Merge branch 'js/valgrind'
[git] / refs.c
1 #include "cache.h"
2 #include "refs.h"
3 #include "object.h"
4 #include "tag.h"
5 #include "dir.h"
6
7 /* ISSYMREF=01 and ISPACKED=02 are public interfaces */
8 #define REF_KNOWS_PEELED 04
9
10 struct ref_list {
11         struct ref_list *next;
12         unsigned char flag; /* ISSYMREF? ISPACKED? */
13         unsigned char sha1[20];
14         unsigned char peeled[20];
15         char name[FLEX_ARRAY];
16 };
17
18 static const char *parse_ref_line(char *line, unsigned char *sha1)
19 {
20         /*
21          * 42: the answer to everything.
22          *
23          * In this case, it happens to be the answer to
24          *  40 (length of sha1 hex representation)
25          *  +1 (space in between hex and name)
26          *  +1 (newline at the end of the line)
27          */
28         int len = strlen(line) - 42;
29
30         if (len <= 0)
31                 return NULL;
32         if (get_sha1_hex(line, sha1) < 0)
33                 return NULL;
34         if (!isspace(line[40]))
35                 return NULL;
36         line += 41;
37         if (isspace(*line))
38                 return NULL;
39         if (line[len] != '\n')
40                 return NULL;
41         line[len] = 0;
42
43         return line;
44 }
45
46 static struct ref_list *add_ref(const char *name, const unsigned char *sha1,
47                                 int flag, struct ref_list *list,
48                                 struct ref_list **new_entry)
49 {
50         int len;
51         struct ref_list *entry;
52
53         /* Allocate it and add it in.. */
54         len = strlen(name) + 1;
55         entry = xmalloc(sizeof(struct ref_list) + len);
56         hashcpy(entry->sha1, sha1);
57         hashclr(entry->peeled);
58         memcpy(entry->name, name, len);
59         entry->flag = flag;
60         entry->next = list;
61         if (new_entry)
62                 *new_entry = entry;
63         return entry;
64 }
65
66 /* merge sort the ref list */
67 static struct ref_list *sort_ref_list(struct ref_list *list)
68 {
69         int psize, qsize, last_merge_count, cmp;
70         struct ref_list *p, *q, *l, *e;
71         struct ref_list *new_list = list;
72         int k = 1;
73         int merge_count = 0;
74
75         if (!list)
76                 return list;
77
78         do {
79                 last_merge_count = merge_count;
80                 merge_count = 0;
81
82                 psize = 0;
83
84                 p = new_list;
85                 q = new_list;
86                 new_list = NULL;
87                 l = NULL;
88
89                 while (p) {
90                         merge_count++;
91
92                         while (psize < k && q->next) {
93                                 q = q->next;
94                                 psize++;
95                         }
96                         qsize = k;
97
98                         while ((psize > 0) || (qsize > 0 && q)) {
99                                 if (qsize == 0 || !q) {
100                                         e = p;
101                                         p = p->next;
102                                         psize--;
103                                 } else if (psize == 0) {
104                                         e = q;
105                                         q = q->next;
106                                         qsize--;
107                                 } else {
108                                         cmp = strcmp(q->name, p->name);
109                                         if (cmp < 0) {
110                                                 e = q;
111                                                 q = q->next;
112                                                 qsize--;
113                                         } else if (cmp > 0) {
114                                                 e = p;
115                                                 p = p->next;
116                                                 psize--;
117                                         } else {
118                                                 if (hashcmp(q->sha1, p->sha1))
119                                                         die("Duplicated ref, and SHA1s don't match: %s",
120                                                             q->name);
121                                                 warning("Duplicated ref: %s", q->name);
122                                                 e = q;
123                                                 q = q->next;
124                                                 qsize--;
125                                                 free(e);
126                                                 e = p;
127                                                 p = p->next;
128                                                 psize--;
129                                         }
130                                 }
131
132                                 e->next = NULL;
133
134                                 if (l)
135                                         l->next = e;
136                                 if (!new_list)
137                                         new_list = e;
138                                 l = e;
139                         }
140
141                         p = q;
142                 };
143
144                 k = k * 2;
145         } while ((last_merge_count != merge_count) || (last_merge_count != 1));
146
147         return new_list;
148 }
149
150 /*
151  * Future: need to be in "struct repository"
152  * when doing a full libification.
153  */
154 static struct cached_refs {
155         char did_loose;
156         char did_packed;
157         struct ref_list *loose;
158         struct ref_list *packed;
159 } cached_refs;
160 static struct ref_list *current_ref;
161
162 static struct ref_list *extra_refs;
163
164 static void free_ref_list(struct ref_list *list)
165 {
166         struct ref_list *next;
167         for ( ; list; list = next) {
168                 next = list->next;
169                 free(list);
170         }
171 }
172
173 static void invalidate_cached_refs(void)
174 {
175         struct cached_refs *ca = &cached_refs;
176
177         if (ca->did_loose && ca->loose)
178                 free_ref_list(ca->loose);
179         if (ca->did_packed && ca->packed)
180                 free_ref_list(ca->packed);
181         ca->loose = ca->packed = NULL;
182         ca->did_loose = ca->did_packed = 0;
183 }
184
185 static void read_packed_refs(FILE *f, struct cached_refs *cached_refs)
186 {
187         struct ref_list *list = NULL;
188         struct ref_list *last = NULL;
189         char refline[PATH_MAX];
190         int flag = REF_ISPACKED;
191
192         while (fgets(refline, sizeof(refline), f)) {
193                 unsigned char sha1[20];
194                 const char *name;
195                 static const char header[] = "# pack-refs with:";
196
197                 if (!strncmp(refline, header, sizeof(header)-1)) {
198                         const char *traits = refline + sizeof(header) - 1;
199                         if (strstr(traits, " peeled "))
200                                 flag |= REF_KNOWS_PEELED;
201                         /* perhaps other traits later as well */
202                         continue;
203                 }
204
205                 name = parse_ref_line(refline, sha1);
206                 if (name) {
207                         list = add_ref(name, sha1, flag, list, &last);
208                         continue;
209                 }
210                 if (last &&
211                     refline[0] == '^' &&
212                     strlen(refline) == 42 &&
213                     refline[41] == '\n' &&
214                     !get_sha1_hex(refline + 1, sha1))
215                         hashcpy(last->peeled, sha1);
216         }
217         cached_refs->packed = sort_ref_list(list);
218 }
219
220 void add_extra_ref(const char *name, const unsigned char *sha1, int flag)
221 {
222         extra_refs = add_ref(name, sha1, flag, extra_refs, NULL);
223 }
224
225 void clear_extra_refs(void)
226 {
227         free_ref_list(extra_refs);
228         extra_refs = NULL;
229 }
230
231 static struct ref_list *get_packed_refs(void)
232 {
233         if (!cached_refs.did_packed) {
234                 FILE *f = fopen(git_path("packed-refs"), "r");
235                 cached_refs.packed = NULL;
236                 if (f) {
237                         read_packed_refs(f, &cached_refs);
238                         fclose(f);
239                 }
240                 cached_refs.did_packed = 1;
241         }
242         return cached_refs.packed;
243 }
244
245 static struct ref_list *get_ref_dir(const char *base, struct ref_list *list)
246 {
247         DIR *dir = opendir(git_path("%s", base));
248
249         if (dir) {
250                 struct dirent *de;
251                 int baselen = strlen(base);
252                 char *ref = xmalloc(baselen + 257);
253
254                 memcpy(ref, base, baselen);
255                 if (baselen && base[baselen-1] != '/')
256                         ref[baselen++] = '/';
257
258                 while ((de = readdir(dir)) != NULL) {
259                         unsigned char sha1[20];
260                         struct stat st;
261                         int flag;
262                         int namelen;
263
264                         if (de->d_name[0] == '.')
