4 #include "refs-internal.h"
5 #include "packed-backend.h"
6 #include "../iterator.h"
7 #include "../lockfile.h"
11 * Don't use mmap() at all for reading `packed-refs`.
16 * Can use mmap() for reading `packed-refs`, but the file must
17 * not remain mmapped. This is the usual option on Windows,
18 * where you cannot rename a new version of a file onto a file
19 * that is currently mmapped.
24 * It is OK to leave the `packed-refs` file mmapped while
25 * arbitrary other code is running.
31 static enum mmap_strategy mmap_strategy
= MMAP_NONE
;
32 #elif defined(MMAP_PREVENTS_DELETE)
33 static enum mmap_strategy mmap_strategy
= MMAP_TEMPORARY
;
35 static enum mmap_strategy mmap_strategy
= MMAP_OK
;
38 struct packed_ref_store
;
41 * A `snapshot` represents one snapshot of a `packed-refs` file.
43 * Normally, this will be a mmapped view of the contents of the
44 * `packed-refs` file at the time the snapshot was created. However,
45 * if the `packed-refs` file was not sorted, this might point at heap
46 * memory holding the contents of the `packed-refs` file with its
47 * records sorted by refname.
49 * `snapshot` instances are reference counted (via
50 * `acquire_snapshot()` and `release_snapshot()`). This is to prevent
51 * an instance from disappearing while an iterator is still iterating
52 * over it. Instances are garbage collected when their `referrers`
55 * The most recent `snapshot`, if available, is referenced by the
56 * `packed_ref_store`. Its freshness is checked whenever
57 * `get_snapshot()` is called; if the existing snapshot is obsolete, a
58 * new snapshot is taken.
62 * A back-pointer to the packed_ref_store with which this
63 * snapshot is associated:
65 struct packed_ref_store
*refs
;
67 /* Is the `packed-refs` file currently mmapped? */
71 * The contents of the `packed-refs` file:
73 * - buf -- a pointer to the start of the memory
74 * - start -- a pointer to the first byte of actual references
75 * (i.e., after the header line, if one is present)
76 * - eof -- a pointer just past the end of the reference
79 * If the `packed-refs` file was already sorted, `buf` points
80 * at the mmapped contents of the file. If not, it points at
81 * heap-allocated memory containing the contents, sorted. If
82 * there were no contents (e.g., because the file didn't
83 * exist), `buf`, `start`, and `eof` are all NULL.
85 char *buf
, *start
, *eof
;
88 * What is the peeled state of the `packed-refs` file that
89 * this snapshot represents? (This is usually determined from
92 enum { PEELED_NONE
, PEELED_TAGS
, PEELED_FULLY
} peeled
;
95 * Count of references to this instance, including the pointer
96 * from `packed_ref_store::snapshot`, if any. The instance
97 * will not be freed as long as the reference count is
100 unsigned int referrers
;
103 * The metadata of the `packed-refs` file from which this
104 * snapshot was created, used to tell if the file has been
105 * replaced since we read it.
107 struct stat_validity validity
;
111 * A `ref_store` representing references stored in a `packed-refs`
112 * file. It implements the `ref_store` interface, though it has some
115 * - It cannot store symbolic references.
117 * - It cannot store reflogs.
119 * - It does not support reference renaming (though it could).
121 * On the other hand, it can be locked outside of a reference
122 * transaction. In that case, it remains locked even after the
123 * transaction is done and the new `packed-refs` file is activated.
125 struct packed_ref_store
{
126 struct ref_store base
;
128 unsigned int store_flags
;
130 /* The path of the "packed-refs" file: */
134 * A snapshot of the values read from the `packed-refs` file,
135 * if it might still be current; otherwise, NULL.
137 struct snapshot
*snapshot
;
140 * Lock used for the "packed-refs" file. Note that this (and
141 * thus the enclosing `packed_ref_store`) must not be freed.
143 struct lock_file lock
;
146 * Temporary file used when rewriting new contents to the
147 * "packed-refs" file. Note that this (and thus the enclosing
148 * `packed_ref_store`) must not be freed.
150 struct tempfile
*tempfile
;
154 * Increment the reference count of `*snapshot`.
156 static void acquire_snapshot(struct snapshot
*snapshot
)
158 snapshot
->referrers
++;
162 * If the buffer in `snapshot` is active, then either munmap the
163 * memory and close the file, or free the memory. Then set the buffer
166 static void clear_snapshot_buffer(struct snapshot
*snapshot
)
168 if (snapshot
->mmapped
) {
169 if (munmap(snapshot
->buf
, snapshot
->eof
- snapshot
->buf
))
170 die_errno("error ummapping packed-refs file %s",
171 snapshot
->refs
->path
);
172 snapshot
->mmapped
= 0;
176 snapshot
->buf
= snapshot
->start
= snapshot
->eof
= NULL
;
180 * Decrease the reference count of `*snapshot`. If it goes to zero,
181 * free `*snapshot` and return true; otherwise return false.
183 static int release_snapshot(struct snapshot
*snapshot
)
185 if (!--snapshot
->referrers
) {
186 stat_validity_clear(&snapshot
->validity
);
187 clear_snapshot_buffer(snapshot
);
195 struct ref_store
*packed_ref_store_create(const char *path
,
196 unsigned int store_flags
)
198 struct packed_ref_store
*refs
= xcalloc(1, sizeof(*refs
));
199 struct ref_store
*ref_store
= (struct ref_store
*)refs
;
201 base_ref_store_init(ref_store
, &refs_be_packed
);
202 refs
->store_flags
= store_flags
;
204 refs
->path
= xstrdup(path
);
209 * Downcast `ref_store` to `packed_ref_store`. Die if `ref_store` is
210 * not a `packed_ref_store`. Also die if `packed_ref_store` doesn't
211 * support at least the flags specified in `required_flags`. `caller`
212 * is used in any necessary error messages.
