stupid.  A magic pathspec
	 * begins with a colon and is followed by a non-alnum; do not
	 * let maybe_die_on_misspelt_object_name() even trigger.
	 */
	if (!(arg[0] == ':' && !isalnum(arg[1])))
		maybe_die_on_misspelt_object_name(arg, prefix);

	/* ... or fall back the most general message. */
	die("ambiguous argument '%s': unknown revision or path not in the working tree.\n"
	    "Use '--' to separate paths from revisions, like this:\n"
	    "'git <command> [<revision>...] -- [<file>...]'", arg);

}

/*
 * Verify a filename that we got as an argument for a pathspec
 * entry. Note that a filename that begins with "-" never verifies
 * as true, because even if such a filename were to exist, we want
 * it to be preceded by the "--" marker (or we want the user to
 * use a format like "./-filename")
 *
 * The "diagnose_misspelt_rev" is used to provide a user-friendly
 * diagnosis when dying upon finding that "name" is not a pathname.
 * If set to 1, the diagnosis will try to diagnose "name" as an
 * invalid object name (e.g. HEAD:foo). If set to 0, the diagnosis
 * will only complain about an inexisting file.
 *
 * This function is typically called to check that a "file or rev"
 * argument is unambiguous. In this case, the caller will want
 * diagnose_misspelt_rev == 1 when verifying the first non-rev
 * argument (which could have been a revision), and
 * diagnose_misspelt_rev == 0 for the next ones (because we already
 * saw a filename, there's not ambiguity anymore).
 */
void verify_filename(const char *prefix,
		     const char *arg,
		     int diagnose_misspelt_rev)
{
	if (*arg == '-')
		die("bad flag '%s' used after filename", arg);
	if (check_filename(prefix, arg) || !no_wildcard(arg))
		return;
	die_verify_filename(prefix, arg, diagnose_misspelt_rev);
}

/*
 * Opposite of the above: the command line did not have -- marker
 * and we parsed the arg as a refname.  It should not be interpretable
 * as a filename.
 */
void verify_non_filename(const char *prefix, const char *arg)
{
	if (!is_inside_work_tree() || is_inside_git_dir())
		return;
	if (*arg == '-')
		return; /* flag */
	if (!check_filename(prefix, arg))
		return;
	die("ambiguous argument '%s': both revision and filename\n"
	    "Use '--' to separate paths from revisions, like this:\n"
	    "'git <command> [<revision>...] -- [<file>...]'", arg);
}

int get_common_dir(struct strbuf *sb, const char *gitdir)
{
	const char *git_env_common_dir = getenv(GIT_COMMON_DIR_ENVIRONMENT);
	if (git_env_common_dir) {
		strbuf_addstr(sb, git_env_common_dir);
		return 1;
	} else {
		return get_common_dir_noenv(sb, gitdir);
	}
}

int get_common_dir_noenv(struct strbuf *sb, const char *gitdir)
{
	struct strbuf data = STRBUF_INIT;
	struct strbuf path = STRBUF_INIT;
	int ret = 0;

	strbuf_addf(&path, "%s/commondir", gitdir);
	if (file_exists(path.buf)) {
		if (strbuf_read_file(&data, path.buf, 0) <= 0)
			die_errno(_("failed to read %s"), path.buf);
		while (data.len && (data.buf[data.len - 1] == '\n' ||
				    data.buf[data.len - 1] == '\r'))
			data.len--;
		data.buf[data.len] = '\0';
		strbuf_reset(&path);
		if (!is_absolute_path(data.buf))
			strbuf_addf(&path, "%s/", gitdir);
		strbuf_addbuf(&path, &data);
		strbuf_addstr(sb, real_path(path.buf));
		ret = 1;
	} else
		strbuf_addstr(sb, gitdir);
	strbuf_release(&data);
	strbuf_release(&path);
	return ret;
}

/*
 * Test if it looks like we're at a git directory.
 * We want to see:
 *
 *  - either an objects/ directory _or_ the proper
 *    GIT_OBJECT_DIRECTORY environment variable
 *  - a refs/ directory
 *  - either a HEAD symlink or a HEAD file that is formatted as
 *    a proper "ref:", or a regular file HEAD that has a properly
 *    formatted sha1 object name.
 */
int is_git_directory(const char *suspect)
{
	struct strbuf path = STRBUF_INIT;
	int ret = 0;
	size_t len;

