Merge branch 'maint'
[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 *entry;
51
52         /* Allocate it and add it in.. */
53         len = strlen(name) + 1;
54         entry = xmalloc(sizeof(struct ref_list) + len);
55         hashcpy(entry->sha1, sha1);
56         hashclr(entry->peeled);
57         memcpy(entry->name, name, len);
58         entry->flag = flag;
59         entry->next = list;
60         if (new_entry)
61                 *new_entry = entry;
62         return entry;
63 }
64
65 /* merge sort the ref list */
66 static struct ref_list *sort_ref_list(struct ref_list *list)
67 {
68         int psize, qsize, last_merge_count, cmp;
69         struct ref_list *p, *q, *l, *e;
70         struct ref_list *new_list = list;
71         int k = 1;
72         int merge_count = 0;
73
74         if (!list)
75                 return list;
76
77         do {
78                 last_merge_count = merge_count;
79                 merge_count = 0;
80
81                 psize = 0;
82
83                 p = new_list;
84                 q = new_list;
85                 new_list = NULL;
86                 l = NULL;
87
88                 while (p) {
89                         merge_count++;
90
91                         while (psize < k && q->next) {
92                                 q = q->next;
93                                 psize++;
94                         }
95                         qsize = k;
96
97                         while ((psize > 0) || (qsize > 0 && q)) {
98                                 if (qsize == 0 || !q) {
99                                         e = p;
100                                         p = p->next;
101                                         psize--;
102                                 } else if (psize == 0) {
103                                         e = q;
104                                         q = q->next;
105                                         qsize--;
106                                 } else {
107                                         cmp = strcmp(q->name, p->name);
108                                         if (cmp < 0) {
109                                                 e = q;
110                                                 q = q->next;
111                                                 qsize--;
112                                         } else if (cmp > 0) {
113                                                 e = p;
114                                                 p = p->next;
115                                                 psize--;
116                                         } else {
117                                                 if (hashcmp(q->sha1, p->sha1))
118                                                         die("Duplicated ref, and SHA1s don't match: %s",
119                                                             q->name);
120                                                 warning("Duplicated ref: %s", q->name);
121                                                 e = q;
122                                                 q = q->next;
123                                                 qsize--;
124                                                 free(e);
125                                                 e = p;
126                                                 p = p->next;
127                                                 psize--;
128                                         }
129                                 }
130
131                                 e->next = NULL;
132
133                                 if (l)
134                                         l->next = e;
135                                 if (!new_list)
136                                         new_list = e;
137                                 l = e;
138                         }
139
140                         p = q;
141                 };
142
143                 k = k * 2;
144         } while ((last_merge_count != merge_count) || (last_merge_count != 1));
145
146         return new_list;
147 }
148
149 /*
150  * Future: need to be in "struct repository"
151  * when doing a full libification.
152  */
153 static struct cached_refs {
154         char did_loose;
155         char did_packed;
156         struct ref_list *loose;
157         struct ref_list *packed;
158 } cached_refs;
159
160 static void free_ref_list(struct ref_list *list)
161 {
162         struct ref_list *next;
163         for ( ; list; list = next) {
164                 next = list->next;
165                 free(list);
166         }
167 }
168
169 static void invalidate_cached_refs(void)
170 {
171         struct cached_refs *ca = &cached_refs;
172
173         if (ca->did_loose && ca->loose)
174                 free_ref_list(ca->loose);
175         if (ca->did_packed && ca->packed)
176                 free_ref_list(ca->packed);
177         ca->loose = ca->packed = NULL;
178         ca->did_loose = ca->did_packed = 0;
179 }
180
181 static void read_packed_refs(FILE *f, struct cached_refs *cached_refs)
182 {
183         struct ref_list *list = NULL;
184         struct ref_list *last = NULL;
185         char refline[PATH_MAX];
186         int flag = REF_ISPACKED;
187
188         while (fgets(refline, sizeof(refline), f)) {
189                 unsigned char sha1[20];
190                 const char *name;
191                 static const char header[] = "# pack-refs with:";
192
193                 if (!strncmp(refline, header, sizeof(header)-1)) {
194                         const char *traits = refline + sizeof(header) - 1;
195                         if (strstr(traits, " peeled "))
196                                 flag |= REF_KNOWS_PEELED;
197                         /* perhaps other traits later as well */
198                         continue;
199                 }
200
201                 name = parse_ref_line(refline, sha1);
202                 if (name) {
203                         list = add_ref(name, sha1, flag, list, &last);
204                         continue;
205                 }
206                 if (last &&
207                     refline[0] == '^' &&
208                     strlen(refline) == 42 &&
209                     refline[41] == '\n' &&
210                     !get_sha1_hex(refline + 1, sha1))
211                         hashcpy(last->peeled, sha1);
212         }
213         cached_refs->packed = sort_ref_list(list);
214 }
215
216 static struct ref_list *get_packed_refs(void)
217 {
218         if (!cached_refs.did_packed) {
219                 FILE *f = fopen(git_path("packed-refs"), "r");
220                 cached_refs.packed = NULL;
221                 if (f) {
222                         read_packed_refs(f, &cached_refs);
223                         fclose(f);
224                 }
225                 cached_refs.did_packed = 1;
226         }
227         return cached_refs.packed;
228 }
229
230 static struct ref_list *get_ref_dir(const char *base, struct ref_list *list)
231 {
232         DIR *dir = opendir(git_path("%s", base));
233
234         if (dir) {
235                 struct dirent *de;
236                 int baselen = strlen(base);
237                 char *ref = xmalloc(baselen + 257);
238
239                 memcpy(ref, base, baselen);
240                 if (baselen && base[baselen-1] != '/')
241                         ref[baselen++] = '/';
242
243                 while ((de = readdir(dir)) != NULL) {
244                         unsigned char sha1[20];
245                         struct stat st;
246                         int flag;
247                         int namelen;
248
249                         if (de->d_name[0] == '.')
