Merge branch 'jc/add'
[git/mingw.git] / read-cache.c
blobd2f332a6222cc3543bde8fa661c54c5c904cf561
1 /*
2 * GIT - The information manager from hell
4 * Copyright (C) Linus Torvalds, 2005
5 */
6 #include "cache.h"
7 #include "cache-tree.h"
8 #include "refs.h"
10 /* Index extensions.
12 * The first letter should be 'A'..'Z' for extensions that are not
13 * necessary for a correct operation (i.e. optimization data).
14 * When new extensions are added that _needs_ to be understood in
15 * order to correctly interpret the index file, pick character that
16 * is outside the range, to cause the reader to abort.
19 #define CACHE_EXT(s) ( (s[0]<<24)|(s[1]<<16)|(s[2]<<8)|(s[3]) )
20 #define CACHE_EXT_TREE 0x54524545 /* "TREE" */
22 struct cache_entry **active_cache;
23 static time_t index_file_timestamp;
24 unsigned int active_nr, active_alloc, active_cache_changed;
26 struct cache_tree *active_cache_tree;
28 static void *cache_mmap;
29 static size_t cache_mmap_size;
32 * This only updates the "non-critical" parts of the directory
33 * cache, ie the parts that aren't tracked by GIT, and only used
34 * to validate the cache.
36 void fill_stat_cache_info(struct cache_entry *ce, struct stat *st)
38 ce->ce_ctime.sec = htonl(st->st_ctime);
39 ce->ce_mtime.sec = htonl(st->st_mtime);
40 #ifdef USE_NSEC
41 ce->ce_ctime.nsec = htonl(st->st_ctim.tv_nsec);
42 ce->ce_mtime.nsec = htonl(st->st_mtim.tv_nsec);
43 #endif
44 ce->ce_dev = htonl(st->st_dev);
45 ce->ce_ino = htonl(st->st_ino);
46 ce->ce_uid = htonl(st->st_uid);
47 ce->ce_gid = htonl(st->st_gid);
48 ce->ce_size = htonl(st->st_size);
50 if (assume_unchanged)
51 ce->ce_flags |= htons(CE_VALID);
54 static int ce_compare_data(struct cache_entry *ce, struct stat *st)
56 int match = -1;
57 int fd = open(ce->name, O_RDONLY);
59 if (fd >= 0) {
60 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 */
65 return match;
68 static int ce_compare_link(struct cache_entry *ce, size_t expected_size)
70 int match = -1;
71 char *target;
72 void *buffer;
73 unsigned long size;
74 enum object_type type;
75 int len;
77 target = xmalloc(expected_size);
78 len = readlink(ce->name, target, expected_size);
79 if (len != expected_size) {
80 free(target);
81 return -1;
83 buffer = read_sha1_file(ce->sha1, &type, &size);
84 if (!buffer) {
85 free(target);
86 return -1;
88 if (size == expected_size)
89 match = memcmp(buffer, target, size);
90 free(buffer);
91 free(target);
92 return match;
95 static int ce_compare_gitlink(struct cache_entry *ce)
97 unsigned char sha1[20];
100 * We don't actually require that the .git directory
101 * under DIRLNK directory be a valid git directory. It
102 * might even be missing (in case nobody populated that
103 * sub-project).
105 * If so, we consider it always to match.
