read-cache.c 26.4 KB
Newer Older
Linus Torvalds's avatar
Linus Torvalds committed
1 2 3 4 5
/*
 * GIT - The information manager from hell
 *
 * Copyright (C) Linus Torvalds, 2005
 */
6
#include "cache.h"
7
#include "cache-tree.h"
8
#include "refs.h"
9 10 11 12 13 14 15 16 17 18 19 20

/* Index extensions.
 *
 * The first letter should be 'A'..'Z' for extensions that are not
 * necessary for a correct operation (i.e. optimization data).
 * When new extensions are added that _needs_ to be understood in
 * order to correctly interpret the index file, pick character that
 * is outside the range, to cause the reader to abort.
 */

#define CACHE_EXT(s) ( (s[0]<<24)|(s[1]<<16)|(s[2]<<8)|(s[3]) )
#define CACHE_EXT_TREE 0x54524545	/* "TREE" */
21

22
struct cache_entry **active_cache;
Junio C Hamano's avatar
Junio C Hamano committed
23
static time_t index_file_timestamp;
24
unsigned int active_nr, active_alloc, active_cache_changed;
25

26
struct cache_tree *active_cache_tree;
27

28 29
static void *cache_mmap;
static size_t cache_mmap_size;
30

31 32 33 34 35 36 37 38 39
/*
 * This only updates the "non-critical" parts of the directory
 * cache, ie the parts that aren't tracked by GIT, and only used
 * to validate the cache.
 */
void fill_stat_cache_info(struct cache_entry *ce, struct stat *st)
{
	ce->ce_ctime.sec = htonl(st->st_ctime);
	ce->ce_mtime.sec = htonl(st->st_mtime);
40
#ifdef USE_NSEC
41 42 43 44 45 46 47 48
	ce->ce_ctime.nsec = htonl(st->st_ctim.tv_nsec);
	ce->ce_mtime.nsec = htonl(st->st_mtim.tv_nsec);
#endif
	ce->ce_dev = htonl(st->st_dev);
	ce->ce_ino = htonl(st->st_ino);
	ce->ce_uid = htonl(st->st_uid);
	ce->ce_gid = htonl(st->st_gid);
	ce->ce_size = htonl(st->st_size);
Junio C Hamano's avatar
Junio C Hamano committed
49 50 51

	if (assume_unchanged)
		ce->ce_flags |= htons(CE_VALID);
52 53
}

Junio C Hamano's avatar
Junio C Hamano committed
54 55 56 57 58 59 60
static int ce_compare_data(struct cache_entry *ce, struct stat *st)
{
	int match = -1;
	int fd = open(ce->name, O_RDONLY);

	if (fd >= 0) {
		unsigned char sha1[20];
61
		if (!index_fd(sha1, fd, st, 0, OBJ_BLOB, ce->name))
62
			match = hashcmp(sha1, ce->sha1);
63
		/* index_fd() closed the file descriptor already */
Junio C Hamano's avatar
Junio C Hamano committed
64 65 66 67
	}
	return match;
}

68
static int ce_compare_link(struct cache_entry *ce, size_t expected_size)
Junio C Hamano's avatar
Junio C Hamano committed
69 70 71 72 73
{
	int match = -1;
	char *target;
	void *buffer;
	unsigned long size;
74
	enum object_type type;
Junio C Hamano's avatar
Junio C Hamano committed
75 76 77 78 79 80 81 82
	int len;

	target = xmalloc(expected_size);
	len = readlink(ce->name, target, expected_size);
	if (len != expected_size) {
		free(target);
		return -1;
	}
83
	buffer = read_sha1_file(ce->sha1, &type, &size);
Junio C Hamano's avatar
Junio C Hamano committed
84 85 86 87 88 89 90 91 92 93 94
	if (!buffer) {
		free(target);
		return -1;
	}
	if (size == expected_size)
		match = memcmp(buffer, target, size);
	free(buffer);
	free(target);
	return match;
}

95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111
static int ce_compare_gitlink(struct cache_entry *ce)
{
	unsigned char sha1[20];

	/*
	 * We don't actually require that the .git directory
	 * under DIRLNK directory be a valid git directory. It
	 * might even be missing (in case nobody populated that
	 * sub-project).
	 *
	 * If so, we consider it always to match.
	 */
	if (resolve_gitlink_ref(ce->name, "HEAD", sha1) < 0)
		return 0;
	return hashcmp(sha1, ce->sha1);
}

Junio C Hamano's avatar
Junio C Hamano committed
112 113 114 115 116 117 118 119
static int ce_modified_check_fs(struct cache_entry *ce, struct stat *st)
{
	switch (st->st_mode & S_IFMT) {
	case S_IFREG:
		if (ce_compare_data(ce, st))
			return DATA_CHANGED;
		break;
	case S_IFLNK:
120
		if (ce_compare_link(ce, xsize_t(st->st_size)))
Junio C Hamano's avatar
Junio C Hamano committed
121 122
			return DATA_CHANGED;
		break;
123 124 125
	case S_IFDIRLNK:
		/* No need to do anything, we did the exact compare in "match_stat_basic" */
		break;
Junio C Hamano's avatar
Junio C Hamano committed
126 127 128 129 130 131
	default:
		return TYPE_CHANGED;
	}
	return 0;
}

