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57 * `get_snapshot()` is called; if the existing snapshot is obsolete, a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
);
461 #define SMALL_FILE_SIZE (32*1024)
464 * Depending on `mmap_strategy`, either mmap or read the contents of
465 * the `packed-refs` file into the snapshot. Return 1 if the file
466 * existed and was read, or 0 if the file was absent or empty. Die on
469 static int load_contents(struct snapshot
*snapshot
)
476 fd
= open(snapshot
->refs
->path
, O_RDONLY
);
478 if (errno
== ENOENT
) {
480 * This is OK; it just means that no
481 * "packed-refs" file has been written yet,
482 * which is equivalent to it being empty,
483 * which is its state when initialized with
488 die_errno("couldn't read %s", snapshot
->refs
->path
);
492 stat_validity_update(&snapshot
->validity
, fd
);
494 if (fstat(fd
, &st
) < 0)
495 die_errno("couldn't stat %s", snapshot
->refs
->path
);
496 size
= xsize_t(st
.st_size
);
500 } else if (mmap_strategy
== MMAP_NONE
|| size
<= SMALL_FILE_SIZE
) {
501 snapshot
->buf
= xmalloc(size
);
502 bytes_read
= read_in_full(fd
, snapshot
->buf
, size
);
503 if (bytes_read
< 0 || bytes_read
!= size
)
504 die_errno("couldn't read %s", snapshot
->refs
->path
);
505 snapshot
->mmapped
= 0;
507 snapshot
->buf
= xmmap(NULL
, size
, PROT_READ
, MAP_PRIVATE
, fd
, 0);
508 snapshot
->mmapped
= 1;
512 snapshot
->start
= snapshot
->buf
;
513 snapshot
->eof
= snapshot
->buf
+ size
;
519 * Find the place in `snapshot->buf` where the start of the record for
520 * `refname` starts. If `mustexist` is true and the reference doesn't
521 * exist, then return NULL. If `mustexist` is false and the reference
522 * doesn't exist, then return the point where that reference would be
523 * inserted, or `snapshot->eof` (which might be NULL) if it would be
524 * inserted at the end of the file. In the latter mode, `refname`
525 * doesn't have to be a proper reference name; for example, one could
526 * search for "refs/replace/" to find the start of any replace
529 * The record is sought using a binary search, so `snapshot->buf` must
532 static const char *find_reference_location(struct snapshot
*snapshot
,
533 const char *refname
, int mustexist
)
536 * This is not *quite* a garden-variety binary search, because
537 * the data we're searching is made up of records, and we
538 * always need to find the beginning of a record to do a
539 * comparison. A "record" here is one line for the reference
540 * itself and zero or one peel lines that start with '^'. Our
541 * loop invariant is described in the next two comments.
545 * A pointer to the character at the start of a record whose
546 * preceding records all have reference names that come
547 * *before* `refname`.
549 const char *lo
= snapshot
->start
;
552 * A pointer to a the first character of a record whose
553 * reference name comes *after* `refname`.
555 const char *hi
= snapshot
->eof
;
558 const char *mid
, *rec
;
561 mid
= lo
+ (hi
- lo
) / 2;
562 rec
= find_start_of_record(lo
, mid
);
563 cmp
= cmp_record_to_refname(rec
, refname
);
565 lo
= find_end_of_record(mid
, hi
);
566 } else if (cmp
> 0) {
580 * Create a newly-allocated `snapshot` of the `packed-refs` file in
581 * its current state and return it. The return value will already have
582 * its reference count incremented.
584 * A comment line of the form "# pack-refs with: " may contain zero or
585 * more traits. We interpret the traits as follows:
587 * Neither `peeled` nor `fully-peeled`:
589 * Probably no references are peeled. But if the file contains a
590 * peeled value for a reference, we will use it.
594 * References under "refs/tags/", if they *can* be peeled, *are*
595 * peeled in this file. References outside of "refs/tags/" are
596 * probably not peeled even if they could have been, but if we find
597 * a peeled value for such a reference we will use it.
601 * All references in the file that can be peeled are peeled.
602 * Inversely (and this is more important), any references in the
603 * file for which no peeled value is recorded is not peelable. This
604 * trait should typically be written alongside "peeled" for
605 * compatibility with older clients, but we do not require it
606 * (i.e., "peeled" is a no-op if "fully-peeled" is set).
610 * The references in this file are known to be sorted by refname.
