Merge branch 'jc/forbid-symbolic-ref-d-HEAD' into maint
[git] / refs.c
1 /*
2  * The backend-independent part of the reference module.
3  */
4
5 #include "cache.h"
6 #include "lockfile.h"
7 #include "refs.h"
8 #include "refs/refs-internal.h"
9 #include "object.h"
10 #include "tag.h"
11
12 /*
13  * How to handle various characters in refnames:
14  * 0: An acceptable character for refs
15  * 1: End-of-component
16  * 2: ., look for a preceding . to reject .. in refs
17  * 3: {, look for a preceding @ to reject @{ in refs
18  * 4: A bad character: ASCII control characters, and
19  *    ":", "?", "[", "\", "^", "~", SP, or TAB
20  * 5: *, reject unless REFNAME_REFSPEC_PATTERN is set
21  */
22 static unsigned char refname_disposition[256] = {
23         1, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
24         4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
25         4, 0, 0, 0, 0, 0, 0, 0, 0, 0, 5, 0, 0, 0, 2, 1,
26         0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 4, 0, 0, 0, 0, 4,
27         0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
28         0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 4, 4, 0, 4, 0,
29         0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
30         0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 3, 0, 0, 4, 4
31 };
32
33 /*
34  * Try to read one refname component from the front of refname.
35  * Return the length of the component found, or -1 if the component is
36  * not legal.  It is legal if it is something reasonable to have under
37  * ".git/refs/"; We do not like it if:
38  *
39  * - any path component of it begins with ".", or
40  * - it has double dots "..", or
41  * - it has ASCII control characters, or
42  * - it has ":", "?", "[", "\", "^", "~", SP, or TAB anywhere, or
43  * - it has "*" anywhere unless REFNAME_REFSPEC_PATTERN is set, or
44  * - it ends with a "/", or
45  * - it ends with ".lock", or
46  * - it contains a "@{" portion
47  */
48 static int check_refname_component(const char *refname, int *flags)
49 {
50         const char *cp;
51         char last = '\0';
52
53         for (cp = refname; ; cp++) {
54                 int ch = *cp & 255;
55                 unsigned char disp = refname_disposition[ch];
56                 switch (disp) {
57                 case 1:
58                         goto out;
59                 case 2:
60                         if (last == '.')
61                                 return -1; /* Refname contains "..". */
62                         break;
63                 case 3:
64                         if (last == '@')
65                                 return -1; /* Refname contains "@{". */
66                         break;
67                 case 4:
68                         return -1;
69                 case 5:
70                         if (!(*flags & REFNAME_REFSPEC_PATTERN))
71                                 return -1; /* refspec can't be a pattern */
72
73                         /*
74                          * Unset the pattern flag so that we only accept
75                          * a single asterisk for one side of refspec.
76                          */
77                         *flags &= ~ REFNAME_REFSPEC_PATTERN;
78                         break;
79                 }
80                 last = ch;
81         }
82 out:
83         if (cp == refname)
84                 return 0; /* Component has zero length. */
85         if (refname[0] == '.')
86                 return -1; /* Component starts with '.'. */
87         if (cp - refname >= LOCK_SUFFIX_LEN &&
88             !memcmp(cp - LOCK_SUFFIX_LEN, LOCK_SUFFIX, LOCK_SUFFIX_LEN))
89                 return -1; /* Refname ends with ".lock". */
90         return cp - refname;
91 }
92
93 int check_refname_format(const char *refname, int flags)
94 {
95         int component_len, component_count = 0;
96
97         if (!strcmp(refname, "@"))
98                 /* Refname is a single character '@'. */
99                 return -1;
100
101         while (1) {
102                 /* We are at the start of a path component. */
103                 component_len = check_refname_component(refname, &flags);
104                 if (component_len <= 0)
105                         return -1;
106
107                 component_count++;
108                 if (refname[component_len] == '\0')
109                         break;
110                 /* Skip to next component. */
111                 refname += component_len + 1;
112         }
113
114         if (refname[component_len - 1] == '.')
115                 return -1; /* Refname ends with '.'. */
116         if (!(flags & REFNAME_ALLOW_ONELEVEL) && component_count < 2)
117                 return -1; /* Refname has only one component. */
118         return 0;
119 }
120
121 int refname_is_safe(const char *refname)
122 {
123         const char *rest;
124
125         if (skip_prefix(refname, "refs/", &rest)) {
126                 char *buf;
127                 int result;
128                 size_t restlen = strlen(rest);
129
130                 /* rest must not be empty, or start or end with "/" */
131                 if (!restlen || *rest == '/' || rest[restlen - 1] == '/')
132                         return 0;
133
134                 /*
135                  * Does the refname try to escape refs/?
136                  * For example: refs/foo/../bar is safe but refs/foo/../../bar
137                  * is not.
