4 #include "../gettext.h"
8 #include "refs-internal.h"
9 #include "packed-backend.h"
10 #include "../iterator.h"
11 #include "../lockfile.h"
12 #include "../chdir-notify.h"
13 #include "../wrapper.h"
14 #include "../write-or-die.h"
18 * Don't use mmap() at all for reading `packed-refs`.
23 * Can use mmap() for reading `packed-refs`, but the file must
24 * not remain mmapped. This is the usual option on Windows,
25 * where you cannot rename a new version of a file onto a file
26 * that is currently mmapped.
31 * It is OK to leave the `packed-refs` file mmapped while
32 * arbitrary other code is running.
38 static enum mmap_strategy mmap_strategy
= MMAP_NONE
;
39 #elif defined(MMAP_PREVENTS_DELETE)
40 static enum mmap_strategy mmap_strategy
= MMAP_TEMPORARY
;
42 static enum mmap_strategy mmap_strategy
= MMAP_OK
;
45 struct packed_ref_store
;
48 * A `snapshot` represents one snapshot of a `packed-refs` file.
50 * Normally, this will be a mmapped view of the contents of the
51 * `packed-refs` file at the time the snapshot was created. However,
52 * if the `packed-refs` file was not sorted, this might point at heap
53 * memory holding the contents of the `packed-refs` file with its
54 * records sorted by refname.
56 * `snapshot` instances are reference counted (via
57 * `acquire_snapshot()` and `release_snapshot()`). This is to prevent
58 * an instance from disappearing while an iterator is still iterating
59 * over it. Instances are garbage collected when their `referrers`
62 * The most recent `snapshot`, if available, is referenced by the
63 * `packed_ref_store`. Its freshness is checked whenever
64 * `get_snapshot()` is called; if the existing snapshot is obsolete, a
65 * new snapshot is taken.
69 * A back-pointer to the packed_ref_store with which this
70 * snapshot is associated:
72 struct packed_ref_store
*refs
;
74 /* Is the `packed-refs` file currently mmapped? */
78 * The contents of the `packed-refs` file:
80 * - buf -- a pointer to the start of the memory
81 * - start -- a pointer to the first byte of actual references
82 * (i.e., after the header line, if one is present)
83 * - eof -- a pointer just past the end of the reference
86 * If the `packed-refs` file was already sorted, `buf` points
87 * at the mmapped contents of the file. If not, it points at
88 * heap-allocated memory containing the contents, sorted. If
89 * there were no contents (e.g., because the file didn't
90 * exist), `buf`, `start`, and `eof` are all NULL.
92 char *buf
, *start
, *eof
;
95 * What is the peeled state of the `packed-refs` file that
96 * this snapshot represents? (This is usually determined from
99 enum { PEELED_NONE
, PEELED_TAGS
, PEELED_FULLY
} peeled
;
102 * Count of references to this instance, including the pointer
103 * from `packed_ref_store::snapshot`, if any. The instance
104 * will not be freed as long as the reference count is
107 unsigned int referrers
;
110 * The metadata of the `packed-refs` file from which this
111 * snapshot was created, used to tell if the file has been
112 * replaced since we read it.
114 struct stat_validity validity
;
118 * A `ref_store` representing references stored in a `packed-refs`
119 * file. It implements the `ref_store` interface, though it has some
122 * - It cannot store symbolic references.
124 * - It cannot store reflogs.
126 * - It does not support reference renaming (though it could).
128 * On the other hand, it can be locked outside of a reference
129 * transaction. In that case, it remains locked even after the
130 * transaction is done and the new `packed-refs` file is activated.
132 struct packed_ref_store
{
133 struct ref_store base
;
135 unsigned int store_flags
;
137 /* The path of the "packed-refs" file: */
141 * A snapshot of the values read from the `packed-refs` file,
142 * if it might still be current; otherwise, NULL.
144 struct snapshot
*snapshot
;
147 * Lock used for the "packed-refs" file. Note that this (and
148 * thus the enclosing `packed_ref_store`) must not be freed.
150 struct lock_file lock
;
153 * Temporary file used when rewriting new contents to the
154 * "packed-refs" file. Note that this (and thus the enclosing
155 * `packed_ref_store`) must not be freed.
157 struct tempfile
*tempfile
;
161 * Increment the reference count of `*snapshot`.
163 static void acquire_snapshot(struct snapshot
*snapshot
)
165 snapshot
->referrers
++;
169 * If the buffer in `snapshot` is active, then either munmap the
170 * memory and close the file, or free the memory. Then set the buffer
173 static void clear_snapshot_buffer(struct snapshot
*snapshot
)
175 if (snapshot
->mmapped
) {
176 if (munmap(snapshot
->buf
, snapshot
->eof
- snapshot
->buf
))
177 die_errno("error ummapping packed-refs file %s",
178 snapshot
->refs
->path
);
179 snapshot
->mmapped
= 0;
183 snapshot
->buf
= snapshot
->start
= snapshot
->eof
= NULL
;
187 * Decrease the reference count of `*snapshot`. If it goes to zero,
188 * free `*snapshot` and return true; otherwise return false.
190 static int release_snapshot(struct snapshot
*snapshot
)
192 if (!--snapshot
->referrers
) {
193 stat_validity_clear(&snapshot
->validity
);
194 clear_snapshot_buffer(snapshot
);
202 struct ref_store
*packed_ref_store_create(struct repository
*repo
,
204 unsigned int store_flags
)
206 struct packed_ref_store
*refs
= xcalloc(1, sizeof(*refs
));
207 struct ref_store
*ref_store
= (struct ref_store
*)refs
;
208 struct strbuf sb
= STRBUF_INIT
;
210 base_ref_store_init(ref_store
, repo
, gitdir
, &refs_be_packed
);
211 refs
->store_flags
= store_flags
;
213 strbuf_addf(&sb
, "%s/packed-refs", gitdir
);
214 refs
->path
= strbuf_detach(&sb
, NULL
);
215 chdir_notify_reparent("packed-refs", &refs
->path
);
220 * Downcast `ref_store` to `packed_ref_store`. Die if `ref_store` is
221 * not a `packed_ref_store`. Also die if `packed_ref_store` doesn't
222 * support at least the flags specified in `required_flags`. `caller`
223 * is used in any necessary error messages.