214 static struct packed_ref_store
*packed_downcast(struct ref_store
*ref_store
,
215 unsigned int required_flags
,
218 struct packed_ref_store
*refs
;
220 if (ref_store
->be
!= &refs_be_packed
)
221 die("BUG: ref_store is type \"%s\" not \"packed\" in %s",
222 ref_store
->be
->name
, caller
);
224 refs
= (struct packed_ref_store
*)ref_store
;
226 if ((refs
->store_flags
& required_flags
) != required_flags
)
227 die("BUG: unallowed operation (%s), requires %x, has %x\n",
228 caller
, required_flags
, refs
->store_flags
);
233 static void clear_snapshot(struct packed_ref_store
*refs
)
235 if (refs
->snapshot
) {
236 struct snapshot
*snapshot
= refs
->snapshot
;
238 refs
->snapshot
= NULL
;
239 release_snapshot(snapshot
);
243 static NORETURN
void die_unterminated_line(const char *path
,
244 const char *p
, size_t len
)
247 die("unterminated line in %s: %.*s", path
, (int)len
, p
);
249 die("unterminated line in %s: %.75s...", path
, p
);
252 static NORETURN
void die_invalid_line(const char *path
,
253 const char *p
, size_t len
)
255 const char *eol
= memchr(p
, '\n', len
);
258 die_unterminated_line(path
, p
, len
);
259 else if (eol
- p
< 80)
260 die("unexpected line in %s: %.*s", path
, (int)(eol
- p
), p
);
262 die("unexpected line in %s: %.75s...", path
, p
);
266 struct snapshot_record
{
271 static int cmp_packed_ref_records(const void *v1
, const void *v2
)
273 const struct snapshot_record
*e1
= v1
, *e2
= v2
;
274 const char *r1
= e1
->start
+ GIT_SHA1_HEXSZ
+ 1;
275 const char *r2
= e2
->start
+ GIT_SHA1_HEXSZ
+ 1;
279 return *r2
== '\n' ? 0 : -1;
284 return (unsigned char)*r1
< (unsigned char)*r2
? -1 : +1;
292 * Compare a snapshot record at `rec` to the specified NUL-terminated
295 static int cmp_record_to_refname(const char *rec
, const char *refname
)
297 const char *r1
= rec
+ GIT_SHA1_HEXSZ
+ 1;
298 const char *r2
= refname
;
306 return (unsigned char)*r1
< (unsigned char)*r2
? -1 : +1;
313 * `snapshot->buf` is not known to be sorted. Check whether it is, and
314 * if not, sort it into new memory and munmap/free the old storage.
316 static void sort_snapshot(struct snapshot
*snapshot
)
318 struct snapshot_record
*records
= NULL
;
319 size_t alloc
= 0, nr
= 0;
321 const char *pos
, *eof
, *eol
;
323 char *new_buffer
, *dst
;
325 pos
= snapshot
->start
;
334 * Initialize records based on a crude estimate of the number
335 * of references in the file (we'll grow it below if needed):
337 ALLOC_GROW(records
, len
/ 80 + 20, alloc
);
340 eol
= memchr(pos
, '\n', eof
- pos
);
342 /* The safety check should prevent this. */
343 BUG("unterminated line found in packed-refs");
344 if (eol
- pos
< GIT_SHA1_HEXSZ
+ 2)
345 die_invalid_line(snapshot
->refs
->path
,
348 if (eol
< eof
&& *eol
== '^') {
350 * Keep any peeled line together with its
353 const char *peeled_start
= eol
;
355 eol
= memchr(peeled_start
, '\n', eof
- peeled_start
);
357 /* The safety check should prevent this. */
358 BUG("unterminated peeled line found in packed-refs");
362 ALLOC_GROW(records
, nr
+ 1, alloc
);
363 records
[nr
].start
= pos
;
364 records
[nr
].len
= eol
- pos
;
369 cmp_packed_ref_records(&records
[nr
- 2],
370 &records
[nr
- 1]) >= 0)
379 /* We need to sort the memory. First we sort the records array: */
380 QSORT(records
, nr
, cmp_packed_ref_records
);
383 * Allocate a new chunk of memory, and copy the old memory to
384 * the new in the order indicated by `records` (not bothering
385 * with the header line):
387 new_buffer
= xmalloc(len
);
388 for (dst
= new_buffer
, i
= 0; i
< nr
; i
++) {
389 memcpy(dst
, records
[i
].start
, records
[i
].len
);
390 dst
+= records
[i
].len
;
394 * Now munmap the old buffer and use the sorted buffer in its
397 clear_snapshot_buffer(snapshot
);
398 snapshot
->buf
= snapshot
->start
= new_buffer
;
399 snapshot
->eof
= new_buffer
+ len
;
406 * Return a pointer to the start of the record that contains the
407 * character `*p` (which must be within the buffer). If no other
408 * record start is found, return `buf`.
410 static const char *find_start_of_record(const char *buf
, const char *p
)
412 while (p
> buf
&& (p
[-1] != '\n' || p
[0] == '^'))
418 * Return a pointer to the start of the record following the record
419 * that contains `*p`. If none is found before `end`, return `end`.
421 static const char *find_end_of_record(const char *p
, const char *end
)
423 while (++p
< end
&& (p
[-1] != '\n' || p
[0] == '^'))
429 * We want to be able to compare mmapped reference records quickly,
430 * without totally parsing them. We can do so because the records are
431 * LF-terminated, and the refname should start exactly (GIT_SHA1_HEXSZ
432 * + 1) bytes past the beginning of the record.
434 * But what if the `packed-refs` file contains garbage? We're willing
435 * to tolerate not detecting the problem, as long as we don't produce
436 * totally garbled output (we can't afford to check the integrity of
437 * the whole file during every Git invocation). But we do want to be
438 * sure that we never read past the end of the buffer in memory and
439 * perform an illegal memory access.