250                                 continue;
251                         namelen = strlen(de->d_name);
252                         if (namelen > 255)
253                                 continue;
254                         if (has_extension(de->d_name, ".lock"))
255                                 continue;
256                         memcpy(ref + baselen, de->d_name, namelen+1);
257                         if (stat(git_path("%s", ref), &st) < 0)
258                                 continue;
259                         if (S_ISDIR(st.st_mode)) {
260                                 list = get_ref_dir(ref, list);
261                                 continue;
262                         }
263                         if (!resolve_ref(ref, sha1, 1, &flag)) {
264                                 error("%s points nowhere!", ref);
265                                 continue;
266                         }
267                         list = add_ref(ref, sha1, flag, list, NULL);
268                 }
269                 free(ref);
270                 closedir(dir);
271         }
272         return sort_ref_list(list);
273 }
274
275 static struct ref_list *get_loose_refs(void)
276 {
277         if (!cached_refs.did_loose) {
278                 cached_refs.loose = get_ref_dir("refs", NULL);
279                 cached_refs.did_loose = 1;
280         }
281         return cached_refs.loose;
282 }
283
284 /* We allow "recursive" symbolic refs. Only within reason, though */
285 #define MAXDEPTH 5
286 #define MAXREFLEN (1024)
287
288 static int resolve_gitlink_packed_ref(char *name, int pathlen, const char *refname, unsigned char *result)
289 {
290         FILE *f;
291         struct cached_refs refs;
292         struct ref_list *ref;
293         int retval;
294
295         strcpy(name + pathlen, "packed-refs");
296         f = fopen(name, "r");
297         if (!f)
298                 return -1;
299         read_packed_refs(f, &refs);
300         fclose(f);
301         ref = refs.packed;
302         retval = -1;
303         while (ref) {
304                 if (!strcmp(ref->name, refname)) {
305                         retval = 0;
306                         memcpy(result, ref->sha1, 20);
307                         break;
308                 }
309                 ref = ref->next;
310         }
311         free_ref_list(refs.packed);
312         return retval;
313 }
314
315 static int resolve_gitlink_ref_recursive(char *name, int pathlen, const char *refname, unsigned char *result, int recursion)
316 {
317         int fd, len = strlen(refname);
318         char buffer[128], *p;
319
320         if (recursion > MAXDEPTH || len > MAXREFLEN)
321                 return -1;
322         memcpy(name + pathlen, refname, len+1);
323         fd = open(name, O_RDONLY);
324         if (fd < 0)
325                 return resolve_gitlink_packed_ref(name, pathlen, refname, result);
326
327         len = read(fd, buffer, sizeof(buffer)-1);
328         close(fd);
329         if (len < 0)
330                 return -1;
331         while (len && isspace(buffer[len-1]))
332                 len--;
333         buffer[len] = 0;
334
335         /* Was it a detached head or an old-fashioned symlink? */
336         if (!get_sha1_hex(buffer, result))
337                 return 0;
338
339         /* Symref? */
340         if (strncmp(buffer, "ref:", 4))
341                 return -1;
342         p = buffer + 4;
343         while (isspace(*p))
344                 p++;
345
346         return resolve_gitlink_ref_recursive(name, pathlen, p, result, recursion+1);
347 }
348
349 int resolve_gitlink_ref(const char *path, const char *refname, unsigned char *result)
350 {
351         int len = strlen(path), retval;
352         char *gitdir;
353
354         while (len && path[len-1] == '/')
355                 len--;
356         if (!len)
357                 return -1;
358         gitdir = xmalloc(len + MAXREFLEN + 8);
359         memcpy(gitdir, path, len);
360         memcpy(gitdir + len, "/.git/", 7);
361
362         retval = resolve_gitlink_ref_recursive(gitdir, len+6, refname, result, 0);
363         free(gitdir);
364         return retval;
365 }
366
367 const char *resolve_ref(const char *ref, unsigned char *sha1, int reading, int *flag)
368 {
369         int depth = MAXDEPTH, len;
370         char buffer[256];
371         static char ref_buffer[256];
372
373         if (flag)
374                 *flag = 0;
375
376         for (;;) {
377                 const char *path = git_path("%s", ref);
378                 struct stat st;
379                 char *buf;
380                 int fd;
381
382                 if (--depth < 0)
383                         return NULL;
384
385                 /* Special case: non-existing file.
386                  * Not having the refs/heads/new-branch is OK
387                  * if we are writing into it, so is .git/HEAD
388                  * that points at refs/heads/master still to be
389                  * born.  It is NOT OK if we are resolving for
390                  * reading.
391                  */
392                 if (lstat(path, &st) < 0) {
393                         struct ref_list *list = get_packed_refs();
394                         while (list) {
395                                 if (!strcmp(ref, list->name)) {
396                                         hashcpy(sha1, list->sha1);
397                                         if (flag)
398                                                 *flag |= REF_ISPACKED;
399                                         return ref;
400                                 }
401                                 list = list->next;
402                         }
403                         if (reading || errno != ENOENT)
404                                 return NULL;
405                         hashclr(sha1);
406                         return ref;
407                 }
408
409                 /* Follow "normalized" - ie "refs/.." symlinks by hand */
410                 if (S_ISLNK(st.st_mode)) {
411                         len = readlink(path, buffer, sizeof(buffer)-1);
412                         if (len >= 5 && !memcmp("refs/", buffer, 5)) {
413                                 buffer[len] = 0;
414                                 strcpy(ref_buffer, buffer);
415                                 ref = ref_buffer;
416                                 if (flag)
417                                         *flag |= REF_ISSYMREF;
418                                 continue;
419                         }
420                 }
421
422                 /* Is it a directory? */
423                 if (S_ISDIR(st.st_mode)) {
424                         errno = EISDIR;
425                         return NULL;
426                 }
427
428                 /*
429                  * Anything else, just open it and try to use it as
430                  * a ref
431                  */
432                 fd = open(path, O_RDONLY);
433                 if (fd < 0)
434                         return NULL;
435                 len = read_in_full(fd, buffer, sizeof(buffer)-1);
436                 close(fd);
437
438                 /*
439                  * Is it a symbolic ref?
