Merge branch 'maint-1.5.1' into maint
[git] / refs.c
1 #include "cache.h"
2 #include "refs.h"
3 #include "object.h"
4 #include "tag.h"
5
6 /* ISSYMREF=01 and ISPACKED=02 are public interfaces */
7 #define REF_KNOWS_PEELED 04
8
9 struct ref_list {
10         struct ref_list *next;
11         unsigned char flag; /* ISSYMREF? ISPACKED? */
12         unsigned char sha1[20];
13         unsigned char peeled[20];
14         char name[FLEX_ARRAY];
15 };
16
17 static const char *parse_ref_line(char *line, unsigned char *sha1)
18 {
19         /*
20          * 42: the answer to everything.
21          *
22          * In this case, it happens to be the answer to
23          *  40 (length of sha1 hex representation)
24          *  +1 (space in between hex and name)
25          *  +1 (newline at the end of the line)
26          */
27         int len = strlen(line) - 42;
28
29         if (len <= 0)
30                 return NULL;
31         if (get_sha1_hex(line, sha1) < 0)
32                 return NULL;
33         if (!isspace(line[40]))
34                 return NULL;
35         line += 41;
36         if (isspace(*line))
37                 return NULL;
38         if (line[len] != '\n')
39                 return NULL;
40         line[len] = 0;
41
42         return line;
43 }
44
45 static struct ref_list *add_ref(const char *name, const unsigned char *sha1,
46                                 int flag, struct ref_list *list,
47                                 struct ref_list **new_entry)
48 {
49         int len;
50         struct ref_list *entry;
51
52         /* Allocate it and add it in.. */
53         len = strlen(name) + 1;
54         entry = xmalloc(sizeof(struct ref_list) + len);
55         hashcpy(entry->sha1, sha1);
56         hashclr(entry->peeled);
57         memcpy(entry->name, name, len);
58         entry->flag = flag;
59         entry->next = list;
60         if (new_entry)
61                 *new_entry = entry;
62         return entry;
63 }
64
65 /* merge sort the ref list */
66 static struct ref_list *sort_ref_list(struct ref_list *list)
67 {
68         int psize, qsize, last_merge_count, cmp;
69         struct ref_list *p, *q, *l, *e;
70         struct ref_list *new_list = list;
71         int k = 1;
72         int merge_count = 0;
73
74         if (!list)
75                 return list;
76
77         do {
78                 last_merge_count = merge_count;
79                 merge_count = 0;
80
81                 psize = 0;
82
83                 p = new_list;
84                 q = new_list;
85                 new_list = NULL;
86                 l = NULL;
87
88                 while (p) {
89                         merge_count++;
90
91                         while (psize < k && q->next) {
92                                 q = q->next;
93                                 psize++;
94                         }
95                         qsize = k;
96
97                         while ((psize > 0) || (qsize > 0 && q)) {
98                                 if (qsize == 0 || !q) {
99                                         e = p;
100                                         p = p->next;
101                                         psize--;
102                                 } else if (psize == 0) {
103                                         e = q;
104                                         q = q->next;
105                                         qsize--;
106                                 } else {
107                                         cmp = strcmp(q->name, p->name);
108                                         if (cmp < 0) {
109                                                 e = q;
110                                                 q = q->next;
111                                                 qsize--;
112                                         } else if (cmp > 0) {
113                                                 e = p;
114                                                 p = p->next;
115                                                 psize--;
116                                         } else {
117                                                 if (hashcmp(q->sha1, p->sha1))
118                                                         die("Duplicated ref, and SHA1s don't match: %s",
119                                                             q->name);
120                                                 warning("Duplicated ref: %s", q->name);
121                                                 e = q;
122                                                 q = q->next;
123                                                 qsize--;
124                                                 free(e);
125                                                 e = p;
126                                                 p = p->next;
127                                                 psize--;
128                                         }
129                                 }
130
131                                 e->next = NULL;
132
133                                 if (l)
134                                         l->next = e;
135                                 if (!new_list)
136                                         new_list = e;
137                                 l = e;
138                         }
139
140                         p = q;
141                 };
142
143                 k = k * 2;
144         } while ((last_merge_count != merge_count) || (last_merge_count != 1));
145
146         return new_list;
147 }
148
149 /*
150  * Future: need to be in "struct repository"
151  * when doing a full libification.
152  */
153 struct cached_refs {
154         char did_loose;
155         char did_packed;
156         struct ref_list *loose;
157         struct ref_list *packed;
158 } cached_refs;
159
160 static void free_ref_list(struct ref_list *list)
161 {
162         struct ref_list *next;
163         for ( ; list; list = next) {
164                 next = list->next;
165                 free(list);
166         }
167 }
168
169 static void invalidate_cached_refs(void)
170 {
171         struct cached_refs *ca = &cached_refs;
172
173         if (ca->did_loose && ca->loose)
174                 free_ref_list(ca->loose);
175         if (ca->did_packed && ca->packed)
176                 free_ref_list(ca->packed);
177         ca->loose = ca->packed = NULL;
178         ca->did_loose = ca->did_packed = 0;
179 }
180
181 static void read_packed_refs(FILE *f, struct cached_refs *cached_refs)
182 {
183         struct ref_list *list = NULL;
184         struct ref_list *last = NULL;
185         char refline[PATH_MAX];
186         int flag = REF_ISPACKED;
187
188         while (fgets(refline, sizeof(refline), f)) {
189                 unsigned char sha1[20];
190                 const char *name;
191                 static const char header[] = "# pack-refs with:";
192
193                 if (!strncmp(refline, header, sizeof(header)-1)) {
194                         const char *traits = refline + sizeof(header) - 1;
195                         if (strstr(traits, " peeled "))
196                                 flag |= REF_KNOWS_PEELED;
197                         /* perhaps other traits later as well */
198                         continue;
199                 }
200
201                 name = parse_ref_line(refline, sha1);
202                 if (name) {
203                         list = add_ref(name, sha1, flag, list, &last);
204                         continue;
205                 }
206                 if (last &&
207                     refline[0] == '^' &&
208                     strlen(refline) == 42 &&
209                     refline[41] == '\n' &&
210                     !get_sha1_hex(refline + 1, sha1))
211                         hashcpy(last->peeled, sha1);
212         }
213         cached_refs->packed = sort_ref_list(list);
214 }
215
216 static struct ref_list *get_packed_refs(void)
217 {
218         if (!cached_refs.did_packed) {
219                 FILE *f = fopen(git_path("packed-refs"), "r");
220                 cached_refs.packed = NULL;
221                 if (f) {
222                         read_packed_refs(f, &cached_refs);
223                         fclose(f);
224                 }
225                 cached_refs.did_packed = 1;
226         }
227         return cached_refs.packed;
228 }
229
230 static struct ref_list *get_ref_dir(const char *base, struct ref_list *list)
231 {
232         DIR *dir = opendir(git_path("%s", base));
233
234         if (dir) {
235                 struct dirent *de;
236                 int baselen = strlen(base);
237                 char *ref = xmalloc(baselen + 257);
238
239                 memcpy(ref, base, baselen);
240                 if (baselen && base[baselen-1] != '/')
241                         ref[baselen++] = '/';
242
243                 while ((de = readdir(dir)) != NULL) {
244                         unsigned char sha1[20];
245                         struct stat st;
246                         int flag;
247                         int namelen;
248
249                         if (de->d_name[0] == '.')
