Merge branch 'ds/commit-graph'
[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 /*
66 * Future: need to be in "struct repository"
67 * when doing a full libification.
68 */
69 struct files_ref_store {
70 struct ref_store base;
71 unsigned int store_flags;
72
73 char *gitdir;
74 char *gitcommondir;
75
76 struct ref_cache *loose;
77
78 struct ref_store *packed_ref_store;
79 };
80
81 static void clear_loose_ref_cache(struct files_ref_store *refs)
82 {
83 if (refs->loose) {
84 free_ref_cache(refs->loose);
85 refs->loose = NULL;
86 }
87 }
88
89 /*
90 * Create a new submodule ref cache and add it to the internal
91 * set of caches.
92 */
93 static struct ref_store *files_ref_store_create(const char *gitdir,
94 unsigned int flags)
95 {
96 struct files_ref_store *refs = xcalloc(1, sizeof(*refs));
97 struct ref_store *ref_store = (struct ref_store *)refs;
98 struct strbuf sb = STRBUF_INIT;
99
100 base_ref_store_init(ref_store, &refs_be_files);
101 refs->store_flags = flags;
102
103 refs->gitdir = xstrdup(gitdir);
104 get_common_dir_noenv(&sb, gitdir);
105 refs->gitcommondir = strbuf_detach(&sb, NULL);
106 strbuf_addf(&sb, "%s/packed-refs", refs->gitcommondir);
107 refs->packed_ref_store = packed_ref_store_create(sb.buf, flags);
108 strbuf_release(&sb);
109
110 chdir_notify_reparent("files-backend $GIT_DIR",
111 &refs->gitdir);
112 chdir_notify_reparent("files-backend $GIT_COMMONDIR",
113 &refs->gitcommondir);
114
115 return ref_store;
116 }
117
118 /*
119 * Die if refs is not the main ref store. caller is used in any
120 * necessary error messages.
121 */
122 static void files_assert_main_repository(struct files_ref_store *refs,
123 const char *caller)
124 {
125 if (refs->store_flags & REF_STORE_MAIN)
126 return;
127
128 die("BUG: operation %s only allowed for main ref store", caller);
129 }
130
131 /*
132 * Downcast ref_store to files_ref_store. Die if ref_store is not a
133 * files_ref_store. required_flags is compared with ref_store's
134 * store_flags to ensure the ref_store has all required capabilities.
135 * "caller" is used in any necessary error messages.
136 */
137 static struct files_ref_store *files_downcast(struct ref_store *ref_store,
138 unsigned int required_flags,
139 const char *caller)
140 {
141 struct files_ref_store *refs;
142
143 if (ref_store->be != &refs_be_files)
144 die("BUG: ref_store is type \"%s\" not \"files\" in %s",
145 ref_store->be->name, caller);
146
147 refs = (struct files_ref_store *)ref_store;
148
149 if ((refs->store_flags & required_flags) != required_flags)
150 die("BUG: operation %s requires abilities 0x%x, but only have 0x%x",
151 caller, required_flags, refs->store_flags);
152
153 return refs;
154 }
155
156 static void files_reflog_path(struct files_ref_store *refs,
157 struct strbuf *sb,
158 const char *refname)
159 {
160 switch (ref_type(refname)) {
161 case REF_TYPE_PER_WORKTREE:
162 case REF_TYPE_PSEUDOREF:
163 strbuf_addf(sb, "%s/logs/%s", refs->gitdir, refname);
164 break;
165 case REF_TYPE_NORMAL:
166 strbuf_addf(sb, "%s/logs/%s", refs->gitcommondir, refname);
167 break;
168 default:
169 die("BUG: unknown ref type %d of ref %s",
170 ref_type(refname), refname);
171 }
172 }
173
174 static void files_ref_path(struct files_ref_store *refs,
175 struct strbuf *sb,
176 const char *refname)
177 {
178 switch (ref_type(refname)) {
179 case REF_TYPE_PER_WORKTREE:
180 case REF_TYPE_PSEUDOREF:
181 strbuf_addf(sb, "%s/%s", refs->gitdir, refname);
182 break;
183 case REF_TYPE_NORMAL:
184 strbuf_addf(sb, "%s/%s", refs->gitcommondir, refname);
185 break;
186 default:
187 die("BUG: unknown ref type %d of ref %s",
188 ref_type(refname), refname);
189 }
190 }
191
192 /*
193 * Read the loose references from the namespace dirname into dir
194 * (without recursing). dirname must end with '/'. dir must be the
195 * directory entry corresponding to dirname.
196 */
197 static void loose_fill_ref_dir(struct ref_store *ref_store,
198 struct ref_dir *dir, const char *dirname)
199 {
200 struct files_ref_store *refs =
201 files_downcast(ref_store, REF_STORE_READ, "fill_ref_dir");
202 DIR *d;
203 struct dirent *de;
204 int dirnamelen = strlen(dirname);
205 struct strbuf refname;
206 struct strbuf path = STRBUF_INIT;
207 size_t path_baselen;
208
209 files_ref_path(refs, &path, dirname);
210 path_baselen = path.len;
211
212 d = opendir(path.buf);
213 if (!d) {
214 strbuf_release(&path);
215 return;
216 }
217
218 strbuf_init(&refname, dirnamelen + 257);
219 strbuf_add(&refname, dirname, dirnamelen);
220
221 while ((de = readdir(d)) != NULL) {
222 struct object_id oid;
223 struct stat st;
224 int flag;
225
226 if (de->d_name[0] == '.')
227 continue;
228 if (ends_with(de->d_name, ".lock"))
229 continue;
230 strbuf_addstr(&refname, de->d_name);
231 strbuf_addstr(&path, de->d_name);
232 if (stat(path.buf, &st) < 0) {
233 ; /* silently ignore */
234 } else if (S_ISDIR(st.st_mode)) {
235 strbuf_addch(&refname, '/');
236 add_entry_to_dir(dir,
237 create_dir_entry(dir->cache, refname.buf,
238 refname.len, 1));
239 } else {
240 if (!refs_resolve_ref_unsafe(&refs->base,
241 refname.buf,
242 RESOLVE_REF_READING,
243 &oid, &flag)) {
244 oidclr(&oid);
245 flag |= REF_ISBROKEN;
246 } else if (is_null_oid(&oid)) {
247 /*
248 * It is so astronomically unlikely
249 * that null_oid is the OID of an
250 * actual object that we consider its
251 * appearance in a loose reference
252 * file to be repo corruption
253 * (probably due to a software bug).
254 */
255 flag |= REF_ISBROKEN;
256 }
257
258 if (check_refname_format(refname.buf,
259 REFNAME_ALLOW_ONELEVEL)) {
260 if (!refname_is_safe(refname.buf))
261 die("loose refname is dangerous: %s", refname.buf);
262 oidclr(&oid);
263 flag |= REF_BAD_NAME | REF_ISBROKEN;
264 }
265 add_entry_to_dir(dir,
266 create_ref_entry(refname.buf, &oid, flag));
267 }
268 strbuf_setlen(&refname, dirnamelen);
269 strbuf_setlen(&path, path_baselen);
270 }
271 strbuf_release(&refname);
272 strbuf_release(&path);
273 closedir(d);
274
275 /*
276 * Manually add refs/bisect, which, being per-worktree, might
277 * not appear in the directory listing for refs/ in the main
278 * repo.
279 */
280 if (!strcmp(dirname, "refs/")) {
281 int pos = search_ref_dir(dir, "refs/bisect/", 12);
282
283 if (pos < 0) {
284 struct ref_entry *child_entry = create_dir_entry(
285 dir->cache, "refs/bisect/", 12, 1);
286 add_entry_to_dir(dir, child_entry);
287 }
288 }
289 }
290
291 static struct ref_cache *get_loose_ref_cache(struct files_ref_store *refs)
292 {
293 if (!refs->loose) {
294 /*
295 * Mark the top-level directory complete because we
296 * are about to read the only subdirectory that can
297 * hold references:
298 */
299 refs->loose = create_ref_cache(&refs->base, loose_fill_ref_dir);
300
301 /* We're going to fill the top level ourselves: */
302 refs->loose->root->flag &= ~REF_INCOMPLETE;
303
304 /*
305 * Add an incomplete entry for "refs/" (to be filled
306 * lazily):
307 */
308 add_entry_to_dir(get_ref_dir(refs->loose->root),
309 create_dir_entry(refs->loose, "refs/", 5, 1));
310 }
311 return refs->loose;
312 }
313
314 static int files_read_raw_ref(struct ref_store *ref_store,
315 const char *refname, struct object_id *oid,
316 struct strbuf *referent, unsigned int *type)
317 {
318 struct files_ref_store *refs =
319 files_downcast(ref_store, REF_STORE_READ, "read_raw_ref");
320 struct strbuf sb_contents = STRBUF_INIT;
321 struct strbuf sb_path = STRBUF_INIT;
322 const char *path;
323 const char *buf;
324 const char *p;
325 struct stat st;
326 int fd;
327 int ret = -1;
328 int save_errno;
329 int remaining_retries = 3;
330
331 *type = 0;
332 strbuf_reset(&sb_path);
333
334 files_ref_path(refs, &sb_path, refname);
335
336 path = sb_path.buf;
337
338 stat_ref:
339 /*
340 * We might have to loop back here to avoid a race
341 * condition: first we lstat() the file, then we try
342 * to read it as a link or as a file. But if somebody
343 * changes the type of the file (file <-> directory
344 * <-> symlink) between the lstat() and reading, then
345 * we don't want to report that as an error but rather
346 * try again starting with the lstat().
347 *
348 * We'll keep a count of the retries, though, just to avoid
349 * any confusing situation sending us into an infinite loop.
350 */
351
352 if (remaining_retries-- <= 0)
353 goto out;
354
355 if (lstat(path, &st) < 0) {
356 if (errno != ENOENT)
357 goto out;
358 if (refs_read_raw_ref(refs->packed_ref_store, refname,
359 oid, referent, type)) {
360 errno = ENOENT;
361 goto out;
362 }
363 ret = 0;
364 goto out;
365 }
366
367 /* Follow "normalized" - ie "refs/.." symlinks by hand */
368 if (S_ISLNK(st.st_mode)) {
369 strbuf_reset(&sb_contents);
370 if (strbuf_readlink(&sb_contents, path, 0) < 0) {
371 if (errno == ENOENT || errno == EINVAL)
372 /* inconsistent with lstat; retry */
373 goto stat_ref;
374 else
375 goto out;
376 }
377 if (starts_with(sb_contents.buf, "refs/") &&
378 !check_refname_format(sb_contents.buf, 0)) {
379 strbuf_swap(&sb_contents, referent);
380 *type |= REF_ISSYMREF;
381 ret = 0;
382 goto out;
383 }
384 /*
385 * It doesn't look like a refname; fall through to just
386 * treating it like a non-symlink, and reading whatever it
387 * points to.
388 */
389 }
390
391 /* Is it a directory? */
392 if (S_ISDIR(st.st_mode)) {
393 /*
394 * Even though there is a directory where the loose
395 * ref is supposed to be, there could still be a
396 * packed ref:
397 */
398 if (refs_read_raw_ref(refs->packed_ref_store, refname,
399 oid, referent, type)) {
400 errno = EISDIR;
401 goto out;
402 }
403 ret = 0;
404 goto out;
405 }
406
407 /*
408 * Anything else, just open it and try to use it as
409 * a ref
410 */
411 fd = open(path, O_RDONLY);
412 if (fd < 0) {
413 if (errno == ENOENT && !S_ISLNK(st.st_mode))
414 /* inconsistent with lstat; retry */
415 goto stat_ref;
416 else
417 goto out;
418 }
419 strbuf_reset(&sb_contents);
420 if (strbuf_read(&sb_contents, fd, 256) < 0) {
421 int save_errno = errno;
422 close(fd);
423 errno = save_errno;
424 goto out;
425 }
426 close(fd);
427 strbuf_rtrim(&sb_contents);
428 buf = sb_contents.buf;
429 if (starts_with(buf, "ref:")) {
430 buf += 4;
431 while (isspace(*buf))
432 buf++;
433
434 strbuf_reset(referent);
435 strbuf_addstr(referent, buf);
436 *type |= REF_ISSYMREF;
437 ret = 0;
438 goto out;
439 }
440
441 /*
442 * Please note that FETCH_HEAD has additional
443 * data after the sha.
444 */
445 if (parse_oid_hex(buf, oid, &p) ||
446 (*p != '\0' && !isspace(*p))) {
447 *type |= REF_ISBROKEN;
448 errno = EINVAL;
449 goto out;
450 }
451
452 ret = 0;
453
454 out:
455 save_errno = errno;
456 strbuf_release(&sb_path);
457 strbuf_release(&sb_contents);
458 errno = save_errno;
459 return ret;
460 }
461
462 static void unlock_ref(struct ref_lock *lock)
463 {
464 rollback_lock_file(&lock->lk);
465 free(lock->ref_name);
466 free(lock);
467 }
468
469 /*
470 * Lock refname, without following symrefs, and set *lock_p to point
471 * at a newly-allocated lock object. Fill in lock->old_oid, referent,
472 * and type similarly to read_raw_ref().
473 *
474 * The caller must verify that refname is a "safe" reference name (in
475 * the sense of refname_is_safe()) before calling this function.
476 *
477 * If the reference doesn't already exist, verify that refname doesn't
478 * have a D/F conflict with any existing references. extras and skip
479 * are passed to refs_verify_refname_available() for this check.
480 *
481 * If mustexist is not set and the reference is not found or is
482 * broken, lock the reference anyway but clear old_oid.
483 *
484 * Return 0 on success. On failure, write an error message to err and
485 * return TRANSACTION_NAME_CONFLICT or TRANSACTION_GENERIC_ERROR.