225 static struct packed_ref_store
*packed_downcast(struct ref_store
*ref_store
,
226 unsigned int required_flags
,
229 struct packed_ref_store
*refs
;
231 if (ref_store
->be
!= &refs_be_packed
)
232 BUG("ref_store is type \"%s\" not \"packed\" in %s",
233 ref_store
->be
->name
, caller
);
235 refs
= (struct packed_ref_store
*)ref_store
;
237 if ((refs
->store_flags
& required_flags
) != required_flags
)
238 BUG("unallowed operation (%s), requires %x, has %x\n",
239 caller
, required_flags
, refs
->store_flags
);
244 static void clear_snapshot(struct packed_ref_store
*refs
)
246 if (refs
->snapshot
) {
247 struct snapshot
*snapshot
= refs
->snapshot
;
249 refs
->snapshot
= NULL
;
250 release_snapshot(snapshot
);
254 static NORETURN
void die_unterminated_line(const char *path
,
255 const char *p
, size_t len
)
258 die("unterminated line in %s: %.*s", path
, (int)len
, p
);
260 die("unterminated line in %s: %.75s...", path
, p
);
263 static NORETURN
void die_invalid_line(const char *path
,
264 const char *p
, size_t len
)
266 const char *eol
= memchr(p
, '\n', len
);
269 die_unterminated_line(path
, p
, len
);
270 else if (eol
- p
< 80)
271 die("unexpected line in %s: %.*s", path
, (int)(eol
- p
), p
);
273 die("unexpected line in %s: %.75s...", path
, p
);
277 struct snapshot_record
{
282 static int cmp_packed_ref_records(const void *v1
, const void *v2
)
284 const struct snapshot_record
*e1
= v1
, *e2
= v2
;
285 const char *r1
= e1
->start
+ the_hash_algo
->hexsz
+ 1;
286 const char *r2
= e2
->start
+ the_hash_algo
->hexsz
+ 1;
290 return *r2
== '\n' ? 0 : -1;
295 return (unsigned char)*r1
< (unsigned char)*r2
? -1 : +1;
303 * Compare a snapshot record at `rec` to the specified NUL-terminated
306 static int cmp_record_to_refname(const char *rec
, const char *refname
)
308 const char *r1
= rec
+ the_hash_algo
->hexsz
+ 1;
309 const char *r2
= refname
;
317 return (unsigned char)*r1
< (unsigned char)*r2
? -1 : +1;
324 * `snapshot->buf` is not known to be sorted. Check whether it is, and
325 * if not, sort it into new memory and munmap/free the old storage.
327 static void sort_snapshot(struct snapshot
*snapshot
)
329 struct snapshot_record
*records
= NULL
;
330 size_t alloc
= 0, nr
= 0;
332 const char *pos
, *eof
, *eol
;
334 char *new_buffer
, *dst
;
336 pos
= snapshot
->start
;
345 * Initialize records based on a crude estimate of the number
346 * of references in the file (we'll grow it below if needed):
348 ALLOC_GROW(records
, len
/ 80 + 20, alloc
);
351 eol
= memchr(pos
, '\n', eof
- pos
);
353 /* The safety check should prevent this. */
354 BUG("unterminated line found in packed-refs");
355 if (eol
- pos
< the_hash_algo
->hexsz
+ 2)
356 die_invalid_line(snapshot
->refs
->path
,
359 if (eol
< eof
&& *eol
== '^') {
361 * Keep any peeled line together with its
364 const char *peeled_start
= eol
;
366 eol
= memchr(peeled_start
, '\n', eof
- peeled_start
);
368 /* The safety check should prevent this. */
369 BUG("unterminated peeled line found in packed-refs");
373 ALLOC_GROW(records
, nr
+ 1, alloc
);
374 records
[nr
].start
= pos
;
375 records
[nr
].len
= eol
- pos
;
380 cmp_packed_ref_records(&records
[nr
- 2],
381 &records
[nr
- 1]) >= 0)
390 /* We need to sort the memory. First we sort the records array: */
391 QSORT(records
, nr
, cmp_packed_ref_records
);
394 * Allocate a new chunk of memory, and copy the old memory to
395 * the new in the order indicated by `records` (not bothering
396 * with the header line):
398 new_buffer
= xmalloc(len
);
399 for (dst
= new_buffer
, i
= 0; i
< nr
; i
++) {
400 memcpy(dst
, records
[i
].start
, records
[i
].len
);
401 dst
+= records
[i
].len
;
405 * Now munmap the old buffer and use the sorted buffer in its
408 clear_snapshot_buffer(snapshot
);
409 snapshot
->buf
= snapshot
->start
= new_buffer
;
410 snapshot
->eof
= new_buffer
+ len
;
417 * Return a pointer to the start of the record that contains the
418 * character `*p` (which must be within the buffer). If no other
419 * record start is found, return `buf`.
421 static const char *find_start_of_record(const char *buf
, const char *p
)
423 while (p
> buf
&& (p
[-1] != '\n' || p
[0] == '^'))
429 * Return a pointer to the start of the record following the record
430 * that contains `*p`. If none is found before `end`, return `end`.
432 static const char *find_end_of_record(const char *p
, const char *end
)
434 while (++p
< end
&& (p
[-1] != '\n' || p
[0] == '^'))
440 * We want to be able to compare mmapped reference records quickly,
441 * without totally parsing them. We can do so because the records are
442 * LF-terminated, and the refname should start exactly (GIT_SHA1_HEXSZ
443 * + 1) bytes past the beginning of the record.
