1 #include "../git-compat-util.h"
3 #include "../gettext.h"
7 #include "refs-internal.h"
8 #include "packed-backend.h"
9 #include "../iterator.h"
10 #include "../lockfile.h"
11 #include "../chdir-notify.h"
12 #include "../statinfo.h"
13 #include "../wrapper.h"
14 #include "../write-or-die.h"
15 #include "../trace2.h"
19 * Don't use mmap() at all for reading `packed-refs`.
24 * Can use mmap() for reading `packed-refs`, but the file must
25 * not remain mmapped. This is the usual option on Windows,
26 * where you cannot rename a new version of a file onto a file
27 * that is currently mmapped.
32 * It is OK to leave the `packed-refs` file mmapped while
33 * arbitrary other code is running.
39 static enum mmap_strategy mmap_strategy
= MMAP_NONE
;
40 #elif defined(MMAP_PREVENTS_DELETE)
41 static enum mmap_strategy mmap_strategy
= MMAP_TEMPORARY
;
43 static enum mmap_strategy mmap_strategy
= MMAP_OK
;
46 struct packed_ref_store
;
49 * A `snapshot` represents one snapshot of a `packed-refs` file.
51 * Normally, this will be a mmapped view of the contents of the
52 * `packed-refs` file at the time the snapshot was created. However,
53 * if the `packed-refs` file was not sorted, this might point at heap
54 * memory holding the contents of the `packed-refs` file with its
55 * records sorted by refname.
57 * `snapshot` instances are reference counted (via
58 * `acquire_snapshot()` and `release_snapshot()`). This is to prevent
59 * an instance from disappearing while an iterator is still iterating
60 * over it. Instances are garbage collected when their `referrers`
63 * The most recent `snapshot`, if available, is referenced by the
64 * `packed_ref_store`. Its freshness is checked whenever
65 * `get_snapshot()` is called; if the existing snapshot is obsolete, a
66 * new snapshot is taken.
70 * A back-pointer to the packed_ref_store with which this
71 * snapshot is associated:
73 struct packed_ref_store
*refs
;
75 /* Is the `packed-refs` file currently mmapped? */
79 * The contents of the `packed-refs` file:
81 * - buf -- a pointer to the start of the memory
82 * - start -- a pointer to the first byte of actual references
83 * (i.e., after the header line, if one is present)
84 * - eof -- a pointer just past the end of the reference
87 * If the `packed-refs` file was already sorted, `buf` points
88 * at the mmapped contents of the file. If not, it points at
89 * heap-allocated memory containing the contents, sorted. If
90 * there were no contents (e.g., because the file didn't
91 * exist), `buf`, `start`, and `eof` are all NULL.
93 char *buf
, *start
, *eof
;
96 * What is the peeled state of the `packed-refs` file that
97 * this snapshot represents? (This is usually determined from
100 enum { PEELED_NONE
, PEELED_TAGS
, PEELED_FULLY
} peeled
;
103 * Count of references to this instance, including the pointer
104 * from `packed_ref_store::snapshot`, if any. The instance
105 * will not be freed as long as the reference count is
108 unsigned int referrers
;
111 * The metadata of the `packed-refs` file from which this
112 * snapshot was created, used to tell if the file has been
113 * replaced since we read it.
115 struct stat_validity validity
;
119 * A `ref_store` representing references stored in a `packed-refs`
120 * file. It implements the `ref_store` interface, though it has some
123 * - It cannot store symbolic references.
125 * - It cannot store reflogs.
127 * - It does not support reference renaming (though it could).
129 * On the other hand, it can be locked outside of a reference
130 * transaction. In that case, it remains locked even after the
131 * transaction is done and the new `packed-refs` file is activated.
133 struct packed_ref_store
{
134 struct ref_store base
;
136 unsigned int store_flags
;
138 /* The path of the "packed-refs" file: */
142 * A snapshot of the values read from the `packed-refs` file,
143 * if it might still be current; otherwise, NULL.
145 struct snapshot
*snapshot
;
148 * Lock used for the "packed-refs" file. Note that this (and
149 * thus the enclosing `packed_ref_store`) must not be freed.
151 struct lock_file lock
;
154 * Temporary file used when rewriting new contents to the
155 * "packed-refs" file. Note that this (and thus the enclosing
156 * `packed_ref_store`) must not be freed.
158 struct tempfile
*tempfile
;
162 * Increment the reference count of `*snapshot`.
164 static void acquire_snapshot(struct snapshot
*snapshot
)
166 snapshot
->referrers
++;
170 * If the buffer in `snapshot` is active, then either munmap the
171 * memory and close the file, or free the memory. Then set the buffer
174 static void clear_snapshot_buffer(struct snapshot
*snapshot
)
176 if (snapshot
->mmapped
) {
177 if (munmap(snapshot
->buf
, snapshot
->eof
- snapshot
->buf
))
178 die_errno("error ummapping packed-refs file %s",
179 snapshot
->refs
->path
);
180 snapshot
->mmapped
= 0;
184 snapshot
->buf
= snapshot
->start
= snapshot
->eof
= NULL
;
188 * Decrease the reference count of `*snapshot`. If it goes to zero,
189 * free `*snapshot` and return true; otherwise return false.
191 static int release_snapshot(struct snapshot
*snapshot
)
193 if (!--snapshot
->referrers
) {
194 stat_validity_clear(&snapshot
->validity
);
195 clear_snapshot_buffer(snapshot
);
203 struct ref_store
*packed_ref_store_create(struct repository
*repo
,
205 unsigned int store_flags
)
207 struct packed_ref_store
*refs
= xcalloc(1, sizeof(*refs
));
208 struct ref_store
*ref_store
= (struct ref_store
*)refs
;
209 struct strbuf sb
= STRBUF_INIT
;
211 base_ref_store_init(ref_store
, repo
, gitdir
, &refs_be_packed
);
212 refs
->store_flags
= store_flags
;
214 strbuf_addf(&sb
, "%s/packed-refs", gitdir
);
215 refs
->path
= strbuf_detach(&sb
, NULL
);
216 chdir_notify_reparent("packed-refs", &refs
->path
);
221 * Downcast `ref_store` to `packed_ref_store`. Die if `ref_store` is
222 * not a `packed_ref_store`. Also die if `packed_ref_store` doesn't
223 * support at least the flags specified in `required_flags`. `caller`
224 * is used in any necessary error messages.
