git

1
#define USE_THE_REPOSITORY_VARIABLE
2

3
#include "git-compat-util.h"
4
#include "environment.h"
5
#include "hex.h"
6
#include "lockfile.h"
7
#include "tree.h"
8
#include "tree-walk.h"
9
#include "cache-tree.h"
10
#include "bulk-checkin.h"
11
#include "object-file.h"
12
#include "object-store-ll.h"
13
#include "read-cache-ll.h"
14
#include "replace-object.h"
15
#include "promisor-remote.h"
16
#include "trace.h"
17
#include "trace2.h"
18

19
#ifndef DEBUG_CACHE_TREE
20
#define DEBUG_CACHE_TREE 0
21
#endif
22

23
struct cache_tree *cache_tree(void)
24
{
25
	struct cache_tree *it = xcalloc(1, sizeof(struct cache_tree));
26
	it->entry_count = -1;
27
	return it;
28
}
29

30
void cache_tree_free(struct cache_tree **it_p)
31
{
32
	int i;
33
	struct cache_tree *it = *it_p;
34

35
	if (!it)
36
		return;
37
	for (i = 0; i < it->subtree_nr; i++)
38
		if (it->down[i]) {
39
			cache_tree_free(&it->down[i]->cache_tree);
40
			free(it->down[i]);
41
		}
42
	free(it->down);
43
	free(it);
44
	*it_p = NULL;
45
}
46

47
static int subtree_name_cmp(const char *one, int onelen,
48
			    const char *two, int twolen)
49
{
50
	if (onelen < twolen)
51
		return -1;
52
	if (twolen < onelen)
53
		return 1;
54
	return memcmp(one, two, onelen);
55
}
56

57
int cache_tree_subtree_pos(struct cache_tree *it, const char *path, int pathlen)
58
{
59
	struct cache_tree_sub **down = it->down;
60
	int lo, hi;
61
	lo = 0;
62
	hi = it->subtree_nr;
63
	while (lo < hi) {
64
		int mi = lo + (hi - lo) / 2;
65
		struct cache_tree_sub *mdl = down[mi];
66
		int cmp = subtree_name_cmp(path, pathlen,
67
					   mdl->name, mdl->namelen);
68
		if (!cmp)
69
			return mi;
70
		if (cmp < 0)
71
			hi = mi;
72
		else
73
			lo = mi + 1;
74
	}
75
	return -lo-1;
76
}
77

78
static struct cache_tree_sub *find_subtree(struct cache_tree *it,
79
					   const char *path,
80
					   int pathlen,
81
					   int create)
82
{
83
	struct cache_tree_sub *down;
84
	int pos = cache_tree_subtree_pos(it, path, pathlen);
85
	if (0 <= pos)
86
		return it->down[pos];
87
	if (!create)
88
		return NULL;
89

90
	pos = -pos-1;
91
	ALLOC_GROW(it->down, it->subtree_nr + 1, it->subtree_alloc);
92
	it->subtree_nr++;
93

94
	FLEX_ALLOC_MEM(down, name, path, pathlen);
95
	down->cache_tree = NULL;
96
	down->namelen = pathlen;
97

98
	if (pos < it->subtree_nr)
99
		MOVE_ARRAY(it->down + pos + 1, it->down + pos,
100
			   it->subtree_nr - pos - 1);
101
	it->down[pos] = down;
102
	return down;
103
}
104

105
struct cache_tree_sub *cache_tree_sub(struct cache_tree *it, const char *path)
106
{
107
	int pathlen = strlen(path);
108
	return find_subtree(it, path, pathlen, 1);
109
}
110

111
static int do_invalidate_path(struct cache_tree *it, const char *path)
112
{
113
	/* a/b/c
114
	 * ==> invalidate self
115
	 * ==> find "a", have it invalidate "b/c"
116
	 * a
117
	 * ==> invalidate self
118
	 * ==> if "a" exists as a subtree, remove it.
119
	 */
120
	const char *slash;
121
	int namelen;
122
	struct cache_tree_sub *down;
123

124
#if DEBUG_CACHE_TREE
125
	fprintf(stderr, "cache-tree invalidate <%s>\n", path);
126
#endif
127

