Merge branch 'jk/t5561-missing-curl'
[git] / refs.c
1 /*
2  * The backend-independent part of the reference module.
3  */
4
5 #include "cache.h"
6 #include "config.h"
7 #include "hashmap.h"
8 #include "lockfile.h"
9 #include "iterator.h"
10 #include "refs.h"
11 #include "refs/refs-internal.h"
12 #include "object.h"
13 #include "tag.h"
14 #include "submodule.h"
15 #include "worktree.h"
16
17 /*
18  * List of all available backends
19  */
20 static struct ref_storage_be *refs_backends = &refs_be_files;
21
22 static struct ref_storage_be *find_ref_storage_backend(const char *name)
23 {
24         struct ref_storage_be *be;
25         for (be = refs_backends; be; be = be->next)
26                 if (!strcmp(be->name, name))
27                         return be;
28         return NULL;
29 }
30
31 int ref_storage_backend_exists(const char *name)
32 {
33         return find_ref_storage_backend(name) != NULL;
34 }
35
36 /*
37  * How to handle various characters in refnames:
38  * 0: An acceptable character for refs
39  * 1: End-of-component
40  * 2: ., look for a preceding . to reject .. in refs
41  * 3: {, look for a preceding @ to reject @{ in refs
42  * 4: A bad character: ASCII control characters, and
43  *    ":", "?", "[", "\", "^", "~", SP, or TAB
44  * 5: *, reject unless REFNAME_REFSPEC_PATTERN is set
45  */
46 static unsigned char refname_disposition[256] = {
47         1, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
48         4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
49         4, 0, 0, 0, 0, 0, 0, 0, 0, 0, 5, 0, 0, 0, 2, 1,
50         0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 4, 0, 0, 0, 0, 4,
51         0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
52         0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 4, 4, 0, 4, 0,
53         0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
54         0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 3, 0, 0, 4, 4
55 };
56
57 /*
58  * Try to read one refname component from the front of refname.
59  * Return the length of the component found, or -1 if the component is
60  * not legal.  It is legal if it is something reasonable to have under
61  * ".git/refs/"; We do not like it if:
62  *
63  * - any path component of it begins with ".", or
64  * - it has double dots "..", or
65  * - it has ASCII control characters, or
66  * - it has ":", "?", "[", "\", "^", "~", SP, or TAB anywhere, or
67  * - it has "*" anywhere unless REFNAME_REFSPEC_PATTERN is set, or
68  * - it ends with a "/", or
69  * - it ends with ".lock", or
70  * - it contains a "@{" portion
71  */
72 static int check_refname_component(const char *refname, int *flags)
73 {
74         const char *cp;
75         char last = '\0';
76
77         for (cp = refname; ; cp++) {
78                 int ch = *cp & 255;
79                 unsigned char disp = refname_disposition[ch];
80                 switch (disp) {
81                 case 1:
82                         goto out;
83                 case 2:
84                         if (last == '.')
85                                 return -1; /* Refname contains "..". */
86                         break;
87                 case 3:
88                         if (last == '@')
89                                 return -1; /* Refname contains "@{". */
90                         break;
91                 case 4:
92                         return -1;
93                 case 5:
94                         if (!(*flags & REFNAME_REFSPEC_PATTERN))
95                                 return -1; /* refspec can't be a pattern */
96
97                         /*
98                          * Unset the pattern flag so that we only accept
99                          * a single asterisk for one side of refspec.
100                          */
101                         *flags &= ~ REFNAME_REFSPEC_PATTERN;
102                         break;
103                 }
104                 last = ch;
105         }
106 out:
107         if (cp == refname)
108                 return 0; /* Component has zero length. */
109         if (refname[0] == '.')
110                 return -1; /* Component starts with '.'. */
111         if (cp - refname >= LOCK_SUFFIX_LEN &&
112             !memcmp(cp - LOCK_SUFFIX_LEN, LOCK_SUFFIX, LOCK_SUFFIX_LEN))
113                 return -1; /* Refname ends with ".lock". */
114         return cp - refname;
115 }
116
117 int check_refname_format(const char *refname, int flags)
118 {
119         int component_len, component_count = 0;
120
121         if (!strcmp(refname, "@"))
122                 /* Refname is a single character '@'. */
123                 return -1;
124
125         while (1) {
126                 /* We are at the start of a path component. */
127                 component_len = check_refname_component(refname, &flags);
128                 if (component_len <= 0)
129                         return -1;
130
131                 component_count++;
132                 if (refname[component_len] == '\0')
133                         break;
134                 /* Skip to next component. */
135                 refname += component_len + 1;
136         }
137
138         if (refname[component_len - 1] == '.')
139                 return -1; /* Refname ends with '.'. */
140         if (!(flags & REFNAME_ALLOW_ONELEVEL) && component_count < 2)
141                 return -1; /* Refname has only one component. */
142         return 0;
143 }
144
145 int refname_is_safe(const char *refname)
146 {
147         const char *rest;
148
149         if (skip_prefix(refname, "refs/", &rest)) {
150                 char *buf;
151                 int result;
152                 size_t restlen = strlen(rest);
153
154                 /* rest must not be empty, or start or end with "/" */
155                 if (!restlen || *rest == '/' || rest[restlen - 1] == '/')
156                         return 0;
157
158                 /*
159                  * Does the refname try to escape refs/?
160                  * For example: refs/foo/../bar is safe but refs/foo/../../bar
161                  * is not.
162                  */
163                 buf = xmallocz(restlen);
164                 result = !normalize_path_copy(buf, rest) && !strcmp(buf, rest);
165                 free(buf);
166                 return result;
167         }
168
169         do {
170                 if (!isupper(*refname) && *refname != '_')
171                         return 0;
172                 refname++;
173         } while (*refname);
174         return 1;
175 }
176
177 /*
178  * Return true if refname, which has the specified oid and flags, can
179  * be resolved to an object in the database. If the referred-to object
180  * does not exist, emit a warning and return false.
181  */
182 int ref_resolves_to_object(const char *refname,
183                            const struct object_id *oid,
184                            unsigned int flags)
185 {
186         if (flags & REF_ISBROKEN)
187                 return 0;
188         if (!has_sha1_file(oid->hash)) {
189                 error("%s does not point to a valid object!", refname);
190                 return 0;
191         }
192         return 1;
193 }
194
195 char *refs_resolve_refdup(struct ref_store *refs,
196                           const char *refname, int resolve_flags,
197                           struct object_id *oid, int *flags)
198 {
199         const char *result;
200
201         result = refs_resolve_ref_unsafe(refs, refname, resolve_flags,
202                                          oid, flags);
203         return xstrdup_or_null(result);
204 }
205
206 char *resolve_refdup(const char *refname, int resolve_flags,
207                      struct object_id *oid, int *flags)
208 {
209         return refs_resolve_refdup(get_main_ref_store(),
210                                    refname, resolve_flags,
211                                    oid, flags);
212 }
213
214 /* The argument to filter_refs */
215 struct ref_filter {
216         const char *pattern;
217         each_ref_fn *fn;
218         void *cb_data;
219 };
220
221 int refs_read_ref_full(struct ref_store *refs, const char *refname,
222                        int resolve_flags, struct object_id *oid, int *flags)
223 {
224         if (refs_resolve_ref_unsafe(refs, refname, resolve_flags, oid, flags))
225                 return 0;
226         return -1;
227 }
228
229 int read_ref_full(const char *refname, int resolve_flags, struct object_id *oid, int *flags)
230 {
231         return refs_read_ref_full(get_main_ref_store(), refname,
232                                   resolve_flags, oid, flags);
233 }
234
235 int read_ref(const char *refname, struct object_id *oid)
236 {
237         return read_ref_full(refname, RESOLVE_REF_READING, oid, NULL);
238 }
239
240 int ref_exists(const char *refname)
241 {
242         return !!resolve_ref_unsafe(refname, RESOLVE_REF_READING, NULL, NULL);