Junio C Hamano's avatar
Junio C Hamano committed
132
static int ce_match_stat_basic(struct cache_entry *ce, struct stat *st)
133 134 135
{
	unsigned int changed = 0;

136 137 138
	switch (ntohl(ce->ce_mode) & S_IFMT) {
	case S_IFREG:
		changed |= !S_ISREG(st->st_mode) ? TYPE_CHANGED : 0;
Junio C Hamano's avatar
Junio C Hamano committed
139 140 141 142 143
		/* We consider only the owner x bit to be relevant for
		 * "mode changes"
		 */
		if (trust_executable_bit &&
		    (0100 & (ntohl(ce->ce_mode) ^ st->st_mode)))
144
			changed |= MODE_CHANGED;
145 146
		break;
	case S_IFLNK:
147 148 149
		if (!S_ISLNK(st->st_mode) &&
		    (has_symlinks || !S_ISREG(st->st_mode)))
			changed |= TYPE_CHANGED;
150
		break;
151 152 153 154 155 156
	case S_IFDIRLNK:
		if (!S_ISDIR(st->st_mode))
			changed |= TYPE_CHANGED;
		else if (ce_compare_gitlink(ce))
			changed |= DATA_CHANGED;
		break;
157 158 159
	default:
		die("internal error: ce_mode is %o", ntohl(ce->ce_mode));
	}
160
	if (ce->ce_mtime.sec != htonl(st->st_mtime))
161
		changed |= MTIME_CHANGED;
162 163 164
	if (ce->ce_ctime.sec != htonl(st->st_ctime))
		changed |= CTIME_CHANGED;

165
#ifdef USE_NSEC
166 167 168 169 170
	/*
	 * nsec seems unreliable - not all filesystems support it, so
	 * as long as it is in the inode cache you get right nsec
	 * but after it gets flushed, you get zero nsec.
	 */
171
	if (ce->ce_mtime.nsec != htonl(st->st_mtim.tv_nsec))
172
		changed |= MTIME_CHANGED;
173
	if (ce->ce_ctime.nsec != htonl(st->st_ctim.tv_nsec))
174
		changed |= CTIME_CHANGED;
175 176 177 178
#endif	

	if (ce->ce_uid != htonl(st->st_uid) ||
	    ce->ce_gid != htonl(st->st_gid))
179
		changed |= OWNER_CHANGED;
180
	if (ce->ce_ino != htonl(st->st_ino))
181
		changed |= INODE_CHANGED;
182 183 184 185 186 187 188 189 190 191 192

#ifdef USE_STDEV
	/*
	 * st_dev breaks on network filesystems where different
	 * clients will have different views of what "device"
	 * the filesystem is on
	 */
	if (ce->ce_dev != htonl(st->st_dev))
		changed |= INODE_CHANGED;
#endif

193
	if (ce->ce_size != htonl(st->st_size))
194
		changed |= DATA_CHANGED;
195

Junio C Hamano's avatar
Junio C Hamano committed
196 197 198
	return changed;
}

199
int ce_match_stat(struct cache_entry *ce, struct stat *st, int options)
Junio C Hamano's avatar
Junio C Hamano committed
200
{
Junio C Hamano's avatar
Junio C Hamano committed
201
	unsigned int changed;
202 203
	int ignore_valid = options & 01;
	int assume_racy_is_modified = options & 02;
Junio C Hamano's avatar
Junio C Hamano committed
204 205 206 207 208 209 210 211 212

	/*
	 * If it's marked as always valid in the index, it's
	 * valid whatever the checked-out copy says.
	 */
	if (!ignore_valid && (ce->ce_flags & htons(CE_VALID)))
		return 0;

	changed = ce_match_stat_basic(ce, st);
Junio C Hamano's avatar
Junio C Hamano committed
213

Junio C Hamano's avatar
Junio C Hamano committed
214 215 216 217 218 219 220 221 222 223 224 225 226 227
	/*
	 * Within 1 second of this sequence:
	 * 	echo xyzzy >file && git-update-index --add file
	 * running this command:
	 * 	echo frotz >file
	 * would give a falsely clean cache entry.  The mtime and
	 * length match the cache, and other stat fields do not change.
	 *
	 * We could detect this at update-index time (the cache entry
	 * being registered/updated records the same time as "now")
	 * and delay the return from git-update-index, but that would
	 * effectively mean we can make at most one commit per second,
	 * which is not acceptable.  Instead, we check cache entries
	 * whose mtime are the same as the index file timestamp more
Junio C Hamano's avatar
Junio C Hamano committed
228
	 * carefully than others.
Junio C Hamano's avatar
Junio C Hamano committed
229 230 231
	 */
	if (!changed &&
	    index_file_timestamp &&
232 233 234 235 236 237
	    index_file_timestamp <= ntohl(ce->ce_mtime.sec)) {
		if (assume_racy_is_modified)
			changed |= DATA_CHANGED;
		else
			changed |= ce_modified_check_fs(ce, st);
	}
238

