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58 * `get_snapshot()` is called; if the existing snapshot is obsolete, a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 ref_store
->gitdir
= xstrdup(path
);
204 refs
->store_flags
= store_flags
;
206 refs
->path
= xstrdup(path
);
207 chdir_notify_reparent("packed-refs", &refs
->path
);
213 * Downcast `ref_store` to `packed_ref_store`. Die if `ref_store` is
214 * not a `packed_ref_store`. Also die if `packed_ref_store` doesn't
215 * support at least the flags specified in `required_flags`. `caller`
216 * is used in any necessary error messages.
218 static struct packed_ref_store
*packed_downcast(struct ref_store
*ref_store
,
219 unsigned int required_flags
,
222 struct packed_ref_store
*refs
;
224 if (ref_store
->be
!= &refs_be_packed
)
225 BUG("ref_store is type \"%s\" not \"packed\" in %s",
226 ref_store
->be
->name
, caller
);
228 refs
= (struct packed_ref_store
*)ref_store
;
230 if ((refs
->store_flags
& required_flags
) != required_flags
)
231 BUG("unallowed operation (%s), requires %x, has %x\n",
232 caller
, required_flags
, refs
->store_flags
);
237 static void clear_snapshot(struct packed_ref_store
*refs
)
239 if (refs
->snapshot
) {
240 struct snapshot
*snapshot
= refs
->snapshot
;
242 refs
->snapshot
= NULL
;
243 release_snapshot(snapshot
);
247 static NORETURN
void die_unterminated_line(const char *path
,
248 const char *p
, size_t len
)
251 die("unterminated line in %s: %.*s", path
, (int)len
, p
);
253 die("unterminated line in %s: %.75s...", path
, p
);
256 static NORETURN
void die_invalid_line(const char *path
,
257 const char *p
, size_t len
)
259 const char *eol
= memchr(p
, '\n', len
);
262 die_unterminated_line(path
, p
, len
);
263 else if (eol
- p
< 80)
264 die("unexpected line in %s: %.*s", path
, (int)(eol
- p
), p
);
266 die("unexpected line in %s: %.75s...", path
, p
);
270 struct snapshot_record
{
275 static int cmp_packed_ref_records(const void *v1
, const void *v2
)
277 const struct snapshot_record
*e1
= v1
, *e2
= v2
;
278 const char *r1
= e1
->start
+ the_hash_algo
->hexsz
+ 1;
279 const char *r2
= e2
->start
+ the_hash_algo
->hexsz
+ 1;
283 return *r2
== '\n' ? 0 : -1;
288 return (unsigned char)*r1
< (unsigned char)*r2
? -1 : +1;
296 * Compare a snapshot record at `rec` to the specified NUL-terminated
299 static int cmp_record_to_refname(const char *rec
, const char *refname
)
301 const char *r1
= rec
+ the_hash_algo
->hexsz
+ 1;
302 const char *r2
= refname
;
310 return (unsigned char)*r1
< (unsigned char)*r2
? -1 : +1;
317 * `snapshot->buf` is not known to be sorted. Check whether it is, and
318 * if not, sort it into new memory and munmap/free the old storage.
320 static void sort_snapshot(struct snapshot
*snapshot
)
322 struct snapshot_record
*records
= NULL
;
323 size_t alloc
= 0, nr
= 0;
325 const char *pos
, *eof
, *eol
;
327 char *new_buffer
, *dst
;
329 pos
= snapshot
->start
;
338 * Initialize records based on a crude estimate of the number
339 * of references in the file (we'll grow it below if needed):
341 ALLOC_GROW(records
, len
/ 80 + 20, alloc
);
344 eol
= memchr(pos
, '\n', eof
- pos
);
346 /* The safety check should prevent this. */
347 BUG("unterminated line found in packed-refs");
348 if (eol
- pos
< the_hash_algo
->hexsz
+ 2)
349 die_invalid_line(snapshot
->refs
->path
,
352 if (eol
< eof
&& *eol
== '^') {
354 * Keep any peeled line together with its
357 const char *peeled_start
= eol
;
359 eol
= memchr(peeled_start
, '\n', eof
- peeled_start
);
361 /* The safety check should prevent this. */
362 BUG("unterminated peeled line found in packed-refs");
366 ALLOC_GROW(records
, nr
+ 1, alloc
);
367 records
[nr
].start
= pos
;
368 records
[nr
].len
= eol
- pos
;
373 cmp_packed_ref_records(&records
[nr
- 2],
374 &records
[nr
- 1]) >= 0)
383 /* We need to sort the memory. First we sort the records array: */
384 QSORT(records
, nr
, cmp_packed_ref_records
);
387 * Allocate a new chunk of memory, and copy the old memory to
388 * the new in the order indicated by `records` (not bothering
389 * with the header line):
391 new_buffer
= xmalloc(len
);
392 for (dst
= new_buffer
, i
= 0; i
< nr
; i
++) {
393 memcpy(dst
, records
[i
].start
, records
[i
].len
);
394 dst
+= records
[i
].len
;
398 * Now munmap the old buffer and use the sorted buffer in its
401 clear_snapshot_buffer(snapshot
);
402 snapshot
->buf
= snapshot
->start
= new_buffer
;
403 snapshot
->eof
= new_buffer
+ len
;
410 * Return a pointer to the start of the record that contains the
411 * character `*p` (which must be within the buffer). If no other
412 * record start is found, return `buf`.
