Merge master.kernel.org:/pub/scm/gitk/gitk
[git/git.git] / read-cache.c
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 unsigned int active_nr = 0, active_alloc = 0, active_cache_changed = 0;
10
11 /*
12 * This only updates the "non-critical" parts of the directory
13 * cache, ie the parts that aren't tracked by GIT, and only used
14 * to validate the cache.
15 */
16 void fill_stat_cache_info(struct cache_entry *ce, struct stat *st)
17 {
18 ce->ce_ctime.sec = htonl(st->st_ctime);
19 ce->ce_mtime.sec = htonl(st->st_mtime);
20 #ifdef USE_NSEC
21 ce->ce_ctime.nsec = htonl(st->st_ctim.tv_nsec);
22 ce->ce_mtime.nsec = htonl(st->st_mtim.tv_nsec);
23 #endif
24 ce->ce_dev = htonl(st->st_dev);
25 ce->ce_ino = htonl(st->st_ino);
26 ce->ce_uid = htonl(st->st_uid);
27 ce->ce_gid = htonl(st->st_gid);
28 ce->ce_size = htonl(st->st_size);
29 }
30
31 int ce_match_stat(struct cache_entry *ce, struct stat *st)
32 {
33 unsigned int changed = 0;
34
35 switch (ntohl(ce->ce_mode) & S_IFMT) {
36 case S_IFREG:
37 changed |= !S_ISREG(st->st_mode) ? TYPE_CHANGED : 0;
38 /* We consider only the owner x bit to be relevant for "mode changes" */
39 if (0100 & (ntohl(ce->ce_mode) ^ st->st_mode))
40 changed |= MODE_CHANGED;
41 break;
42 case S_IFLNK:
43 changed |= !S_ISLNK(st->st_mode) ? TYPE_CHANGED : 0;
44 break;
45 default:
46 die("internal error: ce_mode is %o", ntohl(ce->ce_mode));
47 }
48 if (ce->ce_mtime.sec != htonl(st->st_mtime))
49 changed |= MTIME_CHANGED;
50 if (ce->ce_ctime.sec != htonl(st->st_ctime))
51 changed |= CTIME_CHANGED;
52
53 #ifdef USE_NSEC
54 /*
55 * nsec seems unreliable - not all filesystems support it, so
56 * as long as it is in the inode cache you get right nsec
57 * but after it gets flushed, you get zero nsec.
58 */
59 if (ce->ce_mtime.nsec != htonl(st->st_mtim.tv_nsec))
60 changed |= MTIME_CHANGED;
61 if (ce->ce_ctime.nsec != htonl(st->st_ctim.tv_nsec))
62 changed |= CTIME_CHANGED;
63 #endif
64
65 if (ce->ce_uid != htonl(st->st_uid) ||
66 ce->ce_gid != htonl(st->st_gid))
67 changed |= OWNER_CHANGED;
68 if (ce->ce_ino != htonl(st->st_ino))
69 changed |= INODE_CHANGED;
70
71 #ifdef USE_STDEV
72 /*
73 * st_dev breaks on network filesystems where different
74 * clients will have different views of what "device"
75 * the filesystem is on
76 */
77 if (ce->ce_dev != htonl(st->st_dev))
78 changed |= INODE_CHANGED;
79 #endif
80
81 if (ce->ce_size != htonl(st->st_size))
82 changed |= DATA_CHANGED;
83 return changed;
84 }
85
86 int base_name_compare(const char *name1, int len1, int mode1,
87 const char *name2, int len2, int mode2)
88 {
89 unsigned char c1, c2;
90 int len = len1 < len2 ? len1 : len2;
91 int cmp;
92
93 cmp = memcmp(name1, name2, len);
94 if (cmp)
95 return cmp;
96 c1 = name1[len];
97 c2 = name2[len];
98 if (!c1 && S_ISDIR(mode1))
99 c1 = '/';
100 if (!c2 && S_ISDIR(mode2))
101 c2 = '/';
102 return (c1 < c2) ? -1 : (c1 > c2) ? 1 : 0;
103 }
104
105 int cache_name_compare(const char *name1, int flags1, const char *name2, int flags2)
106 {
107 int len1 = flags1 & CE_NAMEMASK;
108 int len2 = flags2 & CE_NAMEMASK;
