Merge branch 'master' of git://repo.or.cz/git-gui
[git] / refs.c
1 #include "cache.h"
2 #include "refs.h"
3 #include "object.h"
4 #include "tag.h"
5
6 /* ISSYMREF=01 and ISPACKED=02 are public interfaces */
7 #define REF_KNOWS_PEELED 04
8
9 struct ref_list {
10         struct ref_list *next;
11         unsigned char flag; /* ISSYMREF? ISPACKED? */
12         unsigned char sha1[20];
13         unsigned char peeled[20];
14         char name[FLEX_ARRAY];
15 };
16
17 static const char *parse_ref_line(char *line, unsigned char *sha1)
18 {
19         /*
20          * 42: the answer to everything.
21          *
22          * In this case, it happens to be the answer to
23          *  40 (length of sha1 hex representation)
24          *  +1 (space in between hex and name)
25          *  +1 (newline at the end of the line)
26          */
27         int len = strlen(line) - 42;
28
29         if (len <= 0)
30                 return NULL;
31         if (get_sha1_hex(line, sha1) < 0)
32                 return NULL;
33         if (!isspace(line[40]))
34                 return NULL;
35         line += 41;
36         if (isspace(*line))
37                 return NULL;
38         if (line[len] != '\n')
39                 return NULL;
40         line[len] = 0;
41
42         return line;
43 }
44
45 static struct ref_list *add_ref(const char *name, const unsigned char *sha1,
46                                 int flag, struct ref_list *list,
47                                 struct ref_list **new_entry)
48 {
49         int len;
50         struct ref_list **p = &list, *entry;
51
52         /* Find the place to insert the ref into.. */
53         while ((entry = *p) != NULL) {
54                 int cmp = strcmp(entry->name, name);
55                 if (cmp > 0)
56                         break;
57
58                 /* Same as existing entry? */
59                 if (!cmp) {
60                         if (new_entry)
61                                 *new_entry = entry;
62                         return list;
63                 }
64                 p = &entry->next;
65         }
66
67         /* Allocate it and add it in.. */
68         len = strlen(name) + 1;
69         entry = xmalloc(sizeof(struct ref_list) + len);
70         hashcpy(entry->sha1, sha1);
71         hashclr(entry->peeled);
72         memcpy(entry->name, name, len);
73         entry->flag = flag;
74         entry->next = *p;
75         *p = entry;
76         if (new_entry)
77                 *new_entry = entry;
78         return list;
79 }
80
81 /*
82  * Future: need to be in "struct repository"
83  * when doing a full libification.
84  */
85 struct cached_refs {
86         char did_loose;
87         char did_packed;
88         struct ref_list *loose;
89         struct ref_list *packed;
90 } cached_refs;
91
92 static void free_ref_list(struct ref_list *list)
93 {
94         struct ref_list *next;
95         for ( ; list; list = next) {
96                 next = list->next;
97                 free(list);
98         }
99 }
100
101 static void invalidate_cached_refs(void)
102 {
103         struct cached_refs *ca = &cached_refs;
104
105         if (ca->did_loose && ca->loose)
106                 free_ref_list(ca->loose);
107         if (ca->did_packed && ca->packed)
108                 free_ref_list(ca->packed);
109         ca->loose = ca->packed = NULL;
110         ca->did_loose = ca->did_packed = 0;
111 }
112
113 static void read_packed_refs(FILE *f, struct cached_refs *cached_refs)
114 {
115         struct ref_list *list = NULL;
116         struct ref_list *last = NULL;
117         char refline[PATH_MAX];
118         int flag = REF_ISPACKED;
119
120         while (fgets(refline, sizeof(refline), f)) {
121                 unsigned char sha1[20];
122                 const char *name;
123                 static const char header[] = "# pack-refs with:";
124
125                 if (!strncmp(refline, header, sizeof(header)-1)) {
126                         const char *traits = refline + sizeof(header) - 1;
127                         if (strstr(traits, " peeled "))
128                                 flag |= REF_KNOWS_PEELED;
129                         /* perhaps other traits later as well */
130                         continue;
131                 }
132
133                 name = parse_ref_line(refline, sha1);
134                 if (name) {
135                         list = add_ref(name, sha1, flag, list, &last);
136                         continue;
137                 }
138                 if (last &&
139                     refline[0] == '^' &&
140                     strlen(refline) == 42 &&
141                     refline[41] == '\n' &&
142                     !get_sha1_hex(refline + 1, sha1))
143                         hashcpy(last->peeled, sha1);
144         }
145         cached_refs->packed = list;
146 }
147
148 static struct ref_list *get_packed_refs(void)
149 {
150         if (!cached_refs.did_packed) {
151                 FILE *f = fopen(git_path("packed-refs"), "r");
152                 cached_refs.packed = NULL;
153                 if (f) {
154                         read_packed_refs(f, &cached_refs);
155                         fclose(f);
156                 }
157                 cached_refs.did_packed = 1;
158         }
159         return cached_refs.packed;
160 }
161
162 static struct ref_list *get_ref_dir(const char *base, struct ref_list *list)
163 {
164         DIR *dir = opendir(git_path("%s", base));
165
166         if (dir) {
167                 struct dirent *de;
168                 int baselen = strlen(base);
169                 char *ref = xmalloc(baselen + 257);
170
171                 memcpy(ref, base, baselen);
172                 if (baselen && base[baselen-1] != '/')
173                         ref[baselen++] = '/';
174
175                 while ((de = readdir(dir)) != NULL) {
176                         unsigned char sha1[20];
177                         struct stat st;
178                         int flag;
179                         int namelen;
180
181                         if (de->d_name[0] == '.')
