Convert update-ref to use ref_lock API.
[git/git.git] / refs.c
CommitLineData
95fc7512
DB
1#include "refs.h"
2#include "cache.h"
3
4#include <errno.h>
5
ca8db142
LT
6/* We allow "recursive" symbolic refs. Only within reason, though */
7#define MAXDEPTH 5
8
a876ed83 9const char *resolve_ref(const char *path, unsigned char *sha1, int reading)
8a65ff76 10{
a876ed83
JH
11 int depth = MAXDEPTH, len;
12 char buffer[256];
ca8db142 13
a876ed83
JH
14 for (;;) {
15 struct stat st;
16 char *buf;
17 int fd;
8a65ff76 18
a876ed83
JH
19 if (--depth < 0)
20 return NULL;
ca8db142 21
a876ed83
JH
22 /* Special case: non-existing file.
23 * Not having the refs/heads/new-branch is OK
24 * if we are writing into it, so is .git/HEAD
25 * that points at refs/heads/master still to be
26 * born. It is NOT OK if we are resolving for
27 * reading.
28 */
29 if (lstat(path, &st) < 0) {
30 if (reading || errno != ENOENT)
31 return NULL;
32 memset(sha1, 0, 20);
33 return path;
34 }
ca8db142 35
a876ed83
JH
36 /* Follow "normalized" - ie "refs/.." symlinks by hand */
37 if (S_ISLNK(st.st_mode)) {
38 len = readlink(path, buffer, sizeof(buffer)-1);
39 if (len >= 5 && !memcmp("refs/", buffer, 5)) {
40 path = git_path("%.*s", len, buffer);
41 continue;
42 }
ca8db142 43 }
a876ed83
JH
44
45 /*
46 * Anything else, just open it and try to use it as
47 * a ref
48 */
49 fd = open(path, O_RDONLY);
50 if (fd < 0)
51 return NULL;
52 len = read(fd, buffer, sizeof(buffer)-1);
53 close(fd);
54
55 /*
56 * Is it a symbolic ref?
57 */
58 if (len < 4 || memcmp("ref:", buffer, 4))
59 break;
60 buf = buffer + 4;
61 len -= 4;
62 while (len && isspace(*buf))
63 buf++, len--;
64 while (len && isspace(buf[len-1]))
65 buf[--len] = 0;
66 path = git_path("%.*s", len, buf);
8a65ff76 67 }
a876ed83
JH
68 if (len < 40 || get_sha1_hex(buffer, sha1))
69 return NULL;
70 return path;
71}
72
8098a178
JH
73int create_symref(const char *git_HEAD, const char *refs_heads_master)
74{
8098a178
JH
75 const char *lockpath;
76 char ref[1000];
77 int fd, len, written;
78
9f0bb90d
JH
79#ifndef NO_SYMLINK_HEAD
80 if (prefer_symlink_refs) {
f8348be3
JS
81 unlink(git_HEAD);
82 if (!symlink(refs_heads_master, git_HEAD))
83 return 0;
84 fprintf(stderr, "no symlink - falling back to symbolic ref\n");
85 }
303958dc
JS
86#endif
87
8098a178
JH
88 len = snprintf(ref, sizeof(ref), "ref: %s\n", refs_heads_master);
89 if (sizeof(ref) <= len) {
90 error("refname too long: %s", refs_heads_master);
91 return -1;
92 }
93 lockpath = mkpath("%s.lock", git_HEAD);
94 fd = open(lockpath, O_CREAT | O_EXCL | O_WRONLY, 0666);
95 written = write(fd, ref, len);
96 close(fd);
97 if (written != len) {
98 unlink(lockpath);
99 error("Unable to write to %s", lockpath);
100 return -2;
101 }
102 if (rename(lockpath, git_HEAD) < 0) {
103 unlink(lockpath);
104 error("Unable to create %s", git_HEAD);
105 return -3;
106 }
107 return 0;
8098a178
JH
108}
109
a876ed83
JH
110int read_ref(const char *filename, unsigned char *sha1)
111{
112 if (resolve_ref(filename, sha1, 1))
113 return 0;
114 return -1;
8a65ff76
LT
115}
116
a62be77f 117static int do_for_each_ref(const char *base, int (*fn)(const char *path, const unsigned char *sha1), int trim)
8a65ff76
LT
118{
119 int retval = 0;
4ec99bf0 120 DIR *dir = opendir(git_path("%s", base));
8a65ff76
LT
121
122 if (dir) {
123 struct dirent *de;
124 int baselen = strlen(base);
125 char *path = xmalloc(baselen + 257);
6cada6a9
LT
126
127 if (!strncmp(base, "./", 2)) {
128 base += 2;
129 baselen -= 2;
130 }
8a65ff76 131 memcpy(path, base, baselen);
944d8589
LT
132 if (baselen && base[baselen-1] != '/')
133 path[baselen++] = '/';
8a65ff76
LT
134
135 while ((de = readdir(dir)) != NULL) {
136 unsigned char sha1[20];
137 struct stat st;
138 int namelen;
139
140 if (de->d_name[0] == '.')
