1 #include "../git-compat-util.h"
5 #include "refs-internal.h"
6 #include "packed-backend.h"
7 #include "../iterator.h"
8 #include "../lockfile.h"
9 #include "../chdir-notify.h"
13 * Don't use mmap() at all for reading `packed-refs`.
18 * Can use mmap() for reading `packed-refs`, but the file must
19 * not remain mmapped. This is the usual option on Windows,
20 * where you cannot rename a new version of a file onto a file
21 * that is currently mmapped.
26 * It is OK to leave the `packed-refs` file mmapped while
27 * arbitrary other code is running.
33 static enum mmap_strategy mmap_strategy
= MMAP_NONE
;
34 #elif defined(MMAP_PREVENTS_DELETE)
35 static enum mmap_strategy mmap_strategy
= MMAP_TEMPORARY
;
37 static enum mmap_strategy mmap_strategy
= MMAP_OK
;
40 struct packed_ref_store
;
43 * A `snapshot` represents one snapshot of a `packed-refs` file.
45 * Normally, this will be a mmapped view of the contents of the
46 * `packed-refs` file at the time the snapshot was created. However,
47 * if the `packed-refs` file was not sorted, this might point at heap
48 * memory holding the contents of the `packed-refs` file with its
49 * records sorted by refname.
51 * `snapshot` instances are reference counted (via
52 * `acquire_snapshot()` and `release_snapshot()`). This is to prevent
53 * an instance from disappearing while an iterator is still iterating
54 * over it. Instances are garbage collected when their `referrers`
57 * The most recent `snapshot`, if available, is referenced by the
58 * `packed_ref_store`. Its freshness is checked whenever
59 * `get_snapshot()` is called; if the existing snapshot is obsolete, a
60 * new snapshot is taken.
64 * A back-pointer to the packed_ref_store with which this
65 * snapshot is associated:
67 struct packed_ref_store
*refs
;
69 /* Is the `packed-refs` file currently mmapped? */
73 * The contents of the `packed-refs` file:
75 * - buf -- a pointer to the start of the memory
76 * - start -- a pointer to the first byte of actual references
77 * (i.e., after the header line, if one is present)
78 * - eof -- a pointer just past the end of the reference
81 * If the `packed-refs` file was already sorted, `buf` points
82 * at the mmapped contents of the file. If not, it points at
83 * heap-allocated memory containing the contents, sorted. If
84 * there were no contents (e.g., because the file didn't
85 * exist), `buf`, `start`, and `eof` are all NULL.
87 char *buf
, *start
, *eof
;
90 * What is the peeled state of the `packed-refs` file that
91 * this snapshot represents? (This is usually determined from
94 enum { PEELED_NONE
, PEELED_TAGS
, PEELED_FULLY
} peeled
;
97 * Count of references to this instance, including the pointer
98 * from `packed_ref_store::snapshot`, if any. The instance
99 * will not be freed as long as the reference count is
102 unsigned int referrers
;
105 * The metadata of the `packed-refs` file from which this
106 * snapshot was created, used to tell if the file has been
107 * replaced since we read it.
109 struct stat_validity validity
;
113 * A `ref_store` representing references stored in a `packed-refs`
114 * file. It implements the `ref_store` interface, though it has some
117 * - It cannot store symbolic references.
119 * - It cannot store reflogs.
121 * - It does not support reference renaming (though it could).
123 * On the other hand, it can be locked outside of a reference
124 * transaction. In that case, it remains locked even after the
125 * transaction is done and the new `packed-refs` file is activated.
127 struct packed_ref_store
{
128 struct ref_store base
;
130 unsigned int store_flags
;
132 /* The path of the "packed-refs" file: */
136 * A snapshot of the values read from the `packed-refs` file,
137 * if it might still be current; otherwise, NULL.
139 struct snapshot
*snapshot
;
142 * Lock used for the "packed-refs" file. Note that this (and
143 * thus the enclosing `packed_ref_store`) must not be freed.
145 struct lock_file lock
;
148 * Temporary file used when rewriting new contents to the
149 * "packed-refs" file. Note that this (and thus the enclosing
150 * `packed_ref_store`) must not be freed.
152 struct tempfile
*tempfile
;
156 * Increment the reference count of `*snapshot`.
158 static void acquire_snapshot(struct snapshot
*snapshot
)
160 snapshot
->referrers
++;
164 * If the buffer in `snapshot` is active, then either munmap the
165 * memory and close the file, or free the memory. Then set the buffer
168 static void clear_snapshot_buffer(struct snapshot
*snapshot
)
170 if (snapshot
->mmapped
) {
171 if (munmap(snapshot
->buf
, snapshot
->eof
- snapshot
->buf
))
172 die_errno("error ummapping packed-refs file %s",
173 snapshot
->refs
->path
);
174 snapshot
->mmapped
= 0;
178 snapshot
->buf
= snapshot
->start
= snapshot
->eof
= NULL
;
182 * Decrease the reference count of `*snapshot`. If it goes to zero,
183 * free `*snapshot` and return true; otherwise return false.
185 static int release_snapshot(struct snapshot
*snapshot
)
187 if (!--snapshot
->referrers
) {
188 stat_validity_clear(&snapshot
->validity
);
189 clear_snapshot_buffer(snapshot
);
197 struct ref_store
*packed_ref_store_create(struct repository
*repo
,
199 unsigned int store_flags
)
201 struct packed_ref_store
*refs
= xcalloc(1, sizeof(*refs
));
202 struct ref_store
*ref_store
= (struct ref_store
*)refs
;
203 struct strbuf sb
= STRBUF_INIT
;
205 base_ref_store_init(ref_store
, repo
, gitdir
, &refs_be_packed
);
206 refs
->store_flags
= store_flags
;
208 strbuf_addf(&sb
, "%s/packed-refs", gitdir
);
209 refs
->path
= strbuf_detach(&sb
, NULL
);
210 chdir_notify_reparent("packed-refs", &refs
->path
);
215 * Downcast `ref_store` to `packed_ref_store`. Die if `ref_store` is
216 * not a `packed_ref_store`. Also die if `packed_ref_store` doesn't
217 * support at least the flags specified in `required_flags`. `caller`
218 * is used in any necessary error messages.
