6c91ae6468f859897a358ebd97f4143e44cda874
[git/git.git] / refs.c
1 #include "refs.h"
2 #include "cache.h"
3
4 #include <errno.h>
5
6 /* We allow "recursive" symbolic refs. Only within reason, though */
7 #define MAXDEPTH 5
8
9 const char *resolve_ref(const char *path, unsigned char *sha1, int reading)
10 {
11 int depth = MAXDEPTH, len;
12 char buffer[256];
13
14 for (;;) {
15 struct stat st;
16 char *buf;
17 int fd;
18
19 if (--depth < 0)
20 return NULL;
21
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 }
35
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 }
43 }
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);
67 }
68 if (len < 40 || get_sha1_hex(buffer, sha1))
69 return NULL;
70 return path;
71 }
72
73 int create_symref(const char *git_HEAD, const char *refs_heads_master)
74 {
75 const char *lockpath;
76 char ref[1000];
77 int fd, len, written;
78
79 #ifndef NO_SYMLINK_HEAD
80 if (prefer_symlink_refs) {
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 }
86 #endif
87
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;
108 }
109
110 int read_ref(const char *filename, unsigned char *sha1)
111 {
112 if (resolve_ref(filename, sha1, 1))
113 return 0;
114 return -1;
115 }
116
117 static int do_for_each_ref(const char *base, int (*fn)(const char *path, const unsigned char *sha1), int trim)
118 {
119 int retval = 0;
120 DIR *dir = opendir(git_path("%s", base));
121
122 if (dir) {
123 struct dirent *de;
124 int baselen = strlen(base);
125 char *path = xmalloc(baselen + 257);
126
127 if (!strncmp(base, "./", 2)) {
128 base += 2;
129 baselen -= 2;
130 }
131 memcpy(path, base, baselen);
132 if (baselen && base[baselen-1] != '/')
133 path[baselen++] = '/';
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);
146 if (stat(git_path("%s", path), &st) < 0)
147 continue;
148 if (S_ISDIR(st.st_mode)) {
149 retval = do_for_each_ref(path, fn, trim);
150 if (retval)
151 break;
152 continue;
153 }
154 if (read_ref(git_path("%s", path), sha1) < 0) {
155 error("%s points nowhere!", path);
156 continue;
157 }
158 if (!has_sha1_file(sha1)) {
159 error("%s does not point to a valid "
160 "commit object!", path);
161 continue;
162 }
163 retval = fn(path + trim, sha1);
164 if (retval)
165 break;
166 }
167 free(path);
168 closedir(dir);
169 }
170 return retval;
171 }
172
173 int head_ref(int (*fn)(const char *path, const unsigned char *sha1))
174 {
175 unsigned char sha1[20];
176 if (!read_ref(git_path("HEAD"), sha1))
177 return fn("HEAD", sha1);
178 return 0;
179 }
180
181 int for_each_ref(int (*fn)(const char *path, const unsigned char *sha1))
182 {
183 return do_for_each_ref("refs", fn, 0);
184 }
185
186 int 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
191 int 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
196 int for_each_remote_ref(int (*fn)(const char *path, const unsigned char *sha1))
197 {
198 return do_for_each_ref("refs/remotes", fn, 13);
199 }
200
201 static char *ref_file_name(const char *ref)
202 {
203 char *base = get_refs_directory();
204 int baselen = strlen(base);
205 int reflen = strlen(ref);
206 char *ret = xmalloc(baselen + 2 + reflen);
207 sprintf(ret, "%s/%s", base, ref);
208 return ret;
209 }
210
211 static char *ref_lock_file_name(const char *ref)
212 {
213 char *base = get_refs_directory();
214 int baselen = strlen(base);
215 int reflen = strlen(ref);
216 char *ret = xmalloc(baselen + 7 + reflen);
217 sprintf(ret, "%s/%s.lock", base, ref);
218 return ret;
219 }
220
221 int get_ref_sha1(const char *ref, unsigned char *sha1)
222 {
223 const char *filename;
224
225 if (check_ref_format(ref))
226 return -1;
227 filename = git_path("refs/%s", ref);
228 return read_ref(filename, sha1);
229 }
230
231 static int lock_ref_file(const char *filename, const char *lock_filename,
232 const unsigned char *old_sha1)
233 {
234 int fd = open(lock_filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
235 unsigned char current_sha1[20];
236 int retval;
237 if (fd < 0) {
238 return error("Couldn't open lock file for %s: %s",