441 * Guarantee that minimum level of safety by verifying that the last
442 * record in the file is LF-terminated, and that it has at least
443 * (GIT_SHA1_HEXSZ + 1) characters before the LF. Die if either of
444 * these checks fails.
446 static void verify_buffer_safe(struct snapshot
*snapshot
)
448 const char *start
= snapshot
->start
;
449 const char *eof
= snapshot
->eof
;
450 const char *last_line
;
455 last_line
= find_start_of_record(start
, eof
- 1);
456 if (*(eof
- 1) != '\n' || eof
- last_line
< GIT_SHA1_HEXSZ
+ 2)
457 die_invalid_line(snapshot
->refs
->path
,
458 last_line
, eof
- last_line
);
462 * Depending on `mmap_strategy`, either mmap or read the contents of
463 * the `packed-refs` file into the snapshot. Return 1 if the file
464 * existed and was read, or 0 if the file was absent. Die on errors.
466 static int load_contents(struct snapshot
*snapshot
)
473 fd
= open(snapshot
->refs
->path
, O_RDONLY
);
475 if (errno
== ENOENT
) {
477 * This is OK; it just means that no
478 * "packed-refs" file has been written yet,
479 * which is equivalent to it being empty,
480 * which is its state when initialized with
485 die_errno("couldn't read %s", snapshot
->refs
->path
);
489 stat_validity_update(&snapshot
->validity
, fd
);
491 if (fstat(fd
, &st
) < 0)
492 die_errno("couldn't stat %s", snapshot
->refs
->path
);
493 size
= xsize_t(st
.st_size
);
495 switch (mmap_strategy
) {
497 snapshot
->buf
= xmalloc(size
);
498 bytes_read
= read_in_full(fd
, snapshot
->buf
, size
);
499 if (bytes_read
< 0 || bytes_read
!= size
)
500 die_errno("couldn't read %s", snapshot
->refs
->path
);
501 snapshot
->mmapped
= 0;
505 snapshot
->buf
= xmmap(NULL
, size
, PROT_READ
, MAP_PRIVATE
, fd
, 0);
506 snapshot
->mmapped
= 1;
511 snapshot
->start
= snapshot
->buf
;
512 snapshot
->eof
= snapshot
->buf
+ size
;
518 * Find the place in `snapshot->buf` where the start of the record for
519 * `refname` starts. If `mustexist` is true and the reference doesn't
520 * exist, then return NULL. If `mustexist` is false and the reference
521 * doesn't exist, then return the point where that reference would be
522 * inserted. In the latter mode, `refname` doesn't have to be a proper
523 * reference name; for example, one could search for "refs/replace/"
524 * to find the start of any replace references.
526 * The record is sought using a binary search, so `snapshot->buf` must
529 static const char *find_reference_location(struct snapshot
*snapshot
,
530 const char *refname
, int mustexist
)
533 * This is not *quite* a garden-variety binary search, because
534 * the data we're searching is made up of records, and we
535 * always need to find the beginning of a record to do a
536 * comparison. A "record" here is one line for the reference
537 * itself and zero or one peel lines that start with '^'. Our
538 * loop invariant is described in the next two comments.
542 * A pointer to the character at the start of a record whose
543 * preceding records all have reference names that come
544 * *before* `refname`.
546 const char *lo
= snapshot
->start
;
549 * A pointer to a the first character of a record whose
550 * reference name comes *after* `refname`.
552 const char *hi
= snapshot
->eof
;
555 const char *mid
, *rec
;
558 mid
= lo
+ (hi
- lo
) / 2;
559 rec
= find_start_of_record(lo
, mid
);
560 cmp
= cmp_record_to_refname(rec
, refname
);
562 lo
= find_end_of_record(mid
, hi
);
563 } else if (cmp
> 0) {
577 * Create a newly-allocated `snapshot` of the `packed-refs` file in
578 * its current state and return it. The return value will already have
579 * its reference count incremented.
581 * A comment line of the form "# pack-refs with: " may contain zero or
582 * more traits. We interpret the traits as follows:
584 * Neither `peeled` nor `fully-peeled`:
586 * Probably no references are peeled. But if the file contains a
587 * peeled value for a reference, we will use it.
591 * References under "refs/tags/", if they *can* be peeled, *are*
592 * peeled in this file. References outside of "refs/tags/" are
593 * probably not peeled even if they could have been, but if we find
594 * a peeled value for such a reference we will use it.
598 * All references in the file that can be peeled are peeled.
599 * Inversely (and this is more important), any references in the
600 * file for which no peeled value is recorded is not peelable. This
601 * trait should typically be written alongside "peeled" for
602 * compatibility with older clients, but we do not require it
603 * (i.e., "peeled" is a no-op if "fully-peeled" is set).
607 * The references in this file are known to be sorted by refname.