220 static struct packed_ref_store
*packed_downcast(struct ref_store
*ref_store
,
221 unsigned int required_flags
,
224 struct packed_ref_store
*refs
;
226 if (ref_store
->be
!= &refs_be_packed
)
227 BUG("ref_store is type \"%s\" not \"packed\" in %s",
228 ref_store
->be
->name
, caller
);
230 refs
= (struct packed_ref_store
*)ref_store
;
232 if ((refs
->store_flags
& required_flags
) != required_flags
)
233 BUG("unallowed operation (%s), requires %x, has %x\n",
234 caller
, required_flags
, refs
->store_flags
);
239 static void clear_snapshot(struct packed_ref_store
*refs
)
241 if (refs
->snapshot
) {
242 struct snapshot
*snapshot
= refs
->snapshot
;
244 refs
->snapshot
= NULL
;
245 release_snapshot(snapshot
);
249 static NORETURN
void die_unterminated_line(const char *path
,
250 const char *p
, size_t len
)
253 die("unterminated line in %s: %.*s", path
, (int)len
, p
);
255 die("unterminated line in %s: %.75s...", path
, p
);
258 static NORETURN
void die_invalid_line(const char *path
,
259 const char *p
, size_t len
)
261 const char *eol
= memchr(p
, '\n', len
);
264 die_unterminated_line(path
, p
, len
);
265 else if (eol
- p
< 80)
266 die("unexpected line in %s: %.*s", path
, (int)(eol
- p
), p
);
268 die("unexpected line in %s: %.75s...", path
, p
);
272 struct snapshot_record
{
277 static int cmp_packed_ref_records(const void *v1
, const void *v2
)
279 const struct snapshot_record
*e1
= v1
, *e2
= v2
;
280 const char *r1
= e1
->start
+ the_hash_algo
->hexsz
+ 1;
281 const char *r2
= e2
->start
+ the_hash_algo
->hexsz
+ 1;
285 return *r2
== '\n' ? 0 : -1;
290 return (unsigned char)*r1
< (unsigned char)*r2
? -1 : +1;
298 * Compare a snapshot record at `rec` to the specified NUL-terminated
301 static int cmp_record_to_refname(const char *rec
, const char *refname
)
303 const char *r1
= rec
+ the_hash_algo
->hexsz
+ 1;
304 const char *r2
= refname
;
312 return (unsigned char)*r1
< (unsigned char)*r2
? -1 : +1;
319 * `snapshot->buf` is not known to be sorted. Check whether it is, and
320 * if not, sort it into new memory and munmap/free the old storage.
322 static void sort_snapshot(struct snapshot
*snapshot
)
324 struct snapshot_record
*records
= NULL
;
325 size_t alloc
= 0, nr
= 0;
327 const char *pos
, *eof
, *eol
;
329 char *new_buffer
, *dst
;
331 pos
= snapshot
->start
;
340 * Initialize records based on a crude estimate of the number
341 * of references in the file (we'll grow it below if needed):
343 ALLOC_GROW(records
, len
/ 80 + 20, alloc
);
346 eol
= memchr(pos
, '\n', eof
- pos
);
348 /* The safety check should prevent this. */
349 BUG("unterminated line found in packed-refs");
350 if (eol
- pos
< the_hash_algo
->hexsz
+ 2)
351 die_invalid_line(snapshot
->refs
->path
,
354 if (eol
< eof
&& *eol
== '^') {
356 * Keep any peeled line together with its
359 const char *peeled_start
= eol
;
361 eol
= memchr(peeled_start
, '\n', eof
- peeled_start
);
363 /* The safety check should prevent this. */
364 BUG("unterminated peeled line found in packed-refs");
368 ALLOC_GROW(records
, nr
+ 1, alloc
);
369 records
[nr
].start
= pos
;
370 records
[nr
].len
= eol
- pos
;
375 cmp_packed_ref_records(&records
[nr
- 2],
376 &records
[nr
- 1]) >= 0)
385 /* We need to sort the memory. First we sort the records array: */
386 QSORT(records
, nr
, cmp_packed_ref_records
);
389 * Allocate a new chunk of memory, and copy the old memory to
390 * the new in the order indicated by `records` (not bothering
391 * with the header line):
393 new_buffer
= xmalloc(len
);
394 for (dst
= new_buffer
, i
= 0; i
< nr
; i
++) {
395 memcpy(dst
, records
[i
].start
, records
[i
].len
);
396 dst
+= records
[i
].len
;
400 * Now munmap the old buffer and use the sorted buffer in its
403 clear_snapshot_buffer(snapshot
);
404 snapshot
->buf
= snapshot
->start
= new_buffer
;
405 snapshot
->eof
= new_buffer
+ len
;
412 * Return a pointer to the start of the record that contains the
413 * character `*p` (which must be within the buffer). If no other
414 * record start is found, return `buf`.
416 static const char *find_start_of_record(const char *buf
, const char *p
)
418 while (p
> buf
&& (p
[-1] != '\n' || p
[0] == '^'))
424 * Return a pointer to the start of the record following the record
425 * that contains `*p`. If none is found before `end`, return `end`.
427 static const char *find_end_of_record(const char *p
, const char *end
)
429 while (++p
< end
&& (p
[-1] != '\n' || p
[0] == '^'))
435 * We want to be able to compare mmapped reference records quickly,
436 * without totally parsing them. We can do so because the records are
437 * LF-terminated, and the refname should start exactly (GIT_SHA1_HEXSZ
438 * + 1) bytes past the beginning of the record.
440 * But what if the `packed-refs` file contains garbage? We're willing
441 * to tolerate not detecting the problem, as long as we don't produce
442 * totally garbled output (we can't afford to check the integrity of
443 * the whole file during every Git invocation). But we do want to be
444 * sure that we never read past the end of the buffer in memory and
445 * perform an illegal memory access.