440                  */
441                 if (len < 4 || memcmp("ref:", buffer, 4))
442                         break;
443                 buf = buffer + 4;
444                 len -= 4;
445                 while (len && isspace(*buf))
446                         buf++, len--;
447                 while (len && isspace(buf[len-1]))
448                         len--;
449                 buf[len] = 0;
450                 memcpy(ref_buffer, buf, len + 1);
451                 ref = ref_buffer;
452                 if (flag)
453                         *flag |= REF_ISSYMREF;
454         }
455         if (len < 40 || get_sha1_hex(buffer, sha1))
456                 return NULL;
457         return ref;
458 }
459
460 int read_ref(const char *ref, unsigned char *sha1)
461 {
462         if (resolve_ref(ref, sha1, 1, NULL))
463                 return 0;
464         return -1;
465 }
466
467 static int do_one_ref(const char *base, each_ref_fn fn, int trim,
468                       void *cb_data, struct ref_list *entry)
469 {
470         if (strncmp(base, entry->name, trim))
471                 return 0;
472         if (is_null_sha1(entry->sha1))
473                 return 0;
474         if (!has_sha1_file(entry->sha1)) {
475                 error("%s does not point to a valid object!", entry->name);
476                 return 0;
477         }
478         return fn(entry->name + trim, entry->sha1, entry->flag, cb_data);
479 }
480
481 int peel_ref(const char *ref, unsigned char *sha1)
482 {
483         int flag;
484         unsigned char base[20];
485         struct object *o;
486
487         if (!resolve_ref(ref, base, 1, &flag))
488                 return -1;
489
490         if ((flag & REF_ISPACKED)) {
491                 struct ref_list *list = get_packed_refs();
492
493                 while (list) {
494                         if (!strcmp(list->name, ref)) {
495                                 if (list->flag & REF_KNOWS_PEELED) {
496                                         hashcpy(sha1, list->peeled);
497                                         return 0;
498                                 }
499                                 /* older pack-refs did not leave peeled ones */
500                                 break;
501                         }
502                         list = list->next;
503                 }
504         }
505
506         /* fallback - callers should not call this for unpacked refs */
507         o = parse_object(base);
508         if (o->type == OBJ_TAG) {
509                 o = deref_tag(o, ref, 0);
510                 if (o) {
511                         hashcpy(sha1, o->sha1);
512                         return 0;
513                 }
514         }
515         return -1;
516 }
517
518 static int do_for_each_ref(const char *base, each_ref_fn fn, int trim,
519                            void *cb_data)
520 {
521         int retval;
522         struct ref_list *packed = get_packed_refs();
523         struct ref_list *loose = get_loose_refs();
524
525         while (packed && loose) {
526                 struct ref_list *entry;
527                 int cmp = strcmp(packed->name, loose->name);
528                 if (!cmp) {
529                         packed = packed->next;
530                         continue;
531                 }
532                 if (cmp > 0) {
533                         entry = loose;
534                         loose = loose->next;
535                 } else {
536                         entry = packed;
537                         packed = packed->next;
538                 }
539                 retval = do_one_ref(base, fn, trim, cb_data, entry);
540                 if (retval)
541                         return retval;
542         }
543
544         for (packed = packed ? packed : loose; packed; packed = packed->next) {
545                 retval = do_one_ref(base, fn, trim, cb_data, packed);
546                 if (retval)
547                         return retval;
548         }
549         return 0;
550 }
551
552 int head_ref(each_ref_fn fn, void *cb_data)
553 {
554         unsigned char sha1[20];
555         int flag;
556
557         if (resolve_ref("HEAD", sha1, 1, &flag))
558                 return fn("HEAD", sha1, flag, cb_data);
559         return 0;
560 }
561
562 int for_each_ref(each_ref_fn fn, void *cb_data)
563 {
564         return do_for_each_ref("refs/", fn, 0, cb_data);
565 }
566
567 int for_each_tag_ref(each_ref_fn fn, void *cb_data)
568 {
569         return do_for_each_ref("refs/tags/", fn, 10, cb_data);
570 }
571
572 int for_each_branch_ref(each_ref_fn fn, void *cb_data)
573 {
574         return do_for_each_ref("refs/heads/", fn, 11, cb_data);
575 }
576
577 int for_each_remote_ref(each_ref_fn fn, void *cb_data)
578 {
579         return do_for_each_ref("refs/remotes/", fn, 13, cb_data);
580 }
581
582 /* NEEDSWORK: This is only used by ssh-upload and it should go; the
583  * caller should do resolve_ref or read_ref like everybody else.  Or
584  * maybe everybody else should use get_ref_sha1() instead of doing
585  * read_ref().
586  */
587 int get_ref_sha1(const char *ref, unsigned char *sha1)
588 {
589         if (check_ref_format(ref))
590                 return -1;
591         return read_ref(mkpath("refs/%s", ref), sha1);
592 }
593
594 /*
595  * Make sure "ref" is something reasonable to have under ".git/refs/";
596  * We do not like it if:
597  *
598  * - any path component of it begins with ".", or
599  * - it has double dots "..", or
600  * - it has ASCII control character, "~", "^", ":" or SP, anywhere, or
601  * - it ends with a "/".
602  */
603
604 static inline int bad_ref_char(int ch)
605 {
606         if (((unsigned) ch) <= ' ' ||
607             ch == '~' || ch == '^' || ch == ':')
608                 return 1;
609         /* 2.13 Pattern Matching Notation */
610         if (ch == '?' || ch == '[') /* Unsupported */
611                 return 1;
612         if (ch == '*') /* Supported at the end */
613                 return 2;
614         return 0;
615 }
616
617 int check_ref_format(const char *ref)
618 {
619         int ch, level, bad_type;
620         const char *cp = ref;
621
622         level = 0;
623         while (1) {
624                 while ((ch = *cp++) == '/')
625                         ; /* tolerate duplicated slashes */
626                 if (!ch)
627                         return -1; /* should not end with slashes */
628
629                 /* we are at the beginning of the path component */
630                 if (ch == '.')
631                         return -1;
632                 bad_type = bad_ref_char(ch);
633                 if (bad_type) {
634                         return (bad_type == 2 && !*cp) ? -3 : -1;
635                 }
636
637                 /* scan the rest of the path component */
638                 while ((ch = *cp++) != 0) {
639                         bad_type = bad_ref_char(ch);
640                         if (bad_type) {
641                                 return (bad_type == 2 && !*cp) ? -3 : -1;
642                         }
643                         if (ch == '/')
644                                 break;
645                         if (ch == '.' && *cp == '.')