138                  */
139                 buf = xmallocz(restlen);
140                 result = !normalize_path_copy(buf, rest) && !strcmp(buf, rest);
141                 free(buf);
142                 return result;
143         }
144
145         do {
146                 if (!isupper(*refname) && *refname != '_')
147                         return 0;
148                 refname++;
149         } while (*refname);
150         return 1;
151 }
152
153 char *resolve_refdup(const char *refname, int resolve_flags,
154                      unsigned char *sha1, int *flags)
155 {
156         return xstrdup_or_null(resolve_ref_unsafe(refname, resolve_flags,
157                                                   sha1, flags));
158 }
159
160 /* The argument to filter_refs */
161 struct ref_filter {
162         const char *pattern;
163         each_ref_fn *fn;
164         void *cb_data;
165 };
166
167 int read_ref_full(const char *refname, int resolve_flags, unsigned char *sha1, int *flags)
168 {
169         if (resolve_ref_unsafe(refname, resolve_flags, sha1, flags))
170                 return 0;
171         return -1;
172 }
173
174 int read_ref(const char *refname, unsigned char *sha1)
175 {
176         return read_ref_full(refname, RESOLVE_REF_READING, sha1, NULL);
177 }
178
179 int ref_exists(const char *refname)
180 {
181         unsigned char sha1[20];
182         return !!resolve_ref_unsafe(refname, RESOLVE_REF_READING, sha1, NULL);
183 }
184
185 static int filter_refs(const char *refname, const struct object_id *oid,
186                            int flags, void *data)
187 {
188         struct ref_filter *filter = (struct ref_filter *)data;
189
190         if (wildmatch(filter->pattern, refname, 0, NULL))
191                 return 0;
192         return filter->fn(refname, oid, flags, filter->cb_data);
193 }
194
195 enum peel_status peel_object(const unsigned char *name, unsigned char *sha1)
196 {
197         struct object *o = lookup_unknown_object(name);
198
199         if (o->type == OBJ_NONE) {
200                 int type = sha1_object_info(name, NULL);
201                 if (type < 0 || !object_as_type(o, type, 0))
202                         return PEEL_INVALID;
203         }
204
205         if (o->type != OBJ_TAG)
206                 return PEEL_NON_TAG;
207
208         o = deref_tag_noverify(o);
209         if (!o)
210                 return PEEL_INVALID;
211
212         hashcpy(sha1, o->oid.hash);
213         return PEEL_PEELED;
214 }
215
216 struct warn_if_dangling_data {
217         FILE *fp;
218         const char *refname;
219         const struct string_list *refnames;
220         const char *msg_fmt;
221 };
222
223 static int warn_if_dangling_symref(const char *refname, const struct object_id *oid,
224                                    int flags, void *cb_data)
225 {
226         struct warn_if_dangling_data *d = cb_data;
227         const char *resolves_to;
228         struct object_id junk;
229
230         if (!(flags & REF_ISSYMREF))
231                 return 0;
232
233         resolves_to = resolve_ref_unsafe(refname, 0, junk.hash, NULL);
234         if (!resolves_to
235             || (d->refname
236                 ? strcmp(resolves_to, d->refname)
237                 : !string_list_has_string(d->refnames, resolves_to))) {
238                 return 0;
239         }
240
241         fprintf(d->fp, d->msg_fmt, refname);
242         fputc('\n', d->fp);
243         return 0;
244 }
245
246 void warn_dangling_symref(FILE *fp, const char *msg_fmt, const char *refname)
247 {
248         struct warn_if_dangling_data data;
249
250         data.fp = fp;
251         data.refname = refname;
252         data.refnames = NULL;
253         data.msg_fmt = msg_fmt;
254         for_each_rawref(warn_if_dangling_symref, &data);
255 }
256
257 void warn_dangling_symrefs(FILE *fp, const char *msg_fmt, const struct string_list *refnames)
258 {
259         struct warn_if_dangling_data data;
260
261         data.fp = fp;
262         data.refname = NULL;
263         data.refnames = refnames;
264         data.msg_fmt = msg_fmt;
265         for_each_rawref(warn_if_dangling_symref, &data);
266 }
267
268 int for_each_tag_ref(each_ref_fn fn, void *cb_data)
269 {
270         return for_each_ref_in("refs/tags/", fn, cb_data);
271 }
272
273 int for_each_tag_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
274 {
275         return for_each_ref_in_submodule(submodule, "refs/tags/", fn, cb_data);
276 }
277
278 int for_each_branch_ref(each_ref_fn fn, void *cb_data)
279 {
280         return for_each_ref_in("refs/heads/", fn, cb_data);
281 }
282
283 int for_each_branch_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
284 {
285         return for_each_ref_in_submodule(submodule, "refs/heads/", fn, cb_data);
286 }
287
288 int for_each_remote_ref(each_ref_fn fn, void *cb_data)
289 {
290         return for_each_ref_in("refs/remotes/", fn, cb_data);
291 }
292
293 int for_each_remote_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
294 {
295         return for_each_ref_in_submodule(submodule, "refs/remotes/", fn, cb_data);
296 }
297
298 int head_ref_namespaced(each_ref_fn fn, void *cb_data)
299 {
300         struct strbuf buf = STRBUF_INIT;
301         int ret = 0;
302         struct object_id oid;
303         int flag;
304
305         strbuf_addf(&buf, "%sHEAD", get_git_namespace());
306         if (!read_ref_full(buf.buf, RESOLVE_REF_READING, oid.hash, &flag))
307                 ret = fn(buf.buf, &oid, flag, cb_data);
308         strbuf_release(&buf);
309
310         return ret;
311 }
312
313 int for_each_glob_ref_in(each_ref_fn fn, const char *pattern,
314         const char *prefix, void *cb_data)
315 {
316         struct strbuf real_pattern = STRBUF_INIT;
317         struct ref_filter filter;
318         int ret;
319
320         if (!prefix && !starts_with(pattern, "refs/"))
321                 strbuf_addstr(&real_pattern, "refs/");
322         else if (prefix)
323                 strbuf_addstr(&real_pattern, prefix);