612 static struct snapshot
*create_snapshot(struct packed_ref_store
*refs
)
614 struct snapshot
*snapshot
= xcalloc(1, sizeof(*snapshot
));
617 snapshot
->refs
= refs
;
618 acquire_snapshot(snapshot
);
619 snapshot
->peeled
= PEELED_NONE
;
621 if (!load_contents(snapshot
))
624 /* If the file has a header line, process it: */
625 if (snapshot
->buf
< snapshot
->eof
&& *snapshot
->buf
== '#') {
627 struct string_list traits
= STRING_LIST_INIT_NODUP
;
629 eol
= memchr(snapshot
->buf
, '\n',
630 snapshot
->eof
- snapshot
->buf
);
632 die_unterminated_line(refs
->path
,
634 snapshot
->eof
- snapshot
->buf
);
636 tmp
= xmemdupz(snapshot
->buf
, eol
- snapshot
->buf
);
638 if (!skip_prefix(tmp
, "# pack-refs with:", (const char **)&p
))
639 die_invalid_line(refs
->path
,
641 snapshot
->eof
- snapshot
->buf
);
643 string_list_split_in_place(&traits
, p
, ' ', -1);
645 if (unsorted_string_list_has_string(&traits
, "fully-peeled"))
646 snapshot
->peeled
= PEELED_FULLY
;
647 else if (unsorted_string_list_has_string(&traits
, "peeled"))
648 snapshot
->peeled
= PEELED_TAGS
;
650 sorted
= unsorted_string_list_has_string(&traits
, "sorted");
652 /* perhaps other traits later as well */
654 /* The "+ 1" is for the LF character. */
655 snapshot
->start
= eol
+ 1;
657 string_list_clear(&traits
, 0);
661 verify_buffer_safe(snapshot
);
664 sort_snapshot(snapshot
);
667 * Reordering the records might have moved a short one
668 * to the end of the buffer, so verify the buffer's
671 verify_buffer_safe(snapshot
);
674 if (mmap_strategy
!= MMAP_OK
&& snapshot
->mmapped
) {
676 * We don't want to leave the file mmapped, so we are
677 * forced to make a copy now:
679 size_t size
= snapshot
->eof
- snapshot
->start
;
680 char *buf_copy
= xmalloc(size
);
682 memcpy(buf_copy
, snapshot
->start
, size
);
683 clear_snapshot_buffer(snapshot
);
684 snapshot
->buf
= snapshot
->start
= buf_copy
;
685 snapshot
->eof
= buf_copy
+ size
;
692 * Check that `refs->snapshot` (if present) still reflects the
693 * contents of the `packed-refs` file. If not, clear the snapshot.
695 static void validate_snapshot(struct packed_ref_store
*refs
)
697 if (refs
->snapshot
&&
698 !stat_validity_check(&refs
->snapshot
->validity
, refs
->path
))
699 clear_snapshot(refs
);
703 * Get the `snapshot` for the specified packed_ref_store, creating and
704 * populating it if it hasn't been read before or if the file has been
705 * changed (according to its `validity` field) since it was last read.
706 * On the other hand, if we hold the lock, then assume that the file
707 * hasn't been changed out from under us, so skip the extra `stat()`
708 * call in `stat_validity_check()`. This function does *not* increase
709 * the snapshot's reference count on behalf of the caller.
711 static struct snapshot
*get_snapshot(struct packed_ref_store
*refs
)
713 if (!is_lock_file_locked(&refs
->lock
))
714 validate_snapshot(refs
);
717 refs
->snapshot
= create_snapshot(refs
);
719 return refs
->snapshot
;
722 static int packed_read_raw_ref(struct ref_store
*ref_store
,
723 const char *refname
, struct object_id
*oid
,
724 struct strbuf
*referent
, unsigned int *type
)
726 struct packed_ref_store
*refs
=
727 packed_downcast(ref_store
, REF_STORE_READ
, "read_raw_ref");
728 struct snapshot
*snapshot
= get_snapshot(refs
);
733 rec
= find_reference_location(snapshot
, refname
, 1);
736 /* refname is not a packed reference. */
741 if (get_oid_hex(rec
, oid
))
742 die_invalid_line(refs
->path
, rec
, snapshot
->eof
- rec
);
744 *type
= REF_ISPACKED
;
749 * This value is set in `base.flags` if the peeled value of the
750 * current reference is known. In that case, `peeled` contains the
751 * correct peeled value for the reference, which might be `null_oid`
752 * if the reference is not a tag or if it is broken.
