1/*
2 * GIT - The information manager from hell
3 *
4 * Copyright (C) Linus Torvalds, 2005
5 */
6#include "cache.h"
7
8struct cache_entry **active_cache = NULL;
9static time_t index_file_timestamp;
10unsigned int active_nr = 0, active_alloc = 0, active_cache_changed = 0;
11
12/*
13 * This only updates the "non-critical" parts of the directory
14 * cache, ie the parts that aren't tracked by GIT, and only used
15 * to validate the cache.
16 */
17void fill_stat_cache_info(struct cache_entry *ce, struct stat *st)
18{
19 ce->ce_ctime.sec = htonl(st->st_ctime);
20 ce->ce_mtime.sec = htonl(st->st_mtime);
21#ifdef USE_NSEC
22 ce->ce_ctime.nsec = htonl(st->st_ctim.tv_nsec);
23 ce->ce_mtime.nsec = htonl(st->st_mtim.tv_nsec);
24#endif
25 ce->ce_dev = htonl(st->st_dev);
26 ce->ce_ino = htonl(st->st_ino);
27 ce->ce_uid = htonl(st->st_uid);
28 ce->ce_gid = htonl(st->st_gid);
29 ce->ce_size = htonl(st->st_size);
30
31 if (assume_unchanged)
32 ce->ce_flags |= htons(CE_VALID);
33}
34
35static int ce_compare_data(struct cache_entry *ce, struct stat *st)
36{
37 int match = -1;
38 int fd = open(ce->name, O_RDONLY);
39
40 if (fd >= 0) {
41 unsigned char sha1[20];
42 if (!index_fd(sha1, fd, st, 0, NULL))
43 match = memcmp(sha1, ce->sha1, 20);
44 close(fd);
45 }
46 return match;
47}
48
49static int ce_compare_link(struct cache_entry *ce, unsigned long expected_size)
50{
51 int match = -1;
52 char *target;
53 void *buffer;
54 unsigned long size;
55 char type[10];
56 int len;
57
58 target = xmalloc(expected_size);
59 len = readlink(ce->name, target, expected_size);
60 if (len != expected_size) {
61 free(target);
62 return -1;
63 }
64 buffer = read_sha1_file(ce->sha1, type, &size);
65 if (!buffer) {
66 free(target);
67 return -1;
68 }
69 if (size == expected_size)
70 match = memcmp(buffer, target, size);
71 free(buffer);
72 free(target);
73 return match;
74}
75
76static int ce_modified_check_fs(struct cache_entry *ce, struct stat *st)
77{
78 switch (st->st_mode & S_IFMT) {
79 case S_IFREG:
80 if (ce_compare_data(ce, st))
81 return DATA_CHANGED;
82 break;
83 case S_IFLNK:
84 if (ce_compare_link(ce, st->st_size))
85 return DATA_CHANGED;
86 break;
87 default:
88 return TYPE_CHANGED;
89 }
90 return 0;
91}
92
93static int ce_match_stat_basic(struct cache_entry *ce, struct stat *st)
94{
95 unsigned int changed = 0;
96
97 switch (ntohl(ce->ce_mode) & S_IFMT) {
98 case S_IFREG:
99 changed |= !S_ISREG(st->st_mode) ? TYPE_CHANGED : 0;
100 /* We consider only the owner x bit to be relevant for
101 * "mode changes"
102 */
103 if (trust_executable_bit &&
104 (0100 & (ntohl(ce->ce_mode) ^ st->st_mode)))
105 changed |= MODE_CHANGED;
106 break;
107 case S_IFLNK:
108 changed |= !S_ISLNK(st->st_mode) ? TYPE_CHANGED : 0;
109 break;
110 default:
111 die("internal error: ce_mode is %o", ntohl(ce->ce_mode));
112 }
113 if (ce->ce_mtime.sec != htonl(st->st_mtime))
114 changed |= MTIME_CHANGED;
115 if (ce->ce_ctime.sec != htonl(st->st_ctime))
116 changed |= CTIME_CHANGED;
117
118#ifdef USE_NSEC
119 /*
120 * nsec seems unreliable - not all filesystems support it, so
121 * as long as it is in the inode cache you get right nsec
122 * but after it gets flushed, you get zero nsec.