609 static struct snapshot
*create_snapshot(struct packed_ref_store
*refs
)
611 struct snapshot
*snapshot
= xcalloc(1, sizeof(*snapshot
));
614 snapshot
->refs
= refs
;
615 acquire_snapshot(snapshot
);
616 snapshot
->peeled
= PEELED_NONE
;
618 if (!load_contents(snapshot
))
621 /* If the file has a header line, process it: */
622 if (snapshot
->buf
< snapshot
->eof
&& *snapshot
->buf
== '#') {
624 struct string_list traits
= STRING_LIST_INIT_NODUP
;
626 eol
= memchr(snapshot
->buf
, '\n',
627 snapshot
->eof
- snapshot
->buf
);
629 die_unterminated_line(refs
->path
,
631 snapshot
->eof
- snapshot
->buf
);
633 tmp
= xmemdupz(snapshot
->buf
, eol
- snapshot
->buf
);
635 if (!skip_prefix(tmp
, "# pack-refs with:", (const char **)&p
))
636 die_invalid_line(refs
->path
,
638 snapshot
->eof
- snapshot
->buf
);
640 string_list_split_in_place(&traits
, p
, ' ', -1);
642 if (unsorted_string_list_has_string(&traits
, "fully-peeled"))
643 snapshot
->peeled
= PEELED_FULLY
;
644 else if (unsorted_string_list_has_string(&traits
, "peeled"))
645 snapshot
->peeled
= PEELED_TAGS
;
647 sorted
= unsorted_string_list_has_string(&traits
, "sorted");
649 /* perhaps other traits later as well */
651 /* The "+ 1" is for the LF character. */
652 snapshot
->start
= eol
+ 1;
654 string_list_clear(&traits
, 0);
658 verify_buffer_safe(snapshot
);
661 sort_snapshot(snapshot
);
664 * Reordering the records might have moved a short one
665 * to the end of the buffer, so verify the buffer's
668 verify_buffer_safe(snapshot
);
671 if (mmap_strategy
!= MMAP_OK
&& snapshot
->mmapped
) {
673 * We don't want to leave the file mmapped, so we are
674 * forced to make a copy now:
676 size_t size
= snapshot
->eof
- snapshot
->start
;
677 char *buf_copy
= xmalloc(size
);
679 memcpy(buf_copy
, snapshot
->start
, size
);
680 clear_snapshot_buffer(snapshot
);
681 snapshot
->buf
= snapshot
->start
= buf_copy
;
682 snapshot
->eof
= buf_copy
+ size
;
689 * Check that `refs->snapshot` (if present) still reflects the
690 * contents of the `packed-refs` file. If not, clear the snapshot.
692 static void validate_snapshot(struct packed_ref_store
*refs
)
694 if (refs
->snapshot
&&
695 !stat_validity_check(&refs
->snapshot
->validity
, refs
->path
))
696 clear_snapshot(refs
);
700 * Get the `snapshot` for the specified packed_ref_store, creating and
701 * populating it if it hasn't been read before or if the file has been
702 * changed (according to its `validity` field) since it was last read.
703 * On the other hand, if we hold the lock, then assume that the file
704 * hasn't been changed out from under us, so skip the extra `stat()`
705 * call in `stat_validity_check()`. This function does *not* increase
706 * the snapshot's reference count on behalf of the caller.
708 static struct snapshot
*get_snapshot(struct packed_ref_store
*refs
)
710 if (!is_lock_file_locked(&refs
->lock
))
711 validate_snapshot(refs
);
714 refs
->snapshot
= create_snapshot(refs
);
716 return refs
->snapshot
;
719 static int packed_read_raw_ref(struct ref_store
*ref_store
,
720 const char *refname
, unsigned char *sha1
,
721 struct strbuf
*referent
, unsigned int *type
)
723 struct packed_ref_store
*refs
=
724 packed_downcast(ref_store
, REF_STORE_READ
, "read_raw_ref");
725 struct snapshot
*snapshot
= get_snapshot(refs
);
730 rec
= find_reference_location(snapshot
, refname
, 1);
733 /* refname is not a packed reference. */
738 if (get_sha1_hex(rec
, sha1
))
739 die_invalid_line(refs
->path
, rec
, snapshot
->eof
- rec
);
741 *type
= REF_ISPACKED
;
746 * This value is set in `base.flags` if the peeled value of the
747 * current reference is known. In that case, `peeled` contains the
748 * correct peeled value for the reference, which might be `null_sha1`
749 * if the reference is not a tag or if it is broken.
751 #define REF_KNOWS_PEELED 0x40
754 * An iterator over a snapshot of a `packed-refs` file.
756 struct packed_ref_iterator
{
757 struct ref_iterator base
;
759 struct snapshot
*snapshot
;
761 /* The current position in the snapshot's buffer: */
764 /* The end of the part of the buffer that will be iterated over: */
767 /* Scratch space for current values: */
768 struct object_id oid
, peeled
;
769 struct strbuf refname_buf
;
775 * Move the iterator to the next record in the snapshot, without
776 * respect for whether the record is actually required by the current
777 * iteration. Adjust the fields in `iter` and return `ITER_OK` or
778 * `ITER_DONE`. This function does not free the iterator in the case
781 static int next_record(struct packed_ref_iterator
*iter
)
783 const char *p
= iter
->pos
, *eol
;
785 strbuf_reset(&iter
->refname_buf
);
787 if (iter
->pos
== iter
->eof
)
790 iter
->base
.flags
= REF_ISPACKED
;
792 if (iter
->eof
- p
< GIT_SHA1_HEXSZ
+ 2 ||
793 parse_oid_hex(p
, &iter
->oid
, &p
) ||
795 die_invalid_line(iter
->snapshot
->refs
->path
,
796 iter
->pos
, iter
->eof
- iter
->pos
);
798 eol
= memchr(p
, '\n', iter
->eof
- p
);
800 die_unterminated_line(iter
->snapshot
->refs
->path
,
801 iter
->pos
, iter
->eof
- iter
->pos
);
803 strbuf_add(&iter
->refname_buf
, p
, eol
- p
);
804 iter
->base
.refname
= iter
->refname_buf
.buf
;
806 if (check_refname_format(iter
->base
.refname
, REFNAME_ALLOW_ONELEVEL
)) {
807 if (!refname_is_safe(iter
->base
.refname
))
808 die("packed refname is dangerous: %s",