265                                 continue;
266                         namelen = strlen(de->d_name);
267                         if (namelen > 255)
268                                 continue;
269                         if (has_extension(de->d_name, ".lock"))
270                                 continue;
271                         memcpy(ref + baselen, de->d_name, namelen+1);
272                         if (stat(git_path("%s", ref), &st) < 0)
273                                 continue;
274                         if (S_ISDIR(st.st_mode)) {
275                                 list = get_ref_dir(ref, list);
276                                 continue;
277                         }
278                         if (!resolve_ref(ref, sha1, 1, &flag))
279                                 hashclr(sha1);
280                         list = add_ref(ref, sha1, flag, list, NULL);
281                 }
282                 free(ref);
283                 closedir(dir);
284         }
285         return sort_ref_list(list);
286 }
287
288 struct warn_if_dangling_data {
289         const char *refname;
290         const char *msg_fmt;
291 };
292
293 static int warn_if_dangling_symref(const char *refname, const unsigned char *sha1,
294                                    int flags, void *cb_data)
295 {
296         struct warn_if_dangling_data *d = cb_data;
297         const char *resolves_to;
298         unsigned char junk[20];
299
300         if (!(flags & REF_ISSYMREF))
301                 return 0;
302
303         resolves_to = resolve_ref(refname, junk, 0, NULL);
304         if (!resolves_to || strcmp(resolves_to, d->refname))
305                 return 0;
306
307         printf(d->msg_fmt, refname);
308         return 0;
309 }
310
311 void warn_dangling_symref(const char *msg_fmt, const char *refname)
312 {
313         struct warn_if_dangling_data data = { refname, msg_fmt };
314         for_each_rawref(warn_if_dangling_symref, &data);
315 }
316
317 static struct ref_list *get_loose_refs(void)
318 {
319         if (!cached_refs.did_loose) {
320                 cached_refs.loose = get_ref_dir("refs", NULL);
321                 cached_refs.did_loose = 1;
322         }
323         return cached_refs.loose;
324 }
325
326 /* We allow "recursive" symbolic refs. Only within reason, though */
327 #define MAXDEPTH 5
328 #define MAXREFLEN (1024)
329
330 static int resolve_gitlink_packed_ref(char *name, int pathlen, const char *refname, unsigned char *result)
331 {
332         FILE *f;
333         struct cached_refs refs;
334         struct ref_list *ref;
335         int retval;
336
337         strcpy(name + pathlen, "packed-refs");
338         f = fopen(name, "r");
339         if (!f)
340                 return -1;
341         read_packed_refs(f, &refs);
342         fclose(f);
343         ref = refs.packed;
344         retval = -1;
345         while (ref) {
346                 if (!strcmp(ref->name, refname)) {
347                         retval = 0;
348                         memcpy(result, ref->sha1, 20);
349                         break;
350                 }
351                 ref = ref->next;
352         }
353         free_ref_list(refs.packed);
354         return retval;
355 }
356
357 static int resolve_gitlink_ref_recursive(char *name, int pathlen, const char *refname, unsigned char *result, int recursion)
358 {
359         int fd, len = strlen(refname);
360         char buffer[128], *p;
361
362         if (recursion > MAXDEPTH || len > MAXREFLEN)
363                 return -1;
364         memcpy(name + pathlen, refname, len+1);
365         fd = open(name, O_RDONLY);
366         if (fd < 0)
367                 return resolve_gitlink_packed_ref(name, pathlen, refname, result);
368
369         len = read(fd, buffer, sizeof(buffer)-1);
370         close(fd);
371         if (len < 0)
372                 return -1;
373         while (len && isspace(buffer[len-1]))
374                 len--;
375         buffer[len] = 0;
376
377         /* Was it a detached head or an old-fashioned symlink? */
378         if (!get_sha1_hex(buffer, result))
379                 return 0;
380
381         /* Symref? */
382         if (strncmp(buffer, "ref:", 4))
383                 return -1;
384         p = buffer + 4;
385         while (isspace(*p))
386                 p++;
387
388         return resolve_gitlink_ref_recursive(name, pathlen, p, result, recursion+1);
389 }
390
391 int resolve_gitlink_ref(const char *path, const char *refname, unsigned char *result)
392 {
393         int len = strlen(path), retval;
394         char *gitdir;
395         const char *tmp;
396
397         while (len && path[len-1] == '/')
398                 len--;
399         if (!len)
400                 return -1;
401         gitdir = xmalloc(len + MAXREFLEN + 8);
402         memcpy(gitdir, path, len);
403         memcpy(gitdir + len, "/.git", 6);
404         len += 5;
405
406         tmp = read_gitfile_gently(gitdir);
407         if (tmp) {
408                 free(gitdir);
409                 len = strlen(tmp);
410                 gitdir = xmalloc(len + MAXREFLEN + 3);
411                 memcpy(gitdir, tmp, len);
412         }
413         gitdir[len] = '/';
414         gitdir[++len] = '\0';
415         retval = resolve_gitlink_ref_recursive(gitdir, len, refname, result, 0);
416         free(gitdir);
417         return retval;
418 }
419
420 /*
421  * If the "reading" argument is set, this function finds out what _object_
422  * the ref points at by "reading" the ref.  The ref, if it is not symbolic,
423  * has to exist, and if it is symbolic, it has to point at an existing ref,
424  * because the "read" goes through the symref to the ref it points at.
425  *
426  * The access that is not "reading" may often be "writing", but does not
427  * have to; it can be merely checking _where it leads to_. If it is a
428  * prelude to "writing" to the ref, a write to a symref that points at
429  * yet-to-be-born ref will create the real ref pointed by the symref.
430  * reading=0 allows the caller to check where such a symref leads to.