239 filename, strerror(errno));
240 }
241 retval = read_ref(filename, current_sha1);
242 if (old_sha1) {
243 if (retval) {
244 close(fd);
245 unlink(lock_filename);
246 return error("Could not read the current value of %s",
247 filename);
248 }
249 if (memcmp(current_sha1, old_sha1, 20)) {
250 close(fd);
251 unlink(lock_filename);
252 error("The current value of %s is %s",
253 filename, sha1_to_hex(current_sha1));
254 return error("Expected %s",
255 sha1_to_hex(old_sha1));
256 }
257 } else {
258 if (!retval) {
259 close(fd);
260 unlink(lock_filename);
261 return error("Unexpectedly found a value of %s for %s",
262 sha1_to_hex(current_sha1), filename);
263 }
264 }
265 return fd;
266 }
267
268 int lock_ref_sha1(const char *ref, const unsigned char *old_sha1)
269 {
270 char *filename;
271 char *lock_filename;
272 int retval;
273 if (check_ref_format(ref))
274 return -1;
275 filename = ref_file_name(ref);
276 lock_filename = ref_lock_file_name(ref);
277 retval = lock_ref_file(filename, lock_filename, old_sha1);
278 free(filename);
279 free(lock_filename);
280 return retval;
281 }
282
283 static int write_ref_file(const char *filename,
284 const char *lock_filename, int fd,
285 const unsigned char *sha1)
286 {
287 char *hex = sha1_to_hex(sha1);
288 char term = '\n';
289 if (write(fd, hex, 40) < 40 ||
290 write(fd, &term, 1) < 1) {
291 error("Couldn't write %s", filename);
292 close(fd);
293 return -1;
294 }
295 close(fd);
296 rename(lock_filename, filename);
297 return 0;
298 }
299
300 int write_ref_sha1(const char *ref, int fd, const unsigned char *sha1)
301 {
302 char *filename;
303 char *lock_filename;
304 int retval;
305 if (fd < 0)
306 return -1;
307 if (check_ref_format(ref))
308 return -1;
309 filename = ref_file_name(ref);
310 lock_filename = ref_lock_file_name(ref);
311 if (safe_create_leading_directories(filename))
312 die("unable to create leading directory for %s", filename);
313 retval = write_ref_file(filename, lock_filename, fd, sha1);
314 free(filename);
315 free(lock_filename);
316 return retval;
317 }
318
319 /*
320 * Make sure "ref" is something reasonable to have under ".git/refs/";
321 * We do not like it if:
322 *
323 * - any path component of it begins with ".", or
324 * - it has double dots "..", or
325 * - it has ASCII control character, "~", "^", ":" or SP, anywhere, or
326 * - it ends with a "/".
327 */
328
329 static inline int bad_ref_char(int ch)
330 {
331 return (((unsigned) ch) <= ' ' ||
332 ch == '~' || ch == '^' || ch == ':' ||
333 /* 2.13 Pattern Matching Notation */
334 ch == '?' || ch == '*' || ch == '[');
335 }
336
337 int check_ref_format(const char *ref)
338 {
339 int ch, level;
340 const char *cp = ref;
341
342 level = 0;
343 while (1) {
344 while ((ch = *cp++) == '/')
345 ; /* tolerate duplicated slashes */
346 if (!ch)
347 return -1; /* should not end with slashes */
348
349 /* we are at the beginning of the path component */
350 if (ch == '.' || bad_ref_char(ch))
351 return -1;
352
353 /* scan the rest of the path component */
354 while ((ch = *cp++) != 0) {
355 if (bad_ref_char(ch))
356 return -1;
357 if (ch == '/')
358 break;
359 if (ch == '.' && *cp == '.')
360 return -1;
361 }
362 level++;
363 if (!ch) {
364 if (level < 2)
365 return -1; /* at least of form "heads/blah" */
366 return 0;
367 }
368 }
369 }
370
371 int write_ref_sha1_unlocked(const char *ref, const unsigned char *sha1)
372 {
373 char *filename;
374 char *lock_filename;
375 int fd;
376 int retval;
377 if (check_ref_format(ref))
378 return -1;
379 filename = ref_file_name(ref);
380 lock_filename = ref_lock_file_name(ref);
381 if (safe_create_leading_directories(filename))
382 die("unable to create leading directory for %s", filename);
383 fd = open(lock_filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
384 if (fd < 0) {
385 error("Writing %s", lock_filename);
386 perror("Open");
387 }
388 retval = write_ref_file(filename, lock_filename, fd, sha1);
389 free(filename);
390 free(lock_filename);
391 return retval;
392 }