4 #include "refs-internal.h"
5 #include "packed-backend.h"
6 #include "../iterator.h"
7 #include "../lockfile.h"
8 #include "../chdir-notify.h"
12 * Don't use mmap() at all for reading `packed-refs`.
17 * Can use mmap() for reading `packed-refs`, but the file must
18 * not remain mmapped. This is the usual option on Windows,
19 * where you cannot rename a new version of a file onto a file
20 * that is currently mmapped.
25 * It is OK to leave the `packed-refs` file mmapped while
26 * arbitrary other code is running.
32 static enum mmap_strategy mmap_strategy
= MMAP_NONE
;
33 #elif defined(MMAP_PREVENTS_DELETE)
34 static enum mmap_strategy mmap_strategy
= MMAP_TEMPORARY
;
36 static enum mmap_strategy mmap_strategy
= MMAP_OK
;
39 struct packed_ref_store
;
42 * A `snapshot` represents one snapshot of a `packed-refs` file.
44 * Normally, this will be a mmapped view of the contents of the
45 * `packed-refs` file at the time the snapshot was created. However,
46 * if the `packed-refs` file was not sorted, this might point at heap
47 * memory holding the contents of the `packed-refs` file with its
48 * records sorted by refname.
50 * `snapshot` instances are reference counted (via
51 * `acquire_snapshot()` and `release_snapshot()`). This is to prevent
52 * an instance from disappearing while an iterator is still iterating
53 * over it. Instances are garbage collected when their `referrers`
56 * The most recent `snapshot`, if available, is referenced by the
57 * `packed_ref_store`. Its freshness is checked whenever
58 * `get_snapshot()` is called; if the existing snapshot is obsolete, a
59 * new snapshot is taken.
63 * A back-pointer to the packed_ref_store with which this
64 * snapshot is associated:
66 struct packed_ref_store
*refs
;
68 /* Is the `packed-refs` file currently mmapped? */
72 * The contents of the `packed-refs` file:
74 * - buf -- a pointer to the start of the memory
75 * - start -- a pointer to the first byte of actual references
76 * (i.e., after the header line, if one is present)
77 * - eof -- a pointer just past the end of the reference
80 * If the `packed-refs` file was already sorted, `buf` points
81 * at the mmapped contents of the file. If not, it points at
82 * heap-allocated memory containing the contents, sorted. If
83 * there were no contents (e.g., because the file didn't
84 * exist), `buf`, `start`, and `eof` are all NULL.
86 char *buf
, *start
, *eof
;
89 * What is the peeled state of the `packed-refs` file that
90 * this snapshot represents? (This is usually determined from
93 enum { PEELED_NONE
, PEELED_TAGS
, PEELED_FULLY
} peeled
;
96 * Count of references to this instance, including the pointer
97 * from `packed_ref_store::snapshot`, if any. The instance
98 * will not be freed as long as the reference count is
101 unsigned int referrers
;
104 * The metadata of the `packed-refs` file from which this
105 * snapshot was created, used to tell if the file has been
106 * replaced since we read it.
108 struct stat_validity validity
;
112 * A `ref_store` representing references stored in a `packed-refs`
113 * file. It implements the `ref_store` interface, though it has some
116 * - It cannot store symbolic references.
118 * - It cannot store reflogs.
120 * - It does not support reference renaming (though it could).
122 * On the other hand, it can be locked outside of a reference
123 * transaction. In that case, it remains locked even after the
124 * transaction is done and the new `packed-refs` file is activated.
126 struct packed_ref_store
{
127 struct ref_store base
;
129 unsigned int store_flags
;
131 /* The path of the "packed-refs" file: */
135 * A snapshot of the values read from the `packed-refs` file,
136 * if it might still be current; otherwise, NULL.
138 struct snapshot
*snapshot
;
141 * Lock used for the "packed-refs" file. Note that this (and
142 * thus the enclosing `packed_ref_store`) must not be freed.
144 struct lock_file lock
;
147 * Temporary file used when rewriting new contents to the
148 * "packed-refs" file. Note that this (and thus the enclosing
149 * `packed_ref_store`) must not be freed.
151 struct tempfile
*tempfile
;
155 * Increment the reference count of `*snapshot`.
157 static void acquire_snapshot(struct snapshot
*snapshot
)
159 snapshot
->referrers
++;
163 * If the buffer in `snapshot` is active, then either munmap the
164 * memory and close the file, or free the memory. Then set the buffer
167 static void clear_snapshot_buffer(struct snapshot
*snapshot
)
169 if (snapshot
->mmapped
) {
170 if (munmap(snapshot
->buf
, snapshot
->eof
- snapshot
->buf
))
171 die_errno("error ummapping packed-refs file %s",
172 snapshot
->refs
->path
);
173 snapshot
->mmapped
= 0;
177 snapshot
->buf
= snapshot
->start
= snapshot
->eof
= NULL
;
181 * Decrease the reference count of `*snapshot`. If it goes to zero,
182 * free `*snapshot` and return true; otherwise return false.
184 static int release_snapshot(struct snapshot
*snapshot
)
186 if (!--snapshot
->referrers
) {
187 stat_validity_clear(&snapshot
->validity
);
188 clear_snapshot_buffer(snapshot
);
196 struct ref_store
*packed_ref_store_create(const char *path
,
197 unsigned int store_flags
)
199 struct packed_ref_store
*refs
= xcalloc(1, sizeof(*refs
));
200 struct ref_store
*ref_store
= (struct ref_store
*)refs
;
202 base_ref_store_init(ref_store
, &refs_be_packed
);
203 refs
->store_flags
= store_flags
;
205 refs
->path
= xstrdup(path
);
206 chdir_notify_reparent("packed-refs", &refs
->path
);
212 * Downcast `ref_store` to `packed_ref_store`. Die if `ref_store` is
213 * not a `packed_ref_store`. Also die if `packed_ref_store` doesn't
214 * support at least the flags specified in `required_flags`. `caller`
215 * is used in any necessary error messages.
