[PATCH] fix compare symlink against readlink not data
[git/git.git] / read-cache.c
1 /*
2 * GIT - The information manager from hell
3 *
4 * Copyright (C) Linus Torvalds, 2005
5 */
6 #include <stdarg.h>
7 #include "cache.h"
8
9 struct cache_entry **active_cache = NULL;
10 unsigned int active_nr = 0, active_alloc = 0;
11
12 int cache_match_stat(struct cache_entry *ce, struct stat *st)
13 {
14 unsigned int changed = 0;
15
16 switch (ntohl(ce->ce_mode) & S_IFMT) {
17 case S_IFREG:
18 changed |= !S_ISREG(st->st_mode) ? TYPE_CHANGED : 0;
19 /* We consider only the owner x bit to be relevant for "mode changes" */
20 if (0100 & (ntohl(ce->ce_mode) ^ st->st_mode))
21 changed |= MODE_CHANGED;
22 break;
23 case S_IFLNK:
24 changed |= !S_ISLNK(st->st_mode) ? TYPE_CHANGED : 0;
25 break;
26 default:
27 die("internal error: ce_mode is %o", ntohl(ce->ce_mode));
28 }
29 if (ce->ce_mtime.sec != htonl(st->st_mtime))
30 changed |= MTIME_CHANGED;
31 if (ce->ce_ctime.sec != htonl(st->st_ctime))
32 changed |= CTIME_CHANGED;
33
34 #ifdef NSEC
35 /*
36 * nsec seems unreliable - not all filesystems support it, so
37 * as long as it is in the inode cache you get right nsec
38 * but after it gets flushed, you get zero nsec.
39 */
40 if (ce->ce_mtime.nsec != htonl(st->st_mtim.tv_nsec))
41 changed |= MTIME_CHANGED;
42 if (ce->ce_ctime.nsec != htonl(st->st_ctim.tv_nsec))
43 changed |= CTIME_CHANGED;
44 #endif
45
46 if (ce->ce_uid != htonl(st->st_uid) ||
47 ce->ce_gid != htonl(st->st_gid))
48 changed |= OWNER_CHANGED;
49 if (ce->ce_dev != htonl(st->st_dev) ||
50 ce->ce_ino != htonl(st->st_ino))
51 changed |= INODE_CHANGED;
52 if (ce->ce_size != htonl(st->st_size))
53 changed |= DATA_CHANGED;
54 return changed;
55 }
56
57 int cache_name_compare(const char *name1, int flags1, const char *name2, int flags2)
58 {
59 int len1 = flags1 & CE_NAMEMASK;
60 int len2 = flags2 & CE_NAMEMASK;
61 int len = len1 < len2 ? len1 : len2;
62 int cmp;
63
64 cmp = memcmp(name1, name2, len);
65 if (cmp)
66 return cmp;
67 if (len1 < len2)
68 return -1;
69 if (len1 > len2)
70 return 1;
71 if (flags1 < flags2)
72 return -1;
73 if (flags1 > flags2)
74 return 1;
75 return 0;
76 }
77
78 int cache_name_pos(const char *name, int namelen)
79 {
80 int first, last;
81
82 first = 0;
83 last = active_nr;
84 while (last > first) {
85 int next = (last + first) >> 1;
86 struct cache_entry *ce = active_cache[next];
87 int cmp = cache_name_compare(name, namelen, ce->name, htons(ce->ce_flags));
88 if (!cmp)
89 return next;
90 if (cmp < 0) {
91 last = next;
92 continue;
93 }
94 first = next+1;
95 }
96 return -first-1;
97 }
98
99 /* Remove entry, return true if there are more entries to go.. */
100 int remove_entry_at(int pos)
101 {
102 active_nr--;
103 if (pos >= active_nr)
104 return 0;
105 memmove(active_cache + pos, active_cache + pos + 1, (active_nr - pos) * sizeof(struct cache_entry *));
106 return 1;
107 }
108
109 int remove_file_from_cache(char *path)
110 {
111 int pos = cache_name_pos(path, strlen(path));
112 if (pos < 0)
113 pos = -pos-1;
114 while (pos < active_nr && !strcmp(active_cache[pos]->name, path))
115 remove_entry_at(pos);
116 return 0;
117 }
118
119 int same_name(struct cache_entry *a, struct cache_entry *b)
120 {
121 int len = ce_namelen(a);
122 return ce_namelen(b) == len && !memcmp(a->name, b->name, len);
123 }
124
125 int add_cache_entry(struct cache_entry *ce, int ok_to_add)
126 {
127 int pos;
128
129 pos = cache_name_pos(ce->name, htons(ce->ce_flags));
130
131 /* existing match? Just replace it */
132 if (pos >= 0) {
133 active_cache[pos] = ce;
134 return 0;
135 }
136 pos = -pos-1;
137
138 /*
139 * Inserting a merged entry ("stage 0") into the index
140 * will always replace all non-merged entries..
