aboutsummaryrefslogtreecommitdiff
path: root/tree-walk.c
blob: ce278424391b03d1d4e41eb3fc14750f70908fe5 (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
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
#include "cache.h"
#include "tree-walk.h"
#include "unpack-trees.h"
#include "dir.h"
#include "tree.h"
#include "pathspec.h"

static const char *get_mode(const char *str, unsigned int *modep)
{
	unsigned char c;
	unsigned int mode = 0;

	if (*str == ' ')
		return NULL;

	while ((c = *str++) != ' ') {
		if (c < '0' || c > '7')
			return NULL;
		mode = (mode << 3) + (c - '0');
	}
	*modep = mode;
	return str;
}

static void decode_tree_entry(struct tree_desc *desc, const char *buf, unsigned long size)
{
	const char *path;
	unsigned int mode, len;

	if (size < 24 || buf[size - 21])
		die("corrupt tree file");

	path = get_mode(buf, &mode);
	if (!path || !*path)
		die("corrupt tree file");
	len = strlen(path) + 1;

	/* Initialize the descriptor entry */
	desc->entry.path = path;
	desc->entry.mode = canon_mode(mode);
	desc->entry.oid  = (const struct object_id *)(path + len);
}

void init_tree_desc(struct tree_desc *desc, const void *buffer, unsigned long size)
{
	desc->buffer = buffer;
	desc->size = size;
	if (size)
		decode_tree_entry(desc, buffer, size);
}

void *fill_tree_descriptor(struct tree_desc *desc, const unsigned char *sha1)
{
	unsigned long size = 0;
	void *buf = NULL;

	if (sha1) {
		buf = read_object_with_reference(sha1, tree_type, &size, NULL);
		if (!buf)
			die("unable to read tree %s", sha1_to_hex(sha1));
	}
	init_tree_desc(desc, buf, size);
	return buf;
}

static void entry_clear(struct name_entry *a)
{
	memset(a, 0, sizeof(*a));
}

static void entry_extract(struct tree_desc *t, struct name_entry *a)
{
	*a = t->entry;
}

void update_tree_entry(struct tree_desc *desc)
{
	const void *buf = desc->buffer;
	const unsigned char *end = desc->entry.oid->hash + 20;
	unsigned long size = desc->size;
	unsigned long len = end - (const unsigned char *)buf;

	if (size < len)
		die("corrupt tree file");
	buf = end;
	size -= len;
	desc->buffer = buf;
	desc->size = size;
	if (size)
		decode_tree_entry(desc, buf, size);
}

int tree_entry(struct tree_desc *desc, struct name_entry *entry)
{
	if (!desc->size)
		return 0;

	*entry = desc->entry;
	update_tree_entry(desc);
	return 1;
}

void setup_traverse_info(struct traverse_info *info, const char *base)
{
	int pathlen = strlen(base);
	static struct traverse_info dummy;

	memset(info, 0, sizeof(*info));
	if (pathlen && base[pathlen-1] == '/')
		pathlen--;
	info->pathlen = pathlen ? pathlen + 1 : 0;
	info->name.path = base;
	info->name.oid = (void *)(base + pathlen + 1);
	if (pathlen)
		info->prev = &dummy;
}

char *make_traverse_path(char *path, const struct traverse_info *info, const struct name_entry *n)
{
	int len = tree_entry_len(n);
	int pathlen = info->pathlen;

	path[pathlen + len] = 0;
	for (;;) {
		memcpy(path + pathlen, n->path, len);
		if (!pathlen)
			break;
		path[--pathlen] = '/';
		n = &info->name;
		len = tree_entry_len(n);
		info = info->prev;
		pathlen -= len;
	}
	return path;
}

struct tree_desc_skip {
	struct tree_desc_skip *prev;
	const void *ptr;
};

struct tree_desc_x {
	struct tree_desc d;
	struct tree_desc_skip *skip;
};