811 iter
->base
.flags
|= REF_BAD_NAME
| REF_ISBROKEN
;
813 if (iter
->snapshot
->peeled
== PEELED_FULLY
||
814 (iter
->snapshot
->peeled
== PEELED_TAGS
&&
815 starts_with(iter
->base
.refname
, "refs/tags/")))
816 iter
->base
.flags
|= REF_KNOWS_PEELED
;
820 if (iter
->pos
< iter
->eof
&& *iter
->pos
== '^') {
822 if (iter
->eof
- p
< GIT_SHA1_HEXSZ
+ 1 ||
823 parse_oid_hex(p
, &iter
->peeled
, &p
) ||
825 die_invalid_line(iter
->snapshot
->refs
->path
,
826 iter
->pos
, iter
->eof
- iter
->pos
);
830 * Regardless of what the file header said, we
831 * definitely know the value of *this* reference. But
832 * we suppress it if the reference is broken:
834 if ((iter
->base
.flags
& REF_ISBROKEN
)) {
835 oidclr(&iter
->peeled
);
836 iter
->base
.flags
&= ~REF_KNOWS_PEELED
;
838 iter
->base
.flags
|= REF_KNOWS_PEELED
;
841 oidclr(&iter
->peeled
);
847 static int packed_ref_iterator_advance(struct ref_iterator
*ref_iterator
)
849 struct packed_ref_iterator
*iter
=
850 (struct packed_ref_iterator
*)ref_iterator
;
853 while ((ok
= next_record(iter
)) == ITER_OK
) {
854 if (iter
->flags
& DO_FOR_EACH_PER_WORKTREE_ONLY
&&
855 ref_type(iter
->base
.refname
) != REF_TYPE_PER_WORKTREE
)
858 if (!(iter
->flags
& DO_FOR_EACH_INCLUDE_BROKEN
) &&
859 !ref_resolves_to_object(iter
->base
.refname
, &iter
->oid
,
866 if (ref_iterator_abort(ref_iterator
) != ITER_DONE
)
872 static int packed_ref_iterator_peel(struct ref_iterator
*ref_iterator
,
873 struct object_id
*peeled
)
875 struct packed_ref_iterator
*iter
=
876 (struct packed_ref_iterator
*)ref_iterator
;
878 if ((iter
->base
.flags
& REF_KNOWS_PEELED
)) {
879 oidcpy(peeled
, &iter
->peeled
);
880 return is_null_oid(&iter
->peeled
) ? -1 : 0;
881 } else if ((iter
->base
.flags
& (REF_ISBROKEN
| REF_ISSYMREF
))) {
884 return !!peel_object(iter
->oid
.hash
, peeled
->hash
);
888 static int packed_ref_iterator_abort(struct ref_iterator
*ref_iterator
)
890 struct packed_ref_iterator
*iter
=
891 (struct packed_ref_iterator
*)ref_iterator
;
894 strbuf_release(&iter
->refname_buf
);
895 release_snapshot(iter
->snapshot
);
896 base_ref_iterator_free(ref_iterator
);
900 static struct ref_iterator_vtable packed_ref_iterator_vtable
= {
901 packed_ref_iterator_advance
,
902 packed_ref_iterator_peel
,
903 packed_ref_iterator_abort
906 static struct ref_iterator
*packed_ref_iterator_begin(
907 struct ref_store
*ref_store
,
908 const char *prefix
, unsigned int flags
)
910 struct packed_ref_store
*refs
;
911 struct snapshot
*snapshot
;
913 struct packed_ref_iterator
*iter
;
914 struct ref_iterator
*ref_iterator
;
915 unsigned int required_flags
= REF_STORE_READ
;
917 if (!(flags
& DO_FOR_EACH_INCLUDE_BROKEN
))
918 required_flags
|= REF_STORE_ODB
;
919 refs
= packed_downcast(ref_store
, required_flags
, "ref_iterator_begin");
922 * Note that `get_snapshot()` internally checks whether the
923 * snapshot is up to date with what is on disk, and re-reads
926 snapshot
= get_snapshot(refs
);
929 return empty_ref_iterator_begin();
931 iter
= xcalloc(1, sizeof(*iter
));
932 ref_iterator
= &iter
->base
;
933 base_ref_iterator_init(ref_iterator
, &packed_ref_iterator_vtable
, 1);
935 iter
->snapshot
= snapshot
;
936 acquire_snapshot(snapshot
);
938 if (prefix
&& *prefix
)
939 start
= find_reference_location(snapshot
, prefix
, 0);
941 start
= snapshot
->start
;
944 iter
->eof
= snapshot
->eof
;
945 strbuf_init(&iter
->refname_buf
, 0);
947 iter
->base
.oid
= &iter
->oid
;
951 if (prefix
&& *prefix
)
952 /* Stop iteration after we've gone *past* prefix: */
953 ref_iterator
= prefix_ref_iterator_begin(ref_iterator
, prefix
, 0);
959 * Write an entry to the packed-refs file for the specified refname.
960 * If peeled is non-NULL, write it as the entry's peeled value. On
961 * error, return a nonzero value and leave errno set at the value left
962 * by the failing call to `fprintf()`.
964 static int write_packed_entry(FILE *fh
, const char *refname
,
965 const unsigned char *sha1
,
966 const unsigned char *peeled
)
968 if (fprintf(fh
, "%s %s\n", sha1_to_hex(sha1
), refname
) < 0 ||
969 (peeled
&& fprintf(fh
, "^%s\n", sha1_to_hex(peeled
)) < 0))
975 int packed_refs_lock(struct ref_store
*ref_store
, int flags
, struct strbuf
*err
)
977 struct packed_ref_store
*refs
=
978 packed_downcast(ref_store
, REF_STORE_WRITE
| REF_STORE_MAIN
,
980 static int timeout_configured
= 0;
981 static int timeout_value
= 1000;
983 if (!timeout_configured
) {
984 git_config_get_int("core.packedrefstimeout", &timeout_value
);
985 timeout_configured
= 1;
989 * Note that we close the lockfile immediately because we
990 * don't write new content to it, but rather to a separate
993 if (hold_lock_file_for_update_timeout(
996 flags
, timeout_value
) < 0) {
997 unable_to_lock_message(refs
->path
, errno
, err
);
1001 if (close_lock_file_gently(&refs
->lock
)) {
1002 strbuf_addf(err
, "unable to close %s: %s", refs
->path
, strerror(errno
));
1003 rollback_lock_file(&refs
->lock
);
1008 * Now that we hold the `packed-refs` lock, make sure that our
1009 * snapshot matches the current version of the file. Normally
1010 * `get_snapshot()` does that for us, but that function
1011 * assumes that when the file is locked, any existing snapshot
1012 * is still valid. We've just locked the file, but it might
1013 * have changed the moment *before* we locked it.
