[PATCH] read-tree: save more user hassles during fast-forward.
[git/git.git] / read-cache.c
CommitLineData
8bc9a0c7
LT
1/*
2 * GIT - The information manager from hell
3 *
4 * Copyright (C) Linus Torvalds, 2005
5 */
e83c5163
LT
6#include "cache.h"
7
e83c5163 8struct cache_entry **active_cache = NULL;
ee267527 9unsigned int active_nr = 0, active_alloc = 0, active_cache_changed = 0;
e83c5163 10
415e96c8
JH
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 */
16void 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);
2cb45e95 20#ifdef USE_NSEC
415e96c8
JH
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
5d728c84 31int ce_match_stat(struct cache_entry *ce, struct stat *st)
734aab75
LT
32{
33 unsigned int changed = 0;
34
8ae0a8c5
KS
35 switch (ntohl(ce->ce_mode) & S_IFMT) {
36 case S_IFREG:
37 changed |= !S_ISREG(st->st_mode) ? TYPE_CHANGED : 0;
ffbe1add
KS
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;
8ae0a8c5
KS
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 }
ccc4feb5 48 if (ce->ce_mtime.sec != htonl(st->st_mtime))
734aab75 49 changed |= MTIME_CHANGED;
ccc4feb5
LT
50 if (ce->ce_ctime.sec != htonl(st->st_ctime))
51 changed |= CTIME_CHANGED;
52
2cb45e95 53#ifdef USE_NSEC
ccc4feb5
LT
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 */
94dfb7f2 59 if (ce->ce_mtime.nsec != htonl(st->st_mtim.tv_nsec))
ccc4feb5 60 changed |= MTIME_CHANGED;
94dfb7f2 61 if (ce->ce_ctime.nsec != htonl(st->st_ctim.tv_nsec))
734aab75 62 changed |= CTIME_CHANGED;
ccc4feb5
LT
63#endif
64
65 if (ce->ce_uid != htonl(st->st_uid) ||
66 ce->ce_gid != htonl(st->st_gid))
734aab75 67 changed |= OWNER_CHANGED;
2cb45e95 68 if (ce->ce_ino != htonl(st->st_ino))
734aab75 69 changed |= INODE_CHANGED;
2cb45e95
LT
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
ccc4feb5 81 if (ce->ce_size != htonl(st->st_size))
734aab75
LT
82 changed |= DATA_CHANGED;
83 return changed;
84}
85
958ba6c9
LT
86int 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
95fd5bf8 105int cache_name_compare(const char *name1, int flags1, const char *name2, int flags2)
eb38c22f 106{
95fd5bf8
LT
107 int len1 = flags1 & CE_NAMEMASK;
108 int len2 = flags2 & CE_NAMEMASK;
eb38c22f
LT
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;
95fd5bf8
LT
119 if (flags1 < flags2)
120 return -1;
121 if (flags1 > flags2)
122 return 1;
eb38c22f
LT
123 return 0;
124}
125
126int 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];
95fd5bf8 135 int cmp = cache_name_compare(name, namelen, ce->name, htons(ce->ce_flags));
eb38c22f 136 if (!cmp)
76e7f4ec 137 return next;
eb38c22f
LT
138 if (cmp < 0) {
139 last = next;
140 continue;
141 }
142 first = next+1;
143 }
76e7f4ec 144 return -first-1;
eb38c22f
LT
145}
146
7b937ca3 147/* Remove entry, return true if there are more entries to go.. */
dbbce55b 148int remove_cache_entry_at(int pos)
7b937ca3 149{
ee267527 150 active_cache_changed = 1;
7b937ca3
LT
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
197ee8c9
LT
158int remove_file_from_cache(char *path)
159{
160 int pos = cache_name_pos(path, strlen(path));
c4e3cca1
JH
161 if (pos < 0)
162 pos = -pos-1;
163 while (pos < active_nr && !strcmp(active_cache[pos]->name, path))
dbbce55b 164 remove_cache_entry_at(pos);
197ee8c9
LT
165 return 0;
166}
167
dbbce55b 168int ce_same_name(struct cache_entry *a, struct cache_entry *b)
7b937ca3
LT
169{
170 int len = ce_namelen(a);
171 return ce_namelen(b) == len && !memcmp(a->name, b->name, len);
172}
173
0f1e4f04
JH
174/* We may be in a situation where we already have path/file and path
175 * is being added, or we already have path and path/file is being
176 * added. Either one would result in a nonsense tree that has path
177 * twice when git-write-tree tries to write it out. Prevent it.