109 int len = len1 < len2 ? len1 : len2;
110 int cmp;
111
112 cmp = memcmp(name1, name2, len);
113 if (cmp)
114 return cmp;
115 if (len1 < len2)
116 return -1;
117 if (len1 > len2)
118 return 1;
119 if (flags1 < flags2)
120 return -1;
121 if (flags1 > flags2)
122 return 1;
123 return 0;
124 }
125
126 int cache_name_pos(const char *name, int namelen)
127 {
128 int first, last;
129
130 first = 0;
131 last = active_nr;
132 while (last > first) {
133 int next = (last + first) >> 1;
134 struct cache_entry *ce = active_cache[next];
135 int cmp = cache_name_compare(name, namelen, ce->name, ntohs(ce->ce_flags));
136 if (!cmp)
137 return next;
138 if (cmp < 0) {
139 last = next;
140 continue;
141 }
142 first = next+1;
143 }
144 return -first-1;
145 }
146
147 /* Remove entry, return true if there are more entries to go.. */
148 int remove_cache_entry_at(int pos)
149 {
150 active_cache_changed = 1;
151 active_nr--;
152 if (pos >= active_nr)
153 return 0;
154 memmove(active_cache + pos, active_cache + pos + 1, (active_nr - pos) * sizeof(struct cache_entry *));
155 return 1;
156 }
157
158 int remove_file_from_cache(char *path)
159 {
160 int pos = cache_name_pos(path, strlen(path));
161 if (pos < 0)
162 pos = -pos-1;
163 while (pos < active_nr && !strcmp(active_cache[pos]->name, path))
164 remove_cache_entry_at(pos);
165 return 0;
166 }
167
168 int ce_same_name(struct cache_entry *a, struct cache_entry *b)
169 {
170 int len = ce_namelen(a);
171 return ce_namelen(b) == len && !memcmp(a->name, b->name, len);
172 }
173
174 /*
175 * Do we have another file that has the beginning components being a
176 * proper superset of the name we're trying to add?
177 */
178 static int has_file_name(const struct cache_entry *ce, int pos, int ok_to_replace)
179 {
180 int retval = 0;
181 int len = ce_namelen(ce);
182 int stage = ce_stage(ce);
183 const char *name = ce->name;
184
185 while (pos < active_nr) {
186 struct cache_entry *p = active_cache[pos++];
187
188 if (len >= ce_namelen(p))
189 break;
190 if (memcmp(name, p->name, len))
191 break;
192 if (ce_stage(p) != stage)
193 continue;
194 if (p->name[len] != '/')
195 continue;
196 retval = -1;
197 if (!ok_to_replace)
198 break;
199 remove_cache_entry_at(--pos);
200 }
201 return retval;
202 }
203
204 /*
205 * Do we have another file with a pathname that is a proper
206 * subset of the name we're trying to add?
207 */
208 static int has_dir_name(const struct cache_entry *ce, int pos, int ok_to_replace)
209 {
210 int retval = 0;
211 int stage = ce_stage(ce);
212 const char *name = ce->name;
213 const char *slash = name + ce_namelen(ce);
214
215 for (;;) {
216 int len;
217
218 for (;;) {
219 if (*--slash == '/')
220 break;
221 if (slash <= ce->name)
222 return retval;
223 }
224 len = slash - name;
225
226 pos = cache_name_pos(name, ntohs(create_ce_flags(len, stage)));
227 if (pos >= 0) {
228 retval = -1;
229 if (ok_to_replace)
230 break;
231 remove_cache_entry_at(pos);
232 continue;
233 }
234
235 /*
236 * Trivial optimization: if we find an entry that
237 * already matches the sub-directory, then we know
238 * we're ok, and we can exit.
