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         if (adjust_shared_perm(git_HEAD)) {
108                 unlink(lockpath);
109                 error("Unable to fix permissions on %s", lockpath);
110                 return -4;
111         }
112         return 0;
113 }
114
115 int read_ref(const char *filename, unsigned char *sha1)
116 {
117         if (resolve_ref(filename, sha1, 1))
118                 return 0;
119         return -1;
120 }
121
122 static int do_for_each_ref(const char *base, int (*fn)(const char *path, const unsigned char *sha1), int trim)
123 {
124         int retval = 0;
125         DIR *dir = opendir(git_path("%s", base));
126
127         if (dir) {
128                 struct dirent *de;
129                 int baselen = strlen(base);
130                 char *path = xmalloc(baselen + 257);
131
132                 if (!strncmp(base, "./", 2)) {
133                         base += 2;
134                         baselen -= 2;
135                 }
136                 memcpy(path, base, baselen);
137                 if (baselen && base[baselen-1] != '/')
138                         path[baselen++] = '/';
139
140                 while ((de = readdir(dir)) != NULL) {
141                         unsigned char sha1[20];
142                         struct stat st;
143                         int namelen;
144
145                         if (de->d_name[0] == '.')
146                                 continue;
147                         namelen = strlen(de->d_name);
148                         if (namelen > 255)
149                                 continue;
150                         if (has_extension(de->d_name, ".lock"))
151                                 continue;
152                         memcpy(path + baselen, de->d_name, namelen+1);
153                         if (stat(git_path("%s", path), &st) < 0)
154                                 continue;
155                         if (S_ISDIR(st.st_mode)) {
156                                 retval = do_for_each_ref(path, fn, trim);
157                                 if (retval)
158                                         break;
159                                 continue;
160                         }
161                         if (read_ref(git_path("%s", path), sha1) < 0) {
162                                 error("%s points nowhere!", path);
163                                 continue;
164                         }
165                         if (!has_sha1_file(sha1)) {
166                                 error("%s does not point to a valid "
167                                       "commit object!", path);
168                                 continue;
169                         }
170                         retval = fn(path + trim, sha1);
171                         if (retval)
172                                 break;
173                 }
174                 free(path);
175                 closedir(dir);
176         }
177         return retval;
178 }
179
180 int head_ref(int (*fn)(const char *path, const unsigned char *sha1))
181 {
182         unsigned char sha1[20];
183         if (!read_ref(git_path("HEAD"), sha1))
184                 return fn("HEAD", sha1);
185         return 0;
186 }
187
188 int for_each_ref(int (*fn)(const char *path, const unsigned char *sha1))
189 {
190         return do_for_each_ref("refs", fn, 0);
191 }
192
193 int for_each_tag_ref(int (*fn)(const char *path, const unsigned char *sha1))
194 {
195         return do_for_each_ref("refs/tags", fn, 10);
196 }
197
198 int for_each_branch_ref(int (*fn)(const char *path, const unsigned char *sha1))
199 {
200         return do_for_each_ref("refs/heads", fn, 11);
201 }
202
203 int for_each_remote_ref(int (*fn)(const char *path, const unsigned char *sha1))
204 {
205         return do_for_each_ref("refs/remotes", fn, 13);
206 }
207
208 int get_ref_sha1(const char *ref, unsigned char *sha1)
209 {
210         if (check_ref_format(ref))
211                 return -1;
212         return read_ref(git_path("refs/%s", ref), sha1);
213 }
214
215 /*
216  * Make sure "ref" is something reasonable to have under ".git/refs/";
217  * We do not like it if:
218  *
219  * - any path component of it begins with ".", or
220  * - it has double dots "..", or
221  * - it has ASCII control character, "~", "^", ":" or SP, anywhere, or
222  * - it ends with a "/".
223  */
224
225 static inline int bad_ref_char(int ch)
226 {
227         return (((unsigned) ch) <= ' ' ||
228                 ch == '~' || ch == '^' || ch == ':' ||
229                 /* 2.13 Pattern Matching Notation */
230                 ch == '?' || ch == '*' || ch == '[');
231 }
232
233 int check_ref_format(const char *ref)
234 {
235         int ch, level;
236         const char *cp = ref;
237
238         level = 0;
239         while (1) {
240                 while ((ch = *cp++) == '/')
241                         ; /* tolerate duplicated slashes */
242                 if (!ch)
243                         return -1; /* should not end with slashes */
244
245                 /* we are at the beginning of the path component */
246                 if (ch == '.' || bad_ref_char(ch))
247                         return -1;
248
249                 /* scan the rest of the path component */
250                 while ((ch = *cp++) != 0) {
251                         if (bad_ref_char(ch))
252                                 return -1;
253                         if (ch == '/')
254                                 break;
255                         if (ch == '.' && *cp == '.')