123 */
124 if (ce->ce_mtime.nsec != htonl(st->st_mtim.tv_nsec))
125 changed |= MTIME_CHANGED;
126 if (ce->ce_ctime.nsec != htonl(st->st_ctim.tv_nsec))
127 changed |= CTIME_CHANGED;
128#endif
129
130 if (ce->ce_uid != htonl(st->st_uid) ||
131 ce->ce_gid != htonl(st->st_gid))
132 changed |= OWNER_CHANGED;
133 if (ce->ce_ino != htonl(st->st_ino))
134 changed |= INODE_CHANGED;
135
136#ifdef USE_STDEV
137 /*
138 * st_dev breaks on network filesystems where different
139 * clients will have different views of what "device"
140 * the filesystem is on
141 */
142 if (ce->ce_dev != htonl(st->st_dev))
143 changed |= INODE_CHANGED;
144#endif
145
146 if (ce->ce_size != htonl(st->st_size))
147 changed |= DATA_CHANGED;
148
149 return changed;
150}
151
152int ce_match_stat(struct cache_entry *ce, struct stat *st, int ignore_valid)
153{
154 unsigned int changed;
155
156 /*
157 * If it's marked as always valid in the index, it's
158 * valid whatever the checked-out copy says.
159 */
160 if (!ignore_valid && (ce->ce_flags & htons(CE_VALID)))
161 return 0;
162
163 changed = ce_match_stat_basic(ce, st);
164
165 /*
166 * Within 1 second of this sequence:
167 * echo xyzzy >file && git-update-index --add file
168 * running this command:
169 * echo frotz >file
170 * would give a falsely clean cache entry. The mtime and
171 * length match the cache, and other stat fields do not change.
172 *
173 * We could detect this at update-index time (the cache entry
174 * being registered/updated records the same time as "now")
175 * and delay the return from git-update-index, but that would
176 * effectively mean we can make at most one commit per second,
177 * which is not acceptable. Instead, we check cache entries
178 * whose mtime are the same as the index file timestamp more
179 * carefully than others.
180 */
181 if (!changed &&
182 index_file_timestamp &&
183 index_file_timestamp <= ntohl(ce->ce_mtime.sec))
184 changed |= ce_modified_check_fs(ce, st);
185
186 return changed;
187}
188
189int ce_modified(struct cache_entry *ce, struct stat *st, int really)
190{
191 int changed, changed_fs;
192 changed = ce_match_stat(ce, st, really);
193 if (!changed)
194 return 0;
195 /*
196 * If the mode or type has changed, there's no point in trying
197 * to refresh the entry - it's not going to match
198 */
199 if (changed & (MODE_CHANGED | TYPE_CHANGED))
200 return changed;
201
202 /* Immediately after read-tree or update-index --cacheinfo,
203 * the length field is zero. For other cases the ce_size
204 * should match the SHA1 recorded in the index entry.