217 static struct packed_ref_store
*packed_downcast(struct ref_store
*ref_store
,
218 unsigned int required_flags
,
221 struct packed_ref_store
*refs
;
223 if (ref_store
->be
!= &refs_be_packed
)
224 BUG("ref_store is type \"%s\" not \"packed\" in %s",
225 ref_store
->be
->name
, caller
);
227 refs
= (struct packed_ref_store
*)ref_store
;
229 if ((refs
->store_flags
& required_flags
) != required_flags
)
230 BUG("unallowed operation (%s), requires %x, has %x\n",
231 caller
, required_flags
, refs
->store_flags
);
236 static void clear_snapshot(struct packed_ref_store
*refs
)
238 if (refs
->snapshot
) {
239 struct snapshot
*snapshot
= refs
->snapshot
;
241 refs
->snapshot
= NULL
;
242 release_snapshot(snapshot
);
246 static NORETURN
void die_unterminated_line(const char *path
,
247 const char *p
, size_t len
)
250 die("unterminated line in %s: %.*s", path
, (int)len
, p
);
252 die("unterminated line in %s: %.75s...", path
, p
);
255 static NORETURN
void die_invalid_line(const char *path
,
256 const char *p
, size_t len
)
258 const char *eol
= memchr(p
, '\n', len
);
261 die_unterminated_line(path
, p
, len
);
262 else if (eol
- p
< 80)
263 die("unexpected line in %s: %.*s", path
, (int)(eol
- p
), p
);
265 die("unexpected line in %s: %.75s...", path
, p
);
269 struct snapshot_record
{
274 static int cmp_packed_ref_records(const void *v1
, const void *v2
)
276 const struct snapshot_record
*e1
= v1
, *e2
= v2
;
277 const char *r1
= e1
->start
+ the_hash_algo
->hexsz
+ 1;
278 const char *r2
= e2
->start
+ the_hash_algo
->hexsz
+ 1;
282 return *r2
== '\n' ? 0 : -1;
287 return (unsigned char)*r1
< (unsigned char)*r2
? -1 : +1;
295 * Compare a snapshot record at `rec` to the specified NUL-terminated
298 static int cmp_record_to_refname(const char *rec
, const char *refname
)
300 const char *r1
= rec
+ the_hash_algo
->hexsz
+ 1;
301 const char *r2
= refname
;
309 return (unsigned char)*r1
< (unsigned char)*r2
? -1 : +1;
316 * `snapshot->buf` is not known to be sorted. Check whether it is, and
317 * if not, sort it into new memory and munmap/free the old storage.
319 static void sort_snapshot(struct snapshot
*snapshot
)
321 struct snapshot_record
*records
= NULL
;
322 size_t alloc
= 0, nr
= 0;
324 const char *pos
, *eof
, *eol
;
326 char *new_buffer
, *dst
;
328 pos
= snapshot
->start
;
337 * Initialize records based on a crude estimate of the number
338 * of references in the file (we'll grow it below if needed):
340 ALLOC_GROW(records
, len
/ 80 + 20, alloc
);
343 eol
= memchr(pos
, '\n', eof
- pos
);
345 /* The safety check should prevent this. */
346 BUG("unterminated line found in packed-refs");
347 if (eol
- pos
< the_hash_algo
->hexsz
+ 2)
348 die_invalid_line(snapshot
->refs
->path
,
351 if (eol
< eof
&& *eol
== '^') {
353 * Keep any peeled line together with its
356 const char *peeled_start
= eol
;
358 eol
= memchr(peeled_start
, '\n', eof
- peeled_start
);
360 /* The safety check should prevent this. */
361 BUG("unterminated peeled line found in packed-refs");
365 ALLOC_GROW(records
, nr
+ 1, alloc
);
366 records
[nr
].start
= pos
;
367 records
[nr
].len
= eol
- pos
;
372 cmp_packed_ref_records(&records
[nr
- 2],
373 &records
[nr
- 1]) >= 0)
382 /* We need to sort the memory. First we sort the records array: */
383 QSORT(records
, nr
, cmp_packed_ref_records
);
386 * Allocate a new chunk of memory, and copy the old memory to
387 * the new in the order indicated by `records` (not bothering
388 * with the header line):
390 new_buffer
= xmalloc(len
);
391 for (dst
= new_buffer
, i
= 0; i
< nr
; i
++) {
392 memcpy(dst
, records
[i
].start
, records
[i
].len
);
393 dst
+= records
[i
].len
;
397 * Now munmap the old buffer and use the sorted buffer in its
400 clear_snapshot_buffer(snapshot
);
401 snapshot
->buf
= snapshot
->start
= new_buffer
;
402 snapshot
->eof
= new_buffer
+ len
;
409 * Return a pointer to the start of the record that contains the
410 * character `*p` (which must be within the buffer). If no other
411 * record start is found, return `buf`.
413 static const char *find_start_of_record(const char *buf
, const char *p
)
415 while (p
> buf
&& (p
[-1] != '\n' || p
[0] == '^'))
421 * Return a pointer to the start of the record following the record
422 * that contains `*p`. If none is found before `end`, return `end`.
424 static const char *find_end_of_record(const char *p
, const char *end
)
426 while (++p
< end
&& (p
[-1] != '\n' || p
[0] == '^'))
432 * We want to be able to compare mmapped reference records quickly,
433 * without totally parsing them. We can do so because the records are
434 * LF-terminated, and the refname should start exactly (GIT_SHA1_HEXSZ
435 * + 1) bytes past the beginning of the record.
437 * But what if the `packed-refs` file contains garbage? We're willing
438 * to tolerate not detecting the problem, as long as we don't produce
439 * totally garbled output (we can't afford to check the integrity of
440 * the whole file during every Git invocation). But we do want to be
441 * sure that we never read past the end of the buffer in memory and
442 * perform an illegal memory access.