445 * But what if the `packed-refs` file contains garbage? We're willing
446 * to tolerate not detecting the problem, as long as we don't produce
447 * totally garbled output (we can't afford to check the integrity of
448 * the whole file during every Git invocation). But we do want to be
449 * sure that we never read past the end of the buffer in memory and
450 * perform an illegal memory access.
452 * Guarantee that minimum level of safety by verifying that the last
453 * record in the file is LF-terminated, and that it has at least
454 * (GIT_SHA1_HEXSZ + 1) characters before the LF. Die if either of
455 * these checks fails.
457 static void verify_buffer_safe(struct snapshot
*snapshot
)
459 const char *start
= snapshot
->start
;
460 const char *eof
= snapshot
->eof
;
461 const char *last_line
;
466 last_line
= find_start_of_record(start
, eof
- 1);
467 if (*(eof
- 1) != '\n' || eof
- last_line
< the_hash_algo
->hexsz
+ 2)
468 die_invalid_line(snapshot
->refs
->path
,
469 last_line
, eof
- last_line
);
472 #define SMALL_FILE_SIZE (32*1024)
475 * Depending on `mmap_strategy`, either mmap or read the contents of
476 * the `packed-refs` file into the snapshot. Return 1 if the file
477 * existed and was read, or 0 if the file was absent or empty. Die on
480 static int load_contents(struct snapshot
*snapshot
)
487 fd
= open(snapshot
->refs
->path
, O_RDONLY
);
489 if (errno
== ENOENT
) {
491 * This is OK; it just means that no
492 * "packed-refs" file has been written yet,
493 * which is equivalent to it being empty,
494 * which is its state when initialized with
499 die_errno("couldn't read %s", snapshot
->refs
->path
);
503 stat_validity_update(&snapshot
->validity
, fd
);
505 if (fstat(fd
, &st
) < 0)
506 die_errno("couldn't stat %s", snapshot
->refs
->path
);
507 size
= xsize_t(st
.st_size
);
512 } else if (mmap_strategy
== MMAP_NONE
|| size
<= SMALL_FILE_SIZE
) {
513 snapshot
->buf
= xmalloc(size
);
514 bytes_read
= read_in_full(fd
, snapshot
->buf
, size
);
515 if (bytes_read
< 0 || bytes_read
!= size
)
516 die_errno("couldn't read %s", snapshot
->refs
->path
);
517 snapshot
->mmapped
= 0;
519 snapshot
->buf
= xmmap(NULL
, size
, PROT_READ
, MAP_PRIVATE
, fd
, 0);
520 snapshot
->mmapped
= 1;
524 snapshot
->start
= snapshot
->buf
;
525 snapshot
->eof
= snapshot
->buf
+ size
;
531 * Find the place in `snapshot->buf` where the start of the record for
532 * `refname` starts. If `mustexist` is true and the reference doesn't
533 * exist, then return NULL. If `mustexist` is false and the reference
534 * doesn't exist, then return the point where that reference would be
535 * inserted, or `snapshot->eof` (which might be NULL) if it would be
536 * inserted at the end of the file. In the latter mode, `refname`
537 * doesn't have to be a proper reference name; for example, one could
538 * search for "refs/replace/" to find the start of any replace
541 * The record is sought using a binary search, so `snapshot->buf` must
544 static const char *find_reference_location(struct snapshot
*snapshot
,
545 const char *refname
, int mustexist
)
548 * This is not *quite* a garden-variety binary search, because
549 * the data we're searching is made up of records, and we
550 * always need to find the beginning of a record to do a
551 * comparison. A "record" here is one line for the reference
552 * itself and zero or one peel lines that start with '^'. Our
553 * loop invariant is described in the next two comments.
557 * A pointer to the character at the start of a record whose
558 * preceding records all have reference names that come
559 * *before* `refname`.
561 const char *lo
= snapshot
->start
;
564 * A pointer to a the first character of a record whose
565 * reference name comes *after* `refname`.
567 const char *hi
= snapshot
->eof
;
570 const char *mid
, *rec
;
573 mid
= lo
+ (hi
- lo
) / 2;
574 rec
= find_start_of_record(lo
, mid
);
575 cmp
= cmp_record_to_refname(rec
, refname
);
577 lo
= find_end_of_record(mid
, hi
);
578 } else if (cmp
> 0) {
592 * Create a newly-allocated `snapshot` of the `packed-refs` file in
593 * its current state and return it. The return value will already have
594 * its reference count incremented.
596 * A comment line of the form "# pack-refs with: " may contain zero or
597 * more traits. We interpret the traits as follows:
599 * Neither `peeled` nor `fully-peeled`:
601 * Probably no references are peeled. But if the file contains a
602 * peeled value for a reference, we will use it.
606 * References under "refs/tags/", if they *can* be peeled, *are*
607 * peeled in this file. References outside of "refs/tags/" are
608 * probably not peeled even if they could have been, but if we find
609 * a peeled value for such a reference we will use it.
613 * All references in the file that can be peeled are peeled.
614 * Inversely (and this is more important), any references in the
615 * file for which no peeled value is recorded is not peelable. This
616 * trait should typically be written alongside "peeled" for
617 * compatibility with older clients, but we do not require it
618 * (i.e., "peeled" is a no-op if "fully-peeled" is set).
622 * The references in this file are known to be sorted by refname.