250                                 continue;
251                         namelen = strlen(de->d_name);
252                         if (namelen > 255)
253                                 continue;
254                         if (has_extension(de->d_name, ".lock"))
255                                 continue;
256                         memcpy(ref + baselen, de->d_name, namelen+1);
257                         if (stat(git_path("%s", ref), &st) < 0)
258                                 continue;
259                         if (S_ISDIR(st.st_mode)) {
260                                 list = get_ref_dir(ref, list);
261                                 continue;
262                         }
263                         if (!resolve_ref(ref, sha1, 1, &flag)) {
264                                 error("%s points nowhere!", ref);
265                                 continue;
266                         }
267                         list = add_ref(ref, sha1, flag, list, NULL);
268                 }
269                 free(ref);
270                 closedir(dir);
271         }
272         return sort_ref_list(list);
273 }
274
275 static struct ref_list *get_loose_refs(void)
276 {
277         if (!cached_refs.did_loose) {
278                 cached_refs.loose = get_ref_dir("refs", NULL);
279                 cached_refs.did_loose = 1;
280         }
281         return cached_refs.loose;
282 }
283
284 /* We allow "recursive" symbolic refs. Only within reason, though */
285 #define MAXDEPTH 5
286 #define MAXREFLEN (1024)
287
288 static int resolve_gitlink_packed_ref(char *name, int pathlen, const char *refname, unsigned char *result)
289 {
290         FILE *f;
291         struct cached_refs refs;
292         struct ref_list *ref;
293         int retval;
294
295         strcpy(name + pathlen, "packed-refs");
296         f = fopen(name, "r");
297         if (!f)
298                 return -1;
299         read_packed_refs(f, &refs);
300         fclose(f);
301         ref = refs.packed;
302         retval = -1;
303         while (ref) {
304                 if (!strcmp(ref->name, refname)) {
305                         retval = 0;
306                         memcpy(result, ref->sha1, 20);
307                         break;
308                 }
309                 ref = ref->next;
310         }
311         free_ref_list(refs.packed);
312         return retval;
313 }
314
315 static int resolve_gitlink_ref_recursive(char *name, int pathlen, const char *refname, unsigned char *result, int recursion)
316 {
317         int fd, len = strlen(refname);
318         char buffer[128], *p;
319
320         if (recursion > MAXDEPTH || len > MAXREFLEN)
321                 return -1;
322         memcpy(name + pathlen, refname, len+1);
323         fd = open(name, O_RDONLY);
324         if (fd < 0)
325                 return resolve_gitlink_packed_ref(name, pathlen, refname, result);
326
327         len = read(fd, buffer, sizeof(buffer)-1);
328         close(fd);
329         if (len < 0)
330                 return -1;
331         while (len && isspace(buffer[len-1]))
332                 len--;
333         buffer[len] = 0;
334
335         /* Was it a detached head or an old-fashioned symlink? */
336         if (!get_sha1_hex(buffer, result))
337                 return 0;
338
339         /* Symref? */
340         if (strncmp(buffer, "ref:", 4))
341                 return -1;
342         p = buffer + 4;
343         while (isspace(*p))
344                 p++;
345
346         return resolve_gitlink_ref_recursive(name, pathlen, p, result, recursion+1);
347 }
348
349 int resolve_gitlink_ref(const char *path, const char *refname, unsigned char *result)
350 {
351         int len = strlen(path), retval;
352         char *gitdir;
353
354         while (len && path[len-1] == '/')
355                 len--;
356         if (!len)
357                 return -1;
358         gitdir = xmalloc(len + MAXREFLEN + 8);
359         memcpy(gitdir, path, len);
360         memcpy(gitdir + len, "/.git/", 7);
361
362         retval = resolve_gitlink_ref_recursive(gitdir, len+6, refname, result, 0);
363         free(gitdir);
364         return retval;
365 }
366
367 const char *resolve_ref(const char *ref, unsigned char *sha1, int reading, int *flag)
368 {
369         int depth = MAXDEPTH, len;
370         char buffer[256];
371         static char ref_buffer[256];
372
373         if (flag)
374                 *flag = 0;
375
376         for (;;) {
377                 const char *path = git_path("%s", ref);
378                 struct stat st;
379                 char *buf;
380                 int fd;
381
382                 if (--depth < 0)
383                         return NULL;
384
385                 /* Special case: non-existing file.
386                  * Not having the refs/heads/new-branch is OK
387                  * if we are writing into it, so is .git/HEAD
388                  * that points at refs/heads/master still to be
389                  * born.  It is NOT OK if we are resolving for
390                  * reading.
