repack_without_ref(): remove temporary
[git] / refs.c
1 #include "cache.h"
2 #include "refs.h"
3 #include "object.h"
4 #include "tag.h"
5 #include "dir.h"
6
7 /* ISSYMREF=0x01, ISPACKED=0x02 and ISBROKEN=0x04 are public interfaces */
8 #define REF_KNOWS_PEELED 0x10
9
10 struct ref_entry {
11         unsigned char flag; /* ISSYMREF? ISPACKED? */
12         unsigned char sha1[20];
13         unsigned char peeled[20];
14         /* The full name of the reference (e.g., "refs/heads/master"): */
15         char name[FLEX_ARRAY];
16 };
17
18 struct ref_array {
19         int nr, alloc;
20         struct ref_entry **refs;
21 };
22
23 /*
24  * Parse one line from a packed-refs file.  Write the SHA1 to sha1.
25  * Return a pointer to the refname within the line (null-terminated),
26  * or NULL if there was a problem.
27  */
28 static const char *parse_ref_line(char *line, unsigned char *sha1)
29 {
30         /*
31          * 42: the answer to everything.
32          *
33          * In this case, it happens to be the answer to
34          *  40 (length of sha1 hex representation)
35          *  +1 (space in between hex and name)
36          *  +1 (newline at the end of the line)
37          */
38         int len = strlen(line) - 42;
39
40         if (len <= 0)
41                 return NULL;
42         if (get_sha1_hex(line, sha1) < 0)
43                 return NULL;
44         if (!isspace(line[40]))
45                 return NULL;
46         line += 41;
47         if (isspace(*line))
48                 return NULL;
49         if (line[len] != '\n')
50                 return NULL;
51         line[len] = 0;
52
53         return line;
54 }
55
56 /* Add a ref_entry to the end of the ref_array (unsorted). */
57 static void add_ref(const char *refname, const unsigned char *sha1,
58                     int flag, int check_name, struct ref_array *refs,
59                     struct ref_entry **new_entry)
60 {
61         int len;
62         struct ref_entry *entry;
63
64         /* Allocate it and add it in.. */
65         len = strlen(refname) + 1;
66         entry = xmalloc(sizeof(struct ref_entry) + len);
67         hashcpy(entry->sha1, sha1);
68         hashclr(entry->peeled);
69         if (check_name &&
70             check_refname_format(refname, REFNAME_ALLOW_ONELEVEL|REFNAME_DOT_COMPONENT))
71                 die("Reference has invalid format: '%s'", refname);
72         memcpy(entry->name, refname, len);
73         entry->flag = flag;
74         if (new_entry)
75                 *new_entry = entry;
76         ALLOC_GROW(refs->refs, refs->nr + 1, refs->alloc);
77         refs->refs[refs->nr++] = entry;
78 }
79
80 static int ref_entry_cmp(const void *a, const void *b)
81 {
82         struct ref_entry *one = *(struct ref_entry **)a;
83         struct ref_entry *two = *(struct ref_entry **)b;
84         return strcmp(one->name, two->name);
85 }
86
87 /*
88  * Emit a warning and return true iff ref1 and ref2 have the same name
89  * and the same sha1.  Die if they have the same name but different
90  * sha1s.
91  */
92 static int is_dup_ref(const struct ref_entry *ref1, const struct ref_entry *ref2)
93 {
94         if (!strcmp(ref1->name, ref2->name)) {
95                 /* Duplicate name; make sure that the SHA1s match: */
96                 if (hashcmp(ref1->sha1, ref2->sha1))
97                         die("Duplicated ref, and SHA1s don't match: %s",
98                             ref1->name);
99                 warning("Duplicated ref: %s", ref1->name);
100                 return 1;
101         } else {
102                 return 0;
103         }
104 }
105
106 static void sort_ref_array(struct ref_array *array)
107 {
108         int i, j;
109
110         /* Nothing to sort unless there are at least two entries */
111         if (array->nr < 2)
112                 return;
113
114         qsort(array->refs, array->nr, sizeof(*array->refs), ref_entry_cmp);
115
116         /* Remove any duplicates from the ref_array */
117         i = 0;
118         for (j = 1; j < array->nr; j++) {
119                 if (is_dup_ref(array->refs[i], array->refs[j])) {
120                         free(array->refs[j]);
121                         continue;
122                 }
123                 array->refs[++i] = array->refs[j];
124         }
125         array->nr = i + 1;
126 }
127
128 static struct ref_entry *search_ref_array(struct ref_array *array, const char *refname)
129 {
130         struct ref_entry *e, **r;
131         int len;
132
133         if (refname == NULL)
134                 return NULL;
135
136         if (!array->nr)
137                 return NULL;
138
139         len = strlen(refname) + 1;
140         e = xmalloc(sizeof(struct ref_entry) + len);
141         memcpy(e->name, refname, len);
142
143         r = bsearch(&e, array->refs, array->nr, sizeof(*array->refs), ref_entry_cmp);
144
145         free(e);
146
147         if (r == NULL)
148                 return NULL;
149
150         return *r;
151 }
152
153 /*
154  * Future: need to be in "struct repository"
155  * when doing a full libification.
156  */
157 static struct ref_cache {
158         struct ref_cache *next;
159         char did_loose;
160         char did_packed;
161         struct ref_array loose;
162         struct ref_array packed;
163         /* The submodule name, or "" for the main repo. */
164         char name[FLEX_ARRAY];
165 } *ref_cache;
166
167 static struct ref_entry *current_ref;
168
169 static struct ref_array extra_refs;
170
171 static void clear_ref_array(struct ref_array *array)
172 {
173         int i;
174         for (i = 0; i < array->nr; i++)
175                 free(array->refs[i]);
176         free(array->refs);
177         array->nr = array->alloc = 0;
178         array->refs = NULL;
179 }
180
181 static void clear_packed_ref_cache(struct ref_cache *refs)
182 {
183         if (refs->did_packed)
184                 clear_ref_array(&refs->packed);
185         refs->did_packed = 0;
186 }
187
188 static void clear_loose_ref_cache(struct ref_cache *refs)
189 {
190         if (refs->did_loose)
191                 clear_ref_array(&refs->loose);
192         refs->did_loose = 0;
193 }
194
195 static struct ref_cache *create_ref_cache(const char *submodule)
196 {
197         int len;
198         struct ref_cache *refs;
199         if (!submodule)
200                 submodule = "";
201         len = strlen(submodule) + 1;
202         refs = xcalloc(1, sizeof(struct ref_cache) + len);
203         memcpy(refs->name, submodule, len);
204         return refs;
205 }
206
207 /*
208  * Return a pointer to a ref_cache for the specified submodule. For
209  * the main repository, use submodule==NULL. The returned structure
210  * will be allocated and initialized but not necessarily populated; it
211  * should not be freed.
212  */
213 static struct ref_cache *get_ref_cache(const char *submodule)
214 {
215         struct ref_cache *refs = ref_cache;
216         if (!submodule)
217                 submodule = "";
218         while (refs) {
219                 if (!strcmp(submodule, refs->name))
220                         return refs;
221                 refs = refs->next;
222         }
223
224         refs = create_ref_cache(submodule);
225         refs->next = ref_cache;
226         ref_cache = refs;
227         return refs;
228 }
229
230 void invalidate_ref_cache(const char *submodule)
231 {
232         struct ref_cache *refs = get_ref_cache(submodule);
233         clear_packed_ref_cache(refs);
234         clear_loose_ref_cache(refs);
235 }
236
237 static void read_packed_refs(FILE *f, struct ref_array *array)
238 {
239         struct ref_entry *last = NULL;
240         char refline[PATH_MAX];
241         int flag = REF_ISPACKED;
242
243         while (fgets(refline, sizeof(refline), f)) {
244                 unsigned char sha1[20];
245                 const char *refname;
246                 static const char header[] = "# pack-refs with:";
247
248                 if (!strncmp(refline, header, sizeof(header)-1)) {
249                         const char *traits = refline + sizeof(header) - 1;
250                         if (strstr(traits, " peeled "))
251                                 flag |= REF_KNOWS_PEELED;
252                         /* perhaps other traits later as well */
253                         continue;
254                 }
255
256                 refname = parse_ref_line(refline, sha1);
257                 if (refname) {
258                         add_ref(refname, sha1, flag, 1, array, &last);
259                         continue;
260                 }
261                 if (last &&
262                     refline[0] == '^' &&
263                     strlen(refline) == 42 &&
264                     refline[41] == '\n' &&
265                     !get_sha1_hex(refline + 1, sha1))
266                         hashcpy(last->peeled, sha1);
267         }
268         sort_ref_array(array);
269 }
270
271 void add_extra_ref(const char *refname, const unsigned char *sha1, int flag)
272 {
273         add_ref(refname, sha1, flag, 0, &extra_refs, NULL);
274 }
275
276 void clear_extra_refs(void)
277 {
278         clear_ref_array(&extra_refs);
279 }
280
281 static struct ref_array *get_packed_refs(struct ref_cache *refs)
282 {
283         if (!refs->did_packed) {
284                 const char *packed_refs_file;
285                 FILE *f;
286
287                 if (*refs->name)
288                         packed_refs_file = git_path_submodule(refs->name, "packed-refs");
289                 else
290                         packed_refs_file = git_path("packed-refs");
291                 f = fopen(packed_refs_file, "r");
292                 if (f) {
293                         read_packed_refs(f, &refs->packed);
294                         fclose(f);
295                 }
296                 refs->did_packed = 1;
297         }
298         return &refs->packed;
299 }
300
301 static void get_ref_dir(struct ref_cache *refs, const char *base,
302                         struct ref_array *array)
303 {
304         DIR *dir;
305         const char *path;
306
307         if (*refs->name)
308                 path = git_path_submodule(refs->name, "%s", base);
309         else
310                 path = git_path("%s", base);
311
312
313         dir = opendir(path);
314
315         if (dir) {
316                 struct dirent *de;
317                 int baselen = strlen(base);
318                 char *refname = xmalloc(baselen + 257);
319
320                 memcpy(refname, base, baselen);
321                 if (baselen && base[baselen-1] != '/')
322                         refname[baselen++] = '/';
323
324                 while ((de = readdir(dir)) != NULL) {
325                         unsigned char sha1[20];
326                         struct stat st;
327                         int flag;
328                         int namelen;
329                         const char *refdir;
330
331                         if (de->d_name[0] == '.')