624 static struct snapshot
*create_snapshot(struct packed_ref_store
*refs
)
626 struct snapshot
*snapshot
= xcalloc(1, sizeof(*snapshot
));
629 snapshot
->refs
= refs
;
630 acquire_snapshot(snapshot
);
631 snapshot
->peeled
= PEELED_NONE
;
633 if (!load_contents(snapshot
))
636 /* If the file has a header line, process it: */
637 if (snapshot
->buf
< snapshot
->eof
&& *snapshot
->buf
== '#') {
639 struct string_list traits
= STRING_LIST_INIT_NODUP
;
641 eol
= memchr(snapshot
->buf
, '\n',
642 snapshot
->eof
- snapshot
->buf
);
644 die_unterminated_line(refs
->path
,
646 snapshot
->eof
- snapshot
->buf
);
648 tmp
= xmemdupz(snapshot
->buf
, eol
- snapshot
->buf
);
650 if (!skip_prefix(tmp
, "# pack-refs with:", (const char **)&p
))
651 die_invalid_line(refs
->path
,
653 snapshot
->eof
- snapshot
->buf
);
655 string_list_split_in_place(&traits
, p
, " ", -1);
657 if (unsorted_string_list_has_string(&traits
, "fully-peeled"))
658 snapshot
->peeled
= PEELED_FULLY
;
659 else if (unsorted_string_list_has_string(&traits
, "peeled"))
660 snapshot
->peeled
= PEELED_TAGS
;
662 sorted
= unsorted_string_list_has_string(&traits
, "sorted");
664 /* perhaps other traits later as well */
666 /* The "+ 1" is for the LF character. */
667 snapshot
->start
= eol
+ 1;
669 string_list_clear(&traits
, 0);
673 verify_buffer_safe(snapshot
);
676 sort_snapshot(snapshot
);
679 * Reordering the records might have moved a short one
680 * to the end of the buffer, so verify the buffer's
683 verify_buffer_safe(snapshot
);
686 if (mmap_strategy
!= MMAP_OK
&& snapshot
->mmapped
) {
688 * We don't want to leave the file mmapped, so we are
689 * forced to make a copy now:
691 size_t size
= snapshot
->eof
- snapshot
->start
;
692 char *buf_copy
= xmalloc(size
);
694 memcpy(buf_copy
, snapshot
->start
, size
);
695 clear_snapshot_buffer(snapshot
);
696 snapshot
->buf
= snapshot
->start
= buf_copy
;
697 snapshot
->eof
= buf_copy
+ size
;
704 * Check that `refs->snapshot` (if present) still reflects the
705 * contents of the `packed-refs` file. If not, clear the snapshot.
707 static void validate_snapshot(struct packed_ref_store
*refs
)
709 if (refs
->snapshot
&&
710 !stat_validity_check(&refs
->snapshot
->validity
, refs
->path
))
711 clear_snapshot(refs
);
715 * Get the `snapshot` for the specified packed_ref_store, creating and
716 * populating it if it hasn't been read before or if the file has been
717 * changed (according to its `validity` field) since it was last read.
718 * On the other hand, if we hold the lock, then assume that the file
719 * hasn't been changed out from under us, so skip the extra `stat()`
720 * call in `stat_validity_check()`. This function does *not* increase
721 * the snapshot's reference count on behalf of the caller.
723 static struct snapshot
*get_snapshot(struct packed_ref_store
*refs
)
725 if (!is_lock_file_locked(&refs
->lock
))
726 validate_snapshot(refs
);
729 refs
->snapshot
= create_snapshot(refs
);
731 return refs
->snapshot
;
734 static int packed_read_raw_ref(struct ref_store
*ref_store
, const char *refname
,
735 struct object_id
*oid
, struct strbuf
*referent UNUSED
,
736 unsigned int *type
, int *failure_errno
)
738 struct packed_ref_store
*refs
=
739 packed_downcast(ref_store
, REF_STORE_READ
, "read_raw_ref");
740 struct snapshot
*snapshot
= get_snapshot(refs
);
745 rec
= find_reference_location(snapshot
, refname
, 1);
748 /* refname is not a packed reference. */
749 *failure_errno
= ENOENT
;
753 if (get_oid_hex(rec
, oid
))
754 die_invalid_line(refs
->path
, rec
, snapshot
->eof
- rec
);
756 *type
= REF_ISPACKED
;
761 * This value is set in `base.flags` if the peeled value of the
762 * current reference is known. In that case, `peeled` contains the
763 * correct peeled value for the reference, which might be `null_oid`
764 * if the reference is not a tag or if it is broken.
766 #define REF_KNOWS_PEELED 0x40
769 * An iterator over a snapshot of a `packed-refs` file.
771 struct packed_ref_iterator
{
772 struct ref_iterator base
;
774 struct snapshot
*snapshot
;
776 /* The current position in the snapshot's buffer: */
779 /* The end of the part of the buffer that will be iterated over: */
782 /* Scratch space for current values: */
783 struct object_id oid
, peeled
;
784 struct strbuf refname_buf
;
786 struct repository
*repo
;
791 * Move the iterator to the next record in the snapshot, without
792 * respect for whether the record is actually required by the current
793 * iteration. Adjust the fields in `iter` and return `ITER_OK` or
794 * `ITER_DONE`. This function does not free the iterator in the case
797 static int next_record(struct packed_ref_iterator
*iter
)
799 const char *p
= iter
->pos
, *eol
;
801 strbuf_reset(&iter
->refname_buf
);
803 if (iter
