Merge branch 'bc/object-id'
[git/git.git] / refs / files-backend.c
1 #include "../cache.h"
2 #include "../config.h"
3 #include "../refs.h"
4 #include "refs-internal.h"
5 #include "ref-cache.h"
6 #include "packed-backend.h"
7 #include "../iterator.h"
8 #include "../dir-iterator.h"
9 #include "../lockfile.h"
10 #include "../object.h"
11 #include "../dir.h"
12 #include "../chdir-notify.h"
13
14 /*
15 * This backend uses the following flags in `ref_update::flags` for
16 * internal bookkeeping purposes. Their numerical values must not
17 * conflict with REF_NO_DEREF, REF_FORCE_CREATE_REFLOG, REF_HAVE_NEW,
18 * REF_HAVE_OLD, or REF_IS_PRUNING, which are also stored in
19 * `ref_update::flags`.
20 */
21
22 /*
23 * Used as a flag in ref_update::flags when a loose ref is being
24 * pruned. This flag must only be used when REF_NO_DEREF is set.
25 */
26 #define REF_IS_PRUNING (1 << 4)
27
28 /*
29 * Flag passed to lock_ref_sha1_basic() telling it to tolerate broken
30 * refs (i.e., because the reference is about to be deleted anyway).
31 */
32 #define REF_DELETING (1 << 5)
33
34 /*
35 * Used as a flag in ref_update::flags when the lockfile needs to be
36 * committed.
37 */
38 #define REF_NEEDS_COMMIT (1 << 6)
39
40 /*
41 * Used as a flag in ref_update::flags when we want to log a ref
42 * update but not actually perform it. This is used when a symbolic
43 * ref update is split up.
44 */
45 #define REF_LOG_ONLY (1 << 7)
46
47 /*
48 * Used as a flag in ref_update::flags when the ref_update was via an
49 * update to HEAD.
50 */
51 #define REF_UPDATE_VIA_HEAD (1 << 8)
52
53 /*
54 * Used as a flag in ref_update::flags when the loose reference has
55 * been deleted.
56 */
57 #define REF_DELETED_LOOSE (1 << 9)
58
59 struct ref_lock {
60 char *ref_name;
61 struct lock_file lk;
62 struct object_id old_oid;
63 };
64
65 struct files_ref_store {
66 struct ref_store base;
67 unsigned int store_flags;
68
69 char *gitdir;
70 char *gitcommondir;
71
72 struct ref_cache *loose;
73
74 struct ref_store *packed_ref_store;
75 };
76
77 static void clear_loose_ref_cache(struct files_ref_store *refs)
78 {
79 if (refs->loose) {
80 free_ref_cache(refs->loose);
81 refs->loose = NULL;
82 }
83 }
84
85 /*
86 * Create a new submodule ref cache and add it to the internal
87 * set of caches.
88 */
89 static struct ref_store *files_ref_store_create(const char *gitdir,
90 unsigned int flags)
91 {
92 struct files_ref_store *refs = xcalloc(1, sizeof(*refs));
93 struct ref_store *ref_store = (struct ref_store *)refs;
94 struct strbuf sb = STRBUF_INIT;
95
96 base_ref_store_init(ref_store, &refs_be_files);
97 refs->store_flags = flags;
98
99 refs->gitdir = xstrdup(gitdir);
100 get_common_dir_noenv(&sb, gitdir);
101 refs->gitcommondir = strbuf_detach(&sb, NULL);
102 strbuf_addf(&sb, "%s/packed-refs", refs->gitcommondir);
103 refs->packed_ref_store = packed_ref_store_create(sb.buf, flags);
104 strbuf_release(&sb);
105
106 chdir_notify_reparent("files-backend $GIT_DIR",
107 &refs->gitdir);
108 chdir_notify_reparent("files-backend $GIT_COMMONDIR",
109 &refs->gitcommondir);
110
111 return ref_store;
112 }
113
114 /*
115 * Die if refs is not the main ref store. caller is used in any
116 * necessary error messages.
117 */
118 static void files_assert_main_repository(struct files_ref_store *refs,
119 const char *caller)
120 {
121 if (refs->store_flags & REF_STORE_MAIN)
122 return;
123
124 BUG("operation %s only allowed for main ref store", caller);
125 }
126
127 /*
128 * Downcast ref_store to files_ref_store. Die if ref_store is not a
129 * files_ref_store. required_flags is compared with ref_store's
130 * store_flags to ensure the ref_store has all required capabilities.
131 * "caller" is used in any necessary error messages.
132 */
133 static struct files_ref_store *files_downcast(struct ref_store *ref_store,
134 unsigned int required_flags,
135 const char *caller)
136 {
137 struct files_ref_store *refs;
138
139 if (ref_store->be != &refs_be_files)
140 BUG("ref_store is type \"%s\" not \"files\" in %s",
141 ref_store->be->name, caller);
142
143 refs = (struct files_ref_store *)ref_store;
144
145 if ((refs->store_flags & required_flags) != required_flags)
146 BUG("operation %s requires abilities 0x%x, but only have 0x%x",
147 caller, required_flags, refs->store_flags);
148
149 return refs;
150 }
151
152 static void files_reflog_path(struct files_ref_store *refs,
153 struct strbuf *sb,
154 const char *refname)
155 {
156 switch (ref_type(refname)) {
157 case REF_TYPE_PER_WORKTREE:
158 case REF_TYPE_PSEUDOREF:
159 strbuf_addf(sb, "%s/logs/%s", refs->gitdir, refname);
160 break;
161 case REF_TYPE_NORMAL:
162 strbuf_addf(sb, "%s/logs/%s", refs->gitcommondir, refname);
163 break;
164 default:
165 BUG("unknown ref type %d of ref %s",
166 ref_type(refname), refname);
167 }
168 }
169
170 static void files_ref_path(struct files_ref_store *refs,
171 struct strbuf *sb,
172 const char *refname)
173 {
174 switch (ref_type(refname)) {
175 case REF_TYPE_PER_WORKTREE:
176 case REF_TYPE_PSEUDOREF:
177 strbuf_addf(sb, "%s/%s", refs->gitdir, refname);
178 break;
179 case REF_TYPE_NORMAL:
180 strbuf_addf(sb, "%s/%s", refs->gitcommondir, refname);
181 break;
182 default:
183 BUG("unknown ref type %d of ref %s",
184 ref_type(refname), refname);
185 }
186 }
187
188 /*
189 * Read the loose references from the namespace dirname into dir
190 * (without recursing). dirname must end with '/'. dir must be the
191 * directory entry corresponding to dirname.
192 */
193 static void loose_fill_ref_dir(struct ref_store *ref_store,
194 struct ref_dir *dir, const char *dirname)
195 {
196 struct files_ref_store *refs =
197 files_downcast(ref_store, REF_STORE_READ, "fill_ref_dir");
198 DIR *d;
199 struct dirent *de;
200 int dirnamelen = strlen(dirname);
201 struct strbuf refname;
202 struct strbuf path = STRBUF_INIT;
203 size_t path_baselen;
204
205 files_ref_path(refs, &path, dirname);
206 path_baselen = path.len;
207
208 d = opendir(path.buf);
209 if (!d) {
210 strbuf_release(&path);
211 return;
212 }
213
214 strbuf_init(&refname, dirnamelen + 257);
215 strbuf_add(&refname, dirname, dirnamelen);
216
217 while ((de = readdir(d)) != NULL) {
218 struct object_id oid;
219 struct stat st;
220 int flag;
221
222 if (de->d_name[0] == '.')
223 continue;
224 if (ends_with(de->d_name, ".lock"))
225 continue;
226 strbuf_addstr(&refname, de->d_name);
227 strbuf_addstr(&path, de->d_name);
228 if (stat(path.buf, &st) < 0) {
229 ; /* silently ignore */
230 } else if (S_ISDIR(st.st_mode)) {
231 strbuf_addch(&refname, '/');
232 add_entry_to_dir(dir,
233 create_dir_entry(dir->cache, refname.buf,
234 refname.len, 1));
235 } else {
236 if (!refs_resolve_ref_unsafe(&refs->base,
237 refname.buf,
238 RESOLVE_REF_READING,
239 &oid, &flag)) {
240 oidclr(&oid);
241 flag |= REF_ISBROKEN;
242 } else if (is_null_oid(&oid)) {
243 /*
244 * It is so astronomically unlikely
245 * that null_oid is the OID of an
246 * actual object that we consider its
247 * appearance in a loose reference
248 * file to be repo corruption
249 * (probably due to a software bug).
250 */
251 flag |= REF_ISBROKEN;
252 }
253
254 if (check_refname_format(refname.buf,
255 REFNAME_ALLOW_ONELEVEL)) {
256 if (!refname_is_safe(refname.buf))
257 die("loose refname is dangerous: %s", refname.buf);
258 oidclr(&oid);
259 flag |= REF_BAD_NAME | REF_ISBROKEN;
260 }
261 add_entry_to_dir(dir,
262 create_ref_entry(refname.buf, &oid, flag));
263 }
264 strbuf_setlen(&refname, dirnamelen);
265 strbuf_setlen(&path, path_baselen);
266 }
267 strbuf_release(&refname);
268 strbuf_release(&path);
269 closedir(d);
270
271 /*
272 * Manually add refs/bisect, which, being per-worktree, might
273 * not appear in the directory listing for refs/ in the main
274 * repo.
275 */
276 if (!strcmp(dirname, "refs/")) {
277 int pos = search_ref_dir(dir, "refs/bisect/", 12);
278
279 if (pos < 0) {
280 struct ref_entry *child_entry = create_dir_entry(
281 dir->cache, "refs/bisect/", 12, 1);
282 add_entry_to_dir(dir, child_entry);
283 }
284 }
285 }
286
287 static struct ref_cache *get_loose_ref_cache(struct files_ref_store *refs)
288 {
289 if (!refs->loose) {
290 /*
291 * Mark the top-level directory complete because we
292 * are about to read the only subdirectory that can
293 * hold references:
294 */
295 refs->loose = create_ref_cache(&refs->base, loose_fill_ref_dir);
296
297 /* We're going to fill the top level ourselves: */
298 refs->loose->root->flag &= ~REF_INCOMPLETE;
299
300 /*
301 * Add an incomplete entry for "refs/" (to be filled
302 * lazily):
303 */
304 add_entry_to_dir(get_ref_dir(refs->loose->root),
305 create_dir_entry(refs->loose, "refs/", 5, 1));
306 }
307 return refs->loose;
308 }
309
310 static int files_read_raw_ref(struct ref_store *ref_store,
311 const char *refname, struct object_id *oid,
312 struct strbuf *referent, unsigned int *type)
313 {
314 struct files_ref_store *refs =
315 files_downcast(ref_store, REF_STORE_READ, "read_raw_ref");
316 struct strbuf sb_contents = STRBUF_INIT;
317 struct strbuf sb_path = STRBUF_INIT;
318 const char *path;
319 const char *buf;
320 const char *p;
321 struct stat st;
322 int fd;
323 int ret = -1;
324 int save_errno;
325 int remaining_retries = 3;
326
327 *type = 0;
328 strbuf_reset(&sb_path);
329
330 files_ref_path(refs, &sb_path, refname);
331
332 path = sb_path.buf;
333
334 stat_ref:
335 /*
336 * We might have to loop back here to avoid a race
337 * condition: first we lstat() the file, then we try
338 * to read it as a link or as a file. But if somebody
339 * changes the type of the file (file <-> directory
340 * <-> symlink) between the lstat() and reading, then
341 * we don't want to report that as an error but rather
342 * try again starting with the lstat().
343 *
344 * We'll keep a count of the retries, though, just to avoid
345 * any confusing situation sending us into an infinite loop.
346 */
347
348 if (remaining_retries-- <= 0)
349 goto out;
350
351 if (lstat(path, &st) < 0) {
352 if (errno != ENOENT)
353 goto out;
354 if (refs_read_raw_ref(refs->packed_ref_store, refname,
355 oid, referent, type)) {
356 errno = ENOENT;
357 goto out;
358 }
359 ret = 0;
360 goto out;
361 }
362
363 /* Follow "normalized" - ie "refs/.." symlinks by hand */
364 if (S_ISLNK(st.st_mode)) {
365 strbuf_reset(&sb_contents);
366 if (strbuf_readlink(&sb_contents, path, 0) < 0) {
367 if (errno == ENOENT || errno == EINVAL)
368 /* inconsistent with lstat; retry */
369 goto stat_ref;
370 else
371 goto out;
372 }
373 if (starts_with(sb_contents.buf, "refs/") &&
374 !check_refname_format(sb_contents.buf, 0)) {
375 strbuf_swap(&sb_contents, referent);
376 *type |= REF_ISSYMREF;
377 ret = 0;
378 goto out;
379 }
380 /*
381 * It doesn't look like a refname; fall through to just
382 * treating it like a non-symlink, and reading whatever it
383 * points to.
384 */
385 }
386
387 /* Is it a directory? */
388 if (S_ISDIR(st.st_mode)) {
389 /*
390 * Even though there is a directory where the loose
391 * ref is supposed to be, there could still be a
392 * packed ref:
393 */
394 if (refs_read_raw_ref(refs->packed_ref_store, refname,
395 oid, referent, type)) {
396 errno = EISDIR;
397 goto out;
398 }
399 ret = 0;
400 goto out;
401 }
402
403 /*
404 * Anything else, just open it and try to use it as
405 * a ref
406 */
407 fd = open(path, O_RDONLY);
408 if (fd < 0) {
409 if (errno == ENOENT && !S_ISLNK(st.st_mode))
410 /* inconsistent with lstat; retry */
411 goto stat_ref;
412 else
413 goto out;
414 }
415 strbuf_reset(&sb_contents);
416 if (strbuf_read(&sb_contents, fd, 256) < 0) {
417 int save_errno = errno;
418 close(fd);
419 errno = save_errno;
420 goto out;
421 }
422 close(fd);
423 strbuf_rtrim(&sb_contents);
424 buf = sb_contents.buf;
425 if (starts_with(buf, "ref:")) {
426 buf += 4;
427 while (isspace(*buf))
428 buf++;
429
430 strbuf_reset(referent);
431 strbuf_addstr(referent, buf);
432 *type |= REF_ISSYMREF;
433 ret = 0;
434 goto out;
435 }
436
437 /*
438 * Please note that FETCH_HEAD has additional
439 * data after the sha.