444 * Guarantee that minimum level of safety by verifying that the last
445 * record in the file is LF-terminated, and that it has at least
446 * (GIT_SHA1_HEXSZ + 1) characters before the LF. Die if either of
447 * these checks fails.
449 static void verify_buffer_safe(struct snapshot
*snapshot
)
451 const char *start
= snapshot
->start
;
452 const char *eof
= snapshot
->eof
;
453 const char *last_line
;
458 last_line
= find_start_of_record(start
, eof
- 1);
459 if (*(eof
- 1) != '\n' || eof
- last_line
< the_hash_algo
->hexsz
+ 2)
460 die_invalid_line(snapshot
->refs
->path
,
461 last_line
, eof
- last_line
);
464 #define SMALL_FILE_SIZE (32*1024)
467 * Depending on `mmap_strategy`, either mmap or read the contents of
468 * the `packed-refs` file into the snapshot. Return 1 if the file
469 * existed and was read, or 0 if the file was absent or empty. Die on
472 static int load_contents(struct snapshot
*snapshot
)
479 fd
= open(snapshot
->refs
->path
, O_RDONLY
);
481 if (errno
== ENOENT
) {
483 * This is OK; it just means that no
484 * "packed-refs" file has been written yet,
485 * which is equivalent to it being empty,
486 * which is its state when initialized with
491 die_errno("couldn't read %s", snapshot
->refs
->path
);
495 stat_validity_update(&snapshot
->validity
, fd
);
497 if (fstat(fd
, &st
) < 0)
498 die_errno("couldn't stat %s", snapshot
->refs
->path
);
499 size
= xsize_t(st
.st_size
);
504 } else if (mmap_strategy
== MMAP_NONE
|| size
<= SMALL_FILE_SIZE
) {
505 snapshot
->buf
= xmalloc(size
);
506 bytes_read
= read_in_full(fd
, snapshot
->buf
, size
);
507 if (bytes_read
< 0 || bytes_read
!= size
)
508 die_errno("couldn't read %s", snapshot
->refs
->path
);
509 snapshot
->mmapped
= 0;
511 snapshot
->buf
= xmmap(NULL
, size
, PROT_READ
, MAP_PRIVATE
, fd
, 0);
512 snapshot
->mmapped
= 1;
516 snapshot
->start
= snapshot
->buf
;
517 snapshot
->eof
= snapshot
->buf
+ size
;
523 * Find the place in `snapshot->buf` where the start of the record for
524 * `refname` starts. If `mustexist` is true and the reference doesn't
525 * exist, then return NULL. If `mustexist` is false and the reference
526 * doesn't exist, then return the point where that reference would be
527 * inserted, or `snapshot->eof` (which might be NULL) if it would be
528 * inserted at the end of the file. In the latter mode, `refname`
529 * doesn't have to be a proper reference name; for example, one could
530 * search for "refs/replace/" to find the start of any replace
533 * The record is sought using a binary search, so `snapshot->buf` must
536 static const char *find_reference_location(struct snapshot
*snapshot
,
537 const char *refname
, int mustexist
)
540 * This is not *quite* a garden-variety binary search, because
541 * the data we're searching is made up of records, and we
542 * always need to find the beginning of a record to do a
543 * comparison. A "record" here is one line for the reference
544 * itself and zero or one peel lines that start with '^'. Our
545 * loop invariant is described in the next two comments.
549 * A pointer to the character at the start of a record whose
550 * preceding records all have reference names that come
551 * *before* `refname`.
553 const char *lo
= snapshot
->start
;
556 * A pointer to a the first character of a record whose
557 * reference name comes *after* `refname`.
559 const char *hi
= snapshot
->eof
;
562 const char *mid
, *rec
;
565 mid
= lo
+ (hi
- lo
) / 2;
566 rec
= find_start_of_record(lo
, mid
);
567 cmp
= cmp_record_to_refname(rec
, refname
);
569 lo
= find_end_of_record(mid
, hi
);
570 } else if (cmp
> 0) {
584 * Create a newly-allocated `snapshot` of the `packed-refs` file in
585 * its current state and return it. The return value will already have
586 * its reference count incremented.
588 * A comment line of the form "# pack-refs with: " may contain zero or
589 * more traits. We interpret the traits as follows:
591 * Neither `peeled` nor `fully-peeled`:
593 * Probably no references are peeled. But if the file contains a
594 * peeled value for a reference, we will use it.
598 * References under "refs/tags/", if they *can* be peeled, *are*
599 * peeled in this file. References outside of "refs/tags/" are
600 * probably not peeled even if they could have been, but if we find
601 * a peeled value for such a reference we will use it.
605 * All references in the file that can be peeled are peeled.
606 * Inversely (and this is more important), any references in the
607 * file for which no peeled value is recorded is not peelable. This
608 * trait should typically be written alongside "peeled" for
609 * compatibility with older clients, but we do not require it
610 * (i.e., "peeled" is a no-op if "fully-peeled" is set).
614 * The references in this file are known to be sorted by refname.
