Merge branch 'maint-1.7.1' into maint-1.7.2
[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 #define REF_BROKEN 010
10
11 struct ref_list {
12         struct ref_list *next;
13         unsigned char flag; /* ISSYMREF? ISPACKED? */
14         unsigned char sha1[20];
15         unsigned char peeled[20];
16         char name[FLEX_ARRAY];
17 };
18
19 static const char *parse_ref_line(char *line, unsigned char *sha1)
20 {
21         /*
22          * 42: the answer to everything.
23          *
24          * In this case, it happens to be the answer to
25          *  40 (length of sha1 hex representation)
26          *  +1 (space in between hex and name)
27          *  +1 (newline at the end of the line)
28          */
29         int len = strlen(line) - 42;
30
31         if (len <= 0)
32                 return NULL;
33         if (get_sha1_hex(line, sha1) < 0)
34                 return NULL;
35         if (!isspace(line[40]))
36                 return NULL;
37         line += 41;
38         if (isspace(*line))
39                 return NULL;
40         if (line[len] != '\n')
41                 return NULL;
42         line[len] = 0;
43
44         return line;
45 }
46
47 static struct ref_list *add_ref(const char *name, const unsigned char *sha1,
48                                 int flag, struct ref_list *list,
49                                 struct ref_list **new_entry)
50 {
51         int len;
52         struct ref_list *entry;
53
54         /* Allocate it and add it in.. */
55         len = strlen(name) + 1;
56         entry = xmalloc(sizeof(struct ref_list) + len);
57         hashcpy(entry->sha1, sha1);
58         hashclr(entry->peeled);
59         memcpy(entry->name, name, len);
60         entry->flag = flag;
61         entry->next = list;
62         if (new_entry)
63                 *new_entry = entry;
64         return entry;
65 }
66
67 /* merge sort the ref list */
68 static struct ref_list *sort_ref_list(struct ref_list *list)
69 {
70         int psize, qsize, last_merge_count, cmp;
71         struct ref_list *p, *q, *l, *e;
72         struct ref_list *new_list = list;
73         int k = 1;
74         int merge_count = 0;
75
76         if (!list)
77                 return list;
78
79         do {
80                 last_merge_count = merge_count;
81                 merge_count = 0;
82
83                 psize = 0;
84
85                 p = new_list;
86                 q = new_list;
87                 new_list = NULL;
88                 l = NULL;
89
90                 while (p) {
91                         merge_count++;
92
93                         while (psize < k && q->next) {
94                                 q = q->next;
95                                 psize++;
96                         }
97                         qsize = k;
98
99                         while ((psize > 0) || (qsize > 0 && q)) {
100                                 if (qsize == 0 || !q) {
101                                         e = p;
102                                         p = p->next;
103                                         psize--;
104                                 } else if (psize == 0) {
105                                         e = q;
106                                         q = q->next;
107                                         qsize--;
108                                 } else {
109                                         cmp = strcmp(q->name, p->name);
110                                         if (cmp < 0) {
111                                                 e = q;
112                                                 q = q->next;
113                                                 qsize--;
114                                         } else if (cmp > 0) {
115                                                 e = p;
116                                                 p = p->next;
117                                                 psize--;
118                                         } else {
119                                                 if (hashcmp(q->sha1, p->sha1))
120                                                         die("Duplicated ref, and SHA1s don't match: %s",
121                                                             q->name);
122                                                 warning("Duplicated ref: %s", q->name);
123                                                 e = q;
124                                                 q = q->next;
125                                                 qsize--;
126                                                 free(e);
127                                                 e = p;
128                                                 p = p->next;
129                                                 psize--;
130                                         }
131                                 }
132
133                                 e->next = NULL;
134
135                                 if (l)
136                                         l->next = e;
137                                 if (!new_list)
138                                         new_list = e;
139                                 l = e;
140                         }
141
142                         p = q;
143                 };
144
145                 k = k * 2;
146         } while ((last_merge_count != merge_count) || (last_merge_count != 1));
147
148         return new_list;
149 }
150
151 /*
152  * Future: need to be in "struct repository"
153  * when doing a full libification.
154  */
155 static struct cached_refs {
156         char did_loose;
157         char did_packed;
158         struct ref_list *loose;
159         struct ref_list *packed;
160 } cached_refs;
161 static struct ref_list *current_ref;
162
163 static struct ref_list *extra_refs;
164
165 static void free_ref_list(struct ref_list *list)
166 {
167         struct ref_list *next;
168         for ( ; list; list = next) {
169                 next = list->next;
170                 free(list);
171         }
172 }
173
174 static void invalidate_cached_refs(void)
175 {
176         struct cached_refs *ca = &cached_refs;
177
178         if (ca->did_loose && ca->loose)
179                 free_ref_list(ca->loose);
180         if (ca->did_packed && ca->packed)
181                 free_ref_list(ca->packed);
182         ca->loose = ca->packed = NULL;
183         ca->did_loose = ca->did_packed = 0;
184 }
185
186 static void read_packed_refs(FILE *f, struct cached_refs *cached_refs)
187 {
188         struct ref_list *list = NULL;
189         struct ref_list *last = NULL;
190         char refline[PATH_MAX];
191         int flag = REF_ISPACKED;
192
193         while (fgets(refline, sizeof(refline), f)) {
194                 unsigned char sha1[20];
195                 const char *name;
196                 static const char header[] = "# pack-refs with:";
197
198                 if (!strncmp(refline, header, sizeof(header)-1)) {
199                         const char *traits = refline + sizeof(header) - 1;
200                         if (strstr(traits, " peeled "))
201                                 flag |= REF_KNOWS_PEELED;
202                         /* perhaps other traits later as well */
203                         continue;
204                 }
205
206                 name = parse_ref_line(refline, sha1);
207                 if (name) {
208                         list = add_ref(name, sha1, flag, list, &last);
209                         continue;
210                 }
211                 if (last &&
212                     refline[0] == '^' &&
213                     strlen(refline) == 42 &&
214                     refline[41] == '\n' &&
215                     !get_sha1_hex(refline + 1, sha1))
216                         hashcpy(last->peeled, sha1);
217         }
218         cached_refs->packed = sort_ref_list(list);
219 }
220
221 void add_extra_ref(const char *name, const unsigned char *sha1, int flag)
222 {
223         extra_refs = add_ref(name, sha1, flag, extra_refs, NULL);
224 }
225
226 void clear_extra_refs(void)
227 {
228         free_ref_list(extra_refs);
229         extra_refs = NULL;
230 }
231
232 static struct ref_list *get_packed_refs(void)
233 {
234         if (!cached_refs.did_packed) {
235                 FILE *f = fopen(git_path("packed-refs"), "r");
236                 cached_refs.packed = NULL;
237                 if (f) {
238                         read_packed_refs(f, &cached_refs);
239                         fclose(f);
240                 }
241                 cached_refs.did_packed = 1;
242         }
243         return cached_refs.packed;
244 }
245
246 static struct ref_list *get_ref_dir(const char *base, struct ref_list *list)
247 {
248         DIR *dir = opendir(git_path("%s", base));
249
250         if (dir) {
251                 struct dirent *de;
252                 int baselen = strlen(base);
253                 char *ref = xmalloc(baselen + 257);
254
255                 memcpy(ref, base, baselen);
256                 if (baselen && base[baselen-1] != '/')
257                         ref[baselen++] = '/';
258
259                 while ((de = readdir(dir)) != NULL) {
260                         unsigned char sha1[20];
261                         struct stat st;
262                         int flag;
263                         int namelen;
264
265                         if (de->d_name[0] == '.')