440 */
441 if (parse_oid_hex(buf, oid, &p) ||
442 (*p != '\0' && !isspace(*p))) {
443 *type |= REF_ISBROKEN;
444 errno = EINVAL;
445 goto out;
446 }
447
448 ret = 0;
449
450 out:
451 save_errno = errno;
452 strbuf_release(&sb_path);
453 strbuf_release(&sb_contents);
454 errno = save_errno;
455 return ret;
456 }
457
458 static void unlock_ref(struct ref_lock *lock)
459 {
460 rollback_lock_file(&lock->lk);
461 free(lock->ref_name);
462 free(lock);
463 }
464
465 /*
466 * Lock refname, without following symrefs, and set *lock_p to point
467 * at a newly-allocated lock object. Fill in lock->old_oid, referent,
468 * and type similarly to read_raw_ref().
469 *
470 * The caller must verify that refname is a "safe" reference name (in
471 * the sense of refname_is_safe()) before calling this function.
472 *
473 * If the reference doesn't already exist, verify that refname doesn't
474 * have a D/F conflict with any existing references. extras and skip
475 * are passed to refs_verify_refname_available() for this check.
476 *
477 * If mustexist is not set and the reference is not found or is
478 * broken, lock the reference anyway but clear old_oid.
479 *
480 * Return 0 on success. On failure, write an error message to err and
481 * return TRANSACTION_NAME_CONFLICT or TRANSACTION_GENERIC_ERROR.
482 *
483 * Implementation note: This function is basically
484 *
485 * lock reference
486 * read_raw_ref()
487 *
488 * but it includes a lot more code to
489 * - Deal with possible races with other processes
490 * - Avoid calling refs_verify_refname_available() when it can be
491 * avoided, namely if we were successfully able to read the ref
492 * - Generate informative error messages in the case of failure
493 */
494 static int lock_raw_ref(struct files_ref_store *refs,
495 const char *refname, int mustexist,
496 const struct string_list *extras,
497 const struct string_list *skip,
498 struct ref_lock **lock_p,
499 struct strbuf *referent,
500 unsigned int *type,
501 struct strbuf *err)
502 {
503 struct ref_lock *lock;
504 struct strbuf ref_file = STRBUF_INIT;
505 int attempts_remaining = 3;
506 int ret = TRANSACTION_GENERIC_ERROR;
507
508 assert(err);
509 files_assert_main_repository(refs, "lock_raw_ref");
510
511 *type = 0;
512
513 /* First lock the file so it can't change out from under us. */
514
515 *lock_p = lock = xcalloc(1, sizeof(*lock));
516
517 lock->ref_name = xstrdup(refname);
518 files_ref_path(refs, &ref_file, refname);
519
520 retry:
521 switch (safe_create_leading_directories(ref_file.buf)) {
522 case SCLD_OK:
523 break; /* success */
524 case SCLD_EXISTS:
525 /*
526 * Suppose refname is "refs/foo/bar". We just failed
527 * to create the containing directory, "refs/foo",
528 * because there was a non-directory in the way. This
529 * indicates a D/F conflict, probably because of
530 * another reference such as "refs/foo". There is no
531 * reason to expect this error to be transitory.
532 */
533 if (refs_verify_refname_available(&refs->base, refname,
534 extras, skip, err)) {
535 if (mustexist) {
536 /*
537 * To the user the relevant error is
538 * that the "mustexist" reference is
539 * missing:
540 */
541 strbuf_reset(err);
542 strbuf_addf(err, "unable to resolve reference '%s'",
543 refname);
544 } else {
545 /*
546 * The error message set by
547 * refs_verify_refname_available() is
548 * OK.
549 */
550 ret = TRANSACTION_NAME_CONFLICT;
551 }
552 } else {
553 /*
554 * The file that is in the way isn't a loose
555 * reference. Report it as a low-level
556 * failure.
557 */
558 strbuf_addf(err, "unable to create lock file %s.lock; "
559 "non-directory in the way",
560 ref_file.buf);
561 }
562 goto error_return;
563 case SCLD_VANISHED:
564 /* Maybe another process was tidying up. Try again. */
565 if (--attempts_remaining > 0)
566 goto retry;
567 /* fall through */
568 default:
569 strbuf_addf(err, "unable to create directory for %s",
570 ref_file.buf);
571 goto error_return;
572 }
573
574 if (hold_lock_file_for_update_timeout(
575 &lock->lk, ref_file.buf, LOCK_NO_DEREF,
576 get_files_ref_lock_timeout_ms()) < 0) {
577 if (errno == ENOENT && --attempts_remaining > 0) {
578 /*
579 * Maybe somebody just deleted one of the
580 * directories leading to ref_file. Try
581 * again:
582 */
583 goto retry;
584 } else {
585 unable_to_lock_message(ref_file.buf, errno, err);
586 goto error_return;
587 }
588 }
589
590 /*
591 * Now we hold the lock and can read the reference without
592 * fear that its value will change.
593 */
594
595 if (files_read_raw_ref(&refs->base, refname,
596 &lock->old_oid, referent, type)) {
597 if (errno == ENOENT) {
598 if (mustexist) {
599 /* Garden variety missing reference. */
600 strbuf_addf(err, "unable to resolve reference '%s'",
601 refname);
602 goto error_return;
603 } else {
604 /*
605 * Reference is missing, but that's OK. We
606 * know that there is not a conflict with
607 * another loose reference because
608 * (supposing that we are trying to lock
609 * reference "refs/foo/bar"):
610 *
611 * - We were successfully able to create
612 * the lockfile refs/foo/bar.lock, so we
613 * know there cannot be a loose reference
614 * named "refs/foo".
615 *
616 * - We got ENOENT and not EISDIR, so we
617 * know that there cannot be a loose
618 * reference named "refs/foo/bar/baz".
619 */
620 }
621 } else if (errno == EISDIR) {
622 /*
623 * There is a directory in the way. It might have
624 * contained references that have been deleted. If
625 * we don't require that the reference already
626 * exists, try to remove the directory so that it
627 * doesn't cause trouble when we want to rename the
628 * lockfile into place later.
629 */
630 if (mustexist) {
631 /* Garden variety missing reference. */
632 strbuf_addf(err, "unable to resolve reference '%s'",
633 refname);
634 goto error_return;
635 } else if (remove_dir_recursively(&ref_file,
636 REMOVE_DIR_EMPTY_ONLY)) {
637 if (refs_verify_refname_available(
638 &refs->base, refname,
639 extras, skip, err)) {
640 /*
641 * The error message set by
642 * verify_refname_available() is OK.
643 */
644 ret = TRANSACTION_NAME_CONFLICT;
645 goto error_return;
646 } else {
647 /*
648 * We can't delete the directory,
649 * but we also don't know of any
650 * references that it should
651 * contain.
652 */
653 strbuf_addf(err, "there is a non-empty directory '%s' "
654 "blocking reference '%s'",
655 ref_file.buf, refname);
656 goto error_return;
657 }
658 }
659 } else if (errno == EINVAL && (*type & REF_ISBROKEN)) {
660 strbuf_addf(err, "unable to resolve reference '%s': "
661 "reference broken", refname);
662 goto error_return;
663 } else {
664 strbuf_addf(err, "unable to resolve reference '%s': %s",
665 refname, strerror(errno));
666 goto error_return;
667 }
668
669 /*
670 * If the ref did not exist and we are creating it,
671 * make sure there is no existing packed ref that
672 * conflicts with refname:
673 */
674 if (refs_verify_refname_available(
675 refs->packed_ref_store, refname,
676 extras, skip, err))
677 goto error_return;
678 }
679
680 ret = 0;
681 goto out;
682
683 error_return:
684 unlock_ref(lock);
685 *lock_p = NULL;
686
687 out:
688 strbuf_release(&ref_file);
689 return ret;
690 }
691
692 struct files_ref_iterator {
693 struct ref_iterator base;
694
695 struct ref_iterator *iter0;
696 unsigned int flags;
697 };
698
699 static int files_ref_iterator_advance(struct ref_iterator *ref_iterator)
700 {
701 struct files_ref_iterator *iter =
702 (struct files_ref_iterator *)ref_iterator;
703 int ok;
704
705 while ((ok = ref_iterator_advance(iter->iter0)) == ITER_OK) {
706 if (iter->flags & DO_FOR_EACH_PER_WORKTREE_ONLY &&
707 ref_type(iter->iter0->refname) != REF_TYPE_PER_WORKTREE)
708 continue;
709
710 if (!(iter->flags & DO_FOR_EACH_INCLUDE_BROKEN) &&
711 !ref_resolves_to_object(iter->iter0->refname,
712 iter->iter0->oid,
713 iter->iter0->flags))
714 continue;
715
716 iter->base.refname = iter->iter0->refname;
717 iter->base.oid = iter->iter0->oid;
718 iter->base.flags = iter->iter0->flags;
719 return ITER_OK;
720 }
721
722 iter->iter0 = NULL;
723 if (ref_iterator_abort(ref_iterator) != ITER_DONE)
724 ok = ITER_ERROR;
725
726 return ok;
727 }
728
729 static int files_ref_iterator_peel(struct ref_iterator *ref_iterator,
730 struct object_id *peeled)
731 {
732 struct files_ref_iterator *iter =
733 (struct files_ref_iterator *)ref_iterator;
734
735 return ref_iterator_peel(iter->iter0, peeled);
736 }
737
738 static int files_ref_iterator_abort(struct ref_iterator *ref_iterator)
739 {
740 struct files_ref_iterator *iter =
741 (struct files_ref_iterator *)ref_iterator;
742 int ok = ITER_DONE;
743
744 if (iter->iter0)
745 ok = ref_iterator_abort(iter->iter0);
746
747 base_ref_iterator_free(ref_iterator);
748 return ok;
749 }
750
751 static struct ref_iterator_vtable files_ref_iterator_vtable = {
752 files_ref_iterator_advance,
753 files_ref_iterator_peel,
754 files_ref_iterator_abort
755 };
756
757 static struct ref_iterator *files_ref_iterator_begin(
758 struct ref_store *ref_store,
759 const char *prefix, unsigned int flags)
760 {
761 struct files_ref_store *refs;
762 struct ref_iterator *loose_iter, *packed_iter, *overlay_iter;
763 struct files_ref_iterator *iter;
764 struct ref_iterator *ref_iterator;
765 unsigned int required_flags = REF_STORE_READ;
766
767 if (!(flags & DO_FOR_EACH_INCLUDE_BROKEN))
768 required_flags |= REF_STORE_ODB;
769
770 refs = files_downcast(ref_store, required_flags, "ref_iterator_begin");
771
772 /*
773 * We must make sure that all loose refs are read before
774 * accessing the packed-refs file; this avoids a race
775 * condition if loose refs are migrated to the packed-refs
776 * file by a simultaneous process, but our in-memory view is
777 * from before the migration. We ensure this as follows:
778 * First, we call start the loose refs iteration with its
779 * `prime_ref` argument set to true. This causes the loose
780 * references in the subtree to be pre-read into the cache.
781 * (If they've already been read, that's OK; we only need to
782 * guarantee that they're read before the packed refs, not
783 * *how much* before.) After that, we call
784 * packed_ref_iterator_begin(), which internally checks
785 * whether the packed-ref cache is up to date with what is on
786 * disk, and re-reads it if not.
787 */
788
789 loose_iter = cache_ref_iterator_begin(get_loose_ref_cache(refs),
790 prefix, 1);
791
792 /*
793 * The packed-refs file might contain broken references, for
794 * example an old version of a reference that points at an
795 * object that has since been garbage-collected. This is OK as
796 * long as there is a corresponding loose reference that
797 * overrides it, and we don't want to emit an error message in
798 * this case. So ask the packed_ref_store for all of its
799 * references, and (if needed) do our own check for broken
800 * ones in files_ref_iterator_advance(), after we have merged
801 * the packed and loose references.
802 */
803 packed_iter = refs_ref_iterator_begin(
804 refs->packed_ref_store, prefix, 0,
805 DO_FOR_EACH_INCLUDE_BROKEN);
806
807 overlay_iter = overlay_ref_iterator_begin(loose_iter, packed_iter);
808
809 iter = xcalloc(1, sizeof(*iter));
810 ref_iterator = &iter->base;
811 base_ref_iterator_init(ref_iterator, &files_ref_iterator_vtable,
812 overlay_iter->ordered);
813 iter->iter0 = overlay_iter;
814 iter->flags = flags;
815
816 return ref_iterator;
817 }
818
819 /*
820 * Verify that the reference locked by lock has the value old_oid
821 * (unless it is NULL). Fail if the reference doesn't exist and
822 * mustexist is set. Return 0 on success. On error, write an error
823 * message to err, set errno, and return a negative value.
824 */
825 static int verify_lock(struct ref_store *ref_store, struct ref_lock *lock,
826 const struct object_id *old_oid, int mustexist,
827 struct strbuf *err)
828 {
829 assert(err);
830
831 if (refs_read_ref_full(ref_store, lock->ref_name,
832 mustexist ? RESOLVE_REF_READING : 0,
833 &lock->old_oid, NULL)) {
834 if (old_oid) {
835 int save_errno = errno;
836 strbuf_addf(err, "can't verify ref '%s'", lock->ref_name);
837 errno = save_errno;
838 return -1;
839 } else {
840 oidclr(&lock->old_oid);
841 return 0;
842 }
843 }
844 if (old_oid && oidcmp(&lock->old_oid, old_oid)) {
845 strbuf_addf(err, "ref '%s' is at %s but expected %s",
846 lock->ref_name,
847 oid_to_hex(&lock->old_oid),
848 oid_to_hex(old_oid));
849 errno = EBUSY;
850 return -1;
851 }
852 return 0;
853 }
854
855 static int remove_empty_directories(struct strbuf *path)
856 {
857 /*
858 * we want to create a file but there is a directory there;
859 * if that is an empty directory (or a directory that contains
860 * only empty directories), remove them.
