diff options
Diffstat (limited to 'refs')
| -rw-r--r-- | refs/files-backend.c | 1107 | ||||
| -rw-r--r-- | refs/iterator.c | 47 | ||||
| -rw-r--r-- | refs/packed-backend.c | 1558 | ||||
| -rw-r--r-- | refs/packed-backend.h | 26 | ||||
| -rw-r--r-- | refs/ref-cache.c | 44 | ||||
| -rw-r--r-- | refs/ref-cache.h | 35 | ||||
| -rw-r--r-- | refs/refs-internal.h | 47 |
7 files changed, 2055 insertions, 809 deletions
diff --git a/refs/files-backend.c b/refs/files-backend.c index 0404f2c233..014dabb0bf 100644 --- a/refs/files-backend.c +++ b/refs/files-backend.c @@ -3,6 +3,7 @@ #include "../refs.h" #include "refs-internal.h" #include "ref-cache.h" +#include "packed-backend.h" #include "../iterator.h" #include "../dir-iterator.h" #include "../lockfile.h" @@ -11,44 +12,11 @@ struct ref_lock { char *ref_name; - struct lock_file *lk; + struct lock_file lk; struct object_id old_oid; }; /* - * Return true if refname, which has the specified oid and flags, can - * be resolved to an object in the database. If the referred-to object - * does not exist, emit a warning and return false. - */ -static int ref_resolves_to_object(const char *refname, - const struct object_id *oid, - unsigned int flags) -{ - if (flags & REF_ISBROKEN) - return 0; - if (!has_sha1_file(oid->hash)) { - error("%s does not point to a valid object!", refname); - return 0; - } - return 1; -} - -struct packed_ref_cache { - struct ref_cache *cache; - - /* - * Count of references to the data structure in this instance, - * including the pointer from files_ref_store::packed if any. - * The data will not be freed as long as the reference count - * is nonzero. - */ - unsigned int referrers; - - /* The metadata from when this packed-refs cache was read */ - struct stat_validity validity; -}; - -/* * Future: need to be in "struct repository" * when doing a full libification. */ @@ -58,54 +26,12 @@ struct files_ref_store { char *gitdir; char *gitcommondir; - char *packed_refs_path; struct ref_cache *loose; - struct packed_ref_cache *packed; - /* - * Lock used for the "packed-refs" file. Note that this (and - * thus the enclosing `files_ref_store`) must not be freed. - */ - struct lock_file packed_refs_lock; + struct ref_store *packed_ref_store; }; -/* - * Increment the reference count of *packed_refs. - */ -static void acquire_packed_ref_cache(struct packed_ref_cache *packed_refs) -{ - packed_refs->referrers++; -} - -/* - * Decrease the reference count of *packed_refs. If it goes to zero, - * free *packed_refs and return true; otherwise return false. - */ -static int release_packed_ref_cache(struct packed_ref_cache *packed_refs) -{ - if (!--packed_refs->referrers) { - free_ref_cache(packed_refs->cache); - stat_validity_clear(&packed_refs->validity); - free(packed_refs); - return 1; - } else { - return 0; - } -} - -static void clear_packed_ref_cache(struct files_ref_store *refs) -{ - if (refs->packed) { - struct packed_ref_cache *packed_refs = refs->packed; - - if (is_lock_file_locked(&refs->packed_refs_lock)) - die("BUG: packed-ref cache cleared while locked"); - refs->packed = NULL; - release_packed_ref_cache(packed_refs); - } -} - static void clear_loose_ref_cache(struct files_ref_store *refs) { if (refs->loose) { @@ -132,7 +58,8 @@ static struct ref_store *files_ref_store_create(const char *gitdir, get_common_dir_noenv(&sb, gitdir); refs->gitcommondir = strbuf_detach(&sb, NULL); strbuf_addf(&sb, "%s/packed-refs", refs->gitcommondir); - refs->packed_refs_path = strbuf_detach(&sb, NULL); + refs->packed_ref_store = packed_ref_store_create(sb.buf, flags); + strbuf_release(&sb); return ref_store; } @@ -175,169 +102,10 @@ static struct files_ref_store *files_downcast(struct ref_store *ref_store, return refs; } -/* The length of a peeled reference line in packed-refs, including EOL: */ -#define PEELED_LINE_LENGTH 42 - -/* - * The packed-refs header line that we write out. Perhaps other - * traits will be added later. The trailing space is required. - */ -static const char PACKED_REFS_HEADER[] = - "# pack-refs with: peeled fully-peeled \n"; - -/* - * Parse one line from a packed-refs file. Write the SHA1 to sha1. - * Return a pointer to the refname within the line (null-terminated), - * or NULL if there was a problem. - */ -static const char *parse_ref_line(struct strbuf *line, struct object_id *oid) -{ - const char *ref; - - if (parse_oid_hex(line->buf, oid, &ref) < 0) - return NULL; - if (!isspace(*ref++)) - return NULL; - - if (isspace(*ref)) - return NULL; - - if (line->buf[line->len - 1] != '\n') - return NULL; - line->buf[--line->len] = 0; - - return ref; -} - -/* - * Read from `packed_refs_file` into a newly-allocated - * `packed_ref_cache` 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: - * - * No traits: - * - * 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). - */ -static struct packed_ref_cache *read_packed_refs(const char *packed_refs_file) -{ - FILE *f; - struct packed_ref_cache *packed_refs = xcalloc(1, sizeof(*packed_refs)); - struct ref_entry *last = NULL; - struct strbuf line = STRBUF_INIT; - enum { PEELED_NONE, PEELED_TAGS, PEELED_FULLY } peeled = PEELED_NONE; - struct ref_dir *dir; - - acquire_packed_ref_cache(packed_refs); - packed_refs->cache = create_ref_cache(NULL, NULL); - packed_refs->cache->root->flag &= ~REF_INCOMPLETE; - - f = fopen(packed_refs_file, "r"); - if (!f) { - 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. - */ - return packed_refs; - } else { - die_errno("couldn't read %s", packed_refs_file); - } - } - - stat_validity_update(&packed_refs->validity, fileno(f)); - - dir = get_ref_dir(packed_refs->cache->root); - while (strbuf_getwholeline(&line, f, '\n') != EOF) { - struct object_id oid; - const char *refname; - const char *traits; - - if (skip_prefix(line.buf, "# pack-refs with:", &traits)) { - if (strstr(traits, " fully-peeled ")) - peeled = PEELED_FULLY; - else if (strstr(traits, " peeled ")) - peeled = PEELED_TAGS; - /* perhaps other traits later as well */ - continue; - } - - refname = parse_ref_line(&line, &oid); - if (refname) { - int flag = REF_ISPACKED; - - if (check_refname_format(refname, REFNAME_ALLOW_ONELEVEL)) { - if (!refname_is_safe(refname)) - die("packed refname is dangerous: %s", refname); - oidclr(&oid); - flag |= REF_BAD_NAME | REF_ISBROKEN; - } - last = create_ref_entry(refname, &oid, flag); - if (peeled == PEELED_FULLY || - (peeled == PEELED_TAGS && starts_with(refname, "refs/tags/"))) - last->flag |= REF_KNOWS_PEELED; - add_ref_entry(dir, last); - continue; - } - if (last && - line.buf[0] == '^' && - line.len == PEELED_LINE_LENGTH && - line.buf[PEELED_LINE_LENGTH - 1] == '\n' && - !get_oid_hex(line.buf + 1, &oid)) { - oidcpy(&last->u.value.peeled, &oid); - /* - * Regardless of what the file header said, - * we definitely know the value of *this* - * reference: - */ - last->flag |= REF_KNOWS_PEELED; - } - } - - fclose(f); - strbuf_release(&line); - - return packed_refs; -} - -static const char *files_packed_refs_path(struct files_ref_store *refs) -{ - return refs->packed_refs_path; -} - static void files_reflog_path(struct files_ref_store *refs, struct strbuf *sb, const char *refname) { - if (!refname) { - /* - * FIXME: of course this is wrong in multi worktree - * setting. To be fixed real soon. - */ - strbuf_addf(sb, "%s/logs", refs->gitcommondir); - return; - } - switch (ref_type(refname)) { case REF_TYPE_PER_WORKTREE: case REF_TYPE_PSEUDOREF: @@ -371,70 +139,6 @@ static void files_ref_path(struct files_ref_store *refs, } /* - * Check that the packed refs cache (if any) still reflects the - * contents of the file. If not, clear the cache. - */ -static void validate_packed_ref_cache(struct files_ref_store *refs) -{ - if (refs->packed && - !stat_validity_check(&refs->packed->validity, - files_packed_refs_path(refs))) - clear_packed_ref_cache(refs); -} - -/* - * Get the packed_ref_cache for the specified files_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()`. - */ -static struct packed_ref_cache *get_packed_ref_cache(struct files_ref_store *refs) -{ - const char *packed_refs_file = files_packed_refs_path(refs); - - if (!is_lock_file_locked(&refs->packed_refs_lock)) - validate_packed_ref_cache(refs); - - if (!refs->packed) - refs->packed = read_packed_refs(packed_refs_file); - - return refs->packed; -} - -static struct ref_dir *get_packed_ref_dir(struct packed_ref_cache *packed_ref_cache) -{ - return get_ref_dir(packed_ref_cache->cache->root); -} - -static struct ref_dir *get_packed_refs(struct files_ref_store *refs) -{ - return get_packed_ref_dir(get_packed_ref_cache(refs)); -} - -/* - * Add a reference to the in-memory packed reference cache. This may - * only be called while the packed-refs file is locked (see - * lock_packed_refs()). To actually write the packed-refs file, call - * commit_packed_refs(). - */ -static void add_packed_ref(struct files_ref_store *refs, - const char *refname, const struct object_id *oid) -{ - struct packed_ref_cache *packed_ref_cache = get_packed_ref_cache(refs); - - if (!is_lock_file_locked(&refs->packed_refs_lock)) - die("BUG: packed refs not locked"); - - if (check_refname_format(refname, REFNAME_ALLOW_ONELEVEL)) - die("Reference has invalid format: '%s'", refname); - - add_ref_entry(get_packed_ref_dir(packed_ref_cache), - create_ref_entry(refname, oid, REF_ISPACKED)); -} - -/* * Read the loose references from the namespace dirname into dir * (without recursing). dirname must end with '/'. dir must be the * directory entry corresponding to dirname. @@ -556,39 +260,6 @@ static struct ref_cache *get_loose_ref_cache(struct files_ref_store *refs) return refs->loose; } -/* - * Return the ref_entry for the given refname from the packed - * references. If it does not exist, return NULL. - */ -static struct ref_entry *get_packed_ref(struct files_ref_store *refs, - const char *refname) -{ - return find_ref_entry(get_packed_refs(refs), refname); -} - -/* - * A loose ref file doesn't exist; check for a packed ref. - */ -static int resolve_packed_ref(struct files_ref_store *refs, - const char *refname, - unsigned char *sha1, unsigned int *flags) -{ - struct ref_entry *entry; - - /* - * The loose reference file does not exist; check for a packed - * reference. - */ - entry = get_packed_ref(refs, refname); - if (entry) { - hashcpy(sha1, entry->u.value.oid.hash); - *flags |= REF_ISPACKED; - return 0; - } - /* refname is not a packed reference. */ - return -1; -} - static int files_read_raw_ref(struct ref_store *ref_store, const char *refname, unsigned char *sha1, struct strbuf *referent, unsigned int *type) @@ -632,7 +303,8 @@ stat_ref: if (lstat(path, &st) < 0) { if (errno != ENOENT) goto out; - if (resolve_packed_ref(refs, refname, sha1, type)) { + if (refs_read_raw_ref(refs->packed_ref_store, refname, + sha1, referent, type)) { errno = ENOENT; goto out; } @@ -671,7 +343,8 @@ stat_ref: * ref is supposed to be, there could still be a * packed ref: */ - if (resolve_packed_ref(refs, refname, sha1, type)) { + if (refs_read_raw_ref(refs->packed_ref_store, refname, + sha1, referent, type)) { errno = EISDIR; goto out; } @@ -736,9 +409,7 @@ out: static void unlock_ref(struct ref_lock *lock) { - /* Do not free lock->lk -- atexit() still looks at them */ - if (lock->lk) - rollback_lock_file(lock->lk); + rollback_lock_file(&lock->lk); free(lock->ref_name); free(lock); } @@ -852,10 +523,9 @@ retry: goto error_return; } - if (!lock->lk) - lock->lk = xcalloc(1, sizeof(struct lock_file)); - - if (hold_lock_file_for_update(lock->lk, ref_file.buf, LOCK_NO_DEREF) < 0) { + if (hold_lock_file_for_update_timeout( + &lock->lk, ref_file.buf, LOCK_NO_DEREF, + get_files_ref_lock_timeout_ms()) < 0) { if (errno == ENOENT && --attempts_remaining > 0) { /* * Maybe somebody just deleted one of the @@ -950,11 +620,11 @@ retry: /* * If the ref did not exist and we are creating it, - * make sure there is no existing ref that conflicts - * with refname: + * make sure there is no existing packed ref that + * conflicts with refname: */ if (refs_verify_refname_available( - &refs->base, refname, + refs->packed_ref_store, refname, extras, skip, err)) goto error_return; } @@ -971,53 +641,9 @@ out: return ret; } -static int files_peel_ref(struct ref_store *ref_store, - const char *refname, unsigned char *sha1) -{ - struct files_ref_store *refs = - files_downcast(ref_store, REF_STORE_READ | REF_STORE_ODB, - "peel_ref"); - int flag; - unsigned char base[20]; - - if (current_ref_iter && current_ref_iter->refname == refname) { - struct object_id peeled; - - if (ref_iterator_peel(current_ref_iter, &peeled)) - return -1; - hashcpy(sha1, peeled.hash); - return 0; - } - - if (refs_read_ref_full(ref_store, refname, - RESOLVE_REF_READING, base, &flag)) - return -1; - - /* - * If the reference is packed, read its ref_entry from the - * cache in the hope that we already know its peeled value. - * We only try this optimization on packed references because - * (a) forcing the filling of the loose reference cache could - * be expensive and (b) loose references anyway usually do not - * have REF_KNOWS_PEELED. - */ - if (flag & REF_ISPACKED) { - struct ref_entry *r = get_packed_ref(refs, refname); - if (r) { - if (peel_entry(r, 0)) - return -1; - hashcpy(sha1, r->u.value.peeled.hash); - return 0; - } - } - - return peel_object(base, sha1); -} - struct files_ref_iterator { struct ref_iterator base; - struct packed_ref_cache *packed_ref_cache; struct ref_iterator *iter0; unsigned int flags; }; @@ -1070,7 +696,6 @@ static int files_ref_iterator_abort(struct ref_iterator *ref_iterator) if (iter->iter0) ok = ref_iterator_abort(iter->iter0); - release_packed_ref_cache(iter->packed_ref_cache); base_ref_iterator_free(ref_iterator); return ok; } @@ -1086,7 +711,7 @@ static struct ref_iterator *files_ref_iterator_begin( const char *prefix, unsigned int flags) { struct files_ref_store *refs; - struct ref_iterator *loose_iter, *packed_iter; + struct ref_iterator *loose_iter, *packed_iter, *overlay_iter; struct files_ref_iterator *iter; struct ref_iterator *ref_iterator; unsigned int required_flags = REF_STORE_READ; @@ -1096,10 +721,6 @@ static struct ref_iterator *files_ref_iterator_begin( refs = files_downcast(ref_store, required_flags, "ref_iterator_begin"); - iter = xcalloc(1, sizeof(*iter)); - ref_iterator = &iter->base; - base_ref_iterator_init(ref_iterator, &files_ref_iterator_vtable); - /* * We must make sure that all loose refs are read before * accessing the packed-refs file; this avoids a race @@ -1112,20 +733,36 @@ static struct ref_iterator *files_ref_iterator_begin( * (If they've already been read, that's OK; we only need to * guarantee that they're read before the packed refs, not * *how much* before.) After that, we call - * get_packed_ref_cache(), which internally checks whether the - * packed-ref cache is up to date with what is on disk, and - * re-reads it if not. + * packed_ref_iterator_begin(), which internally checks + * whether the packed-ref cache is up to date with what is on + * disk, and re-reads it if not. */ loose_iter = cache_ref_iterator_begin(get_loose_ref_cache(refs), prefix, 1); - iter->packed_ref_cache = get_packed_ref_cache(refs); - acquire_packed_ref_cache(iter->packed_ref_cache); - packed_iter = cache_ref_iterator_begin(iter->packed_ref_cache->cache, - prefix, 0); + /* + * The packed-refs file might contain broken references, for + * example an old version of a reference that points at an + * object that has since been garbage-collected. This is OK as + * long as there is a corresponding loose reference that + * overrides it, and we don't want to emit an error message in + * this case. So ask the packed_ref_store for all of its + * references, and (if needed) do our own check for broken + * ones in files_ref_iterator_advance(), after we have merged + * the packed and loose references. + */ + packed_iter = refs_ref_iterator_begin( + refs->packed_ref_store, prefix, 0, + DO_FOR_EACH_INCLUDE_BROKEN); + + overlay_iter = overlay_ref_iterator_begin(loose_iter, packed_iter); - iter->iter0 = overlay_ref_iterator_begin(loose_iter, packed_iter); + iter = xcalloc(1, sizeof(*iter)); + ref_iterator = &iter->base; + base_ref_iterator_init(ref_iterator, &files_ref_iterator_vtable, + overlay_iter->ordered); + iter->iter0 = overlay_iter; iter->flags = flags; return ref_iterator; @@ -1181,7 +818,9 @@ static int create_reflock(const char *path, void *cb) { struct lock_file *lk = cb; - return hold_lock_file_for_update(lk, path, LOCK_NO_DEREF) < 0 ? -1 : 0; + return hold_lock_file_for_update_timeout( + lk, path, LOCK_NO_DEREF, + get_files_ref_lock_timeout_ms()) < 0 ? -1 : 0; } /* @@ -1255,17 +894,15 @@ static struct ref_lock *lock_ref_sha1_basic(struct files_ref_store *refs, * our refname. */ if (is_null_oid(&lock->old_oid) && - refs_verify_refname_available(&refs->base, refname, + refs_verify_refname_available(refs->packed_ref_store, refname, extras, skip, err)) { last_errno = ENOTDIR; goto error_return; } - lock->lk = xcalloc(1, sizeof(struct lock_file)); - lock->ref_name = xstrdup(refname); - if (raceproof_create_file(ref_file.buf, create_reflock, lock->lk)) { + if (raceproof_create_file(ref_file.buf, create_reflock, &lock->lk)) { last_errno = errno; unable_to_lock_message(ref_file.buf, errno, err); goto error_return; @@ -1287,124 +924,6 @@ static struct ref_lock *lock_ref_sha1_basic(struct files_ref_store *refs, return lock; } -/* - * 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. - */ -static void write_packed_entry(FILE *fh, const char *refname, - const unsigned char *sha1, - const unsigned char *peeled) -{ - fprintf_or_die(fh, "%s %s\n", sha1_to_hex(sha1), refname); - if (peeled) - fprintf_or_die(fh, "^%s\n", sha1_to_hex(peeled)); -} - -/* - * Lock the packed-refs file for writing. Flags is passed to - * hold_lock_file_for_update(). Return 0 on success. On errors, set - * errno appropriately and return a nonzero value. - */ -static int lock_packed_refs(struct files_ref_store *refs, int flags) -{ - static int timeout_configured = 0; - static int timeout_value = 1000; - struct packed_ref_cache *packed_ref_cache; - - files_assert_main_repository(refs, "lock_packed_refs"); - - if (!timeout_configured) { - git_config_get_int("core.packedrefstimeout", &timeout_value); - timeout_configured = 1; - } - - if (hold_lock_file_for_update_timeout( - &refs->packed_refs_lock, files_packed_refs_path(refs), - flags, timeout_value) < 0) - return -1; - - /* - * Now that we hold the `packed-refs` lock, make sure that our - * cache matches the current version of the file. Normally - * `get_packed_ref_cache()` does that for us, but that - * function assumes that when the file is locked, any existing - * cache is still valid. We've just locked the file, but it - * might have changed the moment *before* we locked it. - */ - validate_packed_ref_cache(refs); - - packed_ref_cache = get_packed_ref_cache(refs); - /* Increment the reference count to prevent it from being freed: */ - acquire_packed_ref_cache(packed_ref_cache); - return 0; -} - -/* - * Write