Merge git://git.kernel.org/pub/scm/gitk/gitk
[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                         if (namelen>5 && !strcmp(de->d_name+namelen-5,".lock"))
146                                 continue;
147                         memcpy(path + baselen, de->d_name, namelen+1);
148                         if (stat(git_path("%s", path), &st) < 0)
149                                 continue;
150                         if (S_ISDIR(st.st_mode)) {
151                                 retval = do_for_each_ref(path, fn, trim);
152                                 if (retval)
153                                         break;
154                                 continue;
155                         }
156                         if (read_ref(git_path("%s", path), sha1) < 0) {
157                                 error("%s points nowhere!", path);
158                                 continue;
159                         }
160                         if (!has_sha1_file(sha1)) {
161                                 error("%s does not point to a valid "
162                                       "commit object!", path);
163                                 continue;
164                         }
165                         retval = fn(path + trim, sha1);
166                         if (retval)
167                                 break;
168                 }
169                 free(path);
170                 closedir(dir);
171         }
172         return retval;
173 }
174
175 int head_ref(int (*fn)(const char *path, const unsigned char *sha1))
176 {
177         unsigned char sha1[20];
178         if (!read_ref(git_path("HEAD"), sha1))
179                 return fn("HEAD", sha1);
180         return 0;
181 }
182
183 int for_each_ref(int (*fn)(const char *path, const unsigned char *sha1))
184 {
185         return do_for_each_ref("refs", fn, 0);
186 }
187
188 int for_each_tag_ref(int (*fn)(const char *path, const unsigned char *sha1))
189 {
190         return do_for_each_ref("refs/tags", fn, 10);
191 }
192
193 int for_each_branch_ref(int (*fn)(const char *path, const unsigned char *sha1))
194 {
195         return do_for_each_ref("refs/heads", fn, 11);
196 }
197
198 int for_each_remote_ref(int (*fn)(const char *path, const unsigned char *sha1))
199 {
200         return do_for_each_ref("refs/remotes", fn, 13);
201 }
202
203 int get_ref_sha1(const char *ref, unsigned char *sha1)
204 {
205         if (check_ref_format(ref))
206                 return -1;
207         return read_ref(git_path("refs/%s", ref), sha1);
208 }
209
210 /*
211  * Make sure "ref" is something reasonable to have under ".git/refs/";
212  * We do not like it if:
213  *
214  * - any path component of it begins with ".", or
215  * - it has double dots "..", or
216  * - it has ASCII control character, "~", "^", ":" or SP, anywhere, or
217  * - it ends with a "/".
218  */
219
220 static inline int bad_ref_char(int ch)
221 {
222         return (((unsigned) ch) <= ' ' ||
223                 ch == '~' || ch == '^' || ch == ':' ||
224                 /* 2.13 Pattern Matching Notation */
225                 ch == '?' || ch == '*' || ch == '[');
226 }
227
228 int check_ref_format(const char *ref)
229 {
230         int ch, level;
231         const char *cp = ref;
232
233         level = 0;
234         while (1) {
235                 while ((ch = *cp++) == '/')
236                         ; /* tolerate duplicated slashes */
237                 if (!ch)
238                         return -1; /* should not end with slashes */
239
240                 /* we are at the beginning of the path component */
241                 if (ch == '.' || bad_ref_char(ch))
242                         return -1;
243
244                 /* scan the rest of the path component */
245                 while ((ch = *cp++) != 0) {
246                         if (bad_ref_char(ch))
247                                 return -1;
248                         if (ch == '/')
249                                 break;
250                         if (ch == '.' && *cp == '.')