754 #define REF_KNOWS_PEELED 0x40
757 * An iterator over a snapshot of a `packed-refs` file.
759 struct packed_ref_iterator
{
760 struct ref_iterator base
;
762 struct snapshot
*snapshot
;
764 /* The current position in the snapshot's buffer: */
767 /* The end of the part of the buffer that will be iterated over: */
770 /* Scratch space for current values: */
771 struct object_id oid
, peeled
;
772 struct strbuf refname_buf
;
778 * Move the iterator to the next record in the snapshot, without
779 * respect for whether the record is actually required by the current
780 * iteration. Adjust the fields in `iter` and return `ITER_OK` or
781 * `ITER_DONE`. This function does not free the iterator in the case
784 static int next_record(struct packed_ref_iterator
*iter
)
786 const char *p
= iter
->pos
, *eol
;
788 strbuf_reset(&iter
->refname_buf
);
790 if (iter
->pos
== iter
->eof
)
793 iter
->base
.flags
= REF_ISPACKED
;
795 if (iter
->eof
- p
< GIT_SHA1_HEXSZ
+ 2 ||
796 parse_oid_hex(p
, &iter
->oid
, &p
) ||
798 die_invalid_line(iter
->snapshot
->refs
->path
,
799 iter
->pos
, iter
->eof
- iter
->pos
);
801 eol
= memchr(p
, '\n', iter
->eof
- p
);
803 die_unterminated_line(iter
->snapshot
->refs
->path
,
804 iter
->pos
, iter
->eof
- iter
->pos
);
806 strbuf_add(&iter
->refname_buf
, p
, eol
- p
);
807 iter
->base
.refname
= iter
->refname_buf
.buf
;
809 if (check_refname_format(iter
->base
.refname
, REFNAME_ALLOW_ONELEVEL
)) {
810 if (!refname_is_safe(iter
->base
.refname
))
811 die("packed refname is dangerous: %s",
814 iter
->base
.flags
|= REF_BAD_NAME
| REF_ISBROKEN
;
816 if (iter
->snapshot
->peeled
== PEELED_FULLY
||
817 (iter
->snapshot
->peeled
== PEELED_TAGS
&&
818 starts_with(iter
->base
.refname
, "refs/tags/")))
819 iter
->base
.flags
|= REF_KNOWS_PEELED
;
823 if (iter
->pos
< iter
->eof
&& *iter
->pos
== '^') {
825 if (iter
->eof
- p
< GIT_SHA1_HEXSZ
+ 1 ||
826 parse_oid_hex(p
, &iter
->peeled
, &p
) ||
828 die_invalid_line(iter
->snapshot
->refs
->path
,
829 iter
->pos
, iter
->eof
- iter
->pos
);
833 * Regardless of what the file header said, we
834 * definitely know the value of *this* reference. But
835 * we suppress it if the reference is broken:
837 if ((iter
->base
.flags
& REF_ISBROKEN
)) {
838 oidclr(&iter
->peeled
);
839 iter
->base
.flags
&= ~REF_KNOWS_PEELED
;
841 iter
->base
.flags
|= REF_KNOWS_PEELED
;
844 oidclr(&iter
->peeled
);
850 static int packed_ref_iterator_advance(struct ref_iterator
*ref_iterator
)
852 struct packed_ref_iterator
*iter
=
853 (struct packed_ref_iterator
*)ref_iterator
;
856 while ((ok
= next_record(iter
)) == ITER_OK
) {
857 if (iter
->flags
& DO_FOR_EACH_PER_WORKTREE_ONLY
&&
858 ref_type(iter
->base
.refname
) != REF_TYPE_PER_WORKTREE
)
861 if (!(iter
->flags
& DO_FOR_EACH_INCLUDE_BROKEN
) &&
862 !ref_resolves_to_object(iter
->base
.refname
, &iter
->oid
,
869 if (ref_iterator_abort(ref_iterator
) != ITER_DONE
)
875 static int packed_ref_iterator_peel(struct ref_iterator
*ref_iterator
,
876 struct object_id
*peeled
)
878 struct packed_ref_iterator
*iter
=
879 (struct packed_ref_iterator
*)ref_iterator
;
881 if ((iter
->base
.flags
& REF_KNOWS_PEELED
)) {
882 oidcpy(peeled
, &iter
->peeled
);
883 return is_null_oid(&iter
->peeled
) ? -1 : 0;
884 } else if ((iter
->base
.flags
& (REF_ISBROKEN
| REF_ISSYMREF
))) {
887 return !!peel_object(&iter
->oid
, peeled
);
891 static int packed_ref_iterator_abort(struct ref_iterator
*ref_iterator
)