static int check_entry_match(const char *a, int a_len, const char *b, int b_len)
{
	/*
	 * The caller wants to pick *a* from a tree or nothing.
	 * We are looking at *b* in a tree.
	 *
	 * (0) If a and b are the same name, we are trivially happy.
	 *
	 * There are three possibilities where *a* could be hiding
	 * behind *b*.
	 *
	 * (1) *a* == "t",   *b* == "ab"  i.e. *b* sorts earlier than *a* no
	 *                                matter what.
	 * (2) *a* == "t",   *b* == "t-2" and "t" is a subtree in the tree;
	 * (3) *a* == "t-2", *b* == "t"   and "t-2" is a blob in the tree.
	 *
	 * Otherwise we know *a* won't appear in the tree without
	 * scanning further.
	 */

	int cmp = name_compare(a, a_len, b, b_len);

	/* Most common case first -- reading sync'd trees */
	if (!cmp)
		return cmp;

	if (0 < cmp) {
		/* a comes after b; it does not matter if it is case (3)
		if (b_len < a_len && !memcmp(a, b, b_len) && a[b_len] < '/')
			return 1;
		*/
		return 1; /* keep looking */
	}

	/* b comes after a; are we looking at case (2)? */
	if (a_len < b_len && !memcmp(a, b, a_len) && b[a_len] < '/')
		return 1; /* keep looking */

	return -1; /* a cannot appear in the tree */
}

/*
 * From the extended tree_desc, extract the first name entry, while
 * paying attention to the candidate "first" name.  Most importantly,
 * when looking for an entry, if there are entries that sorts earlier
 * in the tree object representation than that name, skip them and
 * process the named entry first.  We will remember that we haven't
 * processed the first entry yet, and in the later call skip the
 * entry we processed early when update_extended_entry() is called.
 *
 * E.g. if the underlying tree object has these entries:
 *
 *    blob    "t-1"
 *    blob    "t-2"
 *    tree    "t"
 *    blob    "t=1"
 *
 * and the "first" asks for "t", remember that we still need to
 * process "t-1" and "t-2" but extract "t".  After processing the
 * entry "t" from this call, the caller will let us know by calling
 * update_extended_entry() that we can remember "t" has been processed
 * already.
 */

static void extended_entry_extract(struct tree_desc_x *t,
				   struct name_entry *a,
				   const char *first,
				   int first_len)
{
	const char *path;
	int len;
	struct tree_desc probe;
	struct tree_desc_skip *skip;

	/*
	 * Extract the first entry from the tree_desc, but skip the
	 * ones that we already returned in earlier rounds.
	 */
	while (1) {
		if (!t->d.size) {
			entry_clear(a);
			break; /* not found */
		}
		entry_extract(&t->d, a);
		for (skip = t->skip; skip; skip = skip->prev)
			if (a->path == skip->ptr)
				break; /* found */
		if (!skip)
			break;
		/* We have processed this entry already. */
		update_tree_entry(&t->d);
	}

	if (!first || !a->path)
		return;

	/*
	 * The caller wants "first" from this tree, or nothing.
	 */
	path = a->path;
	len = tree_entry_len(a);
	switch (check_entry_match(first, first_len, path, len)) {
	case -1:
		entry_clear(a);
	case 0:
		return;
	default:
		break;
	}

	/*
	 * We need to look-ahead -- we suspect that a subtree whose
	 * name is "first" may be hiding behind the current entry "path".
	 */
	probe = t->d;
	while (probe.size) {
		entry_extract(&probe, a);
		path = a->path;
		len = tree_entry_len(a);
		switch (check_entry_match(first, first_len, path, len)) {
		case -1:
			entry_clear(a);
		case 0:
			return;
		default:
			update_tree_entry(&probe);
			break;
		}
		/* keep looking */
	}
	entry_clear(a);
}