266                                 continue;
267                         namelen = strlen(de->d_name);
268                         if (namelen > 255)
269                                 continue;
270                         if (has_extension(de->d_name, ".lock"))
271                                 continue;
272                         memcpy(ref + baselen, de->d_name, namelen+1);
273                         if (stat(git_path("%s", ref), &st) < 0)
274                                 continue;
275                         if (S_ISDIR(st.st_mode)) {
276                                 list = get_ref_dir(ref, list);
277                                 continue;
278                         }
279                         if (!resolve_ref(ref, sha1, 1, &flag)) {
280                                 hashclr(sha1);
281                                 flag |= REF_BROKEN;
282                         }
283                         list = add_ref(ref, sha1, flag, list, NULL);
284                 }
285                 free(ref);
286                 closedir(dir);
287         }
288         return sort_ref_list(list);
289 }
290
291 struct warn_if_dangling_data {
292         FILE *fp;
293         const char *refname;
294         const char *msg_fmt;
295 };
296
297 static int warn_if_dangling_symref(const char *refname, const unsigned char *sha1,
298                                    int flags, void *cb_data)
299 {
300         struct warn_if_dangling_data *d = cb_data;
301         const char *resolves_to;
302         unsigned char junk[20];
303
304         if (!(flags & REF_ISSYMREF))
305                 return 0;
306
307         resolves_to = resolve_ref(refname, junk, 0, NULL);
308         if (!resolves_to || strcmp(resolves_to, d->refname))
309                 return 0;
310
311         fprintf(d->fp, d->msg_fmt, refname);
312         return 0;
313 }
314
315 void warn_dangling_symref(FILE *fp, const char *msg_fmt, const char *refname)
316 {
317         struct warn_if_dangling_data data;
318
319         data.fp = fp;
320         data.refname = refname;
321         data.msg_fmt = msg_fmt;
322         for_each_rawref(warn_if_dangling_symref, &data);
323 }
324
325 static struct ref_list *get_loose_refs(void)
326 {
327         if (!cached_refs.did_loose) {
328                 cached_refs.loose = get_ref_dir("refs", NULL);
329                 cached_refs.did_loose = 1;
330         }
331         return cached_refs.loose;
332 }
333
334 /* We allow "recursive" symbolic refs. Only within reason, though */
335 #define MAXDEPTH 5
336 #define MAXREFLEN (1024)
337
338 static int resolve_gitlink_packed_ref(char *name, int pathlen, const char *refname, unsigned char *result)
339 {
340         FILE *f;
341         struct cached_refs refs;
342         struct ref_list *ref;
343         int retval;
344
345         strcpy(name + pathlen, "packed-refs");
346         f = fopen(name, "r");
347         if (!f)
348                 return -1;
349         read_packed_refs(f, &refs);
350         fclose(f);
351         ref = refs.packed;
352         retval = -1;
353         while (ref) {
354                 if (!strcmp(ref->name, refname)) {
355                         retval = 0;
356                         memcpy(result, ref->sha1, 20);
357                         break;
358                 }
359                 ref = ref->next;
360         }
361         free_ref_list(refs.packed);
362         return retval;
363 }
364
365 static int resolve_gitlink_ref_recursive(char *name, int pathlen, const char *refname, unsigned char *result, int recursion)
366 {
367         int fd, len = strlen(refname);
368         char buffer[128], *p;
369
370         if (recursion > MAXDEPTH || len > MAXREFLEN)
371                 return -1;
372         memcpy(name + pathlen, refname, len+1);
373         fd = open(name, O_RDONLY);
374         if (fd < 0)
375                 return resolve_gitlink_packed_ref(name, pathlen, refname, result);
376
377         len = read(fd, buffer, sizeof(buffer)-1);
378         close(fd);
379         if (len < 0)
380                 return -1;
381         while (len && isspace(buffer[len-1]))
382                 len--;
383         buffer[len] = 0;
384
385         /* Was it a detached head or an old-fashioned symlink? */
386         if (!get_sha1_hex(buffer, result))
387                 return 0;
388
389         /* Symref? */
390         if (strncmp(buffer, "ref:", 4))
391                 return -1;
392         p = buffer + 4;
393         while (isspace(*p))
394                 p++;
395
396         return resolve_gitlink_ref_recursive(name, pathlen, p, result, recursion+1);
397 }
398
399 int resolve_gitlink_ref(const char *path, const char *refname, unsigned char *result)
400 {
401         int len = strlen(path), retval;
402         char *gitdir;
403         const char *tmp;
404
405         while (len && path[len-1] == '/')
406                 len--;
407         if (!len)
408                 return -1;
409         gitdir = xmalloc(len + MAXREFLEN + 8);
410         memcpy(gitdir, path, len);
411         memcpy(gitdir + len, "/.git", 6);
412         len += 5;
413
414         tmp = read_gitfile_gently(gitdir);
415         if (tmp) {
416                 free(gitdir);
417                 len = strlen(tmp);
418                 gitdir = xmalloc(len + MAXREFLEN + 3);
419                 memcpy(gitdir, tmp, len);
420         }
421         gitdir[len] = '/';
422         gitdir[++len] = '\0';
423         retval = resolve_gitlink_ref_recursive(gitdir, len, refname, result, 0);
424         free(gitdir);
425         return retval;
426 }
427
428 /*
429  * If the "reading" argument is set, this function finds out what _object_
430  * the ref points at by "reading" the ref.  The ref, if it is not symbolic,
431  * has to exist, and if it is symbolic, it has to point at an existing ref,
432  * because the "read" goes through the symref to the ref it points at.
433  *
434  * The access that is not "reading" may often be "writing", but does not
435  * have to; it can be merely checking _where it leads to_. If it is a
436  * prelude to "writing" to the ref, a write to a symref that points at
437  * yet-to-be-born ref will create the real ref pointed by the symref.
438  * reading=0 allows the caller to check where such a symref leads to.
439  */
440 const char *resolve_ref(const char *ref, unsigned char *sha1, int reading, int *flag)
441 {
442         int depth = MAXDEPTH;
443         ssize_t len;
444         char buffer[256];
445         static char ref_buffer[256];
446
447         if (flag)
448                 *flag = 0;
449
450         for (;;) {
451                 char path[PATH_MAX];
452                 struct stat st;
453                 char *buf;
454                 int fd;
455
456                 if (--depth < 0)
457                         return NULL;
458
459                 git_snpath(path, sizeof(path), "%s", ref);
460                 /* Special case: non-existing file. */
461                 if (lstat(path, &st) < 0) {
462                         struct ref_list *list = get_packed_refs();
463                         while (list) {
464                                 if (!strcmp(ref, list->name)) {
465                                         hashcpy(sha1, list->sha1);
466                                         if (flag)
467                                                 *flag |= REF_ISPACKED;
468                                         return ref;
469                                 }
470                                 list = list->next;
471                         }
472                         if (reading || errno != ENOENT)
473                                 return NULL;
474                         hashclr(sha1);
475                         return ref;
476                 }
477
478                 /* Follow "normalized" - ie "refs/.." symlinks by hand */
479                 if (S_ISLNK(st.st_mode)) {
480                         len = readlink(path, buffer, sizeof(buffer)-1);
481                         if (len >= 5 && !memcmp("refs/", buffer, 5)) {
482                                 buffer[len] = 0;
483                                 strcpy(ref_buffer, buffer);
484                                 ref = ref_buffer;
485                                 if (flag)
486                                         *flag |= REF_ISSYMREF;
487                                 continue;
488                         }
489                 }
490
491                 /* Is it a directory? */
492                 if (S_ISDIR(st.st_mode)) {
493                         errno = EISDIR;
494                         return NULL;
495                 }
496
497                 /*
498                  * Anything else, just open it and try to use it as
499                  * a ref
500                  */
501                 fd = open(path, O_RDONLY);
502                 if (fd < 0)
503                         return NULL;
504                 len = read_in_full(fd, buffer, sizeof(buffer)-1);
505                 close(fd);
506
507                 /*
508                  * Is it a symbolic ref?