893 struct packed_ref_iterator
*iter
=
894 (struct packed_ref_iterator
*)ref_iterator
;
897 strbuf_release(&iter
->refname_buf
);
898 release_snapshot(iter
->snapshot
);
899 base_ref_iterator_free(ref_iterator
);
903 static struct ref_iterator_vtable packed_ref_iterator_vtable
= {
904 packed_ref_iterator_advance
,
905 packed_ref_iterator_peel
,
906 packed_ref_iterator_abort
909 static struct ref_iterator
*packed_ref_iterator_begin(
910 struct ref_store
*ref_store
,
911 const char *prefix
, unsigned int flags
)
913 struct packed_ref_store
*refs
;
914 struct snapshot
*snapshot
;
916 struct packed_ref_iterator
*iter
;
917 struct ref_iterator
*ref_iterator
;
918 unsigned int required_flags
= REF_STORE_READ
;
920 if (!(flags
& DO_FOR_EACH_INCLUDE_BROKEN
))
921 required_flags
|= REF_STORE_ODB
;
922 refs
= packed_downcast(ref_store
, required_flags
, "ref_iterator_begin");
925 * Note that `get_snapshot()` internally checks whether the
926 * snapshot is up to date with what is on disk, and re-reads
929 snapshot
= get_snapshot(refs
);
931 if (prefix
&& *prefix
)
932 start
= find_reference_location(snapshot
, prefix
, 0);
934 start
= snapshot
->start
;
936 if (start
== snapshot
->eof
)
937 return empty_ref_iterator_begin();
939 iter
= xcalloc(1, sizeof(*iter
));
940 ref_iterator
= &iter
->base
;
941 base_ref_iterator_init(ref_iterator
, &packed_ref_iterator_vtable
, 1);
943 iter
->snapshot
= snapshot
;
944 acquire_snapshot(snapshot
);
947 iter
->eof
= snapshot
->eof
;
948 strbuf_init(&iter
->refname_buf
, 0);
950 iter
->base
.oid
= &iter
->oid
;
954 if (prefix
&& *prefix
)
955 /* Stop iteration after we've gone *past* prefix: */
956 ref_iterator
= prefix_ref_iterator_begin(ref_iterator
, prefix
, 0);
962 * Write an entry to the packed-refs file for the specified refname.
963 * If peeled is non-NULL, write it as the entry's peeled value. On
964 * error, return a nonzero value and leave errno set at the value left
965 * by the failing call to `fprintf()`.
967 static int write_packed_entry(FILE *fh
, const char *refname
,
968 const struct object_id
*oid
,
969 const struct object_id
*peeled
)
971 if (fprintf(fh
, "%s %s\n", oid_to_hex(oid
), refname
) < 0 ||
972 (peeled
&& fprintf(fh
, "^%s\n", oid_to_hex(peeled
)) < 0))
978 int packed_refs_lock(struct ref_store
*ref_store
, int flags
, struct strbuf
*err
)
980 struct packed_ref_store
*refs
=
981 packed_downcast(ref_store
, REF_STORE_WRITE
| REF_STORE_MAIN
,
983 static int timeout_configured
= 0;
984 static int timeout_value
= 1000;
986 if (!timeout_configured
) {
987 git_config_get_int("core.packedrefstimeout", &timeout_value
);
988 timeout_configured
= 1;
992 * Note that we close the lockfile immediately because we
993 * don't write new content to it, but rather to a separate
996 if (hold_lock_file_for_update_timeout(
999 flags
, timeout_value
) < 0) {
1000 unable_to_lock_message(refs
->path
, errno
, err
);
1004 if (close_lock_file_gently(&refs
->lock
)) {
1005 strbuf_addf(err
, "unable to close %s: %s", refs
->path
, strerror(errno
));
1006 rollback_lock_file(&refs
->lock
);
1011 * Now that we hold the `packed-refs` lock, make sure that our
1012 * snapshot matches the current version of the file. Normally
1013 * `get_snapshot()` does that for us, but that function
1014 * assumes that when the file is locked, any existing snapshot
1015 * is still valid. We've just locked the file, but it might
1016 * have changed the moment *before* we locked it.
