Make read-cache.c "the_index" free.
[git/git.git] / read-cache.c
1 /*
2 * GIT - The information manager from hell
3 *
4 * Copyright (C) Linus Torvalds, 2005
5 */
6 #define NO_THE_INDEX_COMPATIBILITY_MACROS
7 #include "cache.h"
8 #include "cache-tree.h"
9 #include "refs.h"
10
11 /* Index extensions.
12 *
13 * The first letter should be 'A'..'Z' for extensions that are not
14 * necessary for a correct operation (i.e. optimization data).
15 * When new extensions are added that _needs_ to be understood in
16 * order to correctly interpret the index file, pick character that
17 * is outside the range, to cause the reader to abort.
18 */
19
20 #define CACHE_EXT(s) ( (s[0]<<24)|(s[1]<<16)|(s[2]<<8)|(s[3]) )
21 #define CACHE_EXT_TREE 0x54524545 /* "TREE" */
22
23 struct index_state the_index;
24
25 /*
26 * This only updates the "non-critical" parts of the directory
27 * cache, ie the parts that aren't tracked by GIT, and only used
28 * to validate the cache.
29 */
30 void fill_stat_cache_info(struct cache_entry *ce, struct stat *st)
31 {
32 ce->ce_ctime.sec = htonl(st->st_ctime);
33 ce->ce_mtime.sec = htonl(st->st_mtime);
34 #ifdef USE_NSEC
35 ce->ce_ctime.nsec = htonl(st->st_ctim.tv_nsec);
36 ce->ce_mtime.nsec = htonl(st->st_mtim.tv_nsec);
37 #endif
38 ce->ce_dev = htonl(st->st_dev);
39 ce->ce_ino = htonl(st->st_ino);
40 ce->ce_uid = htonl(st->st_uid);
41 ce->ce_gid = htonl(st->st_gid);
42 ce->ce_size = htonl(st->st_size);
43
44 if (assume_unchanged)
45 ce->ce_flags |= htons(CE_VALID);
46 }
47
48 static int ce_compare_data(struct cache_entry *ce, struct stat *st)
49 {
50 int match = -1;
51 int fd = open(ce->name, O_RDONLY);
52
53 if (fd >= 0) {
54 unsigned char sha1[20];
55 if (!index_fd(sha1, fd, st, 0, OBJ_BLOB, ce->name))
56 match = hashcmp(sha1, ce->sha1);
57 /* index_fd() closed the file descriptor already */
58 }
59 return match;
60 }
61
62 static int ce_compare_link(struct cache_entry *ce, size_t expected_size)
63 {
64 int match = -1;
65 char *target;
66 void *buffer;
67 unsigned long size;
68 enum object_type type;
69 int len;
70
71 target = xmalloc(expected_size);
72 len = readlink(ce->name, target, expected_size);
73 if (len != expected_size) {
74 free(target);
75 return -1;
76 }
77 buffer = read_sha1_file(ce->sha1, &type, &size);
78 if (!buffer) {
79 free(target);
80 return -1;
81 }
82 if (size == expected_size)
83 match = memcmp(buffer, target, size);
84 free(buffer);
85 free(target);
86 return match;
87 }
88
89 static int ce_compare_gitlink(struct cache_entry *ce)
90 {
91 unsigned char sha1[20];
92
93 /*
94 * We don't actually require that the .git directory
95 * under DIRLNK directory be a valid git directory. It
96 * might even be missing (in case nobody populated that
97 * sub-project).
98 *
99 * If so, we consider it always to match.