static void update_extended_entry(struct tree_desc_x *t, struct name_entry *a)
{
	if (t->d.entry.path == a->path) {
		update_tree_entry(&t->d);
	} else {
		/* we have returned this entry early */
		struct tree_desc_skip *skip = xmalloc(sizeof(*skip));
		skip->ptr = a->path;
		skip->prev = t->skip;
		t->skip = skip;
	}
}

static void free_extended_entry(struct tree_desc_x *t)
{
	struct tree_desc_skip *p, *s;

	for (s = t->skip; s; s = p) {
		p = s->prev;
		free(s);
	}
}

static inline int prune_traversal(struct name_entry *e,
				  struct traverse_info *info,
				  struct strbuf *base,
				  int still_interesting)
{
	if (!info->pathspec || still_interesting == 2)
		return 2;
	if (still_interesting < 0)
		return still_interesting;
	return tree_entry_interesting(e, base, 0, info->pathspec);
}

int traverse_trees(int n, struct tree_desc *t, struct traverse_info *info)
{
	int error = 0;
	struct name_entry *entry = xmalloc(n*sizeof(*entry));
	int i;
	struct tree_desc_x *tx = xcalloc(n, sizeof(*tx));
	struct strbuf base = STRBUF_INIT;
	int interesting = 1;
	char *traverse_path;

	for (i = 0; i < n; i++)
		tx[i].d = t[i];

	if (info->prev) {
		strbuf_grow(&base, info->pathlen);
		make_traverse_path(base.buf, info->prev, &info->name);
		base.buf[info->pathlen-1] = '/';
		strbuf_setlen(&base, info->pathlen);
		traverse_path = xstrndup(base.buf, info->pathlen);
	} else {
		traverse_path = xstrndup(info->name.path, info->pathlen);
	}
	info->traverse_path = traverse_path;
	for (;;) {
		int trees_used;
		unsigned long mask, dirmask;
		const char *first = NULL;
		int first_len = 0;
		struct name_entry *e = NULL;
		int len;

		for (i = 0; i < n; i++) {
			e = entry + i;
			extended_entry_extract(tx + i, e, NULL, 0);
		}

		/*
		 * A tree may have "t-2" at the current location even
		 * though it may have "t" that is a subtree behind it,
		 * and another tree may return "t".  We want to grab
		 * all "t" from all trees to match in such a case.
		 */
		for (i = 0; i < n; i++) {
			e = entry + i;
			if (!e->path)
				continue;
			len = tree_entry_len(e);
			if (!first) {
				first = e->path;
				first_len = len;
				continue;
			}
			if (name_compare(e->path, len, first, first_len) < 0) {
				first = e->path;
				first_len = len;
			}
		}

		if (first) {
			for (i = 0; i < n; i++) {
				e = entry + i;
				extended_entry_extract(tx + i, e, first, first_len);
				/* Cull the ones that are not the earliest */
				if (!e->path)
					continue;
				len = tree_entry_len(e);
				if (name_compare(e->path, len, first, first_len))
					entry_clear(e);
			}
		}

		/* Now we have in entry[i] the earliest name from the trees */
		mask = 0;
		dirmask = 0;
		for (i = 0; i < n; i++) {
			if (!entry[i].path)
				continue;
			mask |= 1ul << i;
			if (S_ISDIR(entry[i].mode))
				dirmask |= 1ul << i;
			e = &entry[i];
		}
		if (!mask)
			break;
		interesting = prune_traversal(e, info, &base, interesting);
		if (interesting < 0)
			break;
		if (interesting) {
			trees_used = info->fn(n, mask, dirmask, entry, info);
			if (trees_used < 0) {
				error = trees_used;
				if (!info->show_all_errors)
					break;
			}
			mask &= trees_used;
		}
		for (i = 0; i < n; i++)
			if (mask & (1ul << i))
				update_extended_entry(tx + i, entry + i);
	}
	free(entry);
	for (i = 0; i < n; i++)
		free_extended_entry(tx + i);
	free(tx);
	free(traverse_path);
	info->traverse_path = NULL;
	strbuf_release(&base);
	return error;
}