1015 validate_snapshot(refs
);
1018 * Now make sure that the packed-refs file as it exists in the
1019 * locked state is loaded into the snapshot:
1025 void packed_refs_unlock(struct ref_store
*ref_store
)
1027 struct packed_ref_store
*refs
= packed_downcast(
1029 REF_STORE_READ
| REF_STORE_WRITE
,
1030 "packed_refs_unlock");
1032 if (!is_lock_file_locked(&refs
->lock
))
1033 die("BUG: packed_refs_unlock() called when not locked");
1034 rollback_lock_file(&refs
->lock
);
1037 int packed_refs_is_locked(struct ref_store
*ref_store
)
1039 struct packed_ref_store
*refs
= packed_downcast(
1041 REF_STORE_READ
| REF_STORE_WRITE
,
1042 "packed_refs_is_locked");
1044 return is_lock_file_locked(&refs
->lock
);
1048 * The packed-refs header line that we write out. Perhaps other traits
1049 * will be added later.
1051 * Note that earlier versions of Git used to parse these traits by
1052 * looking for " trait " in the line. For this reason, the space after
1053 * the colon and the trailing space are required.
1055 static const char PACKED_REFS_HEADER
[] =
1056 "# pack-refs with: peeled fully-peeled sorted \n";
1058 static int packed_init_db(struct ref_store
*ref_store
, struct strbuf
*err
)
1060 /* Nothing to do. */
1065 * Write the packed refs from the current snapshot to the packed-refs
1066 * tempfile, incorporating any changes from `updates`. `updates` must
1067 * be a sorted string list whose keys are the refnames and whose util
1068 * values are `struct ref_update *`. On error, rollback the tempfile,
1069 * write an error message to `err`, and return a nonzero value.
1071 * The packfile must be locked before calling this function and will
1072 * remain locked when it is done.
1074 static int write_with_updates(struct packed_ref_store
*refs
,
1075 struct string_list
*updates
,
1078 struct ref_iterator
*iter
= NULL
;
1082 struct strbuf sb
= STRBUF_INIT
;
1083 char *packed_refs_path
;
1085 if (!is_lock_file_locked(&refs
->lock
))
1086 die("BUG: write_with_updates() called while unlocked");
1089 * If packed-refs is a symlink, we want to overwrite the
1090 * symlinked-to file, not the symlink itself. Also, put the
1091 * staging file next to it:
1093 packed_refs_path
= get_locked_file_path(&refs
->lock
);
1094 strbuf_addf(&sb
, "%s.new", packed_refs_path
);
1095 free(packed_refs_path
);
1096 refs
->tempfile
= create_tempfile(sb
.buf
);
1097 if (!refs
->tempfile
) {
1098 strbuf_addf(err
, "unable to create file %s: %s",
1099 sb
.buf
, strerror(errno
));
1100 strbuf_release(&sb
);
1103 strbuf_release(&sb
);
1105 out
= fdopen_tempfile(refs
->tempfile
, "w");
1107 strbuf_addf(err
, "unable to fdopen packed-refs tempfile: %s",
1112 if (fprintf(out
, "%s", PACKED_REFS_HEADER
) < 0)
1116 * We iterate in parallel through the current list of refs and
1117 * the list of updates, processing an entry from at least one
1118 * of the lists each time through the loop. When the current
1119 * list of refs is exhausted, set iter to NULL. When the list
1120 * of updates is exhausted, leave i set to updates->nr.
1122 iter
= packed_ref_iterator_begin(&refs
->base
, "",
1123 DO_FOR_EACH_INCLUDE_BROKEN
);
1124 if ((ok
= ref_iterator_advance(iter
)) != ITER_OK
)
1129 while (iter
|| i
< updates
->nr
) {
1130 struct ref_update
*update
= NULL
;
1133 if (i
>= updates
->nr
) {
1136 update
= updates
->items
[i
].util
;
1141 cmp
= strcmp(iter
->refname
, update
->refname
);
1146 * There is both an old value and an update
1147 * for this reference. Check the old value if
1150 if ((update
->flags
& REF_HAVE_OLD
)) {
1151 if (is_null_oid(&update
->old_oid
)) {
1152 strbuf_addf(err
, "cannot update ref '%s': "
1153 "reference already exists",
1156 } else if (oidcmp(&update
->old_oid
, iter
->oid
)) {
1157 strbuf_addf(err
, "cannot update ref '%s': "
1158 "is at %s but expected %s",
1160 oid_to_hex(iter
->oid
),
1161 oid_to_hex(&update
->old_oid
));
1166 /* Now figure out what to use for the new value: */
1167 if ((update
->flags
& REF_HAVE_NEW
)) {
1169 * The update takes precedence. Skip
1170 * the iterator over the unneeded
1173 if ((ok
= ref_iterator_advance(iter
)) != ITER_OK
)
1178 * The update doesn't actually want to
1179 * change anything. We're done with it.