1018 validate_snapshot(refs
);
1021 * Now make sure that the packed-refs file as it exists in the
1022 * locked state is loaded into the snapshot:
1028 void packed_refs_unlock(struct ref_store
*ref_store
)
1030 struct packed_ref_store
*refs
= packed_downcast(
1032 REF_STORE_READ
| REF_STORE_WRITE
,
1033 "packed_refs_unlock");
1035 if (!is_lock_file_locked(&refs
->lock
))
1036 die("BUG: packed_refs_unlock() called when not locked");
1037 rollback_lock_file(&refs
->lock
);
1040 int packed_refs_is_locked(struct ref_store
*ref_store
)
1042 struct packed_ref_store
*refs
= packed_downcast(
1044 REF_STORE_READ
| REF_STORE_WRITE
,
1045 "packed_refs_is_locked");
1047 return is_lock_file_locked(&refs
->lock
);
1051 * The packed-refs header line that we write out. Perhaps other traits
1052 * will be added later.
1054 * Note that earlier versions of Git used to parse these traits by
1055 * looking for " trait " in the line. For this reason, the space after
1056 * the colon and the trailing space are required.
1058 static const char PACKED_REFS_HEADER
[] =
1059 "# pack-refs with: peeled fully-peeled sorted \n";
1061 static int packed_init_db(struct ref_store
*ref_store
, struct strbuf
*err
)
1063 /* Nothing to do. */
1068 * Write the packed refs from the current snapshot to the packed-refs
1069 * tempfile, incorporating any changes from `updates`. `updates` must
1070 * be a sorted string list whose keys are the refnames and whose util
1071 * values are `struct ref_update *`. On error, rollback the tempfile,
1072 * write an error message to `err`, and return a nonzero value.
1074 * The packfile must be locked before calling this function and will
1075 * remain locked when it is done.
1077 static int write_with_updates(struct packed_ref_store
*refs
,
1078 struct string_list
*updates
,
1081 struct ref_iterator
*iter
= NULL
;
1085 struct strbuf sb
= STRBUF_INIT
;
1086 char *packed_refs_path
;
1088 if (!is_lock_file_locked(&refs
->lock
))
1089 die("BUG: write_with_updates() called while unlocked");
1092 * If packed-refs is a symlink, we want to overwrite the
1093 * symlinked-to file, not the symlink itself. Also, put the
1094 * staging file next to it:
1096 packed_refs_path
= get_locked_file_path(&refs
->lock
);
1097 strbuf_addf(&sb
, "%s.new", packed_refs_path
);
1098 free(packed_refs_path
);
1099 refs
->tempfile
= create_tempfile(sb
.buf
);
1100 if (!refs
->tempfile
) {
1101 strbuf_addf(err
, "unable to create file %s: %s",
1102 sb
.buf
, strerror(errno
));
1103 strbuf_release(&sb
);
1106 strbuf_release(&sb
);
1108 out
= fdopen_tempfile(refs
->tempfile
, "w");
1110 strbuf_addf(err
, "unable to fdopen packed-refs tempfile: %s",
1115 if (fprintf(out
, "%s", PACKED_REFS_HEADER
) < 0)
1119 * We iterate in parallel through the current list of refs and
1120 * the list of updates, processing an entry from at least one
1121 * of the lists each time through the loop. When the current
1122 * list of refs is exhausted, set iter to NULL. When the list
1123 * of updates is exhausted, leave i set to updates->nr.
1125 iter
= packed_ref_iterator_begin(&refs
->base
, "",
1126 DO_FOR_EACH_INCLUDE_BROKEN
);
1127 if ((ok
= ref_iterator_advance(iter
)) != ITER_OK
)
1132 while (iter
|| i
< updates
->nr
) {
1133 struct ref_update
*update
= NULL
;
1136 if (i
>= updates
->nr
) {
1139 update
= updates
->items
[i
].util
;
1144 cmp
= strcmp(iter
->refname
, update
->refname
);
1149 * There is both an old value and an update
1150 * for this reference. Check the old value if
1153 if ((update
->flags
& REF_HAVE_OLD
)) {
1154 if (is_null_oid(&update
->old_oid
)) {
1155 strbuf_addf(err
, "cannot update ref '%s': "
1156 "reference already exists",
1159 } else if (oidcmp(&update
->old_oid
, iter
->oid
)) {
1160 strbuf_addf(err
, "cannot update ref '%s': "
1161 "is at %s but expected %s",
1163 oid_to_hex(iter
->oid
),
1164 oid_to_hex(&update
->old_oid
));
1169 /* Now figure out what to use for the new value: */
1170 if ((update
->flags
& REF_HAVE_NEW
)) {
1172 * The update takes precedence. Skip
1173 * the iterator over the unneeded
1176 if ((ok
= ref_iterator_advance(iter
)) != ITER_OK
)
1181 * The update doesn't actually want to
1182 * change anything. We're done with it.