243 }
244
245 static int match_ref_pattern(const char *refname,
246                              const struct string_list_item *item)
247 {
248         int matched = 0;
249         if (item->util == NULL) {
250                 if (!wildmatch(item->string, refname, 0))
251                         matched = 1;
252         } else {
253                 const char *rest;
254                 if (skip_prefix(refname, item->string, &rest) &&
255                     (!*rest || *rest == '/'))
256                         matched = 1;
257         }
258         return matched;
259 }
260
261 int ref_filter_match(const char *refname,
262                      const struct string_list *include_patterns,
263                      const struct string_list *exclude_patterns)
264 {
265         struct string_list_item *item;
266
267         if (exclude_patterns && exclude_patterns->nr) {
268                 for_each_string_list_item(item, exclude_patterns) {
269                         if (match_ref_pattern(refname, item))
270                                 return 0;
271                 }
272         }
273
274         if (include_patterns && include_patterns->nr) {
275                 int found = 0;
276                 for_each_string_list_item(item, include_patterns) {
277                         if (match_ref_pattern(refname, item)) {
278                                 found = 1;
279                                 break;
280                         }
281                 }
282
283                 if (!found)
284                         return 0;
285         }
286         return 1;
287 }
288
289 static int filter_refs(const char *refname, const struct object_id *oid,
290                            int flags, void *data)
291 {
292         struct ref_filter *filter = (struct ref_filter *)data;
293
294         if (wildmatch(filter->pattern, refname, 0))
295                 return 0;
296         return filter->fn(refname, oid, flags, filter->cb_data);
297 }
298
299 enum peel_status peel_object(const struct object_id *name, struct object_id *oid)
300 {
301         struct object *o = lookup_unknown_object(name->hash);
302
303         if (o->type == OBJ_NONE) {
304                 int type = oid_object_info(name, NULL);
305                 if (type < 0 || !object_as_type(o, type, 0))
306                         return PEEL_INVALID;
307         }
308
309         if (o->type != OBJ_TAG)
310                 return PEEL_NON_TAG;
311
312         o = deref_tag_noverify(o);
313         if (!o)
314                 return PEEL_INVALID;
315
316         oidcpy(oid, &o->oid);
317         return PEEL_PEELED;
318 }
319
320 struct warn_if_dangling_data {
321         FILE *fp;
322         const char *refname;
323         const struct string_list *refnames;
324         const char *msg_fmt;
325 };
326
327 static int warn_if_dangling_symref(const char *refname, const struct object_id *oid,
328                                    int flags, void *cb_data)
329 {
330         struct warn_if_dangling_data *d = cb_data;
331         const char *resolves_to;
332
333         if (!(flags & REF_ISSYMREF))
334                 return 0;
335
336         resolves_to = resolve_ref_unsafe(refname, 0, NULL, NULL);
337         if (!resolves_to
338             || (d->refname
339                 ? strcmp(resolves_to, d->refname)
340                 : !string_list_has_string(d->refnames, resolves_to))) {
341                 return 0;
342         }
343
344         fprintf(d->fp, d->msg_fmt, refname);
345         fputc('\n', d->fp);
346         return 0;
347 }
348
349 void warn_dangling_symref(FILE *fp, const char *msg_fmt, const char *refname)
350 {
351         struct warn_if_dangling_data data;
352
353         data.fp = fp;
354         data.refname = refname;
355         data.refnames = NULL;
356         data.msg_fmt = msg_fmt;
357         for_each_rawref(warn_if_dangling_symref, &data);
358 }
359
360 void warn_dangling_symrefs(FILE *fp, const char *msg_fmt, const struct string_list *refnames)
361 {
362         struct warn_if_dangling_data data;
363
364         data.fp = fp;
365         data.refname = NULL;
366         data.refnames = refnames;
367         data.msg_fmt = msg_fmt;
368         for_each_rawref(warn_if_dangling_symref, &data);
369 }
370
371 int refs_for_each_tag_ref(struct ref_store *refs, each_ref_fn fn, void *cb_data)
372 {
373         return refs_for_each_ref_in(refs, "refs/tags/", fn, cb_data);
374 }
375
376 int for_each_tag_ref(each_ref_fn fn, void *cb_data)
377 {
378         return refs_for_each_tag_ref(get_main_ref_store(), fn, cb_data);
379 }
380
381 int refs_for_each_branch_ref(struct ref_store *refs, each_ref_fn fn, void *cb_data)
382 {
383         return refs_for_each_ref_in(refs, "refs/heads/", fn, cb_data);
384 }
385
386 int for_each_branch_ref(each_ref_fn fn, void *cb_data)
387 {
388         return refs_for_each_branch_ref(get_main_ref_store(), fn, cb_data);
389 }
390
391 int refs_for_each_remote_ref(struct ref_store *refs, each_ref_fn fn, void *cb_data)
392 {
393         return refs_for_each_ref_in(refs, "refs/remotes/", fn, cb_data);
394 }
395
396 int for_each_remote_ref(each_ref_fn fn, void *cb_data)
397 {
398         return refs_for_each_remote_ref(get_main_ref_store(), fn, cb_data);
399 }
400
401 int head_ref_namespaced(each_ref_fn fn, void *cb_data)
402 {
403         struct strbuf buf = STRBUF_INIT;
404         int ret = 0;
405         struct object_id oid;
406         int flag;
407
408         strbuf_addf(&buf, "%sHEAD", get_git_namespace());
409         if (!read_ref_full(buf.buf, RESOLVE_REF_READING, &oid, &flag))
410                 ret = fn(buf.buf, &oid, flag, cb_data);
411         strbuf_release(&buf);
412
413         return ret;
414 }
415
416 void normalize_glob_ref(struct string_list_item *item, const char *prefix,
417                         const char *pattern)
418 {
419         struct strbuf normalized_pattern = STRBUF_INIT;
420
421         if (*pattern == '/')
422                 BUG("pattern must not start with '/'");
423
424         if (prefix) {
425                 strbuf_addstr(&normalized_pattern, prefix);
426         }
427         else if (!starts_with(pattern, "refs/"))
428                 strbuf_addstr(&normalized_pattern, "refs/");
429         strbuf_addstr(&normalized_pattern, pattern);
430         strbuf_strip_suffix(&normalized_pattern, "/");
431
432         item->string = strbuf_detach(&normalized_pattern, NULL);
433         item->util = has_glob_specials(pattern) ? NULL : item->string;
434         strbuf_release(&normalized_pattern);
435 }
436
437 int for_each_glob_ref_in(each_ref_fn fn, const char *pattern,
438         const char *prefix, void *cb_data)
439 {
440         struct strbuf real_pattern = STRBUF_INIT;
441         struct ref_filter filter;
442         int ret;
443
444         if (!prefix && !starts_with(pattern, "refs/"))
445                 strbuf_addstr(&real_pattern, "refs/");
446         else if (prefix)
447                 strbuf_addstr(&real_pattern, prefix);
448         strbuf_addstr(&real_pattern, pattern);
449
450         if (!has_glob_specials(pattern)) {
451                 /* Append implied '/' '*' if not present. */
452                 strbuf_complete(&real_pattern, '/');
453                 /* No need to check for '*', there is none. */
454                 strbuf_addch(&real_pattern, '*');
455         }
456
457         filter.pattern = real_pattern.buf;
458         filter.fn = fn;
459         filter.cb_data = cb_data;
460         ret = for_each_ref(filter_refs, &filter);
461
462         strbuf_release(&real_pattern);
463         return ret;
464 }
465
466 int for_each_glob_ref(each_ref_fn fn, const char *pattern, void *cb_data)
467 {
468         return for_each_glob_ref_in(fn, pattern, NULL, cb_data);
469 }
470
471 const char *prettify_refname(const char *name)
472 {
473         if (skip_prefix(name, "refs/heads/", &name) ||
474             skip_prefix(name, "refs/tags/", &name) ||
475             skip_prefix(name, "refs/remotes/", &name))
476                 ; /* nothing */
477         return name;
478 }
479
480 static const char *ref_rev_parse_rules[] = {
481         "%.*s",
482         "refs/%.*s",
483         "refs/tags/%.*s",
484         "refs/heads/%.*s",
485         "refs/remotes/%.*s",
486         "refs/remotes/%.*s/HEAD",
487         NULL
488 };
489
490 int refname_match(const char *abbrev_name, const char *full_name)
491 {
492         const char **p;
493         const int abbrev_name_len = strlen(abbrev_name);
494
495         for (p = ref_rev_parse_rules; *p; p++) {
496                 if (!strcmp(full_name, mkpath(*p, abbrev_name_len, abbrev_name))) {
497                         return 1;
498                 }
499         }
500
501         return 0;
502 }
503
504 /*
505  * *string and *len will only be substituted, and *string returned (for
506  * later free()ing) if the string passed in is a magic short-hand form
507  * to name a branch.
