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Commit | Line | Data |
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1 | /* | |
2 | * GIT - The information manager from hell | |
3 | * | |
4 | * Copyright (C) Linus Torvalds, 2005 | |
5 | */ | |
6 | #include "cache.h" | |
7 | ||
8 | struct cache_entry **active_cache = NULL; | |
9 | static time_t index_file_timestamp; | |
10 | unsigned 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 | */ | |
17 | void 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 | ||
32 | static int ce_compare_data(struct cache_entry *ce, struct stat *st) | |
33 | { | |
34 | int match = -1; | |
35 | int fd = open(ce->name, O_RDONLY); | |
36 | ||
37 | if (fd >= 0) { | |
38 | unsigned char sha1[20]; | |
39 | if (!index_fd(sha1, fd, st, 0, NULL)) | |
40 | match = memcmp(sha1, ce->sha1, 20); | |
41 | close(fd); | |
42 | } | |
43 | return match; | |
44 | } | |
45 | ||
46 | static int ce_compare_link(struct cache_entry *ce, unsigned long expected_size) | |
47 | { | |
48 | int match = -1; | |
49 | char *target; | |
50 | void *buffer; | |
51 | unsigned long size; | |
52 | char type[10]; | |
53 | int len; | |
54 | ||
55 | target = xmalloc(expected_size); | |
56 | len = readlink(ce->name, target, expected_size); | |
57 | if (len != expected_size) { | |
58 | free(target); | |
59 | return -1; | |
60 | } | |
61 | buffer = read_sha1_file(ce->sha1, type, &size); | |
62 | if (!buffer) { | |
63 | free(target); | |
64 | return -1; | |
65 | } | |
66 | if (size == expected_size) | |
67 | match = memcmp(buffer, target, size); | |
68 | free(buffer); | |
69 | free(target); | |
70 | return match; | |
71 | } | |
72 | ||
73 | static int ce_modified_check_fs(struct cache_entry *ce, struct stat *st) | |
74 | { | |
75 | switch (st->st_mode & S_IFMT) { | |
76 | case S_IFREG: | |
77 | if (ce_compare_data(ce, st)) | |
78 | return DATA_CHANGED; | |
79 | break; | |
80 | case S_IFLNK: | |
81 | if (ce_compare_link(ce, st->st_size)) | |
82 | return DATA_CHANGED; | |
83 | break; | |
84 | default: | |
85 | return TYPE_CHANGED; | |
86 | } | |
87 | return 0; | |
88 | } | |
89 | ||
90 | static int ce_match_stat_basic(struct cache_entry *ce, struct stat *st) | |
91 | { | |
92 | unsigned int changed = 0; | |
93 | ||
94 | switch (ntohl(ce->ce_mode) & S_IFMT) { | |
95 | case S_IFREG: | |
96 | changed |= !S_ISREG(st->st_mode) ? TYPE_CHANGED : 0; | |
97 | /* We consider only the owner x bit to be relevant for | |
98 | * "mode changes" | |
99 | */ | |
100 | if (trust_executable_bit && | |
101 | (0100 & (ntohl(ce->ce_mode) ^ st->st_mode))) | |
102 | changed |= MODE_CHANGED; | |
103 | break; | |
104 | case S_IFLNK: | |
105 | changed |= !S_ISLNK(st->st_mode) ? TYPE_CHANGED : 0; | |
106 | break; | |
107 | default: | |
108 | die("internal error: ce_mode is %o", ntohl(ce->ce_mode)); | |
109 | } | |
110 | if (ce->ce_mtime.sec != htonl(st->st_mtime)) | |
111 | changed |= MTIME_CHANGED; | |
112 | if (ce->ce_ctime.sec != htonl(st->st_ctime)) | |
113 | changed |= CTIME_CHANGED; | |
114 | ||
115 | #ifdef USE_NSEC | |
116 | /* | |
117 | * nsec seems unreliable - not all filesystems support it, so | |
118 | * as long as it is in the inode cache you get right nsec | |
119 | * but after it gets flushed, you get zero nsec. | |
120 | */ | |
121 | if (ce->ce_mtime.nsec != htonl(st->st_mtim.tv_nsec)) | |
122 | changed |= MTIME_CHANGED; | |
123 | if (ce->ce_ctime.nsec != htonl(st->st_ctim.tv_nsec)) | |
124 | changed |= CTIME_CHANGED; | |
125 | #endif | |
126 | ||
127 | if (ce->ce_uid != htonl(st->st_uid) || | |
128 | ce->ce_gid != htonl(st->st_gid)) | |
129 | changed |= OWNER_CHANGED; | |
130 | if (ce->ce_ino != htonl(st->st_ino)) | |