226 static struct packed_ref_store
*packed_downcast(struct ref_store
*ref_store
,
227 unsigned int required_flags
,
230 struct packed_ref_store
*refs
;
232 if (ref_store
->be
!= &refs_be_packed
)
233 BUG("ref_store is type \"%s\" not \"packed\" in %s",
234 ref_store
->be
->name
, caller
);
236 refs
= (struct packed_ref_store
*)ref_store
;
238 if ((refs
->store_flags
& required_flags
) != required_flags
)
239 BUG("unallowed operation (%s), requires %x, has %x\n",
240 caller
, required_flags
, refs
->store_flags
);
245 static void clear_snapshot(struct packed_ref_store
*refs
)
247 if (refs
->snapshot
) {
248 struct snapshot
*snapshot
= refs
->snapshot
;
250 refs
->snapshot
= NULL
;
251 release_snapshot(snapshot
);
255 static NORETURN
void die_unterminated_line(const char *path
,
256 const char *p
, size_t len
)
259 die("unterminated line in %s: %.*s", path
, (int)len
, p
);
261 die("unterminated line in %s: %.75s...", path
, p
);
264 static NORETURN
void die_invalid_line(const char *path
,
265 const char *p
, size_t len
)
267 const char *eol
= memchr(p
, '\n', len
);
270 die_unterminated_line(path
, p
, len
);
271 else if (eol
- p
< 80)
272 die("unexpected line in %s: %.*s", path
, (int)(eol
- p
), p
);
274 die("unexpected line in %s: %.75s...", path
, p
);
278 struct snapshot_record
{
283 static int cmp_packed_ref_records(const void *v1
, const void *v2
)
285 const struct snapshot_record
*e1
= v1
, *e2
= v2
;
286 const char *r1
= e1
->start
+ the_hash_algo
->hexsz
+ 1;
287 const char *r2
= e2
->start
+ the_hash_algo
->hexsz
+ 1;
291 return *r2
== '\n' ? 0 : -1;
296 return (unsigned char)*r1
< (unsigned char)*r2
? -1 : +1;
304 * Compare a snapshot record at `rec` to the specified NUL-terminated
307 static int cmp_record_to_refname(const char *rec
, const char *refname
,
310 const char *r1
= rec
+ the_hash_algo
->hexsz
+ 1;
311 const char *r2
= refname
;
317 return start
? 1 : -1;
319 return (unsigned char)*r1
< (unsigned char)*r2
? -1 : +1;
326 * `snapshot->buf` is not known to be sorted. Check whether it is, and
327 * if not, sort it into new memory and munmap/free the old storage.
329 static void sort_snapshot(struct snapshot
*snapshot
)
331 struct snapshot_record
*records
= NULL
;
332 size_t alloc
= 0, nr
= 0;
334 const char *pos
, *eof
, *eol
;
336 char *new_buffer
, *dst
;
338 pos
= snapshot
->start
;
347 * Initialize records based on a crude estimate of the number
348 * of references in the file (we'll grow it below if needed):
350 ALLOC_GROW(records
, len
/ 80 + 20, alloc
);
353 eol
= memchr(pos
, '\n', eof
- pos
);
355 /* The safety check should prevent this. */
356 BUG("unterminated line found in packed-refs");
357 if (eol
- pos
< the_hash_algo
->hexsz
+ 2)
358 die_invalid_line(snapshot
->refs
->path
,
361 if (eol
< eof
&& *eol
== '^') {
363 * Keep any peeled line together with its
366 const char *peeled_start
= eol
;
368 eol
= memchr(peeled_start
, '\n', eof
- peeled_start
);
370 /* The safety check should prevent this. */
371 BUG("unterminated peeled line found in packed-refs");
375 ALLOC_GROW(records
, nr
+ 1, alloc
);
376 records
[nr
].start
= pos
;
377 records
[nr
].len
= eol
- pos
;
382 cmp_packed_ref_records(&records
[nr
- 2],
383 &records
[nr
- 1]) >= 0)
392 /* We need to sort the memory. First we sort the records array: */
393 QSORT(records
, nr
, cmp_packed_ref_records
);
396 * Allocate a new chunk of memory, and copy the old memory to
397 * the new in the order indicated by `records` (not bothering
398 * with the header line):
400 new_buffer
= xmalloc(len
);
401 for (dst
= new_buffer
, i
= 0; i
< nr
; i
++) {
402 memcpy(dst
, records
[i
].start
, records
[i
].len
);
403 dst
+= records
[i
].len
;
407 * Now munmap the old buffer and use the sorted buffer in its
410 clear_snapshot_buffer(snapshot
);
411 snapshot
->buf
= snapshot
->start
= new_buffer
;
412 snapshot
->eof
= new_buffer
+ len
;
419 * Return a pointer to the start of the record that contains the
420 * character `*p` (which must be within the buffer). If no other
421 * record start is found, return `buf`.
423 static const char *find_start_of_record(const char *buf
, const char *p
)
425 while (p
> buf
&& (p
[-1] != '\n' || p
[0] == '^'))
431 * Return a pointer to the start of the record following the record
432 * that contains `*p`. If none is found before `end`, return `end`.
434 static const char *find_end_of_record(const char *p
, const char *end
)
436 while (++p
< end
&& (p
[-1] != '\n' || p
[0] == '^'))
442 * We want to be able to compare mmapped reference records quickly,
443 * without totally parsing them. We can do so because the records are
444 * LF-terminated, and the refname should start exactly (GIT_SHA1_HEXSZ
445 * + 1) bytes past the beginning of the record.
447 * But what if the `packed-refs` file contains garbage? We're willing
448 * to tolerate not detecting the problem, as long as we don't produce
449 * totally garbled output (we can't afford to check the integrity of
450 * the whole file during every Git invocation). But we do want to be
451 * sure that we never read past the end of the buffer in memory and
452 * perform an illegal memory access.
454 * Guarantee that minimum level of safety by verifying that the last
455 * record in the file is LF-terminated, and that it has at least
456 * (GIT_SHA1_HEXSZ + 1) characters before the LF. Die if either of
457 * these checks fails.
