diff options
Diffstat (limited to 'third_party/git/refs/packed-backend.c')
| -rw-r--r-- | third_party/git/refs/packed-backend.c | 1670 |
1 files changed, 0 insertions, 1670 deletions
diff --git a/third_party/git/refs/packed-backend.c b/third_party/git/refs/packed-backend.c deleted file mode 100644 index b912f2505fee..000000000000 --- a/third_party/git/refs/packed-backend.c +++ /dev/null @@ -1,1670 +0,0 @@ -#include "../cache.h" -#include "../config.h" -#include "../refs.h" -#include "refs-internal.h" -#include "packed-backend.h" -#include "../iterator.h" -#include "../lockfile.h" -#include "../chdir-notify.h" - -enum mmap_strategy { - /* - * Don't use mmap() at all for reading `packed-refs`. - */ - MMAP_NONE, - - /* - * Can use mmap() for reading `packed-refs`, but the file must - * not remain mmapped. This is the usual option on Windows, - * where you cannot rename a new version of a file onto a file - * that is currently mmapped. - */ - MMAP_TEMPORARY, - - /* - * It is OK to leave the `packed-refs` file mmapped while - * arbitrary other code is running. - */ - MMAP_OK -}; - -#if defined(NO_MMAP) -static enum mmap_strategy mmap_strategy = MMAP_NONE; -#elif defined(MMAP_PREVENTS_DELETE) -static enum mmap_strategy mmap_strategy = MMAP_TEMPORARY; -#else -static enum mmap_strategy mmap_strategy = MMAP_OK; -#endif - -struct packed_ref_store; - -/* - * A `snapshot` represents one snapshot of a `packed-refs` file. - * - * Normally, this will be a mmapped view of the contents of the - * `packed-refs` file at the time the snapshot was created. However, - * if the `packed-refs` file was not sorted, this might point at heap - * memory holding the contents of the `packed-refs` file with its - * records sorted by refname. - * - * `snapshot` instances are reference counted (via - * `acquire_snapshot()` and `release_snapshot()`). This is to prevent - * an instance from disappearing while an iterator is still iterating - * over it. Instances are garbage collected when their `referrers` - * count goes to zero. - * - * The most recent `snapshot`, if available, is referenced by the - * `packed_ref_store`. Its freshness is checked whenever - * `get_snapshot()` is called; if the existing snapshot is obsolete, a - * new snapshot is taken. - */ -struct snapshot { - /* - * A back-pointer to the packed_ref_store with which this - * snapshot is associated: - */ - struct packed_ref_store *refs; - - /* Is the `packed-refs` file currently mmapped? */ - int mmapped; - - /* - * The contents of the `packed-refs` file: - * - * - buf -- a pointer to the start of the memory - * - start -- a pointer to the first byte of actual references - * (i.e., after the header line, if one is present) - * - eof -- a pointer just past the end of the reference - * contents - * - * If the `packed-refs` file was already sorted, `buf` points - * at the mmapped contents of the file. If not, it points at - * heap-allocated memory containing the contents, sorted. If - * there were no contents (e.g., because the file didn't - * exist), `buf`, `start`, and `eof` are all NULL. - */ - char *buf, *start, *eof; - - /* - * What is the peeled state of the `packed-refs` file that - * this snapshot represents? (This is usually determined from - * the file's header.) - */ - enum { PEELED_NONE, PEELED_TAGS, PEELED_FULLY } peeled; - - /* - * Count of references to this instance, including the pointer - * from `packed_ref_store::snapshot`, if any. The instance - * will not be freed as long as the reference count is - * nonzero. - */ - unsigned int referrers; - - /* - * The metadata of the `packed-refs` file from which this - * snapshot was created, used to tell if the file has been - * replaced since we read it. - */ - struct stat_validity validity; -}; - -/* - * A `ref_store` representing references stored in a `packed-refs` - * file. It implements the `ref_store` interface, though it has some - * limitations: - * - * - It cannot store symbolic references. - * - * - It cannot store reflogs. - * - * - It does not support reference renaming (though it could). - * - * On the other hand, it can be locked outside of a reference - * transaction. In that case, it remains locked even after the - * transaction is done and the new `packed-refs` file is activated. - */ -struct packed_ref_store { - struct ref_store base; - - unsigned int store_flags; - - /* The path of the "packed-refs" file: */ - char *path; - - /* - * A snapshot of the values read from the `packed-refs` file, - * if it might still be current; otherwise, NULL. - */ - struct snapshot *snapshot; - - /* - * Lock used for the "packed-refs" file. Note that this (and - * thus the enclosing `packed_ref_store`) must not be freed. - */ - struct lock_file lock; - - /* - * Temporary file used when rewriting new contents to the - * "packed-refs" file. Note that this (and thus the enclosing - * `packed_ref_store`) must not be freed. - */ - struct tempfile *tempfile; -}; - -/* - * Increment the reference count of `*snapshot`. - */ -static void acquire_snapshot(struct snapshot *snapshot) -{ - snapshot->referrers++; -} - -/* - * If the buffer in `snapshot` is active, then either munmap the - * memory and close the file, or free the memory. Then set the buffer - * pointers to NULL. - */ -static void clear_snapshot_buffer(struct snapshot *snapshot) -{ - if (snapshot->mmapped) { - if (munmap(snapshot->buf, snapshot->eof - snapshot->buf)) - die_errno("error ummapping packed-refs file %s", - snapshot->refs->path); - snapshot->mmapped = 0; - } else { - free(snapshot->buf); - } - snapshot->buf = snapshot->start = snapshot->eof = NULL; -} - -/* - * Decrease the reference count of `*snapshot`. If it goes to zero, - * free `*snapshot` and return true; otherwise return false. - */ -static int release_snapshot(struct snapshot *snapshot) -{ - if (!