107 if (resolve_gitlink_ref(ce->name, "HEAD", sha1) < 0)
108 return 0;
109 return hashcmp(sha1, ce->sha1);
112 static int ce_modified_check_fs(struct cache_entry *ce, struct stat *st)
114 switch (st->st_mode & S_IFMT) {
115 case S_IFREG:
116 if (ce_compare_data(ce, st))
117 return DATA_CHANGED;
118 break;
119 case S_IFLNK:
120 if (ce_compare_link(ce, xsize_t(st->st_size)))
121 return DATA_CHANGED;
122 break;
123 case S_IFDIR:
124 if (S_ISDIRLNK(ntohl(ce->ce_mode)))
125 return 0;
126 default:
127 return TYPE_CHANGED;
129 return 0;
132 static int ce_match_stat_basic(struct cache_entry *ce, struct stat *st)
134 unsigned int changed = 0;
136 switch (ntohl(ce->ce_mode) & S_IFMT) {
137 case S_IFREG:
138 changed |= !S_ISREG(st->st_mode) ? TYPE_CHANGED : 0;
139 /* We consider only the owner x bit to be relevant for
140 * "mode changes"
142 if (trust_executable_bit &&
143 (0100 & (ntohl(ce->ce_mode) ^ st->st_mode)))
144 changed |= MODE_CHANGED;
145 break;
146 case S_IFLNK:
147 if (!S_ISLNK(st->st_mode) &&
148 (has_symlinks || !S_ISREG(st->st_mode)))
149 changed |= TYPE_CHANGED;
150 break;
151 case S_IFDIRLNK:
152 if (!S_ISDIR(st->st_mode))
153 changed |= TYPE_CHANGED;
154 else if (ce_compare_gitlink(ce))
155 changed |= DATA_CHANGED;
156 return changed;
157 default:
158 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 if (ce->ce_ctime.sec != htonl(st->st_ctime))
163 changed |= CTIME_CHANGED;
165 #ifdef USE_NSEC
167 * nsec seems unreliable - not all filesystems support it, so
168 * as long as it is in the inode cache you get right nsec
169 * 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 #endif
177 if (ce->ce_uid != htonl(st->st_uid) ||
178 ce->ce_gid != htonl(st->st_gid))
179 changed |= OWNER_CHANGED;
180 if (ce->ce_ino != htonl(st->st_ino))
181 changed |= INODE_CHANGED;
183 #ifdef USE_STDEV
185 * st_dev breaks on network filesystems where different
186 * clients will have different views of what "device"
187 * the filesystem is on
189 if (ce->ce_dev != htonl(st->st_dev))
190 changed |= INODE_CHANGED;
191 #endif
193 if (ce->ce_size != htonl(st->st_size))
194 changed |= DATA_CHANGED;
196 return changed;
199 int ce_match_stat(struct cache_entry *ce, struct stat *st, int options)
201 unsigned int changed;
202 int ignore_valid = options & 01;
203 int assume_racy_is_modified = options & 02;
206 * If it's marked as always valid in the index, it's
207 * valid whatever the checked-out copy says.
209 if (!ignore_valid && (ce->ce_flags & htons(CE_VALID)))
210 return 0;
212 changed = ce_match_stat_basic(ce, st);
215 * Within 1 second of this sequence:
216 * echo xyzzy >file && git-update-index --add file
217 * running this command:
218 * echo frotz >file
219 * would give a falsely clean cache entry. The mtime and
220 * length match the cache, and other stat fields do not change.
222 * We could detect this at update-index time (the cache entry
223 * being registered/updated records the same time as "now")
224 * and delay the return from git-update-index, but that would
225 * effectively mean we can make at most one commit per second,
226 * which is not acceptable. Instead, we check cache entries
227 * whose mtime are the same as the index file timestamp more
228 * carefully than others.
230 if (!changed &&
231 index_file_timestamp &&
232 index_file_timestamp <= ntohl(ce->ce_mtime.sec)) {
233 if (assume_racy_is_modified)
234 changed |= DATA_CHANGED;
235 else
236 changed |= ce_modified_check_fs(ce, st);
239 return changed;
242 int ce_modified(struct cache_entry *ce, struct stat *st, int really)
244 int changed, changed_fs;
245 changed = ce_match_stat(ce, st, really);
246 if (!changed)
247 return 0;
249 * If the mode or type has changed, there's no point in trying
250 * to refresh the entry - it's not going to match
252 if (changed & (MODE_CHANGED | TYPE_CHANGED))
253 return changed;
255 /* Immediately after read-tree or update-index --cacheinfo,
256 * the length field is zero. For other cases the ce_size
257 * should match the SHA1 recorded in the index entry.