256                                 return -1;
257                 }
258                 level++;
259                 if (!ch) {
260                         if (level < 2)
261                                 return -1; /* at least of form "heads/blah" */
262                         return 0;
263                 }
264         }
265 }
266
267 static struct ref_lock *verify_lock(struct ref_lock *lock,
268         const unsigned char *old_sha1, int mustexist)
269 {
270         char buf[40];
271         int nr, fd = open(lock->ref_file, O_RDONLY);
272         if (fd < 0 && (mustexist || errno != ENOENT)) {
273                 error("Can't verify ref %s", lock->ref_file);
274                 unlock_ref(lock);
275                 return NULL;
276         }
277         nr = read(fd, buf, 40);
278         close(fd);
279         if (nr != 40 || get_sha1_hex(buf, lock->old_sha1) < 0) {
280                 error("Can't verify ref %s", lock->ref_file);
281                 unlock_ref(lock);
282                 return NULL;
283         }
284         if (memcmp(lock->old_sha1, old_sha1, 20)) {
285                 error("Ref %s is at %s but expected %s", lock->ref_file,
286                         sha1_to_hex(lock->old_sha1), sha1_to_hex(old_sha1));
287                 unlock_ref(lock);
288                 return NULL;
289         }
290         return lock;
291 }
292
293 static struct ref_lock *lock_ref_sha1_basic(const char *path,
294         int plen,
295         const unsigned char *old_sha1, int mustexist)
296 {
297         const char *orig_path = path;
298         struct ref_lock *lock;
299         struct stat st;
300
301         lock = xcalloc(1, sizeof(struct ref_lock));
302         lock->lock_fd = -1;
303
304         plen = strlen(path) - plen;
305         path = resolve_ref(path, lock->old_sha1, mustexist);
306         if (!path) {
307                 int last_errno = errno;
308                 error("unable to resolve reference %s: %s",
309                         orig_path, strerror(errno));
310                 unlock_ref(lock);
311                 errno = last_errno;
312                 return NULL;
313         }
314         lock->lk = xcalloc(1, sizeof(struct lock_file));
315
316         lock->ref_file = strdup(path);
317         lock->log_file = strdup(git_path("logs/%s", lock->ref_file + plen));
318         lock->force_write = lstat(lock->ref_file, &st) && errno == ENOENT;
319
320         if (safe_create_leading_directories(lock->ref_file))
321                 die("unable to create directory for %s", lock->ref_file);
322         lock->lock_fd = hold_lock_file_for_update(lock->lk, lock->ref_file, 1);
323
324         return old_sha1 ? verify_lock(lock, old_sha1, mustexist) : lock;
325 }
326
327 struct ref_lock *lock_ref_sha1(const char *ref,
328         const unsigned char *old_sha1, int mustexist)
329 {
330         if (check_ref_format(ref))
331                 return NULL;
332         return lock_ref_sha1_basic(git_path("refs/%s", ref),
333                 5 + strlen(ref), old_sha1, mustexist);
334 }
335
336 struct ref_lock *lock_any_ref_for_update(const char *ref,
337         const unsigned char *old_sha1, int mustexist)
338 {
339         return lock_ref_sha1_basic(git_path("%s", ref),
340                 strlen(ref), old_sha1, mustexist);
341 }
342
343 void unlock_ref(struct ref_lock *lock)
344 {
345         if (lock->lock_fd >= 0) {
346                 close(lock->lock_fd);
347                 /* Do not free lock->lk -- atexit() still looks at them */
348                 if (lock->lk)
349                         rollback_lock_file(lock->lk);
350         }
351         if (lock->ref_file)
352                 free(lock->ref_file);
353         if (lock->log_file)
354                 free(lock->log_file);
355         free(lock);
356 }
357
358 static int log_ref_write(struct ref_lock *lock,
359         const unsigned char *sha1, const char *msg)
360 {
361         int logfd, written, oflags = O_APPEND | O_WRONLY;
362         unsigned maxlen, len;
363         char *logrec;
364         const char *committer;
365
366         if (log_all_ref_updates) {
367                 if (safe_create_leading_directories(lock->log_file) < 0)
368                         return error("unable to create directory for %s",
369                                 lock->log_file);
370                 oflags |= O_CREAT;
371         }
372
373         logfd = open(lock->log_file, oflags, 0666);
374         if (logfd < 0) {
375                 if (!log_all_ref_updates && errno == ENOENT)
376                         return 0;
377                 return error("Unable to append to %s: %s",
378                         lock->log_file, strerror(errno));
379         }
380
381         committer = git_committer_info(1);
382         if (msg) {
383                 maxlen = strlen(committer) + strlen(msg) + 2*40 + 5;
384                 logrec = xmalloc(maxlen);
385                 len = snprintf(logrec, maxlen, "%s %s %s\t%s\n",
386                         sha1_to_hex(lock->old_sha1),
387                         sha1_to_hex(sha1),
388                         committer,
389                         msg);
390         }
391         else {
392                 maxlen = strlen(committer) + 2*40 + 4;
393                 logrec = xmalloc(maxlen);
394                 len = snprintf(logrec, maxlen, "%s %s %s\n",
395                         sha1_to_hex(lock->old_sha1),