--snapshot->referrers) { - stat_validity_clear(&snapshot->validity); - clear_snapshot_buffer(snapshot); - free(snapshot); - return 1; - } else { - return 0; - } -} - -struct ref_store *packed_ref_store_create(const char *path, - unsigned int store_flags) -{ - struct packed_ref_store *refs = xcalloc(1, sizeof(*refs)); - struct ref_store *ref_store = (struct ref_store *)refs; - - base_ref_store_init(ref_store, &refs_be_packed); - ref_store->gitdir = xstrdup(path); - refs->store_flags = store_flags; - - refs->path = xstrdup(path); - chdir_notify_reparent("packed-refs", &refs->path); - - return ref_store; -} - -/* - * Downcast `ref_store` to `packed_ref_store`. Die if `ref_store` is - * not a `packed_ref_store`. Also die if `packed_ref_store` doesn't - * support at least the flags specified in `required_flags`. `caller` - * is used in any necessary error messages. - */ -static struct packed_ref_store *packed_downcast(struct ref_store *ref_store, - unsigned int required_flags, - const char *caller) -{ - struct packed_ref_store *refs; - - if (ref_store->be != &refs_be_packed) - BUG("ref_store is type \"%s\" not \"packed\" in %s", - ref_store->be->name, caller); - - refs = (struct packed_ref_store *)ref_store; - - if ((refs->store_flags & required_flags) != required_flags) - BUG("unallowed operation (%s), requires %x, has %x\n", - caller, required_flags, refs->store_flags); - - return refs; -} - -static void clear_snapshot(struct packed_ref_store *refs) -{ - if (refs->snapshot) { - struct snapshot *snapshot = refs->snapshot; - - refs->snapshot = NULL; - release_snapshot(snapshot); - } -} - -static NORETURN void die_unterminated_line(const char *path, - const char *p, size_t len) -{ - if (len < 80) - die("unterminated line in %s: %.*s", path, (int)len, p); - else - die("unterminated line in %s: %.75s...", path, p); -} - -static NORETURN void die_invalid_line(const char *path, - const char *p, size_t len) -{ - const char *eol = memchr(p, '\n', len); - - if (!eol) - die_unterminated_line(path, p, len); - else if (eol - p < 80) - die("unexpected line in %s: %.*s", path, (int)(eol - p), p); - else - die("unexpected line in %s: %.75s...", path, p); - -} - -struct snapshot_record { - const char *start; - size_t len; -}; - -static int cmp_packed_ref_records(const void *v1, const void *v2) -{ - const struct snapshot_record *e1 = v1, *e2 = v2; - const char *r1 = e1->start + the_hash_algo->hexsz + 1; - const char *r2 = e2->start + the_hash_algo->hexsz + 1; - - while (1) { - if (*r1 == '\n') - return *r2 == '\n' ? 0 : -1; - if (*r1 != *r2) { - if (*r2 == '\n') - return 1; - else - return (unsigned char)*r1 < (unsigned char)*r2 ? -1 : +1; - } - r1++; - r2++; - } -} - -/* - * Compare a snapshot record at `rec` to the specified NUL-terminated - * refname. - */ -static int cmp_record_to_refname(const char *rec, const char *refname) -{ - const char *r1 = rec + the_hash_algo->hexsz + 1; - const char *r2 = refname; - - while (1) { - if (*r1 == '\n') - return *r2 ? -1 : 0; - if (!*r2) - return 1; - if (*r1 != *r2) - return (unsigned char)*r1 < (unsigned char)*r2 ? -1 : +1; - r1++; - r2++; - } -} - -/* - * `snapshot->buf` is not known to be sorted. Check whether it is, and - * if not, sort it into new memory and munmap/free the old storage. - */ -static void sort_snapshot(struct snapshot *snapshot) -{ - struct snapshot_record *records = NULL; - size_t alloc = 0, nr = 0; - int sorted = 1; - const char *pos, *eof, *eol; - size_t len, i; - char *new_buffer, *dst; - - pos = snapshot->start; - eof = snapshot->eof; - - if (pos == eof) - return; - - len = eof - pos; - - /* - * Initialize records based on a crude estimate of the number - * of references in the file (we'll grow it below if needed): - */ - ALLOC_GROW(records, len / 80 + 20, alloc); - - while (pos < eof) { - eol = memchr(pos, '\n', eof - pos); - if (!eol) - /* The safety check should prevent this. */ - BUG("unterminated line found in packed-refs"); - if (eol - pos < the_hash_algo->hexsz + 2) - die_invalid_line(snapshot->refs->path, - pos, eof - pos); - eol++; - if (eol < eof && *eol == '^') { - /* - * Keep any peeled line together with its - * reference: - */ - const char *peeled_start = eol; - - eol = memchr(peeled_start, '\n', eof - peeled_start); - if (!eol) - /* The safety check should prevent this. */ - BUG("unterminated peeled line found in packed-refs"); - eol++; - } - - ALLOC_GROW(records, nr + 1, alloc); - records[nr].start = pos; - records[nr].len = eol - pos; - nr++; - - if (sorted && - nr > 1 && - cmp_packed_ref_records(&records[nr - 2], - &records[nr - 1]) >= 0) - sorted = 0; - - pos = eol; - } - - if (sorted) - goto cleanup; - - /* We need to sort the memory. First we sort the records array: */ - QSORT(records, nr, cmp_packed_ref_records); - - /* - * Allocate a new chunk of memory, and copy the old memory to - * the new in the order indicated by `records` (not bothering - * with the header line): - */ - new_buffer = xmalloc(len); - for (dst = new_buffer, i = 0; i < nr; i++) { - memcpy(dst, records[i].start, records[i].len); - dst += records[i].len; - } - - /* - * Now munmap the old buffer and use the sorted buffer in its - * place: - */ - clear_snapshot_buffer(snapshot); - snapshot->buf = snapshot->start = new_buffer; - snapshot->eof = new_buffer + len; - -cleanup: - free(records); -} - -/* - * Return a pointer to the start of the record that contains the - * character `*p` (which must be within the buffer). If no other - * record start is found, return `buf`. - */ -static const char *find_start_of_record(const char *buf, const char *p) -{ - while (p > buf && (p[-1] != '\n' || p[0] == '^')) - p--; - return p; -} - -/* - * Return