Merge branch 'maint'
[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_ref_in(const char *prefix, each_ref_fn fn, void *cb_data)
651 {
652         return do_for_each_ref(prefix, fn, strlen(prefix), 0, cb_data);
653 }
654
655 int for_each_tag_ref(each_ref_fn fn, void *cb_data)
656 {
657         return for_each_ref_in("refs/tags/", fn, cb_data);
658 }
659
660 int for_each_branch_ref(each_ref_fn fn, void *cb_data)
661 {
662         return for_each_ref_in("refs/heads/", fn, cb_data);
663 }
664
665 int for_each_remote_ref(each_ref_fn fn, void *cb_data)
666 {
667         return for_each_ref_in("refs/remotes/", fn, cb_data);
668 }
669
670 int for_each_rawref(each_ref_fn fn, void *cb_data)
671 {
672         return do_for_each_ref("refs/", fn, 0,
673                                DO_FOR_EACH_INCLUDE_BROKEN, cb_data);
674 }
675
676 /*
677  * Make sure "ref" is something reasonable to have under ".git/refs/";
678  * We do not like it if:
679  *
680  * - any path component of it begins with ".", or
681  * - it has double dots "..", or
682  * - it has ASCII control character, "~", "^", ":" or SP, anywhere, or
683  * - it ends with a "/".
684  * - it ends with ".lock"
685  */
686
687 static inline int bad_ref_char(int ch)
688 {
689         if (((unsigned) ch) <= ' ' ||
690             ch == '~' || ch == '^' || ch == ':')
691                 return 1;
692         /* 2.13 Pattern Matching Notation */
693         if (ch == '?' || ch == '[') /* Unsupported */
694                 return 1;
695         if (ch == '*') /* Supported at the end */
696                 return 2;
697         return 0;
698 }
699
700 int check_ref_format(const char *ref)
701 {
702         int ch, level, bad_type, last;
703         int ret = CHECK_REF_FORMAT_OK;
704         const char *cp = ref;
705
706         level = 0;
707         while (1) {
708                 while ((ch = *cp++) == '/')
709                         ; /* tolerate duplicated slashes */
710                 if (!ch)
711                         /* should not end with slashes */
712                         return CHECK_REF_FORMAT_ERROR;
713
714                 /* we are at the beginning of the path component */
715                 if (ch == '.')
716                         return CHECK_REF_FORMAT_ERROR;
717                 bad_type = bad_ref_char(ch);
718                 if (bad_type) {
719                         if (bad_type == 2 && (!*cp || *cp == '/') &&
720                             ret == CHECK_REF_FORMAT_OK)
721                                 ret = CHECK_REF_FORMAT_WILDCARD;
722                         else
723                                 return CHECK_REF_FORMAT_ERROR;
724                 }
725
726                 last = ch;
727                 /* scan the rest of the path component */
728                 while ((ch = *cp++) != 0) {
729                         bad_type = bad_ref_char(ch);
730                         if (bad_type)
731                                 return CHECK_REF_FORMAT_ERROR;
732                         if (ch == '/')
733                                 break;
734                         if (last == '.' && ch == '.')
735                                 return CHECK_REF_FORMAT_ERROR;
736                         if (last == '@' && ch == '{')
737                                 return CHECK_REF_FORMAT_ERROR;
738                         last = ch;
739                 }
740                 level++;
741                 if (!ch) {
742                         if (ref <= cp - 2 && cp[-2] == '.')
743                                 return CHECK_REF_FORMAT_ERROR;
744                         if (level < 2)
745                                 return CHECK_REF_FORMAT_ONELEVEL;
746                         if (has_extension(ref, ".lock"))
747                                 return CHECK_REF_FORMAT_ERROR;
748                         return ret;
749                 }
750         }
751 }
752
753 const char *prettify_ref(const struct ref *ref)
754 {
755         const char *name = ref->name;
756         return name + (
757                 !prefixcmp(name, "refs/heads/") ? 11 :
758                 !prefixcmp(name, "refs/tags/") ? 10 :
759                 !prefixcmp(name, "refs/remotes/") ? 13 :
760                 0);
761 }
762
763 const char *ref_rev_parse_rules[] = {
764         "%.*s",
765         "refs/%.*s",
766         "refs/tags/%.*s",
767         "refs/heads/%.*s",
768         "refs/remotes/%.*s",
769         "refs/remotes/%.*s/HEAD",
770         NULL
771 };
772
773 const char *ref_fetch_rules[] = {
774         "%.*s",
775         "refs/%.*s",
776         "refs/heads/%.*s",
777         NULL
778 };
779
780 int refname_match(const char *abbrev_name, const char *full_name, const char **rules)
781 {
782         const char **p;
783         const int abbrev_name_len = strlen(abbrev_name);
784
785         for (p = rules; *p; p++) {
786                 if (!strcmp(full_name, mkpath(*p, abbrev_name_len, abbrev_name))) {
787                         return 1;
788                 }
789         }
790
791         return 0;
792 }
793
794 static struct ref_lock *verify_lock(struct ref_lock *lock,
795         const unsigned char *old_sha1, int mustexist)
796 {
797         if (!resolve_ref(lock->ref_name, lock->old_sha1, mustexist, NULL)) {
798                 error("Can't verify ref %s", lock->ref_name);
799                 unlock_ref(lock);
800                 return NULL;
801         }
802         if (hashcmp(lock->old_sha1, old_sha1)) {
803                 error("Ref %s is at %s but expected %s", lock->ref_name,
804                         sha1_to_hex(lock->old_sha1), sha1_to_hex(old_sha1));
805                 unlock_ref(lock);
806                 return NULL;
807         }
808         return lock;
809 }
810
811 static int remove_empty_directories(const char *file)
812 {
813         /* we want to create a file but there is a directory there;
814          * if that is an empty directory (or a directory that contains
815          * only empty directories), remove them.