Junio C Hamano's avatar
Junio C Hamano committed
239
	return changed;
240 241
}

Junio C Hamano's avatar
Junio C Hamano committed
242
int ce_modified(struct cache_entry *ce, struct stat *st, int really)
243
{
Junio C Hamano's avatar
Junio C Hamano committed
244
	int changed, changed_fs;
Junio C Hamano's avatar
Junio C Hamano committed
245
	changed = ce_match_stat(ce, st, really);
246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261
	if (!changed)
		return 0;
	/*
	 * If the mode or type has changed, there's no point in trying
	 * to refresh the entry - it's not going to match
	 */
	if (changed & (MODE_CHANGED | TYPE_CHANGED))
		return changed;

	/* Immediately after read-tree or update-index --cacheinfo,
	 * the length field is zero.  For other cases the ce_size
	 * should match the SHA1 recorded in the index entry.
	 */
	if ((changed & DATA_CHANGED) && ce->ce_size != htonl(0))
		return changed;

Junio C Hamano's avatar
Junio C Hamano committed
262 263 264
	changed_fs = ce_modified_check_fs(ce, st);
	if (changed_fs)
		return changed | changed_fs;
265 266 267
	return 0;
}

268 269 270 271 272 273 274 275 276 277 278 279
int base_name_compare(const char *name1, int len1, int mode1,
		      const char *name2, int len2, int mode2)
{
	unsigned char c1, c2;
	int len = len1 < len2 ? len1 : len2;
	int cmp;

	cmp = memcmp(name1, name2, len);
	if (cmp)
		return cmp;
	c1 = name1[len];
	c2 = name2[len];
280
	if (!c1 && S_ISDIR(mode1))
281
		c1 = '/';
282
	if (!c2 && S_ISDIR(mode2))
283 284 285 286
		c2 = '/';
	return (c1 < c2) ? -1 : (c1 > c2) ? 1 : 0;
}

287
int cache_name_compare(const char *name1, int flags1, const char *name2, int flags2)
288
{
289 290
	int len1 = flags1 & CE_NAMEMASK;
	int len2 = flags2 & CE_NAMEMASK;
291 292 293 294 295 296 297 298 299 300
	int len = len1 < len2 ? len1 : len2;
	int cmp;

	cmp = memcmp(name1, name2, len);
	if (cmp)
		return cmp;
	if (len1 < len2)
		return -1;
	if (len1 > len2)
		return 1;
Junio C Hamano's avatar
Junio C Hamano committed
301

302 303 304
	/* Compare stages  */
	flags1 &= CE_STAGEMASK;
	flags2 &= CE_STAGEMASK;
Junio C Hamano's avatar
Junio C Hamano committed
305

306 307 308 309
	if (flags1 < flags2)
		return -1;
	if (flags1 > flags2)
		return 1;
310 311 312 313 314 315 316 317 318 319 320 321
	return 0;
}

int cache_name_pos(const char *name, int namelen)
{
	int first, last;

	first = 0;
	last = active_nr;
	while (last > first) {
		int next = (last + first) >> 1;
		struct cache_entry *ce = active_cache[next];
322
		int cmp = cache_name_compare(name, namelen, ce->name, ntohs(ce->ce_flags));
323
		if (!cmp)
324
			return next;
325 326 327 328 329 330
		if (cmp < 0) {
			last = next;
			continue;
		}
		first = next+1;
	}
331
	return -first-1;
332 333
}

334
/* Remove entry, return true if there are more entries to go.. */
335
int remove_cache_entry_at(int pos)
336
{
337
	active_cache_changed = 1;
338 339 340 341 342 343 344
	active_nr--;
	if (pos >= active_nr)
		return 0;
	memmove(active_cache + pos, active_cache + pos + 1, (active_nr - pos) * sizeof(struct cache_entry *));
	return 1;
}

Junio C Hamano's avatar
Junio C Hamano committed
345
int remove_file_from_cache(const char *path)
346 347
{
	int pos = cache_name_pos(path, strlen(path));
348 349 350
	if (pos < 0)
		pos = -pos-1;
	while (pos < active_nr && !strcmp(active_cache[pos]->name, path))
351
		remove_cache_entry_at(pos);
352 353 354
	return 0;
}

355
int add_file_to_cache(const char *path, int verbose)
Johannes Schindelin's avatar
Johannes Schindelin committed
356 357 358 359 360 361 362 363
{
	int size, namelen;
	struct stat st;
	struct cache_entry *ce;

	if (lstat(path, &st))
		die("%s: unable to stat (%s)", path, strerror(errno));