192268c1
JH
178 *
179 * If ok-to-replace is specified, we remove the conflicting entries
180 * from the cache so the caller should recompute the insert position.
181 * When this happens, we return non-zero.
0f1e4f04 182 */
192268c1
JH
183static int check_file_directory_conflict(const struct cache_entry *ce,
184 int ok_to_replace)
0f1e4f04 185{
192268c1 186 int pos, replaced = 0;
0f1e4f04
JH
187 const char *path = ce->name;
188 int namelen = strlen(path);
189 int stage = ce_stage(ce);
190 char *pathbuf = xmalloc(namelen + 1);
191 char *cp;
192
193 memcpy(pathbuf, path, namelen + 1);
194
195 /*
196 * We are inserting path/file. Do they have path registered at
197 * the same stage? We need to do this for all the levels of our
198 * subpath.
199 */
200 cp = pathbuf;
201 while (1) {
202 char *ep = strchr(cp, '/');
8310c2c0 203 int len;
aa575f81 204 if (!ep)
0f1e4f04
JH
205 break;
206 *ep = 0; /* first cut it at slash */
8310c2c0 207 len = ep - pathbuf;
0f1e4f04 208 pos = cache_name_pos(pathbuf,
8310c2c0 209 htons(create_ce_flags(len, stage)));
0f1e4f04
JH
210 if (0 <= pos) {
211 /* Our leading path component is registered as a file,
212 * and we are trying to make it a directory. This is
213 * bad.
214 */
192268c1
JH
215 if (!ok_to_replace) {
216 free(pathbuf);
217 return -1;
218 }
219 fprintf(stderr, "removing file '%s' to replace it with a directory to create '%s'.\n", pathbuf, path);
dbbce55b 220 remove_cache_entry_at(pos);
192268c1 221 replaced = 1;
0f1e4f04
JH
222 }
223 *ep = '/'; /* then restore it and go downwards */
224 cp = ep + 1;
225 }
226 free(pathbuf);
227
228 /* Do we have an entry in the cache that makes our path a prefix
229 * of it? That is, are we creating a file where they already expect
230 * a directory there?
231 */
232 pos = cache_name_pos(path,
233 htons(create_ce_flags(namelen, stage)));
234
235 /* (0 <= pos) cannot happen because add_cache_entry()
236 * should have taken care of that case.
237 */
238 pos = -pos-1;
239
240 /* pos would point at an existing entry that would come immediately
241 * after our path. It could be the same as our path in higher stage,
242 * or different path but in a lower stage.
243 *
244 * E.g. when we are inserting path at stage 2,
245 *
246 * 1 path
247 * pos-> 3 path
192268c1
JH
248 * 2 path/file1
249 * 3 path/file1
250 * 2 path/file2
251 * 2 patho
0f1e4f04
JH
252 *
253 * We need to examine pos, ignore it because it is at different
254 * stage, examine next to find the path/file at stage 2, and
192268c1
JH
255 * complain. We need to do this until we are not the leading
256 * path of an existing entry anymore.