508  */
509 static char *substitute_branch_name(const char **string, int *len)
510 {
511         struct strbuf buf = STRBUF_INIT;
512         int ret = interpret_branch_name(*string, *len, &buf, 0);
513
514         if (ret == *len) {
515                 size_t size;
516                 *string = strbuf_detach(&buf, &size);
517                 *len = size;
518                 return (char *)*string;
519         }
520
521         return NULL;
522 }
523
524 int dwim_ref(const char *str, int len, struct object_id *oid, char **ref)
525 {
526         char *last_branch = substitute_branch_name(&str, &len);
527         int   refs_found  = expand_ref(str, len, oid, ref);
528         free(last_branch);
529         return refs_found;
530 }
531
532 int expand_ref(const char *str, int len, struct object_id *oid, char **ref)
533 {
534         const char **p, *r;
535         int refs_found = 0;
536         struct strbuf fullref = STRBUF_INIT;
537
538         *ref = NULL;
539         for (p = ref_rev_parse_rules; *p; p++) {
540                 struct object_id oid_from_ref;
541                 struct object_id *this_result;
542                 int flag;
543
544                 this_result = refs_found ? &oid_from_ref : oid;
545                 strbuf_reset(&fullref);
546                 strbuf_addf(&fullref, *p, len, str);
547                 r = resolve_ref_unsafe(fullref.buf, RESOLVE_REF_READING,
548                                        this_result, &flag);
549                 if (r) {
550                         if (!refs_found++)
551                                 *ref = xstrdup(r);
552                         if (!warn_ambiguous_refs)
553                                 break;
554                 } else if ((flag & REF_ISSYMREF) && strcmp(fullref.buf, "HEAD")) {
555                         warning("ignoring dangling symref %s.", fullref.buf);
556                 } else if ((flag & REF_ISBROKEN) && strchr(fullref.buf, '/')) {
557                         warning("ignoring broken ref %s.", fullref.buf);
558                 }
559         }
560         strbuf_release(&fullref);
561         return refs_found;
562 }
563
564 int dwim_log(const char *str, int len, struct object_id *oid, char **log)
565 {
566         char *last_branch = substitute_branch_name(&str, &len);
567         const char **p;
568         int logs_found = 0;
569         struct strbuf path = STRBUF_INIT;
570
571         *log = NULL;
572         for (p = ref_rev_parse_rules; *p; p++) {
573                 struct object_id hash;
574                 const char *ref, *it;
575
576                 strbuf_reset(&path);
577                 strbuf_addf(&path, *p, len, str);
578                 ref = resolve_ref_unsafe(path.buf, RESOLVE_REF_READING,
579                                          &hash, NULL);
580                 if (!ref)
581                         continue;
582                 if (reflog_exists(path.buf))
583                         it = path.buf;
584                 else if (strcmp(ref, path.buf) && reflog_exists(ref))
585                         it = ref;
586                 else
587                         continue;
588                 if (!logs_found++) {
589                         *log = xstrdup(it);
590                         oidcpy(oid, &hash);
591                 }
592                 if (!warn_ambiguous_refs)
593                         break;
594         }
595         strbuf_release(&path);
596         free(last_branch);
597         return logs_found;
598 }
599
600 static int is_per_worktree_ref(const char *refname)
601 {
602         return !strcmp(refname, "HEAD") ||
603                 starts_with(refname, "refs/bisect/");
604 }
605
606 static int is_pseudoref_syntax(const char *refname)
607 {
608         const char *c;
609
610         for (c = refname; *c; c++) {
611                 if (!isupper(*c) && *c != '-' && *c != '_')
612                         return 0;
613         }
614
615         return 1;
616 }
617
618 enum ref_type ref_type(const char *refname)
619 {
620         if (is_per_worktree_ref(refname))
621                 return REF_TYPE_PER_WORKTREE;
622         if (is_pseudoref_syntax(refname))
623                 return REF_TYPE_PSEUDOREF;
624        return REF_TYPE_NORMAL;
625 }
626
627 long get_files_ref_lock_timeout_ms(void)
628 {
629         static int configured = 0;
630
631         /* The default timeout is 100 ms: */
632         static int timeout_ms = 100;
633
634         if (!configured) {
635                 git_config_get_int("core.filesreflocktimeout", &timeout_ms);
636                 configured = 1;
637         }
638
639         return timeout_ms;
640 }
641
642 static int write_pseudoref(const char *pseudoref, const struct object_id *oid,
643                            const struct object_id *old_oid, struct strbuf *err)
644 {
645         const char *filename;
646         int fd;
647         static struct lock_file lock;
648         struct strbuf buf = STRBUF_INIT;
649         int ret = -1;
650
651         if (!oid)
652                 return 0;
653
654         strbuf_addf(&buf, "%s\n", oid_to_hex(oid));
655
656         filename = git_path("%s", pseudoref);
657         fd = hold_lock_file_for_update_timeout(&lock, filename,
658                                                LOCK_DIE_ON_ERROR,
659                                                get_files_ref_lock_timeout_ms());
660         if (fd < 0) {
661                 strbuf_addf(err, "could not open '%s' for writing: %s",
662                             filename, strerror(errno));
663                 goto done;
664         }
665
666         if (old_oid) {
667                 struct object_id actual_old_oid;
668
669                 if (read_ref(pseudoref, &actual_old_oid))
670                         die("could not read ref '%s'", pseudoref);
671                 if (oidcmp(&actual_old_oid, old_oid)) {
672                         strbuf_addf(err, "unexpected sha1 when writing '%s'", pseudoref);
673                         rollback_lock_file(&lock);
674                         goto done;
675                 }
676         }
677
678         if (write_in_full(fd, buf.buf, buf.len) < 0) {
679                 strbuf_addf(err, "could not write to '%s'", filename);
680                 rollback_lock_file(&lock);
681                 goto done;
682         }
683
684         commit_lock_file(&lock);
685         ret = 0;
686 done:
687         strbuf_release(&buf);
688         return ret;
689 }
690
691 static int delete_pseudoref(const char *pseudoref, const struct object_id *old_oid)
692 {
693         static struct lock_file lock;
694         const char *filename;
695
696         filename = git_path("%s", pseudoref);
697
698         if (old_oid && !is_null_oid(old_oid)) {
699                 int fd;
700                 struct object_id actual_old_oid;
701
702                 fd = hold_lock_file_for_update_timeout(
703                                 &lock, filename, LOCK_DIE_ON_ERROR,
704                                 get_files_ref_lock_timeout_ms());
705                 if (fd < 0)
706                         die_errno(_("Could not open '%s' for writing"), filename);
707                 if (read_ref(pseudoref, &actual_old_oid))
708                         die("could not read ref '%s'", pseudoref);
709                 if (oidcmp(&actual_old_oid, old_oid)) {
710                         warning("Unexpected sha1 when deleting %s", pseudoref);
711                         rollback_lock_file(&lock);
712                         return -1;
713                 }
714
715                 unlink(filename);
716                 rollback_lock_file(&lock);
717         } else {
718                 unlink(filename);
719         }
720
721         return 0;
722 }
723
724 int refs_delete_ref(struct ref_store *refs, const char *msg,
725                     const char *refname,
726                     const struct object_id *old_oid,
727                     unsigned int flags)
728 {
729         struct ref_transaction *transaction;
730         struct strbuf err = STRBUF_INIT;
731
732         if (ref_type(refname) == REF_TYPE_PSEUDOREF) {
733                 assert(refs == get_main_ref_store());
734                 return delete_pseudoref(refname, old_oid);
735         }
736
737         transaction = ref_store_transaction_begin(refs, &err);
738         if (!transaction ||
739             ref_transaction_delete(transaction, refname, old_oid,
740                                    flags, msg, &err) ||
741             ref_transaction_commit(transaction, &err)) {
742                 error("%s", err.buf);
743                 ref_transaction_free(transaction);
744                 strbuf_release(&err);
745                 return 1;
746         }
747         ref_transaction_free(transaction);
748         strbuf_release(&err);
749         return 0;
750 }
751
752 int delete_ref(const char *msg, const char *refname,
753                const struct object_id *old_oid, unsigned int flags)
754 {
755         return refs_delete_ref(get_main_ref_store(), msg, refname,
756                                old_oid, flags);
757 }
758
759 int copy_reflog_msg(char *buf, const char *msg)
760 {
761         char *cp = buf;
762         char c;
763         int wasspace = 1;
764
765         *cp++ = '\t';
766         while ((c = *msg++)) {
767                 if (wasspace && isspace(c))
768                         continue;
769                 wasspace = isspace(c);
770                 if (wasspace)
771                         c = ' ';
772                 *cp++ = c;
773         }
774         while (buf < cp && isspace(cp[-1]))
775                 cp--;
776         *cp++ = '\n';
777         return cp - buf;
778 }
779
780 int should_autocreate_reflog(const char *refname)
781 {
782         switch (log_all_ref_updates) {
783         case LOG_REFS_ALWAYS:
784                 return 1;
785         case LOG_REFS_NORMAL:
786                 return starts_with(refname, "refs/heads/") ||
787                         starts_with(refname, "refs/remotes/") ||
788                         starts_with(refname, "refs/notes/") ||
789                         !strcmp(refname, "HEAD");
790         default:
791                 return 0;
792         }
793 }
794
795 int is_branch(const char *refname)
796 {
797         return !strcmp(refname, "HEAD") || starts_with(refname, "refs/heads/");
798 }
799
800 struct read_ref_at_cb {
801         const char *refname;
802         timestamp_t at_time;
803         int cnt;
804         int reccnt;
805         struct object_id *oid;
806         int found_it;
807
808         struct object_id ooid;
809         struct object_id noid;
810         int tz;
811         timestamp_t date;
812         char **msg;
813         timestamp_t *cutoff_time;
814         int *cutoff_tz;
815         int *cutoff_cnt;
816 };
817
818 static int read_ref_at_ent(struct object_id *ooid, struct object_id *noid,
819                 const char *email, timestamp_t timestamp, int tz,
820                 const char *message, void *cb_data)
821 {
822         struct read_ref_at_cb *cb = cb_data;
823
824         cb->reccnt++;
825         cb->tz = tz;
826         cb->date = timestamp;
827
828         if (timestamp <= cb->at_time || cb->cnt == 0) {
829                 if (cb->msg)
830                         *cb->msg = xstrdup(message);
831                 if (cb->cutoff_time)
832                         *cb->cutoff_time = timestamp;
833                 if (cb->cutoff_tz)
834                         *cb->cutoff_tz = tz;
835                 if (cb->cutoff_cnt)
836                         *cb->cutoff_cnt = cb->reccnt - 1;
837                 /*
838                  * we have not yet updated cb->[n|o]oid so they still
839                  * hold the values for the previous record.