616 static struct snapshot
*create_snapshot(struct packed_ref_store
*refs
)
618 struct snapshot
*snapshot
= xcalloc(1, sizeof(*snapshot
));
621 snapshot
->refs
= refs
;
622 acquire_snapshot(snapshot
);
623 snapshot
->peeled
= PEELED_NONE
;
625 if (!load_contents(snapshot
))
628 /* If the file has a header line, process it: */
629 if (snapshot
->buf
< snapshot
->eof
&& *snapshot
->buf
== '#') {
631 struct string_list traits
= STRING_LIST_INIT_NODUP
;
633 eol
= memchr(snapshot
->buf
, '\n',
634 snapshot
->eof
- snapshot
->buf
);
636 die_unterminated_line(refs
->path
,
638 snapshot
->eof
- snapshot
->buf
);
640 tmp
= xmemdupz(snapshot
->buf
, eol
- snapshot
->buf
);
642 if (!skip_prefix(tmp
, "# pack-refs with:", (const char **)&p
))
643 die_invalid_line(refs
->path
,
645 snapshot
->eof
- snapshot
->buf
);
647 string_list_split_in_place(&traits
, p
, ' ', -1);
649 if (unsorted_string_list_has_string(&traits
, "fully-peeled"))
650 snapshot
->peeled
= PEELED_FULLY
;
651 else if (unsorted_string_list_has_string(&traits
, "peeled"))
652 snapshot
->peeled
= PEELED_TAGS
;
654 sorted
= unsorted_string_list_has_string(&traits
, "sorted");
656 /* perhaps other traits later as well */
658 /* The "+ 1" is for the LF character. */
659 snapshot
->start
= eol
+ 1;
661 string_list_clear(&traits
, 0);
665 verify_buffer_safe(snapshot
);
668 sort_snapshot(snapshot
);
671 * Reordering the records might have moved a short one
672 * to the end of the buffer, so verify the buffer's
675 verify_buffer_safe(snapshot
);
678 if (mmap_strategy
!= MMAP_OK
&& snapshot
->mmapped
) {
680 * We don't want to leave the file mmapped, so we are
681 * forced to make a copy now:
683 size_t size
= snapshot
->eof
- snapshot
->start
;
684 char *buf_copy
= xmalloc(size
);
686 memcpy(buf_copy
, snapshot
->start
, size
);
687 clear_snapshot_buffer(snapshot
);
688 snapshot
->buf
= snapshot
->start
= buf_copy
;
689 snapshot
->eof
= buf_copy
+ size
;
696 * Check that `refs->snapshot` (if present) still reflects the
697 * contents of the `packed-refs` file. If not, clear the snapshot.
699 static void validate_snapshot(struct packed_ref_store
*refs
)
701 if (refs
->snapshot
&&
702 !stat_validity_check(&refs
->snapshot
->validity
, refs
->path
))
703 clear_snapshot(refs
);
707 * Get the `snapshot` for the specified packed_ref_store, creating and
708 * populating it if it hasn't been read before or if the file has been
709 * changed (according to its `validity` field) since it was last read.
710 * On the other hand, if we hold the lock, then assume that the file
711 * hasn't been changed out from under us, so skip the extra `stat()`
712 * call in `stat_validity_check()`. This function does *not* increase
713 * the snapshot's reference count on behalf of the caller.
715 static struct snapshot
*get_snapshot(struct packed_ref_store
*refs
)
717 if (!is_lock_file_locked(&refs
->lock
))
718 validate_snapshot(refs
);
721 refs
->snapshot
= create_snapshot(refs
);
723 return refs
->snapshot
;
726 static int packed_read_raw_ref(struct ref_store
*ref_store
,
727 const char *refname
, struct object_id
*oid
,
728 struct strbuf
*referent
, unsigned int *type
)
730 struct packed_ref_store
*refs
=
731 packed_downcast(ref_store
, REF_STORE_READ
, "read_raw_ref");
732 struct snapshot
*snapshot
= get_snapshot(refs
);
737 rec
= find_reference_location(snapshot
, refname
, 1);
740 /* refname is not a packed reference. */
745 if (get_oid_hex(rec
, oid
))
746 die_invalid_line(refs
->path
, rec
, snapshot
->eof
- rec
);
748 *type
= REF_ISPACKED
;
753 * This value is set in `base.flags` if the peeled value of the
754 * current reference is known. In that case, `peeled` contains the
755 * correct peeled value for the reference, which might be `null_oid`
756 * if the reference is not a tag or if it is broken.
758 #define REF_KNOWS_PEELED 0x40
761 * An iterator over a snapshot of a `packed-refs` file.
763 struct packed_ref_iterator
{
764 struct ref_iterator base
;
766 struct snapshot
*snapshot
;
768 /* The current position in the snapshot's buffer: */
771 /* The end of the part of the buffer that will be iterated over: */
774 /* Scratch space for current values: */
775 struct object_id oid
, peeled
;
776 struct strbuf refname_buf
;
782 * Move the iterator to the next record in the snapshot, without
783 * respect for whether the record is actually required by the current
784 * iteration. Adjust the fields in `iter` and return `ITER_OK` or
785 * `ITER_DONE`. This function does not free the iterator in the case
788 static int next_record(struct packed_ref_iterator
*iter
)
790 const char *p
= iter
->pos
, *eol
;
792 strbuf_reset(&iter
->refname_buf
);
794 if (iter
->pos
== iter
->eof
)
797 iter
->base
.flags
= REF_ISPACKED
;
799 if (iter
->eof
- p
< the_hash_algo
->hexsz
+ 2 ||
800 parse_oid_hex(p
, &iter
->oid
, &p
) ||
802 die_invalid_line(iter
->snapshot
->refs
->path
,
803 iter
->pos
, iter
->eof
- iter
->pos
);
805 eol
= memchr(p
, '\n', iter
->eof
- p
);
807 die_unterminated_line(iter
->snapshot
->refs
->path
,
808 iter
->pos
, iter
->eof
- iter
->pos
);
810 strbuf_add(&iter
->refname_buf
, p
, eol
- p
);
811 iter
->base
.refname
= iter
->refname_buf
.buf
;
813 if (check_refname_format(iter
->base
.refname
, REFNAME_ALLOW_ONELEVEL
)) {
814 if (!refname_is_safe(iter
->base
.refname
))
815 die("packed refname is dangerous: %s",
818 iter
->base
.flags
|= REF_BAD_NAME