128
	if (!it)
129
		return 0;
130
	slash = strchrnul(path, '/');
131
	namelen = slash - path;
132
	it->entry_count = -1;
133
	if (!*slash) {
134
		int pos;
135
		pos = cache_tree_subtree_pos(it, path, namelen);
136
		if (0 <= pos) {
137
			cache_tree_free(&it->down[pos]->cache_tree);
138
			free(it->down[pos]);
139
			/* 0 1 2 3 4 5
140
			 *       ^     ^subtree_nr = 6
141
			 *       pos
142
			 * move 4 and 5 up one place (2 entries)
143
			 * 2 = 6 - 3 - 1 = subtree_nr - pos - 1
144
			 */
145
			MOVE_ARRAY(it->down + pos, it->down + pos + 1,
146
				   it->subtree_nr - pos - 1);
147
			it->subtree_nr--;
148
		}
149
		return 1;
150
	}
151
	down = find_subtree(it, path, namelen, 0);
152
	if (down)
153
		do_invalidate_path(down->cache_tree, slash + 1);
154
	return 1;
155
}
156

157
void cache_tree_invalidate_path(struct index_state *istate, const char *path)
158
{
159
	if (do_invalidate_path(istate->cache_tree, path))
160
		istate->cache_changed |= CACHE_TREE_CHANGED;
161
}
162

163
static int verify_cache(struct index_state *istate, int flags)
164
{
165
	unsigned i, funny;
166
	int silent = flags & WRITE_TREE_SILENT;
167

168
	/* Verify that the tree is merged */
169
	funny = 0;
170
	for (i = 0; i < istate->cache_nr; i++) {
171
		const struct cache_entry *ce = istate->cache[i];
172
		if (ce_stage(ce)) {
173
			if (silent)
174
				return -1;
175
			if (10 < ++funny) {
176
				fprintf(stderr, "...\n");
177
				break;
178
			}
179
			fprintf(stderr, "%s: unmerged (%s)\n",
180
				ce->name, oid_to_hex(&ce->oid));
181
		}
182
	}
183
	if (funny)
184
		return -1;
185

186
	/* Also verify that the cache does not have path and path/file
187
	 * at the same time.  At this point we know the cache has only
188
	 * stage 0 entries.
189
	 */
190
	funny = 0;
191
	for (i = 0; i + 1 < istate->cache_nr; i++) {
192
		/* path/file always comes after path because of the way
193
		 * the cache is sorted.  Also path can appear only once,
194
		 * which means conflicting one would immediately follow.
195
		 */
196
		const struct cache_entry *this_ce = istate->cache[i];
197
		const struct cache_entry *next_ce = istate->cache[i + 1];
198
		const char *this_name = this_ce->name;
199
		const char *next_name = next_ce->name;
200
		int this_len = ce_namelen(this_ce);
201
		if (this_len < ce_namelen(next_ce) &&
202
		    next_name[this_len] == '/' &&
203
		    strncmp(this_name, next_name, this_len) == 0) {
204
			if (10 < ++funny) {
205
				fprintf(stderr, "...\n");
206
				break;
207
			}
208
			fprintf(stderr, "You have both %s and %s\n",
209
				this_name, next_name);
210
		}
211
	}
212
	if (funny)
213
		return -1;
214
	return 0;
215
}
216

217
static void discard_unused_subtrees(struct cache_tree *it)
218
{
219
	struct cache_tree_sub **down = it->down;
220
	int nr = it->subtree_nr;
221
	int dst, src;
222
	for (dst = src = 0; src < nr; src++) {
223
		struct cache_tree_sub *s = down[src];
224
		if (s->used)
225
			down[dst++] = s;
226
		else {
227
			cache_tree_free(&s->cache_tree);
228
			free(s);
229
			it->subtree_nr--;
230
		}
231
	}
232
}
233

234
int cache_tree_fully_valid(struct cache_tree *it)
235
{
236
	int i;
237
	if (!it)
238
		return 0;
239
	if (it->entry_count < 0 || !repo_has_object_file(the_repository, &it->oid))
240
		return 0;
241
	for (i = 0; i < it->subtree_nr; i++) {
242
		if (!cache_tree_fully_valid(it->down[i]->cache_tree))
243
			return 0;
244
	}
245
	return 1;
246
}
247

248
static int must_check_existence(const struct cache_entry *ce)
249
{
250
	return !(repo_has_promisor_remote(the_repository) && ce_skip_worktree(ce));
251
}
252

253
static int update_one(struct cache_tree *it,
254
		      struct cache_entry **cache,
255
		      int entries,
256
		      const char *base,
257
		      int baselen,
258
		      int *skip_count,
259
		      int flags)
260
{
261
	struct strbuf buffer;
262
	int missing_ok = flags & WRITE_TREE_MISSING_OK;
263
	int dryrun = flags & WRITE_TREE_DRY_RUN;
264
	int repair = flags & WRITE_TREE_REPAIR;
265
	int to_invalidate = 0;
266
	int i;
267