->pos
== iter
->eof
)
806 iter
->base
.flags
= REF_ISPACKED
;
808 if (iter
->eof
- p
< the_hash_algo
->hexsz
+ 2 ||
809 parse_oid_hex(p
, &iter
->oid
, &p
) ||
811 die_invalid_line(iter
->snapshot
->refs
->path
,
812 iter
->pos
, iter
->eof
- iter
->pos
);
814 eol
= memchr(p
, '\n', iter
->eof
- p
);
816 die_unterminated_line(iter
->snapshot
->refs
->path
,
817 iter
->pos
, iter
->eof
- iter
->pos
);
819 strbuf_add(&iter
->refname_buf
, p
, eol
- p
);
820 iter
->base
.refname
= iter
->refname_buf
.buf
;
822 if (check_refname_format(iter
->base
.refname
, REFNAME_ALLOW_ONELEVEL
)) {
823 if (!refname_is_safe(iter
->base
.refname
))
824 die("packed refname is dangerous: %s",
827 iter
->base
.flags
|= REF_BAD_NAME
| REF_ISBROKEN
;
829 if (iter
->snapshot
->peeled
== PEELED_FULLY
||
830 (iter
->snapshot
->peeled
== PEELED_TAGS
&&
831 starts_with(iter
->base
.refname
, "refs/tags/")))
832 iter
->base
.flags
|= REF_KNOWS_PEELED
;
836 if (iter
->pos
< iter
->eof
&& *iter
->pos
== '^') {
838 if (iter
->eof
- p
< the_hash_algo
->hexsz
+ 1 ||
839 parse_oid_hex(p
, &iter
->peeled
, &p
) ||
841 die_invalid_line(iter
->snapshot
->refs
->path
,
842 iter
->pos
, iter
->eof
- iter
->pos
);
846 * Regardless of what the file header said, we
847 * definitely know the value of *this* reference. But
848 * we suppress it if the reference is broken:
850 if ((iter
->base
.flags
& REF_ISBROKEN
)) {
851 oidclr(&iter
->peeled
);
852 iter
->base
.flags
&= ~REF_KNOWS_PEELED
;
854 iter
->base
.flags
|= REF_KNOWS_PEELED
;
857 oidclr(&iter
->peeled
);
863 static int packed_ref_iterator_advance(struct ref_iterator
*ref_iterator
)
865 struct packed_ref_iterator
*iter
=
866 (struct packed_ref_iterator
*)ref_iterator
;
869 while ((ok
= next_record(iter
)) == ITER_OK
) {
870 if (iter
->flags
& DO_FOR_EACH_PER_WORKTREE_ONLY
&&
871 !is_per_worktree_ref(iter
->base
.refname
))
874 if (!(iter
->flags
& DO_FOR_EACH_INCLUDE_BROKEN
) &&
875 !ref_resolves_to_object(iter
->base
.refname
, iter
->repo
,
876 &iter
->oid
, iter
->flags
))
882 if (ref_iterator_abort(ref_iterator
) != ITER_DONE
)
888 static int packed_ref_iterator_peel(struct ref_iterator
*ref_iterator
,
889 struct object_id
*peeled
)
891 struct packed_ref_iterator
*iter
=
892 (struct packed_ref_iterator
*)ref_iterator
;
894 if (iter
->repo
!= the_repository
)
895 BUG("peeling for non-the_repository is not supported");
897 if ((iter
->base
.flags
& REF_KNOWS_PEELED
)) {
898 oidcpy(peeled
, &iter
->peeled
);
899 return is_null_oid(&iter
->peeled
) ? -1 : 0;
900 } else if ((iter
->base
.flags
& (REF_ISBROKEN
| REF_ISSYMREF
))) {
903 return peel_object(&iter
->oid
, peeled
) ? -1 : 0;
907 static int packed_ref_iterator_abort(struct ref_iterator
*ref_iterator
)
909 struct packed_ref_iterator
*iter
=
910 (struct packed_ref_iterator
*)ref_iterator
;
913 strbuf_release(&iter
->refname_buf
);
914 release_snapshot(iter
->snapshot
);
915 base_ref_iterator_free(ref_iterator
);
919 static struct ref_iterator_vtable packed_ref_iterator_vtable
= {
920 .advance
= packed_ref_iterator_advance
,
921 .peel
= packed_ref_iterator_peel
,
922 .abort
= packed_ref_iterator_abort
925 static struct ref_iterator
*packed_ref_iterator_begin(
926 struct ref_store
*ref_store
,
927 const char *prefix
, unsigned int flags
)
929 struct packed_ref_store
*refs
;
930 struct snapshot
*snapshot
;
932 struct packed_ref_iterator
*iter
;
933 struct ref_iterator
*ref_iterator
;
934 unsigned int required_flags
= REF_STORE_READ
;
936 if (!(flags
& DO_FOR_EACH_INCLUDE_BROKEN
))
937 required_flags
|= REF_STORE_ODB
;
938 refs
= packed_downcast(ref_store
, required_flags
, "ref_iterator_begin");
941 * Note that `get_snapshot()` internally checks whether the
942 * snapshot is up to date with what is on disk, and re-reads
945 snapshot
= get_snapshot(refs
);
947 if (prefix
&& *prefix
)
948 start
= find_reference_location(snapshot
, prefix
, 0);
950 start
= snapshot
->start
;
952 if (start
== snapshot
->eof
)
953 return empty_ref_iterator_begin();
955 CALLOC_ARRAY(iter
, 1);
956 ref_iterator
= &iter
->base
;
957 base_ref_iterator_init(ref_iterator
, &packed_ref_iterator_vtable
, 1);
959 iter
->snapshot
= snapshot
;
960 acquire_snapshot(snapshot
);
963 iter
->eof
= snapshot
->eof
;
964 strbuf_init(&iter
->refname_buf
, 0);
966 iter
->base
.oid
= &iter
->oid
;
968 iter
->repo
= ref_store
->repo
;
971 if (prefix
&& *prefix
)
972 /* Stop iteration after we've gone *past* prefix: */
973 ref_iterator
= prefix_ref_iterator_begin(ref_iterator
, prefix
, 0);
979 * Write an entry to the packed-refs file for the specified refname.
980 * If peeled is non-NULL, write it as the entry's peeled value. On
981 * error, return a nonzero value and leave errno set at the value left
982 * by the failing call to `fprintf()`.