431  */
432 const char *resolve_ref(const char *ref, unsigned char *sha1, int reading, int *flag)
433 {
434         int depth = MAXDEPTH;
435         ssize_t len;
436         char buffer[256];
437         static char ref_buffer[256];
438
439         if (flag)
440                 *flag = 0;
441
442         for (;;) {
443                 char path[PATH_MAX];
444                 struct stat st;
445                 char *buf;
446                 int fd;
447
448                 if (--depth < 0)
449                         return NULL;
450
451                 git_snpath(path, sizeof(path), "%s", ref);
452                 /* Special case: non-existing file. */
453                 if (lstat(path, &st) < 0) {
454                         struct ref_list *list = get_packed_refs();
455                         while (list) {
456                                 if (!strcmp(ref, list->name)) {
457                                         hashcpy(sha1, list->sha1);
458                                         if (flag)
459                                                 *flag |= REF_ISPACKED;
460                                         return ref;
461                                 }
462                                 list = list->next;
463                         }
464                         if (reading || errno != ENOENT)
465                                 return NULL;
466                         hashclr(sha1);
467                         return ref;
468                 }
469
470                 /* Follow "normalized" - ie "refs/.." symlinks by hand */
471                 if (S_ISLNK(st.st_mode)) {
472                         len = readlink(path, buffer, sizeof(buffer)-1);
473                         if (len >= 5 && !memcmp("refs/", buffer, 5)) {
474                                 buffer[len] = 0;
475                                 strcpy(ref_buffer, buffer);
476                                 ref = ref_buffer;
477                                 if (flag)
478                                         *flag |= REF_ISSYMREF;
479                                 continue;
480                         }
481                 }
482
483                 /* Is it a directory? */
484                 if (S_ISDIR(st.st_mode)) {
485                         errno = EISDIR;
486                         return NULL;
487                 }
488
489                 /*
490                  * Anything else, just open it and try to use it as
491                  * a ref
492                  */
493                 fd = open(path, O_RDONLY);
494                 if (fd < 0)
495                         return NULL;
496                 len = read_in_full(fd, buffer, sizeof(buffer)-1);
497                 close(fd);
498
499                 /*
500                  * Is it a symbolic ref?
501                  */
502                 if (len < 4 || memcmp("ref:", buffer, 4))
503                         break;
504                 buf = buffer + 4;
505                 len -= 4;
506                 while (len && isspace(*buf))
507                         buf++, len--;
508                 while (len && isspace(buf[len-1]))
509                         len--;
510                 buf[len] = 0;
511                 memcpy(ref_buffer, buf, len + 1);
512                 ref = ref_buffer;
513                 if (flag)
514                         *flag |= REF_ISSYMREF;
515         }
516         if (len < 40 || get_sha1_hex(buffer, sha1))
517                 return NULL;
518         return ref;
519 }
520
521 int read_ref(const char *ref, unsigned char *sha1)
522 {
523         if (resolve_ref(ref, sha1, 1, NULL))
524                 return 0;
525         return -1;
526 }
527
528 #define DO_FOR_EACH_INCLUDE_BROKEN 01
529 static int do_one_ref(const char *base, each_ref_fn fn, int trim,
530                       int flags, void *cb_data, struct ref_list *entry)
531 {
532         if (strncmp(base, entry->name, trim))
533                 return 0;
534         if (!(flags & DO_FOR_EACH_INCLUDE_BROKEN)) {
535                 if (is_null_sha1(entry->sha1))
536                         return 0;
537                 if (!has_sha1_file(entry->sha1)) {
538                         error("%s does not point to a valid object!", entry->name);
539                         return 0;
540                 }
541         }
542         current_ref = entry;
543         return fn(entry->name + trim, entry->sha1, entry->flag, cb_data);
544 }
545
546 int peel_ref(const char *ref, unsigned char *sha1)
547 {
548         int flag;
549         unsigned char base[20];
550         struct object *o;
551
552         if (current_ref && (current_ref->name == ref
553                 || !strcmp(current_ref->name, ref))) {
554                 if (current_ref->flag & REF_KNOWS_PEELED) {
555                         hashcpy(sha1, current_ref->peeled);
556                         return 0;
557                 }
558                 hashcpy(base, current_ref->sha1);
559                 goto fallback;
560         }
561
562         if (!resolve_ref(ref, base, 1, &flag))
563                 return -1;
564
565         if ((flag & REF_ISPACKED)) {
566                 struct ref_list *list = get_packed_refs();
567
568                 while (list) {
569                         if (!strcmp(list->name, ref)) {
570                                 if (list->flag & REF_KNOWS_PEELED) {
571                                         hashcpy(sha1, list->peeled);
572                                         return 0;
573                                 }
574                                 /* older pack-refs did not leave peeled ones */
575                                 break;
576                         }
577                         list = list->next;
578                 }
579         }
580
581 fallback:
582         o = parse_object(base);
583         if (o && o->type == OBJ_TAG) {
584                 o = deref_tag(o, ref, 0);
585                 if (o) {
586                         hashcpy(sha1, o->sha1);
587                         return 0;
588                 }
589         }
590         return -1;
591 }
592
593 static int do_for_each_ref(const char *base, each_ref_fn fn, int trim,
594                            int flags, void *cb_data)
595 {
596         int retval = 0;
597         struct ref_list *packed = get_packed_refs();
598         struct ref_list *loose = get_loose_refs();
599
600         struct ref_list *extra;
601
602         for (extra = extra_refs; extra; extra = extra->next)
603                 retval = do_one_ref(base, fn, trim, flags, cb_data, extra);
604
605         while (packed && loose) {
606                 struct ref_list *entry;
607                 int cmp = strcmp(packed->name, loose->name);
608                 if (!cmp) {
609                         packed = packed->next;
610                         continue;
611                 }
612                 if (cmp > 0) {
613                         entry = loose;
614                         loose = loose->next;
615                 } else {
616                         entry = packed;
617                         packed = packed->next;
618                 }
619                 retval = do_one_ref(base, fn, trim, flags, cb_data, entry);
620                 if (retval)
621                         goto end_each;
622         }
623
624         for (packed = packed ? packed : loose; packed; packed = packed->next) {
625                 retval = do_one_ref(base, fn, trim, flags, cb_data, packed);
626                 if (retval)
627                         goto end_each;
628         }
629
630 end_each:
631         current_ref = NULL;
632         return retval;
633 }
634
635 int head_ref(each_ref_fn fn, void *cb_data)
636 {
637         unsigned char sha1[20];
638         int flag;
639
640         if (resolve_ref("HEAD", sha1, 1, &flag))
641                 return fn("HEAD", sha1, flag, cb_data);
642         return 0;
643 }
644
645 int for_each_ref(each_ref_fn fn, void *cb_data)
646 {
647         return do_for_each_ref("refs/", fn, 0, 0, cb_data);
648 }
649
650 int for_each_tag_ref(each_ref_fn fn, void *cb_data)
651 {
652         return do_for_each_ref("refs/tags/", fn, 10, 0, cb_data);
653 }
654
655 int for_each_branch_ref(each_ref_fn fn, void *cb_data)
656 {
657         return do_for_each_ref("refs/heads/", fn, 11, 0, cb_data);
658 }
659
660 int for_each_remote_ref(each_ref_fn fn, void *cb_data)
661 {
662         return do_for_each_ref("refs/remotes/", fn, 13, 0, cb_data);
663 }
664
665 int for_each_rawref(each_ref_fn fn, void *cb_data)
666 {
667         return do_for_each_ref("refs/", fn, 0,
668                                DO_FOR_EACH_INCLUDE_BROKEN, cb_data);
669 }
670
671 /*
672  * Make sure "ref" is something reasonable to have under ".git/refs/";
673  * We do not like it if:
674  *
675  * - any path component of it begins with ".", or
676  * - it has double dots "..", or
677  * - it has ASCII control character, "~", "^", ":" or SP, anywhere, or
678  * - it ends with a "/".