459 static void verify_buffer_safe(struct snapshot
*snapshot
)
461 const char *start
= snapshot
->start
;
462 const char *eof
= snapshot
->eof
;
463 const char *last_line
;
468 last_line
= find_start_of_record(start
, eof
- 1);
469 if (*(eof
- 1) != '\n' || eof
- last_line
< the_hash_algo
->hexsz
+ 2)
470 die_invalid_line(snapshot
->refs
->path
,
471 last_line
, eof
- last_line
);
474 #define SMALL_FILE_SIZE (32*1024)
477 * Depending on `mmap_strategy`, either mmap or read the contents of
478 * the `packed-refs` file into the snapshot. Return 1 if the file
479 * existed and was read, or 0 if the file was absent or empty. Die on
482 static int load_contents(struct snapshot
*snapshot
)
489 fd
= open(snapshot
->refs
->path
, O_RDONLY
);
491 if (errno
== ENOENT
) {
493 * This is OK; it just means that no
494 * "packed-refs" file has been written yet,
495 * which is equivalent to it being empty,
496 * which is its state when initialized with
501 die_errno("couldn't read %s", snapshot
->refs
->path
);
505 stat_validity_update(&snapshot
->validity
, fd
);
507 if (fstat(fd
, &st
) < 0)
508 die_errno("couldn't stat %s", snapshot
->refs
->path
);
509 size
= xsize_t(st
.st_size
);
514 } else if (mmap_strategy
== MMAP_NONE
|| size
<= SMALL_FILE_SIZE
) {
515 snapshot
->buf
= xmalloc(size
);
516 bytes_read
= read_in_full(fd
, snapshot
->buf
, size
);
517 if (bytes_read
< 0 || bytes_read
!= size
)
518 die_errno("couldn't read %s", snapshot
->refs
->path
);
519 snapshot
->mmapped
= 0;
521 snapshot
->buf
= xmmap(NULL
, size
, PROT_READ
, MAP_PRIVATE
, fd
, 0);
522 snapshot
->mmapped
= 1;
526 snapshot
->start
= snapshot
->buf
;
527 snapshot
->eof
= snapshot
->buf
+ size
;
532 static const char *find_reference_location_1(struct snapshot
*snapshot
,
533 const char *refname
, int mustexist
,
537 * This is not *quite* a garden-variety binary search, because
538 * the data we're searching is made up of records, and we
539 * always need to find the beginning of a record to do a
540 * comparison. A "record" here is one line for the reference
541 * itself and zero or one peel lines that start with '^'. Our
542 * loop invariant is described in the next two comments.
546 * A pointer to the character at the start of a record whose
547 * preceding records all have reference names that come
548 * *before* `refname`.
550 const char *lo
= snapshot
->start
;
553 * A pointer to a the first character of a record whose
554 * reference name comes *after* `refname`.
556 const char *hi
= snapshot
->eof
;
559 const char *mid
, *rec
;
562 mid
= lo
+ (hi
- lo
) / 2;
563 rec
= find_start_of_record(lo
, mid
);
564 cmp
= cmp_record_to_refname(rec
, refname
, start
);
566 lo
= find_end_of_record(mid
, hi
);
567 } else if (cmp
> 0) {
581 * Find the place in `snapshot->buf` where the start of the record for
582 * `refname` starts. If `mustexist` is true and the reference doesn't
583 * exist, then return NULL. If `mustexist` is false and the reference
584 * doesn't exist, then return the point where that reference would be
585 * inserted, or `snapshot->eof` (which might be NULL) if it would be
586 * inserted at the end of the file. In the latter mode, `refname`
587 * doesn't have to be a proper reference name; for example, one could
588 * search for "refs/replace/" to find the start of any replace
591 * The record is sought using a binary search, so `snapshot->buf` must
594 static const char *find_reference_location(struct snapshot
*snapshot
,
595 const char *refname
, int mustexist
)
597 return find_reference_location_1(snapshot
, refname
, mustexist
, 1);
601 * Find the place in `snapshot->buf` after the end of the record for
602 * `refname`. In other words, find the location of first thing *after*
605 * Other semantics are identical to the ones in
606 * `find_reference_location()`.
608 static const char *find_reference_location_end(struct snapshot
*snapshot
,
612 return find_reference_location_1(snapshot
, refname
, mustexist
, 0);
616 * Create a newly-allocated `snapshot` of the `packed-refs` file in
617 * its current state and return it. The return value will already have
618 * its reference count incremented.
620 * A comment line of the form "# pack-refs with: " may contain zero or
621 * more traits. We interpret the traits as follows:
623 * Neither `peeled` nor `fully-peeled`:
625 * Probably no references are peeled. But if the file contains a
626 * peeled value for a reference, we will use it.
630 * References under "refs/tags/", if they *can* be peeled, *are*
631 * peeled in this file. References outside of "refs/tags/" are
632 * probably not peeled even if they could have been, but if we find
633 * a peeled value for such a reference we will use it.
637 * All references in the file that can be peeled are peeled.
638 * Inversely (and this is more important), any references in the
639 * file for which no peeled value is recorded is not peelable. This
640 * trait should typically be written alongside "peeled" for
641 * compatibility with older clients, but we do not require it
642 * (i.e., "peeled" is a no-op if "fully-peeled" is set).
646 * The references in this file are known to be sorted by refname.
