4 #include "../gettext.h"
7 #include "refs-internal.h"
8 #include "packed-backend.h"
9 #include "../iterator.h"
10 #include "../lockfile.h"
11 #include "../chdir-notify.h"
15 * Don't use mmap() at all for reading `packed-refs`.
20 * Can use mmap() for reading `packed-refs`, but the file must
21 * not remain mmapped. This is the usual option on Windows,
22 * where you cannot rename a new version of a file onto a file
23 * that is currently mmapped.
28 * It is OK to leave the `packed-refs` file mmapped while
29 * arbitrary other code is running.
35 static enum mmap_strategy mmap_strategy
= MMAP_NONE
;
36 #elif defined(MMAP_PREVENTS_DELETE)
37 static enum mmap_strategy mmap_strategy
= MMAP_TEMPORARY
;
39 static enum mmap_strategy mmap_strategy
= MMAP_OK
;
42 struct packed_ref_store
;
45 * A `snapshot` represents one snapshot of a `packed-refs` file.
47 * Normally, this will be a mmapped view of the contents of the
48 * `packed-refs` file at the time the snapshot was created. However,
49 * if the `packed-refs` file was not sorted, this might point at heap
50 * memory holding the contents of the `packed-refs` file with its
51 * records sorted by refname.
53 * `snapshot` instances are reference counted (via
54 * `acquire_snapshot()` and `release_snapshot()`). This is to prevent
55 * an instance from disappearing while an iterator is still iterating
56 * over it. Instances are garbage collected when their `referrers`
59 * The most recent `snapshot`, if available, is referenced by the
60 * `packed_ref_store`. Its freshness is checked whenever
61 * `get_snapshot()` is called; if the existing snapshot is obsolete, a
62 * new snapshot is taken.
66 * A back-pointer to the packed_ref_store with which this
67 * snapshot is associated:
69 struct packed_ref_store
*refs
;
71 /* Is the `packed-refs` file currently mmapped? */
75 * The contents of the `packed-refs` file:
77 * - buf -- a pointer to the start of the memory
78 * - start -- a pointer to the first byte of actual references
79 * (i.e., after the header line, if one is present)
80 * - eof -- a pointer just past the end of the reference
83 * If the `packed-refs` file was already sorted, `buf` points
84 * at the mmapped contents of the file. If not, it points at
85 * heap-allocated memory containing the contents, sorted. If
86 * there were no contents (e.g., because the file didn't
87 * exist), `buf`, `start`, and `eof` are all NULL.
89 char *buf
, *start
, *eof
;
92 * What is the peeled state of the `packed-refs` file that
93 * this snapshot represents? (This is usually determined from
96 enum { PEELED_NONE
, PEELED_TAGS
, PEELED_FULLY
} peeled
;
99 * Count of references to this instance, including the pointer
100 * from `packed_ref_store::snapshot`, if any. The instance
101 * will not be freed as long as the reference count is
104 unsigned int referrers
;
107 * The metadata of the `packed-refs` file from which this
108 * snapshot was created, used to tell if the file has been
109 * replaced since we read it.
111 struct stat_validity validity
;
115 * A `ref_store` representing references stored in a `packed-refs`
116 * file. It implements the `ref_store` interface, though it has some
119 * - It cannot store symbolic references.
121 * - It cannot store reflogs.
123 * - It does not support reference renaming (though it could).
125 * On the other hand, it can be locked outside of a reference
126 * transaction. In that case, it remains locked even after the
127 * transaction is done and the new `packed-refs` file is activated.
129 struct packed_ref_store
{
130 struct ref_store base
;
132 unsigned int store_flags
;
134 /* The path of the "packed-refs" file: */
138 * A snapshot of the values read from the `packed-refs` file,
139 * if it might still be current; otherwise, NULL.
141 struct snapshot
*snapshot
;
144 * Lock used for the "packed-refs" file. Note that this (and
145 * thus the enclosing `packed_ref_store`) must not be freed.
147 struct lock_file lock
;
150 * Temporary file used when rewriting new contents to the
151 * "packed-refs" file. Note that this (and thus the enclosing
152 * `packed_ref_store`) must not be freed.
154 struct tempfile
*tempfile
;
158 * Increment the reference count of `*snapshot`.
160 static void acquire_snapshot(struct snapshot
*snapshot
)
162 snapshot
->referrers
++;
166 * If the buffer in `snapshot` is active, then either munmap the
167 * memory and close the file, or free the memory. Then set the buffer
170 static void clear_snapshot_buffer(struct snapshot
*snapshot
)
172 if (snapshot
->mmapped
) {
173 if (munmap(snapshot
->buf
, snapshot
->eof
- snapshot
->buf
))
174 die_errno("error ummapping packed-refs file %s",
175 snapshot
->refs
->path
);
176 snapshot
->mmapped
= 0;
180 snapshot
->buf
= snapshot
->start
= snapshot
->eof
= NULL
;
184 * Decrease the reference count of `*snapshot`. If it goes to zero,
185 * free `*snapshot` and return true; otherwise return false.
187 static int release_snapshot(struct snapshot
*snapshot
)
189 if (!--snapshot
->referrers
) {
190 stat_validity_clear(&snapshot
->validity
);
191 clear_snapshot_buffer(snapshot
);
199 struct ref_store
*packed_ref_store_create(struct repository
*repo
,
201 unsigned int store_flags
)
203 struct packed_ref_store
*refs
= xcalloc(1, sizeof(*refs
));
204 struct ref_store
*ref_store
= (struct ref_store
*)refs
;
205 struct strbuf sb
= STRBUF_INIT
;
207 base_ref_store_init(ref_store
, repo
, gitdir
, &refs_be_packed
);
208 refs
->store_flags
= store_flags
;
210 strbuf_addf(&sb
, "%s/packed-refs", gitdir
);
211 refs
->path
= strbuf_detach(&sb
, NULL
);
212 chdir_notify_reparent("packed-refs", &refs
->path
);
217 * Downcast `ref_store` to `packed_ref_store`. Die if `ref_store` is
218 * not a `packed_ref_store`. Also die if `packed_ref_store` doesn't
219 * support at least the flags specified in `required_flags`. `caller`
220 * is used in any necessary error messages.