332                                 continue;
333                         namelen = strlen(de->d_name);
334                         if (namelen > 255)
335                                 continue;
336                         if (has_extension(de->d_name, ".lock"))
337                                 continue;
338                         memcpy(refname + baselen, de->d_name, namelen+1);
339                         refdir = *refs->name
340                                 ? git_path_submodule(refs->name, "%s", refname)
341                                 : git_path("%s", refname);
342                         if (stat(refdir, &st) < 0)
343                                 continue;
344                         if (S_ISDIR(st.st_mode)) {
345                                 get_ref_dir(refs, refname, array);
346                                 continue;
347                         }
348                         if (*refs->name) {
349                                 hashclr(sha1);
350                                 flag = 0;
351                                 if (resolve_gitlink_ref(refs->name, refname, sha1) < 0) {
352                                         hashclr(sha1);
353                                         flag |= REF_ISBROKEN;
354                                 }
355                         } else if (read_ref_full(refname, sha1, 1, &flag)) {
356                                 hashclr(sha1);
357                                 flag |= REF_ISBROKEN;
358                         }
359                         add_ref(refname, sha1, flag, 1, array, NULL);
360                 }
361                 free(refname);
362                 closedir(dir);
363         }
364 }
365
366 struct warn_if_dangling_data {
367         FILE *fp;
368         const char *refname;
369         const char *msg_fmt;
370 };
371
372 static int warn_if_dangling_symref(const char *refname, const unsigned char *sha1,
373                                    int flags, void *cb_data)
374 {
375         struct warn_if_dangling_data *d = cb_data;
376         const char *resolves_to;
377         unsigned char junk[20];
378
379         if (!(flags & REF_ISSYMREF))
380                 return 0;
381
382         resolves_to = resolve_ref(refname, junk, 0, NULL);
383         if (!resolves_to || strcmp(resolves_to, d->refname))
384                 return 0;
385
386         fprintf(d->fp, d->msg_fmt, refname);
387         return 0;
388 }
389
390 void warn_dangling_symref(FILE *fp, const char *msg_fmt, const char *refname)
391 {
392         struct warn_if_dangling_data data;
393
394         data.fp = fp;
395         data.refname = refname;
396         data.msg_fmt = msg_fmt;
397         for_each_rawref(warn_if_dangling_symref, &data);
398 }
399
400 static struct ref_array *get_loose_refs(struct ref_cache *refs)
401 {
402         if (!refs->did_loose) {
403                 get_ref_dir(refs, "refs", &refs->loose);
404                 sort_ref_array(&refs->loose);
405                 refs->did_loose = 1;
406         }
407         return &refs->loose;
408 }
409
410 /* We allow "recursive" symbolic refs. Only within reason, though */
411 #define MAXDEPTH 5
412 #define MAXREFLEN (1024)
413
414 /*
415  * Called by resolve_gitlink_ref_recursive() after it failed to read
416  * from the loose refs in ref_cache refs. Find <refname> in the
417  * packed-refs file for the submodule.
418  */
419 static int resolve_gitlink_packed_ref(struct ref_cache *refs,
420                                       const char *refname, unsigned char *sha1)
421 {
422         struct ref_entry *ref;
423         struct ref_array *array = get_packed_refs(refs);
424
425         ref = search_ref_array(array, refname);
426         if (ref == NULL)
427                 return -1;
428
429         memcpy(sha1, ref->sha1, 20);
430         return 0;
431 }
432
433 static int resolve_gitlink_ref_recursive(struct ref_cache *refs,
434                                          const char *refname, unsigned char *sha1,
435                                          int recursion)
436 {
437         int fd, len;
438         char buffer[128], *p;
439         char *path;
440
441         if (recursion > MAXDEPTH || strlen(refname) > MAXREFLEN)
442                 return -1;
443         path = *refs->name
444                 ? git_path_submodule(refs->name, "%s", refname)
445                 : git_path("%s", refname);
446         fd = open(path, O_RDONLY);
447         if (fd < 0)
448                 return resolve_gitlink_packed_ref(refs, refname, sha1);
449
450         len = read(fd, buffer, sizeof(buffer)-1);
451         close(fd);
452         if (len < 0)
453                 return -1;
454         while (len && isspace(buffer[len-1]))
455                 len--;
456         buffer[len] = 0;
457
458         /* Was it a detached head or an old-fashioned symlink? */
459         if (!get_sha1_hex(buffer, sha1))
460                 return 0;
461
462         /* Symref? */
463         if (strncmp(buffer, "ref:", 4))
464                 return -1;
465         p = buffer + 4;
466         while (isspace(*p))
467                 p++;
468
469         return resolve_gitlink_ref_recursive(refs, p, sha1, recursion+1);
470 }
471
472 int resolve_gitlink_ref(const char *path, const char *refname, unsigned char *sha1)
473 {
474         int len = strlen(path), retval;
475         char *submodule;
476         struct ref_cache *refs;
477
478         while (len && path[len-1] == '/')
479                 len--;
480         if (!len)
481                 return -1;
482         submodule = xstrndup(path, len);
483         refs = get_ref_cache(submodule);
484         free(submodule);
485
486         retval = resolve_gitlink_ref_recursive(refs, refname, sha1, 0);
487         return retval;
488 }
489
490 /*
491  * Try to read ref from the packed references.  On success, set sha1
492  * and return 0; otherwise, return -1.
493  */
494 static int get_packed_ref(const char *refname, unsigned char *sha1)
495 {
496         struct ref_array *packed = get_packed_refs(get_ref_cache(NULL));
497         struct ref_entry *entry = search_ref_array(packed, refname);
498         if (entry) {
499                 hashcpy(sha1, entry->sha1);
500                 return 0;
501         }
502         return -1;
503 }
504
505 const char *resolve_ref(const char *refname, unsigned char *sha1, int reading, int *flag)
506 {
507         int depth = MAXDEPTH;
508         ssize_t len;
509         char buffer[256];
510         static char refname_buffer[256];
511
512         if (flag)
513                 *flag = 0;
514
515         if (check_refname_format(refname, REFNAME_ALLOW_ONELEVEL))
516                 return NULL;
517
518         for (;;) {
519                 char path[PATH_MAX];
520                 struct stat st;
521                 char *buf;
522                 int fd;
523
524                 if (--depth < 0)
525                         return NULL;
526
527                 git_snpath(path, sizeof(path), "%s", refname);
528
529                 if (lstat(path, &st) < 0) {
530                         if (errno != ENOENT)
531                                 return NULL;
532                         /*
533                          * The loose reference file does not exist;
534                          * check for a packed reference.
535                          */
536                         if (!get_packed_ref(refname, sha1)) {
537                                 if (flag)
538                                         *flag |= REF_ISPACKED;
539                                 return refname;
540                         }
541                         /* The reference is not a packed reference, either. */
542                         if (reading) {
543                                 return NULL;
544                         } else {
545                                 hashclr(sha1);
546                                 return refname;
547                         }
548                 }
549
550                 /* Follow "normalized" - ie "refs/.." symlinks by hand */
551                 if (S_ISLNK(st.st_mode)) {
552                         len = readlink(path, buffer, sizeof(buffer)-1);
553                         if (len < 0)
554                                 return NULL;
555                         buffer[len] = 0;
556                         if (!prefixcmp(buffer, "refs/") &&
557                                         !check_refname_format(buffer, 0)) {
558                                 strcpy(refname_buffer, buffer);
559                                 refname = refname_buffer;
560                                 if (flag)
561                                         *flag |= REF_ISSYMREF;
562                                 continue;
563                         }
564                 }
565
566                 /* Is it a directory? */
567                 if (S_ISDIR(st.st_mode)) {
568                         errno = EISDIR;
569                         return NULL;
570                 }
571
572                 /*
573                  * Anything else, just open it and try to use it as
574                  * a ref
575                  */
576                 fd = open(path, O_RDONLY);
577                 if (fd < 0)
578                         return NULL;
579                 len = read_in_full(fd, buffer, sizeof(buffer)-1);
580                 close(fd);
581                 if (len < 0)
582                         return NULL;
583                 while (len && isspace(buffer[len-1]))
584                         len--;
585                 buffer[len] = '\0';
586
587                 /*
588                  * Is it a symbolic ref?