648 static struct snapshot
*create_snapshot(struct packed_ref_store
*refs
)
650 struct snapshot
*snapshot
= xcalloc(1, sizeof(*snapshot
));
653 snapshot
->refs
= refs
;
654 acquire_snapshot(snapshot
);
655 snapshot
->peeled
= PEELED_NONE
;
657 if (!load_contents(snapshot
))
660 /* If the file has a header line, process it: */
661 if (snapshot
->buf
< snapshot
->eof
&& *snapshot
->buf
== '#') {
663 struct string_list traits
= STRING_LIST_INIT_NODUP
;
665 eol
= memchr(snapshot
->buf
, '\n',
666 snapshot
->eof
- snapshot
->buf
);
668 die_unterminated_line(refs
->path
,
670 snapshot
->eof
- snapshot
->buf
);
672 tmp
= xmemdupz(snapshot
->buf
, eol
- snapshot
->buf
);
674 if (!skip_prefix(tmp
, "# pack-refs with:", (const char **)&p
))
675 die_invalid_line(refs
->path
,
677 snapshot
->eof
- snapshot
->buf
);
679 string_list_split_in_place(&traits
, p
, " ", -1);
681 if (unsorted_string_list_has_string(&traits
, "fully-peeled"))
682 snapshot
->peeled
= PEELED_FULLY
;
683 else if (unsorted_string_list_has_string(&traits
, "peeled"))
684 snapshot
->peeled
= PEELED_TAGS
;
686 sorted
= unsorted_string_list_has_string(&traits
, "sorted");
688 /* perhaps other traits later as well */
690 /* The "+ 1" is for the LF character. */
691 snapshot
->start
= eol
+ 1;
693 string_list_clear(&traits
, 0);
697 verify_buffer_safe(snapshot
);
700 sort_snapshot(snapshot
);
703 * Reordering the records might have moved a short one
704 * to the end of the buffer, so verify the buffer's
707 verify_buffer_safe(snapshot
);
710 if (mmap_strategy
!= MMAP_OK
&& snapshot
->mmapped
) {
712 * We don't want to leave the file mmapped, so we are
713 * forced to make a copy now:
715 size_t size
= snapshot
->eof
- snapshot
->start
;
716 char *buf_copy
= xmalloc(size
);
718 memcpy(buf_copy
, snapshot
->start
, size
);
719 clear_snapshot_buffer(snapshot
);
720 snapshot
->buf
= snapshot
->start
= buf_copy
;
721 snapshot
->eof
= buf_copy
+ size
;
728 * Check that `refs->snapshot` (if present) still reflects the
729 * contents of the `packed-refs` file. If not, clear the snapshot.
731 static void validate_snapshot(struct packed_ref_store
*refs
)
733 if (refs
->snapshot
&&
734 !stat_validity_check(&refs
->snapshot
->validity
, refs
->path
))
735 clear_snapshot(refs
);
739 * Get the `snapshot` for the specified packed_ref_store, creating and
740 * populating it if it hasn't been read before or if the file has been
741 * changed (according to its `validity` field) since it was last read.
742 * On the other hand, if we hold the lock, then assume that the file
743 * hasn't been changed out from under us, so skip the extra `stat()`
744 * call in `stat_validity_check()`. This function does *not* increase
745 * the snapshot's reference count on behalf of the caller.
747 static struct snapshot
*get_snapshot(struct packed_ref_store
*refs
)
749 if (!is_lock_file_locked(&refs
->lock
))
750 validate_snapshot(refs
);
753 refs
->snapshot
= create_snapshot(refs
);
755 return refs
->snapshot
;
758 static int packed_read_raw_ref(struct ref_store
*ref_store
, const char *refname
,
759 struct object_id
*oid
, struct strbuf
*referent UNUSED
,
760 unsigned int *type
, int *failure_errno
)
762 struct packed_ref_store
*refs
=
763 packed_downcast(ref_store
, REF_STORE_READ
, "read_raw_ref");
764 struct snapshot
*snapshot
= get_snapshot(refs
);
769 rec
= find_reference_location(snapshot
, refname
, 1);
772 /* refname is not a packed reference. */
773 *failure_errno
= ENOENT
;
777 if (get_oid_hex(rec
, oid
))
778 die_invalid_line(refs
->path
, rec
, snapshot
->eof
- rec
);
780 *type
= REF_ISPACKED
;
785 * This value is set in `base.flags` if the peeled value of the
786 * current reference is known. In that case, `peeled` contains the
787 * correct peeled value for the reference, which might be `null_oid`
788 * if the reference is not a tag or if it is broken.
790 #define REF_KNOWS_PEELED 0x40
793 * An iterator over a snapshot of a `packed-refs` file.
795 struct packed_ref_iterator
{
796 struct ref_iterator base
;
798 struct snapshot
*snapshot
;
800 /* The current position in the snapshot's buffer: */
803 /* The end of the part of the buffer that will be iterated over: */
806 struct jump_list_entry
{
810 size_t jump_nr
, jump_alloc
;
813 /* Scratch space for current values: */
814 struct object_id oid
, peeled
;
815 struct strbuf refname_buf
;
817 struct repository
*repo
;
822 * Move the iterator to the next record in the snapshot, without
823 * respect for whether the record is actually required by the current
824 * iteration. Adjust the fields in `iter` and return `ITER_OK` or
825 * `ITER_DONE`. This function does not free the iterator in the case
828 static int next_record(struct packed_ref_iterator
*iter
)
832 strbuf_reset(&iter
->refname_buf
);
835 * If iter->pos is contained within a skipped region, jump past
838 * Note that each skipped region is considered at most once,
839 * since they are ordered based on their starting position.