268
	assert(!(dryrun && repair));
269

270
	*skip_count = 0;
271

272
	/*
273
	 * If the first entry of this region is a sparse directory
274
	 * entry corresponding exactly to 'base', then this cache_tree
275
	 * struct is a "leaf" in the data structure, pointing to the
276
	 * tree OID specified in the entry.
277
	 */
278
	if (entries > 0) {
279
		const struct cache_entry *ce = cache[0];
280

281
		if (S_ISSPARSEDIR(ce->ce_mode) &&
282
		    ce->ce_namelen == baselen &&
283
		    !strncmp(ce->name, base, baselen)) {
284
			it->entry_count = 1;
285
			oidcpy(&it->oid, &ce->oid);
286
			return 1;
287
		}
288
	}
289

290
	if (0 <= it->entry_count && repo_has_object_file(the_repository, &it->oid))
291
		return it->entry_count;
292

293
	/*
294
	 * We first scan for subtrees and update them; we start by
295
	 * marking existing subtrees -- the ones that are unmarked
296
	 * should not be in the result.
297
	 */
298
	for (i = 0; i < it->subtree_nr; i++)
299
		it->down[i]->used = 0;
300

301
	/*
302
	 * Find the subtrees and update them.
303
	 */
304
	i = 0;
305
	while (i < entries) {
306
		const struct cache_entry *ce = cache[i];
307
		struct cache_tree_sub *sub;
308
		const char *path, *slash;
309
		int pathlen, sublen, subcnt, subskip;
310

311
		path = ce->name;
312
		pathlen = ce_namelen(ce);
313
		if (pathlen <= baselen || memcmp(base, path, baselen))
314
			break; /* at the end of this level */
315

316
		slash = strchr(path + baselen, '/');
317
		if (!slash) {
318
			i++;
319
			continue;
320
		}
321
		/*
322
		 * a/bbb/c (base = a/, slash = /c)
323
		 * ==>
324
		 * path+baselen = bbb/c, sublen = 3
325
		 */
326
		sublen = slash - (path + baselen);
327
		sub = find_subtree(it, path + baselen, sublen, 1);
328
		if (!sub->cache_tree)
329
			sub->cache_tree = cache_tree();
330
		subcnt = update_one(sub->cache_tree,
331
				    cache + i, entries - i,
332
				    path,
333
				    baselen + sublen + 1,
334
				    &subskip,
335
				    flags);
336
		if (subcnt < 0)
337
			return subcnt;
338
		if (!subcnt)
339
			die("index cache-tree records empty sub-tree");
340
		i += subcnt;
341
		sub->count = subcnt; /* to be used in the next loop */
342
		*skip_count += subskip;
343
		sub->used = 1;
344
	}
345

346
	discard_unused_subtrees(it);
347

348
	/*
349
	 * Then write out the tree object for this level.
350
	 */
351
	strbuf_init(&buffer, 8192);
352

353
	i = 0;
354
	while (i < entries) {
355
		const struct cache_entry *ce = cache[i];
356
		struct cache_tree_sub *sub = NULL;
357
		const char *path, *slash;
358
		int pathlen, entlen;
359
		const struct object_id *oid;
360
		unsigned mode;
361
		int expected_missing = 0;
362
		int contains_ita = 0;
363
		int ce_missing_ok;
364

365
		path = ce->name;
366
		pathlen = ce_namelen(ce);
367
		if (pathlen <= baselen || memcmp(base, path, baselen))
368
			break; /* at the end of this level */
369

370
		slash = strchr(path + baselen, '/');
371
		if (slash) {
372
			entlen = slash - (path + baselen);
373
			sub = find_subtree(it, path + baselen, entlen, 0);
374
			if (!sub)
375
				die("cache-tree.c: '%.*s' in '%s' not found",
376
				    entlen, path + baselen, path);
377
			i += sub->count;
378
			oid = &sub->cache_tree->oid;
379
			mode = S_IFDIR;
380
			contains_ita = sub->cache_tree->entry_count < 0;
381
			if (contains_ita) {
382
				to_invalidate = 1;
383
				expected_missing = 1;
384
			}
385
		}
386
		else {
387
			oid = &ce->oid;
388
			mode = ce->ce_mode;
389
			entlen = pathlen - baselen;
390
			i++;
391
		}
392