861 */
862 return remove_dir_recursively(path, REMOVE_DIR_EMPTY_ONLY);
863 }
864
865 static int create_reflock(const char *path, void *cb)
866 {
867 struct lock_file *lk = cb;
868
869 return hold_lock_file_for_update_timeout(
870 lk, path, LOCK_NO_DEREF,
871 get_files_ref_lock_timeout_ms()) < 0 ? -1 : 0;
872 }
873
874 /*
875 * Locks a ref returning the lock on success and NULL on failure.
876 * On failure errno is set to something meaningful.
877 */
878 static struct ref_lock *lock_ref_oid_basic(struct files_ref_store *refs,
879 const char *refname,
880 const struct object_id *old_oid,
881 const struct string_list *extras,
882 const struct string_list *skip,
883 unsigned int flags, int *type,
884 struct strbuf *err)
885 {
886 struct strbuf ref_file = STRBUF_INIT;
887 struct ref_lock *lock;
888 int last_errno = 0;
889 int mustexist = (old_oid && !is_null_oid(old_oid));
890 int resolve_flags = RESOLVE_REF_NO_RECURSE;
891 int resolved;
892
893 files_assert_main_repository(refs, "lock_ref_oid_basic");
894 assert(err);
895
896 lock = xcalloc(1, sizeof(struct ref_lock));
897
898 if (mustexist)
899 resolve_flags |= RESOLVE_REF_READING;
900 if (flags & REF_DELETING)
901 resolve_flags |= RESOLVE_REF_ALLOW_BAD_NAME;
902
903 files_ref_path(refs, &ref_file, refname);
904 resolved = !!refs_resolve_ref_unsafe(&refs->base,
905 refname, resolve_flags,
906 &lock->old_oid, type);
907 if (!resolved && errno == EISDIR) {
908 /*
909 * we are trying to lock foo but we used to
910 * have foo/bar which now does not exist;
911 * it is normal for the empty directory 'foo'
912 * to remain.
913 */
914 if (remove_empty_directories(&ref_file)) {
915 last_errno = errno;
916 if (!refs_verify_refname_available(
917 &refs->base,
918 refname, extras, skip, err))
919 strbuf_addf(err, "there are still refs under '%s'",
920 refname);
921 goto error_return;
922 }
923 resolved = !!refs_resolve_ref_unsafe(&refs->base,
924 refname, resolve_flags,
925 &lock->old_oid, type);
926 }
927 if (!resolved) {
928 last_errno = errno;
929 if (last_errno != ENOTDIR ||
930 !refs_verify_refname_available(&refs->base, refname,
931 extras, skip, err))
932 strbuf_addf(err, "unable to resolve reference '%s': %s",
933 refname, strerror(last_errno));
934
935 goto error_return;
936 }
937
938 /*
939 * If the ref did not exist and we are creating it, make sure
940 * there is no existing packed ref whose name begins with our
941 * refname, nor a packed ref whose name is a proper prefix of
942 * our refname.
943 */
944 if (is_null_oid(&lock->old_oid) &&
945 refs_verify_refname_available(refs->packed_ref_store, refname,
946 extras, skip, err)) {
947 last_errno = ENOTDIR;
948 goto error_return;
949 }
950
951 lock->ref_name = xstrdup(refname);
952
953 if (raceproof_create_file(ref_file.buf, create_reflock, &lock->lk)) {
954 last_errno = errno;
955 unable_to_lock_message(ref_file.buf, errno, err);
956 goto error_return;
957 }
958
959 if (verify_lock(&refs->base, lock, old_oid, mustexist, err)) {
960 last_errno = errno;
961 goto error_return;
962 }
963 goto out;
964
965 error_return:
966 unlock_ref(lock);
967 lock = NULL;
968
969 out:
970 strbuf_release(&ref_file);
971 errno = last_errno;
972 return lock;
973 }
974
975 struct ref_to_prune {
976 struct ref_to_prune *next;
977 struct object_id oid;
978 char name[FLEX_ARRAY];
979 };
980
981 enum {
982 REMOVE_EMPTY_PARENTS_REF = 0x01,
983 REMOVE_EMPTY_PARENTS_REFLOG = 0x02
984 };
985
986 /*
987 * Remove empty parent directories associated with the specified
988 * reference and/or its reflog, but spare [logs/]refs/ and immediate
989 * subdirs. flags is a combination of REMOVE_EMPTY_PARENTS_REF and/or
990 * REMOVE_EMPTY_PARENTS_REFLOG.
991 */
992 static void try_remove_empty_parents(struct files_ref_store *refs,
993 const char *refname,
994 unsigned int flags)
995 {
996 struct strbuf buf = STRBUF_INIT;
997 struct strbuf sb = STRBUF_INIT;
998 char *p, *q;
999 int i;
1000
1001 strbuf_addstr(&buf, refname);
1002 p = buf.buf;
1003 for (i = 0; i < 2; i++) { /* refs/{heads,tags,...}/ */
1004 while (*p && *p != '/')
1005 p++;
1006 /* tolerate duplicate slashes; see check_refname_format() */
1007 while (*p == '/')
1008 p++;
1009 }
1010 q = buf.buf + buf.len;
1011 while (flags & (REMOVE_EMPTY_PARENTS_REF | REMOVE_EMPTY_PARENTS_REFLOG)) {
1012 while (q > p && *q != '/')
1013 q--;
1014 while (q > p && *(q-1) == '/')
1015 q--;
1016 if (q == p)
1017 break;
1018 strbuf_setlen(&buf, q - buf.buf);
1019
1020 strbuf_reset(&sb);
1021 files_ref_path(refs, &sb, buf.buf);
1022 if ((flags & REMOVE_EMPTY_PARENTS_REF) && rmdir(sb.buf))
1023 flags &= ~REMOVE_EMPTY_PARENTS_REF;
1024
1025 strbuf_reset(&sb);
1026 files_reflog_path(refs, &sb, buf.buf);
1027 if ((flags & REMOVE_EMPTY_PARENTS_REFLOG) && rmdir(sb.buf))
1028 flags &= ~REMOVE_EMPTY_PARENTS_REFLOG;
1029 }
1030 strbuf_release(&buf);
1031 strbuf_release(&sb);
1032 }
1033
1034 /* make sure nobody touched the ref, and unlink */
1035 static void prune_ref(struct files_ref_store *refs, struct ref_to_prune *r)
1036 {
1037 struct ref_transaction *transaction;
1038 struct strbuf err = STRBUF_INIT;
1039 int ret = -1;
1040
1041 if (check_refname_format(r->name, 0))
1042 return;
1043
1044 transaction = ref_store_transaction_begin(&refs->base, &err);
1045 if (!transaction)
1046 goto cleanup;
1047 ref_transaction_add_update(
1048 transaction, r->name,
1049 REF_NO_DEREF | REF_HAVE_NEW | REF_HAVE_OLD | REF_IS_PRUNING,
1050 &null_oid, &r->oid, NULL);
1051 if (ref_transaction_commit(transaction, &err))
1052 goto cleanup;
1053
1054 ret = 0;
1055
1056 cleanup:
1057 if (ret)
1058 error("%s", err.buf);
1059 strbuf_release(&err);
1060 ref_transaction_free(transaction);
1061 return;
1062 }
1063
1064 /*
1065 * Prune the loose versions of the references in the linked list
1066 * `*refs_to_prune`, freeing the entries in the list as we go.
1067 */
1068 static void prune_refs(struct files_ref_store *refs, struct ref_to_prune **refs_to_prune)
1069 {
1070 while (*refs_to_prune) {
1071 struct ref_to_prune *r = *refs_to_prune;
1072 *refs_to_prune = r->next;
1073 prune_ref(refs, r);
1074 free(r);
1075 }
1076 }
1077
1078 /*
1079 * Return true if the specified reference should be packed.
1080 */
1081 static int should_pack_ref(const char *refname,
1082 const struct object_id *oid, unsigned int ref_flags,
1083 unsigned int pack_flags)
1084 {
1085 /* Do not pack per-worktree refs: */
1086 if (ref_type(refname) != REF_TYPE_NORMAL)
1087 return 0;
1088
1089 /* Do not pack non-tags unless PACK_REFS_ALL is set: */
1090 if (!(pack_flags & PACK_REFS_ALL) && !starts_with(refname, "refs/tags/"))
1091 return 0;
1092
1093 /* Do not pack symbolic refs: */
1094 if (ref_flags & REF_ISSYMREF)
1095 return 0;
1096
1097 /* Do not pack broken refs: */
1098 if (!ref_resolves_to_object(refname, oid, ref_flags))
1099 return 0;
1100
1101 return 1;
1102 }
1103
1104 static int files_pack_refs(struct ref_store *ref_store, unsigned int flags)
1105 {
1106 struct files_ref_store *refs =
1107 files_downcast(ref_store, REF_STORE_WRITE | REF_STORE_ODB,
1108 "pack_refs");
1109 struct ref_iterator *iter;
1110 int ok;
1111 struct ref_to_prune *refs_to_prune = NULL;
1112 struct strbuf err = STRBUF_INIT;
1113 struct ref_transaction *transaction;
1114
1115 transaction = ref_store_transaction_begin(refs->packed_ref_store, &err);
1116 if (!transaction)
1117 return -1;
1118
1119 packed_refs_lock(refs->packed_ref_store, LOCK_DIE_ON_ERROR, &err);
1120
1121 iter = cache_ref_iterator_begin(get_loose_ref_cache(refs), NULL, 0);
1122 while ((ok = ref_iterator_advance(iter)) == ITER_OK) {
1123 /*
1124 * If the loose reference can be packed, add an entry
1125 * in the packed ref cache. If the reference should be
1126 * pruned, also add it to refs_to_prune.
1127 */
1128 if (!should_pack_ref(iter->refname, iter->oid, iter->flags,
1129 flags))
1130 continue;
1131
1132 /*
1133 * Add a reference creation for this reference to the
1134 * packed-refs transaction:
1135 */
1136 if (ref_transaction_update(transaction, iter->refname,
1137 iter->oid, NULL,
1138 REF_NO_DEREF, NULL, &err))
1139 die("failure preparing to create packed reference %s: %s",
1140 iter->refname, err.buf);
1141
1142 /* Schedule the loose reference for pruning if requested. */
1143 if ((flags & PACK_REFS_PRUNE)) {
1144 struct ref_to_prune *n;
1145 FLEX_ALLOC_STR(n, name, iter->refname);
1146 oidcpy(&n->oid, iter->oid);
1147 n->next = refs_to_prune;
1148 refs_to_prune = n;
1149 }
1150 }
1151 if (ok != ITER_DONE)
1152 die("error while iterating over references");
1153
1154 if (ref_transaction_commit(transaction, &err))
1155 die("unable to write new packed-refs: %s", err.buf);
1156
1157 ref_transaction_free(transaction);
1158
1159 packed_refs_unlock(refs->packed_ref_store);
1160
1161 prune_refs(refs, &refs_to_prune);
1162 strbuf_release(&err);
1163 return 0;
1164 }
1165
1166 static int files_delete_refs(struct ref_store *ref_store, const char *msg,
1167 struct string_list *refnames, unsigned int flags)
1168 {
1169 struct files_ref_store *refs =
1170 files_downcast(ref_store, REF_STORE_WRITE, "delete_refs");
1171 struct strbuf err = STRBUF_INIT;
1172 int i, result = 0;
1173
1174 if (!refnames->nr)
1175 return 0;
1176
1177 if (packed_refs_lock(refs->packed_ref_store, 0, &err))
1178 goto error;
1179
1180 if (refs_delete_refs(refs->packed_ref_store, msg, refnames, flags)) {
1181 packed_refs_unlock(refs->packed_ref_store);
1182 goto error;
1183 }
1184
1185 packed_refs_unlock(refs->packed_ref_store);
1186
1187 for (i = 0; i < refnames->nr; i++) {
1188 const char *refname = refnames->items[i].string;
1189
1190 if (refs_delete_ref(&refs->base, msg, refname, NULL, flags))
1191 result |= error(_("could not remove reference %s"), refname);
1192 }
1193
1194 strbuf_release(&err);
1195 return result;
1196
1197 error:
1198 /*
1199 * If we failed to rewrite the packed-refs file, then it is
1200 * unsafe to try to remove loose refs, because doing so might
1201 * expose an obsolete packed value for a reference that might
1202 * even point at an object that has been garbage collected.
1203 */
1204 if (refnames->nr == 1)
1205 error(_("could not delete reference %s: %s"),
1206 refnames->items[0].string, err.buf);
1207 else
1208 error(_("could not delete references: %s"), err.buf);
1209
1210 strbuf_release(&err);
1211 return -1;
1212 }
1213
1214 /*
1215 * People using contrib's git-new-workdir have .git/logs/refs ->
1216 * /some/other/path/.git/logs/refs, and that may live on another device.
1217 *
1218 * IOW, to avoid cross device rename errors, the temporary renamed log must
1219 * live into logs/refs.
1220 */
1221 #define TMP_RENAMED_LOG "refs/.tmp-renamed-log"
1222
1223 struct rename_cb {
1224 const char *tmp_renamed_log;
1225 int true_errno;
1226 };
1227
1228 static int rename_tmp_log_callback(const char *path, void *cb_data)
1229 {
1230 struct rename_cb *cb = cb_data;
1231
1232 if (rename(cb->tmp_renamed_log, path)) {
1233 /*
1234 * rename(a, b) when b is an existing directory ought
1235 * to result in ISDIR, but Solaris 5.8 gives ENOTDIR.
1236 * Sheesh. Record the true errno for error reporting,
1237 * but report EISDIR to raceproof_create_file() so
1238 * that it knows to retry.