	/* Check worktree-related signatures */
	strbuf_addf(&path, "%s/HEAD", suspect);
	if (validate_headref(path.buf))
		goto done;

	strbuf_reset(&path);
	get_common_dir(&path, suspect);
	len = path.len;

	/* Check non-worktree-related signatures */
	if (getenv(DB_ENVIRONMENT)) {
		if (access(getenv(DB_ENVIRONMENT), X_OK))
			goto done;
	}
	else {
		strbuf_setlen(&path, len);
		strbuf_addstr(&path, "/objects");
		if (access(path.buf, X_OK))
			goto done;
	}

	strbuf_setlen(&path, len);
	strbuf_addstr(&path, "/refs");
	if (access(path.buf, X_OK))
		goto done;

	ret = 1;
done:
	strbuf_release(&path);
	return ret;
}

int is_nonbare_repository_dir(struct strbuf *path)
{
	int ret = 0;
	int gitfile_error;
	size_t orig_path_len = path->len;
	assert(orig_path_len != 0);
	strbuf_complete(path, '/');
	strbuf_addstr(path, ".git");
	if (read_gitfile_gently(path->buf, &gitfile_error) || is_git_directory(path->buf))
		ret = 1;
	if (gitfile_error == READ_GITFILE_ERR_OPEN_FAILED ||
	    gitfile_error == READ_GITFILE_ERR_READ_FAILED)
		ret = 1;
	strbuf_setlen(path, orig_path_len);
	return ret;
}

int is_inside_git_dir(void)
{
	if (inside_git_dir < 0)
		inside_git_dir = is_inside_dir(get_git_dir());
	return inside_git_dir;
}

int is_inside_work_tree(void)
{
	if (inside_work_tree < 0)
		inside_work_tree = is_inside_dir(get_git_work_tree());
	return inside_work_tree;
}

void setup_work_tree(void)
{
	const char *work_tree, *git_dir;
	static int initialized = 0;

	if (initialized)
		return;

	if (work_tree_config_is_bogus)
		die("unable to set up work tree using invalid config");

	work_tree = get_git_work_tree();
	git_dir = get_git_dir();
	if (!is_absolute_path(git_dir))
		git_dir = real_path(get_git_dir());
	if (!work_tree || chdir(work_tree))
		die("This operation must be run in a work tree");

	/*
	 * Make sure subsequent git processes find correct worktree
	 * if $GIT_WORK_TREE is set relative
	 */
	if (getenv(GIT_WORK_TREE_ENVIRONMENT))
		setenv(GIT_WORK_TREE_ENVIRONMENT, ".", 1);

	set_git_dir(remove_leading_path(git_dir, work_tree));
	initialized = 1;
}

static int check_repo_format(const char *var, const char *value, void *cb)
{
	const char *ext;

	if (strcmp(var, "core.repositoryformatversion") == 0)
		repository_format_version = git_config_int(var, value);
	else if (strcmp(var, "core.sharedrepository") == 0)
		shared_repository = git_config_perm(var, value);
	else if (skip_prefix(var, "extensions.", &ext)) {
		/*
		 * record any known extensions here; otherwise,
		 * we fall through to recording it as unknown, and
		 * check_repository_format will complain
		 */
		if (!strcmp(ext, "noop"))
			;
		else if (!strcmp(ext, "preciousobjects"))
			repository_format_precious_objects = git_config_bool(var, value);
		else
			string_list_append(&unknown_extensions, ext);
	}
	return 0;
}

static int check_repository_format_gently(const char *gitdir, int *nongit_ok)
{
	struct strbuf sb = STRBUF_INIT;
	const char *repo_config;
	config_fn_t fn;
	int ret = 0;

	string_list_clear(&unknown_extensions, 0);

	if (get_common_dir(&sb, gitdir))
		fn = check_repo_format;
	else
		fn = check_repository_format_version;
	strbuf_addstr(&sb, "/config");
	repo_config = sb.buf;