324         strbuf_addstr(&real_pattern, pattern);
325
326         if (!has_glob_specials(pattern)) {
327                 /* Append implied '/' '*' if not present. */
328                 strbuf_complete(&real_pattern, '/');
329                 /* No need to check for '*', there is none. */
330                 strbuf_addch(&real_pattern, '*');
331         }
332
333         filter.pattern = real_pattern.buf;
334         filter.fn = fn;
335         filter.cb_data = cb_data;
336         ret = for_each_ref(filter_refs, &filter);
337
338         strbuf_release(&real_pattern);
339         return ret;
340 }
341
342 int for_each_glob_ref(each_ref_fn fn, const char *pattern, void *cb_data)
343 {
344         return for_each_glob_ref_in(fn, pattern, NULL, cb_data);
345 }
346
347 const char *prettify_refname(const char *name)
348 {
349         return name + (
350                 starts_with(name, "refs/heads/") ? 11 :
351                 starts_with(name, "refs/tags/") ? 10 :
352                 starts_with(name, "refs/remotes/") ? 13 :
353                 0);
354 }
355
356 static const char *ref_rev_parse_rules[] = {
357         "%.*s",
358         "refs/%.*s",
359         "refs/tags/%.*s",
360         "refs/heads/%.*s",
361         "refs/remotes/%.*s",
362         "refs/remotes/%.*s/HEAD",
363         NULL
364 };
365
366 int refname_match(const char *abbrev_name, const char *full_name)
367 {
368         const char **p;
369         const int abbrev_name_len = strlen(abbrev_name);
370
371         for (p = ref_rev_parse_rules; *p; p++) {
372                 if (!strcmp(full_name, mkpath(*p, abbrev_name_len, abbrev_name))) {
373                         return 1;
374                 }
375         }
376
377         return 0;
378 }
379
380 /*
381  * *string and *len will only be substituted, and *string returned (for
382  * later free()ing) if the string passed in is a magic short-hand form
383  * to name a branch.
384  */
385 static char *substitute_branch_name(const char **string, int *len)
386 {
387         struct strbuf buf = STRBUF_INIT;
388         int ret = interpret_branch_name(*string, *len, &buf);
389
390         if (ret == *len) {
391                 size_t size;
392                 *string = strbuf_detach(&buf, &size);
393                 *len = size;
394                 return (char *)*string;
395         }
396
397         return NULL;
398 }
399
400 int dwim_ref(const char *str, int len, unsigned char *sha1, char **ref)
401 {
402         char *last_branch = substitute_branch_name(&str, &len);
403         const char **p, *r;
404         int refs_found = 0;
405
406         *ref = NULL;
407         for (p = ref_rev_parse_rules; *p; p++) {
408                 char fullref[PATH_MAX];
409                 unsigned char sha1_from_ref[20];
410                 unsigned char *this_result;
411                 int flag;
412
413                 this_result = refs_found ? sha1_from_ref : sha1;
414                 mksnpath(fullref, sizeof(fullref), *p, len, str);
415                 r = resolve_ref_unsafe(fullref, RESOLVE_REF_READING,
416                                        this_result, &flag);
417                 if (r) {
418                         if (!refs_found++)
419                                 *ref = xstrdup(r);
420                         if (!warn_ambiguous_refs)
421                                 break;
422                 } else if ((flag & REF_ISSYMREF) && strcmp(fullref, "HEAD")) {
423                         warning("ignoring dangling symref %s.", fullref);
424                 } else if ((flag & REF_ISBROKEN) && strchr(fullref, '/')) {
425                         warning("ignoring broken ref %s.", fullref);
426                 }
427         }
428         free(last_branch);
429         return refs_found;
430 }
431
432 int dwim_log(const char *str, int len, unsigned char *sha1, char **log)
433 {
434         char *last_branch = substitute_branch_name(&str, &len);
435         const char **p;
436         int logs_found = 0;
437
438         *log = NULL;
439         for (p = ref_rev_parse_rules; *p; p++) {
440                 unsigned char hash[20];
441                 char path[PATH_MAX];
442                 const char *ref, *it;
443
444                 mksnpath(path, sizeof(path), *p, len, str);
445                 ref = resolve_ref_unsafe(path, RESOLVE_REF_READING,
446                                          hash, NULL);
447                 if (!ref)
448                         continue;
449                 if (reflog_exists(path))
450                         it = path;
451                 else if (strcmp(ref, path) && reflog_exists(ref))
452                         it = ref;
453                 else
454                         continue;
455                 if (!logs_found++) {
456                         *log = xstrdup(it);
457                         hashcpy(sha1, hash);
458                 }
459                 if (!warn_ambiguous_refs)
460                         break;
461         }
462         free(last_branch);
463         return logs_found;
464 }
465
466 static int is_per_worktree_ref(const char *refname)
467 {
468         return !strcmp(refname, "HEAD") ||
469                 starts_with(refname, "refs/bisect/");
470 }
471
472 static int is_pseudoref_syntax(const char *refname)
473 {
474         const char *c;
475
476         for (c = refname; *c; c++) {
477                 if (!isupper(*c) && *c != '-' && *c != '_')
478                         return 0;
479         }
480
481         return 1;
482 }
483
484 enum ref_type ref_type(const char *refname)
485 {
486         if (is_per_worktree_ref(refname))
487                 return REF_TYPE_PER_WORKTREE;
488         if (is_pseudoref_syntax(refname))
489                 return REF_TYPE_PSEUDOREF;
490        return REF_TYPE_NORMAL;
491 }
492
493 static int write_pseudoref(const char *pseudoref, const unsigned char *sha1,
494                            const unsigned char *old_sha1, struct strbuf *err)
495 {
496         const char *filename;
497         int fd;