509                  */
510                 if (len < 4 || memcmp("ref:", buffer, 4))
511                         break;
512                 buf = buffer + 4;
513                 len -= 4;
514                 while (len && isspace(*buf))
515                         buf++, len--;
516                 while (len && isspace(buf[len-1]))
517                         len--;
518                 buf[len] = 0;
519                 memcpy(ref_buffer, buf, len + 1);
520                 ref = ref_buffer;
521                 if (flag)
522                         *flag |= REF_ISSYMREF;
523         }
524         if (len < 40 || get_sha1_hex(buffer, sha1))
525                 return NULL;
526         return ref;
527 }
528
529 /* The argument to filter_refs */
530 struct ref_filter {
531         const char *pattern;
532         each_ref_fn *fn;
533         void *cb_data;
534 };
535
536 int read_ref(const char *ref, unsigned char *sha1)
537 {
538         if (resolve_ref(ref, sha1, 1, NULL))
539                 return 0;
540         return -1;
541 }
542
543 #define DO_FOR_EACH_INCLUDE_BROKEN 01
544 static int do_one_ref(const char *base, each_ref_fn fn, int trim,
545                       int flags, void *cb_data, struct ref_list *entry)
546 {
547         if (strncmp(base, entry->name, trim))
548                 return 0;
549
550         if (!(flags & DO_FOR_EACH_INCLUDE_BROKEN)) {
551                 if (entry->flag & REF_BROKEN)
552                         return 0; /* ignore dangling symref */
553                 if (!has_sha1_file(entry->sha1)) {
554                         error("%s does not point to a valid object!", entry->name);
555                         return 0;
556                 }
557         }
558         current_ref = entry;
559         return fn(entry->name + trim, entry->sha1, entry->flag, cb_data);
560 }
561
562 static int filter_refs(const char *ref, const unsigned char *sha, int flags,
563         void *data)
564 {
565         struct ref_filter *filter = (struct ref_filter *)data;
566         if (fnmatch(filter->pattern, ref, 0))
567                 return 0;
568         return filter->fn(ref, sha, flags, filter->cb_data);
569 }
570
571 int peel_ref(const char *ref, unsigned char *sha1)
572 {
573         int flag;
574         unsigned char base[20];
575         struct object *o;
576
577         if (current_ref && (current_ref->name == ref
578                 || !strcmp(current_ref->name, ref))) {
579                 if (current_ref->flag & REF_KNOWS_PEELED) {
580                         hashcpy(sha1, current_ref->peeled);
581                         return 0;
582                 }
583                 hashcpy(base, current_ref->sha1);
584                 goto fallback;
585         }
586
587         if (!resolve_ref(ref, base, 1, &flag))
588                 return -1;
589
590         if ((flag & REF_ISPACKED)) {
591                 struct ref_list *list = get_packed_refs();
592
593                 while (list) {
594                         if (!strcmp(list->name, ref)) {
595                                 if (list->flag & REF_KNOWS_PEELED) {
596                                         hashcpy(sha1, list->peeled);
597                                         return 0;
598                                 }
599                                 /* older pack-refs did not leave peeled ones */
600                                 break;
601                         }
602                         list = list->next;
603                 }
604         }
605
606 fallback:
607         o = parse_object(base);
608         if (o && o->type == OBJ_TAG) {
609                 o = deref_tag(o, ref, 0);
610                 if (o) {
611                         hashcpy(sha1, o->sha1);
612                         return 0;
613                 }
614         }
615         return -1;
616 }
617
618 static int do_for_each_ref(const char *base, each_ref_fn fn, int trim,
619                            int flags, void *cb_data)
620 {
621         int retval = 0;
622         struct ref_list *packed = get_packed_refs();
623         struct ref_list *loose = get_loose_refs();
624
625         struct ref_list *extra;
626
627         for (extra = extra_refs; extra; extra = extra->next)
628                 retval = do_one_ref(base, fn, trim, flags, cb_data, extra);
629
630         while (packed && loose) {
631                 struct ref_list *entry;
632                 int cmp = strcmp(packed->name, loose->name);
633                 if (!cmp) {
634                         packed = packed->next;
635                         continue;
636                 }
637                 if (cmp > 0) {
638                         entry = loose;
639                         loose = loose->next;
640                 } else {
641                         entry = packed;
642                         packed = packed->next;
643                 }
644                 retval = do_one_ref(base, fn, trim, flags, cb_data, entry);
645                 if (retval)
646                         goto end_each;
647         }
648
649         for (packed = packed ? packed : loose; packed; packed = packed->next) {
650                 retval = do_one_ref(base, fn, trim, flags, cb_data, packed);
651                 if (retval)
652                         goto end_each;
653         }
654
655 end_each:
656         current_ref = NULL;
657         return retval;
658 }
659
660 int head_ref(each_ref_fn fn, void *cb_data)
661 {
662         unsigned char sha1[20];
663         int flag;
664
665         if (resolve_ref("HEAD", sha1, 1, &flag))
666                 return fn("HEAD", sha1, flag, cb_data);
667         return 0;
668 }
669
670 int for_each_ref(each_ref_fn fn, void *cb_data)
671 {
672         return do_for_each_ref("refs/", fn, 0, 0, cb_data);
673 }
674
675 int for_each_ref_in(const char *prefix, each_ref_fn fn, void *cb_data)
676 {
677         return do_for_each_ref(prefix, fn, strlen(prefix), 0, cb_data);
678 }
679
680 int for_each_tag_ref(each_ref_fn fn, void *cb_data)
681 {
682         return for_each_ref_in("refs/tags/", fn, cb_data);
683 }
684
685 int for_each_branch_ref(each_ref_fn fn, void *cb_data)
686 {
687         return for_each_ref_in("refs/heads/", fn, cb_data);
688 }
689
690 int for_each_remote_ref(each_ref_fn fn, void *cb_data)
691 {
692         return for_each_ref_in("refs/remotes/", fn, cb_data);
693 }
694
695 int for_each_replace_ref(each_ref_fn fn, void *cb_data)
696 {
697         return do_for_each_ref("refs/replace/", fn, 13, 0, cb_data);
698 }
699
700 int for_each_glob_ref_in(each_ref_fn fn, const char *pattern,
701         const char *prefix, void *cb_data)
702 {
703         struct strbuf real_pattern = STRBUF_INIT;
704         struct ref_filter filter;
705         int ret;
706
707         if (!prefix && prefixcmp(pattern, "refs/"))
708                 strbuf_addstr(&real_pattern, "refs/");
709         else if (prefix)
710                 strbuf_addstr(&real_pattern, prefix);
711         strbuf_addstr(&real_pattern, pattern);
712
713         if (!has_glob_specials(pattern)) {
714                 /* Append implied '/' '*' if not present. */
715                 if (real_pattern.buf[real_pattern.len - 1] != '/')
716                         strbuf_addch(&real_pattern, '/');
717                 /* No need to check for '*', there is none. */
718                 strbuf_addch(&real_pattern, '*');
719         }
720
721         filter.pattern = real_pattern.buf;
722         filter.fn = fn;
723         filter.cb_data = cb_data;
724         ret = for_each_ref(filter_refs, &filter);
725
726         strbuf_release(&real_pattern);
727         return ret;
728 }
729
730 int for_each_glob_ref(each_ref_fn fn, const char *pattern, void *cb_data)
731 {
732         return for_each_glob_ref_in(fn, pattern, NULL, cb_data);
733 }
734
735 int for_each_rawref(each_ref_fn fn, void *cb_data)
736 {
737         return do_for_each_ref("refs/", fn, 0,
738                                DO_FOR_EACH_INCLUDE_BROKEN, cb_data);
739 }
740
741 /*
742  * Make sure "ref" is something reasonable to have under ".git/refs/";
743  * We do not like it if:
744  *
745  * - any path component of it begins with ".", or
746  * - it has double dots "..", or
747  * - it has ASCII control character, "~", "^", ":" or SP, anywhere, or
748  * - it ends with a "/".
749  * - it ends with ".lock"
750  * - it contains a "\" (backslash)
751  */
752
753 static inline int bad_ref_char(int ch)
754 {
755         if (((unsigned) ch) <= ' ' ||
756             ch == '~' || ch == '^' || ch == ':' || ch == '\\')
757                 return 1;
758         /* 2.13 Pattern Matching Notation */
759         if (ch == '?' || ch == '[') /* Unsupported */
760                 return 1;
761         if (ch == '*') /* Supported at the end */
762                 return 2;
763         return 0;
764 }
765
766 int check_ref_format(const char *ref)
767 {
768         int ch, level, bad_type, last;
769         int ret = CHECK_REF_FORMAT_OK;
770         const char *cp = ref;
771
772         level = 0;
773         while (1) {
774                 while ((ch = *cp++) == '/')
775                         ; /* tolerate duplicated slashes */
776                 if (!ch)
777                         /* should not end with slashes */
778                         return CHECK_REF_FORMAT_ERROR;
779
780                 /* we are at the beginning of the path component */
781                 if (ch == '.')