679  */
680
681 static inline int bad_ref_char(int ch)
682 {
683         if (((unsigned) ch) <= ' ' ||
684             ch == '~' || ch == '^' || ch == ':')
685                 return 1;
686         /* 2.13 Pattern Matching Notation */
687         if (ch == '?' || ch == '[') /* Unsupported */
688                 return 1;
689         if (ch == '*') /* Supported at the end */
690                 return 2;
691         return 0;
692 }
693
694 int check_ref_format(const char *ref)
695 {
696         int ch, level, bad_type;
697         const char *cp = ref;
698
699         level = 0;
700         while (1) {
701                 while ((ch = *cp++) == '/')
702                         ; /* tolerate duplicated slashes */
703                 if (!ch)
704                         /* should not end with slashes */
705                         return CHECK_REF_FORMAT_ERROR;
706
707                 /* we are at the beginning of the path component */
708                 if (ch == '.')
709                         return CHECK_REF_FORMAT_ERROR;
710                 bad_type = bad_ref_char(ch);
711                 if (bad_type) {
712                         return (bad_type == 2 && !*cp)
713                                 ? CHECK_REF_FORMAT_WILDCARD
714                                 : CHECK_REF_FORMAT_ERROR;
715                 }
716
717                 /* scan the rest of the path component */
718                 while ((ch = *cp++) != 0) {
719                         bad_type = bad_ref_char(ch);
720                         if (bad_type) {
721                                 return (bad_type == 2 && !*cp)
722                                         ? CHECK_REF_FORMAT_WILDCARD
723                                         : CHECK_REF_FORMAT_ERROR;
724                         }
725                         if (ch == '/')
726                                 break;
727                         if (ch == '.' && *cp == '.')
728                                 return CHECK_REF_FORMAT_ERROR;
729                 }
730                 level++;
731                 if (!ch) {
732                         if (level < 2)
733                                 return CHECK_REF_FORMAT_ONELEVEL;
734                         return CHECK_REF_FORMAT_OK;
735                 }
736         }
737 }
738
739 const char *ref_rev_parse_rules[] = {
740         "%.*s",
741         "refs/%.*s",
742         "refs/tags/%.*s",
743         "refs/heads/%.*s",
744         "refs/remotes/%.*s",
745         "refs/remotes/%.*s/HEAD",
746         NULL
747 };
748
749 const char *ref_fetch_rules[] = {
750         "%.*s",
751         "refs/%.*s",
752         "refs/heads/%.*s",
753         NULL
754 };
755
756 int refname_match(const char *abbrev_name, const char *full_name, const char **rules)
757 {
758         const char **p;
759         const int abbrev_name_len = strlen(abbrev_name);
760
761         for (p = rules; *p; p++) {
762                 if (!strcmp(full_name, mkpath(*p, abbrev_name_len, abbrev_name))) {
763                         return 1;
764                 }
765         }
766
767         return 0;
768 }
769
770 static struct ref_lock *verify_lock(struct ref_lock *lock,
771         const unsigned char *old_sha1, int mustexist)
772 {
773         if (!resolve_ref(lock->ref_name, lock->old_sha1, mustexist, NULL)) {
774                 error("Can't verify ref %s", lock->ref_name);
775                 unlock_ref(lock);
776                 return NULL;
777         }
778         if (hashcmp(lock->old_sha1, old_sha1)) {
779                 error("Ref %s is at %s but expected %s", lock->ref_name,
780                         sha1_to_hex(lock->old_sha1), sha1_to_hex(old_sha1));
781                 unlock_ref(lock);
782                 return NULL;
783         }
784         return lock;
785 }
786
787 static int remove_empty_directories(const char *file)
788 {
789         /* we want to create a file but there is a directory there;
790          * if that is an empty directory (or a directory that contains
791          * only empty directories), remove them.
792          */
793         struct strbuf path;
794         int result;
795
796         strbuf_init(&path, 20);
797         strbuf_addstr(&path, file);
798
799         result = remove_dir_recursively(&path, 1);
800
801         strbuf_release(&path);
802
803         return result;
804 }
805
806 static int is_refname_available(const char *ref, const char *oldref,
807                                 struct ref_list *list, int quiet)
808 {
809         int namlen = strlen(ref); /* e.g. 'foo/bar' */
810         while (list) {
811                 /* list->name could be 'foo' or 'foo/bar/baz' */
812                 if (!oldref || strcmp(oldref, list->name)) {
813                         int len = strlen(list->name);
814                         int cmplen = (namlen < len) ? namlen : len;
815                         const char *lead = (namlen < len) ? list->name : ref;
816                         if (!strncmp(ref, list->name, cmplen) &&
817                             lead[cmplen] == '/') {
818                                 if (!quiet)
819                                         error("'%s' exists; cannot create '%s'",
820                                               list->name, ref);
821                                 return 0;
822                         }
823                 }
824                 list = list->next;
825         }
826         return 1;
827 }
828
829 static struct ref_lock *lock_ref_sha1_basic(const char *ref, const unsigned char *old_sha1, int flags, int *type_p)
830 {
831         char *ref_file;
832         const char *orig_ref = ref;
833         struct ref_lock *lock;
834         int last_errno = 0;
835         int type, lflags;
836         int mustexist = (old_sha1 && !is_null_sha1(old_sha1));
837         int missing = 0;
838
839         lock = xcalloc(1, sizeof(struct ref_lock));
840         lock->lock_fd = -1;
841
842         ref = resolve_ref(ref, lock->old_sha1, mustexist, &type);
843         if (!ref && errno == EISDIR) {
844                 /* we are trying to lock foo but we used to
845                  * have foo/bar which now does not exist;
846                  * it is normal for the empty directory 'foo'
847                  * to remain.
848                  */
849                 ref_file = git_path("%s", orig_ref);
850                 if (remove_empty_directories(ref_file)) {
851                         last_errno = errno;
852                         error("there are still refs under '%s'", orig_ref);
853                         goto error_return;
854                 }
855                 ref = resolve_ref(orig_ref, lock->old_sha1, mustexist, &type);
856         }
857         if (type_p)
858             *type_p = type;
859         if (!ref) {
860                 last_errno = errno;
861                 error("unable to resolve reference %s: %s",
862                         orig_ref, strerror(errno));
863                 goto error_return;
864         }
865         missing = is_null_sha1(lock->old_sha1);
866         /* When the ref did not exist and we are creating it,
867          * make sure there is no existing ref that is packed
868          * whose name begins with our refname, nor a ref whose
869          * name is a proper prefix of our refname.