the current version of the packed refs cache from memory to - * disk. The packed-refs file must already be locked for writing (see - * lock_packed_refs()). Return zero on success. On errors, set errno - * and return a nonzero value - */ -static int commit_packed_refs(struct files_ref_store *refs) -{ - struct packed_ref_cache *packed_ref_cache = - get_packed_ref_cache(refs); - int ok, error = 0; - int save_errno = 0; - FILE *out; - struct ref_iterator *iter; - - files_assert_main_repository(refs, "commit_packed_refs"); - - if (!is_lock_file_locked(&refs->packed_refs_lock)) - die("BUG: packed-refs not locked"); - - out = fdopen_lock_file(&refs->packed_refs_lock, "w"); - if (!out) - die_errno("unable to fdopen packed-refs descriptor"); - - fprintf_or_die(out, "%s", PACKED_REFS_HEADER); - - iter = cache_ref_iterator_begin(packed_ref_cache->cache, NULL, 0); - while ((ok = ref_iterator_advance(iter)) == ITER_OK) { - struct object_id peeled; - int peel_error = ref_iterator_peel(iter, &peeled); - - write_packed_entry(out, iter->refname, iter->oid->hash, - peel_error ? NULL : peeled.hash); - } - - if (ok != ITER_DONE) - die("error while iterating over references"); - - if (commit_lock_file(&refs->packed_refs_lock)) { - save_errno = errno; - error = -1; - } - release_packed_ref_cache(packed_ref_cache); - errno = save_errno; - return error; -} - -/* - * Rollback the lockfile for the packed-refs file, and discard the - * in-memory packed reference cache. (The packed-refs file will be - * read anew if it is needed again after this function is called.) - */ -static void rollback_packed_refs(struct files_ref_store *refs) -{ - struct packed_ref_cache *packed_ref_cache = - get_packed_ref_cache(refs); - - files_assert_main_repository(refs, "rollback_packed_refs"); - - if (!is_lock_file_locked(&refs->packed_refs_lock)) - die("BUG: packed-refs not locked"); - rollback_lock_file(&refs->packed_refs_lock); - release_packed_ref_cache(packed_ref_cache); - clear_packed_ref_cache(refs); -} - struct ref_to_prune { struct ref_to_prune *next; unsigned char sha1[20]; @@ -1487,11 +1006,17 @@ static void prune_ref(struct files_ref_store *refs, struct ref_to_prune *r) strbuf_release(&err); } -static void prune_refs(struct files_ref_store *refs, struct ref_to_prune *r) +/* + * Prune the loose versions of the references in the linked list + * `*refs_to_prune`, freeing the entries in the list as we go. + */ +static void prune_refs(struct files_ref_store *refs, struct ref_to_prune **refs_to_prune) { - while (r) { + while (*refs_to_prune) { + struct ref_to_prune *r = *refs_to_prune; + *refs_to_prune = r->next; prune_ref(refs, r); - r = r->next; + free(r); } } @@ -1527,12 +1052,16 @@ static int files_pack_refs(struct ref_store *ref_store, unsigned int flags) files_downcast(ref_store, REF_STORE_WRITE | REF_STORE_ODB, "pack_refs"); struct ref_iterator *iter; - struct ref_dir *packed_refs; int ok; struct ref_to_prune *refs_to_prune = NULL; + struct strbuf err = STRBUF_INIT; + struct ref_transaction *transaction; + + transaction = ref_store_transaction_begin(refs->packed_ref_store, &err); + if (!transaction) + return -1; - lock_packed_refs(refs, LOCK_DIE_ON_ERROR); - packed_refs = get_packed_refs(refs); + packed_refs_lock(refs->packed_ref_store, LOCK_DIE_ON_ERROR, &err); iter = cache_ref_iterator_begin(get_loose_ref_cache(refs), NULL, 0); while ((ok = ref_iterator_advance(iter)) == ITER_OK) { @@ -1541,29 +1070,19 @@ static int files_pack_refs(struct ref_store *ref_store, unsigned int flags) * in the packed ref cache. If the reference should be * pruned, also add it to refs_to_prune. */ - struct ref_entry *packed_entry; - if (!should_pack_ref(iter->refname, iter->oid, iter->flags, flags)) continue; /* - * Create an entry in the packed-refs cache equivalent - * to the one from the loose ref cache, except that - * we don't copy the peeled status, because we want it - * to be re-peeled. + * Add a reference creation for this reference to the + * packed-refs transaction: */ - packed_entry = find_ref_entry(packed_refs, iter->refname); - if (packed_entry) { - /* Overwrite existing packed entry with info from loose entry */ - packed_entry->flag = REF_ISPACKED; - oidcpy(&packed_entry->u.value.oid, iter->oid); - } else { - packed_entry = create_ref_entry(iter->refname, iter->oid, - REF_ISPACKED); - add_ref_entry(packed_refs, packed_entry); - } - oidclr(&packed_entry->u.value.peeled); + if (ref_transaction_update(transaction, iter->refname, + iter->oid->hash, NULL, + REF_NODEREF, NULL, &err)) + die("failure preparing to create packed reference %s: %s", + iter->refname, err.buf); /* Schedule the loose reference for pruning if requested. */ if ((flags & PACK_REFS_PRUNE)) { @@ -1577,67 +1096,16 @@ static int