393
		ce_missing_ok = mode == S_IFGITLINK || missing_ok ||
394
			!must_check_existence(ce);
395
		if (is_null_oid(oid) ||
396
		    (!ce_missing_ok && !repo_has_object_file(the_repository, oid))) {
397
			strbuf_release(&buffer);
398
			if (expected_missing)
399
				return -1;
400
			return error("invalid object %06o %s for '%.*s'",
401
				mode, oid_to_hex(oid), entlen+baselen, path);
402
		}
403

404
		/*
405
		 * CE_REMOVE entries are removed before the index is
406
		 * written to disk. Skip them to remain consistent
407
		 * with the future on-disk index.
408
		 */
409
		if (ce->ce_flags & CE_REMOVE) {
410
			*skip_count = *skip_count + 1;
411
			continue;
412
		}
413

414
		/*
415
		 * CE_INTENT_TO_ADD entries exist in on-disk index but
416
		 * they are not part of generated trees. Invalidate up
417
		 * to root to force cache-tree users to read elsewhere.
418
		 */
419
		if (!sub && ce_intent_to_add(ce)) {
420
			to_invalidate = 1;
421
			continue;
422
		}
423

424
		/*
425
		 * "sub" can be an empty tree if all subentries are i-t-a.
426
		 */
427
		if (contains_ita && is_empty_tree_oid(oid, the_repository->hash_algo))
428
			continue;
429

430
		strbuf_grow(&buffer, entlen + 100);
431
		strbuf_addf(&buffer, "%o %.*s%c", mode, entlen, path + baselen, '\0');
432
		strbuf_add(&buffer, oid->hash, the_hash_algo->rawsz);
433

434
#if DEBUG_CACHE_TREE
435
		fprintf(stderr, "cache-tree update-one %o %.*s\n",
436
			mode, entlen, path + baselen);
437
#endif
438
	}
439

440
	if (repair) {
441
		struct object_id oid;
442
		hash_object_file(the_hash_algo, buffer.buf, buffer.len,
443
				 OBJ_TREE, &oid);
444
		if (repo_has_object_file_with_flags(the_repository, &oid, OBJECT_INFO_SKIP_FETCH_OBJECT))
445
			oidcpy(&it->oid, &oid);
446
		else
447
			to_invalidate = 1;
448
	} else if (dryrun) {
449
		hash_object_file(the_hash_algo, buffer.buf, buffer.len,
450
				 OBJ_TREE, &it->oid);
451
	} else if (write_object_file_flags(buffer.buf, buffer.len, OBJ_TREE,
452
					   &it->oid, NULL, flags & WRITE_TREE_SILENT
453
					   ? HASH_SILENT : 0)) {
454
		strbuf_release(&buffer);
455
		return -1;
456
	}
457

458
	strbuf_release(&buffer);
459
	it->entry_count = to_invalidate ? -1 : i - *skip_count;
460
#if DEBUG_CACHE_TREE
461
	fprintf(stderr, "cache-tree update-one (%d ent, %d subtree) %s\n",
462
		it->entry_count, it->subtree_nr,
463
		oid_to_hex(&it->oid));
464
#endif
465
	return i;
466
}
467

468
int cache_tree_update(struct index_state *istate, int flags)
469
{
470
	int skip, i;
471

472
	i = verify_cache(istate, flags);
473

474
	if (i)
475
		return i;
476

477
	if (!istate->cache_tree)
478
		istate->cache_tree = cache_tree();
479

480
	if (!(flags & WRITE_TREE_MISSING_OK) && repo_has_promisor_remote(the_repository))
481
		prefetch_cache_entries(istate, must_check_existence);
482

483
	trace_performance_enter();
484
	trace2_region_enter("cache_tree", "update", the_repository);
485
	begin_odb_transaction();
486
	i = update_one(istate->cache_tree, istate->cache, istate->cache_nr,
487
		       "", 0, &skip, flags);
488
	end_odb_transaction();
489
	trace2_region_leave("cache_tree", "update", the_repository);
490
	trace_performance_leave("cache_tree_update");
491
	if (i < 0)
492
		return i;
493
	istate->cache_changed |= CACHE_TREE_CHANGED;
494
	return 0;
495
}
496

497
static void write_one(struct strbuf *buffer, struct cache_tree *it,
498
		      const char *path, int pathlen)
499
{
500
	int i;
501