	/*
	 * git_config() can't be used here because it calls git_pathdup()
	 * to get $GIT_CONFIG/config. That call will make setup_git_env()
	 * set git_dir to ".git".
	 *
	 * We are in gitdir setup, no git dir has been found useable yet.
	 * Use a gentler version of git_config() to check if this repo
	 * is a good one.
	 */
	git_config_early(fn, NULL, repo_config);
	if (GIT_REPO_VERSION_READ < repository_format_version) {
		if (!nongit_ok)
			die ("Expected git repo version <= %d, found %d",
			     GIT_REPO_VERSION_READ, repository_format_version);
		warning("Expected git repo version <= %d, found %d",
			GIT_REPO_VERSION_READ, repository_format_version);
		warning("Please upgrade Git");
		*nongit_ok = -1;
		ret = -1;
	}

	if (repository_format_version >= 1 && unknown_extensions.nr) {
		int i;

		if (!nongit_ok)
			die("unknown repository extension: %s",
			    unknown_extensions.items[0].string);

		for (i = 0; i < unknown_extensions.nr; i++)
			warning("unknown repository extension: %s",
				unknown_extensions.items[i].string);
		*nongit_ok = -1;
		ret = -1;
	}

	strbuf_release(&sb);
	return ret;
}

/*
 * Try to read the location of the git directory from the .git file,
 * return path to git directory if found.
 *
 * On failure, if return_error_code is not NULL, return_error_code
 * will be set to an error code and NULL will be returned. If
 * return_error_code is NULL the function will die instead (for most
 * cases).
 */
const char *read_gitfile_gently(const char *path, int *return_error_code)
{
	const int max_file_size = 1 << 20;  /* 1MB */
	int error_code = 0;
	char *buf = NULL;
	char *dir = NULL;
	const char *slash;
	struct stat st;
	int fd;
	ssize_t len;

	if (stat(path, &st)) {
		error_code = READ_GITFILE_ERR_STAT_FAILED;
		goto cleanup_return;
	}
	if (!S_ISREG(st.st_mode)) {
		error_code = READ_GITFILE_ERR_NOT_A_FILE;
		goto cleanup_return;
	}
	if (st.st_size > max_file_size) {
		error_code = READ_GITFILE_ERR_TOO_LARGE;
		goto cleanup_return;
	}
	fd = open(path, O_RDONLY);
	if (fd < 0) {
		error_code = READ_GITFILE_ERR_OPEN_FAILED;
		goto cleanup_return;
	}
	buf = xmallocz(st.st_size);
	len = read_in_full(fd, buf, st.st_size);
	close(fd);
	if (len != st.st_size) {
		error_code = READ_GITFILE_ERR_READ_FAILED;
		goto cleanup_return;
	}
	if (!starts_with(buf, "gitdir: ")) {
		error_code = READ_GITFILE_ERR_INVALID_FORMAT;
		goto cleanup_return;
	}
	while (buf[len - 1] == '\n' || buf[len - 1] == '\r')
		len--;
	if (len < 9) {
		error_code = READ_GITFILE_ERR_NO_PATH;
		goto cleanup_return;
	}
	buf[len] = '\0';
	dir = buf + 8;

	if (!is_absolute_path(dir) && (slash = strrchr(path, '/'))) {
		size_t pathlen = slash+1 - path;
		dir = xstrfmt("%.*s%.*s", (int)pathlen, path,
			      (int)(len - 8), buf + 8);
		free(buf);
		buf = dir;
	}
	if (!is_git_directory(dir)) {
		error_code = READ_GITFILE_ERR_NOT_A_REPO;
		goto cleanup_return;
	}
	path = real_path(dir);