447 * Guarantee that minimum level of safety by verifying that the last
448 * record in the file is LF-terminated, and that it has at least
449 * (GIT_SHA1_HEXSZ + 1) characters before the LF. Die if either of
450 * these checks fails.
452 static void verify_buffer_safe(struct snapshot
*snapshot
)
454 const char *start
= snapshot
->start
;
455 const char *eof
= snapshot
->eof
;
456 const char *last_line
;
461 last_line
= find_start_of_record(start
, eof
- 1);
462 if (*(eof
- 1) != '\n' || eof
- last_line
< the_hash_algo
->hexsz
+ 2)
463 die_invalid_line(snapshot
->refs
->path
,
464 last_line
, eof
- last_line
);
467 #define SMALL_FILE_SIZE (32*1024)
470 * Depending on `mmap_strategy`, either mmap or read the contents of
471 * the `packed-refs` file into the snapshot. Return 1 if the file
472 * existed and was read, or 0 if the file was absent or empty. Die on
475 static int load_contents(struct snapshot
*snapshot
)
482 fd
= open(snapshot
->refs
->path
, O_RDONLY
);
484 if (errno
== ENOENT
) {
486 * This is OK; it just means that no
487 * "packed-refs" file has been written yet,
488 * which is equivalent to it being empty,
489 * which is its state when initialized with
494 die_errno("couldn't read %s", snapshot
->refs
->path
);
498 stat_validity_update(&snapshot
->validity
, fd
);
500 if (fstat(fd
, &st
) < 0)
501 die_errno("couldn't stat %s", snapshot
->refs
->path
);
502 size
= xsize_t(st
.st_size
);
507 } else if (mmap_strategy
== MMAP_NONE
|| size
<= SMALL_FILE_SIZE
) {
508 snapshot
->buf
= xmalloc(size
);
509 bytes_read
= read_in_full(fd
, snapshot
->buf
, size
);
510 if (bytes_read
< 0 || bytes_read
!= size
)
511 die_errno("couldn't read %s", snapshot
->refs
->path
);
512 snapshot
->mmapped
= 0;
514 snapshot
->buf
= xmmap(NULL
, size
, PROT_READ
, MAP_PRIVATE
, fd
, 0);
515 snapshot
->mmapped
= 1;
519 snapshot
->start
= snapshot
->buf
;
520 snapshot
->eof
= snapshot
->buf
+ size
;
526 * Find the place in `snapshot->buf` where the start of the record for
527 * `refname` starts. If `mustexist` is true and the reference doesn't
528 * exist, then return NULL. If `mustexist` is false and the reference
529 * doesn't exist, then return the point where that reference would be
530 * inserted, or `snapshot->eof` (which might be NULL) if it would be
531 * inserted at the end of the file. In the latter mode, `refname`
532 * doesn't have to be a proper reference name; for example, one could
533 * search for "refs/replace/" to find the start of any replace
536 * The record is sought using a binary search, so `snapshot->buf` must
539 static const char *find_reference_location(struct snapshot
*snapshot
,
540 const char *refname
, int mustexist
)
543 * This is not *quite* a garden-variety binary search, because
544 * the data we're searching is made up of records, and we
545 * always need to find the beginning of a record to do a
546 * comparison. A "record" here is one line for the reference
547 * itself and zero or one peel lines that start with '^'. Our
548 * loop invariant is described in the next two comments.
552 * A pointer to the character at the start of a record whose
553 * preceding records all have reference names that come
554 * *before* `refname`.
556 const char *lo
= snapshot
->start
;
559 * A pointer to a the first character of a record whose
560 * reference name comes *after* `refname`.
562 const char *hi
= snapshot
->eof
;
565 const char *mid
, *rec
;
568 mid
= lo
+ (hi
- lo
) / 2;
569 rec
= find_start_of_record(lo
, mid
);
570 cmp
= cmp_record_to_refname(rec
, refname
);
572 lo
= find_end_of_record(mid
, hi
);
573 } else if (cmp
> 0) {
587 * Create a newly-allocated `snapshot` of the `packed-refs` file in
588 * its current state and return it. The return value will already have
589 * its reference count incremented.
591 * A comment line of the form "# pack-refs with: " may contain zero or
592 * more traits. We interpret the traits as follows:
594 * Neither `peeled` nor `fully-peeled`:
596 * Probably no references are peeled. But if the file contains a
597 * peeled value for a reference, we will use it.
601 * References under "refs/tags/", if they *can* be peeled, *are*
602 * peeled in this file. References outside of "refs/tags/" are
603 * probably not peeled even if they could have been, but if we find
604 * a peeled value for such a reference we will use it.
608 * All references in the file that can be peeled are peeled.
609 * Inversely (and this is more important), any references in the
610 * file for which no peeled value is recorded is not peelable. This
611 * trait should typically be written alongside "peeled" for
612 * compatibility with older clients, but we do not require it
613 * (i.e., "peeled" is a no-op if "fully-peeled" is set).
617 * The references in this file are known to be sorted by refname.