841 while (iter
->jump_cur
< iter
->jump_nr
) {
842 struct jump_list_entry
*curr
= &iter
->jump
[iter
->jump_cur
];
843 if (iter
->pos
< curr
->start
)
844 break; /* not to the next jump yet */
847 if (iter
->pos
< curr
->end
) {
848 iter
->pos
= curr
->end
;
849 trace2_counter_add(TRACE2_COUNTER_ID_PACKED_REFS_JUMPS
, 1);
850 /* jumps are coalesced, so only one jump is necessary */
855 if (iter
->pos
== iter
->eof
)
858 iter
->base
.flags
= REF_ISPACKED
;
861 if (iter
->eof
- p
< the_hash_algo
->hexsz
+ 2 ||
862 parse_oid_hex(p
, &iter
->oid
, &p
) ||
864 die_invalid_line(iter
->snapshot
->refs
->path
,
865 iter
->pos
, iter
->eof
- iter
->pos
);
867 eol
= memchr(p
, '\n', iter
->eof
- p
);
869 die_unterminated_line(iter
->snapshot
->refs
->path
,
870 iter
->pos
, iter
->eof
- iter
->pos
);
872 strbuf_add(&iter
->refname_buf
, p
, eol
- p
);
873 iter
->base
.refname
= iter
->refname_buf
.buf
;
875 if (check_refname_format(iter
->base
.refname
, REFNAME_ALLOW_ONELEVEL
)) {
876 if (!refname_is_safe(iter
->base
.refname
))
877 die("packed refname is dangerous: %s",
880 iter
->base
.flags
|= REF_BAD_NAME
| REF_ISBROKEN
;
882 if (iter
->snapshot
->peeled
== PEELED_FULLY
||
883 (iter
->snapshot
->peeled
== PEELED_TAGS
&&
884 starts_with(iter
->base
.refname
, "refs/tags/")))
885 iter
->base
.flags
|= REF_KNOWS_PEELED
;
889 if (iter
->pos
< iter
->eof
&& *iter
->pos
== '^') {
891 if (iter
->eof
- p
< the_hash_algo
->hexsz
+ 1 ||
892 parse_oid_hex(p
, &iter
->peeled
, &p
) ||
894 die_invalid_line(iter
->snapshot
->refs
->path
,
895 iter
->pos
, iter
->eof
- iter
->pos
);
899 * Regardless of what the file header said, we
900 * definitely know the value of *this* reference. But
901 * we suppress it if the reference is broken:
903 if ((iter
->base
.flags
& REF_ISBROKEN
)) {
904 oidclr(&iter
->peeled
);
905 iter
->base
.flags
&= ~REF_KNOWS_PEELED
;
907 iter
->base
.flags
|= REF_KNOWS_PEELED
;
910 oidclr(&iter
->peeled
);
916 static int packed_ref_iterator_advance(struct ref_iterator
*ref_iterator
)
918 struct packed_ref_iterator
*iter
=
919 (struct packed_ref_iterator
*)ref_iterator
;
922 while ((ok
= next_record(iter
)) == ITER_OK
) {
923 if (iter
->flags
& DO_FOR_EACH_PER_WORKTREE_ONLY
&&
924 !is_per_worktree_ref(iter
->base
.refname
))
927 if (!(iter
->flags
& DO_FOR_EACH_INCLUDE_BROKEN
) &&
928 !ref_resolves_to_object(iter
->base
.refname
, iter
->repo
,
929 &iter
->oid
, iter
->flags
))
935 if (ref_iterator_abort(ref_iterator
) != ITER_DONE
)
941 static int packed_ref_iterator_peel(struct ref_iterator
*ref_iterator
,
942 struct object_id
*peeled
)
944 struct packed_ref_iterator
*iter
=
945 (struct packed_ref_iterator
*)ref_iterator
;
947 if (iter
->repo
!= the_repository
)
948 BUG("peeling for non-the_repository is not supported");
950 if ((iter
->base
.flags
& REF_KNOWS_PEELED
)) {
951 oidcpy(peeled
, &iter
->peeled
);
952 return is_null_oid(&iter
->peeled
) ? -1 : 0;
953 } else if ((iter
->base
.flags
& (REF_ISBROKEN
| REF_ISSYMREF
))) {
956 return peel_object(&iter
->oid
, peeled
) ? -1 : 0;
960 static int packed_ref_iterator_abort(struct ref_iterator
*ref_iterator
)
962 struct packed_ref_iterator
*iter
=
963 (struct packed_ref_iterator
*)ref_iterator
;
966 strbuf_release(&iter
->refname_buf
);
968 release_snapshot(iter
->snapshot
);
969 base_ref_iterator_free(ref_iterator
);
973 static struct ref_iterator_vtable packed_ref_iterator_vtable
= {
974 .advance
= packed_ref_iterator_advance
,
975 .peel
= packed_ref_iterator_peel
,
976 .abort
= packed_ref_iterator_abort
979 static int jump_list_entry_cmp(const void *va
, const void *vb
)
981 const struct jump_list_entry
*a
= va
;
982 const struct jump_list_entry
*b
= vb
;
984 if (a
->start
< b
->start
)
986 if (a
->start
> b
->start
)
991 static int has_glob_special(const char *str
)
994 for (p
= str
; *p
; p
++) {
995 if (is_glob_special(*p
))
1001 static void populate_excluded_jump_list(struct packed_ref_iterator
*iter
,
1002 struct snapshot
*snapshot
,
1003 const char **excluded_patterns
)
1006 const char **pattern
;
1007 struct jump_list_entry
*last_disjoint
;
1009 if (!excluded_patterns
)
1012 for (pattern
= excluded_patterns
; *pattern
; pattern
++) {
1013 struct jump_list_entry
*e
;
1014 const char *start
, *end
;
1017 * We can't feed any excludes with globs in them to the
1018 * refs machinery. It only understands prefix matching.
1019 * We likewise can't even feed the string leading up to
1020 * the first meta-character, as something like "foo[a]"
1021 * should not exclude "foobar" (but the prefix "foo"
1022 * would match that and mark it for exclusion).
1024 if (has_glob_special(*pattern
))
1027 start
= find_reference_location(snapshot
, *pattern
, 0);
1028 end
= find_reference_location_end(snapshot
, *pattern
, 0);
1031 continue; /* nothing to jump over */
1033 ALLOC_GROW(iter
->jump
, iter
->jump_nr
+ 1, iter
->jump_alloc
);
1035 e
= &iter
->jump
[iter
->jump_nr
++];
1040 if (!iter
->jump_nr
) {
1042 * Every entry in exclude_patterns has a meta-character,
1043 * nothing to do here.
1048 QSORT(iter
->jump
, iter
->jump_nr
, jump_list_entry_cmp
);
1051 * As an optimization, merge adjacent entries in the jump list
1052 * to jump forwards as far as possible when entering a skipped
1055 * For example, if we have two skipped regions:
1059 * we want to combine that into a single entry jumping from A to
1062 last_disjoint
= iter
->jump
;
1064 for (i
= 1, j
= 1; i
< iter
->jump_nr
; i
++) {
1065 struct jump_list_entry
*ours
= &iter
->jump
[i
];
1066 if (ours
->start
<= last_disjoint
->end
) {
1067 /* overlapping regions extend the previous one */
1068 last_disjoint
->end
= last_disjoint
->end
> ours
->end
1069 ? last_disjoint
->end
: ours
->end
;
1071 /* otherwise, insert a new region */
1072 iter
->jump
[j
++] = *ours
;
1073 last_disjoint
= ours
;
1081 static struct ref_iterator
*packed_ref_iterator_begin(
1082 struct ref_store
*ref_store
,
1083 const char *prefix
, const char **exclude_patterns
,
1086 struct packed_ref_store
*refs
;
1087 struct snapshot
*snapshot
;
1089 struct packed_ref_iterator
*iter
;
1090 struct ref_iterator
*ref_iterator
;
1091 unsigned int required_flags
= REF_STORE_READ
;
1093 if (!(flags
& DO_FOR_EACH_INCLUDE_BROKEN
))
1094 required_flags
|= REF_STORE_ODB
;
1095 refs
= packed_downcast(ref_store
, required_flags
, "ref_iterator_begin");
1098 * Note that `get_snapshot()` internally checks whether the
1099 * snapshot is up to date with what is on disk, and re-reads
1102 snapshot
= get_snapshot(refs
);
1104 if (prefix
&& *prefix
)
1105 start
= find_reference_location(snapshot
, prefix
, 0);
1107 start
= snapshot
->start
;
1109 if (start
== snapshot
->eof
)
1110 return empty_ref_iterator_begin();
1112 CALLOC_ARRAY(iter
, 1);
1113 ref_iterator
= &iter
->base
;
1114 base_ref_iterator_init(ref_iterator
, &packed_ref_iterator_vtable
);
1116 if (exclude_patterns
)
1117 populate_excluded_jump_list(iter
, snapshot
, exclude_patterns
);
1119 iter
->snapshot
= snapshot
;
1120 acquire_snapshot(snapshot
);
1123 iter
->eof
= snapshot
->eof
;
1124 strbuf_init(&iter
->refname_buf
, 0);
1126 iter
->base
.oid
= &iter
->oid
;
1128 iter
->repo
= ref_store
->repo
;
1129 iter
->flags
= flags
;
1131 if (prefix
&& *prefix
)
1132 /* Stop iteration after we've gone *past* prefix: */
1133 ref_iterator
= prefix_ref_iterator_begin(ref_iterator
, prefix
, 0);
1135 return ref_iterator
;
1139 * Write an entry to the packed-refs file for the specified refname.