1239 */
1240 cb->true_errno = errno;
1241 if (errno == ENOTDIR)
1242 errno = EISDIR;
1243 return -1;
1244 } else {
1245 return 0;
1246 }
1247 }
1248
1249 static int rename_tmp_log(struct files_ref_store *refs, const char *newrefname)
1250 {
1251 struct strbuf path = STRBUF_INIT;
1252 struct strbuf tmp = STRBUF_INIT;
1253 struct rename_cb cb;
1254 int ret;
1255
1256 files_reflog_path(refs, &path, newrefname);
1257 files_reflog_path(refs, &tmp, TMP_RENAMED_LOG);
1258 cb.tmp_renamed_log = tmp.buf;
1259 ret = raceproof_create_file(path.buf, rename_tmp_log_callback, &cb);
1260 if (ret) {
1261 if (errno == EISDIR)
1262 error("directory not empty: %s", path.buf);
1263 else
1264 error("unable to move logfile %s to %s: %s",
1265 tmp.buf, path.buf,
1266 strerror(cb.true_errno));
1267 }
1268
1269 strbuf_release(&path);
1270 strbuf_release(&tmp);
1271 return ret;
1272 }
1273
1274 static int write_ref_to_lockfile(struct ref_lock *lock,
1275 const struct object_id *oid, struct strbuf *err);
1276 static int commit_ref_update(struct files_ref_store *refs,
1277 struct ref_lock *lock,
1278 const struct object_id *oid, const char *logmsg,
1279 struct strbuf *err);
1280
1281 static int files_copy_or_rename_ref(struct ref_store *ref_store,
1282 const char *oldrefname, const char *newrefname,
1283 const char *logmsg, int copy)
1284 {
1285 struct files_ref_store *refs =
1286 files_downcast(ref_store, REF_STORE_WRITE, "rename_ref");
1287 struct object_id oid, orig_oid;
1288 int flag = 0, logmoved = 0;
1289 struct ref_lock *lock;
1290 struct stat loginfo;
1291 struct strbuf sb_oldref = STRBUF_INIT;
1292 struct strbuf sb_newref = STRBUF_INIT;
1293 struct strbuf tmp_renamed_log = STRBUF_INIT;
1294 int log, ret;
1295 struct strbuf err = STRBUF_INIT;
1296
1297 files_reflog_path(refs, &sb_oldref, oldrefname);
1298 files_reflog_path(refs, &sb_newref, newrefname);
1299 files_reflog_path(refs, &tmp_renamed_log, TMP_RENAMED_LOG);
1300
1301 log = !lstat(sb_oldref.buf, &loginfo);
1302 if (log && S_ISLNK(loginfo.st_mode)) {
1303 ret = error("reflog for %s is a symlink", oldrefname);
1304 goto out;
1305 }
1306
1307 if (!refs_resolve_ref_unsafe(&refs->base, oldrefname,
1308 RESOLVE_REF_READING | RESOLVE_REF_NO_RECURSE,
1309 &orig_oid, &flag)) {
1310 ret = error("refname %s not found", oldrefname);
1311 goto out;
1312 }
1313
1314 if (flag & REF_ISSYMREF) {
1315 if (copy)
1316 ret = error("refname %s is a symbolic ref, copying it is not supported",
1317 oldrefname);
1318 else
1319 ret = error("refname %s is a symbolic ref, renaming it is not supported",
1320 oldrefname);
1321 goto out;
1322 }
1323 if (!refs_rename_ref_available(&refs->base, oldrefname, newrefname)) {
1324 ret = 1;
1325 goto out;
1326 }
1327
1328 if (!copy && log && rename(sb_oldref.buf, tmp_renamed_log.buf)) {
1329 ret = error("unable to move logfile logs/%s to logs/"TMP_RENAMED_LOG": %s",
1330 oldrefname, strerror(errno));
1331 goto out;
1332 }
1333
1334 if (copy && log && copy_file(tmp_renamed_log.buf, sb_oldref.buf, 0644)) {
1335 ret = error("unable to copy logfile logs/%s to logs/"TMP_RENAMED_LOG": %s",
1336 oldrefname, strerror(errno));
1337 goto out;
1338 }
1339
1340 if (!copy && refs_delete_ref(&refs->base, logmsg, oldrefname,
1341 &orig_oid, REF_NO_DEREF)) {
1342 error("unable to delete old %s", oldrefname);
1343 goto rollback;
1344 }
1345
1346 /*
1347 * Since we are doing a shallow lookup, oid is not the
1348 * correct value to pass to delete_ref as old_oid. But that
1349 * doesn't matter, because an old_oid check wouldn't add to
1350 * the safety anyway; we want to delete the reference whatever
1351 * its current value.
1352 */
1353 if (!copy && !refs_read_ref_full(&refs->base, newrefname,
1354 RESOLVE_REF_READING | RESOLVE_REF_NO_RECURSE,
1355 &oid, NULL) &&
1356 refs_delete_ref(&refs->base, NULL, newrefname,
1357 NULL, REF_NO_DEREF)) {
1358 if (errno == EISDIR) {
1359 struct strbuf path = STRBUF_INIT;
1360 int result;
1361
1362 files_ref_path(refs, &path, newrefname);
1363 result = remove_empty_directories(&path);
1364 strbuf_release(&path);
1365
1366 if (result) {
1367 error("Directory not empty: %s", newrefname);
1368 goto rollback;
1369 }
1370 } else {
1371 error("unable to delete existing %s", newrefname);
1372 goto rollback;
1373 }
1374 }
1375
1376 if (log && rename_tmp_log(refs, newrefname))
1377 goto rollback;
1378
1379 logmoved = log;
1380
1381 lock = lock_ref_oid_basic(refs, newrefname, NULL, NULL, NULL,
1382 REF_NO_DEREF, NULL, &err);
1383 if (!lock) {
1384 if (copy)
1385 error("unable to copy '%s' to '%s': %s", oldrefname, newrefname, err.buf);
1386 else
1387 error("unable to rename '%s' to '%s': %s", oldrefname, newrefname, err.buf);
1388 strbuf_release(&err);
1389 goto rollback;
1390 }
1391 oidcpy(&lock->old_oid, &orig_oid);
1392
1393 if (write_ref_to_lockfile(lock, &orig_oid, &err) ||
1394 commit_ref_update(refs, lock, &orig_oid, logmsg, &err)) {
1395 error("unable to write current sha1 into %s: %s", newrefname, err.buf);
1396 strbuf_release(&err);
1397 goto rollback;
1398 }
1399
1400 ret = 0;
1401 goto out;
1402
1403 rollback:
1404 lock = lock_ref_oid_basic(refs, oldrefname, NULL, NULL, NULL,
1405 REF_NO_DEREF, NULL, &err);
1406 if (!lock) {
1407 error("unable to lock %s for rollback: %s", oldrefname, err.buf);
1408 strbuf_release(&err);
1409 goto rollbacklog;
1410 }
1411
1412 flag = log_all_ref_updates;
1413 log_all_ref_updates = LOG_REFS_NONE;
1414 if (write_ref_to_lockfile(lock, &orig_oid, &err) ||
1415 commit_ref_update(refs, lock, &orig_oid, NULL, &err)) {
1416 error("unable to write current sha1 into %s: %s", oldrefname, err.buf);
1417 strbuf_release(&err);
1418 }
1419 log_all_ref_updates = flag;
1420
1421 rollbacklog:
1422 if (logmoved && rename(sb_newref.buf, sb_oldref.buf))
1423 error("unable to restore logfile %s from %s: %s",
1424 oldrefname, newrefname, strerror(errno));
1425 if (!logmoved && log &&
1426 rename(tmp_renamed_log.buf, sb_oldref.buf))
1427 error("unable to restore logfile %s from logs/"TMP_RENAMED_LOG": %s",
1428 oldrefname, strerror(errno));
1429 ret = 1;
1430 out:
1431 strbuf_release(&sb_newref);
1432 strbuf_release(&sb_oldref);
1433 strbuf_release(&tmp_renamed_log);
1434
1435 return ret;
1436 }
1437
1438 static int files_rename_ref(struct ref_store *ref_store,
1439 const char *oldrefname, const char *newrefname,
1440 const char *logmsg)
1441 {
1442 return files_copy_or_rename_ref(ref_store, oldrefname,
1443 newrefname, logmsg, 0);
1444 }
1445
1446 static int files_copy_ref(struct ref_store *ref_store,
1447 const char *oldrefname, const char *newrefname,
1448 const char *logmsg)
1449 {
1450 return files_copy_or_rename_ref(ref_store, oldrefname,
1451 newrefname, logmsg, 1);
1452 }
1453
1454 static int close_ref_gently(struct ref_lock *lock)
1455 {
1456 if (close_lock_file_gently(&lock->lk))
1457 return -1;
1458 return 0;
1459 }
1460
1461 static int commit_ref(struct ref_lock *lock)
1462 {
1463 char *path = get_locked_file_path(&lock->lk);
1464 struct stat st;
1465
1466 if (!lstat(path, &st) && S_ISDIR(st.st_mode)) {
1467 /*
1468 * There is a directory at the path we want to rename
1469 * the lockfile to. Hopefully it is empty; try to
1470 * delete it.
1471 */
1472 size_t len = strlen(path);
1473 struct strbuf sb_path = STRBUF_INIT;
1474
1475 strbuf_attach(&sb_path, path, len, len);
1476
1477 /*
1478 * If this fails, commit_lock_file() will also fail
1479 * and will report the problem.
1480 */
1481 remove_empty_directories(&sb_path);
1482 strbuf_release(&sb_path);
1483 } else {
1484 free(path);
1485 }
1486
1487 if (commit_lock_file(&lock->lk))
1488 return -1;
1489 return 0;
1490 }
1491
1492 static int open_or_create_logfile(const char *path, void *cb)
1493 {
1494 int *fd = cb;
1495
1496 *fd = open(path, O_APPEND | O_WRONLY | O_CREAT, 0666);
1497 return (*fd < 0) ? -1 : 0;
1498 }
1499
1500 /*
1501 * Create a reflog for a ref. If force_create = 0, only create the
1502 * reflog for certain refs (those for which should_autocreate_reflog
1503 * returns non-zero). Otherwise, create it regardless of the reference
1504 * name. If the logfile already existed or was created, return 0 and
1505 * set *logfd to the file descriptor opened for appending to the file.
1506 * If no logfile exists and we decided not to create one, return 0 and
1507 * set *logfd to -1. On failure, fill in *err, set *logfd to -1, and
1508 * return -1.
1509 */
1510 static int log_ref_setup(struct files_ref_store *refs,
1511 const char *refname, int force_create,
1512 int *logfd, struct strbuf *err)
1513 {
1514 struct strbuf logfile_sb = STRBUF_INIT;
1515 char *logfile;
1516
1517 files_reflog_path(refs, &logfile_sb, refname);
1518 logfile = strbuf_detach(&logfile_sb, NULL);
1519
1520 if (force_create || should_autocreate_reflog(refname)) {
1521 if (raceproof_create_file(logfile, open_or_create_logfile, logfd)) {
1522 if (errno == ENOENT)
1523 strbuf_addf(err, "unable to create directory for '%s': "
1524 "%s", logfile, strerror(errno));
1525 else if (errno == EISDIR)
1526 strbuf_addf(err, "there are still logs under '%s'",
1527 logfile);
1528 else
1529 strbuf_addf(err, "unable to append to '%s': %s",
1530 logfile, strerror(errno));
1531
1532 goto error;
1533 }
1534 } else {
1535 *logfd = open(logfile, O_APPEND | O_WRONLY, 0666);
1536 if (*logfd < 0) {
1537 if (errno == ENOENT || errno == EISDIR) {
1538 /*
1539 * The logfile doesn't already exist,
1540 * but that is not an error; it only
1541 * means that we won't write log
1542 * entries to it.
1543 */
1544 ;
1545 } else {
1546 strbuf_addf(err, "unable to append to '%s': %s",
1547 logfile, strerror(errno));
1548 goto error;
1549 }
1550 }
1551 }
1552
1553 if (*logfd >= 0)
1554 adjust_shared_perm(logfile);
1555
1556 free(logfile);
1557 return 0;
1558
1559 error:
1560 free(logfile);
1561 return -1;
1562 }
1563
1564 static int files_create_reflog(struct ref_store *ref_store,
1565 const char *refname, int force_create,
1566 struct strbuf *err)
1567 {
1568 struct files_ref_store *refs =
1569 files_downcast(ref_store, REF_STORE_WRITE, "create_reflog");
1570 int fd;
1571
1572 if (log_ref_setup(refs, refname, force_create, &fd, err))
1573 return -1;
1574
1575 if (fd >= 0)
1576 close(fd);
1577
1578 return 0;
1579 }
1580
1581 static int log_ref_write_fd(int fd, const struct object_id *old_oid,
1582 const struct object_id *new_oid,
1583 const char *committer, const char *msg)
1584 {
1585 struct strbuf sb = STRBUF_INIT;
1586 int ret = 0;
1587
1588 strbuf_addf(&sb, "%s %s %s", oid_to_hex(old_oid), oid_to_hex(new_oid), committer);
1589 if (msg && *msg)
1590 copy_reflog_msg(&sb, msg);
1591 strbuf_addch(&sb, '\n');
1592 if (write_in_full(fd, sb.buf, sb.len) < 0)
1593 ret = -1;
1594 strbuf_release(&sb);
1595 return ret;
1596 }
1597
1598 static int files_log_ref_write(struct files_ref_store *refs,
1599 const char *refname, const struct object_id *old_oid,
1600 const struct object_id *new_oid, const char *msg,
1601 int flags, struct strbuf *err)
1602 {
1603 int logfd, result;
1604
1605 if (log_all_ref_updates == LOG_REFS_UNSET)
1606 log_all_ref_updates = is_bare_repository() ? LOG_REFS_NONE : LOG_REFS_NORMAL;
1607
1608 result = log_ref_setup(refs, refname,
1609 flags & REF_FORCE_CREATE_REFLOG,
1610 &logfd, err);
1611
1612 if (result)
1613 return result;
1614
1615 if (logfd < 0)
1616 return 0;
1617 result = log_ref_write_fd(logfd, old_oid, new_oid,
1618 git_committer_info(0), msg);
1619 if (result) {
1620 struct strbuf sb = STRBUF_INIT;
1621 int save_errno = errno;
1622
1623 files_reflog_path(refs, &sb, refname);
1624 strbuf_addf(err, "unable to append to '%s': %s",
1625 sb.buf, strerror(save_errno));
1626 strbuf_release(&sb);
1627 close(logfd);
1628 return -1;
1629 }
1630 if (close(logfd)) {
1631 struct strbuf sb = STRBUF_INIT;
1632 int save_errno = errno;
1633
1634 files_reflog_path(refs, &sb, refname);
1635 strbuf_addf(err, "unable to append to '%s': %s",
1636 sb.buf, strerror(save_errno));
1637 strbuf_release(&sb);
1638 return -1;
1639 }
1640 return 0;
1641 }
1642
1643 /*
1644 * Write oid into the open lockfile, then close the lockfile. On
1645 * errors, rollback the lockfile, fill in *err and return -1.