984 static int write_packed_entry(FILE *fh
, const char *refname
,
985 const struct object_id
*oid
,
986 const struct object_id
*peeled
)
988 if (fprintf(fh
, "%s %s\n", oid_to_hex(oid
), refname
) < 0 ||
989 (peeled
&& fprintf(fh
, "^%s\n", oid_to_hex(peeled
)) < 0))
995 int packed_refs_lock(struct ref_store
*ref_store
, int flags
, struct strbuf
*err
)
997 struct packed_ref_store
*refs
=
998 packed_downcast(ref_store
, REF_STORE_WRITE
| REF_STORE_MAIN
,
1000 static int timeout_configured
= 0;
1001 static int timeout_value
= 1000;
1003 if (!timeout_configured
) {
1004 git_config_get_int("core.packedrefstimeout", &timeout_value
);
1005 timeout_configured
= 1;
1009 * Note that we close the lockfile immediately because we
1010 * don't write new content to it, but rather to a separate
1013 if (hold_lock_file_for_update_timeout(
1016 flags
, timeout_value
) < 0) {
1017 unable_to_lock_message(refs
->path
, errno
, err
);
1021 if (close_lock_file_gently(&refs
->lock
)) {
1022 strbuf_addf(err
, "unable to close %s: %s", refs
->path
, strerror(errno
));
1023 rollback_lock_file(&refs
->lock
);
1028 * There is a stat-validity problem might cause `update-ref -d`
1029 * lost the newly commit of a ref, because a new `packed-refs`
1030 * file might has the same on-disk file attributes such as
1031 * timestamp, file size and inode value, but has a changed
1034 * This could happen with a very small chance when
1035 * `update-ref -d` is called and at the same time another
1036 * `pack-refs --all` process is running.
1038 * Now that we hold the `packed-refs` lock, it is important
1039 * to make sure we could read the latest version of
1040 * `packed-refs` file no matter we have just mmap it or not.
1041 * So what need to do is clear the snapshot if we hold it
1044 clear_snapshot(refs
);
1047 * Now make sure that the packed-refs file as it exists in the
1048 * locked state is loaded into the snapshot:
1054 void packed_refs_unlock(struct ref_store
*ref_store
)
1056 struct packed_ref_store
*refs
= packed_downcast(
1058 REF_STORE_READ
| REF_STORE_WRITE
,
1059 "packed_refs_unlock");
1061 if (!is_lock_file_locked(&refs
->lock
))
1062 BUG("packed_refs_unlock() called when not locked");
1063 rollback_lock_file(&refs
->lock
);
1066 int packed_refs_is_locked(struct ref_store
*ref_store
)
1068 struct packed_ref_store
*refs
= packed_downcast(
1070 REF_STORE_READ
| REF_STORE_WRITE
,
1071 "packed_refs_is_locked");
1073 return is_lock_file_locked(&refs
->lock
);
1077 * The packed-refs header line that we write out. Perhaps other traits
1078 * will be added later.
1080 * Note that earlier versions of Git used to parse these traits by
1081 * looking for " trait " in the line. For this reason, the space after
1082 * the colon and the trailing space are required.
1084 static const char PACKED_REFS_HEADER
[] =
1085 "# pack-refs with: peeled fully-peeled sorted \n";
1087 static int packed_init_db(struct ref_store
*ref_store UNUSED
,
1088 struct strbuf
*err UNUSED
)
1090 /* Nothing to do. */
1095 * Write the packed refs from the current snapshot to the packed-refs
1096 * tempfile, incorporating any changes from `updates`. `updates` must
1097 * be a sorted string list whose keys are the refnames and whose util
1098 * values are `struct ref_update *`. On error, rollback the tempfile,
1099 * write an error message to `err`, and return a nonzero value.
1101 * The packfile must be locked before calling this function and will
1102 * remain locked when it is done.
1104 static int write_with_updates(struct packed_ref_store
*refs
,
1105 struct string_list
*updates
,
1108 struct ref_iterator
*iter
= NULL
;
1112 struct strbuf sb
= STRBUF_INIT
;
1113 char *packed_refs_path
;
1115 if (!is_lock_file_locked(&refs
->lock
))
1116 BUG("write_with_updates() called while unlocked");
1119 * If packed-refs is a symlink, we want to overwrite the
1120 * symlinked-to file, not the symlink itself. Also, put the
1121 * staging file next to it:
1123 packed_refs_path
= get_locked_file_path(&refs
->lock
);
1124 strbuf_addf(&sb
, "%s.new", packed_refs_path
);
1125 free(packed_refs_path
);
1126 refs
->tempfile
= create_tempfile(sb
.buf
);
1127 if (!refs
->tempfile
) {
1128 strbuf_addf(err
, "unable to create file %s: %s",
1129 sb
.buf
, strerror(errno
));
1130 strbuf_release(&sb
);
1133 strbuf_release(&sb
);
1135 out
= fdopen_tempfile(refs
->tempfile
, "w");
1137 strbuf_addf(err
, "unable to fdopen packed-refs tempfile: %s",
1142 if (fprintf(out
, "%s", PACKED_REFS_HEADER
) < 0)
1146 * We iterate in parallel through the current list of refs and
1147 * the list of updates, processing an entry from at least one
1148 * of the lists each time through the loop. When the current
1149 * list of refs is exhausted, set iter to NULL. When the list
1150 * of updates is exhausted, leave i set to updates->nr.
1152 iter
= packed_ref_iterator_begin(&refs
->base
, "",
1153 DO_FOR_EACH_INCLUDE_BROKEN
);
1154 if ((ok
= ref_iterator_advance(iter
)) != ITER_OK
)
1159 while (iter
|| i
< updates
->nr
) {
1160 struct ref_update
*update
= NULL
;
1163 if (i
>= updates
->nr
) {
1166 update
= updates
->items
[i
].util
;
1171 cmp
= strcmp(iter
->refname
, update
->refname
);
1176 * There is both an old value and an update
1177 * for this reference. Check the old value if
1180 if ((update
->flags
& REF_HAVE_OLD
)) {
1181 if (is_null_oid(&update
->old_oid
)) {
1182 strbuf_addf(err
, "cannot update ref '%s': "
1183 "reference already exists",
1186 } else if (!oideq(&update
->old_oid
, iter
->oid
)) {
1187 strbuf_addf(err
, "cannot update ref '%s': "
1188 "is at %s but expected %s",
1190 oid_to_hex(iter
->oid
),
1191 oid_to_hex(&update
->old_oid
));
1196 /* Now figure out what to use for the new value: */
1197 if ((update
->flags
& REF_HAVE_NEW
)) {
1199 * The update takes precedence. Skip
1200 * the iterator over the unneeded
1203 if ((ok
= ref_iterator_advance(iter
)) != ITER_OK
)
1208 * The update doesn't actually want to
1209 * change anything. We're done with it.