259 if ((changed & DATA_CHANGED) && ce->ce_size != htonl(0))
260 return changed;
262 changed_fs = ce_modified_check_fs(ce, st);
263 if (changed_fs)
264 return changed | changed_fs;
265 return 0;
268 int base_name_compare(const char *name1, int len1, int mode1,
269 const char *name2, int len2, int mode2)
271 unsigned char c1, c2;
272 int len = len1 < len2 ? len1 : len2;
273 int cmp;
275 cmp = memcmp(name1, name2, len);
276 if (cmp)
277 return cmp;
278 c1 = name1[len];
279 c2 = name2[len];
280 if (!c1 && S_ISDIR(mode1))
281 c1 = '/';
282 if (!c2 && S_ISDIR(mode2))
283 c2 = '/';
284 return (c1 < c2) ? -1 : (c1 > c2) ? 1 : 0;
287 int cache_name_compare(const char *name1, int flags1, const char *name2, int flags2)
289 int len1 = flags1 & CE_NAMEMASK;
290 int len2 = flags2 & CE_NAMEMASK;
291 int len = len1 < len2 ? len1 : len2;
292 int cmp;
294 cmp = memcmp(name1, name2, len);
295 if (cmp)
296 return cmp;
297 if (len1 < len2)
298 return -1;
299 if (len1 > len2)
300 return 1;
302 /* Compare stages */
303 flags1 &= CE_STAGEMASK;
304 flags2 &= CE_STAGEMASK;
306 if (flags1 < flags2)
307 return -1;
308 if (flags1 > flags2)
309 return 1;
310 return 0;
313 int cache_name_pos(const char *name, int namelen)
315 int first, last;
317 first = 0;
318 last = active_nr;
319 while (last > first) {
320 int next = (last + first) >> 1;
321 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 if (cmp < 0) {
326 last = next;
327 continue;
329 first = next+1;
331 return -first-1;
334 /* Remove entry, return true if there are more entries to go.. */
335 int remove_cache_entry_at(int pos)
337 active_cache_changed = 1;
338 active_nr--;
339 if (pos >= active_nr)
340 return 0;
341 memmove(active_cache + pos, active_cache + pos + 1, (active_nr - pos) * sizeof(struct cache_entry *));
342 return 1;
345 int remove_file_from_cache(const char *path)
347 int pos = cache_name_pos(path, strlen(path));
348 if (pos < 0)
349 pos = -pos-1;
350 while (pos < active_nr && !strcmp(active_cache[pos]->name, path))
351 remove_cache_entry_at(pos);
352 return 0;
355 int add_file_to_cache(const char *path, int verbose)
357 int size, namelen;
358 struct stat st;
359 struct cache_entry *ce;
361 if (lstat(path, &st))
362 die("%s: unable to stat (%s)", path, strerror(errno));
364 if (!S_ISREG(st.st_mode) && !S_ISLNK(st.st_mode) && !S_ISDIR(st.st_mode))
365 die("%s: can only add regular files, symbolic links or git-directories", path);
367 namelen = strlen(path);
368 if (S_ISDIR(st.st_mode)) {
369 while (namelen && path[namelen-1] == '/')
370 namelen--;
372 size = cache_entry_size(namelen);
373 ce = xcalloc(1, size);
374 memcpy(ce->name, path, namelen);
375 ce->ce_flags = htons(namelen);
376 fill_stat_cache_info(ce, &st);
378 if (trust_executable_bit && has_symlinks)
379 ce->ce_mode = create_ce_mode(st.st_mode);
380 else {
381 /* If there is an existing entry, pick the mode bits and type
382 * from it, otherwise assume unexecutable regular file.