816          */
817         struct strbuf path;
818         int result;
819
820         strbuf_init(&path, 20);
821         strbuf_addstr(&path, file);
822
823         result = remove_dir_recursively(&path, 1);
824
825         strbuf_release(&path);
826
827         return result;
828 }
829
830 static int is_refname_available(const char *ref, const char *oldref,
831                                 struct ref_list *list, int quiet)
832 {
833         int namlen = strlen(ref); /* e.g. 'foo/bar' */
834         while (list) {
835                 /* list->name could be 'foo' or 'foo/bar/baz' */
836                 if (!oldref || strcmp(oldref, list->name)) {
837                         int len = strlen(list->name);
838                         int cmplen = (namlen < len) ? namlen : len;
839                         const char *lead = (namlen < len) ? list->name : ref;
840                         if (!strncmp(ref, list->name, cmplen) &&
841                             lead[cmplen] == '/') {
842                                 if (!quiet)
843                                         error("'%s' exists; cannot create '%s'",
844                                               list->name, ref);
845                                 return 0;
846                         }
847                 }
848                 list = list->next;
849         }
850         return 1;
851 }
852
853 static struct ref_lock *lock_ref_sha1_basic(const char *ref, const unsigned char *old_sha1, int flags, int *type_p)
854 {
855         char *ref_file;
856         const char *orig_ref = ref;
857         struct ref_lock *lock;
858         int last_errno = 0;
859         int type, lflags;
860         int mustexist = (old_sha1 && !is_null_sha1(old_sha1));
861         int missing = 0;
862
863         lock = xcalloc(1, sizeof(struct ref_lock));
864         lock->lock_fd = -1;
865
866         ref = resolve_ref(ref, lock->old_sha1, mustexist, &type);
867         if (!ref && errno == EISDIR) {
868                 /* we are trying to lock foo but we used to
869                  * have foo/bar which now does not exist;
870                  * it is normal for the empty directory 'foo'
871                  * to remain.
872                  */
873                 ref_file = git_path("%s", orig_ref);
874                 if (remove_empty_directories(ref_file)) {
875                         last_errno = errno;
876                         error("there are still refs under '%s'", orig_ref);
877                         goto error_return;
878                 }
879                 ref = resolve_ref(orig_ref, lock->old_sha1, mustexist, &type);
880         }
881         if (type_p)
882             *type_p = type;
883         if (!ref) {
884                 last_errno = errno;
885                 error("unable to resolve reference %s: %s",
886                         orig_ref, strerror(errno));
887                 goto error_return;
888         }
889         missing = is_null_sha1(lock->old_sha1);
890         /* When the ref did not exist and we are creating it,
891          * make sure there is no existing ref that is packed
892          * whose name begins with our refname, nor a ref whose
893          * name is a proper prefix of our refname.
894          */
895         if (missing &&
896             !is_refname_available(ref, NULL, get_packed_refs(), 0))
897                 goto error_return;
898
899         lock->lk = xcalloc(1, sizeof(struct lock_file));
900
901         lflags = LOCK_DIE_ON_ERROR;
902         if (flags & REF_NODEREF) {
903                 ref = orig_ref;
904                 lflags |= LOCK_NODEREF;
905         }
906         lock->ref_name = xstrdup(ref);
907         lock->orig_ref_name = xstrdup(orig_ref);
908         ref_file = git_path("%s", ref);
909         if (missing)
910                 lock->force_write = 1;
911         if ((flags & REF_NODEREF) && (type & REF_ISSYMREF))
912                 lock->force_write = 1;
913
914         if (safe_create_leading_directories(ref_file)) {
915                 last_errno = errno;
916                 error("unable to create directory for %s", ref_file);
917                 goto error_return;
918         }
919
920         lock->lock_fd = hold_lock_file_for_update(lock->lk, ref_file, lflags);
921         return old_sha1 ? verify_lock(lock, old_sha1, mustexist) : lock;
922
923  error_return:
924         unlock_ref(lock);
925         errno = last_errno;
926         return NULL;
927 }
928
929 struct ref_lock *lock_ref_sha1(const char *ref, const unsigned char *old_sha1)
930 {
931         char refpath[PATH_MAX];
932         if (check_ref_format(ref))
933                 return NULL;
934         strcpy(refpath, mkpath("refs/%s", ref));
935         return lock_ref_sha1_basic(refpath, old_sha1, 0, NULL);
936 }
937
938 struct ref_lock *lock_any_ref_for_update(const char *ref, const unsigned char *old_sha1, int flags)
939 {
940         switch (check_ref_format(ref)) {
941         default:
942                 return NULL;
943         case 0:
944         case CHECK_REF_FORMAT_ONELEVEL:
945                 return lock_ref_sha1_basic(ref, old_sha1, flags, NULL);
946         }
947 }
948
949 static struct lock_file packlock;
950
951 static int repack_without_ref(const char *refname)
952 {
953         struct ref_list *list, *packed_ref_list;
954         int fd;
955         int found = 0;
956
957         packed_ref_list = get_packed_refs();
958         for (list = packed_ref_list; list; list = list->next) {
959                 if (!strcmp(refname, list->name)) {
960                         found = 1;
961                         break;
962                 }
963         }
964         if (!found)
965                 return 0;