391                  */
392                 if (lstat(path, &st) < 0) {
393                         struct ref_list *list = get_packed_refs();
394                         while (list) {
395                                 if (!strcmp(ref, list->name)) {
396                                         hashcpy(sha1, list->sha1);
397                                         if (flag)
398                                                 *flag |= REF_ISPACKED;
399                                         return ref;
400                                 }
401                                 list = list->next;
402                         }
403                         if (reading || errno != ENOENT)
404                                 return NULL;
405                         hashclr(sha1);
406                         return ref;
407                 }
408
409                 /* Follow "normalized" - ie "refs/.." symlinks by hand */
410                 if (S_ISLNK(st.st_mode)) {
411                         len = readlink(path, buffer, sizeof(buffer)-1);
412                         if (len >= 5 && !memcmp("refs/", buffer, 5)) {
413                                 buffer[len] = 0;
414                                 strcpy(ref_buffer, buffer);
415                                 ref = ref_buffer;
416                                 if (flag)
417                                         *flag |= REF_ISSYMREF;
418                                 continue;
419                         }
420                 }
421
422                 /* Is it a directory? */
423                 if (S_ISDIR(st.st_mode)) {
424                         errno = EISDIR;
425                         return NULL;
426                 }
427
428                 /*
429                  * Anything else, just open it and try to use it as
430                  * a ref
431                  */
432                 fd = open(path, O_RDONLY);
433                 if (fd < 0)
434                         return NULL;
435                 len = read_in_full(fd, buffer, sizeof(buffer)-1);
436                 close(fd);
437
438                 /*
439                  * Is it a symbolic ref?
440                  */
441                 if (len < 4 || memcmp("ref:", buffer, 4))
442                         break;
443                 buf = buffer + 4;
444                 len -= 4;
445                 while (len && isspace(*buf))
446                         buf++, len--;
447                 while (len && isspace(buf[len-1]))
448                         len--;
449                 buf[len] = 0;
450                 memcpy(ref_buffer, buf, len + 1);
451                 ref = ref_buffer;
452                 if (flag)
453                         *flag |= REF_ISSYMREF;
454         }
455         if (len < 40 || get_sha1_hex(buffer, sha1))
456                 return NULL;
457         return ref;
458 }
459
460 int read_ref(const char *ref, unsigned char *sha1)
461 {
462         if (resolve_ref(ref, sha1, 1, NULL))
463                 return 0;
464         return -1;
465 }
466
467 static int do_one_ref(const char *base, each_ref_fn fn, int trim,
468                       void *cb_data, struct ref_list *entry)
469 {
470         if (strncmp(base, entry->name, trim))
471                 return 0;
472         if (is_null_sha1(entry->sha1))
473                 return 0;
474         if (!has_sha1_file(entry->sha1)) {
475                 error("%s does not point to a valid object!", entry->name);
476                 return 0;
477         }
478         return fn(entry->name + trim, entry->sha1, entry->flag, cb_data);
479 }
480
481 int peel_ref(const char *ref, unsigned char *sha1)
482 {
483         int flag;
484         unsigned char base[20];
485         struct object *o;
486
487         if (!resolve_ref(ref, base, 1, &flag))
488                 return -1;
489
490         if ((flag & REF_ISPACKED)) {
491                 struct ref_list *list = get_packed_refs();
492
493                 while (list) {
494                         if (!strcmp(list->name, ref)) {
495                                 if (list->flag & REF_KNOWS_PEELED) {
496                                         hashcpy(sha1, list->peeled);
497                                         return 0;
498                                 }
499                                 /* older pack-refs did not leave peeled ones */
500                                 break;
501                         }
502                         list = list->next;
503                 }
504         }
505
506         /* fallback - callers should not call this for unpacked refs */
507         o = parse_object(base);
508         if (o->type == OBJ_TAG) {
509                 o = deref_tag(o, ref, 0);
510                 if (o) {
511                         hashcpy(sha1, o->sha1);
512                         return 0;
513                 }
514         }
515         return -1;
516 }
517
518 static int do_for_each_ref(const char *base, each_ref_fn fn, int trim,
519                            void *cb_data)
520 {
521         int retval;
522         struct ref_list *packed = get_packed_refs();
523         struct ref_list *loose = get_loose_refs();
524
525         while (packed && loose) {
526                 struct ref_list *entry;
527                 int cmp = strcmp(packed->name, loose->name);
528                 if (!cmp) {
529                         packed = packed->next;
530                         continue;
531                 }
532                 if (cmp > 0) {
533                         entry = loose;
534                         loose = loose->next;
535                 } else {
536                         entry = packed;
537                         packed = packed->next;
538                 }
539                 retval = do_one_ref(base, fn, trim, cb_data, entry);
540                 if (retval)
541                         return retval;
542         }
543
544         for (packed = packed ? packed : loose; packed; packed = packed->next) {
545                 retval = do_one_ref(base, fn, trim, cb_data, packed);
546                 if (retval)
547                         return retval;
548         }
549         return 0;
550 }
551
552 int head_ref(each_ref_fn fn, void *cb_data)
553 {
554         unsigned char sha1[20];
555         int flag;
556
557         if (resolve_ref("HEAD", sha1, 1, &flag))
558                 return fn("HEAD", sha1, flag, cb_data);
559         return 0;
560 }
561
562 int for_each_ref(each_ref_fn fn, void *cb_data)
563 {
564         return do_for_each_ref("refs/", fn, 0, cb_data);
565 }
566
567 int for_each_tag_ref(each_ref_fn fn, void *cb_data)
568 {
569         return do_for_each_ref("refs/tags/", fn, 10, cb_data);
570 }
571
572 int for_each_branch_ref(each_ref_fn fn, void *cb_data)
573 {
574         return do_for_each_ref("refs/heads/", fn, 11, cb_data);
575 }
576
577 int for_each_remote_ref(each_ref_fn fn, void *cb_data)
578 {
579         return do_for_each_ref("refs/remotes/", fn, 13, cb_data);
580 }
581
582 /* NEEDSWORK: This is only used by ssh-upload and it should go; the
583  * caller should do resolve_ref or read_ref like everybody else.  Or
584  * maybe everybody else should use get_ref_sha1() instead of doing
585  * read_ref().
586  */
587 int get_ref_sha1(const char *ref, unsigned char *sha1)
588 {
589         if (check_ref_format(ref))
590                 return -1;
591         return read_ref(mkpath("refs/%s", ref), sha1);
592 }
593
594 /*
595  * Make sure "ref" is something reasonable to have under ".git/refs/";
596  * We do not like it if:
597  *
598  * - any path component of it begins with ".", or
599  * - it has double dots "..", or
600  * - it has ASCII control character, "~", "^", ":" or SP, anywhere, or
601  * - it ends with a "/".