486 *
487 * Implementation note: This function is basically
488 *
489 * lock reference
490 * read_raw_ref()
491 *
492 * but it includes a lot more code to
493 * - Deal with possible races with other processes
494 * - Avoid calling refs_verify_refname_available() when it can be
495 * avoided, namely if we were successfully able to read the ref
496 * - Generate informative error messages in the case of failure
497 */
498 static int lock_raw_ref(struct files_ref_store *refs,
499 const char *refname, int mustexist,
500 const struct string_list *extras,
501 const struct string_list *skip,
502 struct ref_lock **lock_p,
503 struct strbuf *referent,
504 unsigned int *type,
505 struct strbuf *err)
506 {
507 struct ref_lock *lock;
508 struct strbuf ref_file = STRBUF_INIT;
509 int attempts_remaining = 3;
510 int ret = TRANSACTION_GENERIC_ERROR;
511
512 assert(err);
513 files_assert_main_repository(refs, "lock_raw_ref");
514
515 *type = 0;
516
517 /* First lock the file so it can't change out from under us. */
518
519 *lock_p = lock = xcalloc(1, sizeof(*lock));
520
521 lock->ref_name = xstrdup(refname);
522 files_ref_path(refs, &ref_file, refname);
523
524 retry:
525 switch (safe_create_leading_directories(ref_file.buf)) {
526 case SCLD_OK:
527 break; /* success */
528 case SCLD_EXISTS:
529 /*
530 * Suppose refname is "refs/foo/bar". We just failed
531 * to create the containing directory, "refs/foo",
532 * because there was a non-directory in the way. This
533 * indicates a D/F conflict, probably because of
534 * another reference such as "refs/foo". There is no
535 * reason to expect this error to be transitory.
536 */
537 if (refs_verify_refname_available(&refs->base, refname,
538 extras, skip, err)) {
539 if (mustexist) {
540 /*
541 * To the user the relevant error is
542 * that the "mustexist" reference is
543 * missing:
544 */
545 strbuf_reset(err);
546 strbuf_addf(err, "unable to resolve reference '%s'",
547 refname);
548 } else {
549 /*
550 * The error message set by
551 * refs_verify_refname_available() is
552 * OK.
553 */
554 ret = TRANSACTION_NAME_CONFLICT;
555 }
556 } else {
557 /*
558 * The file that is in the way isn't a loose
559 * reference. Report it as a low-level
560 * failure.
561 */
562 strbuf_addf(err, "unable to create lock file %s.lock; "
563 "non-directory in the way",
564 ref_file.buf);
565 }
566 goto error_return;
567 case SCLD_VANISHED:
568 /* Maybe another process was tidying up. Try again. */
569 if (--attempts_remaining > 0)
570 goto retry;
571 /* fall through */
572 default:
573 strbuf_addf(err, "unable to create directory for %s",
574 ref_file.buf);
575 goto error_return;
576 }
577
578 if (hold_lock_file_for_update_timeout(
579 &lock->lk, ref_file.buf, LOCK_NO_DEREF,
580 get_files_ref_lock_timeout_ms()) < 0) {
581 if (errno == ENOENT && --attempts_remaining > 0) {
582 /*
583 * Maybe somebody just deleted one of the
584 * directories leading to ref_file. Try
585 * again:
586 */
587 goto retry;
588 } else {
589 unable_to_lock_message(ref_file.buf, errno, err);
590 goto error_return;
591 }
592 }
593
594 /*
595 * Now we hold the lock and can read the reference without
596 * fear that its value will change.
597 */
598
599 if (files_read_raw_ref(&refs->base, refname,
600 &lock->old_oid, referent, type)) {
601 if (errno == ENOENT) {
602 if (mustexist) {
603 /* Garden variety missing reference. */
604 strbuf_addf(err, "unable to resolve reference '%s'",
605 refname);
606 goto error_return;
607 } else {
608 /*
609 * Reference is missing, but that's OK. We
610 * know that there is not a conflict with
611 * another loose reference because
612 * (supposing that we are trying to lock
613 * reference "refs/foo/bar"):
614 *
615 * - We were successfully able to create
616 * the lockfile refs/foo/bar.lock, so we
617 * know there cannot be a loose reference
618 * named "refs/foo".
619 *
620 * - We got ENOENT and not EISDIR, so we
621 * know that there cannot be a loose
622 * reference named "refs/foo/bar/baz".
623 */
624 }
625 } else if (errno == EISDIR) {
626 /*
627 * There is a directory in the way. It might have
628 * contained references that have been deleted. If
629 * we don't require that the reference already
630 * exists, try to remove the directory so that it
631 * doesn't cause trouble when we want to rename the
632 * lockfile into place later.
633 */
634 if (mustexist) {
635 /* Garden variety missing reference. */
636 strbuf_addf(err, "unable to resolve reference '%s'",
637 refname);
638 goto error_return;
639 } else if (remove_dir_recursively(&ref_file,
640 REMOVE_DIR_EMPTY_ONLY)) {
641 if (refs_verify_refname_available(
642 &refs->base, refname,
643 extras, skip, err)) {
644 /*
645 * The error message set by
646 * verify_refname_available() is OK.
647 */
648 ret = TRANSACTION_NAME_CONFLICT;
649 goto error_return;
650 } else {
651 /*
652 * We can't delete the directory,
653 * but we also don't know of any
654 * references that it should
655 * contain.
656 */
657 strbuf_addf(err, "there is a non-empty directory '%s' "
658 "blocking reference '%s'",
659 ref_file.buf, refname);
660 goto error_return;
661 }
662 }
663 } else if (errno == EINVAL && (*type & REF_ISBROKEN)) {
664 strbuf_addf(err, "unable to resolve reference '%s': "
665 "reference broken", refname);
666 goto error_return;
667 } else {
668 strbuf_addf(err, "unable to resolve reference '%s': %s",
669 refname, strerror(errno));
670 goto error_return;
671 }
672
673 /*
674 * If the ref did not exist and we are creating it,
675 * make sure there is no existing packed ref that
676 * conflicts with refname:
677 */
678 if (refs_verify_refname_available(
679 refs->packed_ref_store, refname,
680 extras, skip, err))
681 goto error_return;
682 }
683
684 ret = 0;
685 goto out;
686
687 error_return:
688 unlock_ref(lock);
689 *lock_p = NULL;
690
691 out:
692 strbuf_release(&ref_file);
693 return ret;
694 }
695
696 struct files_ref_iterator {
697 struct ref_iterator base;
698
699 struct ref_iterator *iter0;
700 unsigned int flags;
701 };
702
703 static int files_ref_iterator_advance(struct ref_iterator *ref_iterator)
704 {
705 struct files_ref_iterator *iter =
706 (struct files_ref_iterator *)ref_iterator;
707 int ok;
708
709 while ((ok = ref_iterator_advance(iter->iter0)) == ITER_OK) {
710 if (iter->flags & DO_FOR_EACH_PER_WORKTREE_ONLY &&
711 ref_type(iter->iter0->refname) != REF_TYPE_PER_WORKTREE)
712 continue;
713
714 if (!(iter->flags & DO_FOR_EACH_INCLUDE_BROKEN) &&
715 !ref_resolves_to_object(iter->iter0->refname,
716 iter->iter0->oid,
717 iter->iter0->flags))
718 continue;
719
720 iter->base.refname = iter->iter0->refname;
721 iter->base.oid = iter->iter0->oid;
722 iter->base.flags = iter->iter0->flags;
723 return ITER_OK;
724 }
725
726 iter->iter0 = NULL;
727 if (ref_iterator_abort(ref_iterator) != ITER_DONE)
728 ok = ITER_ERROR;
729
730 return ok;
731 }
732
733 static int files_ref_iterator_peel(struct ref_iterator *ref_iterator,
734 struct object_id *peeled)
735 {
736 struct files_ref_iterator *iter =
737 (struct files_ref_iterator *)ref_iterator;
738
739 return ref_iterator_peel(iter->iter0, peeled);
740 }
741
742 static int files_ref_iterator_abort(struct ref_iterator *ref_iterator)
743 {
744 struct files_ref_iterator *iter =
745 (struct files_ref_iterator *)ref_iterator;
746 int ok = ITER_DONE;
747
748 if (iter->iter0)
749 ok = ref_iterator_abort(iter->iter0);
750
751 base_ref_iterator_free(ref_iterator);
752 return ok;
753 }
754
755 static struct ref_iterator_vtable files_ref_iterator_vtable = {
756 files_ref_iterator_advance,
757 files_ref_iterator_peel,
758 files_ref_iterator_abort
759 };
760
761 static struct ref_iterator *files_ref_iterator_begin(
762 struct ref_store *ref_store,
763 const char *prefix, unsigned int flags)
764 {
765 struct files_ref_store *refs;
766 struct ref_iterator *loose_iter, *packed_iter, *overlay_iter;
767 struct files_ref_iterator *iter;
768 struct ref_iterator *ref_iterator;
769 unsigned int required_flags = REF_STORE_READ;
770
771 if (!(flags & DO_FOR_EACH_INCLUDE_BROKEN))
772 required_flags |= REF_STORE_ODB;
773
774 refs = files_downcast(ref_store, required_flags, "ref_iterator_begin");
775
776 /*
777 * We must make sure that all loose refs are read before
778 * accessing the packed-refs file; this avoids a race
779 * condition if loose refs are migrated to the packed-refs
780 * file by a simultaneous process, but our in-memory view is
781 * from before the migration. We ensure this as follows:
782 * First, we call start the loose refs iteration with its
783 * `prime_ref` argument set to true. This causes the loose
784 * references in the subtree to be pre-read into the cache.
785 * (If they've already been read, that's OK; we only need to
786 * guarantee that they're read before the packed refs, not
787 * *how much* before.) After that, we call
788 * packed_ref_iterator_begin(), which internally checks
789 * whether the packed-ref cache is up to date with what is on
790 * disk, and re-reads it if not.
791 */
792
793 loose_iter = cache_ref_iterator_begin(get_loose_ref_cache(refs),
794 prefix, 1);
795
796 /*
797 * The packed-refs file might contain broken references, for
798 * example an old version of a reference that points at an
799 * object that has since been garbage-collected. This is OK as
800 * long as there is a corresponding loose reference that
801 * overrides it, and we don't want to emit an error message in
802 * this case. So ask the packed_ref_store for all of its
803 * references, and (if needed) do our own check for broken
804 * ones in files_ref_iterator_advance(), after we have merged
805 * the packed and loose references.
806 */
807 packed_iter = refs_ref_iterator_begin(
808 refs->packed_ref_store, prefix, 0,
809 DO_FOR_EACH_INCLUDE_BROKEN);
810
811 overlay_iter = overlay_ref_iterator_begin(loose_iter, packed_iter);
812
813 iter = xcalloc(1, sizeof(*iter));
814 ref_iterator = &iter->base;
815 base_ref_iterator_init(ref_iterator, &files_ref_iterator_vtable,
816 overlay_iter->ordered);
817 iter->iter0 = overlay_iter;
818 iter->flags = flags;
819
820 return ref_iterator;
821 }
822
823 /*
824 * Verify that the reference locked by lock has the value old_oid
825 * (unless it is NULL). Fail if the reference doesn't exist and
826 * mustexist is set. Return 0 on success. On error, write an error
827 * message to err, set errno, and return a negative value.
828 */
829 static int verify_lock(struct ref_store *ref_store, struct ref_lock *lock,
830 const struct object_id *old_oid, int mustexist,
831 struct strbuf *err)
832 {
833 assert(err);
834
835 if (refs_read_ref_full(ref_store, lock->ref_name,
836 mustexist ? RESOLVE_REF_READING : 0,
837 &lock->old_oid, NULL)) {
838 if (old_oid) {
839 int save_errno = errno;
840 strbuf_addf(err, "can't verify ref '%s'", lock->ref_name);
841 errno = save_errno;
842 return -1;
843 } else {
844 oidclr(&lock->old_oid);
845 return 0;
846 }
847 }
848 if (old_oid && oidcmp(&lock->old_oid, old_oid)) {
849 strbuf_addf(err, "ref '%s' is at %s but expected %s",
850 lock->ref_name,
851 oid_to_hex(&lock->old_oid),
852 oid_to_hex(old_oid));
853 errno = EBUSY;
854 return -1;
855 }
856 return 0;
857 }
858
859 static int remove_empty_directories(struct strbuf *path)
860 {
861 /*
862 * we want to create a file but there is a directory there;
863 * if that is an empty directory (or a directory that contains
864 * only empty directories), remove them.
865 */
866 return remove_dir_recursively(path, REMOVE_DIR_EMPTY_ONLY);
867 }
868
869 static int create_reflock(const char *path, void *cb)
870 {
871 struct lock_file *lk = cb;
872
873 return hold_lock_file_for_update_timeout(
874 lk, path, LOCK_NO_DEREF,
875 get_files_ref_lock_timeout_ms()) < 0 ? -1 : 0;
876 }
877
878 /*
879 * Locks a ref returning the lock on success and NULL on failure.
880 * On failure errno is set to something meaningful.
881 */
882 static struct ref_lock *lock_ref_oid_basic(struct files_ref_store *refs,
883 const char *refname,
884 const struct object_id *old_oid,
885 const struct string_list *extras,
886 const struct string_list *skip,
887 unsigned int flags, int *type,
888 struct strbuf *err)
889 {
890 struct strbuf ref_file = STRBUF_INIT;
891 struct ref_lock *lock;
892 int last_errno = 0;
893 int mustexist = (old_oid && !is_null_oid(old_oid));
894 int resolve_flags = RESOLVE_REF_NO_RECURSE;
895 int resolved;
896
897 files_assert_main_repository(refs, "lock_ref_oid_basic");
898 assert(err);
899
900 lock = xcalloc(1, sizeof(struct ref_lock));
901
902 if (mustexist)
903 resolve_flags |= RESOLVE_REF_READING;
904 if (flags & REF_DELETING)
905 resolve_flags |= RESOLVE_REF_ALLOW_BAD_NAME;
906
907 files_ref_path(refs, &ref_file, refname);
908 resolved = !!refs_resolve_ref_unsafe(&refs->base,
909 refname, resolve_flags,
910 &lock->old_oid, type);
911 if (!resolved && errno == EISDIR) {
912 /*
913 * we are trying to lock foo but we used to
914 * have foo/bar which now does not exist;
915 * it is normal for the empty directory 'foo'
916 * to remain.