205 */
206 if ((changed & DATA_CHANGED) && ce->ce_size != htonl(0))
207 return changed;
208
209 changed_fs = ce_modified_check_fs(ce, st);
210 if (changed_fs)
211 return changed | changed_fs;
212 return 0;
213}
214
215int base_name_compare(const char *name1, int len1, int mode1,
216 const char *name2, int len2, int mode2)
217{
218 unsigned char c1, c2;
219 int len = len1 < len2 ? len1 : len2;
220 int cmp;
221
222 cmp = memcmp(name1, name2, len);
223 if (cmp)
224 return cmp;
225 c1 = name1[len];
226 c2 = name2[len];
227 if (!c1 && S_ISDIR(mode1))
228 c1 = '/';
229 if (!c2 && S_ISDIR(mode2))
230 c2 = '/';
231 return (c1 < c2) ? -1 : (c1 > c2) ? 1 : 0;
232}
233
234int cache_name_compare(const char *name1, int flags1, const char *name2, int flags2)
235{
236 int len1 = flags1 & CE_NAMEMASK;
237 int len2 = flags2 & CE_NAMEMASK;
238 int len = len1 < len2 ? len1 : len2;
239 int cmp;
240
241 cmp = memcmp(name1, name2, len);
242 if (cmp)
243 return cmp;
244 if (len1 < len2)
245 return -1;
246 if (len1 > len2)
247 return 1;
248
249 /* Compare stages */
250 flags1 &= CE_STAGEMASK;
251 flags2 &= CE_STAGEMASK;
252
253 if (flags1 < flags2)
254 return -1;
255 if (flags1 > flags2)
256 return 1;
257 return 0;
258}
259
260int cache_name_pos(const char *name, int namelen)
261{
262 int first, last;
263
264 first = 0;
265 last = active_nr;
266 while (last > first) {
267 int next = (last + first) >> 1;
268 struct cache_entry *ce = active_cache[next];
269 int cmp = cache_name_compare(name, namelen, ce->name, ntohs(ce->ce_flags));
270 if (!cmp)
271 return next;
272 if (cmp < 0) {
273 last = next;
274 continue;
275 }
276 first = next+1;
277 }
278 return -first-1;
279}
280
281/* Remove entry, return true if there are more entries to go.. */
282int remove_cache_entry_at(int pos)
283{
284 active_cache_changed = 1;
285 active_nr--;
286 if (pos >= active_nr)
287 return 0;
288 memmove(active_cache + pos, active_cache + pos + 1, (active_nr - pos) * sizeof(struct cache_entry *));
289 return 1;
290}
291
292int remove_file_from_cache(const char *path)
293{
294 int pos = cache_name_pos(path, strlen(path));
295 if (pos < 0)
296 pos = -pos-1;
297 while (pos < active_nr && !strcmp(active_cache[pos]->name, path))
298 remove_cache_entry_at(pos);
299 return 0;
300}
301
302int ce_same_name(struct cache_entry *a, struct cache_entry *b)
303{
304 int len = ce_namelen(a);
305 return ce_namelen(b) == len && !memcmp(a->name, b->name, len);
306}
307
308int ce_path_match(const struct cache_entry *ce, const char **pathspec)
309{
310 const char *match, *name;
311 int len;
312
313 if (!pathspec)
314 return 1;
315
316 len = ce_namelen(ce);
317 name = ce->name;
318 while ((match = *pathspec++) != NULL) {
319 int matchlen = strlen(match);
320 if (matchlen > len)
321 continue;
322 if (memcmp(name, match, matchlen))
323 continue;
324 if (matchlen && name[matchlen-1] == '/')
325 return 1;
326 if (name[matchlen] == '/' || !name[matchlen])
327 return 1;
328 if (!matchlen)
329 return 1;
330 }
331 return 0;
332}
333
334/*
335 * We fundamentally don't like some paths: we don't want
336 * dot or dot-dot anywhere, and for obvious reasons don't
337 * want to recurse into ".git" either.
338 *
339 * Also, we don't want double slashes or slashes at the
340 * end that can make pathnames ambiguous.
341 */
342static int verify_dotfile(const char *rest)
343{
344 /*
345 * The first character was '.', but that
346 * has already been discarded, we now test
347 * the rest.
348 */
349 switch (*rest) {
350 /* "." is not allowed */
351 case '\0': case '/':
352 return 0;
353
354 /*
355 * ".git" followed by NUL or slash is bad. This
356 * shares the path end test with the ".." case.
357 */
358 case 'g':
359 if (rest[1] != 'i')
360 break;
361 if (rest[2] != 't')
362 break;
363 rest += 2;
364 /* fallthrough */
365 case '.':
366 if (rest[1] == '\0' || rest[1] == '/')
367 return 0;
368 }
369 return 1;
370}
371
372int verify_path(const char *path)
373{
374 char c;
375
376 goto inside;
377 for (;;) {
378 if (!c)
379 return 1;
380 if (c == '/') {
381inside:
382 c = *path++;
383 switch (c) {
384 default:
385 continue;
386 case '/': case '\0':
387 break;
388 case '.':
389 if (verify_dotfile(path))
390 continue;
391 }
392 return 0;
393 }
394 c = *path++;
395 }
396}
397
398/*
399 * Do we have another file that has the beginning components being a
400 * proper superset of the name we're trying to add?