966         fd = hold_lock_file_for_update(&packlock, git_path("packed-refs"), 0);
967         if (fd < 0)
968                 return error("cannot delete '%s' from packed refs", refname);
969
970         for (list = packed_ref_list; list; list = list->next) {
971                 char line[PATH_MAX + 100];
972                 int len;
973
974                 if (!strcmp(refname, list->name))
975                         continue;
976                 len = snprintf(line, sizeof(line), "%s %s\n",
977                                sha1_to_hex(list->sha1), list->name);
978                 /* this should not happen but just being defensive */
979                 if (len > sizeof(line))
980                         die("too long a refname '%s'", list->name);
981                 write_or_die(fd, line, len);
982         }
983         return commit_lock_file(&packlock);
984 }
985
986 int delete_ref(const char *refname, const unsigned char *sha1, int delopt)
987 {
988         struct ref_lock *lock;
989         int err, i = 0, ret = 0, flag = 0;
990
991         lock = lock_ref_sha1_basic(refname, sha1, 0, &flag);
992         if (!lock)
993                 return 1;
994         if (!(flag & REF_ISPACKED) || flag & REF_ISSYMREF) {
995                 /* loose */
996                 const char *path;
997
998                 if (!(delopt & REF_NODEREF)) {
999                         i = strlen(lock->lk->filename) - 5; /* .lock */
1000                         lock->lk->filename[i] = 0;
1001                         path = lock->lk->filename;
1002                 } else {
1003                         path = git_path("%s", refname);
1004                 }
1005                 err = unlink(path);
1006                 if (err && errno != ENOENT) {
1007                         ret = 1;
1008                         error("unlink(%s) failed: %s",
1009                               path, strerror(errno));
1010                 }
1011                 if (!(delopt & REF_NODEREF))
1012                         lock->lk->filename[i] = '.';
1013         }
1014         /* removing the loose one could have resurrected an earlier
1015          * packed one.  Also, if it was not loose we need to repack
1016          * without it.
1017          */
1018         ret |= repack_without_ref(refname);
1019
1020         err = unlink(git_path("logs/%s", lock->ref_name));
1021         if (err && errno != ENOENT)
1022                 warning("unlink(%s) failed: %s",
1023                         git_path("logs/%s", lock->ref_name), strerror(errno));
1024         invalidate_cached_refs();
1025         unlock_ref(lock);
1026         return ret;
1027 }
1028
1029 int rename_ref(const char *oldref, const char *newref, const char *logmsg)
1030 {
1031         static const char renamed_ref[] = "RENAMED-REF";
1032         unsigned char sha1[20], orig_sha1[20];
1033         int flag = 0, logmoved = 0;
1034         struct ref_lock *lock;
1035         struct stat loginfo;
1036         int log = !lstat(git_path("logs/%s", oldref), &loginfo);
1037         const char *symref = NULL;
1038
1039         if (log && S_ISLNK(loginfo.st_mode))
1040                 return error("reflog for %s is a symlink", oldref);
1041
1042         symref = resolve_ref(oldref, orig_sha1, 1, &flag);
1043         if (flag & REF_ISSYMREF)
1044                 return error("refname %s is a symbolic ref, renaming it is not supported",
1045                         oldref);
1046         if (!symref)
1047                 return error("refname %s not found", oldref);
1048
1049         if (!is_refname_available(newref, oldref, get_packed_refs(), 0))
1050                 return 1;
1051
1052         if (!is_refname_available(newref, oldref, get_loose_refs(), 0))
1053                 return 1;
1054
1055         lock = lock_ref_sha1_basic(renamed_ref, NULL, 0, NULL);
1056         if (!lock)
1057                 return error("unable to lock %s", renamed_ref);
1058         lock->force_write = 1;
1059         if (write_ref_sha1(lock, orig_sha1, logmsg))
1060                 return error("unable to save current sha1 in %s", renamed_ref);
1061
1062         if (log && rename(git_path("logs/%s", oldref), git_path("tmp-renamed-log")))
1063                 return error("unable to move logfile logs/%s to tmp-renamed-log: %s",
1064                         oldref, strerror(errno));
1065
1066         if (delete_ref(oldref, orig_sha1, REF_NODEREF)) {
1067                 error("unable to delete old %s", oldref);
1068                 goto rollback;
1069         }
1070
1071         if (resolve_ref(newref, sha1, 1, &flag) && delete_ref(newref, sha1, REF_NODEREF)) {
1072                 if (errno==EISDIR) {
1073                         if (remove_empty_directories(git_path("%s", newref))) {
1074                                 error("Directory not empty: %s", newref);
1075                                 goto rollback;
1076                         }
1077                 } else {
1078                         error("unable to delete existing %s", newref);
1079                         goto rollback;
1080                 }
1081         }
1082
1083         if (log && safe_create_leading_directories(git_path("logs/%s", newref))) {
1084                 error("unable to create directory for %s", newref);
1085                 goto rollback;
1086         }
1087
1088  retry:
1089         if (log && rename(git_path("tmp-renamed-log"), git_path("logs/%s", newref))) {
1090                 if (errno==EISDIR || errno==ENOTDIR) {
1091                         /*
1092                          * rename(a, b) when b is an existing
1093                          * directory ought to result in ISDIR, but
1094                          * Solaris 5.8 gives ENOTDIR.  Sheesh.