502
	/* One "cache-tree" entry consists of the following:
503
	 * path (NUL terminated)
504
	 * entry_count, subtree_nr ("%d %d\n")
505
	 * tree-sha1 (missing if invalid)
506
	 * subtree_nr "cache-tree" entries for subtrees.
507
	 */
508
	strbuf_grow(buffer, pathlen + 100);
509
	strbuf_add(buffer, path, pathlen);
510
	strbuf_addf(buffer, "%c%d %d\n", 0, it->entry_count, it->subtree_nr);
511

512
#if DEBUG_CACHE_TREE
513
	if (0 <= it->entry_count)
514
		fprintf(stderr, "cache-tree <%.*s> (%d ent, %d subtree) %s\n",
515
			pathlen, path, it->entry_count, it->subtree_nr,
516
			oid_to_hex(&it->oid));
517
	else
518
		fprintf(stderr, "cache-tree <%.*s> (%d subtree) invalid\n",
519
			pathlen, path, it->subtree_nr);
520
#endif
521

522
	if (0 <= it->entry_count) {
523
		strbuf_add(buffer, it->oid.hash, the_hash_algo->rawsz);
524
	}
525
	for (i = 0; i < it->subtree_nr; i++) {
526
		struct cache_tree_sub *down = it->down[i];
527
		if (i) {
528
			struct cache_tree_sub *prev = it->down[i-1];
529
			if (subtree_name_cmp(down->name, down->namelen,
530
					     prev->name, prev->namelen) <= 0)
531
				die("fatal - unsorted cache subtree");
532
		}
533
		write_one(buffer, down->cache_tree, down->name, down->namelen);
534
	}
535
}
536

537
void cache_tree_write(struct strbuf *sb, struct cache_tree *root)
538
{
539
	trace2_region_enter("cache_tree", "write", the_repository);
540
	write_one(sb, root, "", 0);
541
	trace2_region_leave("cache_tree", "write", the_repository);
542
}
543

544
static struct cache_tree *read_one(const char **buffer, unsigned long *size_p)
545
{
546
	const char *buf = *buffer;
547
	unsigned long size = *size_p;
548
	const char *cp;
549
	char *ep;
550
	struct cache_tree *it;
551
	int i, subtree_nr;
552
	const unsigned rawsz = the_hash_algo->rawsz;
553

554
	it = NULL;
555
	/* skip name, but make sure name exists */
556
	while (size && *buf) {
557
		size--;
558
		buf++;
559
	}
560
	if (!size)
561
		goto free_return;
562
	buf++; size--;
563
	it = cache_tree();
564

565
	cp = buf;
566
	it->entry_count = strtol(cp, &ep, 10);
567
	if (cp == ep)
568
		goto free_return;
569
	cp = ep;
570
	subtree_nr = strtol(cp, &ep, 10);
571
	if (cp == ep)
572
		goto free_return;
573
	while (size && *buf && *buf != '\n') {
574
		size--;
575
		buf++;
576
	}
577
	if (!size)
578
		goto free_return;
579
	buf++; size--;
580
	if (0 <= it->entry_count) {
581
		if (size < rawsz)
582
			goto free_return;
583
		oidread(&it->oid, (const unsigned char *)buf,
584
			the_repository->hash_algo);
585
		buf += rawsz;
586
		size -= rawsz;
587
	}
588

589
#if DEBUG_CACHE_TREE
590
	if (0 <= it->entry_count)
591
		fprintf(stderr, "cache-tree <%s> (%d ent, %d subtree) %s\n",
592
			*buffer, it->entry_count, subtree_nr,
593
			oid_to_hex(&it->oid));
594
	else
595
		fprintf(stderr, "cache-tree <%s> (%d subtrees) invalid\n",
596
			*buffer, subtree_nr);
597
#endif
598

599
	/*
600
	 * Just a heuristic -- we do not add directories that often but
601
	 * we do not want to have to extend it immediately when we do,
602
	 * hence +2.
603
	 */
604
	it->subtree_alloc = subtree_nr + 2;
605
	CALLOC_ARRAY(it->down, it->subtree_alloc);
606
	for (i = 0; i < subtree_nr; i++) {
607
		/* read each subtree */
608
		struct cache_tree *sub;
609
		struct cache_tree_sub *subtree;
610
		const char *name = buf;
611

612
		sub = read_one(&buf, &size);
613
		if (!sub)
614
			goto free_return;
615
		subtree = cache_tree_sub(it, name);
616
		subtree->cache_tree = sub;
617
	}
618
	if (subtree_nr != it->subtree_nr)
619
		die("cache-tree: internal error");
620
	*buffer = buf;
621
	*size_p = size;
622
	return it;
623