917 */
918 if (remove_empty_directories(&ref_file)) {
919 last_errno = errno;
920 if (!refs_verify_refname_available(
921 &refs->base,
922 refname, extras, skip, err))
923 strbuf_addf(err, "there are still refs under '%s'",
924 refname);
925 goto error_return;
926 }
927 resolved = !!refs_resolve_ref_unsafe(&refs->base,
928 refname, resolve_flags,
929 &lock->old_oid, type);
930 }
931 if (!resolved) {
932 last_errno = errno;
933 if (last_errno != ENOTDIR ||
934 !refs_verify_refname_available(&refs->base, refname,
935 extras, skip, err))
936 strbuf_addf(err, "unable to resolve reference '%s': %s",
937 refname, strerror(last_errno));
938
939 goto error_return;
940 }
941
942 /*
943 * If the ref did not exist and we are creating it, make sure
944 * there is no existing packed ref whose name begins with our
945 * refname, nor a packed ref whose name is a proper prefix of
946 * our refname.
947 */
948 if (is_null_oid(&lock->old_oid) &&
949 refs_verify_refname_available(refs->packed_ref_store, refname,
950 extras, skip, err)) {
951 last_errno = ENOTDIR;
952 goto error_return;
953 }
954
955 lock->ref_name = xstrdup(refname);
956
957 if (raceproof_create_file(ref_file.buf, create_reflock, &lock->lk)) {
958 last_errno = errno;
959 unable_to_lock_message(ref_file.buf, errno, err);
960 goto error_return;
961 }
962
963 if (verify_lock(&refs->base, lock, old_oid, mustexist, err)) {
964 last_errno = errno;
965 goto error_return;
966 }
967 goto out;
968
969 error_return:
970 unlock_ref(lock);
971 lock = NULL;
972
973 out:
974 strbuf_release(&ref_file);
975 errno = last_errno;
976 return lock;
977 }
978
979 struct ref_to_prune {
980 struct ref_to_prune *next;
981 struct object_id oid;
982 char name[FLEX_ARRAY];
983 };
984
985 enum {
986 REMOVE_EMPTY_PARENTS_REF = 0x01,
987 REMOVE_EMPTY_PARENTS_REFLOG = 0x02
988 };
989
990 /*
991 * Remove empty parent directories associated with the specified
992 * reference and/or its reflog, but spare [logs/]refs/ and immediate
993 * subdirs. flags is a combination of REMOVE_EMPTY_PARENTS_REF and/or
994 * REMOVE_EMPTY_PARENTS_REFLOG.
995 */
996 static void try_remove_empty_parents(struct files_ref_store *refs,
997 const char *refname,
998 unsigned int flags)
999 {
1000 struct strbuf buf = STRBUF_INIT;
1001 struct strbuf sb = STRBUF_INIT;
1002 char *p, *q;
1003 int i;
1004
1005 strbuf_addstr(&buf, refname);
1006 p = buf.buf;
1007 for (i = 0; i < 2; i++) { /* refs/{heads,tags,...}/ */
1008 while (*p && *p != '/')
1009 p++;
1010 /* tolerate duplicate slashes; see check_refname_format() */
1011 while (*p == '/')
1012 p++;
1013 }
1014 q = buf.buf + buf.len;
1015 while (flags & (REMOVE_EMPTY_PARENTS_REF | REMOVE_EMPTY_PARENTS_REFLOG)) {
1016 while (q > p && *q != '/')
1017 q--;
1018 while (q > p && *(q-1) == '/')
1019 q--;
1020 if (q == p)
1021 break;
1022 strbuf_setlen(&buf, q - buf.buf);
1023
1024 strbuf_reset(&sb);
1025 files_ref_path(refs, &sb, buf.buf);
1026 if ((flags & REMOVE_EMPTY_PARENTS_REF) && rmdir(sb.buf))
1027 flags &= ~REMOVE_EMPTY_PARENTS_REF;
1028
1029 strbuf_reset(&sb);
1030 files_reflog_path(refs, &sb, buf.buf);
1031 if ((flags & REMOVE_EMPTY_PARENTS_REFLOG) && rmdir(sb.buf))
1032 flags &= ~REMOVE_EMPTY_PARENTS_REFLOG;
1033 }
1034 strbuf_release(&buf);
1035 strbuf_release(&sb);
1036 }
1037
1038 /* make sure nobody touched the ref, and unlink */
1039 static void prune_ref(struct files_ref_store *refs, struct ref_to_prune *r)
1040 {
1041 struct ref_transaction *transaction;
1042 struct strbuf err = STRBUF_INIT;
1043 int ret = -1;
1044
1045 if (check_refname_format(r->name, 0))
1046 return;
1047
1048 transaction = ref_store_transaction_begin(&refs->base, &err);
1049 if (!transaction)
1050 goto cleanup;
1051 ref_transaction_add_update(
1052 transaction, r->name,
1053 REF_NO_DEREF | REF_HAVE_NEW | REF_HAVE_OLD | REF_IS_PRUNING,
1054 &null_oid, &r->oid, NULL);
1055 if (ref_transaction_commit(transaction, &err))
1056 goto cleanup;
1057
1058 ret = 0;
1059
1060 cleanup:
1061 if (ret)
1062 error("%s", err.buf);
1063 strbuf_release(&err);
1064 ref_transaction_free(transaction);
1065 return;
1066 }
1067
1068 /*
1069 * Prune the loose versions of the references in the linked list
1070 * `*refs_to_prune`, freeing the entries in the list as we go.
1071 */
1072 static void prune_refs(struct files_ref_store *refs, struct ref_to_prune **refs_to_prune)
1073 {
1074 while (*refs_to_prune) {
1075 struct ref_to_prune *r = *refs_to_prune;
1076 *refs_to_prune = r->next;
1077 prune_ref(refs, r);
1078 free(r);
1079 }
1080 }
1081
1082 /*
1083 * Return true if the specified reference should be packed.
1084 */
1085 static int should_pack_ref(const char *refname,
1086 const struct object_id *oid, unsigned int ref_flags,
1087 unsigned int pack_flags)
1088 {
1089 /* Do not pack per-worktree refs: */
1090 if (ref_type(refname) != REF_TYPE_NORMAL)
1091 return 0;
1092
1093 /* Do not pack non-tags unless PACK_REFS_ALL is set: */
1094 if (!(pack_flags & PACK_REFS_ALL) && !starts_with(refname, "refs/tags/"))
1095 return 0;
1096
1097 /* Do not pack symbolic refs: */
1098 if (ref_flags & REF_ISSYMREF)
1099 return 0;
1100
1101 /* Do not pack broken refs: */
1102 if (!ref_resolves_to_object(refname, oid, ref_flags))
1103 return 0;
1104
1105 return 1;
1106 }
1107
1108 static int files_pack_refs(struct ref_store *ref_store, unsigned int flags)
1109 {
1110 struct files_ref_store *refs =
1111 files_downcast(ref_store, REF_STORE_WRITE | REF_STORE_ODB,
1112 "pack_refs");
1113 struct ref_iterator *iter;
1114 int ok;
1115 struct ref_to_prune *refs_to_prune = NULL;
1116 struct strbuf err = STRBUF_INIT;
1117 struct ref_transaction *transaction;
1118
1119 transaction = ref_store_transaction_begin(refs->packed_ref_store, &err);
1120 if (!transaction)
1121 return -1;
1122
1123 packed_refs_lock(refs->packed_ref_store, LOCK_DIE_ON_ERROR, &err);
1124
1125 iter = cache_ref_iterator_begin(get_loose_ref_cache(refs), NULL, 0);
1126 while ((ok = ref_iterator_advance(iter)) == ITER_OK) {
1127 /*
1128 * If the loose reference can be packed, add an entry
1129 * in the packed ref cache. If the reference should be
1130 * pruned, also add it to refs_to_prune.
1131 */
1132 if (!should_pack_ref(iter->refname, iter->oid, iter->flags,
1133 flags))
1134 continue;
1135
1136 /*
1137 * Add a reference creation for this reference to the
1138 * packed-refs transaction:
1139 */
1140 if (ref_transaction_update(transaction, iter->refname,
1141 iter->oid, NULL,
1142 REF_NO_DEREF, NULL, &err))
1143 die("failure preparing to create packed reference %s: %s",
1144 iter->refname, err.buf);
1145
1146 /* Schedule the loose reference for pruning if requested. */
1147 if ((flags & PACK_REFS_PRUNE)) {
1148 struct ref_to_prune *n;
1149 FLEX_ALLOC_STR(n, name, iter->refname);
1150 oidcpy(&n->oid, iter->oid);
1151 n->next = refs_to_prune;
1152 refs_to_prune = n;
1153 }
1154 }
1155 if (ok != ITER_DONE)
1156 die("error while iterating over references");
1157
1158 if (ref_transaction_commit(transaction, &err))
1159 die("unable to write new packed-refs: %s", err.buf);
1160
1161 ref_transaction_free(transaction);
1162
1163 packed_refs_unlock(refs->packed_ref_store);
1164
1165 prune_refs(refs, &refs_to_prune);
1166 strbuf_release(&err);
1167 return 0;
1168 }
1169
1170 static int files_delete_refs(struct ref_store *ref_store, const char *msg,
1171 struct string_list *refnames, unsigned int flags)
1172 {
1173 struct files_ref_store *refs =
1174 files_downcast(ref_store, REF_STORE_WRITE, "delete_refs");
1175 struct strbuf err = STRBUF_INIT;
1176 int i, result = 0;
1177
1178 if (!refnames->nr)
1179 return 0;
1180
1181 if (packed_refs_lock(refs->packed_ref_store, 0, &err))
1182 goto error;
1183
1184 if (refs_delete_refs(refs->packed_ref_store, msg, refnames, flags)) {
1185 packed_refs_unlock(refs->packed_ref_store);
1186 goto error;
1187 }
1188
1189 packed_refs_unlock(refs->packed_ref_store);
1190
1191 for (i = 0; i < refnames->nr; i++) {
1192 const char *refname = refnames->items[i].string;
1193
1194 if (refs_delete_ref(&refs->base, msg, refname, NULL, flags))
1195 result |= error(_("could not remove reference %s"), refname);
1196 }
1197
1198 strbuf_release(&err);
1199 return result;
1200
1201 error:
1202 /*
1203 * If we failed to rewrite the packed-refs file, then it is
1204 * unsafe to try to remove loose refs, because doing so might
1205 * expose an obsolete packed value for a reference that might
1206 * even point at an object that has been garbage collected.
1207 */
1208 if (refnames->nr == 1)
1209 error(_("could not delete reference %s: %s"),
1210 refnames->items[0].string, err.buf);
1211 else
1212 error(_("could not delete references: %s"), err.buf);
1213
1214 strbuf_release(&err);
1215 return -1;
1216 }
1217
1218 /*
1219 * People using contrib's git-new-workdir have .git/logs/refs ->
1220 * /some/other/path/.git/logs/refs, and that may live on another device.
1221 *
1222 * IOW, to avoid cross device rename errors, the temporary renamed log must
1223 * live into logs/refs.
1224 */
1225 #define TMP_RENAMED_LOG "refs/.tmp-renamed-log"
1226
1227 struct rename_cb {
1228 const char *tmp_renamed_log;
1229 int true_errno;
1230 };
1231
1232 static int rename_tmp_log_callback(const char *path, void *cb_data)
1233 {
1234 struct rename_cb *cb = cb_data;
1235
1236 if (rename(cb->tmp_renamed_log, path)) {
1237 /*
1238 * rename(a, b) when b is an existing directory ought
1239 * to result in ISDIR, but Solaris 5.8 gives ENOTDIR.
1240 * Sheesh. Record the true errno for error reporting,
1241 * but report EISDIR to raceproof_create_file() so
1242 * that it knows to retry.