1095                          */
1096                         if (remove_empty_directories(git_path("logs/%s", newref))) {
1097                                 error("Directory not empty: logs/%s", newref);
1098                                 goto rollback;
1099                         }
1100                         goto retry;
1101                 } else {
1102                         error("unable to move logfile tmp-renamed-log to logs/%s: %s",
1103                                 newref, strerror(errno));
1104                         goto rollback;
1105                 }
1106         }
1107         logmoved = log;
1108
1109         lock = lock_ref_sha1_basic(newref, NULL, 0, NULL);
1110         if (!lock) {
1111                 error("unable to lock %s for update", newref);
1112                 goto rollback;
1113         }
1114         lock->force_write = 1;
1115         hashcpy(lock->old_sha1, orig_sha1);
1116         if (write_ref_sha1(lock, orig_sha1, logmsg)) {
1117                 error("unable to write current sha1 into %s", newref);
1118                 goto rollback;
1119         }
1120
1121         return 0;
1122
1123  rollback:
1124         lock = lock_ref_sha1_basic(oldref, NULL, 0, NULL);
1125         if (!lock) {
1126                 error("unable to lock %s for rollback", oldref);
1127                 goto rollbacklog;
1128         }
1129
1130         lock->force_write = 1;
1131         flag = log_all_ref_updates;
1132         log_all_ref_updates = 0;
1133         if (write_ref_sha1(lock, orig_sha1, NULL))
1134                 error("unable to write current sha1 into %s", oldref);
1135         log_all_ref_updates = flag;
1136
1137  rollbacklog:
1138         if (logmoved && rename(git_path("logs/%s", newref), git_path("logs/%s", oldref)))
1139                 error("unable to restore logfile %s from %s: %s",
1140                         oldref, newref, strerror(errno));
1141         if (!logmoved && log &&
1142             rename(git_path("tmp-renamed-log"), git_path("logs/%s", oldref)))
1143                 error("unable to restore logfile %s from tmp-renamed-log: %s",
1144                         oldref, strerror(errno));
1145
1146         return 1;
1147 }
1148
1149 int close_ref(struct ref_lock *lock)
1150 {
1151         if (close_lock_file(lock->lk))
1152                 return -1;
1153         lock->lock_fd = -1;
1154         return 0;
1155 }
1156
1157 int commit_ref(struct ref_lock *lock)
1158 {
1159         if (commit_lock_file(lock->lk))
1160                 return -1;
1161         lock->lock_fd = -1;
1162         return 0;
1163 }
1164
1165 void unlock_ref(struct ref_lock *lock)
1166 {
1167         /* Do not free lock->lk -- atexit() still looks at them */
1168         if (lock->lk)
1169                 rollback_lock_file(lock->lk);
1170         free(lock->ref_name);
1171         free(lock->orig_ref_name);
1172         free(lock);
1173 }
1174
1175 /*
1176  * copy the reflog message msg to buf, which has been allocated sufficiently
1177  * large, while cleaning up the whitespaces.  Especially, convert LF to space,
1178  * because reflog file is one line per entry.
1179  */
1180 static int copy_msg(char *buf, const char *msg)
1181 {
1182         char *cp = buf;
1183         char c;
1184         int wasspace = 1;
1185
1186         *cp++ = '\t';
1187         while ((c = *msg++)) {
1188                 if (wasspace && isspace(c))
1189                         continue;
1190                 wasspace = isspace(c);
1191                 if (wasspace)
1192                         c = ' ';
1193                 *cp++ = c;
1194         }
1195         while (buf < cp && isspace(cp[-1]))
1196                 cp--;
1197         *cp++ = '\n';
1198         return cp - buf;
1199 }
1200
1201 static int log_ref_write(const char *ref_name, const unsigned char *old_sha1,
1202                          const unsigned char *new_sha1, const char *msg)
1203 {
1204         int logfd, written, oflags = O_APPEND | O_WRONLY;
1205         unsigned maxlen, len;
1206         int msglen;
1207         char log_file[PATH_MAX];
1208         char *logrec;
1209         const char *committer;
1210
1211         if (log_all_ref_updates < 0)
1212                 log_all_ref_updates = !is_bare_repository();
1213
1214         git_snpath(log_file, sizeof(log_file), "logs/%s", ref_name);
1215
1216         if (log_all_ref_updates &&
1217             (!prefixcmp(ref_name, "refs/heads/") ||
1218              !prefixcmp(ref_name, "refs/remotes/") ||
1219              !strcmp(ref_name, "HEAD"))) {