624
 free_return:
625
	cache_tree_free(&it);
626
	return NULL;
627
}
628

629
struct cache_tree *cache_tree_read(const char *buffer, unsigned long size)
630
{
631
	struct cache_tree *result;
632

633
	if (buffer[0])
634
		return NULL; /* not the whole tree */
635

636
	trace2_region_enter("cache_tree", "read", the_repository);
637
	result = read_one(&buffer, &size);
638
	trace2_region_leave("cache_tree", "read", the_repository);
639

640
	return result;
641
}
642

643
static struct cache_tree *cache_tree_find(struct cache_tree *it, const char *path)
644
{
645
	if (!it)
646
		return NULL;
647
	while (*path) {
648
		const char *slash;
649
		struct cache_tree_sub *sub;
650

651
		slash = strchrnul(path, '/');
652
		/*
653
		 * Between path and slash is the name of the subtree
654
		 * to look for.
655
		 */
656
		sub = find_subtree(it, path, slash - path, 0);
657
		if (!sub)
658
			return NULL;
659
		it = sub->cache_tree;
660

661
		path = slash;
662
		while (*path == '/')
663
			path++;
664
	}
665
	return it;
666
}
667

668
static int write_index_as_tree_internal(struct object_id *oid,
669
					struct index_state *index_state,
670
					int cache_tree_valid,
671
					int flags,
672
					const char *prefix)
673
{
674
	if (flags & WRITE_TREE_IGNORE_CACHE_TREE) {
675
		cache_tree_free(&index_state->cache_tree);
676
		cache_tree_valid = 0;
677
	}
678

679
	if (!cache_tree_valid && cache_tree_update(index_state, flags) < 0)
680
		return WRITE_TREE_UNMERGED_INDEX;
681

682
	if (prefix) {
683
		struct cache_tree *subtree;
684
		subtree = cache_tree_find(index_state->cache_tree, prefix);
685
		if (!subtree)
686
			return WRITE_TREE_PREFIX_ERROR;
687
		oidcpy(oid, &subtree->oid);
688
	}
689
	else
690
		oidcpy(oid, &index_state->cache_tree->oid);
691

692
	return 0;
693
}
694

695
struct tree* write_in_core_index_as_tree(struct repository *repo) {
696
	struct object_id o;
697
	int was_valid, ret;
698

699
	struct index_state *index_state	= repo->index;
700
	was_valid = index_state->cache_tree &&
701
		    cache_tree_fully_valid(index_state->cache_tree);
702

703
	ret = write_index_as_tree_internal(&o, index_state, was_valid, 0, NULL);
704
	if (ret == WRITE_TREE_UNMERGED_INDEX) {
705
		int i;
706
		bug("there are unmerged index entries:");
707
		for (i = 0; i < index_state->cache_nr; i++) {
708
			const struct cache_entry *ce = index_state->cache[i];
709
			if (ce_stage(ce))
710
				bug("%d %.*s", ce_stage(ce),
711
				    (int)ce_namelen(ce), ce->name);
712
		}
713
		BUG("unmerged index entries when writing in-core index");
714
	}
715

716
	return lookup_tree(repo, &index_state->cache_tree->oid);
717
}
718

719

720
int write_index_as_tree(struct object_id *oid, struct index_state *index_state, const char *index_path, int flags, const char *prefix)
721
{
722
	int entries, was_valid;
723
	struct lock_file lock_file = LOCK_INIT;
724
	int ret;
725

726
	hold_lock_file_for_update(&lock_file, index_path, LOCK_DIE_ON_ERROR);
727

728
	entries = read_index_from(index_state, index_path, get_git_dir());
729
	if (entries < 0) {
730
		ret = WRITE_TREE_UNREADABLE_INDEX;
731
		goto out;
732
	}
733

734
	was_valid = !(flags & WRITE_TREE_IGNORE_CACHE_TREE) &&
735
		    index_state->cache_tree &&
736
		    cache_tree_fully_valid(index_state->cache_tree);
737

738
	ret = write_index_as_tree_internal(oid, index_state, was_valid, flags,
739
					   prefix);
740
	if (!ret && !was_valid) {
741
		write_locked_index(index_state, &lock_file, COMMIT_LOCK);
742
		/* Not being able to write is fine -- we are only interested
743
		 * in updating the cache-tree part, and if the next caller
744
		 * ends up using the old index with unupdated cache-tree part
745
		 * it misses the work we did here, but that is just a
746
		 * performance penalty and not a big deal.
747
		 */
748
	}
749