| REF_ISBROKEN
;
820 if (iter
->snapshot
->peeled
== PEELED_FULLY
||
821 (iter
->snapshot
->peeled
== PEELED_TAGS
&&
822 starts_with(iter
->base
.refname
, "refs/tags/")))
823 iter
->base
.flags
|= REF_KNOWS_PEELED
;
827 if (iter
->pos
< iter
->eof
&& *iter
->pos
== '^') {
829 if (iter
->eof
- p
< the_hash_algo
->hexsz
+ 1 ||
830 parse_oid_hex(p
, &iter
->peeled
, &p
) ||
832 die_invalid_line(iter
->snapshot
->refs
->path
,
833 iter
->pos
, iter
->eof
- iter
->pos
);
837 * Regardless of what the file header said, we
838 * definitely know the value of *this* reference. But
839 * we suppress it if the reference is broken:
841 if ((iter
->base
.flags
& REF_ISBROKEN
)) {
842 oidclr(&iter
->peeled
);
843 iter
->base
.flags
&= ~REF_KNOWS_PEELED
;
845 iter
->base
.flags
|= REF_KNOWS_PEELED
;
848 oidclr(&iter
->peeled
);
854 static int packed_ref_iterator_advance(struct ref_iterator
*ref_iterator
)
856 struct packed_ref_iterator
*iter
=
857 (struct packed_ref_iterator
*)ref_iterator
;
860 while ((ok
= next_record(iter
)) == ITER_OK
) {
861 if (iter
->flags
& DO_FOR_EACH_PER_WORKTREE_ONLY
&&
862 ref_type(iter
->base
.refname
) != REF_TYPE_PER_WORKTREE
)
865 if (!(iter
->flags
& DO_FOR_EACH_INCLUDE_BROKEN
) &&
866 !ref_resolves_to_object(iter
->base
.refname
, &iter
->oid
,
873 if (ref_iterator_abort(ref_iterator
) != ITER_DONE
)
879 static int packed_ref_iterator_peel(struct ref_iterator
*ref_iterator
,
880 struct object_id
*peeled
)
882 struct packed_ref_iterator
*iter
=
883 (struct packed_ref_iterator
*)ref_iterator
;
885 if ((iter
->base
.flags
& REF_KNOWS_PEELED
)) {
886 oidcpy(peeled
, &iter
->peeled
);
887 return is_null_oid(&iter
->peeled
) ? -1 : 0;
888 } else if ((iter
->base
.flags
& (REF_ISBROKEN
| REF_ISSYMREF
))) {
891 return !!peel_object(&iter
->oid
, peeled
);
895 static int packed_ref_iterator_abort(struct ref_iterator
*ref_iterator
)
897 struct packed_ref_iterator
*iter
=
898 (struct packed_ref_iterator
*)ref_iterator
;
901 strbuf_release(&iter
->refname_buf
);
902 release_snapshot(iter
->snapshot
);
903 base_ref_iterator_free(ref_iterator
);
907 static struct ref_iterator_vtable packed_ref_iterator_vtable
= {
908 packed_ref_iterator_advance
,
909 packed_ref_iterator_peel
,
910 packed_ref_iterator_abort
913 static struct ref_iterator
*packed_ref_iterator_begin(
914 struct ref_store
*ref_store
,
915 const char *prefix
, unsigned int flags
)
917 struct packed_ref_store
*refs
;
918 struct snapshot
*snapshot
;
920 struct packed_ref_iterator
*iter
;
921 struct ref_iterator
*ref_iterator
;
922 unsigned int required_flags
= REF_STORE_READ
;
924 if (!(flags
& DO_FOR_EACH_INCLUDE_BROKEN
))
925 required_flags
|= REF_STORE_ODB
;
926 refs
= packed_downcast(ref_store
, required_flags
, "ref_iterator_begin");
929 * Note that `get_snapshot()` internally checks whether the
930 * snapshot is up to date with what is on disk, and re-reads
933 snapshot
= get_snapshot(refs
);
935 if (prefix
&& *prefix
)
936 start
= find_reference_location(snapshot
, prefix
, 0);
938 start
= snapshot
->start
;
940 if (start
== snapshot
->eof
)
941 return empty_ref_iterator_begin();
943 iter
= xcalloc(1, sizeof(*iter
));
944 ref_iterator
= &iter
->base
;
945 base_ref_iterator_init(ref_iterator
, &packed_ref_iterator_vtable
, 1);
947 iter
->snapshot
= snapshot
;
948 acquire_snapshot(snapshot
);
951 iter
->eof
= snapshot
->eof
;
952 strbuf_init(&iter
->refname_buf
, 0);
954 iter
->base
.oid
= &iter
->oid
;
958 if (prefix
&& *prefix
)
959 /* Stop iteration after we've gone *past* prefix: */
960 ref_iterator
= prefix_ref_iterator_begin(ref_iterator
, prefix
, 0);
966 * Write an entry to the packed-refs file for the specified refname.
967 * If peeled is non-NULL, write it as the entry's peeled value. On
968 * error, return a nonzero value and leave errno set at the value left
969 * by the failing call to `fprintf()`.
971 static int write_packed_entry(FILE *fh
, const char *refname
,
972 const struct object_id
*oid
,
973 const struct object_id
*peeled
)
975 if (fprintf(fh
, "%s %s\n", oid_to_hex(oid
), refname
) < 0 ||
976 (peeled
&& fprintf(fh
, "^%s\n", oid_to_hex(peeled
)) < 0))
982 int packed_refs_lock(struct ref_store
*ref_store
, int flags
, struct strbuf
*err
)
984 struct packed_ref_store
*refs
=
985 packed_downcast(ref_store
, REF_STORE_WRITE
| REF_STORE_MAIN
,
987 static int timeout_configured
= 0;
988 static int timeout_value
= 1000;
990 if (!timeout_configured
) {
991 git_config_get_int("core.packedrefstimeout", &timeout_value
);
992 timeout_configured
= 1;
996 * Note that we close the lockfile immediately because we
997 * don't write new content to it, but rather to a separate
1000 if (hold_lock_file_for_update_timeout(
1003 flags
, timeout_value
) < 0) {
1004 unable_to_lock_message(refs
->path
, errno
, err
);
1008 if (close_lock_file_gently(&refs
->lock
)) {
1009 strbuf_addf(err
, "unable to close %s: %s", refs
->path
, strerror(errno
));
1010 rollback_lock_file(&refs
->lock
);
1015 * There is a stat-validity problem might cause `update-ref -d`
1016 * lost the newly commit of a ref, because a new `packed-refs`
1017 * file might has the same on-disk file attributes such as
1018 * timestamp, file size and inode value, but has a changed
1021 * This could happen with a very small chance when
1022 * `update-ref -d` is called and at the same time another
1023 * `pack-refs --all` process is running.