396                         sha1_to_hex(sha1),
397                         committer);
398         }
399         written = len <= maxlen ? write(logfd, logrec, len) : -1;
400         free(logrec);
401         close(logfd);
402         if (written != len)
403                 return error("Unable to append to %s", lock->log_file);
404         return 0;
405 }
406
407 int write_ref_sha1(struct ref_lock *lock,
408         const unsigned char *sha1, const char *logmsg)
409 {
410         static char term = '\n';
411
412         if (!lock)
413                 return -1;
414         if (!lock->force_write && !memcmp(lock->old_sha1, sha1, 20)) {
415                 unlock_ref(lock);
416                 return 0;
417         }
418         if (write(lock->lock_fd, sha1_to_hex(sha1), 40) != 40 ||
419             write(lock->lock_fd, &term, 1) != 1
420                 || close(lock->lock_fd) < 0) {
421                 error("Couldn't write %s", lock->lk->filename);
422                 unlock_ref(lock);
423                 return -1;
424         }
425         if (log_ref_write(lock, sha1, logmsg) < 0) {
426                 unlock_ref(lock);
427                 return -1;
428         }
429         if (commit_lock_file(lock->lk)) {
430                 error("Couldn't set %s", lock->ref_file);
431                 unlock_ref(lock);
432                 return -1;
433         }
434         lock->lock_fd = -1;
435         unlock_ref(lock);
436         return 0;
437 }
438
439 int read_ref_at(const char *ref, unsigned long at_time, unsigned char *sha1)
440 {
441         const char *logfile, *logdata, *logend, *rec, *lastgt, *lastrec;
442         char *tz_c;
443         int logfd, tz;
444         struct stat st;
445         unsigned long date;
446         unsigned char logged_sha1[20];
447
448         logfile = git_path("logs/%s", ref);
449         logfd = open(logfile, O_RDONLY, 0);
450         if (logfd < 0)
451                 die("Unable to read log %s: %s", logfile, strerror(errno));
452         fstat(logfd, &st);
453         if (!st.st_size)
454                 die("Log %s is empty.", logfile);
455         logdata = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, logfd, 0);
456         close(logfd);
457
458         lastrec = NULL;
459         rec = logend = logdata + st.st_size;
460         while (logdata < rec) {
461                 if (logdata < rec && *(rec-1) == '\n')
462                         rec--;
463                 lastgt = NULL;
464                 while (logdata < rec && *(rec-1) != '\n') {
465                         rec--;
466                         if (*rec == '>')
467                                 lastgt = rec;
468                 }
469                 if (!lastgt)
470                         die("Log %s is corrupt.", logfile);
471                 date = strtoul(lastgt + 1, &tz_c, 10);
472                 if (date <= at_time) {
473                         if (lastrec) {
474                                 if (get_sha1_hex(lastrec, logged_sha1))
475                                         die("Log %s is corrupt.", logfile);
476                                 if (get_sha1_hex(rec + 41, sha1))
477                                         die("Log %s is corrupt.", logfile);
478                                 if (memcmp(logged_sha1, sha1, 20)) {
479                                         tz = strtoul(tz_c, NULL, 10);
480                                         fprintf(stderr,
481                                                 "warning: Log %s has gap after %s.\n",
482                                                 logfile, show_rfc2822_date(date, tz));
483                                 }
484                         }
485                         else if (date == at_time) {
486                                 if (get_sha1_hex(rec + 41, sha1))
487                                         die("Log %s is corrupt.", logfile);
488                         }
489                         else {
490                                 if (get_sha1_hex(rec + 41, logged_sha1))
491                                         die("Log %s is corrupt.", logfile);
492                                 if (memcmp(logged_sha1, sha1, 20)) {
493                                         tz = strtoul(tz_c, NULL, 10);
494                                         fprintf(stderr,
495                                                 "warning: Log %s unexpectedly ended on %s.\n",
496                                                 logfile, show_rfc2822_date(date, tz));
497                                 }
498                         }
499                         munmap((void*)logdata, st.st_size);
500                         return 0;
501                 }
502                 lastrec = rec;
503         }
504
505         rec = logdata;
506         while (rec < logend && *rec != '>' && *rec != '\n')
507                 rec++;
508         if (rec == logend || *rec == '\n')
509                 die("Log %s is corrupt.", logfile);
510         date = strtoul(rec + 1, &tz_c, 10);
511         tz = strtoul(tz_c, NULL, 10);
512         if (get_sha1_hex(logdata, sha1))
513                 die("Log %s is corrupt.", logfile);
514         munmap((void*)logdata, st.st_size);
515         fprintf(stderr, "warning: Log %s only goes back to %s.\n",
516                 logfile, show_rfc2822_date(date, tz));
517         return 0;
518 }