cleanup_return:
	if (return_error_code)
		*return_error_code = error_code;
	else if (error_code) {
		switch (error_code) {
		case READ_GITFILE_ERR_STAT_FAILED:
		case READ_GITFILE_ERR_NOT_A_FILE:
			/* non-fatal; follow return path */
			break;
		case READ_GITFILE_ERR_OPEN_FAILED:
			die_errno("Error opening '%s'", path);
		case READ_GITFILE_ERR_TOO_LARGE:
			die("Too large to be a .git file: '%s'", path);
		case READ_GITFILE_ERR_READ_FAILED:
			die("Error reading %s", path);
		case READ_GITFILE_ERR_INVALID_FORMAT:
			die("Invalid gitfile format: %s", path);
		case READ_GITFILE_ERR_NO_PATH:
			die("No path in gitfile: %s", path);
		case READ_GITFILE_ERR_NOT_A_REPO:
			die("Not a git repository: %s", dir);
		default:
			assert(0);
		}
	}

	free(buf);
	return error_code ? NULL : path;
}

static const char *setup_explicit_git_dir(const char *gitdirenv,
					  struct strbuf *cwd,
					  int *nongit_ok)
{
	const char *work_tree_env = getenv(GIT_WORK_TREE_ENVIRONMENT);
	const char *worktree;
	char *gitfile;
	int offset;

	if (PATH_MAX - 40 < strlen(gitdirenv))
		die("'$%s' too big", GIT_DIR_ENVIRONMENT);

	gitfile = (char*)read_gitfile(gitdirenv);
	if (gitfile) {
		gitfile = xstrdup(gitfile);
		gitdirenv = gitfile;
	}

	if (!is_git_directory(gitdirenv)) {
		if (nongit_ok) {
			*nongit_ok = 1;
			free(gitfile);
			return NULL;
		}
		die("Not a git repository: '%s'", gitdirenv);
	}

	if (check_repository_format_gently(gitdirenv, nongit_ok)) {
		free(gitfile);
		return NULL;
	}

	/* #3, #7, #11, #15, #19, #23, #27, #31 (see t1510) */
	if (work_tree_env)
		set_git_work_tree(work_tree_env);
	else if (is_bare_repository_cfg > 0) {
		if (git_work_tree_cfg) {
			/* #22.2, #30 */
			warning("core.bare and core.worktree do not make sense");
			work_tree_config_is_bogus = 1;
		}

		/* #18, #26 */
		set_git_dir(gitdirenv);
		free(gitfile);
		return NULL;
	}
	else if (git_work_tree_cfg) { /* #6, #14 */
		if (is_absolute_path(git_work_tree_cfg))
			set_git_work_tree(git_work_tree_cfg);
		else {
			char *core_worktree;
			if (chdir(gitdirenv))
				die_errno("Could not chdir to '%s'", gitdirenv);
			if (chdir(git_work_tree_cfg))
				die_errno("Could not chdir to '%s'", git_work_tree_cfg);
			core_worktree = xgetcwd();
			if (chdir(cwd->buf))
				die_errno("Could not come back to cwd");
			set_git_work_tree(core_worktree);
			free(core_worktree);
		}
	}
	else if (!git_env_bool(GIT_IMPLICIT_WORK_TREE_ENVIRONMENT, 1)) {
		/* #16d */
		set_git_dir(gitdirenv);
		free(gitfile);
		return NULL;
	}
	else /* #2, #10 */
		set_git_work_tree(".");

	/* set_git_work_tree() must have been called by now */
	worktree = get_git_work_tree();

	/* both get_git_work_tree() and cwd are already normalized */
	if (!strcmp(cwd->buf, worktree)) { /* cwd == worktree */
		set_git_dir(gitdirenv);
		free(gitfile);
		return NULL;
	}

	offset = dir_inside_of(cwd->buf, worktree);
	if (offset >= 0) {	/* cwd inside worktree? */
		set_git_dir(real_path(gitdirenv));
		if (chdir(worktree))
			die_errno("Could not chdir to '%s'", worktree);
		strbuf_addch(cwd, '/');
		free(gitfile);
		return cwd->buf + offset;
	}

	/* cwd outside worktree */
	set_git_dir(gitdirenv);
	free(gitfile);
	return NULL;
}

static const char *setup_discovered_git_dir(const char *gitdir,
					    struct strbuf *cwd, int offset,
					    int *nongit_ok)
{
	if (check_repository_format_gently(gitdir, nongit_ok))
		return NULL;