750
out:
751
	rollback_lock_file(&lock_file);
752
	return ret;
753
}
754

755
static void prime_cache_tree_sparse_dir(struct cache_tree *it,
756
					struct tree *tree)
757
{
758

759
	oidcpy(&it->oid, &tree->object.oid);
760
	it->entry_count = 1;
761
}
762

763
static void prime_cache_tree_rec(struct repository *r,
764
				 struct cache_tree *it,
765
				 struct tree *tree,
766
				 struct strbuf *tree_path)
767
{
768
	struct tree_desc desc;
769
	struct name_entry entry;
770
	int cnt;
771
	size_t base_path_len = tree_path->len;
772

773
	oidcpy(&it->oid, &tree->object.oid);
774

775
	init_tree_desc(&desc, &tree->object.oid, tree->buffer, tree->size);
776
	cnt = 0;
777
	while (tree_entry(&desc, &entry)) {
778
		if (!S_ISDIR(entry.mode))
779
			cnt++;
780
		else {
781
			struct cache_tree_sub *sub;
782
			struct tree *subtree = lookup_tree(r, &entry.oid);
783

784
			if (parse_tree(subtree) < 0)
785
				exit(128);
786
			sub = cache_tree_sub(it, entry.path);
787
			sub->cache_tree = cache_tree();
788

789
			/*
790
			 * Recursively-constructed subtree path is only needed when working
791
			 * in a sparse index (where it's used to determine whether the
792
			 * subtree is a sparse directory in the index).
793
			 */
794
			if (r->index->sparse_index) {
795
				strbuf_setlen(tree_path, base_path_len);
796
				strbuf_add(tree_path, entry.path, entry.pathlen);
797
				strbuf_addch(tree_path, '/');
798
			}
799

800
			/*
801
			 * If a sparse index is in use, the directory being processed may be
802
			 * sparse. To confirm that, we can check whether an entry with that
803
			 * exact name exists in the index. If it does, the created subtree
804
			 * should be sparse. Otherwise, cache tree expansion should continue
805
			 * as normal.
806
			 */
807
			if (r->index->sparse_index &&
808
			    index_entry_exists(r->index, tree_path->buf, tree_path->len))
809
				prime_cache_tree_sparse_dir(sub->cache_tree, subtree);
810
			else
811
				prime_cache_tree_rec(r, sub->cache_tree, subtree, tree_path);
812
			cnt += sub->cache_tree->entry_count;
813
		}
814
	}
815

816
	it->entry_count = cnt;
817
}
818

819
void prime_cache_tree(struct repository *r,
820
		      struct index_state *istate,
821
		      struct tree *tree)
822
{
823
	struct strbuf tree_path = STRBUF_INIT;
824

825
	trace2_region_enter("cache-tree", "prime_cache_tree", r);
826
	cache_tree_free(&istate->cache_tree);
827
	istate->cache_tree = cache_tree();
828

829
	prime_cache_tree_rec(r, istate->cache_tree, tree, &tree_path);
830
	strbuf_release(&tree_path);
831
	istate->cache_changed |= CACHE_TREE_CHANGED;
832
	trace2_region_leave("cache-tree", "prime_cache_tree", r);
833
}
834

835
/*
836
 * find the cache_tree that corresponds to the current level without
837
 * exploding the full path into textual form.  The root of the
838
 * cache tree is given as "root", and our current level is "info".
839
 * (1) When at root level, info->prev is NULL, so it is "root" itself.
840
 * (2) Otherwise, find the cache_tree that corresponds to one level
841
 *     above us, and find ourselves in there.
842
 */
843
static struct cache_tree *find_cache_tree_from_traversal(struct cache_tree *root,
844
							 struct traverse_info *info)
845
{
846
	struct cache_tree *our_parent;
847

848
	if (!info->prev)
849
		return root;
850
	our_parent = find_cache_tree_from_traversal(root, info->prev);
851
	return cache_tree_find(our_parent, info->name);
852
}
853

854
int cache_tree_matches_traversal(struct cache_tree *root,
855
				 struct name_entry *ent,
856
				 struct traverse_info *info)
857
{
858
	struct cache_tree *it;
859

860
	it = find_cache_tree_from_traversal(root, info);
861
	it = cache_tree_find(it, ent->path);
862
	if (it && it->entry_count > 0 && oideq(&ent->oid, &it->oid))
863
		return it->entry_count;
864
	return 0;
865
}
866