364 365
	if (!S_ISREG(st.st_mode) && !S_ISLNK(st.st_mode) && !S_ISDIR(st.st_mode))
		die("%s: can only add regular files, symbolic links or git-directories", path);
Johannes Schindelin's avatar
Johannes Schindelin committed
366 367 368 369 370 371 372 373

	namelen = strlen(path);
	size = cache_entry_size(namelen);
	ce = xcalloc(1, size);
	memcpy(ce->name, path, namelen);
	ce->ce_flags = htons(namelen);
	fill_stat_cache_info(ce, &st);

374
	if (trust_executable_bit && has_symlinks)
375 376
		ce->ce_mode = create_ce_mode(st.st_mode);
	else {
377 378
		/* If there is an existing entry, pick the mode bits and type
		 * from it, otherwise assume unexecutable regular file.
Johannes Schindelin's avatar
Johannes Schindelin committed
379
		 */
380
		struct cache_entry *ent;
Johannes Schindelin's avatar
Johannes Schindelin committed
381
		int pos = cache_name_pos(path, namelen);
382 383 384

		ent = (0 <= pos) ? active_cache[pos] : NULL;
		ce->ce_mode = ce_mode_from_stat(ent, st.st_mode);
Johannes Schindelin's avatar
Johannes Schindelin committed
385 386 387 388
	}

	if (index_path(ce->sha1, path, &st, 1))
		die("unable to index file %s", path);
389
	if (add_cache_entry(ce, ADD_CACHE_OK_TO_ADD|ADD_CACHE_OK_TO_REPLACE))
Johannes Schindelin's avatar
Johannes Schindelin committed
390 391 392 393 394 395 396
		die("unable to add %s to index",path);
	if (verbose)
		printf("add '%s'\n", path);
	cache_tree_invalidate_path(active_cache_tree, path);
	return 0;
}

397
int ce_same_name(struct cache_entry *a, struct cache_entry *b)
398 399 400 401 402
{
	int len = ce_namelen(a);
	return ce_namelen(b) == len && !memcmp(a->name, b->name, len);
}

403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422
int ce_path_match(const struct cache_entry *ce, const char **pathspec)
{
	const char *match, *name;
	int len;

	if (!pathspec)
		return 1;

	len = ce_namelen(ce);
	name = ce->name;
	while ((match = *pathspec++) != NULL) {
		int matchlen = strlen(match);
		if (matchlen > len)
			continue;
		if (memcmp(name, match, matchlen))
			continue;
		if (matchlen && name[matchlen-1] == '/')
			return 1;
		if (name[matchlen] == '/' || !name[matchlen])
			return 1;
423 424
		if (!matchlen)
			return 1;
425 426 427 428
	}
	return 0;
}

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
/*
 * We fundamentally don't like some paths: we don't want
 * dot or dot-dot anywhere, and for obvious reasons don't
 * want to recurse into ".git" either.
 *
 * Also, we don't want double slashes or slashes at the
 * end that can make pathnames ambiguous.
 */
static int verify_dotfile(const char *rest)
{
	/*
	 * The first character was '.', but that
	 * has already been discarded, we now test
	 * the rest.
	 */
	switch (*rest) {
	/* "." is not allowed */
	case '\0': case '/':
		return 0;

	/*
	 * ".git" followed by  NUL or slash is bad. This
	 * shares the path end test with the ".." case.
	 */
	case 'g':
		if (rest[1] != 'i')
			break;
		if (rest[2] != 't')
			break;
		rest += 2;
	/* fallthrough */
	case '.':
		if (rest[1] == '\0' || rest[1] == '/')
			return 0;
	}
	return 1;
}

int verify_path(const char *path)
{
	char c;

	goto inside;
	for (;;) {
		if (!c)
			return 1;
		if (c == '/') {
inside:
			c = *path++;
			switch (c) {
			default:
				continue;
			case '/': case '\0':
				break;
			case '.':
				if (verify_dotfile(path))
					continue;
			}
			return 0;
		}
		c = *path++;
	}
}

493 494 495
/*
 * Do we have another file that has the beginning components being a
 * proper superset of the name we're trying to add?
496
 */
497
static int has_file_name(const struct cache_entry *ce, int pos, int ok_to_replace)
498
{
499 500
	int retval = 0;
	int len = ce_namelen(ce);
501
	int stage = ce_stage(ce);
502
	const char *name = ce->name;
503

504 505
	while (pos < active_nr) {
		struct cache_entry *p = active_cache[pos++];
506

507
		if (len >= ce_namelen(p))
508
			break;
509 510
		if (memcmp(name, p->name, len))
			break;
511 512
		if (ce_stage(p) != stage)
			continue;
513 514
		if (p->name[len] != '/')
			continue;
515 516
		if (!ce_stage(p) && !p->ce_mode)
			continue;
517 518 519 520
		retval = -1;
		if (!ok_to_replace)
			break;
		remove_cache_entry_at(--pos);
521
	}
522 523
	return retval;
}
524