782                         return CHECK_REF_FORMAT_ERROR;
783                 bad_type = bad_ref_char(ch);
784                 if (bad_type) {
785                         if (bad_type == 2 && (!*cp || *cp == '/') &&
786                             ret == CHECK_REF_FORMAT_OK)
787                                 ret = CHECK_REF_FORMAT_WILDCARD;
788                         else
789                                 return CHECK_REF_FORMAT_ERROR;
790                 }
791
792                 last = ch;
793                 /* scan the rest of the path component */
794                 while ((ch = *cp++) != 0) {
795                         bad_type = bad_ref_char(ch);
796                         if (bad_type)
797                                 return CHECK_REF_FORMAT_ERROR;
798                         if (ch == '/')
799                                 break;
800                         if (last == '.' && ch == '.')
801                                 return CHECK_REF_FORMAT_ERROR;
802                         if (last == '@' && ch == '{')
803                                 return CHECK_REF_FORMAT_ERROR;
804                         last = ch;
805                 }
806                 level++;
807                 if (!ch) {
808                         if (ref <= cp - 2 && cp[-2] == '.')
809                                 return CHECK_REF_FORMAT_ERROR;
810                         if (level < 2)
811                                 return CHECK_REF_FORMAT_ONELEVEL;
812                         if (has_extension(ref, ".lock"))
813                                 return CHECK_REF_FORMAT_ERROR;
814                         return ret;
815                 }
816         }
817 }
818
819 const char *prettify_refname(const char *name)
820 {
821         return name + (
822                 !prefixcmp(name, "refs/heads/") ? 11 :
823                 !prefixcmp(name, "refs/tags/") ? 10 :
824                 !prefixcmp(name, "refs/remotes/") ? 13 :
825                 0);
826 }
827
828 const char *ref_rev_parse_rules[] = {
829         "%.*s",
830         "refs/%.*s",
831         "refs/tags/%.*s",
832         "refs/heads/%.*s",
833         "refs/remotes/%.*s",
834         "refs/remotes/%.*s/HEAD",
835         NULL
836 };
837
838 const char *ref_fetch_rules[] = {
839         "%.*s",
840         "refs/%.*s",
841         "refs/heads/%.*s",
842         NULL
843 };
844
845 int refname_match(const char *abbrev_name, const char *full_name, const char **rules)
846 {
847         const char **p;
848         const int abbrev_name_len = strlen(abbrev_name);
849
850         for (p = rules; *p; p++) {
851                 if (!strcmp(full_name, mkpath(*p, abbrev_name_len, abbrev_name))) {
852                         return 1;
853                 }
854         }
855
856         return 0;
857 }
858
859 static struct ref_lock *verify_lock(struct ref_lock *lock,
860         const unsigned char *old_sha1, int mustexist)
861 {
862         if (!resolve_ref(lock->ref_name, lock->old_sha1, mustexist, NULL)) {
863                 error("Can't verify ref %s", lock->ref_name);
864                 unlock_ref(lock);
865                 return NULL;
866         }
867         if (hashcmp(lock->old_sha1, old_sha1)) {
868                 error("Ref %s is at %s but expected %s", lock->ref_name,
869                         sha1_to_hex(lock->old_sha1), sha1_to_hex(old_sha1));
870                 unlock_ref(lock);
871                 return NULL;
872         }
873         return lock;
874 }
875
876 static int remove_empty_directories(const char *file)
877 {
878         /* we want to create a file but there is a directory there;
879          * if that is an empty directory (or a directory that contains
880          * only empty directories), remove them.
881          */
882         struct strbuf path;
883         int result;
884
885         strbuf_init(&path, 20);
886         strbuf_addstr(&path, file);
887
888         result = remove_dir_recursively(&path, REMOVE_DIR_EMPTY_ONLY);
889
890         strbuf_release(&path);
891
892         return result;
893 }
894
895 static int is_refname_available(const char *ref, const char *oldref,
896                                 struct ref_list *list, int quiet)
897 {
898         int namlen = strlen(ref); /* e.g. 'foo/bar' */
899         while (list) {
900                 /* list->name could be 'foo' or 'foo/bar/baz' */
901                 if (!oldref || strcmp(oldref, list->name)) {
902                         int len = strlen(list->name);
903                         int cmplen = (namlen < len) ? namlen : len;
904                         const char *lead = (namlen < len) ? list->name : ref;
905                         if (!strncmp(ref, list->name, cmplen) &&
906                             lead[cmplen] == '/') {
907                                 if (!quiet)
908                                         error("'%s' exists; cannot create '%s'",
909                                               list->name, ref);
910                                 return 0;
911                         }
912                 }
913                 list = list->next;
914         }
915         return 1;
916 }
917
918 static struct ref_lock *lock_ref_sha1_basic(const char *ref, const unsigned char *old_sha1, int flags, int *type_p)
919 {
920         char *ref_file;
921         const char *orig_ref = ref;
922         struct ref_lock *lock;
923         int last_errno = 0;
924         int type, lflags;
925         int mustexist = (old_sha1 && !is_null_sha1(old_sha1));
926         int missing = 0;
927
928         lock = xcalloc(1, sizeof(struct ref_lock));
929         lock->lock_fd = -1;
930
931         ref = resolve_ref(ref, lock->old_sha1, mustexist, &type);
932         if (!ref && errno == EISDIR) {
933                 /* we are trying to lock foo but we used to
934                  * have foo/bar which now does not exist;
935                  * it is normal for the empty directory 'foo'
936                  * to remain.
937                  */
938                 ref_file = git_path("%s", orig_ref);
939                 if (remove_empty_directories(ref_file)) {
940                         last_errno = errno;
941                         error("there are still refs under '%s'", orig_ref);
942                         goto error_return;
943                 }
944                 ref = resolve_ref(orig_ref, lock->old_sha1, mustexist, &type);
945         }
946         if (type_p)
947             *type_p = type;
948         if (!ref) {
949                 last_errno = errno;
950                 error("unable to resolve reference %s: %s",
951                         orig_ref, strerror(errno));
952                 goto error_return;
953         }
954         missing = is_null_sha1(lock->old_sha1);
955         /* When the ref did not exist and we are creating it,
956          * make sure there is no existing ref that is packed
957          * whose name begins with our refname, nor a ref whose
958          * name is a proper prefix of our refname.