100 */
101 if (resolve_gitlink_ref(ce->name, "HEAD", sha1) < 0)
102 return 0;
103 return hashcmp(sha1, ce->sha1);
104 }
105
106 static int ce_modified_check_fs(struct cache_entry *ce, struct stat *st)
107 {
108 switch (st->st_mode & S_IFMT) {
109 case S_IFREG:
110 if (ce_compare_data(ce, st))
111 return DATA_CHANGED;
112 break;
113 case S_IFLNK:
114 if (ce_compare_link(ce, xsize_t(st->st_size)))
115 return DATA_CHANGED;
116 break;
117 case S_IFDIR:
118 if (S_ISDIRLNK(ntohl(ce->ce_mode)))
119 return 0;
120 default:
121 return TYPE_CHANGED;
122 }
123 return 0;
124 }
125
126 static int ce_match_stat_basic(struct cache_entry *ce, struct stat *st)
127 {
128 unsigned int changed = 0;
129
130 switch (ntohl(ce->ce_mode) & S_IFMT) {
131 case S_IFREG:
132 changed |= !S_ISREG(st->st_mode) ? TYPE_CHANGED : 0;
133 /* We consider only the owner x bit to be relevant for
134 * "mode changes"
135 */
136 if (trust_executable_bit &&
137 (0100 & (ntohl(ce->ce_mode) ^ st->st_mode)))
138 changed |= MODE_CHANGED;
139 break;
140 case S_IFLNK:
141 if (!S_ISLNK(st->st_mode) &&
142 (has_symlinks || !S_ISREG(st->st_mode)))
143 changed |= TYPE_CHANGED;
144 break;
145 case S_IFDIRLNK:
146 if (!S_ISDIR(st->st_mode))
147 changed |= TYPE_CHANGED;
148 else if (ce_compare_gitlink(ce))
149 changed |= DATA_CHANGED;
150 return changed;
151 default:
152 die("internal error: ce_mode is %o", ntohl(ce->ce_mode));
153 }
154 if (ce->ce_mtime.sec != htonl(st->st_mtime))
155 changed |= MTIME_CHANGED;
156 if (ce->ce_ctime.sec != htonl(st->st_ctime))
157 changed |= CTIME_CHANGED;
158
159 #ifdef USE_NSEC
160 /*
161 * nsec seems unreliable - not all filesystems support it, so
162 * as long as it is in the inode cache you get right nsec
163 * but after it gets flushed, you get zero nsec.
164 */
165 if (ce->ce_mtime.nsec != htonl(st->st_mtim.tv_nsec))
166 changed |= MTIME_CHANGED;
167 if (ce->ce_ctime.nsec != htonl(st->st_ctim.tv_nsec))
168 changed |= CTIME_CHANGED;
169 #endif
170
171 if (ce->ce_uid != htonl(st->st_uid) ||
172 ce->ce_gid != htonl(st->st_gid))
173 changed |= OWNER_CHANGED;
174 if (ce->ce_ino != htonl(st->st_ino))
175 changed |= INODE_CHANGED;
176
177 #ifdef USE_STDEV
178 /*
179 * st_dev breaks on network filesystems where different
180 * clients will have different views of what "device"
181 * the filesystem is on
182 */
183 if (ce->ce_dev != htonl(st->st_dev))
184 changed |= INODE_CHANGED;
185 #endif
186
187 if (ce->ce_size != htonl(st->st_size))
188 changed |= DATA_CHANGED;
189
190 return changed;
191 }
192
193 int ie_match_stat(struct index_state *istate,
194 struct cache_entry *ce, struct stat *st, int options)
195 {
196 unsigned int changed;
197 int ignore_valid = options & 01;
198 int assume_racy_is_modified = options & 02;
199
200 /*
201 * If it's marked as always valid in the index, it's
202 * valid whatever the checked-out copy says.
203 */
204 if (!ignore_valid && (ce->ce_flags & htons(CE_VALID)))
205 return 0;
206
207 changed = ce_match_stat_basic(ce, st);
208
209 /*
210 * Within 1 second of this sequence:
211 * echo xyzzy >file && git-update-index --add file
212 * running this command:
213 * echo frotz >file
214 * would give a falsely clean cache entry. The mtime and
215 * length match the cache, and other stat fields do not change.
216 *
217 * We could detect this at update-index time (the cache entry
218 * being registered/updated records the same time as "now")
219 * and delay the return from git-update-index, but that would
220 * effectively mean we can make at most one commit per second,
221 * which is not acceptable. Instead, we check cache entries
222 * whose mtime are the same as the index file timestamp more
223 * carefully than others.
224 */
225 if (!changed &&
226 istate->timestamp &&
227 istate->timestamp <= ntohl(ce->ce_mtime.sec)) {
228 if (assume_racy_is_modified)
229 changed |= DATA_CHANGED;
230 else
231 changed |= ce_modified_check_fs(ce, st);
232 }
233
234 return changed;
235 }
236
237 int ie_modified(struct index_state *istate,
238 struct cache_entry *ce, struct stat *st, int really)
239 {
240 int changed, changed_fs;
241 changed = ie_match_stat(istate, ce, st, really);
242 if (!changed)
243 return 0;
244 /*
245 * If the mode or type has changed, there's no point in trying
246 * to refresh the entry - it's not going to match
247 */
248 if (changed & (MODE_CHANGED | TYPE_CHANGED))
249 return changed;
250
251 /* Immediately after read-tree or update-index --cacheinfo,
252 * the length field is zero. For other cases the ce_size
253 * should match the SHA1 recorded in the index entry.
