Merge git://git.kernel.org/pub/scm/gitk/gitk
[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 #ifdef USE_SYMLINK_HEAD
80 if (!only_use_symrefs) {
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))
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);
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, 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);
184 }
185
186 static char *ref_file_name(const char *ref)
187 {
188 char *base = get_refs_directory();
189 int baselen = strlen(base);
190 int reflen = strlen(ref);
191 char *ret = xmalloc(baselen + 2 + reflen);
192 sprintf(ret, "%s/%s", base, ref);
193 return ret;
194 }
195
196 static char *ref_lock_file_name(const char *ref)
197 {
198 char *base = get_refs_directory();
199 int baselen = strlen(base);
200 int reflen = strlen(ref);
201 char *ret = xmalloc(baselen + 7 + reflen);
202 sprintf(ret, "%s/%s.lock", base, ref);
203 return ret;
204 }
205
206 int get_ref_sha1(const char *ref, unsigned char *sha1)
207 {
208 const char *filename;
209
210 if (check_ref_format(ref))
211 return -1;
212 filename = git_path("refs/%s", ref);
213 return read_ref(filename, sha1);
214 }
215
216 static int lock_ref_file(const char *filename, const char *lock_filename,
217 const unsigned char *old_sha1)
218 {
219 int fd = open(lock_filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
220 unsigned char current_sha1[20];
221 int retval;
222 if (fd < 0) {
223 return error("Couldn't open lock file for %s: %s",
224 filename, strerror(errno));
225 }
226 retval = read_ref(filename, current_sha1);
227 if (old_sha1) {
228 if (retval) {
229 close(fd);
230 unlink(lock_filename);
231 return error("Could not read the current value of %s",
232 filename);
233 }
234 if (memcmp(current_sha1, old_sha1, 20)) {
235 close(fd);
236 unlink(lock_filename);
237 error("The current value of %s is %s",
238 filename, sha1_to_hex(current_sha1));
239 return error("Expected %s",
240 sha1_to_hex(old_sha1));
241 }
242 } else {
243 if (!retval) {
244 close(fd);
245 unlink(lock_filename);
246 return error("Unexpectedly found a value of %s for %s",
247 sha1_to_hex(current_sha1), filename);
248 }
249 }
250 return fd;
251 }
252
253 int lock_ref_sha1(const char *ref, const unsigned char *old_sha1)
254 {
255 char *filename;
256 char *lock_filename;
257 int retval;
258 if (check_ref_format(ref))
259 return -1;
260 filename = ref_file_name(ref);
261 lock_filename = ref_lock_file_name(ref);
262 retval = lock_ref_file(filename, lock_filename, old_sha1);
263 free(filename);
264 free(lock_filename);
265 return retval;
266 }
267
268 static int write_ref_file(const char *filename,
269 const char *lock_filename, int fd,
270 const unsigned char *sha1)
271 {
272 char *hex = sha1_to_hex(sha1);
273 char term = '\n';
274 if (write(fd, hex, 40) < 40 ||
275 write(fd, &term, 1) < 1) {
276 error("Couldn't write %s", filename);
277 close(fd);
278 return -1;
279 }
280 close(fd);
281 rename(lock_filename, filename);
282 return 0;
283 }
284
285 int write_ref_sha1(const char *ref, int fd, const unsigned char *sha1)
286 {
287 char *filename;
288 char *lock_filename;
289 int retval;
290 if (fd < 0)
291 return -1;
292 if (check_ref_format(ref))
293 return -1;
294 filename = ref_file_name(ref);
295 lock_filename = ref_lock_file_name(ref);
296 if (safe_create_leading_directories(filename))
297 die("unable to create leading directory for %s", filename);
298 retval = write_ref_file(filename, lock_filename, fd, sha1);
299 free(filename);
300 free(lock_filename);
301 return retval;
302 }
303
304 /*
305 * Make sure "ref" is something reasonable to have under ".git/refs/";
306 * We do not like it if:
307 *
308 * - any path component of it begins with ".", or
309 * - it has double dots "..", or
310 * - it has ASCII control character, "~", "^", ":" or SP, anywhere, or
311 * - it ends with a "/".
312 */
313
314 static inline int bad_ref_char(int ch)
315 {
316 return (((unsigned) ch) <= ' ' ||
317 ch == '~' || ch == '^' || ch == ':' ||
318 /* 2.13 Pattern Matching Notation */
319 ch == '?' || ch == '*' || ch == '[');
320 }
321
322 int check_ref_format(const char *ref)
323 {
324 int ch, level;
325 const char *cp = ref;
326
327 level = 0;
328 while (1) {
329 while ((ch = *cp++) == '/')
330 ; /* tolerate duplicated slashes */
331 if (!ch)
332 return -1; /* should not end with slashes */
333
334 /* we are at the beginning of the path component */
335 if (ch == '.' || bad_ref_char(ch))
336 return -1;
337
338 /* scan the rest of the path component */
339 while ((ch = *cp++) != 0) {
340 if (bad_ref_char(ch))
341 return -1;
342 if (ch == '/')
343 break;
344 if (ch == '.' && *cp == '.')
345 return -1;
346 }
347 level++;
348 if (!ch) {
349 if (level < 2)
350 return -1; /* at least of form "heads/blah" */
351 return 0;
352 }
353 }
354 }
355
356 int write_ref_sha1_unlocked(const char *ref, const unsigned char *sha1)
357 {
358 char *filename;
359 char *lock_filename;
360 int fd;
361 int retval;
362 if (check_ref_format(ref))
363 return -1;
364 filename = ref_file_name(ref);
365 lock_filename = ref_lock_file_name(ref);
366 if (safe_create_leading_directories(filename))
367 die("unable to create leading directory for %s", filename);
368 fd = open(lock_filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
369 if (fd < 0) {
370 error("Writing %s", lock_filename);
371 perror("Open");
372 }
373 retval = write_ref_file(filename, lock_filename, fd, sha1);
374 free(filename);
375 free(lock_filename);
376 return retval;
377 }