131 | changed |= INODE_CHANGED; | |
132 | ||
133 | #ifdef USE_STDEV | |
134 | /* | |
135 | * st_dev breaks on network filesystems where different | |
136 | * clients will have different views of what "device" | |
137 | * the filesystem is on | |
138 | */ | |
139 | if (ce->ce_dev != htonl(st->st_dev)) | |
140 | changed |= INODE_CHANGED; | |
141 | #endif | |
142 | ||
143 | if (ce->ce_size != htonl(st->st_size)) | |
144 | changed |= DATA_CHANGED; | |
145 | ||
146 | return changed; | |
147 | } | |
148 | ||
149 | int ce_match_stat(struct cache_entry *ce, struct stat *st) | |
150 | { | |
151 | unsigned int changed = ce_match_stat_basic(ce, st); | |
152 | ||
153 | /* | |
154 | * Within 1 second of this sequence: | |
155 | * echo xyzzy >file && git-update-index --add file | |
156 | * running this command: | |
157 | * echo frotz >file | |
158 | * would give a falsely clean cache entry. The mtime and | |
159 | * length match the cache, and other stat fields do not change. | |
160 | * | |
161 | * We could detect this at update-index time (the cache entry | |
162 | * being registered/updated records the same time as "now") | |
163 | * and delay the return from git-update-index, but that would | |
164 | * effectively mean we can make at most one commit per second, | |
165 | * which is not acceptable. Instead, we check cache entries | |
166 | * whose mtime are the same as the index file timestamp more | |
167 | * careful than others. | |
168 | */ | |
169 | if (!changed && | |
170 | index_file_timestamp && | |
171 | index_file_timestamp <= ntohl(ce->ce_mtime.sec)) | |
172 | changed |= ce_modified_check_fs(ce, st); | |
173 | ||
174 | return changed; | |
175 | } | |
176 | ||
177 | int ce_modified(struct cache_entry *ce, struct stat *st) | |
178 | { | |
179 | int changed, changed_fs; | |
180 | changed = ce_match_stat(ce, st); | |
181 | if (!changed) | |
182 | return 0; | |
183 | /* | |
184 | * If the mode or type has changed, there's no point in trying | |
185 | * to refresh the entry - it's not going to match | |
186 | */ | |
187 | if (changed & (MODE_CHANGED | TYPE_CHANGED)) | |
188 | return changed; | |
189 | ||
190 | /* Immediately after read-tree or update-index --cacheinfo, | |
191 | * the length field is zero. For other cases the ce_size | |
192 | * should match the SHA1 recorded in the index entry. | |
193 | */ | |
194 | if ((changed & DATA_CHANGED) && ce->ce_size != htonl(0)) | |
195 | return changed; | |
196 | ||
197 | changed_fs = ce_modified_check_fs(ce, st); | |
198 | if (changed_fs) | |
199 | return changed | changed_fs; | |
200 | return 0; | |
201 | } | |
202 | ||
203 | int base_name_compare(const char *name1, int len1, int mode1, | |
204 | const char *name2, int len2, int mode2) | |
205 | { | |
206 | unsigned char c1, c2; | |
207 | int len = len1 < len2 ? len1 : len2; | |
208 | int cmp; | |
209 | ||
210 | cmp = memcmp(name1, name2, len); | |
211 | if (cmp) | |
212 | return cmp; | |
213 | c1 = name1[len]; | |
214 | c2 = name2[len]; | |
215 | if (!c1 && S_ISDIR(mode1)) | |
216 | c1 = '/'; | |
217 | if (!c2 && S_ISDIR(mode2)) | |
218 | c2 = '/'; | |
219 | return (c1 < c2) ? -1 : (c1 > c2) ? 1 : 0; | |
220 | } | |
221 | ||
222 | int cache_name_compare(const char *name1, int flags1, const char *name2, int flags2) | |
223 | { | |
224 | int len1 = flags1 & CE_NAMEMASK; | |
225 | int len2 = flags2 & CE_NAMEMASK; | |
226 | int len = len1 < len2 ? len1 : len2; | |
227 | int cmp; | |
228 | ||
229 | cmp = memcmp(name1, name2, len); | |
230 | if (cmp) | |
231 | return cmp; | |
232 | if (len1 < len2) | |
233 | return -1; | |
234 | if (len1 > len2) | |
235 | return 1; | |
236 | if (flags1 < flags2) | |