589                  */
590                 if (prefixcmp(buffer, "ref:"))
591                         break;
592                 if (flag)
593                         *flag |= REF_ISSYMREF;
594                 buf = buffer + 4;
595                 while (isspace(*buf))
596                         buf++;
597                 if (check_refname_format(buf, REFNAME_ALLOW_ONELEVEL)) {
598                         if (flag)
599                                 *flag |= REF_ISBROKEN;
600                         return NULL;
601                 }
602                 refname = strcpy(refname_buffer, buf);
603         }
604         /* Please note that FETCH_HEAD has a second line containing other data. */
605         if (get_sha1_hex(buffer, sha1) || (buffer[40] != '\0' && !isspace(buffer[40]))) {
606                 if (flag)
607                         *flag |= REF_ISBROKEN;
608                 return NULL;
609         }
610         return refname;
611 }
612
613 /* The argument to filter_refs */
614 struct ref_filter {
615         const char *pattern;
616         each_ref_fn *fn;
617         void *cb_data;
618 };
619
620 int read_ref_full(const char *refname, unsigned char *sha1, int reading, int *flags)
621 {
622         if (resolve_ref(refname, sha1, reading, flags))
623                 return 0;
624         return -1;
625 }
626
627 int read_ref(const char *refname, unsigned char *sha1)
628 {
629         return read_ref_full(refname, sha1, 1, NULL);
630 }
631
632 #define DO_FOR_EACH_INCLUDE_BROKEN 01
633 static int do_one_ref(const char *base, each_ref_fn fn, int trim,
634                       int flags, void *cb_data, struct ref_entry *entry)
635 {
636         if (prefixcmp(entry->name, base))
637                 return 0;
638
639         if (!(flags & DO_FOR_EACH_INCLUDE_BROKEN)) {
640                 if (entry->flag & REF_ISBROKEN)
641                         return 0; /* ignore broken refs e.g. dangling symref */
642                 if (!has_sha1_file(entry->sha1)) {
643                         error("%s does not point to a valid object!", entry->name);
644                         return 0;
645                 }
646         }
647         current_ref = entry;
648         return fn(entry->name + trim, entry->sha1, entry->flag, cb_data);
649 }
650
651 static int filter_refs(const char *refname, const unsigned char *sha1, int flags,
652                        void *data)
653 {
654         struct ref_filter *filter = (struct ref_filter *)data;
655         if (fnmatch(filter->pattern, refname, 0))
656                 return 0;
657         return filter->fn(refname, sha1, flags, filter->cb_data);
658 }
659
660 int peel_ref(const char *refname, unsigned char *sha1)
661 {
662         int flag;
663         unsigned char base[20];
664         struct object *o;
665
666         if (current_ref && (current_ref->name == refname
667                 || !strcmp(current_ref->name, refname))) {
668                 if (current_ref->flag & REF_KNOWS_PEELED) {
669                         hashcpy(sha1, current_ref->peeled);
670                         return 0;
671                 }
672                 hashcpy(base, current_ref->sha1);
673                 goto fallback;
674         }
675
676         if (read_ref_full(refname, base, 1, &flag))
677                 return -1;
678
679         if ((flag & REF_ISPACKED)) {
680                 struct ref_array *array = get_packed_refs(get_ref_cache(NULL));
681                 struct ref_entry *r = search_ref_array(array, refname);
682
683                 if (r != NULL && r->flag & REF_KNOWS_PEELED) {
684                         hashcpy(sha1, r->peeled);
685                         return 0;
686                 }
687         }
688
689 fallback:
690         o = parse_object(base);
691         if (o && o->type == OBJ_TAG) {
692                 o = deref_tag(o, refname, 0);
693                 if (o) {
694                         hashcpy(sha1, o->sha1);
695                         return 0;
696                 }
697         }
698         return -1;
699 }
700
701 static int do_for_each_ref(const char *submodule, const char *base, each_ref_fn fn,
702                            int trim, int flags, void *cb_data)
703 {
704         int retval = 0, i, p = 0, l = 0;
705         struct ref_cache *refs = get_ref_cache(submodule);
706         struct ref_array *packed = get_packed_refs(refs);
707         struct ref_array *loose = get_loose_refs(refs);
708
709         struct ref_array *extra = &extra_refs;
710
711         for (i = 0; i < extra->nr; i++)
712                 retval = do_one_ref(base, fn, trim, flags, cb_data, extra->refs[i]);
713
714         while (p < packed->nr && l < loose->nr) {
715                 struct ref_entry *entry;
716                 int cmp = strcmp(packed->refs[p]->name, loose->refs[l]->name);
717                 if (!cmp) {
718                         p++;
719                         continue;
720                 }
721                 if (cmp > 0) {
722                         entry = loose->refs[l++];
723                 } else {
724                         entry = packed->refs[p++];
725                 }
726                 retval = do_one_ref(base, fn, trim, flags, cb_data, entry);
727                 if (retval)
728                         goto end_each;
729         }
730
731         if (l < loose->nr) {
732                 p = l;
733                 packed = loose;
734         }
735
736         for (; p < packed->nr; p++) {
737                 retval = do_one_ref(base, fn, trim, flags, cb_data, packed->refs[p]);
738                 if (retval)
739                         goto end_each;
740         }
741
742 end_each:
743         current_ref = NULL;
744         return retval;
745 }
746
747
748 static int do_head_ref(const char *submodule, each_ref_fn fn, void *cb_data)
749 {
750         unsigned char sha1[20];
751         int flag;
752
753         if (submodule) {
754                 if (resolve_gitlink_ref(submodule, "HEAD", sha1) == 0)
755                         return fn("HEAD", sha1, 0, cb_data);
756
757                 return 0;
758         }
759
760         if (!read_ref_full("HEAD", sha1, 1, &flag))
761                 return fn("HEAD", sha1, flag, cb_data);
762
763         return 0;
764 }
765
766 int head_ref(each_ref_fn fn, void *cb_data)
767 {
768         return do_head_ref(NULL, fn, cb_data);
769 }
770
771 int head_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
772 {
773         return do_head_ref(submodule, fn, cb_data);
774 }
775
776 int for_each_ref(each_ref_fn fn, void *cb_data)
777 {
778         return do_for_each_ref(NULL, "", fn, 0, 0, cb_data);
779 }
780
781 int for_each_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
782 {
783         return do_for_each_ref(submodule, "", fn, 0, 0, cb_data);
784 }
785
786 int for_each_ref_in(const char *prefix, each_ref_fn fn, void *cb_data)
787 {
788         return do_for_each_ref(NULL, prefix, fn, strlen(prefix), 0, cb_data);
789 }
790
791 int for_each_ref_in_submodule(const char *submodule, const char *prefix,
792                 each_ref_fn fn, void *cb_data)
793 {
794         return do_for_each_ref(submodule, prefix, fn, strlen(prefix), 0, cb_data);
795 }
796
797 int for_each_tag_ref(each_ref_fn fn, void *cb_data)
798 {
799         return for_each_ref_in("refs/tags/", fn, cb_data);
800 }
801
802 int for_each_tag_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
803 {
804         return for_each_ref_in_submodule(submodule, "refs/tags/", fn, cb_data);
805 }
806
807 int for_each_branch_ref(each_ref_fn fn, void *cb_data)
808 {
809         return for_each_ref_in("refs/heads/", fn, cb_data);
810 }
811
812 int for_each_branch_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
813 {
814         return for_each_ref_in_submodule(submodule, "refs/heads/", fn, cb_data);
815 }
816
817 int for_each_remote_ref(each_ref_fn fn, void *cb_data)
818 {
819         return for_each_ref_in("refs/remotes/", fn, cb_data);
820 }
821
822 int for_each_remote_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
823 {
824         return for_each_ref_in_submodule(submodule, "refs/remotes/", fn, cb_data);
825 }
826
827 int for_each_replace_ref(each_ref_fn fn, void *cb_data)
828 {
829         return do_for_each_ref(NULL, "refs/replace/", fn, 13, 0, cb_data);
830 }
831
832 int head_ref_namespaced(each_ref_fn fn, void *cb_data)
833 {
834         struct strbuf buf = STRBUF_INIT;
835         int ret = 0;
836         unsigned char sha1[20];
837         int flag;
838
839         strbuf_addf(&buf, "%sHEAD", get_git_namespace());
840         if (!read_ref_full(buf.buf, sha1, 1, &flag))
841                 ret = fn(buf.buf, sha1, flag, cb_data);
842         strbuf_release(&buf);
843
844         return ret;
845 }
846
847 int for_each_namespaced_ref(each_ref_fn fn, void *cb_data)
848 {
849         struct strbuf buf = STRBUF_INIT;
850         int ret;
851         strbuf_addf(&buf, "%srefs/", get_git_namespace());
852         ret = do_for_each_ref(NULL, buf.buf, fn, 0, 0, cb_data);
853         strbuf_release(&buf);
854         return ret;
855 }
856
857 int for_each_glob_ref_in(each_ref_fn fn, const char *pattern,
858         const char *prefix, void *cb_data)
859 {
860         struct strbuf real_pattern = STRBUF_INIT;
861         struct ref_filter filter;
862         int ret;
863
864         if (!prefix && prefixcmp(pattern, "refs/"))
865                 strbuf_addstr(&real_pattern, "refs/");
866         else if (prefix)
867                 strbuf_addstr(&real_pattern, prefix);
868         strbuf_addstr(&real_pattern, pattern);
869
870         if (!has_glob_specials(pattern)) {
871                 /* Append implied '/' '*' if not present. */
872                 if (real_pattern.buf[real_pattern.len - 1] != '/')
873                         strbuf_addch(&real_pattern, '/');
874                 /* No need to check for '*', there is none. */
875                 strbuf_addch(&real_pattern, '*');
876         }
877
878         filter.pattern = real_pattern.buf;
879         filter.fn = fn;
880         filter.cb_data = cb_data;
881         ret = for_each_ref(filter_refs, &filter);
882
883         strbuf_release(&real_pattern);
884         return ret;
885 }
886
887 int for_each_glob_ref(each_ref_fn fn, const char *pattern, void *cb_data)
888 {
889         return for_each_glob_ref_in(fn, pattern, NULL, cb_data);
890 }
891
892 int for_each_rawref(each_ref_fn fn, void *cb_data)
893 {
894         return do_for_each_ref(NULL, "", fn, 0,
895                                DO_FOR_EACH_INCLUDE_BROKEN, cb_data);
896 }
897
898 /*
899  * Make sure "ref" is something reasonable to have under ".git/refs/";
900  * We do not like it if:
901  *
902  * - any path component of it begins with ".", or
903  * - it has double dots "..", or
904  * - it has ASCII control character, "~", "^", ":" or SP, anywhere, or
905  * - it ends with a "/".