182                                 continue;
183                         namelen = strlen(de->d_name);
184                         if (namelen > 255)
185                                 continue;
186                         if (has_extension(de->d_name, ".lock"))
187                                 continue;
188                         memcpy(ref + baselen, de->d_name, namelen+1);
189                         if (stat(git_path("%s", ref), &st) < 0)
190                                 continue;
191                         if (S_ISDIR(st.st_mode)) {
192                                 list = get_ref_dir(ref, list);
193                                 continue;
194                         }
195                         if (!resolve_ref(ref, sha1, 1, &flag)) {
196                                 error("%s points nowhere!", ref);
197                                 continue;
198                         }
199                         list = add_ref(ref, sha1, flag, list, NULL);
200                 }
201                 free(ref);
202                 closedir(dir);
203         }
204         return list;
205 }
206
207 static struct ref_list *get_loose_refs(void)
208 {
209         if (!cached_refs.did_loose) {
210                 cached_refs.loose = get_ref_dir("refs", NULL);
211                 cached_refs.did_loose = 1;
212         }
213         return cached_refs.loose;
214 }
215
216 /* We allow "recursive" symbolic refs. Only within reason, though */
217 #define MAXDEPTH 5
218
219 const char *resolve_ref(const char *ref, unsigned char *sha1, int reading, int *flag)
220 {
221         int depth = MAXDEPTH, len;
222         char buffer[256];
223         static char ref_buffer[256];
224
225         if (flag)
226                 *flag = 0;
227
228         for (;;) {
229                 const char *path = git_path("%s", ref);
230                 struct stat st;
231                 char *buf;
232                 int fd;
233
234                 if (--depth < 0)
235                         return NULL;
236
237                 /* Special case: non-existing file.
238                  * Not having the refs/heads/new-branch is OK
239                  * if we are writing into it, so is .git/HEAD
240                  * that points at refs/heads/master still to be
241                  * born.  It is NOT OK if we are resolving for
242                  * reading.
243                  */
244                 if (lstat(path, &st) < 0) {
245                         struct ref_list *list = get_packed_refs();
246                         while (list) {
247                                 if (!strcmp(ref, list->name)) {
248                                         hashcpy(sha1, list->sha1);
249                                         if (flag)
250                                                 *flag |= REF_ISPACKED;
251                                         return ref;
252                                 }
253                                 list = list->next;
254                         }
255                         if (reading || errno != ENOENT)
256                                 return NULL;
257                         hashclr(sha1);
258                         return ref;
259                 }
260
261                 /* Follow "normalized" - ie "refs/.." symlinks by hand */
262                 if (S_ISLNK(st.st_mode)) {
263                         len = readlink(path, buffer, sizeof(buffer)-1);
264                         if (len >= 5 && !memcmp("refs/", buffer, 5)) {
265                                 buffer[len] = 0;
266                                 strcpy(ref_buffer, buffer);
267                                 ref = ref_buffer;
268                                 if (flag)
269                                         *flag |= REF_ISSYMREF;
270                                 continue;
271                         }
272                 }
273
274                 /* Is it a directory? */
275                 if (S_ISDIR(st.st_mode)) {
276                         errno = EISDIR;
277                         return NULL;
278                 }
279
280                 /*
281                  * Anything else, just open it and try to use it as
282                  * a ref
283                  */
284                 fd = open(path, O_RDONLY);
285                 if (fd < 0)
286                         return NULL;
287                 len = read_in_full(fd, buffer, sizeof(buffer)-1);
288                 close(fd);
289
290                 /*
291                  * Is it a symbolic ref?
292                  */
293                 if (len < 4 || memcmp("ref:", buffer, 4))
294                         break;
295                 buf = buffer + 4;
296                 len -= 4;
297                 while (len && isspace(*buf))
298                         buf++, len--;
299                 while (len && isspace(buf[len-1]))
300                         len--;
301                 buf[len] = 0;
302                 memcpy(ref_buffer, buf, len + 1);
303                 ref = ref_buffer;
304                 if (flag)
305                         *flag |= REF_ISSYMREF;
306         }
307         if (len < 40 || get_sha1_hex(buffer, sha1))
308                 return NULL;
309         return ref;
310 }
311
312 int read_ref(const char *ref, unsigned char *sha1)
313 {
314         if (resolve_ref(ref, sha1, 1, NULL))
315                 return 0;
316         return -1;
317 }
318
319 static int do_one_ref(const char *base, each_ref_fn fn, int trim,
320                       void *cb_data, struct ref_list *entry)
321 {
322         if (strncmp(base, entry->name, trim))
323                 return 0;
324         if (is_null_sha1(entry->sha1))
325                 return 0;
326         if (!has_sha1_file(entry->sha1)) {
327                 error("%s does not point to a valid object!", entry->name);
328                 return 0;
329         }
330         return fn(entry->name + trim, entry->sha1, entry->flag, cb_data);
331 }
332
333 int peel_ref(const char *ref, unsigned char *sha1)
334 {
335         int flag;
336         unsigned char base[20];
337         struct object *o;
338
339         if (!resolve_ref(ref, base, 1, &flag))
340                 return -1;
341
342         if ((flag & REF_ISPACKED)) {
343                 struct ref_list *list = get_packed_refs();
344
345                 while (list) {
346                         if (!strcmp(list->name, ref)) {
347                                 if (list->flag & REF_KNOWS_PEELED) {
348                                         hashcpy(sha1, list->peeled);
349                                         return 0;
350                                 }
351                                 /* older pack-refs did not leave peeled ones */
352                                 break;
353                         }
354                         list = list->next;
355                 }
356         }
357
358         /* fallback - callers should not call this for unpacked refs */