498         static struct lock_file lock;
499         struct strbuf buf = STRBUF_INIT;
500         int ret = -1;
501
502         strbuf_addf(&buf, "%s\n", sha1_to_hex(sha1));
503
504         filename = git_path("%s", pseudoref);
505         fd = hold_lock_file_for_update(&lock, filename, LOCK_DIE_ON_ERROR);
506         if (fd < 0) {
507                 strbuf_addf(err, "could not open '%s' for writing: %s",
508                             filename, strerror(errno));
509                 return -1;
510         }
511
512         if (old_sha1) {
513                 unsigned char actual_old_sha1[20];
514
515                 if (read_ref(pseudoref, actual_old_sha1))
516                         die("could not read ref '%s'", pseudoref);
517                 if (hashcmp(actual_old_sha1, old_sha1)) {
518                         strbuf_addf(err, "unexpected sha1 when writing '%s'", pseudoref);
519                         rollback_lock_file(&lock);
520                         goto done;
521                 }
522         }
523
524         if (write_in_full(fd, buf.buf, buf.len) != buf.len) {
525                 strbuf_addf(err, "could not write to '%s'", filename);
526                 rollback_lock_file(&lock);
527                 goto done;
528         }
529
530         commit_lock_file(&lock);
531         ret = 0;
532 done:
533         strbuf_release(&buf);
534         return ret;
535 }
536
537 static int delete_pseudoref(const char *pseudoref, const unsigned char *old_sha1)
538 {
539         static struct lock_file lock;
540         const char *filename;
541
542         filename = git_path("%s", pseudoref);
543
544         if (old_sha1 && !is_null_sha1(old_sha1)) {
545                 int fd;
546                 unsigned char actual_old_sha1[20];
547
548                 fd = hold_lock_file_for_update(&lock, filename,
549                                                LOCK_DIE_ON_ERROR);
550                 if (fd < 0)
551                         die_errno(_("Could not open '%s' for writing"), filename);
552                 if (read_ref(pseudoref, actual_old_sha1))
553                         die("could not read ref '%s'", pseudoref);
554                 if (hashcmp(actual_old_sha1, old_sha1)) {
555                         warning("Unexpected sha1 when deleting %s", pseudoref);
556                         rollback_lock_file(&lock);
557                         return -1;
558                 }
559
560                 unlink(filename);
561                 rollback_lock_file(&lock);
562         } else {
563                 unlink(filename);
564         }
565
566         return 0;
567 }
568
569 int delete_ref(const char *refname, const unsigned char *old_sha1,
570                unsigned int flags)
571 {
572         struct ref_transaction *transaction;
573         struct strbuf err = STRBUF_INIT;
574
575         if (ref_type(refname) == REF_TYPE_PSEUDOREF)
576                 return delete_pseudoref(refname, old_sha1);
577
578         transaction = ref_transaction_begin(&err);
579         if (!transaction ||
580             ref_transaction_delete(transaction, refname, old_sha1,
581                                    flags, NULL, &err) ||
582             ref_transaction_commit(transaction, &err)) {
583                 error("%s", err.buf);
584                 ref_transaction_free(transaction);
585                 strbuf_release(&err);
586                 return 1;
587         }
588         ref_transaction_free(transaction);
589         strbuf_release(&err);
590         return 0;
591 }
592
593 int copy_reflog_msg(char *buf, const char *msg)
594 {
595         char *cp = buf;
596         char c;
597         int wasspace = 1;
598
599         *cp++ = '\t';
600         while ((c = *msg++)) {
601                 if (wasspace && isspace(c))
602                         continue;
603                 wasspace = isspace(c);
604                 if (wasspace)
605                         c = ' ';
606                 *cp++ = c;
607         }
608         while (buf < cp && isspace(cp[-1]))
609                 cp--;
610         *cp++ = '\n';
611         return cp - buf;
612 }
613
614 int should_autocreate_reflog(const char *refname)
615 {
616         if (!log_all_ref_updates)
617                 return 0;
618         return starts_with(refname, "refs/heads/") ||
619                 starts_with(refname, "refs/remotes/") ||
620                 starts_with(refname, "refs/notes/") ||
621                 !strcmp(refname, "HEAD");
622 }
623
624 int is_branch(const char *refname)
625 {
626         return !strcmp(refname, "HEAD") || starts_with(refname, "refs/heads/");
627 }
628
629 struct read_ref_at_cb {
630         const char *refname;
631         unsigned long at_time;
632         int cnt;
633         int reccnt;
634         unsigned char *sha1;
635         int found_it;
636
637         unsigned char osha1[20];
638         unsigned char nsha1[20];
639         int tz;
640         unsigned long date;
641         char **msg;
642         unsigned long *cutoff_time;
643         int *cutoff_tz;
644         int *cutoff_cnt;
645 };
646
647 static int read_ref_at_ent(unsigned char *osha1, unsigned char *nsha1,
648                 const char *email, unsigned long timestamp, int tz,
649                 const char *message, void *cb_data)
650 {
651         struct read_ref_at_cb *cb = cb_data;
652
653         cb->reccnt++;
654         cb->tz = tz;
655         cb->date = timestamp;
656
657         if (timestamp <= cb->at_time || cb->cnt == 0) {
658                 if (cb->msg)
659                         *cb->msg = xstrdup(message);
660                 if (cb->cutoff_time)
661                         *cb->cutoff_time = timestamp;
662                 if (cb->cutoff_tz)
663                         *cb->cutoff_tz = tz;
664                 if (cb->cutoff_cnt)
665                         *cb->cutoff_cnt = cb->reccnt - 1;
666                 /*
667                  * we have not yet updated cb->[n|o]sha1 so they still
668                  * hold the values for the previous record.