906  * - it ends with ".lock"
907  * - it contains a "\" (backslash)
908  */
909
910 /* Return true iff ch is not allowed in reference names. */
911 static inline int bad_ref_char(int ch)
912 {
913         if (((unsigned) ch) <= ' ' || ch == 0x7f ||
914             ch == '~' || ch == '^' || ch == ':' || ch == '\\')
915                 return 1;
916         /* 2.13 Pattern Matching Notation */
917         if (ch == '*' || ch == '?' || ch == '[') /* Unsupported */
918                 return 1;
919         return 0;
920 }
921
922 /*
923  * Try to read one refname component from the front of refname.  Return
924  * the length of the component found, or -1 if the component is not
925  * legal.
926  */
927 static int check_refname_component(const char *refname, int flags)
928 {
929         const char *cp;
930         char last = '\0';
931
932         for (cp = refname; ; cp++) {
933                 char ch = *cp;
934                 if (ch == '\0' || ch == '/')
935                         break;
936                 if (bad_ref_char(ch))
937                         return -1; /* Illegal character in refname. */
938                 if (last == '.' && ch == '.')
939                         return -1; /* Refname contains "..". */
940                 if (last == '@' && ch == '{')
941                         return -1; /* Refname contains "@{". */
942                 last = ch;
943         }
944         if (cp == refname)
945                 return -1; /* Component has zero length. */
946         if (refname[0] == '.') {
947                 if (!(flags & REFNAME_DOT_COMPONENT))
948                         return -1; /* Component starts with '.'. */
949                 /*
950                  * Even if leading dots are allowed, don't allow "."
951                  * as a component (".." is prevented by a rule above).
952                  */
953                 if (refname[1] == '\0')
954                         return -1; /* Component equals ".". */
955         }
956         if (cp - refname >= 5 && !memcmp(cp - 5, ".lock", 5))
957                 return -1; /* Refname ends with ".lock". */
958         return cp - refname;
959 }
960
961 int check_refname_format(const char *refname, int flags)
962 {
963         int component_len, component_count = 0;
964
965         while (1) {
966                 /* We are at the start of a path component. */
967                 component_len = check_refname_component(refname, flags);
968                 if (component_len < 0) {
969                         if ((flags & REFNAME_REFSPEC_PATTERN) &&
970                                         refname[0] == '*' &&
971                                         (refname[1] == '\0' || refname[1] == '/')) {
972                                 /* Accept one wildcard as a full refname component. */
973                                 flags &= ~REFNAME_REFSPEC_PATTERN;
974                                 component_len = 1;
975                         } else {
976                                 return -1;
977                         }
978                 }
979                 component_count++;
980                 if (refname[component_len] == '\0')
981                         break;
982                 /* Skip to next component. */
983                 refname += component_len + 1;
984         }
985
986         if (refname[component_len - 1] == '.')
987                 return -1; /* Refname ends with '.'. */
988         if (!(flags & REFNAME_ALLOW_ONELEVEL) && component_count < 2)
989                 return -1; /* Refname has only one component. */
990         return 0;
991 }
992
993 const char *prettify_refname(const char *name)
994 {
995         return name + (
996                 !prefixcmp(name, "refs/heads/") ? 11 :
997                 !prefixcmp(name, "refs/tags/") ? 10 :
998                 !prefixcmp(name, "refs/remotes/") ? 13 :
999                 0);
1000 }
1001
1002 const char *ref_rev_parse_rules[] = {
1003         "%.*s",
1004         "refs/%.*s",
1005         "refs/tags/%.*s",
1006         "refs/heads/%.*s",
1007         "refs/remotes/%.*s",
1008         "refs/remotes/%.*s/HEAD",
1009         NULL
1010 };
1011
1012 int refname_match(const char *abbrev_name, const char *full_name, const char **rules)
1013 {
1014         const char **p;
1015         const int abbrev_name_len = strlen(abbrev_name);
1016
1017         for (p = rules; *p; p++) {
1018                 if (!strcmp(full_name, mkpath(*p, abbrev_name_len, abbrev_name))) {
1019                         return 1;
1020                 }
1021         }
1022
1023         return 0;
1024 }
1025
1026 static struct ref_lock *verify_lock(struct ref_lock *lock,
1027         const unsigned char *old_sha1, int mustexist)
1028 {
1029         if (read_ref_full(lock->ref_name, lock->old_sha1, mustexist, NULL)) {
1030                 error("Can't verify ref %s", lock->ref_name);
1031                 unlock_ref(lock);
1032                 return NULL;
1033         }
1034         if (hashcmp(lock->old_sha1, old_sha1)) {
1035                 error("Ref %s is at %s but expected %s", lock->ref_name,
1036                         sha1_to_hex(lock->old_sha1), sha1_to_hex(old_sha1));
1037                 unlock_ref(lock);
1038                 return NULL;
1039         }
1040         return lock;
1041 }
1042
1043 static int remove_empty_directories(const char *file)
1044 {
1045         /* we want to create a file but there is a directory there;
1046          * if that is an empty directory (or a directory that contains
1047          * only empty directories), remove them.
1048          */
1049         struct strbuf path;
1050         int result;
1051
1052         strbuf_init(&path, 20);
1053         strbuf_addstr(&path, file);
1054
1055         result = remove_dir_recursively(&path, REMOVE_DIR_EMPTY_ONLY);
1056
1057         strbuf_release(&path);
1058
1059         return result;
1060 }
1061
1062 /*
1063  * Return true iff a reference named refname could be created without
1064  * conflicting with the name of an existing reference.  If oldrefname
1065  * is non-NULL, ignore potential conflicts with oldrefname (e.g.,
1066  * because oldrefname is scheduled for deletion in the same
1067  * operation).
1068  */
1069 static int is_refname_available(const char *refname, const char *oldrefname,
1070                                 struct ref_array *array)
1071 {
1072         int i, namlen = strlen(refname); /* e.g. 'foo/bar' */
1073         for (i = 0; i < array->nr; i++ ) {
1074                 struct ref_entry *entry = array->refs[i];
1075                 /* entry->name could be 'foo' or 'foo/bar/baz' */
1076                 if (!oldrefname || strcmp(oldrefname, entry->name)) {
1077                         int len = strlen(entry->name);
1078                         int cmplen = (namlen < len) ? namlen : len;
1079                         const char *lead = (namlen < len) ? entry->name : refname;
1080                         if (!strncmp(refname, entry->name, cmplen) &&
1081                             lead[cmplen] == '/') {
1082                                 error("'%s' exists; cannot create '%s'",
1083                                       entry->name, refname);
1084                                 return 0;
1085                         }
1086                 }
1087         }
1088         return 1;
1089 }
1090
1091 /*
1092  * *string and *len will only be substituted, and *string returned (for
1093  * later free()ing) if the string passed in is a magic short-hand form
1094  * to name a branch.