619 static struct snapshot
*create_snapshot(struct packed_ref_store
*refs
)
621 struct snapshot
*snapshot
= xcalloc(1, sizeof(*snapshot
));
624 snapshot
->refs
= refs
;
625 acquire_snapshot(snapshot
);
626 snapshot
->peeled
= PEELED_NONE
;
628 if (!load_contents(snapshot
))
631 /* If the file has a header line, process it: */
632 if (snapshot
->buf
< snapshot
->eof
&& *snapshot
->buf
== '#') {
634 struct string_list traits
= STRING_LIST_INIT_NODUP
;
636 eol
= memchr(snapshot
->buf
, '\n',
637 snapshot
->eof
- snapshot
->buf
);
639 die_unterminated_line(refs
->path
,
641 snapshot
->eof
- snapshot
->buf
);
643 tmp
= xmemdupz(snapshot
->buf
, eol
- snapshot
->buf
);
645 if (!skip_prefix(tmp
, "# pack-refs with:", (const char **)&p
))
646 die_invalid_line(refs
->path
,
648 snapshot
->eof
- snapshot
->buf
);
650 string_list_split_in_place(&traits
, p
, ' ', -1);
652 if (unsorted_string_list_has_string(&traits
, "fully-peeled"))
653 snapshot
->peeled
= PEELED_FULLY
;
654 else if (unsorted_string_list_has_string(&traits
, "peeled"))
655 snapshot
->peeled
= PEELED_TAGS
;
657 sorted
= unsorted_string_list_has_string(&traits
, "sorted");
659 /* perhaps other traits later as well */
661 /* The "+ 1" is for the LF character. */
662 snapshot
->start
= eol
+ 1;
664 string_list_clear(&traits
, 0);
668 verify_buffer_safe(snapshot
);
671 sort_snapshot(snapshot
);
674 * Reordering the records might have moved a short one
675 * to the end of the buffer, so verify the buffer's
678 verify_buffer_safe(snapshot
);
681 if (mmap_strategy
!= MMAP_OK
&& snapshot
->mmapped
) {
683 * We don't want to leave the file mmapped, so we are
684 * forced to make a copy now:
686 size_t size
= snapshot
->eof
- snapshot
->start
;
687 char *buf_copy
= xmalloc(size
);
689 memcpy(buf_copy
, snapshot
->start
, size
);
690 clear_snapshot_buffer(snapshot
);
691 snapshot
->buf
= snapshot
->start
= buf_copy
;
692 snapshot
->eof
= buf_copy
+ size
;
699 * Check that `refs->snapshot` (if present) still reflects the
700 * contents of the `packed-refs` file. If not, clear the snapshot.
702 static void validate_snapshot(struct packed_ref_store
*refs
)
704 if (refs
->snapshot
&&
705 !stat_validity_check(&refs
->snapshot
->validity
, refs
->path
))
706 clear_snapshot(refs
);
710 * Get the `snapshot` for the specified packed_ref_store, creating and
711 * populating it if it hasn't been read before or if the file has been
712 * changed (according to its `validity` field) since it was last read.
713 * On the other hand, if we hold the lock, then assume that the file
714 * hasn't been changed out from under us, so skip the extra `stat()`
715 * call in `stat_validity_check()`. This function does *not* increase
716 * the snapshot's reference count on behalf of the caller.
718 static struct snapshot
*get_snapshot(struct packed_ref_store
*refs
)
720 if (!is_lock_file_locked(&refs
->lock
))
721 validate_snapshot(refs
);
724 refs
->snapshot
= create_snapshot(refs
);
726 return refs
->snapshot
;
729 static int packed_read_raw_ref(struct ref_store
*ref_store
, const char *refname
,
730 struct object_id
*oid
, struct strbuf
*referent UNUSED
,
731 unsigned int *type
, int *failure_errno
)
733 struct packed_ref_store
*refs
=
734 packed_downcast(ref_store
, REF_STORE_READ
, "read_raw_ref");
735 struct snapshot
*snapshot
= get_snapshot(refs
);
740 rec
= find_reference_location(snapshot
, refname
, 1);
743 /* refname is not a packed reference. */
744 *failure_errno
= ENOENT
;
748 if (get_oid_hex(rec
, oid
))
749 die_invalid_line(refs
->path
, rec
, snapshot
->eof
- rec
);
751 *type
= REF_ISPACKED
;
756 * This value is set in `base.flags` if the peeled value of the
757 * current reference is known. In that case, `peeled` contains the
758 * correct peeled value for the reference, which might be `null_oid`
759 * if the reference is not a tag or if it is broken.
761 #define REF_KNOWS_PEELED 0x40
764 * An iterator over a snapshot of a `packed-refs` file.
766 struct packed_ref_iterator
{
767 struct ref_iterator base
;
769 struct snapshot
*snapshot
;
771 /* The current position in the snapshot's buffer: */
774 /* The end of the part of the buffer that will be iterated over: */
777 /* Scratch space for current values: */
778 struct object_id oid
, peeled
;
779 struct strbuf refname_buf
;
781 struct repository
*repo
;
786 * Move the iterator to the next record in the snapshot, without
787 * respect for whether the record is actually required by the current
788 * iteration. Adjust the fields in `iter` and return `ITER_OK` or
789 * `ITER_DONE`. This function does not free the iterator in the case
792 static int next_record(struct packed_ref_iterator
*iter
)
794 const char *p
= iter
->pos
, *eol
;
796 strbuf_reset(&iter
->refname_buf
);
798 if (iter