239 */
240 pos = -pos-1;
241 while (pos < active_nr) {
242 struct cache_entry *p = active_cache[pos];
243 if ((ce_namelen(p) <= len) ||
244 (p->name[len] != '/') ||
245 memcmp(p->name, name, len))
246 break; /* not our subdirectory */
247 if (ce_stage(p) == stage)
248 /* p is at the same stage as our entry, and
249 * is a subdirectory of what we are looking
250 * at, so we cannot have conflicts at our
251 * level or anything shorter.
252 */
253 return retval;
254 pos++;
255 }
256 }
257 return retval;
258 }
259
260 /* We may be in a situation where we already have path/file and path
261 * is being added, or we already have path and path/file is being
262 * added. Either one would result in a nonsense tree that has path
263 * twice when git-write-tree tries to write it out. Prevent it.
264 *
265 * If ok-to-replace is specified, we remove the conflicting entries
266 * from the cache so the caller should recompute the insert position.
267 * When this happens, we return non-zero.
268 */
269 static int check_file_directory_conflict(const struct cache_entry *ce, int pos, int ok_to_replace)
270 {
271 /*
272 * We check if the path is a sub-path of a subsequent pathname
273 * first, since removing those will not change the position
274 * in the array
275 */
276 int retval = has_file_name(ce, pos, ok_to_replace);
277 /*
278 * Then check if the path might have a clashing sub-directory
279 * before it.
280 */
281 return retval + has_dir_name(ce, pos, ok_to_replace);
282 }
283
284 int add_cache_entry(struct cache_entry *ce, int option)
285 {
286 int pos;
287 int ok_to_add = option & ADD_CACHE_OK_TO_ADD;
288 int ok_to_replace = option & ADD_CACHE_OK_TO_REPLACE;
289 int skip_df_check = option & ADD_CACHE_SKIP_DFCHECK;
290 pos = cache_name_pos(ce->name, ntohs(ce->ce_flags));
291
292 /* existing match? Just replace it */
293 if (pos >= 0) {
294 active_cache_changed = 1;
295 active_cache[pos] = ce;
296 return 0;
297 }
298 pos = -pos-1;
299
300 /*
301 * Inserting a merged entry ("stage 0") into the index
302 * will always replace all non-merged entries..
303 */
304 if (pos < active_nr && ce_stage(ce) == 0) {
305 while (ce_same_name(active_cache[pos], ce)) {
306 ok_to_add = 1;
307 if (!remove_cache_entry_at(pos))
308 break;
309 }
310 }
311
312 if (!ok_to_add)
313 return -1;
314
315 if (!skip_df_check && check_file_directory_conflict(ce, pos, ok_to_replace)) {
316 if (!ok_to_replace)
317 return -1;
318 pos = cache_name_pos(ce->name, ntohs(ce->ce_flags));
319 pos = -pos-1;
320 }
321
322 /* Make sure the array is big enough .. */
323 if (active_nr == active_alloc) {
324 active_alloc = alloc_nr(active_alloc);
325 active_cache = xrealloc(active_cache, active_alloc * sizeof(struct cache_entry *));
326 }
327
328 /* Add it in.. */
329 active_nr++;
330 if (active_nr > pos)
331 memmove(active_cache + pos + 1, active_cache + pos, (active_nr - pos - 1) * sizeof(ce));
332 active_cache[pos] = ce;
333 active_cache_changed = 1;
334 return 0;
335 }
336
337 static int verify_hdr(struct cache_header *hdr, unsigned long size)
338 {
339 SHA_CTX c;
340 unsigned char sha1[20];
341
342 if (hdr->hdr_signature != htonl(CACHE_SIGNATURE))
343 return error("bad signature");
344 if (hdr->hdr_version != htonl(2))
345 return error("bad index version");
346 SHA1_Init(&c);