525 526 527 528 529 530 531
/*
 * Do we have another file with a pathname that is a proper
 * subset of the name we're trying to add?
 */
static int has_dir_name(const struct cache_entry *ce, int pos, int ok_to_replace)
{
	int retval = 0;
532
	int stage = ce_stage(ce);
533 534
	const char *name = ce->name;
	const char *slash = name + ce_namelen(ce);
535

536 537
	for (;;) {
		int len;
538

539 540 541 542 543 544 545
		for (;;) {
			if (*--slash == '/')
				break;
			if (slash <= ce->name)
				return retval;
		}
		len = slash - name;
546

547
		pos = cache_name_pos(name, ntohs(create_ce_flags(len, stage)));
548
		if (pos >= 0) {
549 550 551 552 553 554 555 556 557 558 559 560 561 562 563
			/*
			 * Found one, but not so fast.  This could
			 * be a marker that says "I was here, but
			 * I am being removed".  Such an entry is
			 * not a part of the resulting tree, and
			 * it is Ok to have a directory at the same
			 * path.
			 */
			if (stage || active_cache[pos]->ce_mode) {
				retval = -1;
				if (!ok_to_replace)
					break;
				remove_cache_entry_at(pos);
				continue;
			}
564
		}
565 566
		else
			pos = -pos-1;
567 568 569 570

		/*
		 * Trivial optimization: if we find an entry that
		 * already matches the sub-directory, then we know
571
		 * we're ok, and we can exit.
572
		 */
573
		while (pos < active_nr) {
574
			struct cache_entry *p = active_cache[pos];
575 576 577 578
			if ((ce_namelen(p) <= len) ||
			    (p->name[len] != '/') ||
			    memcmp(p->name, name, len))
				break; /* not our subdirectory */
579
			if (ce_stage(p) == stage && (stage || p->ce_mode))
580 581 582 583 584 585 586
				/* p is at the same stage as our entry, and
				 * is a subdirectory of what we are looking
				 * at, so we cannot have conflicts at our
				 * level or anything shorter.
				 */
				return retval;
			pos++;
587
		}
588
	}
589 590 591 592 593 594 595 596 597 598 599 600 601 602
	return retval;
}

/* We may be in a situation where we already have path/file and path
 * is being added, or we already have path and path/file is being
 * added.  Either one would result in a nonsense tree that has path
 * twice when git-write-tree tries to write it out.  Prevent it.
 * 
 * If ok-to-replace is specified, we remove the conflicting entries
 * from the cache so the caller should recompute the insert position.
 * When this happens, we return non-zero.
 */
static int check_file_directory_conflict(const struct cache_entry *ce, int pos, int ok_to_replace)
{
603 604 605 606 607 608 609 610
	int retval;

	/*
	 * When ce is an "I am going away" entry, we allow it to be added
	 */
	if (!ce_stage(ce) && !ce->ce_mode)
		return 0;

611 612 613
	/*
	 * We check if the path is a sub-path of a subsequent pathname
	 * first, since removing those will not change the position
614
	 * in the array.
615
	 */
616 617
	retval = has_file_name(ce, pos, ok_to_replace);

618 619 620 621 622
	/*
	 * Then check if the path might have a clashing sub-directory
	 * before it.
	 */
	return retval + has_dir_name(ce, pos, ok_to_replace);
623 624
}

625
int add_cache_entry(struct cache_entry *ce, int option)
626 627
{
	int pos;
628 629
	int ok_to_add = option & ADD_CACHE_OK_TO_ADD;
	int ok_to_replace = option & ADD_CACHE_OK_TO_REPLACE;
630
	int skip_df_check = option & ADD_CACHE_SKIP_DFCHECK;
Junio C Hamano's avatar
Junio C Hamano committed
631

632
	pos = cache_name_pos(ce->name, ntohs(ce->ce_flags));
633

Junio C Hamano's avatar
Junio C Hamano committed
634
	/* existing match? Just replace it. */
635
	if (pos >= 0) {
636
		active_cache_changed = 1;
637
		active_cache[pos] = ce;
638 639
		return 0;
	}
640
	pos = -pos-1;
641

642 643 644 645 646
	/*
	 * Inserting a merged entry ("stage 0") into the index
	 * will always replace all non-merged entries..
	 */
	if (pos < active_nr && ce_stage(ce) == 0) {
647
		while (ce_same_name(active_cache[pos], ce)) {
648
			ok_to_add = 1;
649
			if (!remove_cache_entry_at(pos))
650 651 652 653
				break;
		}
	}

654 655
	if (!ok_to_add)
		return -1;
656 657
	if (!verify_path(ce->name))
		return -1;
658

Junio C Hamano's avatar
Junio C Hamano committed
659 660
	if (!skip_df_check &&
	    check_file_directory_conflict(ce, pos, ok_to_replace)) {
661
		if (!ok_to_replace)
662
			return error("'%s' appears as both a file and as a directory", ce->name);
663
		pos = cache_name_pos(ce->name, ntohs(ce->ce_flags));
664 665
		pos = -pos-1;
	}
666