1646 */
1647 static int write_ref_to_lockfile(struct ref_lock *lock,
1648 const struct object_id *oid, struct strbuf *err)
1649 {
1650 static char term = '\n';
1651 struct object *o;
1652 int fd;
1653
1654 o = parse_object(oid);
1655 if (!o) {
1656 strbuf_addf(err,
1657 "trying to write ref '%s' with nonexistent object %s",
1658 lock->ref_name, oid_to_hex(oid));
1659 unlock_ref(lock);
1660 return -1;
1661 }
1662 if (o->type != OBJ_COMMIT && is_branch(lock->ref_name)) {
1663 strbuf_addf(err,
1664 "trying to write non-commit object %s to branch '%s'",
1665 oid_to_hex(oid), lock->ref_name);
1666 unlock_ref(lock);
1667 return -1;
1668 }
1669 fd = get_lock_file_fd(&lock->lk);
1670 if (write_in_full(fd, oid_to_hex(oid), the_hash_algo->hexsz) < 0 ||
1671 write_in_full(fd, &term, 1) < 0 ||
1672 close_ref_gently(lock) < 0) {
1673 strbuf_addf(err,
1674 "couldn't write '%s'", get_lock_file_path(&lock->lk));
1675 unlock_ref(lock);
1676 return -1;
1677 }
1678 return 0;
1679 }
1680
1681 /*
1682 * Commit a change to a loose reference that has already been written
1683 * to the loose reference lockfile. Also update the reflogs if
1684 * necessary, using the specified lockmsg (which can be NULL).
1685 */
1686 static int commit_ref_update(struct files_ref_store *refs,
1687 struct ref_lock *lock,
1688 const struct object_id *oid, const char *logmsg,
1689 struct strbuf *err)
1690 {
1691 files_assert_main_repository(refs, "commit_ref_update");
1692
1693 clear_loose_ref_cache(refs);
1694 if (files_log_ref_write(refs, lock->ref_name,
1695 &lock->old_oid, oid,
1696 logmsg, 0, err)) {
1697 char *old_msg = strbuf_detach(err, NULL);
1698 strbuf_addf(err, "cannot update the ref '%s': %s",
1699 lock->ref_name, old_msg);
1700 free(old_msg);
1701 unlock_ref(lock);
1702 return -1;
1703 }
1704
1705 if (strcmp(lock->ref_name, "HEAD") != 0) {
1706 /*
1707 * Special hack: If a branch is updated directly and HEAD
1708 * points to it (may happen on the remote side of a push
1709 * for example) then logically the HEAD reflog should be
1710 * updated too.
1711 * A generic solution implies reverse symref information,
1712 * but finding all symrefs pointing to the given branch
1713 * would be rather costly for this rare event (the direct
1714 * update of a branch) to be worth it. So let's cheat and
1715 * check with HEAD only which should cover 99% of all usage
1716 * scenarios (even 100% of the default ones).
1717 */
1718 int head_flag;
1719 const char *head_ref;
1720
1721 head_ref = refs_resolve_ref_unsafe(&refs->base, "HEAD",
1722 RESOLVE_REF_READING,
1723 NULL, &head_flag);
1724 if (head_ref && (head_flag & REF_ISSYMREF) &&
1725 !strcmp(head_ref, lock->ref_name)) {
1726 struct strbuf log_err = STRBUF_INIT;
1727 if (files_log_ref_write(refs, "HEAD",
1728 &lock->old_oid, oid,
1729 logmsg, 0, &log_err)) {
1730 error("%s", log_err.buf);
1731 strbuf_release(&log_err);
1732 }
1733 }
1734 }
1735
1736 if (commit_ref(lock)) {
1737 strbuf_addf(err, "couldn't set '%s'", lock->ref_name);
1738 unlock_ref(lock);
1739 return -1;
1740 }
1741
1742 unlock_ref(lock);
1743 return 0;
1744 }
1745
1746 static int create_ref_symlink(struct ref_lock *lock, const char *target)
1747 {
1748 int ret = -1;
1749 #ifndef NO_SYMLINK_HEAD
1750 char *ref_path = get_locked_file_path(&lock->lk);
1751 unlink(ref_path);
1752 ret = symlink(target, ref_path);
1753 free(ref_path);
1754
1755 if (ret)
1756 fprintf(stderr, "no symlink - falling back to symbolic ref\n");
1757 #endif
1758 return ret;
1759 }
1760
1761 static void update_symref_reflog(struct files_ref_store *refs,
1762 struct ref_lock *lock, const char *refname,
1763 const char *target, const char *logmsg)
1764 {
1765 struct strbuf err = STRBUF_INIT;
1766 struct object_id new_oid;
1767 if (logmsg &&
1768 !refs_read_ref_full(&refs->base, target,
1769 RESOLVE_REF_READING, &new_oid, NULL) &&
1770 files_log_ref_write(refs, refname, &lock->old_oid,
1771 &new_oid, logmsg, 0, &err)) {
1772 error("%s", err.buf);
1773 strbuf_release(&err);
1774 }
1775 }
1776
1777 static int create_symref_locked(struct files_ref_store *refs,
1778 struct ref_lock *lock, const char *refname,
1779 const char *target, const char *logmsg)
1780 {
1781 if (prefer_symlink_refs && !create_ref_symlink(lock, target)) {
1782 update_symref_reflog(refs, lock, refname, target, logmsg);
1783 return 0;
1784 }
1785
1786 if (!fdopen_lock_file(&lock->lk, "w"))
1787 return error("unable to fdopen %s: %s",
1788 lock->lk.tempfile->filename.buf, strerror(errno));
1789
1790 update_symref_reflog(refs, lock, refname, target, logmsg);
1791
1792 /* no error check; commit_ref will check ferror */
1793 fprintf(lock->lk.tempfile->fp, "ref: %s\n", target);
1794 if (commit_ref(lock) < 0)
1795 return error("unable to write symref for %s: %s", refname,
1796 strerror(errno));
1797 return 0;
1798 }
1799
1800 static int files_create_symref(struct ref_store *ref_store,
1801 const char *refname, const char *target,
1802 const char *logmsg)
1803 {
1804 struct files_ref_store *refs =
1805 files_downcast(ref_store, REF_STORE_WRITE, "create_symref");
1806 struct strbuf err = STRBUF_INIT;
1807 struct ref_lock *lock;
1808 int ret;
1809
1810 lock = lock_ref_oid_basic(refs, refname, NULL,
1811 NULL, NULL, REF_NO_DEREF, NULL,
1812 &err);
1813 if (!lock) {
1814 error("%s", err.buf);
1815 strbuf_release(&err);
1816 return -1;
1817 }
1818
1819 ret = create_symref_locked(refs, lock, refname, target, logmsg);
1820 unlock_ref(lock);
1821 return ret;
1822 }
1823
1824 static int files_reflog_exists(struct ref_store *ref_store,
1825 const char *refname)
1826 {
1827 struct files_ref_store *refs =
1828 files_downcast(ref_store, REF_STORE_READ, "reflog_exists");
1829 struct strbuf sb = STRBUF_INIT;
1830 struct stat st;
1831 int ret;
1832
1833 files_reflog_path(refs, &sb, refname);
1834 ret = !lstat(sb.buf, &st) && S_ISREG(st.st_mode);
1835 strbuf_release(&sb);
1836 return ret;
1837 }
1838
1839 static int files_delete_reflog(struct ref_store *ref_store,
1840 const char *refname)
1841 {
1842 struct files_ref_store *refs =
1843 files_downcast(ref_store, REF_STORE_WRITE, "delete_reflog");
1844 struct strbuf sb = STRBUF_INIT;
1845 int ret;
1846
1847 files_reflog_path(refs, &sb, refname);
1848 ret = remove_path(sb.buf);
1849 strbuf_release(&sb);
1850 return ret;
1851 }
1852
1853 static int show_one_reflog_ent(struct strbuf *sb, each_reflog_ent_fn fn, void *cb_data)
1854 {
1855 struct object_id ooid, noid;
1856 char *email_end, *message;
1857 timestamp_t timestamp;
1858 int tz;
1859 const char *p = sb->buf;
1860
1861 /* old SP new SP name <email> SP time TAB msg LF */
1862 if (!sb->len || sb->buf[sb->len - 1] != '\n' ||
1863 parse_oid_hex(p, &ooid, &p) || *p++ != ' ' ||
1864 parse_oid_hex(p, &noid, &p) || *p++ != ' ' ||
1865 !(email_end = strchr(p, '>')) ||
1866 email_end[1] != ' ' ||
1867 !(timestamp = parse_timestamp(email_end + 2, &message, 10)) ||
1868 !message || message[0] != ' ' ||
1869 (message[1] != '+' && message[1] != '-') ||
1870 !isdigit(message[2]) || !isdigit(message[3]) ||
1871 !isdigit(message[4]) || !isdigit(message[5]))
1872 return 0; /* corrupt? */
1873 email_end[1] = '\0';
1874 tz = strtol(message + 1, NULL, 10);
1875 if (message[6] != '\t')
1876 message += 6;
1877 else
1878 message += 7;
1879 return fn(&ooid, &noid, p, timestamp, tz, message, cb_data);
1880 }
1881
1882 static char *find_beginning_of_line(char *bob, char *scan)
1883 {
1884 while (bob < scan && *(--scan) != '\n')
1885 ; /* keep scanning backwards */
1886 /*
1887 * Return either beginning of the buffer, or LF at the end of
1888 * the previous line.
1889 */
1890 return scan;
1891 }
1892
1893 static int files_for_each_reflog_ent_reverse(struct ref_store *ref_store,
1894 const char *refname,
1895 each_reflog_ent_fn fn,
1896 void *cb_data)
1897 {
1898 struct files_ref_store *refs =
1899 files_downcast(ref_store, REF_STORE_READ,
1900 "for_each_reflog_ent_reverse");
1901 struct strbuf sb = STRBUF_INIT;
1902 FILE *logfp;
1903 long pos;
1904 int ret = 0, at_tail = 1;
1905
1906 files_reflog_path(refs, &sb, refname);
1907 logfp = fopen(sb.buf, "r");
1908 strbuf_release(&sb);
1909 if (!logfp)
1910 return -1;
1911
1912 /* Jump to the end */
1913 if (fseek(logfp, 0, SEEK_END) < 0)
1914 ret = error("cannot seek back reflog for %s: %s",
1915 refname, strerror(errno));
1916 pos = ftell(logfp);
1917 while (!ret && 0 < pos) {
1918 int cnt;
1919 size_t nread;
1920 char buf[BUFSIZ];
1921 char *endp, *scanp;
1922
1923 /* Fill next block from the end */
1924 cnt = (sizeof(buf) < pos) ? sizeof(buf) : pos;
1925 if (fseek(logfp, pos - cnt, SEEK_SET)) {
1926 ret = error("cannot seek back reflog for %s: %s",
1927 refname, strerror(errno));
1928 break;
1929 }
1930 nread = fread(buf, cnt, 1, logfp);
1931 if (nread != 1) {
1932 ret = error("cannot read %d bytes from reflog for %s: %s",
1933 cnt, refname, strerror(errno));
1934 break;
1935 }
1936 pos -= cnt;
1937
1938 scanp = endp = buf + cnt;
1939 if (at_tail && scanp[-1] == '\n')
1940 /* Looking at the final LF at the end of the file */
1941 scanp--;
1942 at_tail = 0;
1943
1944 while (buf < scanp) {
1945 /*
1946 * terminating LF of the previous line, or the beginning
1947 * of the buffer.
1948 */
1949 char *bp;
1950
1951 bp = find_beginning_of_line(buf, scanp);
1952
1953 if (*bp == '\n') {
1954 /*
1955 * The newline is the end of the previous line,
1956 * so we know we have complete line starting
1957 * at (bp + 1). Prefix it onto any prior data
1958 * we collected for the line and process it.
1959 */
1960 strbuf_splice(&sb, 0, 0, bp + 1, endp - (bp + 1));
1961 scanp = bp;
1962 endp = bp + 1;
1963 ret = show_one_reflog_ent(&sb, fn, cb_data);
1964 strbuf_reset(&sb);
1965 if (ret)
1966 break;
1967 } else if (!pos) {
1968 /*
1969 * We are at the start of the buffer, and the
1970 * start of the file; there is no previous
1971 * line, and we have everything for this one.
1972 * Process it, and we can end the loop.
1973 */
1974 strbuf_splice(&sb, 0, 0, buf, endp - buf);
1975 ret = show_one_reflog_ent(&sb, fn, cb_data);
1976 strbuf_reset(&sb);
1977 break;
1978 }
1979
1980 if (bp == buf) {
1981 /*
1982 * We are at the start of the buffer, and there
1983 * is more file to read backwards. Which means
1984 * we are in the middle of a line. Note that we
1985 * may get here even if *bp was a newline; that
1986 * just means we are at the exact end of the
1987 * previous line, rather than some spot in the
1988 * middle.