1214 } else if (cmp
> 0) {
1216 * There is no old value but there is an
1217 * update for this reference. Make sure that
1218 * the update didn't expect an existing value:
1220 if ((update
->flags
& REF_HAVE_OLD
) &&
1221 !is_null_oid(&update
->old_oid
)) {
1222 strbuf_addf(err
, "cannot update ref '%s': "
1223 "reference is missing but expected %s",
1225 oid_to_hex(&update
->old_oid
));
1231 /* Pass the old reference through. */
1233 struct object_id peeled
;
1234 int peel_error
= ref_iterator_peel(iter
, &peeled
);
1236 if (write_packed_entry(out
, iter
->refname
,
1238 peel_error
? NULL
: &peeled
))
1241 if ((ok
= ref_iterator_advance(iter
)) != ITER_OK
)
1243 } else if (is_null_oid(&update
->new_oid
)) {
1245 * The update wants to delete the reference,
1246 * and the reference either didn't exist or we
1247 * have already skipped it. So we're done with
1248 * the update (and don't have to write
1253 struct object_id peeled
;
1254 int peel_error
= peel_object(&update
->new_oid
,
1257 if (write_packed_entry(out
, update
->refname
,
1259 peel_error
? NULL
: &peeled
))
1266 if (ok
!= ITER_DONE
) {
1267 strbuf_addstr(err
, "unable to write packed-refs file: "
1268 "error iterating over old contents");
1273 fsync_component(FSYNC_COMPONENT_REFERENCE
, get_tempfile_fd(refs
->tempfile
)) ||
1274 close_tempfile_gently(refs
->tempfile
)) {
1275 strbuf_addf(err
, "error closing file %s: %s",
1276 get_tempfile_path(refs
->tempfile
),
1278 strbuf_release(&sb
);
1279 delete_tempfile(&refs
->tempfile
);
1286 strbuf_addf(err
, "error writing to %s: %s",
1287 get_tempfile_path(refs
->tempfile
), strerror(errno
));
1291 ref_iterator_abort(iter
);
1293 delete_tempfile(&refs
->tempfile
);
1297 int is_packed_transaction_needed(struct ref_store
*ref_store
,
1298 struct ref_transaction
*transaction
)
1300 struct packed_ref_store
*refs
= packed_downcast(
1303 "is_packed_transaction_needed");
1304 struct strbuf referent
= STRBUF_INIT
;
1308 if (!is_lock_file_locked(&refs
->lock
))
1309 BUG("is_packed_transaction_needed() called while unlocked");
1312 * We're only going to bother returning false for the common,
1313 * trivial case that references are only being deleted, their
1314 * old values are not being checked, and the old `packed-refs`
1315 * file doesn't contain any of those reference(s). This gives
1316 * false positives for some other cases that could
1317 * theoretically be optimized away:
1319 * 1. It could be that the old value is being verified without
1320 * setting a new value. In this case, we could verify the
1321 * old value here and skip the update if it agrees. If it
1322 * disagrees, we could either let the update go through
1323 * (the actual commit would re-detect and report the
1324 * problem), or come up with a way of reporting such an
1325 * error to *our* caller.
1327 * 2. It could be that a new value is being set, but that it
1328 * is identical to the current packed value of the
1331 * Neither of these cases will come up in the current code,
1332 * because the only caller of this function passes to it a
1333 * transaction that only includes `delete` updates with no
1334 * `old_id`. Even if that ever changes, false positives only
1335 * cause an optimization to be missed; they do not affect
1340 * Start with the cheap checks that don't require old
1341 * reference values to be read:
1343 for (i
= 0; i
< transaction
->nr
; i
++) {
1344 struct ref_update
*update
= transaction
->updates
[i
];
1346 if (update
->flags
& REF_HAVE_OLD
)
1347 /* Have to check the old value -> needed. */
1350 if ((update
->flags
& REF_HAVE_NEW
) && !is_null_oid(&update
->new_oid
))
1351 /* Have to set a new value -> needed. */
1356 * The transaction isn't checking any old values nor is it
1357 * setting any nonzero new values, so it still might be able
1358 * to be skipped. Now do the more expensive check: the update
1359 * is needed if any of the updates is a delete, and the old
1360 * `packed-refs` file contains a value for that reference.
1363 for (i
= 0; i
< transaction
->nr
; i
++) {
1364 struct ref_update
*update
= transaction
->updates
[i
];
1367 struct object_id oid
;
1369 if (!(update
->flags
& REF_HAVE_NEW
))
1371 * This reference isn't being deleted -> not
1376 if (!refs_read_raw_ref(ref_store
, update
->refname
, &oid
,
1377 &referent
, &type
, &failure_errno
) ||
1378 failure_errno
!= ENOENT
) {
1380 * We have to actually delete that reference
1381 * -> this transaction is needed.