	/* --work-tree is set without --git-dir; use discovered one */
	if (getenv(GIT_WORK_TREE_ENVIRONMENT) || git_work_tree_cfg) {
		if (offset != cwd->len && !is_absolute_path(gitdir))
			gitdir = xstrdup(real_path(gitdir));
		if (chdir(cwd->buf))
			die_errno("Could not come back to cwd");
		return setup_explicit_git_dir(gitdir, cwd, nongit_ok);
	}

	/* #16.2, #17.2, #20.2, #21.2, #24, #25, #28, #29 (see t1510) */
	if (is_bare_repository_cfg > 0) {
		set_git_dir(offset == cwd->len ? gitdir : real_path(gitdir));
		if (chdir(cwd->buf))
			die_errno("Could not come back to cwd");
		return NULL;
	}

	/* #0, #1, #5, #8, #9, #12, #13 */
	set_git_work_tree(".");
	if (strcmp(gitdir, DEFAULT_GIT_DIR_ENVIRONMENT))
		set_git_dir(gitdir);
	inside_git_dir = 0;
	inside_work_tree = 1;
	if (offset == cwd->len)
		return NULL;

	/* Make "offset" point to past the '/', and add a '/' at the end */
	offset++;
	strbuf_addch(cwd, '/');
	return cwd->buf + offset;
}

/* #16.1, #17.1, #20.1, #21.1, #22.1 (see t1510) */
static const char *setup_bare_git_dir(struct strbuf *cwd, int offset,
				      int *nongit_ok)
{
	int root_len;

	if (check_repository_format_gently(".", nongit_ok))
		return NULL;

	setenv(GIT_IMPLICIT_WORK_TREE_ENVIRONMENT, "0", 1);

	/* --work-tree is set without --git-dir; use discovered one */
	if (getenv(GIT_WORK_TREE_ENVIRONMENT) || git_work_tree_cfg) {
		const char *gitdir;

		gitdir = offset == cwd->len ? "." : xmemdupz(cwd->buf, offset);
		if (chdir(cwd->buf))
			die_errno("Could not come back to cwd");
		return setup_explicit_git_dir(gitdir, cwd, nongit_ok);
	}

	inside_git_dir = 1;
	inside_work_tree = 0;
	if (offset != cwd->len) {
		if (chdir(cwd->buf))
			die_errno("Cannot come back to cwd");
		root_len = offset_1st_component(cwd->buf);
		strbuf_setlen(cwd, offset > root_len ? offset : root_len);
		set_git_dir(cwd->buf);
	}
	else
		set_git_dir(".");
	return NULL;
}

static const char *setup_nongit(const char *cwd, int *nongit_ok)
{
	if (!nongit_ok)
		die("Not a git repository (or any of the parent directories): %s", DEFAULT_GIT_DIR_ENVIRONMENT);
	if (chdir(cwd))
		die_errno("Cannot come back to cwd");
	*nongit_ok = 1;
	return NULL;
}

static dev_t get_device_or_die(const char *path, const char *prefix, int prefix_len)
{
	struct stat buf;
	if (stat(path, &buf)) {
		die_errno("failed to stat '%*s%s%s'",
				prefix_len,
				prefix ? prefix : "",
				prefix ? "/" : "", path);
	}
	return buf.st_dev;
}

/*
 * A "string_list_each_func_t" function that canonicalizes an entry
 * from GIT_CEILING_DIRECTORIES using real_path_if_valid(), or
 * discards it if unusable.  The presence of an empty entry in
 * GIT_CEILING_DIRECTORIES turns off canonicalization for all
 * subsequent entries.
 */
static int canonicalize_ceiling_entry(struct string_list_item *item,
				      void *cb_data)
{
	int *empty_entry_found = cb_data;
	char *ceil = item->string;

	if (!*ceil) {
		*empty_entry_found = 1;
		return 0;
	} else if (!is_absolute_path(ceil)) {
		return 0;
	} else if (*empty_entry_found) {
		/* Keep entry but do not canonicalize it */
		return 1;
	} else {
		const char *real_path = real_path_if_valid(ceil);
		if (!real_path)
			return 0;
		free(item->string);
		item->string = xstrdup(real_path);
		return 1;
	}
}