254 */
255 if ((changed & DATA_CHANGED) && ce->ce_size != htonl(0))
256 return changed;
257
258 changed_fs = ce_modified_check_fs(ce, st);
259 if (changed_fs)
260 return changed | changed_fs;
261 return 0;
262 }
263
264 int base_name_compare(const char *name1, int len1, int mode1,
265 const char *name2, int len2, int mode2)
266 {
267 unsigned char c1, c2;
268 int len = len1 < len2 ? len1 : len2;
269 int cmp;
270
271 cmp = memcmp(name1, name2, len);
272 if (cmp)
273 return cmp;
274 c1 = name1[len];
275 c2 = name2[len];
276 if (!c1 && S_ISDIR(mode1))
277 c1 = '/';
278 if (!c2 && S_ISDIR(mode2))
279 c2 = '/';
280 return (c1 < c2) ? -1 : (c1 > c2) ? 1 : 0;
281 }
282
283 int cache_name_compare(const char *name1, int flags1, const char *name2, int flags2)
284 {
285 int len1 = flags1 & CE_NAMEMASK;
286 int len2 = flags2 & CE_NAMEMASK;
287 int len = len1 < len2 ? len1 : len2;
288 int cmp;
289
290 cmp = memcmp(name1, name2, len);
291 if (cmp)
292 return cmp;
293 if (len1 < len2)
294 return -1;
295 if (len1 > len2)
296 return 1;
297
298 /* Compare stages */
299 flags1 &= CE_STAGEMASK;
300 flags2 &= CE_STAGEMASK;
301
302 if (flags1 < flags2)
303 return -1;
304 if (flags1 > flags2)
305 return 1;
306 return 0;
307 }
308
309 int index_name_pos(struct index_state *istate, const char *name, int namelen)
310 {
311 int first, last;
312
313 first = 0;
314 last = istate->cache_nr;
315 while (last > first) {
316 int next = (last + first) >> 1;
317 struct cache_entry *ce = istate->cache[next];
318 int cmp = cache_name_compare(name, namelen, ce->name, ntohs(ce->ce_flags));
319 if (!cmp)
320 return next;
321 if (cmp < 0) {
322 last = next;
323 continue;
324 }
325 first = next+1;
326 }
327 return -first-1;
328 }
329
330 /* Remove entry, return true if there are more entries to go.. */
331 int remove_index_entry_at(struct index_state *istate, int pos)
332 {
333 istate->cache_changed = 1;
334 istate->cache_nr--;
335 if (pos >= istate->cache_nr)
336 return 0;
337 memmove(istate->cache + pos,
338 istate->cache + pos + 1,
339 (istate->cache_nr - pos) * sizeof(struct cache_entry *));
340 return 1;
341 }
342
343 int remove_file_from_index(struct index_state *istate, const char *path)
344 {
345 int pos = index_name_pos(istate, path, strlen(path));
346 if (pos < 0)
347 pos = -pos-1;
348 while (pos < istate->cache_nr && !strcmp(istate->cache[pos]->name, path))
349 remove_index_entry_at(istate, pos);
350 return 0;
351 }
352
353 int add_file_to_index(struct index_state *istate, const char *path, int verbose)
354 {
355 int size, namelen;
356 struct stat st;
357 struct cache_entry *ce;
358
359 if (lstat(path, &st))
360 die("%s: unable to stat (%s)", path, strerror(errno));
361
362 if (!S_ISREG(st.st_mode) && !S_ISLNK(st.st_mode) && !S_ISDIR(st.st_mode))
363 die("%s: can only add regular files, symbolic links or git-directories", path);
364
365 namelen = strlen(path);
366 if (S_ISDIR(st.st_mode)) {
367 while (namelen && path[namelen-1] == '/')
368 namelen--;
369 }
370 size = cache_entry_size(namelen);
371 ce = xcalloc(1, size);
372 memcpy(ce->name, path, namelen);
373 ce->ce_flags = htons(namelen);
374 fill_stat_cache_info(ce, &st);
375
376 if (trust_executable_bit && has_symlinks)
377 ce->ce_mode = create_ce_mode(st.st_mode);
378 else {
379 /* If there is an existing entry, pick the mode bits and type
380 * from it, otherwise assume unexecutable regular file.
