apply delta depth bias to already deltified objects
[git] / refs.c
1 #include "cache.h"
2 #include "refs.h"
3 #include "object.h"
4 #include "tag.h"
5
6 /* ISSYMREF=01 and ISPACKED=02 are public interfaces */
7 #define REF_KNOWS_PEELED 04
8
9 struct ref_list {
10         struct ref_list *next;
11         unsigned char flag; /* ISSYMREF? ISPACKED? */
12         unsigned char sha1[20];
13         unsigned char peeled[20];
14         char name[FLEX_ARRAY];
15 };
16
17 static const char *parse_ref_line(char *line, unsigned char *sha1)
18 {
19         /*
20          * 42: the answer to everything.
21          *
22          * In this case, it happens to be the answer to
23          *  40 (length of sha1 hex representation)
24          *  +1 (space in between hex and name)
25          *  +1 (newline at the end of the line)
26          */
27         int len = strlen(line) - 42;
28
29         if (len <= 0)
30                 return NULL;
31         if (get_sha1_hex(line, sha1) < 0)
32                 return NULL;
33         if (!isspace(line[40]))
34                 return NULL;
35         line += 41;
36         if (isspace(*line))
37                 return NULL;
38         if (line[len] != '\n')
39                 return NULL;
40         line[len] = 0;
41
42         return line;
43 }
44
45 static struct ref_list *add_ref(const char *name, const unsigned char *sha1,
46                                 int flag, struct ref_list *list,
47                                 struct ref_list **new_entry)
48 {
49         int len;
50         struct ref_list *entry;
51
52         /* Allocate it and add it in.. */
53         len = strlen(name) + 1;
54         entry = xmalloc(sizeof(struct ref_list) + len);
55         hashcpy(entry->sha1, sha1);
56         hashclr(entry->peeled);
57         memcpy(entry->name, name, len);
58         entry->flag = flag;
59         entry->next = list;
60         if (new_entry)
61                 *new_entry = entry;
62         return entry;
63 }
64
65 /* merge sort the ref list */
66 static struct ref_list *sort_ref_list(struct ref_list *list)
67 {
68         int psize, qsize, last_merge_count, cmp;
69         struct ref_list *p, *q, *l, *e;
70         struct ref_list *new_list = list;
71         int k = 1;
72         int merge_count = 0;
73
74         if (!list)
75                 return list;
76
77         do {
78                 last_merge_count = merge_count;
79                 merge_count = 0;
80
81                 psize = 0;
82
83                 p = new_list;
84                 q = new_list;
85                 new_list = NULL;
86                 l = NULL;
87
88                 while (p) {
89                         merge_count++;
90
91                         while (psize < k && q->next) {
92                                 q = q->next;
93                                 psize++;
94                         }
95                         qsize = k;
96
97                         while ((psize > 0) || (qsize > 0 && q)) {
98                                 if (qsize == 0 || !q) {
99                                         e = p;
100                                         p = p->next;
101                                         psize--;
102                                 } else if (psize == 0) {
103                                         e = q;
104                                         q = q->next;
105                                         qsize--;
106                                 } else {
107                                         cmp = strcmp(q->name, p->name);
108                                         if (cmp < 0) {
109                                                 e = q;
110                                                 q = q->next;
111                                                 qsize--;
112                                         } else if (cmp > 0) {
113                                                 e = p;
114                                                 p = p->next;
115                                                 psize--;
116                                         } else {
117                                                 if (hashcmp(q->sha1, p->sha1))
118                                                         die("Duplicated ref, and SHA1s don't match: %s",
119                                                             q->name);
120                                                 warning("Duplicated ref: %s", q->name);
121                                                 e = q;
122                                                 q = q->next;
123                                                 qsize--;
124                                                 free(e);
125                                                 e = p;
126                                                 p = p->next;
127                                                 psize--;
128                                         }
129                                 }
130
131                                 e->next = NULL;
132
133                                 if (l)
134                                         l->next = e;
135                                 if (!new_list)
136                                         new_list = e;
137                                 l = e;
138                         }
139
140                         p = q;
141                 };
142
143                 k = k * 2;
144         } while ((last_merge_count != merge_count) || (last_merge_count != 1));
145
146         return new_list;
147 }
148
149 /*
150  * Future: need to be in "struct repository"
151  * when doing a full libification.
152  */
153 static struct cached_refs {
154         char did_loose;
155         char did_packed;
156         struct ref_list *loose;
157         struct ref_list *packed;
158 } cached_refs;
159
160 static void free_ref_list(struct ref_list *list)
161 {
162         struct ref_list *next;
163         for ( ; list; list = next) {
164                 next = list->next;
165                 free(list);
166         }
167 }
168
169 static void invalidate_cached_refs(void)
170 {
171         struct cached_refs *ca = &cached_refs;
172
173         if (ca->did_loose && ca->loose)
174                 free_ref_list(ca->loose);
175         if (ca->did_packed && ca->packed)
176                 free_ref_list(ca->packed);
177         ca->loose = ca->packed = NULL;
178         ca->did_loose = ca->did_packed = 0;
179 }
180
181 static void read_packed_refs(FILE *f, struct cached_refs *cached_refs)
182 {
183         struct ref_list *list = NULL;
184         struct ref_list *last = NULL;
185         char refline[PATH_MAX];
186         int flag = REF_ISPACKED;
187
188         while (fgets(refline, sizeof(refline), f)) {
189                 unsigned char sha1[20];
190                 const char *name;
191                 static const char header[] = "# pack-refs with:";
192
193                 if (!strncmp(refline, header, sizeof(header)-1)) {
194                         const char *traits = refline + sizeof(header) - 1;
195                         if (strstr(traits, " peeled "))
196                                 flag |= REF_KNOWS_PEELED;
197                         /* perhaps other traits later as well */
198                         continue;
199                 }
200
201                 name = parse_ref_line(refline, sha1);
202                 if (name) {
203                         list = add_ref(name, sha1, flag, list, &last);
204                         continue;
205                 }
206                 if (last &&
207                     refline[0] == '^' &&
208                     strlen(refline) == 42 &&
209                     refline[41] == '\n' &&
210                     !get_sha1_hex(refline + 1, sha1))
211                         hashcpy(last->peeled, sha1);
212         }
213         cached_refs->packed = sort_ref_list(list);
214 }
215
216 static struct ref_list *get_packed_refs(void)
217 {
218         if (!cached_refs.did_packed) {
219                 FILE *f = fopen(git_path("packed-refs"), "r");
220                 cached_refs.packed = NULL;
221                 if (f) {
222                         read_packed_refs(f, &cached_refs);
223                         fclose(f);
224                 }
225                 cached_refs.did_packed = 1;
226         }
227         return cached_refs.packed;
228 }
229
230 static struct ref_list *get_ref_dir(const char *base, struct ref_list *list)
231 {
232         DIR *dir = opendir(git_path("%s", base));
233
234         if (dir) {
235                 struct dirent *de;
236                 int baselen = strlen(base);
237                 char *ref = xmalloc(baselen + 257);
238
239                 memcpy(ref, base, baselen);
240                 if (baselen && base[baselen-1] != '/')
241                         ref[baselen++] = '/';
242
243                 while ((de = readdir(dir)) != NULL) {
244                         unsigned char sha1[20];
245                         struct stat st;
246                         int flag;
247                         int namelen;
248
249                         if (de->d_name[0] == '.')