646                                 return -1;
647                 }
648                 level++;
649                 if (!ch) {
650                         if (level < 2)
651                                 return -2; /* at least of form "heads/blah" */
652                         return 0;
653                 }
654         }
655 }
656
657 static struct ref_lock *verify_lock(struct ref_lock *lock,
658         const unsigned char *old_sha1, int mustexist)
659 {
660         if (!resolve_ref(lock->ref_name, lock->old_sha1, mustexist, NULL)) {
661                 error("Can't verify ref %s", lock->ref_name);
662                 unlock_ref(lock);
663                 return NULL;
664         }
665         if (hashcmp(lock->old_sha1, old_sha1)) {
666                 error("Ref %s is at %s but expected %s", lock->ref_name,
667                         sha1_to_hex(lock->old_sha1), sha1_to_hex(old_sha1));
668                 unlock_ref(lock);
669                 return NULL;
670         }
671         return lock;
672 }
673
674 static int remove_empty_dir_recursive(char *path, int len)
675 {
676         DIR *dir = opendir(path);
677         struct dirent *e;
678         int ret = 0;
679
680         if (!dir)
681                 return -1;
682         if (path[len-1] != '/')
683                 path[len++] = '/';
684         while ((e = readdir(dir)) != NULL) {
685                 struct stat st;
686                 int namlen;
687                 if ((e->d_name[0] == '.') &&
688                     ((e->d_name[1] == 0) ||
689                      ((e->d_name[1] == '.') && e->d_name[2] == 0)))
690                         continue; /* "." and ".." */
691
692                 namlen = strlen(e->d_name);
693                 if ((len + namlen < PATH_MAX) &&
694                     strcpy(path + len, e->d_name) &&
695                     !lstat(path, &st) &&
696                     S_ISDIR(st.st_mode) &&
697                     !remove_empty_dir_recursive(path, len + namlen))
698                         continue; /* happy */
699
700                 /* path too long, stat fails, or non-directory still exists */
701                 ret = -1;
702                 break;
703         }
704         closedir(dir);
705         if (!ret) {
706                 path[len] = 0;
707                 ret = rmdir(path);
708         }
709         return ret;
710 }
711
712 static int remove_empty_directories(char *file)
713 {
714         /* we want to create a file but there is a directory there;
715          * if that is an empty directory (or a directory that contains
716          * only empty directories), remove them.
717          */
718         char path[PATH_MAX];
719         int len = strlen(file);
720
721         if (len >= PATH_MAX) /* path too long ;-) */
722                 return -1;
723         strcpy(path, file);
724         return remove_empty_dir_recursive(path, len);
725 }
726
727 static int is_refname_available(const char *ref, const char *oldref,
728                                 struct ref_list *list, int quiet)
729 {
730         int namlen = strlen(ref); /* e.g. 'foo/bar' */
731         while (list) {
732                 /* list->name could be 'foo' or 'foo/bar/baz' */
733                 if (!oldref || strcmp(oldref, list->name)) {
734                         int len = strlen(list->name);
735                         int cmplen = (namlen < len) ? namlen : len;
736                         const char *lead = (namlen < len) ? list->name : ref;
737                         if (!strncmp(ref, list->name, cmplen) &&
738                             lead[cmplen] == '/') {
739                                 if (!quiet)
740                                         error("'%s' exists; cannot create '%s'",
741                                               list->name, ref);
742                                 return 0;
743                         }
744                 }
745                 list = list->next;
746         }
747         return 1;
748 }
749
750 static struct ref_lock *lock_ref_sha1_basic(const char *ref, const unsigned char *old_sha1, int flags, int *type_p)
751 {
752         char *ref_file;
753         const char *orig_ref = ref;
754         struct ref_lock *lock;
755         struct stat st;
756         int last_errno = 0;
757         int type;
758         int mustexist = (old_sha1 && !is_null_sha1(old_sha1));
759
760         lock = xcalloc(1, sizeof(struct ref_lock));
761         lock->lock_fd = -1;
762
763         ref = resolve_ref(ref, lock->old_sha1, mustexist, &type);
764         if (!ref && errno == EISDIR) {
765                 /* we are trying to lock foo but we used to
766                  * have foo/bar which now does not exist;
767                  * it is normal for the empty directory 'foo'
768                  * to remain.
769                  */
770                 ref_file = git_path("%s", orig_ref);
771                 if (remove_empty_directories(ref_file)) {
772                         last_errno = errno;
773                         error("there are still refs under '%s'", orig_ref);
774                         goto error_return;
775                 }
776                 ref = resolve_ref(orig_ref, lock->old_sha1, mustexist, &type);
777         }
778         if (type_p)
779             *type_p = type;
780         if (!ref) {
781                 last_errno = errno;
782                 error("unable to resolve reference %s: %s",
783                         orig_ref, strerror(errno));
784                 goto error_return;
785         }
786         /* When the ref did not exist and we are creating it,
787          * make sure there is no existing ref that is packed
788          * whose name begins with our refname, nor a ref whose
789          * name is a proper prefix of our refname.