1187 } else if (cmp
> 0) {
1189 * There is no old value but there is an
1190 * update for this reference. Make sure that
1191 * the update didn't expect an existing value:
1193 if ((update
->flags
& REF_HAVE_OLD
) &&
1194 !is_null_oid(&update
->old_oid
)) {
1195 strbuf_addf(err
, "cannot update ref '%s': "
1196 "reference is missing but expected %s",
1198 oid_to_hex(&update
->old_oid
));
1204 /* Pass the old reference through. */
1206 struct object_id peeled
;
1207 int peel_error
= ref_iterator_peel(iter
, &peeled
);
1209 if (write_packed_entry(out
, iter
->refname
,
1211 peel_error
? NULL
: &peeled
))
1214 if ((ok
= ref_iterator_advance(iter
)) != ITER_OK
)
1216 } else if (is_null_oid(&update
->new_oid
)) {
1218 * The update wants to delete the reference,
1219 * and the reference either didn't exist or we
1220 * have already skipped it. So we're done with
1221 * the update (and don't have to write
1226 struct object_id peeled
;
1227 int peel_error
= peel_object(&update
->new_oid
,
1230 if (write_packed_entry(out
, update
->refname
,
1232 peel_error
? NULL
: &peeled
))
1239 if (ok
!= ITER_DONE
) {
1240 strbuf_addstr(err
, "unable to write packed-refs file: "
1241 "error iterating over old contents");
1245 if (close_tempfile_gently(refs
->tempfile
)) {
1246 strbuf_addf(err
, "error closing file %s: %s",
1247 get_tempfile_path(refs
->tempfile
),
1249 strbuf_release(&sb
);
1250 delete_tempfile(&refs
->tempfile
);
1257 strbuf_addf(err
, "error writing to %s: %s",
1258 get_tempfile_path(refs
->tempfile
), strerror(errno
));
1262 ref_iterator_abort(iter
);
1264 delete_tempfile(&refs
->tempfile
);
1268 int is_packed_transaction_needed(struct ref_store
*ref_store
,
1269 struct ref_transaction
*transaction
)
1271 struct packed_ref_store
*refs
= packed_downcast(
1274 "is_packed_transaction_needed");
1275 struct strbuf referent
= STRBUF_INIT
;
1279 if (!is_lock_file_locked(&refs
->lock
))
1280 BUG("is_packed_transaction_needed() called while unlocked");
1283 * We're only going to bother returning false for the common,
1284 * trivial case that references are only being deleted, their
1285 * old values are not being checked, and the old `packed-refs`
1286 * file doesn't contain any of those reference(s). This gives
1287 * false positives for some other cases that could
1288 * theoretically be optimized away:
1290 * 1. It could be that the old value is being verified without
1291 * setting a new value. In this case, we could verify the
1292 * old value here and skip the update if it agrees. If it
1293 * disagrees, we could either let the update go through
1294 * (the actual commit would re-detect and report the
1295 * problem), or come up with a way of reporting such an
1296 * error to *our* caller.
1298 * 2. It could be that a new value is being set, but that it
1299 * is identical to the current packed value of the
1302 * Neither of these cases will come up in the current code,
1303 * because the only caller of this function passes to it a
1304 * transaction that only includes `delete` updates with no
1305 * `old_id`. Even if that ever changes, false positives only
1306 * cause an optimization to be missed; they do not affect
1311 * Start with the cheap checks that don't require old
1312 * reference values to be read:
1314 for (i
= 0; i
< transaction
->nr
; i
++) {
1315 struct ref_update
*update
= transaction
->updates
[i
];
1317 if (update
->flags
& REF_HAVE_OLD
)
1318 /* Have to check the old value -> needed. */
1321 if ((update
->flags
& REF_HAVE_NEW
) && !is_null_oid(&update
->new_oid
))
1322 /* Have to set a new value -> needed. */
1327 * The transaction isn't checking any old values nor is it
1328 * setting any nonzero new values, so it still might be able
1329 * to be skipped. Now do the more expensive check: the update
1330 * is needed if any of the updates is a delete, and the old
1331 * `packed-refs` file contains a value for that reference.