->pos
== iter
->eof
)
801 iter
->base
.flags
= REF_ISPACKED
;
803 if (iter
->eof
- p
< the_hash_algo
->hexsz
+ 2 ||
804 parse_oid_hex(p
, &iter
->oid
, &p
) ||
806 die_invalid_line(iter
->snapshot
->refs
->path
,
807 iter
->pos
, iter
->eof
- iter
->pos
);
809 eol
= memchr(p
, '\n', iter
->eof
- p
);
811 die_unterminated_line(iter
->snapshot
->refs
->path
,
812 iter
->pos
, iter
->eof
- iter
->pos
);
814 strbuf_add(&iter
->refname_buf
, p
, eol
- p
);
815 iter
->base
.refname
= iter
->refname_buf
.buf
;
817 if (check_refname_format(iter
->base
.refname
, REFNAME_ALLOW_ONELEVEL
)) {
818 if (!refname_is_safe(iter
->base
.refname
))
819 die("packed refname is dangerous: %s",
822 iter
->base
.flags
|= REF_BAD_NAME
| REF_ISBROKEN
;
824 if (iter
->snapshot
->peeled
== PEELED_FULLY
||
825 (iter
->snapshot
->peeled
== PEELED_TAGS
&&
826 starts_with(iter
->base
.refname
, "refs/tags/")))
827 iter
->base
.flags
|= REF_KNOWS_PEELED
;
831 if (iter
->pos
< iter
->eof
&& *iter
->pos
== '^') {
833 if (iter
->eof
- p
< the_hash_algo
->hexsz
+ 1 ||
834 parse_oid_hex(p
, &iter
->peeled
, &p
) ||
836 die_invalid_line(iter
->snapshot
->refs
->path
,
837 iter
->pos
, iter
->eof
- iter
->pos
);
841 * Regardless of what the file header said, we
842 * definitely know the value of *this* reference. But
843 * we suppress it if the reference is broken:
845 if ((iter
->base
.flags
& REF_ISBROKEN
)) {
846 oidclr(&iter
->peeled
);
847 iter
->base
.flags
&= ~REF_KNOWS_PEELED
;
849 iter
->base
.flags
|= REF_KNOWS_PEELED
;
852 oidclr(&iter
->peeled
);
858 static int packed_ref_iterator_advance(struct ref_iterator
*ref_iterator
)
860 struct packed_ref_iterator
*iter
=
861 (struct packed_ref_iterator
*)ref_iterator
;
864 while ((ok
= next_record(iter
)) == ITER_OK
) {
865 if (iter
->flags
& DO_FOR_EACH_PER_WORKTREE_ONLY
&&
866 !is_per_worktree_ref(iter
->base
.refname
))
869 if (!(iter
->flags
& DO_FOR_EACH_INCLUDE_BROKEN
) &&
870 !ref_resolves_to_object(iter
->base
.refname
, iter
->repo
,
871 &iter
->oid
, iter
->flags
))
877 if (ref_iterator_abort(ref_iterator
) != ITER_DONE
)
883 static int packed_ref_iterator_peel(struct ref_iterator
*ref_iterator
,
884 struct object_id
*peeled
)
886 struct packed_ref_iterator
*iter
=
887 (struct packed_ref_iterator
*)ref_iterator
;
889 if (iter
->repo
!= the_repository
)
890 BUG("peeling for non-the_repository is not supported");
892 if ((iter
->base
.flags
& REF_KNOWS_PEELED
)) {
893 oidcpy(peeled
, &iter
->peeled
);
894 return is_null_oid(&iter
->peeled
) ? -1 : 0;
895 } else if ((iter
->base
.flags
& (REF_ISBROKEN
| REF_ISSYMREF
))) {
898 return peel_object(&iter
->oid
, peeled
) ? -1 : 0;
902 static int packed_ref_iterator_abort(struct ref_iterator
*ref_iterator
)
904 struct packed_ref_iterator
*iter
=
905 (struct packed_ref_iterator
*)ref_iterator
;
908 strbuf_release(&iter
->refname_buf
);
909 release_snapshot(iter
->snapshot
);
910 base_ref_iterator_free(ref_iterator
);
914 static struct ref_iterator_vtable packed_ref_iterator_vtable
= {
915 .advance
= packed_ref_iterator_advance
,
916 .peel
= packed_ref_iterator_peel
,
917 .abort
= packed_ref_iterator_abort
920 static struct ref_iterator
*packed_ref_iterator_begin(
921 struct ref_store
*ref_store
,
922 const char *prefix
, unsigned int flags
)
924 struct packed_ref_store
*refs
;
925 struct snapshot
*snapshot
;
927 struct packed_ref_iterator
*iter
;
928 struct ref_iterator
*ref_iterator
;
929 unsigned int required_flags
= REF_STORE_READ
;
931 if (!(flags
& DO_FOR_EACH_INCLUDE_BROKEN
))
932 required_flags
|= REF_STORE_ODB
;
933 refs
= packed_downcast(ref_store
, required_flags
, "ref_iterator_begin");
936 * Note that `get_snapshot()` internally checks whether the
937 * snapshot is up to date with what is on disk, and re-reads
940 snapshot
= get_snapshot(refs
);
942 if (prefix
&& *prefix
)
943 start
= find_reference_location(snapshot
, prefix
, 0);
945 start
= snapshot
->start
;
947 if (start
== snapshot
->eof
)
948 return empty_ref_iterator_begin();
950 CALLOC_ARRAY(iter
, 1);
951 ref_iterator
= &iter
->base
;
952 base_ref_iterator_init(ref_iterator
, &packed_ref_iterator_vtable
, 1);
954 iter
->snapshot
= snapshot
;
955 acquire_snapshot(snapshot
);
958 iter
->eof
= snapshot
->eof
;
959 strbuf_init(&iter
->refname_buf
, 0);
961 iter
->base
.oid
= &iter
->oid
;
963 iter
->repo
= ref_store
->repo
;
966 if (prefix
&& *prefix
)
967 /* Stop iteration after we've gone *past* prefix: */
968 ref_iterator
= prefix_ref_iterator_begin(ref_iterator
, prefix
, 0);
974 * Write an entry to the packed-refs file for the specified refname.
975 * If peeled is non-NULL, write it as the entry's peeled value. On
976 * error, return a nonzero value and leave errno set at the value left
977 * by the failing call to `fprintf()`.