1989 *
1990 * Save away what we have to be combined with
1991 * the data from the next read.
1992 */
1993 strbuf_splice(&sb, 0, 0, buf, endp - buf);
1994 break;
1995 }
1996 }
1997
1998 }
1999 if (!ret && sb.len)
2000 BUG("reverse reflog parser had leftover data");
2001
2002 fclose(logfp);
2003 strbuf_release(&sb);
2004 return ret;
2005 }
2006
2007 static int files_for_each_reflog_ent(struct ref_store *ref_store,
2008 const char *refname,
2009 each_reflog_ent_fn fn, void *cb_data)
2010 {
2011 struct files_ref_store *refs =
2012 files_downcast(ref_store, REF_STORE_READ,
2013 "for_each_reflog_ent");
2014 FILE *logfp;
2015 struct strbuf sb = STRBUF_INIT;
2016 int ret = 0;
2017
2018 files_reflog_path(refs, &sb, refname);
2019 logfp = fopen(sb.buf, "r");
2020 strbuf_release(&sb);
2021 if (!logfp)
2022 return -1;
2023
2024 while (!ret && !strbuf_getwholeline(&sb, logfp, '\n'))
2025 ret = show_one_reflog_ent(&sb, fn, cb_data);
2026 fclose(logfp);
2027 strbuf_release(&sb);
2028 return ret;
2029 }
2030
2031 struct files_reflog_iterator {
2032 struct ref_iterator base;
2033
2034 struct ref_store *ref_store;
2035 struct dir_iterator *dir_iterator;
2036 struct object_id oid;
2037 };
2038
2039 static int files_reflog_iterator_advance(struct ref_iterator *ref_iterator)
2040 {
2041 struct files_reflog_iterator *iter =
2042 (struct files_reflog_iterator *)ref_iterator;
2043 struct dir_iterator *diter = iter->dir_iterator;
2044 int ok;
2045
2046 while ((ok = dir_iterator_advance(diter)) == ITER_OK) {
2047 int flags;
2048
2049 if (!S_ISREG(diter->st.st_mode))
2050 continue;
2051 if (diter->basename[0] == '.')
2052 continue;
2053 if (ends_with(diter->basename, ".lock"))
2054 continue;
2055
2056 if (refs_read_ref_full(iter->ref_store,
2057 diter->relative_path, 0,
2058 &iter->oid, &flags)) {
2059 error("bad ref for %s", diter->path.buf);
2060 continue;
2061 }
2062
2063 iter->base.refname = diter->relative_path;
2064 iter->base.oid = &iter->oid;
2065 iter->base.flags = flags;
2066 return ITER_OK;
2067 }
2068
2069 iter->dir_iterator = NULL;
2070 if (ref_iterator_abort(ref_iterator) == ITER_ERROR)
2071 ok = ITER_ERROR;
2072 return ok;
2073 }
2074
2075 static int files_reflog_iterator_peel(struct ref_iterator *ref_iterator,
2076 struct object_id *peeled)
2077 {
2078 BUG("ref_iterator_peel() called for reflog_iterator");
2079 }
2080
2081 static int files_reflog_iterator_abort(struct ref_iterator *ref_iterator)
2082 {
2083 struct files_reflog_iterator *iter =
2084 (struct files_reflog_iterator *)ref_iterator;
2085 int ok = ITER_DONE;
2086
2087 if (iter->dir_iterator)
2088 ok = dir_iterator_abort(iter->dir_iterator);
2089
2090 base_ref_iterator_free(ref_iterator);
2091 return ok;
2092 }
2093
2094 static struct ref_iterator_vtable files_reflog_iterator_vtable = {
2095 files_reflog_iterator_advance,
2096 files_reflog_iterator_peel,
2097 files_reflog_iterator_abort
2098 };
2099
2100 static struct ref_iterator *reflog_iterator_begin(struct ref_store *ref_store,
2101 const char *gitdir)
2102 {
2103 struct files_reflog_iterator *iter = xcalloc(1, sizeof(*iter));
2104 struct ref_iterator *ref_iterator = &iter->base;
2105 struct strbuf sb = STRBUF_INIT;
2106
2107 base_ref_iterator_init(ref_iterator, &files_reflog_iterator_vtable, 0);
2108 strbuf_addf(&sb, "%s/logs", gitdir);
2109 iter->dir_iterator = dir_iterator_begin(sb.buf);
2110 iter->ref_store = ref_store;
2111 strbuf_release(&sb);
2112
2113 return ref_iterator;
2114 }
2115
2116 static enum iterator_selection reflog_iterator_select(
2117 struct ref_iterator *iter_worktree,
2118 struct ref_iterator *iter_common,
2119 void *cb_data)
2120 {
2121 if (iter_worktree) {
2122 /*
2123 * We're a bit loose here. We probably should ignore
2124 * common refs if they are accidentally added as
2125 * per-worktree refs.
2126 */
2127 return ITER_SELECT_0;
2128 } else if (iter_common) {
2129 if (ref_type(iter_common->refname) == REF_TYPE_NORMAL)
2130 return ITER_SELECT_1;
2131
2132 /*
2133 * The main ref store may contain main worktree's
2134 * per-worktree refs, which should be ignored
2135 */
2136 return ITER_SKIP_1;
2137 } else
2138 return ITER_DONE;
2139 }
2140
2141 static struct ref_iterator *files_reflog_iterator_begin(struct ref_store *ref_store)
2142 {
2143 struct files_ref_store *refs =
2144 files_downcast(ref_store, REF_STORE_READ,
2145 "reflog_iterator_begin");
2146
2147 if (!strcmp(refs->gitdir, refs->gitcommondir)) {
2148 return reflog_iterator_begin(ref_store, refs->gitcommondir);
2149 } else {
2150 return merge_ref_iterator_begin(
2151 0,
2152 reflog_iterator_begin(ref_store, refs->gitdir),
2153 reflog_iterator_begin(ref_store, refs->gitcommondir),
2154 reflog_iterator_select, refs);
2155 }
2156 }
2157
2158 /*
2159 * If update is a direct update of head_ref (the reference pointed to
2160 * by HEAD), then add an extra REF_LOG_ONLY update for HEAD.
2161 */
2162 static int split_head_update(struct ref_update *update,
2163 struct ref_transaction *transaction,
2164 const char *head_ref,
2165 struct string_list *affected_refnames,
2166 struct strbuf *err)
2167 {
2168 struct string_list_item *item;
2169 struct ref_update *new_update;
2170
2171 if ((update->flags & REF_LOG_ONLY) ||
2172 (update->flags & REF_IS_PRUNING) ||
2173 (update->flags & REF_UPDATE_VIA_HEAD))
2174 return 0;
2175
2176 if (strcmp(update->refname, head_ref))
2177 return 0;
2178
2179 /*
2180 * First make sure that HEAD is not already in the
2181 * transaction. This check is O(lg N) in the transaction
2182 * size, but it happens at most once per transaction.
2183 */
2184 if (string_list_has_string(affected_refnames, "HEAD")) {
2185 /* An entry already existed */
2186 strbuf_addf(err,
2187 "multiple updates for 'HEAD' (including one "
2188 "via its referent '%s') are not allowed",
2189 update->refname);
2190 return TRANSACTION_NAME_CONFLICT;
2191 }
2192
2193 new_update = ref_transaction_add_update(
2194 transaction, "HEAD",
2195 update->flags | REF_LOG_ONLY | REF_NO_DEREF,
2196 &update->new_oid, &update->old_oid,
2197 update->msg);
2198
2199 /*
2200 * Add "HEAD". This insertion is O(N) in the transaction
2201 * size, but it happens at most once per transaction.
2202 * Add new_update->refname instead of a literal "HEAD".
2203 */
2204 if (strcmp(new_update->refname, "HEAD"))
2205 BUG("%s unexpectedly not 'HEAD'", new_update->refname);
2206 item = string_list_insert(affected_refnames, new_update->refname);
2207 item->util = new_update;
2208
2209 return 0;
2210 }
2211
2212 /*
2213 * update is for a symref that points at referent and doesn't have
2214 * REF_NO_DEREF set. Split it into two updates:
2215 * - The original update, but with REF_LOG_ONLY and REF_NO_DEREF set
2216 * - A new, separate update for the referent reference
2217 * Note that the new update will itself be subject to splitting when
2218 * the iteration gets to it.
2219 */
2220 static int split_symref_update(struct files_ref_store *refs,
2221 struct ref_update *update,
2222 const char *referent,
2223 struct ref_transaction *transaction,
2224 struct string_list *affected_refnames,
2225 struct strbuf *err)
2226 {
2227 struct string_list_item *item;
2228 struct ref_update *new_update;
2229 unsigned int new_flags;
2230
2231 /*
2232 * First make sure that referent is not already in the
2233 * transaction. This check is O(lg N) in the transaction
2234 * size, but it happens at most once per symref in a
2235 * transaction.
2236 */
2237 if (string_list_has_string(affected_refnames, referent)) {
2238 /* An entry already exists */
2239 strbuf_addf(err,
2240 "multiple updates for '%s' (including one "
2241 "via symref '%s') are not allowed",
2242 referent, update->refname);
2243 return TRANSACTION_NAME_CONFLICT;
2244 }
2245
2246 new_flags = update->flags;
2247 if (!strcmp(update->refname, "HEAD")) {
2248 /*
2249 * Record that the new update came via HEAD, so that
2250 * when we process it, split_head_update() doesn't try
2251 * to add another reflog update for HEAD. Note that
2252 * this bit will be propagated if the new_update
2253 * itself needs to be split.
2254 */
2255 new_flags |= REF_UPDATE_VIA_HEAD;
2256 }
2257
2258 new_update = ref_transaction_add_update(
2259 transaction, referent, new_flags,
2260 &update->new_oid, &update->old_oid,
2261 update->msg);
2262
2263 new_update->parent_update = update;
2264
2265 /*
2266 * Change the symbolic ref update to log only. Also, it
2267 * doesn't need to check its old OID value, as that will be
2268 * done when new_update is processed.
2269 */
2270 update->flags |= REF_LOG_ONLY | REF_NO_DEREF;
2271 update->flags &= ~REF_HAVE_OLD;
2272
2273 /*
2274 * Add the referent. This insertion is O(N) in the transaction
2275 * size, but it happens at most once per symref in a
2276 * transaction. Make sure to add new_update->refname, which will
2277 * be valid as long as affected_refnames is in use, and NOT
2278 * referent, which might soon be freed by our caller.
2279 */
2280 item = string_list_insert(affected_refnames, new_update->refname);
2281 if (item->util)
2282 BUG("%s unexpectedly found in affected_refnames",
2283 new_update->refname);
2284 item->util = new_update;
2285
2286 return 0;
2287 }
2288
2289 /*
2290 * Return the refname under which update was originally requested.
2291 */
2292 static const char *original_update_refname(struct ref_update *update)
2293 {
2294 while (update->parent_update)
2295 update = update->parent_update;
2296
2297 return update->refname;
2298 }
2299
2300 /*
2301 * Check whether the REF_HAVE_OLD and old_oid values stored in update
2302 * are consistent with oid, which is the reference's current value. If
2303 * everything is OK, return 0; otherwise, write an error message to
2304 * err and return -1.
2305 */
2306 static int check_old_oid(struct ref_update *update, struct object_id *oid,
2307 struct strbuf *err)
2308 {
2309 if (!(update->flags & REF_HAVE_OLD) ||
2310 !oidcmp(oid, &update->old_oid))
2311 return 0;
2312
2313 if (is_null_oid(&update->old_oid))
2314 strbuf_addf(err, "cannot lock ref '%s': "
2315 "reference already exists",
2316 original_update_refname(update));
2317 else if (is_null_oid(oid))
2318 strbuf_addf(err, "cannot lock ref '%s': "
2319 "reference is missing but expected %s",
2320 original_update_refname(update),
2321 oid_to_hex(&update->old_oid));
2322 else
2323 strbuf_addf(err, "cannot lock ref '%s': "
2324 "is at %s but expected %s",
2325 original_update_refname(update),
2326 oid_to_hex(oid),
2327 oid_to_hex(&update->old_oid));
2328
2329 return -1;
2330 }
2331
2332 /*
2333 * Prepare for carrying out update:
2334 * - Lock the reference referred to by update.
2335 * - Read the reference under lock.
2336 * - Check that its old OID value (if specified) is correct, and in
2337 * any case record it in update->lock->old_oid for later use when
2338 * writing the reflog.
2339 * - If it is a symref update without REF_NO_DEREF, split it up into a
2340 * REF_LOG_ONLY update of the symref and add a separate update for
2341 * the referent to transaction.
2342 * - If it is an update of head_ref, add a corresponding REF_LOG_ONLY
2343 * update of HEAD.