1334 for (i
= 0; i
< transaction
->nr
; i
++) {
1335 struct ref_update
*update
= transaction
->updates
[i
];
1337 struct object_id oid
;
1339 if (!(update
->flags
& REF_HAVE_NEW
))
1341 * This reference isn't being deleted -> not
1346 if (!refs_read_raw_ref(ref_store
, update
->refname
,
1347 &oid
, &referent
, &type
) ||
1350 * We have to actually delete that reference
1351 * -> this transaction is needed.
1358 strbuf_release(&referent
);
1362 struct packed_transaction_backend_data
{
1363 /* True iff the transaction owns the packed-refs lock. */
1366 struct string_list updates
;
1369 static void packed_transaction_cleanup(struct packed_ref_store
*refs
,
1370 struct ref_transaction
*transaction
)
1372 struct packed_transaction_backend_data
*data
= transaction
->backend_data
;
1375 string_list_clear(&data
->updates
, 0);
1377 if (is_tempfile_active(refs
->tempfile
))
1378 delete_tempfile(&refs
->tempfile
);
1380 if (data
->own_lock
&& is_lock_file_locked(&refs
->lock
)) {
1381 packed_refs_unlock(&refs
->base
);
1386 transaction
->backend_data
= NULL
;
1389 transaction
->state
= REF_TRANSACTION_CLOSED
;
1392 static int packed_transaction_prepare(struct ref_store
*ref_store
,
1393 struct ref_transaction
*transaction
,
1396 struct packed_ref_store
*refs
= packed_downcast(
1398 REF_STORE_READ
| REF_STORE_WRITE
| REF_STORE_ODB
,
1399 "ref_transaction_prepare");
1400 struct packed_transaction_backend_data
*data
;
1402 int ret
= TRANSACTION_GENERIC_ERROR
;
1405 * Note that we *don't* skip transactions with zero updates,
1406 * because such a transaction might be executed for the side
1407 * effect of ensuring that all of the references are peeled or
1408 * ensuring that the `packed-refs` file is sorted. If the
1409 * caller wants to optimize away empty transactions, it should
1413 data
= xcalloc(1, sizeof(*data
));
1414 string_list_init(&data
->updates
, 0);
1416 transaction
->backend_data
= data
;
1419 * Stick the updates in a string list by refname so that we
1422 for (i
= 0; i
< transaction
->nr
; i
++) {
1423 struct ref_update
*update
= transaction
->updates
[i
];
1424 struct string_list_item
*item
=
1425 string_list_append(&data
->updates
, update
->refname
);
1427 /* Store a pointer to update in item->util: */
1428 item
->util
= update
;
1430 string_list_sort(&data
->updates
);
1432 if (ref_update_reject_duplicates(&data
->updates
, err
))
1435 if (!is_lock_file_locked(&refs
->lock
)) {
1436 if (packed_refs_lock(ref_store
, 0, err
))
1441 if (write_with_updates(refs
, &data
->updates
, err
))
1444 transaction
->state
= REF_TRANSACTION_PREPARED
;
1448 packed_transaction_cleanup(refs
, transaction
);
1452 static int packed_transaction_abort(struct ref_store
*ref_store
,
1453 struct ref_transaction
*transaction
,
1456 struct packed_ref_store
*refs
= packed_downcast(
1458 REF_STORE_READ
| REF_STORE_WRITE
| REF_STORE_ODB
,
1459 "ref_transaction_abort");
1461 packed_transaction_cleanup(refs
, transaction
);
1465 static int packed_transaction_finish(struct ref_store
*ref_store
,
1466 struct ref_transaction
*transaction
,
1469 struct packed_ref_store
*refs
= packed_downcast(
1471 REF_STORE_READ
| REF_STORE_WRITE
| REF_STORE_ODB
,
1472 "ref_transaction_finish");
1473 int ret
= TRANSACTION_GENERIC_ERROR
;
1474 char *packed_refs_path
;
1476 clear_snapshot(refs
);
1478 packed_refs_path
= get_locked_file_path(&refs
->lock
);
1479 if (rename_tempfile(&refs
->tempfile
, packed_refs_path
)) {
1480 strbuf_addf(err
, "error replacing %s: %s",
1481 refs
->path
, strerror(errno
));
1488 free(packed_refs_path
);
1489 packed_transaction_cleanup(refs
, transaction
);
1493 static int packed_initial_transaction_commit(struct ref_store
*ref_store
,
1494 struct ref_transaction
*transaction
,
1497 return ref_transaction_commit(transaction
, err
);
1500 static int packed_delete_refs(struct ref_store
*ref_store
, const char *msg
,
1501 struct string_list
*refnames
, unsigned int flags
)
1503 struct packed_ref_store
*refs
=
1504 packed_downcast(ref_store
, REF_STORE_WRITE
, "delete_refs");
1505 struct strbuf err
= STRBUF_INIT
;
1506 struct ref_transaction
*transaction
;
1507 struct string_list_item
*item
;
1510 (void)refs
; /* We need the check above, but don't use the variable */
1516 * Since we don't check the references' old_oids, the
1517 * individual updates can't fail, so we can pack all of the
1518 * updates into a single transaction.