1220                 if (safe_create_leading_directories(log_file) < 0)
1221                         return error("unable to create directory for %s",
1222                                      log_file);
1223                 oflags |= O_CREAT;
1224         }
1225
1226         logfd = open(log_file, oflags, 0666);
1227         if (logfd < 0) {
1228                 if (!(oflags & O_CREAT) && errno == ENOENT)
1229                         return 0;
1230
1231                 if ((oflags & O_CREAT) && errno == EISDIR) {
1232                         if (remove_empty_directories(log_file)) {
1233                                 return error("There are still logs under '%s'",
1234                                              log_file);
1235                         }
1236                         logfd = open(log_file, oflags, 0666);
1237                 }
1238
1239                 if (logfd < 0)
1240                         return error("Unable to append to %s: %s",
1241                                      log_file, strerror(errno));
1242         }
1243
1244         adjust_shared_perm(log_file);
1245
1246         msglen = msg ? strlen(msg) : 0;
1247         committer = git_committer_info(0);
1248         maxlen = strlen(committer) + msglen + 100;
1249         logrec = xmalloc(maxlen);
1250         len = sprintf(logrec, "%s %s %s\n",
1251                       sha1_to_hex(old_sha1),
1252                       sha1_to_hex(new_sha1),
1253                       committer);
1254         if (msglen)
1255                 len += copy_msg(logrec + len - 1, msg) - 1;
1256         written = len <= maxlen ? write_in_full(logfd, logrec, len) : -1;
1257         free(logrec);
1258         if (close(logfd) != 0 || written != len)
1259                 return error("Unable to append to %s", log_file);
1260         return 0;
1261 }
1262
1263 static int is_branch(const char *refname)
1264 {
1265         return !strcmp(refname, "HEAD") || !prefixcmp(refname, "refs/heads/");
1266 }
1267
1268 int write_ref_sha1(struct ref_lock *lock,
1269         const unsigned char *sha1, const char *logmsg)
1270 {
1271         static char term = '\n';
1272         struct object *o;
1273
1274         if (!lock)
1275                 return -1;
1276         if (!lock->force_write && !hashcmp(lock->old_sha1, sha1)) {
1277                 unlock_ref(lock);
1278                 return 0;
1279         }
1280         o = parse_object(sha1);
1281         if (!o) {
1282                 error("Trying to write ref %s with nonexistant object %s",
1283                         lock->ref_name, sha1_to_hex(sha1));
1284                 unlock_ref(lock);
1285                 return -1;
1286         }
1287         if (o->type != OBJ_COMMIT && is_branch(lock->ref_name)) {
1288                 error("Trying to write non-commit object %s to branch %s",
1289                         sha1_to_hex(sha1), lock->ref_name);
1290                 unlock_ref(lock);
1291                 return -1;
1292         }
1293         if (write_in_full(lock->lock_fd, sha1_to_hex(sha1), 40) != 40 ||
1294             write_in_full(lock->lock_fd, &term, 1) != 1
1295                 || close_ref(lock) < 0) {
1296                 error("Couldn't write %s", lock->lk->filename);
1297                 unlock_ref(lock);
1298                 return -1;
1299         }
1300         invalidate_cached_refs();
1301         if (log_ref_write(lock->ref_name, lock->old_sha1, sha1, logmsg) < 0 ||
1302             (strcmp(lock->ref_name, lock->orig_ref_name) &&
1303              log_ref_write(lock->orig_ref_name, lock->old_sha1, sha1, logmsg) < 0)) {
1304                 unlock_ref(lock);
1305                 return -1;
1306         }
1307         if (strcmp(lock->orig_ref_name, "HEAD") != 0) {
1308                 /*
1309                  * Special hack: If a branch is updated directly and HEAD
1310                  * points to it (may happen on the remote side of a push
1311                  * for example) then logically the HEAD reflog should be
1312                  * updated too.
1313                  * A generic solution implies reverse symref information,
1314                  * but finding all symrefs pointing to the given branch
1315                  * would be rather costly for this rare event (the direct
1316                  * update of a branch) to be worth it.  So let's cheat and
1317                  * check with HEAD only which should cover 99% of all usage
1318                  * scenarios (even 100% of the default ones).