667 668 669
	/* Make sure the array is big enough .. */
	if (active_nr == active_alloc) {
		active_alloc = alloc_nr(active_alloc);
670
		active_cache = xrealloc(active_cache, active_alloc * sizeof(struct cache_entry *));
671 672 673 674 675 676 677
	}

	/* Add it in.. */
	active_nr++;
	if (active_nr > pos)
		memmove(active_cache + pos + 1, active_cache + pos, (active_nr - pos - 1) * sizeof(ce));
	active_cache[pos] = ce;
678
	active_cache_changed = 1;
679 680 681
	return 0;
}

682 683 684 685 686 687 688 689 690 691 692
/*
 * "refresh" does not calculate a new sha1 file or bring the
 * cache up-to-date for mode/content changes. But what it
 * _does_ do is to "re-match" the stat information of a file
 * with the cache, so that you can refresh the cache for a
 * file that hasn't been changed but where the stat entry is
 * out of date.
 *
 * For example, you'd want to do this after doing a "git-read-tree",
 * to link up the stat cache details with the proper files.
 */
693
static struct cache_entry *refresh_cache_ent(struct cache_entry *ce, int really, int *err)
694 695 696 697 698
{
	struct stat st;
	struct cache_entry *updated;
	int changed, size;

699
	if (lstat(ce->name, &st) < 0) {
700 701
		if (err)
			*err = errno;
702 703
		return NULL;
	}
704 705 706 707 708 709 710

	changed = ce_match_stat(ce, &st, really);
	if (!changed) {
		if (really && assume_unchanged &&
		    !(ce->ce_flags & htons(CE_VALID)))
			; /* mark this one VALID again */
		else
711
			return ce;
712 713
	}

714
	if (ce_modified(ce, &st, really)) {
715 716
		if (err)
			*err = EINVAL;
717 718
		return NULL;
	}
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

	size = ce_size(ce);
	updated = xmalloc(size);
	memcpy(updated, ce, size);
	fill_stat_cache_info(updated, &st);

	/* In this case, if really is not set, we should leave
	 * CE_VALID bit alone.  Otherwise, paths marked with
	 * --no-assume-unchanged (i.e. things to be edited) will
	 * reacquire CE_VALID bit automatically, which is not
	 * really what we want.
	 */
	if (!really && assume_unchanged && !(ce->ce_flags & htons(CE_VALID)))
		updated->ce_flags &= ~htons(CE_VALID);

	return updated;
}

int refresh_cache(unsigned int flags)
{
	int i;
	int has_errors = 0;
	int really = (flags & REFRESH_REALLY) != 0;
	int allow_unmerged = (flags & REFRESH_UNMERGED) != 0;
	int quiet = (flags & REFRESH_QUIET) != 0;
	int not_new = (flags & REFRESH_IGNORE_MISSING) != 0;

	for (i = 0; i < active_nr; i++) {
		struct cache_entry *ce, *new;
748 749
		int cache_errno = 0;

750 751 752 753 754 755 756 757 758 759 760 761 762
		ce = active_cache[i];
		if (ce_stage(ce)) {
			while ((i < active_nr) &&
			       ! strcmp(active_cache[i]->name, ce->name))
				i++;
			i--;
			if (allow_unmerged)
				continue;
			printf("%s: needs merge\n", ce->name);
			has_errors = 1;
			continue;
		}

763
		new = refresh_cache_ent(ce, really, &cache_errno);
764
		if (new == ce)
765
			continue;
766 767
		if (!new) {
			if (not_new && cache_errno == ENOENT)
768
				continue;
769
			if (really && cache_errno == EINVAL) {
770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790
				/* If we are doing --really-refresh that
				 * means the index is not valid anymore.
				 */
				ce->ce_flags &= ~htons(CE_VALID);
				active_cache_changed = 1;
			}
			if (quiet)
				continue;
			printf("%s: needs update\n", ce->name);
			has_errors = 1;
			continue;
		}
		active_cache_changed = 1;
		/* You can NOT just free active_cache[i] here, since it
		 * might not be necessarily malloc()ed but can also come
		 * from mmap(). */
		active_cache[i] = new;
	}
	return has_errors;
}

791 792 793 794 795
struct cache_entry *refresh_cache_entry(struct cache_entry *ce, int really)
{
	return refresh_cache_ent(ce, really, NULL);
}

796
static int verify_hdr(struct cache_header *hdr, unsigned long size)
797 798
{
	SHA_CTX c;
799
	unsigned char sha1[20];
800

801
	if (hdr->hdr_signature != htonl(CACHE_SIGNATURE))
802
		return error("bad signature");
803 804
	if (hdr->hdr_version != htonl(2))
		return error("bad index version");
805
	SHA1_Init(&c);
806
	SHA1_Update(&c, hdr, size - 20);
807
	SHA1_Final(sha1, &c);
808
	if (hashcmp(sha1, (unsigned char *)hdr + size - 20))
809
		return error("bad index file sha1 signature");
810 811 812
	return 0;
}