250                                 continue;
251                         namelen = strlen(de->d_name);
252                         if (namelen > 255)
253                                 continue;
254                         if (has_extension(de->d_name, ".lock"))
255                                 continue;
256                         memcpy(ref + baselen, de->d_name, namelen+1);
257                         if (stat(git_path("%s", ref), &st) < 0)
258                                 continue;
259                         if (S_ISDIR(st.st_mode)) {
260                                 list = get_ref_dir(ref, list);
261                                 continue;
262                         }
263                         if (!resolve_ref(ref, sha1, 1, &flag)) {
264                                 error("%s points nowhere!", ref);
265                                 continue;
266                         }
267                         list = add_ref(ref, sha1, flag, list, NULL);
268                 }
269                 free(ref);
270                 closedir(dir);
271         }
272         return sort_ref_list(list);
273 }
274
275 static struct ref_list *get_loose_refs(void)
276 {
277         if (!cached_refs.did_loose) {
278                 cached_refs.loose = get_ref_dir("refs", NULL);
279                 cached_refs.did_loose = 1;
280         }
281         return cached_refs.loose;
282 }
283
284 /* We allow "recursive" symbolic refs. Only within reason, though */
285 #define MAXDEPTH 5
286 #define MAXREFLEN (1024)
287
288 static int resolve_gitlink_packed_ref(char *name, int pathlen, const char *refname, unsigned char *result)
289 {
290         FILE *f;
291         struct cached_refs refs;
292         struct ref_list *ref;
293         int retval;
294
295         strcpy(name + pathlen, "packed-refs");
296         f = fopen(name, "r");
297         if (!f)
298                 return -1;
299         read_packed_refs(f, &refs);
300         fclose(f);
301         ref = refs.packed;
302         retval = -1;
303         while (ref) {
304                 if (!strcmp(ref->name, refname)) {
305                         retval = 0;
306                         memcpy(result, ref->sha1, 20);
307                         break;
308                 }
309                 ref = ref->next;
310         }
311         free_ref_list(refs.packed);
312         return retval;
313 }
314
315 static int resolve_gitlink_ref_recursive(char *name, int pathlen, const char *refname, unsigned char *result, int recursion)
316 {
317         int fd, len = strlen(refname);
318         char buffer[128], *p;
319
320         if (recursion > MAXDEPTH || len > MAXREFLEN)
321                 return -1;
322         memcpy(name + pathlen, refname, len+1);
323         fd = open(name, O_RDONLY);
324         if (fd < 0)
325                 return resolve_gitlink_packed_ref(name, pathlen, refname, result);
326
327         len = read(fd, buffer, sizeof(buffer)-1);
328         close(fd);
329         if (len < 0)
330                 return -1;
331         while (len && isspace(buffer[len-1]))
332                 len--;
333         buffer[len] = 0;
334
335         /* Was it a detached head or an old-fashioned symlink? */
336         if (!get_sha1_hex(buffer, result))
337                 return 0;
338
339         /* Symref? */
340         if (strncmp(buffer, "ref:", 4))
341                 return -1;
342         p = buffer + 4;
343         while (isspace(*p))
344                 p++;
345
346         return resolve_gitlink_ref_recursive(name, pathlen, p, result, recursion+1);
347 }
348
349 int resolve_gitlink_ref(const char *path, const char *refname, unsigned char *result)
350 {
351         int len = strlen(path), retval;
352         char *gitdir;
353
354         while (len && path[len-1] == '/')
355                 len--;
356         if (!len)
357                 return -1;
358         gitdir = xmalloc(len + MAXREFLEN + 8);
359         memcpy(gitdir, path, len);
360         memcpy(gitdir + len, "/.git/", 7);
361
362         retval = resolve_gitlink_ref_recursive(gitdir, len+6, refname, result, 0);
363         free(gitdir);
364         return retval;
365 }
366
367 const char *resolve_ref(const char *ref, unsigned char *sha1, int reading, int *flag)
368 {
369         int depth = MAXDEPTH, len;
370         char buffer[256];
371         static char ref_buffer[256];
372
373         if (flag)
374                 *flag = 0;
375
376         for (;;) {
377                 const char *path = git_path("%s", ref);
378                 struct stat st;
379                 char *buf;
380                 int fd;
381
382                 if (--depth < 0)
383                         return NULL;
384
385                 /* Special case: non-existing file.
386                  * Not having the refs/heads/new-branch is OK
387                  * if we are writing into it, so is .git/HEAD
388                  * that points at refs/heads/master still to be
389                  * born.  It is NOT OK if we are resolving for
390                  * reading.