2344 */
2345 static int lock_ref_for_update(struct files_ref_store *refs,
2346 struct ref_update *update,
2347 struct ref_transaction *transaction,
2348 const char *head_ref,
2349 struct string_list *affected_refnames,
2350 struct strbuf *err)
2351 {
2352 struct strbuf referent = STRBUF_INIT;
2353 int mustexist = (update->flags & REF_HAVE_OLD) &&
2354 !is_null_oid(&update->old_oid);
2355 int ret = 0;
2356 struct ref_lock *lock;
2357
2358 files_assert_main_repository(refs, "lock_ref_for_update");
2359
2360 if ((update->flags & REF_HAVE_NEW) && is_null_oid(&update->new_oid))
2361 update->flags |= REF_DELETING;
2362
2363 if (head_ref) {
2364 ret = split_head_update(update, transaction, head_ref,
2365 affected_refnames, err);
2366 if (ret)
2367 goto out;
2368 }
2369
2370 ret = lock_raw_ref(refs, update->refname, mustexist,
2371 affected_refnames, NULL,
2372 &lock, &referent,
2373 &update->type, err);
2374 if (ret) {
2375 char *reason;
2376
2377 reason = strbuf_detach(err, NULL);
2378 strbuf_addf(err, "cannot lock ref '%s': %s",
2379 original_update_refname(update), reason);
2380 free(reason);
2381 goto out;
2382 }
2383
2384 update->backend_data = lock;
2385
2386 if (update->type & REF_ISSYMREF) {
2387 if (update->flags & REF_NO_DEREF) {
2388 /*
2389 * We won't be reading the referent as part of
2390 * the transaction, so we have to read it here
2391 * to record and possibly check old_oid:
2392 */
2393 if (refs_read_ref_full(&refs->base,
2394 referent.buf, 0,
2395 &lock->old_oid, NULL)) {
2396 if (update->flags & REF_HAVE_OLD) {
2397 strbuf_addf(err, "cannot lock ref '%s': "
2398 "error reading reference",
2399 original_update_refname(update));
2400 ret = TRANSACTION_GENERIC_ERROR;
2401 goto out;
2402 }
2403 } else if (check_old_oid(update, &lock->old_oid, err)) {
2404 ret = TRANSACTION_GENERIC_ERROR;
2405 goto out;
2406 }
2407 } else {
2408 /*
2409 * Create a new update for the reference this
2410 * symref is pointing at. Also, we will record
2411 * and verify old_oid for this update as part
2412 * of processing the split-off update, so we
2413 * don't have to do it here.
2414 */
2415 ret = split_symref_update(refs, update,
2416 referent.buf, transaction,
2417 affected_refnames, err);
2418 if (ret)
2419 goto out;
2420 }
2421 } else {
2422 struct ref_update *parent_update;
2423
2424 if (check_old_oid(update, &lock->old_oid, err)) {
2425 ret = TRANSACTION_GENERIC_ERROR;
2426 goto out;
2427 }
2428
2429 /*
2430 * If this update is happening indirectly because of a
2431 * symref update, record the old OID in the parent
2432 * update:
2433 */
2434 for (parent_update = update->parent_update;
2435 parent_update;
2436 parent_update = parent_update->parent_update) {
2437 struct ref_lock *parent_lock = parent_update->backend_data;
2438 oidcpy(&parent_lock->old_oid, &lock->old_oid);
2439 }
2440 }
2441
2442 if ((update->flags & REF_HAVE_NEW) &&
2443 !(update->flags & REF_DELETING) &&
2444 !(update->flags & REF_LOG_ONLY)) {
2445 if (!(update->type & REF_ISSYMREF) &&
2446 !oidcmp(&lock->old_oid, &update->new_oid)) {
2447 /*
2448 * The reference already has the desired
2449 * value, so we don't need to write it.
2450 */
2451 } else if (write_ref_to_lockfile(lock, &update->new_oid,
2452 err)) {
2453 char *write_err = strbuf_detach(err, NULL);
2454
2455 /*
2456 * The lock was freed upon failure of
2457 * write_ref_to_lockfile():
2458 */
2459 update->backend_data = NULL;
2460 strbuf_addf(err,
2461 "cannot update ref '%s': %s",
2462 update->refname, write_err);
2463 free(write_err);
2464 ret = TRANSACTION_GENERIC_ERROR;
2465 goto out;
2466 } else {
2467 update->flags |= REF_NEEDS_COMMIT;
2468 }
2469 }
2470 if (!(update->flags & REF_NEEDS_COMMIT)) {
2471 /*
2472 * We didn't call write_ref_to_lockfile(), so
2473 * the lockfile is still open. Close it to
2474 * free up the file descriptor:
2475 */
2476 if (close_ref_gently(lock)) {
2477 strbuf_addf(err, "couldn't close '%s.lock'",
2478 update->refname);
2479 ret = TRANSACTION_GENERIC_ERROR;
2480 goto out;
2481 }
2482 }
2483
2484 out:
2485 strbuf_release(&referent);
2486 return ret;
2487 }
2488
2489 struct files_transaction_backend_data {
2490 struct ref_transaction *packed_transaction;
2491 int packed_refs_locked;
2492 };
2493
2494 /*
2495 * Unlock any references in `transaction` that are still locked, and
2496 * mark the transaction closed.
2497 */
2498 static void files_transaction_cleanup(struct files_ref_store *refs,
2499 struct ref_transaction *transaction)
2500 {
2501 size_t i;
2502 struct files_transaction_backend_data *backend_data =
2503 transaction->backend_data;
2504 struct strbuf err = STRBUF_INIT;
2505
2506 for (i = 0; i < transaction->nr; i++) {
2507 struct ref_update *update = transaction->updates[i];
2508 struct ref_lock *lock = update->backend_data;
2509
2510 if (lock) {
2511 unlock_ref(lock);
2512 update->backend_data = NULL;
2513 }
2514 }
2515
2516 if (backend_data->packed_transaction &&
2517 ref_transaction_abort(backend_data->packed_transaction, &err)) {
2518 error("error aborting transaction: %s", err.buf);
2519 strbuf_release(&err);
2520 }
2521
2522 if (backend_data->packed_refs_locked)
2523 packed_refs_unlock(refs->packed_ref_store);
2524
2525 free(backend_data);
2526
2527 transaction->state = REF_TRANSACTION_CLOSED;
2528 }
2529
2530 static int files_transaction_prepare(struct ref_store *ref_store,
2531 struct ref_transaction *transaction,
2532 struct strbuf *err)
2533 {
2534 struct files_ref_store *refs =
2535 files_downcast(ref_store, REF_STORE_WRITE,
2536 "ref_transaction_prepare");
2537 size_t i;
2538 int ret = 0;
2539 struct string_list affected_refnames = STRING_LIST_INIT_NODUP;
2540 char *head_ref = NULL;
2541 int head_type;
2542 struct files_transaction_backend_data *backend_data;
2543 struct ref_transaction *packed_transaction = NULL;
2544
2545 assert(err);
2546
2547 if (!transaction->nr)
2548 goto cleanup;
2549
2550 backend_data = xcalloc(1, sizeof(*backend_data));
2551 transaction->backend_data = backend_data;
2552
2553 /*
2554 * Fail if a refname appears more than once in the
2555 * transaction. (If we end up splitting up any updates using
2556 * split_symref_update() or split_head_update(), those
2557 * functions will check that the new updates don't have the
2558 * same refname as any existing ones.) Also fail if any of the
2559 * updates use REF_IS_PRUNING without REF_NO_DEREF.
2560 */
2561 for (i = 0; i < transaction->nr; i++) {
2562 struct ref_update *update = transaction->updates[i];
2563 struct string_list_item *item =
2564 string_list_append(&affected_refnames, update->refname);
2565
2566 if ((update->flags & REF_IS_PRUNING) &&
2567 !(update->flags & REF_NO_DEREF))
2568 BUG("REF_IS_PRUNING set without REF_NO_DEREF");
2569
2570 /*
2571 * We store a pointer to update in item->util, but at
2572 * the moment we never use the value of this field
2573 * except to check whether it is non-NULL.
2574 */
2575 item->util = update;
2576 }
2577 string_list_sort(&affected_refnames);
2578 if (ref_update_reject_duplicates(&affected_refnames, err)) {
2579 ret = TRANSACTION_GENERIC_ERROR;
2580 goto cleanup;
2581 }
2582
2583 /*
2584 * Special hack: If a branch is updated directly and HEAD
2585 * points to it (may happen on the remote side of a push
2586 * for example) then logically the HEAD reflog should be
2587 * updated too.
2588 *
2589 * A generic solution would require reverse symref lookups,
2590 * but finding all symrefs pointing to a given branch would be
2591 * rather costly for this rare event (the direct update of a
2592 * branch) to be worth it. So let's cheat and check with HEAD
2593 * only, which should cover 99% of all usage scenarios (even
2594 * 100% of the default ones).
2595 *
2596 * So if HEAD is a symbolic reference, then record the name of
2597 * the reference that it points to. If we see an update of
2598 * head_ref within the transaction, then split_head_update()
2599 * arranges for the reflog of HEAD to be updated, too.
2600 */
2601 head_ref = refs_resolve_refdup(ref_store, "HEAD",
2602 RESOLVE_REF_NO_RECURSE,
2603 NULL, &head_type);
2604
2605 if (head_ref && !(head_type & REF_ISSYMREF)) {
2606 FREE_AND_NULL(head_ref);
2607 }
2608
2609 /*
2610 * Acquire all locks, verify old values if provided, check
2611 * that new values are valid, and write new values to the
2612 * lockfiles, ready to be activated. Only keep one lockfile
2613 * open at a time to avoid running out of file descriptors.
2614 * Note that lock_ref_for_update() might append more updates
2615 * to the transaction.
2616 */
2617 for (i = 0; i < transaction->nr; i++) {
2618 struct ref_update *update = transaction->updates[i];
2619
2620 ret = lock_ref_for_update(refs, update, transaction,
2621 head_ref, &affected_refnames, err);
2622 if (ret)
2623 goto cleanup;
2624
2625 if (update->flags & REF_DELETING &&
2626 !(update->flags & REF_LOG_ONLY) &&
2627 !(update->flags & REF_IS_PRUNING)) {
2628 /*
2629 * This reference has to be deleted from
2630 * packed-refs if it exists there.
2631 */
2632 if (!packed_transaction) {
2633 packed_transaction = ref_store_transaction_begin(
2634 refs->packed_ref_store, err);
2635 if (!packed_transaction) {
2636 ret = TRANSACTION_GENERIC_ERROR;
2637 goto cleanup;
2638 }
2639
2640 backend_data->packed_transaction =
2641 packed_transaction;
2642 }
2643
2644 ref_transaction_add_update(
2645 packed_transaction, update->refname,
2646 REF_HAVE_NEW | REF_NO_DEREF,
2647 &update->new_oid, NULL,
2648 NULL);
2649 }
2650 }
2651
2652 if (packed_transaction) {
2653 if (packed_refs_lock(refs->packed_ref_store, 0, err)) {
2654 ret = TRANSACTION_GENERIC_ERROR;
2655 goto cleanup;
2656 }
2657 backend_data->packed_refs_locked = 1;
2658
2659 if (is_packed_transaction_needed(refs->packed_ref_store,
2660 packed_transaction)) {
2661 ret = ref_transaction_prepare(packed_transaction, err);
2662 } else {
2663 /*
2664 * We can skip rewriting the `packed-refs`
2665 * file. But we do need to leave it locked, so
2666 * that somebody else doesn't pack a reference
2667 * that we are trying to delete.
2668 */
2669 if (ref_transaction_abort(packed_transaction, err)) {
2670 ret = TRANSACTION_GENERIC_ERROR;
2671 goto cleanup;
2672 }
2673 backend_data->packed_transaction = NULL;
2674 }
2675 }
2676
2677 cleanup:
2678 free(head_ref);
2679 string_list_clear(&affected_refnames, 0);
2680
2681 if (ret)
2682 files_transaction_cleanup(refs, transaction);
2683 else
2684 transaction->state = REF_TRANSACTION_PREPARED;
2685
2686 return ret;
2687 }
2688
2689 static int files_transaction_finish(struct ref_store *ref_store,
2690 struct ref_transaction *transaction,
2691 struct strbuf *err)
2692 {
2693 struct files_ref_store *refs =
2694 files_downcast(ref_store, 0, "ref_transaction_finish");
2695 size_t i;
2696 int ret = 0;
2697 struct strbuf sb = STRBUF_INIT;
2698 struct files_transaction_backend_data *backend_data;
2699 struct ref_transaction *packed_transaction;
2700
2701
2702 assert(err);
2703
2704 if (!transaction->nr) {
2705 transaction->state = REF_TRANSACTION_CLOSED;
2706 return 0;
2707 }
2708
2709 backend_data = transaction->backend_data;
2710 packed_transaction = backend_data->packed_transaction;
2711
2712 /* Perform updates first so live commits remain referenced */
2713 for (i = 0; i < transaction->nr; i++) {
2714 struct ref_update *update = transaction->updates[i];
2715 struct ref_lock *lock = update->backend_data;
2716
2717 if (update->flags & REF_NEEDS_COMMIT ||
2718 update->flags & REF_LOG_ONLY) {
2719 if (files_log_ref_write(refs,
2720 lock->ref_name,
2721 &lock->old_oid,
2722 &update->new_oid,
2723 update->msg, update->flags,
2724 err)) {
2725 char *old_msg = strbuf_detach(err, NULL);
2726
2727 strbuf_addf(err, "cannot update the ref '%s': %s",
2728 lock->ref_name, old_msg);
2729 free(old_msg);
2730 unlock_ref(lock);
2731 update->backend_data = NULL;
2732 ret = TRANSACTION_GENERIC_ERROR;
2733 goto cleanup;
2734 }
2735 }
2736 if (update->flags & REF_NEEDS_COMMIT) {
2737 clear_loose_ref_cache(refs);
2738 if (commit_ref(lock)) {
2739 strbuf_addf(err, "couldn't set '%s'", lock->ref_name);
2740 unlock_ref(lock);
2741 update->backend_data = NULL;
2742 ret = TRANSACTION_GENERIC_ERROR;
2743 goto cleanup;
2744 }
2745 }
2746 }
2747
2748 /*
2749 * Now that updates are safely completed, we can perform
2750 * deletes. First delete the reflogs of any references that
2751 * will be deleted, since (in the unexpected event of an
2752 * error) leaving a reference without a reflog is less bad
2753 * than leaving a reflog without a reference (the latter is a
2754 * mildly invalid repository state):
2755 */
2756 for (i = 0; i < transaction->nr; i++) {
2757 struct ref_update *update = transaction->updates[i];
2758 if (update->flags & REF_DELETING &&
2759 !(update->flags & REF_LOG_ONLY) &&
2760 !(update->flags & REF_IS_PRUNING)) {
2761 strbuf_reset(&sb);
2762 files_reflog_path(refs, &sb, update->refname);
2763 if (!unlink_or_warn(sb.buf))
2764 try_remove_empty_parents(refs, update->refname,
2765 REMOVE_EMPTY_PARENTS_REFLOG);
2766 }
2767 }
2768
2769 /*
2770 * Perform deletes now that updates are safely completed.