381 */
382 struct cache_entry *ent;
383 int pos = index_name_pos(istate, path, namelen);
384
385 ent = (0 <= pos) ? istate->cache[pos] : NULL;
386 ce->ce_mode = ce_mode_from_stat(ent, st.st_mode);
387 }
388
389 if (index_path(ce->sha1, path, &st, 1))
390 die("unable to index file %s", path);
391 if (add_index_entry(istate, ce, ADD_CACHE_OK_TO_ADD|ADD_CACHE_OK_TO_REPLACE))
392 die("unable to add %s to index",path);
393 if (verbose)
394 printf("add '%s'\n", path);
395 cache_tree_invalidate_path(istate->cache_tree, path);
396 return 0;
397 }
398
399 int ce_same_name(struct cache_entry *a, struct cache_entry *b)
400 {
401 int len = ce_namelen(a);
402 return ce_namelen(b) == len && !memcmp(a->name, b->name, len);
403 }
404
405 int ce_path_match(const struct cache_entry *ce, const char **pathspec)
406 {
407 const char *match, *name;
408 int len;
409
410 if (!pathspec)
411 return 1;
412
413 len = ce_namelen(ce);
414 name = ce->name;
415 while ((match = *pathspec++) != NULL) {
416 int matchlen = strlen(match);
417 if (matchlen > len)
418 continue;
419 if (memcmp(name, match, matchlen))
420 continue;
421 if (matchlen && name[matchlen-1] == '/')
422 return 1;
423 if (name[matchlen] == '/' || !name[matchlen])
424 return 1;
425 if (!matchlen)
426 return 1;
427 }
428 return 0;
429 }
430
431 /*
432 * We fundamentally don't like some paths: we don't want
433 * dot or dot-dot anywhere, and for obvious reasons don't
434 * want to recurse into ".git" either.
435 *
436 * Also, we don't want double slashes or slashes at the
437 * end that can make pathnames ambiguous.
438 */
439 static int verify_dotfile(const char *rest)
440 {
441 /*
442 * The first character was '.', but that
443 * has already been discarded, we now test
444 * the rest.
445 */
446 switch (*rest) {
447 /* "." is not allowed */
448 case '\0': case '/':
449 return 0;
450
451 /*
452 * ".git" followed by NUL or slash is bad. This
453 * shares the path end test with the ".." case.
454 */
455 case 'g':
456 if (rest[1] != 'i')
457 break;
458 if (rest[2] != 't')
459 break;
460 rest += 2;
461 /* fallthrough */
462 case '.':
463 if (rest[1] == '\0' || rest[1] == '/')
464 return 0;
465 }
466 return 1;
467 }
468
469 int verify_path(const char *path)
470 {
471 char c;
472
473 goto inside;
474 for (;;) {
475 if (!c)
476 return 1;
477 if (c == '/') {
478 inside:
479 c = *path++;
480 switch (c) {
481 default:
482 continue;
483 case '/': case '\0':
484 break;
485 case '.':
486 if (verify_dotfile(path))
487 continue;
488 }
489 return 0;
490 }
491 c = *path++;
492 }
493 }
494
495 /*
496 * Do we have another file that has the beginning components being a
497 * proper superset of the name we're trying to add?
498 */
499 static int has_file_name(struct index_state *istate,
500 const struct cache_entry *ce, int pos, int ok_to_replace)
501 {
502 int retval = 0;
503 int len = ce_namelen(ce);
504 int stage = ce_stage(ce);
505 const char *name = ce->name;
506
507 while (pos < istate->cache_nr) {
508 struct cache_entry *p = istate->cache[pos++];
509
510 if (len >= ce_namelen(p))
511 break;
512 if (memcmp(name, p->name, len))
513 break;
514 if (ce_stage(p) != stage)
515 continue;
516 if (p->name[len] != '/')
517 continue;
518 if (!ce_stage(p) && !p->ce_mode)
519 continue;
520 retval = -1;
521 if (!ok_to_replace)
522 break;
523 remove_index_entry_at(istate, --pos);
524 }
525 return retval;
526 }
527
528 /*
529 * Do we have another file with a pathname that is a proper
530 * subset of the name we're trying to add?
531 */
532 static int has_dir_name(struct index_state *istate,
533 const struct cache_entry *ce, int pos, int ok_to_replace)
534 {
535 int retval = 0;
536 int stage = ce_stage(ce);
537 const char *name = ce->name;
538 const char *slash = name + ce_namelen(ce);
539
540 for (;;) {
541 int len;
542
543 for (;;) {
544 if (*--slash == '/')
545 break;
546 if (slash <= ce->name)
547 return retval;
548 }
549 len = slash - name;
550
551 pos = index_name_pos(istate, name, ntohs(create_ce_flags(len, stage)));
552 if (pos >= 0) {
553 /*
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.