870          */
871         if (missing &&
872             !is_refname_available(ref, NULL, get_packed_refs(), 0))
873                 goto error_return;
874
875         lock->lk = xcalloc(1, sizeof(struct lock_file));
876
877         lflags = LOCK_DIE_ON_ERROR;
878         if (flags & REF_NODEREF) {
879                 ref = orig_ref;
880                 lflags |= LOCK_NODEREF;
881         }
882         lock->ref_name = xstrdup(ref);
883         lock->orig_ref_name = xstrdup(orig_ref);
884         ref_file = git_path("%s", ref);
885         if (missing)
886                 lock->force_write = 1;
887         if ((flags & REF_NODEREF) && (type & REF_ISSYMREF))
888                 lock->force_write = 1;
889
890         if (safe_create_leading_directories(ref_file)) {
891                 last_errno = errno;
892                 error("unable to create directory for %s", ref_file);
893                 goto error_return;
894         }
895
896         lock->lock_fd = hold_lock_file_for_update(lock->lk, ref_file, lflags);
897         return old_sha1 ? verify_lock(lock, old_sha1, mustexist) : lock;
898
899  error_return:
900         unlock_ref(lock);
901         errno = last_errno;
902         return NULL;
903 }
904
905 struct ref_lock *lock_ref_sha1(const char *ref, const unsigned char *old_sha1)
906 {
907         char refpath[PATH_MAX];
908         if (check_ref_format(ref))
909                 return NULL;
910         strcpy(refpath, mkpath("refs/%s", ref));
911         return lock_ref_sha1_basic(refpath, old_sha1, 0, NULL);
912 }
913
914 struct ref_lock *lock_any_ref_for_update(const char *ref, const unsigned char *old_sha1, int flags)
915 {
916         switch (check_ref_format(ref)) {
917         default:
918                 return NULL;
919         case 0:
920         case CHECK_REF_FORMAT_ONELEVEL:
921                 return lock_ref_sha1_basic(ref, old_sha1, flags, NULL);
922         }
923 }
924
925 static struct lock_file packlock;
926
927 static int repack_without_ref(const char *refname)
928 {
929         struct ref_list *list, *packed_ref_list;
930         int fd;
931         int found = 0;
932
933         packed_ref_list = get_packed_refs();
934         for (list = packed_ref_list; list; list = list->next) {
935                 if (!strcmp(refname, list->name)) {
936                         found = 1;
937                         break;
938                 }
939         }
940         if (!found)
941                 return 0;
942         fd = hold_lock_file_for_update(&packlock, git_path("packed-refs"), 0);
943         if (fd < 0)
944                 return error("cannot delete '%s' from packed refs", refname);
945
946         for (list = packed_ref_list; list; list = list->next) {
947                 char line[PATH_MAX + 100];
948                 int len;
949
950                 if (!strcmp(refname, list->name))
951                         continue;
952                 len = snprintf(line, sizeof(line), "%s %s\n",
953                                sha1_to_hex(list->sha1), list->name);
954                 /* this should not happen but just being defensive */
955                 if (len > sizeof(line))
956                         die("too long a refname '%s'", list->name);
957                 write_or_die(fd, line, len);
958         }
959         return commit_lock_file(&packlock);
960 }
961
962 int delete_ref(const char *refname, const unsigned char *sha1, int delopt)
963 {
964         struct ref_lock *lock;
965         int err, i = 0, ret = 0, flag = 0;
966
967         lock = lock_ref_sha1_basic(refname, sha1, 0, &flag);
968         if (!lock)
969                 return 1;
970         if (!(flag & REF_ISPACKED) || flag & REF_ISSYMREF) {
971                 /* loose */
972                 const char *path;
973
974                 if (!(delopt & REF_NODEREF)) {
975                         i = strlen(lock->lk->filename) - 5; /* .lock */
976                         lock->lk->filename[i] = 0;
977                         path = lock->lk->filename;
978                 } else {
979                         path = git_path("%s", refname);
980                 }
981                 err = unlink(path);
982                 if (err && errno != ENOENT) {
983                         ret = 1;
984                         error("unlink(%s) failed: %s",
985                               path, strerror(errno));
986                 }
987                 if (!(delopt & REF_NODEREF))
988                         lock->lk->filename[i] = '.';
989         }
990         /* removing the loose one could have resurrected an earlier
991          * packed one.  Also, if it was not loose we need to repack
992          * without it.
993          */
994         ret |= repack_without_ref(refname);
995
996         err = unlink(git_path("logs/%s", lock->ref_name));
997         if (err && errno != ENOENT)
998                 fprintf(stderr, "warning: unlink(%s) failed: %s",
999                         git_path("logs/%s", lock->ref_name), strerror(errno));
1000         invalidate_cached_refs();
1001         unlock_ref(lock);
1002         return ret;
1003 }
1004
1005 int rename_ref(const char *oldref, const char *newref, const char *logmsg)
1006 {
1007         static const char renamed_ref[] = "RENAMED-REF";
1008         unsigned char sha1[20], orig_sha1[20];
1009         int flag = 0, logmoved = 0;
1010         struct ref_lock *lock;
1011         struct stat loginfo;
1012         int log = !lstat(git_path("logs/%s", oldref), &loginfo);
1013         const char *symref = NULL;
1014
1015         if (log && S_ISLNK(loginfo.st_mode))
1016                 return error("reflog for %s is a symlink", oldref);
1017
1018         symref = resolve_ref(oldref, orig_sha1, 1, &flag);
1019         if (flag & REF_ISSYMREF)
1020                 return error("refname %s is a symbolic ref, renaming it is not supported",
1021                         oldref);
1022         if (!symref)
1023                 return error("refname %s not found", oldref);
1024
1025         if (!is_refname_available(newref, oldref, get_packed_refs(), 0))
1026                 return 1;
1027
1028         if (!is_refname_available(newref, oldref, get_loose_refs(), 0))
1029                 return 1;
1030
1031         lock = lock_ref_sha1_basic(renamed_ref, NULL, 0, NULL);
1032         if (!lock)
1033                 return error("unable to lock %s", renamed_ref);
1034         lock->force_write = 1;
1035         if (write_ref_sha1(lock, orig_sha1, logmsg))
1036                 return error("unable to save current sha1 in %s", renamed_ref);
1037
1038         if (log && rename(git_path("logs/%s", oldref), git_path("tmp-renamed-log")))
1039                 return error("unable to move logfile logs/%s to tmp-renamed-log: %s",
1040                         oldref, strerror(errno));
1041
1042         if (delete_ref(oldref, orig_sha1, REF_NODEREF)) {
1043                 error("unable to delete old %s", oldref);
1044                 goto rollback;
1045         }
1046
1047         if (resolve_ref(newref, sha1, 1, &flag) && delete_ref(newref, sha1, REF_NODEREF)) {
1048                 if (errno==EISDIR) {
1049                         if (remove_empty_directories(git_path("%s", newref))) {
1050                                 error("Directory not empty: %s", newref);
1051                                 goto rollback;
1052                         }
1053                 } else {
1054                         error("unable to delete existing %s", newref);
1055                         goto rollback;
1056                 }
1057         }
1058
1059         if (log && safe_create_leading_directories(git_path("logs/%s", newref))) {
1060                 error("unable to create directory for %s", newref);
1061                 goto rollback;
1062         }
1063
1064  retry:
1065         if (log && rename(git_path("tmp-renamed-log"), git_path("logs/%s", newref))) {
1066                 if (errno==EISDIR || errno==ENOTDIR) {
1067                         /*
1068                          * rename(a, b) when b is an existing
1069                          * directory ought to result in ISDIR, but
1070                          * Solaris 5.8 gives ENOTDIR.  Sheesh.