1521 transaction
= ref_store_transaction_begin(ref_store
, &err
);
1525 for_each_string_list_item(item
, refnames
) {
1526 if (ref_transaction_delete(transaction
, item
->string
, NULL
,
1527 flags
, msg
, &err
)) {
1528 warning(_("could not delete reference %s: %s"),
1529 item
->string
, err
.buf
);
1534 ret
= ref_transaction_commit(transaction
, &err
);
1537 if (refnames
->nr
== 1)
1538 error(_("could not delete reference %s: %s"),
1539 refnames
->items
[0].string
, err
.buf
);
1541 error(_("could not delete references: %s"), err
.buf
);
1544 ref_transaction_free(transaction
);
1545 strbuf_release(&err
);
1549 static int packed_pack_refs(struct ref_store
*ref_store
, unsigned int flags
)
1552 * Packed refs are already packed. It might be that loose refs
1553 * are packed *into* a packed refs store, but that is done by
1554 * updating the packed references via a transaction.
1559 static int packed_create_symref(struct ref_store
*ref_store
,
1560 const char *refname
, const char *target
,
1563 die("BUG: packed reference store does not support symrefs");
1566 static int packed_rename_ref(struct ref_store
*ref_store
,
1567 const char *oldrefname
, const char *newrefname
,
1570 die("BUG: packed reference store does not support renaming references");
1573 static int packed_copy_ref(struct ref_store
*ref_store
,
1574 const char *oldrefname
, const char *newrefname
,
1577 die("BUG: packed reference store does not support copying references");
1580 static struct ref_iterator
*packed_reflog_iterator_begin(struct ref_store
*ref_store
)
1582 return empty_ref_iterator_begin();
1585 static int packed_for_each_reflog_ent(struct ref_store
*ref_store
,
1586 const char *refname
,
1587 each_reflog_ent_fn fn
, void *cb_data
)
1592 static int packed_for_each_reflog_ent_reverse(struct ref_store
*ref_store
,
1593 const char *refname
,
1594 each_reflog_ent_fn fn
,
1600 static int packed_reflog_exists(struct ref_store
*ref_store
,
1601 const char *refname
)
1606 static int packed_create_reflog(struct ref_store
*ref_store
,
1607 const char *refname
, int force_create
,
1610 die("BUG: packed reference store does not support reflogs");
1613 static int packed_delete_reflog(struct ref_store
*ref_store
,
1614 const char *refname
)
1619 static int packed_reflog_expire(struct ref_store
*ref_store
,
1620 const char *refname
, const struct object_id
*oid
,
1622 reflog_expiry_prepare_fn prepare_fn
,
1623 reflog_expiry_should_prune_fn should_prune_fn
,
1624 reflog_expiry_cleanup_fn cleanup_fn
,
1625 void *policy_cb_data
)
1630 struct ref_storage_be refs_be_packed
= {
1633 packed_ref_store_create
,
1635 packed_transaction_prepare
,
1636 packed_transaction_finish
,
1637 packed_transaction_abort
,
1638 packed_initial_transaction_commit
,
1641 packed_create_symref
,
1646 packed_ref_iterator_begin
,
1647 packed_read_raw_ref
,
1649 packed_reflog_iterator_begin
,
1650 packed_for_each_reflog_ent
,
1651 packed_for_each_reflog_ent_reverse
,
1652 packed_reflog_exists
,
1653 packed_create_reflog
,
1654 packed_delete_reflog
,
1655 packed_reflog_expire