1025 * Now that we hold the `packed-refs` lock, it is important
1026 * to make sure we could read the latest version of
1027 * `packed-refs` file no matter we have just mmap it or not.
1028 * So what need to do is clear the snapshot if we hold it
1031 clear_snapshot(refs
);
1034 * Now make sure that the packed-refs file as it exists in the
1035 * locked state is loaded into the snapshot:
1041 void packed_refs_unlock(struct ref_store
*ref_store
)
1043 struct packed_ref_store
*refs
= packed_downcast(
1045 REF_STORE_READ
| REF_STORE_WRITE
,
1046 "packed_refs_unlock");
1048 if (!is_lock_file_locked(&refs
->lock
))
1049 BUG("packed_refs_unlock() called when not locked");
1050 rollback_lock_file(&refs
->lock
);
1053 int packed_refs_is_locked(struct ref_store
*ref_store
)
1055 struct packed_ref_store
*refs
= packed_downcast(
1057 REF_STORE_READ
| REF_STORE_WRITE
,
1058 "packed_refs_is_locked");
1060 return is_lock_file_locked(&refs
->lock
);
1064 * The packed-refs header line that we write out. Perhaps other traits
1065 * will be added later.
1067 * Note that earlier versions of Git used to parse these traits by
1068 * looking for " trait " in the line. For this reason, the space after
1069 * the colon and the trailing space are required.
1071 static const char PACKED_REFS_HEADER
[] =
1072 "# pack-refs with: peeled fully-peeled sorted \n";
1074 static int packed_init_db(struct ref_store
*ref_store
, struct strbuf
*err
)
1076 /* Nothing to do. */
1081 * Write the packed refs from the current snapshot to the packed-refs
1082 * tempfile, incorporating any changes from `updates`. `updates` must
1083 * be a sorted string list whose keys are the refnames and whose util
1084 * values are `struct ref_update *`. On error, rollback the tempfile,
1085 * write an error message to `err`, and return a nonzero value.
1087 * The packfile must be locked before calling this function and will
1088 * remain locked when it is done.
1090 static int write_with_updates(struct packed_ref_store
*refs
,
1091 struct string_list
*updates
,
1094 struct ref_iterator
*iter
= NULL
;
1098 struct strbuf sb
= STRBUF_INIT
;
1099 char *packed_refs_path
;
1101 if (!is_lock_file_locked(&refs
->lock
))
1102 BUG("write_with_updates() called while unlocked");
1105 * If packed-refs is a symlink, we want to overwrite the
1106 * symlinked-to file, not the symlink itself. Also, put the
1107 * staging file next to it:
1109 packed_refs_path
= get_locked_file_path(&refs
->lock
);
1110 strbuf_addf(&sb
, "%s.new", packed_refs_path
);
1111 free(packed_refs_path
);
1112 refs
->tempfile
= create_tempfile(sb
.buf
);
1113 if (!refs
->tempfile
) {
1114 strbuf_addf(err
, "unable to create file %s: %s",
1115 sb
.buf
, strerror(errno
));
1116 strbuf_release(&sb
);
1119 strbuf_release(&sb
);
1121 out
= fdopen_tempfile(refs
->tempfile
, "w");
1123 strbuf_addf(err
, "unable to fdopen packed-refs tempfile: %s",
1128 if (fprintf(out
, "%s", PACKED_REFS_HEADER
) < 0)
1132 * We iterate in parallel through the current list of refs and
1133 * the list of updates, processing an entry from at least one
1134 * of the lists each time through the loop. When the current
1135 * list of refs is exhausted, set iter to NULL. When the list
1136 * of updates is exhausted, leave i set to updates->nr.
1138 iter
= packed_ref_iterator_begin(&refs
->base
, "",
1139 DO_FOR_EACH_INCLUDE_BROKEN
);
1140 if ((ok
= ref_iterator_advance(iter
)) != ITER_OK
)
1145 while (iter
|| i
< updates
->nr
) {
1146 struct ref_update
*update
= NULL
;
1149 if (i
>= updates
->nr
) {
1152 update
= updates
->items
[i
].util
;
1157 cmp
= strcmp(iter
->refname
, update
->refname
);
1162 * There is both an old value and an update
1163 * for this reference. Check the old value if
1166 if ((update
->flags
& REF_HAVE_OLD
)) {
1167 if (is_null_oid(&update
->old_oid
)) {
1168 strbuf_addf(err
, "cannot update ref '%s': "
1169 "reference already exists",
1172 } else if (!oideq(&update
->old_oid
, iter
->oid
)) {
1173 strbuf_addf(err
, "cannot update ref '%s': "
1174 "is at %s but expected %s",
1176 oid_to_hex(iter
->oid
),
1177 oid_to_hex(&update
->old_oid
));
1182 /* Now figure out what to use for the new value: */
1183 if ((update
->flags
& REF_HAVE_NEW
)) {
1185 * The update takes precedence. Skip
1186 * the iterator over the unneeded
1189 if ((ok
= ref_iterator_advance(iter
)) != ITER_OK
)
1194 * The update doesn't actually want to
1195 * change anything. We're done with it.