1243 */
1244 cb->true_errno = errno;
1245 if (errno == ENOTDIR)
1246 errno = EISDIR;
1247 return -1;
1248 } else {
1249 return 0;
1250 }
1251 }
1252
1253 static int rename_tmp_log(struct files_ref_store *refs, const char *newrefname)
1254 {
1255 struct strbuf path = STRBUF_INIT;
1256 struct strbuf tmp = STRBUF_INIT;
1257 struct rename_cb cb;
1258 int ret;
1259
1260 files_reflog_path(refs, &path, newrefname);
1261 files_reflog_path(refs, &tmp, TMP_RENAMED_LOG);
1262 cb.tmp_renamed_log = tmp.buf;
1263 ret = raceproof_create_file(path.buf, rename_tmp_log_callback, &cb);
1264 if (ret) {
1265 if (errno == EISDIR)
1266 error("directory not empty: %s", path.buf);
1267 else
1268 error("unable to move logfile %s to %s: %s",
1269 tmp.buf, path.buf,
1270 strerror(cb.true_errno));
1271 }
1272
1273 strbuf_release(&path);
1274 strbuf_release(&tmp);
1275 return ret;
1276 }
1277
1278 static int write_ref_to_lockfile(struct ref_lock *lock,
1279 const struct object_id *oid, struct strbuf *err);
1280 static int commit_ref_update(struct files_ref_store *refs,
1281 struct ref_lock *lock,
1282 const struct object_id *oid, const char *logmsg,
1283 struct strbuf *err);
1284
1285 static int files_copy_or_rename_ref(struct ref_store *ref_store,
1286 const char *oldrefname, const char *newrefname,
1287 const char *logmsg, int copy)
1288 {
1289 struct files_ref_store *refs =
1290 files_downcast(ref_store, REF_STORE_WRITE, "rename_ref");
1291 struct object_id oid, orig_oid;
1292 int flag = 0, logmoved = 0;
1293 struct ref_lock *lock;
1294 struct stat loginfo;
1295 struct strbuf sb_oldref = STRBUF_INIT;
1296 struct strbuf sb_newref = STRBUF_INIT;
1297 struct strbuf tmp_renamed_log = STRBUF_INIT;
1298 int log, ret;
1299 struct strbuf err = STRBUF_INIT;
1300
1301 files_reflog_path(refs, &sb_oldref, oldrefname);
1302 files_reflog_path(refs, &sb_newref, newrefname);
1303 files_reflog_path(refs, &tmp_renamed_log, TMP_RENAMED_LOG);
1304
1305 log = !lstat(sb_oldref.buf, &loginfo);
1306 if (log && S_ISLNK(loginfo.st_mode)) {
1307 ret = error("reflog for %s is a symlink", oldrefname);
1308 goto out;
1309 }
1310
1311 if (!refs_resolve_ref_unsafe(&refs->base, oldrefname,
1312 RESOLVE_REF_READING | RESOLVE_REF_NO_RECURSE,
1313 &orig_oid, &flag)) {
1314 ret = error("refname %s not found", oldrefname);
1315 goto out;
1316 }
1317
1318 if (flag & REF_ISSYMREF) {
1319 if (copy)
1320 ret = error("refname %s is a symbolic ref, copying it is not supported",
1321 oldrefname);
1322 else
1323 ret = error("refname %s is a symbolic ref, renaming it is not supported",
1324 oldrefname);
1325 goto out;
1326 }
1327 if (!refs_rename_ref_available(&refs->base, oldrefname, newrefname)) {
1328 ret = 1;
1329 goto out;
1330 }
1331
1332 if (!copy && log && rename(sb_oldref.buf, tmp_renamed_log.buf)) {
1333 ret = error("unable to move logfile logs/%s to logs/"TMP_RENAMED_LOG": %s",
1334 oldrefname, strerror(errno));
1335 goto out;
1336 }
1337
1338 if (copy && log && copy_file(tmp_renamed_log.buf, sb_oldref.buf, 0644)) {
1339 ret = error("unable to copy logfile logs/%s to logs/"TMP_RENAMED_LOG": %s",
1340 oldrefname, strerror(errno));
1341 goto out;
1342 }
1343
1344 if (!copy && refs_delete_ref(&refs->base, logmsg, oldrefname,
1345 &orig_oid, REF_NO_DEREF)) {
1346 error("unable to delete old %s", oldrefname);
1347 goto rollback;
1348 }
1349
1350 /*
1351 * Since we are doing a shallow lookup, oid is not the
1352 * correct value to pass to delete_ref as old_oid. But that
1353 * doesn't matter, because an old_oid check wouldn't add to
1354 * the safety anyway; we want to delete the reference whatever
1355 * its current value.
1356 */
1357 if (!copy && !refs_read_ref_full(&refs->base, newrefname,
1358 RESOLVE_REF_READING | RESOLVE_REF_NO_RECURSE,
1359 &oid, NULL) &&
1360 refs_delete_ref(&refs->base, NULL, newrefname,
1361 NULL, REF_NO_DEREF)) {
1362 if (errno == EISDIR) {
1363 struct strbuf path = STRBUF_INIT;
1364 int result;
1365
1366 files_ref_path(refs, &path, newrefname);
1367 result = remove_empty_directories(&path);
1368 strbuf_release(&path);
1369
1370 if (result) {
1371 error("Directory not empty: %s", newrefname);
1372 goto rollback;
1373 }
1374 } else {
1375 error("unable to delete existing %s", newrefname);
1376 goto rollback;
1377 }
1378 }
1379
1380 if (log && rename_tmp_log(refs, newrefname))
1381 goto rollback;
1382
1383 logmoved = log;
1384
1385 lock = lock_ref_oid_basic(refs, newrefname, NULL, NULL, NULL,
1386 REF_NO_DEREF, NULL, &err);
1387 if (!lock) {
1388 if (copy)
1389 error("unable to copy '%s' to '%s': %s", oldrefname, newrefname, err.buf);
1390 else
1391 error("unable to rename '%s' to '%s': %s", oldrefname, newrefname, err.buf);
1392 strbuf_release(&err);
1393 goto rollback;
1394 }
1395 oidcpy(&lock->old_oid, &orig_oid);
1396
1397 if (write_ref_to_lockfile(lock, &orig_oid, &err) ||
1398 commit_ref_update(refs, lock, &orig_oid, logmsg, &err)) {
1399 error("unable to write current sha1 into %s: %s", newrefname, err.buf);
1400 strbuf_release(&err);
1401 goto rollback;
1402 }
1403
1404 ret = 0;
1405 goto out;
1406
1407 rollback:
1408 lock = lock_ref_oid_basic(refs, oldrefname, NULL, NULL, NULL,
1409 REF_NO_DEREF, NULL, &err);
1410 if (!lock) {
1411 error("unable to lock %s for rollback: %s", oldrefname, err.buf);
1412 strbuf_release(&err);
1413 goto rollbacklog;
1414 }
1415
1416 flag = log_all_ref_updates;
1417 log_all_ref_updates = LOG_REFS_NONE;
1418 if (write_ref_to_lockfile(lock, &orig_oid, &err) ||
1419 commit_ref_update(refs, lock, &orig_oid, NULL, &err)) {
1420 error("unable to write current sha1 into %s: %s", oldrefname, err.buf);
1421 strbuf_release(&err);
1422 }
1423 log_all_ref_updates = flag;
1424
1425 rollbacklog:
1426 if (logmoved && rename(sb_newref.buf, sb_oldref.buf))
1427 error("unable to restore logfile %s from %s: %s",
1428 oldrefname, newrefname, strerror(errno));
1429 if (!logmoved && log &&
1430 rename(tmp_renamed_log.buf, sb_oldref.buf))
1431 error("unable to restore logfile %s from logs/"TMP_RENAMED_LOG": %s",
1432 oldrefname, strerror(errno));
1433 ret = 1;
1434 out:
1435 strbuf_release(&sb_newref);
1436 strbuf_release(&sb_oldref);
1437 strbuf_release(&tmp_renamed_log);
1438
1439 return ret;
1440 }
1441
1442 static int files_rename_ref(struct ref_store *ref_store,
1443 const char *oldrefname, const char *newrefname,
1444 const char *logmsg)
1445 {
1446 return files_copy_or_rename_ref(ref_store, oldrefname,
1447 newrefname, logmsg, 0);
1448 }
1449
1450 static int files_copy_ref(struct ref_store *ref_store,
1451 const char *oldrefname, const char *newrefname,
1452 const char *logmsg)
1453 {
1454 return files_copy_or_rename_ref(ref_store, oldrefname,
1455 newrefname, logmsg, 1);
1456 }
1457
1458 static int close_ref_gently(struct ref_lock *lock)
1459 {
1460 if (close_lock_file_gently(&lock->lk))
1461 return -1;
1462 return 0;
1463 }
1464
1465 static int commit_ref(struct ref_lock *lock)
1466 {
1467 char *path = get_locked_file_path(&lock->lk);
1468 struct stat st;
1469
1470 if (!lstat(path, &st) && S_ISDIR(st.st_mode)) {
1471 /*
1472 * There is a directory at the path we want to rename
1473 * the lockfile to. Hopefully it is empty; try to
1474 * delete it.
1475 */
1476 size_t len = strlen(path);
1477 struct strbuf sb_path = STRBUF_INIT;
1478
1479 strbuf_attach(&sb_path, path, len, len);
1480
1481 /*
1482 * If this fails, commit_lock_file() will also fail
1483 * and will report the problem.
1484 */
1485 remove_empty_directories(&sb_path);
1486 strbuf_release(&sb_path);
1487 } else {
1488 free(path);
1489 }
1490
1491 if (commit_lock_file(&lock->lk))
1492 return -1;
1493 return 0;
1494 }
1495
1496 static int open_or_create_logfile(const char *path, void *cb)
1497 {
1498 int *fd = cb;
1499
1500 *fd = open(path, O_APPEND | O_WRONLY | O_CREAT, 0666);
1501 return (*fd < 0) ? -1 : 0;
1502 }
1503
1504 /*
1505 * Create a reflog for a ref. If force_create = 0, only create the
1506 * reflog for certain refs (those for which should_autocreate_reflog
1507 * returns non-zero). Otherwise, create it regardless of the reference
1508 * name. If the logfile already existed or was created, return 0 and
1509 * set *logfd to the file descriptor opened for appending to the file.
1510 * If no logfile exists and we decided not to create one, return 0 and
1511 * set *logfd to -1. On failure, fill in *err, set *logfd to -1, and
1512 * return -1.
1513 */
1514 static int log_ref_setup(struct files_ref_store *refs,
1515 const char *refname, int force_create,
1516 int *logfd, struct strbuf *err)
1517 {
1518 struct strbuf logfile_sb = STRBUF_INIT;
1519 char *logfile;
1520
1521 files_reflog_path(refs, &logfile_sb, refname);
1522 logfile = strbuf_detach(&logfile_sb, NULL);
1523
1524 if (force_create || should_autocreate_reflog(refname)) {
1525 if (raceproof_create_file(logfile, open_or_create_logfile, logfd)) {
1526 if (errno == ENOENT)
1527 strbuf_addf(err, "unable to create directory for '%s': "
1528 "%s", logfile, strerror(errno));
1529 else if (errno == EISDIR)
1530 strbuf_addf(err, "there are still logs under '%s'",
1531 logfile);
1532 else
1533 strbuf_addf(err, "unable to append to '%s': %s",
1534 logfile, strerror(errno));
1535
1536 goto error;
1537 }
1538 } else {
1539 *logfd = open(logfile, O_APPEND | O_WRONLY, 0666);
1540 if (*logfd < 0) {
1541 if (errno == ENOENT || errno == EISDIR) {
1542 /*
1543 * The logfile doesn't already exist,
1544 * but that is not an error; it only
1545 * means that we won't write log
1546 * entries to it.
1547 */
1548 ;
1549 } else {
1550 strbuf_addf(err, "unable to append to '%s': %s",
1551 logfile, strerror(errno));
1552 goto error;
1553 }
1554 }
1555 }
1556
1557 if (*logfd >= 0)
1558 adjust_shared_perm(logfile);
1559
1560 free(logfile);
1561 return 0;
1562
1563 error:
1564 free(logfile);
1565 return -1;
1566 }
1567
1568 static int files_create_reflog(struct ref_store *ref_store,
1569 const char *refname, int force_create,
1570 struct strbuf *err)
1571 {
1572 struct files_ref_store *refs =
1573 files_downcast(ref_store, REF_STORE_WRITE, "create_reflog");
1574 int fd;
1575
1576 if (log_ref_setup(refs, refname, force_create, &fd, err))
1577 return -1;
1578
1579 if (fd >= 0)
1580 close(fd);
1581
1582 return 0;
1583 }
1584
1585 static int log_ref_write_fd(int fd, const struct object_id *old_oid,
1586 const struct object_id *new_oid,
1587 const char *committer, const char *msg)
1588 {
1589 int msglen, written;
1590 unsigned maxlen, len;
1591 char *logrec;
1592
1593 msglen = msg ? strlen(msg) : 0;
1594 maxlen = strlen(committer) + msglen + 100;
1595 logrec = xmalloc(maxlen);
1596 len = xsnprintf(logrec, maxlen, "%s %s %s\n",
1597 oid_to_hex(old_oid),
1598 oid_to_hex(new_oid),
1599 committer);
1600 if (msglen)
1601 len += copy_reflog_msg(logrec + len - 1, msg) - 1;
1602
1603 written = len <= maxlen ? write_in_full(fd, logrec, len) : -1;
1604 free(logrec);
1605 if (written < 0)
1606 return -1;
1607
1608 return 0;
1609 }
1610
1611 static int files_log_ref_write(struct files_ref_store *refs,
1612 const char *refname, const struct object_id *old_oid,
1613 const struct object_id *new_oid, const char *msg,
1614 int flags, struct strbuf *err)
1615 {
1616 int logfd, result;
1617
1618 if (log_all_ref_updates == LOG_REFS_UNSET)
1619 log_all_ref_updates = is_bare_repository() ? LOG_REFS_NONE : LOG_REFS_NORMAL;
1620
1621 result = log_ref_setup(refs, refname,
1622 flags & REF_FORCE_CREATE_REFLOG,
1623 &logfd, err);
1624
1625 if (result)
1626 return result;
1627
1628 if (logfd < 0)
1629 return 0;
1630 result = log_ref_write_fd(logfd, old_oid, new_oid,
1631 git_committer_info(0), msg);
1632 if (result) {
1633 struct strbuf sb = STRBUF_INIT;
1634 int save_errno = errno;
1635
1636 files_reflog_path(refs, &sb, refname);
1637 strbuf_addf(err, "unable to append to '%s': %s",
1638 sb.buf, strerror(save_errno));
1639 strbuf_release(&sb);
1640 close(logfd);
1641 return -1;
1642 }
1643 if (close(logfd)) {
1644 struct strbuf sb = STRBUF_INIT;
1645 int save_errno = errno;
1646
1647 files_reflog_path(refs, &sb, refname);
1648 strbuf_addf(err, "unable to append to '%s': %s",
1649 sb.buf, strerror(save_errno));
1650 strbuf_release(&sb);
1651 return -1;
1652 }
1653 return 0;
1654 }
1655
1656 /*
1657 * Write oid into the open lockfile, then close the lockfile. On
1658 * errors, rollback the lockfile, fill in *err and return -1.