1319                  */
1320                 unsigned char head_sha1[20];
1321                 int head_flag;
1322                 const char *head_ref;
1323                 head_ref = resolve_ref("HEAD", head_sha1, 1, &head_flag);
1324                 if (head_ref && (head_flag & REF_ISSYMREF) &&
1325                     !strcmp(head_ref, lock->ref_name))
1326                         log_ref_write("HEAD", lock->old_sha1, sha1, logmsg);
1327         }
1328         if (commit_ref(lock)) {
1329                 error("Couldn't set %s", lock->ref_name);
1330                 unlock_ref(lock);
1331                 return -1;
1332         }
1333         unlock_ref(lock);
1334         return 0;
1335 }
1336
1337 int create_symref(const char *ref_target, const char *refs_heads_master,
1338                   const char *logmsg)
1339 {
1340         const char *lockpath;
1341         char ref[1000];
1342         int fd, len, written;
1343         char *git_HEAD = git_pathdup("%s", ref_target);
1344         unsigned char old_sha1[20], new_sha1[20];
1345
1346         if (logmsg && read_ref(ref_target, old_sha1))
1347                 hashclr(old_sha1);
1348
1349         if (safe_create_leading_directories(git_HEAD) < 0)
1350                 return error("unable to create directory for %s", git_HEAD);
1351
1352 #ifndef NO_SYMLINK_HEAD
1353         if (prefer_symlink_refs) {
1354                 unlink(git_HEAD);
1355                 if (!symlink(refs_heads_master, git_HEAD))
1356                         goto done;
1357                 fprintf(stderr, "no symlink - falling back to symbolic ref\n");
1358         }
1359 #endif
1360
1361         len = snprintf(ref, sizeof(ref), "ref: %s\n", refs_heads_master);
1362         if (sizeof(ref) <= len) {
1363                 error("refname too long: %s", refs_heads_master);
1364                 goto error_free_return;
1365         }
1366         lockpath = mkpath("%s.lock", git_HEAD);
1367         fd = open(lockpath, O_CREAT | O_EXCL | O_WRONLY, 0666);
1368         if (fd < 0) {
1369                 error("Unable to open %s for writing", lockpath);
1370                 goto error_free_return;
1371         }
1372         written = write_in_full(fd, ref, len);
1373         if (close(fd) != 0 || written != len) {
1374                 error("Unable to write to %s", lockpath);
1375                 goto error_unlink_return;
1376         }
1377         if (rename(lockpath, git_HEAD) < 0) {
1378                 error("Unable to create %s", git_HEAD);
1379                 goto error_unlink_return;
1380         }
1381         if (adjust_shared_perm(git_HEAD)) {
1382                 error("Unable to fix permissions on %s", lockpath);
1383         error_unlink_return:
1384                 unlink(lockpath);
1385         error_free_return:
1386                 free(git_HEAD);
1387                 return -1;
1388         }
1389
1390 #ifndef NO_SYMLINK_HEAD
1391         done:
1392 #endif
1393         if (logmsg && !read_ref(refs_heads_master, new_sha1))
1394                 log_ref_write(ref_target, old_sha1, new_sha1, logmsg);
1395
1396         free(git_HEAD);
1397         return 0;
1398 }
1399
1400 static char *ref_msg(const char *line, const char *endp)
1401 {
1402         const char *ep;
1403         line += 82;
1404         ep = memchr(line, '\n', endp - line);
1405         if (!ep)
1406                 ep = endp;
1407         return xmemdupz(line, ep - line);
1408 }
1409
1410 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)
1411 {
1412         const char *logfile, *logdata, *logend, *rec, *lastgt, *lastrec;
1413         char *tz_c;
1414         int logfd, tz, reccnt = 0;
1415         struct stat st;
1416         unsigned long date;
1417         unsigned char logged_sha1[20];
1418         void *log_mapped;
1419         size_t mapsz;
1420
1421         logfile = git_path("logs/%s", ref);
1422         logfd = open(logfile, O_RDONLY, 0);
1423         if (logfd < 0)
1424                 die("Unable to read log %s: %s", logfile, strerror(errno));
1425         fstat(logfd, &st);
1426         if (!st.st_size)
1427                 die("Log %s is empty.", logfile);
1428         mapsz = xsize_t(st.st_size);
1429         log_mapped = xmmap(NULL, mapsz, PROT_READ, MAP_PRIVATE, logfd, 0);
1430         logdata = log_mapped;
1431         close(logfd);
1432
1433         lastrec = NULL;
1434         rec = logend = logdata + st.st_size;
1435         while (logdata < rec) {
1436                 reccnt++;
1437                 if (logdata < rec && *(rec-1) == '\n')
1438                         rec--;
1439                 lastgt = NULL;
1440                 while (logdata < rec && *(rec-1) != '\n') {
1441                         rec--;
1442                         if (*rec == '>')
1443                                 lastgt = rec;
1444                 }
1445                 if (!lastgt)
1446                         die("Log %s is corrupt.", logfile);
1447                 date = strtoul(lastgt + 1, &tz_c, 10);
1448                 if (date <= at_time || cnt == 0) {
1449                         tz = strtoul(tz_c, NULL, 10);
1450                         if (msg)
1451                                 *msg = ref_msg(rec, logend);
1452                         if (cutoff_time)
1453                                 *cutoff_time = date;
1454                         if (cutoff_tz)
1455                                 *cutoff_tz = tz;
1456                         if (cutoff_cnt)
1457                                 *cutoff_cnt = reccnt - 1;
1458                         if (lastrec) {
1459                                 if (get_sha1_hex(lastrec, logged_sha1))