384 struct cache_entry *ent;
385 int pos = cache_name_pos(path, namelen);
387 ent = (0 <= pos) ? active_cache[pos] : NULL;
388 ce->ce_mode = ce_mode_from_stat(ent, st.st_mode);
391 if (index_path(ce->sha1, path, &st, 1))
392 die("unable to index file %s", path);
393 if (add_cache_entry(ce, ADD_CACHE_OK_TO_ADD|ADD_CACHE_OK_TO_REPLACE))
394 die("unable to add %s to index",path);
395 if (verbose)
396 printf("add '%s'\n", path);
397 cache_tree_invalidate_path(active_cache_tree, path);
398 return 0;
401 int ce_same_name(struct cache_entry *a, struct cache_entry *b)
403 int len = ce_namelen(a);
404 return ce_namelen(b) == len && !memcmp(a->name, b->name, len);
407 int ce_path_match(const struct cache_entry *ce, const char **pathspec)
409 const char *match, *name;
410 int len;
412 if (!pathspec)
413 return 1;
415 len = ce_namelen(ce);
416 name = ce->name;
417 while ((match = *pathspec++) != NULL) {
418 int matchlen = strlen(match);
419 if (matchlen > len)
420 continue;
421 if (memcmp(name, match, matchlen))
422 continue;
423 if (matchlen && name[matchlen-1] == '/')
424 return 1;
425 if (name[matchlen] == '/' || !name[matchlen])
426 return 1;
427 if (!matchlen)
428 return 1;
430 return 0;
434 * We fundamentally don't like some paths: we don't want
435 * dot or dot-dot anywhere, and for obvious reasons don't
436 * want to recurse into ".git" either.
438 * Also, we don't want double slashes or slashes at the
439 * end that can make pathnames ambiguous.
441 static int verify_dotfile(const char *rest)
444 * The first character was '.', but that
445 * has already been discarded, we now test
446 * the rest.
448 switch (*rest) {
449 /* "." is not allowed */
450 case '\0': case '/':
451 return 0;
454 * ".git" followed by NUL or slash is bad. This
455 * shares the path end test with the ".." case.
457 case 'g':
458 if (rest[1] != 'i')
459 break;
460 if (rest[2] != 't')
461 break;
462 rest += 2;
463 /* fallthrough */
464 case '.':
465 if (rest[1] == '\0' || rest[1] == '/')
466 return 0;
468 return 1;
471 int verify_path(const char *path)
473 char c;
475 goto inside;
476 for (;;) {
477 if (!c)
478 return 1;
479 if (c == '/') {
480 inside:
481 c = *path++;
482 switch (c) {
483 default:
484 continue;
485 case '/': case '\0':
486 break;
487 case '.':
488 if (verify_dotfile(path))
489 continue;
491 return 0;
493 c = *path++;
498 * Do we have another file that has the beginning components being a
499 * proper superset of the name we're trying to add?
501 static int has_file_name(const struct cache_entry *ce, int pos, int ok_to_replace)
503 int retval = 0;
504 int len = ce_namelen(ce);
505 int stage = ce_stage(ce);
506 const char *name = ce->name;
508 while (pos < active_nr) {
509 struct cache_entry *p = active_cache[pos++];
511 if (len >= ce_namelen(p))
512 break;
513 if (memcmp(name, p->name, len))
514 break;
515 if (ce_stage(p) != stage)
516 continue;
517 if (p->name[len] != '/')
518 continue;
519 if (!ce_stage(p) && !p->ce_mode)
520 continue;
521 retval = -1;
522 if (!ok_to_replace)
523 break;
524 remove_cache_entry_at(--pos);
526 return retval;
530 * Do we have another file with a pathname that is a proper
531 * subset of the name we're trying to add?
533 static int has_dir_name(const struct cache_entry *ce, int pos, int ok_to_replace)
535 int retval = 0;
536 int stage = ce_stage(ce);
537 const char *name = ce->name;
538 const char *slash = name + ce_namelen(ce);
540 for (;;) {
541 int len;
543 for (;;) {
544 if (*--slash == '/')
545 break;
546 if (slash <= ce->name)
547 return retval;
549 len = slash - name;
551 pos = cache_name_pos(name, ntohs(create_ce_flags(len, stage)));
552 if (pos >= 0) {
554 * Found one, but not so fast. This could
555 * be a marker that says "I was here, but
556 * I am being removed". Such an entry is
557 * not a part of the resulting tree, and
558 * it is Ok to have a directory at the same
559 * path.
561 if (stage || active_cache[pos]->ce_mode) {
562 retval = -1;
563 if (!ok_to_replace)
564 break;
565 remove_cache_entry_at(pos);
566 continue;
569 else
570 pos = -pos-1;
573 * Trivial optimization: if we find an entry that
574 * already matches the sub-directory, then we know
575 * we're ok, and we can exit.