391                  */
392                 if (lstat(path, &st) < 0) {
393                         struct ref_list *list = get_packed_refs();
394                         while (list) {
395                                 if (!strcmp(ref, list->name)) {
396                                         hashcpy(sha1, list->sha1);
397                                         if (flag)
398                                                 *flag |= REF_ISPACKED;
399                                         return ref;
400                                 }
401                                 list = list->next;
402                         }
403                         if (reading || errno != ENOENT)
404                                 return NULL;
405                         hashclr(sha1);
406                         return ref;
407                 }
408
409                 /* Follow "normalized" - ie "refs/.." symlinks by hand */
410                 if (S_ISLNK(st.st_mode)) {
411                         len = readlink(path, buffer, sizeof(buffer)-1);
412                         if (len >= 5 && !memcmp("refs/", buffer, 5)) {
413                                 buffer[len] = 0;
414                                 strcpy(ref_buffer, buffer);
415                                 ref = ref_buffer;
416                                 if (flag)
417                                         *flag |= REF_ISSYMREF;
418                                 continue;
419                         }
420                 }
421
422                 /* Is it a directory? */
423                 if (S_ISDIR(st.st_mode)) {
424                         errno = EISDIR;
425                         return NULL;
426                 }
427
428                 /*
429                  * Anything else, just open it and try to use it as
430                  * a ref
431                  */
432                 fd = open(path, O_RDONLY);
433                 if (fd < 0)
434                         return NULL;
435                 len = read_in_full(fd, buffer, sizeof(buffer)-1);
436                 close(fd);
437
438                 /*
439                  * Is it a symbolic ref?
440                  */
441                 if (len < 4 || memcmp("ref:", buffer, 4))
442                         break;
443                 buf = buffer + 4;
444                 len -= 4;
445                 while (len && isspace(*buf))
446                         buf++, len--;
447                 while (len && isspace(buf[len-1]))
448                         len--;
449                 buf[len] = 0;
450                 memcpy(ref_buffer, buf, len + 1);
451                 ref = ref_buffer;
452                 if (flag)
453                         *flag |= REF_ISSYMREF;
454         }
455         if (len < 40 || get_sha1_hex(buffer, sha1))
456                 return NULL;
457         return ref;
458 }
459
460 int read_ref(const char *ref, unsigned char *sha1)
461 {
462         if (resolve_ref(ref, sha1, 1, NULL))
463                 return 0;
464         return -1;
465 }
466
467 static int do_one_ref(const char *base, each_ref_fn fn, int trim,
468                       void *cb_data, struct ref_list *entry)
469 {
470         if (strncmp(base, entry->name, trim))
471                 return 0;
472         if (is_null_sha1(entry->sha1))
473                 return 0;
474         if (!has_sha1_file(entry->sha1)) {
475                 error("%s does not point to a valid object!", entry->name);
476                 return 0;
477         }
478         return fn(entry->name + trim, entry->sha1, entry->flag, cb_data);
479 }
480
481 int peel_ref(const char *ref, unsigned char *sha1)
482 {
483         int flag;
484         unsigned char base[20];
485         struct object *o;
486
487         if (!resolve_ref(ref, base, 1, &flag))
488                 return -1;
489
490         if ((flag & REF_ISPACKED)) {
491                 struct ref_list *list = get_packed_refs();
492
493                 while (list) {
494                         if (!strcmp(list->name, ref)) {
495                                 if (list->flag & REF_KNOWS_PEELED) {
496                                         hashcpy(sha1, list->peeled);
497                                         return 0;
498                                 }
499                                 /* older pack-refs did not leave peeled ones */
500                                 break;
501                         }
502                         list = list->next;
503                 }
504         }
505
506         /* fallback - callers should not call this for unpacked refs */
507         o = parse_object(base);
508         if (o->type == OBJ_TAG) {
509                 o = deref_tag(o, ref, 0);
510                 if (o) {
511                         hashcpy(sha1, o->sha1);
512                         return 0;
513                 }
514         }
515         return -1;
516 }
517
518 static int do_for_each_ref(const char *base, each_ref_fn fn, int trim,
519                            void *cb_data)
520 {
521         int retval;
522         struct ref_list *packed = get_packed_refs();
523         struct ref_list *loose = get_loose_refs();
524
525         while (packed && loose) {
526                 struct ref_list *entry;
527                 int cmp = strcmp(packed->name, loose->name);
528                 if (!cmp) {
529                         packed = packed->next;
530                         continue;
531                 }
532                 if (cmp > 0) {
533                         entry = loose;
534                         loose = loose->next;
535                 } else {
536                         entry = packed;
537                         packed = packed->next;
538                 }
539                 retval = do_one_ref(base, fn, trim, cb_data, entry);
540                 if (retval)
541                         return retval;
542         }
543
544         for (packed = packed ? packed : loose; packed; packed = packed->next) {
545                 retval = do_one_ref(base, fn, trim, cb_data, packed);
546                 if (retval)
547                         return retval;
548         }
549         return 0;
550 }
551
552 int head_ref(each_ref_fn fn, void *cb_data)
553 {
554         unsigned char sha1[20];
555         int flag;
556
557         if (resolve_ref("HEAD", sha1, 1, &flag))
558                 return fn("HEAD", sha1, flag, cb_data);
559         return 0;
560 }
561
562 int for_each_ref(each_ref_fn fn, void *cb_data)
563 {
564         return do_for_each_ref("refs/", fn, 0, cb_data);
565 }
566
567 int for_each_tag_ref(each_ref_fn fn, void *cb_data)
568 {
569         return do_for_each_ref("refs/tags/", fn, 10, cb_data);
570 }
571
572 int for_each_branch_ref(each_ref_fn fn, void *cb_data)
573 {
574         return do_for_each_ref("refs/heads/", fn, 11, cb_data);
575 }
576
577 int for_each_remote_ref(each_ref_fn fn, void *cb_data)
578 {
579         return do_for_each_ref("refs/remotes/", fn, 13, cb_data);
580 }
581
582 /* NEEDSWORK: This is only used by ssh-upload and it should go; the
583  * caller should do resolve_ref or read_ref like everybody else.  Or
584  * maybe everybody else should use get_ref_sha1() instead of doing
585  * read_ref().
586  */
587 int get_ref_sha1(const char *ref, unsigned char *sha1)
588 {
589         if (check_ref_format(ref))
590                 return -1;
591         return read_ref(mkpath("refs/%s", ref), sha1);
592 }
593
594 /*
595  * Make sure "ref" is something reasonable to have under ".git/refs/";
596  * We do not like it if:
597  *
598  * - any path component of it begins with ".", or
599  * - it has double dots "..", or
600  * - it has ASCII control character, "~", "^", ":" or SP, anywhere, or
601  * - it ends with a "/".