602  */
603
604 static inline int bad_ref_char(int ch)
605 {
606         return (((unsigned) ch) <= ' ' ||
607                 ch == '~' || ch == '^' || ch == ':' ||
608                 /* 2.13 Pattern Matching Notation */
609                 ch == '?' || ch == '*' || ch == '[');
610 }
611
612 int check_ref_format(const char *ref)
613 {
614         int ch, level;
615         const char *cp = ref;
616
617         level = 0;
618         while (1) {
619                 while ((ch = *cp++) == '/')
620                         ; /* tolerate duplicated slashes */
621                 if (!ch)
622                         return -1; /* should not end with slashes */
623
624                 /* we are at the beginning of the path component */
625                 if (ch == '.' || bad_ref_char(ch))
626                         return -1;
627
628                 /* scan the rest of the path component */
629                 while ((ch = *cp++) != 0) {
630                         if (bad_ref_char(ch))
631                                 return -1;
632                         if (ch == '/')
633                                 break;
634                         if (ch == '.' && *cp == '.')
635                                 return -1;
636                 }
637                 level++;
638                 if (!ch) {
639                         if (level < 2)
640                                 return -2; /* at least of form "heads/blah" */
641                         return 0;
642                 }
643         }
644 }
645
646 static struct ref_lock *verify_lock(struct ref_lock *lock,
647         const unsigned char *old_sha1, int mustexist)
648 {
649         if (!resolve_ref(lock->ref_name, lock->old_sha1, mustexist, NULL)) {
650                 error("Can't verify ref %s", lock->ref_name);
651                 unlock_ref(lock);
652                 return NULL;
653         }
654         if (hashcmp(lock->old_sha1, old_sha1)) {
655                 error("Ref %s is at %s but expected %s", lock->ref_name,
656                         sha1_to_hex(lock->old_sha1), sha1_to_hex(old_sha1));
657                 unlock_ref(lock);
658                 return NULL;
659         }
660         return lock;
661 }
662
663 static int remove_empty_dir_recursive(char *path, int len)
664 {
665         DIR *dir = opendir(path);
666         struct dirent *e;
667         int ret = 0;
668
669         if (!dir)
670                 return -1;
671         if (path[len-1] != '/')
672                 path[len++] = '/';
673         while ((e = readdir(dir)) != NULL) {
674                 struct stat st;
675                 int namlen;
676                 if ((e->d_name[0] == '.') &&
677                     ((e->d_name[1] == 0) ||
678                      ((e->d_name[1] == '.') && e->d_name[2] == 0)))
679                         continue; /* "." and ".." */
680
681                 namlen = strlen(e->d_name);
682                 if ((len + namlen < PATH_MAX) &&
683                     strcpy(path + len, e->d_name) &&
684                     !lstat(path, &st) &&
685                     S_ISDIR(st.st_mode) &&
686                     !remove_empty_dir_recursive(path, len + namlen))
687                         continue; /* happy */
688
689                 /* path too long, stat fails, or non-directory still exists */
690                 ret = -1;
691                 break;
692         }
693         closedir(dir);
694         if (!ret) {
695                 path[len] = 0;
696                 ret = rmdir(path);
697         }
698         return ret;
699 }
700
701 static int remove_empty_directories(char *file)
702 {
703         /* we want to create a file but there is a directory there;
704          * if that is an empty directory (or a directory that contains
705          * only empty directories), remove them.
706          */
707         char path[PATH_MAX];
708         int len = strlen(file);
709
710         if (len >= PATH_MAX) /* path too long ;-) */
711                 return -1;
712         strcpy(path, file);
713         return remove_empty_dir_recursive(path, len);
714 }
715
716 static int is_refname_available(const char *ref, const char *oldref,
717                                 struct ref_list *list, int quiet)
718 {
719         int namlen = strlen(ref); /* e.g. 'foo/bar' */
720         while (list) {
721                 /* list->name could be 'foo' or 'foo/bar/baz' */
722                 if (!oldref || strcmp(oldref, list->name)) {
723                         int len = strlen(list->name);
724                         int cmplen = (namlen < len) ? namlen : len;
725                         const char *lead = (namlen < len) ? list->name : ref;
726                         if (!strncmp(ref, list->name, cmplen) &&
727                             lead[cmplen] == '/') {
728                                 if (!quiet)
729                                         error("'%s' exists; cannot create '%s'",
730                                               list->name, ref);
731                                 return 0;
732                         }
733                 }
734                 list = list->next;
735         }
736         return 1;
737 }
738
739 static struct ref_lock *lock_ref_sha1_basic(const char *ref, const unsigned char *old_sha1, int *flag)
740 {
741         char *ref_file;
742         const char *orig_ref = ref;
743         struct ref_lock *lock;
744         struct stat st;
745         int last_errno = 0;
746         int mustexist = (old_sha1 && !is_null_sha1(old_sha1));
747
748         lock = xcalloc(1, sizeof(struct ref_lock));
749         lock->lock_fd = -1;
750
751         ref = resolve_ref(ref, lock->old_sha1, mustexist, flag);
752         if (!ref && errno == EISDIR) {
753                 /* we are trying to lock foo but we used to
754                  * have foo/bar which now does not exist;
755                  * it is normal for the empty directory 'foo'
756                  * to remain.
757                  */
758                 ref_file = git_path("%s", orig_ref);
759                 if (remove_empty_directories(ref_file)) {
760                         last_errno = errno;
761                         error("there are still refs under '%s'", orig_ref);
762                         goto error_return;
763                 }
764                 ref = resolve_ref(orig_ref, lock->old_sha1, mustexist, flag);
765         }
766         if (!ref) {
767                 last_errno = errno;
768                 error("unable to resolve reference %s: %s",
769                         orig_ref, strerror(errno));
770                 goto error_return;
771         }
772         /* When the ref did not exist and we are creating it,
773          * make sure there is no existing ref that is packed
774          * whose name begins with our refname, nor a ref whose
775          * name is a proper prefix of our refname.