struct dir_state {
	void *tree;
	unsigned long size;
	unsigned char sha1[20];
};

static int find_tree_entry(struct tree_desc *t, const char *name, unsigned char *result, unsigned *mode)
{
	int namelen = strlen(name);
	while (t->size) {
		const char *entry;
		const struct object_id *oid;
		int entrylen, cmp;

		oid = tree_entry_extract(t, &entry, mode);
		entrylen = tree_entry_len(&t->entry);
		update_tree_entry(t);
		if (entrylen > namelen)
			continue;
		cmp = memcmp(name, entry, entrylen);
		if (cmp > 0)
			continue;
		if (cmp < 0)
			break;
		if (entrylen == namelen) {
			hashcpy(result, oid->hash);
			return 0;
		}
		if (name[entrylen] != '/')
			continue;
		if (!S_ISDIR(*mode))
			break;
		if (++entrylen == namelen) {
			hashcpy(result, oid->hash);
			return 0;
		}
		return get_tree_entry(oid->hash, name + entrylen, result, mode);
	}
	return -1;
}

int get_tree_entry(const unsigned char *tree_sha1, const char *name, unsigned char *sha1, unsigned *mode)
{
	int retval;
	void *tree;
	unsigned long size;
	unsigned char root[20];

	tree = read_object_with_reference(tree_sha1, tree_type, &size, root);
	if (!tree)
		return -1;

	if (name[0] == '\0') {
		hashcpy(sha1, root);
		free(tree);
		return 0;
	}

	if (!size) {
		retval = -1;
	} else {
		struct tree_desc t;
		init_tree_desc(&t, tree, size);
		retval = find_tree_entry(&t, name, sha1, mode);
	}
	free(tree);
	return retval;
}

/*
 * This is Linux's built-in max for the number of symlinks to follow.
 * That limit, of course, does not affect git, but it's a reasonable
 * choice.
 */
#define GET_TREE_ENTRY_FOLLOW_SYMLINKS_MAX_LINKS 40

/**
 * Find a tree entry by following symlinks in tree_sha (which is
 * assumed to be the root of the repository).  In the event that a
 * symlink points outside the repository (e.g. a link to /foo or a
 * root-level link to ../foo), the portion of the link which is
 * outside the repository will be returned in result_path, and *mode
 * will be set to 0.  It is assumed that result_path is uninitialized.
 * If there are no symlinks, or the end result of the symlink chain
 * points to an object inside the repository, result will be filled in
 * with the sha1 of the found object, and *mode will hold the mode of
 * the object.
 *
 * See the code for enum follow_symlink_result for a description of
 * the return values.
 */
enum follow_symlinks_result get_tree_entry_follow_symlinks(unsigned char *tree_sha1, const char *name, unsigned char *result, struct strbuf *result_path, unsigned *mode)
{
	int retval = MISSING_OBJECT;
	struct dir_state *parents = NULL;
	size_t parents_alloc = 0;
	ssize_t parents_nr = 0;
	unsigned char current_tree_sha1[20];
	struct strbuf namebuf = STRBUF_INIT;
	struct tree_desc t;
	int follows_remaining = GET_TREE_ENTRY_FOLLOW_SYMLINKS_MAX_LINKS;
	int i;

	init_tree_desc(&t, NULL, 0UL);
	strbuf_init(result_path, 0);
	strbuf_addstr(&namebuf, name);
	hashcpy(current_tree_sha1, tree_sha1);

	while (1) {
		int find_result;
		char *first_slash;
		char *remainder = NULL;

		if (!t.buffer) {
			void *tree;
			unsigned char root[20];
			unsigned long size;
			tree = read_object_with_reference(current_tree_sha1,
							  tree_type, &size,
							  root);
			if (!tree)
				goto done;