979 static int write_packed_entry(FILE *fh
, const char *refname
,
980 const struct object_id
*oid
,
981 const struct object_id
*peeled
)
983 if (fprintf(fh
, "%s %s\n", oid_to_hex(oid
), refname
) < 0 ||
984 (peeled
&& fprintf(fh
, "^%s\n", oid_to_hex(peeled
)) < 0))
990 int packed_refs_lock(struct ref_store
*ref_store
, int flags
, struct strbuf
*err
)
992 struct packed_ref_store
*refs
=
993 packed_downcast(ref_store
, REF_STORE_WRITE
| REF_STORE_MAIN
,
995 static int timeout_configured
= 0;
996 static int timeout_value
= 1000;
998 if (!timeout_configured
) {
999 git_config_get_int("core.packedrefstimeout", &timeout_value
);
1000 timeout_configured
= 1;
1004 * Note that we close the lockfile immediately because we
1005 * don't write new content to it, but rather to a separate
1008 if (hold_lock_file_for_update_timeout(
1011 flags
, timeout_value
) < 0) {
1012 unable_to_lock_message(refs
->path
, errno
, err
);
1016 if (close_lock_file_gently(&refs
->lock
)) {
1017 strbuf_addf(err
, "unable to close %s: %s", refs
->path
, strerror(errno
));
1018 rollback_lock_file(&refs
->lock
);
1023 * There is a stat-validity problem might cause `update-ref -d`
1024 * lost the newly commit of a ref, because a new `packed-refs`
1025 * file might has the same on-disk file attributes such as
1026 * timestamp, file size and inode value, but has a changed
1029 * This could happen with a very small chance when
1030 * `update-ref -d` is called and at the same time another
1031 * `pack-refs --all` process is running.
1033 * Now that we hold the `packed-refs` lock, it is important
1034 * to make sure we could read the latest version of
1035 * `packed-refs` file no matter we have just mmap it or not.
1036 * So what need to do is clear the snapshot if we hold it
1039 clear_snapshot(refs
);
1042 * Now make sure that the packed-refs file as it exists in the
1043 * locked state is loaded into the snapshot:
1049 void packed_refs_unlock(struct ref_store
*ref_store
)
1051 struct packed_ref_store
*refs
= packed_downcast(
1053 REF_STORE_READ
| REF_STORE_WRITE
,
1054 "packed_refs_unlock");
1056 if (!is_lock_file_locked(&refs
->lock
))
1057 BUG("packed_refs_unlock() called when not locked");
1058 rollback_lock_file(&refs
->lock
);
1061 int packed_refs_is_locked(struct ref_store
*ref_store
)
1063 struct packed_ref_store
*refs
= packed_downcast(
1065 REF_STORE_READ
| REF_STORE_WRITE
,
1066 "packed_refs_is_locked");
1068 return is_lock_file_locked(&refs
->lock
);
1072 * The packed-refs header line that we write out. Perhaps other traits
1073 * will be added later.
1075 * Note that earlier versions of Git used to parse these traits by
1076 * looking for " trait " in the line. For this reason, the space after
1077 * the colon and the trailing space are required.
1079 static const char PACKED_REFS_HEADER
[] =
1080 "# pack-refs with: peeled fully-peeled sorted \n";
1082 static int packed_init_db(struct ref_store
*ref_store UNUSED
,
1083 struct strbuf
*err UNUSED
)
1085 /* Nothing to do. */
1090 * Write the packed refs from the current snapshot to the packed-refs
1091 * tempfile, incorporating any changes from `updates`. `updates` must
1092 * be a sorted string list whose keys are the refnames and whose util
1093 * values are `struct ref_update *`. On error, rollback the tempfile,
1094 * write an error message to `err`, and return a nonzero value.
1096 * The packfile must be locked before calling this function and will
1097 * remain locked when it is done.
1099 static int write_with_updates(struct packed_ref_store
*refs
,
1100 struct string_list
*updates
,
1103 struct ref_iterator
*iter
= NULL
;
1107 struct strbuf sb
= STRBUF_INIT
;
1108 char *packed_refs_path
;
1110 if (!is_lock_file_locked(&refs
->lock
))
1111 BUG("write_with_updates() called while unlocked");
1114 * If packed-refs is a symlink, we want to overwrite the
1115 * symlinked-to file, not the symlink itself. Also, put the
1116 * staging file next to it:
1118 packed_refs_path
= get_locked_file_path(&refs
->lock
);
1119 strbuf_addf(&sb
, "%s.new", packed_refs_path
);
1120 free(packed_refs_path
);
1121 refs
->tempfile
= create_tempfile(sb
.buf
);
1122 if (!refs
->tempfile
) {
1123 strbuf_addf(err
, "unable to create file %s: %s",
1124 sb
.buf
, strerror(errno
));
1125 strbuf_release(&sb
);
1128 strbuf_release(&sb
);
1130 out
= fdopen_tempfile(refs
->tempfile
, "w");
1132 strbuf_addf(err
, "unable to fdopen packed-refs tempfile: %s",
1137 if (fprintf(out
, "%s", PACKED_REFS_HEADER
) < 0)
1141 * We iterate in parallel through the current list of refs and
1142 * the list of updates, processing an entry from at least one
1143 * of the lists each time through the loop. When the current
1144 * list of refs is exhausted, set iter to NULL. When the list
1145 * of updates is exhausted, leave i set to updates->nr.
1147 iter
= packed_ref_iterator_begin(&refs
->base
, "",
1148 DO_FOR_EACH_INCLUDE_BROKEN
);
1149 if ((ok
= ref_iterator_advance(iter
)) != ITER_OK
)
1154 while (iter
|| i
< updates
->nr
) {
1155 struct ref_update
*update
= NULL
;
1158 if (i
>= updates
->nr
) {
1161 update
= updates
->items
[i
].util
;
1166 cmp
= strcmp(iter
->refname
, update
->refname
);
1171 * There is both an old value and an update
1172 * for this reference. Check the old value if
1175 if ((update
->flags
& REF_HAVE_OLD
)) {
1176 if (is_null_oid(&update
->old_oid
)) {
1177 strbuf_addf(err
, "cannot update ref '%s': "
1178 "reference already exists",
1181 } else if (!oideq(&update
->old_oid
, iter
->oid
)) {
1182 strbuf_addf(err
, "cannot update ref '%s': "
1183 "is at %s but expected %s",
1185 oid_to_hex(iter
->oid
),
1186 oid_to_hex(&update
->old_oid
));
1191 /* Now figure out what to use for the new value: */
1192 if ((update
->flags
& REF_HAVE_NEW
)) {
1194 * The update takes precedence. Skip
1195 * the iterator over the unneeded
1198 if ((ok
= ref_iterator_advance(iter
)) != ITER_OK
)
1203 * The update doesn't actually want to
1204 * change anything. We're done with it.