1659 */
1660 static int write_ref_to_lockfile(struct ref_lock *lock,
1661 const struct object_id *oid, struct strbuf *err)
1662 {
1663 static char term = '\n';
1664 struct object *o;
1665 int fd;
1666
1667 o = parse_object(oid);
1668 if (!o) {
1669 strbuf_addf(err,
1670 "trying to write ref '%s' with nonexistent object %s",
1671 lock->ref_name, oid_to_hex(oid));
1672 unlock_ref(lock);
1673 return -1;
1674 }
1675 if (o->type != OBJ_COMMIT && is_branch(lock->ref_name)) {
1676 strbuf_addf(err,
1677 "trying to write non-commit object %s to branch '%s'",
1678 oid_to_hex(oid), lock->ref_name);
1679 unlock_ref(lock);
1680 return -1;
1681 }
1682 fd = get_lock_file_fd(&lock->lk);
1683 if (write_in_full(fd, oid_to_hex(oid), GIT_SHA1_HEXSZ) < 0 ||
1684 write_in_full(fd, &term, 1) < 0 ||
1685 close_ref_gently(lock) < 0) {
1686 strbuf_addf(err,
1687 "couldn't write '%s'", get_lock_file_path(&lock->lk));
1688 unlock_ref(lock);
1689 return -1;
1690 }
1691 return 0;
1692 }
1693
1694 /*
1695 * Commit a change to a loose reference that has already been written
1696 * to the loose reference lockfile. Also update the reflogs if
1697 * necessary, using the specified lockmsg (which can be NULL).
1698 */
1699 static int commit_ref_update(struct files_ref_store *refs,
1700 struct ref_lock *lock,
1701 const struct object_id *oid, const char *logmsg,
1702 struct strbuf *err)
1703 {
1704 files_assert_main_repository(refs, "commit_ref_update");
1705
1706 clear_loose_ref_cache(refs);
1707 if (files_log_ref_write(refs, lock->ref_name,
1708 &lock->old_oid, oid,
1709 logmsg, 0, err)) {
1710 char *old_msg = strbuf_detach(err, NULL);
1711 strbuf_addf(err, "cannot update the ref '%s': %s",
1712 lock->ref_name, old_msg);
1713 free(old_msg);
1714 unlock_ref(lock);
1715 return -1;
1716 }
1717
1718 if (strcmp(lock->ref_name, "HEAD") != 0) {
1719 /*
1720 * Special hack: If a branch is updated directly and HEAD
1721 * points to it (may happen on the remote side of a push
1722 * for example) then logically the HEAD reflog should be
1723 * updated too.
1724 * A generic solution implies reverse symref information,
1725 * but finding all symrefs pointing to the given branch
1726 * would be rather costly for this rare event (the direct
1727 * update of a branch) to be worth it. So let's cheat and
1728 * check with HEAD only which should cover 99% of all usage
1729 * scenarios (even 100% of the default ones).
1730 */
1731 int head_flag;
1732 const char *head_ref;
1733
1734 head_ref = refs_resolve_ref_unsafe(&refs->base, "HEAD",
1735 RESOLVE_REF_READING,
1736 NULL, &head_flag);
1737 if (head_ref && (head_flag & REF_ISSYMREF) &&
1738 !strcmp(head_ref, lock->ref_name)) {
1739 struct strbuf log_err = STRBUF_INIT;
1740 if (files_log_ref_write(refs, "HEAD",
1741 &lock->old_oid, oid,
1742 logmsg, 0, &log_err)) {
1743 error("%s", log_err.buf);
1744 strbuf_release(&log_err);
1745 }
1746 }
1747 }
1748
1749 if (commit_ref(lock)) {
1750 strbuf_addf(err, "couldn't set '%s'", lock->ref_name);
1751 unlock_ref(lock);
1752 return -1;
1753 }
1754
1755 unlock_ref(lock);
1756 return 0;
1757 }
1758
1759 static int create_ref_symlink(struct ref_lock *lock, const char *target)
1760 {
1761 int ret = -1;
1762 #ifndef NO_SYMLINK_HEAD
1763 char *ref_path = get_locked_file_path(&lock->lk);
1764 unlink(ref_path);
1765 ret = symlink(target, ref_path);
1766 free(ref_path);
1767
1768 if (ret)
1769 fprintf(stderr, "no symlink - falling back to symbolic ref\n");
1770 #endif
1771 return ret;
1772 }
1773
1774 static void update_symref_reflog(struct files_ref_store *refs,
1775 struct ref_lock *lock, const char *refname,
1776 const char *target, const char *logmsg)
1777 {
1778 struct strbuf err = STRBUF_INIT;
1779 struct object_id new_oid;
1780 if (logmsg &&
1781 !refs_read_ref_full(&refs->base, target,
1782 RESOLVE_REF_READING, &new_oid, NULL) &&
1783 files_log_ref_write(refs, refname, &lock->old_oid,
1784 &new_oid, logmsg, 0, &err)) {
1785 error("%s", err.buf);
1786 strbuf_release(&err);
1787 }
1788 }
1789
1790 static int create_symref_locked(struct files_ref_store *refs,
1791 struct ref_lock *lock, const char *refname,
1792 const char *target, const char *logmsg)
1793 {
1794 if (prefer_symlink_refs && !create_ref_symlink(lock, target)) {
1795 update_symref_reflog(refs, lock, refname, target, logmsg);
1796 return 0;
1797 }
1798
1799 if (!fdopen_lock_file(&lock->lk, "w"))
1800 return error("unable to fdopen %s: %s",
1801 lock->lk.tempfile->filename.buf, strerror(errno));
1802
1803 update_symref_reflog(refs, lock, refname, target, logmsg);
1804
1805 /* no error check; commit_ref will check ferror */
1806 fprintf(lock->lk.tempfile->fp, "ref: %s\n", target);
1807 if (commit_ref(lock) < 0)
1808 return error("unable to write symref for %s: %s", refname,
1809 strerror(errno));
1810 return 0;
1811 }
1812
1813 static int files_create_symref(struct ref_store *ref_store,
1814 const char *refname, const char *target,
1815 const char *logmsg)
1816 {
1817 struct files_ref_store *refs =
1818 files_downcast(ref_store, REF_STORE_WRITE, "create_symref");
1819 struct strbuf err = STRBUF_INIT;
1820 struct ref_lock *lock;
1821 int ret;
1822
1823 lock = lock_ref_oid_basic(refs, refname, NULL,
1824 NULL, NULL, REF_NO_DEREF, NULL,
1825 &err);
1826 if (!lock) {
1827 error("%s", err.buf);
1828 strbuf_release(&err);
1829 return -1;
1830 }
1831
1832 ret = create_symref_locked(refs, lock, refname, target, logmsg);
1833 unlock_ref(lock);
1834 return ret;
1835 }
1836
1837 static int files_reflog_exists(struct ref_store *ref_store,
1838 const char *refname)
1839 {
1840 struct files_ref_store *refs =
1841 files_downcast(ref_store, REF_STORE_READ, "reflog_exists");
1842 struct strbuf sb = STRBUF_INIT;
1843 struct stat st;
1844 int ret;
1845
1846 files_reflog_path(refs, &sb, refname);
1847 ret = !lstat(sb.buf, &st) && S_ISREG(st.st_mode);
1848 strbuf_release(&sb);
1849 return ret;
1850 }
1851
1852 static int files_delete_reflog(struct ref_store *ref_store,
1853 const char *refname)
1854 {
1855 struct files_ref_store *refs =
1856 files_downcast(ref_store, REF_STORE_WRITE, "delete_reflog");
1857 struct strbuf sb = STRBUF_INIT;
1858 int ret;
1859
1860 files_reflog_path(refs, &sb, refname);
1861 ret = remove_path(sb.buf);
1862 strbuf_release(&sb);
1863 return ret;
1864 }
1865
1866 static int show_one_reflog_ent(struct strbuf *sb, each_reflog_ent_fn fn, void *cb_data)
1867 {
1868 struct object_id ooid, noid;
1869 char *email_end, *message;
1870 timestamp_t timestamp;
1871 int tz;
1872 const char *p = sb->buf;
1873
1874 /* old SP new SP name <email> SP time TAB msg LF */
1875 if (!sb->len || sb->buf[sb->len - 1] != '\n' ||
1876 parse_oid_hex(p, &ooid, &p) || *p++ != ' ' ||
1877 parse_oid_hex(p, &noid, &p) || *p++ != ' ' ||
1878 !(email_end = strchr(p, '>')) ||
1879 email_end[1] != ' ' ||
1880 !(timestamp = parse_timestamp(email_end + 2, &message, 10)) ||
1881 !message || message[0] != ' ' ||
1882 (message[1] != '+' && message[1] != '-') ||
1883 !isdigit(message[2]) || !isdigit(message[3]) ||
1884 !isdigit(message[4]) || !isdigit(message[5]))
1885 return 0; /* corrupt? */
1886 email_end[1] = '\0';
1887 tz = strtol(message + 1, NULL, 10);
1888 if (message[6] != '\t')
1889 message += 6;
1890 else
1891 message += 7;
1892 return fn(&ooid, &noid, p, timestamp, tz, message, cb_data);
1893 }
1894
1895 static char *find_beginning_of_line(char *bob, char *scan)
1896 {
1897 while (bob < scan && *(--scan) != '\n')
1898 ; /* keep scanning backwards */
1899 /*
1900 * Return either beginning of the buffer, or LF at the end of
1901 * the previous line.
1902 */
1903 return scan;
1904 }
1905
1906 static int files_for_each_reflog_ent_reverse(struct ref_store *ref_store,
1907 const char *refname,
1908 each_reflog_ent_fn fn,
1909 void *cb_data)
1910 {
1911 struct files_ref_store *refs =
1912 files_downcast(ref_store, REF_STORE_READ,
1913 "for_each_reflog_ent_reverse");
1914 struct strbuf sb = STRBUF_INIT;
1915 FILE *logfp;
1916 long pos;
1917 int ret = 0, at_tail = 1;
1918
1919 files_reflog_path(refs, &sb, refname);
1920 logfp = fopen(sb.buf, "r");
1921 strbuf_release(&sb);
1922 if (!logfp)
1923 return -1;
1924
1925 /* Jump to the end */
1926 if (fseek(logfp, 0, SEEK_END) < 0)
1927 ret = error("cannot seek back reflog for %s: %s",
1928 refname, strerror(errno));
1929 pos = ftell(logfp);
1930 while (!ret && 0 < pos) {
1931 int cnt;
1932 size_t nread;
1933 char buf[BUFSIZ];
1934 char *endp, *scanp;
1935
1936 /* Fill next block from the end */
1937 cnt = (sizeof(buf) < pos) ? sizeof(buf) : pos;
1938 if (fseek(logfp, pos - cnt, SEEK_SET)) {
1939 ret = error("cannot seek back reflog for %s: %s",
1940 refname, strerror(errno));
1941 break;
1942 }
1943 nread = fread(buf, cnt, 1, logfp);
1944 if (nread != 1) {
1945 ret = error("cannot read %d bytes from reflog for %s: %s",
1946 cnt, refname, strerror(errno));
1947 break;
1948 }
1949 pos -= cnt;
1950
1951 scanp = endp = buf + cnt;
1952 if (at_tail && scanp[-1] == '\n')
1953 /* Looking at the final LF at the end of the file */
1954 scanp--;
1955 at_tail = 0;
1956
1957 while (buf < scanp) {
1958 /*
1959 * terminating LF of the previous line, or the beginning
1960 * of the buffer.
1961 */
1962 char *bp;
1963
1964 bp = find_beginning_of_line(buf, scanp);
1965
1966 if (*bp == '\n') {
1967 /*
1968 * The newline is the end of the previous line,
1969 * so we know we have complete line starting
1970 * at (bp + 1). Prefix it onto any prior data
1971 * we collected for the line and process it.
1972 */
1973 strbuf_splice(&sb, 0, 0, bp + 1, endp - (bp + 1));
1974 scanp = bp;
1975 endp = bp + 1;
1976 ret = show_one_reflog_ent(&sb, fn, cb_data);
1977 strbuf_reset(&sb);
1978 if (ret)
1979 break;
1980 } else if (!pos) {
1981 /*
1982 * We are at the start of the buffer, and the
1983 * start of the file; there is no previous
1984 * line, and we have everything for this one.
1985 * Process it, and we can end the loop.
1986 */
1987 strbuf_splice(&sb, 0, 0, buf, endp - buf);
1988 ret = show_one_reflog_ent(&sb, fn, cb_data);
1989 strbuf_reset(&sb);
1990 break;
1991 }
1992
1993 if (bp == buf) {
1994 /*
1995 * We are at the start of the buffer, and there
1996 * is more file to read backwards. Which means
1997 * we are in the middle of a line. Note that we
1998 * may get here even if *bp was a newline; that
1999 * just means we are at the exact end of the
2000 * previous line, rather than some spot in the
2001 * middle.
2002 *
2003 * Save away what we have to be combined with
2004 * the data from the next read.