			ALLOC_GROW(parents, parents_nr + 1, parents_alloc);
			parents[parents_nr].tree = tree;
			parents[parents_nr].size = size;
			hashcpy(parents[parents_nr].sha1, root);
			parents_nr++;

			if (namebuf.buf[0] == '\0') {
				hashcpy(result, root);
				retval = FOUND;
				goto done;
			}

			if (!size)
				goto done;

			/* descend */
			init_tree_desc(&t, tree, size);
		}

		/* Handle symlinks to e.g. a//b by removing leading slashes */
		while (namebuf.buf[0] == '/') {
			strbuf_remove(&namebuf, 0, 1);
		}

		/* Split namebuf into a first component and a remainder */
		if ((first_slash = strchr(namebuf.buf, '/'))) {
			*first_slash = 0;
			remainder = first_slash + 1;
		}

		if (!strcmp(namebuf.buf, "..")) {
			struct dir_state *parent;
			/*
			 * We could end up with .. in the namebuf if it
			 * appears in a symlink.
			 */

			if (parents_nr == 1) {
				if (remainder)
					*first_slash = '/';
				strbuf_add(result_path, namebuf.buf,
					   namebuf.len);
				*mode = 0;
				retval = FOUND;
				goto done;
			}
			parent = &parents[parents_nr - 1];
			free(parent->tree);
			parents_nr--;
			parent = &parents[parents_nr - 1];
			init_tree_desc(&t, parent->tree, parent->size);
			strbuf_remove(&namebuf, 0, remainder ? 3 : 2);
			continue;
		}

		/* We could end up here via a symlink to dir/.. */
		if (namebuf.buf[0] == '\0') {
			hashcpy(result, parents[parents_nr - 1].sha1);
			retval = FOUND;
			goto done;
		}

		/* Look up the first (or only) path component in the tree. */
		find_result = find_tree_entry(&t, namebuf.buf,
					      current_tree_sha1, mode);
		if (find_result) {
			goto done;
		}

		if (S_ISDIR(*mode)) {
			if (!remainder) {
				hashcpy(result, current_tree_sha1);
				retval = FOUND;
				goto done;
			}
			/* Descend the tree */
			t.buffer = NULL;
			strbuf_remove(&namebuf, 0,
				      1 + first_slash - namebuf.buf);
		} else if (S_ISREG(*mode)) {
			if (!remainder) {
				hashcpy(result, current_tree_sha1);
				retval = FOUND;
			} else {
				retval = NOT_DIR;
			}
			goto done;
		} else if (S_ISLNK(*mode)) {
			/* Follow a symlink */
			unsigned long link_len;
			size_t len;
			char *contents, *contents_start;
			struct dir_state *parent;
			enum object_type type;

			if (follows_remaining-- == 0) {
				/* Too many symlinks followed */
				retval = SYMLINK_LOOP;
				goto done;
			}

			/*
			 * At this point, we have followed at a least
			 * one symlink, so on error we need to report this.
			 */
			retval = DANGLING_SYMLINK;

			contents = read_sha1_file(current_tree_sha1, &type,
						  &link_len);

			if (!contents)
				goto done;

			if (contents[0] == '/') {
				strbuf_addstr(result_path, contents);
				free(contents);
				*mode = 0;
				retval = FOUND;
				goto done;
			}

			if (remainder)
				len = first_slash - namebuf.buf;
			else
				len = namebuf.len;

			contents_start = contents;

			parent = &parents[parents_nr - 1];
			init_tree_desc(&t, parent->tree, parent->size);
			strbuf_splice(&namebuf, 0, len,
				      contents_start, link_len);
			if (remainder)
				namebuf.buf[link_len] = '/';
			free(contents);
		}
	}
done:
	for (i = 0; i < parents_nr; i++)
		free(parents[i].tree);
	free(parents);

	strbuf_release(&namebuf);
	return retval;
}

static int match_entry(const struct pathspec_item *item,
		       const struct name_entry *entry, int pathlen,
		       const char *match, int matchlen,
		       enum interesting *never_interesting)
{
	int m = -1; /* signals that we haven't called strncmp() */