359         o = parse_object(base);
360         if (o->type == OBJ_TAG) {
361                 o = deref_tag(o, ref, 0);
362                 if (o) {
363                         hashcpy(sha1, o->sha1);
364                         return 0;
365                 }
366         }
367         return -1;
368 }
369
370 static int do_for_each_ref(const char *base, each_ref_fn fn, int trim,
371                            void *cb_data)
372 {
373         int retval;
374         struct ref_list *packed = get_packed_refs();
375         struct ref_list *loose = get_loose_refs();
376
377         while (packed && loose) {
378                 struct ref_list *entry;
379                 int cmp = strcmp(packed->name, loose->name);
380                 if (!cmp) {
381                         packed = packed->next;
382                         continue;
383                 }
384                 if (cmp > 0) {
385                         entry = loose;
386                         loose = loose->next;
387                 } else {
388                         entry = packed;
389                         packed = packed->next;
390                 }
391                 retval = do_one_ref(base, fn, trim, cb_data, entry);
392                 if (retval)
393                         return retval;
394         }
395
396         for (packed = packed ? packed : loose; packed; packed = packed->next) {
397                 retval = do_one_ref(base, fn, trim, cb_data, packed);
398                 if (retval)
399                         return retval;
400         }
401         return 0;
402 }
403
404 int head_ref(each_ref_fn fn, void *cb_data)
405 {
406         unsigned char sha1[20];
407         int flag;
408
409         if (resolve_ref("HEAD", sha1, 1, &flag))
410                 return fn("HEAD", sha1, flag, cb_data);
411         return 0;
412 }
413
414 int for_each_ref(each_ref_fn fn, void *cb_data)
415 {
416         return do_for_each_ref("refs/", fn, 0, cb_data);
417 }
418
419 int for_each_tag_ref(each_ref_fn fn, void *cb_data)
420 {
421         return do_for_each_ref("refs/tags/", fn, 10, cb_data);
422 }
423
424 int for_each_branch_ref(each_ref_fn fn, void *cb_data)
425 {
426         return do_for_each_ref("refs/heads/", fn, 11, cb_data);
427 }
428
429 int for_each_remote_ref(each_ref_fn fn, void *cb_data)
430 {
431         return do_for_each_ref("refs/remotes/", fn, 13, cb_data);
432 }
433
434 /* NEEDSWORK: This is only used by ssh-upload and it should go; the
435  * caller should do resolve_ref or read_ref like everybody else.  Or
436  * maybe everybody else should use get_ref_sha1() instead of doing
437  * read_ref().
438  */
439 int get_ref_sha1(const char *ref, unsigned char *sha1)
440 {
441         if (check_ref_format(ref))
442                 return -1;
443         return read_ref(mkpath("refs/%s", ref), sha1);
444 }
445
446 /*
447  * Make sure "ref" is something reasonable to have under ".git/refs/";
448  * We do not like it if:
449  *
450  * - any path component of it begins with ".", or
451  * - it has double dots "..", or
452  * - it has ASCII control character, "~", "^", ":" or SP, anywhere, or
453  * - it ends with a "/".
454  */
455
456 static inline int bad_ref_char(int ch)
457 {
458         return (((unsigned) ch) <= ' ' ||
459                 ch == '~' || ch == '^' || ch == ':' ||
460                 /* 2.13 Pattern Matching Notation */
461                 ch == '?' || ch == '*' || ch == '[');
462 }
463
464 int check_ref_format(const char *ref)
465 {
466         int ch, level;
467         const char *cp = ref;
468
469         level = 0;
470         while (1) {
471                 while ((ch = *cp++) == '/')
472                         ; /* tolerate duplicated slashes */
473                 if (!ch)
474                         return -1; /* should not end with slashes */
475
476                 /* we are at the beginning of the path component */
477                 if (ch == '.' || bad_ref_char(ch))
478                         return -1;
479
480                 /* scan the rest of the path component */
481                 while ((ch = *cp++) != 0) {
482                         if (bad_ref_char(ch))
483                                 return -1;
484                         if (ch == '/')
485                                 break;
486                         if (ch == '.' && *cp == '.')
487                                 return -1;
488                 }
489                 level++;
490                 if (!ch) {
491                         if (level < 2)
492                                 return -2; /* at least of form "heads/blah" */
493                         return 0;
494                 }
495         }
496 }
497
498 static struct ref_lock *verify_lock(struct ref_lock *lock,
499         const unsigned char *old_sha1, int mustexist)
500 {
501         if (!resolve_ref(lock->ref_name, lock->old_sha1, mustexist, NULL)) {
502                 error("Can't verify ref %s", lock->ref_name);
503                 unlock_ref(lock);
504                 return NULL;
505         }
506         if (hashcmp(lock->old_sha1, old_sha1)) {
507                 error("Ref %s is at %s but expected %s", lock->ref_name,
508                         sha1_to_hex(lock->old_sha1), sha1_to_hex(old_sha1));
509                 unlock_ref(lock);
510                 return NULL;
511         }
512         return lock;
513 }
514
515 static int remove_empty_dir_recursive(char *path, int len)
516 {
517         DIR *dir = opendir(path);
518         struct dirent *e;
519         int ret = 0;
520
521         if (!dir)
522                 return -1;
523         if (path[len-1] != '/')
524                 path[len++] = '/';
525         while ((e = readdir(dir)) != NULL) {
526                 struct stat st;
527                 int namlen;
528                 if ((e->d_name[0] == '.') &&
529                     ((e->d_name[1] == 0) ||
530                      ((e->d_name[1] == '.') && e->d_name[2] == 0)))
531                         continue; /* "." and ".." */
532
533                 namlen = strlen(e->d_name);
534                 if ((len + namlen < PATH_MAX) &&
535                     strcpy(path + len, e->d_name) &&
536                     !lstat(path, &st) &&
537                     S_ISDIR(st.st_mode) &&
538                     !remove_empty_dir_recursive(path, len + namlen))
539                         continue; /* happy */
540
541                 /* path too long, stat fails, or non-directory still exists */
542                 ret = -1;
543                 break;
544         }
545         closedir(dir);
546         if (!ret) {
547                 path[len] = 0;
548                 ret = rmdir(path);
549         }
550         return ret;
551 }
552
553 static int remove_empty_directories(char *file)
554 {
555         /* we want to create a file but there is a directory there;
556          * if that is an empty directory (or a directory that contains
557          * only empty directories), remove them.