2005 */
2006 strbuf_splice(&sb, 0, 0, buf, endp - buf);
2007 break;
2008 }
2009 }
2010
2011 }
2012 if (!ret && sb.len)
2013 die("BUG: reverse reflog parser had leftover data");
2014
2015 fclose(logfp);
2016 strbuf_release(&sb);
2017 return ret;
2018 }
2019
2020 static int files_for_each_reflog_ent(struct ref_store *ref_store,
2021 const char *refname,
2022 each_reflog_ent_fn fn, void *cb_data)
2023 {
2024 struct files_ref_store *refs =
2025 files_downcast(ref_store, REF_STORE_READ,
2026 "for_each_reflog_ent");
2027 FILE *logfp;
2028 struct strbuf sb = STRBUF_INIT;
2029 int ret = 0;
2030
2031 files_reflog_path(refs, &sb, refname);
2032 logfp = fopen(sb.buf, "r");
2033 strbuf_release(&sb);
2034 if (!logfp)
2035 return -1;
2036
2037 while (!ret && !strbuf_getwholeline(&sb, logfp, '\n'))
2038 ret = show_one_reflog_ent(&sb, fn, cb_data);
2039 fclose(logfp);
2040 strbuf_release(&sb);
2041 return ret;
2042 }
2043
2044 struct files_reflog_iterator {
2045 struct ref_iterator base;
2046
2047 struct ref_store *ref_store;
2048 struct dir_iterator *dir_iterator;
2049 struct object_id oid;
2050 };
2051
2052 static int files_reflog_iterator_advance(struct ref_iterator *ref_iterator)
2053 {
2054 struct files_reflog_iterator *iter =
2055 (struct files_reflog_iterator *)ref_iterator;
2056 struct dir_iterator *diter = iter->dir_iterator;
2057 int ok;
2058
2059 while ((ok = dir_iterator_advance(diter)) == ITER_OK) {
2060 int flags;
2061
2062 if (!S_ISREG(diter->st.st_mode))
2063 continue;
2064 if (diter->basename[0] == '.')
2065 continue;
2066 if (ends_with(diter->basename, ".lock"))
2067 continue;
2068
2069 if (refs_read_ref_full(iter->ref_store,
2070 diter->relative_path, 0,
2071 &iter->oid, &flags)) {
2072 error("bad ref for %s", diter->path.buf);
2073 continue;
2074 }
2075
2076 iter->base.refname = diter->relative_path;
2077 iter->base.oid = &iter->oid;
2078 iter->base.flags = flags;
2079 return ITER_OK;
2080 }
2081
2082 iter->dir_iterator = NULL;
2083 if (ref_iterator_abort(ref_iterator) == ITER_ERROR)
2084 ok = ITER_ERROR;
2085 return ok;
2086 }
2087
2088 static int files_reflog_iterator_peel(struct ref_iterator *ref_iterator,
2089 struct object_id *peeled)
2090 {
2091 die("BUG: ref_iterator_peel() called for reflog_iterator");
2092 }
2093
2094 static int files_reflog_iterator_abort(struct ref_iterator *ref_iterator)
2095 {
2096 struct files_reflog_iterator *iter =
2097 (struct files_reflog_iterator *)ref_iterator;
2098 int ok = ITER_DONE;
2099
2100 if (iter->dir_iterator)
2101 ok = dir_iterator_abort(iter->dir_iterator);
2102
2103 base_ref_iterator_free(ref_iterator);
2104 return ok;
2105 }
2106
2107 static struct ref_iterator_vtable files_reflog_iterator_vtable = {
2108 files_reflog_iterator_advance,
2109 files_reflog_iterator_peel,
2110 files_reflog_iterator_abort
2111 };
2112
2113 static struct ref_iterator *reflog_iterator_begin(struct ref_store *ref_store,
2114 const char *gitdir)
2115 {
2116 struct files_reflog_iterator *iter = xcalloc(1, sizeof(*iter));
2117 struct ref_iterator *ref_iterator = &iter->base;
2118 struct strbuf sb = STRBUF_INIT;
2119
2120 base_ref_iterator_init(ref_iterator, &files_reflog_iterator_vtable, 0);
2121 strbuf_addf(&sb, "%s/logs", gitdir);
2122 iter->dir_iterator = dir_iterator_begin(sb.buf);
2123 iter->ref_store = ref_store;
2124 strbuf_release(&sb);
2125
2126 return ref_iterator;
2127 }
2128
2129 static enum iterator_selection reflog_iterator_select(
2130 struct ref_iterator *iter_worktree,
2131 struct ref_iterator *iter_common,
2132 void *cb_data)
2133 {
2134 if (iter_worktree) {
2135 /*
2136 * We're a bit loose here. We probably should ignore
2137 * common refs if they are accidentally added as
2138 * per-worktree refs.
2139 */
2140 return ITER_SELECT_0;
2141 } else if (iter_common) {
2142 if (ref_type(iter_common->refname) == REF_TYPE_NORMAL)
2143 return ITER_SELECT_1;
2144
2145 /*
2146 * The main ref store may contain main worktree's
2147 * per-worktree refs, which should be ignored
2148 */
2149 return ITER_SKIP_1;
2150 } else
2151 return ITER_DONE;
2152 }
2153
2154 static struct ref_iterator *files_reflog_iterator_begin(struct ref_store *ref_store)
2155 {
2156 struct files_ref_store *refs =
2157 files_downcast(ref_store, REF_STORE_READ,
2158 "reflog_iterator_begin");
2159
2160 if (!strcmp(refs->gitdir, refs->gitcommondir)) {
2161 return reflog_iterator_begin(ref_store, refs->gitcommondir);
2162 } else {
2163 return merge_ref_iterator_begin(
2164 0,
2165 reflog_iterator_begin(ref_store, refs->gitdir),
2166 reflog_iterator_begin(ref_store, refs->gitcommondir),
2167 reflog_iterator_select, refs);
2168 }
2169 }
2170
2171 /*
2172 * If update is a direct update of head_ref (the reference pointed to
2173 * by HEAD), then add an extra REF_LOG_ONLY update for HEAD.
2174 */
2175 static int split_head_update(struct ref_update *update,
2176 struct ref_transaction *transaction,
2177 const char *head_ref,
2178 struct string_list *affected_refnames,
2179 struct strbuf *err)
2180 {
2181 struct string_list_item *item;
2182 struct ref_update *new_update;
2183
2184 if ((update->flags & REF_LOG_ONLY) ||
2185 (update->flags & REF_IS_PRUNING) ||
2186 (update->flags & REF_UPDATE_VIA_HEAD))
2187 return 0;
2188
2189 if (strcmp(update->refname, head_ref))
2190 return 0;
2191
2192 /*
2193 * First make sure that HEAD is not already in the
2194 * transaction. This check is O(lg N) in the transaction
2195 * size, but it happens at most once per transaction.
2196 */
2197 if (string_list_has_string(affected_refnames, "HEAD")) {
2198 /* An entry already existed */
2199 strbuf_addf(err,
2200 "multiple updates for 'HEAD' (including one "
2201 "via its referent '%s') are not allowed",
2202 update->refname);
2203 return TRANSACTION_NAME_CONFLICT;
2204 }
2205
2206 new_update = ref_transaction_add_update(
2207 transaction, "HEAD",
2208 update->flags | REF_LOG_ONLY | REF_NO_DEREF,
2209 &update->new_oid, &update->old_oid,
2210 update->msg);
2211
2212 /*
2213 * Add "HEAD". This insertion is O(N) in the transaction
2214 * size, but it happens at most once per transaction.
2215 * Add new_update->refname instead of a literal "HEAD".
2216 */
2217 if (strcmp(new_update->refname, "HEAD"))
2218 BUG("%s unexpectedly not 'HEAD'", new_update->refname);
2219 item = string_list_insert(affected_refnames, new_update->refname);
2220 item->util = new_update;
2221
2222 return 0;
2223 }
2224
2225 /*
2226 * update is for a symref that points at referent and doesn't have
2227 * REF_NO_DEREF set. Split it into two updates:
2228 * - The original update, but with REF_LOG_ONLY and REF_NO_DEREF set
2229 * - A new, separate update for the referent reference
2230 * Note that the new update will itself be subject to splitting when
2231 * the iteration gets to it.
2232 */
2233 static int split_symref_update(struct files_ref_store *refs,
2234 struct ref_update *update,
2235 const char *referent,
2236 struct ref_transaction *transaction,
2237 struct string_list *affected_refnames,
2238 struct strbuf *err)
2239 {
2240 struct string_list_item *item;
2241 struct ref_update *new_update;
2242 unsigned int new_flags;
2243
2244 /*
2245 * First make sure that referent is not already in the
2246 * transaction. This check is O(lg N) in the transaction
2247 * size, but it happens at most once per symref in a
2248 * transaction.
2249 */
2250 if (string_list_has_string(affected_refnames, referent)) {
2251 /* An entry already exists */
2252 strbuf_addf(err,
2253 "multiple updates for '%s' (including one "
2254 "via symref '%s') are not allowed",
2255 referent, update->refname);
2256 return TRANSACTION_NAME_CONFLICT;
2257 }
2258
2259 new_flags = update->flags;
2260 if (!strcmp(update->refname, "HEAD")) {
2261 /*
2262 * Record that the new update came via HEAD, so that
2263 * when we process it, split_head_update() doesn't try
2264 * to add another reflog update for HEAD. Note that
2265 * this bit will be propagated if the new_update
2266 * itself needs to be split.
2267 */
2268 new_flags |= REF_UPDATE_VIA_HEAD;
2269 }
2270
2271 new_update = ref_transaction_add_update(
2272 transaction, referent, new_flags,
2273 &update->new_oid, &update->old_oid,
2274 update->msg);
2275
2276 new_update->parent_update = update;
2277
2278 /*
2279 * Change the symbolic ref update to log only. Also, it
2280 * doesn't need to check its old OID value, as that will be
2281 * done when new_update is processed.
2282 */
2283 update->flags |= REF_LOG_ONLY | REF_NO_DEREF;
2284 update->flags &= ~REF_HAVE_OLD;
2285
2286 /*
2287 * Add the referent. This insertion is O(N) in the transaction
2288 * size, but it happens at most once per symref in a
2289 * transaction. Make sure to add new_update->refname, which will
2290 * be valid as long as affected_refnames is in use, and NOT
2291 * referent, which might soon be freed by our caller.
2292 */
2293 item = string_list_insert(affected_refnames, new_update->refname);
2294 if (item->util)
2295 BUG("%s unexpectedly found in affected_refnames",
2296 new_update->refname);
2297 item->util = new_update;
2298
2299 return 0;
2300 }
2301
2302 /*
2303 * Return the refname under which update was originally requested.
2304 */
2305 static const char *original_update_refname(struct ref_update *update)
2306 {
2307 while (update->parent_update)
2308 update = update->parent_update;
2309
2310 return update->refname;
2311 }
2312
2313 /*
2314 * Check whether the REF_HAVE_OLD and old_oid values stored in update
2315 * are consistent with oid, which is the reference's current value. If
2316 * everything is OK, return 0; otherwise, write an error message to
2317 * err and return -1.
2318 */
2319 static int check_old_oid(struct ref_update *update, struct object_id *oid,
2320 struct strbuf *err)
2321 {
2322 if (!(update->flags & REF_HAVE_OLD) ||
2323 !oidcmp(oid, &update->old_oid))
2324 return 0;
2325
2326 if (is_null_oid(&update->old_oid))
2327 strbuf_addf(err, "cannot lock ref '%s': "
2328 "reference already exists",
2329 original_update_refname(update));
2330 else if (is_null_oid(oid))
2331 strbuf_addf(err, "cannot lock ref '%s': "
2332 "reference is missing but expected %s",
2333 original_update_refname(update),
2334 oid_to_hex(&update->old_oid));
2335 else
2336 strbuf_addf(err, "cannot lock ref '%s': "
2337 "is at %s but expected %s",
2338 original_update_refname(update),
2339 oid_to_hex(oid),
2340 oid_to_hex(&update->old_oid));
2341
2342 return -1;
2343 }
2344
2345 /*
2346 * Prepare for carrying out update:
2347 * - Lock the reference referred to by update.
2348 * - Read the reference under lock.
2349 * - Check that its old OID value (if specified) is correct, and in
2350 * any case record it in update->lock->old_oid for later use when
2351 * writing the reflog.
2352 * - If it is a symref update without REF_NO_DEREF, split it up into a
2353 * REF_LOG_ONLY update of the symref and add a separate update for
2354 * the referent to transaction.
2355 * - If it is an update of head_ref, add a corresponding REF_LOG_ONLY
2356 * update of HEAD.
2357 */
2358 static int lock_ref_for_update(struct files_ref_store *refs,
2359 struct ref_update *update,
2360 struct ref_transaction *transaction,
2361 const char *head_ref,
2362 struct string_list *affected_refnames,
2363 struct strbuf *err)
2364 {
2365 struct strbuf referent = STRBUF_INIT;
2366 int mustexist = (update->flags & REF_HAVE_OLD) &&
2367 !is_null_oid(&update->old_oid);
2368 int ret = 0;
2369 struct ref_lock *lock;
2370
2371 files_assert_main_repository(refs, "lock_ref_for_update");
2372
2373 if ((update->flags & REF_HAVE_NEW) && is_null_oid(&update->new_oid))
2374 update->flags |= REF_DELETING;
2375
2376 if (head_ref) {
2377 ret = split_head_update(update, transaction, head_ref,
2378 affected_refnames, err);
2379 if (ret)
2380 goto out;
2381 }
2382
2383 ret = lock_raw_ref(refs, update->refname, mustexist,
2384 affected_refnames, NULL,
2385 &lock, &referent,
2386 &update->type, err);
2387 if (ret) {
2388 char *reason;
2389
2390 reason = strbuf_detach(err, NULL);
2391 strbuf_addf(err, "cannot lock ref '%s': %s",
2392 original_update_refname(update), reason);
2393 free(reason);
2394 goto out;
2395 }
2396
2397 update->backend_data = lock;
2398
2399 if (update->type & REF_ISSYMREF) {
2400 if (update->flags & REF_NO_DEREF) {
2401 /*
2402 * We won't be reading the referent as part of
2403 * the transaction, so we have to read it here
2404 * to record and possibly check old_oid:
2405 */
2406 if (refs_read_ref_full(&refs->base,
2407 referent.buf, 0,
2408 &lock->old_oid, NULL)) {
2409 if (update->flags & REF_HAVE_OLD) {
2410 strbuf_addf(err, "cannot lock ref '%s': "
2411 "error reading reference",
2412 original_update_refname(update));
2413 ret = TRANSACTION_GENERIC_ERROR;
2414 goto out;
2415 }
2416 } else if (check_old_oid(update, &lock->old_oid, err)) {
2417 ret = TRANSACTION_GENERIC_ERROR;
2418 goto out;
2419 }
2420 } else {
2421 /*
2422 * Create a new update for the reference this
2423 * symref is pointing at. Also, we will record
2424 * and verify old_oid for this update as part
2425 * of processing the split-off update, so we
2426 * don't have to do it here.