1388 strbuf_release(&referent
);
1392 struct packed_transaction_backend_data
{
1393 /* True iff the transaction owns the packed-refs lock. */
1396 struct string_list updates
;
1399 static void packed_transaction_cleanup(struct packed_ref_store
*refs
,
1400 struct ref_transaction
*transaction
)
1402 struct packed_transaction_backend_data
*data
= transaction
->backend_data
;
1405 string_list_clear(&data
->updates
, 0);
1407 if (is_tempfile_active(refs
->tempfile
))
1408 delete_tempfile(&refs
->tempfile
);
1410 if (data
->own_lock
&& is_lock_file_locked(&refs
->lock
)) {
1411 packed_refs_unlock(&refs
->base
);
1416 transaction
->backend_data
= NULL
;
1419 transaction
->state
= REF_TRANSACTION_CLOSED
;
1422 static int packed_transaction_prepare(struct ref_store
*ref_store
,
1423 struct ref_transaction
*transaction
,
1426 struct packed_ref_store
*refs
= packed_downcast(
1428 REF_STORE_READ
| REF_STORE_WRITE
| REF_STORE_ODB
,
1429 "ref_transaction_prepare");
1430 struct packed_transaction_backend_data
*data
;
1432 int ret
= TRANSACTION_GENERIC_ERROR
;
1435 * Note that we *don't* skip transactions with zero updates,
1436 * because such a transaction might be executed for the side
1437 * effect of ensuring that all of the references are peeled or
1438 * ensuring that the `packed-refs` file is sorted. If the
1439 * caller wants to optimize away empty transactions, it should
1443 CALLOC_ARRAY(data
, 1);
1444 string_list_init_nodup(&data
->updates
);
1446 transaction
->backend_data
= data
;
1449 * Stick the updates in a string list by refname so that we
1452 for (i
= 0; i
< transaction
->nr
; i
++) {
1453 struct ref_update
*update
= transaction
->updates
[i
];
1454 struct string_list_item
*item
=
1455 string_list_append(&data
->updates
, update
->refname
);
1457 /* Store a pointer to update in item->util: */
1458 item
->util
= update
;
1460 string_list_sort(&data
->updates
);
1462 if (ref_update_reject_duplicates(&data
->updates
, err
))
1465 if (!is_lock_file_locked(&refs
->lock
)) {
1466 if (packed_refs_lock(ref_store
, 0, err
))
1471 if (write_with_updates(refs
, &data
->updates
, err
))
1474 transaction
->state
= REF_TRANSACTION_PREPARED
;
1478 packed_transaction_cleanup(refs
, transaction
);
1482 static int packed_transaction_abort(struct ref_store
*ref_store
,
1483 struct ref_transaction
*transaction
,
1484 struct strbuf
*err UNUSED
)
1486 struct packed_ref_store
*refs
= packed_downcast(
1488 REF_STORE_READ
| REF_STORE_WRITE
| REF_STORE_ODB
,
1489 "ref_transaction_abort");
1491 packed_transaction_cleanup(refs
, transaction
);
1495 static int packed_transaction_finish(struct ref_store
*ref_store
,
1496 struct ref_transaction
*transaction
,
1499 struct packed_ref_store
*refs
= packed_downcast(
1501 REF_STORE_READ
| REF_STORE_WRITE
| REF_STORE_ODB
,
1502 "ref_transaction_finish");
1503 int ret
= TRANSACTION_GENERIC_ERROR
;
1504 char *packed_refs_path
;
1506 clear_snapshot(refs
);
1508 packed_refs_path
= get_locked_file_path(&refs
->lock
);
1509 if (rename_tempfile(&refs
->tempfile
, packed_refs_path
)) {
1510 strbuf_addf(err
, "error replacing %s: %s",
1511 refs
->path
, strerror(errno
));
1518 free(packed_refs_path
);
1519 packed_transaction_cleanup(refs
, transaction
);
1523 static int packed_initial_transaction_commit(struct ref_store
*ref_store UNUSED
,
1524 struct ref_transaction
*transaction
,
1527 return ref_transaction_commit(transaction
, err
);
1530 static int packed_delete_refs(struct ref_store
*ref_store
, const char *msg
,
1531 struct string_list
*refnames
, unsigned int flags
)
1533 struct packed_ref_store
*refs
=
1534 packed_downcast(ref_store
, REF_STORE_WRITE
, "delete_refs");
1535 struct strbuf err
= STRBUF_INIT
;
1536 struct ref_transaction
*transaction
;
1537 struct string_list_item
*item
;
1540 (void)refs
; /* We need the check above, but don't use the variable */
1546 * Since we don't check the references' old_oids, the
1547 * individual updates can't fail, so we can pack all of the
1548 * updates into a single transaction.
1551 transaction
= ref_store_transaction_begin(ref_store
, &err
);
1555 for_each_string_list_item(item
, refnames
) {
1556 if (ref_transaction_delete(transaction
, item
->string
, NULL
,
1557 flags
, msg
, &err
)) {
1558 warning(_("could not delete reference %s: %s"),
1559 item
->string
, err
.buf
);
1564 ret
= ref_transaction_commit(transaction
, &err
);
1567 if (refnames
->nr
== 1)
1568 error(_("could not delete reference %s: %s"),
1569 refnames
->items
[0].string
, err
.buf
);
1571 error(_("could not delete references: %s"), err
.buf
);
1574 ref_transaction_free(transaction
);
1575 strbuf_release(&err
);
1579 static int packed_pack_refs(struct ref_store
*ref_store UNUSED
,
1580 struct pack_refs_opts
*pack_opts UNUSED
)
1583 * Packed refs are already packed. It might be that loose refs
1584 * are packed *into* a packed refs store, but that is done by
1585 * updating the packed references via a transaction.
1590 static struct ref_iterator
*packed_reflog_iterator_begin(struct ref_store
*ref_store UNUSED
)
1592 return empty_ref_iterator_begin();
1595 struct ref_storage_be refs_be_packed
= {
1598 .init
= packed_ref_store_create
,
1599 .init_db
= packed_init_db
,
1600 .transaction_prepare
= packed_transaction_prepare
,
1601 .transaction_finish
= packed_transaction_finish
,
1602 .transaction_abort
= packed_transaction_abort
,
1603 .initial_transaction_commit
= packed_initial_transaction_commit
,
1605 .pack_refs
= packed_pack_refs
,
1606 .create_symref
= NULL
,
1607 .delete_refs
= packed_delete_refs
,
1611 .iterator_begin
= packed_ref_iterator_begin
,
1612 .read_raw_ref
= packed_read_raw_ref
,
1613 .read_symbolic_ref
= NULL
,
1615 .reflog_iterator_begin
= packed_reflog_iterator_begin
,
1616 .for_each_reflog_ent
= NULL
,
1617 .for_each_reflog_ent_reverse
= NULL
,
1618 .reflog_exists
= NULL
,
1619 .create_reflog
= NULL
,
1620 .delete_reflog
= NULL
,
1621 .reflog_expire
= NULL
,