414 static const char *find_start_of_record(const char *buf
, const char *p
)
416 while (p
> buf
&& (p
[-1] != '\n' || p
[0] == '^'))
422 * Return a pointer to the start of the record following the record
423 * that contains `*p`. If none is found before `end`, return `end`.
425 static const char *find_end_of_record(const char *p
, const char *end
)
427 while (++p
< end
&& (p
[-1] != '\n' || p
[0] == '^'))
433 * We want to be able to compare mmapped reference records quickly,
434 * without totally parsing them. We can do so because the records are
435 * LF-terminated, and the refname should start exactly (GIT_SHA1_HEXSZ
436 * + 1) bytes past the beginning of the record.
438 * But what if the `packed-refs` file contains garbage? We're willing
439 * to tolerate not detecting the problem, as long as we don't produce
440 * totally garbled output (we can't afford to check the integrity of
441 * the whole file during every Git invocation). But we do want to be
442 * sure that we never read past the end of the buffer in memory and
443 * perform an illegal memory access.
445 * Guarantee that minimum level of safety by verifying that the last
446 * record in the file is LF-terminated, and that it has at least
447 * (GIT_SHA1_HEXSZ + 1) characters before the LF. Die if either of
448 * these checks fails.
450 static void verify_buffer_safe(struct snapshot
*snapshot
)
452 const char *start
= snapshot
->start
;
453 const char *eof
= snapshot
->eof
;
454 const char *last_line
;
459 last_line
= find_start_of_record(start
, eof
- 1);
460 if (*(eof
- 1) != '\n' || eof
- last_line
< the_hash_algo
->hexsz
+ 2)
461 die_invalid_line(snapshot
->refs
->path
,
462 last_line
, eof
- last_line
);
465 #define SMALL_FILE_SIZE (32*1024)
468 * Depending on `mmap_strategy`, either mmap or read the contents of
469 * the `packed-refs` file into the snapshot. Return 1 if the file
470 * existed and was read, or 0 if the file was absent or empty. Die on
473 static int load_contents(struct snapshot
*snapshot
)
480 fd
= open(snapshot
->refs
->path
, O_RDONLY
);
482 if (errno
== ENOENT
) {
484 * This is OK; it just means that no
485 * "packed-refs" file has been written yet,
486 * which is equivalent to it being empty,
487 * which is its state when initialized with
492 die_errno("couldn't read %s", snapshot
->refs
->path
);
496 stat_validity_update(&snapshot
->validity
, fd
);
498 if (fstat(fd
, &st
) < 0)
499 die_errno("couldn't stat %s", snapshot
->refs
->path
);
500 size
= xsize_t(st
.st_size
);
505 } else if (mmap_strategy
== MMAP_NONE
|| size
<= SMALL_FILE_SIZE
) {
506 snapshot
->buf
= xmalloc(size
);
507 bytes_read
= read_in_full(fd
, snapshot
->buf
, size
);
508 if (bytes_read
< 0 || bytes_read
!= size
)
509 die_errno("couldn't read %s", snapshot
->refs
->path
);
510 snapshot
->mmapped
= 0;
512 snapshot
->buf
= xmmap(NULL
, size
, PROT_READ
, MAP_PRIVATE
, fd
, 0);
513 snapshot
->mmapped
= 1;
517 snapshot
->start
= snapshot
->buf
;
518 snapshot
->eof
= snapshot
->buf
+ size
;
524 * Find the place in `snapshot->buf` where the start of the record for
525 * `refname` starts. If `mustexist` is true and the reference doesn't
526 * exist, then return NULL. If `mustexist` is false and the reference
527 * doesn't exist, then return the point where that reference would be
528 * inserted, or `snapshot->eof` (which might be NULL) if it would be
529 * inserted at the end of the file. In the latter mode, `refname`
530 * doesn't have to be a proper reference name; for example, one could
531 * search for "refs/replace/" to find the start of any replace
534 * The record is sought using a binary search, so `snapshot->buf` must
537 static const char *find_reference_location(struct snapshot
*snapshot
,
538 const char *refname
, int mustexist
)
541 * This is not *quite* a garden-variety binary search, because
542 * the data we're searching is made up of records, and we
543 * always need to find the beginning of a record to do a
544 * comparison. A "record" here is one line for the reference
545 * itself and zero or one peel lines that start with '^'. Our
546 * loop invariant is described in the next two comments.
550 * A pointer to the character at the start of a record whose
551 * preceding records all have reference names that come
552 * *before* `refname`.
554 const char *lo
= snapshot
->start
;
557 * A pointer to a the first character of a record whose
558 * reference name comes *after* `refname`.
560 const char *hi
= snapshot
->eof
;
563 const char *mid
, *rec
;
566 mid
= lo
+ (hi
- lo
) / 2;
567 rec
= find_start_of_record(lo
, mid
);
568 cmp
= cmp_record_to_refname(rec
, refname
);
570 lo
= find_end_of_record(mid
, hi
);
571 } else if (cmp
> 0) {
585 * Create a newly-allocated `snapshot` of the `packed-refs` file in
586 * its current state and return it. The return value will already have
587 * its reference count incremented.