222 static struct packed_ref_store
*packed_downcast(struct ref_store
*ref_store
,
223 unsigned int required_flags
,
226 struct packed_ref_store
*refs
;
228 if (ref_store
->be
!= &refs_be_packed
)
229 BUG("ref_store is type \"%s\" not \"packed\" in %s",
230 ref_store
->be
->name
, caller
);
232 refs
= (struct packed_ref_store
*)ref_store
;
234 if ((refs
->store_flags
& required_flags
) != required_flags
)
235 BUG("unallowed operation (%s), requires %x, has %x\n",
236 caller
, required_flags
, refs
->store_flags
);
241 static void clear_snapshot(struct packed_ref_store
*refs
)
243 if (refs
->snapshot
) {
244 struct snapshot
*snapshot
= refs
->snapshot
;
246 refs
->snapshot
= NULL
;
247 release_snapshot(snapshot
);
251 static NORETURN
void die_unterminated_line(const char *path
,
252 const char *p
, size_t len
)
255 die("unterminated line in %s: %.*s", path
, (int)len
, p
);
257 die("unterminated line in %s: %.75s...", path
, p
);
260 static NORETURN
void die_invalid_line(const char *path
,
261 const char *p
, size_t len
)
263 const char *eol
= memchr(p
, '\n', len
);
266 die_unterminated_line(path
, p
, len
);
267 else if (eol
- p
< 80)
268 die("unexpected line in %s: %.*s", path
, (int)(eol
- p
), p
);
270 die("unexpected line in %s: %.75s...", path
, p
);
274 struct snapshot_record
{
279 static int cmp_packed_ref_records(const void *v1
, const void *v2
)
281 const struct snapshot_record
*e1
= v1
, *e2
= v2
;
282 const char *r1
= e1
->start
+ the_hash_algo
->hexsz
+ 1;
283 const char *r2
= e2
->start
+ the_hash_algo
->hexsz
+ 1;
287 return *r2
== '\n' ? 0 : -1;
292 return (unsigned char)*r1
< (unsigned char)*r2
? -1 : +1;
300 * Compare a snapshot record at `rec` to the specified NUL-terminated
303 static int cmp_record_to_refname(const char *rec
, const char *refname
)
305 const char *r1
= rec
+ the_hash_algo
->hexsz
+ 1;
306 const char *r2
= refname
;
314 return (unsigned char)*r1
< (unsigned char)*r2
? -1 : +1;
321 * `snapshot->buf` is not known to be sorted. Check whether it is, and
322 * if not, sort it into new memory and munmap/free the old storage.
324 static void sort_snapshot(struct snapshot
*snapshot
)
326 struct snapshot_record
*records
= NULL
;
327 size_t alloc
= 0, nr
= 0;
329 const char *pos
, *eof
, *eol
;
331 char *new_buffer
, *dst
;
333 pos
= snapshot
->start
;
342 * Initialize records based on a crude estimate of the number
343 * of references in the file (we'll grow it below if needed):
345 ALLOC_GROW(records
, len
/ 80 + 20, alloc
);
348 eol
= memchr(pos
, '\n', eof
- pos
);
350 /* The safety check should prevent this. */
351 BUG("unterminated line found in packed-refs");
352 if (eol
- pos
< the_hash_algo
->hexsz
+ 2)
353 die_invalid_line(snapshot
->refs
->path
,
356 if (eol
< eof
&& *eol
== '^') {
358 * Keep any peeled line together with its
361 const char *peeled_start
= eol
;
363 eol
= memchr(peeled_start
, '\n', eof
- peeled_start
);
365 /* The safety check should prevent this. */
366 BUG("unterminated peeled line found in packed-refs");
370 ALLOC_GROW(records
, nr
+ 1, alloc
);
371 records
[nr
].start
= pos
;
372 records
[nr
].len
= eol
- pos
;
377 cmp_packed_ref_records(&records
[nr
- 2],
378 &records
[nr
- 1]) >= 0)
387 /* We need to sort the memory. First we sort the records array: */
388 QSORT(records
, nr
, cmp_packed_ref_records
);
391 * Allocate a new chunk of memory, and copy the old memory to
392 * the new in the order indicated by `records` (not bothering
393 * with the header line):
395 new_buffer
= xmalloc(len
);
396 for (dst
= new_buffer
, i
= 0; i
< nr
; i
++) {
397 memcpy(dst
, records
[i
].start
, records
[i
].len
);
398 dst
+= records
[i
].len
;
402 * Now munmap the old buffer and use the sorted buffer in its
405 clear_snapshot_buffer(snapshot
);
406 snapshot
->buf
= snapshot
->start
= new_buffer
;
407 snapshot
->eof
= new_buffer
+ len
;
414 * Return a pointer to the start of the record that contains the
415 * character `*p` (which must be within the buffer). If no other
416 * record start is found, return `buf`.
418 static const char *find_start_of_record(const char *buf
, const char *p
)
420 while (p
> buf
&& (p
[-1] != '\n' || p
[0] == '^'))
426 * Return a pointer to the start of the record following the record
427 * that contains `*p`. If none is found before `end`, return `end`.
429 static const char *find_end_of_record(const char *p
, const char *end
)
431 while (++p
< end
&& (p
[-1] != '\n' || p
[0] == '^'))
437 * We want to be able to compare mmapped reference records quickly,
438 * without totally parsing them. We can do so because the records are
439 * LF-terminated, and the refname should start exactly (GIT_SHA1_HEXSZ
440 * + 1) bytes past the beginning of the record.
442 * But what if the `packed-refs` file contains garbage? We're willing
443 * to tolerate not detecting the problem, as long as we don't produce
444 * totally garbled output (we can't afford to check the integrity of
445 * the whole file during every Git invocation). But we do want to be
446 * sure that we never read past the end of the buffer in memory and
447 * perform an illegal memory access.