776          */
777         if (is_null_sha1(lock->old_sha1) &&
778             !is_refname_available(ref, NULL, get_packed_refs(), 0))
779                 goto error_return;
780
781         lock->lk = xcalloc(1, sizeof(struct lock_file));
782
783         lock->ref_name = xstrdup(ref);
784         lock->orig_ref_name = xstrdup(orig_ref);
785         ref_file = git_path("%s", ref);
786         lock->force_write = lstat(ref_file, &st) && errno == ENOENT;
787
788         if (safe_create_leading_directories(ref_file)) {
789                 last_errno = errno;
790                 error("unable to create directory for %s", ref_file);
791                 goto error_return;
792         }
793         lock->lock_fd = hold_lock_file_for_update(lock->lk, ref_file, 1);
794
795         return old_sha1 ? verify_lock(lock, old_sha1, mustexist) : lock;
796
797  error_return:
798         unlock_ref(lock);
799         errno = last_errno;
800         return NULL;
801 }
802
803 struct ref_lock *lock_ref_sha1(const char *ref, const unsigned char *old_sha1)
804 {
805         char refpath[PATH_MAX];
806         if (check_ref_format(ref))
807                 return NULL;
808         strcpy(refpath, mkpath("refs/%s", ref));
809         return lock_ref_sha1_basic(refpath, old_sha1, NULL);
810 }
811
812 struct ref_lock *lock_any_ref_for_update(const char *ref, const unsigned char *old_sha1)
813 {
814         if (check_ref_format(ref) == -1)
815                 return NULL;
816         return lock_ref_sha1_basic(ref, old_sha1, NULL);
817 }
818
819 static struct lock_file packlock;
820
821 static int repack_without_ref(const char *refname)
822 {
823         struct ref_list *list, *packed_ref_list;
824         int fd;
825         int found = 0;
826
827         packed_ref_list = get_packed_refs();
828         for (list = packed_ref_list; list; list = list->next) {
829                 if (!strcmp(refname, list->name)) {
830                         found = 1;
831                         break;
832                 }
833         }
834         if (!found)
835                 return 0;
836         fd = hold_lock_file_for_update(&packlock, git_path("packed-refs"), 0);
837         if (fd < 0)
838                 return error("cannot delete '%s' from packed refs", refname);
839
840         for (list = packed_ref_list; list; list = list->next) {
841                 char line[PATH_MAX + 100];
842                 int len;
843
844                 if (!strcmp(refname, list->name))
845                         continue;
846                 len = snprintf(line, sizeof(line), "%s %s\n",
847                                sha1_to_hex(list->sha1), list->name);
848                 /* this should not happen but just being defensive */
849                 if (len > sizeof(line))
850                         die("too long a refname '%s'", list->name);
851                 write_or_die(fd, line, len);
852         }
853         return commit_lock_file(&packlock);
854 }
855
856 int delete_ref(const char *refname, const unsigned char *sha1)
857 {
858         struct ref_lock *lock;
859         int err, i, ret = 0, flag = 0;
860
861         lock = lock_ref_sha1_basic(refname, sha1, &flag);
862         if (!lock)
863                 return 1;
864         if (!(flag & REF_ISPACKED)) {
865                 /* loose */
866                 i = strlen(lock->lk->filename) - 5; /* .lock */
867                 lock->lk->filename[i] = 0;
868                 err = unlink(lock->lk->filename);
869                 if (err) {
870                         ret = 1;
871                         error("unlink(%s) failed: %s",
872                               lock->lk->filename, strerror(errno));
873                 }
874                 lock->lk->filename[i] = '.';
875         }
876         /* removing the loose one could have resurrected an earlier
877          * packed one.  Also, if it was not loose we need to repack
878          * without it.
879          */
880         ret |= repack_without_ref(refname);
881
882         err = unlink(git_path("logs/%s", lock->ref_name));
883         if (err && errno != ENOENT)
884                 fprintf(stderr, "warning: unlink(%s) failed: %s",
885                         git_path("logs/%s", lock->ref_name), strerror(errno));
886         invalidate_cached_refs();
887         unlock_ref(lock);
888         return ret;
889 }
890
891 int rename_ref(const char *oldref, const char *newref, const char *logmsg)
892 {
893         static const char renamed_ref[] = "RENAMED-REF";
894         unsigned char sha1[20], orig_sha1[20];
895         int flag = 0, logmoved = 0;
896         struct ref_lock *lock;
897         struct stat loginfo;
898         int log = !lstat(git_path("logs/%s", oldref), &loginfo);
899
900         if (S_ISLNK(loginfo.st_mode))
901                 return error("reflog for %s is a symlink", oldref);
902
903         if (!resolve_ref(oldref, orig_sha1, 1, &flag))
904                 return error("refname %s not found", oldref);
905
906         if (!is_refname_available(newref, oldref, get_packed_refs(), 0))
907                 return 1;
908
909         if (!is_refname_available(newref, oldref, get_loose_refs(), 0))
910                 return 1;
911
912         lock = lock_ref_sha1_basic(renamed_ref, NULL, NULL);
913         if (!lock)
914                 return error("unable to lock %s", renamed_ref);
915         lock->force_write = 1;
916         if (write_ref_sha1(lock, orig_sha1, logmsg))
917                 return error("unable to save current sha1 in %s", renamed_ref);
918
919         if (log && rename(git_path("logs/%s", oldref), git_path("tmp-renamed-log")))
920                 return error("unable to move logfile logs/%s to tmp-renamed-log: %s",
921                         oldref, strerror(errno));
922
923         if (delete_ref(oldref, orig_sha1)) {
924                 error("unable to delete old %s", oldref);
925                 goto rollback;
926         }
927
928         if (resolve_ref(newref, sha1, 1, &flag) && delete_ref(newref, sha1)) {
929                 if (errno==EISDIR) {
930                         if (remove_empty_directories(git_path("%s", newref))) {
931                                 error("Directory not empty: %s", newref);
932                                 goto rollback;
933                         }
934                 } else {
935                         error("unable to delete existing %s", newref);
936                         goto rollback;
937                 }
938         }
939
940         if (log && safe_create_leading_directories(git_path("logs/%s", newref))) {
941                 error("unable to create directory for %s", newref);
942                 goto rollback;
943         }
944
945  retry:
946         if (log && rename(git_path("tmp-renamed-log"), git_path("logs/%s", newref))) {
947                 if (errno==EISDIR || errno==ENOTDIR) {
948                         /*
949                          * rename(a, b) when b is an existing
950                          * directory ought to result in ISDIR, but
951                          * Solaris 5.8 gives ENOTDIR.  Sheesh.