/*
 * We cannot decide in this function whether we are in the work tree or
 * not, since the config can only be read _after_ this function was called.
 */
static const char *setup_git_directory_gently_1(int *nongit_ok)
{
	const char *env_ceiling_dirs = getenv(CEILING_DIRECTORIES_ENVIRONMENT);
	struct string_list ceiling_dirs = STRING_LIST_INIT_DUP;
	static struct strbuf cwd = STRBUF_INIT;
	const char *gitdirenv, *ret;
	char *gitfile;
	int offset, offset_parent, ceil_offset = -1;
	dev_t current_device = 0;
	int one_filesystem = 1;

	/*
	 * We may have read an incomplete configuration before
	 * setting-up the git directory. If so, clear the cache so
	 * that the next queries to the configuration reload complete
	 * configuration (including the per-repo config file that we
	 * ignored previously).
	 */
	git_config_clear();

	/*
	 * Let's assume that we are in a git repository.
	 * If it turns out later that we are somewhere else, the value will be
	 * updated accordingly.
	 */
	if (nongit_ok)
		*nongit_ok = 0;

	if (strbuf_getcwd(&cwd))
		die_errno("Unable to read current working directory");
	offset = cwd.len;

	/*
	 * If GIT_DIR is set explicitly, we're not going
	 * to do any discovery, but we still do repository
	 * validation.
	 */
	gitdirenv = getenv(GIT_DIR_ENVIRONMENT);
	if (gitdirenv)
		return setup_explicit_git_dir(gitdirenv, &cwd, nongit_ok);

	if (env_ceiling_dirs) {
		int empty_entry_found = 0;

		string_list_split(&ceiling_dirs, env_ceiling_dirs, PATH_SEP, -1);
		filter_string_list(&ceiling_dirs, 0,
				   canonicalize_ceiling_entry, &empty_entry_found);
		ceil_offset = longest_ancestor_length(cwd.buf, &ceiling_dirs);
		string_list_clear(&ceiling_dirs, 0);
	}

	if (ceil_offset < 0 && has_dos_drive_prefix(cwd.buf))
		ceil_offset = 1;

	/*
	 * Test in the following order (relative to the cwd):
	 * - .git (file containing "gitdir: <path>")
	 * - .git/
	 * - ./ (bare)
	 * - ../.git
	 * - ../.git/
	 * - ../ (bare)
	 * - ../../.git/
	 *   etc.
	 */
	one_filesystem = !git_env_bool("GIT_DISCOVERY_ACROSS_FILESYSTEM", 0);
	if (one_filesystem)
		current_device = get_device_or_die(".", NULL, 0);
	for (;;) {
		gitfile = (char*)read_gitfile(DEFAULT_GIT_DIR_ENVIRONMENT);
		if (gitfile)
			gitdirenv = gitfile = xstrdup(gitfile);
		else {
			if (is_git_directory(DEFAULT_GIT_DIR_ENVIRONMENT))
				gitdirenv = DEFAULT_GIT_DIR_ENVIRONMENT;
		}

		if (gitdirenv) {
			ret = setup_discovered_git_dir(gitdirenv,
						       &cwd, offset,
						       nongit_ok);
			free(gitfile);
			return ret;
		}
		free(gitfile);

		if (is_git_directory("."))
			return setup_bare_git_dir(&cwd, offset, nongit_ok);

		offset_parent = offset;
		while (--offset_parent > ceil_offset && cwd.buf[offset_parent] != '/');
		if (offset_parent <= ceil_offset)
			return setup_nongit(cwd.buf, nongit_ok);
		if (one_filesystem) {
			dev_t parent_device = get_device_or_die("..", cwd.buf,
								offset);
			if (parent_device != current_device) {
				if (nongit_ok) {
					if (chdir(cwd.buf))
						die_errno("Cannot come back to cwd");
					*nongit_ok = 1;
					return NULL;
				}
				strbuf_setlen(&cwd, offset);
				die("Not a git repository (or any parent up to mount point %s)\n"
				"Stopping at filesystem boundary (GIT_DISCOVERY_ACROSS_FILESYSTEM not set).",
				    cwd.buf);
			}
		}
		if (chdir("..")) {
			strbuf_setlen(&cwd, offset);
			die_errno("Cannot change to '%s/..'", cwd.buf);
		}
		offset = offset_parent;
	}
}