558          */
559         char path[PATH_MAX];
560         int len = strlen(file);
561
562         if (len >= PATH_MAX) /* path too long ;-) */
563                 return -1;
564         strcpy(path, file);
565         return remove_empty_dir_recursive(path, len);
566 }
567
568 static int is_refname_available(const char *ref, const char *oldref,
569                                 struct ref_list *list, int quiet)
570 {
571         int namlen = strlen(ref); /* e.g. 'foo/bar' */
572         while (list) {
573                 /* list->name could be 'foo' or 'foo/bar/baz' */
574                 if (!oldref || strcmp(oldref, list->name)) {
575                         int len = strlen(list->name);
576                         int cmplen = (namlen < len) ? namlen : len;
577                         const char *lead = (namlen < len) ? list->name : ref;
578                         if (!strncmp(ref, list->name, cmplen) &&
579                             lead[cmplen] == '/') {
580                                 if (!quiet)
581                                         error("'%s' exists; cannot create '%s'",
582                                               list->name, ref);
583                                 return 0;
584                         }
585                 }
586                 list = list->next;
587         }
588         return 1;
589 }
590
591 static struct ref_lock *lock_ref_sha1_basic(const char *ref, const unsigned char *old_sha1, int *flag)
592 {
593         char *ref_file;
594         const char *orig_ref = ref;
595         struct ref_lock *lock;
596         struct stat st;
597         int last_errno = 0;
598         int mustexist = (old_sha1 && !is_null_sha1(old_sha1));
599
600         lock = xcalloc(1, sizeof(struct ref_lock));
601         lock->lock_fd = -1;
602
603         ref = resolve_ref(ref, lock->old_sha1, mustexist, flag);
604         if (!ref && errno == EISDIR) {
605                 /* we are trying to lock foo but we used to
606                  * have foo/bar which now does not exist;
607                  * it is normal for the empty directory 'foo'
608                  * to remain.
609                  */
610                 ref_file = git_path("%s", orig_ref);
611                 if (remove_empty_directories(ref_file)) {
612                         last_errno = errno;
613                         error("there are still refs under '%s'", orig_ref);
614                         goto error_return;
615                 }
616                 ref = resolve_ref(orig_ref, lock->old_sha1, mustexist, flag);
617         }
618         if (!ref) {
619                 last_errno = errno;
620                 error("unable to resolve reference %s: %s",
621                         orig_ref, strerror(errno));
622                 goto error_return;
623         }
624         /* When the ref did not exist and we are creating it,
625          * make sure there is no existing ref that is packed
626          * whose name begins with our refname, nor a ref whose
627          * name is a proper prefix of our refname.
628          */
629         if (is_null_sha1(lock->old_sha1) &&
630             !is_refname_available(ref, NULL, get_packed_refs(), 0))
631                 goto error_return;
632
633         lock->lk = xcalloc(1, sizeof(struct lock_file));
634
635         lock->ref_name = xstrdup(ref);
636         lock->orig_ref_name = xstrdup(orig_ref);
637         ref_file = git_path("%s", ref);
638         lock->force_write = lstat(ref_file, &st) && errno == ENOENT;
639
640         if (safe_create_leading_directories(ref_file)) {
641                 last_errno = errno;
642                 error("unable to create directory for %s", ref_file);
643                 goto error_return;
644         }
645         lock->lock_fd = hold_lock_file_for_update(lock->lk, ref_file, 1);
646
647         return old_sha1 ? verify_lock(lock, old_sha1, mustexist) : lock;
648
649  error_return:
650         unlock_ref(lock);
651         errno = last_errno;
652         return NULL;
653 }
654
655 struct ref_lock *lock_ref_sha1(const char *ref, const unsigned char *old_sha1)
656 {
657         char refpath[PATH_MAX];
658         if (check_ref_format(ref))
659                 return NULL;
660         strcpy(refpath, mkpath("refs/%s", ref));
661         return lock_ref_sha1_basic(refpath, old_sha1, NULL);
662 }
663
664 struct ref_lock *lock_any_ref_for_update(const char *ref, const unsigned char *old_sha1)
665 {
666         if (check_ref_format(ref) == -1)
667                 return NULL;
668         return lock_ref_sha1_basic(ref, old_sha1, NULL);
669 }
670
671 static struct lock_file packlock;
672
673 static int repack_without_ref(const char *refname)
674 {
675         struct ref_list *list, *packed_ref_list;
676         int fd;
677         int found = 0;
678
679         packed_ref_list = get_packed_refs();
680         for (list = packed_ref_list; list; list = list->next) {
681                 if (!strcmp(refname, list->name)) {
682                         found = 1;
683                         break;
684                 }