1071                          */
1072                         if (remove_empty_directories(git_path("logs/%s", newref))) {
1073                                 error("Directory not empty: logs/%s", newref);
1074                                 goto rollback;
1075                         }
1076                         goto retry;
1077                 } else {
1078                         error("unable to move logfile tmp-renamed-log to logs/%s: %s",
1079                                 newref, strerror(errno));
1080                         goto rollback;
1081                 }
1082         }
1083         logmoved = log;
1084
1085         lock = lock_ref_sha1_basic(newref, NULL, 0, NULL);
1086         if (!lock) {
1087                 error("unable to lock %s for update", newref);
1088                 goto rollback;
1089         }
1090         lock->force_write = 1;
1091         hashcpy(lock->old_sha1, orig_sha1);
1092         if (write_ref_sha1(lock, orig_sha1, logmsg)) {
1093                 error("unable to write current sha1 into %s", newref);
1094                 goto rollback;
1095         }
1096
1097         return 0;
1098
1099  rollback:
1100         lock = lock_ref_sha1_basic(oldref, NULL, 0, NULL);
1101         if (!lock) {
1102                 error("unable to lock %s for rollback", oldref);
1103                 goto rollbacklog;
1104         }
1105
1106         lock->force_write = 1;
1107         flag = log_all_ref_updates;
1108         log_all_ref_updates = 0;
1109         if (write_ref_sha1(lock, orig_sha1, NULL))
1110                 error("unable to write current sha1 into %s", oldref);
1111         log_all_ref_updates = flag;
1112
1113  rollbacklog:
1114         if (logmoved && rename(git_path("logs/%s", newref), git_path("logs/%s", oldref)))
1115                 error("unable to restore logfile %s from %s: %s",
1116                         oldref, newref, strerror(errno));
1117         if (!logmoved && log &&
1118             rename(git_path("tmp-renamed-log"), git_path("logs/%s", oldref)))
1119                 error("unable to restore logfile %s from tmp-renamed-log: %s",
1120                         oldref, strerror(errno));
1121
1122         return 1;
1123 }
1124
1125 int close_ref(struct ref_lock *lock)
1126 {
1127         if (close_lock_file(lock->lk))
1128                 return -1;
1129         lock->lock_fd = -1;
1130         return 0;
1131 }
1132
1133 int commit_ref(struct ref_lock *lock)
1134 {
1135         if (commit_lock_file(lock->lk))
1136                 return -1;
1137         lock->lock_fd = -1;
1138         return 0;
1139 }
1140
1141 void unlock_ref(struct ref_lock *lock)
1142 {
1143         /* Do not free lock->lk -- atexit() still looks at them */
1144         if (lock->lk)
1145                 rollback_lock_file(lock->lk);
1146         free(lock->ref_name);
1147         free(lock->orig_ref_name);
1148         free(lock);
1149 }
1150
1151 /*
1152  * copy the reflog message msg to buf, which has been allocated sufficiently
1153  * large, while cleaning up the whitespaces.  Especially, convert LF to space,
1154  * because reflog file is one line per entry.
1155  */
1156 static int copy_msg(char *buf, const char *msg)
1157 {
1158         char *cp = buf;
1159         char c;
1160         int wasspace = 1;
1161
1162         *cp++ = '\t';
1163         while ((c = *msg++)) {
1164                 if (wasspace && isspace(c))
1165                         continue;
1166                 wasspace = isspace(c);
1167                 if (wasspace)
1168                         c = ' ';
1169                 *cp++ = c;
1170         }
1171         while (buf < cp && isspace(cp[-1]))
1172                 cp--;
1173         *cp++ = '\n';
1174         return cp - buf;
1175 }
1176
1177 static int log_ref_write(const char *ref_name, const unsigned char *old_sha1,
1178                          const unsigned char *new_sha1, const char *msg)
1179 {
1180         int logfd, written, oflags = O_APPEND | O_WRONLY;
1181         unsigned maxlen, len;
1182         int msglen;
1183         char log_file[PATH_MAX];
1184         char *logrec;
1185         const char *committer;
1186
1187         if (log_all_ref_updates < 0)
1188                 log_all_ref_updates = !is_bare_repository();
1189
1190         git_snpath(log_file, sizeof(log_file), "logs/%s", ref_name);
1191
1192         if (log_all_ref_updates &&
1193             (!prefixcmp(ref_name, "refs/heads/") ||
1194              !prefixcmp(ref_name, "refs/remotes/") ||
1195              !strcmp(ref_name, "HEAD"))) {
1196                 if (safe_create_leading_directories(log_file) < 0)
1197                         return error("unable to create directory for %s",
1198                                      log_file);
1199                 oflags |= O_CREAT;
1200         }
1201
1202         logfd = open(log_file, oflags, 0666);
1203         if (logfd < 0) {
1204                 if (!(oflags & O_CREAT) && errno == ENOENT)
1205                         return 0;
1206
1207                 if ((oflags & O_CREAT) && errno == EISDIR) {
1208                         if (remove_empty_directories(log_file)) {
1209                                 return error("There are still logs under '%s'",
1210                                              log_file);
1211                         }
1212                         logfd = open(log_file, oflags, 0666);
1213                 }
1214
1215                 if (logfd < 0)
1216                         return error("Unable to append to %s: %s",
1217                                      log_file, strerror(errno));
1218         }
1219
1220         adjust_shared_perm(log_file);
1221
1222         msglen = msg ? strlen(msg) : 0;
1223         committer = git_committer_info(0);
1224         maxlen = strlen(committer) + msglen + 100;
1225         logrec = xmalloc(maxlen);
1226         len = sprintf(logrec, "%s %s %s\n",
1227                       sha1_to_hex(old_sha1),
1228                       sha1_to_hex(new_sha1),
1229                       committer);
1230         if (msglen)
1231                 len += copy_msg(logrec + len - 1, msg) - 1;
1232         written = len <= maxlen ? write_in_full(logfd, logrec, len) : -1;
1233         free(logrec);
1234         if (close(logfd) != 0 || written != len)
1235                 return error("Unable to append to %s", log_file);
1236         return 0;
1237 }
1238
1239 static int is_branch(const char *refname)
1240 {
1241         return !strcmp(refname, "HEAD") || !prefixcmp(refname, "refs/heads/");
1242 }
1243
1244 int write_ref_sha1(struct ref_lock *lock,
1245         const unsigned char *sha1, const char *logmsg)
1246 {
1247         static char term = '\n';
1248         struct object *o;
1249
1250         if (!lock)
1251                 return -1;
1252         if (!lock->force_write && !hashcmp(lock->old_sha1, sha1)) {
1253                 unlock_ref(lock);
1254                 return 0;
1255         }
1256         o = parse_object(sha1);
1257         if (!o) {
1258                 error("Trying to write ref %s with nonexistant object %s",
1259                         lock->ref_name, sha1_to_hex(sha1));
1260                 unlock_ref(lock);
1261                 return -1;
1262         }
1263         if (o->type != OBJ_COMMIT && is_branch(lock->ref_name)) {
1264                 error("Trying to write non-commit object %s to branch %s",
1265                         sha1_to_hex(sha1), lock->ref_name);
1266                 unlock_ref(lock);
1267                 return -1;
1268         }
1269         if (write_in_full(lock->lock_fd, sha1_to_hex(sha1), 40) != 40 ||
1270             write_in_full(lock->lock_fd, &term, 1) != 1
1271                 || close_ref(lock) < 0) {
1272                 error("Couldn't write %s", lock->lk->filename);
1273                 unlock_ref(lock);
1274                 return -1;
1275         }
1276         invalidate_cached_refs();
1277         if (log_ref_write(lock->ref_name, lock->old_sha1, sha1, logmsg) < 0 ||
1278             (strcmp(lock->ref_name, lock->orig_ref_name) &&
1279              log_ref_write(lock->orig_ref_name, lock->old_sha1, sha1, logmsg) < 0)) {
1280                 unlock_ref(lock);
1281                 return -1;
1282         }
1283         if (strcmp(lock->orig_ref_name, "HEAD") != 0) {
1284                 /*
1285                  * Special hack: If a branch is updated directly and HEAD
1286                  * points to it (may happen on the remote side of a push
1287                  * for example) then logically the HEAD reflog should be
1288                  * updated too.