449 * Guarantee that minimum level of safety by verifying that the last
450 * record in the file is LF-terminated, and that it has at least
451 * (GIT_SHA1_HEXSZ + 1) characters before the LF. Die if either of
452 * these checks fails.
454 static void verify_buffer_safe(struct snapshot
*snapshot
)
456 const char *start
= snapshot
->start
;
457 const char *eof
= snapshot
->eof
;
458 const char *last_line
;
463 last_line
= find_start_of_record(start
, eof
- 1);
464 if (*(eof
- 1) != '\n' || eof
- last_line
< the_hash_algo
->hexsz
+ 2)
465 die_invalid_line(snapshot
->refs
->path
,
466 last_line
, eof
- last_line
);
469 #define SMALL_FILE_SIZE (32*1024)
472 * Depending on `mmap_strategy`, either mmap or read the contents of
473 * the `packed-refs` file into the snapshot. Return 1 if the file
474 * existed and was read, or 0 if the file was absent or empty. Die on
477 static int load_contents(struct snapshot
*snapshot
)
484 fd
= open(snapshot
->refs
->path
, O_RDONLY
);
486 if (errno
== ENOENT
) {
488 * This is OK; it just means that no
489 * "packed-refs" file has been written yet,
490 * which is equivalent to it being empty,
491 * which is its state when initialized with
496 die_errno("couldn't read %s", snapshot
->refs
->path
);
500 stat_validity_update(&snapshot
->validity
, fd
);
502 if (fstat(fd
, &st
) < 0)
503 die_errno("couldn't stat %s", snapshot
->refs
->path
);
504 size
= xsize_t(st
.st_size
);
509 } else if (mmap_strategy
== MMAP_NONE
|| size
<= SMALL_FILE_SIZE
) {
510 snapshot
->buf
= xmalloc(size
);
511 bytes_read
= read_in_full(fd
, snapshot
->buf
, size
);
512 if (bytes_read
< 0 || bytes_read
!= size
)
513 die_errno("couldn't read %s", snapshot
->refs
->path
);
514 snapshot
->mmapped
= 0;
516 snapshot
->buf
= xmmap(NULL
, size
, PROT_READ
, MAP_PRIVATE
, fd
, 0);
517 snapshot
->mmapped
= 1;
521 snapshot
->start
= snapshot
->buf
;
522 snapshot
->eof
= snapshot
->buf
+ size
;
528 * Find the place in `snapshot->buf` where the start of the record for
529 * `refname` starts. If `mustexist` is true and the reference doesn't
530 * exist, then return NULL. If `mustexist` is false and the reference
531 * doesn't exist, then return the point where that reference would be
532 * inserted, or `snapshot->eof` (which might be NULL) if it would be
533 * inserted at the end of the file. In the latter mode, `refname`
534 * doesn't have to be a proper reference name; for example, one could
535 * search for "refs/replace/" to find the start of any replace
538 * The record is sought using a binary search, so `snapshot->buf` must
541 static const char *find_reference_location(struct snapshot
*snapshot
,
542 const char *refname
, int mustexist
)
545 * This is not *quite* a garden-variety binary search, because
546 * the data we're searching is made up of records, and we
547 * always need to find the beginning of a record to do a
548 * comparison. A "record" here is one line for the reference
549 * itself and zero or one peel lines that start with '^'. Our
550 * loop invariant is described in the next two comments.
554 * A pointer to the character at the start of a record whose
555 * preceding records all have reference names that come
556 * *before* `refname`.
558 const char *lo
= snapshot
->start
;
561 * A pointer to a the first character of a record whose
562 * reference name comes *after* `refname`.
564 const char *hi
= snapshot
->eof
;
567 const char *mid
, *rec
;
570 mid
= lo
+ (hi
- lo
) / 2;
571 rec
= find_start_of_record(lo
, mid
);
572 cmp
= cmp_record_to_refname(rec
, refname
);
574 lo
= find_end_of_record(mid
, hi
);
575 } else if (cmp
> 0) {
589 * Create a newly-allocated `snapshot` of the `packed-refs` file in
590 * its current state and return it. The return value will already have
591 * its reference count incremented.
593 * A comment line of the form "# pack-refs with: " may contain zero or
594 * more traits. We interpret the traits as follows:
596 * Neither `peeled` nor `fully-peeled`:
598 * Probably no references are peeled. But if the file contains a
599 * peeled value for a reference, we will use it.
603 * References under "refs/tags/", if they *can* be peeled, *are*
604 * peeled in this file. References outside of "refs/tags/" are
605 * probably not peeled even if they could have been, but if we find
606 * a peeled value for such a reference we will use it.
610 * All references in the file that can be peeled are peeled.
611 * Inversely (and this is more important), any references in the
612 * file for which no peeled value is recorded is not peelable. This
613 * trait should typically be written alongside "peeled" for
614 * compatibility with older clients, but we do not require it
615 * (i.e., "peeled" is a no-op if "fully-peeled" is set).
619 * The references in this file are known to be sorted by refname.