589 * A comment line of the form "# pack-refs with: " may contain zero or
590 * more traits. We interpret the traits as follows:
592 * Neither `peeled` nor `fully-peeled`:
594 * Probably no references are peeled. But if the file contains a
595 * peeled value for a reference, we will use it.
599 * References under "refs/tags/", if they *can* be peeled, *are*
600 * peeled in this file. References outside of "refs/tags/" are
601 * probably not peeled even if they could have been, but if we find
602 * a peeled value for such a reference we will use it.
606 * All references in the file that can be peeled are peeled.
607 * Inversely (and this is more important), any references in the
608 * file for which no peeled value is recorded is not peelable. This
609 * trait should typically be written alongside "peeled" for
610 * compatibility with older clients, but we do not require it
611 * (i.e., "peeled" is a no-op if "fully-peeled" is set).
615 * The references in this file are known to be sorted by refname.
617 static struct snapshot
*create_snapshot(struct packed_ref_store
*refs
)
619 struct snapshot
*snapshot
= xcalloc(1, sizeof(*snapshot
));
622 snapshot
->refs
= refs
;
623 acquire_snapshot(snapshot
);
624 snapshot
->peeled
= PEELED_NONE
;
626 if (!load_contents(snapshot
))
629 /* If the file has a header line, process it: */
630 if (snapshot
->buf
< snapshot
->eof
&& *snapshot
->buf
== '#') {
632 struct string_list traits
= STRING_LIST_INIT_NODUP
;
634 eol
= memchr(snapshot
->buf
, '\n',
635 snapshot
->eof
- snapshot
->buf
);
637 die_unterminated_line(refs
->path
,
639 snapshot
->eof
- snapshot
->buf
);
641 tmp
= xmemdupz(snapshot
->buf
, eol
- snapshot
->buf
);
643 if (!skip_prefix(tmp
, "# pack-refs with:", (const char **)&p
))
644 die_invalid_line(refs
->path
,
646 snapshot
->eof
- snapshot
->buf
);
648 string_list_split_in_place(&traits
, p
, ' ', -1);
650 if (unsorted_string_list_has_string(&traits
, "fully-peeled"))
651 snapshot
->peeled
= PEELED_FULLY
;
652 else if (unsorted_string_list_has_string(&traits
, "peeled"))
653 snapshot
->peeled
= PEELED_TAGS
;
655 sorted
= unsorted_string_list_has_string(&traits
, "sorted");
657 /* perhaps other traits later as well */
659 /* The "+ 1" is for the LF character. */
660 snapshot
->start
= eol
+ 1;
662 string_list_clear(&traits
, 0);
666 verify_buffer_safe(snapshot
);
669 sort_snapshot(snapshot
);
672 * Reordering the records might have moved a short one
673 * to the end of the buffer, so verify the buffer's
676 verify_buffer_safe(snapshot
);
679 if (mmap_strategy
!= MMAP_OK
&& snapshot
->mmapped
) {
681 * We don't want to leave the file mmapped, so we are
682 * forced to make a copy now:
684 size_t size
= snapshot
->eof
- snapshot
->start
;
685 char *buf_copy
= xmalloc(size
);
687 memcpy(buf_copy
, snapshot
->start
, size
);
688 clear_snapshot_buffer(snapshot
);
689 snapshot
->buf
= snapshot
->start
= buf_copy
;
690 snapshot
->eof
= buf_copy
+ size
;
697 * Check that `refs->snapshot` (if present) still reflects the
698 * contents of the `packed-refs` file. If not, clear the snapshot.
700 static void validate_snapshot(struct packed_ref_store
*refs
)
702 if (refs
->snapshot
&&
703 !stat_validity_check(&refs
->snapshot
->validity
, refs
->path
))
704 clear_snapshot(refs
);
708 * Get the `snapshot` for the specified packed_ref_store, creating and
709 * populating it if it hasn't been read before or if the file has been
710 * changed (according to its `validity` field) since it was last read.
711 * On the other hand, if we hold the lock, then assume that the file
712 * hasn't been changed out from under us, so skip the extra `stat()`
713 * call in `stat_validity_check()`. This function does *not* increase
714 * the snapshot's reference count on behalf of the caller.
716 static struct snapshot
*get_snapshot(struct packed_ref_store
*refs
)
718 if (!is_lock_file_locked(&refs
->lock
))
719 validate_snapshot(refs
);
722 refs
->snapshot
= create_snapshot(refs
);
724 return refs
->snapshot
;
727 static int packed_read_raw_ref(struct ref_store
*ref_store
,
728 const char *refname
, struct object_id
*oid
,
729 struct strbuf
*referent
, unsigned int *type
)
731 struct packed_ref_store
*refs
=
732 packed_downcast(ref_store
, REF_STORE_READ
, "read_raw_ref");
733 struct snapshot
*snapshot
= get_snapshot(refs
);
738 rec
= find_reference_location(snapshot
, refname
, 1);
741 /* refname is not a packed reference. */
746 if (get_oid_hex(rec
, oid
))
747 die_invalid_line(refs
->path
, rec
, snapshot
->eof
- rec
);
749 *type
= REF_ISPACKED
;
754 * This value is set in `base.flags` if the peeled value of the
755 * current reference is known. In that case, `peeled` contains the
756 * correct peeled value for the reference, which might be `null_oid`
757 * if the reference is not a tag or if it is broken.