1095  */
1096 static char *substitute_branch_name(const char **string, int *len)
1097 {
1098         struct strbuf buf = STRBUF_INIT;
1099         int ret = interpret_branch_name(*string, &buf);
1100
1101         if (ret == *len) {
1102                 size_t size;
1103                 *string = strbuf_detach(&buf, &size);
1104                 *len = size;
1105                 return (char *)*string;
1106         }
1107
1108         return NULL;
1109 }
1110
1111 int dwim_ref(const char *str, int len, unsigned char *sha1, char **ref)
1112 {
1113         char *last_branch = substitute_branch_name(&str, &len);
1114         const char **p, *r;
1115         int refs_found = 0;
1116
1117         *ref = NULL;
1118         for (p = ref_rev_parse_rules; *p; p++) {
1119                 char fullref[PATH_MAX];
1120                 unsigned char sha1_from_ref[20];
1121                 unsigned char *this_result;
1122                 int flag;
1123
1124                 this_result = refs_found ? sha1_from_ref : sha1;
1125                 mksnpath(fullref, sizeof(fullref), *p, len, str);
1126                 r = resolve_ref(fullref, this_result, 1, &flag);
1127                 if (r) {
1128                         if (!refs_found++)
1129                                 *ref = xstrdup(r);
1130                         if (!warn_ambiguous_refs)
1131                                 break;
1132                 } else if ((flag & REF_ISSYMREF) && strcmp(fullref, "HEAD")) {
1133                         warning("ignoring dangling symref %s.", fullref);
1134                 } else if ((flag & REF_ISBROKEN) && strchr(fullref, '/')) {
1135                         warning("ignoring broken ref %s.", fullref);
1136                 }
1137         }
1138         free(last_branch);
1139         return refs_found;
1140 }
1141
1142 int dwim_log(const char *str, int len, unsigned char *sha1, char **log)
1143 {
1144         char *last_branch = substitute_branch_name(&str, &len);
1145         const char **p;
1146         int logs_found = 0;
1147
1148         *log = NULL;
1149         for (p = ref_rev_parse_rules; *p; p++) {
1150                 struct stat st;
1151                 unsigned char hash[20];
1152                 char path[PATH_MAX];
1153                 const char *ref, *it;
1154
1155                 mksnpath(path, sizeof(path), *p, len, str);
1156                 ref = resolve_ref(path, hash, 1, NULL);
1157                 if (!ref)
1158                         continue;
1159                 if (!stat(git_path("logs/%s", path), &st) &&
1160                     S_ISREG(st.st_mode))
1161                         it = path;
1162                 else if (strcmp(ref, path) &&
1163                          !stat(git_path("logs/%s", ref), &st) &&
1164                          S_ISREG(st.st_mode))
1165                         it = ref;
1166                 else
1167                         continue;
1168                 if (!logs_found++) {
1169                         *log = xstrdup(it);
1170                         hashcpy(sha1, hash);
1171                 }
1172                 if (!warn_ambiguous_refs)
1173                         break;
1174         }
1175         free(last_branch);
1176         return logs_found;
1177 }
1178
1179 static struct ref_lock *lock_ref_sha1_basic(const char *refname,
1180                                             const unsigned char *old_sha1,
1181                                             int flags, int *type_p)
1182 {
1183         char *ref_file;
1184         const char *orig_refname = refname;
1185         struct ref_lock *lock;
1186         int last_errno = 0;
1187         int type, lflags;
1188         int mustexist = (old_sha1 && !is_null_sha1(old_sha1));
1189         int missing = 0;
1190
1191         lock = xcalloc(1, sizeof(struct ref_lock));
1192         lock->lock_fd = -1;
1193
1194         refname = resolve_ref(refname, lock->old_sha1, mustexist, &type);
1195         if (!refname && errno == EISDIR) {
1196                 /* we are trying to lock foo but we used to
1197                  * have foo/bar which now does not exist;
1198                  * it is normal for the empty directory 'foo'
1199                  * to remain.
1200                  */
1201                 ref_file = git_path("%s", orig_refname);
1202                 if (remove_empty_directories(ref_file)) {
1203                         last_errno = errno;
1204                         error("there are still refs under '%s'", orig_refname);
1205                         goto error_return;
1206                 }
1207                 refname = resolve_ref(orig_refname, lock->old_sha1, mustexist, &type);
1208         }
1209         if (type_p)
1210             *type_p = type;
1211         if (!refname) {
1212                 last_errno = errno;
1213                 error("unable to resolve reference %s: %s",
1214                         orig_refname, strerror(errno));
1215                 goto error_return;
1216         }
1217         missing = is_null_sha1(lock->old_sha1);
1218         /* When the ref did not exist and we are creating it,
1219          * make sure there is no existing ref that is packed
1220          * whose name begins with our refname, nor a ref whose
1221          * name is a proper prefix of our refname.
1222          */
1223         if (missing &&
1224              !is_refname_available(refname, NULL, get_packed_refs(get_ref_cache(NULL)))) {
1225                 last_errno = ENOTDIR;
1226                 goto error_return;
1227         }
1228
1229         lock->lk = xcalloc(1, sizeof(struct lock_file));
1230
1231         lflags = LOCK_DIE_ON_ERROR;
1232         if (flags & REF_NODEREF) {
1233                 refname = orig_refname;
1234                 lflags |= LOCK_NODEREF;
1235         }
1236         lock->ref_name = xstrdup(refname);
1237         lock->orig_ref_name = xstrdup(orig_refname);
1238         ref_file = git_path("%s", refname);
1239         if (missing)
1240                 lock->force_write = 1;
1241         if ((flags & REF_NODEREF) && (type & REF_ISSYMREF))
1242                 lock->force_write = 1;
1243
1244         if (safe_create_leading_directories(ref_file)) {
1245                 last_errno = errno;
1246                 error("unable to create directory for %s", ref_file);
1247                 goto error_return;
1248         }
1249
1250         lock->lock_fd = hold_lock_file_for_update(lock->lk, ref_file, lflags);
1251         return old_sha1 ? verify_lock(lock, old_sha1, mustexist) : lock;
1252
1253  error_return:
1254         unlock_ref(lock);
1255         errno = last_errno;
1256         return NULL;
1257 }
1258
1259 struct ref_lock *lock_ref_sha1(const char *refname, const unsigned char *old_sha1)
1260 {
1261         char refpath[PATH_MAX];
1262         if (check_refname_format(refname, 0))
1263                 return NULL;
1264         strcpy(refpath, mkpath("refs/%s", refname));
1265         return lock_ref_sha1_basic(refpath, old_sha1, 0, NULL);
1266 }
1267
1268 struct ref_lock *lock_any_ref_for_update(const char *refname,
1269                                          const unsigned char *old_sha1, int flags)
1270 {
1271         if (check_refname_format(refname, REFNAME_ALLOW_ONELEVEL))
1272                 return NULL;
1273         return lock_ref_sha1_basic(refname, old_sha1, flags, NULL);
1274 }
1275
1276 static struct lock_file packlock;
1277
1278 static int repack_without_ref(const char *refname)
1279 {
1280         struct ref_array *packed;
1281         int fd, i;
1282
1283         packed = get_packed_refs(get_ref_cache(NULL));
1284         if (search_ref_array(packed, refname) == NULL)
1285                 return 0;
1286         fd = hold_lock_file_for_update(&packlock, git_path("packed-refs"), 0);
1287         if (fd < 0) {
1288                 unable_to_lock_error(git_path("packed-refs"), errno);
1289                 return error("cannot delete '%s' from packed refs", refname);
1290         }
1291
1292         for (i = 0; i < packed->nr; i++) {
1293                 char line[PATH_MAX + 100];
1294                 int len;
1295                 struct ref_entry *ref = packed->refs[i];
1296
1297                 if (!strcmp(refname, ref->name))
1298                         continue;
1299                 len = snprintf(line, sizeof(line), "%s %s\n",
1300                                sha1_to_hex(ref->sha1), ref->name);
1301                 /* this should not happen but just being defensive */
1302                 if (len > sizeof(line))
1303                         die("too long a refname '%s'", ref->name);
1304                 write_or_die(fd, line, len);
1305         }
1306         return commit_lock_file(&packlock);
1307 }
1308
1309 int delete_ref(const char *refname, const unsigned char *sha1, int delopt)
1310 {
1311         struct ref_lock *lock;
1312         int err, i = 0, ret = 0, flag = 0;
1313
1314         lock = lock_ref_sha1_basic(refname, sha1, 0, &flag);
1315         if (!lock)
1316                 return 1;
1317         if (!(flag & REF_ISPACKED) || flag & REF_ISSYMREF) {
1318                 /* loose */
1319                 const char *path;
1320
1321                 if (!(delopt & REF_NODEREF)) {
1322                         i = strlen(lock->lk->filename) - 5; /* .lock */
1323                         lock->lk->filename[i] = 0;
1324                         path = lock->lk->filename;
1325                 } else {
1326                         path = git_path("%s", refname);
1327                 }
1328                 err = unlink_or_warn(path);
1329                 if (err && errno != ENOENT)
1330                         ret = 1;
1331
1332                 if (!(delopt & REF_NODEREF))
1333                         lock->lk->filename[i] = '.';
1334         }
1335         /* removing the loose one could have resurrected an earlier
1336          * packed one.  Also, if it was not loose we need to repack
1337          * without it.
1338          */
1339         ret |= repack_without_ref(refname);
1340
1341         unlink_or_warn(git_path("logs/%s", lock->ref_name));
1342         invalidate_ref_cache(NULL);
1343         unlock_ref(lock);
1344         return ret;
1345 }
1346
1347 /*
1348  * People using contrib's git-new-workdir have .git/logs/refs ->
1349  * /some/other/path/.git/logs/refs, and that may live on another device.
1350  *
1351  * IOW, to avoid cross device rename errors, the temporary renamed log must
1352  * live into logs/refs.