const char *setup_git_directory_gently(int *nongit_ok)
{
	const char *prefix;

	prefix = setup_git_directory_gently_1(nongit_ok);
	if (prefix)
		setenv(GIT_PREFIX_ENVIRONMENT, prefix, 1);
	else
		setenv(GIT_PREFIX_ENVIRONMENT, "", 1);

	startup_info->have_repository = !nongit_ok || !*nongit_ok;
	startup_info->prefix = prefix;

	return prefix;
}

int git_config_perm(const char *var, const char *value)
{
	int i;
	char *endptr;

	if (value == NULL)
		return PERM_GROUP;

	if (!strcmp(value, "umask"))
		return PERM_UMASK;
	if (!strcmp(value, "group"))
		return PERM_GROUP;
	if (!strcmp(value, "all") ||
	    !strcmp(value, "world") ||
	    !strcmp(value, "everybody"))
		return PERM_EVERYBODY;

	/* Parse octal numbers */
	i = strtol(value, &endptr, 8);

	/* If not an octal number, maybe true/false? */
	if (*endptr != 0)
		return git_config_bool(var, value) ? PERM_GROUP : PERM_UMASK;

	/*
	 * Treat values 0, 1 and 2 as compatibility cases, otherwise it is
	 * a chmod value to restrict to.
	 */
	switch (i) {
	case PERM_UMASK:               /* 0 */
		return PERM_UMASK;
	case OLD_PERM_GROUP:           /* 1 */
		return PERM_GROUP;
	case OLD_PERM_EVERYBODY:       /* 2 */
		return PERM_EVERYBODY;
	}

	/* A filemode value was given: 0xxx */

	if ((i & 0600) != 0600)
		die("Problem with core.sharedRepository filemode value "
		    "(0%.3o).\nThe owner of files must always have "
		    "read and write permissions.", i);

	/*
	 * Mask filemode value. Others can not get write permission.
	 * x flags for directories are handled separately.
	 */
	return -(i & 0666);
}

int check_repository_format_version(const char *var, const char *value, void *cb)
{
	int ret = check_repo_format(var, value, cb);
	if (ret)
		return ret;
	if (strcmp(var, "core.bare") == 0) {
		is_bare_repository_cfg = git_config_bool(var, value);
		if (is_bare_repository_cfg == 1)
			inside_work_tree = -1;
	} else if (strcmp(var, "core.worktree") == 0) {
		if (!value)
			return config_error_nonbool(var);
		free(git_work_tree_cfg);
		git_work_tree_cfg = xstrdup(value);
		inside_work_tree = -1;
	}
	return 0;
}

int check_repository_format(void)
{
	check_repository_format_gently(get_git_dir(), NULL);
	startup_info->have_repository = 1;
	return 0;
}

/*
 * Returns the "prefix", a path to the current working directory
 * relative to the work tree root, or NULL, if the current working
 * directory is not a strict subdirectory of the work tree root. The
 * prefix always ends with a '/' character.
 */
const char *setup_git_directory(void)
{
	return setup_git_directory_gently(NULL);
}

const char *resolve_gitdir(const char *suspect)
{
	if (is_git_directory(suspect))
		return suspect;
	return read_gitfile(suspect);
}

/* if any standard file descriptor is missing open it to /dev/null */
void sanitize_stdfds(void)
{
	int fd = open("/dev/null", O_RDWR, 0);
	while (fd != -1 && fd < 2)
		fd = dup(fd);
	if (fd == -1)
		die_errno("open /dev/null or dup failed");
	if (fd > 2)
		close(fd);
}

int daemonize(void)
{
#ifdef NO_POSIX_GOODIES
	errno = ENOSYS;
	return -1;
#else
	switch (fork()) {
		case 0:
			break;
		case -1:
			die_errno("fork failed");
		default:
			exit(0);
	}
	if (setsid() == -1)
		die_errno("setsid failed");
	close(0);
	close(1);
	close(2);
	sanitize_stdfds();
	return 0;
#endif
}