759 #define REF_KNOWS_PEELED 0x40
762 * An iterator over a snapshot of a `packed-refs` file.
764 struct packed_ref_iterator
{
765 struct ref_iterator base
;
767 struct snapshot
*snapshot
;
769 /* The current position in the snapshot's buffer: */
772 /* The end of the part of the buffer that will be iterated over: */
775 /* Scratch space for current values: */
776 struct object_id oid
, peeled
;
777 struct strbuf refname_buf
;
783 * Move the iterator to the next record in the snapshot, without
784 * respect for whether the record is actually required by the current
785 * iteration. Adjust the fields in `iter` and return `ITER_OK` or
786 * `ITER_DONE`. This function does not free the iterator in the case
789 static int next_record(struct packed_ref_iterator
*iter
)
791 const char *p
= iter
->pos
, *eol
;
793 strbuf_reset(&iter
->refname_buf
);
795 if (iter
->pos
== iter
->eof
)
798 iter
->base
.flags
= REF_ISPACKED
;
800 if (iter
->eof
- p
< the_hash_algo
->hexsz
+ 2 ||
801 parse_oid_hex(p
, &iter
->oid
, &p
) ||
803 die_invalid_line(iter
->snapshot
->refs
->path
,
804 iter
->pos
, iter
->eof
- iter
->pos
);
806 eol
= memchr(p
, '\n', iter
->eof
- p
);
808 die_unterminated_line(iter
->snapshot
->refs
->path
,
809 iter
->pos
, iter
->eof
- iter
->pos
);
811 strbuf_add(&iter
->refname_buf
, p
, eol
- p
);
812 iter
->base
.refname
= iter
->refname_buf
.buf
;
814 if (check_refname_format(iter
->base
.refname
, REFNAME_ALLOW_ONELEVEL
)) {
815 if (!refname_is_safe(iter
->base
.refname
))
816 die("packed refname is dangerous: %s",
819 iter
->base
.flags
|= REF_BAD_NAME
| REF_ISBROKEN
;
821 if (iter
->snapshot
->peeled
== PEELED_FULLY
||
822 (iter
->snapshot
->peeled
== PEELED_TAGS
&&
823 starts_with(iter
->base
.refname
, "refs/tags/")))
824 iter
->base
.flags
|= REF_KNOWS_PEELED
;
828 if (iter
->pos
< iter
->eof
&& *iter
->pos
== '^') {
830 if (iter
->eof
- p
< the_hash_algo
->hexsz
+ 1 ||
831 parse_oid_hex(p
, &iter
->peeled
, &p
) ||
833 die_invalid_line(iter
->snapshot
->refs
->path
,
834 iter
->pos
, iter
->eof
- iter
->pos
);
838 * Regardless of what the file header said, we
839 * definitely know the value of *this* reference. But
840 * we suppress it if the reference is broken:
842 if ((iter
->base
.flags
& REF_ISBROKEN
)) {
843 oidclr(&iter
->peeled
);
844 iter
->base
.flags
&= ~REF_KNOWS_PEELED
;
846 iter
->base
.flags
|= REF_KNOWS_PEELED
;
849 oidclr(&iter
->peeled
);
855 static int packed_ref_iterator_advance(struct ref_iterator
*ref_iterator
)
857 struct packed_ref_iterator
*iter
=
858 (struct packed_ref_iterator
*)ref_iterator
;
861 while ((ok
= next_record(iter
)) == ITER_OK
) {
862 if (iter
->flags
& DO_FOR_EACH_PER_WORKTREE_ONLY
&&
863 ref_type(iter
->base
.refname
) != REF_TYPE_PER_WORKTREE
)
866 if (!(iter
->flags
& DO_FOR_EACH_INCLUDE_BROKEN
) &&
867 !ref_resolves_to_object(iter
->base
.refname
, &iter
->oid
,
874 if (ref_iterator_abort(ref_iterator
) != ITER_DONE
)
880 static int packed_ref_iterator_peel(struct ref_iterator
*ref_iterator
,
881 struct object_id
*peeled
)
883 struct packed_ref_iterator
*iter
=
884 (struct packed_ref_iterator
*)ref_iterator
;
886 if ((iter
->base
.flags
& REF_KNOWS_PEELED
)) {
887 oidcpy(peeled
, &iter
->peeled
);
888 return is_null_oid(&iter
->peeled
) ? -1 : 0;
889 } else if ((iter
->base
.flags
& (REF_ISBROKEN
| REF_ISSYMREF
))) {
892 return !!peel_object(&iter
->oid
, peeled
);
896 static int packed_ref_iterator_abort(struct ref_iterator
*ref_iterator
)
898 struct packed_ref_iterator
*iter
=
899 (struct packed_ref_iterator
*)ref_iterator
;
902 strbuf_release(&iter
->refname_buf
);
903 release_snapshot(iter
->snapshot
);
904 base_ref_iterator_free(ref_iterator
);
908 static struct ref_iterator_vtable packed_ref_iterator_vtable
= {
909 packed_ref_iterator_advance
,
910 packed_ref_iterator_peel
,
911 packed_ref_iterator_abort
914 static struct ref_iterator
*packed_ref_iterator_begin(
915 struct ref_store
*ref_store
,
916 const char *prefix
, unsigned int flags
)
918 struct packed_ref_store
*refs
;
919 struct snapshot
*snapshot
;
921 struct packed_ref_iterator
*iter
;
922 struct ref_iterator
*ref_iterator
;
923 unsigned int required_flags
= REF_STORE_READ
;
925 if (!(flags
& DO_FOR_EACH_INCLUDE_BROKEN
))
926 required_flags
|= REF_STORE_ODB
;
927 refs
= packed_downcast(ref_store
, required_flags
, "ref_iterator_begin");
930 * Note that `get_snapshot()` internally checks whether the
931 * snapshot is up to date with what is on disk, and re-reads
934 snapshot
= get_snapshot(refs
);
936 if (prefix
&& *prefix
)
937 start
= find_reference_location(snapshot
, prefix
, 0);
939 start
= snapshot
->start
;
941 if (start
== snapshot
->eof
)
942 return empty_ref_iterator_begin();
944 iter
= xcalloc(1, sizeof(*iter
));
945 ref_iterator
= &iter
->base
;
946 base_ref_iterator_init(ref_iterator
, &packed_ref_iterator_vtable
, 1);
948 iter
->snapshot
= snapshot
;
949 acquire_snapshot(snapshot
);
952 iter
->eof
= snapshot
->eof
;
953 strbuf_init(&iter
->refname_buf
, 0);
955 iter
->base
.oid
= &iter
->oid
;
959 if (prefix
&& *prefix
)
960 /* Stop iteration after we've gone *past* prefix: */
961 ref_iterator
= prefix_ref_iterator_begin(ref_iterator
, prefix
, 0);
967 * Write an entry to the packed-refs file for the specified refname.