959          */
960         if (missing &&
961              !is_refname_available(ref, NULL, get_packed_refs(), 0)) {
962                 last_errno = ENOTDIR;
963                 goto error_return;
964         }
965
966         lock->lk = xcalloc(1, sizeof(struct lock_file));
967
968         lflags = LOCK_DIE_ON_ERROR;
969         if (flags & REF_NODEREF) {
970                 ref = orig_ref;
971                 lflags |= LOCK_NODEREF;
972         }
973         lock->ref_name = xstrdup(ref);
974         lock->orig_ref_name = xstrdup(orig_ref);
975         ref_file = git_path("%s", ref);
976         if (missing)
977                 lock->force_write = 1;
978         if ((flags & REF_NODEREF) && (type & REF_ISSYMREF))
979                 lock->force_write = 1;
980
981         if (safe_create_leading_directories(ref_file)) {
982                 last_errno = errno;
983                 error("unable to create directory for %s", ref_file);
984                 goto error_return;
985         }
986
987         lock->lock_fd = hold_lock_file_for_update(lock->lk, ref_file, lflags);
988         return old_sha1 ? verify_lock(lock, old_sha1, mustexist) : lock;
989
990  error_return:
991         unlock_ref(lock);
992         errno = last_errno;
993         return NULL;
994 }
995
996 struct ref_lock *lock_ref_sha1(const char *ref, const unsigned char *old_sha1)
997 {
998         char refpath[PATH_MAX];
999         if (check_ref_format(ref))
1000                 return NULL;
1001         strcpy(refpath, mkpath("refs/%s", ref));
1002         return lock_ref_sha1_basic(refpath, old_sha1, 0, NULL);
1003 }
1004
1005 struct ref_lock *lock_any_ref_for_update(const char *ref, const unsigned char *old_sha1, int flags)
1006 {
1007         switch (check_ref_format(ref)) {
1008         default:
1009                 return NULL;
1010         case 0:
1011         case CHECK_REF_FORMAT_ONELEVEL:
1012                 return lock_ref_sha1_basic(ref, old_sha1, flags, NULL);
1013         }
1014 }
1015
1016 static struct lock_file packlock;
1017
1018 static int repack_without_ref(const char *refname)
1019 {
1020         struct ref_list *list, *packed_ref_list;
1021         int fd;
1022         int found = 0;
1023
1024         packed_ref_list = get_packed_refs();
1025         for (list = packed_ref_list; list; list = list->next) {
1026                 if (!strcmp(refname, list->name)) {
1027                         found = 1;
1028                         break;
1029                 }
1030         }
1031         if (!found)
1032                 return 0;
1033         fd = hold_lock_file_for_update(&packlock, git_path("packed-refs"), 0);
1034         if (fd < 0) {
1035                 unable_to_lock_error(git_path("packed-refs"), errno);
1036                 return error("cannot delete '%s' from packed refs", refname);
1037         }
1038
1039         for (list = packed_ref_list; list; list = list->next) {
1040                 char line[PATH_MAX + 100];
1041                 int len;
1042
1043                 if (!strcmp(refname, list->name))
1044                         continue;
1045                 len = snprintf(line, sizeof(line), "%s %s\n",
1046                                sha1_to_hex(list->sha1), list->name);
1047                 /* this should not happen but just being defensive */
1048                 if (len > sizeof(line))
1049                         die("too long a refname '%s'", list->name);
1050                 write_or_die(fd, line, len);
1051         }
1052         return commit_lock_file(&packlock);
1053 }
1054
1055 int delete_ref(const char *refname, const unsigned char *sha1, int delopt)
1056 {
1057         struct ref_lock *lock;
1058         int err, i = 0, ret = 0, flag = 0;
1059
1060         lock = lock_ref_sha1_basic(refname, sha1, 0, &flag);
1061         if (!lock)
1062                 return 1;
1063         if (!(flag & REF_ISPACKED) || flag & REF_ISSYMREF) {
1064                 /* loose */
1065                 const char *path;
1066
1067                 if (!(delopt & REF_NODEREF)) {
1068                         i = strlen(lock->lk->filename) - 5; /* .lock */
1069                         lock->lk->filename[i] = 0;
1070                         path = lock->lk->filename;
1071                 } else {
1072                         path = git_path("%s", refname);
1073                 }
1074                 err = unlink_or_warn(path);
1075                 if (err && errno != ENOENT)
1076                         ret = 1;
1077
1078                 if (!(delopt & REF_NODEREF))
1079                         lock->lk->filename[i] = '.';
1080         }
1081         /* removing the loose one could have resurrected an earlier
1082          * packed one.  Also, if it was not loose we need to repack
1083          * without it.
1084          */
1085         ret |= repack_without_ref(refname);
1086
1087         unlink_or_warn(git_path("logs/%s", lock->ref_name));
1088         invalidate_cached_refs();
1089         unlock_ref(lock);
1090         return ret;
1091 }
1092
1093 /*
1094  * People using contrib's git-new-workdir have .git/logs/refs ->
1095  * /some/other/path/.git/logs/refs, and that may live on another device.
1096  *
1097  * IOW, to avoid cross device rename errors, the temporary renamed log must
1098  * live into logs/refs.
1099  */
1100 #define TMP_RENAMED_LOG  "logs/refs/.tmp-renamed-log"
1101
1102 int rename_ref(const char *oldref, const char *newref, const char *logmsg)
1103 {
1104         static const char renamed_ref[] = "RENAMED-REF";
1105         unsigned char sha1[20], orig_sha1[20];
1106         int flag = 0, logmoved = 0;
1107         struct ref_lock *lock;
1108         struct stat loginfo;
1109         int log = !lstat(git_path("logs/%s", oldref), &loginfo);
1110         const char *symref = NULL;
1111
1112         if (log && S_ISLNK(loginfo.st_mode))
1113                 return error("reflog for %s is a symlink", oldref);
1114
1115         symref = resolve_ref(oldref, orig_sha1, 1, &flag);
1116         if (flag & REF_ISSYMREF)
1117                 return error("refname %s is a symbolic ref, renaming it is not supported",
1118                         oldref);
1119         if (!symref)
1120                 return error("refname %s not found", oldref);
1121
1122         if (!is_refname_available(newref, oldref, get_packed_refs(), 0))
1123                 return 1;
1124
1125         if (!is_refname_available(newref, oldref, get_loose_refs(), 0))
1126                 return 1;
1127
1128         lock = lock_ref_sha1_basic(renamed_ref, NULL, 0, NULL);
1129         if (!lock)
1130                 return error("unable to lock %s", renamed_ref);
1131         lock->force_write = 1;
1132         if (write_ref_sha1(lock, orig_sha1, logmsg))
1133                 return error("unable to save current sha1 in %s", renamed_ref);
1134
1135         if (log && rename(git_path("logs/%s", oldref), git_path(TMP_RENAMED_LOG)))
1136                 return error("unable to move logfile logs/%s to "TMP_RENAMED_LOG": %s",
1137                         oldref, strerror(errno));
1138
1139         if (delete_ref(oldref, orig_sha1, REF_NODEREF)) {
1140                 error("unable to delete old %s", oldref);
1141                 goto rollback;
1142         }
1143
1144         if (resolve_ref(newref, sha1, 1, &flag) && delete_ref(newref, sha1, REF_NODEREF)) {
1145                 if (errno==EISDIR) {
1146                         if (remove_empty_directories(git_path("%s", newref))) {
1147                                 error("Directory not empty: %s", newref);
1148                                 goto rollback;
1149                         }
1150                 } else {
1151                         error("unable to delete existing %s", newref);
1152                         goto rollback;
1153                 }
1154         }
1155
1156         if (log && safe_create_leading_directories(git_path("logs/%s", newref))) {
1157                 error("unable to create directory for %s", newref);
1158                 goto rollback;
1159         }
1160
1161  retry:
1162         if (log && rename(git_path(TMP_RENAMED_LOG), git_path("logs/%s", newref))) {
1163                 if (errno==EISDIR || errno==ENOTDIR) {
1164                         /*
1165                          * rename(a, b) when b is an existing
1166                          * directory ought to result in ISDIR, but
1167                          * Solaris 5.8 gives ENOTDIR.  Sheesh.
1168                          */
1169                         if (remove_empty_directories(git_path("logs/%s", newref))) {
1170                                 error("Directory not empty: logs/%s", newref);
1171                                 goto rollback;
1172                         }
1173                         goto retry;
1174                 } else {
1175                         error("unable to move logfile "TMP_RENAMED_LOG" to logs/%s: %s",
1176                                 newref, strerror(errno));
1177                         goto rollback;
1178                 }
1179         }
1180         logmoved = log;
1181
1182         lock = lock_ref_sha1_basic(newref, NULL, 0, NULL);
1183         if (!lock) {
1184                 error("unable to lock %s for update", newref);
1185                 goto rollback;
1186         }
1187         lock->force_write = 1;
1188         hashcpy(lock->old_sha1, orig_sha1);
1189         if (write_ref_sha1(lock, orig_sha1, logmsg)) {
1190                 error("unable to write current sha1 into %s", newref);
1191                 goto rollback;
1192         }
1193
1194         return 0;
1195
1196  rollback:
1197         lock = lock_ref_sha1_basic(oldref, NULL, 0, NULL);
1198         if (!lock) {
1199                 error("unable to lock %s for rollback", oldref);
1200                 goto rollbacklog;
1201         }
1202
1203         lock->force_write = 1;
1204         flag = log_all_ref_updates;
1205         log_all_ref_updates = 0;
1206         if (write_ref_sha1(lock, orig_sha1, NULL))
1207                 error("unable to write current sha1 into %s", oldref);
1208         log_all_ref_updates = flag;
1209
1210  rollbacklog:
1211         if (logmoved && rename(git_path("logs/%s", newref), git_path("logs/%s", oldref)))
1212                 error("unable to restore logfile %s from %s: %s",
1213                         oldref, newref, strerror(errno));
1214         if (!logmoved && log &&
1215             rename(git_path(TMP_RENAMED_LOG), git_path("logs/%s", oldref)))
1216                 error("unable to restore logfile %s from "TMP_RENAMED_LOG": %s",
1217                         oldref, strerror(errno));
1218
1219         return 1;
1220 }
1221
1222 int close_ref(struct ref_lock *lock)
1223 {
1224         if (close_lock_file(lock->lk))
1225                 return -1;
1226         lock->lock_fd = -1;
1227         return 0;
1228 }
1229
1230 int commit_ref(struct ref_lock *lock)
1231 {
1232         if (commit_lock_file(lock->lk))
1233                 return -1;
1234         lock->lock_fd = -1;
1235         return 0;
1236 }
1237
1238 void unlock_ref(struct ref_lock *lock)
1239 {
1240         /* Do not free lock->lk -- atexit() still looks at them */
1241         if (lock->lk)
1242                 rollback_lock_file(lock->lk);
1243         free(lock->ref_name);
1244         free(lock->orig_ref_name);
1245         free(lock);
1246 }
1247
1248 /*
1249  * copy the reflog message msg to buf, which has been allocated sufficiently
1250  * large, while cleaning up the whitespaces.  Especially, convert LF to space,
1251  * because reflog file is one line per entry.