560 */
561 if (stage || istate->cache[pos]->ce_mode) {
562 retval = -1;
563 if (!ok_to_replace)
564 break;
565 remove_index_entry_at(istate, pos);
566 continue;
567 }
568 }
569 else
570 pos = -pos-1;
571
572 /*
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.
576 */
577 while (pos < istate->cache_nr) {
578 struct cache_entry *p = istate->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.
588 */
589 return retval;
590 pos++;
591 }
592 }
593 return retval;
594 }
595
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.
600 *
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.
604 */
605 static int check_file_directory_conflict(struct index_state *istate,
606 const struct cache_entry *ce,
607 int pos, int ok_to_replace)
608 {
609 int retval;
610
611 /*
612 * When ce is an "I am going away" entry, we allow it to be added
613 */
614 if (!ce_stage(ce) && !ce->ce_mode)
615 return 0;
616
617 /*
618 * We check if the path is a sub-path of a subsequent pathname
619 * first, since removing those will not change the position
620 * in the array.
621 */
622 retval = has_file_name(istate, ce, pos, ok_to_replace);
623
624 /*
625 * Then check if the path might have a clashing sub-directory
626 * before it.
627 */
628 return retval + has_dir_name(istate, ce, pos, ok_to_replace);
629 }
630
631 int add_index_entry(struct index_state *istate, struct cache_entry *ce, int option)
632 {
633 int pos;
634 int ok_to_add = option & ADD_CACHE_OK_TO_ADD;
635 int ok_to_replace = option & ADD_CACHE_OK_TO_REPLACE;
636 int skip_df_check = option & ADD_CACHE_SKIP_DFCHECK;
637
638 pos = index_name_pos(istate, ce->name, ntohs(ce->ce_flags));
639
640 /* existing match? Just replace it. */
641 if (pos >= 0) {
642 istate->cache_changed = 1;
643 istate->cache[pos] = ce;
644 return 0;
645 }
646 pos = -pos-1;
647
648 /*
649 * Inserting a merged entry ("stage 0") into the index
650 * will always replace all non-merged entries..
651 */
652 if (pos < istate->cache_nr && ce_stage(ce) == 0) {
653 while (ce_same_name(istate->cache[pos], ce)) {
654 ok_to_add = 1;
655 if (!remove_index_entry_at(istate, pos))
656 break;
657 }
658 }
659
660 if (!ok_to_add)
661 return -1;
662 if (!verify_path(ce->name))
663 return -1;
664
665 if (!skip_df_check &&
666 check_file_directory_conflict(istate, ce, pos, ok_to_replace)) {
667 if (!ok_to_replace)
668 return error("'%s' appears as both a file and as a directory",
669 ce->name);
670 pos = index_name_pos(istate, ce->name, ntohs(ce->ce_flags));
671 pos = -pos-1;
672 }
673
674 /* Make sure the array is big enough .. */
675 if (istate->cache_nr == istate->cache_alloc) {
676 istate->cache_alloc = alloc_nr(istate->cache_alloc);
677 istate->cache = xrealloc(istate->cache,
678 istate->cache_alloc * sizeof(struct cache_entry *));
679 }
680
681 /* Add it in.. */
682 istate->cache_nr++;
683 if (istate->cache_nr > pos)
684 memmove(istate->cache + pos + 1,
685 istate->cache + pos,
686 (istate->cache_nr - pos - 1) * sizeof(ce));
687 istate->cache[pos] = ce;
688 istate->cache_changed = 1;
689 return 0;
690 }
691
692 /*
693 * "refresh" does not calculate a new sha1 file or bring the
694 * cache up-to-date for mode/content changes. But what it
695 * _does_ do is to "re-match" the stat information of a file
696 * with the cache, so that you can refresh the cache for a
697 * file that hasn't been changed but where the stat entry is
698 * out of date.
699 *
700 * For example, you'd want to do this after doing a "git-read-tree",
701 * to link up the stat cache details with the proper files.