968 * If peeled is non-NULL, write it as the entry's peeled value. On
969 * error, return a nonzero value and leave errno set at the value left
970 * by the failing call to `fprintf()`.
972 static int write_packed_entry(FILE *fh
, const char *refname
,
973 const struct object_id
*oid
,
974 const struct object_id
*peeled
)
976 if (fprintf(fh
, "%s %s\n", oid_to_hex(oid
), refname
) < 0 ||
977 (peeled
&& fprintf(fh
, "^%s\n", oid_to_hex(peeled
)) < 0))
983 int packed_refs_lock(struct ref_store
*ref_store
, int flags
, struct strbuf
*err
)
985 struct packed_ref_store
*refs
=
986 packed_downcast(ref_store
, REF_STORE_WRITE
| REF_STORE_MAIN
,
988 static int timeout_configured
= 0;
989 static int timeout_value
= 1000;
991 if (!timeout_configured
) {
992 git_config_get_int("core.packedrefstimeout", &timeout_value
);
993 timeout_configured
= 1;
997 * Note that we close the lockfile immediately because we
998 * don't write new content to it, but rather to a separate
1001 if (hold_lock_file_for_update_timeout(
1004 flags
, timeout_value
) < 0) {
1005 unable_to_lock_message(refs
->path
, errno
, err
);
1009 if (close_lock_file_gently(&refs
->lock
)) {
1010 strbuf_addf(err
, "unable to close %s: %s", refs
->path
, strerror(errno
));
1011 rollback_lock_file(&refs
->lock
);
1016 * There is a stat-validity problem might cause `update-ref -d`
1017 * lost the newly commit of a ref, because a new `packed-refs`
1018 * file might has the same on-disk file attributes such as
1019 * timestamp, file size and inode value, but has a changed
1022 * This could happen with a very small chance when
1023 * `update-ref -d` is called and at the same time another
1024 * `pack-refs --all` process is running.
1026 * Now that we hold the `packed-refs` lock, it is important
1027 * to make sure we could read the latest version of
1028 * `packed-refs` file no matter we have just mmap it or not.
1029 * So what need to do is clear the snapshot if we hold it
1032 clear_snapshot(refs
);
1035 * Now make sure that the packed-refs file as it exists in the
1036 * locked state is loaded into the snapshot:
1042 void packed_refs_unlock(struct ref_store
*ref_store
)
1044 struct packed_ref_store
*refs
= packed_downcast(
1046 REF_STORE_READ
| REF_STORE_WRITE
,
1047 "packed_refs_unlock");
1049 if (!is_lock_file_locked(&refs
->lock
))
1050 BUG("packed_refs_unlock() called when not locked");
1051 rollback_lock_file(&refs
->lock
);
1054 int packed_refs_is_locked(struct ref_store
*ref_store
)
1056 struct packed_ref_store
*refs
= packed_downcast(
1058 REF_STORE_READ
| REF_STORE_WRITE
,
1059 "packed_refs_is_locked");
1061 return is_lock_file_locked(&refs
->lock
);
1065 * The packed-refs header line that we write out. Perhaps other traits
1066 * will be added later.
1068 * Note that earlier versions of Git used to parse these traits by
1069 * looking for " trait " in the line. For this reason, the space after
1070 * the colon and the trailing space are required.
1072 static const char PACKED_REFS_HEADER
[] =
1073 "# pack-refs with: peeled fully-peeled sorted \n";
1075 static int packed_init_db(struct ref_store
*ref_store
, struct strbuf
*err
)
1077 /* Nothing to do. */
1082 * Write the packed refs from the current snapshot to the packed-refs
1083 * tempfile, incorporating any changes from `updates`. `updates` must
1084 * be a sorted string list whose keys are the refnames and whose util
1085 * values are `struct ref_update *`. On error, rollback the tempfile,
1086 * write an error message to `err`, and return a nonzero value.