0f1e4f04
JH
257 */
258
259 while (pos < active_nr) {
260 struct cache_entry *other = active_cache[pos];
261 if (strncmp(other->name, path, namelen))
262 break; /* it is not our "subdirectory" anymore */
192268c1
JH
263 if ((ce_stage(other) == stage) &&
264 other->name[namelen] == '/') {
265 if (!ok_to_replace)
266 return -1;
267 fprintf(stderr, "removing file '%s' under '%s' to be replaced with a file\n", other->name, path);
dbbce55b 268 remove_cache_entry_at(pos);
192268c1
JH
269 replaced = 1;
270 continue; /* cycle without updating pos */
271 }
0f1e4f04
JH
272 pos++;
273 }
192268c1 274 return replaced;
0f1e4f04
JH
275}
276
192268c1 277int add_cache_entry(struct cache_entry *ce, int option)
197ee8c9
LT
278{
279 int pos;
192268c1
JH
280 int ok_to_add = option & ADD_CACHE_OK_TO_ADD;
281 int ok_to_replace = option & ADD_CACHE_OK_TO_REPLACE;
95fd5bf8 282 pos = cache_name_pos(ce->name, htons(ce->ce_flags));
197ee8c9
LT
283
284 /* existing match? Just replace it */
76e7f4ec 285 if (pos >= 0) {
ee267527 286 active_cache_changed = 1;
76e7f4ec 287 active_cache[pos] = ce;
197ee8c9
LT
288 return 0;
289 }
76e7f4ec 290 pos = -pos-1;
197ee8c9 291
7b937ca3
LT
292 /*
293 * Inserting a merged entry ("stage 0") into the index
294 * will always replace all non-merged entries..
295 */
296 if (pos < active_nr && ce_stage(ce) == 0) {
dbbce55b 297 while (ce_same_name(active_cache[pos], ce)) {
7b937ca3 298 ok_to_add = 1;
dbbce55b 299 if (!remove_cache_entry_at(pos))
7b937ca3
LT
300 break;
301 }
302 }
303
121481ab
LT
304 if (!ok_to_add)
305 return -1;
306
192268c1
JH
307 if (check_file_directory_conflict(ce, ok_to_replace)) {
308 if (!ok_to_replace)
309 return -1;
310 pos = cache_name_pos(ce->name, htons(ce->ce_flags));
311 pos = -pos-1;
312 }
0f1e4f04 313
197ee8c9
LT
314 /* Make sure the array is big enough .. */
315 if (active_nr == active_alloc) {
316 active_alloc = alloc_nr(active_alloc);
812666c8 317 active_cache = xrealloc(active_cache, active_alloc * sizeof(struct cache_entry *));
197ee8c9
LT
318 }
319
320 /* Add it in.. */
321 active_nr++;
322 if (active_nr > pos)
323 memmove(active_cache + pos + 1, active_cache + pos, (active_nr - pos - 1) * sizeof(ce));
324 active_cache[pos] = ce;
ee267527 325 active_cache_changed = 1;
197ee8c9
LT
326 return 0;
327}
328
e83c5163
LT
329static int verify_hdr(struct cache_header *hdr, unsigned long size)
330{
331 SHA_CTX c;
332 unsigned char sha1[20];
333
ccc4feb5 334 if (hdr->hdr_signature != htonl(CACHE_SIGNATURE))
e83c5163 335 return error("bad signature");
ca9be054
LT
336 if (hdr->hdr_version != htonl(2))
337 return error("bad index version");
e83c5163 338 SHA1_Init(&c);
ca9be054 339 SHA1_Update(&c, hdr, size - 20);
e83c5163 340 SHA1_Final(sha1, &c);
ca9be054
LT
341 if (memcmp(sha1, (void *)hdr + size - 20, 20))
342 return error("bad index file sha1 signature");
e83c5163
LT
343 return 0;
344}
345
346int read_cache(void)
347{
348 int fd, i;
349 struct stat st;
350 unsigned long size, offset;
351 void *map;
352 struct cache_header *hdr;
353
354 errno = EBUSY;
355 if (active_cache)
356 return error("more than one cachefile");