952                          */
953                         if (remove_empty_directories(git_path("logs/%s", newref))) {
954                                 error("Directory not empty: logs/%s", newref);
955                                 goto rollback;
956                         }
957                         goto retry;
958                 } else {
959                         error("unable to move logfile tmp-renamed-log to logs/%s: %s",
960                                 newref, strerror(errno));
961                         goto rollback;
962                 }
963         }
964         logmoved = log;
965
966         lock = lock_ref_sha1_basic(newref, NULL, NULL);
967         if (!lock) {
968                 error("unable to lock %s for update", newref);
969                 goto rollback;
970         }
971
972         lock->force_write = 1;
973         hashcpy(lock->old_sha1, orig_sha1);
974         if (write_ref_sha1(lock, orig_sha1, logmsg)) {
975                 error("unable to write current sha1 into %s", newref);
976                 goto rollback;
977         }
978
979         return 0;
980
981  rollback:
982         lock = lock_ref_sha1_basic(oldref, NULL, NULL);
983         if (!lock) {
984                 error("unable to lock %s for rollback", oldref);
985                 goto rollbacklog;
986         }
987
988         lock->force_write = 1;
989         flag = log_all_ref_updates;
990         log_all_ref_updates = 0;
991         if (write_ref_sha1(lock, orig_sha1, NULL))
992                 error("unable to write current sha1 into %s", oldref);
993         log_all_ref_updates = flag;
994
995  rollbacklog:
996         if (logmoved && rename(git_path("logs/%s", newref), git_path("logs/%s", oldref)))
997                 error("unable to restore logfile %s from %s: %s",
998                         oldref, newref, strerror(errno));
999         if (!logmoved && log &&
1000             rename(git_path("tmp-renamed-log"), git_path("logs/%s", oldref)))
1001                 error("unable to restore logfile %s from tmp-renamed-log: %s",
1002                         oldref, strerror(errno));
1003
1004         return 1;
1005 }
1006
1007 void unlock_ref(struct ref_lock *lock)
1008 {
1009         if (lock->lock_fd >= 0) {
1010                 close(lock->lock_fd);
1011                 /* Do not free lock->lk -- atexit() still looks at them */
1012                 if (lock->lk)
1013                         rollback_lock_file(lock->lk);
1014         }
1015         free(lock->ref_name);
1016         free(lock->orig_ref_name);
1017         free(lock);
1018 }
1019
1020 static int log_ref_write(const char *ref_name, const unsigned char *old_sha1,
1021                          const unsigned char *new_sha1, const char *msg)
1022 {
1023         int logfd, written, oflags = O_APPEND | O_WRONLY;
1024         unsigned maxlen, len;
1025         int msglen;
1026         char *log_file, *logrec;
1027         const char *committer;
1028
1029         if (log_all_ref_updates < 0)
1030                 log_all_ref_updates = !is_bare_repository();
1031
1032         log_file = git_path("logs/%s", ref_name);
1033
1034         if (log_all_ref_updates &&
1035             (!prefixcmp(ref_name, "refs/heads/") ||
1036              !prefixcmp(ref_name, "refs/remotes/") ||
1037              !strcmp(ref_name, "HEAD"))) {
1038                 if (safe_create_leading_directories(log_file) < 0)
1039                         return error("unable to create directory for %s",
1040                                      log_file);
1041                 oflags |= O_CREAT;
1042         }
1043
1044         logfd = open(log_file, oflags, 0666);
1045         if (logfd < 0) {
1046                 if (!(oflags & O_CREAT) && errno == ENOENT)
1047                         return 0;
1048
1049                 if ((oflags & O_CREAT) && errno == EISDIR) {
1050                         if (remove_empty_directories(log_file)) {
1051                                 return error("There are still logs under '%s'",
1052                                              log_file);
1053                         }
1054                         logfd = open(log_file, oflags, 0666);
1055                 }
1056
1057                 if (logfd < 0)
1058                         return error("Unable to append to %s: %s",
1059                                      log_file, strerror(errno));
1060         }
1061
1062         adjust_shared_perm(log_file);
1063
1064         msglen = 0;
1065         if (msg) {
1066                 /* clean up the message and make sure it is a single line */
1067                 for ( ; *msg; msg++)
1068                         if (!isspace(*msg))
1069                                 break;
1070                 if (*msg) {
1071                         const char *ep = strchr(msg, '\n');
1072                         if (ep)
1073                                 msglen = ep - msg;
1074                         else
1075                                 msglen = strlen(msg);
1076                 }
1077         }
1078
1079         committer = git_committer_info(-1);
1080         maxlen = strlen(committer) + msglen + 100;
1081         logrec = xmalloc(maxlen);
1082         len = sprintf(logrec, "%s %s %s\n",
1083                       sha1_to_hex(old_sha1),
1084                       sha1_to_hex(new_sha1),
1085                       committer);
1086         if (msglen)
1087                 len += sprintf(logrec + len - 1, "\t%.*s\n", msglen, msg) - 1;
1088         written = len <= maxlen ? write_in_full(logfd, logrec, len) : -1;
1089         free(logrec);
1090         close(logfd);
1091         if (written != len)
1092                 return error("Unable to append to %s", log_file);
1093         return 0;
1094 }
1095
1096 int write_ref_sha1(struct ref_lock *lock,
1097         const unsigned char *sha1, const char *logmsg)
1098 {
1099         static char term = '\n';
1100
1101         if (!lock)
1102                 return -1;
1103         if (!lock->force_write && !hashcmp(lock->old_sha1, sha1)) {
1104                 unlock_ref(lock);
1105                 return 0;
1106         }
1107         if (write_in_full(lock->lock_fd, sha1_to_hex(sha1), 40) != 40 ||
1108             write_in_full(lock->lock_fd, &term, 1) != 1
1109                 || close(lock->lock_fd) < 0) {
1110                 error("Couldn't write %s", lock->lk->filename);
1111                 unlock_ref(lock);
1112                 return -1;
1113         }
1114         invalidate_cached_refs();
1115         if (log_ref_write(lock->ref_name, lock->old_sha1, sha1, logmsg) < 0 ||
1116             (strcmp(lock->ref_name, lock->orig_ref_name) &&
1117              log_ref_write(lock->orig_ref_name, lock->old_sha1, sha1, logmsg) < 0)) {
1118                 unlock_ref(lock);
1119                 return -1;
1120         }
1121         if (strcmp(lock->orig_ref_name, "HEAD") != 0) {
1122                 /*
1123                  * Special hack: If a branch is updated directly and HEAD
1124                  * points to it (may happen on the remote side of a push
1125                  * for example) then logically the HEAD reflog should be
1126                  * updated too.