401 */
402static int has_file_name(const struct cache_entry *ce, int pos, int ok_to_replace)
403{
404 int retval = 0;
405 int len = ce_namelen(ce);
406 int stage = ce_stage(ce);
407 const char *name = ce->name;
408
409 while (pos < active_nr) {
410 struct cache_entry *p = active_cache[pos++];
411
412 if (len >= ce_namelen(p))
413 break;
414 if (memcmp(name, p->name, len))
415 break;
416 if (ce_stage(p) != stage)
417 continue;
418 if (p->name[len] != '/')
419 continue;
420 retval = -1;
421 if (!ok_to_replace)
422 break;
423 remove_cache_entry_at(--pos);
424 }
425 return retval;
426}
427
428/*
429 * Do we have another file with a pathname that is a proper
430 * subset of the name we're trying to add?
431 */
432static int has_dir_name(const struct cache_entry *ce, int pos, int ok_to_replace)
433{
434 int retval = 0;
435 int stage = ce_stage(ce);
436 const char *name = ce->name;
437 const char *slash = name + ce_namelen(ce);
438
439 for (;;) {
440 int len;
441
442 for (;;) {
443 if (*--slash == '/')
444 break;
445 if (slash <= ce->name)
446 return retval;
447 }
448 len = slash - name;
449
450 pos = cache_name_pos(name, ntohs(create_ce_flags(len, stage)));
451 if (pos >= 0) {
452 retval = -1;
453 if (ok_to_replace)
454 break;
455 remove_cache_entry_at(pos);
456 continue;
457 }
458
459 /*
460 * Trivial optimization: if we find an entry that
461 * already matches the sub-directory, then we know
462 * we're ok, and we can exit.
463 */
464 pos = -pos-1;
465 while (pos < active_nr) {
466 struct cache_entry *p = active_cache[pos];
467 if ((ce_namelen(p) <= len) ||
468 (p->name[len] != '/') ||
469 memcmp(p->name, name, len))
470 break; /* not our subdirectory */
471 if (ce_stage(p) == stage)
472 /* p is at the same stage as our entry, and
473 * is a subdirectory of what we are looking
474 * at, so we cannot have conflicts at our
475 * level or anything shorter.
476 */
477 return retval;
478 pos++;
479 }
480 }
481 return retval;
482}
483
484/* We may be in a situation where we already have path/file and path
485 * is being added, or we already have path and path/file is being
486 * added. Either one would result in a nonsense tree that has path
487 * twice when git-write-tree tries to write it out. Prevent it.
488 *
489 * If ok-to-replace is specified, we remove the conflicting entries
490 * from the cache so the caller should recompute the insert position.
491 * When this happens, we return non-zero.
492 */
493static int check_file_directory_conflict(const struct cache_entry *ce, int pos, int ok_to_replace)
494{
495 /*
496 * We check if the path is a sub-path of a subsequent pathname
497 * first, since removing those will not change the position
498 * in the array
499 */
500 int retval = has_file_name(ce, pos, ok_to_replace);
501 /*
502 * Then check if the path might have a clashing sub-directory
503 * before it.
504 */
505 return retval + has_dir_name(ce, pos, ok_to_replace);
506}
507
508int add_cache_entry(struct cache_entry *ce, int option)
509{
510 int pos;
511 int ok_to_add = option & ADD_CACHE_OK_TO_ADD;
512 int ok_to_replace = option & ADD_CACHE_OK_TO_REPLACE;
513 int skip_df_check = option & ADD_CACHE_SKIP_DFCHECK;
514
515 pos = cache_name_pos(ce->name, ntohs(ce->ce_flags));
516
517 /* existing match? Just replace it. */
518 if (pos >= 0) {
519 active_cache_changed = 1;
520 active_cache[pos] = ce;
521 return 0;
522 }
523 pos = -pos-1;
524
525 /*
526 * Inserting a merged entry ("stage 0") into the index
527 * will always replace all non-merged entries..