1200 } else if (cmp
> 0) {
1202 * There is no old value but there is an
1203 * update for this reference. Make sure that
1204 * the update didn't expect an existing value:
1206 if ((update
->flags
& REF_HAVE_OLD
) &&
1207 !is_null_oid(&update
->old_oid
)) {
1208 strbuf_addf(err
, "cannot update ref '%s': "
1209 "reference is missing but expected %s",
1211 oid_to_hex(&update
->old_oid
));
1217 /* Pass the old reference through. */
1219 struct object_id peeled
;
1220 int peel_error
= ref_iterator_peel(iter
, &peeled
);
1222 if (write_packed_entry(out
, iter
->refname
,
1224 peel_error
? NULL
: &peeled
))
1227 if ((ok
= ref_iterator_advance(iter
)) != ITER_OK
)
1229 } else if (is_null_oid(&update
->new_oid
)) {
1231 * The update wants to delete the reference,
1232 * and the reference either didn't exist or we
1233 * have already skipped it. So we're done with
1234 * the update (and don't have to write
1239 struct object_id peeled
;
1240 int peel_error
= peel_object(&update
->new_oid
,
1243 if (write_packed_entry(out
, update
->refname
,
1245 peel_error
? NULL
: &peeled
))
1252 if (ok
!= ITER_DONE
) {
1253 strbuf_addstr(err
, "unable to write packed-refs file: "
1254 "error iterating over old contents");
1258 if (close_tempfile_gently(refs
->tempfile
)) {
1259 strbuf_addf(err
, "error closing file %s: %s",
1260 get_tempfile_path(refs
->tempfile
),
1262 strbuf_release(&sb
);
1263 delete_tempfile(&refs
->tempfile
);
1270 strbuf_addf(err
, "error writing to %s: %s",
1271 get_tempfile_path(refs
->tempfile
), strerror(errno
));
1275 ref_iterator_abort(iter
);
1277 delete_tempfile(&refs
->tempfile
);
1281 int is_packed_transaction_needed(struct ref_store
*ref_store
,
1282 struct ref_transaction
*transaction
)
1284 struct packed_ref_store
*refs
= packed_downcast(
1287 "is_packed_transaction_needed");
1288 struct strbuf referent
= STRBUF_INIT
;
1292 if (!is_lock_file_locked(&refs
->lock
))
1293 BUG("is_packed_transaction_needed() called while unlocked");
1296 * We're only going to bother returning false for the common,
1297 * trivial case that references are only being deleted, their
1298 * old values are not being checked, and the old `packed-refs`
1299 * file doesn't contain any of those reference(s). This gives
1300 * false positives for some other cases that could
1301 * theoretically be optimized away:
1303 * 1. It could be that the old value is being verified without
1304 * setting a new value. In this case, we could verify the
1305 * old value here and skip the update if it agrees. If it
1306 * disagrees, we could either let the update go through
1307 * (the actual commit would re-detect and report the
1308 * problem), or come up with a way of reporting such an
1309 * error to *our* caller.
1311 * 2. It could be that a new value is being set, but that it
1312 * is identical to the current packed value of the
1315 * Neither of these cases will come up in the current code,
1316 * because the only caller of this function passes to it a
1317 * transaction that only includes `delete` updates with no
1318 * `old_id`. Even if that ever changes, false positives only
1319 * cause an optimization to be missed; they do not affect
1324 * Start with the cheap checks that don't require old
1325 * reference values to be read:
1327 for (i
= 0; i
< transaction
->nr
; i
++) {
1328 struct ref_update
*update
= transaction
->updates
[i
];
1330 if (update
->flags
& REF_HAVE_OLD
)
1331 /* Have to check the old value -> needed. */
1334 if ((update
->flags
& REF_HAVE_NEW
) && !is_null_oid(&update
->new_oid
))
1335 /* Have to set a new value -> needed. */
1340 * The transaction isn't checking any old values nor is it
1341 * setting any nonzero new values, so it still might be able
1342 * to be skipped. Now do the more expensive check: the update
1343 * is needed if any of the updates is a delete, and the old
1344 * `packed-refs` file contains a value for that reference.
1347 for (i
= 0; i
< transaction
->nr
; i
++) {
1348 struct ref_update
*update
= transaction
->updates
[i
];
1350 struct object_id oid
;
1352 if (!(update
->flags
& REF_HAVE_NEW
))
1354 * This reference isn't being deleted -> not
1359 if (!refs_read_raw_ref(ref_store
, update
->refname
,
1360 &oid
, &referent
, &type
) ||
1363 * We have to actually delete that reference
1364 * -> this transaction is needed.
1371 strbuf_release(&referent
);
1375 struct packed_transaction_backend_data
{
1376 /* True iff the transaction owns the packed-refs lock. */
1379 struct string_list updates
;
1382 static void packed_transaction_cleanup(struct packed_ref_store
*refs
,
1383 struct ref_transaction
*transaction
)
1385 struct packed_transaction_backend_data
*data
= transaction
->backend_data
;
1388 string_list_clear(&data
->updates
, 0);
1390 if (is_tempfile_active(refs
->tempfile
))
1391 delete_tempfile(&refs
->tempfile
);
1393 if (data
->own_lock
&& is_lock_file_locked(&refs
->lock
)) {
1394 packed_refs_unlock(&refs
->base
);
1399 transaction
->backend_data
= NULL
;
1402 transaction
->state
= REF_TRANSACTION_CLOSED
;
1405 static int packed_transaction_prepare(struct ref_store
*ref_store
,
1406 struct ref_transaction
*transaction
,
1409 struct packed_ref_store
*refs
= packed_downcast(
1411 REF_STORE_READ
| REF_STORE_WRITE
| REF_STORE_ODB
,
1412 "ref_transaction_prepare");
1413 struct packed_transaction_backend_data
*data
;
1415 int ret
= TRANSACTION_GENERIC_ERROR
;
1418 * Note that we *don't* skip transactions with zero updates,
1419 * because such a transaction might be executed for the side
1420 * effect of ensuring that all of the references are peeled or