251                                 return -1;
252                 }
253                 level++;
254                 if (!ch) {
255                         if (level < 2)
256                                 return -1; /* at least of form "heads/blah" */
257                         return 0;
258                 }
259         }
260 }
261
262 static struct ref_lock *verify_lock(struct ref_lock *lock,
263         const unsigned char *old_sha1, int mustexist)
264 {
265         char buf[40];
266         int nr, fd = open(lock->ref_file, O_RDONLY);
267         if (fd < 0 && (mustexist || errno != ENOENT)) {
268                 error("Can't verify ref %s", lock->ref_file);
269                 unlock_ref(lock);
270                 return NULL;
271         }
272         nr = read(fd, buf, 40);
273         close(fd);
274         if (nr != 40 || get_sha1_hex(buf, lock->old_sha1) < 0) {
275                 error("Can't verify ref %s", lock->ref_file);
276                 unlock_ref(lock);
277                 return NULL;
278         }
279         if (memcmp(lock->old_sha1, old_sha1, 20)) {
280                 error("Ref %s is at %s but expected %s", lock->ref_file,
281                         sha1_to_hex(lock->old_sha1), sha1_to_hex(old_sha1));
282                 unlock_ref(lock);
283                 return NULL;
284         }
285         return lock;
286 }
287
288 static struct ref_lock *lock_ref_sha1_basic(const char *path,
289         int plen,
290         const unsigned char *old_sha1, int mustexist)
291 {
292         struct ref_lock *lock;
293         struct stat st;
294
295         lock = xcalloc(1, sizeof(struct ref_lock));
296         lock->lock_fd = -1;
297
298         plen = strlen(path) - plen;
299         path = resolve_ref(path, lock->old_sha1, mustexist);
300         if (!path) {
301                 unlock_ref(lock);
302                 return NULL;
303         }
304         lock->lk = xcalloc(1, sizeof(struct lock_file));
305
306         lock->ref_file = strdup(path);
307         lock->log_file = strdup(git_path("logs/%s", lock->ref_file + plen));
308         lock->force_write = lstat(lock->ref_file, &st) && errno == ENOENT;
309
310         if (safe_create_leading_directories(lock->ref_file))
311                 die("unable to create directory for %s", lock->ref_file);
312         lock->lock_fd = hold_lock_file_for_update(lock->lk, lock->ref_file);
313         if (lock->lock_fd < 0) {
314                 error("Couldn't open lock file %s: %s",
315                       lock->lk->filename, strerror(errno));
316                 unlock_ref(lock);
317                 return NULL;
318         }
319
320         return old_sha1 ? verify_lock(lock, old_sha1, mustexist) : lock;
321 }
322
323 struct ref_lock *lock_ref_sha1(const char *ref,
324         const unsigned char *old_sha1, int mustexist)
325 {
326         if (check_ref_format(ref))
327                 return NULL;
328         return lock_ref_sha1_basic(git_path("refs/%s", ref),
329                 5 + strlen(ref), old_sha1, mustexist);
330 }
331
332 struct ref_lock *lock_any_ref_for_update(const char *ref,
333         const unsigned char *old_sha1, int mustexist)
334 {
335         return lock_ref_sha1_basic(git_path("%s", ref),
336                 strlen(ref), old_sha1, mustexist);
337 }
338
339 void unlock_ref(struct ref_lock *lock)
340 {
341         if (lock->lock_fd >= 0) {
342                 close(lock->lock_fd);
343                 /* Do not free lock->lk -- atexit() still looks at them */
344                 if (lock->lk)
345                         rollback_lock_file(lock->lk);
346         }
347         if (lock->ref_file)
348                 free(lock->ref_file);
349         if (lock->log_file)
350                 free(lock->log_file);
351         free(lock);
352 }
353
354 static int log_ref_write(struct ref_lock *lock,
355         const unsigned char *sha1, const char *msg)
356 {
357         int logfd, written, oflags = O_APPEND | O_WRONLY;
358         unsigned maxlen, len;
359         char *logrec;
360         const char *comitter;
361
362         if (log_all_ref_updates) {
363                 if (safe_create_leading_directories(lock->log_file) < 0)
364                         return error("unable to create directory for %s",
365                                 lock->log_file);
366                 oflags |= O_CREAT;
367         }
368
369         logfd = open(lock->log_file, oflags, 0666);
370         if (logfd < 0) {
371                 if (!log_all_ref_updates && errno == ENOENT)
372                         return 0;
373                 return error("Unable to append to %s: %s",
374                         lock->log_file, strerror(errno));
375         }
376
377         setup_ident();
378         comitter = git_committer_info(1);
379         if (msg) {
380                 maxlen = strlen(comitter) + strlen(msg) + 2*40 + 5;
381                 logrec = xmalloc(maxlen);
382                 len = snprintf(logrec, maxlen, "%s %s %s\t%s\n",
383                         sha1_to_hex(lock->old_sha1),
384                         sha1_to_hex(sha1),
385                         comitter,
386                         msg);
387         }
388         else {
389                 maxlen = strlen(comitter) + 2*40 + 4;
390                 logrec = xmalloc(maxlen);
391                 len = snprintf(logrec, maxlen, "%s %s %s\n",
392                         sha1_to_hex(lock->old_sha1),