790          */
791         if (is_null_sha1(lock->old_sha1) &&
792             !is_refname_available(ref, NULL, get_packed_refs(), 0))
793                 goto error_return;
794
795         lock->lk = xcalloc(1, sizeof(struct lock_file));
796
797         if (flags & REF_NODEREF)
798                 ref = orig_ref;
799         lock->ref_name = xstrdup(ref);
800         lock->orig_ref_name = xstrdup(orig_ref);
801         ref_file = git_path("%s", ref);
802         if (lstat(ref_file, &st) && errno == ENOENT)
803                 lock->force_write = 1;
804         if ((flags & REF_NODEREF) && (type & REF_ISSYMREF))
805                 lock->force_write = 1;
806
807         if (safe_create_leading_directories(ref_file)) {
808                 last_errno = errno;
809                 error("unable to create directory for %s", ref_file);
810                 goto error_return;
811         }
812         lock->lock_fd = hold_lock_file_for_update(lock->lk, ref_file, 1);
813
814         return old_sha1 ? verify_lock(lock, old_sha1, mustexist) : lock;
815
816  error_return:
817         unlock_ref(lock);
818         errno = last_errno;
819         return NULL;
820 }
821
822 struct ref_lock *lock_ref_sha1(const char *ref, const unsigned char *old_sha1)
823 {
824         char refpath[PATH_MAX];
825         if (check_ref_format(ref))
826                 return NULL;
827         strcpy(refpath, mkpath("refs/%s", ref));
828         return lock_ref_sha1_basic(refpath, old_sha1, 0, NULL);
829 }
830
831 struct ref_lock *lock_any_ref_for_update(const char *ref, const unsigned char *old_sha1, int flags)
832 {
833         if (check_ref_format(ref) == -1)
834                 return NULL;
835         return lock_ref_sha1_basic(ref, old_sha1, flags, NULL);
836 }
837
838 static struct lock_file packlock;
839
840 static int repack_without_ref(const char *refname)
841 {
842         struct ref_list *list, *packed_ref_list;
843         int fd;
844         int found = 0;
845
846         packed_ref_list = get_packed_refs();
847         for (list = packed_ref_list; list; list = list->next) {
848                 if (!strcmp(refname, list->name)) {
849                         found = 1;
850                         break;
851                 }
852         }
853         if (!found)
854                 return 0;
855         fd = hold_lock_file_for_update(&packlock, git_path("packed-refs"), 0);
856         if (fd < 0)
857                 return error("cannot delete '%s' from packed refs", refname);
858
859         for (list = packed_ref_list; list; list = list->next) {
860                 char line[PATH_MAX + 100];
861                 int len;
862
863                 if (!strcmp(refname, list->name))
864                         continue;
865                 len = snprintf(line, sizeof(line), "%s %s\n",
866                                sha1_to_hex(list->sha1), list->name);
867                 /* this should not happen but just being defensive */
868                 if (len > sizeof(line))
869                         die("too long a refname '%s'", list->name);
870                 write_or_die(fd, line, len);
871         }
872         close(fd);
873         return commit_lock_file(&packlock);
874 }
875
876 int delete_ref(const char *refname, const unsigned char *sha1)
877 {
878         struct ref_lock *lock;
879         int err, i, ret = 0, flag = 0;
880
881         lock = lock_ref_sha1_basic(refname, sha1, 0, &flag);
882         if (!lock)
883                 return 1;
884         if (!(flag & REF_ISPACKED)) {
885                 /* loose */
886                 i = strlen(lock->lk->filename) - 5; /* .lock */
887                 lock->lk->filename[i] = 0;
888                 err = unlink(lock->lk->filename);
889                 if (err) {
890                         ret = 1;
891                         error("unlink(%s) failed: %s",
892                               lock->lk->filename, strerror(errno));
893                 }
894                 lock->lk->filename[i] = '.';
895         }
896         /* removing the loose one could have resurrected an earlier
897          * packed one.  Also, if it was not loose we need to repack
898          * without it.
899          */
900         ret |= repack_without_ref(refname);
901
902         err = unlink(git_path("logs/%s", lock->ref_name));
903         if (err && errno != ENOENT)
904                 fprintf(stderr, "warning: unlink(%s) failed: %s",
905                         git_path("logs/%s", lock->ref_name), strerror(errno));
906         invalidate_cached_refs();
907         unlock_ref(lock);
908         return ret;
909 }
910
911 int rename_ref(const char *oldref, const char *newref, const char *logmsg)
912 {
913         static const char renamed_ref[] = "RENAMED-REF";
914         unsigned char sha1[20], orig_sha1[20];
915         int flag = 0, logmoved = 0;
916         struct ref_lock *lock;
917         struct stat loginfo;
918         int log = !lstat(git_path("logs/%s", oldref), &loginfo);
919
920         if (S_ISLNK(loginfo.st_mode))
921                 return error("reflog for %s is a symlink", oldref);
922
923         if (!resolve_ref(oldref, orig_sha1, 1, &flag))
924                 return error("refname %s not found", oldref);
925
926         if (!is_refname_available(newref, oldref, get_packed_refs(), 0))
927                 return 1;
928
929         if (!is_refname_available(newref, oldref, get_loose_refs(), 0))
930                 return 1;
931
932         lock = lock_ref_sha1_basic(renamed_ref, NULL, 0, NULL);
933         if (!lock)
934                 return error("unable to lock %s", renamed_ref);
935         lock->force_write = 1;
936         if (write_ref_sha1(lock, orig_sha1, logmsg))
937                 return error("unable to save current sha1 in %s", renamed_ref);
938
939         if (log && rename(git_path("logs/%s", oldref), git_path("tmp-renamed-log")))
940                 return error("unable to move logfile logs/%s to tmp-renamed-log: %s",
941                         oldref, strerror(errno));
942
943         if (delete_ref(oldref, orig_sha1)) {
944                 error("unable to delete old %s", oldref);
945                 goto rollback;
946         }
947
948         if (resolve_ref(newref, sha1, 1, &flag) && delete_ref(newref, sha1)) {
949                 if (errno==EISDIR) {
950                         if (remove_empty_directories(git_path("%s", newref))) {
951                                 error("Directory not empty: %s", newref);
952                                 goto rollback;
953                         }
954                 } else {
955                         error("unable to delete existing %s", newref);
956                         goto rollback;
957                 }
958         }
959
960         if (log && safe_create_leading_directories(git_path("logs/%s", newref))) {
961                 error("unable to create directory for %s", newref);
962                 goto rollback;
963         }
964
965  retry:
966         if (log && rename(git_path("tmp-renamed-log"), git_path("logs/%s", newref))) {
967                 if (errno==EISDIR || errno==ENOTDIR) {
968                         /*
969                          * rename(a, b) when b is an existing
970                          * directory ought to result in ISDIR, but
971                          * Solaris 5.8 gives ENOTDIR.  Sheesh.