1353  */
1354 #define TMP_RENAMED_LOG  "logs/refs/.tmp-renamed-log"
1355
1356 int rename_ref(const char *oldrefname, const char *newrefname, const char *logmsg)
1357 {
1358         unsigned char sha1[20], orig_sha1[20];
1359         int flag = 0, logmoved = 0;
1360         struct ref_lock *lock;
1361         struct stat loginfo;
1362         int log = !lstat(git_path("logs/%s", oldrefname), &loginfo);
1363         const char *symref = NULL;
1364         struct ref_cache *refs = get_ref_cache(NULL);
1365
1366         if (log && S_ISLNK(loginfo.st_mode))
1367                 return error("reflog for %s is a symlink", oldrefname);
1368
1369         symref = resolve_ref(oldrefname, orig_sha1, 1, &flag);
1370         if (flag & REF_ISSYMREF)
1371                 return error("refname %s is a symbolic ref, renaming it is not supported",
1372                         oldrefname);
1373         if (!symref)
1374                 return error("refname %s not found", oldrefname);
1375
1376         if (!is_refname_available(newrefname, oldrefname, get_packed_refs(refs)))
1377                 return 1;
1378
1379         if (!is_refname_available(newrefname, oldrefname, get_loose_refs(refs)))
1380                 return 1;
1381
1382         if (log && rename(git_path("logs/%s", oldrefname), git_path(TMP_RENAMED_LOG)))
1383                 return error("unable to move logfile logs/%s to "TMP_RENAMED_LOG": %s",
1384                         oldrefname, strerror(errno));
1385
1386         if (delete_ref(oldrefname, orig_sha1, REF_NODEREF)) {
1387                 error("unable to delete old %s", oldrefname);
1388                 goto rollback;
1389         }
1390
1391         if (!read_ref_full(newrefname, sha1, 1, &flag) &&
1392             delete_ref(newrefname, sha1, REF_NODEREF)) {
1393                 if (errno==EISDIR) {
1394                         if (remove_empty_directories(git_path("%s", newrefname))) {
1395                                 error("Directory not empty: %s", newrefname);
1396                                 goto rollback;
1397                         }
1398                 } else {
1399                         error("unable to delete existing %s", newrefname);
1400                         goto rollback;
1401                 }
1402         }
1403
1404         if (log && safe_create_leading_directories(git_path("logs/%s", newrefname))) {
1405                 error("unable to create directory for %s", newrefname);
1406                 goto rollback;
1407         }
1408
1409  retry:
1410         if (log && rename(git_path(TMP_RENAMED_LOG), git_path("logs/%s", newrefname))) {
1411                 if (errno==EISDIR || errno==ENOTDIR) {
1412                         /*
1413                          * rename(a, b) when b is an existing
1414                          * directory ought to result in ISDIR, but
1415                          * Solaris 5.8 gives ENOTDIR.  Sheesh.
1416                          */
1417                         if (remove_empty_directories(git_path("logs/%s", newrefname))) {
1418                                 error("Directory not empty: logs/%s", newrefname);
1419                                 goto rollback;
1420                         }
1421                         goto retry;
1422                 } else {
1423                         error("unable to move logfile "TMP_RENAMED_LOG" to logs/%s: %s",
1424                                 newrefname, strerror(errno));
1425                         goto rollback;
1426                 }
1427         }
1428         logmoved = log;
1429
1430         lock = lock_ref_sha1_basic(newrefname, NULL, 0, NULL);
1431         if (!lock) {
1432                 error("unable to lock %s for update", newrefname);
1433                 goto rollback;
1434         }
1435         lock->force_write = 1;
1436         hashcpy(lock->old_sha1, orig_sha1);
1437         if (write_ref_sha1(lock, orig_sha1, logmsg)) {
1438                 error("unable to write current sha1 into %s", newrefname);
1439                 goto rollback;
1440         }
1441
1442         return 0;
1443
1444  rollback:
1445         lock = lock_ref_sha1_basic(oldrefname, NULL, 0, NULL);
1446         if (!lock) {
1447                 error("unable to lock %s for rollback", oldrefname);
1448                 goto rollbacklog;
1449         }
1450
1451         lock->force_write = 1;
1452         flag = log_all_ref_updates;
1453         log_all_ref_updates = 0;
1454         if (write_ref_sha1(lock, orig_sha1, NULL))
1455                 error("unable to write current sha1 into %s", oldrefname);
1456         log_all_ref_updates = flag;
1457
1458  rollbacklog:
1459         if (logmoved && rename(git_path("logs/%s", newrefname), git_path("logs/%s", oldrefname)))
1460                 error("unable to restore logfile %s from %s: %s",
1461                         oldrefname, newrefname, strerror(errno));
1462         if (!logmoved && log &&
1463             rename(git_path(TMP_RENAMED_LOG), git_path("logs/%s", oldrefname)))
1464                 error("unable to restore logfile %s from "TMP_RENAMED_LOG": %s",
1465                         oldrefname, strerror(errno));
1466
1467         return 1;
1468 }
1469
1470 int close_ref(struct ref_lock *lock)
1471 {
1472         if (close_lock_file(lock->lk))
1473                 return -1;
1474         lock->lock_fd = -1;
1475         return 0;
1476 }
1477
1478 int commit_ref(struct ref_lock *lock)
1479 {
1480         if (commit_lock_file(lock->lk))
1481                 return -1;
1482         lock->lock_fd = -1;
1483         return 0;
1484 }
1485
1486 void unlock_ref(struct ref_lock *lock)
1487 {
1488         /* Do not free lock->lk -- atexit() still looks at them */
1489         if (lock->lk)
1490                 rollback_lock_file(lock->lk);
1491         free(lock->ref_name);
1492         free(lock->orig_ref_name);
1493         free(lock);
1494 }
1495
1496 /*
1497  * copy the reflog message msg to buf, which has been allocated sufficiently
1498  * large, while cleaning up the whitespaces.  Especially, convert LF to space,
1499  * because reflog file is one line per entry.
1500  */
1501 static int copy_msg(char *buf, const char *msg)
1502 {
1503         char *cp = buf;
1504         char c;
1505         int wasspace = 1;
1506
1507         *cp++ = '\t';
1508         while ((c = *msg++)) {
1509                 if (wasspace && isspace(c))
1510                         continue;
1511                 wasspace = isspace(c);
1512                 if (wasspace)
1513                         c = ' ';
1514                 *cp++ = c;
1515         }
1516         while (buf < cp && isspace(cp[-1]))
1517                 cp--;
1518         *cp++ = '\n';
1519         return cp - buf;
1520 }
1521
1522 int log_ref_setup(const char *refname, char *logfile, int bufsize)
1523 {
1524         int logfd, oflags = O_APPEND | O_WRONLY;
1525
1526         git_snpath(logfile, bufsize, "logs/%s", refname);
1527         if (log_all_ref_updates &&
1528             (!prefixcmp(refname, "refs/heads/") ||
1529              !prefixcmp(refname, "refs/remotes/") ||
1530              !prefixcmp(refname, "refs/notes/") ||
1531              !strcmp(refname, "HEAD"))) {
1532                 if (safe_create_leading_directories(logfile) < 0)
1533                         return error("unable to create directory for %s",
1534                                      logfile);
1535                 oflags |= O_CREAT;
1536         }
1537
1538         logfd = open(logfile, oflags, 0666);
1539         if (logfd < 0) {
1540                 if (!(oflags & O_CREAT) && errno == ENOENT)
1541                         return 0;
1542
1543                 if ((oflags & O_CREAT) && errno == EISDIR) {
1544                         if (remove_empty_directories(logfile)) {
1545                                 return error("There are still logs under '%s'",
1546                                              logfile);
1547                         }
1548                         logfd = open(logfile, oflags, 0666);
1549                 }
1550
1551                 if (logfd < 0)
1552                         return error("Unable to append to %s: %s",
1553                                      logfile, strerror(errno));
1554         }
1555
1556         adjust_shared_perm(logfile);
1557         close(logfd);
1558         return 0;
1559 }
1560
1561 static int log_ref_write(const char *refname, const unsigned char *old_sha1,
1562                          const unsigned char *new_sha1, const char *msg)
1563 {
1564         int logfd, result, written, oflags = O_APPEND | O_WRONLY;
1565         unsigned maxlen, len;
1566         int msglen;
1567         char log_file[PATH_MAX];
1568         char *logrec;
1569         const char *committer;
1570
1571         if (log_all_ref_updates < 0)
1572                 log_all_ref_updates = !is_bare_repository();
1573
1574         result = log_ref_setup(refname, log_file, sizeof(log_file));
1575         if (result)
1576                 return result;
1577
1578         logfd = open(log_file, oflags);
1579         if (logfd < 0)
1580                 return 0;
1581         msglen = msg ? strlen(msg) : 0;
1582         committer = git_committer_info(0);
1583         maxlen = strlen(committer) + msglen + 100;
1584         logrec = xmalloc(maxlen);
1585         len = sprintf(logrec, "%s %s %s\n",
1586                       sha1_to_hex(old_sha1),
1587                       sha1_to_hex(new_sha1),
1588                       committer);
1589         if (msglen)
1590                 len += copy_msg(logrec + len - 1, msg) - 1;
1591         written = len <= maxlen ? write_in_full(logfd, logrec, len) : -1;
1592         free(logrec);
1593         if (close(logfd) != 0 || written != len)
1594                 return error("Unable to append to %s", log_file);
1595         return 0;
1596 }
1597
1598 static int is_branch(const char *refname)
1599 {
1600         return !strcmp(refname, "HEAD") || !prefixcmp(refname, "refs/heads/");
1601 }
1602
1603 int write_ref_sha1(struct ref_lock *lock,
1604         const unsigned char *sha1, const char *logmsg)
1605 {
1606         static char term = '\n';
1607         struct object *o;
1608
1609         if (!lock)
1610                 return -1;
1611         if (!lock->force_write && !hashcmp(lock->old_sha1, sha1)) {
1612                 unlock_ref(lock);
1613                 return 0;
1614         }
1615         o = parse_object(sha1);
1616         if (!o) {
1617                 error("Trying to write ref %s with nonexistent object %s",
1618                         lock->ref_name, sha1_to_hex(sha1));
1619                 unlock_ref(lock);
1620                 return -1;
1621         }
1622         if (o->type != OBJ_COMMIT && is_branch(lock->ref_name)) {
1623                 error("Trying to write non-commit object %s to branch %s",
1624                         sha1_to_hex(sha1), lock->ref_name);
1625                 unlock_ref(lock);
1626                 return -1;
1627         }
1628         if (write_in_full(lock->lock_fd, sha1_to_hex(sha1), 40) != 40 ||
1629             write_in_full(lock->lock_fd, &term, 1) != 1
1630                 || close_ref(lock) < 0) {
1631                 error("Couldn't write %s", lock->lk->filename);
1632                 unlock_ref(lock);
1633                 return -1;
1634         }
1635         clear_loose_ref_cache(get_ref_cache(NULL));
1636         if (log_ref_write(lock->ref_name, lock->old_sha1, sha1, logmsg) < 0 ||
1637             (strcmp(lock->ref_name, lock->orig_ref_name) &&
1638              log_ref_write(lock->orig_ref_name, lock->old_sha1, sha1, logmsg) < 0)) {
1639                 unlock_ref(lock);
1640                 return -1;
1641         }
1642         if (strcmp(lock->orig_ref_name, "HEAD") != 0) {
1643                 /*
1644                  * Special hack: If a branch is updated directly and HEAD
1645                  * points to it (may happen on the remote side of a push
1646                  * for example) then logically the HEAD reflog should be
1647                  * updated too.