840                  */
841                 if (!is_null_oid(&cb->ooid)) {
842                         oidcpy(cb->oid, noid);
843                         if (oidcmp(&cb->ooid, noid))
844                                 warning("Log for ref %s has gap after %s.",
845                                         cb->refname, show_date(cb->date, cb->tz, DATE_MODE(RFC2822)));
846                 }
847                 else if (cb->date == cb->at_time)
848                         oidcpy(cb->oid, noid);
849                 else if (oidcmp(noid, cb->oid))
850                         warning("Log for ref %s unexpectedly ended on %s.",
851                                 cb->refname, show_date(cb->date, cb->tz,
852                                                        DATE_MODE(RFC2822)));
853                 oidcpy(&cb->ooid, ooid);
854                 oidcpy(&cb->noid, noid);
855                 cb->found_it = 1;
856                 return 1;
857         }
858         oidcpy(&cb->ooid, ooid);
859         oidcpy(&cb->noid, noid);
860         if (cb->cnt > 0)
861                 cb->cnt--;
862         return 0;
863 }
864
865 static int read_ref_at_ent_oldest(struct object_id *ooid, struct object_id *noid,
866                                   const char *email, timestamp_t timestamp,
867                                   int tz, const char *message, void *cb_data)
868 {
869         struct read_ref_at_cb *cb = cb_data;
870
871         if (cb->msg)
872                 *cb->msg = xstrdup(message);
873         if (cb->cutoff_time)
874                 *cb->cutoff_time = timestamp;
875         if (cb->cutoff_tz)
876                 *cb->cutoff_tz = tz;
877         if (cb->cutoff_cnt)
878                 *cb->cutoff_cnt = cb->reccnt;
879         oidcpy(cb->oid, ooid);
880         if (is_null_oid(cb->oid))
881                 oidcpy(cb->oid, noid);
882         /* We just want the first entry */
883         return 1;
884 }
885
886 int read_ref_at(const char *refname, unsigned int flags, timestamp_t at_time, int cnt,
887                 struct object_id *oid, char **msg,
888                 timestamp_t *cutoff_time, int *cutoff_tz, int *cutoff_cnt)
889 {
890         struct read_ref_at_cb cb;
891
892         memset(&cb, 0, sizeof(cb));
893         cb.refname = refname;
894         cb.at_time = at_time;
895         cb.cnt = cnt;
896         cb.msg = msg;
897         cb.cutoff_time = cutoff_time;
898         cb.cutoff_tz = cutoff_tz;
899         cb.cutoff_cnt = cutoff_cnt;
900         cb.oid = oid;
901
902         for_each_reflog_ent_reverse(refname, read_ref_at_ent, &cb);
903
904         if (!cb.reccnt) {
905                 if (flags & GET_OID_QUIETLY)
906                         exit(128);
907                 else
908                         die("Log for %s is empty.", refname);
909         }
910         if (cb.found_it)
911                 return 0;
912
913         for_each_reflog_ent(refname, read_ref_at_ent_oldest, &cb);
914
915         return 1;
916 }
917
918 struct ref_transaction *ref_store_transaction_begin(struct ref_store *refs,
919                                                     struct strbuf *err)
920 {
921         struct ref_transaction *tr;
922         assert(err);
923
924         tr = xcalloc(1, sizeof(struct ref_transaction));
925         tr->ref_store = refs;
926         return tr;
927 }
928
929 struct ref_transaction *ref_transaction_begin(struct strbuf *err)
930 {
931         return ref_store_transaction_begin(get_main_ref_store(), err);
932 }
933
934 void ref_transaction_free(struct ref_transaction *transaction)
935 {
936         size_t i;
937
938         if (!transaction)
939                 return;
940
941         switch (transaction->state) {
942         case REF_TRANSACTION_OPEN:
943         case REF_TRANSACTION_CLOSED:
944                 /* OK */
945                 break;
946         case REF_TRANSACTION_PREPARED:
947                 die("BUG: free called on a prepared reference transaction");
948                 break;
949         default:
950                 die("BUG: unexpected reference transaction state");
951                 break;
952         }
953
954         for (i = 0; i < transaction->nr; i++) {
955                 free(transaction->updates[i]->msg);
956                 free(transaction->updates[i]);
957         }
958         free(transaction->updates);
959         free(transaction);
960 }
961
962 struct ref_update *ref_transaction_add_update(
963                 struct ref_transaction *transaction,
964                 const char *refname, unsigned int flags,
965                 const struct object_id *new_oid,
966                 const struct object_id *old_oid,
967                 const char *msg)
968 {
969         struct ref_update *update;
970
971         if (transaction->state != REF_TRANSACTION_OPEN)
972                 die("BUG: update called for transaction that is not open");
973
974         FLEX_ALLOC_STR(update, refname, refname);
975         ALLOC_GROW(transaction->updates, transaction->nr + 1, transaction->alloc);
976         transaction->updates[transaction->nr++] = update;
977
978         update->flags = flags;
979
980         if (flags & REF_HAVE_NEW)
981                 oidcpy(&update->new_oid, new_oid);
982         if (flags & REF_HAVE_OLD)
983                 oidcpy(&update->old_oid, old_oid);
984         update->msg = xstrdup_or_null(msg);
985         return update;
986 }
987
988 int ref_transaction_update(struct ref_transaction *transaction,
989                            const char *refname,
990                            const struct object_id *new_oid,
991                            const struct object_id *old_oid,
992                            unsigned int flags, const char *msg,
993                            struct strbuf *err)
994 {
995         assert(err);
996
997         if ((new_oid && !is_null_oid(new_oid)) ?
998             check_refname_format(refname, REFNAME_ALLOW_ONELEVEL) :
999             !refname_is_safe(refname)) {
1000                 strbuf_addf(err, "refusing to update ref with bad name '%s'",
1001                             refname);
1002                 return -1;
1003         }
1004
1005         if (flags & ~REF_TRANSACTION_UPDATE_ALLOWED_FLAGS)
1006                 BUG("illegal flags 0x%x passed to ref_transaction_update()", flags);
1007
1008         flags |= (new_oid ? REF_HAVE_NEW : 0) | (old_oid ? REF_HAVE_OLD : 0);
1009
1010         ref_transaction_add_update(transaction, refname, flags,
1011                                    new_oid, old_oid, msg);
1012         return 0;
1013 }
1014
1015 int ref_transaction_create(struct ref_transaction *transaction,
1016                            const char *refname,
1017                            const struct object_id *new_oid,
1018                            unsigned int flags, const char *msg,
1019                            struct strbuf *err)
1020 {
1021         if (!new_oid || is_null_oid(new_oid))
1022                 die("BUG: create called without valid new_oid");
1023         return ref_transaction_update(transaction, refname, new_oid,
1024                                       &null_oid, flags, msg, err);
1025 }
1026
1027 int ref_transaction_delete(struct ref_transaction *transaction,
1028                            const char *refname,
1029                            const struct object_id *old_oid,
1030                            unsigned int flags, const char *msg,
1031                            struct strbuf *err)
1032 {
1033         if (old_oid && is_null_oid(old_oid))
1034                 die("BUG: delete called with old_oid set to zeros");
1035         return ref_transaction_update(transaction, refname,
1036                                       &null_oid, old_oid,
1037                                       flags, msg, err);
1038 }
1039
1040 int ref_transaction_verify(struct ref_transaction *transaction,
1041                            const char *refname,
1042                            const struct object_id *old_oid,
1043                            unsigned int flags,
1044                            struct strbuf *err)
1045 {
1046         if (!old_oid)
1047                 die("BUG: verify called with old_oid set to NULL");
1048         return ref_transaction_update(transaction, refname,
1049                                       NULL, old_oid,
1050                                       flags, NULL, err);
1051 }
1052
1053 int refs_update_ref(struct ref_store *refs, const char *msg,
1054                     const char *refname, const struct object_id *new_oid,
1055                     const struct object_id *old_oid, unsigned int flags,
1056                     enum action_on_err onerr)
1057 {
1058         struct ref_transaction *t = NULL;
1059         struct strbuf err = STRBUF_INIT;
1060         int ret = 0;
1061
1062         if (ref_type(refname) == REF_TYPE_PSEUDOREF) {
1063                 assert(refs == get_main_ref_store());
1064                 ret = write_pseudoref(refname, new_oid, old_oid, &err);
1065         } else {
1066                 t = ref_store_transaction_begin(refs, &err);
1067                 if (!t ||
1068                     ref_transaction_update(t, refname, new_oid, old_oid,
1069                                            flags, msg, &err) ||
1070                     ref_transaction_commit(t, &err)) {
1071                         ret = 1;
1072                         ref_transaction_free(t);
1073                 }
1074         }
1075         if (ret) {
1076                 const char *str = "update_ref failed for ref '%s': %s";
1077
1078                 switch (onerr) {
1079                 case UPDATE_REFS_MSG_ON_ERR:
1080                         error(str, refname, err.buf);
1081                         break;
1082                 case UPDATE_REFS_DIE_ON_ERR:
1083                         die(str, refname, err.buf);
1084                         break;
1085                 case UPDATE_REFS_QUIET_ON_ERR:
1086                         break;
1087                 }
1088                 strbuf_release(&err);
1089                 return 1;
1090         }
1091         strbuf_release(&err);
1092         if (t)
1093                 ref_transaction_free(t);
1094         return 0;
1095 }
1096
1097 int update_ref(const char *msg, const char *refname,
1098                const struct object_id *new_oid,
1099                const struct object_id *old_oid,
1100                unsigned int flags, enum action_on_err onerr)
1101 {
1102         return refs_update_ref(get_main_ref_store(), msg, refname, new_oid,
1103                                old_oid, flags, onerr);
1104 }
1105
1106 char *shorten_unambiguous_ref(const char *refname, int strict)
1107 {
1108         int i;
1109         static char **scanf_fmts;
1110         static int nr_rules;
1111         char *short_name;
1112         struct strbuf resolved_buf = STRBUF_INIT;
1113
1114         if (!nr_rules) {
1115                 /*
1116                  * Pre-generate scanf formats from ref_rev_parse_rules[].