685         }
686         if (!found)
687                 return 0;
688         fd = hold_lock_file_for_update(&packlock, git_path("packed-refs"), 0);
689         if (fd < 0)
690                 return error("cannot delete '%s' from packed refs", refname);
691
692         for (list = packed_ref_list; list; list = list->next) {
693                 char line[PATH_MAX + 100];
694                 int len;
695
696                 if (!strcmp(refname, list->name))
697                         continue;
698                 len = snprintf(line, sizeof(line), "%s %s\n",
699                                sha1_to_hex(list->sha1), list->name);
700                 /* this should not happen but just being defensive */
701                 if (len > sizeof(line))
702                         die("too long a refname '%s'", list->name);
703                 write_or_die(fd, line, len);
704         }
705         return commit_lock_file(&packlock);
706 }
707
708 int delete_ref(const char *refname, unsigned char *sha1)
709 {
710         struct ref_lock *lock;
711         int err, i, ret = 0, flag = 0;
712
713         lock = lock_ref_sha1_basic(refname, sha1, &flag);
714         if (!lock)
715                 return 1;
716         if (!(flag & REF_ISPACKED)) {
717                 /* loose */
718                 i = strlen(lock->lk->filename) - 5; /* .lock */
719                 lock->lk->filename[i] = 0;
720                 err = unlink(lock->lk->filename);
721                 if (err) {
722                         ret = 1;
723                         error("unlink(%s) failed: %s",
724                               lock->lk->filename, strerror(errno));
725                 }
726                 lock->lk->filename[i] = '.';
727         }
728         /* removing the loose one could have resurrected an earlier
729          * packed one.  Also, if it was not loose we need to repack
730          * without it.
731          */
732         ret |= repack_without_ref(refname);
733
734         err = unlink(git_path("logs/%s", lock->ref_name));
735         if (err && errno != ENOENT)
736                 fprintf(stderr, "warning: unlink(%s) failed: %s",
737                         git_path("logs/%s", lock->ref_name), strerror(errno));
738         invalidate_cached_refs();
739         unlock_ref(lock);
740         return ret;
741 }
742
743 int rename_ref(const char *oldref, const char *newref, const char *logmsg)
744 {
745         static const char renamed_ref[] = "RENAMED-REF";
746         unsigned char sha1[20], orig_sha1[20];
747         int flag = 0, logmoved = 0;
748         struct ref_lock *lock;
749         struct stat loginfo;
750         int log = !lstat(git_path("logs/%s", oldref), &loginfo);
751
752         if (S_ISLNK(loginfo.st_mode))
753                 return error("reflog for %s is a symlink", oldref);
754
755         if (!resolve_ref(oldref, orig_sha1, 1, &flag))
756                 return error("refname %s not found", oldref);
757
758         if (!is_refname_available(newref, oldref, get_packed_refs(), 0))
759                 return 1;
760
761         if (!is_refname_available(newref, oldref, get_loose_refs(), 0))
762                 return 1;
763
764         lock = lock_ref_sha1_basic(renamed_ref, NULL, NULL);
765         if (!lock)
766                 return error("unable to lock %s", renamed_ref);
767         lock->force_write = 1;
768         if (write_ref_sha1(lock, orig_sha1, logmsg))
769                 return error("unable to save current sha1 in %s", renamed_ref);
770
771         if (log && rename(git_path("logs/%s", oldref), git_path("tmp-renamed-log")))
772                 return error("unable to move logfile logs/%s to tmp-renamed-log: %s",
773                         oldref, strerror(errno));
774
775         if (delete_ref(oldref, orig_sha1)) {
776                 error("unable to delete old %s", oldref);
777                 goto rollback;
778         }
779
780         if (resolve_ref(newref, sha1, 1, &flag) && delete_ref(newref, sha1)) {
781                 if (errno==EISDIR) {
782                         if (remove_empty_directories(git_path("%s", newref))) {
783                                 error("Directory not empty: %s", newref);
784                                 goto rollback;
785                         }
786                 } else {
787                         error("unable to delete existing %s", newref);
788                         goto rollback;
789                 }
790         }
791
792         if (log && safe_create_leading_directories(git_path("logs/%s", newref))) {
793                 error("unable to create directory for %s", newref);
794                 goto rollback;
795         }
796
797  retry:
798         if (log && rename(git_path("tmp-renamed-log"), git_path("logs/%s", newref))) {
799                 if (errno==EISDIR || errno==ENOTDIR) {
800                         /*
801                          * rename(a, b) when b is an existing
802                          * directory ought to result in ISDIR, but
803                          * Solaris 5.8 gives ENOTDIR.  Sheesh.