1648                  * A generic solution implies reverse symref information,
1649                  * but finding all symrefs pointing to the given branch
1650                  * would be rather costly for this rare event (the direct
1651                  * update of a branch) to be worth it.  So let's cheat and
1652                  * check with HEAD only which should cover 99% of all usage
1653                  * scenarios (even 100% of the default ones).
1654                  */
1655                 unsigned char head_sha1[20];
1656                 int head_flag;
1657                 const char *head_ref;
1658                 head_ref = resolve_ref("HEAD", head_sha1, 1, &head_flag);
1659                 if (head_ref && (head_flag & REF_ISSYMREF) &&
1660                     !strcmp(head_ref, lock->ref_name))
1661                         log_ref_write("HEAD", lock->old_sha1, sha1, logmsg);
1662         }
1663         if (commit_ref(lock)) {
1664                 error("Couldn't set %s", lock->ref_name);
1665                 unlock_ref(lock);
1666                 return -1;
1667         }
1668         unlock_ref(lock);
1669         return 0;
1670 }
1671
1672 int create_symref(const char *ref_target, const char *refs_heads_master,
1673                   const char *logmsg)
1674 {
1675         const char *lockpath;
1676         char ref[1000];
1677         int fd, len, written;
1678         char *git_HEAD = git_pathdup("%s", ref_target);
1679         unsigned char old_sha1[20], new_sha1[20];
1680
1681         if (logmsg && read_ref(ref_target, old_sha1))
1682                 hashclr(old_sha1);
1683
1684         if (safe_create_leading_directories(git_HEAD) < 0)
1685                 return error("unable to create directory for %s", git_HEAD);
1686
1687 #ifndef NO_SYMLINK_HEAD
1688         if (prefer_symlink_refs) {
1689                 unlink(git_HEAD);
1690                 if (!symlink(refs_heads_master, git_HEAD))
1691                         goto done;
1692                 fprintf(stderr, "no symlink - falling back to symbolic ref\n");
1693         }
1694 #endif
1695
1696         len = snprintf(ref, sizeof(ref), "ref: %s\n", refs_heads_master);
1697         if (sizeof(ref) <= len) {
1698                 error("refname too long: %s", refs_heads_master);
1699                 goto error_free_return;
1700         }
1701         lockpath = mkpath("%s.lock", git_HEAD);
1702         fd = open(lockpath, O_CREAT | O_EXCL | O_WRONLY, 0666);
1703         if (fd < 0) {
1704                 error("Unable to open %s for writing", lockpath);
1705                 goto error_free_return;
1706         }
1707         written = write_in_full(fd, ref, len);
1708         if (close(fd) != 0 || written != len) {
1709                 error("Unable to write to %s", lockpath);
1710                 goto error_unlink_return;
1711         }
1712         if (rename(lockpath, git_HEAD) < 0) {
1713                 error("Unable to create %s", git_HEAD);
1714                 goto error_unlink_return;
1715         }
1716         if (adjust_shared_perm(git_HEAD)) {
1717                 error("Unable to fix permissions on %s", lockpath);
1718         error_unlink_return:
1719                 unlink_or_warn(lockpath);
1720         error_free_return:
1721                 free(git_HEAD);
1722                 return -1;
1723         }
1724
1725 #ifndef NO_SYMLINK_HEAD
1726         done:
1727 #endif
1728         if (logmsg && !read_ref(refs_heads_master, new_sha1))
1729                 log_ref_write(ref_target, old_sha1, new_sha1, logmsg);
1730
1731         free(git_HEAD);
1732         return 0;
1733 }
1734
1735 static char *ref_msg(const char *line, const char *endp)
1736 {
1737         const char *ep;
1738         line += 82;
1739         ep = memchr(line, '\n', endp - line);
1740         if (!ep)
1741                 ep = endp;
1742         return xmemdupz(line, ep - line);
1743 }
1744
1745 int read_ref_at(const char *refname, unsigned long at_time, int cnt,
1746                 unsigned char *sha1, char **msg,
1747                 unsigned long *cutoff_time, int *cutoff_tz, int *cutoff_cnt)
1748 {
1749         const char *logfile, *logdata, *logend, *rec, *lastgt, *lastrec;
1750         char *tz_c;
1751         int logfd, tz, reccnt = 0;
1752         struct stat st;
1753         unsigned long date;
1754         unsigned char logged_sha1[20];
1755         void *log_mapped;
1756         size_t mapsz;
1757
1758         logfile = git_path("logs/%s", refname);
1759         logfd = open(logfile, O_RDONLY, 0);
1760         if (logfd < 0)
1761                 die_errno("Unable to read log '%s'", logfile);
1762         fstat(logfd, &st);
1763         if (!st.st_size)
1764                 die("Log %s is empty.", logfile);
1765         mapsz = xsize_t(st.st_size);
1766         log_mapped = xmmap(NULL, mapsz, PROT_READ, MAP_PRIVATE, logfd, 0);
1767         logdata = log_mapped;
1768         close(logfd);
1769
1770         lastrec = NULL;
1771         rec = logend = logdata + st.st_size;
1772         while (logdata < rec) {
1773                 reccnt++;
1774                 if (logdata < rec && *(rec-1) == '\n')
1775                         rec--;
1776                 lastgt = NULL;
1777                 while (logdata < rec && *(rec-1) != '\n') {
1778                         rec--;
1779                         if (*rec == '>')
1780                                 lastgt = rec;
1781                 }
1782                 if (!lastgt)
1783                         die("Log %s is corrupt.", logfile);
1784                 date = strtoul(lastgt + 1, &tz_c, 10);
1785                 if (date <= at_time || cnt == 0) {
1786                         tz = strtoul(tz_c, NULL, 10);
1787                         if (msg)
1788                                 *msg = ref_msg(rec, logend);
1789                         if (cutoff_time)
1790                                 *cutoff_time = date;
1791                         if (cutoff_tz)
1792                                 *cutoff_tz = tz;
1793                         if (cutoff_cnt)
1794                                 *cutoff_cnt = reccnt - 1;
1795                         if (lastrec) {
1796                                 if (get_sha1_hex(lastrec, logged_sha1))
1797                                         die("Log %s is corrupt.", logfile);
1798                                 if (get_sha1_hex(rec + 41, sha1))
1799                                         die("Log %s is corrupt.", logfile);
1800                                 if (hashcmp(logged_sha1, sha1)) {
1801                                         warning("Log %s has gap after %s.",
1802                                                 logfile, show_date(date, tz, DATE_RFC2822));
1803                                 }
1804                         }
1805                         else if (date == at_time) {
1806                                 if (get_sha1_hex(rec + 41, sha1))
1807                                         die("Log %s is corrupt.", logfile);
1808                         }
1809                         else {
1810                                 if (get_sha1_hex(rec + 41, logged_sha1))
1811                                         die("Log %s is corrupt.", logfile);
1812                                 if (hashcmp(logged_sha1, sha1)) {
1813                                         warning("Log %s unexpectedly ended on %s.",
1814                                                 logfile, show_date(date, tz, DATE_RFC2822));
1815                                 }
1816                         }
1817                         munmap(log_mapped, mapsz);
1818                         return 0;
1819                 }
1820                 lastrec = rec;
1821                 if (cnt > 0)
1822                         cnt--;
1823         }
1824
1825         rec = logdata;
1826         while (rec < logend && *rec != '>' && *rec != '\n')
1827                 rec++;
1828         if (rec == logend || *rec == '\n')
1829                 die("Log %s is corrupt.", logfile);
1830         date = strtoul(rec + 1, &tz_c, 10);
1831         tz = strtoul(tz_c, NULL, 10);
1832         if (get_sha1_hex(logdata, sha1))
1833                 die("Log %s is corrupt.", logfile);
1834         if (is_null_sha1(sha1)) {
1835                 if (get_sha1_hex(logdata + 41, sha1))
1836                         die("Log %s is corrupt.", logfile);
1837         }
1838         if (msg)
1839                 *msg = ref_msg(logdata, logend);
1840         munmap(log_mapped, mapsz);
1841
1842         if (cutoff_time)
1843                 *cutoff_time = date;
1844         if (cutoff_tz)
1845                 *cutoff_tz = tz;
1846         if (cutoff_cnt)
1847                 *cutoff_cnt = reccnt;
1848         return 1;
1849 }
1850
1851 int for_each_recent_reflog_ent(const char *refname, each_reflog_ent_fn fn, long ofs, void *cb_data)
1852 {
1853         const char *logfile;
1854         FILE *logfp;
1855         struct strbuf sb = STRBUF_INIT;
1856         int ret = 0;
1857
1858         logfile = git_path("logs/%s", refname);
1859         logfp = fopen(logfile, "r");
1860         if (!logfp)
1861                 return -1;
1862
1863         if (ofs) {
1864                 struct stat statbuf;
1865                 if (fstat(fileno(logfp), &statbuf) ||
1866                     statbuf.st_size < ofs ||
1867                     fseek(logfp, -ofs, SEEK_END) ||
1868                     strbuf_getwholeline(&sb, logfp, '\n')) {
1869                         fclose(logfp);
1870                         strbuf_release(&sb);
1871                         return -1;
1872                 }
1873         }
1874
1875         while (!strbuf_getwholeline(&sb, logfp, '\n')) {
1876                 unsigned char osha1[20], nsha1[20];