237 | return -1; | |
238 | if (flags1 > flags2) | |
239 | return 1; | |
240 | return 0; | |
241 | } | |
242 | ||
243 | int cache_name_pos(const char *name, int namelen) | |
244 | { | |
245 | int first, last; | |
246 | ||
247 | first = 0; | |
248 | last = active_nr; | |
249 | while (last > first) { | |
250 | int next = (last + first) >> 1; | |
251 | struct cache_entry *ce = active_cache[next]; | |
252 | int cmp = cache_name_compare(name, namelen, ce->name, ntohs(ce->ce_flags)); | |
253 | if (!cmp) | |
254 | return next; | |
255 | if (cmp < 0) { | |
256 | last = next; | |
257 | continue; | |
258 | } | |
259 | first = next+1; | |
260 | } | |
261 | return -first-1; | |
262 | } | |
263 | ||
264 | /* Remove entry, return true if there are more entries to go.. */ | |
265 | int remove_cache_entry_at(int pos) | |
266 | { | |
267 | active_cache_changed = 1; | |
268 | active_nr--; | |
269 | if (pos >= active_nr) | |
270 | return 0; | |
271 | memmove(active_cache + pos, active_cache + pos + 1, (active_nr - pos) * sizeof(struct cache_entry *)); | |
272 | return 1; | |
273 | } | |
274 | ||
275 | int remove_file_from_cache(const char *path) | |
276 | { | |
277 | int pos = cache_name_pos(path, strlen(path)); | |
278 | if (pos < 0) | |
279 | pos = -pos-1; | |
280 | while (pos < active_nr && !strcmp(active_cache[pos]->name, path)) | |
281 | remove_cache_entry_at(pos); | |
282 | return 0; | |
283 | } | |
284 | ||
285 | int ce_same_name(struct cache_entry *a, struct cache_entry *b) | |
286 | { | |
287 | int len = ce_namelen(a); | |
288 | return ce_namelen(b) == len && !memcmp(a->name, b->name, len); | |
289 | } | |
290 | ||
291 | int ce_path_match(const struct cache_entry *ce, const char **pathspec) | |
292 | { | |
293 | const char *match, *name; | |
294 | int len; | |
295 | ||
296 | if (!pathspec) | |
297 | return 1; | |
298 | ||
299 | len = ce_namelen(ce); | |
300 | name = ce->name; | |
301 | while ((match = *pathspec++) != NULL) { | |
302 | int matchlen = strlen(match); | |
303 | if (matchlen > len) | |
304 | continue; | |
305 | if (memcmp(name, match, matchlen)) | |
306 | continue; | |
307 | if (matchlen && name[matchlen-1] == '/') | |
308 | return 1; | |
309 | if (name[matchlen] == '/' || !name[matchlen]) | |
310 | return 1; | |
311 | if (!matchlen) | |
312 | return 1; | |
313 | } | |
314 | return 0; | |
315 | } | |
316 | ||
317 | /* | |
318 | * Do we have another file that has the beginning components being a | |
319 | * proper superset of the name we're trying to add? | |
320 | */ | |
321 | static int has_file_name(const struct cache_entry *ce, int pos, int ok_to_replace) | |
322 | { | |
323 | int retval = 0; | |
324 | int len = ce_namelen(ce); | |
325 | int stage = ce_stage(ce); | |
326 | const char *name = ce->name; | |
327 | ||
328 | while (pos < active_nr) { | |
329 | struct cache_entry *p = active_cache[pos++]; | |
330 | ||
331 | if (len >= ce_namelen(p)) | |
332 | break; | |
333 | if (memcmp(name, p->name, len)) | |
334 | break; | |
335 | if (ce_stage(p) != stage) | |
336 | continue; | |
337 | if (p->name[len] != '/') | |
338 | continue; | |
339 | retval = -1; | |
340 | if (!ok_to_replace) | |
341 | break; | |
342 | remove_cache_entry_at(--pos); | |
343 | } | |
344 | return retval; | |
345 | } | |
346 | ||
347 | /* | |
348 | * Do we have another file with a pathname that is a proper | |
349 | * subset of the name we're trying to add? | |
350 | */ | |
351 | static int has_dir_name(const struct cache_entry *ce, int pos, int ok_to_replace) | |
352 | { | |
353 | int retval = 0; | |
354 | int stage = ce_stage(ce); | |
355 | const char *name = ce->name; | |
356 | const char *slash = name + ce_namelen(ce); | |