804                          */
805                         if (remove_empty_directories(git_path("logs/%s", newref))) {
806                                 error("Directory not empty: logs/%s", newref);
807                                 goto rollback;
808                         }
809                         goto retry;
810                 } else {
811                         error("unable to move logfile tmp-renamed-log to logs/%s: %s",
812                                 newref, strerror(errno));
813                         goto rollback;
814                 }
815         }
816         logmoved = log;
817
818         lock = lock_ref_sha1_basic(newref, NULL, NULL);
819         if (!lock) {
820                 error("unable to lock %s for update", newref);
821                 goto rollback;
822         }
823
824         lock->force_write = 1;
825         hashcpy(lock->old_sha1, orig_sha1);
826         if (write_ref_sha1(lock, orig_sha1, logmsg)) {
827                 error("unable to write current sha1 into %s", newref);
828                 goto rollback;
829         }
830
831         if (!strncmp(oldref, "refs/heads/", 11) &&
832                         !strncmp(newref, "refs/heads/", 11)) {
833                 char oldsection[1024], newsection[1024];
834
835                 snprintf(oldsection, 1024, "branch.%s", oldref + 11);
836                 snprintf(newsection, 1024, "branch.%s", newref + 11);
837                 if (git_config_rename_section(oldsection, newsection) < 0)
838                         return 1;
839         }
840
841         return 0;
842
843  rollback:
844         lock = lock_ref_sha1_basic(oldref, NULL, NULL);
845         if (!lock) {
846                 error("unable to lock %s for rollback", oldref);
847                 goto rollbacklog;
848         }
849
850         lock->force_write = 1;
851         flag = log_all_ref_updates;
852         log_all_ref_updates = 0;
853         if (write_ref_sha1(lock, orig_sha1, NULL))
854                 error("unable to write current sha1 into %s", oldref);
855         log_all_ref_updates = flag;
856
857  rollbacklog:
858         if (logmoved && rename(git_path("logs/%s", newref), git_path("logs/%s", oldref)))
859                 error("unable to restore logfile %s from %s: %s",
860                         oldref, newref, strerror(errno));
861         if (!logmoved && log &&
862             rename(git_path("tmp-renamed-log"), git_path("logs/%s", oldref)))
863                 error("unable to restore logfile %s from tmp-renamed-log: %s",
864                         oldref, strerror(errno));
865
866         return 1;
867 }
868
869 void unlock_ref(struct ref_lock *lock)
870 {
871         if (lock->lock_fd >= 0) {
872                 close(lock->lock_fd);
873                 /* Do not free lock->lk -- atexit() still looks at them */
874                 if (lock->lk)
875                         rollback_lock_file(lock->lk);
876         }
877         free(lock->ref_name);
878         free(lock->orig_ref_name);
879         free(lock);
880 }
881
882 static int log_ref_write(const char *ref_name, const unsigned char *old_sha1,
883                          const unsigned char *new_sha1, const char *msg)
884 {
885         int logfd, written, oflags = O_APPEND | O_WRONLY;
886         unsigned maxlen, len;
887         int msglen;
888         char *log_file, *logrec;
889         const char *committer;
890
891         if (log_all_ref_updates < 0)
892                 log_all_ref_updates = !is_bare_repository();
893
894         log_file = git_path("logs/%s", ref_name);
895
896         if (log_all_ref_updates &&
897             (!strncmp(ref_name, "refs/heads/", 11) ||
898              !strncmp(ref_name, "refs/remotes/", 13) ||
899              !strcmp(ref_name, "HEAD"))) {
900                 if (safe_create_leading_directories(log_file) < 0)
901                         return error("unable to create directory for %s",
902                                      log_file);
903                 oflags |= O_CREAT;
904         }
905
906         logfd = open(log_file, oflags, 0666);
907         if (logfd < 0) {
908                 if (!(oflags & O_CREAT) && errno == ENOENT)
909                         return 0;
910
911                 if ((oflags & O_CREAT) && errno == EISDIR) {
912                         if (remove_empty_directories(log_file)) {
913                                 return error("There are still logs under '%s'",
914                                              log_file);
915                         }
916                         logfd = open(log_file, oflags, 0666);
917                 }
918
919                 if (logfd < 0)
920                         return error("Unable to append to %s: %s",
921                                      log_file, strerror(errno));
922         }
923
924         msglen = 0;
925         if (msg) {
926                 /* clean up the message and make sure it is a single line */
927                 for ( ; *msg; msg++)
928                         if (!isspace(*msg))
929                                 break;
930                 if (*msg) {
931                         const char *ep = strchr(msg, '\n');
932                         if (ep)
933                                 msglen = ep - msg;
934                         else
935                                 msglen = strlen(msg);
936                 }
937         }
938
939         committer = git_committer_info(-1);
940         maxlen = strlen(committer) + msglen + 100;
941         logrec = xmalloc(maxlen);
942         len = sprintf(logrec, "%s %s %s\n",
943                       sha1_to_hex(old_sha1),
944                       sha1_to_hex(new_sha1),
945                       committer);
946         if (msglen)
947                 len += sprintf(logrec + len - 1, "\t%.*s\n", msglen, msg) - 1;
948         written = len <= maxlen ? write_in_full(logfd, logrec, len) : -1;
949         free(logrec);
950         close(logfd);
951         if (written != len)
952                 return error("Unable to append to %s", log_file);
953         return 0;
954 }
955
956 int write_ref_sha1(struct ref_lock *lock,
957         const unsigned char *sha1, const char *logmsg)
958 {
959         static char term = '\n';
960
961         if (!lock)
962                 return -1;
963         if (!lock->force_write && !hashcmp(lock->old_sha1, sha1)) {