1460                                         die("Log %s is corrupt.", logfile);
1461                                 if (get_sha1_hex(rec + 41, sha1))
1462                                         die("Log %s is corrupt.", logfile);
1463                                 if (hashcmp(logged_sha1, sha1)) {
1464                                         warning("Log %s has gap after %s.",
1465                                                 logfile, show_date(date, tz, DATE_RFC2822));
1466                                 }
1467                         }
1468                         else if (date == at_time) {
1469                                 if (get_sha1_hex(rec + 41, sha1))
1470                                         die("Log %s is corrupt.", logfile);
1471                         }
1472                         else {
1473                                 if (get_sha1_hex(rec + 41, logged_sha1))
1474                                         die("Log %s is corrupt.", logfile);
1475                                 if (hashcmp(logged_sha1, sha1)) {
1476                                         warning("Log %s unexpectedly ended on %s.",
1477                                                 logfile, show_date(date, tz, DATE_RFC2822));
1478                                 }
1479                         }
1480                         munmap(log_mapped, mapsz);
1481                         return 0;
1482                 }
1483                 lastrec = rec;
1484                 if (cnt > 0)
1485                         cnt--;
1486         }
1487
1488         rec = logdata;
1489         while (rec < logend && *rec != '>' && *rec != '\n')
1490                 rec++;
1491         if (rec == logend || *rec == '\n')
1492                 die("Log %s is corrupt.", logfile);
1493         date = strtoul(rec + 1, &tz_c, 10);
1494         tz = strtoul(tz_c, NULL, 10);
1495         if (get_sha1_hex(logdata, sha1))
1496                 die("Log %s is corrupt.", logfile);
1497         if (is_null_sha1(sha1)) {
1498                 if (get_sha1_hex(logdata + 41, sha1))
1499                         die("Log %s is corrupt.", logfile);
1500         }
1501         if (msg)
1502                 *msg = ref_msg(logdata, logend);
1503         munmap(log_mapped, mapsz);
1504
1505         if (cutoff_time)
1506                 *cutoff_time = date;
1507         if (cutoff_tz)
1508                 *cutoff_tz = tz;
1509         if (cutoff_cnt)
1510                 *cutoff_cnt = reccnt;
1511         return 1;
1512 }
1513
1514 int for_each_recent_reflog_ent(const char *ref, each_reflog_ent_fn fn, long ofs, void *cb_data)
1515 {
1516         const char *logfile;
1517         FILE *logfp;
1518         char buf[1024];
1519         int ret = 0;
1520
1521         logfile = git_path("logs/%s", ref);
1522         logfp = fopen(logfile, "r");
1523         if (!logfp)
1524                 return -1;
1525
1526         if (ofs) {
1527                 struct stat statbuf;
1528                 if (fstat(fileno(logfp), &statbuf) ||
1529                     statbuf.st_size < ofs ||
1530                     fseek(logfp, -ofs, SEEK_END) ||
1531                     fgets(buf, sizeof(buf), logfp))
1532                         return -1;
1533         }
1534
1535         while (fgets(buf, sizeof(buf), logfp)) {
1536                 unsigned char osha1[20], nsha1[20];
1537                 char *email_end, *message;
1538                 unsigned long timestamp;
1539                 int len, tz;
1540
1541                 /* old SP new SP name <email> SP time TAB msg LF */
1542                 len = strlen(buf);
1543                 if (len < 83 || buf[len-1] != '\n' ||
1544                     get_sha1_hex(buf, osha1) || buf[40] != ' ' ||
1545                     get_sha1_hex(buf + 41, nsha1) || buf[81] != ' ' ||
1546                     !(email_end = strchr(buf + 82, '>')) ||
1547                     email_end[1] != ' ' ||
1548                     !(timestamp = strtoul(email_end + 2, &message, 10)) ||
1549                     !message || message[0] != ' ' ||
1550                     (message[1] != '+' && message[1] != '-') ||
1551                     !isdigit(message[2]) || !isdigit(message[3]) ||
1552                     !isdigit(message[4]) || !isdigit(message[5]))
1553                         continue; /* corrupt? */
1554                 email_end[1] = '\0';
1555                 tz = strtol(message + 1, NULL, 10);
1556                 if (message[6] != '\t')
1557                         message += 6;
1558                 else
1559                         message += 7;
1560                 ret = fn(osha1, nsha1, buf+82, timestamp, tz, message, cb_data);
1561                 if (ret)
1562                         break;
1563         }
1564         fclose(logfp);
1565         return ret;
1566 }
1567
1568 int for_each_reflog_ent(const char *ref, each_reflog_ent_fn fn, void *cb_data)
1569 {
1570         return for_each_recent_reflog_ent(ref, fn, 0, cb_data);
1571 }
1572
1573 static int do_for_each_reflog(const char *base, each_ref_fn fn, void *cb_data)
1574 {
1575         DIR *dir = opendir(git_path("logs/%s", base));
1576         int retval = 0;
1577
1578         if (dir) {
1579                 struct dirent *de;
1580                 int baselen = strlen(base);
1581                 char *log = xmalloc(baselen + 257);
1582
1583                 memcpy(log, base, baselen);
1584                 if (baselen && base[baselen-1] != '/')
1585                         log[baselen++] = '/';
1586
1587                 while ((de = readdir(dir)) != NULL) {
1588                         struct stat st;
1589                         int namelen;
1590
1591                         if (de->d_name[0] == '.')