2771 *
2772 * First delete any packed versions of the references, while
2773 * retaining the packed-refs lock:
2774 */
2775 if (packed_transaction) {
2776 ret = ref_transaction_commit(packed_transaction, err);
2777 ref_transaction_free(packed_transaction);
2778 packed_transaction = NULL;
2779 backend_data->packed_transaction = NULL;
2780 if (ret)
2781 goto cleanup;
2782 }
2783
2784 /* Now delete the loose versions of the references: */
2785 for (i = 0; i < transaction->nr; i++) {
2786 struct ref_update *update = transaction->updates[i];
2787 struct ref_lock *lock = update->backend_data;
2788
2789 if (update->flags & REF_DELETING &&
2790 !(update->flags & REF_LOG_ONLY)) {
2791 if (!(update->type & REF_ISPACKED) ||
2792 update->type & REF_ISSYMREF) {
2793 /* It is a loose reference. */
2794 strbuf_reset(&sb);
2795 files_ref_path(refs, &sb, lock->ref_name);
2796 if (unlink_or_msg(sb.buf, err)) {
2797 ret = TRANSACTION_GENERIC_ERROR;
2798 goto cleanup;
2799 }
2800 update->flags |= REF_DELETED_LOOSE;
2801 }
2802 }
2803 }
2804
2805 clear_loose_ref_cache(refs);
2806
2807 cleanup:
2808 files_transaction_cleanup(refs, transaction);
2809
2810 for (i = 0; i < transaction->nr; i++) {
2811 struct ref_update *update = transaction->updates[i];
2812
2813 if (update->flags & REF_DELETED_LOOSE) {
2814 /*
2815 * The loose reference was deleted. Delete any
2816 * empty parent directories. (Note that this
2817 * can only work because we have already
2818 * removed the lockfile.)
2819 */
2820 try_remove_empty_parents(refs, update->refname,
2821 REMOVE_EMPTY_PARENTS_REF);
2822 }
2823 }
2824
2825 strbuf_release(&sb);
2826 return ret;
2827 }
2828
2829 static int files_transaction_abort(struct ref_store *ref_store,
2830 struct ref_transaction *transaction,
2831 struct strbuf *err)
2832 {
2833 struct files_ref_store *refs =
2834 files_downcast(ref_store, 0, "ref_transaction_abort");
2835
2836 files_transaction_cleanup(refs, transaction);
2837 return 0;
2838 }
2839
2840 static int ref_present(const char *refname,
2841 const struct object_id *oid, int flags, void *cb_data)
2842 {
2843 struct string_list *affected_refnames = cb_data;
2844
2845 return string_list_has_string(affected_refnames, refname);
2846 }
2847
2848 static int files_initial_transaction_commit(struct ref_store *ref_store,
2849 struct ref_transaction *transaction,
2850 struct strbuf *err)
2851 {
2852 struct files_ref_store *refs =
2853 files_downcast(ref_store, REF_STORE_WRITE,
2854 "initial_ref_transaction_commit");
2855 size_t i;
2856 int ret = 0;
2857 struct string_list affected_refnames = STRING_LIST_INIT_NODUP;
2858 struct ref_transaction *packed_transaction = NULL;
2859
2860 assert(err);
2861
2862 if (transaction->state != REF_TRANSACTION_OPEN)
2863 BUG("commit called for transaction that is not open");
2864
2865 /* Fail if a refname appears more than once in the transaction: */
2866 for (i = 0; i < transaction->nr; i++)
2867 string_list_append(&affected_refnames,
2868 transaction->updates[i]->refname);
2869 string_list_sort(&affected_refnames);
2870 if (ref_update_reject_duplicates(&affected_refnames, err)) {
2871 ret = TRANSACTION_GENERIC_ERROR;
2872 goto cleanup;
2873 }
2874
2875 /*
2876 * It's really undefined to call this function in an active
2877 * repository or when there are existing references: we are
2878 * only locking and changing packed-refs, so (1) any
2879 * simultaneous processes might try to change a reference at
2880 * the same time we do, and (2) any existing loose versions of
2881 * the references that we are setting would have precedence
2882 * over our values. But some remote helpers create the remote
2883 * "HEAD" and "master" branches before calling this function,
2884 * so here we really only check that none of the references
2885 * that we are creating already exists.
2886 */
2887 if (refs_for_each_rawref(&refs->base, ref_present,
2888 &affected_refnames))
2889 BUG("initial ref transaction called with existing refs");
2890
2891 packed_transaction = ref_store_transaction_begin(refs->packed_ref_store, err);
2892 if (!packed_transaction) {
2893 ret = TRANSACTION_GENERIC_ERROR;
2894 goto cleanup;
2895 }
2896
2897 for (i = 0; i < transaction->nr; i++) {
2898 struct ref_update *update = transaction->updates[i];
2899
2900 if ((update->flags & REF_HAVE_OLD) &&
2901 !is_null_oid(&update->old_oid))
2902 BUG("initial ref transaction with old_sha1 set");
2903 if (refs_verify_refname_available(&refs->base, update->refname,
2904 &affected_refnames, NULL,
2905 err)) {
2906 ret = TRANSACTION_NAME_CONFLICT;
2907 goto cleanup;
2908 }
2909
2910 /*
2911 * Add a reference creation for this reference to the
2912 * packed-refs transaction:
2913 */
2914 ref_transaction_add_update(packed_transaction, update->refname,
2915 update->flags & ~REF_HAVE_OLD,
2916 &update->new_oid, &update->old_oid,
2917 NULL);
2918 }
2919
2920 if (packed_refs_lock(refs->packed_ref_store, 0, err)) {
2921 ret = TRANSACTION_GENERIC_ERROR;
2922 goto cleanup;
2923 }
2924
2925 if (initial_ref_transaction_commit(packed_transaction, err)) {
2926 ret = TRANSACTION_GENERIC_ERROR;
2927 }
2928
2929 packed_refs_unlock(refs->packed_ref_store);
2930 cleanup:
2931 if (packed_transaction)
2932 ref_transaction_free(packed_transaction);
2933 transaction->state = REF_TRANSACTION_CLOSED;
2934 string_list_clear(&affected_refnames, 0);
2935 return ret;
2936 }
2937
2938 struct expire_reflog_cb {
2939 unsigned int flags;
2940 reflog_expiry_should_prune_fn *should_prune_fn;
2941 void *policy_cb;
2942 FILE *newlog;
2943 struct object_id last_kept_oid;
2944 };
2945
2946 static int expire_reflog_ent(struct object_id *ooid, struct object_id *noid,
2947 const char *email, timestamp_t timestamp, int tz,
2948 const char *message, void *cb_data)
2949 {
2950 struct expire_reflog_cb *cb = cb_data;
2951 struct expire_reflog_policy_cb *policy_cb = cb->policy_cb;
2952
2953 if (cb->flags & EXPIRE_REFLOGS_REWRITE)
2954 ooid = &cb->last_kept_oid;
2955
2956 if ((*cb->should_prune_fn)(ooid, noid, email, timestamp, tz,
2957 message, policy_cb)) {
2958 if (!cb->newlog)
2959 printf("would prune %s", message);
2960 else if (cb->flags & EXPIRE_REFLOGS_VERBOSE)
2961 printf("prune %s", message);
2962 } else {
2963 if (cb->newlog) {
2964 fprintf(cb->newlog, "%s %s %s %"PRItime" %+05d\t%s",
2965 oid_to_hex(ooid), oid_to_hex(noid),
2966 email, timestamp, tz, message);
2967 oidcpy(&cb->last_kept_oid, noid);
2968 }
2969 if (cb->flags & EXPIRE_REFLOGS_VERBOSE)
2970 printf("keep %s", message);
2971 }
2972 return 0;
2973 }
2974
2975 static int files_reflog_expire(struct ref_store *ref_store,
2976 const char *refname, const struct object_id *oid,
2977 unsigned int flags,
2978 reflog_expiry_prepare_fn prepare_fn,
2979 reflog_expiry_should_prune_fn should_prune_fn,
2980 reflog_expiry_cleanup_fn cleanup_fn,
2981 void *policy_cb_data)
2982 {
2983 struct files_ref_store *refs =
2984 files_downcast(ref_store, REF_STORE_WRITE, "reflog_expire");
2985 struct lock_file reflog_lock = LOCK_INIT;
2986 struct expire_reflog_cb cb;
2987 struct ref_lock *lock;
2988 struct strbuf log_file_sb = STRBUF_INIT;
2989 char *log_file;
2990 int status = 0;
2991 int type;
2992 struct strbuf err = STRBUF_INIT;
2993
2994 memset(&cb, 0, sizeof(cb));
2995 cb.flags = flags;
2996 cb.policy_cb = policy_cb_data;
2997 cb.should_prune_fn = should_prune_fn;
2998
2999 /*
3000 * The reflog file is locked by holding the lock on the
3001 * reference itself, plus we might need to update the
3002 * reference if --updateref was specified:
3003 */
3004 lock = lock_ref_oid_basic(refs, refname, oid,
3005 NULL, NULL, REF_NO_DEREF,
3006 &type, &err);
3007 if (!lock) {
3008 error("cannot lock ref '%s': %s", refname, err.buf);
3009 strbuf_release(&err);
3010 return -1;
3011 }
3012 if (!refs_reflog_exists(ref_store, refname)) {
3013 unlock_ref(lock);
3014 return 0;
3015 }
3016
3017 files_reflog_path(refs, &log_file_sb, refname);
3018 log_file = strbuf_detach(&log_file_sb, NULL);
3019 if (!(flags & EXPIRE_REFLOGS_DRY_RUN)) {
3020 /*
3021 * Even though holding $GIT_DIR/logs/$reflog.lock has
3022 * no locking implications, we use the lock_file
3023 * machinery here anyway because it does a lot of the
3024 * work we need, including cleaning up if the program
3025 * exits unexpectedly.
3026 */
3027 if (hold_lock_file_for_update(&reflog_lock, log_file, 0) < 0) {
3028 struct strbuf err = STRBUF_INIT;
3029 unable_to_lock_message(log_file, errno, &err);
3030 error("%s", err.buf);
3031 strbuf_release(&err);
3032 goto failure;
3033 }
3034 cb.newlog = fdopen_lock_file(&reflog_lock, "w");
3035 if (!cb.newlog) {
3036 error("cannot fdopen %s (%s)",
3037 get_lock_file_path(&reflog_lock), strerror(errno));
3038 goto failure;
3039 }
3040 }
3041
3042 (*prepare_fn)(refname, oid, cb.policy_cb);
3043 refs_for_each_reflog_ent(ref_store, refname, expire_reflog_ent, &cb);
3044 (*cleanup_fn)(cb.policy_cb);
3045
3046 if (!(flags & EXPIRE_REFLOGS_DRY_RUN)) {
3047 /*
3048 * It doesn't make sense to adjust a reference pointed
3049 * to by a symbolic ref based on expiring entries in
3050 * the symbolic reference's reflog. Nor can we update
3051 * a reference if there are no remaining reflog
3052 * entries.
3053 */
3054 int update = (flags & EXPIRE_REFLOGS_UPDATE_REF) &&
3055 !(type & REF_ISSYMREF) &&
3056 !is_null_oid(&cb.last_kept_oid);
3057
3058 if (close_lock_file_gently(&reflog_lock)) {
3059 status |= error("couldn't write %s: %s", log_file,
3060 strerror(errno));
3061 rollback_lock_file(&reflog_lock);
3062 } else if (update &&
3063 (write_in_full(get_lock_file_fd(&lock->lk),
3064 oid_to_hex(&cb.last_kept_oid), the_hash_algo->hexsz) < 0 ||
3065 write_str_in_full(get_lock_file_fd(&lock->lk), "\n") < 0 ||
3066 close_ref_gently(lock) < 0)) {
3067 status |= error("couldn't write %s",
3068 get_lock_file_path(&lock->lk));
3069 rollback_lock_file(&reflog_lock);
3070 } else if (commit_lock_file(&reflog_lock)) {
3071 status |= error("unable to write reflog '%s' (%s)",
3072 log_file, strerror(errno));
3073 } else if (update && commit_ref(lock)) {
3074 status |= error("couldn't set %s", lock->ref_name);
3075 }
3076 }
3077 free(log_file);
3078 unlock_ref(lock);
3079 return status;
3080
3081 failure:
3082 rollback_lock_file(&reflog_lock);
3083 free(log_file);
3084 unlock_ref(lock);
3085 return -1;
3086 }
3087
3088 static int files_init_db(struct ref_store *ref_store, struct strbuf *err)
3089 {
3090 struct files_ref_store *refs =
3091 files_downcast(ref_store, REF_STORE_WRITE, "init_db");
3092 struct strbuf sb = STRBUF_INIT;
3093
3094 /*
3095 * Create .git/refs/{heads,tags}
3096 */
3097 files_ref_path(refs, &sb, "refs/heads");
3098 safe_create_dir(sb.buf, 1);
3099
3100 strbuf_reset(&sb);
3101 files_ref_path(refs, &sb, "refs/tags");
3102 safe_create_dir(sb.buf, 1);
3103
3104 strbuf_release(&sb);
3105 return 0;
3106 }
3107
3108 struct ref_storage_be refs_be_files = {
3109 NULL,
3110 "files",
3111 files_ref_store_create,
3112 files_init_db,
3113 files_transaction_prepare,
3114 files_transaction_finish,
3115 files_transaction_abort,
3116 files_initial_transaction_commit,
3117
3118 files_pack_refs,
3119 files_create_symref,
3120 files_delete_refs,
3121 files_rename_ref,
3122 files_copy_ref,
3123
3124 files_ref_iterator_begin,
3125 files_read_raw_ref,
3126
3127 files_reflog_iterator_begin,
3128 files_for_each_reflog_ent,
3129 files_for_each_reflog_ent_reverse,
3130 files_reflog_exists,
3131 files_create_reflog,
3132 files_delete_reflog,
3133 files_reflog_expire
3134 };