702 */
703 static struct cache_entry *refresh_cache_ent(struct index_state *istate,
704 struct cache_entry *ce, int really, int *err)
705 {
706 struct stat st;
707 struct cache_entry *updated;
708 int changed, size;
709
710 if (lstat(ce->name, &st) < 0) {
711 if (err)
712 *err = errno;
713 return NULL;
714 }
715
716 changed = ie_match_stat(istate, ce, &st, really);
717 if (!changed) {
718 if (really && assume_unchanged &&
719 !(ce->ce_flags & htons(CE_VALID)))
720 ; /* mark this one VALID again */
721 else
722 return ce;
723 }
724
725 if (ie_modified(istate, ce, &st, really)) {
726 if (err)
727 *err = EINVAL;
728 return NULL;
729 }
730
731 size = ce_size(ce);
732 updated = xmalloc(size);
733 memcpy(updated, ce, size);
734 fill_stat_cache_info(updated, &st);
735
736 /* In this case, if really is not set, we should leave
737 * CE_VALID bit alone. Otherwise, paths marked with
738 * --no-assume-unchanged (i.e. things to be edited) will
739 * reacquire CE_VALID bit automatically, which is not
740 * really what we want.
741 */
742 if (!really && assume_unchanged && !(ce->ce_flags & htons(CE_VALID)))
743 updated->ce_flags &= ~htons(CE_VALID);
744
745 return updated;
746 }
747
748 int refresh_index(struct index_state *istate, unsigned int flags)
749 {
750 int i;
751 int has_errors = 0;
752 int really = (flags & REFRESH_REALLY) != 0;
753 int allow_unmerged = (flags & REFRESH_UNMERGED) != 0;
754 int quiet = (flags & REFRESH_QUIET) != 0;
755 int not_new = (flags & REFRESH_IGNORE_MISSING) != 0;
756
757 for (i = 0; i < istate->cache_nr; i++) {
758 struct cache_entry *ce, *new;
759 int cache_errno = 0;
760
761 ce = istate->cache[i];
762 if (ce_stage(ce)) {
763 while ((i < istate->cache_nr) &&
764 ! strcmp(istate->cache[i]->name, ce->name))
765 i++;
766 i--;
767 if (allow_unmerged)
768 continue;
769 printf("%s: needs merge\n", ce->name);
770 has_errors = 1;
771 continue;
772 }
773
774 new = refresh_cache_ent(istate, ce, really, &cache_errno);
775 if (new == ce)
776 continue;
777 if (!new) {
778 if (not_new && cache_errno == ENOENT)
779 continue;
780 if (really && cache_errno == EINVAL) {
781 /* If we are doing --really-refresh that
782 * means the index is not valid anymore.
783 */
784 ce->ce_flags &= ~htons(CE_VALID);
785 istate->cache_changed = 1;
786 }
787 if (quiet)
788 continue;
789 printf("%s: needs update\n", ce->name);
790 has_errors = 1;
791 continue;
792 }
793 istate->cache_changed = 1;
794 /* You can NOT just free istate->cache[i] here, since it
795 * might not be necessarily malloc()ed but can also come
796 * from mmap(). */
797 istate->cache[i] = new;
798 }
799 return has_errors;
800 }
801
802 struct cache_entry *refresh_cache_entry(struct cache_entry *ce, int really)
803 {
804 return refresh_cache_ent(&the_index, ce, really, NULL);
805 }
806
807 static int verify_hdr(struct cache_header *hdr, unsigned long size)
808 {
809 SHA_CTX c;
810 unsigned char sha1[20];
811
812 if (hdr->hdr_signature != htonl(CACHE_SIGNATURE))
813 return error("bad signature");
814 if (hdr->hdr_version != htonl(2))
815 return error("bad index version");
816 SHA1_Init(&c);
817 SHA1_Update(&c, hdr, size - 20);
818 SHA1_Final(sha1, &c);
819 if (hashcmp(sha1, (unsigned char *)hdr + size - 20))
820 return error("bad index file sha1 signature");
821 return 0;
822 }
823
824 static int read_index_extension(struct index_state *istate,
825 const char *ext, void *data, unsigned long sz)
826 {
827 switch (CACHE_EXT(ext)) {
828 case CACHE_EXT_TREE:
829 istate->cache_tree = cache_tree_read(data, sz);
830 break;
831 default:
832 if (*ext < 'A' || 'Z' < *ext)
833 return error("index uses %.4s extension, which we do not understand",
834 ext);
835 fprintf(stderr, "ignoring %.4s extension\n", ext);
836 break;
837 }
838 return 0;
839 }
840