1592                                 continue;
1593                         namelen = strlen(de->d_name);
1594                         if (namelen > 255)
1595                                 continue;
1596                         if (has_extension(de->d_name, ".lock"))
1597                                 continue;
1598                         memcpy(log + baselen, de->d_name, namelen+1);
1599                         if (stat(git_path("logs/%s", log), &st) < 0)
1600                                 continue;
1601                         if (S_ISDIR(st.st_mode)) {
1602                                 retval = do_for_each_reflog(log, fn, cb_data);
1603                         } else {
1604                                 unsigned char sha1[20];
1605                                 if (!resolve_ref(log, sha1, 0, NULL))
1606                                         retval = error("bad ref for %s", log);
1607                                 else
1608                                         retval = fn(log, sha1, 0, cb_data);
1609                         }
1610                         if (retval)
1611                                 break;
1612                 }
1613                 free(log);
1614                 closedir(dir);
1615         }
1616         else if (*base)
1617                 return errno;
1618         return retval;
1619 }
1620
1621 int for_each_reflog(each_ref_fn fn, void *cb_data)
1622 {
1623         return do_for_each_reflog("", fn, cb_data);
1624 }
1625
1626 int update_ref(const char *action, const char *refname,
1627                 const unsigned char *sha1, const unsigned char *oldval,
1628                 int flags, enum action_on_err onerr)
1629 {
1630         static struct ref_lock *lock;
1631         lock = lock_any_ref_for_update(refname, oldval, flags);
1632         if (!lock) {
1633                 const char *str = "Cannot lock the ref '%s'.";
1634                 switch (onerr) {
1635                 case MSG_ON_ERR: error(str, refname); break;
1636                 case DIE_ON_ERR: die(str, refname); break;
1637                 case QUIET_ON_ERR: break;
1638                 }
1639                 return 1;
1640         }
1641         if (write_ref_sha1(lock, sha1, action) < 0) {
1642                 const char *str = "Cannot update the ref '%s'.";
1643                 switch (onerr) {
1644                 case MSG_ON_ERR: error(str, refname); break;
1645                 case DIE_ON_ERR: die(str, refname); break;
1646                 case QUIET_ON_ERR: break;
1647                 }
1648                 return 1;
1649         }
1650         return 0;
1651 }
1652
1653 struct ref *find_ref_by_name(const struct ref *list, const char *name)
1654 {
1655         for ( ; list; list = list->next)
1656                 if (!strcmp(list->name, name))
1657                         return (struct ref *)list;
1658         return NULL;
1659 }
1660
1661 /*
1662  * generate a format suitable for scanf from a ref_rev_parse_rules
1663  * rule, that is replace the "%.*s" spec with a "%s" spec
1664  */
1665 static void gen_scanf_fmt(char *scanf_fmt, const char *rule)
1666 {
1667         char *spec;
1668
1669         spec = strstr(rule, "%.*s");
1670         if (!spec || strstr(spec + 4, "%.*s"))
1671                 die("invalid rule in ref_rev_parse_rules: %s", rule);
1672
1673         /* copy all until spec */
1674         strncpy(scanf_fmt, rule, spec - rule);
1675         scanf_fmt[spec - rule] = '\0';
1676         /* copy new spec */
1677         strcat(scanf_fmt, "%s");
1678         /* copy remaining rule */
1679         strcat(scanf_fmt, spec + 4);
1680
1681         return;
1682 }
1683
1684 char *shorten_unambiguous_ref(const char *ref)
1685 {
1686         int i;
1687         static char **scanf_fmts;
1688         static int nr_rules;
1689         char *short_name;
1690
1691         /* pre generate scanf formats from ref_rev_parse_rules[] */
1692         if (!nr_rules) {
1693                 size_t total_len = 0;
1694
1695                 /* the rule list is NULL terminated, count them first */
1696                 for (; ref_rev_parse_rules[nr_rules]; nr_rules++)
1697                         /* no +1 because strlen("%s") < strlen("%.*s") */
1698                         total_len += strlen(ref_rev_parse_rules[nr_rules]);
1699
1700                 scanf_fmts = xmalloc(nr_rules * sizeof(char *) + total_len);
1701
1702                 total_len = 0;
1703                 for (i = 0; i < nr_rules; i++) {
1704                         scanf_fmts[i] = (char *)&scanf_fmts[nr_rules]
1705                                         + total_len;
1706                         gen_scanf_fmt(scanf_fmts[i], ref_rev_parse_rules[i]);
1707                         total_len += strlen(ref_rev_parse_rules[i]);
1708                 }
1709         }
1710
1711         /* bail out if there are no rules */
1712         if (!nr_rules)
1713                 return xstrdup(ref);
1714
1715         /* buffer for scanf result, at most ref must fit */
1716         short_name = xstrdup(ref);
1717
1718         /* skip first rule, it will always match */
1719         for (i = nr_rules - 1; i > 0 ; --i) {
1720                 int j;
1721                 int short_name_len;
1722
1723                 if (1 != sscanf(ref, scanf_fmts[i], short_name))
1724                         continue;
1725
1726                 short_name_len = strlen(short_name);
1727
1728                 /*
1729                  * check if the short name resolves to a valid ref,
1730                  * but use only rules prior to the matched one
1731                  */
1732                 for (j = 0; j < i; j++) {
1733                         const char *rule = ref_rev_parse_rules[j];
1734                         unsigned char short_objectname[20];
1735                         char refname[PATH_MAX];
1736
1737                         /*
1738                          * the short name is ambiguous, if it resolves
1739                          * (with this previous rule) to a valid ref
1740                          * read_ref() returns 0 on success
1741                          */
1742                         mksnpath(refname, sizeof(refname),
1743                                  rule, short_name_len, short_name);
1744                         if (!read_ref(refname, short_objectname))
1745                                 break;
1746                 }
1747
1748                 /*
1749                  * short name is non-ambiguous if all previous rules
1750                  * haven't resolved to a valid ref
1751                  */
1752                 if (j == i)
1753                         return short_name;
1754         }
1755
1756         free(short_name);
1757         return xstrdup(ref);
1758 }