621 static struct snapshot
*create_snapshot(struct packed_ref_store
*refs
)
623 struct snapshot
*snapshot
= xcalloc(1, sizeof(*snapshot
));
626 snapshot
->refs
= refs
;
627 acquire_snapshot(snapshot
);
628 snapshot
->peeled
= PEELED_NONE
;
630 if (!load_contents(snapshot
))
633 /* If the file has a header line, process it: */
634 if (snapshot
->buf
< snapshot
->eof
&& *snapshot
->buf
== '#') {
636 struct string_list traits
= STRING_LIST_INIT_NODUP
;
638 eol
= memchr(snapshot
->buf
, '\n',
639 snapshot
->eof
- snapshot
->buf
);
641 die_unterminated_line(refs
->path
,
643 snapshot
->eof
- snapshot
->buf
);
645 tmp
= xmemdupz(snapshot
->buf
, eol
- snapshot
->buf
);
647 if (!skip_prefix(tmp
, "# pack-refs with:", (const char **)&p
))
648 die_invalid_line(refs
->path
,
650 snapshot
->eof
- snapshot
->buf
);
652 string_list_split_in_place(&traits
, p
, ' ', -1);
654 if (unsorted_string_list_has_string(&traits
, "fully-peeled"))
655 snapshot
->peeled
= PEELED_FULLY
;
656 else if (unsorted_string_list_has_string(&traits
, "peeled"))
657 snapshot
->peeled
= PEELED_TAGS
;
659 sorted
= unsorted_string_list_has_string(&traits
, "sorted");
661 /* perhaps other traits later as well */
663 /* The "+ 1" is for the LF character. */
664 snapshot
->start
= eol
+ 1;
666 string_list_clear(&traits
, 0);
670 verify_buffer_safe(snapshot
);
673 sort_snapshot(snapshot
);
676 * Reordering the records might have moved a short one
677 * to the end of the buffer, so verify the buffer's
680 verify_buffer_safe(snapshot
);
683 if (mmap_strategy
!= MMAP_OK
&& snapshot
->mmapped
) {
685 * We don't want to leave the file mmapped, so we are
686 * forced to make a copy now:
688 size_t size
= snapshot
->eof
- snapshot
->start
;
689 char *buf_copy
= xmalloc(size
);
691 memcpy(buf_copy
, snapshot
->start
, size
);
692 clear_snapshot_buffer(snapshot
);
693 snapshot
->buf
= snapshot
->start
= buf_copy
;
694 snapshot
->eof
= buf_copy
+ size
;
701 * Check that `refs->snapshot` (if present) still reflects the
702 * contents of the `packed-refs` file. If not, clear the snapshot.
704 static void validate_snapshot(struct packed_ref_store
*refs
)
706 if (refs
->snapshot
&&
707 !stat_validity_check(&refs
->snapshot
->validity
, refs
->path
))
708 clear_snapshot(refs
);
712 * Get the `snapshot` for the specified packed_ref_store, creating and
713 * populating it if it hasn't been read before or if the file has been
714 * changed (according to its `validity` field) since it was last read.
715 * On the other hand, if we hold the lock, then assume that the file
716 * hasn't been changed out from under us, so skip the extra `stat()`
717 * call in `stat_validity_check()`. This function does *not* increase
718 * the snapshot's reference count on behalf of the caller.
720 static struct snapshot
*get_snapshot(struct packed_ref_store
*refs
)
722 if (!is_lock_file_locked(&refs
->lock
))
723 validate_snapshot(refs
);
726 refs
->snapshot
= create_snapshot(refs
);
728 return refs
->snapshot
;
731 static int packed_read_raw_ref(struct ref_store
*ref_store
, const char *refname
,
732 struct object_id
*oid
, struct strbuf
*referent UNUSED
,
733 unsigned int *type
, int *failure_errno
)
735 struct packed_ref_store
*refs
=
736 packed_downcast(ref_store
, REF_STORE_READ
, "read_raw_ref");
737 struct snapshot
*snapshot
= get_snapshot(refs
);
742 rec
= find_reference_location(snapshot
, refname
, 1);
745 /* refname is not a packed reference. */
746 *failure_errno
= ENOENT
;
750 if (get_oid_hex(rec
, oid
))
751 die_invalid_line(refs
->path
, rec
, snapshot
->eof
- rec
);
753 *type
= REF_ISPACKED
;
758 * This value is set in `base.flags` if the peeled value of the
759 * current reference is known. In that case, `peeled` contains the
760 * correct peeled value for the reference, which might be `null_oid`
761 * if the reference is not a tag or if it is broken.
763 #define REF_KNOWS_PEELED 0x40
766 * An iterator over a snapshot of a `packed-refs` file.
768 struct packed_ref_iterator
{
769 struct ref_iterator base
;
771 struct snapshot
*snapshot
;
773 /* The current position in the snapshot's buffer: */
776 /* The end of the part of the buffer that will be iterated over: */
779 /* Scratch space for current values: */
780 struct object_id oid
, peeled
;
781 struct strbuf refname_buf
;
783 struct repository
*repo
;
788 * Move the iterator to the next record in the snapshot, without
789 * respect for whether the record is actually required by the current
790 * iteration. Adjust the fields in `iter` and return `ITER_OK` or
791 * `ITER_DONE`. This function does not free the iterator in the case
794 static int next_record(struct packed_ref_iterator
*iter
)
796 const char *p
= iter
->pos
, *eol
;
798 strbuf_reset(&iter
->refname_buf
);
800 if (iter