1289                  * A generic solution implies reverse symref information,
1290                  * but finding all symrefs pointing to the given branch
1291                  * would be rather costly for this rare event (the direct
1292                  * update of a branch) to be worth it.  So let's cheat and
1293                  * check with HEAD only which should cover 99% of all usage
1294                  * scenarios (even 100% of the default ones).
1295                  */
1296                 unsigned char head_sha1[20];
1297                 int head_flag;
1298                 const char *head_ref;
1299                 head_ref = resolve_ref("HEAD", head_sha1, 1, &head_flag);
1300                 if (head_ref && (head_flag & REF_ISSYMREF) &&
1301                     !strcmp(head_ref, lock->ref_name))
1302                         log_ref_write("HEAD", lock->old_sha1, sha1, logmsg);
1303         }
1304         if (commit_ref(lock)) {
1305                 error("Couldn't set %s", lock->ref_name);
1306                 unlock_ref(lock);
1307                 return -1;
1308         }
1309         unlock_ref(lock);
1310         return 0;
1311 }
1312
1313 int create_symref(const char *ref_target, const char *refs_heads_master,
1314                   const char *logmsg)
1315 {
1316         const char *lockpath;
1317         char ref[1000];
1318         int fd, len, written;
1319         char *git_HEAD = git_pathdup("%s", ref_target);
1320         unsigned char old_sha1[20], new_sha1[20];
1321
1322         if (logmsg && read_ref(ref_target, old_sha1))
1323                 hashclr(old_sha1);
1324
1325         if (safe_create_leading_directories(git_HEAD) < 0)
1326                 return error("unable to create directory for %s", git_HEAD);
1327
1328 #ifndef NO_SYMLINK_HEAD
1329         if (prefer_symlink_refs) {
1330                 unlink(git_HEAD);
1331                 if (!symlink(refs_heads_master, git_HEAD))
1332                         goto done;
1333                 fprintf(stderr, "no symlink - falling back to symbolic ref\n");
1334         }
1335 #endif
1336
1337         len = snprintf(ref, sizeof(ref), "ref: %s\n", refs_heads_master);
1338         if (sizeof(ref) <= len) {
1339                 error("refname too long: %s", refs_heads_master);
1340                 goto error_free_return;
1341         }
1342         lockpath = mkpath("%s.lock", git_HEAD);
1343         fd = open(lockpath, O_CREAT | O_EXCL | O_WRONLY, 0666);
1344         if (fd < 0) {
1345                 error("Unable to open %s for writing", lockpath);
1346                 goto error_free_return;
1347         }
1348         written = write_in_full(fd, ref, len);
1349         if (close(fd) != 0 || written != len) {
1350                 error("Unable to write to %s", lockpath);
1351                 goto error_unlink_return;
1352         }
1353         if (rename(lockpath, git_HEAD) < 0) {
1354                 error("Unable to create %s", git_HEAD);
1355                 goto error_unlink_return;
1356         }
1357         if (adjust_shared_perm(git_HEAD)) {
1358                 error("Unable to fix permissions on %s", lockpath);
1359         error_unlink_return:
1360                 unlink(lockpath);
1361         error_free_return:
1362                 free(git_HEAD);
1363                 return -1;
1364         }
1365
1366 #ifndef NO_SYMLINK_HEAD
1367         done:
1368 #endif
1369         if (logmsg && !read_ref(refs_heads_master, new_sha1))
1370                 log_ref_write(ref_target, old_sha1, new_sha1, logmsg);
1371
1372         free(git_HEAD);
1373         return 0;
1374 }
1375
1376 static char *ref_msg(const char *line, const char *endp)
1377 {
1378         const char *ep;
1379         line += 82;
1380         ep = memchr(line, '\n', endp - line);
1381         if (!ep)
1382                 ep = endp;
1383         return xmemdupz(line, ep - line);
1384 }
1385
1386 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)
1387 {
1388         const char *logfile, *logdata, *logend, *rec, *lastgt, *lastrec;
1389         char *tz_c;
1390         int logfd, tz, reccnt = 0;
1391         struct stat st;
1392         unsigned long date;
1393         unsigned char logged_sha1[20];
1394         void *log_mapped;
1395         size_t mapsz;
1396
1397         logfile = git_path("logs/%s", ref);
1398         logfd = open(logfile, O_RDONLY, 0);
1399         if (logfd < 0)
1400                 die("Unable to read log %s: %s", logfile, strerror(errno));
1401         fstat(logfd, &st);
1402         if (!st.st_size)
1403                 die("Log %s is empty.", logfile);
1404         mapsz = xsize_t(st.st_size);
1405         log_mapped = xmmap(NULL, mapsz, PROT_READ, MAP_PRIVATE, logfd, 0);
1406         logdata = log_mapped;
1407         close(logfd);
1408
1409         lastrec = NULL;
1410         rec = logend = logdata + st.st_size;
1411         while (logdata < rec) {
1412                 reccnt++;
1413                 if (logdata < rec && *(rec-1) == '\n')
1414                         rec--;
1415                 lastgt = NULL;
1416                 while (logdata < rec && *(rec-1) != '\n') {
1417                         rec--;
1418                         if (*rec == '>')
1419                                 lastgt = rec;
1420                 }
1421                 if (!lastgt)
1422                         die("Log %s is corrupt.", logfile);
1423                 date = strtoul(lastgt + 1, &tz_c, 10);
1424                 if (date <= at_time || cnt == 0) {
1425                         tz = strtoul(tz_c, NULL, 10);
1426                         if (msg)
1427                                 *msg = ref_msg(rec, logend);
1428                         if (cutoff_time)
1429                                 *cutoff_time = date;
1430                         if (cutoff_tz)
1431                                 *cutoff_tz = tz;
1432                         if (cutoff_cnt)
1433                                 *cutoff_cnt = reccnt - 1;
1434                         if (lastrec) {
1435                                 if (get_sha1_hex(lastrec, logged_sha1))
1436                                         die("Log %s is corrupt.", logfile);
1437                                 if (get_sha1_hex(rec + 41, sha1))
1438                                         die("Log %s is corrupt.", logfile);
1439                                 if (hashcmp(logged_sha1, sha1)) {
1440                                         fprintf(stderr,
1441                                                 "warning: Log %s has gap after %s.\n",
1442                                                 logfile, show_date(date, tz, DATE_RFC2822));
1443                                 }
1444                         }
1445                         else if (date == at_time) {
1446                                 if (get_sha1_hex(rec + 41, sha1))
1447                                         die("Log %s is corrupt.", logfile);
1448                         }
1449                         else {
1450                                 if (get_sha1_hex(rec + 41, logged_sha1))
1451                                         die("Log %s is corrupt.", logfile);
1452                                 if (hashcmp(logged_sha1, sha1)) {
1453                                         fprintf(stderr,
1454                                                 "warning: Log %s unexpectedly ended on %s.\n",