357 | ||
358 | for (;;) { | |
359 | int len; | |
360 | ||
361 | for (;;) { | |
362 | if (*--slash == '/') | |
363 | break; | |
364 | if (slash <= ce->name) | |
365 | return retval; | |
366 | } | |
367 | len = slash - name; | |
368 | ||
369 | pos = cache_name_pos(name, ntohs(create_ce_flags(len, stage))); | |
370 | if (pos >= 0) { | |
371 | retval = -1; | |
372 | if (ok_to_replace) | |
373 | break; | |
374 | remove_cache_entry_at(pos); | |
375 | continue; | |
376 | } | |
377 | ||
378 | /* | |
379 | * Trivial optimization: if we find an entry that | |
380 | * already matches the sub-directory, then we know | |
381 | * we're ok, and we can exit. | |
382 | */ | |
383 | pos = -pos-1; | |
384 | while (pos < active_nr) { | |
385 | struct cache_entry *p = active_cache[pos]; | |
386 | if ((ce_namelen(p) <= len) || | |
387 | (p->name[len] != '/') || | |
388 | memcmp(p->name, name, len)) | |
389 | break; /* not our subdirectory */ | |
390 | if (ce_stage(p) == stage) | |
391 | /* p is at the same stage as our entry, and | |
392 | * is a subdirectory of what we are looking | |
393 | * at, so we cannot have conflicts at our | |
394 | * level or anything shorter. | |
395 | */ | |
396 | return retval; | |
397 | pos++; | |
398 | } | |
399 | } | |
400 | return retval; | |
401 | } | |
402 | ||
403 | /* We may be in a situation where we already have path/file and path | |
404 | * is being added, or we already have path and path/file is being | |
405 | * added. Either one would result in a nonsense tree that has path | |
406 | * twice when git-write-tree tries to write it out. Prevent it. | |
407 | * | |
408 | * If ok-to-replace is specified, we remove the conflicting entries | |
409 | * from the cache so the caller should recompute the insert position. | |
410 | * When this happens, we return non-zero. | |
411 | */ | |
412 | static int check_file_directory_conflict(const struct cache_entry *ce, int pos, int ok_to_replace) | |
413 | { | |
414 | /* | |
415 | * We check if the path is a sub-path of a subsequent pathname | |
416 | * first, since removing those will not change the position | |
417 | * in the array | |
418 | */ | |
419 | int retval = has_file_name(ce, pos, ok_to_replace); | |
420 | /* | |
421 | * Then check if the path might have a clashing sub-directory | |
422 | * before it. | |
423 | */ | |
424 | return retval + has_dir_name(ce, pos, ok_to_replace); | |
425 | } | |
426 | ||
427 | int add_cache_entry(struct cache_entry *ce, int option) | |
428 | { | |
429 | int pos; | |
430 | int ok_to_add = option & ADD_CACHE_OK_TO_ADD; | |
431 | int ok_to_replace = option & ADD_CACHE_OK_TO_REPLACE; | |
432 | int skip_df_check = option & ADD_CACHE_SKIP_DFCHECK; | |
433 | pos = cache_name_pos(ce->name, ntohs(ce->ce_flags)); | |
434 | ||
435 | /* existing match? Just replace it. */ | |
436 | if (pos >= 0) { | |
437 | active_cache_changed = 1; | |
438 | active_cache[pos] = ce; | |
439 | return 0; | |
440 | } | |
441 | pos = -pos-1; | |
442 | ||
443 | /* | |
444 | * Inserting a merged entry ("stage 0") into the index | |
445 | * will always replace all non-merged entries.. | |
446 | */ | |
447 | if (pos < active_nr && ce_stage(ce) == 0) { | |
448 | while (ce_same_name(active_cache[pos], ce)) { | |
449 | ok_to_add = 1; | |
450 | if (!remove_cache_entry_at(pos)) | |
451 | break; | |
452 | } | |
453 | } | |
454 | ||
455 | if (!ok_to_add) | |
456 | return -1; | |
457 | ||
458 | if (!skip_df_check && | |
459 | check_file_directory_conflict(ce, pos, ok_to_replace)) { | |
460 | if (!ok_to_replace) | |
461 | return -1; | |
462 | pos = cache_name_pos(ce->name, ntohs(ce->ce_flags)); | |
463 | pos = -pos-1; | |
464 | } | |