867
static void verify_one_sparse(struct index_state *istate,
868
			      struct strbuf *path,
869
			      int pos)
870
{
871
	struct cache_entry *ce = istate->cache[pos];
872

873
	if (!S_ISSPARSEDIR(ce->ce_mode))
874
		BUG("directory '%s' is present in index, but not sparse",
875
		    path->buf);
876
}
877

878
/*
879
 * Returns:
880
 *  0 - Verification completed.
881
 *  1 - Restart verification - a call to ensure_full_index() freed the cache
882
 *      tree that is being verified and verification needs to be restarted from
883
 *      the new toplevel cache tree.
884
 */
885
static int verify_one(struct repository *r,
886
		      struct index_state *istate,
887
		      struct cache_tree *it,
888
		      struct strbuf *path)
889
{
890
	int i, pos, len = path->len;
891
	struct strbuf tree_buf = STRBUF_INIT;
892
	struct object_id new_oid;
893

894
	for (i = 0; i < it->subtree_nr; i++) {
895
		strbuf_addf(path, "%s/", it->down[i]->name);
896
		if (verify_one(r, istate, it->down[i]->cache_tree, path))
897
			return 1;
898
		strbuf_setlen(path, len);
899
	}
900

901
	if (it->entry_count < 0 ||
902
	    /* no verification on tests (t7003) that replace trees */
903
	    lookup_replace_object(r, &it->oid) != &it->oid)
904
		return 0;
905

906
	if (path->len) {
907
		/*
908
		 * If the index is sparse and the cache tree is not
909
		 * index_name_pos() may trigger ensure_full_index() which will
910
		 * free the tree that is being verified.
911
		 */
912
		int is_sparse = istate->sparse_index;
913
		pos = index_name_pos(istate, path->buf, path->len);
914
		if (is_sparse && !istate->sparse_index)
915
			return 1;
916

917
		if (pos >= 0) {
918
			verify_one_sparse(istate, path, pos);
919
			return 0;
920
		}
921

922
		pos = -pos - 1;
923
	} else {
924
		pos = 0;
925
	}
926

927
	i = 0;
928
	while (i < it->entry_count) {
929
		struct cache_entry *ce = istate->cache[pos + i];
930
		const char *slash;
931
		struct cache_tree_sub *sub = NULL;
932
		const struct object_id *oid;
933
		const char *name;
934
		unsigned mode;
935
		int entlen;
936

937
		if (ce->ce_flags & (CE_STAGEMASK | CE_INTENT_TO_ADD | CE_REMOVE))
938
			BUG("%s with flags 0x%x should not be in cache-tree",
939
			    ce->name, ce->ce_flags);
940
		name = ce->name + path->len;
941
		slash = strchr(name, '/');
942
		if (slash) {
943
			entlen = slash - name;
944
			sub = find_subtree(it, ce->name + path->len, entlen, 0);
945
			if (!sub || sub->cache_tree->entry_count < 0)
946
				BUG("bad subtree '%.*s'", entlen, name);
947
			oid = &sub->cache_tree->oid;
948
			mode = S_IFDIR;
949
			i += sub->cache_tree->entry_count;
950
		} else {
951
			oid = &ce->oid;
952
			mode = ce->ce_mode;
953
			entlen = ce_namelen(ce) - path->len;
954
			i++;
955
		}
956
		strbuf_addf(&tree_buf, "%o %.*s%c", mode, entlen, name, '\0');
957
		strbuf_add(&tree_buf, oid->hash, r->hash_algo->rawsz);
958
	}
959
	hash_object_file(r->hash_algo, tree_buf.buf, tree_buf.len, OBJ_TREE,
960
			 &new_oid);
961
	if (!oideq(&new_oid, &it->oid))
962
		BUG("cache-tree for path %.*s does not match. "
963
		    "Expected %s got %s", len, path->buf,
964
		    oid_to_hex(&new_oid), oid_to_hex(&it->oid));
965
	strbuf_setlen(path, len);
966
	strbuf_release(&tree_buf);
967
	return 0;
968
}
969

970
void cache_tree_verify(struct repository *r, struct index_state *istate)
971
{
972
	struct strbuf path = STRBUF_INIT;
973

974
	if (!istate->cache_tree)
975
		return;
976
	if (verify_one(r, istate, istate->cache_tree, &path)) {
977
		strbuf_reset(&path);
978
		if (verify_one(r, istate, istate->cache_tree, &path))
979
			BUG("ensure_full_index() called twice while verifying cache tree");
980
	}
981
	strbuf_release(&path);
982
}
983