1252  */
1253 static int copy_msg(char *buf, const char *msg)
1254 {
1255         char *cp = buf;
1256         char c;
1257         int wasspace = 1;
1258
1259         *cp++ = '\t';
1260         while ((c = *msg++)) {
1261                 if (wasspace && isspace(c))
1262                         continue;
1263                 wasspace = isspace(c);
1264                 if (wasspace)
1265                         c = ' ';
1266                 *cp++ = c;
1267         }
1268         while (buf < cp && isspace(cp[-1]))
1269                 cp--;
1270         *cp++ = '\n';
1271         return cp - buf;
1272 }
1273
1274 int log_ref_setup(const char *ref_name, char *logfile, int bufsize)
1275 {
1276         int logfd, oflags = O_APPEND | O_WRONLY;
1277
1278         git_snpath(logfile, bufsize, "logs/%s", ref_name);
1279         if (log_all_ref_updates &&
1280             (!prefixcmp(ref_name, "refs/heads/") ||
1281              !prefixcmp(ref_name, "refs/remotes/") ||
1282              !prefixcmp(ref_name, "refs/notes/") ||
1283              !strcmp(ref_name, "HEAD"))) {
1284                 if (safe_create_leading_directories(logfile) < 0)
1285                         return error("unable to create directory for %s",
1286                                      logfile);
1287                 oflags |= O_CREAT;
1288         }
1289
1290         logfd = open(logfile, oflags, 0666);
1291         if (logfd < 0) {
1292                 if (!(oflags & O_CREAT) && errno == ENOENT)
1293                         return 0;
1294
1295                 if ((oflags & O_CREAT) && errno == EISDIR) {
1296                         if (remove_empty_directories(logfile)) {
1297                                 return error("There are still logs under '%s'",
1298                                              logfile);
1299                         }
1300                         logfd = open(logfile, oflags, 0666);
1301                 }
1302
1303                 if (logfd < 0)
1304                         return error("Unable to append to %s: %s",
1305                                      logfile, strerror(errno));
1306         }
1307
1308         adjust_shared_perm(logfile);
1309         close(logfd);
1310         return 0;
1311 }
1312
1313 static int log_ref_write(const char *ref_name, const unsigned char *old_sha1,
1314                          const unsigned char *new_sha1, const char *msg)
1315 {
1316         int logfd, result, written, oflags = O_APPEND | O_WRONLY;
1317         unsigned maxlen, len;
1318         int msglen;
1319         char log_file[PATH_MAX];
1320         char *logrec;
1321         const char *committer;
1322
1323         if (log_all_ref_updates < 0)
1324                 log_all_ref_updates = !is_bare_repository();
1325
1326         result = log_ref_setup(ref_name, log_file, sizeof(log_file));
1327         if (result)
1328                 return result;
1329
1330         logfd = open(log_file, oflags);
1331         if (logfd < 0)
1332                 return 0;
1333         msglen = msg ? strlen(msg) : 0;
1334         committer = git_committer_info(0);
1335         maxlen = strlen(committer) + msglen + 100;
1336         logrec = xmalloc(maxlen);
1337         len = sprintf(logrec, "%s %s %s\n",
1338                       sha1_to_hex(old_sha1),
1339                       sha1_to_hex(new_sha1),
1340                       committer);
1341         if (msglen)
1342                 len += copy_msg(logrec + len - 1, msg) - 1;
1343         written = len <= maxlen ? write_in_full(logfd, logrec, len) : -1;
1344         free(logrec);
1345         if (close(logfd) != 0 || written != len)
1346                 return error("Unable to append to %s", log_file);
1347         return 0;
1348 }
1349
1350 static int is_branch(const char *refname)
1351 {
1352         return !strcmp(refname, "HEAD") || !prefixcmp(refname, "refs/heads/");
1353 }
1354
1355 int write_ref_sha1(struct ref_lock *lock,
1356         const unsigned char *sha1, const char *logmsg)
1357 {
1358         static char term = '\n';
1359         struct object *o;
1360
1361         if (!lock)
1362                 return -1;
1363         if (!lock->force_write && !hashcmp(lock->old_sha1, sha1)) {
1364                 unlock_ref(lock);
1365                 return 0;
1366         }
1367         o = parse_object(sha1);
1368         if (!o) {
1369                 error("Trying to write ref %s with nonexistant object %s",
1370                         lock->ref_name, sha1_to_hex(sha1));
1371                 unlock_ref(lock);
1372                 return -1;
1373         }
1374         if (o->type != OBJ_COMMIT && is_branch(lock->ref_name)) {
1375                 error("Trying to write non-commit object %s to branch %s",
1376                         sha1_to_hex(sha1), lock->ref_name);
1377                 unlock_ref(lock);
1378                 return -1;
1379         }
1380         if (write_in_full(lock->lock_fd, sha1_to_hex(sha1), 40) != 40 ||
1381             write_in_full(lock->lock_fd, &term, 1) != 1
1382                 || close_ref(lock) < 0) {
1383                 error("Couldn't write %s", lock->lk->filename);
1384                 unlock_ref(lock);
1385                 return -1;
1386         }
1387         invalidate_cached_refs();
1388         if (log_ref_write(lock->ref_name, lock->old_sha1, sha1, logmsg) < 0 ||
1389             (strcmp(lock->ref_name, lock->orig_ref_name) &&
1390              log_ref_write(lock->orig_ref_name, lock->old_sha1, sha1, logmsg) < 0)) {
1391                 unlock_ref(lock);
1392                 return -1;
1393         }
1394         if (strcmp(lock->orig_ref_name, "HEAD") != 0) {
1395                 /*
1396                  * Special hack: If a branch is updated directly and HEAD
1397                  * points to it (may happen on the remote side of a push
1398                  * for example) then logically the HEAD reflog should be
1399                  * updated too.
1400                  * A generic solution implies reverse symref information,
1401                  * but finding all symrefs pointing to the given branch
1402                  * would be rather costly for this rare event (the direct
1403                  * update of a branch) to be worth it.  So let's cheat and
1404                  * check with HEAD only which should cover 99% of all usage
1405                  * scenarios (even 100% of the default ones).