577 while (pos < active_nr) {
578 struct cache_entry *p = active_cache[pos];
579 if ((ce_namelen(p) <= len) ||
580 (p->name[len] != '/') ||
581 memcmp(p->name, name, len))
582 break; /* not our subdirectory */
583 if (ce_stage(p) == stage && (stage || p->ce_mode))
584 /* p is at the same stage as our entry, and
585 * is a subdirectory of what we are looking
586 * at, so we cannot have conflicts at our
587 * level or anything shorter.
589 return retval;
590 pos++;
593 return retval;
596 /* We may be in a situation where we already have path/file and path
597 * is being added, or we already have path and path/file is being
598 * added. Either one would result in a nonsense tree that has path
599 * twice when git-write-tree tries to write it out. Prevent it.
601 * If ok-to-replace is specified, we remove the conflicting entries
602 * from the cache so the caller should recompute the insert position.
603 * When this happens, we return non-zero.
605 static int check_file_directory_conflict(const struct cache_entry *ce, int pos, int ok_to_replace)
607 int retval;
610 * When ce is an "I am going away" entry, we allow it to be added
612 if (!ce_stage(ce) && !ce->ce_mode)
613 return 0;
616 * We check if the path is a sub-path of a subsequent pathname
617 * first, since removing those will not change the position
618 * in the array.
620 retval = has_file_name(ce, pos, ok_to_replace);
623 * Then check if the path might have a clashing sub-directory
624 * before it.
626 return retval + has_dir_name(ce, pos, ok_to_replace);
629 int add_cache_entry(struct cache_entry *ce, int option)
631 int pos;
632 int ok_to_add = option & ADD_CACHE_OK_TO_ADD;
633 int ok_to_replace = option & ADD_CACHE_OK_TO_REPLACE;
634 int skip_df_check = option & ADD_CACHE_SKIP_DFCHECK;
636 pos = cache_name_pos(ce->name, ntohs(ce->ce_flags));
638 /* existing match? Just replace it. */
639 if (pos >= 0) {
640 active_cache_changed = 1;
641 active_cache[pos] = ce;
642 return 0;
644 pos = -pos-1;
647 * Inserting a merged entry ("stage 0") into the index
648 * will always replace all non-merged entries..
650 if (pos < active_nr && ce_stage(ce) == 0) {
651 while (ce_same_name(active_cache[pos], ce)) {
652 ok_to_add = 1;
653 if (!remove_cache_entry_at(pos))
654 break;
658 if (!ok_to_add)
659 return -1;
660 if (!verify_path(ce->name))
661 return -1;
663 if (!skip_df_check &&
664 check_file_directory_conflict(ce, pos, ok_to_replace)) {
665 if (!ok_to_replace)
666 return error("'%s' appears as both a file and as a directory", ce->name);
667 pos = cache_name_pos(ce->name, ntohs(ce->ce_flags));
668 pos = -pos-1;
671 /* Make sure the array is big enough .. */
672 if (active_nr == active_alloc) {
673 active_alloc = alloc_nr(active_alloc);
674 active_cache = xrealloc(active_cache, active_alloc * sizeof(struct cache_entry *));
677 /* Add it in.. */
678 active_nr++;
679 if (active_nr > pos)
680 memmove(active_cache + pos + 1, active_cache + pos, (active_nr - pos - 1) * sizeof(ce));
681 active_cache[pos] = ce;
682 active_cache_changed = 1;
683 return 0;
687 * "refresh" does not calculate a new sha1 file or bring the
688 * cache up-to-date for mode/content changes. But what it
689 * _does_ do is to "re-match" the stat information of a file
690 * with the cache, so that you can refresh the cache for a
691 * file that hasn't been changed but where the stat entry is
692 * out of date.
694 * For example, you'd want to do this after doing a "git-read-tree",
695 * to link up the stat cache details with the proper files.