1140 * If peeled is non-NULL, write it as the entry's peeled value. On
1141 * error, return a nonzero value and leave errno set at the value left
1142 * by the failing call to `fprintf()`.
1144 static int write_packed_entry(FILE *fh
, const char *refname
,
1145 const struct object_id
*oid
,
1146 const struct object_id
*peeled
)
1148 if (fprintf(fh
, "%s %s\n", oid_to_hex(oid
), refname
) < 0 ||
1149 (peeled
&& fprintf(fh
, "^%s\n", oid_to_hex(peeled
)) < 0))
1155 int packed_refs_lock(struct ref_store
*ref_store
, int flags
, struct strbuf
*err
)
1157 struct packed_ref_store
*refs
=
1158 packed_downcast(ref_store
, REF_STORE_WRITE
| REF_STORE_MAIN
,
1159 "packed_refs_lock");
1160 static int timeout_configured
= 0;
1161 static int timeout_value
= 1000;
1163 if (!timeout_configured
) {
1164 git_config_get_int("core.packedrefstimeout", &timeout_value
);
1165 timeout_configured
= 1;
1169 * Note that we close the lockfile immediately because we
1170 * don't write new content to it, but rather to a separate
1173 if (hold_lock_file_for_update_timeout(
1176 flags
, timeout_value
) < 0) {
1177 unable_to_lock_message(refs
->path
, errno
, err
);
1181 if (close_lock_file_gently(&refs
->lock
)) {
1182 strbuf_addf(err
, "unable to close %s: %s", refs
->path
, strerror(errno
));
1183 rollback_lock_file(&refs
->lock
);
1188 * There is a stat-validity problem might cause `update-ref -d`
1189 * lost the newly commit of a ref, because a new `packed-refs`
1190 * file might has the same on-disk file attributes such as
1191 * timestamp, file size and inode value, but has a changed
1194 * This could happen with a very small chance when
1195 * `update-ref -d` is called and at the same time another
1196 * `pack-refs --all` process is running.
1198 * Now that we hold the `packed-refs` lock, it is important
1199 * to make sure we could read the latest version of
1200 * `packed-refs` file no matter we have just mmap it or not.
1201 * So what need to do is clear the snapshot if we hold it
1204 clear_snapshot(refs
);
1207 * Now make sure that the packed-refs file as it exists in the
1208 * locked state is loaded into the snapshot:
1214 void packed_refs_unlock(struct ref_store
*ref_store
)
1216 struct packed_ref_store
*refs
= packed_downcast(
1218 REF_STORE_READ
| REF_STORE_WRITE
,
1219 "packed_refs_unlock");
1221 if (!is_lock_file_locked(&refs
->lock
))
1222 BUG("packed_refs_unlock() called when not locked");
1223 rollback_lock_file(&refs
->lock
);
1226 int packed_refs_is_locked(struct ref_store
*ref_store
)
1228 struct packed_ref_store
*refs
= packed_downcast(
1230 REF_STORE_READ
| REF_STORE_WRITE
,
1231 "packed_refs_is_locked");
1233 return is_lock_file_locked(&refs
->lock
);
1237 * The packed-refs header line that we write out. Perhaps other traits
1238 * will be added later.
1240 * Note that earlier versions of Git used to parse these traits by
1241 * looking for " trait " in the line. For this reason, the space after
1242 * the colon and the trailing space are required.
1244 static const char PACKED_REFS_HEADER
[] =
1245 "# pack-refs with: peeled fully-peeled sorted \n";
1247 static int packed_init_db(struct ref_store
*ref_store UNUSED
,
1249 struct strbuf
*err UNUSED
)
1251 /* Nothing to do. */
1256 * Write the packed refs from the current snapshot to the packed-refs
1257 * tempfile, incorporating any changes from `updates`. `updates` must
1258 * be a sorted string list whose keys are the refnames and whose util
1259 * values are `struct ref_update *`. On error, rollback the tempfile,
1260 * write an error message to `err`, and return a nonzero value.
1262 * The packfile must be locked before calling this function and will
1263 * remain locked when it is done.