602  */
603
604 static inline int bad_ref_char(int ch)
605 {
606         if (((unsigned) ch) <= ' ' ||
607             ch == '~' || ch == '^' || ch == ':')
608                 return 1;
609         /* 2.13 Pattern Matching Notation */
610         if (ch == '?' || ch == '[') /* Unsupported */
611                 return 1;
612         if (ch == '*') /* Supported at the end */
613                 return 2;
614         return 0;
615 }
616
617 int check_ref_format(const char *ref)
618 {
619         int ch, level, bad_type;
620         const char *cp = ref;
621
622         level = 0;
623         while (1) {
624                 while ((ch = *cp++) == '/')
625                         ; /* tolerate duplicated slashes */
626                 if (!ch)
627                         return -1; /* should not end with slashes */
628
629                 /* we are at the beginning of the path component */
630                 if (ch == '.')
631                         return -1;
632                 bad_type = bad_ref_char(ch);
633                 if (bad_type) {
634                         return (bad_type == 2 && !*cp) ? -3 : -1;
635                 }
636
637                 /* scan the rest of the path component */
638                 while ((ch = *cp++) != 0) {
639                         bad_type = bad_ref_char(ch);
640                         if (bad_type) {
641                                 return (bad_type == 2 && !*cp) ? -3 : -1;
642                         }
643                         if (ch == '/')
644                                 break;
645                         if (ch == '.' && *cp == '.')
646                                 return -1;
647                 }
648                 level++;
649                 if (!ch) {
650                         if (level < 2)
651                                 return -2; /* at least of form "heads/blah" */
652                         return 0;
653                 }
654         }
655 }
656
657 static struct ref_lock *verify_lock(struct ref_lock *lock,
658         const unsigned char *old_sha1, int mustexist)
659 {
660         if (!resolve_ref(lock->ref_name, lock->old_sha1, mustexist, NULL)) {
661                 error("Can't verify ref %s", lock->ref_name);
662                 unlock_ref(lock);
663                 return NULL;
664         }
665         if (hashcmp(lock->old_sha1, old_sha1)) {
666                 error("Ref %s is at %s but expected %s", lock->ref_name,
667                         sha1_to_hex(lock->old_sha1), sha1_to_hex(old_sha1));
668                 unlock_ref(lock);
669                 return NULL;
670         }
671         return lock;
672 }
673
674 static int remove_empty_dir_recursive(char *path, int len)
675 {
676         DIR *dir = opendir(path);
677         struct dirent *e;
678         int ret = 0;
679
680         if (!dir)
681                 return -1;
682         if (path[len-1] != '/')
683                 path[len++] = '/';
684         while ((e = readdir(dir)) != NULL) {
685                 struct stat st;
686                 int namlen;
687                 if ((e->d_name[0] == '.') &&
688                     ((e->d_name[1] == 0) ||
689                      ((e->d_name[1] == '.') && e->d_name[2] == 0)))
690                         continue; /* "." and ".." */
691
692                 namlen = strlen(e->d_name);
693                 if ((len + namlen < PATH_MAX) &&
694                     strcpy(path + len, e->d_name) &&
695                     !lstat(path, &st) &&
696                     S_ISDIR(st.st_mode) &&
697                     !remove_empty_dir_recursive(path, len + namlen))
698                         continue; /* happy */
699
700                 /* path too long, stat fails, or non-directory still exists */
701                 ret = -1;
702                 break;
703         }
704         closedir(dir);
705         if (!ret) {
706                 path[len] = 0;
707                 ret = rmdir(path);
708         }
709         return ret;
710 }
711
712 static int remove_empty_directories(char *file)
713 {
714         /* we want to create a file but there is a directory there;
715          * if that is an empty directory (or a directory that contains
716          * only empty directories), remove them.
717          */
718         char path[PATH_MAX];
719         int len = strlen(file);
720
721         if (len >= PATH_MAX) /* path too long ;-) */
722                 return -1;
723         strcpy(path, file);
724         return remove_empty_dir_recursive(path, len);
725 }
726
727 static int is_refname_available(const char *ref, const char *oldref,
728                                 struct ref_list *list, int quiet)
729 {
730         int namlen = strlen(ref); /* e.g. 'foo/bar' */
731         while (list) {
732                 /* list->name could be 'foo' or 'foo/bar/baz' */
733                 if (!oldref || strcmp(oldref, list->name)) {
734                         int len = strlen(list->name);
735                         int cmplen = (namlen < len) ? namlen : len;
736                         const char *lead = (namlen < len) ? list->name : ref;
737                         if (!strncmp(ref, list->name, cmplen) &&
738                             lead[cmplen] == '/') {
739                                 if (!quiet)
740                                         error("'%s' exists; cannot create '%s'",
741                                               list->name, ref);
742                                 return 0;
743                         }
744                 }
745                 list = list->next;
746         }
747         return 1;
748 }
749
750 static struct ref_lock *lock_ref_sha1_basic(const char *ref, const unsigned char *old_sha1, int flags, int *type_p)
751 {
752         char *ref_file;
753         const char *orig_ref = ref;
754         struct ref_lock *lock;
755         struct stat st;
756         int last_errno = 0;
757         int type;
758         int mustexist = (old_sha1 && !is_null_sha1(old_sha1));
759
760         lock = xcalloc(1, sizeof(struct ref_lock));
761         lock->lock_fd = -1;
762
763         ref = resolve_ref(ref, lock->old_sha1, mustexist, &type);
764         if (!ref && errno == EISDIR) {
765                 /* we are trying to lock foo but we used to
766                  * have foo/bar which now does not exist;
767                  * it is normal for the empty directory 'foo'
768                  * to remain.
769                  */
770                 ref_file = git_path("%s", orig_ref);
771                 if (remove_empty_directories(ref_file)) {
772                         last_errno = errno;
773                         error("there are still refs under '%s'", orig_ref);
774                         goto error_return;
775                 }
776                 ref = resolve_ref(orig_ref, lock->old_sha1, mustexist, &type);
777         }
778         if (type_p)
779             *type_p = type;
780         if (!ref) {
781                 last_errno = errno;
782                 error("unable to resolve reference %s: %s",
783                         orig_ref, strerror(errno));
784                 goto error_return;
785         }
786         /* When the ref did not exist and we are creating it,
787          * make sure there is no existing ref that is packed
788          * whose name begins with our refname, nor a ref whose
789          * name is a proper prefix of our refname.