465 | ||
466 | /* Make sure the array is big enough .. */ | |
467 | if (active_nr == active_alloc) { | |
468 | active_alloc = alloc_nr(active_alloc); | |
469 | active_cache = xrealloc(active_cache, active_alloc * sizeof(struct cache_entry *)); | |
470 | } | |
471 | ||
472 | /* Add it in.. */ | |
473 | active_nr++; | |
474 | if (active_nr > pos) | |
475 | memmove(active_cache + pos + 1, active_cache + pos, (active_nr - pos - 1) * sizeof(ce)); | |
476 | active_cache[pos] = ce; | |
477 | active_cache_changed = 1; | |
478 | return 0; | |
479 | } | |
480 | ||
481 | static int verify_hdr(struct cache_header *hdr, unsigned long size) | |
482 | { | |
483 | SHA_CTX c; | |
484 | unsigned char sha1[20]; | |
485 | ||
486 | if (hdr->hdr_signature != htonl(CACHE_SIGNATURE)) | |
487 | return error("bad signature"); | |
488 | if (hdr->hdr_version != htonl(2)) | |
489 | return error("bad index version"); | |
490 | SHA1_Init(&c); | |
491 | SHA1_Update(&c, hdr, size - 20); | |
492 | SHA1_Final(sha1, &c); | |
493 | if (memcmp(sha1, (void *)hdr + size - 20, 20)) | |
494 | return error("bad index file sha1 signature"); | |
495 | return 0; | |
496 | } | |
497 | ||
498 | int read_cache(void) | |
499 | { | |
500 | int fd, i; | |
501 | struct stat st; | |
502 | unsigned long size, offset; | |
503 | void *map; | |
504 | struct cache_header *hdr; | |
505 | ||
506 | errno = EBUSY; | |
507 | if (active_cache) | |
508 | return active_nr; | |
509 | ||
510 | errno = ENOENT; | |
511 | index_file_timestamp = 0; | |
512 | fd = open(get_index_file(), O_RDONLY); | |
513 | if (fd < 0) { | |
514 | if (errno == ENOENT) | |
515 | return 0; | |
516 | die("index file open failed (%s)", strerror(errno)); | |
517 | } | |
518 | ||
519 | size = 0; // avoid gcc warning | |
520 | map = MAP_FAILED; | |
521 | if (!fstat(fd, &st)) { | |
522 | size = st.st_size; | |
523 | errno = EINVAL; | |
524 | if (size >= sizeof(struct cache_header) + 20) | |
525 | map = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0); | |
526 | } | |
527 | close(fd); | |
528 | if (map == MAP_FAILED) | |
529 | die("index file mmap failed (%s)", strerror(errno)); | |
530 | ||
531 | hdr = map; | |
532 | if (verify_hdr(hdr, size) < 0) | |
533 | goto unmap; | |
534 | ||
535 | active_nr = ntohl(hdr->hdr_entries); | |
536 | active_alloc = alloc_nr(active_nr); | |
537 | active_cache = calloc(active_alloc, sizeof(struct cache_entry *)); | |
538 | ||
539 | offset = sizeof(*hdr); | |
540 | for (i = 0; i < active_nr; i++) { | |
541 | struct cache_entry *ce = map + offset; | |
542 | offset = offset + ce_size(ce); | |
543 | active_cache[i] = ce; | |
544 | } | |
545 | index_file_timestamp = st.st_mtime; | |
546 | return active_nr; | |
547 | ||
548 | unmap: | |
549 | munmap(map, size); | |
550 | errno = EINVAL; | |
551 | die("index file corrupt"); | |
552 | } | |
553 | ||
554 | #define WRITE_BUFFER_SIZE 8192 | |
555 | static unsigned char write_buffer[WRITE_BUFFER_SIZE]; | |
556 | static unsigned long write_buffer_len; | |
557 | ||
558 | static int ce_write(SHA_CTX *context, int fd, void *data, unsigned int len) | |
559 | { | |
560 | while (len) { | |
561 | unsigned int buffered = write_buffer_len; | |
562 | unsigned int partial = WRITE_BUFFER_SIZE - buffered; | |
563 | if (partial > len) | |
564 | partial = len; | |
565 | memcpy(write_buffer + buffered, data, partial); | |
566 | buffered += partial; | |
567 | if (buffered == WRITE_BUFFER_SIZE) { | |
568 | SHA1_Update(context, write_buffer, WRITE_BUFFER_SIZE); | |
569 | if (write(fd, write_buffer, WRITE_BUFFER_SIZE) != WRITE_BUFFER_SIZE) | |
570 | return -1; | |
571 | buffered = 0; | |
572 | } | |
573 | write_buffer_len = buffered; | |