972                          */
973                         if (remove_empty_directories(git_path("logs/%s", newref))) {
974                                 error("Directory not empty: logs/%s", newref);
975                                 goto rollback;
976                         }
977                         goto retry;
978                 } else {
979                         error("unable to move logfile tmp-renamed-log to logs/%s: %s",
980                                 newref, strerror(errno));
981                         goto rollback;
982                 }
983         }
984         logmoved = log;
985
986         lock = lock_ref_sha1_basic(newref, NULL, 0, NULL);
987         if (!lock) {
988                 error("unable to lock %s for update", newref);
989                 goto rollback;
990         }
991
992         lock->force_write = 1;
993         hashcpy(lock->old_sha1, orig_sha1);
994         if (write_ref_sha1(lock, orig_sha1, logmsg)) {
995                 error("unable to write current sha1 into %s", newref);
996                 goto rollback;
997         }
998
999         return 0;
1000
1001  rollback:
1002         lock = lock_ref_sha1_basic(oldref, NULL, 0, NULL);
1003         if (!lock) {
1004                 error("unable to lock %s for rollback", oldref);
1005                 goto rollbacklog;
1006         }
1007
1008         lock->force_write = 1;
1009         flag = log_all_ref_updates;
1010         log_all_ref_updates = 0;
1011         if (write_ref_sha1(lock, orig_sha1, NULL))
1012                 error("unable to write current sha1 into %s", oldref);
1013         log_all_ref_updates = flag;
1014
1015  rollbacklog:
1016         if (logmoved && rename(git_path("logs/%s", newref), git_path("logs/%s", oldref)))
1017                 error("unable to restore logfile %s from %s: %s",
1018                         oldref, newref, strerror(errno));
1019         if (!logmoved && log &&
1020             rename(git_path("tmp-renamed-log"), git_path("logs/%s", oldref)))
1021                 error("unable to restore logfile %s from tmp-renamed-log: %s",
1022                         oldref, strerror(errno));
1023
1024         return 1;
1025 }
1026
1027 void unlock_ref(struct ref_lock *lock)
1028 {
1029         if (lock->lock_fd >= 0) {
1030                 close(lock->lock_fd);
1031                 /* Do not free lock->lk -- atexit() still looks at them */
1032                 if (lock->lk)
1033                         rollback_lock_file(lock->lk);
1034         }
1035         free(lock->ref_name);
1036         free(lock->orig_ref_name);
1037         free(lock);
1038 }
1039
1040 /*
1041  * copy the reflog message msg to buf, which has been allocated sufficiently
1042  * large, while cleaning up the whitespaces.  Especially, convert LF to space,
1043  * because reflog file is one line per entry.
1044  */
1045 static int copy_msg(char *buf, const char *msg)
1046 {
1047         char *cp = buf;
1048         char c;
1049         int wasspace = 1;
1050
1051         *cp++ = '\t';
1052         while ((c = *msg++)) {
1053                 if (wasspace && isspace(c))
1054                         continue;
1055                 wasspace = isspace(c);
1056                 if (wasspace)
1057                         c = ' ';
1058                 *cp++ = c;
1059         }
1060         while (buf < cp && isspace(cp[-1]))
1061                 cp--;
1062         *cp++ = '\n';
1063         return cp - buf;
1064 }
1065
1066 static int log_ref_write(const char *ref_name, const unsigned char *old_sha1,
1067                          const unsigned char *new_sha1, const char *msg)
1068 {
1069         int logfd, written, oflags = O_APPEND | O_WRONLY;
1070         unsigned maxlen, len;
1071         int msglen;
1072         char *log_file, *logrec;
1073         const char *committer;
1074
1075         if (log_all_ref_updates < 0)
1076                 log_all_ref_updates = !is_bare_repository();
1077
1078         log_file = git_path("logs/%s", ref_name);
1079
1080         if (log_all_ref_updates &&
1081             (!prefixcmp(ref_name, "refs/heads/") ||
1082              !prefixcmp(ref_name, "refs/remotes/") ||
1083              !strcmp(ref_name, "HEAD"))) {
1084                 if (safe_create_leading_directories(log_file) < 0)
1085                         return error("unable to create directory for %s",
1086                                      log_file);
1087                 oflags |= O_CREAT;
1088         }
1089
1090         logfd = open(log_file, oflags, 0666);
1091         if (logfd < 0) {
1092                 if (!(oflags & O_CREAT) && errno == ENOENT)
1093                         return 0;
1094
1095                 if ((oflags & O_CREAT) && errno == EISDIR) {
1096                         if (remove_empty_directories(log_file)) {
1097                                 return error("There are still logs under '%s'",
1098                                              log_file);
1099                         }
1100                         logfd = open(log_file, oflags, 0666);
1101                 }
1102
1103                 if (logfd < 0)
1104                         return error("Unable to append to %s: %s",
1105                                      log_file, strerror(errno));
1106         }
1107
1108         adjust_shared_perm(log_file);
1109
1110         msglen = msg ? strlen(msg) : 0;
1111         committer = git_committer_info(-1);
1112         maxlen = strlen(committer) + msglen + 100;
1113         logrec = xmalloc(maxlen);
1114         len = sprintf(logrec, "%s %s %s\n",
1115                       sha1_to_hex(old_sha1),
1116                       sha1_to_hex(new_sha1),
1117                       committer);
1118         if (msglen)
1119                 len += copy_msg(logrec + len - 1, msg) - 1;
1120         written = len <= maxlen ? write_in_full(logfd, logrec, len) : -1;
1121         free(logrec);
1122         if (close(logfd) != 0 || written != len)
1123                 return error("Unable to append to %s", log_file);
1124         return 0;
1125 }
1126
1127 int write_ref_sha1(struct ref_lock *lock,
1128         const unsigned char *sha1, const char *logmsg)
1129 {
1130         static char term = '\n';
1131
1132         if (!lock)
1133                 return -1;
1134         if (!lock->force_write && !hashcmp(lock->old_sha1, sha1)) {
1135                 unlock_ref(lock);
1136                 return 0;
1137         }
1138         if (write_in_full(lock->lock_fd, sha1_to_hex(sha1), 40) != 40 ||
1139             write_in_full(lock->lock_fd, &term, 1) != 1
1140                 || close(lock->lock_fd) < 0) {
1141                 error("Couldn't write %s", lock->lk->filename);
1142                 unlock_ref(lock);
1143                 return -1;
1144         }
1145         invalidate_cached_refs();
1146         if (log_ref_write(lock->ref_name, lock->old_sha1, sha1, logmsg) < 0 ||
1147             (strcmp(lock->ref_name, lock->orig_ref_name) &&
1148              log_ref_write(lock->orig_ref_name, lock->old_sha1, sha1, logmsg) < 0)) {
1149                 unlock_ref(lock);
1150                 return -1;
1151         }
1152         if (strcmp(lock->orig_ref_name, "HEAD") != 0) {
1153                 /*
1154                  * Special hack: If a branch is updated directly and HEAD
1155                  * points to it (may happen on the remote side of a push
1156                  * for example) then logically the HEAD reflog should be
1157                  * updated too.
1158                  * A generic solution implies reverse symref information,
1159                  * but finding all symrefs pointing to the given branch
1160                  * would be rather costly for this rare event (the direct
1161                  * update of a branch) to be worth it.  So let's cheat and
1162                  * check with HEAD only which should cover 99% of all usage
1163                  * scenarios (even 100% of the default ones).