1184 } else if (cmp
> 0) {
1186 * There is no old value but there is an
1187 * update for this reference. Make sure that
1188 * the update didn't expect an existing value:
1190 if ((update
->flags
& REF_HAVE_OLD
) &&
1191 !is_null_oid(&update
->old_oid
)) {
1192 strbuf_addf(err
, "cannot update ref '%s': "
1193 "reference is missing but expected %s",
1195 oid_to_hex(&update
->old_oid
));
1201 /* Pass the old reference through. */
1203 struct object_id peeled
;
1204 int peel_error
= ref_iterator_peel(iter
, &peeled
);
1206 if (write_packed_entry(out
, iter
->refname
,
1208 peel_error
? NULL
: peeled
.hash
))
1211 if ((ok
= ref_iterator_advance(iter
)) != ITER_OK
)
1213 } else if (is_null_oid(&update
->new_oid
)) {
1215 * The update wants to delete the reference,
1216 * and the reference either didn't exist or we
1217 * have already skipped it. So we're done with
1218 * the update (and don't have to write
1223 struct object_id peeled
;
1224 int peel_error
= peel_object(update
->new_oid
.hash
,
1227 if (write_packed_entry(out
, update
->refname
,
1228 update
->new_oid
.hash
,
1229 peel_error
? NULL
: peeled
.hash
))
1236 if (ok
!= ITER_DONE
) {
1237 strbuf_addstr(err
, "unable to write packed-refs file: "
1238 "error iterating over old contents");
1242 if (close_tempfile_gently(refs
->tempfile
)) {
1243 strbuf_addf(err
, "error closing file %s: %s",
1244 get_tempfile_path(refs
->tempfile
),
1246 strbuf_release(&sb
);
1247 delete_tempfile(&refs
->tempfile
);
1254 strbuf_addf(err
, "error writing to %s: %s",
1255 get_tempfile_path(refs
->tempfile
), strerror(errno
));
1259 ref_iterator_abort(iter
);
1261 delete_tempfile(&refs
->tempfile
);
1265 int is_packed_transaction_needed(struct ref_store
*ref_store
,
1266 struct ref_transaction
*transaction
)
1268 struct packed_ref_store
*refs
= packed_downcast(
1271 "is_packed_transaction_needed");
1272 struct strbuf referent
= STRBUF_INIT
;
1276 if (!is_lock_file_locked(&refs
->lock
))
1277 BUG("is_packed_transaction_needed() called while unlocked");
1280 * We're only going to bother returning false for the common,
1281 * trivial case that references are only being deleted, their
1282 * old values are not being checked, and the old `packed-refs`
1283 * file doesn't contain any of those reference(s). This gives
1284 * false positives for some other cases that could
1285 * theoretically be optimized away:
1287 * 1. It could be that the old value is being verified without
1288 * setting a new value. In this case, we could verify the
1289 * old value here and skip the update if it agrees. If it
1290 * disagrees, we could either let the update go through
1291 * (the actual commit would re-detect and report the
1292 * problem), or come up with a way of reporting such an
1293 * error to *our* caller.
1295 * 2. It could be that a new value is being set, but that it
1296 * is identical to the current packed value of the
1299 * Neither of these cases will come up in the current code,
1300 * because the only caller of this function passes to it a
1301 * transaction that only includes `delete` updates with no
1302 * `old_id`. Even if that ever changes, false positives only
1303 * cause an optimization to be missed; they do not affect
1308 * Start with the cheap checks that don't require old
1309 * reference values to be read:
1311 for (i
= 0; i
< transaction
->nr
; i
++) {
1312 struct ref_update
*update
= transaction
->updates
[i
];
1314 if (update
->flags
& REF_HAVE_OLD
)
1315 /* Have to check the old value -> needed. */
1318 if ((update
->flags
& REF_HAVE_NEW
) && !is_null_oid(&update
->new_oid
))
1319 /* Have to set a new value -> needed. */
1324 * The transaction isn't checking any old values nor is it
1325 * setting any nonzero new values, so it still might be able
1326 * to be skipped. Now do the more expensive check: the update
1327 * is needed if any of the updates is a delete, and the old
1328 * `packed-refs` file contains a value for that reference.
1331 for (i
= 0; i
< transaction
->nr
; i
++) {
1332 struct ref_update
*update
= transaction
->updates
[i
];
1334 struct object_id oid
;
1336 if (!(update
->flags
& REF_HAVE_NEW
))
1338 * This reference isn't being deleted -> not
1343 if (!refs_read_raw_ref(ref_store
, update
->refname
,
1344 oid
.hash
, &referent
, &type
) ||
1347 * We have to actually delete that reference
1348 * -> this transaction is needed.
1355 strbuf_release(&referent
);
1359 struct packed_transaction_backend_data
{
1360 /* True iff the transaction owns the packed-refs lock. */
1363 struct string_list updates
;
1366 static void packed_transaction_cleanup(struct packed_ref_store
*refs
,
1367 struct ref_transaction
*transaction
)
1369 struct packed_transaction_backend_data
*data
= transaction
->backend_data
;
1372 string_list_clear(&data
->updates
, 0);
1374 if (is_tempfile_active(refs
->tempfile
))
1375 delete_tempfile(&refs
->tempfile
);
1377 if (data
->own_lock
&& is_lock_file_locked(&refs
->lock
)) {
1378 packed_refs_unlock(&refs
->base
);
1383 transaction
->backend_data
= NULL
;
1386 transaction
->state
= REF_TRANSACTION_CLOSED
;
1389 static int packed_transaction_prepare(struct ref_store
*ref_store
,
1390 struct ref_transaction
*transaction
,
1393 struct packed_ref_store
*refs
= packed_downcast(
1395 REF_STORE_READ
| REF_STORE_WRITE
| REF_STORE_ODB
,
1396 "ref_transaction_prepare");
1397 struct packed_transaction_backend_data
*data
;
1399 int ret
= TRANSACTION_GENERIC_ERROR
;
1402 * Note that we *don't* skip transactions with zero updates,
1403 * because such a transaction might be executed for the side
1404 * effect of ensuring that all of the references are peeled or
1405 * ensuring that the `packed-refs` file is sorted. If the