->pos
== iter
->eof
)
803 iter
->base
.flags
= REF_ISPACKED
;
805 if (iter
->eof
- p
< the_hash_algo
->hexsz
+ 2 ||
806 parse_oid_hex(p
, &iter
->oid
, &p
) ||
808 die_invalid_line(iter
->snapshot
->refs
->path
,
809 iter
->pos
, iter
->eof
- iter
->pos
);
811 eol
= memchr(p
, '\n', iter
->eof
- p
);
813 die_unterminated_line(iter
->snapshot
->refs
->path
,
814 iter
->pos
, iter
->eof
- iter
->pos
);
816 strbuf_add(&iter
->refname_buf
, p
, eol
- p
);
817 iter
->base
.refname
= iter
->refname_buf
.buf
;
819 if (check_refname_format(iter
->base
.refname
, REFNAME_ALLOW_ONELEVEL
)) {
820 if (!refname_is_safe(iter
->base
.refname
))
821 die("packed refname is dangerous: %s",
824 iter
->base
.flags
|= REF_BAD_NAME
| REF_ISBROKEN
;
826 if (iter
->snapshot
->peeled
== PEELED_FULLY
||
827 (iter
->snapshot
->peeled
== PEELED_TAGS
&&
828 starts_with(iter
->base
.refname
, "refs/tags/")))
829 iter
->base
.flags
|= REF_KNOWS_PEELED
;
833 if (iter
->pos
< iter
->eof
&& *iter
->pos
== '^') {
835 if (iter
->eof
- p
< the_hash_algo
->hexsz
+ 1 ||
836 parse_oid_hex(p
, &iter
->peeled
, &p
) ||
838 die_invalid_line(iter
->snapshot
->refs
->path
,
839 iter
->pos
, iter
->eof
- iter
->pos
);
843 * Regardless of what the file header said, we
844 * definitely know the value of *this* reference. But
845 * we suppress it if the reference is broken:
847 if ((iter
->base
.flags
& REF_ISBROKEN
)) {
848 oidclr(&iter
->peeled
);
849 iter
->base
.flags
&= ~REF_KNOWS_PEELED
;
851 iter
->base
.flags
|= REF_KNOWS_PEELED
;
854 oidclr(&iter
->peeled
);
860 static int packed_ref_iterator_advance(struct ref_iterator
*ref_iterator
)
862 struct packed_ref_iterator
*iter
=
863 (struct packed_ref_iterator
*)ref_iterator
;
866 while ((ok
= next_record(iter
)) == ITER_OK
) {
867 if (iter
->flags
& DO_FOR_EACH_PER_WORKTREE_ONLY
&&
868 !is_per_worktree_ref(iter
->base
.refname
))
871 if (!(iter
->flags
& DO_FOR_EACH_INCLUDE_BROKEN
) &&
872 !ref_resolves_to_object(iter
->base
.refname
, iter
->repo
,
873 &iter
->oid
, iter
->flags
))
879 if (ref_iterator_abort(ref_iterator
) != ITER_DONE
)
885 static int packed_ref_iterator_peel(struct ref_iterator
*ref_iterator
,
886 struct object_id
*peeled
)
888 struct packed_ref_iterator
*iter
=
889 (struct packed_ref_iterator
*)ref_iterator
;
891 if (iter
->repo
!= the_repository
)
892 BUG("peeling for non-the_repository is not supported");
894 if ((iter
->base
.flags
& REF_KNOWS_PEELED
)) {
895 oidcpy(peeled
, &iter
->peeled
);
896 return is_null_oid(&iter
->peeled
) ? -1 : 0;
897 } else if ((iter
->base
.flags
& (REF_ISBROKEN
| REF_ISSYMREF
))) {
900 return peel_object(&iter
->oid
, peeled
) ? -1 : 0;
904 static int packed_ref_iterator_abort(struct ref_iterator
*ref_iterator
)
906 struct packed_ref_iterator
*iter
=
907 (struct packed_ref_iterator
*)ref_iterator
;
910 strbuf_release(&iter
->refname_buf
);
911 release_snapshot(iter
->snapshot
);
912 base_ref_iterator_free(ref_iterator
);
916 static struct ref_iterator_vtable packed_ref_iterator_vtable
= {
917 .advance
= packed_ref_iterator_advance
,
918 .peel
= packed_ref_iterator_peel
,
919 .abort
= packed_ref_iterator_abort
922 static struct ref_iterator
*packed_ref_iterator_begin(
923 struct ref_store
*ref_store
,
924 const char *prefix
, unsigned int flags
)
926 struct packed_ref_store
*refs
;
927 struct snapshot
*snapshot
;
929 struct packed_ref_iterator
*iter
;
930 struct ref_iterator
*ref_iterator
;
931 unsigned int required_flags
= REF_STORE_READ
;
933 if (!(flags
& DO_FOR_EACH_INCLUDE_BROKEN
))
934 required_flags
|= REF_STORE_ODB
;
935 refs
= packed_downcast(ref_store
, required_flags
, "ref_iterator_begin");
938 * Note that `get_snapshot()` internally checks whether the
939 * snapshot is up to date with what is on disk, and re-reads
942 snapshot
= get_snapshot(refs
);
944 if (prefix
&& *prefix
)
945 start
= find_reference_location(snapshot
, prefix
, 0);
947 start
= snapshot
->start
;
949 if (start
== snapshot
->eof
)
950 return empty_ref_iterator_begin();
952 CALLOC_ARRAY(iter
, 1);
953 ref_iterator
= &iter
->base
;
954 base_ref_iterator_init(ref_iterator
, &packed_ref_iterator_vtable
, 1);
956 iter
->snapshot
= snapshot
;
957 acquire_snapshot(snapshot
);
960 iter
->eof
= snapshot
->eof
;
961 strbuf_init(&iter
->refname_buf
, 0);
963 iter
->base
.oid
= &iter
->oid
;
965 iter
->repo
= ref_store
->repo
;
968 if (prefix
&& *prefix
)
969 /* Stop iteration after we've gone *past* prefix: */
970 ref_iterator
= prefix_ref_iterator_begin(ref_iterator
, prefix
, 0);
976 * Write an entry to the packed-refs file for the specified refname.
977 * If peeled is non-NULL, write it as the entry's peeled value. On
978 * error, return a nonzero value and leave errno set at the value left
979 * by the failing call to `fprintf()`.