1455                                                 logfile, show_date(date, tz, DATE_RFC2822));
1456                                 }
1457                         }
1458                         munmap(log_mapped, mapsz);
1459                         return 0;
1460                 }
1461                 lastrec = rec;
1462                 if (cnt > 0)
1463                         cnt--;
1464         }
1465
1466         rec = logdata;
1467         while (rec < logend && *rec != '>' && *rec != '\n')
1468                 rec++;
1469         if (rec == logend || *rec == '\n')
1470                 die("Log %s is corrupt.", logfile);
1471         date = strtoul(rec + 1, &tz_c, 10);
1472         tz = strtoul(tz_c, NULL, 10);
1473         if (get_sha1_hex(logdata, sha1))
1474                 die("Log %s is corrupt.", logfile);
1475         if (is_null_sha1(sha1)) {
1476                 if (get_sha1_hex(logdata + 41, sha1))
1477                         die("Log %s is corrupt.", logfile);
1478         }
1479         if (msg)
1480                 *msg = ref_msg(logdata, logend);
1481         munmap(log_mapped, mapsz);
1482
1483         if (cutoff_time)
1484                 *cutoff_time = date;
1485         if (cutoff_tz)
1486                 *cutoff_tz = tz;
1487         if (cutoff_cnt)
1488                 *cutoff_cnt = reccnt;
1489         return 1;
1490 }
1491
1492 int for_each_recent_reflog_ent(const char *ref, each_reflog_ent_fn fn, long ofs, void *cb_data)
1493 {
1494         const char *logfile;
1495         FILE *logfp;
1496         char buf[1024];
1497         int ret = 0;
1498
1499         logfile = git_path("logs/%s", ref);
1500         logfp = fopen(logfile, "r");
1501         if (!logfp)
1502                 return -1;
1503
1504         if (ofs) {
1505                 struct stat statbuf;
1506                 if (fstat(fileno(logfp), &statbuf) ||
1507                     statbuf.st_size < ofs ||
1508                     fseek(logfp, -ofs, SEEK_END) ||
1509                     fgets(buf, sizeof(buf), logfp))
1510                         return -1;
1511         }
1512
1513         while (fgets(buf, sizeof(buf), logfp)) {
1514                 unsigned char osha1[20], nsha1[20];
1515                 char *email_end, *message;
1516                 unsigned long timestamp;
1517                 int len, tz;
1518
1519                 /* old SP new SP name <email> SP time TAB msg LF */
1520                 len = strlen(buf);
1521                 if (len < 83 || buf[len-1] != '\n' ||
1522                     get_sha1_hex(buf, osha1) || buf[40] != ' ' ||
1523                     get_sha1_hex(buf + 41, nsha1) || buf[81] != ' ' ||
1524                     !(email_end = strchr(buf + 82, '>')) ||
1525                     email_end[1] != ' ' ||
1526                     !(timestamp = strtoul(email_end + 2, &message, 10)) ||
1527                     !message || message[0] != ' ' ||
1528                     (message[1] != '+' && message[1] != '-') ||
1529                     !isdigit(message[2]) || !isdigit(message[3]) ||
1530                     !isdigit(message[4]) || !isdigit(message[5]))
1531                         continue; /* corrupt? */
1532                 email_end[1] = '\0';
1533                 tz = strtol(message + 1, NULL, 10);
1534                 if (message[6] != '\t')
1535                         message += 6;
1536                 else
1537                         message += 7;
1538                 ret = fn(osha1, nsha1, buf+82, timestamp, tz, message, cb_data);
1539                 if (ret)
1540                         break;
1541         }
1542         fclose(logfp);
1543         return ret;
1544 }
1545
1546 int for_each_reflog_ent(const char *ref, each_reflog_ent_fn fn, void *cb_data)
1547 {
1548         return for_each_recent_reflog_ent(ref, fn, 0, cb_data);
1549 }
1550
1551 static int do_for_each_reflog(const char *base, each_ref_fn fn, void *cb_data)
1552 {
1553         DIR *dir = opendir(git_path("logs/%s", base));
1554         int retval = 0;
1555
1556         if (dir) {
1557                 struct dirent *de;
1558                 int baselen = strlen(base);
1559                 char *log = xmalloc(baselen + 257);
1560
1561                 memcpy(log, base, baselen);
1562                 if (baselen && base[baselen-1] != '/')
1563                         log[baselen++] = '/';
1564
1565                 while ((de = readdir(dir)) != NULL) {
1566                         struct stat st;
1567                         int namelen;
1568
1569                         if (de->d_name[0] == '.')
1570                                 continue;
1571                         namelen = strlen(de->d_name);
1572                         if (namelen > 255)
1573                                 continue;
1574                         if (has_extension(de->d_name, ".lock"))
1575                                 continue;
1576                         memcpy(log + baselen, de->d_name, namelen+1);
1577                         if (stat(git_path("logs/%s", log), &st) < 0)
1578                                 continue;
1579                         if (S_ISDIR(st.st_mode)) {
1580                                 retval = do_for_each_reflog(log, fn, cb_data);
1581                         } else {
1582                                 unsigned char sha1[20];
1583                                 if (!resolve_ref(log, sha1, 0, NULL))
1584                                         retval = error("bad ref for %s", log);
1585                                 else
1586                                         retval = fn(log, sha1, 0, cb_data);
1587                         }
1588                         if (retval)
1589                                 break;
1590                 }
1591                 free(log);
1592                 closedir(dir);
1593         }
1594         else if (*base)
1595                 return errno;
1596         return retval;
1597 }
1598
1599 int for_each_reflog(each_ref_fn fn, void *cb_data)
1600 {
1601         return do_for_each_reflog("", fn, cb_data);
1602 }
1603
1604 int update_ref(const char *action, const char *refname,
1605                 const unsigned char *sha1, const unsigned char *oldval,
1606                 int flags, enum action_on_err onerr)
1607 {
1608         static struct ref_lock *lock;
1609         lock = lock_any_ref_for_update(refname, oldval, flags);
1610         if (!lock) {
1611                 const char *str = "Cannot lock the ref '%s'.";
1612                 switch (onerr) {
1613                 case MSG_ON_ERR: error(str, refname); break;
1614                 case DIE_ON_ERR: die(str, refname); break;
1615                 case QUIET_ON_ERR: break;
1616                 }
1617                 return 1;
1618         }
1619         if (write_ref_sha1(lock, sha1, action) < 0) {
1620                 const char *str = "Cannot update the ref '%s'.";
1621                 switch (onerr) {
1622                 case MSG_ON_ERR: error(str, refname); break;
1623                 case DIE_ON_ERR: die(str, refname); break;
1624                 case QUIET_ON_ERR: break;
1625                 }
1626                 return 1;
1627         }
1628         return 0;
1629 }
1630
1631 struct ref *find_ref_by_name(struct ref *list, const char *name)
1632 {
1633         for ( ; list; list = list->next)
1634                 if (!strcmp(list->name, name))
1635                         return list;
1636         return NULL;
1637 }