files_pack_refs(struct ref_store *ref_store, unsigned int flags) if (ok != ITER_DONE) die("error while iterating over references"); - if (commit_packed_refs(refs)) - die_errno("unable to overwrite old ref-pack file"); - - prune_refs(refs, refs_to_prune); - return 0; -} + if (ref_transaction_commit(transaction, &err)) + die("unable to write new packed-refs: %s", err.buf); -/* - * Rewrite the packed-refs file, omitting any refs listed in - * 'refnames'. On error, leave packed-refs unchanged, write an error - * message to 'err', and return a nonzero value. - * - * The refs in 'refnames' needn't be sorted. `err` must not be NULL. - */ -static int repack_without_refs(struct files_ref_store *refs, - struct string_list *refnames, struct strbuf *err) -{ - struct ref_dir *packed; - struct string_list_item *refname; - int ret, needs_repacking = 0, removed = 0; - - files_assert_main_repository(refs, "repack_without_refs"); - assert(err); - - /* Look for a packed ref */ - for_each_string_list_item(refname, refnames) { - if (get_packed_ref(refs, refname->string)) { - needs_repacking = 1; - break; - } - } - - /* Avoid locking if we have nothing to do */ - if (!needs_repacking) - return 0; /* no refname exists in packed refs */ - - if (lock_packed_refs(refs, 0)) { - unable_to_lock_message(files_packed_refs_path(refs), errno, err); - return -1; - } - packed = get_packed_refs(refs); + ref_transaction_free(transaction); - /* Remove refnames from the cache */ - for_each_string_list_item(refname, refnames) - if (remove_entry_from_dir(packed, refname->string) != -1) - removed = 1; - if (!removed) { - /* - * All packed entries disappeared while we were - * acquiring the lock. - */ - rollback_packed_refs(refs); - return 0; - } + packed_refs_unlock(refs->packed_ref_store); - /* Write what remains */ - ret = commit_packed_refs(refs); - if (ret) - strbuf_addf(err, "unable to overwrite old ref-pack file: %s", - strerror(errno)); - return ret; + prune_refs(refs, &refs_to_prune); + strbuf_release(&err); + return 0; } static int files_delete_refs(struct ref_store *ref_store, const char *msg, @@ -1651,24 +1119,16 @@ static int files_delete_refs(struct ref_store *ref_store, const char *msg, if (!refnames->nr) return 0; - result = repack_without_refs(refs, refnames, &err); - if (result) { - /* - * If we failed to rewrite the packed-refs file, then - * it is unsafe to try to remove loose refs, because - * doing so might expose an obsolete packed value for - * a reference that might even point at an object that - * has been garbage collected. - */ - 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); + if (packed_refs_lock(refs->packed_ref_store, 0, &err)) + goto error; - goto out; + if (refs_delete_refs(refs->packed_ref_store, msg, refnames, flags)) { + packed_refs_unlock(refs->packed_ref_store); + goto error; } + packed_refs_unlock(refs->packed_ref_store); + for (i = 0; i < refnames->nr; i++) { const char *refname = refnames->items[i].string; @@ -1676,9 +1136,24 @@ static int files_delete_refs(struct ref_store *ref_store, const char *msg, result |= error(_("could not remove reference %s"), refname); } -out: strbuf_release(&err); return result; + +error: + /* + * If we failed to rewrite the packed-refs file, then it is + * unsafe to try to remove loose refs, because doing so might + * expose an obsolete packed value for a reference that might + * even point at an object that has been garbage collected. + */ + 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); + + strbuf_release(&err); + return -1; } /* @@ -1748,9 +1223,9 @@ static int commit_ref_update(struct files_ref_store *refs, const struct object_id *oid, const char *logmsg, struct strbuf *err); -static int files_rename_ref(struct ref_store *ref_store, +static int files_copy_or_rename_ref(struct ref_store *ref_store, const char *oldrefname, const char *newrefname, - const char *logmsg) + const char *logmsg, int copy) { struct files_ref_store *refs = files_downcast(ref_store, REF_STORE_WRITE, "rename_ref"); @@ -1782,8 +1257,12 @@ static int files_rename_ref(struct ref_store *ref_store, } if (flag & REF_ISSYMREF) { - ret = error("refname %s is a symbolic ref, renaming it is not supported", - oldrefname); + if (copy) + ret = error("refname %s is a symbolic ref, copying it is not supported", + oldrefname); + else + ret = error("refname %s is a symbolic ref, renaming it is not supported", + oldrefname); goto out; } if (!refs_rename_ref_available(&refs->base, oldrefname, newrefname)) { @@ -1791,13 +1270,19 @@ static int files_rename_ref(struct ref_store *ref_store, goto out; } - if (log && rename(sb_oldref.buf, tmp_renamed_log.buf)) { + if (!copy && log && rename(sb_oldref.buf, tmp_renamed_log.buf)) { ret = error("unable to move logfile logs/%s to