1421 * ensuring that the `packed-refs` file is sorted. If the
1422 * caller wants to optimize away empty transactions, it should
1426 data
= xcalloc(1, sizeof(*data
));
1427 string_list_init(&data
->updates
, 0);
1429 transaction
->backend_data
= data
;
1432 * Stick the updates in a string list by refname so that we
1435 for (i
= 0; i
< transaction
->nr
; i
++) {
1436 struct ref_update
*update
= transaction
->updates
[i
];
1437 struct string_list_item
*item
=
1438 string_list_append(&data
->updates
, update
->refname
);
1440 /* Store a pointer to update in item->util: */
1441 item
->util
= update
;
1443 string_list_sort(&data
->updates
);
1445 if (ref_update_reject_duplicates(&data
->updates
, err
))
1448 if (!is_lock_file_locked(&refs
->lock
)) {
1449 if (packed_refs_lock(ref_store
, 0, err
))
1454 if (write_with_updates(refs
, &data
->updates
, err
))
1457 transaction
->state
= REF_TRANSACTION_PREPARED
;
1461 packed_transaction_cleanup(refs
, transaction
);
1465 static int packed_transaction_abort(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_abort");
1474 packed_transaction_cleanup(refs
, transaction
);
1478 static int packed_transaction_finish(struct ref_store
*ref_store
,
1479 struct ref_transaction
*transaction
,
1482 struct packed_ref_store
*refs
= packed_downcast(
1484 REF_STORE_READ
| REF_STORE_WRITE
| REF_STORE_ODB
,
1485 "ref_transaction_finish");
1486 int ret
= TRANSACTION_GENERIC_ERROR
;
1487 char *packed_refs_path
;
1489 clear_snapshot(refs
);
1491 packed_refs_path
= get_locked_file_path(&refs
->lock
);
1492 if (rename_tempfile(&refs
->tempfile
, packed_refs_path
)) {
1493 strbuf_addf(err
, "error replacing %s: %s",
1494 refs
->path
, strerror(errno
));
1501 free(packed_refs_path
);
1502 packed_transaction_cleanup(refs
, transaction
);
1506 static int packed_initial_transaction_commit(struct ref_store
*ref_store
,
1507 struct ref_transaction
*transaction
,
1510 return ref_transaction_commit(transaction
, err
);
1513 static int packed_delete_refs(struct ref_store
*ref_store
, const char *msg
,
1514 struct string_list
*refnames
, unsigned int flags
)
1516 struct packed_ref_store
*refs
=
1517 packed_downcast(ref_store
, REF_STORE_WRITE
, "delete_refs");
1518 struct strbuf err
= STRBUF_INIT
;
1519 struct ref_transaction
*transaction
;
1520 struct string_list_item
*item
;
1523 (void)refs
; /* We need the check above, but don't use the variable */
1529 * Since we don't check the references' old_oids, the
1530 * individual updates can't fail, so we can pack all of the
1531 * updates into a single transaction.
1534 transaction
= ref_store_transaction_begin(ref_store
, &err
);
1538 for_each_string_list_item(item
, refnames
) {
1539 if (ref_transaction_delete(transaction
, item
->string
, NULL
,
1540 flags
, msg
, &err
)) {
1541 warning(_("could not delete reference %s: %s"),
1542 item
->string
, err
.buf
);
1547 ret
= ref_transaction_commit(transaction
, &err
);
1550 if (refnames
->nr
== 1)
1551 error(_("could not delete reference %s: %s"),
1552 refnames
->items
[0].string
, err
.buf
);
1554 error(_("could not delete references: %s"), err
.buf
);
1557 ref_transaction_free(transaction
);
1558 strbuf_release(&err
);
1562 static int packed_pack_refs(struct ref_store
*ref_store
, unsigned int flags
)
1565 * Packed refs are already packed. It might be that loose refs
1566 * are packed *into* a packed refs store, but that is done by
1567 * updating the packed references via a transaction.
1572 static int packed_create_symref(struct ref_store
*ref_store
,
1573 const char *refname
, const char *target
,
1576 BUG("packed reference store does not support symrefs");
1579 static int packed_rename_ref(struct ref_store
*ref_store
,
1580 const char *oldrefname
, const char *newrefname
,
1583 BUG("packed reference store does not support renaming references");
1586 static int packed_copy_ref(struct ref_store
*ref_store
,
1587 const char *oldrefname
, const char *newrefname
,
1590 BUG("packed reference store does not support copying references");
1593 static struct ref_iterator
*packed_reflog_iterator_begin(struct ref_store
*ref_store
)
1595 return empty_ref_iterator_begin();
1598 static int packed_for_each_reflog_ent(struct ref_store
*ref_store
,
1599 const char *refname
,
1600 each_reflog_ent_fn fn
, void *cb_data
)
1605 static int packed_for_each_reflog_ent_reverse(struct ref_store
*ref_store
,
1606 const char *refname
,
1607 each_reflog_ent_fn fn
,
1613 static int packed_reflog_exists(struct ref_store
*ref_store
,
1614 const char *refname
)
1619 static int packed_create_reflog(struct ref_store
*ref_store
,
1620 const char *refname
, int force_create
,
1623 BUG("packed reference store does not support reflogs");
1626 static int packed_delete_reflog(struct ref_store
*ref_store
,
1627 const char *refname
)
1632 static int packed_reflog_expire(struct ref_store
*ref_store
,
1633 const char *refname
, const struct object_id
*oid
,
1635 reflog_expiry_prepare_fn prepare_fn
,
1636 reflog_expiry_should_prune_fn should_prune_fn
,
1637 reflog_expiry_cleanup_fn cleanup_fn
,
1638 void *policy_cb_data
)
1643 struct ref_storage_be refs_be_packed
= {
1646 packed_ref_store_create
,
1648 packed_transaction_prepare
,
1649 packed_transaction_finish
,
1650 packed_transaction_abort
,
1651 packed_initial_transaction_commit
,
1654 packed_create_symref
,
1659 packed_ref_iterator_begin
,
1660 packed_read_raw_ref
,
1662 packed_reflog_iterator_begin
,
1663 packed_for_each_reflog_ent
,
1664 packed_for_each_reflog_ent_reverse
,
1665 packed_reflog_exists
,
1666 packed_create_reflog
,
1667 packed_delete_reflog
,
1668 packed_reflog_expire