790          */
791         if (is_null_sha1(lock->old_sha1) &&
792             !is_refname_available(ref, NULL, get_packed_refs(), 0))
793                 goto error_return;
794
795         lock->lk = xcalloc(1, sizeof(struct lock_file));
796
797         if (flags & REF_NODEREF)
798                 ref = orig_ref;
799         lock->ref_name = xstrdup(ref);
800         lock->orig_ref_name = xstrdup(orig_ref);
801         ref_file = git_path("%s", ref);
802         if (lstat(ref_file, &st) && errno == ENOENT)
803                 lock->force_write = 1;
804         if ((flags & REF_NODEREF) && (type & REF_ISSYMREF))
805                 lock->force_write = 1;
806
807         if (safe_create_leading_directories(ref_file)) {
808                 last_errno = errno;
809                 error("unable to create directory for %s", ref_file);
810                 goto error_return;
811         }
812         lock->lock_fd = hold_lock_file_for_update(lock->lk, ref_file, 1);
813
814         return old_sha1 ? verify_lock(lock, old_sha1, mustexist) : lock;
815
816  error_return:
817         unlock_ref(lock);
818         errno = last_errno;
819         return NULL;
820 }
821
822 struct ref_lock *lock_ref_sha1(const char *ref, const unsigned char *old_sha1)
823 {
824         char refpath[PATH_MAX];
825         if (check_ref_format(ref))
826                 return NULL;
827         strcpy(refpath, mkpath("refs/%s", ref));
828         return lock_ref_sha1_basic(refpath, old_sha1, 0, NULL);
829 }
830
831 struct ref_lock *lock_any_ref_for_update(const char *ref, const unsigned char *old_sha1, int flags)
832 {
833         if (check_ref_format(ref) == -1)
834                 return NULL;
835         return lock_ref_sha1_basic(ref, old_sha1, flags, NULL);
836 }
837
838 static struct lock_file packlock;
839
840 static int repack_without_ref(const char *refname)
841 {
842         struct ref_list *list, *packed_ref_list;
843         int fd;
844         int found = 0;
845
846         packed_ref_list = get_packed_refs();
847         for (list = packed_ref_list; list; list = list->next) {
848                 if (!strcmp(refname, list->name)) {
849                         found = 1;
850                         break;
851                 }
852         }
853         if (!found)
854                 return 0;
855         fd = hold_lock_file_for_update(&packlock, git_path("packed-refs"), 0);
856         if (fd < 0)
857                 return error("cannot delete '%s' from packed refs", refname);
858
859         for (list = packed_ref_list; list; list = list->next) {
860                 char line[PATH_MAX + 100];
861                 int len;
862
863                 if (!strcmp(refname, list->name))
864                         continue;
865                 len = snprintf(line, sizeof(line), "%s %s\n",
866                                sha1_to_hex(list->sha1), list->name);
867                 /* this should not happen but just being defensive */
868                 if (len > sizeof(line))
869                         die("too long a refname '%s'", list->name);
870                 write_or_die(fd, line, len);
871         }
872         return commit_lock_file(&packlock);
873 }
874
875 int delete_ref(const char *refname, const unsigned char *sha1)
876 {
877         struct ref_lock *lock;
878         int err, i, ret = 0, flag = 0;
879
880         lock = lock_ref_sha1_basic(refname, sha1, 0, &flag);
881         if (!lock)
882                 return 1;
883         if (!(flag & REF_ISPACKED)) {
884                 /* loose */
885                 i = strlen(lock->lk->filename) - 5; /* .lock */
886                 lock->lk->filename[i] = 0;
887                 err = unlink(lock->lk->filename);
888                 if (err) {
889                         ret = 1;
890                         error("unlink(%s) failed: %s",
891                               lock->lk->filename, strerror(errno));
892                 }
893                 lock->lk->filename[i] = '.';
894         }
895         /* removing the loose one could have resurrected an earlier
896          * packed one.  Also, if it was not loose we need to repack
897          * without it.
898          */
899         ret |= repack_without_ref(refname);
900
901         err = unlink(git_path("logs/%s", lock->ref_name));
902         if (err && errno != ENOENT)
903                 fprintf(stderr, "warning: unlink(%s) failed: %s",
904                         git_path("logs/%s", lock->ref_name), strerror(errno));
905         invalidate_cached_refs();
906         unlock_ref(lock);
907         return ret;
908 }
909
910 int rename_ref(const char *oldref, const char *newref, const char *logmsg)
911 {
912         static const char renamed_ref[] = "RENAMED-REF";
913         unsigned char sha1[20], orig_sha1[20];
914         int flag = 0, logmoved = 0;
915         struct ref_lock *lock;
916         struct stat loginfo;
917         int log = !lstat(git_path("logs/%s", oldref), &loginfo);
918
919         if (S_ISLNK(loginfo.st_mode))
920                 return error("reflog for %s is a symlink", oldref);
921
922         if (!resolve_ref(oldref, orig_sha1, 1, &flag))
923                 return error("refname %s not found", oldref);
924
925         if (!is_refname_available(newref, oldref, get_packed_refs(), 0))
926                 return 1;
927
928         if (!is_refname_available(newref, oldref, get_loose_refs(), 0))
929                 return 1;
930
931         lock = lock_ref_sha1_basic(renamed_ref, NULL, 0, NULL);
932         if (!lock)
933                 return error("unable to lock %s", renamed_ref);
934         lock->force_write = 1;
935         if (write_ref_sha1(lock, orig_sha1, logmsg))
936                 return error("unable to save current sha1 in %s", renamed_ref);
937
938         if (log && rename(git_path("logs/%s", oldref), git_path("tmp-renamed-log")))
939                 return error("unable to move logfile logs/%s to tmp-renamed-log: %s",
940                         oldref, strerror(errno));
941
942         if (delete_ref(oldref, orig_sha1)) {
943                 error("unable to delete old %s", oldref);
944                 goto rollback;
945         }
946
947         if (resolve_ref(newref, sha1, 1, &flag) && delete_ref(newref, sha1)) {
948                 if (errno==EISDIR) {
949                         if (remove_empty_directories(git_path("%s", newref))) {
950                                 error("Directory not empty: %s", newref);
951                                 goto rollback;
952                         }
953                 } else {
954                         error("unable to delete existing %s", newref);
955                         goto rollback;
956                 }
957         }
958
959         if (log && safe_create_leading_directories(git_path("logs/%s", newref))) {
960                 error("unable to create directory for %s", newref);
961                 goto rollback;
962         }
963
964  retry:
965         if (log && rename(git_path("tmp-renamed-log"), git_path("logs/%s", newref))) {
966                 if (errno==EISDIR || errno==ENOTDIR) {
967                         /*
968                          * rename(a, b) when b is an existing
969                          * directory ought to result in ISDIR, but
970                          * Solaris 5.8 gives ENOTDIR.  Sheesh.