1127                  * A generic solution implies reverse symref information,
1128                  * but finding all symrefs pointing to the given branch
1129                  * would be rather costly for this rare event (the direct
1130                  * update of a branch) to be worth it.  So let's cheat and
1131                  * check with HEAD only which should cover 99% of all usage
1132                  * scenarios (even 100% of the default ones).
1133                  */
1134                 unsigned char head_sha1[20];
1135                 int head_flag;
1136                 const char *head_ref;
1137                 head_ref = resolve_ref("HEAD", head_sha1, 1, &head_flag);
1138                 if (head_ref && (head_flag & REF_ISSYMREF) &&
1139                     !strcmp(head_ref, lock->ref_name))
1140                         log_ref_write("HEAD", lock->old_sha1, sha1, logmsg);
1141         }
1142         if (commit_lock_file(lock->lk)) {
1143                 error("Couldn't set %s", lock->ref_name);
1144                 unlock_ref(lock);
1145                 return -1;
1146         }
1147         lock->lock_fd = -1;
1148         unlock_ref(lock);
1149         return 0;
1150 }
1151
1152 int create_symref(const char *ref_target, const char *refs_heads_master,
1153                   const char *logmsg)
1154 {
1155         const char *lockpath;
1156         char ref[1000];
1157         int fd, len, written;
1158         char *git_HEAD = xstrdup(git_path("%s", ref_target));
1159         unsigned char old_sha1[20], new_sha1[20];
1160
1161         if (logmsg && read_ref(ref_target, old_sha1))
1162                 hashclr(old_sha1);
1163
1164         if (safe_create_leading_directories(git_HEAD) < 0)
1165                 return error("unable to create directory for %s", git_HEAD);
1166
1167 #ifndef NO_SYMLINK_HEAD
1168         if (prefer_symlink_refs) {
1169                 unlink(git_HEAD);
1170                 if (!symlink(refs_heads_master, git_HEAD))
1171                         goto done;
1172                 fprintf(stderr, "no symlink - falling back to symbolic ref\n");
1173         }
1174 #endif
1175
1176         len = snprintf(ref, sizeof(ref), "ref: %s\n", refs_heads_master);
1177         if (sizeof(ref) <= len) {
1178                 error("refname too long: %s", refs_heads_master);
1179                 goto error_free_return;
1180         }
1181         lockpath = mkpath("%s.lock", git_HEAD);
1182         fd = open(lockpath, O_CREAT | O_EXCL | O_WRONLY, 0666);
1183         if (fd < 0) {
1184                 error("Unable to open %s for writing", lockpath);
1185                 goto error_free_return;
1186         }
1187         written = write_in_full(fd, ref, len);
1188         close(fd);
1189         if (written != len) {
1190                 error("Unable to write to %s", lockpath);
1191                 goto error_unlink_return;
1192         }
1193         if (rename(lockpath, git_HEAD) < 0) {
1194                 error("Unable to create %s", git_HEAD);
1195                 goto error_unlink_return;
1196         }
1197         if (adjust_shared_perm(git_HEAD)) {
1198                 error("Unable to fix permissions on %s", lockpath);
1199         error_unlink_return:
1200                 unlink(lockpath);
1201         error_free_return:
1202                 free(git_HEAD);
1203                 return -1;
1204         }
1205
1206 #ifndef NO_SYMLINK_HEAD
1207         done:
1208 #endif
1209         if (logmsg && !read_ref(refs_heads_master, new_sha1))
1210                 log_ref_write(ref_target, old_sha1, new_sha1, logmsg);
1211
1212         free(git_HEAD);
1213         return 0;
1214 }
1215
1216 static char *ref_msg(const char *line, const char *endp)
1217 {
1218         const char *ep;
1219         char *msg;
1220
1221         line += 82;
1222         for (ep = line; ep < endp && *ep != '\n'; ep++)
1223                 ;
1224         msg = xmalloc(ep - line + 1);
1225         memcpy(msg, line, ep - line);
1226         msg[ep - line] = 0;
1227         return msg;
1228 }
1229
1230 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)
1231 {
1232         const char *logfile, *logdata, *logend, *rec, *lastgt, *lastrec;
1233         char *tz_c;
1234         int logfd, tz, reccnt = 0;
1235         struct stat st;
1236         unsigned long date;
1237         unsigned char logged_sha1[20];
1238         void *log_mapped;
1239         size_t mapsz;
1240
1241         logfile = git_path("logs/%s", ref);
1242         logfd = open(logfile, O_RDONLY, 0);
1243         if (logfd < 0)
1244                 die("Unable to read log %s: %s", logfile, strerror(errno));
1245         fstat(logfd, &st);
1246         if (!st.st_size)
1247                 die("Log %s is empty.", logfile);
1248         mapsz = xsize_t(st.st_size);
1249         log_mapped = xmmap(NULL, mapsz, PROT_READ, MAP_PRIVATE, logfd, 0);
1250         logdata = log_mapped;
1251         close(logfd);
1252
1253         lastrec = NULL;
1254         rec = logend = logdata + st.st_size;
1255         while (logdata < rec) {
1256                 reccnt++;
1257                 if (logdata < rec && *(rec-1) == '\n')
1258                         rec--;
1259                 lastgt = NULL;
1260                 while (logdata < rec && *(rec-1) != '\n') {
1261                         rec--;
1262                         if (*rec == '>')
1263                                 lastgt = rec;
1264                 }
1265                 if (!lastgt)
1266                         die("Log %s is corrupt.", logfile);
1267                 date = strtoul(lastgt + 1, &tz_c, 10);
1268                 if (date <= at_time || cnt == 0) {
1269                         tz = strtoul(tz_c, NULL, 10);
1270                         if (msg)
1271                                 *msg = ref_msg(rec, logend);
1272                         if (cutoff_time)
1273                                 *cutoff_time = date;
1274                         if (cutoff_tz)
1275                                 *cutoff_tz = tz;
1276                         if (cutoff_cnt)
1277                                 *cutoff_cnt = reccnt - 1;
1278                         if (lastrec) {
1279                                 if (get_sha1_hex(lastrec, logged_sha1))
1280                                         die("Log %s is corrupt.", logfile);
1281                                 if (get_sha1_hex(rec + 41, sha1))