357 errno = ENOENT;
bb233d69 358 fd = open(get_index_file(), O_RDONLY);
e83c5163
LT
359 if (fd < 0)
360 return (errno == ENOENT) ? 0 : error("open failed");
361
19b2860c 362 size = 0; // avoid gcc warning
e83c5163
LT
363 map = (void *)-1;
364 if (!fstat(fd, &st)) {
e83c5163
LT
365 size = st.st_size;
366 errno = EINVAL;
ca9be054 367 if (size >= sizeof(struct cache_header) + 20)
520fc241 368 map = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
e83c5163
LT
369 }
370 close(fd);
371 if (-1 == (int)(long)map)
372 return error("mmap failed");
373
374 hdr = map;
375 if (verify_hdr(hdr, size) < 0)
376 goto unmap;
377
ccc4feb5 378 active_nr = ntohl(hdr->hdr_entries);
e83c5163
LT
379 active_alloc = alloc_nr(active_nr);
380 active_cache = calloc(active_alloc, sizeof(struct cache_entry *));
381
382 offset = sizeof(*hdr);
ccc4feb5 383 for (i = 0; i < active_nr; i++) {
e83c5163
LT
384 struct cache_entry *ce = map + offset;
385 offset = offset + ce_size(ce);
386 active_cache[i] = ce;
387 }
388 return active_nr;
389
390unmap:
391 munmap(map, size);
392 errno = EINVAL;
393 return error("verify header failed");
394}
395
4990aadc 396#define WRITE_BUFFER_SIZE 8192
bf0f910d 397static unsigned char write_buffer[WRITE_BUFFER_SIZE];
4990aadc
LT
398static unsigned long write_buffer_len;
399
ca9be054 400static int ce_write(SHA_CTX *context, int fd, void *data, unsigned int len)
4990aadc
LT
401{
402 while (len) {
403 unsigned int buffered = write_buffer_len;
404 unsigned int partial = WRITE_BUFFER_SIZE - buffered;
405 if (partial > len)
406 partial = len;
407 memcpy(write_buffer + buffered, data, partial);
408 buffered += partial;
409 if (buffered == WRITE_BUFFER_SIZE) {
ca9be054 410 SHA1_Update(context, write_buffer, WRITE_BUFFER_SIZE);
4990aadc
LT
411 if (write(fd, write_buffer, WRITE_BUFFER_SIZE) != WRITE_BUFFER_SIZE)
412 return -1;
413 buffered = 0;
414 }
415 write_buffer_len = buffered;
416 len -= partial;
417 data += partial;
418 }
419 return 0;
420}
421
ca9be054 422static int ce_flush(SHA_CTX *context, int fd)
4990aadc
LT
423{
424 unsigned int left = write_buffer_len;
ca9be054 425
4990aadc
LT
426 if (left) {
427 write_buffer_len = 0;
ca9be054 428 SHA1_Update(context, write_buffer, left);
4990aadc 429 }
ca9be054
LT
430
431 /* Append the SHA1 signature at the end */
432 SHA1_Final(write_buffer + left, context);
433 left += 20;
434 if (write(fd, write_buffer, left) != left)
435 return -1;
4990aadc
LT
436 return 0;
437}
438
197ee8c9
LT
439int write_cache(int newfd, struct cache_entry **cache, int entries)
440{
441 SHA_CTX c;
442 struct cache_header hdr;
443 int i;
444
ccc4feb5 445 hdr.hdr_signature = htonl(CACHE_SIGNATURE);
ca9be054 446 hdr.hdr_version = htonl(2);
ccc4feb5 447 hdr.hdr_entries = htonl(entries);
197ee8c9
LT
448
449 SHA1_Init(&c);
ca9be054 450 if (ce_write(&c, newfd, &hdr, sizeof(hdr)) < 0)
197ee8c9
LT
451 return -1;
452
453 for (i = 0; i < entries; i++) {
454 struct cache_entry *ce = cache[i];
ca9be054 455 if (ce_write(&c, newfd, ce, ce_size(ce)) < 0)
197ee8c9
LT
456 return -1;
457 }
ca9be054 458 return ce_flush(&c, newfd);
197ee8c9 459}