971                          */
972                         if (remove_empty_directories(git_path("logs/%s", newref))) {
973                                 error("Directory not empty: logs/%s", newref);
974                                 goto rollback;
975                         }
976                         goto retry;
977                 } else {
978                         error("unable to move logfile tmp-renamed-log to logs/%s: %s",
979                                 newref, strerror(errno));
980                         goto rollback;
981                 }
982         }
983         logmoved = log;
984
985         lock = lock_ref_sha1_basic(newref, NULL, 0, NULL);
986         if (!lock) {
987                 error("unable to lock %s for update", newref);
988                 goto rollback;
989         }
990
991         lock->force_write = 1;
992         hashcpy(lock->old_sha1, orig_sha1);
993         if (write_ref_sha1(lock, orig_sha1, logmsg)) {
994                 error("unable to write current sha1 into %s", newref);
995                 goto rollback;
996         }
997
998         return 0;
999
1000  rollback:
1001         lock = lock_ref_sha1_basic(oldref, NULL, 0, NULL);
1002         if (!lock) {
1003                 error("unable to lock %s for rollback", oldref);
1004                 goto rollbacklog;
1005         }
1006
1007         lock->force_write = 1;
1008         flag = log_all_ref_updates;
1009         log_all_ref_updates = 0;
1010         if (write_ref_sha1(lock, orig_sha1, NULL))
1011                 error("unable to write current sha1 into %s", oldref);
1012         log_all_ref_updates = flag;
1013
1014  rollbacklog:
1015         if (logmoved && rename(git_path("logs/%s", newref), git_path("logs/%s", oldref)))
1016                 error("unable to restore logfile %s from %s: %s",
1017                         oldref, newref, strerror(errno));
1018         if (!logmoved && log &&
1019             rename(git_path("tmp-renamed-log"), git_path("logs/%s", oldref)))
1020                 error("unable to restore logfile %s from tmp-renamed-log: %s",
1021                         oldref, strerror(errno));
1022
1023         return 1;
1024 }
1025
1026 void unlock_ref(struct ref_lock *lock)
1027 {
1028         if (lock->lock_fd >= 0) {
1029                 close(lock->lock_fd);
1030                 /* Do not free lock->lk -- atexit() still looks at them */
1031                 if (lock->lk)
1032                         rollback_lock_file(lock->lk);
1033         }
1034         free(lock->ref_name);
1035         free(lock->orig_ref_name);
1036         free(lock);
1037 }
1038
1039 static int log_ref_write(const char *ref_name, const unsigned char *old_sha1,
1040                          const unsigned char *new_sha1, const char *msg)
1041 {
1042         int logfd, written, oflags = O_APPEND | O_WRONLY;
1043         unsigned maxlen, len;
1044         int msglen;
1045         char *log_file, *logrec;
1046         const char *committer;
1047
1048         if (log_all_ref_updates < 0)
1049                 log_all_ref_updates = !is_bare_repository();
1050
1051         log_file = git_path("logs/%s", ref_name);
1052
1053         if (log_all_ref_updates &&
1054             (!prefixcmp(ref_name, "refs/heads/") ||
1055              !prefixcmp(ref_name, "refs/remotes/") ||
1056              !strcmp(ref_name, "HEAD"))) {
1057                 if (safe_create_leading_directories(log_file) < 0)
1058                         return error("unable to create directory for %s",
1059                                      log_file);
1060                 oflags |= O_CREAT;
1061         }
1062
1063         logfd = open(log_file, oflags, 0666);
1064         if (logfd < 0) {
1065                 if (!(oflags & O_CREAT) && errno == ENOENT)
1066                         return 0;
1067
1068                 if ((oflags & O_CREAT) && errno == EISDIR) {
1069                         if (remove_empty_directories(log_file)) {
1070                                 return error("There are still logs under '%s'",
1071                                              log_file);
1072                         }
1073                         logfd = open(log_file, oflags, 0666);
1074                 }
1075
1076                 if (logfd < 0)
1077                         return error("Unable to append to %s: %s",
1078                                      log_file, strerror(errno));
1079         }
1080
1081         adjust_shared_perm(log_file);
1082
1083         msglen = 0;
1084         if (msg) {
1085                 /* clean up the message and make sure it is a single line */
1086                 for ( ; *msg; msg++)
1087                         if (!isspace(*msg))
1088                                 break;
1089                 if (*msg) {
1090                         const char *ep = strchr(msg, '\n');
1091                         if (ep)
1092                                 msglen = ep - msg;
1093                         else
1094                                 msglen = strlen(msg);
1095                 }
1096         }
1097
1098         committer = git_committer_info(-1);
1099         maxlen = strlen(committer) + msglen + 100;
1100         logrec = xmalloc(maxlen);
1101         len = sprintf(logrec, "%s %s %s\n",
1102                       sha1_to_hex(old_sha1),
1103                       sha1_to_hex(new_sha1),
1104                       committer);
1105         if (msglen)
1106                 len += sprintf(logrec + len - 1, "\t%.*s\n", msglen, msg) - 1;
1107         written = len <= maxlen ? write_in_full(logfd, logrec, len) : -1;
1108         free(logrec);
1109         if (close(logfd) != 0 || written != len)
1110                 return error("Unable to append to %s", log_file);
1111         return 0;
1112 }
1113
1114 int write_ref_sha1(struct ref_lock *lock,
1115         const unsigned char *sha1, const char *logmsg)
1116 {
1117         static char term = '\n';
1118
1119         if (!lock)
1120                 return -1;
1121         if (!lock->force_write && !hashcmp(lock->old_sha1, sha1)) {
1122                 unlock_ref(lock);
1123                 return 0;
1124         }
1125         if (write_in_full(lock->lock_fd, sha1_to_hex(sha1), 40) != 40 ||
1126             write_in_full(lock->lock_fd, &term, 1) != 1
1127                 || close(lock->lock_fd) < 0) {
1128                 error("Couldn't write %s", lock->lk->filename);
1129                 unlock_ref(lock);
1130                 return -1;
1131         }
1132         invalidate_cached_refs();
1133         if (log_ref_write(lock->ref_name, lock->old_sha1, sha1, logmsg) < 0 ||
1134             (strcmp(lock->ref_name, lock->orig_ref_name) &&
1135              log_ref_write(lock->orig_ref_name, lock->old_sha1, sha1, logmsg) < 0)) {
1136                 unlock_ref(lock);
1137                 return -1;
1138         }
1139         if (strcmp(lock->orig_ref_name, "HEAD") != 0) {
1140                 /*
1141                  * Special hack: If a branch is updated directly and HEAD
1142                  * points to it (may happen on the remote side of a push
1143                  * for example) then logically the HEAD reflog should be
1144                  * updated too.