669                  */
670                 if (!is_null_sha1(cb->osha1)) {
671                         hashcpy(cb->sha1, nsha1);
672                         if (hashcmp(cb->osha1, nsha1))
673                                 warning("Log for ref %s has gap after %s.",
674                                         cb->refname, show_date(cb->date, cb->tz, DATE_MODE(RFC2822)));
675                 }
676                 else if (cb->date == cb->at_time)
677                         hashcpy(cb->sha1, nsha1);
678                 else if (hashcmp(nsha1, cb->sha1))
679                         warning("Log for ref %s unexpectedly ended on %s.",
680                                 cb->refname, show_date(cb->date, cb->tz,
681                                                        DATE_MODE(RFC2822)));
682                 hashcpy(cb->osha1, osha1);
683                 hashcpy(cb->nsha1, nsha1);
684                 cb->found_it = 1;
685                 return 1;
686         }
687         hashcpy(cb->osha1, osha1);
688         hashcpy(cb->nsha1, nsha1);
689         if (cb->cnt > 0)
690                 cb->cnt--;
691         return 0;
692 }
693
694 static int read_ref_at_ent_oldest(unsigned char *osha1, unsigned char *nsha1,
695                                   const char *email, unsigned long timestamp,
696                                   int tz, const char *message, void *cb_data)
697 {
698         struct read_ref_at_cb *cb = cb_data;
699
700         if (cb->msg)
701                 *cb->msg = xstrdup(message);
702         if (cb->cutoff_time)
703                 *cb->cutoff_time = timestamp;
704         if (cb->cutoff_tz)
705                 *cb->cutoff_tz = tz;
706         if (cb->cutoff_cnt)
707                 *cb->cutoff_cnt = cb->reccnt;
708         hashcpy(cb->sha1, osha1);
709         if (is_null_sha1(cb->sha1))
710                 hashcpy(cb->sha1, nsha1);
711         /* We just want the first entry */
712         return 1;
713 }
714
715 int read_ref_at(const char *refname, unsigned int flags, unsigned long at_time, int cnt,
716                 unsigned char *sha1, char **msg,
717                 unsigned long *cutoff_time, int *cutoff_tz, int *cutoff_cnt)
718 {
719         struct read_ref_at_cb cb;
720
721         memset(&cb, 0, sizeof(cb));
722         cb.refname = refname;
723         cb.at_time = at_time;
724         cb.cnt = cnt;
725         cb.msg = msg;
726         cb.cutoff_time = cutoff_time;
727         cb.cutoff_tz = cutoff_tz;
728         cb.cutoff_cnt = cutoff_cnt;
729         cb.sha1 = sha1;
730
731         for_each_reflog_ent_reverse(refname, read_ref_at_ent, &cb);
732
733         if (!cb.reccnt) {
734                 if (flags & GET_SHA1_QUIETLY)
735                         exit(128);
736                 else
737                         die("Log for %s is empty.", refname);
738         }
739         if (cb.found_it)
740                 return 0;
741
742         for_each_reflog_ent(refname, read_ref_at_ent_oldest, &cb);
743
744         return 1;
745 }
746
747 struct ref_transaction *ref_transaction_begin(struct strbuf *err)
748 {
749         assert(err);
750
751         return xcalloc(1, sizeof(struct ref_transaction));
752 }
753
754 void ref_transaction_free(struct ref_transaction *transaction)
755 {
756         int i;
757
758         if (!transaction)
759                 return;
760
761         for (i = 0; i < transaction->nr; i++) {
762                 free(transaction->updates[i]->msg);
763                 free(transaction->updates[i]);
764         }
765         free(transaction->updates);
766         free(transaction);
767 }
768
769 struct ref_update *ref_transaction_add_update(
770                 struct ref_transaction *transaction,
771                 const char *refname, unsigned int flags,
772                 const unsigned char *new_sha1,
773                 const unsigned char *old_sha1,
774                 const char *msg)
775 {
776         struct ref_update *update;
777
778         if (transaction->state != REF_TRANSACTION_OPEN)
779                 die("BUG: update called for transaction that is not open");
780
781         if ((flags & REF_ISPRUNING) && !(flags & REF_NODEREF))
782                 die("BUG: REF_ISPRUNING set without REF_NODEREF");
783
784         FLEX_ALLOC_STR(update, refname, refname);
785         ALLOC_GROW(transaction->updates, transaction->nr + 1, transaction->alloc);
786         transaction->updates[transaction->nr++] = update;
787
788         update->flags = flags;
789
790         if (flags & REF_HAVE_NEW)
791                 hashcpy(update->new_sha1, new_sha1);
792         if (flags & REF_HAVE_OLD)
793                 hashcpy(update->old_sha1, old_sha1);
794         if (msg)
795                 update->msg = xstrdup(msg);
796         return update;
797 }
798
799 int ref_transaction_update(struct ref_transaction *transaction,
800                            const char *refname,
801                            const unsigned char *new_sha1,
802                            const unsigned char *old_sha1,
803                            unsigned int flags, const char *msg,
804                            struct strbuf *err)
805 {
806         assert(err);
807
808         if ((new_sha1 && !is_null_sha1(new_sha1)) ?