1265 static int write_with_updates(struct packed_ref_store
*refs
,
1266 struct string_list
*updates
,
1269 struct ref_iterator
*iter
= NULL
;
1273 struct strbuf sb
= STRBUF_INIT
;
1274 char *packed_refs_path
;
1276 if (!is_lock_file_locked(&refs
->lock
))
1277 BUG("write_with_updates() called while unlocked");
1280 * If packed-refs is a symlink, we want to overwrite the
1281 * symlinked-to file, not the symlink itself. Also, put the
1282 * staging file next to it:
1284 packed_refs_path
= get_locked_file_path(&refs
->lock
);
1285 strbuf_addf(&sb
, "%s.new", packed_refs_path
);
1286 free(packed_refs_path
);
1287 refs
->tempfile
= create_tempfile(sb
.buf
);
1288 if (!refs
->tempfile
) {
1289 strbuf_addf(err
, "unable to create file %s: %s",
1290 sb
.buf
, strerror(errno
));
1291 strbuf_release(&sb
);
1294 strbuf_release(&sb
);
1296 out
= fdopen_tempfile(refs
->tempfile
, "w");
1298 strbuf_addf(err
, "unable to fdopen packed-refs tempfile: %s",
1303 if (fprintf(out
, "%s", PACKED_REFS_HEADER
) < 0)
1307 * We iterate in parallel through the current list of refs and
1308 * the list of updates, processing an entry from at least one
1309 * of the lists each time through the loop. When the current
1310 * list of refs is exhausted, set iter to NULL. When the list
1311 * of updates is exhausted, leave i set to updates->nr.
1313 iter
= packed_ref_iterator_begin(&refs
->base
, "", NULL
,
1314 DO_FOR_EACH_INCLUDE_BROKEN
);
1315 if ((ok
= ref_iterator_advance(iter
)) != ITER_OK
)
1320 while (iter
|| i
< updates
->nr
) {
1321 struct ref_update
*update
= NULL
;
1324 if (i
>= updates
->nr
) {
1327 update
= updates
->items
[i
].util
;
1332 cmp
= strcmp(iter
->refname
, update
->refname
);
1337 * There is both an old value and an update
1338 * for this reference. Check the old value if
1341 if ((update
->flags
& REF_HAVE_OLD
)) {
1342 if (is_null_oid(&update
->old_oid
)) {
1343 strbuf_addf(err
, "cannot update ref '%s': "
1344 "reference already exists",
1347 } else if (!oideq(&update
->old_oid
, iter
->oid
)) {
1348 strbuf_addf(err
, "cannot update ref '%s': "
1349 "is at %s but expected %s",
1351 oid_to_hex(iter
->oid
),
1352 oid_to_hex(&update
->old_oid
));
1357 /* Now figure out what to use for the new value: */
1358 if ((update
->flags
& REF_HAVE_NEW
)) {
1360 * The update takes precedence. Skip
1361 * the iterator over the unneeded
1364 if ((ok
= ref_iterator_advance(iter
)) != ITER_OK
)
1369 * The update doesn't actually want to
1370 * change anything. We're done with it.
1375 } else if (cmp
> 0) {
1377 * There is no old value but there is an
1378 * update for this reference. Make sure that
1379 * the update didn't expect an existing value:
1381 if ((update
->flags
& REF_HAVE_OLD
) &&
1382 !is_null_oid(&update
->old_oid
)) {
1383 strbuf_addf(err
, "cannot update ref '%s': "
1384 "reference is missing but expected %s",
1386 oid_to_hex(&update
->old_oid
));
1392 /* Pass the old reference through. */
1394 struct object_id peeled
;
1395 int peel_error
= ref_iterator_peel(iter
, &peeled
);
1397 if (write_packed_entry(out
, iter
->refname
,
1399 peel_error
? NULL
: &peeled
))
1402 if ((ok
= ref_iterator_advance(iter
)) != ITER_OK
)
1404 } else if (is_null_oid(&update
->new_oid
)) {
1406 * The update wants to delete the reference,
1407 * and the reference either didn't exist or we
1408 * have already skipped it. So we're done with
1409 * the update (and don't have to write
1414 struct object_id peeled
;
1415 int peel_error
= peel_object(&update
->new_oid
,
1418 if (write_packed_entry(out
, update
->refname
,
1420 peel_error
? NULL
: &peeled
))
1427 if (ok
!= ITER_DONE
) {
1428 strbuf_addstr(err
, "unable to write packed-refs file: "
1429 "error iterating over old contents");
1434 fsync_component(FSYNC_COMPONENT_REFERENCE
, get_tempfile_fd(refs
->tempfile
)) ||
1435 close_tempfile_gently(refs
->tempfile
)) {
1436 strbuf_addf(err
, "error closing file %s: %s",
1437 get_tempfile_path(refs
->tempfile
),
1439 strbuf_release(&sb
);
1440 delete_tempfile(&refs
->tempfile
);
1447 strbuf_addf(err
, "error writing to %s: %s",
1448 get_tempfile_path(refs
->tempfile
), strerror(errno
));
1452 ref_iterator_abort(iter
);
1454 delete_tempfile(&refs
->tempfile
);
1458 int is_packed_transaction_needed(struct ref_store
*ref_store
,
1459 struct ref_transaction
*transaction
)
1461 struct packed_ref_store
*refs
= packed_downcast(
1464 "is_packed_transaction_needed");
1465 struct strbuf referent
= STRBUF_INIT
;
1469 if (!is_lock_file_locked(&refs
->lock
))
1470 BUG("is_packed_transaction_needed() called while unlocked");
1473 * We're only going to bother returning false for the common,
1474 * trivial case that references are only being deleted, their
1475 * old values are not being checked, and the old `packed-refs`
1476 * file doesn't contain any of those reference(s). This gives
1477 * false positives for some other cases that could
1478 * theoretically be optimized away:
1480 * 1. It could be that the old value is being verified without
1481 * setting a new value. In this case, we could verify the
1482 * old value here and skip the update if it agrees. If it
1483 * disagrees, we could either let the update go through
1484 * (the actual commit would re-detect and report the
1485 * problem), or come up with a way of reporting such an
1486 * error to *our* caller.
1488 * 2. It could be that a new value is being set, but that it
1489 * is identical to the current packed value of the
1492 * Neither of these cases will come up in the current code,
1493 * because the only caller of this function passes to it a
1494 * transaction that only includes `delete` updates with no
1495 * `old_id`. Even if that ever changes, false positives only
1496 * cause an optimization to be missed; they do not affect
1501 * Start with the cheap checks that don't require old
1502 * reference values to be read:
1504 for (i
= 0; i
< transaction
->nr
; i
++) {
1505 struct ref_update
*update
= transaction
->updates
[i
];
1507 if (update
->flags
& REF_HAVE_OLD
)
1508 /* Have to check the old value -> needed. */
1511 if ((update
->flags
& REF_HAVE_NEW
) && !is_null_oid(&update
->new_oid
))
1512 /* Have to set a new value -> needed. */
1517 * The transaction isn't checking any old values nor is it
1518 * setting any nonzero new values, so it still might be able
1519 * to be skipped. Now do the more expensive check: the update
1520 * is needed if any of the updates is a delete, and the old
1521 * `packed-refs` file contains a value for that reference.