1145                  * A generic solution implies reverse symref information,
1146                  * but finding all symrefs pointing to the given branch
1147                  * would be rather costly for this rare event (the direct
1148                  * update of a branch) to be worth it.  So let's cheat and
1149                  * check with HEAD only which should cover 99% of all usage
1150                  * scenarios (even 100% of the default ones).
1151                  */
1152                 unsigned char head_sha1[20];
1153                 int head_flag;
1154                 const char *head_ref;
1155                 head_ref = resolve_ref("HEAD", head_sha1, 1, &head_flag);
1156                 if (head_ref && (head_flag & REF_ISSYMREF) &&
1157                     !strcmp(head_ref, lock->ref_name))
1158                         log_ref_write("HEAD", lock->old_sha1, sha1, logmsg);
1159         }
1160         if (commit_lock_file(lock->lk)) {
1161                 error("Couldn't set %s", lock->ref_name);
1162                 unlock_ref(lock);
1163                 return -1;
1164         }
1165         lock->lock_fd = -1;
1166         unlock_ref(lock);
1167         return 0;
1168 }
1169
1170 int create_symref(const char *ref_target, const char *refs_heads_master,
1171                   const char *logmsg)
1172 {
1173         const char *lockpath;
1174         char ref[1000];
1175         int fd, len, written;
1176         char *git_HEAD = xstrdup(git_path("%s", ref_target));
1177         unsigned char old_sha1[20], new_sha1[20];
1178
1179         if (logmsg && read_ref(ref_target, old_sha1))
1180                 hashclr(old_sha1);
1181
1182         if (safe_create_leading_directories(git_HEAD) < 0)
1183                 return error("unable to create directory for %s", git_HEAD);
1184
1185 #ifndef NO_SYMLINK_HEAD
1186         if (prefer_symlink_refs) {
1187                 unlink(git_HEAD);
1188                 if (!symlink(refs_heads_master, git_HEAD))
1189                         goto done;
1190                 fprintf(stderr, "no symlink - falling back to symbolic ref\n");
1191         }
1192 #endif
1193
1194         len = snprintf(ref, sizeof(ref), "ref: %s\n", refs_heads_master);
1195         if (sizeof(ref) <= len) {
1196                 error("refname too long: %s", refs_heads_master);
1197                 goto error_free_return;
1198         }
1199         lockpath = mkpath("%s.lock", git_HEAD);
1200         fd = open(lockpath, O_CREAT | O_EXCL | O_WRONLY, 0666);
1201         if (fd < 0) {
1202                 error("Unable to open %s for writing", lockpath);
1203                 goto error_free_return;
1204         }
1205         written = write_in_full(fd, ref, len);
1206         if (close(fd) != 0 || written != len) {
1207                 error("Unable to write to %s", lockpath);
1208                 goto error_unlink_return;
1209         }
1210         if (rename(lockpath, git_HEAD) < 0) {
1211                 error("Unable to create %s", git_HEAD);
1212                 goto error_unlink_return;
1213         }
1214         if (adjust_shared_perm(git_HEAD)) {
1215                 error("Unable to fix permissions on %s", lockpath);
1216         error_unlink_return:
1217                 unlink(lockpath);
1218         error_free_return:
1219                 free(git_HEAD);
1220                 return -1;
1221         }
1222
1223 #ifndef NO_SYMLINK_HEAD
1224         done:
1225 #endif
1226         if (logmsg && !read_ref(refs_heads_master, new_sha1))
1227                 log_ref_write(ref_target, old_sha1, new_sha1, logmsg);
1228
1229         free(git_HEAD);
1230         return 0;
1231 }
1232
1233 static char *ref_msg(const char *line, const char *endp)
1234 {
1235         const char *ep;
1236         char *msg;
1237
1238         line += 82;
1239         for (ep = line; ep < endp && *ep != '\n'; ep++)
1240                 ;
1241         msg = xmalloc(ep - line + 1);
1242         memcpy(msg, line, ep - line);
1243         msg[ep - line] = 0;
1244         return msg;
1245 }
1246
1247 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)
1248 {
1249         const char *logfile, *logdata, *logend, *rec, *lastgt, *lastrec;
1250         char *tz_c;
1251         int logfd, tz, reccnt = 0;
1252         struct stat st;
1253         unsigned long date;
1254         unsigned char logged_sha1[20];
1255         void *log_mapped;
1256         size_t mapsz;
1257
1258         logfile = git_path("logs/%s", ref);
1259         logfd = open(logfile, O_RDONLY, 0);
1260         if (logfd < 0)
1261                 die("Unable to read log %s: %s", logfile, strerror(errno));
1262         fstat(logfd, &st);
1263         if (!st.st_size)
1264                 die("Log %s is empty.", logfile);
1265         mapsz = xsize_t(st.st_size);
1266         log_mapped = xmmap(NULL, mapsz, PROT_READ, MAP_PRIVATE, logfd, 0);
1267         logdata = log_mapped;
1268         close(logfd);
1269
1270         lastrec = NULL;
1271         rec = logend = logdata + st.st_size;
1272         while (logdata < rec) {
1273                 reccnt++;
1274                 if (logdata < rec && *(rec-1) == '\n')
1275                         rec--;
1276                 lastgt = NULL;
1277                 while (logdata < rec && *(rec-1) != '\n') {
1278                         rec--;
1279                         if (*rec == '>')
1280                                 lastgt = rec;
1281                 }
1282                 if (!lastgt)
1283                         die("Log %s is corrupt.", logfile);
1284                 date = strtoul(lastgt + 1, &tz_c, 10);
1285                 if (date <= at_time || cnt == 0) {
1286                         tz = strtoul(tz_c, NULL, 10);
1287                         if (msg)
1288                                 *msg = ref_msg(rec, logend);
1289                         if (cutoff_time)
1290                                 *cutoff_time = date;
1291                         if (cutoff_tz)
1292                                 *cutoff_tz = tz;
1293                         if (cutoff_cnt)
1294                                 *cutoff_cnt = reccnt - 1;
1295                         if (lastrec) {
1296                                 if (get_sha1_hex(lastrec, logged_sha1))
1297                                         die("Log %s is corrupt.", logfile);
1298                                 if (get_sha1_hex(rec + 41, sha1))