1164                  */
1165                 unsigned char head_sha1[20];
1166                 int head_flag;
1167                 const char *head_ref;
1168                 head_ref = resolve_ref("HEAD", head_sha1, 1, &head_flag);
1169                 if (head_ref && (head_flag & REF_ISSYMREF) &&
1170                     !strcmp(head_ref, lock->ref_name))
1171                         log_ref_write("HEAD", lock->old_sha1, sha1, logmsg);
1172         }
1173         if (commit_lock_file(lock->lk)) {
1174                 error("Couldn't set %s", lock->ref_name);
1175                 unlock_ref(lock);
1176                 return -1;
1177         }
1178         lock->lock_fd = -1;
1179         unlock_ref(lock);
1180         return 0;
1181 }
1182
1183 int create_symref(const char *ref_target, const char *refs_heads_master,
1184                   const char *logmsg)
1185 {
1186         const char *lockpath;
1187         char ref[1000];
1188         int fd, len, written;
1189         char *git_HEAD = xstrdup(git_path("%s", ref_target));
1190         unsigned char old_sha1[20], new_sha1[20];
1191
1192         if (logmsg && read_ref(ref_target, old_sha1))
1193                 hashclr(old_sha1);
1194
1195         if (safe_create_leading_directories(git_HEAD) < 0)
1196                 return error("unable to create directory for %s", git_HEAD);
1197
1198 #ifndef NO_SYMLINK_HEAD
1199         if (prefer_symlink_refs) {
1200                 unlink(git_HEAD);
1201                 if (!symlink(refs_heads_master, git_HEAD))
1202                         goto done;
1203                 fprintf(stderr, "no symlink - falling back to symbolic ref\n");
1204         }
1205 #endif
1206
1207         len = snprintf(ref, sizeof(ref), "ref: %s\n", refs_heads_master);
1208         if (sizeof(ref) <= len) {
1209                 error("refname too long: %s", refs_heads_master);
1210                 goto error_free_return;
1211         }
1212         lockpath = mkpath("%s.lock", git_HEAD);
1213         fd = open(lockpath, O_CREAT | O_EXCL | O_WRONLY, 0666);
1214         if (fd < 0) {
1215                 error("Unable to open %s for writing", lockpath);
1216                 goto error_free_return;
1217         }
1218         written = write_in_full(fd, ref, len);
1219         if (close(fd) != 0 || written != len) {
1220                 error("Unable to write to %s", lockpath);
1221                 goto error_unlink_return;
1222         }
1223         if (rename(lockpath, git_HEAD) < 0) {
1224                 error("Unable to create %s", git_HEAD);
1225                 goto error_unlink_return;
1226         }
1227         if (adjust_shared_perm(git_HEAD)) {
1228                 error("Unable to fix permissions on %s", lockpath);
1229         error_unlink_return:
1230                 unlink(lockpath);
1231         error_free_return:
1232                 free(git_HEAD);
1233                 return -1;
1234         }
1235
1236 #ifndef NO_SYMLINK_HEAD
1237         done:
1238 #endif
1239         if (logmsg && !read_ref(refs_heads_master, new_sha1))
1240                 log_ref_write(ref_target, old_sha1, new_sha1, logmsg);
1241
1242         free(git_HEAD);
1243         return 0;
1244 }
1245
1246 static char *ref_msg(const char *line, const char *endp)
1247 {
1248         const char *ep;
1249         line += 82;
1250         ep = memchr(line, '\n', endp - line);
1251         if (!ep)
1252                 ep = endp;
1253         return xmemdupz(line, ep - line);
1254 }
1255
1256 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)
1257 {
1258         const char *logfile, *logdata, *logend, *rec, *lastgt, *lastrec;
1259         char *tz_c;
1260         int logfd, tz, reccnt = 0;
1261         struct stat st;
1262         unsigned long date;
1263         unsigned char logged_sha1[20];
1264         void *log_mapped;
1265         size_t mapsz;
1266
1267         logfile = git_path("logs/%s", ref);
1268         logfd = open(logfile, O_RDONLY, 0);
1269         if (logfd < 0)
1270                 die("Unable to read log %s: %s", logfile, strerror(errno));
1271         fstat(logfd, &st);
1272         if (!st.st_size)
1273                 die("Log %s is empty.", logfile);
1274         mapsz = xsize_t(st.st_size);
1275         log_mapped = xmmap(NULL, mapsz, PROT_READ, MAP_PRIVATE, logfd, 0);
1276         logdata = log_mapped;
1277         close(logfd);
1278
1279         lastrec = NULL;
1280         rec = logend = logdata + st.st_size;
1281         while (logdata < rec) {
1282                 reccnt++;
1283                 if (logdata < rec && *(rec-1) == '\n')
1284                         rec--;
1285                 lastgt = NULL;
1286                 while (logdata < rec && *(rec-1) != '\n') {
1287                         rec--;
1288                         if (*rec == '>')
1289                                 lastgt = rec;
1290                 }
1291                 if (!lastgt)
1292                         die("Log %s is corrupt.", logfile);
1293                 date = strtoul(lastgt + 1, &tz_c, 10);
1294                 if (date <= at_time || cnt == 0) {
1295                         tz = strtoul(tz_c, NULL, 10);
1296                         if (msg)
1297                                 *msg = ref_msg(rec, logend);
1298                         if (cutoff_time)
1299                                 *cutoff_time = date;
1300                         if (cutoff_tz)
1301                                 *cutoff_tz = tz;
1302                         if (cutoff_cnt)
1303                                 *cutoff_cnt = reccnt - 1;
1304                         if (lastrec) {
1305                                 if (get_sha1_hex(lastrec, logged_sha1))
1306                                         die("Log %s is corrupt.", logfile);
1307                                 if (get_sha1_hex(rec + 41, sha1))
1308                                         die("Log %s is corrupt.", logfile);
1309                                 if (hashcmp(logged_sha1, sha1)) {
1310                                         fprintf(stderr,
1311                                                 "warning: Log %s has gap after %s.\n",
1312                                                 logfile, show_date(date, tz, DATE_RFC2822));
1313                                 }
1314                         }
1315                         else if (date == at_time) {
1316                                 if (get_sha1_hex(rec + 41, sha1))
1317                                         die("Log %s is corrupt.", logfile);
1318                         }
1319                         else {
1320                                 if (get_sha1_hex(rec + 41, logged_sha1))
1321                                         die("Log %s is corrupt.", logfile);