841 int read_index(struct index_state *istate)
842 {
843 return read_index_from(istate, get_index_file());
844 }
845
846 /* remember to discard_cache() before reading a different cache! */
847 int read_index_from(struct index_state *istate, const char *path)
848 {
849 int fd, i;
850 struct stat st;
851 unsigned long offset;
852 struct cache_header *hdr;
853
854 errno = EBUSY;
855 if (istate->mmap)
856 return istate->cache_nr;
857
858 errno = ENOENT;
859 istate->timestamp = 0;
860 fd = open(path, O_RDONLY);
861 if (fd < 0) {
862 if (errno == ENOENT)
863 return 0;
864 die("index file open failed (%s)", strerror(errno));
865 }
866
867 if (!fstat(fd, &st)) {
868 istate->mmap_size = xsize_t(st.st_size);
869 errno = EINVAL;
870 if (istate->mmap_size >= sizeof(struct cache_header) + 20)
871 istate->mmap = xmmap(NULL, istate->mmap_size,
872 PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
873 else
874 die("index file smaller than expected");
875 } else
876 die("cannot stat the open index (%s)", strerror(errno));
877 close(fd);
878
879 hdr = istate->mmap;
880 if (verify_hdr(hdr, istate->mmap_size) < 0)
881 goto unmap;
882
883 istate->cache_nr = ntohl(hdr->hdr_entries);
884 istate->cache_alloc = alloc_nr(istate->cache_nr);
885 istate->cache = xcalloc(istate->cache_alloc, sizeof(struct cache_entry *));
886
887 offset = sizeof(*hdr);
888 for (i = 0; i < istate->cache_nr; i++) {
889 struct cache_entry *ce;
890
891 ce = (struct cache_entry *)((char *)(istate->mmap) + offset);
892 offset = offset + ce_size(ce);
893 istate->cache[i] = ce;
894 }
895 istate->timestamp = st.st_mtime;
896 while (offset <= istate->mmap_size - 20 - 8) {
897 /* After an array of active_nr index entries,
898 * there can be arbitrary number of extended
899 * sections, each of which is prefixed with
900 * extension name (4-byte) and section length
901 * in 4-byte network byte order.
902 */
903 unsigned long extsize;
904 memcpy(&extsize, (char *)(istate->mmap) + offset + 4, 4);
905 extsize = ntohl(extsize);
906 if (read_index_extension(istate,
907 ((const char *) (istate->mmap)) + offset,
908 (char *) (istate->mmap) + offset + 8,
909 extsize) < 0)
910 goto unmap;
911 offset += 8;
912 offset += extsize;
913 }
914 return istate->cache_nr;
915
916 unmap:
917 munmap(istate->mmap, istate->mmap_size);
918 errno = EINVAL;
919 die("index file corrupt");
920 }
921
922 int discard_index(struct index_state *istate)
923 {
924 int ret;
925
926 istate->cache_nr = 0;
927 istate->cache_changed = 0;
928 istate->timestamp = 0;
929 cache_tree_free(&(istate->cache_tree));
930 if (istate->mmap == NULL)
931 return 0;
932 ret = munmap(istate->mmap, istate->mmap_size);
933 istate->mmap = NULL;
934 istate->mmap_size = 0;
935
936 /* no need to throw away allocated active_cache */
937 return ret;
938 }
939
940 #define WRITE_BUFFER_SIZE 8192
941 static unsigned char write_buffer[WRITE_BUFFER_SIZE];
942 static unsigned long write_buffer_len;
943
944 static int ce_write_flush(SHA_CTX *context, int fd)
945 {
946 unsigned int buffered = write_buffer_len;
947 if (buffered) {
948 SHA1_Update(context, write_buffer, buffered);
949 if (write_in_full(fd, write_buffer, buffered) != buffered)
950 return -1;
951 write_buffer_len = 0;
952 }
953 return 0;
954 }
955
956 static int ce_write(SHA_CTX *context, int fd, void *data, unsigned int len)
957 {
958 while (len) {
959 unsigned int buffered = write_buffer_len;
960 unsigned int partial = WRITE_BUFFER_SIZE - buffered;
961 if (partial > len)
962 partial = len;
963 memcpy(write_buffer + buffered, data, partial);
964 buffered += partial;
965 if (buffered == WRITE_BUFFER_SIZE) {
966 write_buffer_len = buffered;
967 if (ce_write_flush(context, fd))
968 return -1;
969 buffered = 0;
970 }
971 write_buffer_len = buffered;
972 len -= partial;
973 data = (char *) data + partial;