1406 * caller wants to optimize away empty transactions, it should
1410 data
= xcalloc(1, sizeof(*data
));
1411 string_list_init(&data
->updates
, 0);
1413 transaction
->backend_data
= data
;
1416 * Stick the updates in a string list by refname so that we
1419 for (i
= 0; i
< transaction
->nr
; i
++) {
1420 struct ref_update
*update
= transaction
->updates
[i
];
1421 struct string_list_item
*item
=
1422 string_list_append(&data
->updates
, update
->refname
);
1424 /* Store a pointer to update in item->util: */
1425 item
->util
= update
;
1427 string_list_sort(&data
->updates
);
1429 if (ref_update_reject_duplicates(&data
->updates
, err
))
1432 if (!is_lock_file_locked(&refs
->lock
)) {
1433 if (packed_refs_lock(ref_store
, 0, err
))
1438 if (write_with_updates(refs
, &data
->updates
, err
))
1441 transaction
->state
= REF_TRANSACTION_PREPARED
;
1445 packed_transaction_cleanup(refs
, transaction
);
1449 static int packed_transaction_abort(struct ref_store
*ref_store
,
1450 struct ref_transaction
*transaction
,
1453 struct packed_ref_store
*refs
= packed_downcast(
1455 REF_STORE_READ
| REF_STORE_WRITE
| REF_STORE_ODB
,
1456 "ref_transaction_abort");
1458 packed_transaction_cleanup(refs
, transaction
);
1462 static int packed_transaction_finish(struct ref_store
*ref_store
,
1463 struct ref_transaction
*transaction
,
1466 struct packed_ref_store
*refs
= packed_downcast(
1468 REF_STORE_READ
| REF_STORE_WRITE
| REF_STORE_ODB
,
1469 "ref_transaction_finish");
1470 int ret
= TRANSACTION_GENERIC_ERROR
;
1471 char *packed_refs_path
;
1473 clear_snapshot(refs
);
1475 packed_refs_path
= get_locked_file_path(&refs
->lock
);
1476 if (rename_tempfile(&refs
->tempfile
, packed_refs_path
)) {
1477 strbuf_addf(err
, "error replacing %s: %s",
1478 refs
->path
, strerror(errno
));
1485 free(packed_refs_path
);
1486 packed_transaction_cleanup(refs
, transaction
);
1490 static int packed_initial_transaction_commit(struct ref_store
*ref_store
,
1491 struct ref_transaction
*transaction
,
1494 return ref_transaction_commit(transaction
, err
);
1497 static int packed_delete_refs(struct ref_store
*ref_store
, const char *msg
,
1498 struct string_list
*refnames
, unsigned int flags
)
1500 struct packed_ref_store
*refs
=
1501 packed_downcast(ref_store
, REF_STORE_WRITE
, "delete_refs");
1502 struct strbuf err
= STRBUF_INIT
;
1503 struct ref_transaction
*transaction
;
1504 struct string_list_item
*item
;
1507 (void)refs
; /* We need the check above, but don't use the variable */
1513 * Since we don't check the references' old_oids, the
1514 * individual updates can't fail, so we can pack all of the
1515 * updates into a single transaction.
1518 transaction
= ref_store_transaction_begin(ref_store
, &err
);
1522 for_each_string_list_item(item
, refnames
) {
1523 if (ref_transaction_delete(transaction
, item
->string
, NULL
,
1524 flags
, msg
, &err
)) {
1525 warning(_("could not delete reference %s: %s"),
1526 item
->string
, err
.buf
);
1531 ret
= ref_transaction_commit(transaction
, &err
);
1534 if (refnames
->nr
== 1)
1535 error(_("could not delete reference %s: %s"),
1536 refnames
->items
[0].string
, err
.buf
);
1538 error(_("could not delete references: %s"), err
.buf
);
1541 ref_transaction_free(transaction
);
1542 strbuf_release(&err
);
1546 static int packed_pack_refs(struct ref_store
*ref_store
, unsigned int flags
)
1549 * Packed refs are already packed. It might be that loose refs
1550 * are packed *into* a packed refs store, but that is done by
1551 * updating the packed references via a transaction.
1556 static int packed_create_symref(struct ref_store
*ref_store
,
1557 const char *refname
, const char *target
,
1560 die("BUG: packed reference store does not support symrefs");
1563 static int packed_rename_ref(struct ref_store
*ref_store
,
1564 const char *oldrefname
, const char *newrefname
,
1567 die("BUG: packed reference store does not support renaming references");
1570 static int packed_copy_ref(struct ref_store
*ref_store
,
1571 const char *oldrefname
, const char *newrefname
,
1574 die("BUG: packed reference store does not support copying references");
1577 static struct ref_iterator
*packed_reflog_iterator_begin(struct ref_store
*ref_store
)
1579 return empty_ref_iterator_begin();
1582 static int packed_for_each_reflog_ent(struct ref_store
*ref_store
,
1583 const char *refname
,
1584 each_reflog_ent_fn fn
, void *cb_data
)
1589 static int packed_for_each_reflog_ent_reverse(struct ref_store
*ref_store
,
1590 const char *refname
,
1591 each_reflog_ent_fn fn
,
1597 static int packed_reflog_exists(struct ref_store
*ref_store
,
1598 const char *refname
)
1603 static int packed_create_reflog(struct ref_store
*ref_store
,
1604 const char *refname
, int force_create
,
1607 die("BUG: packed reference store does not support reflogs");
1610 static int packed_delete_reflog(struct ref_store
*ref_store
,
1611 const char *refname
)
1616 static int packed_reflog_expire(struct ref_store
*ref_store
,
1617 const char *refname
, const unsigned char *sha1
,
1619 reflog_expiry_prepare_fn prepare_fn
,
1620 reflog_expiry_should_prune_fn should_prune_fn
,
1621 reflog_expiry_cleanup_fn cleanup_fn
,
1622 void *policy_cb_data
)
1627 struct ref_storage_be refs_be_packed
= {
1630 packed_ref_store_create
,
1632 packed_transaction_prepare
,
1633 packed_transaction_finish
,
1634 packed_transaction_abort
,
1635 packed_initial_transaction_commit
,
1638 packed_create_symref
,
1643 packed_ref_iterator_begin
,
1644 packed_read_raw_ref
,
1646 packed_reflog_iterator_begin
,
1647 packed_for_each_reflog_ent
,
1648 packed_for_each_reflog_ent_reverse
,
1649 packed_reflog_exists
,
1650 packed_create_reflog
,
1651 packed_delete_reflog
,
1652 packed_reflog_expire