981 static int write_packed_entry(FILE *fh
, const char *refname
,
982 const struct object_id
*oid
,
983 const struct object_id
*peeled
)
985 if (fprintf(fh
, "%s %s\n", oid_to_hex(oid
), refname
) < 0 ||
986 (peeled
&& fprintf(fh
, "^%s\n", oid_to_hex(peeled
)) < 0))
992 int packed_refs_lock(struct ref_store
*ref_store
, int flags
, struct strbuf
*err
)
994 struct packed_ref_store
*refs
=
995 packed_downcast(ref_store
, REF_STORE_WRITE
| REF_STORE_MAIN
,
997 static int timeout_configured
= 0;
998 static int timeout_value
= 1000;
1000 if (!timeout_configured
) {
1001 git_config_get_int("core.packedrefstimeout", &timeout_value
);
1002 timeout_configured
= 1;
1006 * Note that we close the lockfile immediately because we
1007 * don't write new content to it, but rather to a separate
1010 if (hold_lock_file_for_update_timeout(
1013 flags
, timeout_value
) < 0) {
1014 unable_to_lock_message(refs
->path
, errno
, err
);
1018 if (close_lock_file_gently(&refs
->lock
)) {
1019 strbuf_addf(err
, "unable to close %s: %s", refs
->path
, strerror(errno
));
1020 rollback_lock_file(&refs
->lock
);
1025 * There is a stat-validity problem might cause `update-ref -d`
1026 * lost the newly commit of a ref, because a new `packed-refs`
1027 * file might has the same on-disk file attributes such as
1028 * timestamp, file size and inode value, but has a changed
1031 * This could happen with a very small chance when
1032 * `update-ref -d` is called and at the same time another
1033 * `pack-refs --all` process is running.
1035 * Now that we hold the `packed-refs` lock, it is important
1036 * to make sure we could read the latest version of
1037 * `packed-refs` file no matter we have just mmap it or not.
1038 * So what need to do is clear the snapshot if we hold it
1041 clear_snapshot(refs
);
1044 * Now make sure that the packed-refs file as it exists in the
1045 * locked state is loaded into the snapshot:
1051 void packed_refs_unlock(struct ref_store
*ref_store
)
1053 struct packed_ref_store
*refs
= packed_downcast(
1055 REF_STORE_READ
| REF_STORE_WRITE
,
1056 "packed_refs_unlock");
1058 if (!is_lock_file_locked(&refs
->lock
))
1059 BUG("packed_refs_unlock() called when not locked");
1060 rollback_lock_file(&refs
->lock
);
1063 int packed_refs_is_locked(struct ref_store
*ref_store
)
1065 struct packed_ref_store
*refs
= packed_downcast(
1067 REF_STORE_READ
| REF_STORE_WRITE
,
1068 "packed_refs_is_locked");
1070 return is_lock_file_locked(&refs
->lock
);
1074 * The packed-refs header line that we write out. Perhaps other traits
1075 * will be added later.
1077 * Note that earlier versions of Git used to parse these traits by
1078 * looking for " trait " in the line. For this reason, the space after
1079 * the colon and the trailing space are required.
1081 static const char PACKED_REFS_HEADER
[] =
1082 "# pack-refs with: peeled fully-peeled sorted \n";
1084 static int packed_init_db(struct ref_store
*ref_store UNUSED
,
1085 struct strbuf
*err UNUSED
)
1087 /* Nothing to do. */
1092 * Write the packed refs from the current snapshot to the packed-refs
1093 * tempfile, incorporating any changes from `updates`. `updates` must
1094 * be a sorted string list whose keys are the refnames and whose util
1095 * values are `struct ref_update *`. On error, rollback the tempfile,
1096 * write an error message to `err`, and return a nonzero value.
1098 * The packfile must be locked before calling this function and will
1099 * remain locked when it is done.
1101 static int write_with_updates(struct packed_ref_store
*refs
,
1102 struct string_list
*updates
,
1105 struct ref_iterator
*iter
= NULL
;
1109 struct strbuf sb
= STRBUF_INIT
;
1110 char *packed_refs_path
;
1112 if (!is_lock_file_locked(&refs
->lock
))
1113 BUG("write_with_updates() called while unlocked");
1116 * If packed-refs is a symlink, we want to overwrite the
1117 * symlinked-to file, not the symlink itself. Also, put the
1118 * staging file next to it:
1120 packed_refs_path
= get_locked_file_path(&refs
->lock
);
1121 strbuf_addf(&sb
, "%s.new", packed_refs_path
);
1122 free(packed_refs_path
);
1123 refs
->tempfile
= create_tempfile(sb
.buf
);
1124 if (!refs
->tempfile
) {
1125 strbuf_addf(err
, "unable to create file %s: %s",
1126 sb
.buf
, strerror(errno
));
1127 strbuf_release(&sb
);
1130 strbuf_release(&sb
);
1132 out
= fdopen_tempfile(refs
->tempfile
, "w");
1134 strbuf_addf(err
, "unable to fdopen packed-refs tempfile: %s",
1139 if (fprintf(out
, "%s", PACKED_REFS_HEADER
) < 0)
1143 * We iterate in parallel through the current list of refs and
1144 * the list of updates, processing an entry from at least one
1145 * of the lists each time through the loop. When the current
1146 * list of refs is exhausted, set iter to NULL. When the list
1147 * of updates is exhausted, leave i set to updates->nr.
1149 iter
= packed_ref_iterator_begin(&refs
->base
, "",
1150 DO_FOR_EACH_INCLUDE_BROKEN
);
1151 if ((ok
= ref_iterator_advance(iter
)) != ITER_OK
)
1156 while (iter
|| i
< updates
->nr
) {
1157 struct ref_update
*update
= NULL
;
1160 if (i
>= updates
->nr
) {
1163 update
= updates
->items
[i
].util
;
1168 cmp
= strcmp(iter
->refname
, update
->refname
);
1173 * There is both an old value and an update
1174 * for this reference. Check the old value if
1177 if ((update
->flags
& REF_HAVE_OLD
)) {
1178 if (is_null_oid(&update
->old_oid
)) {
1179 strbuf_addf(err
, "cannot update ref '%s': "
1180 "reference already exists",
1183 } else if (!oideq(&update
->old_oid
, iter
->oid
)) {
1184 strbuf_addf(err
, "cannot update ref '%s': "
1185 "is at %s but expected %s",
1187 oid_to_hex(iter
->oid
),
1188 oid_to_hex(&update
->old_oid
));
1193 /* Now figure out what to use for the new value: */
1194 if ((update
->flags
& REF_HAVE_NEW
)) {
1196 * The update takes precedence. Skip
1197 * the iterator over the unneeded
1200 if ((ok
= ref_iterator_advance(iter
)) != ITER_OK
)
1205 * The update doesn't actually want to
1206 * change anything. We're done with it.