813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829
static int read_index_extension(const char *ext, void *data, unsigned long sz)
{
	switch (CACHE_EXT(ext)) {
	case CACHE_EXT_TREE:
		active_cache_tree = cache_tree_read(data, sz);
		break;
	default:
		if (*ext < 'A' || 'Z' < *ext)
			return error("index uses %.4s extension, which we do not understand",
				     ext);
		fprintf(stderr, "ignoring %.4s extension\n", ext);
		break;
	}
	return 0;
}

int read_cache(void)
830 831 832 833 834 835
{
	return read_cache_from(get_index_file());
}

/* remember to discard_cache() before reading a different cache! */
int read_cache_from(const char *path)
836 837 838
{
	int fd, i;
	struct stat st;
839
	unsigned long offset;
840 841 842
	struct cache_header *hdr;

	errno = EBUSY;
843
	if (cache_mmap)
844 845
		return active_nr;

846
	errno = ENOENT;
Junio C Hamano's avatar
Junio C Hamano committed
847
	index_file_timestamp = 0;
848
	fd = open(path, O_RDONLY);
849 850 851 852 853
	if (fd < 0) {
		if (errno == ENOENT)
			return 0;
		die("index file open failed (%s)", strerror(errno));
	}
854 855

	if (!fstat(fd, &st)) {
856
		cache_mmap_size = xsize_t(st.st_size);
857
		errno = EINVAL;
858
		if (cache_mmap_size >= sizeof(struct cache_header) + 20)
859
			cache_mmap = xmmap(NULL, cache_mmap_size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
860 861 862 863
		else
			die("index file smaller than expected");
	} else
		die("cannot stat the open index (%s)", strerror(errno));
864 865
	close(fd);

866 867
	hdr = cache_mmap;
	if (verify_hdr(hdr, cache_mmap_size) < 0)
868 869
		goto unmap;

870
	active_nr = ntohl(hdr->hdr_entries);
871
	active_alloc = alloc_nr(active_nr);
872
	active_cache = xcalloc(active_alloc, sizeof(struct cache_entry *));
873 874

	offset = sizeof(*hdr);
875
	for (i = 0; i < active_nr; i++) {
876
		struct cache_entry *ce = (struct cache_entry *) ((char *) cache_mmap + offset);
877 878 879
		offset = offset + ce_size(ce);
		active_cache[i] = ce;
	}
Junio C Hamano's avatar
Junio C Hamano committed
880
	index_file_timestamp = st.st_mtime;
881
	while (offset <= cache_mmap_size - 20 - 8) {
882 883 884 885 886 887 888
		/* After an array of active_nr index entries,
		 * there can be arbitrary number of extended
		 * sections, each of which is prefixed with
		 * extension name (4-byte) and section length
		 * in 4-byte network byte order.
		 */
		unsigned long extsize;
889
		memcpy(&extsize, (char *) cache_mmap + offset + 4, 4);
890
		extsize = ntohl(extsize);
891 892
		if (read_index_extension(((const char *) cache_mmap) + offset,
					 (char *) cache_mmap + offset + 8,
893
					 extsize) < 0)
894 895 896 897
			goto unmap;
		offset += 8;
		offset += extsize;
	}
898 899 900
	return active_nr;

unmap:
901
	munmap(cache_mmap, cache_mmap_size);
902
	errno = EINVAL;
903
	die("index file corrupt");
904 905
}

906
int discard_cache(void)
907 908 909
{
	int ret;

910 911 912
	active_nr = active_cache_changed = 0;
	index_file_timestamp = 0;
	cache_tree_free(&active_cache_tree);
913 914 915 916 917 918 919 920 921 922
	if (cache_mmap == NULL)
		return 0;
	ret = munmap(cache_mmap, cache_mmap_size);
	cache_mmap = NULL;
	cache_mmap_size = 0;

	/* no need to throw away allocated active_cache */
	return ret;
}

923
#define WRITE_BUFFER_SIZE 8192
924
static unsigned char write_buffer[WRITE_BUFFER_SIZE];
925 926
static unsigned long write_buffer_len;

927 928 929 930 931
static int ce_write_flush(SHA_CTX *context, int fd)
{
	unsigned int buffered = write_buffer_len;
	if (buffered) {
		SHA1_Update(context, write_buffer, buffered);
932
		if (write_in_full(fd, write_buffer, buffered) != buffered)
933 934 935 936 937 938
			return -1;
		write_buffer_len = 0;
	}
	return 0;
}

939
static int ce_write(SHA_CTX *context, int fd, void *data, unsigned int len)
940 941 942 943 944 945 946 947 948
{
	while (len) {
		unsigned int buffered = write_buffer_len;
		unsigned int partial = WRITE_BUFFER_SIZE - buffered;
		if (partial > len)
			partial = len;
		memcpy(write_buffer + buffered, data, partial);
		buffered += partial;
		if (buffered == WRITE_BUFFER_SIZE) {
949 950
			write_buffer_len = buffered;
			if (ce_write_flush(context, fd))
951 952 953 954 955
				return -1;
			buffered = 0;
		}
		write_buffer_len = buffered;
		len -= partial;
956
		data = (char *) data + partial;
957 958 959 960
 	}
 	return 0;
}