1088 * The packfile must be locked before calling this function and will
1089 * remain locked when it is done.
1091 static int write_with_updates(struct packed_ref_store
*refs
,
1092 struct string_list
*updates
,
1095 struct ref_iterator
*iter
= NULL
;
1099 struct strbuf sb
= STRBUF_INIT
;
1100 char *packed_refs_path
;
1102 if (!is_lock_file_locked(&refs
->lock
))
1103 BUG("write_with_updates() called while unlocked");
1106 * If packed-refs is a symlink, we want to overwrite the
1107 * symlinked-to file, not the symlink itself. Also, put the
1108 * staging file next to it:
1110 packed_refs_path
= get_locked_file_path(&refs
->lock
);
1111 strbuf_addf(&sb
, "%s.new", packed_refs_path
);
1112 free(packed_refs_path
);
1113 refs
->tempfile
= create_tempfile(sb
.buf
);
1114 if (!refs
->tempfile
) {
1115 strbuf_addf(err
, "unable to create file %s: %s",
1116 sb
.buf
, strerror(errno
));
1117 strbuf_release(&sb
);
1120 strbuf_release(&sb
);
1122 out
= fdopen_tempfile(refs
->tempfile
, "w");
1124 strbuf_addf(err
, "unable to fdopen packed-refs tempfile: %s",
1129 if (fprintf(out
, "%s", PACKED_REFS_HEADER
) < 0)
1133 * We iterate in parallel through the current list of refs and
1134 * the list of updates, processing an entry from at least one
1135 * of the lists each time through the loop. When the current
1136 * list of refs is exhausted, set iter to NULL. When the list
1137 * of updates is exhausted, leave i set to updates->nr.
1139 iter
= packed_ref_iterator_begin(&refs
->base
, "",
1140 DO_FOR_EACH_INCLUDE_BROKEN
);
1141 if ((ok
= ref_iterator_advance(iter
)) != ITER_OK
)
1146 while (iter
|| i
< updates
->nr
) {
1147 struct ref_update
*update
= NULL
;
1150 if (i
>= updates
->nr
) {
1153 update
= updates
->items
[i
].util
;
1158 cmp
= strcmp(iter
->refname
, update
->refname
);
1163 * There is both an old value and an update
1164 * for this reference. Check the old value if
1167 if ((update
->flags
& REF_HAVE_OLD
)) {
1168 if (is_null_oid(&update
->old_oid
)) {
1169 strbuf_addf(err
, "cannot update ref '%s': "
1170 "reference already exists",
1173 } else if (!oideq(&update
->old_oid
, iter
->oid
)) {
1174 strbuf_addf(err
, "cannot update ref '%s': "
1175 "is at %s but expected %s",
1177 oid_to_hex(iter
->oid
),
1178 oid_to_hex(&update
->old_oid
));
1183 /* Now figure out what to use for the new value: */
1184 if ((update
->flags
& REF_HAVE_NEW
)) {
1186 * The update takes precedence. Skip
1187 * the iterator over the unneeded
1190 if ((ok
= ref_iterator_advance(iter
)) != ITER_OK
)
1195 * The update doesn't actually want to
1196 * change anything. We're done with it.
1201 } else if (cmp
> 0) {
1203 * There is no old value but there is an
1204 * update for this reference. Make sure that
1205 * the update didn't expect an existing value:
1207 if ((update
->flags
& REF_HAVE_OLD
) &&
1208 !is_null_oid(&update
->old_oid
)) {
1209 strbuf_addf(err
, "cannot update ref '%s': "
1210 "reference is missing but expected %s",
1212 oid_to_hex(&update
->old_oid
));
1218 /* Pass the old reference through. */
1220 struct object_id peeled
;
1221 int peel_error
= ref_iterator_peel(iter
, &peeled
);
1223 if (write_packed_entry(out
, iter
->refname
,
1225 peel_error
? NULL
: &peeled
))
1228 if ((ok
= ref_iterator_advance(iter
)) != ITER_OK
)
1230 } else if (is_null_oid(&update
->new_oid
)) {
1232 * The update wants to delete the reference,
1233 * and the reference either didn't exist or we
1234 * have already skipped it. So we're done with
1235 * the update (and don't have to write
1240 struct object_id peeled
;
1241 int peel_error
= peel_object(&update
->new_oid
,
1244 if (write_packed_entry(out
, update
->refname
,
1246 peel_error
? NULL
: &peeled
))
1253 if (ok
!= ITER_DONE
) {
1254 strbuf_addstr(err
, "unable to write packed-refs file: "
1255 "error iterating over old contents");
1259 if (close_tempfile_gently(refs
->tempfile
)) {
1260 strbuf_addf(err
, "error closing file %s: %s",
1261 get_tempfile_path(refs
->tempfile
),
1263 strbuf_release(&sb
);
1264 delete_tempfile(&refs
->tempfile
);
1271 strbuf_addf(err
, "error writing to %s: %s",
1272 get_tempfile_path(refs
->tempfile
), strerror(errno
));
1276 ref_iterator_abort(iter
);
1278 delete_tempfile(&refs
->tempfile
);
1282 int is_packed_transaction_needed(struct ref_store
*ref_store
,
1283 struct ref_transaction
*transaction
)
1285 struct packed_ref_store
*refs
= packed_downcast(
1288 "is_packed_transaction_needed");
1289 struct strbuf referent
= STRBUF_INIT
;
1293 if (!is_lock_file_locked(&refs
->lock
))
1294 BUG("is_packed_transaction_needed() called while unlocked");
1297 * We're only going to bother returning false for the common,
1298 * trivial case that references are only being deleted, their
1299 * old values are not being checked, and the old `packed-refs`
1300 * file doesn't contain any of those reference(s). This gives
1301 * false positives for some other cases that could
1302 * theoretically be optimized away:
1304 * 1. It could be that the old value is being verified without
1305 * setting a new value. In this case, we could verify the
1306 * old value here and skip the update if it agrees. If it
1307 * disagrees, we could either let the update go through
1308 * (the actual commit would re-detect and report the
1309 * problem), or come up with a way of reporting such an
1310 * error to *our* caller.