2427 */
2428 ret = split_symref_update(refs, update,
2429 referent.buf, transaction,
2430 affected_refnames, err);
2431 if (ret)
2432 goto out;
2433 }
2434 } else {
2435 struct ref_update *parent_update;
2436
2437 if (check_old_oid(update, &lock->old_oid, err)) {
2438 ret = TRANSACTION_GENERIC_ERROR;
2439 goto out;
2440 }
2441
2442 /*
2443 * If this update is happening indirectly because of a
2444 * symref update, record the old OID in the parent
2445 * update:
2446 */
2447 for (parent_update = update->parent_update;
2448 parent_update;
2449 parent_update = parent_update->parent_update) {
2450 struct ref_lock *parent_lock = parent_update->backend_data;
2451 oidcpy(&parent_lock->old_oid, &lock->old_oid);
2452 }
2453 }
2454
2455 if ((update->flags & REF_HAVE_NEW) &&
2456 !(update->flags & REF_DELETING) &&
2457 !(update->flags & REF_LOG_ONLY)) {
2458 if (!(update->type & REF_ISSYMREF) &&
2459 !oidcmp(&lock->old_oid, &update->new_oid)) {
2460 /*
2461 * The reference already has the desired
2462 * value, so we don't need to write it.
2463 */
2464 } else if (write_ref_to_lockfile(lock, &update->new_oid,
2465 err)) {
2466 char *write_err = strbuf_detach(err, NULL);
2467
2468 /*
2469 * The lock was freed upon failure of
2470 * write_ref_to_lockfile():
2471 */
2472 update->backend_data = NULL;
2473 strbuf_addf(err,
2474 "cannot update ref '%s': %s",
2475 update->refname, write_err);
2476 free(write_err);
2477 ret = TRANSACTION_GENERIC_ERROR;
2478 goto out;
2479 } else {
2480 update->flags |= REF_NEEDS_COMMIT;
2481 }
2482 }
2483 if (!(update->flags & REF_NEEDS_COMMIT)) {
2484 /*
2485 * We didn't call write_ref_to_lockfile(), so
2486 * the lockfile is still open. Close it to
2487 * free up the file descriptor:
2488 */
2489 if (close_ref_gently(lock)) {
2490 strbuf_addf(err, "couldn't close '%s.lock'",
2491 update->refname);
2492 ret = TRANSACTION_GENERIC_ERROR;
2493 goto out;
2494 }
2495 }
2496
2497 out:
2498 strbuf_release(&referent);
2499 return ret;
2500 }
2501
2502 struct files_transaction_backend_data {
2503 struct ref_transaction *packed_transaction;
2504 int packed_refs_locked;
2505 };
2506
2507 /*
2508 * Unlock any references in `transaction` that are still locked, and
2509 * mark the transaction closed.
2510 */
2511 static void files_transaction_cleanup(struct files_ref_store *refs,
2512 struct ref_transaction *transaction)
2513 {
2514 size_t i;
2515 struct files_transaction_backend_data *backend_data =
2516 transaction->backend_data;
2517 struct strbuf err = STRBUF_INIT;
2518
2519 for (i = 0; i < transaction->nr; i++) {
2520 struct ref_update *update = transaction->updates[i];
2521 struct ref_lock *lock = update->backend_data;
2522
2523 if (lock) {
2524 unlock_ref(lock);
2525 update->backend_data = NULL;
2526 }
2527 }
2528
2529 if (backend_data->packed_transaction &&
2530 ref_transaction_abort(backend_data->packed_transaction, &err)) {
2531 error("error aborting transaction: %s", err.buf);
2532 strbuf_release(&err);
2533 }
2534
2535 if (backend_data->packed_refs_locked)
2536 packed_refs_unlock(refs->packed_ref_store);
2537
2538 free(backend_data);
2539
2540 transaction->state = REF_TRANSACTION_CLOSED;
2541 }
2542
2543 static int files_transaction_prepare(struct ref_store *ref_store,
2544 struct ref_transaction *transaction,
2545 struct strbuf *err)
2546 {
2547 struct files_ref_store *refs =
2548 files_downcast(ref_store, REF_STORE_WRITE,
2549 "ref_transaction_prepare");
2550 size_t i;
2551 int ret = 0;
2552 struct string_list affected_refnames = STRING_LIST_INIT_NODUP;
2553 char *head_ref = NULL;
2554 int head_type;
2555 struct files_transaction_backend_data *backend_data;
2556 struct ref_transaction *packed_transaction = NULL;
2557
2558 assert(err);
2559
2560 if (!transaction->nr)
2561 goto cleanup;
2562
2563 backend_data = xcalloc(1, sizeof(*backend_data));
2564 transaction->backend_data = backend_data;
2565
2566 /*
2567 * Fail if a refname appears more than once in the
2568 * transaction. (If we end up splitting up any updates using
2569 * split_symref_update() or split_head_update(), those
2570 * functions will check that the new updates don't have the
2571 * same refname as any existing ones.) Also fail if any of the
2572 * updates use REF_IS_PRUNING without REF_NO_DEREF.
2573 */
2574 for (i = 0; i < transaction->nr; i++) {
2575 struct ref_update *update = transaction->updates[i];
2576 struct string_list_item *item =
2577 string_list_append(&affected_refnames, update->refname);
2578
2579 if ((update->flags & REF_IS_PRUNING) &&
2580 !(update->flags & REF_NO_DEREF))
2581 BUG("REF_IS_PRUNING set without REF_NO_DEREF");
2582
2583 /*
2584 * We store a pointer to update in item->util, but at
2585 * the moment we never use the value of this field
2586 * except to check whether it is non-NULL.
2587 */
2588 item->util = update;
2589 }
2590 string_list_sort(&affected_refnames);
2591 if (ref_update_reject_duplicates(&affected_refnames, err)) {
2592 ret = TRANSACTION_GENERIC_ERROR;
2593 goto cleanup;
2594 }
2595
2596 /*
2597 * Special hack: If a branch is updated directly and HEAD
2598 * points to it (may happen on the remote side of a push
2599 * for example) then logically the HEAD reflog should be
2600 * updated too.
2601 *
2602 * A generic solution would require reverse symref lookups,
2603 * but finding all symrefs pointing to a given branch would be
2604 * rather costly for this rare event (the direct update of a
2605 * branch) to be worth it. So let's cheat and check with HEAD
2606 * only, which should cover 99% of all usage scenarios (even
2607 * 100% of the default ones).
2608 *
2609 * So if HEAD is a symbolic reference, then record the name of
2610 * the reference that it points to. If we see an update of
2611 * head_ref within the transaction, then split_head_update()
2612 * arranges for the reflog of HEAD to be updated, too.
2613 */
2614 head_ref = refs_resolve_refdup(ref_store, "HEAD",
2615 RESOLVE_REF_NO_RECURSE,
2616 NULL, &head_type);
2617
2618 if (head_ref && !(head_type & REF_ISSYMREF)) {
2619 FREE_AND_NULL(head_ref);
2620 }
2621
2622 /*
2623 * Acquire all locks, verify old values if provided, check
2624 * that new values are valid, and write new values to the
2625 * lockfiles, ready to be activated. Only keep one lockfile
2626 * open at a time to avoid running out of file descriptors.
2627 * Note that lock_ref_for_update() might append more updates
2628 * to the transaction.
2629 */
2630 for (i = 0; i < transaction->nr; i++) {
2631 struct ref_update *update = transaction->updates[i];
2632
2633 ret = lock_ref_for_update(refs, update, transaction,
2634 head_ref, &affected_refnames, err);
2635 if (ret)
2636 goto cleanup;
2637
2638 if (update->flags & REF_DELETING &&
2639 !(update->flags & REF_LOG_ONLY) &&
2640 !(update->flags & REF_IS_PRUNING)) {
2641 /*
2642 * This reference has to be deleted from
2643 * packed-refs if it exists there.
2644 */
2645 if (!packed_transaction) {
2646 packed_transaction = ref_store_transaction_begin(
2647 refs->packed_ref_store, err);
2648 if (!packed_transaction) {
2649 ret = TRANSACTION_GENERIC_ERROR;
2650 goto cleanup;
2651 }
2652
2653 backend_data->packed_transaction =
2654 packed_transaction;
2655 }
2656
2657 ref_transaction_add_update(
2658 packed_transaction, update->refname,
2659 REF_HAVE_NEW | REF_NO_DEREF,
2660 &update->new_oid, NULL,
2661 NULL);
2662 }
2663 }
2664
2665 if (packed_transaction) {
2666 if (packed_refs_lock(refs->packed_ref_store, 0, err)) {
2667 ret = TRANSACTION_GENERIC_ERROR;
2668 goto cleanup;
2669 }
2670 backend_data->packed_refs_locked = 1;
2671
2672 if (is_packed_transaction_needed(refs->packed_ref_store,
2673 packed_transaction)) {
2674 ret = ref_transaction_prepare(packed_transaction, err);
2675 } else {
2676 /*
2677 * We can skip rewriting the `packed-refs`
2678 * file. But we do need to leave it locked, so
2679 * that somebody else doesn't pack a reference
2680 * that we are trying to delete.
2681 */
2682 if (ref_transaction_abort(packed_transaction, err)) {
2683 ret = TRANSACTION_GENERIC_ERROR;
2684 goto cleanup;
2685 }
2686 backend_data->packed_transaction = NULL;
2687 }
2688 }
2689
2690 cleanup:
2691 free(head_ref);
2692 string_list_clear(&affected_refnames, 0);
2693
2694 if (ret)
2695 files_transaction_cleanup(refs, transaction);
2696 else
2697 transaction->state = REF_TRANSACTION_PREPARED;
2698
2699 return ret;
2700 }
2701
2702 static int files_transaction_finish(struct ref_store *ref_store,
2703 struct ref_transaction *transaction,
2704 struct strbuf *err)
2705 {
2706 struct files_ref_store *refs =
2707 files_downcast(ref_store, 0, "ref_transaction_finish");
2708 size_t i;
2709 int ret = 0;
2710 struct strbuf sb = STRBUF_INIT;
2711 struct files_transaction_backend_data *backend_data;
2712 struct ref_transaction *packed_transaction;
2713
2714
2715 assert(err);
2716
2717 if (!transaction->nr) {
2718 transaction->state = REF_TRANSACTION_CLOSED;
2719 return 0;
2720 }
2721
2722 backend_data = transaction->backend_data;
2723 packed_transaction = backend_data->packed_transaction;
2724
2725 /* Perform updates first so live commits remain referenced */
2726 for (i = 0; i < transaction->nr; i++) {
2727 struct ref_update *update = transaction->updates[i];
2728 struct ref_lock *lock = update->backend_data;
2729
2730 if (update->flags & REF_NEEDS_COMMIT ||
2731 update->flags & REF_LOG_ONLY) {
2732 if (files_log_ref_write(refs,
2733 lock->ref_name,
2734 &lock->old_oid,
2735 &update->new_oid,
2736 update->msg, update->flags,
2737 err)) {
2738 char *old_msg = strbuf_detach(err, NULL);
2739
2740 strbuf_addf(err, "cannot update the ref '%s': %s",
2741 lock->ref_name, old_msg);
2742 free(old_msg);
2743 unlock_ref(lock);
2744 update->backend_data = NULL;
2745 ret = TRANSACTION_GENERIC_ERROR;
2746 goto cleanup;
2747 }
2748 }
2749 if (update->flags & REF_NEEDS_COMMIT) {
2750 clear_loose_ref_cache(refs);
2751 if (commit_ref(lock)) {
2752 strbuf_addf(err, "couldn't set '%s'", lock->ref_name);
2753 unlock_ref(lock);
2754 update->backend_data = NULL;
2755 ret = TRANSACTION_GENERIC_ERROR;
2756 goto cleanup;
2757 }
2758 }
2759 }
2760
2761 /*
2762 * Now that updates are safely completed, we can perform
2763 * deletes. First delete the reflogs of any references that
2764 * will be deleted, since (in the unexpected event of an
2765 * error) leaving a reference without a reflog is less bad
2766 * than leaving a reflog without a reference (the latter is a
2767 * mildly invalid repository state):
2768 */
2769 for (i = 0; i < transaction->nr; i++) {
2770 struct ref_update *update = transaction->updates[i];
2771 if (update->flags & REF_DELETING &&
2772 !(update->flags & REF_LOG_ONLY) &&
2773 !(update->flags & REF_IS_PRUNING)) {
2774 strbuf_reset(&sb);
2775 files_reflog_path(refs, &sb, update->refname);
2776 if (!unlink_or_warn(sb.buf))
2777 try_remove_empty_parents(refs, update->refname,
2778 REMOVE_EMPTY_PARENTS_REFLOG);
2779 }
2780 }
2781
2782 /*
2783 * Perform deletes now that updates are safely completed.