961
static int write_index_ext_header(SHA_CTX *context, int fd,
962
				  unsigned int ext, unsigned int sz)
963 964 965
{
	ext = htonl(ext);
	sz = htonl(sz);
David Rientjes's avatar
David Rientjes committed
966 967
	return ((ce_write(context, fd, &ext, 4) < 0) ||
		(ce_write(context, fd, &sz, 4) < 0)) ? -1 : 0;
968 969 970
}

static int ce_flush(SHA_CTX *context, int fd)
971 972
{
	unsigned int left = write_buffer_len;
973

974 975
	if (left) {
		write_buffer_len = 0;
976
		SHA1_Update(context, write_buffer, left);
977
	}
978

979 980
	/* Flush first if not enough space for SHA1 signature */
	if (left + 20 > WRITE_BUFFER_SIZE) {
981
		if (write_in_full(fd, write_buffer, left) != left)
982 983 984 985
			return -1;
		left = 0;
	}

986
	/* Append the SHA1 signature at the end */
987
	SHA1_Final(write_buffer + left, context);
988
	left += 20;
989
	return (write_in_full(fd, write_buffer, left) != left) ? -1 : 0;
990 991
}

Junio C Hamano's avatar
Junio C Hamano committed
992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006
static void ce_smudge_racily_clean_entry(struct cache_entry *ce)
{
	/*
	 * The only thing we care about in this function is to smudge the
	 * falsely clean entry due to touch-update-touch race, so we leave
	 * everything else as they are.  We are called for entries whose
	 * ce_mtime match the index file mtime.
	 */
	struct stat st;

	if (lstat(ce->name, &st) < 0)
		return;
	if (ce_match_stat_basic(ce, &st))
		return;
	if (ce_modified_check_fs(ce, &st)) {
1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017
		/* This is "racily clean"; smudge it.  Note that this
		 * is a tricky code.  At first glance, it may appear
		 * that it can break with this sequence:
		 *
		 * $ echo xyzzy >frotz
		 * $ git-update-index --add frotz
		 * $ : >frotz
		 * $ sleep 3
		 * $ echo filfre >nitfol
		 * $ git-update-index --add nitfol
		 *
1018
		 * but it does not.  When the second update-index runs,
1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031
		 * it notices that the entry "frotz" has the same timestamp
		 * as index, and if we were to smudge it by resetting its
		 * size to zero here, then the object name recorded
		 * in index is the 6-byte file but the cached stat information
		 * becomes zero --- which would then match what we would
		 * obtain from the filesystem next time we stat("frotz"). 
		 *
		 * However, the second update-index, before calling
		 * this function, notices that the cached size is 6
		 * bytes and what is on the filesystem is an empty
		 * file, and never calls us, so the cached size information
		 * for "frotz" stays 6 which does not match the filesystem.
		 */
Junio C Hamano's avatar
Junio C Hamano committed
1032 1033 1034 1035
		ce->ce_size = htonl(0);
	}
}

1036
int write_cache(int newfd, struct cache_entry **cache, int entries)
1037 1038 1039
{
	SHA_CTX c;
	struct cache_header hdr;
1040
	int i, removed;
1041 1042 1043 1044

	for (i = removed = 0; i < entries; i++)
		if (!cache[i]->ce_mode)
			removed++;
1045

1046
	hdr.hdr_signature = htonl(CACHE_SIGNATURE);
1047
	hdr.hdr_version = htonl(2);
1048
	hdr.hdr_entries = htonl(entries - removed);
1049 1050

	SHA1_Init(&c);
1051
	if (ce_write(&c, newfd, &hdr, sizeof(hdr)) < 0)
1052 1053 1054 1055
		return -1;

	for (i = 0; i < entries; i++) {
		struct cache_entry *ce = cache[i];
1056 1057
		if (!ce->ce_mode)
			continue;
1058 1059
		if (index_file_timestamp &&
		    index_file_timestamp <= ntohl(ce->ce_mtime.sec))
Junio C Hamano's avatar
Junio C Hamano committed
1060
			ce_smudge_racily_clean_entry(ce);
1061
		if (ce_write(&c, newfd, ce, ce_size(ce)) < 0)
1062 1063
			return -1;
	}
1064

1065 1066 1067 1068 1069 1070 1071
	/* Write extension data here */
	if (active_cache_tree) {
		unsigned long sz;
		void *data = cache_tree_write(active_cache_tree, &sz);
		if (data &&
		    !write_index_ext_header(&c, newfd, CACHE_EXT_TREE, sz) &&
		    !ce_write(&c, newfd, data, sz))
1072
			free(data);
1073 1074 1075 1076 1077 1078
		else {
			free(data);
			return -1;
		}
	}
	return ce_flush(&c, newfd);
1079
}