528 */
529 if (pos < active_nr && ce_stage(ce) == 0) {
530 while (ce_same_name(active_cache[pos], ce)) {
531 ok_to_add = 1;
532 if (!remove_cache_entry_at(pos))
533 break;
534 }
535 }
536
537 if (!ok_to_add)
538 return -1;
539 if (!verify_path(ce->name))
540 return -1;
541
542 if (!skip_df_check &&
543 check_file_directory_conflict(ce, pos, ok_to_replace)) {
544 if (!ok_to_replace)
545 return -1;
546 pos = cache_name_pos(ce->name, ntohs(ce->ce_flags));
547 pos = -pos-1;
548 }
549
550 /* Make sure the array is big enough .. */
551 if (active_nr == active_alloc) {
552 active_alloc = alloc_nr(active_alloc);
553 active_cache = xrealloc(active_cache, active_alloc * sizeof(struct cache_entry *));
554 }
555
556 /* Add it in.. */
557 active_nr++;
558 if (active_nr > pos)
559 memmove(active_cache + pos + 1, active_cache + pos, (active_nr - pos - 1) * sizeof(ce));
560 active_cache[pos] = ce;
561 active_cache_changed = 1;
562 return 0;
563}
564
565/* Three functions to allow overloaded pointer return; see linux/err.h */
566static inline void *ERR_PTR(long error)
567{
568 return (void *) error;
569}
570
571static inline long PTR_ERR(const void *ptr)
572{
573 return (long) ptr;
574}
575
576static inline long IS_ERR(const void *ptr)
577{
578 return (unsigned long)ptr > (unsigned long)-1000L;
579}
580
581/*
582 * "refresh" does not calculate a new sha1 file or bring the
583 * cache up-to-date for mode/content changes. But what it
584 * _does_ do is to "re-match" the stat information of a file
585 * with the cache, so that you can refresh the cache for a
586 * file that hasn't been changed but where the stat entry is
587 * out of date.
588 *
589 * For example, you'd want to do this after doing a "git-read-tree",
590 * to link up the stat cache details with the proper files.
591 */
592static struct cache_entry *refresh_entry(struct cache_entry *ce, int really)
593{
594 struct stat st;
595 struct cache_entry *updated;
596 int changed, size;
597
598 if (lstat(ce->name, &st) < 0)
599 return ERR_PTR(-errno);
600
601 changed = ce_match_stat(ce, &st, really);
602 if (!changed) {
603 if (really && assume_unchanged &&
604 !(ce->ce_flags & htons(CE_VALID)))
605 ; /* mark this one VALID again */
606 else
607 return NULL;
608 }
609
610 if (ce_modified(ce, &st, really))
611 return ERR_PTR(-EINVAL);
612
613 size = ce_size(ce);
614 updated = xmalloc(size);
615 memcpy(updated, ce, size);
616 fill_stat_cache_info(updated, &st);
617
618 /* In this case, if really is not set, we should leave
619 * CE_VALID bit alone. Otherwise, paths marked with
620 * --no-assume-unchanged (i.e. things to be edited) will
621 * reacquire CE_VALID bit automatically, which is not
622 * really what we want.