1211 } else if (cmp
> 0) {
1213 * There is no old value but there is an
1214 * update for this reference. Make sure that
1215 * the update didn't expect an existing value:
1217 if ((update
->flags
& REF_HAVE_OLD
) &&
1218 !is_null_oid(&update
->old_oid
)) {
1219 strbuf_addf(err
, "cannot update ref '%s': "
1220 "reference is missing but expected %s",
1222 oid_to_hex(&update
->old_oid
));
1228 /* Pass the old reference through. */
1230 struct object_id peeled
;
1231 int peel_error
= ref_iterator_peel(iter
, &peeled
);
1233 if (write_packed_entry(out
, iter
->refname
,
1235 peel_error
? NULL
: &peeled
))
1238 if ((ok
= ref_iterator_advance(iter
)) != ITER_OK
)
1240 } else if (is_null_oid(&update
->new_oid
)) {
1242 * The update wants to delete the reference,
1243 * and the reference either didn't exist or we
1244 * have already skipped it. So we're done with
1245 * the update (and don't have to write
1250 struct object_id peeled
;
1251 int peel_error
= peel_object(&update
->new_oid
,
1254 if (write_packed_entry(out
, update
->refname
,
1256 peel_error
? NULL
: &peeled
))
1263 if (ok
!= ITER_DONE
) {
1264 strbuf_addstr(err
, "unable to write packed-refs file: "
1265 "error iterating over old contents");
1270 fsync_component(FSYNC_COMPONENT_REFERENCE
, get_tempfile_fd(refs
->tempfile
)) ||
1271 close_tempfile_gently(refs
->tempfile
)) {
1272 strbuf_addf(err
, "error closing file %s: %s",
1273 get_tempfile_path(refs
->tempfile
),
1275 strbuf_release(&sb
);
1276 delete_tempfile(&refs
->tempfile
);
1283 strbuf_addf(err
, "error writing to %s: %s",
1284 get_tempfile_path(refs
->tempfile
), strerror(errno
));
1288 ref_iterator_abort(iter
);
1290 delete_tempfile(&refs
->tempfile
);
1294 int is_packed_transaction_needed(struct ref_store
*ref_store
,
1295 struct ref_transaction
*transaction
)
1297 struct packed_ref_store
*refs
= packed_downcast(
1300 "is_packed_transaction_needed");
1301 struct strbuf referent
= STRBUF_INIT
;
1305 if (!is_lock_file_locked(&refs
->lock
))
1306 BUG("is_packed_transaction_needed() called while unlocked");
1309 * We're only going to bother returning false for the common,
1310 * trivial case that references are only being deleted, their
1311 * old values are not being checked, and the old `packed-refs`
1312 * file doesn't contain any of those reference(s). This gives
1313 * false positives for some other cases that could
1314 * theoretically be optimized away:
1316 * 1. It could be that the old value is being verified without
1317 * setting a new value. In this case, we could verify the
1318 * old value here and skip the update if it agrees. If it
1319 * disagrees, we could either let the update go through
1320 * (the actual commit would re-detect and report the
1321 * problem), or come up with a way of reporting such an
1322 * error to *our* caller.
1324 * 2. It could be that a new value is being set, but that it
1325 * is identical to the current packed value of the
1328 * Neither of these cases will come up in the current code,
1329 * because the only caller of this function passes to it a
1330 * transaction that only includes `delete` updates with no
1331 * `old_id`. Even if that ever changes, false positives only
1332 * cause an optimization to be missed; they do not affect
1337 * Start with the cheap checks that don't require old
1338 * reference values to be read:
1340 for (i
= 0; i
< transaction
->nr
; i
++) {
1341 struct ref_update
*update
= transaction
->updates
[i
];
1343 if (update
->flags
& REF_HAVE_OLD
)
1344 /* Have to check the old value -> needed. */
1347 if ((update
->flags
& REF_HAVE_NEW
) && !is_null_oid(&update
->new_oid
))
1348 /* Have to set a new value -> needed. */
1353 * The transaction isn't checking any old values nor is it
1354 * setting any nonzero new values, so it still might be able
1355 * to be skipped. Now do the more expensive check: the update
1356 * is needed if any of the updates is a delete, and the old
1357 * `packed-refs` file contains a value for that reference.
1360 for (i
= 0; i
< transaction
->nr
; i
++) {
1361 struct ref_update
*update
= transaction
->updates
[i
];
1364 struct object_id oid
;
1366 if (!(update
->flags
& REF_HAVE_NEW
))
1368 * This reference isn't being deleted -> not
1373 if (!refs_read_raw_ref(ref_store
, update
->refname
, &oid
,
1374 &referent
, &type
, &failure_errno
) ||
1375 failure_errno
!= ENOENT
) {
1377 * We have to actually delete that reference
1378 * -> this transaction is needed.