1524 for (i
= 0; i
< transaction
->nr
; i
++) {
1525 struct ref_update
*update
= transaction
->updates
[i
];
1528 struct object_id oid
;
1530 if (!(update
->flags
& REF_HAVE_NEW
))
1532 * This reference isn't being deleted -> not
1537 if (!refs_read_raw_ref(ref_store
, update
->refname
, &oid
,
1538 &referent
, &type
, &failure_errno
) ||
1539 failure_errno
!= ENOENT
) {
1541 * We have to actually delete that reference
1542 * -> this transaction is needed.
1549 strbuf_release(&referent
);
1553 struct packed_transaction_backend_data
{
1554 /* True iff the transaction owns the packed-refs lock. */
1557 struct string_list updates
;
1560 static void packed_transaction_cleanup(struct packed_ref_store
*refs
,
1561 struct ref_transaction
*transaction
)
1563 struct packed_transaction_backend_data
*data
= transaction
->backend_data
;
1566 string_list_clear(&data
->updates
, 0);
1568 if (is_tempfile_active(refs
->tempfile
))
1569 delete_tempfile(&refs
->tempfile
);
1571 if (data
->own_lock
&& is_lock_file_locked(&refs
->lock
)) {
1572 packed_refs_unlock(&refs
->base
);
1577 transaction
->backend_data
= NULL
;
1580 transaction
->state
= REF_TRANSACTION_CLOSED
;
1583 static int packed_transaction_prepare(struct ref_store
*ref_store
,
1584 struct ref_transaction
*transaction
,
1587 struct packed_ref_store
*refs
= packed_downcast(
1589 REF_STORE_READ
| REF_STORE_WRITE
| REF_STORE_ODB
,
1590 "ref_transaction_prepare");
1591 struct packed_transaction_backend_data
*data
;
1593 int ret
= TRANSACTION_GENERIC_ERROR
;
1596 * Note that we *don't* skip transactions with zero updates,
1597 * because such a transaction might be executed for the side
1598 * effect of ensuring that all of the references are peeled or
1599 * ensuring that the `packed-refs` file is sorted. If the
1600 * caller wants to optimize away empty transactions, it should
1604 CALLOC_ARRAY(data
, 1);
1605 string_list_init_nodup(&data
->updates
);
1607 transaction
->backend_data
= data
;
1610 * Stick the updates in a string list by refname so that we
1613 for (i
= 0; i
< transaction
->nr
; i
++) {
1614 struct ref_update
*update
= transaction
->updates
[i
];
1615 struct string_list_item
*item
=
1616 string_list_append(&data
->updates
, update
->refname
);
1618 /* Store a pointer to update in item->util: */
1619 item
->util
= update
;
1621 string_list_sort(&data
->updates
);
1623 if (ref_update_reject_duplicates(&data
->updates
, err
))
1626 if (!is_lock_file_locked(&refs
->lock
)) {
1627 if (packed_refs_lock(ref_store
, 0, err
))
1632 if (write_with_updates(refs
, &data
->updates
, err
))
1635 transaction
->state
= REF_TRANSACTION_PREPARED
;
1639 packed_transaction_cleanup(refs
, transaction
);
1643 static int packed_transaction_abort(struct ref_store
*ref_store
,
1644 struct ref_transaction
*transaction
,
1645 struct strbuf
*err UNUSED
)
1647 struct packed_ref_store
*refs
= packed_downcast(
1649 REF_STORE_READ
| REF_STORE_WRITE
| REF_STORE_ODB
,
1650 "ref_transaction_abort");
1652 packed_transaction_cleanup(refs
, transaction
);
1656 static int packed_transaction_finish(struct ref_store
*ref_store
,
1657 struct ref_transaction
*transaction
,
1660 struct packed_ref_store
*refs
= packed_downcast(
1662 REF_STORE_READ
| REF_STORE_WRITE
| REF_STORE_ODB
,
1663 "ref_transaction_finish");
1664 int ret
= TRANSACTION_GENERIC_ERROR
;
1665 char *packed_refs_path
;
1667 clear_snapshot(refs
);
1669 packed_refs_path
= get_locked_file_path(&refs
->lock
);
1670 if (rename_tempfile(&refs
->tempfile
, packed_refs_path
)) {
1671 strbuf_addf(err
, "error replacing %s: %s",
1672 refs
->path
, strerror(errno
));
1679 free(packed_refs_path
);
1680 packed_transaction_cleanup(refs
, transaction
);
1684 static int packed_initial_transaction_commit(struct ref_store
*ref_store UNUSED
,
1685 struct ref_transaction
*transaction
,
1688 return ref_transaction_commit(transaction
, err
);
1691 static int packed_pack_refs(struct ref_store
*ref_store UNUSED
,
1692 struct pack_refs_opts
*pack_opts UNUSED
)
1695 * Packed refs are already packed. It might be that loose refs
1696 * are packed *into* a packed refs store, but that is done by
1697 * updating the packed references via a transaction.
1702 static struct ref_iterator
*packed_reflog_iterator_begin(struct ref_store
*ref_store UNUSED
)
1704 return empty_ref_iterator_begin();
1707 struct ref_storage_be refs_be_packed
= {
1709 .init
= packed_ref_store_create
,
1710 .init_db
= packed_init_db
,
1711 .transaction_prepare
= packed_transaction_prepare
,
1712 .transaction_finish
= packed_transaction_finish
,
1713 .transaction_abort
= packed_transaction_abort
,
1714 .initial_transaction_commit
= packed_initial_transaction_commit
,
1716 .pack_refs
= packed_pack_refs
,
1720 .iterator_begin
= packed_ref_iterator_begin
,
1721 .read_raw_ref
= packed_read_raw_ref
,
1722 .read_symbolic_ref
= NULL
,
1724 .reflog_iterator_begin
= packed_reflog_iterator_begin
,
1725 .for_each_reflog_ent
= NULL
,
1726 .for_each_reflog_ent_reverse
= NULL
,
1727 .reflog_exists
= NULL
,
1728 .create_reflog
= NULL
,
1729 .delete_reflog
= NULL
,
1730 .reflog_expire
= NULL
,