	if (item->magic & PATHSPEC_ICASE)
		/*
		 * "Never interesting" trick requires exact
		 * matching. We could do something clever with inexact
		 * matching, but it's trickier (and not to forget that
		 * strcasecmp is locale-dependent, at least in
		 * glibc). Just disable it for now. It can't be worse
		 * than the wildcard's codepath of '[Tt][Hi][Is][Ss]'
		 * pattern.
		 */
		*never_interesting = entry_not_interesting;
	else if (*never_interesting != entry_not_interesting) {
		/*
		 * We have not seen any match that sorts later
		 * than the current path.
		 */

		/*
		 * Does match sort strictly earlier than path
		 * with their common parts?
		 */
		m = strncmp(match, entry->path,
			    (matchlen < pathlen) ? matchlen : pathlen);
		if (m < 0)
			return 0;

		/*
		 * If we come here even once, that means there is at
		 * least one pathspec that would sort equal to or
		 * later than the path we are currently looking at.
		 * In other words, if we have never reached this point
		 * after iterating all pathspecs, it means all
		 * pathspecs are either outside of base, or inside the
		 * base but sorts strictly earlier than the current
		 * one.  In either case, they will never match the
		 * subsequent entries.  In such a case, we initialized
		 * the variable to -1 and that is what will be
		 * returned, allowing the caller to terminate early.
		 */
		*never_interesting = entry_not_interesting;
	}

	if (pathlen > matchlen)
		return 0;

	if (matchlen > pathlen) {
		if (match[pathlen] != '/')
			return 0;
		if (!S_ISDIR(entry->mode) && !S_ISGITLINK(entry->mode))
			return 0;
	}

	if (m == -1)
		/*
		 * we cheated and did not do strncmp(), so we do
		 * that here.
		 */
		m = ps_strncmp(item, match, entry->path, pathlen);

	/*
	 * If common part matched earlier then it is a hit,
	 * because we rejected the case where path is not a
	 * leading directory and is shorter than match.
	 */
	if (!m)
		/*
		 * match_entry does not check if the prefix part is
		 * matched case-sensitively. If the entry is a
		 * directory and part of prefix, it'll be rematched
		 * eventually by basecmp with special treatment for
		 * the prefix.
		 */
		return 1;

	return 0;
}

/* :(icase)-aware string compare */
static int basecmp(const struct pathspec_item *item,
		   const char *base, const char *match, int len)
{
	if (item->magic & PATHSPEC_ICASE) {
		int ret, n = len > item->prefix ? item->prefix : len;
		ret = strncmp(base, match, n);
		if (ret)
			return ret;
		base += n;
		match += n;
		len -= n;
	}
	return ps_strncmp(item, base, match, len);
}

static int match_dir_prefix(const struct pathspec_item *item,
			    const char *base,
			    const char *match, int matchlen)
{
	if (basecmp(item, base, match, matchlen))
		return 0;

	/*
	 * If the base is a subdirectory of a path which
	 * was specified, all of them are interesting.
	 */
	if (!matchlen ||
	    base[matchlen] == '/' ||
	    match[matchlen - 1] == '/')
		return 1;

	/* Just a random prefix match */
	return 0;
}

/*
 * Perform matching on the leading non-wildcard part of
 * pathspec. item->nowildcard_len must be greater than zero. Return
 * non-zero if base is matched.
 */
static int match_wildcard_base(const struct pathspec_item *item,
			       const char *base, int baselen,
			       int *matched)
{
	const char *match = item->match;
	/* the wildcard part is not considered in this function */
	int matchlen = item->nowildcard_len;

	if (baselen) {
		int dirlen;
		/*
		 * Return early if base is longer than the
		 * non-wildcard part but it does not match.
		 */
		if (baselen >= matchlen) {
			*matched = matchlen;
			return !basecmp(item, base, match, matchlen);
		}

		dirlen = matchlen;
		while (dirlen && match[dirlen - 1] != '/')
			dirlen--;