1282                                         die("Log %s is corrupt.", logfile);
1283                                 if (hashcmp(logged_sha1, sha1)) {
1284                                         fprintf(stderr,
1285                                                 "warning: Log %s has gap after %s.\n",
1286                                                 logfile, show_rfc2822_date(date, tz));
1287                                 }
1288                         }
1289                         else if (date == at_time) {
1290                                 if (get_sha1_hex(rec + 41, sha1))
1291                                         die("Log %s is corrupt.", logfile);
1292                         }
1293                         else {
1294                                 if (get_sha1_hex(rec + 41, logged_sha1))
1295                                         die("Log %s is corrupt.", logfile);
1296                                 if (hashcmp(logged_sha1, sha1)) {
1297                                         fprintf(stderr,
1298                                                 "warning: Log %s unexpectedly ended on %s.\n",
1299                                                 logfile, show_rfc2822_date(date, tz));
1300                                 }
1301                         }
1302                         munmap(log_mapped, mapsz);
1303                         return 0;
1304                 }
1305                 lastrec = rec;
1306                 if (cnt > 0)
1307                         cnt--;
1308         }
1309
1310         rec = logdata;
1311         while (rec < logend && *rec != '>' && *rec != '\n')
1312                 rec++;
1313         if (rec == logend || *rec == '\n')
1314                 die("Log %s is corrupt.", logfile);
1315         date = strtoul(rec + 1, &tz_c, 10);
1316         tz = strtoul(tz_c, NULL, 10);
1317         if (get_sha1_hex(logdata, sha1))
1318                 die("Log %s is corrupt.", logfile);
1319         if (msg)
1320                 *msg = ref_msg(logdata, logend);
1321         munmap(log_mapped, mapsz);
1322
1323         if (cutoff_time)
1324                 *cutoff_time = date;
1325         if (cutoff_tz)
1326                 *cutoff_tz = tz;
1327         if (cutoff_cnt)
1328                 *cutoff_cnt = reccnt;
1329         return 1;
1330 }
1331
1332 int for_each_reflog_ent(const char *ref, each_reflog_ent_fn fn, void *cb_data)
1333 {
1334         const char *logfile;
1335         FILE *logfp;
1336         char buf[1024];
1337         int ret = 0;
1338
1339         logfile = git_path("logs/%s", ref);
1340         logfp = fopen(logfile, "r");
1341         if (!logfp)
1342                 return -1;
1343         while (fgets(buf, sizeof(buf), logfp)) {
1344                 unsigned char osha1[20], nsha1[20];
1345                 char *email_end, *message;
1346                 unsigned long timestamp;
1347                 int len, tz;
1348
1349                 /* old SP new SP name <email> SP time TAB msg LF */
1350                 len = strlen(buf);
1351                 if (len < 83 || buf[len-1] != '\n' ||
1352                     get_sha1_hex(buf, osha1) || buf[40] != ' ' ||
1353                     get_sha1_hex(buf + 41, nsha1) || buf[81] != ' ' ||
1354                     !(email_end = strchr(buf + 82, '>')) ||
1355                     email_end[1] != ' ' ||
1356                     !(timestamp = strtoul(email_end + 2, &message, 10)) ||
1357                     !message || message[0] != ' ' ||
1358                     (message[1] != '+' && message[1] != '-') ||
1359                     !isdigit(message[2]) || !isdigit(message[3]) ||
1360                     !isdigit(message[4]) || !isdigit(message[5]))
1361                         continue; /* corrupt? */
1362                 email_end[1] = '\0';
1363                 tz = strtol(message + 1, NULL, 10);
1364                 if (message[6] != '\t')
1365                         message += 6;
1366                 else
1367                         message += 7;
1368                 ret = fn(osha1, nsha1, buf+82, timestamp, tz, message, cb_data);
1369                 if (ret)
1370                         break;
1371         }
1372         fclose(logfp);
1373         return ret;
1374 }
1375
1376 static int do_for_each_reflog(const char *base, each_ref_fn fn, void *cb_data)
1377 {
1378         DIR *dir = opendir(git_path("logs/%s", base));
1379         int retval = 0;
1380
1381         if (dir) {
1382                 struct dirent *de;
1383                 int baselen = strlen(base);
1384                 char *log = xmalloc(baselen + 257);
1385
1386                 memcpy(log, base, baselen);
1387                 if (baselen && base[baselen-1] != '/')
1388                         log[baselen++] = '/';
1389
1390                 while ((de = readdir(dir)) != NULL) {
1391                         struct stat st;
1392                         int namelen;
1393
1394                         if (de->d_name[0] == '.')
1395                                 continue;
1396                         namelen = strlen(de->d_name);
1397                         if (namelen > 255)
1398                                 continue;
1399                         if (has_extension(de->d_name, ".lock"))
1400                                 continue;
1401                         memcpy(log + baselen, de->d_name, namelen+1);
1402                         if (stat(git_path("logs/%s", log), &st) < 0)
1403                                 continue;
1404                         if (S_ISDIR(st.st_mode)) {
1405                                 retval = do_for_each_reflog(log, fn, cb_data);
1406                         } else {
1407                                 unsigned char sha1[20];
1408                                 if (!resolve_ref(log, sha1, 0, NULL))
1409                                         retval = error("bad ref for %s", log);
1410                                 else
1411                                         retval = fn(log, sha1, 0, cb_data);
1412                         }
1413                         if (retval)
1414                                 break;
1415                 }
1416                 free(log);
1417                 closedir(dir);
1418         }
1419         else if (*base)
1420                 return errno;
1421         return retval;
1422 }
1423
1424 int for_each_reflog(each_ref_fn fn, void *cb_data)
1425 {
1426         return do_for_each_reflog("", fn, cb_data);
1427 }