347 SHA1_Update(&c, hdr, size - 20);
348 SHA1_Final(sha1, &c);
349 if (memcmp(sha1, (void *)hdr + size - 20, 20))
350 return error("bad index file sha1 signature");
351 return 0;
352 }
353
354 int read_cache(void)
355 {
356 int fd, i;
357 struct stat st;
358 unsigned long size, offset;
359 void *map;
360 struct cache_header *hdr;
361
362 errno = EBUSY;
363 if (active_cache)
364 return error("more than one cachefile");
365 errno = ENOENT;
366 fd = open(get_index_file(), O_RDONLY);
367 if (fd < 0)
368 return (errno == ENOENT) ? 0 : error("open failed");
369
370 size = 0; // avoid gcc warning
371 map = (void *)-1;
372 if (!fstat(fd, &st)) {
373 size = st.st_size;
374 errno = EINVAL;
375 if (size >= sizeof(struct cache_header) + 20)
376 map = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
377 }
378 close(fd);
379 if (-1 == (int)(long)map)
380 return error("mmap failed");
381
382 hdr = map;
383 if (verify_hdr(hdr, size) < 0)
384 goto unmap;
385
386 active_nr = ntohl(hdr->hdr_entries);
387 active_alloc = alloc_nr(active_nr);
388 active_cache = calloc(active_alloc, sizeof(struct cache_entry *));
389
390 offset = sizeof(*hdr);
391 for (i = 0; i < active_nr; i++) {
392 struct cache_entry *ce = map + offset;
393 offset = offset + ce_size(ce);
394 active_cache[i] = ce;
395 }
396 return active_nr;
397
398 unmap:
399 munmap(map, size);
400 errno = EINVAL;
401 return error("verify header failed");
402 }
403
404 #define WRITE_BUFFER_SIZE 8192
405 static unsigned char write_buffer[WRITE_BUFFER_SIZE];
406 static unsigned long write_buffer_len;
407
408 static int ce_write(SHA_CTX *context, int fd, void *data, unsigned int len)
409 {
410 while (len) {
411 unsigned int buffered = write_buffer_len;
412 unsigned int partial = WRITE_BUFFER_SIZE - buffered;
413 if (partial > len)
414 partial = len;
415 memcpy(write_buffer + buffered, data, partial);
416 buffered += partial;
417 if (buffered == WRITE_BUFFER_SIZE) {
418 SHA1_Update(context, write_buffer, WRITE_BUFFER_SIZE);
419 if (write(fd, write_buffer, WRITE_BUFFER_SIZE) != WRITE_BUFFER_SIZE)
420 return -1;
421 buffered = 0;
422 }
423 write_buffer_len = buffered;
424 len -= partial;
425 data += partial;
426 }
427 return 0;
428 }
429
430 static int ce_flush(SHA_CTX *context, int fd)
431 {
432 unsigned int left = write_buffer_len;
433
434 if (left) {
435 write_buffer_len = 0;
436 SHA1_Update(context, write_buffer, left);
437 }
438
439 /* Append the SHA1 signature at the end */
440 SHA1_Final(write_buffer + left, context);
441 left += 20;
442 if (write(fd, write_buffer, left) != left)
443 return -1;
444 return 0;
445 }
446
447 int write_cache(int newfd, struct cache_entry **cache, int entries)
448 {
449 SHA_CTX c;
450 struct cache_header hdr;
451 int i, removed;
452
453 for (i = removed = 0; i < entries; i++)
454 if (!cache[i]->ce_mode)
455 removed++;
456
457 hdr.hdr_signature = htonl(CACHE_SIGNATURE);
458 hdr.hdr_version = htonl(2);
459 hdr.hdr_entries = htonl(entries - removed);
460
461 SHA1_Init(&c);
462 if (ce_write(&c, newfd, &hdr, sizeof(hdr)) < 0)
463 return -1;
464
465 for (i = 0; i < entries; i++) {
466 struct cache_entry *ce = cache[i];
467 if (!ce->ce_mode)
468 continue;
469 if (ce_write(&c, newfd, ce, ce_size(ce)) < 0)
470 return -1;
471 }
472 return ce_flush(&c, newfd);
473 }