964                 unlock_ref(lock);
965                 return 0;
966         }
967         if (write_in_full(lock->lock_fd, sha1_to_hex(sha1), 40) != 40 ||
968             write_in_full(lock->lock_fd, &term, 1) != 1
969                 || close(lock->lock_fd) < 0) {
970                 error("Couldn't write %s", lock->lk->filename);
971                 unlock_ref(lock);
972                 return -1;
973         }
974         invalidate_cached_refs();
975         if (log_ref_write(lock->ref_name, lock->old_sha1, sha1, logmsg) < 0 ||
976             (strcmp(lock->ref_name, lock->orig_ref_name) &&
977              log_ref_write(lock->orig_ref_name, lock->old_sha1, sha1, logmsg) < 0)) {
978                 unlock_ref(lock);
979                 return -1;
980         }
981         if (commit_lock_file(lock->lk)) {
982                 error("Couldn't set %s", lock->ref_name);
983                 unlock_ref(lock);
984                 return -1;
985         }
986         lock->lock_fd = -1;
987         unlock_ref(lock);
988         return 0;
989 }
990
991 int create_symref(const char *ref_target, const char *refs_heads_master,
992                   const char *logmsg)
993 {
994         const char *lockpath;
995         char ref[1000];
996         int fd, len, written;
997         char *git_HEAD = xstrdup(git_path("%s", ref_target));
998         unsigned char old_sha1[20], new_sha1[20];
999
1000         if (logmsg && read_ref(ref_target, old_sha1))
1001                 hashclr(old_sha1);
1002
1003         if (safe_create_leading_directories(git_HEAD) < 0)
1004                 return error("unable to create directory for %s", git_HEAD);
1005
1006 #ifndef NO_SYMLINK_HEAD
1007         if (prefer_symlink_refs) {
1008                 unlink(git_HEAD);
1009                 if (!symlink(refs_heads_master, git_HEAD))
1010                         goto done;
1011                 fprintf(stderr, "no symlink - falling back to symbolic ref\n");
1012         }
1013 #endif
1014
1015         len = snprintf(ref, sizeof(ref), "ref: %s\n", refs_heads_master);
1016         if (sizeof(ref) <= len) {
1017                 error("refname too long: %s", refs_heads_master);
1018                 goto error_free_return;
1019         }
1020         lockpath = mkpath("%s.lock", git_HEAD);
1021         fd = open(lockpath, O_CREAT | O_EXCL | O_WRONLY, 0666);
1022         if (fd < 0) {
1023                 error("Unable to open %s for writing", lockpath);
1024                 goto error_free_return;
1025         }
1026         written = write_in_full(fd, ref, len);
1027         close(fd);
1028         if (written != len) {
1029                 error("Unable to write to %s", lockpath);
1030                 goto error_unlink_return;
1031         }
1032         if (rename(lockpath, git_HEAD) < 0) {
1033                 error("Unable to create %s", git_HEAD);
1034                 goto error_unlink_return;
1035         }
1036         if (adjust_shared_perm(git_HEAD)) {
1037                 error("Unable to fix permissions on %s", lockpath);
1038         error_unlink_return:
1039                 unlink(lockpath);
1040         error_free_return:
1041                 free(git_HEAD);
1042                 return -1;
1043         }
1044
1045         done:
1046         if (logmsg && !read_ref(refs_heads_master, new_sha1))
1047                 log_ref_write(ref_target, old_sha1, new_sha1, logmsg);
1048
1049         free(git_HEAD);
1050         return 0;
1051 }
1052
1053 static char *ref_msg(const char *line, const char *endp)
1054 {
1055         const char *ep;
1056         char *msg;
1057
1058         line += 82;
1059         for (ep = line; ep < endp && *ep != '\n'; ep++)
1060                 ;
1061         msg = xmalloc(ep - line + 1);
1062         memcpy(msg, line, ep - line);
1063         msg[ep - line] = 0;
1064         return msg;
1065 }
1066
1067 int read_ref_at(const char *ref, unsigned long at_time, int cnt, unsigned char *sha1, char **msg, unsigned long *cutoff_time, int *cutoff_tz, int *cutoff_cnt)
1068 {
1069         const char *logfile, *logdata, *logend, *rec, *lastgt, *lastrec;
1070         char *tz_c;
1071         int logfd, tz, reccnt = 0;
1072         struct stat st;
1073         unsigned long date;
1074         unsigned char logged_sha1[20];
1075         void *log_mapped;
1076
1077         logfile = git_path("logs/%s", ref);
1078         logfd = open(logfile, O_RDONLY, 0);
1079         if (logfd < 0)
1080                 die("Unable to read log %s: %s", logfile, strerror(errno));
1081         fstat(logfd, &st);
1082         if (!st.st_size)
1083                 die("Log %s is empty.", logfile);
1084         log_mapped = xmmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, logfd, 0);
1085         logdata = log_mapped;
1086         close(logfd);
1087
1088         lastrec = NULL;
1089         rec = logend = logdata + st.st_size;
1090         while (logdata < rec) {
1091                 reccnt++;
1092                 if (logdata < rec && *(rec-1) == '\n')
1093                         rec--;
1094                 lastgt = NULL;
1095                 while (logdata < rec && *(rec-1) != '\n') {
1096                         rec--;
1097                         if (*rec == '>')
1098                                 lastgt = rec;
1099                 }
1100                 if (!lastgt)
1101                         die("Log %s is corrupt.", logfile);
1102                 date = strtoul(lastgt + 1, &tz_c, 10);
1103                 if (date <= at_time || cnt == 0) {
1104                         tz = strtoul(tz_c, NULL, 10);
1105                         if (msg)
1106                                 *msg = ref_msg(rec, logend);
1107                         if (cutoff_time)
1108                                 *cutoff_time = date;
1109                         if (cutoff_tz)
1110                                 *cutoff_tz = tz;
1111                         if (cutoff_cnt)
1112                                 *cutoff_cnt = reccnt - 1;
1113                         if (lastrec) {
1114                                 if (get_sha1_hex(lastrec, logged_sha1))
1115                                         die("Log %s is corrupt.", logfile);
1116                                 if (get_sha1_hex(rec + 41, sha1))
1117                                         die("Log %s is corrupt.", logfile);