2784 *
2785 * First delete any packed versions of the references, while
2786 * retaining the packed-refs lock:
2787 */
2788 if (packed_transaction) {
2789 ret = ref_transaction_commit(packed_transaction, err);
2790 ref_transaction_free(packed_transaction);
2791 packed_transaction = NULL;
2792 backend_data->packed_transaction = NULL;
2793 if (ret)
2794 goto cleanup;
2795 }
2796
2797 /* Now delete the loose versions of the references: */
2798 for (i = 0; i < transaction->nr; i++) {
2799 struct ref_update *update = transaction->updates[i];
2800 struct ref_lock *lock = update->backend_data;
2801
2802 if (update->flags & REF_DELETING &&
2803 !(update->flags & REF_LOG_ONLY)) {
2804 if (!(update->type & REF_ISPACKED) ||
2805 update->type & REF_ISSYMREF) {
2806 /* It is a loose reference. */
2807 strbuf_reset(&sb);
2808 files_ref_path(refs, &sb, lock->ref_name);
2809 if (unlink_or_msg(sb.buf, err)) {
2810 ret = TRANSACTION_GENERIC_ERROR;
2811 goto cleanup;
2812 }
2813 update->flags |= REF_DELETED_LOOSE;
2814 }
2815 }
2816 }
2817
2818 clear_loose_ref_cache(refs);
2819
2820 cleanup:
2821 files_transaction_cleanup(refs, transaction);
2822
2823 for (i = 0; i < transaction->nr; i++) {
2824 struct ref_update *update = transaction->updates[i];
2825
2826 if (update->flags & REF_DELETED_LOOSE) {
2827 /*
2828 * The loose reference was deleted. Delete any
2829 * empty parent directories. (Note that this
2830 * can only work because we have already
2831 * removed the lockfile.)
2832 */
2833 try_remove_empty_parents(refs, update->refname,
2834 REMOVE_EMPTY_PARENTS_REF);
2835 }
2836 }
2837
2838 strbuf_release(&sb);
2839 return ret;
2840 }
2841
2842 static int files_transaction_abort(struct ref_store *ref_store,
2843 struct ref_transaction *transaction,
2844 struct strbuf *err)
2845 {
2846 struct files_ref_store *refs =
2847 files_downcast(ref_store, 0, "ref_transaction_abort");
2848
2849 files_transaction_cleanup(refs, transaction);
2850 return 0;
2851 }
2852
2853 static int ref_present(const char *refname,
2854 const struct object_id *oid, int flags, void *cb_data)
2855 {
2856 struct string_list *affected_refnames = cb_data;
2857
2858 return string_list_has_string(affected_refnames, refname);
2859 }
2860
2861 static int files_initial_transaction_commit(struct ref_store *ref_store,
2862 struct ref_transaction *transaction,
2863 struct strbuf *err)
2864 {
2865 struct files_ref_store *refs =
2866 files_downcast(ref_store, REF_STORE_WRITE,
2867 "initial_ref_transaction_commit");
2868 size_t i;
2869 int ret = 0;
2870 struct string_list affected_refnames = STRING_LIST_INIT_NODUP;
2871 struct ref_transaction *packed_transaction = NULL;
2872
2873 assert(err);
2874
2875 if (transaction->state != REF_TRANSACTION_OPEN)
2876 die("BUG: commit called for transaction that is not open");
2877
2878 /* Fail if a refname appears more than once in the transaction: */
2879 for (i = 0; i < transaction->nr; i++)
2880 string_list_append(&affected_refnames,
2881 transaction->updates[i]->refname);
2882 string_list_sort(&affected_refnames);
2883 if (ref_update_reject_duplicates(&affected_refnames, err)) {
2884 ret = TRANSACTION_GENERIC_ERROR;
2885 goto cleanup;
2886 }
2887
2888 /*
2889 * It's really undefined to call this function in an active
2890 * repository or when there are existing references: we are
2891 * only locking and changing packed-refs, so (1) any
2892 * simultaneous processes might try to change a reference at
2893 * the same time we do, and (2) any existing loose versions of
2894 * the references that we are setting would have precedence
2895 * over our values. But some remote helpers create the remote
2896 * "HEAD" and "master" branches before calling this function,
2897 * so here we really only check that none of the references
2898 * that we are creating already exists.
2899 */
2900 if (refs_for_each_rawref(&refs->base, ref_present,
2901 &affected_refnames))
2902 die("BUG: initial ref transaction called with existing refs");
2903
2904 packed_transaction = ref_store_transaction_begin(refs->packed_ref_store, err);
2905 if (!packed_transaction) {
2906 ret = TRANSACTION_GENERIC_ERROR;
2907 goto cleanup;
2908 }
2909
2910 for (i = 0; i < transaction->nr; i++) {
2911 struct ref_update *update = transaction->updates[i];
2912
2913 if ((update->flags & REF_HAVE_OLD) &&
2914 !is_null_oid(&update->old_oid))
2915 die("BUG: initial ref transaction with old_sha1 set");
2916 if (refs_verify_refname_available(&refs->base, update->refname,
2917 &affected_refnames, NULL,
2918 err)) {
2919 ret = TRANSACTION_NAME_CONFLICT;
2920 goto cleanup;
2921 }
2922
2923 /*
2924 * Add a reference creation for this reference to the
2925 * packed-refs transaction:
2926 */
2927 ref_transaction_add_update(packed_transaction, update->refname,
2928 update->flags & ~REF_HAVE_OLD,
2929 &update->new_oid, &update->old_oid,
2930 NULL);
2931 }
2932
2933 if (packed_refs_lock(refs->packed_ref_store, 0, err)) {
2934 ret = TRANSACTION_GENERIC_ERROR;
2935 goto cleanup;
2936 }
2937
2938 if (initial_ref_transaction_commit(packed_transaction, err)) {
2939 ret = TRANSACTION_GENERIC_ERROR;
2940 }
2941
2942 packed_refs_unlock(refs->packed_ref_store);
2943 cleanup:
2944 if (packed_transaction)
2945 ref_transaction_free(packed_transaction);
2946 transaction->state = REF_TRANSACTION_CLOSED;
2947 string_list_clear(&affected_refnames, 0);
2948 return ret;
2949 }
2950
2951 struct expire_reflog_cb {
2952 unsigned int flags;
2953 reflog_expiry_should_prune_fn *should_prune_fn;
2954 void *policy_cb;
2955 FILE *newlog;
2956 struct object_id last_kept_oid;
2957 };
2958
2959 static int expire_reflog_ent(struct object_id *ooid, struct object_id *noid,
2960 const char *email, timestamp_t timestamp, int tz,
2961 const char *message, void *cb_data)
2962 {
2963 struct expire_reflog_cb *cb = cb_data;
2964 struct expire_reflog_policy_cb *policy_cb = cb->policy_cb;
2965
2966 if (cb->flags & EXPIRE_REFLOGS_REWRITE)
2967 ooid = &cb->last_kept_oid;
2968
2969 if ((*cb->should_prune_fn)(ooid, noid, email, timestamp, tz,
2970 message, policy_cb)) {
2971 if (!cb->newlog)
2972 printf("would prune %s", message);
2973 else if (cb->flags & EXPIRE_REFLOGS_VERBOSE)
2974 printf("prune %s", message);
2975 } else {
2976 if (cb->newlog) {
2977 fprintf(cb->newlog, "%s %s %s %"PRItime" %+05d\t%s",
2978 oid_to_hex(ooid), oid_to_hex(noid),
2979 email, timestamp, tz, message);
2980 oidcpy(&cb->last_kept_oid, noid);
2981 }
2982 if (cb->flags & EXPIRE_REFLOGS_VERBOSE)
2983 printf("keep %s", message);
2984 }
2985 return 0;
2986 }
2987
2988 static int files_reflog_expire(struct ref_store *ref_store,
2989 const char *refname, const struct object_id *oid,
2990 unsigned int flags,
2991 reflog_expiry_prepare_fn prepare_fn,
2992 reflog_expiry_should_prune_fn should_prune_fn,
2993 reflog_expiry_cleanup_fn cleanup_fn,
2994 void *policy_cb_data)
2995 {
2996 struct files_ref_store *refs =
2997 files_downcast(ref_store, REF_STORE_WRITE, "reflog_expire");
2998 static struct lock_file reflog_lock;
2999 struct expire_reflog_cb cb;
3000 struct ref_lock *lock;
3001 struct strbuf log_file_sb = STRBUF_INIT;
3002 char *log_file;
3003 int status = 0;
3004 int type;
3005 struct strbuf err = STRBUF_INIT;
3006
3007 memset(&cb, 0, sizeof(cb));
3008 cb.flags = flags;
3009 cb.policy_cb = policy_cb_data;
3010 cb.should_prune_fn = should_prune_fn;
3011
3012 /*
3013 * The reflog file is locked by holding the lock on the
3014 * reference itself, plus we might need to update the
3015 * reference if --updateref was specified:
3016 */
3017 lock = lock_ref_oid_basic(refs, refname, oid,
3018 NULL, NULL, REF_NO_DEREF,
3019 &type, &err);
3020 if (!lock) {
3021 error("cannot lock ref '%s': %s", refname, err.buf);
3022 strbuf_release(&err);
3023 return -1;
3024 }
3025 if (!refs_reflog_exists(ref_store, refname)) {
3026 unlock_ref(lock);
3027 return 0;
3028 }
3029
3030 files_reflog_path(refs, &log_file_sb, refname);
3031 log_file = strbuf_detach(&log_file_sb, NULL);
3032 if (!(flags & EXPIRE_REFLOGS_DRY_RUN)) {
3033 /*
3034 * Even though holding $GIT_DIR/logs/$reflog.lock has
3035 * no locking implications, we use the lock_file
3036 * machinery here anyway because it does a lot of the
3037 * work we need, including cleaning up if the program
3038 * exits unexpectedly.
3039 */
3040 if (hold_lock_file_for_update(&reflog_lock, log_file, 0) < 0) {
3041 struct strbuf err = STRBUF_INIT;
3042 unable_to_lock_message(log_file, errno, &err);
3043 error("%s", err.buf);
3044 strbuf_release(&err);
3045 goto failure;
3046 }
3047 cb.newlog = fdopen_lock_file(&reflog_lock, "w");
3048 if (!cb.newlog) {
3049 error("cannot fdopen %s (%s)",
3050 get_lock_file_path(&reflog_lock), strerror(errno));
3051 goto failure;
3052 }
3053 }
3054
3055 (*prepare_fn)(refname, oid, cb.policy_cb);
3056 refs_for_each_reflog_ent(ref_store, refname, expire_reflog_ent, &cb);
3057 (*cleanup_fn)(cb.policy_cb);
3058
3059 if (!(flags & EXPIRE_REFLOGS_DRY_RUN)) {
3060 /*
3061 * It doesn't make sense to adjust a reference pointed
3062 * to by a symbolic ref based on expiring entries in
3063 * the symbolic reference's reflog. Nor can we update
3064 * a reference if there are no remaining reflog
3065 * entries.
3066 */
3067 int update = (flags & EXPIRE_REFLOGS_UPDATE_REF) &&
3068 !(type & REF_ISSYMREF) &&
3069 !is_null_oid(&cb.last_kept_oid);
3070
3071 if (close_lock_file_gently(&reflog_lock)) {
3072 status |= error("couldn't write %s: %s", log_file,
3073 strerror(errno));
3074 rollback_lock_file(&reflog_lock);
3075 } else if (update &&
3076 (write_in_full(get_lock_file_fd(&lock->lk),
3077 oid_to_hex(&cb.last_kept_oid), GIT_SHA1_HEXSZ) < 0 ||
3078 write_str_in_full(get_lock_file_fd(&lock->lk), "\n") < 0 ||
3079 close_ref_gently(lock) < 0)) {
3080 status |= error("couldn't write %s",
3081 get_lock_file_path(&lock->lk));
3082 rollback_lock_file(&reflog_lock);
3083 } else if (commit_lock_file(&reflog_lock)) {
3084 status |= error("unable to write reflog '%s' (%s)",
3085 log_file, strerror(errno));
3086 } else if (update && commit_ref(lock)) {
3087 status |= error("couldn't set %s", lock->ref_name);
3088 }
3089 }
3090 free(log_file);
3091 unlock_ref(lock);
3092 return status;
3093
3094 failure:
3095 rollback_lock_file(&reflog_lock);
3096 free(log_file);
3097 unlock_ref(lock);
3098 return -1;
3099 }
3100
3101 static int files_init_db(struct ref_store *ref_store, struct strbuf *err)
3102 {
3103 struct files_ref_store *refs =
3104 files_downcast(ref_store, REF_STORE_WRITE, "init_db");
3105 struct strbuf sb = STRBUF_INIT;
3106
3107 /*
3108 * Create .git/refs/{heads,tags}
3109 */
3110 files_ref_path(refs, &sb, "refs/heads");
3111 safe_create_dir(sb.buf, 1);
3112
3113 strbuf_reset(&sb);
3114 files_ref_path(refs, &sb, "refs/tags");
3115 safe_create_dir(sb.buf, 1);
3116
3117 strbuf_release(&sb);
3118 return 0;
3119 }
3120
3121 struct ref_storage_be refs_be_files = {
3122 NULL,
3123 "files",
3124 files_ref_store_create,
3125 files_init_db,
3126 files_transaction_prepare,
3127 files_transaction_finish,
3128 files_transaction_abort,
3129 files_initial_transaction_commit,
3130
3131 files_pack_refs,
3132 files_create_symref,
3133 files_delete_refs,
3134 files_rename_ref,
3135 files_copy_ref,
3136
3137 files_ref_iterator_begin,
3138 files_read_raw_ref,
3139
3140 files_reflog_iterator_begin,
3141 files_for_each_reflog_ent,
3142 files_for_each_reflog_ent_reverse,
3143 files_reflog_exists,
3144 files_create_reflog,
3145 files_delete_reflog,
3146 files_reflog_expire
3147 };