1117                  * Generate a format suitable for scanf from a
1118                  * ref_rev_parse_rules rule by interpolating "%s" at the
1119                  * location of the "%.*s".
1120                  */
1121                 size_t total_len = 0;
1122                 size_t offset = 0;
1123
1124                 /* the rule list is NULL terminated, count them first */
1125                 for (nr_rules = 0; ref_rev_parse_rules[nr_rules]; nr_rules++)
1126                         /* -2 for strlen("%.*s") - strlen("%s"); +1 for NUL */
1127                         total_len += strlen(ref_rev_parse_rules[nr_rules]) - 2 + 1;
1128
1129                 scanf_fmts = xmalloc(st_add(st_mult(sizeof(char *), nr_rules), total_len));
1130
1131                 offset = 0;
1132                 for (i = 0; i < nr_rules; i++) {
1133                         assert(offset < total_len);
1134                         scanf_fmts[i] = (char *)&scanf_fmts[nr_rules] + offset;
1135                         offset += snprintf(scanf_fmts[i], total_len - offset,
1136                                            ref_rev_parse_rules[i], 2, "%s") + 1;
1137                 }
1138         }
1139
1140         /* bail out if there are no rules */
1141         if (!nr_rules)
1142                 return xstrdup(refname);
1143
1144         /* buffer for scanf result, at most refname must fit */
1145         short_name = xstrdup(refname);
1146
1147         /* skip first rule, it will always match */
1148         for (i = nr_rules - 1; i > 0 ; --i) {
1149                 int j;
1150                 int rules_to_fail = i;
1151                 int short_name_len;
1152
1153                 if (1 != sscanf(refname, scanf_fmts[i], short_name))
1154                         continue;
1155
1156                 short_name_len = strlen(short_name);
1157
1158                 /*
1159                  * in strict mode, all (except the matched one) rules
1160                  * must fail to resolve to a valid non-ambiguous ref
1161                  */
1162                 if (strict)
1163                         rules_to_fail = nr_rules;
1164
1165                 /*
1166                  * check if the short name resolves to a valid ref,
1167                  * but use only rules prior to the matched one
1168                  */
1169                 for (j = 0; j < rules_to_fail; j++) {
1170                         const char *rule = ref_rev_parse_rules[j];
1171
1172                         /* skip matched rule */
1173                         if (i == j)
1174                                 continue;
1175
1176                         /*
1177                          * the short name is ambiguous, if it resolves
1178                          * (with this previous rule) to a valid ref
1179                          * read_ref() returns 0 on success
1180                          */
1181                         strbuf_reset(&resolved_buf);
1182                         strbuf_addf(&resolved_buf, rule,
1183                                     short_name_len, short_name);
1184                         if (ref_exists(resolved_buf.buf))
1185                                 break;
1186                 }
1187
1188                 /*
1189                  * short name is non-ambiguous if all previous rules
1190                  * haven't resolved to a valid ref
1191                  */
1192                 if (j == rules_to_fail) {
1193                         strbuf_release(&resolved_buf);
1194                         return short_name;
1195                 }
1196         }
1197
1198         strbuf_release(&resolved_buf);
1199         free(short_name);
1200         return xstrdup(refname);
1201 }
1202
1203 static struct string_list *hide_refs;
1204
1205 int parse_hide_refs_config(const char *var, const char *value, const char *section)
1206 {
1207         const char *key;
1208         if (!strcmp("transfer.hiderefs", var) ||
1209             (!parse_config_key(var, section, NULL, NULL, &key) &&
1210              !strcmp(key, "hiderefs"))) {
1211                 char *ref;
1212                 int len;
1213
1214                 if (!value)
1215                         return config_error_nonbool(var);
1216                 ref = xstrdup(value);
1217                 len = strlen(ref);
1218                 while (len && ref[len - 1] == '/')
1219                         ref[--len] = '\0';
1220                 if (!hide_refs) {
1221                         hide_refs = xcalloc(1, sizeof(*hide_refs));
1222                         hide_refs->strdup_strings = 1;
1223                 }
1224                 string_list_append(hide_refs, ref);
1225         }
1226         return 0;
1227 }
1228
1229 int ref_is_hidden(const char *refname, const char *refname_full)
1230 {
1231         int i;
1232
1233         if (!hide_refs)
1234                 return 0;
1235         for (i = hide_refs->nr - 1; i >= 0; i--) {
1236                 const char *match = hide_refs->items[i].string;
1237                 const char *subject;
1238                 int neg = 0;
1239                 const char *p;
1240
1241                 if (*match == '!') {
1242                         neg = 1;
1243                         match++;
1244                 }
1245
1246                 if (*match == '^') {
1247                         subject = refname_full;
1248                         match++;
1249                 } else {
1250                         subject = refname;
1251                 }
1252
1253                 /* refname can be NULL when namespaces are used. */
1254                 if (subject &&
1255                     skip_prefix(subject, match, &p) &&
1256                     (!*p || *p == '/'))
1257                         return !neg;
1258         }
1259         return 0;
1260 }
1261
1262 const char *find_descendant_ref(const char *dirname,
1263                                 const struct string_list *extras,
1264                                 const struct string_list *skip)
1265 {
1266         int pos;
1267
1268         if (!extras)
1269                 return NULL;
1270
1271         /*
1272          * Look at the place where dirname would be inserted into
1273          * extras. If there is an entry at that position that starts
1274          * with dirname (remember, dirname includes the trailing
1275          * slash) and is not in skip, then we have a conflict.
1276          */
1277         for (pos = string_list_find_insert_index(extras, dirname, 0);
1278              pos < extras->nr; pos++) {
1279                 const char *extra_refname = extras->items[pos].string;
1280
1281                 if (!starts_with(extra_refname, dirname))
1282                         break;
1283
1284                 if (!skip || !string_list_has_string(skip, extra_refname))
1285                         return extra_refname;
1286         }
1287         return NULL;
1288 }
1289
1290 int refs_rename_ref_available(struct ref_store *refs,
1291                               const char *old_refname,
1292                               const char *new_refname)
1293 {
1294         struct string_list skip = STRING_LIST_INIT_NODUP;
1295         struct strbuf err = STRBUF_INIT;
1296         int ok;
1297
1298         string_list_insert(&skip, old_refname);
1299         ok = !refs_verify_refname_available(refs, new_refname,
1300                                             NULL, &skip, &err);
1301         if (!ok)
1302                 error("%s", err.buf);
1303
1304         string_list_clear(&skip, 0);
1305         strbuf_release(&err);
1306         return ok;
1307 }
1308
1309 int refs_head_ref(struct ref_store *refs, each_ref_fn fn, void *cb_data)
1310 {
1311         struct object_id oid;
1312         int flag;
1313
1314         if (!refs_read_ref_full(refs, "HEAD", RESOLVE_REF_READING,
1315                                 &oid, &flag))
1316                 return fn("HEAD", &oid, flag, cb_data);
1317
1318         return 0;
1319 }
1320
1321 int head_ref(each_ref_fn fn, void *cb_data)
1322 {
1323         return refs_head_ref(get_main_ref_store(), fn, cb_data);
1324 }
1325
1326 struct ref_iterator *refs_ref_iterator_begin(
1327                 struct ref_store *refs,
1328                 const char *prefix, int trim, int flags)
1329 {
1330         struct ref_iterator *iter;
1331
1332         if (ref_paranoia < 0)
1333                 ref_paranoia = git_env_bool("GIT_REF_PARANOIA", 0);
1334         if (ref_paranoia)
1335                 flags |= DO_FOR_EACH_INCLUDE_BROKEN;
1336
1337         iter = refs->be->iterator_begin(refs, prefix, flags);
1338
1339         /*
1340          * `iterator_begin()` already takes care of prefix, but we
1341          * might need to do some trimming:
1342          */
1343         if (trim)
1344                 iter = prefix_ref_iterator_begin(iter, "", trim);
1345
1346         /* Sanity check for subclasses: */
1347         if (!iter->ordered)
1348                 BUG("reference iterator is not ordered");
1349
1350         return iter;
1351 }
1352
1353 /*
1354  * Call fn for each reference in the specified submodule for which the
1355  * refname begins with prefix. If trim is non-zero, then trim that
1356  * many characters off the beginning of each refname before passing
1357  * the refname to fn. flags can be DO_FOR_EACH_INCLUDE_BROKEN to
1358  * include broken references in the iteration. If fn ever returns a
1359  * non-zero value, stop the iteration and return that value;
1360  * otherwise, return 0.