1406                  */
1407                 unsigned char head_sha1[20];
1408                 int head_flag;
1409                 const char *head_ref;
1410                 head_ref = resolve_ref("HEAD", head_sha1, 1, &head_flag);
1411                 if (head_ref && (head_flag & REF_ISSYMREF) &&
1412                     !strcmp(head_ref, lock->ref_name))
1413                         log_ref_write("HEAD", lock->old_sha1, sha1, logmsg);
1414         }
1415         if (commit_ref(lock)) {
1416                 error("Couldn't set %s", lock->ref_name);
1417                 unlock_ref(lock);
1418                 return -1;
1419         }
1420         unlock_ref(lock);
1421         return 0;
1422 }
1423
1424 int create_symref(const char *ref_target, const char *refs_heads_master,
1425                   const char *logmsg)
1426 {
1427         const char *lockpath;
1428         char ref[1000];
1429         int fd, len, written;
1430         char *git_HEAD = git_pathdup("%s", ref_target);
1431         unsigned char old_sha1[20], new_sha1[20];
1432
1433         if (logmsg && read_ref(ref_target, old_sha1))
1434                 hashclr(old_sha1);
1435
1436         if (safe_create_leading_directories(git_HEAD) < 0)
1437                 return error("unable to create directory for %s", git_HEAD);
1438
1439 #ifndef NO_SYMLINK_HEAD
1440         if (prefer_symlink_refs) {
1441                 unlink(git_HEAD);
1442                 if (!symlink(refs_heads_master, git_HEAD))
1443                         goto done;
1444                 fprintf(stderr, "no symlink - falling back to symbolic ref\n");
1445         }
1446 #endif
1447
1448         len = snprintf(ref, sizeof(ref), "ref: %s\n", refs_heads_master);
1449         if (sizeof(ref) <= len) {
1450                 error("refname too long: %s", refs_heads_master);
1451                 goto error_free_return;
1452         }
1453         lockpath = mkpath("%s.lock", git_HEAD);
1454         fd = open(lockpath, O_CREAT | O_EXCL | O_WRONLY, 0666);
1455         if (fd < 0) {
1456                 error("Unable to open %s for writing", lockpath);
1457                 goto error_free_return;
1458         }
1459         written = write_in_full(fd, ref, len);
1460         if (close(fd) != 0 || written != len) {
1461                 error("Unable to write to %s", lockpath);
1462                 goto error_unlink_return;
1463         }
1464         if (rename(lockpath, git_HEAD) < 0) {
1465                 error("Unable to create %s", git_HEAD);
1466                 goto error_unlink_return;
1467         }
1468         if (adjust_shared_perm(git_HEAD)) {
1469                 error("Unable to fix permissions on %s", lockpath);
1470         error_unlink_return:
1471                 unlink_or_warn(lockpath);
1472         error_free_return:
1473                 free(git_HEAD);
1474                 return -1;
1475         }
1476
1477 #ifndef NO_SYMLINK_HEAD
1478         done:
1479 #endif
1480         if (logmsg && !read_ref(refs_heads_master, new_sha1))
1481                 log_ref_write(ref_target, old_sha1, new_sha1, logmsg);
1482
1483         free(git_HEAD);
1484         return 0;
1485 }
1486
1487 static char *ref_msg(const char *line, const char *endp)
1488 {
1489         const char *ep;
1490         line += 82;
1491         ep = memchr(line, '\n', endp - line);
1492         if (!ep)
1493                 ep = endp;
1494         return xmemdupz(line, ep - line);
1495 }
1496
1497 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)
1498 {
1499         const char *logfile, *logdata, *logend, *rec, *lastgt, *lastrec;
1500         char *tz_c;
1501         int logfd, tz, reccnt = 0;
1502         struct stat st;
1503         unsigned long date;
1504         unsigned char logged_sha1[20];
1505         void *log_mapped;
1506         size_t mapsz;
1507
1508         logfile = git_path("logs/%s", ref);
1509         logfd = open(logfile, O_RDONLY, 0);
1510         if (logfd < 0)
1511                 die_errno("Unable to read log '%s'", logfile);
1512         fstat(logfd, &st);
1513         if (!st.st_size)
1514                 die("Log %s is empty.", logfile);
1515         mapsz = xsize_t(st.st_size);
1516         log_mapped = xmmap(NULL, mapsz, PROT_READ, MAP_PRIVATE, logfd, 0);
1517         logdata = log_mapped;
1518         close(logfd);
1519
1520         lastrec = NULL;
1521         rec = logend = logdata + st.st_size;
1522         while (logdata < rec) {
1523                 reccnt++;
1524                 if (logdata < rec && *(rec-1) == '\n')
1525                         rec--;
1526                 lastgt = NULL;
1527                 while (logdata < rec && *(rec-1) != '\n') {
1528                         rec--;
1529                         if (*rec == '>')
1530                                 lastgt = rec;
1531                 }
1532                 if (!lastgt)
1533                         die("Log %s is corrupt.", logfile);
1534                 date = strtoul(lastgt + 1, &tz_c, 10);
1535                 if (date <= at_time || cnt == 0) {
1536                         tz = strtoul(tz_c, NULL, 10);
1537                         if (msg)
1538                                 *msg = ref_msg(rec, logend);
1539                         if (cutoff_time)
1540                                 *cutoff_time = date;
1541                         if (cutoff_tz)
1542                                 *cutoff_tz = tz;
1543                         if (cutoff_cnt)
1544                                 *cutoff_cnt = reccnt - 1;
1545                         if (lastrec) {
1546                                 if (get_sha1_hex(lastrec, logged_sha1))
1547                                         die("Log %s is corrupt.", logfile);
1548                                 if (get_sha1_hex(rec + 41, sha1))
1549                                         die("Log %s is corrupt.", logfile);
1550                                 if (hashcmp(logged_sha1, sha1)) {
1551                                         warning("Log %s has gap after %s.",
1552                                                 logfile, show_date(date, tz, DATE_RFC2822));
1553                                 }
1554                         }
1555                         else if (date == at_time) {
1556                                 if (get_sha1_hex(rec + 41, sha1))
1557                                         die("Log %s is corrupt.", logfile);
1558                         }
1559                         else {
1560                                 if (get_sha1_hex(rec + 41, logged_sha1))
1561                                         die("Log %s is corrupt.", logfile);
1562                                 if (hashcmp(logged_sha1, sha1)) {
1563                                         warning("Log %s unexpectedly ended on %s.",
1564                                                 logfile, show_date(date, tz, DATE_RFC2822));
1565                                 }
1566                         }
1567                         munmap(log_mapped, mapsz);
1568                         return 0;
1569                 }
1570                 lastrec = rec;
1571                 if (cnt > 0)
1572                         cnt--;
1573         }
1574
1575         rec = logdata;
1576         while (rec < logend && *rec != '>' && *rec != '\n')
1577                 rec++;
1578         if (rec == logend || *rec == '\n')
1579                 die("Log %s is corrupt.", logfile);
1580         date = strtoul(rec + 1, &tz_c, 10);
1581         tz = strtoul(tz_c, NULL, 10);
1582         if (get_sha1_hex(logdata, sha1))
1583                 die("Log %s is corrupt.", logfile);
1584         if (is_null_sha1(sha1)) {
1585                 if (get_sha1_hex(logdata + 41, sha1))
1586                         die("Log %s is corrupt.", logfile);
1587         }
1588         if (msg)
1589                 *msg = ref_msg(logdata, logend);
1590         munmap(log_mapped, mapsz);
1591
1592         if (cutoff_time)
1593                 *cutoff_time = date;
1594         if (cutoff_tz)
1595                 *cutoff_tz = tz;
1596         if (cutoff_cnt)
1597                 *cutoff_cnt = reccnt;
1598         return 1;
1599 }
1600
1601 int for_each_recent_reflog_ent(const char *ref, each_reflog_ent_fn fn, long ofs, void *cb_data)
1602 {
1603         const char *logfile;
1604         FILE *logfp;
1605         struct strbuf sb = STRBUF_INIT;
1606         int ret = 0;
1607
1608         logfile = git_path("logs/%s", ref);
1609         logfp = fopen(logfile, "r");
1610         if (!logfp)
1611                 return -1;
1612
1613         if (ofs) {
1614                 struct stat statbuf;
1615                 if (fstat(fileno(logfp), &statbuf) ||
1616                     statbuf.st_size < ofs ||
1617                     fseek(logfp, -ofs, SEEK_END) ||
1618                     strbuf_getwholeline(&sb, logfp, '\n')) {
1619                         fclose(logfp);
1620                         strbuf_release(&sb);
1621                         return -1;
1622                 }
1623         }
1624
1625         while (!strbuf_getwholeline(&sb, logfp, '\n')) {
1626                 unsigned char osha1[20], nsha1[20];
1627                 char *email_end, *message;
1628                 unsigned long timestamp;
1629                 int tz;
1630
1631                 /* old SP new SP name <email> SP time TAB msg LF */
1632                 if (sb.len < 83 || sb.buf[sb.len - 1] != '\n' ||
1633                     get_sha1_hex(sb.buf, osha1) || sb.buf[40] != ' ' ||
1634                     get_sha1_hex(sb.buf + 41, nsha1) || sb.buf[81] != ' ' ||
1635                     !(email_end = strchr(sb.buf + 82, '>')) ||
1636                     email_end[1] != ' ' ||
1637                     !(timestamp = strtoul(email_end + 2, &message, 10)) ||
1638                     !message || message[0] != ' ' ||
1639                     (message[1] != '+' && message[1] != '-') ||
1640                     !isdigit(message[2]) || !isdigit(message[3]) ||
1641                     !isdigit(message[4]) || !isdigit(message[5]))
1642                         continue; /* corrupt? */
1643                 email_end[1] = '\0';
1644                 tz = strtol(message + 1, NULL, 10);
1645                 if (message[6] != '\t')
1646                         message += 6;
1647                 else
1648                         message += 7;
1649                 ret = fn(osha1, nsha1, sb.buf + 82, timestamp, tz, message,
1650                          cb_data);
1651                 if (ret)
1652                         break;
1653         }
1654         fclose(logfp);
1655         strbuf_release(&sb);
1656         return ret;
1657 }
1658
1659 int for_each_reflog_ent(const char *ref, each_reflog_ent_fn fn, void *cb_data)
1660 {
1661         return for_each_recent_reflog_ent(ref, fn, 0, cb_data);
1662 }
1663
1664 static int do_for_each_reflog(const char *base, each_ref_fn fn, void *cb_data)
1665 {
1666         DIR *dir = opendir(git_path("logs/%s", base));
1667         int retval = 0;
1668
1669         if (dir) {
1670                 struct dirent *de;
1671                 int baselen = strlen(base);
1672                 char *log = xmalloc(baselen + 257);
1673
1674                 memcpy(log, base, baselen);
1675                 if (baselen && base[baselen-1] != '/')
1676                         log[baselen++] = '/';
1677
1678                 while ((de = readdir(dir)) != NULL) {
1679                         struct stat st;
1680                         int namelen;
1681
1682                         if (de->d_name[0] == '.')