141 */
142 if (pos < active_nr && ce_stage(ce) == 0) {
143 while (same_name(active_cache[pos], ce)) {
144 ok_to_add = 1;
145 if (!remove_entry_at(pos))
146 break;
147 }
148 }
149
150 if (!ok_to_add)
151 return -1;
152
153 /* Make sure the array is big enough .. */
154 if (active_nr == active_alloc) {
155 active_alloc = alloc_nr(active_alloc);
156 active_cache = xrealloc(active_cache, active_alloc * sizeof(struct cache_entry *));
157 }
158
159 /* Add it in.. */
160 active_nr++;
161 if (active_nr > pos)
162 memmove(active_cache + pos + 1, active_cache + pos, (active_nr - pos - 1) * sizeof(ce));
163 active_cache[pos] = ce;
164 return 0;
165 }
166
167 static int verify_hdr(struct cache_header *hdr, unsigned long size)
168 {
169 SHA_CTX c;
170 unsigned char sha1[20];
171
172 if (hdr->hdr_signature != htonl(CACHE_SIGNATURE))
173 return error("bad signature");
174 if (hdr->hdr_version != htonl(2))
175 return error("bad index version");
176 SHA1_Init(&c);
177 SHA1_Update(&c, hdr, size - 20);
178 SHA1_Final(sha1, &c);
179 if (memcmp(sha1, (void *)hdr + size - 20, 20))
180 return error("bad index file sha1 signature");
181 return 0;
182 }
183
184 int read_cache(void)
185 {
186 int fd, i;
187 struct stat st;
188 unsigned long size, offset;
189 void *map;
190 struct cache_header *hdr;
191
192 errno = EBUSY;
193 if (active_cache)
194 return error("more than one cachefile");
195 errno = ENOENT;
196 sha1_file_directory = getenv(DB_ENVIRONMENT);
197 if (!sha1_file_directory)
198 sha1_file_directory = DEFAULT_DB_ENVIRONMENT;
199 if (access(sha1_file_directory, X_OK) < 0)
200 return error("no access to SHA1 file directory");
201 fd = open(get_index_file(), O_RDONLY);
202 if (fd < 0)
203 return (errno == ENOENT) ? 0 : error("open failed");
204
205 size = 0; // avoid gcc warning
206 map = (void *)-1;
207 if (!fstat(fd, &st)) {
208 size = st.st_size;
209 errno = EINVAL;
210 if (size >= sizeof(struct cache_header) + 20)
211 map = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
212 }
213 close(fd);
214 if (-1 == (int)(long)map)
215 return error("mmap failed");
216
217 hdr = map;
218 if (verify_hdr(hdr, size) < 0)
219 goto unmap;
220
221 active_nr = ntohl(hdr->hdr_entries);
222 active_alloc = alloc_nr(active_nr);
223 active_cache = calloc(active_alloc, sizeof(struct cache_entry *));
224
225 offset = sizeof(*hdr);
226 for (i = 0; i < active_nr; i++) {
227 struct cache_entry *ce = map + offset;
228 offset = offset + ce_size(ce);
229 active_cache[i] = ce;
230 }
231 return active_nr;
232
233 unmap:
234 munmap(map, size);
235 errno = EINVAL;
236 return error("verify header failed");
237 }
238
239 #define WRITE_BUFFER_SIZE 8192
240 static char write_buffer[WRITE_BUFFER_SIZE];
241 static unsigned long write_buffer_len;
242
243 static int ce_write(SHA_CTX *context, int fd, void *data, unsigned int len)
244 {
245 while (len) {
246 unsigned int buffered = write_buffer_len;
247 unsigned int partial = WRITE_BUFFER_SIZE - buffered;
248 if (partial > len)
249 partial = len;
250 memcpy(write_buffer + buffered, data, partial);
251 buffered += partial;
252 if (buffered == WRITE_BUFFER_SIZE) {
253 SHA1_Update(context, write_buffer, WRITE_BUFFER_SIZE);
254 if (write(fd, write_buffer, WRITE_BUFFER_SIZE) != WRITE_BUFFER_SIZE)
255 return -1;
256 buffered = 0;
257 }
258 write_buffer_len = buffered;
259 len -= partial;
260 data += partial;
261 }
262 return 0;
263 }
264
265 static int ce_flush(SHA_CTX *context, int fd)
266 {
267 unsigned int left = write_buffer_len;
268
269 if (left) {
270 write_buffer_len = 0;
271 SHA1_Update(context, write_buffer, left);
272 }
273
274 /* Append the SHA1 signature at the end */
275 SHA1_Final(write_buffer + left, context);
276 left += 20;
277 if (write(fd, write_buffer, left) != left)
278 return -1;
279 return 0;
280 }
281
282 int write_cache(int newfd, struct cache_entry **cache, int entries)
283 {
284 SHA_CTX c;
285 struct cache_header hdr;
286 int i;
287
288 hdr.hdr_signature = htonl(CACHE_SIGNATURE);
289 hdr.hdr_version = htonl(2);
290 hdr.hdr_entries = htonl(entries);
291
292 SHA1_Init(&c);
293 if (ce_write(&c, newfd, &hdr, sizeof(hdr)) < 0)
294 return -1;
295
296 for (i = 0; i < entries; i++) {
297 struct cache_entry *ce = cache[i];
298 if (ce_write(&c, newfd, ce, ce_size(ce)) < 0)
299 return -1;
300 }
301 return ce_flush(&c, newfd);
302 }