974 }
975 return 0;
976 }
977
978 static int write_index_ext_header(SHA_CTX *context, int fd,
979 unsigned int ext, unsigned int sz)
980 {
981 ext = htonl(ext);
982 sz = htonl(sz);
983 return ((ce_write(context, fd, &ext, 4) < 0) ||
984 (ce_write(context, fd, &sz, 4) < 0)) ? -1 : 0;
985 }
986
987 static int ce_flush(SHA_CTX *context, int fd)
988 {
989 unsigned int left = write_buffer_len;
990
991 if (left) {
992 write_buffer_len = 0;
993 SHA1_Update(context, write_buffer, left);
994 }
995
996 /* Flush first if not enough space for SHA1 signature */
997 if (left + 20 > WRITE_BUFFER_SIZE) {
998 if (write_in_full(fd, write_buffer, left) != left)
999 return -1;
1000 left = 0;
1001 }
1002
1003 /* Append the SHA1 signature at the end */
1004 SHA1_Final(write_buffer + left, context);
1005 left += 20;
1006 return (write_in_full(fd, write_buffer, left) != left) ? -1 : 0;
1007 }
1008
1009 static void ce_smudge_racily_clean_entry(struct cache_entry *ce)
1010 {
1011 /*
1012 * The only thing we care about in this function is to smudge the
1013 * falsely clean entry due to touch-update-touch race, so we leave
1014 * everything else as they are. We are called for entries whose
1015 * ce_mtime match the index file mtime.
1016 */
1017 struct stat st;
1018
1019 if (lstat(ce->name, &st) < 0)
1020 return;
1021 if (ce_match_stat_basic(ce, &st))
1022 return;
1023 if (ce_modified_check_fs(ce, &st)) {
1024 /* This is "racily clean"; smudge it. Note that this
1025 * is a tricky code. At first glance, it may appear
1026 * that it can break with this sequence:
1027 *
1028 * $ echo xyzzy >frotz
1029 * $ git-update-index --add frotz
1030 * $ : >frotz
1031 * $ sleep 3
1032 * $ echo filfre >nitfol
1033 * $ git-update-index --add nitfol
1034 *
1035 * but it does not. When the second update-index runs,
1036 * it notices that the entry "frotz" has the same timestamp
1037 * as index, and if we were to smudge it by resetting its
1038 * size to zero here, then the object name recorded
1039 * in index is the 6-byte file but the cached stat information
1040 * becomes zero --- which would then match what we would
1041 * obtain from the filesystem next time we stat("frotz").
1042 *
1043 * However, the second update-index, before calling
1044 * this function, notices that the cached size is 6
1045 * bytes and what is on the filesystem is an empty
1046 * file, and never calls us, so the cached size information
1047 * for "frotz" stays 6 which does not match the filesystem.
1048 */
1049 ce->ce_size = htonl(0);
1050 }
1051 }
1052
1053 int write_index(struct index_state *istate, int newfd)
1054 {
1055 SHA_CTX c;
1056 struct cache_header hdr;
1057 int i, removed;
1058 struct cache_entry **cache = istate->cache;
1059 int entries = istate->cache_nr;
1060
1061 for (i = removed = 0; i < entries; i++)
1062 if (!cache[i]->ce_mode)
1063 removed++;
1064
1065 hdr.hdr_signature = htonl(CACHE_SIGNATURE);
1066 hdr.hdr_version = htonl(2);
1067 hdr.hdr_entries = htonl(entries - removed);
1068
1069 SHA1_Init(&c);
1070 if (ce_write(&c, newfd, &hdr, sizeof(hdr)) < 0)
1071 return -1;
1072
1073 for (i = 0; i < entries; i++) {
1074 struct cache_entry *ce = cache[i];
1075 if (!ce->ce_mode)
1076 continue;
1077 if (istate->timestamp &&
1078 istate->timestamp <= ntohl(ce->ce_mtime.sec))
1079 ce_smudge_racily_clean_entry(ce);
1080 if (ce_write(&c, newfd, ce, ce_size(ce)) < 0)
1081 return -1;
1082 }
1083
1084 /* Write extension data here */
1085 if (istate->cache_tree) {
1086 unsigned long sz;
1087 void *data = cache_tree_write(istate->cache_tree, &sz);
1088 if (data &&
1089 !write_index_ext_header(&c, newfd, CACHE_EXT_TREE, sz) &&
1090 !ce_write(&c, newfd, data, sz))
1091 free(data);
1092 else {
1093 free(data);
1094 return -1;
1095 }
1096 }
1097 return ce_flush(&c, newfd);
1098 }