1385 strbuf_release(&referent
);
1389 struct packed_transaction_backend_data
{
1390 /* True iff the transaction owns the packed-refs lock. */
1393 struct string_list updates
;
1396 static void packed_transaction_cleanup(struct packed_ref_store
*refs
,
1397 struct ref_transaction
*transaction
)
1399 struct packed_transaction_backend_data
*data
= transaction
->backend_data
;
1402 string_list_clear(&data
->updates
, 0);
1404 if (is_tempfile_active(refs
->tempfile
))
1405 delete_tempfile(&refs
->tempfile
);
1407 if (data
->own_lock
&& is_lock_file_locked(&refs
->lock
)) {
1408 packed_refs_unlock(&refs
->base
);
1413 transaction
->backend_data
= NULL
;
1416 transaction
->state
= REF_TRANSACTION_CLOSED
;
1419 static int packed_transaction_prepare(struct ref_store
*ref_store
,
1420 struct ref_transaction
*transaction
,
1423 struct packed_ref_store
*refs
= packed_downcast(
1425 REF_STORE_READ
| REF_STORE_WRITE
| REF_STORE_ODB
,
1426 "ref_transaction_prepare");
1427 struct packed_transaction_backend_data
*data
;
1429 int ret
= TRANSACTION_GENERIC_ERROR
;
1432 * Note that we *don't* skip transactions with zero updates,
1433 * because such a transaction might be executed for the side
1434 * effect of ensuring that all of the references are peeled or
1435 * ensuring that the `packed-refs` file is sorted. If the
1436 * caller wants to optimize away empty transactions, it should
1440 CALLOC_ARRAY(data
, 1);
1441 string_list_init_nodup(&data
->updates
);
1443 transaction
->backend_data
= data
;
1446 * Stick the updates in a string list by refname so that we
1449 for (i
= 0; i
< transaction
->nr
; i
++) {
1450 struct ref_update
*update
= transaction
->updates
[i
];
1451 struct string_list_item
*item
=
1452 string_list_append(&data
->updates
, update
->refname
);
1454 /* Store a pointer to update in item->util: */
1455 item
->util
= update
;
1457 string_list_sort(&data
->updates
);
1459 if (ref_update_reject_duplicates(&data
->updates
, err
))
1462 if (!is_lock_file_locked(&refs
->lock
)) {
1463 if (packed_refs_lock(ref_store
, 0, err
))
1468 if (write_with_updates(refs
, &data
->updates
, err
))
1471 transaction
->state
= REF_TRANSACTION_PREPARED
;
1475 packed_transaction_cleanup(refs
, transaction
);
1479 static int packed_transaction_abort(struct ref_store
*ref_store
,
1480 struct ref_transaction
*transaction
,
1481 struct strbuf
*err UNUSED
)
1483 struct packed_ref_store
*refs
= packed_downcast(
1485 REF_STORE_READ
| REF_STORE_WRITE
| REF_STORE_ODB
,
1486 "ref_transaction_abort");
1488 packed_transaction_cleanup(refs
, transaction
);
1492 static int packed_transaction_finish(struct ref_store
*ref_store
,
1493 struct ref_transaction
*transaction
,
1496 struct packed_ref_store
*refs
= packed_downcast(
1498 REF_STORE_READ
| REF_STORE_WRITE
| REF_STORE_ODB
,
1499 "ref_transaction_finish");
1500 int ret
= TRANSACTION_GENERIC_ERROR
;
1501 char *packed_refs_path
;
1503 clear_snapshot(refs
);
1505 packed_refs_path
= get_locked_file_path(&refs
->lock
);
1506 if (rename_tempfile(&refs
->tempfile
, packed_refs_path
)) {
1507 strbuf_addf(err
, "error replacing %s: %s",
1508 refs
->path
, strerror(errno
));
1515 free(packed_refs_path
);
1516 packed_transaction_cleanup(refs
, transaction
);
1520 static int packed_initial_transaction_commit(struct ref_store
*ref_store UNUSED
,
1521 struct ref_transaction
*transaction
,
1524 return ref_transaction_commit(transaction
, err
);
1527 static int packed_delete_refs(struct ref_store
*ref_store
, const char *msg
,
1528 struct string_list
*refnames
, unsigned int flags
)
1530 struct packed_ref_store
*refs
=
1531 packed_downcast(ref_store
, REF_STORE_WRITE
, "delete_refs");
1532 struct strbuf err
= STRBUF_INIT
;
1533 struct ref_transaction
*transaction
;
1534 struct string_list_item
*item
;
1537 (void)refs
; /* We need the check above, but don't use the variable */
1543 * Since we don't check the references' old_oids, the
1544 * individual updates can't fail, so we can pack all of the
1545 * updates into a single transaction.
1548 transaction
= ref_store_transaction_begin(ref_store
, &err
);
1552 for_each_string_list_item(item
, refnames
) {
1553 if (ref_transaction_delete(transaction
, item
->string
, NULL
,
1554 flags
, msg
, &err
)) {
1555 warning(_("could not delete reference %s: %s"),
1556 item
->string
, err
.buf
);
1561 ret
= ref_transaction_commit(transaction
, &err
);
1564 if (refnames
->nr
== 1)
1565 error(_("could not delete reference %s: %s"),
1566 refnames
->items
[0].string
, err
.buf
);
1568 error(_("could not delete references: %s"), err
.buf
);
1571 ref_transaction_free(transaction
);
1572 strbuf_release(&err
);
1576 static int packed_pack_refs(struct ref_store
*ref_store UNUSED
,
1577 unsigned int flags UNUSED
)
1580 * Packed refs are already packed. It might be that loose refs
1581 * are packed *into* a packed refs store, but that is done by
1582 * updating the packed references via a transaction.
1587 static struct ref_iterator
*packed_reflog_iterator_begin(struct ref_store
*ref_store UNUSED
)
1589 return empty_ref_iterator_begin();
1592 struct ref_storage_be refs_be_packed
= {
1595 .init
= packed_ref_store_create
,
1596 .init_db
= packed_init_db
,
1597 .transaction_prepare
= packed_transaction_prepare
,
1598 .transaction_finish
= packed_transaction_finish
,
1599 .transaction_abort
= packed_transaction_abort
,
1600 .initial_transaction_commit
= packed_initial_transaction_commit
,
1602 .pack_refs
= packed_pack_refs
,
1603 .create_symref
= NULL
,
1604 .delete_refs
= packed_delete_refs
,
1608 .iterator_begin
= packed_ref_iterator_begin
,
1609 .read_raw_ref
= packed_read_raw_ref
,
1610 .read_symbolic_ref
= NULL
,
1612 .reflog_iterator_begin
= packed_reflog_iterator_begin
,
1613 .for_each_reflog_ent
= NULL
,
1614 .for_each_reflog_ent_reverse
= NULL
,
1615 .reflog_exists
= NULL
,
1616 .create_reflog
= NULL
,
1617 .delete_reflog
= NULL
,
1618 .reflog_expire
= NULL
,