1312 * 2. It could be that a new value is being set, but that it
1313 * is identical to the current packed value of the
1316 * Neither of these cases will come up in the current code,
1317 * because the only caller of this function passes to it a
1318 * transaction that only includes `delete` updates with no
1319 * `old_id`. Even if that ever changes, false positives only
1320 * cause an optimization to be missed; they do not affect
1325 * Start with the cheap checks that don't require old
1326 * reference values to be read:
1328 for (i
= 0; i
< transaction
->nr
; i
++) {
1329 struct ref_update
*update
= transaction
->updates
[i
];
1331 if (update
->flags
& REF_HAVE_OLD
)
1332 /* Have to check the old value -> needed. */
1335 if ((update
->flags
& REF_HAVE_NEW
) && !is_null_oid(&update
->new_oid
))
1336 /* Have to set a new value -> needed. */
1341 * The transaction isn't checking any old values nor is it
1342 * setting any nonzero new values, so it still might be able
1343 * to be skipped. Now do the more expensive check: the update
1344 * is needed if any of the updates is a delete, and the old
1345 * `packed-refs` file contains a value for that reference.
1348 for (i
= 0; i
< transaction
->nr
; i
++) {
1349 struct ref_update
*update
= transaction
->updates
[i
];
1351 struct object_id oid
;
1353 if (!(update
->flags
& REF_HAVE_NEW
))
1355 * This reference isn't being deleted -> not
1360 if (!refs_read_raw_ref(ref_store
, update
->refname
,
1361 &oid
, &referent
, &type
) ||
1364 * We have to actually delete that reference
1365 * -> this transaction is needed.
1372 strbuf_release(&referent
);
1376 struct packed_transaction_backend_data
{
1377 /* True iff the transaction owns the packed-refs lock. */
1380 struct string_list updates
;
1383 static void packed_transaction_cleanup(struct packed_ref_store
*refs
,
1384 struct ref_transaction
*transaction
)
1386 struct packed_transaction_backend_data
*data
= transaction
->backend_data
;
1389 string_list_clear(&data
->updates
, 0);
1391 if (is_tempfile_active(refs
->tempfile
))
1392 delete_tempfile(&refs
->tempfile
);
1394 if (data
->own_lock
&& is_lock_file_locked(&refs
->lock
)) {
1395 packed_refs_unlock(&refs
->base
);
1400 transaction
->backend_data
= NULL
;
1403 transaction
->state
= REF_TRANSACTION_CLOSED
;
1406 static int packed_transaction_prepare(struct ref_store
*ref_store
,
1407 struct ref_transaction
*transaction
,
1410 struct packed_ref_store
*refs
= packed_downcast(
1412 REF_STORE_READ
| REF_STORE_WRITE
| REF_STORE_ODB
,
1413 "ref_transaction_prepare");
1414 struct packed_transaction_backend_data
*data
;
1416 int ret
= TRANSACTION_GENERIC_ERROR
;
1419 * Note that we *don't* skip transactions with zero updates,
1420 * because such a transaction might be executed for the side
1421 * effect of ensuring that all of the references are peeled or
1422 * ensuring that the `packed-refs` file is sorted. If the
1423 * caller wants to optimize away empty transactions, it should
1427 data
= xcalloc(1, sizeof(*data
));
1428 string_list_init(&data
->updates
, 0);
1430 transaction
->backend_data
= data
;
1433 * Stick the updates in a string list by refname so that we
1436 for (i
= 0; i
< transaction
->nr
; i
++) {
1437 struct ref_update
*update
= transaction
->updates
[i
];
1438 struct string_list_item
*item
=
1439 string_list_append(&data
->updates
, update
->refname
);
1441 /* Store a pointer to update in item->util: */
1442 item
->util
= update
;
1444 string_list_sort(&data
->updates
);
1446 if (ref_update_reject_duplicates(&data
->updates
, err
))
1449 if (!is_lock_file_locked(&refs
->lock
)) {
1450 if (packed_refs_lock(ref_store
, 0, err
))
1455 if (write_with_updates(refs
, &data
->updates
, err
))
1458 transaction
->state
= REF_TRANSACTION_PREPARED
;
1462 packed_transaction_cleanup(refs
, transaction
);
1466 static int packed_transaction_abort(struct ref_store
*ref_store
,
1467 struct ref_transaction
*transaction
,
1470 struct packed_ref_store
*refs
= packed_downcast(
1472 REF_STORE_READ
| REF_STORE_WRITE
| REF_STORE_ODB
,
1473 "ref_transaction_abort");
1475 packed_transaction_cleanup(refs
, transaction
);
1479 static int packed_transaction_finish(struct ref_store
*ref_store
,
1480 struct ref_transaction
*transaction
,
1483 struct packed_ref_store
*refs
= packed_downcast(