1322                                 if (hashcmp(logged_sha1, sha1)) {
1323                                         fprintf(stderr,
1324                                                 "warning: Log %s unexpectedly ended on %s.\n",
1325                                                 logfile, show_date(date, tz, DATE_RFC2822));
1326                                 }
1327                         }
1328                         munmap(log_mapped, mapsz);
1329                         return 0;
1330                 }
1331                 lastrec = rec;
1332                 if (cnt > 0)
1333                         cnt--;
1334         }
1335
1336         rec = logdata;
1337         while (rec < logend && *rec != '>' && *rec != '\n')
1338                 rec++;
1339         if (rec == logend || *rec == '\n')
1340                 die("Log %s is corrupt.", logfile);
1341         date = strtoul(rec + 1, &tz_c, 10);
1342         tz = strtoul(tz_c, NULL, 10);
1343         if (get_sha1_hex(logdata, sha1))
1344                 die("Log %s is corrupt.", logfile);
1345         if (msg)
1346                 *msg = ref_msg(logdata, logend);
1347         munmap(log_mapped, mapsz);
1348
1349         if (cutoff_time)
1350                 *cutoff_time = date;
1351         if (cutoff_tz)
1352                 *cutoff_tz = tz;
1353         if (cutoff_cnt)
1354                 *cutoff_cnt = reccnt;
1355         return 1;
1356 }
1357
1358 int for_each_reflog_ent(const char *ref, each_reflog_ent_fn fn, void *cb_data)
1359 {
1360         const char *logfile;
1361         FILE *logfp;
1362         char buf[1024];
1363         int ret = 0;
1364
1365         logfile = git_path("logs/%s", ref);
1366         logfp = fopen(logfile, "r");
1367         if (!logfp)
1368                 return -1;
1369         while (fgets(buf, sizeof(buf), logfp)) {
1370                 unsigned char osha1[20], nsha1[20];
1371                 char *email_end, *message;
1372                 unsigned long timestamp;
1373                 int len, tz;
1374
1375                 /* old SP new SP name <email> SP time TAB msg LF */
1376                 len = strlen(buf);
1377                 if (len < 83 || buf[len-1] != '\n' ||
1378                     get_sha1_hex(buf, osha1) || buf[40] != ' ' ||
1379                     get_sha1_hex(buf + 41, nsha1) || buf[81] != ' ' ||
1380                     !(email_end = strchr(buf + 82, '>')) ||
1381                     email_end[1] != ' ' ||
1382                     !(timestamp = strtoul(email_end + 2, &message, 10)) ||
1383                     !message || message[0] != ' ' ||
1384                     (message[1] != '+' && message[1] != '-') ||
1385                     !isdigit(message[2]) || !isdigit(message[3]) ||
1386                     !isdigit(message[4]) || !isdigit(message[5]))
1387                         continue; /* corrupt? */
1388                 email_end[1] = '\0';
1389                 tz = strtol(message + 1, NULL, 10);
1390                 if (message[6] != '\t')
1391                         message += 6;
1392                 else
1393                         message += 7;
1394                 ret = fn(osha1, nsha1, buf+82, timestamp, tz, message, cb_data);
1395                 if (ret)
1396                         break;
1397         }
1398         fclose(logfp);
1399         return ret;
1400 }
1401
1402 static int do_for_each_reflog(const char *base, each_ref_fn fn, void *cb_data)
1403 {
1404         DIR *dir = opendir(git_path("logs/%s", base));
1405         int retval = 0;
1406
1407         if (dir) {
1408                 struct dirent *de;
1409                 int baselen = strlen(base);
1410                 char *log = xmalloc(baselen + 257);
1411
1412                 memcpy(log, base, baselen);
1413                 if (baselen && base[baselen-1] != '/')
1414                         log[baselen++] = '/';
1415
1416                 while ((de = readdir(dir)) != NULL) {
1417                         struct stat st;
1418                         int namelen;
1419
1420                         if (de->d_name[0] == '.')
1421                                 continue;
1422                         namelen = strlen(de->d_name);
1423                         if (namelen > 255)
1424                                 continue;
1425                         if (has_extension(de->d_name, ".lock"))
1426                                 continue;
1427                         memcpy(log + baselen, de->d_name, namelen+1);
1428                         if (stat(git_path("logs/%s", log), &st) < 0)
1429                                 continue;
1430                         if (S_ISDIR(st.st_mode)) {
1431                                 retval = do_for_each_reflog(log, fn, cb_data);
1432                         } else {
1433                                 unsigned char sha1[20];
1434                                 if (!resolve_ref(log, sha1, 0, NULL))
1435                                         retval = error("bad ref for %s", log);
1436                                 else
1437                                         retval = fn(log, sha1, 0, cb_data);
1438                         }
1439                         if (retval)
1440                                 break;
1441                 }
1442                 free(log);
1443                 closedir(dir);
1444         }
1445         else if (*base)
1446                 return errno;
1447         return retval;
1448 }
1449
1450 int for_each_reflog(each_ref_fn fn, void *cb_data)
1451 {
1452         return do_for_each_reflog("", fn, cb_data);
1453 }
1454
1455 int update_ref(const char *action, const char *refname,
1456                 const unsigned char *sha1, const unsigned char *oldval,
1457                 int flags, enum action_on_err onerr)
1458 {
1459         static struct ref_lock *lock;
1460         lock = lock_any_ref_for_update(refname, oldval, flags);
1461         if (!lock) {
1462                 const char *str = "Cannot lock the ref '%s'.";
1463                 switch (onerr) {
1464                 case MSG_ON_ERR: error(str, refname); break;
1465                 case DIE_ON_ERR: die(str, refname); break;
1466                 case QUIET_ON_ERR: break;
1467                 }
1468                 return 1;
1469         }
1470         if (write_ref_sha1(lock, sha1, action) < 0) {
1471                 const char *str = "Cannot update the ref '%s'.";
1472                 switch (onerr) {
1473                 case MSG_ON_ERR: error(str, refname); break;
1474                 case DIE_ON_ERR: die(str, refname); break;
1475                 case QUIET_ON_ERR: break;
1476                 }
1477                 return 1;
1478         }
1479         return 0;
1480 }