623 */
624 if (!really && assume_unchanged && !(ce->ce_flags & htons(CE_VALID)))
625 updated->ce_flags &= ~htons(CE_VALID);
626
627 return updated;
628}
629
630int refresh_cache(unsigned int flags)
631{
632 int i;
633 int has_errors = 0;
634 int really = (flags & REFRESH_REALLY) != 0;
635 int allow_unmerged = (flags & REFRESH_UNMERGED) != 0;
636 int quiet = (flags & REFRESH_QUIET) != 0;
637 int not_new = (flags & REFRESH_IGNORE_MISSING) != 0;
638
639 for (i = 0; i < active_nr; i++) {
640 struct cache_entry *ce, *new;
641 ce = active_cache[i];
642 if (ce_stage(ce)) {
643 while ((i < active_nr) &&
644 ! strcmp(active_cache[i]->name, ce->name))
645 i++;
646 i--;
647 if (allow_unmerged)
648 continue;
649 printf("%s: needs merge\n", ce->name);
650 has_errors = 1;
651 continue;
652 }
653
654 new = refresh_entry(ce, really);
655 if (!new)
656 continue;
657 if (IS_ERR(new)) {
658 if (not_new && PTR_ERR(new) == -ENOENT)
659 continue;
660 if (really && PTR_ERR(new) == -EINVAL) {
661 /* If we are doing --really-refresh that
662 * means the index is not valid anymore.
663 */
664 ce->ce_flags &= ~htons(CE_VALID);
665 active_cache_changed = 1;
666 }
667 if (quiet)
668 continue;
669 printf("%s: needs update\n", ce->name);
670 has_errors = 1;
671 continue;
672 }
673 active_cache_changed = 1;
674 /* You can NOT just free active_cache[i] here, since it
675 * might not be necessarily malloc()ed but can also come
676 * from mmap(). */
677 active_cache[i] = new;
678 }
679 return has_errors;
680}
681
682static int verify_hdr(struct cache_header *hdr, unsigned long size)
683{
684 SHA_CTX c;
685 unsigned char sha1[20];
686
687 if (hdr->hdr_signature != htonl(CACHE_SIGNATURE))
688 return error("bad signature");
689 if (hdr->hdr_version != htonl(2))
690 return error("bad index version");
691 SHA1_Init(&c);
692 SHA1_Update(&c, hdr, size - 20);
693 SHA1_Final(sha1, &c);
694 if (memcmp(sha1, (void *)hdr + size - 20, 20))
695 return error("bad index file sha1 signature");
696 return 0;
697}
698
699int read_cache(void)
700{
701 int fd, i;
702 struct stat st;
703 unsigned long size, offset;
704 void *map;
705 struct cache_header *hdr;
706
707 errno = EBUSY;
708 if (active_cache)
709 return active_nr;
710
711 errno = ENOENT;
712 index_file_timestamp = 0;
713 fd = open(get_index_file(), O_RDONLY);
714 if (fd < 0) {
715 if (errno == ENOENT)
716 return 0;
717 die("index file open failed (%s)", strerror(errno));
718 }
719
720 size = 0; // avoid gcc warning
721 map = MAP_FAILED;
722 if (!fstat(fd, &st)) {
723 size = st.st_size;
724 errno = EINVAL;
725 if (size >= sizeof(struct cache_header) + 20)
726 map = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
727 }
728 close(fd);
729 if (map == MAP_FAILED)
730 die("index file mmap failed (%s)", strerror(errno));
731
732 hdr = map;
733 if (verify_hdr(hdr, size) < 0)
734 goto unmap;
735
736 active_nr = ntohl(hdr->hdr_entries);
737 active_alloc = alloc_nr(active_nr);
738 active_cache = xcalloc(active_alloc, sizeof(struct cache_entry *));
739
740 offset = sizeof(*hdr);
741 for (i = 0; i < active_nr; i++) {
742 struct cache_entry *ce = map + offset;
743 offset = offset + ce_size(ce);
744 active_cache[i] = ce;
745 }
746 index_file_timestamp = st.st_mtime;
747 return active_nr;
748
749unmap:
750 munmap(map, size);
751 errno = EINVAL;
752 die("index file corrupt");
753}
754
755#define WRITE_BUFFER_SIZE 8192
756static unsigned char write_buffer[WRITE_BUFFER_SIZE];
757static unsigned long write_buffer_len;
758
759static int ce_write(SHA_CTX *context, int fd, void *data, unsigned int len)