1361  */
1362 static int do_for_each_ref(struct ref_store *refs, const char *prefix,
1363                            each_ref_fn fn, int trim, int flags, void *cb_data)
1364 {
1365         struct ref_iterator *iter;
1366
1367         if (!refs)
1368                 return 0;
1369
1370         iter = refs_ref_iterator_begin(refs, prefix, trim, flags);
1371
1372         return do_for_each_ref_iterator(iter, fn, cb_data);
1373 }
1374
1375 int refs_for_each_ref(struct ref_store *refs, each_ref_fn fn, void *cb_data)
1376 {
1377         return do_for_each_ref(refs, "", fn, 0, 0, cb_data);
1378 }
1379
1380 int for_each_ref(each_ref_fn fn, void *cb_data)
1381 {
1382         return refs_for_each_ref(get_main_ref_store(), fn, cb_data);
1383 }
1384
1385 int refs_for_each_ref_in(struct ref_store *refs, const char *prefix,
1386                          each_ref_fn fn, void *cb_data)
1387 {
1388         return do_for_each_ref(refs, prefix, fn, strlen(prefix), 0, cb_data);
1389 }
1390
1391 int for_each_ref_in(const char *prefix, each_ref_fn fn, void *cb_data)
1392 {
1393         return refs_for_each_ref_in(get_main_ref_store(), prefix, fn, cb_data);
1394 }
1395
1396 int for_each_fullref_in(const char *prefix, each_ref_fn fn, void *cb_data, unsigned int broken)
1397 {
1398         unsigned int flag = 0;
1399
1400         if (broken)
1401                 flag = DO_FOR_EACH_INCLUDE_BROKEN;
1402         return do_for_each_ref(get_main_ref_store(),
1403                                prefix, fn, 0, flag, cb_data);
1404 }
1405
1406 int refs_for_each_fullref_in(struct ref_store *refs, const char *prefix,
1407                              each_ref_fn fn, void *cb_data,
1408                              unsigned int broken)
1409 {
1410         unsigned int flag = 0;
1411
1412         if (broken)
1413                 flag = DO_FOR_EACH_INCLUDE_BROKEN;
1414         return do_for_each_ref(refs, prefix, fn, 0, flag, cb_data);
1415 }
1416
1417 int for_each_replace_ref(each_ref_fn fn, void *cb_data)
1418 {
1419         return do_for_each_ref(get_main_ref_store(),
1420                                git_replace_ref_base, fn,
1421                                strlen(git_replace_ref_base),
1422                                DO_FOR_EACH_INCLUDE_BROKEN, cb_data);
1423 }
1424
1425 int for_each_namespaced_ref(each_ref_fn fn, void *cb_data)
1426 {
1427         struct strbuf buf = STRBUF_INIT;
1428         int ret;
1429         strbuf_addf(&buf, "%srefs/", get_git_namespace());
1430         ret = do_for_each_ref(get_main_ref_store(),
1431                               buf.buf, fn, 0, 0, cb_data);
1432         strbuf_release(&buf);
1433         return ret;
1434 }
1435
1436 int refs_for_each_rawref(struct ref_store *refs, each_ref_fn fn, void *cb_data)
1437 {
1438         return do_for_each_ref(refs, "", fn, 0,
1439                                DO_FOR_EACH_INCLUDE_BROKEN, cb_data);
1440 }
1441
1442 int for_each_rawref(each_ref_fn fn, void *cb_data)
1443 {
1444         return refs_for_each_rawref(get_main_ref_store(), fn, cb_data);
1445 }
1446
1447 int refs_read_raw_ref(struct ref_store *ref_store,
1448                       const char *refname, struct object_id *oid,
1449                       struct strbuf *referent, unsigned int *type)
1450 {
1451         return ref_store->be->read_raw_ref(ref_store, refname, oid, referent, type);
1452 }
1453
1454 /* This function needs to return a meaningful errno on failure */
1455 const char *refs_resolve_ref_unsafe(struct ref_store *refs,
1456                                     const char *refname,
1457                                     int resolve_flags,
1458                                     struct object_id *oid, int *flags)
1459 {
1460         static struct strbuf sb_refname = STRBUF_INIT;
1461         struct object_id unused_oid;
1462         int unused_flags;
1463         int symref_count;
1464
1465         if (!oid)
1466                 oid = &unused_oid;
1467         if (!flags)
1468                 flags = &unused_flags;
1469
1470         *flags = 0;
1471
1472         if (check_refname_format(refname, REFNAME_ALLOW_ONELEVEL)) {
1473                 if (!(resolve_flags & RESOLVE_REF_ALLOW_BAD_NAME) ||
1474                     !refname_is_safe(refname)) {
1475                         errno = EINVAL;
1476                         return NULL;
1477                 }
1478
1479                 /*
1480                  * dwim_ref() uses REF_ISBROKEN to distinguish between
1481                  * missing refs and refs that were present but invalid,
1482                  * to complain about the latter to stderr.
1483                  *
1484                  * We don't know whether the ref exists, so don't set
1485                  * REF_ISBROKEN yet.
1486                  */
1487                 *flags |= REF_BAD_NAME;
1488         }
1489
1490         for (symref_count = 0; symref_count < SYMREF_MAXDEPTH; symref_count++) {
1491                 unsigned int read_flags = 0;
1492
1493                 if (refs_read_raw_ref(refs, refname,
1494                                       oid, &sb_refname, &read_flags)) {
1495                         *flags |= read_flags;
1496
1497                         /* In reading mode, refs must eventually resolve */
1498                         if (resolve_flags & RESOLVE_REF_READING)
1499                                 return NULL;
1500
1501                         /*
1502                          * Otherwise a missing ref is OK. But the files backend
1503                          * may show errors besides ENOENT if there are
1504                          * similarly-named refs.
1505                          */
1506                         if (errno != ENOENT &&
1507                             errno != EISDIR &&
1508                             errno != ENOTDIR)
1509                                 return NULL;
1510
1511                         oidclr(oid);
1512                         if (*flags & REF_BAD_NAME)
1513                                 *flags |= REF_ISBROKEN;
1514                         return refname;
1515                 }
1516
1517                 *flags |= read_flags;
1518
1519                 if (!(read_flags & REF_ISSYMREF)) {
1520                         if (*flags & REF_BAD_NAME) {
1521                                 oidclr(oid);
1522                                 *flags |= REF_ISBROKEN;
1523                         }
1524                         return refname;
1525                 }
1526
1527                 refname = sb_refname.buf;
1528                 if (resolve_flags & RESOLVE_REF_NO_RECURSE) {
1529                         oidclr(oid);
1530                         return refname;
1531                 }
1532                 if (check_refname_format(refname, REFNAME_ALLOW_ONELEVEL)) {
1533                         if (!(resolve_flags & RESOLVE_REF_ALLOW_BAD_NAME) ||
1534                             !refname_is_safe(refname)) {
1535                                 errno = EINVAL;
1536                                 return NULL;
1537                         }
1538
1539                         *flags |= REF_ISBROKEN | REF_BAD_NAME;
1540                 }
1541         }
1542
1543         errno = ELOOP;
1544         return NULL;
1545 }
1546
1547 /* backend functions */
1548 int refs_init_db(struct strbuf *err)
1549 {
1550         struct ref_store *refs = get_main_ref_store();
1551
1552         return refs->be->init_db(refs, err);
1553 }
1554
1555 const char *resolve_ref_unsafe(const char *refname, int resolve_flags,
1556                                struct object_id *oid, int *flags)
1557 {
1558         return refs_resolve_ref_unsafe(get_main_ref_store(), refname,
1559                                        resolve_flags, oid, flags);
1560 }
1561
1562 int resolve_gitlink_ref(const char *submodule, const char *refname,
1563                         struct object_id *oid)
1564 {
1565         struct ref_store *refs;
1566         int flags;
1567
1568         refs = get_submodule_ref_store(submodule);
1569
1570         if (!refs)
1571                 return -1;
1572
1573         if (!refs_resolve_ref_unsafe(refs, refname, 0, oid, &flags) ||
1574             is_null_oid(oid))
1575                 return -1;
1576         return 0;
1577 }
1578
1579 struct ref_store_hash_entry
1580 {
1581         struct hashmap_entry ent; /* must be the first member! */
1582
1583         struct ref_store *refs;
1584
1585         /* NUL-terminated identifier of the ref store: */
1586         char name[FLEX_ARRAY];
1587 };
1588
1589 static int ref_store_hash_cmp(const void *unused_cmp_data,
1590                               const void *entry, const void *entry_or_key,
1591                               const void *keydata)
1592 {
1593         const struct ref_store_hash_entry *e1 = entry, *e2 = entry_or_key;
1594         const char *name = keydata ? keydata : e2->name;
1595
1596         return strcmp(e1->name, name);
1597 }
1598
1599 static struct ref_store_hash_entry *alloc_ref_store_hash_entry(
1600                 const char *name, struct ref_store *refs)
1601 {
1602         struct ref_store_hash_entry *entry;
1603
1604         FLEX_ALLOC_STR(entry, name, name);
1605         hashmap_entry_init(entry, strhash(name));
1606         entry->refs = refs;
1607         return entry;
1608 }
1609
1610 /* A pointer to the ref_store for the main repository: */
1611 static struct ref_store *main_ref_store;
1612
1613 /* A hashmap of ref_stores, stored by submodule name: */
1614 static struct hashmap submodule_ref_stores;
1615
1616 /* A hashmap of ref_stores, stored by worktree id: */
1617 static struct hashmap worktree_ref_stores;
1618
1619 /*
1620  * Look up a ref store by name. If that ref_store hasn't been
1621  * registered yet, return NULL.