a pointer to the start of the record following the record - * that contains `*p`. If none is found before `end`, return `end`. - */ -static const char *find_end_of_record(const char *p, const char *end) -{ - while (++p < end && (p[-1] != '\n' || p[0] == '^')) - ; - return p; -} - -/* - * We want to be able to compare mmapped reference records quickly, - * without totally parsing them. We can do so because the records are - * LF-terminated, and the refname should start exactly (GIT_SHA1_HEXSZ - * + 1) bytes past the beginning of the record. - * - * But what if the `packed-refs` file contains garbage? We're willing - * to tolerate not detecting the problem, as long as we don't produce - * totally garbled output (we can't afford to check the integrity of - * the whole file during every Git invocation). But we do want to be - * sure that we never read past the end of the buffer in memory and - * perform an illegal memory access. - * - * Guarantee that minimum level of safety by verifying that the last - * record in the file is LF-terminated, and that it has at least - * (GIT_SHA1_HEXSZ + 1) characters before the LF. Die if either of - * these checks fails. - */ -static void verify_buffer_safe(struct snapshot *snapshot) -{ - const char *start = snapshot->start; - const char *eof = snapshot->eof; - const char *last_line; - - if (start == eof) - return; - - last_line = find_start_of_record(start, eof - 1); - if (*(eof - 1) != '\n' || eof - last_line < the_hash_algo->hexsz + 2) - die_invalid_line(snapshot->refs->path, - last_line, eof - last_line); -} - -#define SMALL_FILE_SIZE (32*1024) - -/* - * Depending on `mmap_strategy`, either mmap or read the contents of - * the `packed-refs` file into the snapshot. Return 1 if the file - * existed and was read, or 0 if the file was absent or empty. Die on - * errors. - */ -static int load_contents(struct snapshot *snapshot) -{ - int fd; - struct stat st; - size_t size; - ssize_t bytes_read; - - fd = open(snapshot->refs->path, O_RDONLY); - if (fd < 0) { - if (errno == ENOENT) { - /* - * This is OK; it just means that no - * "packed-refs" file has been written yet, - * which is equivalent to it being empty, - * which is its state when initialized with - * zeros. - */ - return 0; - } else { - die_errno("couldn't read %s", snapshot->refs->path); - } - } - - stat_validity_update(&snapshot->validity, fd); - - if (fstat(fd, &st) < 0) - die_errno("couldn't stat %s", snapshot->refs->path); - size = xsize_t(st.st_size); - - if (!size) { - close(fd); - return 0; - } else if (mmap_strategy == MMAP_NONE || size <= SMALL_FILE_SIZE) { - snapshot->buf = xmalloc(size); - bytes_read = read_in_full(fd, snapshot->buf, size); - if (bytes_read < 0 || bytes_read != size) - die_errno("couldn't read %s", snapshot->refs->path); - snapshot->mmapped = 0; - } else { - snapshot->buf = xmmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0); - snapshot->mmapped = 1; - } - close(fd); - - snapshot->start = snapshot->buf; - snapshot->eof = snapshot->buf + size; - - return 1; -} - -/* - * Find the place in `snapshot->buf` where the start of the record for - * `refname` starts. If `mustexist` is true and the reference doesn't - * exist, then return NULL. If `mustexist` is false and the reference - * doesn't exist, then return the point where that reference would be - * inserted, or `snapshot->eof` (which might be NULL) if it would be - * inserted at the end of the file. In the latter mode, `refname` - * doesn't have to be a proper reference name; for example, one could - * search for "refs/replace/" to find the start of any replace - * references. - * - * The record is sought using a binary search, so `snapshot->buf` must - * be sorted. - */ -static const char *find_reference_location(struct snapshot *snapshot, - const char *refname, int mustexist) -{ - /* - * This is not *quite* a garden-variety binary search, because - * the data we're searching is made up of records, and we - * always need to find the beginning of a record to do a - * comparison. A "record" here is one line for the reference - * itself and zero or one peel lines that start with '^'. Our - * loop invariant is described in the next two comments. - */ - - /* - * A pointer to the character at the start of a record whose - * preceding records all have reference names that come - * *before* `refname`. - */ - const char *lo = snapshot->start; - - /* - * A pointer to a the first character of a record whose - * reference name comes *after* `refname`. - */ - const char *hi = snapshot->eof; - - while (lo != hi) { - const char *mid, *rec; - int cmp; - - mid = lo + (hi - lo) / 2; - rec = find_start_of_record(lo, mid); - cmp = cmp_record_to_refname(rec, refname); - if (cmp < 0) { - lo = find_end_of_record(mid, hi); - } else if (cmp > 0) { - hi = rec; - } else { - return rec; - } - } - - if (mustexist) - return NULL; - else - return lo; -} - -/* - * Create a newly-allocated `snapshot` of the `packed-refs` file in - * its current state and return it. The return value will already have - * its reference count incremented. - * - * A comment line of the form "# pack-refs with: " may contain zero or - * more traits. We interpret the traits as follows: - * - * Neither `peeled` nor `fully-peeled`: - * - * Probably no references are peeled. But if the file contains a - * peeled value for a reference, we will use it. - * - * `peeled`: - * - * References under "refs/tags/", if they *can* be peeled, *are* - * peeled in this file. References outside of "refs/tags/" are - * probably not peeled even if they could have been, but if we find - * a peeled value for such a reference we will use it. - * - * `fully-peeled`: - * - * All references in the file that can be peeled are peeled. - * Inversely (and this is more important), any references in the - * file for which no peeled value is recorded is not peelable. This - * trait should typically be written alongside "peeled" for - * compatibility with older clients, but we do not require it - * (i.e., "peeled" is a no-op if "fully-peeled" is set). - * - * `sorted`: - * - * The references in this file are known to be sorted by refname. - */ -static struct snapshot *create_snapshot(struct packed_ref_store *refs) -{ - struct snapshot *snapshot = xcalloc(1, sizeof(*snapshot)); - int sorted = 0; - - snapshot->refs = refs; - acquire_snapshot(snapshot); - snapshot->peeled = PEELED_NONE; - - if (!load_contents(snapshot)) - return snapshot; - - /* If the file has a header line, process it: */ - if (snapshot->buf < snapshot->eof && *snapshot->buf == '#') { - char *tmp, *p, *eol; - struct string_list traits = STRING_LIST_INIT_NODUP; - - eol = memchr(snapshot->buf, '\n', - snapshot->eof - snapshot->buf); - if (!eol) - die_unterminated_line(refs->path, - snapshot->buf, - snapshot->eof - snapshot->buf); - - tmp = xmemdupz(snapshot->buf, eol - snapshot->buf); - - if (!skip_prefix(tmp, "# pack-refs with:", (const char **)&p)) - die_invalid_line(refs->path, - snapshot->buf, - snapshot->eof - snapshot->buf); - - string_list_split_in_place(&traits, p, ' ', -1); - - if (unsorted_string_list_has_string(&traits, "fully-peeled")) - snapshot->peeled = PEELED_FULLY; - else if (unsorted_string_list_has_string(&traits, "peeled")) - snapshot->peeled = PEELED_TAGS; - - sorted = unsorted_string_list_has_string(&traits, "sorted"); - - /* perhaps other traits later as well */ - - /* The "+ 1" is for the LF character. */ - snapshot->start = eol + 1; - - string_list_clear(&traits, 0); - free(tmp); - } - - verify_buffer_safe(snapshot); - - if (!sorted) { - sort_snapshot(snapshot); - - /* - * Reordering the records might have moved a short one - * to the end of the buffer, so verify the buffer's - * safety again: - */ - verify_buffer_safe(snapshot); - } - - if (mmap_strategy != MMAP_OK && snapshot->mmapped) { - /* - * We don't want to leave the file mmapped, so we are - * forced to make a copy now: - */ - size_t size = snapshot->eof - snapshot->start; - char *buf_copy = xmalloc(size); - - memcpy(buf_copy, snapshot->start, size); - clear_snapshot_buffer(snapshot); - snapshot->buf = snapshot->start = buf_copy; - snapshot->eof = buf_copy + size; - } - - return snapshot; -} - -/* - * Check that `refs->snapshot` (if present) still reflects the - * contents of the `packed-refs` file. If not, clear the snapshot. - */ -static void validate_snapshot(struct packed_ref_store *refs) -{ - if (refs->snapshot && - !stat_validity_check(&refs->snapshot->validity, refs->path)) - clear_snapshot(refs); -} - -/* - * Get the `snapshot` for the specified packed_ref_store, creating and - * populating it if it hasn't been read before or if the file has been - * changed (according to its `validity` field) since it was last read. - * On the other hand, if we hold the lock, then assume that the file - * hasn't been changed out from under us, so skip the extra `stat()` - * call in `stat_validity_check()`. This function does *not* increase - * the snapshot's reference count on behalf of the caller. - */ -static struct snapshot *get_snapshot(struct packed_ref_store *refs) -{ - if (!is_lock_file_locked(&refs->lock)) - validate_snapshot(refs); - - if (!refs->snapshot) - refs->snapshot = create_snapshot(refs); - - return refs->snapshot; -} - -static int packed_read_raw_ref(struct ref_store *ref_store, - const char *refname, struct object_id *oid, - struct strbuf *referent, unsigned int *type) -{ - struct packed_ref_store *refs = - packed_downcast(ref_store, REF_STORE_READ, "read_raw_ref"); - struct snapshot *snapshot = get_snapshot(refs); - const char *rec; - - *type = 0; - - rec = find_reference_location(snapshot, refname, 1); - - if (!rec) { - /* refname is not a packed reference. */ - errno = ENOENT; - return -1; - } - - if (get_oid_hex(rec, oid)) - die_invalid_line(refs->path, rec, snapshot->eof - rec); - - *type = REF_ISPACKED; - return 0; -} - -/* - * This value is set in `base.flags` if the peeled value of the - * current reference is known. In that case, `peeled` contains the - * correct peeled value for the reference, which might be `null_oid` - * if the reference is not a tag or if it is broken. - */ -#define REF_KNOWS_PEELED 0x40 - -/* - * An iterator over a snapshot of a `packed-refs` file. - */ -struct packed_ref_iterator { - struct ref_iterator base; - - struct snapshot *snapshot; - - /* The current position in the snapshot's buffer: */ - const char *pos; - - /* The end of the part of the buffer that will be iterated over: */ - const char *eof; - - /* Scratch space for current values: */ - struct object_id oid, peeled; - struct strbuf refname_buf; - - unsigned int flags; -}; - -/* - * Move the iterator to the next record in the snapshot, without - * respect for whether the record is actually required by the current - * iteration. Adjust the fields in `iter` and return `ITER_OK` or - * `ITER_DONE`. This function does not free the iterator in the case - * of `ITER_DONE`. - */ -static int next_record(struct packed_ref_iterator *iter) -{ - const char *p = iter->pos, *eol; - - strbuf_reset(&iter->refname_buf); - - if (iter->pos == iter->eof) - return ITER_DONE; - - iter->base.flags = REF_ISPACKED; - - if (iter->eof - p < the_hash_algo->hexsz + 2 || - parse_oid_hex(p, &iter->oid, &p) || - !isspace(*p++)) - die_invalid_line(iter->snapshot->refs->path, - iter->pos, iter->eof - iter->pos); - - eol = memchr(p, '\n', iter->eof - p); - if (!eol) - die_unterminated_line(iter->snapshot->refs->path, - iter->pos, iter->eof - iter->pos); - - strbuf_add(&iter->refname_buf, p, eol - p); - iter->base.refname = iter->refname_buf.buf; - - if (check_refname_format(iter->base.refname, REFNAME_ALLOW_ONELEVEL)) { - if (!refname_is_safe(iter->base.refname)) - die("packed refname is dangerous: %s", - iter->base.refname); - oidclr(&iter->oid); - iter->base.flags |= REF_BAD_NAME | REF_ISBROKEN; - } - if (iter->snapshot->peeled == PEELED_FULLY || - (iter->snapshot->peeled == PEELED_TAGS && - starts_with(iter->base.refname, "refs/tags/"))) - iter->base.flags |= REF_KNOWS_PEELED; - - iter->pos = eol + 1; - - if (iter->pos < iter->eof && *iter->pos == '^') { - p = iter->pos + 1; - if (iter->eof - p < the_hash_algo->hexsz + 1 || - parse_oid_hex(p, &iter->peeled, &p) || - *p++ != '\n') - die_invalid_line(iter->snapshot->refs->path, - iter->pos, iter->eof - iter->pos); - iter->pos = p; - - /* - * Regardless of what the file header said, we - * definitely know the value of *this* reference. But - * we suppress it if the reference is broken: - */ - if ((iter->base.flags & REF_ISBROKEN)) { - oidclr(&iter->peeled); - iter->base.flags &= ~REF_KNOWS_PEELED; - } else { - iter->base.flags |= REF_KNOWS_PEELED; - } - } else { - oidclr(&iter->peeled); - } - - return ITER_OK; -} - -static int packed_ref_iterator_advance(struct ref_iterator *ref_iterator) -{ - struct packed_ref_iterator *iter = - (struct packed_ref_iterator *)ref_iterator; - int ok; - - while ((ok = next_record(iter)) == ITER_OK) { - if (iter->flags & DO_FOR_EACH_PER_WORKTREE_ONLY && - ref_type(iter->base.refname) != REF_TYPE_PER_WORKTREE) - continue; - - if (!(iter->flags & DO_FOR_EACH_INCLUDE_BROKEN) && - !ref_resolves_to_object(iter->base.refname, &iter->oid, - iter->flags)) - continue; - - return ITER_OK; - } - - if (ref_iterator_abort(ref_iterator) != ITER_DONE) - ok = ITER_ERROR; - - return ok; -} - -static int packed_ref_iterator_peel(struct ref_iterator *ref_iterator, - struct object_id *peeled) -{ - struct packed_ref_iterator *iter = - (struct packed_ref_iterator *)ref_iterator; - - if ((iter->base.flags & REF_KNOWS_PEELED)) { - oidcpy(peeled, &iter->peeled); - return is_null_oid(&iter->peeled) ? -1 : 0; - } else if ((iter->base.flags & (REF_ISBROKEN | REF_ISSYMREF))) { - return -1; - } else { - return !!peel_object(&iter->oid, peeled); - } -} - -static int packed_ref_iterator_abort(struct ref_iterator *ref_iterator) -{ - struct packed_ref_iterator *iter = - (struct packed_ref_iterator *)ref_iterator; - int ok = ITER_DONE; - - strbuf_release(&iter->refname_buf); - release_snapshot(iter->snapshot); - base_ref_iterator_free(ref_iterator); - return ok; -} - -static struct ref_iterator_vtable packed_ref_iterator_vtable = { - packed_ref_iterator_advance, - packed_ref_iterator_peel, - packed_ref_iterator_abort -}; - -static struct ref_iterator *packed_ref_iterator_begin( - struct ref_store *ref_store, - const char *prefix, unsigned int flags) -{ - struct packed_ref_store *refs; - struct snapshot *snapshot; - const char *start; - struct packed_ref_iterator *iter; - struct ref_iterator *ref_iterator; - unsigned int required_flags = REF_STORE_READ; - - if (!(flags & DO_FOR_EACH_INCLUDE_BROKEN)) - required_flags |= REF_STORE_ODB; - refs = packed_downcast(ref_store, required_flags, "ref_iterator_begin"); - - /* - * Note that `get_snapshot()` internally checks whether the - * snapshot is up to date with what is on disk, and re-reads - * it if not. - */ - snapshot = get_snapshot(refs); - - if (prefix && *prefix) - start = find_reference_location(snapshot, prefix, 0); - else - start = snapshot->start; - - if (start == snapshot->eof) - return empty_ref_iterator_begin(); - - iter = xcalloc(1, sizeof(*iter)); - ref_iterator = &iter->base; - base_ref_iterator_init(ref_iterator, &packed_ref_iterator_vtable, 1); - - iter->snapshot = snapshot; - acquire_snapshot(snapshot); - - iter->pos = start; - iter->eof = snapshot->eof; - strbuf_init(&iter->refname_buf, 0); - - iter->base.oid = &iter->oid; - - iter->flags = flags; - - if (prefix && *prefix) - /* Stop iteration after we've gone *past* prefix: */ - ref_iterator = prefix_ref_iterator_begin(ref_iterator, prefix, 0); - - return ref_iterator; -} - -/* - * Write an entry to the packed-refs file for the specified refname. - * If peeled is non-NULL, write it as the entry's peeled value. On - * error, return a nonzero value and leave errno set at the value left - * by the failing call to `fprintf()`. - */ -static int write_packed_entry(FILE *fh, const char *refname, - const struct object_id *oid, - const struct object_id *peeled) -{ - if (fprintf(fh, "%s %s\n", oid_to_hex(oid), refname) < 0 || - (peeled && fprintf(fh, "^%s\n", oid_to_hex(peeled)) < 0)) - return -1; - - return 0; -} - -int packed_refs_lock(struct ref_store *ref_store, int flags, struct strbuf *err) -{ - struct packed_ref_store *refs = - packed_downcast(ref_store, REF_STORE_WRITE | REF_STORE_MAIN, - "packed_refs_lock"); - static int timeout_configured = 0; - static int timeout_value = 1000; - - if (!timeout_configured) { - git_config_get_int("core.packedrefstimeout", &timeout_value); - timeout_configured = 1; - } - - /* - * Note that we close the lockfile immediately because we - * don't write new content to it, but rather to a separate - * tempfile. - */ - if (hold_lock_file_for_update_timeout( - &refs->lock, - refs->path, - flags, timeout_value) < 0) { - unable_to_lock_message(refs->path, errno, err); - return -1; - } - - if (close_lock_file_gently(&refs->lock)) { - strbuf_addf(err, "unable to close %s: %s", refs->path, strerror(errno)); - rollback_lock_file(&refs->lock); - return -1; - } - - /* - * There is a stat-validity problem might cause `update-ref -d` - * lost the newly commit of a ref, because a new `packed-refs` - * file might has the same on-disk