1877                 char *email_end, *message;
1878                 unsigned long timestamp;
1879                 int tz;
1880
1881                 /* old SP new SP name <email> SP time TAB msg LF */
1882                 if (sb.len < 83 || sb.buf[sb.len - 1] != '\n' ||
1883                     get_sha1_hex(sb.buf, osha1) || sb.buf[40] != ' ' ||
1884                     get_sha1_hex(sb.buf + 41, nsha1) || sb.buf[81] != ' ' ||
1885                     !(email_end = strchr(sb.buf + 82, '>')) ||
1886                     email_end[1] != ' ' ||
1887                     !(timestamp = strtoul(email_end + 2, &message, 10)) ||
1888                     !message || message[0] != ' ' ||
1889                     (message[1] != '+' && message[1] != '-') ||
1890                     !isdigit(message[2]) || !isdigit(message[3]) ||
1891                     !isdigit(message[4]) || !isdigit(message[5]))
1892                         continue; /* corrupt? */
1893                 email_end[1] = '\0';
1894                 tz = strtol(message + 1, NULL, 10);
1895                 if (message[6] != '\t')
1896                         message += 6;
1897                 else
1898                         message += 7;
1899                 ret = fn(osha1, nsha1, sb.buf + 82, timestamp, tz, message,
1900                          cb_data);
1901                 if (ret)
1902                         break;
1903         }
1904         fclose(logfp);
1905         strbuf_release(&sb);
1906         return ret;
1907 }
1908
1909 int for_each_reflog_ent(const char *refname, each_reflog_ent_fn fn, void *cb_data)
1910 {
1911         return for_each_recent_reflog_ent(refname, fn, 0, cb_data);
1912 }
1913
1914 static int do_for_each_reflog(const char *base, each_ref_fn fn, void *cb_data)
1915 {
1916         DIR *dir = opendir(git_path("logs/%s", base));
1917         int retval = 0;
1918
1919         if (dir) {
1920                 struct dirent *de;
1921                 int baselen = strlen(base);
1922                 char *log = xmalloc(baselen + 257);
1923
1924                 memcpy(log, base, baselen);
1925                 if (baselen && base[baselen-1] != '/')
1926                         log[baselen++] = '/';
1927
1928                 while ((de = readdir(dir)) != NULL) {
1929                         struct stat st;
1930                         int namelen;
1931
1932                         if (de->d_name[0] == '.')
1933                                 continue;
1934                         namelen = strlen(de->d_name);
1935                         if (namelen > 255)
1936                                 continue;
1937                         if (has_extension(de->d_name, ".lock"))
1938                                 continue;
1939                         memcpy(log + baselen, de->d_name, namelen+1);
1940                         if (stat(git_path("logs/%s", log), &st) < 0)
1941                                 continue;
1942                         if (S_ISDIR(st.st_mode)) {
1943                                 retval = do_for_each_reflog(log, fn, cb_data);
1944                         } else {
1945                                 unsigned char sha1[20];
1946                                 if (read_ref_full(log, sha1, 0, NULL))
1947                                         retval = error("bad ref for %s", log);
1948                                 else
1949                                         retval = fn(log, sha1, 0, cb_data);
1950                         }
1951                         if (retval)
1952                                 break;
1953                 }
1954                 free(log);
1955                 closedir(dir);
1956         }
1957         else if (*base)
1958                 return errno;
1959         return retval;
1960 }
1961
1962 int for_each_reflog(each_ref_fn fn, void *cb_data)
1963 {
1964         return do_for_each_reflog("", fn, cb_data);
1965 }
1966
1967 int update_ref(const char *action, const char *refname,
1968                 const unsigned char *sha1, const unsigned char *oldval,
1969                 int flags, enum action_on_err onerr)
1970 {
1971         static struct ref_lock *lock;
1972         lock = lock_any_ref_for_update(refname, oldval, flags);
1973         if (!lock) {
1974                 const char *str = "Cannot lock the ref '%s'.";
1975                 switch (onerr) {
1976                 case MSG_ON_ERR: error(str, refname); break;
1977                 case DIE_ON_ERR: die(str, refname); break;
1978                 case QUIET_ON_ERR: break;
1979                 }
1980                 return 1;
1981         }
1982         if (write_ref_sha1(lock, sha1, action) < 0) {
1983                 const char *str = "Cannot update the ref '%s'.";
1984                 switch (onerr) {
1985                 case MSG_ON_ERR: error(str, refname); break;
1986                 case DIE_ON_ERR: die(str, refname); break;
1987                 case QUIET_ON_ERR: break;
1988                 }
1989                 return 1;
1990         }
1991         return 0;
1992 }
1993
1994 int ref_exists(const char *refname)
1995 {
1996         unsigned char sha1[20];
1997         return !!resolve_ref(refname, sha1, 1, NULL);
1998 }
1999
2000 struct ref *find_ref_by_name(const struct ref *list, const char *name)
2001 {
2002         for ( ; list; list = list->next)
2003                 if (!strcmp(list->name, name))
2004                         return (struct ref *)list;
2005         return NULL;
2006 }
2007
2008 /*
2009  * generate a format suitable for scanf from a ref_rev_parse_rules
2010  * rule, that is replace the "%.*s" spec with a "%s" spec
2011  */
2012 static void gen_scanf_fmt(char *scanf_fmt, const char *rule)
2013 {
2014         char *spec;
2015
2016         spec = strstr(rule, "%.*s");
2017         if (!spec || strstr(spec + 4, "%.*s"))
2018                 die("invalid rule in ref_rev_parse_rules: %s", rule);
2019
2020         /* copy all until spec */
2021         strncpy(scanf_fmt, rule, spec - rule);
2022         scanf_fmt[spec - rule] = '\0';
2023         /* copy new spec */
2024         strcat(scanf_fmt, "%s");
2025         /* copy remaining rule */
2026         strcat(scanf_fmt, spec + 4);
2027
2028         return;
2029 }
2030
2031 char *shorten_unambiguous_ref(const char *refname, int strict)
2032 {
2033         int i;
2034         static char **scanf_fmts;
2035         static int nr_rules;
2036         char *short_name;
2037
2038         /* pre generate scanf formats from ref_rev_parse_rules[] */
2039         if (!nr_rules) {
2040                 size_t total_len = 0;
2041
2042                 /* the rule list is NULL terminated, count them first */
2043                 for (; ref_rev_parse_rules[nr_rules]; nr_rules++)
2044                         /* no +1 because strlen("%s") < strlen("%.*s") */
2045                         total_len += strlen(ref_rev_parse_rules[nr_rules]);
2046
2047                 scanf_fmts = xmalloc(nr_rules * sizeof(char *) + total_len);
2048
2049                 total_len = 0;
2050                 for (i = 0; i < nr_rules; i++) {
2051                         scanf_fmts[i] = (char *)&scanf_fmts[nr_rules]
2052                                         + total_len;
2053                         gen_scanf_fmt(scanf_fmts[i], ref_rev_parse_rules[i]);
2054                         total_len += strlen(ref_rev_parse_rules[i]);
2055                 }
2056         }
2057
2058         /* bail out if there are no rules */
2059         if (!nr_rules)
2060                 return xstrdup(refname);
2061
2062         /* buffer for scanf result, at most refname must fit */
2063         short_name = xstrdup(refname);
2064
2065         /* skip first rule, it will always match */
2066         for (i = nr_rules - 1; i > 0 ; --i) {
2067                 int j;
2068                 int rules_to_fail = i;
2069                 int short_name_len;
2070
2071                 if (1 != sscanf(refname, scanf_fmts[i], short_name))
2072                         continue;
2073
2074                 short_name_len = strlen(short_name);
2075
2076                 /*
2077                  * in strict mode, all (except the matched one) rules
2078                  * must fail to resolve to a valid non-ambiguous ref
2079                  */
2080                 if (strict)
2081                         rules_to_fail = nr_rules;
2082
2083                 /*
2084                  * check if the short name resolves to a valid ref,
2085                  * but use only rules prior to the matched one
2086                  */
2087                 for (j = 0; j < rules_to_fail; j++) {
2088                         const char *rule = ref_rev_parse_rules[j];
2089                         char refname[PATH_MAX];
2090
2091                         /* skip matched rule */
2092                         if (i == j)
2093                                 continue;
2094
2095                         /*
2096                          * the short name is ambiguous, if it resolves
2097                          * (with this previous rule) to a valid ref
2098                          * read_ref() returns 0 on success
2099                          */
2100                         mksnpath(refname, sizeof(refname),
2101                                  rule, short_name_len, short_name);
2102                         if (ref_exists(refname))
2103                                 break;
2104                 }
2105
2106                 /*
2107                  * short name is non-ambiguous if all previous rules
2108                  * haven't resolved to a valid ref
2109                  */
2110                 if (j == rules_to_fail)
2111                         return short_name;
2112         }
2113
2114         free(short_name);
2115         return xstrdup(refname);
2116 }