1683                                 continue;
1684                         namelen = strlen(de->d_name);
1685                         if (namelen > 255)
1686                                 continue;
1687                         if (has_extension(de->d_name, ".lock"))
1688                                 continue;
1689                         memcpy(log + baselen, de->d_name, namelen+1);
1690                         if (stat(git_path("logs/%s", log), &st) < 0)
1691                                 continue;
1692                         if (S_ISDIR(st.st_mode)) {
1693                                 retval = do_for_each_reflog(log, fn, cb_data);
1694                         } else {
1695                                 unsigned char sha1[20];
1696                                 if (!resolve_ref(log, sha1, 0, NULL))
1697                                         retval = error("bad ref for %s", log);
1698                                 else
1699                                         retval = fn(log, sha1, 0, cb_data);
1700                         }
1701                         if (retval)
1702                                 break;
1703                 }
1704                 free(log);
1705                 closedir(dir);
1706         }
1707         else if (*base)
1708                 return errno;
1709         return retval;
1710 }
1711
1712 int for_each_reflog(each_ref_fn fn, void *cb_data)
1713 {
1714         return do_for_each_reflog("", fn, cb_data);
1715 }
1716
1717 int update_ref(const char *action, const char *refname,
1718                 const unsigned char *sha1, const unsigned char *oldval,
1719                 int flags, enum action_on_err onerr)
1720 {
1721         static struct ref_lock *lock;
1722         lock = lock_any_ref_for_update(refname, oldval, flags);
1723         if (!lock) {
1724                 const char *str = "Cannot lock the ref '%s'.";
1725                 switch (onerr) {
1726                 case MSG_ON_ERR: error(str, refname); break;
1727                 case DIE_ON_ERR: die(str, refname); break;
1728                 case QUIET_ON_ERR: break;
1729                 }
1730                 return 1;
1731         }
1732         if (write_ref_sha1(lock, sha1, action) < 0) {
1733                 const char *str = "Cannot update the ref '%s'.";
1734                 switch (onerr) {
1735                 case MSG_ON_ERR: error(str, refname); break;
1736                 case DIE_ON_ERR: die(str, refname); break;
1737                 case QUIET_ON_ERR: break;
1738                 }
1739                 return 1;
1740         }
1741         return 0;
1742 }
1743
1744 struct ref *find_ref_by_name(const struct ref *list, const char *name)
1745 {
1746         for ( ; list; list = list->next)
1747                 if (!strcmp(list->name, name))
1748                         return (struct ref *)list;
1749         return NULL;
1750 }
1751
1752 /*
1753  * generate a format suitable for scanf from a ref_rev_parse_rules
1754  * rule, that is replace the "%.*s" spec with a "%s" spec
1755  */
1756 static void gen_scanf_fmt(char *scanf_fmt, const char *rule)
1757 {
1758         char *spec;
1759
1760         spec = strstr(rule, "%.*s");
1761         if (!spec || strstr(spec + 4, "%.*s"))
1762                 die("invalid rule in ref_rev_parse_rules: %s", rule);
1763
1764         /* copy all until spec */
1765         strncpy(scanf_fmt, rule, spec - rule);
1766         scanf_fmt[spec - rule] = '\0';
1767         /* copy new spec */
1768         strcat(scanf_fmt, "%s");
1769         /* copy remaining rule */
1770         strcat(scanf_fmt, spec + 4);
1771
1772         return;
1773 }
1774
1775 char *shorten_unambiguous_ref(const char *ref, int strict)
1776 {
1777         int i;
1778         static char **scanf_fmts;
1779         static int nr_rules;
1780         char *short_name;
1781
1782         /* pre generate scanf formats from ref_rev_parse_rules[] */
1783         if (!nr_rules) {
1784                 size_t total_len = 0;
1785
1786                 /* the rule list is NULL terminated, count them first */
1787                 for (; ref_rev_parse_rules[nr_rules]; nr_rules++)
1788                         /* no +1 because strlen("%s") < strlen("%.*s") */
1789                         total_len += strlen(ref_rev_parse_rules[nr_rules]);
1790
1791                 scanf_fmts = xmalloc(nr_rules * sizeof(char *) + total_len);
1792
1793                 total_len = 0;
1794                 for (i = 0; i < nr_rules; i++) {
1795                         scanf_fmts[i] = (char *)&scanf_fmts[nr_rules]
1796                                         + total_len;
1797                         gen_scanf_fmt(scanf_fmts[i], ref_rev_parse_rules[i]);
1798                         total_len += strlen(ref_rev_parse_rules[i]);
1799                 }
1800         }
1801
1802         /* bail out if there are no rules */
1803         if (!nr_rules)
1804                 return xstrdup(ref);
1805
1806         /* buffer for scanf result, at most ref must fit */
1807         short_name = xstrdup(ref);
1808
1809         /* skip first rule, it will always match */
1810         for (i = nr_rules - 1; i > 0 ; --i) {
1811                 int j;
1812                 int rules_to_fail = i;
1813                 int short_name_len;
1814
1815                 if (1 != sscanf(ref, scanf_fmts[i], short_name))
1816                         continue;
1817
1818                 short_name_len = strlen(short_name);
1819
1820                 /*
1821                  * in strict mode, all (except the matched one) rules
1822                  * must fail to resolve to a valid non-ambiguous ref
1823                  */
1824                 if (strict)
1825                         rules_to_fail = nr_rules;
1826
1827                 /*
1828                  * check if the short name resolves to a valid ref,
1829                  * but use only rules prior to the matched one
1830                  */
1831                 for (j = 0; j < rules_to_fail; j++) {
1832                         const char *rule = ref_rev_parse_rules[j];
1833                         unsigned char short_objectname[20];
1834                         char refname[PATH_MAX];
1835
1836                         /* skip matched rule */
1837                         if (i == j)
1838                                 continue;
1839
1840                         /*
1841                          * the short name is ambiguous, if it resolves
1842                          * (with this previous rule) to a valid ref
1843                          * read_ref() returns 0 on success
1844                          */
1845                         mksnpath(refname, sizeof(refname),
1846                                  rule, short_name_len, short_name);
1847                         if (!read_ref(refname, short_objectname))
1848                                 break;
1849                 }
1850
1851                 /*
1852                  * short name is non-ambiguous if all previous rules
1853                  * haven't resolved to a valid ref
1854                  */
1855                 if (j == rules_to_fail)
1856                         return short_name;
1857         }
1858
1859         free(short_name);
1860         return xstrdup(ref);
1861 }