393                         sha1_to_hex(sha1),
394                         comitter);
395         }
396         written = len <= maxlen ? write(logfd, logrec, len) : -1;
397         free(logrec);
398         close(logfd);
399         if (written != len)
400                 return error("Unable to append to %s", lock->log_file);
401         return 0;
402 }
403
404 int write_ref_sha1(struct ref_lock *lock,
405         const unsigned char *sha1, const char *logmsg)
406 {
407         static char term = '\n';
408
409         if (!lock)
410                 return -1;
411         if (!lock->force_write && !memcmp(lock->old_sha1, sha1, 20)) {
412                 unlock_ref(lock);
413                 return 0;
414         }
415         if (write(lock->lock_fd, sha1_to_hex(sha1), 40) != 40 ||
416             write(lock->lock_fd, &term, 1) != 1
417                 || close(lock->lock_fd) < 0) {
418                 error("Couldn't write %s", lock->lk->filename);
419                 unlock_ref(lock);
420                 return -1;
421         }
422         if (log_ref_write(lock, sha1, logmsg) < 0) {
423                 unlock_ref(lock);
424                 return -1;
425         }
426         if (commit_lock_file(lock->lk)) {
427                 error("Couldn't set %s", lock->ref_file);
428                 unlock_ref(lock);
429                 return -1;
430         }
431         lock->lock_fd = -1;
432         unlock_ref(lock);
433         return 0;
434 }
435
436 int read_ref_at(const char *ref, unsigned long at_time, unsigned char *sha1)
437 {
438         const char *logfile, *logdata, *logend, *rec, *lastgt, *lastrec;
439         char *tz_c;
440         int logfd, tz;
441         struct stat st;
442         unsigned long date;
443         unsigned char logged_sha1[20];
444
445         logfile = git_path("logs/%s", ref);
446         logfd = open(logfile, O_RDONLY, 0);
447         if (logfd < 0)
448                 die("Unable to read log %s: %s", logfile, strerror(errno));
449         fstat(logfd, &st);
450         if (!st.st_size)
451                 die("Log %s is empty.", logfile);
452         logdata = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, logfd, 0);
453         close(logfd);
454
455         lastrec = NULL;
456         rec = logend = logdata + st.st_size;
457         while (logdata < rec) {
458                 if (logdata < rec && *(rec-1) == '\n')
459                         rec--;
460                 lastgt = NULL;
461                 while (logdata < rec && *(rec-1) != '\n') {
462                         rec--;
463                         if (*rec == '>')
464                                 lastgt = rec;
465                 }
466                 if (!lastgt)
467                         die("Log %s is corrupt.", logfile);
468                 date = strtoul(lastgt + 1, &tz_c, 10);
469                 if (date <= at_time) {
470                         if (lastrec) {
471                                 if (get_sha1_hex(lastrec, logged_sha1))
472                                         die("Log %s is corrupt.", logfile);
473                                 if (get_sha1_hex(rec + 41, sha1))
474                                         die("Log %s is corrupt.", logfile);
475                                 if (memcmp(logged_sha1, sha1, 20)) {
476                                         tz = strtoul(tz_c, NULL, 10);
477                                         fprintf(stderr,
478                                                 "warning: Log %s has gap after %s.\n",
479                                                 logfile, show_rfc2822_date(date, tz));
480                                 }
481                         }
482                         else if (date == at_time) {
483                                 if (get_sha1_hex(rec + 41, sha1))
484                                         die("Log %s is corrupt.", logfile);
485                         }
486                         else {
487                                 if (get_sha1_hex(rec + 41, logged_sha1))
488                                         die("Log %s is corrupt.", logfile);
489                                 if (memcmp(logged_sha1, sha1, 20)) {
490                                         tz = strtoul(tz_c, NULL, 10);
491                                         fprintf(stderr,
492                                                 "warning: Log %s unexpectedly ended on %s.\n",
493                                                 logfile, show_rfc2822_date(date, tz));
494                                 }
495                         }
496                         munmap((void*)logdata, st.st_size);
497                         return 0;
498                 }
499                 lastrec = rec;
500         }
501
502         rec = logdata;
503         while (rec < logend && *rec != '>' && *rec != '\n')
504                 rec++;
505         if (rec == logend || *rec == '\n')
506                 die("Log %s is corrupt.", logfile);
507         date = strtoul(rec + 1, &tz_c, 10);
508         tz = strtoul(tz_c, NULL, 10);
509         if (get_sha1_hex(logdata, sha1))
510                 die("Log %s is corrupt.", logfile);
511         munmap((void*)logdata, st.st_size);
512         fprintf(stderr, "warning: Log %s only goes back to %s.\n",
513                 logfile, show_rfc2822_date(date, tz));
514         return 0;
515 }