1485 REF_STORE_READ
| REF_STORE_WRITE
| REF_STORE_ODB
,
1486 "ref_transaction_finish");
1487 int ret
= TRANSACTION_GENERIC_ERROR
;
1488 char *packed_refs_path
;
1490 clear_snapshot(refs
);
1492 packed_refs_path
= get_locked_file_path(&refs
->lock
);
1493 if (rename_tempfile(&refs
->tempfile
, packed_refs_path
)) {
1494 strbuf_addf(err
, "error replacing %s: %s",
1495 refs
->path
, strerror(errno
));
1502 free(packed_refs_path
);
1503 packed_transaction_cleanup(refs
, transaction
);
1507 static int packed_initial_transaction_commit(struct ref_store
*ref_store
,
1508 struct ref_transaction
*transaction
,
1511 return ref_transaction_commit(transaction
, err
);
1514 static int packed_delete_refs(struct ref_store
*ref_store
, const char *msg
,
1515 struct string_list
*refnames
, unsigned int flags
)
1517 struct packed_ref_store
*refs
=
1518 packed_downcast(ref_store
, REF_STORE_WRITE
, "delete_refs");
1519 struct strbuf err
= STRBUF_INIT
;
1520 struct ref_transaction
*transaction
;
1521 struct string_list_item
*item
;
1524 (void)refs
; /* We need the check above, but don't use the variable */
1530 * Since we don't check the references' old_oids, the
1531 * individual updates can't fail, so we can pack all of the
1532 * updates into a single transaction.
1535 transaction
= ref_store_transaction_begin(ref_store
, &err
);
1539 for_each_string_list_item(item
, refnames
) {
1540 if (ref_transaction_delete(transaction
, item
->string
, NULL
,
1541 flags
, msg
, &err
)) {
1542 warning(_("could not delete reference %s: %s"),
1543 item
->string
, err
.buf
);
1548 ret
= ref_transaction_commit(transaction
, &err
);
1551 if (refnames
->nr
== 1)
1552 error(_("could not delete reference %s: %s"),
1553 refnames
->items
[0].string
, err
.buf
);
1555 error(_("could not delete references: %s"), err
.buf
);
1558 ref_transaction_free(transaction
);
1559 strbuf_release(&err
);
1563 static int packed_pack_refs(struct ref_store
*ref_store
, unsigned int flags
)
1566 * Packed refs are already packed. It might be that loose refs
1567 * are packed *into* a packed refs store, but that is done by
1568 * updating the packed references via a transaction.
1573 static int packed_create_symref(struct ref_store
*ref_store
,
1574 const char *refname
, const char *target
,
1577 BUG("packed reference store does not support symrefs");
1580 static int packed_rename_ref(struct ref_store
*ref_store
,
1581 const char *oldrefname
, const char *newrefname
,
1584 BUG("packed reference store does not support renaming references");
1587 static int packed_copy_ref(struct ref_store
*ref_store
,
1588 const char *oldrefname
, const char *newrefname
,
1591 BUG("packed reference store does not support copying references");
1594 static struct ref_iterator
*packed_reflog_iterator_begin(struct ref_store
*ref_store
)
1596 return empty_ref_iterator_begin();
1599 static int packed_for_each_reflog_ent(struct ref_store
*ref_store
,
1600 const char *refname
,
1601 each_reflog_ent_fn fn
, void *cb_data
)
1606 static int packed_for_each_reflog_ent_reverse(struct ref_store
*ref_store
,
1607 const char *refname
,
1608 each_reflog_ent_fn fn
,
1614 static int packed_reflog_exists(struct ref_store
*ref_store
,
1615 const char *refname
)
1620 static int packed_create_reflog(struct ref_store
*ref_store
,
1621 const char *refname
, int force_create
,
1624 BUG("packed reference store does not support reflogs");
1627 static int packed_delete_reflog(struct ref_store
*ref_store
,
1628 const char *refname
)
1633 static int packed_reflog_expire(struct ref_store
*ref_store
,
1634 const char *refname
, const struct object_id
*oid
,
1636 reflog_expiry_prepare_fn prepare_fn
,
1637 reflog_expiry_should_prune_fn should_prune_fn
,
1638 reflog_expiry_cleanup_fn cleanup_fn
,
1639 void *policy_cb_data
)
1644 struct ref_storage_be refs_be_packed
= {
1647 packed_ref_store_create
,
1649 packed_transaction_prepare
,
1650 packed_transaction_finish
,
1651 packed_transaction_abort
,
1652 packed_initial_transaction_commit
,
1655 packed_create_symref
,
1660 packed_ref_iterator_begin
,
1661 packed_read_raw_ref
,
1663 packed_reflog_iterator_begin
,
1664 packed_for_each_reflog_ent
,
1665 packed_for_each_reflog_ent_reverse
,
1666 packed_reflog_exists
,
1667 packed_create_reflog
,
1668 packed_delete_reflog
,
1669 packed_reflog_expire