697 static struct cache_entry *refresh_cache_ent(struct cache_entry *ce, int really, int *err)
699 struct stat st;
700 struct cache_entry *updated;
701 int changed, size;
703 if (lstat(ce->name, &st) < 0) {
704 if (err)
705 *err = errno;
706 return NULL;
709 changed = ce_match_stat(ce, &st, really);
710 if (!changed) {
711 if (really && assume_unchanged &&
712 !(ce->ce_flags & htons(CE_VALID)))
713 ; /* mark this one VALID again */
714 else
715 return ce;
718 if (ce_modified(ce, &st, really)) {
719 if (err)
720 *err = EINVAL;
721 return NULL;
724 size = ce_size(ce);
725 updated = xmalloc(size);
726 memcpy(updated, ce, size);
727 fill_stat_cache_info(updated, &st);
729 /* In this case, if really is not set, we should leave
730 * CE_VALID bit alone. Otherwise, paths marked with
731 * --no-assume-unchanged (i.e. things to be edited) will
732 * reacquire CE_VALID bit automatically, which is not
733 * really what we want.
735 if (!really && assume_unchanged && !(ce->ce_flags & htons(CE_VALID)))
736 updated->ce_flags &= ~htons(CE_VALID);
738 return updated;
741 int refresh_cache(unsigned int flags)
743 int i;
744 int has_errors = 0;
745 int really = (flags & REFRESH_REALLY) != 0;
746 int allow_unmerged = (flags & REFRESH_UNMERGED) != 0;
747 int quiet = (flags & REFRESH_QUIET) != 0;
748 int not_new = (flags & REFRESH_IGNORE_MISSING) != 0;
750 for (i = 0; i < active_nr; i++) {
751 struct cache_entry *ce, *new;
752 int cache_errno = 0;
754 ce = active_cache[i];
755 if (ce_stage(ce)) {
756 while ((i < active_nr) &&
757 ! strcmp(active_cache[i]->name, ce->name))
758 i++;
759 i--;
760 if (allow_unmerged)
761 continue;
762 printf("%s: needs merge\n", ce->name);
763 has_errors = 1;
764 continue;
767 new = refresh_cache_ent(ce, really, &cache_errno);
768 if (new == ce)
769 continue;
770 if (!new) {
771 if (not_new && cache_errno == ENOENT)
772 continue;
773 if (really && cache_errno == EINVAL) {
774 /* If we are doing --really-refresh that
775 * means the index is not valid anymore.
777 ce->ce_flags &= ~htons(CE_VALID);
778 active_cache_changed = 1;
780 if (quiet)
781 continue;
782 printf("%s: needs update\n", ce->name);
783 has_errors = 1;
784 continue;
786 active_cache_changed = 1;
787 /* You can NOT just free active_cache[i] here, since it
788 * might not be necessarily malloc()ed but can also come
789 * from mmap(). */
790 active_cache[i] = new;
792 return has_errors;
795 struct cache_entry *refresh_cache_entry(struct cache_entry *ce, int really)
797 return refresh_cache_ent(ce, really, NULL);
800 static int verify_hdr(struct cache_header *hdr, unsigned long size)
802 SHA_CTX c;
803 unsigned char sha1[20];
805 if (hdr->hdr_signature != htonl(CACHE_SIGNATURE))
806 return error("bad signature");
807 if (hdr->hdr_version != htonl(2))
808 return error("bad index version");
809 SHA1_Init(&c);
810 SHA1_Update(&c, hdr, size - 20);
811 SHA1_Final(sha1, &c);
812 if (hashcmp(sha1, (unsigned char *)hdr + size - 20))
813 return error("bad index file sha1 signature");
814 return 0;
817 static int read_index_extension(const char *ext, void *data, unsigned long sz)
819 switch (CACHE_EXT(ext)) {
820 case CACHE_EXT_TREE:
821 active_cache_tree = cache_tree_read(data, sz);
822 break;
823 default:
824 if (*ext < 'A' || 'Z' < *ext)
825 return error("index uses %.4s extension, which we do not understand",
826 ext);
827 fprintf(stderr, "ignoring %.4s extension\n", ext);
828 break;
830 return 0;
833 int read_cache(void)