1209 } else if (cmp
> 0) {
1211 * There is no old value but there is an
1212 * update for this reference. Make sure that
1213 * the update didn't expect an existing value:
1215 if ((update
->flags
& REF_HAVE_OLD
) &&
1216 !is_null_oid(&update
->old_oid
)) {
1217 strbuf_addf(err
, "cannot update ref '%s': "
1218 "reference is missing but expected %s",
1220 oid_to_hex(&update
->old_oid
));
1226 /* Pass the old reference through. */
1228 struct object_id peeled
;
1229 int peel_error
= ref_iterator_peel(iter
, &peeled
);
1231 if (write_packed_entry(out
, iter
->refname
,
1233 peel_error
? NULL
: &peeled
))
1236 if ((ok
= ref_iterator_advance(iter
)) != ITER_OK
)
1238 } else if (is_null_oid(&update
->new_oid
)) {
1240 * The update wants to delete the reference,
1241 * and the reference either didn't exist or we
1242 * have already skipped it. So we're done with
1243 * the update (and don't have to write
1248 struct object_id peeled
;
1249 int peel_error
= peel_object(&update
->new_oid
,
1252 if (write_packed_entry(out
, update
->refname
,
1254 peel_error
? NULL
: &peeled
))
1261 if (ok
!= ITER_DONE
) {
1262 strbuf_addstr(err
, "unable to write packed-refs file: "
1263 "error iterating over old contents");
1268 fsync_component(FSYNC_COMPONENT_REFERENCE
, get_tempfile_fd(refs
->tempfile
)) ||
1269 close_tempfile_gently(refs
->tempfile
)) {
1270 strbuf_addf(err
, "error closing file %s: %s",
1271 get_tempfile_path(refs
->tempfile
),
1273 strbuf_release(&sb
);
1274 delete_tempfile(&refs
->tempfile
);
1281 strbuf_addf(err
, "error writing to %s: %s",
1282 get_tempfile_path(refs
->tempfile
), strerror(errno
));
1286 ref_iterator_abort(iter
);
1288 delete_tempfile(&refs
->tempfile
);
1292 int is_packed_transaction_needed(struct ref_store
*ref_store
,
1293 struct ref_transaction
*transaction
)
1295 struct packed_ref_store
*refs
= packed_downcast(
1298 "is_packed_transaction_needed");
1299 struct strbuf referent
= STRBUF_INIT
;
1303 if (!is_lock_file_locked(&refs
->lock
))
1304 BUG("is_packed_transaction_needed() called while unlocked");
1307 * We're only going to bother returning false for the common,
1308 * trivial case that references are only being deleted, their
1309 * old values are not being checked, and the old `packed-refs`
1310 * file doesn't contain any of those reference(s). This gives
1311 * false positives for some other cases that could
1312 * theoretically be optimized away:
1314 * 1. It could be that the old value is being verified without
1315 * setting a new value. In this case, we could verify the
1316 * old value here and skip the update if it agrees. If it
1317 * disagrees, we could either let the update go through
1318 * (the actual commit would re-detect and report the
1319 * problem), or come up with a way of reporting such an
1320 * error to *our* caller.
1322 * 2. It could be that a new value is being set, but that it
1323 * is identical to the current packed value of the
1326 * Neither of these cases will come up in the current code,
1327 * because the only caller of this function passes to it a
1328 * transaction that only includes `delete` updates with no
1329 * `old_id`. Even if that ever changes, false positives only
1330 * cause an optimization to be missed; they do not affect
1335 * Start with the cheap checks that don't require old
1336 * reference values to be read:
1338 for (i
= 0; i
< transaction
->nr
; i
++) {
1339 struct ref_update
*update
= transaction
->updates
[i
];
1341 if (update
->flags
& REF_HAVE_OLD
)
1342 /* Have to check the old value -> needed. */
1345 if ((update
->flags
& REF_HAVE_NEW
) && !is_null_oid(&update
->new_oid
))
1346 /* Have to set a new value -> needed. */
1351 * The transaction isn't checking any old values nor is it
1352 * setting any nonzero new values, so it still might be able
1353 * to be skipped. Now do the more expensive check: the update
1354 * is needed if any of the updates is a delete, and the old
1355 * `packed-refs` file contains a value for that reference.
1358 for (i
= 0; i
< transaction
->nr
; i
++) {
1359 struct ref_update
*update
= transaction
->updates
[i
];
1362 struct object_id oid
;
1364 if (!(update
->flags
& REF_HAVE_NEW
))
1366 * This reference isn't being deleted -> not
1371 if (!refs_read_raw_ref(ref_store
, update
->refname
, &oid
,
1372 &referent
, &type
, &failure_errno
) ||
1373 failure_errno
!= ENOENT
) {
1375 * We have to actually delete that reference
1376 * -> this transaction is needed.