141 continue;
142 namelen = strlen(de->d_name);
143 if (namelen > 255)
144 continue;
145 memcpy(path + baselen, de->d_name, namelen+1);
a7e66ae3 146 if (stat(git_path("%s", path), &st) < 0)
8a65ff76
LT
147 continue;
148 if (S_ISDIR(st.st_mode)) {
a62be77f 149 retval = do_for_each_ref(path, fn, trim);
8a65ff76
LT
150 if (retval)
151 break;
152 continue;
153 }
c401cb48 154 if (read_ref(git_path("%s", path), sha1) < 0) {
f61c2c97 155 error("%s points nowhere!", path);
8a65ff76 156 continue;
c401cb48
JS
157 }
158 if (!has_sha1_file(sha1)) {
f61c2c97
JH
159 error("%s does not point to a valid "
160 "commit object!", path);
8a65ff76 161 continue;
c401cb48 162 }
a62be77f 163 retval = fn(path + trim, sha1);
8a65ff76
LT
164 if (retval)
165 break;
166 }
167 free(path);
168 closedir(dir);
169 }
170 return retval;
171}
172
723c31fe
LT
173int head_ref(int (*fn)(const char *path, const unsigned char *sha1))
174{
175 unsigned char sha1[20];
ca8db142 176 if (!read_ref(git_path("HEAD"), sha1))
99a0a6e0 177 return fn("HEAD", sha1);
2f34ba32 178 return 0;
723c31fe
LT
179}
180
944d8589 181int for_each_ref(int (*fn)(const char *path, const unsigned char *sha1))
8a65ff76 182{
a62be77f
SE
183 return do_for_each_ref("refs", fn, 0);
184}
185
186int for_each_tag_ref(int (*fn)(const char *path, const unsigned char *sha1))
187{
188 return do_for_each_ref("refs/tags", fn, 10);
189}
190
191int for_each_branch_ref(int (*fn)(const char *path, const unsigned char *sha1))
192{
193 return do_for_each_ref("refs/heads", fn, 11);
194}
195
196int for_each_remote_ref(int (*fn)(const char *path, const unsigned char *sha1))
197{
198 return do_for_each_ref("refs/remotes", fn, 13);
8a65ff76
LT
199}
200
95fc7512
DB
201int get_ref_sha1(const char *ref, unsigned char *sha1)
202{
95fc7512
DB
203 if (check_ref_format(ref))
204 return -1;
70e1a880 205 return read_ref(git_path("refs/%s", ref), sha1);
95fc7512
DB
206}
207
03feddd6
JH
208/*
209 * Make sure "ref" is something reasonable to have under ".git/refs/";
210 * We do not like it if:
211 *
212 * - any path component of it begins with ".", or
213 * - it has double dots "..", or
214 * - it has ASCII control character, "~", "^", ":" or SP, anywhere, or
215 * - it ends with a "/".
216 */
217
218static inline int bad_ref_char(int ch)
219{
220 return (((unsigned) ch) <= ' ' ||
68283999
JH
221 ch == '~' || ch == '^' || ch == ':' ||
222 /* 2.13 Pattern Matching Notation */
223 ch == '?' || ch == '*' || ch == '[');
03feddd6
JH
224}
225
95fc7512
DB
226int check_ref_format(const char *ref)
227{
03feddd6
JH
228 int ch, level;
229 const char *cp = ref;
230
231 level = 0;
232 while (1) {
233 while ((ch = *cp++) == '/')
234 ; /* tolerate duplicated slashes */
235 if (!ch)
236 return -1; /* should not end with slashes */
237
238 /* we are at the beginning of the path component */
239 if (ch == '.' || bad_ref_char(ch))
240 return -1;
241
242 /* scan the rest of the path component */
243 while ((ch = *cp++) != 0) {
244 if (bad_ref_char(ch))
245 return -1;
246 if (ch == '/')
247 break;
248 if (ch == '.' && *cp == '.')