574 | len -= partial; | |
575 | data += partial; | |
576 | } | |
577 | return 0; | |
578 | } | |
579 | ||
580 | static int ce_flush(SHA_CTX *context, int fd) | |
581 | { | |
582 | unsigned int left = write_buffer_len; | |
583 | ||
584 | if (left) { | |
585 | write_buffer_len = 0; | |
586 | SHA1_Update(context, write_buffer, left); | |
587 | } | |
588 | ||
589 | /* Flush first if not enough space for SHA1 signature */ | |
590 | if (left + 20 > WRITE_BUFFER_SIZE) { | |
591 | if (write(fd, write_buffer, left) != left) | |
592 | return -1; | |
593 | left = 0; | |
594 | } | |
595 | ||
596 | /* Append the SHA1 signature at the end */ | |
597 | SHA1_Final(write_buffer + left, context); | |
598 | left += 20; | |
599 | if (write(fd, write_buffer, left) != left) | |
600 | return -1; | |
601 | return 0; | |
602 | } | |
603 | ||
604 | static void ce_smudge_racily_clean_entry(struct cache_entry *ce) | |
605 | { | |
606 | /* | |
607 | * The only thing we care about in this function is to smudge the | |
608 | * falsely clean entry due to touch-update-touch race, so we leave | |
609 | * everything else as they are. We are called for entries whose | |
610 | * ce_mtime match the index file mtime. | |
611 | */ | |
612 | struct stat st; | |
613 | ||
614 | if (lstat(ce->name, &st) < 0) | |
615 | return; | |
616 | if (ce_match_stat_basic(ce, &st)) | |
617 | return; | |
618 | if (ce_modified_check_fs(ce, &st)) { | |
619 | /* This is "racily clean"; smudge it. Note that this | |
620 | * is a tricky code. At first glance, it may appear | |
621 | * that it can break with this sequence: | |
622 | * | |
623 | * $ echo xyzzy >frotz | |
624 | * $ git-update-index --add frotz | |
625 | * $ : >frotz | |
626 | * $ sleep 3 | |
627 | * $ echo filfre >nitfol | |
628 | * $ git-update-index --add nitfol | |
629 | * | |
630 | * but it does not. Whe the second update-index runs, | |
631 | * it notices that the entry "frotz" has the same timestamp | |
632 | * as index, and if we were to smudge it by resetting its | |
633 | * size to zero here, then the object name recorded | |
634 | * in index is the 6-byte file but the cached stat information | |
635 | * becomes zero --- which would then match what we would | |
636 | * obtain from the filesystem next time we stat("frotz"). | |
637 | * | |
638 | * However, the second update-index, before calling | |
639 | * this function, notices that the cached size is 6 | |
640 | * bytes and what is on the filesystem is an empty | |
641 | * file, and never calls us, so the cached size information | |
642 | * for "frotz" stays 6 which does not match the filesystem. | |
643 | */ | |
644 | ce->ce_size = htonl(0); | |
645 | } | |
646 | } | |
647 | ||
648 | int write_cache(int newfd, struct cache_entry **cache, int entries) | |
649 | { | |
650 | SHA_CTX c; | |
651 | struct cache_header hdr; | |
652 | int i, removed; | |
653 | ||
654 | for (i = removed = 0; i < entries; i++) | |
655 | if (!cache[i]->ce_mode) | |
656 | removed++; | |
657 | ||
658 | hdr.hdr_signature = htonl(CACHE_SIGNATURE); | |
659 | hdr.hdr_version = htonl(2); | |
660 | hdr.hdr_entries = htonl(entries - removed); | |
661 | ||
662 | SHA1_Init(&c); | |
663 | if (ce_write(&c, newfd, &hdr, sizeof(hdr)) < 0) | |
664 | return -1; | |
665 | ||
666 | for (i = 0; i < entries; i++) { | |
667 | struct cache_entry *ce = cache[i]; | |
668 | if (!ce->ce_mode) | |
669 | continue; | |
670 | if (index_file_timestamp && | |
671 | index_file_timestamp <= ntohl(ce->ce_mtime.sec)) | |
672 | ce_smudge_racily_clean_entry(ce); | |
673 | if (ce_write(&c, newfd, ce, ce_size(ce)) < 0) | |
674 | return -1; | |
675 | } | |
676 | return ce_flush(&c, newfd); | |
677 | } |