1383 strbuf_release(&referent
);
1387 struct packed_transaction_backend_data
{
1388 /* True iff the transaction owns the packed-refs lock. */
1391 struct string_list updates
;
1394 static void packed_transaction_cleanup(struct packed_ref_store
*refs
,
1395 struct ref_transaction
*transaction
)
1397 struct packed_transaction_backend_data
*data
= transaction
->backend_data
;
1400 string_list_clear(&data
->updates
, 0);
1402 if (is_tempfile_active(refs
->tempfile
))
1403 delete_tempfile(&refs
->tempfile
);
1405 if (data
->own_lock
&& is_lock_file_locked(&refs
->lock
)) {
1406 packed_refs_unlock(&refs
->base
);
1411 transaction
->backend_data
= NULL
;
1414 transaction
->state
= REF_TRANSACTION_CLOSED
;
1417 static int packed_transaction_prepare(struct ref_store
*ref_store
,
1418 struct ref_transaction
*transaction
,
1421 struct packed_ref_store
*refs
= packed_downcast(
1423 REF_STORE_READ
| REF_STORE_WRITE
| REF_STORE_ODB
,
1424 "ref_transaction_prepare");
1425 struct packed_transaction_backend_data
*data
;
1427 int ret
= TRANSACTION_GENERIC_ERROR
;
1430 * Note that we *don't* skip transactions with zero updates,
1431 * because such a transaction might be executed for the side
1432 * effect of ensuring that all of the references are peeled or
1433 * ensuring that the `packed-refs` file is sorted. If the
1434 * caller wants to optimize away empty transactions, it should
1438 CALLOC_ARRAY(data
, 1);
1439 string_list_init_nodup(&data
->updates
);
1441 transaction
->backend_data
= data
;
1444 * Stick the updates in a string list by refname so that we
1447 for (i
= 0; i
< transaction
->nr
; i
++) {
1448 struct ref_update
*update
= transaction
->updates
[i
];
1449 struct string_list_item
*item
=
1450 string_list_append(&data
->updates
, update
->refname
);
1452 /* Store a pointer to update in item->util: */
1453 item
->util
= update
;
1455 string_list_sort(&data
->updates
);
1457 if (ref_update_reject_duplicates(&data
->updates
, err
))
1460 if (!is_lock_file_locked(&refs
->lock
)) {
1461 if (packed_refs_lock(ref_store
, 0, err
))
1466 if (write_with_updates(refs
, &data
->updates
, err
))
1469 transaction
->state
= REF_TRANSACTION_PREPARED
;
1473 packed_transaction_cleanup(refs
, transaction
);
1477 static int packed_transaction_abort(struct ref_store
*ref_store
,
1478 struct ref_transaction
*transaction
,
1479 struct strbuf
*err UNUSED
)
1481 struct packed_ref_store
*refs
= packed_downcast(
1483 REF_STORE_READ
| REF_STORE_WRITE
| REF_STORE_ODB
,
1484 "ref_transaction_abort");
1486 packed_transaction_cleanup(refs
, transaction
);
1490 static int packed_transaction_finish(struct ref_store
*ref_store
,
1491 struct ref_transaction
*transaction
,
1494 struct packed_ref_store
*refs
= packed_downcast(
1496 REF_STORE_READ
| REF_STORE_WRITE
| REF_STORE_ODB
,
1497 "ref_transaction_finish");
1498 int ret
= TRANSACTION_GENERIC_ERROR
;
1499 char *packed_refs_path
;
1501 clear_snapshot(refs
);
1503 packed_refs_path
= get_locked_file_path(&refs
->lock
);
1504 if (rename_tempfile(&refs
->tempfile
, packed_refs_path
)) {
1505 strbuf_addf(err
, "error replacing %s: %s",
1506 refs
->path
, strerror(errno
));
1513 free(packed_refs_path
);
1514 packed_transaction_cleanup(refs
, transaction
);
1518 static int packed_initial_transaction_commit(struct ref_store
*ref_store UNUSED
,
1519 struct ref_transaction
*transaction
,
1522 return ref_transaction_commit(transaction
, err
);
1525 static int packed_delete_refs(struct ref_store
*ref_store
, const char *msg
,
1526 struct string_list
*refnames
, unsigned int flags
)
1528 struct packed_ref_store
*refs
=
1529 packed_downcast(ref_store
, REF_STORE_WRITE
, "delete_refs");
1530 struct strbuf err
= STRBUF_INIT
;
1531 struct ref_transaction
*transaction
;
1532 struct string_list_item
*item
;
1535 (void)refs
; /* We need the check above, but don't use the variable */
1541 * Since we don't check the references' old_oids, the
1542 * individual updates can't fail, so we can pack all of the
1543 * updates into a single transaction.
1546 transaction
= ref_store_transaction_begin(ref_store
, &err
);
1550 for_each_string_list_item(item
, refnames
) {
1551 if (ref_transaction_delete(transaction
, item
->string
, NULL
,
1552 flags
, msg
, &err
)) {
1553 warning(_("could not delete reference %s: %s"),
1554 item
->string
, err
.buf
);
1559 ret
= ref_transaction_commit(transaction
, &err
);
1562 if (refnames
->nr
== 1)
1563 error(_("could not delete reference %s: %s"),
1564 refnames
->items
[0].string
, err
.buf
);
1566 error(_("could not delete references: %s"), err
.buf
);
1569 ref_transaction_free(transaction
);
1570 strbuf_release(&err
);
1574 static int packed_pack_refs(struct ref_store
*ref_store UNUSED
,
1575 unsigned int flags UNUSED
)
1578 * Packed refs are already packed. It might be that loose refs
1579 * are packed *into* a packed refs store, but that is done by
1580 * updating the packed references via a transaction.
1585 static struct ref_iterator
*packed_reflog_iterator_begin(struct ref_store
*ref_store UNUSED
)
1587 return empty_ref_iterator_begin();
1590 struct ref_storage_be refs_be_packed
= {
1593 .init
= packed_ref_store_create
,
1594 .init_db
= packed_init_db
,
1595 .transaction_prepare
= packed_transaction_prepare
,
1596 .transaction_finish
= packed_transaction_finish
,
1597 .transaction_abort
= packed_transaction_abort
,
1598 .initial_transaction_commit
= packed_initial_transaction_commit
,
1600 .pack_refs
= packed_pack_refs
,
1601 .create_symref
= NULL
,
1602 .delete_refs
= packed_delete_refs
,
1606 .iterator_begin
= packed_ref_iterator_begin
,
1607 .read_raw_ref
= packed_read_raw_ref
,
1608 .read_symbolic_ref
= NULL
,
1610 .reflog_iterator_begin
= packed_reflog_iterator_begin
,
1611 .for_each_reflog_ent
= NULL
,
1612 .for_each_reflog_ent_reverse
= NULL
,
1613 .reflog_exists
= NULL
,
1614 .create_reflog
= NULL
,
1615 .delete_reflog
= NULL
,
1616 .reflog_expire
= NULL
,