1299                                         die("Log %s is corrupt.", logfile);
1300                                 if (hashcmp(logged_sha1, sha1)) {
1301                                         fprintf(stderr,
1302                                                 "warning: Log %s has gap after %s.\n",
1303                                                 logfile, show_rfc2822_date(date, tz));
1304                                 }
1305                         }
1306                         else if (date == at_time) {
1307                                 if (get_sha1_hex(rec + 41, sha1))
1308                                         die("Log %s is corrupt.", logfile);
1309                         }
1310                         else {
1311                                 if (get_sha1_hex(rec + 41, logged_sha1))
1312                                         die("Log %s is corrupt.", logfile);
1313                                 if (hashcmp(logged_sha1, sha1)) {
1314                                         fprintf(stderr,
1315                                                 "warning: Log %s unexpectedly ended on %s.\n",
1316                                                 logfile, show_rfc2822_date(date, tz));
1317                                 }
1318                         }
1319                         munmap(log_mapped, mapsz);
1320                         return 0;
1321                 }
1322                 lastrec = rec;
1323                 if (cnt > 0)
1324                         cnt--;
1325         }
1326
1327         rec = logdata;
1328         while (rec < logend && *rec != '>' && *rec != '\n')
1329                 rec++;
1330         if (rec == logend || *rec == '\n')
1331                 die("Log %s is corrupt.", logfile);
1332         date = strtoul(rec + 1, &tz_c, 10);
1333         tz = strtoul(tz_c, NULL, 10);
1334         if (get_sha1_hex(logdata, sha1))
1335                 die("Log %s is corrupt.", logfile);
1336         if (msg)
1337                 *msg = ref_msg(logdata, logend);
1338         munmap(log_mapped, mapsz);
1339
1340         if (cutoff_time)
1341                 *cutoff_time = date;
1342         if (cutoff_tz)
1343                 *cutoff_tz = tz;
1344         if (cutoff_cnt)
1345                 *cutoff_cnt = reccnt;
1346         return 1;
1347 }
1348
1349 int for_each_reflog_ent(const char *ref, each_reflog_ent_fn fn, void *cb_data)
1350 {
1351         const char *logfile;
1352         FILE *logfp;
1353         char buf[1024];
1354         int ret = 0;
1355
1356         logfile = git_path("logs/%s", ref);
1357         logfp = fopen(logfile, "r");
1358         if (!logfp)
1359                 return -1;
1360         while (fgets(buf, sizeof(buf), logfp)) {
1361                 unsigned char osha1[20], nsha1[20];
1362                 char *email_end, *message;
1363                 unsigned long timestamp;
1364                 int len, tz;
1365
1366                 /* old SP new SP name <email> SP time TAB msg LF */
1367                 len = strlen(buf);
1368                 if (len < 83 || buf[len-1] != '\n' ||
1369                     get_sha1_hex(buf, osha1) || buf[40] != ' ' ||
1370                     get_sha1_hex(buf + 41, nsha1) || buf[81] != ' ' ||
1371                     !(email_end = strchr(buf + 82, '>')) ||
1372                     email_end[1] != ' ' ||
1373                     !(timestamp = strtoul(email_end + 2, &message, 10)) ||
1374                     !message || message[0] != ' ' ||
1375                     (message[1] != '+' && message[1] != '-') ||
1376                     !isdigit(message[2]) || !isdigit(message[3]) ||
1377                     !isdigit(message[4]) || !isdigit(message[5]))
1378                         continue; /* corrupt? */
1379                 email_end[1] = '\0';
1380                 tz = strtol(message + 1, NULL, 10);
1381                 if (message[6] != '\t')
1382                         message += 6;
1383                 else
1384                         message += 7;
1385                 ret = fn(osha1, nsha1, buf+82, timestamp, tz, message, cb_data);
1386                 if (ret)
1387                         break;
1388         }
1389         fclose(logfp);
1390         return ret;
1391 }
1392
1393 static int do_for_each_reflog(const char *base, each_ref_fn fn, void *cb_data)
1394 {
1395         DIR *dir = opendir(git_path("logs/%s", base));
1396         int retval = 0;
1397
1398         if (dir) {
1399                 struct dirent *de;
1400                 int baselen = strlen(base);
1401                 char *log = xmalloc(baselen + 257);
1402
1403                 memcpy(log, base, baselen);
1404                 if (baselen && base[baselen-1] != '/')
1405                         log[baselen++] = '/';
1406
1407                 while ((de = readdir(dir)) != NULL) {
1408                         struct stat st;
1409                         int namelen;
1410
1411                         if (de->d_name[0] == '.')
1412                                 continue;
1413                         namelen = strlen(de->d_name);
1414                         if (namelen > 255)
1415                                 continue;
1416                         if (has_extension(de->d_name, ".lock"))
1417                                 continue;
1418                         memcpy(log + baselen, de->d_name, namelen+1);
1419                         if (stat(git_path("logs/%s", log), &st) < 0)
1420                                 continue;
1421                         if (S_ISDIR(st.st_mode)) {
1422                                 retval = do_for_each_reflog(log, fn, cb_data);
1423                         } else {
1424                                 unsigned char sha1[20];
1425                                 if (!resolve_ref(log, sha1, 0, NULL))
1426                                         retval = error("bad ref for %s", log);
1427                                 else
1428                                         retval = fn(log, sha1, 0, cb_data);
1429                         }
1430                         if (retval)
1431                                 break;
1432                 }
1433                 free(log);
1434                 closedir(dir);
1435         }
1436         else if (*base)
1437                 return errno;
1438         return retval;
1439 }
1440
1441 int for_each_reflog(each_ref_fn fn, void *cb_data)
1442 {
1443         return do_for_each_reflog("", fn, cb_data);
1444 }