809             check_refname_format(refname, REFNAME_ALLOW_ONELEVEL) :
810             !refname_is_safe(refname)) {
811                 strbuf_addf(err, "refusing to update ref with bad name '%s'",
812                             refname);
813                 return -1;
814         }
815
816         flags |= (new_sha1 ? REF_HAVE_NEW : 0) | (old_sha1 ? REF_HAVE_OLD : 0);
817
818         ref_transaction_add_update(transaction, refname, flags,
819                                    new_sha1, old_sha1, msg);
820         return 0;
821 }
822
823 int ref_transaction_create(struct ref_transaction *transaction,
824                            const char *refname,
825                            const unsigned char *new_sha1,
826                            unsigned int flags, const char *msg,
827                            struct strbuf *err)
828 {
829         if (!new_sha1 || is_null_sha1(new_sha1))
830                 die("BUG: create called without valid new_sha1");
831         return ref_transaction_update(transaction, refname, new_sha1,
832                                       null_sha1, flags, msg, err);
833 }
834
835 int ref_transaction_delete(struct ref_transaction *transaction,
836                            const char *refname,
837                            const unsigned char *old_sha1,
838                            unsigned int flags, const char *msg,
839                            struct strbuf *err)
840 {
841         if (old_sha1 && is_null_sha1(old_sha1))
842                 die("BUG: delete called with old_sha1 set to zeros");
843         return ref_transaction_update(transaction, refname,
844                                       null_sha1, old_sha1,
845                                       flags, msg, err);
846 }
847
848 int ref_transaction_verify(struct ref_transaction *transaction,
849                            const char *refname,
850                            const unsigned char *old_sha1,
851                            unsigned int flags,
852                            struct strbuf *err)
853 {
854         if (!old_sha1)
855                 die("BUG: verify called with old_sha1 set to NULL");
856         return ref_transaction_update(transaction, refname,
857                                       NULL, old_sha1,
858                                       flags, NULL, err);
859 }
860
861 int update_ref(const char *msg, const char *refname,
862                const unsigned char *new_sha1, const unsigned char *old_sha1,
863                unsigned int flags, enum action_on_err onerr)
864 {
865         struct ref_transaction *t = NULL;
866         struct strbuf err = STRBUF_INIT;
867         int ret = 0;
868
869         if (ref_type(refname) == REF_TYPE_PSEUDOREF) {
870                 ret = write_pseudoref(refname, new_sha1, old_sha1, &err);
871         } else {
872                 t = ref_transaction_begin(&err);
873                 if (!t ||
874                     ref_transaction_update(t, refname, new_sha1, old_sha1,
875                                            flags, msg, &err) ||
876                     ref_transaction_commit(t, &err)) {
877                         ret = 1;
878                         ref_transaction_free(t);
879                 }
880         }
881         if (ret) {
882                 const char *str = "update_ref failed for ref '%s': %s";
883
884                 switch (onerr) {
885                 case UPDATE_REFS_MSG_ON_ERR:
886                         error(str, refname, err.buf);
887                         break;
888                 case UPDATE_REFS_DIE_ON_ERR:
889                         die(str, refname, err.buf);
890                         break;
891                 case UPDATE_REFS_QUIET_ON_ERR:
892                         break;
893                 }
894                 strbuf_release(&err);
895                 return 1;
896         }
897         strbuf_release(&err);
898         if (t)
899                 ref_transaction_free(t);
900         return 0;
901 }
902
903 char *shorten_unambiguous_ref(const char *refname, int strict)
904 {
905         int i;
906         static char **scanf_fmts;
907         static int nr_rules;
908         char *short_name;
909
910         if (!nr_rules) {
911                 /*
912                  * Pre-generate scanf formats from ref_rev_parse_rules[].
913                  * Generate a format suitable for scanf from a
914                  * ref_rev_parse_rules rule by interpolating "%s" at the
915                  * location of the "%.*s".
916                  */
917                 size_t total_len = 0;
918                 size_t offset = 0;
919
920                 /* the rule list is NULL terminated, count them first */
921                 for (nr_rules = 0; ref_rev_parse_rules[nr_rules]; nr_rules++)
922                         /* -2 for strlen("%.*s") - strlen("%s"); +1 for NUL */
923                         total_len += strlen(ref_rev_parse_rules[nr_rules]) - 2 + 1;
924
925                 scanf_fmts = xmalloc(st_add(st_mult(sizeof(char *), nr_rules), total_len));
926
927                 offset = 0;
928                 for (i = 0; i < nr_rules; i++) {
929                         assert(offset < total_len);
930                         scanf_fmts[i] = (char *)&scanf_fmts[nr_rules] + offset;
931                         offset += snprintf(scanf_fmts[i], total_len - offset,
932                                            ref_rev_parse_rules[i], 2, "%s") + 1;
933                 }
934         }
935
936         /* bail out if there are no rules */
937         if (!nr_rules)
938                 return xstrdup(refname);
939
940         /* buffer for scanf result, at most refname must fit */
941         short_name = xstrdup(refname);
942
943         /* skip first rule, it will always match */
944         for (i = nr_rules - 1; i > 0 ; --i) {
945                 int j;
946                 int rules_to_fail = i;
947                 int short_name_len;
948
949                 if (1 != sscanf(refname, scanf_fmts[i], short_name))
950                         continue;
951
952                 short_name_len = strlen(short_name);
953
954                 /*
955                  * in strict mode, all (except the matched one) rules
956                  * must fail to resolve to a valid non-ambiguous ref
957                  */
958                 if (strict)
959                         rules_to_fail = nr_rules;
960