249 return -1;
250 }
251 level++;
252 if (!ch) {
253 if (level < 2)
254 return -1; /* at least of form "heads/blah" */
255 return 0;
256 }
257 }
95fc7512
DB
258}
259
4bd18c43
SP
260static struct ref_lock* verify_lock(struct ref_lock *lock,
261 const unsigned char *old_sha1, int mustexist)
262{
263 char buf[40];
264 int nr, fd = open(lock->ref_file, O_RDONLY);
265 if (fd < 0 && (mustexist || errno != ENOENT)) {
266 error("Can't verify ref %s", lock->ref_file);
267 unlock_ref(lock);
268 return NULL;
269 }
270 nr = read(fd, buf, 40);
271 close(fd);
272 if (nr != 40 || get_sha1_hex(buf, lock->old_sha1) < 0) {
273 error("Can't verify ref %s", lock->ref_file);
274 unlock_ref(lock);
275 return NULL;
276 }
277 if (memcmp(lock->old_sha1, old_sha1, 20)) {
278 error("Ref %s is at %s but expected %s", lock->ref_file,
279 sha1_to_hex(lock->old_sha1), sha1_to_hex(old_sha1));
280 unlock_ref(lock);
281 return NULL;
282 }
283 return lock;
284}
285
286static struct ref_lock* lock_ref_sha1_basic(const char *path,
287 int plen,
288 const unsigned char *old_sha1, int mustexist)
289{
290 struct ref_lock *lock;
291
292 lock = xcalloc(1, sizeof(struct ref_lock));
293 lock->lock_fd = -1;
294
295 plen = strlen(path) - plen;
296 path = resolve_ref(path, lock->old_sha1, mustexist);
297 if (!path) {
298 error("Can't read ref %s", path);
299 unlock_ref(lock);
300 return NULL;
301 }
302
303 lock->ref_file = strdup(path);
304 lock->lock_file = strdup(mkpath("%s.lock", lock->ref_file));
305
306 if (safe_create_leading_directories(lock->lock_file))
307 die("unable to create directory for %s", lock->lock_file);
308 lock->lock_fd = open(lock->lock_file,
309 O_WRONLY | O_CREAT | O_EXCL, 0666);
310 if (lock->lock_fd < 0) {
311 error("Couldn't open lock file %s: %s",
312 lock->lock_file, strerror(errno));
313 unlock_ref(lock);
314 return NULL;
315 }
316
317 return old_sha1 ? verify_lock(lock, old_sha1, mustexist) : lock;
318}
319
320struct ref_lock* lock_ref_sha1(const char *ref,
321 const unsigned char *old_sha1, int mustexist)
95fc7512 322{
95fc7512 323 if (check_ref_format(ref))
4bd18c43
SP
324 return NULL;
325 return lock_ref_sha1_basic(git_path("refs/%s", ref),
326 strlen(ref), old_sha1, mustexist);
327}
328
329struct ref_lock* lock_any_ref_for_update(const char *ref,
330 const unsigned char *old_sha1, int mustexist)
331{
332 return lock_ref_sha1_basic(git_path("%s", ref),
333 strlen(ref), old_sha1, mustexist);
334}
335
336void unlock_ref (struct ref_lock *lock)
337{
338 if (lock->lock_fd >= 0) {
339 close(lock->lock_fd);
340 unlink(lock->lock_file);
341 }
342 if (lock->ref_file)
343 free(lock->ref_file);
344 if (lock->lock_file)
345 free(lock->lock_file);
346 free(lock);
347}
348
349int write_ref_sha1(struct ref_lock *lock,
350 const unsigned char *sha1, const char *logmsg)
351{
352 static char term = '\n';
353
354 if (!lock)
95fc7512 355 return -1;
4bd18c43
SP
356 if (!memcmp(lock->old_sha1, sha1, 20)) {
357 unlock_ref(lock);
358 return 0;
95fc7512 359 }
4bd18c43
SP
360 if (write(lock->lock_fd, sha1_to_hex(sha1), 40) != 40 ||
361 write(lock->lock_fd, &term, 1) != 1
362 || close(lock->lock_fd) < 0) {
363 error("Couldn't write %s", lock->lock_file);
364 unlock_ref(lock);
365 return -1;
366 }
367 if (rename(lock->lock_file, lock->ref_file) < 0) {
368 error("Couldn't set %s", lock->ref_file);
369 unlock_ref(lock);
370 return -1;
371 }
372 lock->lock_fd = -1;
373 unlock_ref(lock);
374 return 0;
95fc7512 375}