835 return read_cache_from(get_index_file());
838 /* remember to discard_cache() before reading a different cache! */
839 int read_cache_from(const char *path)
841 int fd, i;
842 struct stat st;
843 unsigned long offset;
844 struct cache_header *hdr;
846 errno = EBUSY;
847 if (cache_mmap)
848 return active_nr;
850 errno = ENOENT;
851 index_file_timestamp = 0;
852 fd = open(path, O_RDONLY);
853 if (fd < 0) {
854 if (errno == ENOENT)
855 return 0;
856 die("index file open failed (%s)", strerror(errno));
859 if (!fstat(fd, &st)) {
860 cache_mmap_size = xsize_t(st.st_size);
861 errno = EINVAL;
862 if (cache_mmap_size >= sizeof(struct cache_header) + 20)
863 cache_mmap = xmmap(NULL, cache_mmap_size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
864 else
865 die("index file smaller than expected");
866 } else
867 die("cannot stat the open index (%s)", strerror(errno));
868 close(fd);
870 hdr = cache_mmap;
871 if (verify_hdr(hdr, cache_mmap_size) < 0)
872 goto unmap;
874 active_nr = ntohl(hdr->hdr_entries);
875 active_alloc = alloc_nr(active_nr);
876 active_cache = xcalloc(active_alloc, sizeof(struct cache_entry *));
878 offset = sizeof(*hdr);
879 for (i = 0; i < active_nr; i++) {
880 struct cache_entry *ce = (struct cache_entry *) ((char *) cache_mmap + offset);
881 offset = offset + ce_size(ce);
882 active_cache[i] = ce;
884 index_file_timestamp = st.st_mtime;
885 while (offset <= cache_mmap_size - 20 - 8) {
886 /* After an array of active_nr index entries,
887 * there can be arbitrary number of extended
888 * sections, each of which is prefixed with
889 * extension name (4-byte) and section length
890 * in 4-byte network byte order.
892 unsigned long extsize;
893 memcpy(&extsize, (char *) cache_mmap + offset + 4, 4);
894 extsize = ntohl(extsize);
895 if (read_index_extension(((const char *) cache_mmap) + offset,
896 (char *) cache_mmap + offset + 8,
897 extsize) < 0)
898 goto unmap;
899 offset += 8;
900 offset += extsize;
902 return active_nr;
904 unmap:
905 munmap(cache_mmap, cache_mmap_size);
906 errno = EINVAL;
907 die("index file corrupt");
910 int discard_cache(void)
912 int ret;
914 active_nr = active_cache_changed = 0;
915 index_file_timestamp = 0;
916 cache_tree_free(&active_cache_tree);
917 if (cache_mmap == NULL)
918 return 0;
919 ret = munmap(cache_mmap, cache_mmap_size);
920 cache_mmap = NULL;
921 cache_mmap_size = 0;
923 /* no need to throw away allocated active_cache */
924 return ret;
927 #define WRITE_BUFFER_SIZE 8192
928 static unsigned char write_buffer[WRITE_BUFFER_SIZE];
929 static unsigned long write_buffer_len;
931 static int ce_write_flush(SHA_CTX *context, int fd)
933 unsigned int buffered = write_buffer_len;
934 if (buffered) {
935 SHA1_Update(context, write_buffer, buffered);
936 if (write_in_full(fd, write_buffer, buffered) != buffered)
937 return -1;
938 write_buffer_len = 0;
940 return 0;
943 static int ce_write(SHA_CTX *context, int fd, void *data, unsigned int len)
945 while (len) {
946 unsigned int buffered = write_buffer_len;
947 unsigned int partial = WRITE_BUFFER_SIZE - buffered;
948 if (partial > len)
949 partial = len;
950 memcpy(write_buffer + buffered, data, partial);
951 buffered += partial;
952 if (buffered == WRITE_BUFFER_SIZE) {
953 write_buffer_len = buffered;
954 if (ce_write_flush(context, fd))
955 return -1;
956 buffered = 0;
958 write_buffer_len = buffered;
959 len -= partial;
960 data = (char *) data + partial;
962 return 0;