961                 /*
962                  * check if the short name resolves to a valid ref,
963                  * but use only rules prior to the matched one
964                  */
965                 for (j = 0; j < rules_to_fail; j++) {
966                         const char *rule = ref_rev_parse_rules[j];
967                         char refname[PATH_MAX];
968
969                         /* skip matched rule */
970                         if (i == j)
971                                 continue;
972
973                         /*
974                          * the short name is ambiguous, if it resolves
975                          * (with this previous rule) to a valid ref
976                          * read_ref() returns 0 on success
977                          */
978                         mksnpath(refname, sizeof(refname),
979                                  rule, short_name_len, short_name);
980                         if (ref_exists(refname))
981                                 break;
982                 }
983
984                 /*
985                  * short name is non-ambiguous if all previous rules
986                  * haven't resolved to a valid ref
987                  */
988                 if (j == rules_to_fail)
989                         return short_name;
990         }
991
992         free(short_name);
993         return xstrdup(refname);
994 }
995
996 static struct string_list *hide_refs;
997
998 int parse_hide_refs_config(const char *var, const char *value, const char *section)
999 {
1000         if (!strcmp("transfer.hiderefs", var) ||
1001             /* NEEDSWORK: use parse_config_key() once both are merged */
1002             (starts_with(var, section) && var[strlen(section)] == '.' &&
1003              !strcmp(var + strlen(section), ".hiderefs"))) {
1004                 char *ref;
1005                 int len;
1006
1007                 if (!value)
1008                         return config_error_nonbool(var);
1009                 ref = xstrdup(value);
1010                 len = strlen(ref);
1011                 while (len && ref[len - 1] == '/')
1012                         ref[--len] = '\0';
1013                 if (!hide_refs) {
1014                         hide_refs = xcalloc(1, sizeof(*hide_refs));
1015                         hide_refs->strdup_strings = 1;
1016                 }
1017                 string_list_append(hide_refs, ref);
1018         }
1019         return 0;
1020 }
1021
1022 int ref_is_hidden(const char *refname, const char *refname_full)
1023 {
1024         int i;
1025
1026         if (!hide_refs)
1027                 return 0;
1028         for (i = hide_refs->nr - 1; i >= 0; i--) {
1029                 const char *match = hide_refs->items[i].string;
1030                 const char *subject;
1031                 int neg = 0;
1032                 int len;
1033
1034                 if (*match == '!') {
1035                         neg = 1;
1036                         match++;
1037                 }
1038
1039                 if (*match == '^') {
1040                         subject = refname_full;
1041                         match++;
1042                 } else {
1043                         subject = refname;
1044                 }
1045
1046                 /* refname can be NULL when namespaces are used. */
1047                 if (!subject || !starts_with(subject, match))
1048                         continue;
1049                 len = strlen(match);
1050                 if (!subject[len] || subject[len] == '/')
1051                         return !neg;
1052         }
1053         return 0;
1054 }
1055
1056 const char *find_descendant_ref(const char *dirname,
1057                                 const struct string_list *extras,
1058                                 const struct string_list *skip)
1059 {
1060         int pos;
1061
1062         if (!extras)
1063                 return NULL;
1064
1065         /*
1066          * Look at the place where dirname would be inserted into
1067          * extras. If there is an entry at that position that starts
1068          * with dirname (remember, dirname includes the trailing
1069          * slash) and is not in skip, then we have a conflict.
1070          */
1071         for (pos = string_list_find_insert_index(extras, dirname, 0);
1072              pos < extras->nr; pos++) {
1073                 const char *extra_refname = extras->items[pos].string;
1074
1075                 if (!starts_with(extra_refname, dirname))
1076                         break;
1077
1078                 if (!skip || !string_list_has_string(skip, extra_refname))
1079                         return extra_refname;
1080         }
1081         return NULL;
1082 }
1083
1084 int rename_ref_available(const char *oldname, const char *newname)
1085 {
1086         struct string_list skip = STRING_LIST_INIT_NODUP;
1087         struct strbuf err = STRBUF_INIT;
1088         int ret;
1089
1090         string_list_insert(&skip, oldname);
1091         ret = !verify_refname_available(newname, NULL, &skip, &err);
1092         if (!ret)
1093                 error("%s", err.buf);
1094
1095         string_list_clear(&skip, 0);
1096         strbuf_release(&err);
1097         return ret;
1098 }
1099
1100 int head_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
1101 {
1102         struct object_id oid;
1103         int flag;
1104
1105         if (submodule) {
1106                 if (resolve_gitlink_ref(submodule, "HEAD", oid.hash) == 0)
1107                         return fn("HEAD", &oid, 0, cb_data);
1108
1109                 return 0;
1110         }
1111
1112         if (!read_ref_full("HEAD", RESOLVE_REF_READING, oid.hash, &flag))
1113                 return fn("HEAD", &oid, flag, cb_data);
1114
1115         return 0;
1116 }
1117
1118 int head_ref(each_ref_fn fn, void *cb_data)
1119 {
1120         return head_ref_submodule(NULL, fn, cb_data);
1121 }
1122
1123 /*
1124  * Call fn for each reference in the specified submodule for which the
1125  * refname begins with prefix. If trim is non-zero, then trim that
1126  * many characters off the beginning of each refname before passing
1127  * the refname to fn. flags can be DO_FOR_EACH_INCLUDE_BROKEN to
1128  * include broken references in the iteration. If fn ever returns a
1129  * non-zero value, stop the iteration and return that value;
1130  * otherwise, return 0.