760{
761 while (len) {
762 unsigned int buffered = write_buffer_len;
763 unsigned int partial = WRITE_BUFFER_SIZE - buffered;
764 if (partial > len)
765 partial = len;
766 memcpy(write_buffer + buffered, data, partial);
767 buffered += partial;
768 if (buffered == WRITE_BUFFER_SIZE) {
769 SHA1_Update(context, write_buffer, WRITE_BUFFER_SIZE);
770 if (write(fd, write_buffer, WRITE_BUFFER_SIZE) != WRITE_BUFFER_SIZE)
771 return -1;
772 buffered = 0;
773 }
774 write_buffer_len = buffered;
775 len -= partial;
776 data += partial;
777 }
778 return 0;
779}
780
781static int ce_flush(SHA_CTX *context, int fd)
782{
783 unsigned int left = write_buffer_len;
784
785 if (left) {
786 write_buffer_len = 0;
787 SHA1_Update(context, write_buffer, left);
788 }
789
790 /* Flush first if not enough space for SHA1 signature */
791 if (left + 20 > WRITE_BUFFER_SIZE) {
792 if (write(fd, write_buffer, left) != left)
793 return -1;
794 left = 0;
795 }
796
797 /* Append the SHA1 signature at the end */
798 SHA1_Final(write_buffer + left, context);
799 left += 20;
800 if (write(fd, write_buffer, left) != left)
801 return -1;
802 return 0;
803}
804
805static void ce_smudge_racily_clean_entry(struct cache_entry *ce)
806{
807 /*
808 * The only thing we care about in this function is to smudge the
809 * falsely clean entry due to touch-update-touch race, so we leave
810 * everything else as they are. We are called for entries whose
811 * ce_mtime match the index file mtime.
812 */
813 struct stat st;
814
815 if (lstat(ce->name, &st) < 0)
816 return;
817 if (ce_match_stat_basic(ce, &st))
818 return;
819 if (ce_modified_check_fs(ce, &st)) {
820 /* This is "racily clean"; smudge it. Note that this
821 * is a tricky code. At first glance, it may appear
822 * that it can break with this sequence:
823 *
824 * $ echo xyzzy >frotz
825 * $ git-update-index --add frotz
826 * $ : >frotz
827 * $ sleep 3
828 * $ echo filfre >nitfol
829 * $ git-update-index --add nitfol
830 *
831 * but it does not. Whe the second update-index runs,
832 * it notices that the entry "frotz" has the same timestamp
833 * as index, and if we were to smudge it by resetting its
834 * size to zero here, then the object name recorded
835 * in index is the 6-byte file but the cached stat information
836 * becomes zero --- which would then match what we would
837 * obtain from the filesystem next time we stat("frotz").
838 *
839 * However, the second update-index, before calling
840 * this function, notices that the cached size is 6
841 * bytes and what is on the filesystem is an empty
842 * file, and never calls us, so the cached size information
843 * for "frotz" stays 6 which does not match the filesystem.
844 */
845 ce->ce_size = htonl(0);
846 }
847}
848
849int write_cache(int newfd, struct cache_entry **cache, int entries)
850{
851 SHA_CTX c;
852 struct cache_header hdr;
853 int i, removed;
854
855 for (i = removed = 0; i < entries; i++)
856 if (!cache[i]->ce_mode)
857 removed++;
858
859 hdr.hdr_signature = htonl(CACHE_SIGNATURE);
860 hdr.hdr_version = htonl(2);
861 hdr.hdr_entries = htonl(entries - removed);
862
863 SHA1_Init(&c);
864 if (ce_write(&c, newfd, &hdr, sizeof(hdr)) < 0)
865 return -1;
866
867 for (i = 0; i < entries; i++) {
868 struct cache_entry *ce = cache[i];
869 if (!ce->ce_mode)
870 continue;
871 if (index_file_timestamp &&
872 index_file_timestamp <= ntohl(ce->ce_mtime.sec))
873 ce_smudge_racily_clean_entry(ce);
874 if (ce_write(&c, newfd, ce, ce_size(ce)) < 0)
875 return -1;
876 }
877 return ce_flush(&c, newfd);
878}