965 static int write_index_ext_header(SHA_CTX *context, int fd,
966 unsigned int ext, unsigned int sz)
968 ext = htonl(ext);
969 sz = htonl(sz);
970 return ((ce_write(context, fd, &ext, 4) < 0) ||
971 (ce_write(context, fd, &sz, 4) < 0)) ? -1 : 0;
974 static int ce_flush(SHA_CTX *context, int fd)
976 unsigned int left = write_buffer_len;
978 if (left) {
979 write_buffer_len = 0;
980 SHA1_Update(context, write_buffer, left);
983 /* Flush first if not enough space for SHA1 signature */
984 if (left + 20 > WRITE_BUFFER_SIZE) {
985 if (write_in_full(fd, write_buffer, left) != left)
986 return -1;
987 left = 0;
990 /* Append the SHA1 signature at the end */
991 SHA1_Final(write_buffer + left, context);
992 left += 20;
993 return (write_in_full(fd, write_buffer, left) != left) ? -1 : 0;
996 static void ce_smudge_racily_clean_entry(struct cache_entry *ce)
999 * The only thing we care about in this function is to smudge the
1000 * falsely clean entry due to touch-update-touch race, so we leave
1001 * everything else as they are. We are called for entries whose
1002 * ce_mtime match the index file mtime.
1004 struct stat st;
1006 if (lstat(ce->name, &st) < 0)
1007 return;
1008 if (ce_match_stat_basic(ce, &st))
1009 return;
1010 if (ce_modified_check_fs(ce, &st)) {
1011 /* This is "racily clean"; smudge it. Note that this
1012 * is a tricky code. At first glance, it may appear
1013 * that it can break with this sequence:
1015 * $ echo xyzzy >frotz
1016 * $ git-update-index --add frotz
1017 * $ : >frotz
1018 * $ sleep 3
1019 * $ echo filfre >nitfol
1020 * $ git-update-index --add nitfol
1022 * but it does not. When the second update-index runs,
1023 * it notices that the entry "frotz" has the same timestamp
1024 * as index, and if we were to smudge it by resetting its
1025 * size to zero here, then the object name recorded
1026 * in index is the 6-byte file but the cached stat information
1027 * becomes zero --- which would then match what we would
1028 * obtain from the filesystem next time we stat("frotz").
1030 * However, the second update-index, before calling
1031 * this function, notices that the cached size is 6
1032 * bytes and what is on the filesystem is an empty
1033 * file, and never calls us, so the cached size information
1034 * for "frotz" stays 6 which does not match the filesystem.
1036 ce->ce_size = htonl(0);
1040 int write_cache(int newfd, struct cache_entry **cache, int entries)
1042 SHA_CTX c;
1043 struct cache_header hdr;
1044 int i, removed;
1046 for (i = removed = 0; i < entries; i++)
1047 if (!cache[i]->ce_mode)
1048 removed++;
1050 hdr.hdr_signature = htonl(CACHE_SIGNATURE);
1051 hdr.hdr_version = htonl(2);
1052 hdr.hdr_entries = htonl(entries - removed);
1054 SHA1_Init(&c);
1055 if (ce_write(&c, newfd, &hdr, sizeof(hdr)) < 0)
1056 return -1;
1058 for (i = 0; i < entries; i++) {
1059 struct cache_entry *ce = cache[i];
1060 if (!ce->ce_mode)
1061 continue;
1062 if (index_file_timestamp &&
1063 index_file_timestamp <= ntohl(ce->ce_mtime.sec))
1064 ce_smudge_racily_clean_entry(ce);
1065 if (ce_write(&c, newfd, ce, ce_size(ce)) < 0)
1066 return -1;
1069 /* Write extension data here */
1070 if (active_cache_tree) {
1071 unsigned long sz;
1072 void *data = cache_tree_write(active_cache_tree, &sz);
1073 if (data &&
1074 !write_index_ext_header(&c, newfd, CACHE_EXT_TREE, sz) &&
1075 !ce_write(&c, newfd, data, sz))
1076 free(data);
1077 else {
1078 free(data);
1079 return -1;
1082 return ce_flush(&c, newfd);