1622  */
1623 static struct ref_store *lookup_ref_store_map(struct hashmap *map,
1624                                               const char *name)
1625 {
1626         struct ref_store_hash_entry *entry;
1627
1628         if (!map->tablesize)
1629                 /* It's initialized on demand in register_ref_store(). */
1630                 return NULL;
1631
1632         entry = hashmap_get_from_hash(map, strhash(name), name);
1633         return entry ? entry->refs : NULL;
1634 }
1635
1636 /*
1637  * Create, record, and return a ref_store instance for the specified
1638  * gitdir.
1639  */
1640 static struct ref_store *ref_store_init(const char *gitdir,
1641                                         unsigned int flags)
1642 {
1643         const char *be_name = "files";
1644         struct ref_storage_be *be = find_ref_storage_backend(be_name);
1645         struct ref_store *refs;
1646
1647         if (!be)
1648                 die("BUG: reference backend %s is unknown", be_name);
1649
1650         refs = be->init(gitdir, flags);
1651         return refs;
1652 }
1653
1654 struct ref_store *get_main_ref_store(void)
1655 {
1656         if (main_ref_store)
1657                 return main_ref_store;
1658
1659         main_ref_store = ref_store_init(get_git_dir(), REF_STORE_ALL_CAPS);
1660         return main_ref_store;
1661 }
1662
1663 /*
1664  * Associate a ref store with a name. It is a fatal error to call this
1665  * function twice for the same name.
1666  */
1667 static void register_ref_store_map(struct hashmap *map,
1668                                    const char *type,
1669                                    struct ref_store *refs,
1670                                    const char *name)
1671 {
1672         if (!map->tablesize)
1673                 hashmap_init(map, ref_store_hash_cmp, NULL, 0);
1674
1675         if (hashmap_put(map, alloc_ref_store_hash_entry(name, refs)))
1676                 die("BUG: %s ref_store '%s' initialized twice", type, name);
1677 }
1678
1679 struct ref_store *get_submodule_ref_store(const char *submodule)
1680 {
1681         struct strbuf submodule_sb = STRBUF_INIT;
1682         struct ref_store *refs;
1683         char *to_free = NULL;
1684         size_t len;
1685
1686         if (!submodule)
1687                 return NULL;
1688
1689         len = strlen(submodule);
1690         while (len && is_dir_sep(submodule[len - 1]))
1691                 len--;
1692         if (!len)
1693                 return NULL;
1694
1695         if (submodule[len])
1696                 /* We need to strip off one or more trailing slashes */
1697                 submodule = to_free = xmemdupz(submodule, len);
1698
1699         refs = lookup_ref_store_map(&submodule_ref_stores, submodule);
1700         if (refs)
1701                 goto done;
1702
1703         strbuf_addstr(&submodule_sb, submodule);
1704         if (!is_nonbare_repository_dir(&submodule_sb))
1705                 goto done;
1706
1707         if (submodule_to_gitdir(&submodule_sb, submodule))
1708                 goto done;
1709
1710         /* assume that add_submodule_odb() has been called */
1711         refs = ref_store_init(submodule_sb.buf,
1712                               REF_STORE_READ | REF_STORE_ODB);
1713         register_ref_store_map(&submodule_ref_stores, "submodule",
1714                                refs, submodule);
1715
1716 done:
1717         strbuf_release(&submodule_sb);
1718         free(to_free);
1719
1720         return refs;
1721 }
1722
1723 struct ref_store *get_worktree_ref_store(const struct worktree *wt)
1724 {
1725         struct ref_store *refs;
1726         const char *id;
1727
1728         if (wt->is_current)
1729                 return get_main_ref_store();
1730
1731         id = wt->id ? wt->id : "/";
1732         refs = lookup_ref_store_map(&worktree_ref_stores, id);
1733         if (refs)
1734                 return refs;
1735
1736         if (wt->id)
1737                 refs = ref_store_init(git_common_path("worktrees/%s", wt->id),
1738                                       REF_STORE_ALL_CAPS);
1739         else
1740                 refs = ref_store_init(get_git_common_dir(),
1741                                       REF_STORE_ALL_CAPS);
1742
1743         if (refs)
1744                 register_ref_store_map(&worktree_ref_stores, "worktree",
1745                                        refs, id);
1746         return refs;
1747 }
1748
1749 void base_ref_store_init(struct ref_store *refs,
1750                          const struct ref_storage_be *be)
1751 {
1752         refs->be = be;
1753 }
1754
1755 /* backend functions */
1756 int refs_pack_refs(struct ref_store *refs, unsigned int flags)
1757 {
1758         return refs->be->pack_refs(refs, flags);
1759 }
1760
1761 int refs_peel_ref(struct ref_store *refs, const char *refname,
1762                   struct object_id *oid)
1763 {
1764         int flag;
1765         struct object_id base;
1766
1767         if (current_ref_iter && current_ref_iter->refname == refname) {
1768                 struct object_id peeled;
1769
1770                 if (ref_iterator_peel(current_ref_iter, &peeled))
1771                         return -1;
1772                 oidcpy(oid, &peeled);
1773                 return 0;
1774         }
1775
1776         if (refs_read_ref_full(refs, refname,
1777                                RESOLVE_REF_READING, &base, &flag))
1778                 return -1;
1779
1780         return peel_object(&base, oid);
1781 }
1782
1783 int peel_ref(const char *refname, struct object_id *oid)
1784 {
1785         return refs_peel_ref(get_main_ref_store(), refname, oid);
1786 }
1787
1788 int refs_create_symref(struct ref_store *refs,
1789                        const char *ref_target,
1790                        const char *refs_heads_master,
1791                        const char *logmsg)
1792 {
1793         return refs->be->create_symref(refs, ref_target,
1794                                        refs_heads_master,
1795                                        logmsg);
1796 }
1797
1798 int create_symref(const char *ref_target, const char *refs_heads_master,
1799                   const char *logmsg)
1800 {
1801         return refs_create_symref(get_main_ref_store(), ref_target,
1802                                   refs_heads_master, logmsg);
1803 }
1804
1805 int ref_update_reject_duplicates(struct string_list *refnames,
1806                                  struct strbuf *err)
1807 {
1808         size_t i, n = refnames->nr;
1809
1810         assert(err);
1811
1812         for (i = 1; i < n; i++) {
1813                 int cmp = strcmp(refnames->items[i - 1].string,
1814                                  refnames->items[i].string);
1815
1816                 if (!cmp) {
1817                         strbuf_addf(err,
1818                                     "multiple updates for ref '%s' not allowed.",
1819                                     refnames->items[i].string);
1820                         return 1;
1821                 } else if (cmp > 0) {
1822                         die("BUG: ref_update_reject_duplicates() received unsorted list");
1823                 }
1824         }
1825         return 0;
1826 }
1827
1828 int ref_transaction_prepare(struct ref_transaction *transaction,
1829                             struct strbuf *err)
1830 {
1831         struct ref_store *refs = transaction->ref_store;
1832
1833         switch (transaction->state) {
1834         case REF_TRANSACTION_OPEN:
1835                 /* Good. */
1836                 break;
1837         case REF_TRANSACTION_PREPARED:
1838                 die("BUG: prepare called twice on reference transaction");
1839                 break;
1840         case REF_TRANSACTION_CLOSED:
1841                 die("BUG: prepare called on a closed reference transaction");
1842                 break;
1843         default:
1844                 die("BUG: unexpected reference transaction state");
1845                 break;
1846         }
1847
1848         if (getenv(GIT_QUARANTINE_ENVIRONMENT)) {
1849                 strbuf_addstr(err,
1850                               _("ref updates forbidden inside quarantine environment"));
1851                 return -1;
1852         }
1853
1854         return refs->be->transaction_prepare(refs, transaction, err);
1855 }
1856
1857 int ref_transaction_abort(struct ref_transaction *transaction,
1858                           struct strbuf *err)
1859 {
1860         struct ref_store *refs = transaction->ref_store;
1861         int ret = 0;
1862
1863         switch (transaction->state) {
1864         case REF_TRANSACTION_OPEN:
1865                 /* No need to abort explicitly. */
1866                 break;
1867         case REF_TRANSACTION_PREPARED:
1868                 ret = refs->be->transaction_abort(refs, transaction, err);
1869                 break;
1870         case REF_TRANSACTION_CLOSED:
1871                 die("BUG: abort called on a closed reference transaction");
1872                 break;
1873         default:
1874                 die("BUG: unexpected reference transaction state");
1875                 break;
1876         }
1877
1878         ref_transaction_free(transaction);
1879         return ret;
1880 }
1881
1882 int ref_transaction_commit(struct ref_transaction *transaction,
1883                            struct strbuf *err)
1884 {
1885         struct ref_store *refs = transaction->ref_store;
1886         int ret;
1887
1888         switch (transaction->state) {
1889         case REF_TRANSACTION_OPEN:
1890                 /* Need to prepare first. */
1891                 ret = ref_transaction_prepare(transaction, err);
1892                 if (ret)
1893                         return ret;
1894                 break;
1895         case REF_TRANSACTION_PREPARED:
1896                 /* Fall through to finish. */
1897                 break;
1898         case REF_TRANSACTION_CLOSED:
1899                 die("BUG: commit called on a closed reference transaction");
1900                 break;
1901         default:
1902                 die("BUG: unexpected reference transaction state");
1903                 break;
1904         }
1905
1906         return refs->be->transaction_finish(refs, transaction, err);
1907 }
1908
1909 int refs_verify_refname_available(struct ref_store *refs,
1910                                   const char *refname,
1911                                   const struct string_list *extras,
1912                                   const struct string_list *skip,
1913                                   struct strbuf *err)
1914 {
1915         const char *slash;
1916         const char *extra_refname;
1917         struct strbuf dirname = STRBUF_INIT;
1918         struct strbuf referent = STRBUF_INIT;
1919         struct object_id oid;
1920         unsigned int type;
1921         struct ref_iterator *iter;
1922         int ok;
1923         int ret = -1;
1924
1925         /*
1926          * For the sake of comments in this function, suppose that
1927          * refname is "refs/foo/bar".