1131  */
1132 static int do_for_each_ref(const char *submodule, const char *prefix,
1133                            each_ref_fn fn, int trim, int flags, void *cb_data)
1134 {
1135         struct ref_iterator *iter;
1136
1137         iter = files_ref_iterator_begin(submodule, prefix, flags);
1138         iter = prefix_ref_iterator_begin(iter, prefix, trim);
1139
1140         return do_for_each_ref_iterator(iter, fn, cb_data);
1141 }
1142
1143 int for_each_ref(each_ref_fn fn, void *cb_data)
1144 {
1145         return do_for_each_ref(NULL, "", fn, 0, 0, cb_data);
1146 }
1147
1148 int for_each_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
1149 {
1150         return do_for_each_ref(submodule, "", fn, 0, 0, cb_data);
1151 }
1152
1153 int for_each_ref_in(const char *prefix, each_ref_fn fn, void *cb_data)
1154 {
1155         return do_for_each_ref(NULL, prefix, fn, strlen(prefix), 0, cb_data);
1156 }
1157
1158 int for_each_fullref_in(const char *prefix, each_ref_fn fn, void *cb_data, unsigned int broken)
1159 {
1160         unsigned int flag = 0;
1161
1162         if (broken)
1163                 flag = DO_FOR_EACH_INCLUDE_BROKEN;
1164         return do_for_each_ref(NULL, prefix, fn, 0, flag, cb_data);
1165 }
1166
1167 int for_each_ref_in_submodule(const char *submodule, const char *prefix,
1168                 each_ref_fn fn, void *cb_data)
1169 {
1170         return do_for_each_ref(submodule, prefix, fn, strlen(prefix), 0, cb_data);
1171 }
1172
1173 int for_each_replace_ref(each_ref_fn fn, void *cb_data)
1174 {
1175         return do_for_each_ref(NULL, git_replace_ref_base, fn,
1176                                strlen(git_replace_ref_base), 0, cb_data);
1177 }
1178
1179 int for_each_namespaced_ref(each_ref_fn fn, void *cb_data)
1180 {
1181         struct strbuf buf = STRBUF_INIT;
1182         int ret;
1183         strbuf_addf(&buf, "%srefs/", get_git_namespace());
1184         ret = do_for_each_ref(NULL, buf.buf, fn, 0, 0, cb_data);
1185         strbuf_release(&buf);
1186         return ret;
1187 }
1188
1189 int for_each_rawref(each_ref_fn fn, void *cb_data)
1190 {
1191         return do_for_each_ref(NULL, "", fn, 0,
1192                                DO_FOR_EACH_INCLUDE_BROKEN, cb_data);
1193 }
1194
1195 /* This function needs to return a meaningful errno on failure */
1196 const char *resolve_ref_unsafe(const char *refname, int resolve_flags,
1197                                unsigned char *sha1, int *flags)
1198 {
1199         static struct strbuf sb_refname = STRBUF_INIT;
1200         int unused_flags;
1201         int symref_count;
1202
1203         if (!flags)
1204                 flags = &unused_flags;
1205
1206         *flags = 0;
1207
1208         if (check_refname_format(refname, REFNAME_ALLOW_ONELEVEL)) {
1209                 if (!(resolve_flags & RESOLVE_REF_ALLOW_BAD_NAME) ||
1210                     !refname_is_safe(refname)) {
1211                         errno = EINVAL;
1212                         return NULL;
1213                 }
1214
1215                 /*
1216                  * dwim_ref() uses REF_ISBROKEN to distinguish between
1217                  * missing refs and refs that were present but invalid,
1218                  * to complain about the latter to stderr.
1219                  *
1220                  * We don't know whether the ref exists, so don't set
1221                  * REF_ISBROKEN yet.
1222                  */
1223                 *flags |= REF_BAD_NAME;
1224         }
1225
1226         for (symref_count = 0; symref_count < SYMREF_MAXDEPTH; symref_count++) {
1227                 unsigned int read_flags = 0;
1228
1229                 if (read_raw_ref(refname, sha1, &sb_refname, &read_flags)) {
1230                         *flags |= read_flags;
1231                         if (errno != ENOENT || (resolve_flags & RESOLVE_REF_READING))
1232                                 return NULL;
1233                         hashclr(sha1);
1234                         if (*flags & REF_BAD_NAME)
1235                                 *flags |= REF_ISBROKEN;
1236                         return refname;
1237                 }
1238
1239                 *flags |= read_flags;
1240
1241                 if (!(read_flags & REF_ISSYMREF)) {
1242                         if (*flags & REF_BAD_NAME) {
1243                                 hashclr(sha1);
1244                                 *flags |= REF_ISBROKEN;
1245                         }
1246                         return refname;
1247                 }
1248
1249                 refname = sb_refname.buf;
1250                 if (resolve_flags & RESOLVE_REF_NO_RECURSE) {
1251                         hashclr(sha1);
1252                         return refname;
1253                 }
1254                 if (check_refname_format(refname, REFNAME_ALLOW_ONELEVEL)) {
1255                         if (!(resolve_flags & RESOLVE_REF_ALLOW_BAD_NAME) ||
1256                             !refname_is_safe(refname)) {
1257                                 errno = EINVAL;
1258                                 return NULL;
1259                         }
1260
1261                         *flags |= REF_ISBROKEN | REF_BAD_NAME;
1262                 }
1263         }
1264
1265         errno = ELOOP;
1266         return NULL;
1267 }