1118                                 if (hashcmp(logged_sha1, sha1)) {
1119                                         fprintf(stderr,
1120                                                 "warning: Log %s has gap after %s.\n",
1121                                                 logfile, show_rfc2822_date(date, tz));
1122                                 }
1123                         }
1124                         else if (date == at_time) {
1125                                 if (get_sha1_hex(rec + 41, sha1))
1126                                         die("Log %s is corrupt.", logfile);
1127                         }
1128                         else {
1129                                 if (get_sha1_hex(rec + 41, logged_sha1))
1130                                         die("Log %s is corrupt.", logfile);
1131                                 if (hashcmp(logged_sha1, sha1)) {
1132                                         fprintf(stderr,
1133                                                 "warning: Log %s unexpectedly ended on %s.\n",
1134                                                 logfile, show_rfc2822_date(date, tz));
1135                                 }
1136                         }
1137                         munmap(log_mapped, st.st_size);
1138                         return 0;
1139                 }
1140                 lastrec = rec;
1141                 if (cnt > 0)
1142                         cnt--;
1143         }
1144
1145         rec = logdata;
1146         while (rec < logend && *rec != '>' && *rec != '\n')
1147                 rec++;
1148         if (rec == logend || *rec == '\n')
1149                 die("Log %s is corrupt.", logfile);
1150         date = strtoul(rec + 1, &tz_c, 10);
1151         tz = strtoul(tz_c, NULL, 10);
1152         if (get_sha1_hex(logdata, sha1))
1153                 die("Log %s is corrupt.", logfile);
1154         if (msg)
1155                 *msg = ref_msg(logdata, logend);
1156         munmap(log_mapped, st.st_size);
1157
1158         if (cutoff_time)
1159                 *cutoff_time = date;
1160         if (cutoff_tz)
1161                 *cutoff_tz = tz;
1162         if (cutoff_cnt)
1163                 *cutoff_cnt = reccnt;
1164         return 1;
1165 }
1166
1167 int for_each_reflog_ent(const char *ref, each_reflog_ent_fn fn, void *cb_data)
1168 {
1169         const char *logfile;
1170         FILE *logfp;
1171         char buf[1024];
1172         int ret = 0;
1173
1174         logfile = git_path("logs/%s", ref);
1175         logfp = fopen(logfile, "r");
1176         if (!logfp)
1177                 return -1;
1178         while (fgets(buf, sizeof(buf), logfp)) {
1179                 unsigned char osha1[20], nsha1[20];
1180                 char *email_end, *message;
1181                 unsigned long timestamp;
1182                 int len, tz;
1183
1184                 /* old SP new SP name <email> SP time TAB msg LF */
1185                 len = strlen(buf);
1186                 if (len < 83 || buf[len-1] != '\n' ||
1187                     get_sha1_hex(buf, osha1) || buf[40] != ' ' ||
1188                     get_sha1_hex(buf + 41, nsha1) || buf[81] != ' ' ||
1189                     !(email_end = strchr(buf + 82, '>')) ||
1190                     email_end[1] != ' ' ||
1191                     !(timestamp = strtoul(email_end + 2, &message, 10)) ||
1192                     !message || message[0] != ' ' ||
1193                     (message[1] != '+' && message[1] != '-') ||
1194                     !isdigit(message[2]) || !isdigit(message[3]) ||
1195                     !isdigit(message[4]) || !isdigit(message[5]))
1196                         continue; /* corrupt? */
1197                 email_end[1] = '\0';
1198                 tz = strtol(message + 1, NULL, 10);
1199                 if (message[6] != '\t')
1200                         message += 6;
1201                 else
1202                         message += 7;
1203                 ret = fn(osha1, nsha1, buf+82, timestamp, tz, message, cb_data);
1204                 if (ret)
1205                         break;
1206         }
1207         fclose(logfp);
1208         return ret;
1209 }
1210
1211 static int do_for_each_reflog(const char *base, each_ref_fn fn, void *cb_data)
1212 {
1213         DIR *dir = opendir(git_path("logs/%s", base));
1214         int retval = 0;
1215
1216         if (dir) {
1217                 struct dirent *de;
1218                 int baselen = strlen(base);
1219                 char *log = xmalloc(baselen + 257);
1220
1221                 memcpy(log, base, baselen);
1222                 if (baselen && base[baselen-1] != '/')
1223                         log[baselen++] = '/';
1224
1225                 while ((de = readdir(dir)) != NULL) {
1226                         struct stat st;
1227                         int namelen;
1228
1229                         if (de->d_name[0] == '.')
1230                                 continue;
1231                         namelen = strlen(de->d_name);
1232                         if (namelen > 255)
1233                                 continue;
1234                         if (has_extension(de->d_name, ".lock"))
1235                                 continue;
1236                         memcpy(log + baselen, de->d_name, namelen+1);
1237                         if (stat(git_path("logs/%s", log), &st) < 0)
1238                                 continue;
1239                         if (S_ISDIR(st.st_mode)) {
1240                                 retval = do_for_each_reflog(log, fn, cb_data);
1241                         } else {
1242                                 unsigned char sha1[20];
1243                                 if (!resolve_ref(log, sha1, 0, NULL))
1244                                         retval = error("bad ref for %s", log);
1245                                 else
1246                                         retval = fn(log, sha1, 0, cb_data);
1247                         }
1248                         if (retval)
1249                                 break;
1250                 }
1251                 free(log);
1252                 closedir(dir);
1253         }
1254         else if (*base)
1255                 return errno;
1256         return retval;
1257 }
1258
1259 int for_each_reflog(each_ref_fn fn, void *cb_data)
1260 {
1261         return do_for_each_reflog("", fn, cb_data);
1262 }