		/*
		 * Return early if base is shorter than the
		 * non-wildcard part but it does not match. Note that
		 * base ends with '/' so we are sure it really matches
		 * directory
		 */
		if (basecmp(item, base, match, baselen))
			return 0;
		*matched = baselen;
	} else
		*matched = 0;
	/*
	 * we could have checked entry against the non-wildcard part
	 * that is not in base and does similar never_interesting
	 * optimization as in match_entry. For now just be happy with
	 * base comparison.
	 */
	return entry_interesting;
}

/*
 * Is a tree entry interesting given the pathspec we have?
 *
 * Pre-condition: either baselen == base_offset (i.e. empty path)
 * or base[baselen-1] == '/' (i.e. with trailing slash).
 */
static enum interesting do_match(const struct name_entry *entry,
				 struct strbuf *base, int base_offset,
				 const struct pathspec *ps,
				 int exclude)
{
	int i;
	int pathlen, baselen = base->len - base_offset;
	enum interesting never_interesting = ps->has_wildcard ?
		entry_not_interesting : all_entries_not_interesting;

	GUARD_PATHSPEC(ps,
		       PATHSPEC_FROMTOP |
		       PATHSPEC_MAXDEPTH |
		       PATHSPEC_LITERAL |
		       PATHSPEC_GLOB |
		       PATHSPEC_ICASE |
		       PATHSPEC_EXCLUDE);

	if (!ps->nr) {
		if (!ps->recursive ||
		    !(ps->magic & PATHSPEC_MAXDEPTH) ||
		    ps->max_depth == -1)
			return all_entries_interesting;
		return within_depth(base->buf + base_offset, baselen,
				    !!S_ISDIR(entry->mode),
				    ps->max_depth) ?
			entry_interesting : entry_not_interesting;
	}

	pathlen = tree_entry_len(entry);

	for (i = ps->nr - 1; i >= 0; i--) {
		const struct pathspec_item *item = ps->items+i;
		const char *match = item->match;
		const char *base_str = base->buf + base_offset;
		int matchlen = item->len, matched = 0;

		if ((!exclude &&   item->magic & PATHSPEC_EXCLUDE) ||
		    ( exclude && !(item->magic & PATHSPEC_EXCLUDE)))
			continue;

		if (baselen >= matchlen) {
			/* If it doesn't match, move along... */
			if (!match_dir_prefix(item, base_str, match, matchlen))
				goto match_wildcards;

			if (!ps->recursive ||
			    !(ps->magic & PATHSPEC_MAXDEPTH) ||
			    ps->max_depth == -1)
				return all_entries_interesting;

			return within_depth(base_str + matchlen + 1,
					    baselen - matchlen - 1,
					    !!S_ISDIR(entry->mode),
					    ps->max_depth) ?
				entry_interesting : entry_not_interesting;
		}

		/* Either there must be no base, or the base must match. */
		if (baselen == 0 || !basecmp(item, base_str, match, baselen)) {
			if (match_entry(item, entry, pathlen,
					match + baselen, matchlen - baselen,
					&never_interesting))
				return entry_interesting;

			if (item->nowildcard_len < item->len) {
				if (!git_fnmatch(item, match + baselen, entry->path,
						 item->nowildcard_len - baselen))
					return entry_interesting;

				/*
				 * Match all directories. We'll try to
				 * match files later on.
				 */
				if (ps->recursive && S_ISDIR(entry->mode))
					return entry_interesting;
			}

			continue;
		}

match_wildcards:
		if (item->nowildcard_len == item->len)
			continue;

		if (item->nowildcard_len &&
		    !match_wildcard_base(item, base_str, baselen, &matched))
			continue;