file attributes such as - * timestamp, file size and inode value, but has a changed - * ref value. - * - * This could happen with a very small chance when - * `update-ref -d` is called and at the same time another - * `pack-refs --all` process is running. - * - * Now that we hold the `packed-refs` lock, it is important - * to make sure we could read the latest version of - * `packed-refs` file no matter we have just mmap it or not. - * So what need to do is clear the snapshot if we hold it - * already. - */ - clear_snapshot(refs); - - /* - * Now make sure that the packed-refs file as it exists in the - * locked state is loaded into the snapshot: - */ - get_snapshot(refs); - return 0; -} - -void packed_refs_unlock(struct ref_store *ref_store) -{ - struct packed_ref_store *refs = packed_downcast( - ref_store, - REF_STORE_READ | REF_STORE_WRITE, - "packed_refs_unlock"); - - if (!is_lock_file_locked(&refs->lock)) - BUG("packed_refs_unlock() called when not locked"); - rollback_lock_file(&refs->lock); -} - -int packed_refs_is_locked(struct ref_store *ref_store) -{ - struct packed_ref_store *refs = packed_downcast( - ref_store, - REF_STORE_READ | REF_STORE_WRITE, - "packed_refs_is_locked"); - - return is_lock_file_locked(&refs->lock); -} - -/* - * The packed-refs header line that we write out. Perhaps other traits - * will be added later. - * - * Note that earlier versions of Git used to parse these traits by - * looking for " trait " in the line. For this reason, the space after - * the colon and the trailing space are required. - */ -static const char PACKED_REFS_HEADER[] = - "# pack-refs with: peeled fully-peeled sorted \n"; - -static int packed_init_db(struct ref_store *ref_store, struct strbuf *err) -{ - /* Nothing to do. */ - return 0; -} - -/* - * Write the packed refs from the current snapshot to the packed-refs - * tempfile, incorporating any changes from `updates`. `updates` must - * be a sorted string list whose keys are the refnames and whose util - * values are `struct ref_update *`. On error, rollback the tempfile, - * write an error message to `err`, and return a nonzero value. - * - * The packfile must be locked before calling this function and will - * remain locked when it is done. - */ -static int write_with_updates(struct packed_ref_store *refs, - struct string_list *updates, - struct strbuf *err) -{ - struct ref_iterator *iter = NULL; - size_t i; - int ok; - FILE *out; - struct strbuf sb = STRBUF_INIT; - char *packed_refs_path; - - if (!is_lock_file_locked(&refs->lock)) - BUG("write_with_updates() called while unlocked"); - - /* - * If packed-refs is a symlink, we want to overwrite the - * symlinked-to file, not the symlink itself. Also, put the - * staging file next to it: - */ - packed_refs_path = get_locked_file_path(&refs->lock); - strbuf_addf(&sb, "%s.new", packed_refs_path); - free(packed_refs_path); - refs->tempfile = create_tempfile(sb.buf); - if (!refs->tempfile) { - strbuf_addf(err, "unable to create file %s: %s", - sb.buf, strerror(errno)); - strbuf_release(&sb); - return -1; - } - strbuf_release(&sb); - - out = fdopen_tempfile(refs->tempfile, "w"); - if (!out) { - strbuf_addf(err, "unable to fdopen packed-refs tempfile: %s", - strerror(errno)); - goto error; - } - - if (fprintf(out, "%s", PACKED_REFS_HEADER) < 0) - goto write_error; - - /* - * We iterate in parallel through the current list of refs and - * the list of updates, processing an entry from at least one - * of the lists each time through the loop. When the current - * list of refs is exhausted, set iter to NULL. When the list - * of updates is exhausted, leave i set to updates->nr. - */ - iter = packed_ref_iterator_begin(&refs->base, "", - DO_FOR_EACH_INCLUDE_BROKEN); - if ((ok = ref_iterator_advance(iter)) != ITER_OK) - iter = NULL; - - i = 0; - - while (iter || i < updates->nr) { - struct ref_update *update = NULL; - int cmp; - - if (i >= updates->nr) { - cmp = -1; - } else { - update = updates->items[i].util; - - if (!iter) - cmp = +1; - else - cmp = strcmp(iter->refname, update->refname); - } - - if (!cmp) { - /* - * There is both an old value and an update - * for this reference. Check the old value if - * necessary: - */ - if ((update->flags & REF_HAVE_OLD)) { - if (is_null_oid(&update->old_oid)) { - strbuf_addf(err, "cannot update ref '%s': " - "reference already exists", - update->refname); - goto error; - } else if (!oideq(&update->old_oid, iter->oid)) { - strbuf_addf(err, "cannot update ref '%s': " - "is at %s but expected %s", - update->refname, - oid_to_hex(iter->oid), - oid_to_hex(&update->old_oid)); - goto error; - } - } - - /* Now figure out what to use for the new value: */ - if ((update->flags & REF_HAVE_NEW)) { - /* - * The update takes precedence. Skip - * the iterator over the unneeded - * value. - */ - if ((ok = ref_iterator_advance(iter)) != ITER_OK) - iter = NULL; - cmp = +1; - } else { - /* - * The update doesn't actually want to - * change anything. We're done with it. - */ - i++; - cmp = -1; - } - } else if (cmp > 0) { - /* - * There is no old value but there is an - * update for this reference. Make sure that - * the update didn't expect an existing value: - */ - if ((update->flags & REF_HAVE_OLD) && - !is_null_oid(&update->old_oid)) { - strbuf_addf(err, "cannot update ref '%s': " - "reference is missing but expected %s", - update->refname, - oid_to_hex(&update->old_oid)); - goto error; - } - } - - if (cmp < 0) { - /* Pass the old reference through. */ - - struct object_id peeled; - int peel_error = ref_iterator_peel(iter, &peeled); - - if (write_packed_entry(out, iter->refname, - iter->oid, - peel_error ? NULL : &peeled)) - goto write_error; - - if ((ok = ref_iterator_advance(iter)) != ITER_OK) - iter = NULL; - } else if (is_null_oid(&update->new_oid)) { - /* - * The update wants to delete the reference, - * and the reference either didn't exist or we - * have already skipped it. So we're done with - * the update (and don't have to write - * anything). - */ - i++; - } else { - struct object_id peeled; - int peel_error = peel_object(&update->new_oid, - &peeled); - - if (write_packed_entry(out, update->refname, - &update->new_oid, - peel_error ? NULL : &peeled)) - goto write_error; - - i++; - } - } - - if (ok != ITER_DONE) { - strbuf_addstr(err, "unable to write packed-refs file: " - "error iterating over old contents"); - goto error; - } - - if (close_tempfile_gently(refs->tempfile)) { - strbuf_addf(err, "error closing file %s: %s", - get_tempfile_path(refs->tempfile), - strerror(errno)); - strbuf_release(&sb); - delete_tempfile(&refs->tempfile); - return -1; - } - - return 0; - -write_error: - strbuf_addf(err, "error writing to %s: %s", - get_tempfile_path(refs->tempfile), strerror(errno)); - -error: - if (iter) - ref_iterator_abort(iter); - - delete_tempfile(&refs->tempfile); - return -1; -} - -int is_packed_transaction_needed(struct ref_store *ref_store, - struct ref_transaction *transaction) -{ - struct packed_ref_store *refs = packed_downcast( - ref_store, - REF_STORE_READ, - "is_packed_transaction_needed"); - struct strbuf referent = STRBUF_INIT; - size_t i; - int ret; - - if (!is_lock_file_locked(&refs->lock)) - BUG("is_packed_transaction_needed() called while unlocked"); - - /* - * We're only going to bother returning false for the common, - * trivial case that references are only being deleted, their - * old values are not being checked, and the old `packed-refs` - * file doesn't contain any of those reference(s). This gives - * false positives for some other cases that could - * theoretically be optimized away: - * - * 1. It could be that the old value is being verified without - * setting a new value. In this case, we could verify the - * old value here and skip the update if it agrees. If it - * disagrees, we could either let the update go through - * (the actual commit would re-detect and report the - * problem), or come up with a way of reporting such an - * error to *our* caller. - * - * 2. It could be that a new value is being set, but that it - * is identical to the current packed value of the - * reference. - * - * Neither of these cases will come up in the current code, - * because the only caller of this function passes to it a - * transaction that only includes `delete` updates with no - * `old_id`. Even if that ever changes, false positives only - * cause an optimization to be missed; they do not affect - * correctness. - */ - - /* - * Start with the cheap checks that don't require old - * reference values to be read: - */ - for (i = 0; i < transaction->nr; i++) { - struct ref_update *update = transaction->updates[i]; - - if (update->flags & REF_HAVE_OLD) - /* Have to check the old value -> needed. */ - return 1; - - if ((update->flags & REF_HAVE_NEW) && !is_null_oid(&update->new_oid)) - /* Have to set a new value -> needed. */ - return 1; - } - - /* - * The transaction isn't checking any old values nor is it - * setting any nonzero new values, so it still might be able - * to be skipped. Now do the more expensive check: the update - * is needed if any of the updates is a delete, and the old - * `packed-refs` file contains a value for that reference. - */ - ret = 0; - for (i = 0; i < transaction->nr; i++) { - struct ref_update *update = transaction->updates[i]; - unsigned int type; - struct object_id oid; - - if (!(update->flags & REF_HAVE_NEW)) - /* - * This reference isn't being deleted -> not - * needed. - */ - continue; - - if (!refs_read_raw_ref(ref_store, update->refname, - &oid, &referent, &type) || - errno != ENOENT) { - /* - * We have to actually delete that reference - * -> this transaction is needed. - */ - ret = 1; - break; - } - } - - strbuf_release(&referent); - return ret; -} - -struct packed_transaction_backend_data { - /* True iff the transaction owns the packed-refs lock. */ - int own_lock; - - struct string_list updates; -}; - -static void packed_transaction_cleanup(struct packed_ref_store *refs, - struct ref_transaction *transaction) -{ - struct packed_transaction_backend_data *data = transaction->backend_data; - - if (data) { - string_list_clear(&data->updates, 0); - - if (is_tempfile_active(refs->tempfile)) - delete_tempfile(&refs->tempfile); - - if (data->own_lock && is_lock_file_locked(&refs->lock)) { - packed_refs_unlock(&refs->base); - data->own_lock = 0; - } - - free(data); - transaction->backend_data = NULL; - } - - transaction->state = REF_TRANSACTION_CLOSED; -} - -static int packed_transaction_prepare(struct ref_store *ref_store, - struct ref_transaction *transaction, - struct strbuf *err) -{ - struct packed_ref_store *refs = packed_downcast( - ref_store, - REF_STORE_READ | REF_STORE_WRITE | REF_STORE_ODB, - "ref_transaction_prepare"); - struct packed_transaction_backend_data *data; - size_t i; - int ret = TRANSACTION_GENERIC_ERROR; - - /* - * Note that we *don't* skip transactions with zero updates, - * because such a transaction might be executed for the side - * effect of ensuring that all of the references are peeled or - * ensuring that the `packed-refs` file is sorted. If the - * caller wants to optimize away empty transactions, it should - * do so itself. - */ - - data = xcalloc(1, sizeof(*data)); - string_list_init(&data->updates, 0); - - transaction->backend_data = data; - - /* - * Stick the updates in a string list by refname so that we - * can sort them: - */ - for (i = 0; i < transaction->nr; i++) { - struct ref_update *update = transaction->updates[i]; - struct string_list_item *item = - string_list_append(&data->updates, update->refname); - - /* Store a pointer to update in item->util: */ - item->util = update; - } - string_list_sort(&data->updates); - - if (ref_update_reject_duplicates(&data->updates, err)) - goto failure; - - if (!is_lock_file_locked(&refs->lock)) { - if (packed_refs_lock(ref_store, 0, err)) - goto failure; - data->own_lock = 1; - } - - if (write_with_updates(refs, &data->updates, err)) - goto failure; - - transaction->state = REF_TRANSACTION_PREPARED; - return 0; - -failure: - packed_transaction_cleanup(refs, transaction); - return ret; -} - -static int packed_transaction_abort(struct ref_store *ref_store, - struct ref_transaction *transaction, - struct strbuf *err) -{ - struct packed_ref_store *refs = packed_downcast( - ref_store, - REF_STORE_READ | REF_STORE_WRITE | REF_STORE_ODB, - "ref_transaction_abort"); - - packed_transaction_cleanup(refs, transaction); - return 0; -} - -static int packed_transaction_finish(struct ref_store *ref_store, - struct ref_transaction *transaction, - struct strbuf *err) -{ - struct packed_ref_store *refs = packed_downcast( - ref_store, - REF_STORE_READ | REF_STORE_WRITE | REF_STORE_ODB, - "ref_transaction_finish"); - int ret = TRANSACTION_GENERIC_ERROR; - char *packed_refs_path; - - clear_snapshot(refs); - - packed_refs_path = get_locked_file_path(&refs->lock); - if (rename_tempfile(&refs->tempfile, packed_refs_path)) { - strbuf_addf(err, "error replacing %s: %s", - refs->path, strerror(errno)); - goto cleanup; - } - - ret = 0; - -cleanup: - free(packed_refs_path); - packed_transaction_cleanup(refs, transaction); - return ret; -} - -static int packed_initial_transaction_commit(struct ref_store *ref_store, - struct ref_transaction *transaction, - struct strbuf *err) -{ - return ref_transaction_commit(transaction, err); -} - -static int packed_delete_refs(struct ref_store *ref_store, const char *msg, - struct string_list *refnames, unsigned int flags) -{ - struct packed_ref_store *refs = - packed_downcast(ref_store, REF_STORE_WRITE, "delete_refs"); - struct strbuf err = STRBUF_INIT; - struct ref_transaction *transaction; - struct string_list_item *item; - int ret; - - (void)refs; /* We need the check above, but don't use the variable */ - - if (!refnames->nr) - return 0; - - /* - * Since we don't check the references' old_oids, the - * individual updates can't fail, so we can pack all of the - * updates into a single transaction. - */ - - transaction = ref_store_transaction_begin(ref_store, &err); - if (!transaction) - return -1; - - for_each_string_list_item(item, refnames) { - if (ref_transaction_delete(transaction, item->string, NULL, - flags, msg, &err)) { - warning(_("could not delete reference %s: %s"), - item->string, err.buf); - strbuf_reset(&err); - } - } - - ret = ref_transaction_commit(transaction, &err); - - if (ret) { - if (refnames->nr == 1) - error(_("could not delete reference %s: %s"), - refnames->items[0].string, err.buf); - else - error(_("could not delete references: %s"), err.buf); - } - - ref_transaction_free(transaction); - strbuf_release(&err); - return ret; -} - -static int packed_pack_refs(struct ref_store *ref_store, unsigned int flags) -{ - /* - * Packed refs are already packed. It might be that loose refs - * are packed *into* a packed refs store, but that is done by - * updating the packed references via a transaction. - */ - return 0; -} - -static int packed_create_symref(struct ref_store *ref_store, - const char *refname, const char *target, - const char *logmsg) -{ - BUG("packed reference store does not support symrefs"); -} - -static int packed_rename_ref(struct ref_store *ref_store, - const char *oldrefname, const char *newrefname, - const char *logmsg) -{ - BUG("packed reference store does not support renaming references"); -} - -static int packed_copy_ref(struct ref_store *ref_store, - const char *oldrefname, const char *newrefname, - const char *logmsg) -{ - BUG("packed reference store does not support copying references"); -} - -static struct ref_iterator *packed_reflog_iterator_begin(struct ref_store *ref_store) -{ - return empty_ref_iterator_begin(); -} - -static int packed_for_each_reflog_ent(struct ref_store *ref_store, - const char *refname, - each_reflog_ent_fn fn, void *cb_data) -{ - return 0; -} - -static int packed_for_each_reflog_ent_reverse(struct ref_store *ref_store, - const char *refname, - each_reflog_ent_fn fn, - void *cb_data) -{ - return 0; -} - -static int packed_reflog_exists(struct ref_store *ref_store, - const char *refname) -{ - return 0; -} - -static int packed_create_reflog(struct ref_store *ref_store, - const char *refname, int force_create, - struct strbuf *err) -{ - BUG("packed reference store does not support reflogs"); -} - -static int packed_delete_reflog(struct ref_store *ref_store, - const char *refname) -{ - return 0; -} - -static int packed_reflog_expire(struct ref_store *ref_store, - const char *refname, const struct object_id *oid, - unsigned int flags, - reflog_expiry_prepare_fn prepare_fn, - reflog_expiry_should_prune_fn should_prune_fn, - reflog_expiry_cleanup_fn cleanup_fn, - void *policy_cb_data) -{ - return 0; -} - -struct ref_storage_be refs_be_packed = { - NULL, - "packed", - packed_ref_store_create, - packed_init_db, - packed_transaction_prepare, - packed_transaction_finish, - packed_transaction_abort, - packed_initial_transaction_commit, - - packed_pack_refs, - packed_create_symref, - packed_delete_refs, - packed_rename_ref, - packed_copy_ref, - - packed_ref_iterator_begin, - packed_read_raw_ref, - - packed_reflog_iterator_begin, - packed_for_each_reflog_ent, - packed_for_each_reflog_ent_reverse, - packed_reflog_exists, - packed_create_reflog, - packed_delete_reflog, - packed_reflog_expire -}; |