1928          */
1929
1930         assert(err);
1931
1932         strbuf_grow(&dirname, strlen(refname) + 1);
1933         for (slash = strchr(refname, '/'); slash; slash = strchr(slash + 1, '/')) {
1934                 /* Expand dirname to the new prefix, not including the trailing slash: */
1935                 strbuf_add(&dirname, refname + dirname.len, slash - refname - dirname.len);
1936
1937                 /*
1938                  * We are still at a leading dir of the refname (e.g.,
1939                  * "refs/foo"; if there is a reference with that name,
1940                  * it is a conflict, *unless* it is in skip.
1941                  */
1942                 if (skip && string_list_has_string(skip, dirname.buf))
1943                         continue;
1944
1945                 if (!refs_read_raw_ref(refs, dirname.buf, &oid, &referent, &type)) {
1946                         strbuf_addf(err, "'%s' exists; cannot create '%s'",
1947                                     dirname.buf, refname);
1948                         goto cleanup;
1949                 }
1950
1951                 if (extras && string_list_has_string(extras, dirname.buf)) {
1952                         strbuf_addf(err, "cannot process '%s' and '%s' at the same time",
1953                                     refname, dirname.buf);
1954                         goto cleanup;
1955                 }
1956         }
1957
1958         /*
1959          * We are at the leaf of our refname (e.g., "refs/foo/bar").
1960          * There is no point in searching for a reference with that
1961          * name, because a refname isn't considered to conflict with
1962          * itself. But we still need to check for references whose
1963          * names are in the "refs/foo/bar/" namespace, because they
1964          * *do* conflict.
1965          */
1966         strbuf_addstr(&dirname, refname + dirname.len);
1967         strbuf_addch(&dirname, '/');
1968
1969         iter = refs_ref_iterator_begin(refs, dirname.buf, 0,
1970                                        DO_FOR_EACH_INCLUDE_BROKEN);
1971         while ((ok = ref_iterator_advance(iter)) == ITER_OK) {
1972                 if (skip &&
1973                     string_list_has_string(skip, iter->refname))
1974                         continue;
1975
1976                 strbuf_addf(err, "'%s' exists; cannot create '%s'",
1977                             iter->refname, refname);
1978                 ref_iterator_abort(iter);
1979                 goto cleanup;
1980         }
1981
1982         if (ok != ITER_DONE)
1983                 die("BUG: error while iterating over references");
1984
1985         extra_refname = find_descendant_ref(dirname.buf, extras, skip);
1986         if (extra_refname)
1987                 strbuf_addf(err, "cannot process '%s' and '%s' at the same time",
1988                             refname, extra_refname);
1989         else
1990                 ret = 0;
1991
1992 cleanup:
1993         strbuf_release(&referent);
1994         strbuf_release(&dirname);
1995         return ret;
1996 }
1997
1998 int refs_for_each_reflog(struct ref_store *refs, each_ref_fn fn, void *cb_data)
1999 {
2000         struct ref_iterator *iter;
2001
2002         iter = refs->be->reflog_iterator_begin(refs);
2003
2004         return do_for_each_ref_iterator(iter, fn, cb_data);
2005 }
2006
2007 int for_each_reflog(each_ref_fn fn, void *cb_data)
2008 {
2009         return refs_for_each_reflog(get_main_ref_store(), fn, cb_data);
2010 }
2011
2012 int refs_for_each_reflog_ent_reverse(struct ref_store *refs,
2013                                      const char *refname,
2014                                      each_reflog_ent_fn fn,
2015                                      void *cb_data)
2016 {
2017         return refs->be->for_each_reflog_ent_reverse(refs, refname,
2018                                                      fn, cb_data);
2019 }
2020
2021 int for_each_reflog_ent_reverse(const char *refname, each_reflog_ent_fn fn,
2022                                 void *cb_data)
2023 {
2024         return refs_for_each_reflog_ent_reverse(get_main_ref_store(),
2025                                                 refname, fn, cb_data);
2026 }
2027
2028 int refs_for_each_reflog_ent(struct ref_store *refs, const char *refname,
2029                              each_reflog_ent_fn fn, void *cb_data)
2030 {
2031         return refs->be->for_each_reflog_ent(refs, refname, fn, cb_data);
2032 }
2033
2034 int for_each_reflog_ent(const char *refname, each_reflog_ent_fn fn,
2035                         void *cb_data)
2036 {
2037         return refs_for_each_reflog_ent(get_main_ref_store(), refname,
2038                                         fn, cb_data);
2039 }
2040
2041 int refs_reflog_exists(struct ref_store *refs, const char *refname)
2042 {
2043         return refs->be->reflog_exists(refs, refname);
2044 }
2045
2046 int reflog_exists(const char *refname)
2047 {
2048         return refs_reflog_exists(get_main_ref_store(), refname);
2049 }
2050
2051 int refs_create_reflog(struct ref_store *refs, const char *refname,
2052                        int force_create, struct strbuf *err)
2053 {
2054         return refs->be->create_reflog(refs, refname, force_create, err);
2055 }
2056
2057 int safe_create_reflog(const char *refname, int force_create,
2058                        struct strbuf *err)
2059 {
2060         return refs_create_reflog(get_main_ref_store(), refname,
2061                                   force_create, err);
2062 }
2063
2064 int refs_delete_reflog(struct ref_store *refs, const char *refname)
2065 {
2066         return refs->be->delete_reflog(refs, refname);
2067 }
2068
2069 int delete_reflog(const char *refname)
2070 {
2071         return refs_delete_reflog(get_main_ref_store(), refname);
2072 }
2073
2074 int refs_reflog_expire(struct ref_store *refs,
2075                        const char *refname, const struct object_id *oid,
2076                        unsigned int flags,
2077                        reflog_expiry_prepare_fn prepare_fn,
2078                        reflog_expiry_should_prune_fn should_prune_fn,
2079                        reflog_expiry_cleanup_fn cleanup_fn,
2080                        void *policy_cb_data)
2081 {
2082         return refs->be->reflog_expire(refs, refname, oid, flags,
2083                                        prepare_fn, should_prune_fn,
2084                                        cleanup_fn, policy_cb_data);
2085 }
2086
2087 int reflog_expire(const char *refname, const struct object_id *oid,
2088                   unsigned int flags,
2089                   reflog_expiry_prepare_fn prepare_fn,
2090                   reflog_expiry_should_prune_fn should_prune_fn,
2091                   reflog_expiry_cleanup_fn cleanup_fn,
2092                   void *policy_cb_data)
2093 {
2094         return refs_reflog_expire(get_main_ref_store(),
2095                                   refname, oid, flags,
2096                                   prepare_fn, should_prune_fn,
2097                                   cleanup_fn, policy_cb_data);
2098 }
2099
2100 int initial_ref_transaction_commit(struct ref_transaction *transaction,
2101                                    struct strbuf *err)
2102 {
2103         struct ref_store *refs = transaction->ref_store;
2104
2105         return refs->be->initial_transaction_commit(refs, transaction, err);
2106 }
2107
2108 int refs_delete_refs(struct ref_store *refs, const char *msg,
2109                      struct string_list *refnames, unsigned int flags)
2110 {
2111         return refs->be->delete_refs(refs, msg, refnames, flags);
2112 }
2113
2114 int delete_refs(const char *msg, struct string_list *refnames,
2115                 unsigned int flags)
2116 {
2117         return refs_delete_refs(get_main_ref_store(), msg, refnames, flags);
2118 }
2119
2120 int refs_rename_ref(struct ref_store *refs, const char *oldref,
2121                     const char *newref, const char *logmsg)
2122 {
2123         return refs->be->rename_ref(refs, oldref, newref, logmsg);
2124 }
2125
2126 int rename_ref(const char *oldref, const char *newref, const char *logmsg)
2127 {
2128         return refs_rename_ref(get_main_ref_store(), oldref, newref, logmsg);
2129 }
2130
2131 int refs_copy_existing_ref(struct ref_store *refs, const char *oldref,
2132                     const char *newref, const char *logmsg)
2133 {
2134         return refs->be->copy_ref(refs, oldref, newref, logmsg);
2135 }
2136
2137 int copy_existing_ref(const char *oldref, const char *newref, const char *logmsg)
2138 {
2139         return refs_copy_existing_ref(get_main_ref_store(), oldref, newref, logmsg);
2140 }