		/*
		 * Concatenate base and entry->path into one and do
		 * fnmatch() on it.
		 *
		 * While we could avoid concatenation in certain cases
		 * [1], which saves a memcpy and potentially a
		 * realloc, it turns out not worth it. Measurement on
		 * linux-2.6 does not show any clear improvements,
		 * partly because of the nowildcard_len optimization
		 * in git_fnmatch(). Avoid micro-optimizations here.
		 *
		 * [1] if match_wildcard_base() says the base
		 * directory is already matched, we only need to match
		 * the rest, which is shorter so _in theory_ faster.
		 */

		strbuf_add(base, entry->path, pathlen);

		if (!git_fnmatch(item, match, base->buf + base_offset,
				 item->nowildcard_len)) {
			strbuf_setlen(base, base_offset + baselen);
			return entry_interesting;
		}
		strbuf_setlen(base, base_offset + baselen);

		/*
		 * Match all directories. We'll try to match files
		 * later on.
		 * max_depth is ignored but we may consider support it
		 * in future, see
		 * http://thread.gmane.org/gmane.comp.version-control.git/163757/focus=163840
		 */
		if (ps->recursive && S_ISDIR(entry->mode))
			return entry_interesting;
	}
	return never_interesting; /* No matches */
}

/*
 * Is a tree entry interesting given the pathspec we have?
 *
 * Pre-condition: either baselen == base_offset (i.e. empty path)
 * or base[baselen-1] == '/' (i.e. with trailing slash).
 */
enum interesting tree_entry_interesting(const struct name_entry *entry,
					struct strbuf *base, int base_offset,
					const struct pathspec *ps)
{
	enum interesting positive, negative;
	positive = do_match(entry, base, base_offset, ps, 0);

	/*
	 * case | entry | positive | negative | result
	 * -----+-------+----------+----------+-------
	 *   1  |  file |   -1     |  -1..2   |  -1
	 *   2  |  file |    0     |  -1..2   |   0
	 *   3  |  file |    1     |   -1     |   1
	 *   4  |  file |    1     |    0     |   1
	 *   5  |  file |    1     |    1     |   0
	 *   6  |  file |    1     |    2     |   0
	 *   7  |  file |    2     |   -1     |   2
	 *   8  |  file |    2     |    0     |   2
	 *   9  |  file |    2     |    1     |   0
	 *  10  |  file |    2     |    2     |  -1
	 * -----+-------+----------+----------+-------
	 *  11  |  dir  |   -1     |  -1..2   |  -1
	 *  12  |  dir  |    0     |  -1..2   |   0
	 *  13  |  dir  |    1     |   -1     |   1
	 *  14  |  dir  |    1     |    0     |   1
	 *  15  |  dir  |    1     |    1     |   1 (*)
	 *  16  |  dir  |    1     |    2     |   0
	 *  17  |  dir  |    2     |   -1     |   2
	 *  18  |  dir  |    2     |    0     |   2
	 *  19  |  dir  |    2     |    1     |   1 (*)
	 *  20  |  dir  |    2     |    2     |  -1
	 *
	 * (*) An exclude pattern interested in a directory does not
	 * necessarily mean it will exclude all of the directory. In
	 * wildcard case, it can't decide until looking at individual
	 * files inside. So don't write such directories off yet.
	 */

	if (!(ps->magic & PATHSPEC_EXCLUDE) ||
	    positive <= entry_not_interesting) /* #1, #2, #11, #12 */
		return positive;

	negative = do_match(entry, base, base_offset, ps, 1);

	/* #3, #4, #7, #8, #13, #14, #17, #18 */
	if (negative <= entry_not_interesting)
		return positive;

	/* #15, #19 */
	if (S_ISDIR(entry->mode) &&
	    positive >= entry_interesting &&
	    negative == entry_interesting)
		return entry_interesting;

	if ((positive == entry_interesting &&
	     negative >= entry_interesting) || /* #5, #6, #16 */
	    (positive == all_entries_interesting &&
	     negative == entry_interesting)) /* #9 */
		return entry_not_interesting;

	return all_entries_not_interesting; /* #10, #20 */
}