logs/"TMP_RENAMED_LOG": %s", oldrefname, strerror(errno)); goto out; } - if (refs_delete_ref(&refs->base, logmsg, oldrefname, + if (copy && log && copy_file(tmp_renamed_log.buf, sb_oldref.buf, 0644)) { + ret = error("unable to copy logfile logs/%s to logs/"TMP_RENAMED_LOG": %s", + oldrefname, strerror(errno)); + goto out; + } + + if (!copy && refs_delete_ref(&refs->base, logmsg, oldrefname, orig_oid.hash, REF_NODEREF)) { error("unable to delete old %s", oldrefname); goto rollback; @@ -1810,7 +1295,7 @@ static int files_rename_ref(struct ref_store *ref_store, * the safety anyway; we want to delete the reference whatever * its current value. */ - if (!refs_read_ref_full(&refs->base, newrefname, + if (!copy && !refs_read_ref_full(&refs->base, newrefname, RESOLVE_REF_READING | RESOLVE_REF_NO_RECURSE, oid.hash, NULL) && refs_delete_ref(&refs->base, NULL, newrefname, @@ -1841,7 +1326,10 @@ static int files_rename_ref(struct ref_store *ref_store, lock = lock_ref_sha1_basic(refs, newrefname, NULL, NULL, NULL, REF_NODEREF, NULL, &err); if (!lock) { - error("unable to rename '%s' to '%s': %s", oldrefname, newrefname, err.buf); + if (copy) + error("unable to copy '%s' to '%s': %s", oldrefname, newrefname, err.buf); + else + error("unable to rename '%s' to '%s': %s", oldrefname, newrefname, err.buf); strbuf_release(&err); goto rollback; } @@ -1892,16 +1380,32 @@ static int files_rename_ref(struct ref_store *ref_store, return ret; } -static int close_ref(struct ref_lock *lock) +static int files_rename_ref(struct ref_store *ref_store, + const char *oldrefname, const char *newrefname, + const char *logmsg) +{ + return files_copy_or_rename_ref(ref_store, oldrefname, + newrefname, logmsg, 0); +} + +static int files_copy_ref(struct ref_store *ref_store, + const char *oldrefname, const char *newrefname, + const char *logmsg) +{ + return files_copy_or_rename_ref(ref_store, oldrefname, + newrefname, logmsg, 1); +} + +static int close_ref_gently(struct ref_lock *lock) { - if (close_lock_file(lock->lk)) + if (close_lock_file_gently(&lock->lk)) return -1; return 0; } static int commit_ref(struct ref_lock *lock) { - char *path = get_locked_file_path(lock->lk); + char *path = get_locked_file_path(&lock->lk); struct stat st; if (!lstat(path, &st) && S_ISDIR(st.st_mode)) { @@ -1925,7 +1429,7 @@ static int commit_ref(struct ref_lock *lock) free(path); } - if (commit_lock_file(lock->lk)) + if (commit_lock_file(&lock->lk)) return -1; return 0; } @@ -2039,7 +1543,7 @@ static int log_ref_write_fd(int fd, const struct object_id *old_oid, written = len <= maxlen ? write_in_full(fd, logrec, len) : -1; free(logrec); - if (written != len) + if (written < 0) return -1; return 0; @@ -2117,12 +1621,12 @@ static int write_ref_to_lockfile(struct ref_lock *lock, unlock_ref(lock); return -1; } - fd = get_lock_file_fd(lock->lk); - if (write_in_full(fd, oid_to_hex(oid), GIT_SHA1_HEXSZ) != GIT_SHA1_HEXSZ || - write_in_full(fd, &term, 1) != 1 || - close_ref(lock) < 0) { + fd = get_lock_file_fd(&lock->lk); + if (write_in_full(fd, oid_to_hex(oid), GIT_SHA1_HEXSZ) < 0 || + write_in_full(fd, &term, 1) < 0 || + close_ref_gently(lock) < 0) { strbuf_addf(err, - "couldn't write '%s'", get_lock_file_path(lock->lk)); + "couldn't write '%s'", get_lock_file_path(&lock->lk)); unlock_ref(lock); return -1; } @@ -2166,13 +1670,12 @@ static int commit_ref_update(struct files_ref_store *refs, * check with HEAD only which should cover 99% of all usage * scenarios (even 100% of the default ones). */ - struct object_id head_oid; int head_flag; const char *head_ref; head_ref = refs_resolve_ref_unsafe(&refs->base, "HEAD", RESOLVE_REF_READING, - head_oid.hash, &head_flag); + NULL, &head_flag); if (head_ref && (head_flag & REF_ISSYMREF) && !strcmp(head_ref, lock->ref_name)) { struct strbuf log_err = STRBUF_INIT; @@ -2199,7 +1702,7 @@ static int create_ref_symlink(struct ref_lock *lock, const char *target) { int ret = -1; #ifndef NO_SYMLINK_HEAD - char *ref_path = get_locked_file_path(lock->lk); + char *ref_path = get_locked_file_path(&lock->lk); unlink(ref_path); ret = symlink(target, ref_path); free(ref_path); @@ -2235,14 +1738,14 @@ static int create_symref_locked(struct files_ref_store *refs, return 0; } - if (!fdopen_lock_file(lock->lk, "w")) + if (!fdopen_lock_file(&lock->lk, "w")) return error("unable to fdopen %s: %s", - lock->lk->tempfile.filename.buf, strerror(errno)); + lock->lk.tempfile->filename.buf, strerror(errno)); update_symref_reflog(refs, lock, refname, target, logmsg); /* no error check; commit_ref will check ferror */ - fprintf(lock->lk->tempfile.fp, "ref: %s\n", target); + fprintf(lock->lk.tempfile->fp, "ref: %s\n", target); if (commit_ref(lock) < 0) return error("unable to write symref for %s: %s", refname, strerror(errno)); @@ -2549,23 +2052,64 @@ static struct ref_iterator_vtable files_reflog_iterator_vtable = { files_reflog_iterator_abort }; -static struct ref_iterator *files_reflog_iterator_begin(struct ref_store *ref_store) +static struct ref_iterator *reflog_iterator_begin(struct ref_store *ref_store, + const char *gitdir) { - struct files_ref_store *refs = - files_downcast(ref_store, REF_STORE_READ, - "reflog_iterator_begin"); struct files_reflog_iterator *iter = xcalloc(1, sizeof(*iter)); struct ref_iterator *ref_iterator = &iter->base; struct strbuf sb = STRBUF_INIT; - base_ref_iterator_init(ref_iterator, &files_reflog_iterator_vtable); - files_reflog_path(refs, &sb, NULL); + base_ref_iterator_init(ref_iterator, &files_reflog_iterator_vtable, 0); + strbuf_addf(&sb, "%s/logs", gitdir); iter->dir_iterator = dir_iterator_begin(sb.buf); iter->ref_store = ref_store; strbuf_release(&sb); + return ref_iterator; } +static enum iterator_selection reflog_iterator_select( + struct ref_iterator *iter_worktree, + struct ref_iterator *iter_common, + void *cb_data) +{ + if (iter_worktree) { + /* + * We're a bit loose here. We probably should ignore + * common refs if they are accidentally added as + * per-worktree refs. + */ + return ITER_SELECT_0; + } else if (iter_common) { + if (ref_type(iter_common->refname) == REF_TYPE_NORMAL) + return ITER_SELECT_1; + + /* + * The main ref store may contain main worktree's + * per-worktree refs, which should be ignored + */ + return ITER_SKIP_1; + } else + return ITER_DONE; +} + +static struct ref_iterator *files_reflog_iterator_begin(struct ref_store *ref_store) +{ + struct files_ref_store *refs = + files_downcast(ref_store, REF_STORE_READ, + "reflog_iterator_begin"); + + if (!strcmp(refs->gitdir, refs->gitcommondir)) { + return reflog_iterator_begin(ref_store, refs->gitcommondir); + } else { + return merge_ref_iterator_begin( + 0, + reflog_iterator_begin(ref_store, refs->gitdir), + reflog_iterator_begin(ref_store, refs->gitcommondir), + reflog_iterator_select, refs); + } +} + /* * If update is a direct update of head_ref (the reference pointed to * by HEAD), then add an extra REF_LOG_ONLY update for HEAD. @@ -2589,11 +2133,10 @@ static int split_head_update(struct ref_update *update, /* * First make sure that HEAD is not already in the - * transaction. This insertion is O(N) in the transaction + * transaction. This check is O(lg N) in the transaction * size, but it happens at most once per transaction. */ - item = string_list_insert(affected_refnames, "HEAD"); - if (item->util) { + if (string_list_has_string(affected_refnames, "HEAD")) { /* An entry already existed */ strbuf_addf(err, "multiple updates for 'HEAD' (including one " @@ -2608,6 +2151,14 @@ static int split_head_update(struct ref_update *update, update->new_oid.hash, update->old_oid.hash, update->msg); + /* + * Add "HEAD". This insertion is O(N) in the transaction + * size, but it happens at most once per transaction. + * Add new_update->refname instead of a literal "HEAD". + */ + if (strcmp(new_update->refname, "HEAD")) + BUG("%s unexpectedly not 'HEAD'", new_update->refname); + item = string_list_insert(affected_refnames, new_update->refname); item->util = new_update; return 0; @@ -2634,13 +2185,12 @@ static int split_symref_update(struct files_ref_store *refs, /* * First make sure that referent is not already in the - * transaction. This insertion is O(N) in the transaction + * transaction. This check is O(lg N) in the transaction * size, but it happens at most once per symref in a * transaction. */ - item = string_list_insert(affected_refnames, referent); - if (item->util) { - /* An entry already existed */ + if (string_list_has_string(affected_refnames, referent)) { + /* An entry already exists */ strbuf_addf(err, "multiple updates for '%s' (including one " "via symref '%s') are not allowed", @@ -2675,6 +2225,17 @@ static int split_symref_update(struct files_ref_store *refs, update->flags |= REF_LOG_ONLY | REF_NODEREF; update->flags &= ~REF_HAVE_OLD; + /* + * Add the referent. This insertion is O(N) in the transaction + * size, but it happens at most once per symref in a + * transaction. Make sure to add new_update->refname, which will + * be valid as long as affected_refnames is in use, and NOT + * referent, which might soon be freed by our caller. + */ + item = string_list_insert(affected_refnames, new_update->refname); + if (item->util) + BUG("%s unexpectedly found in affected_refnames", + new_update->refname); item->util = new_update; return 0; @@ -2746,7 +2307,7 @@ static int lock_ref_for_update(struct files_ref_store *refs, struct strbuf referent = STRBUF_INIT; int mustexist = (update->flags & REF_HAVE_OLD) && !is_null_oid(&update->old_oid); - int ret; + int ret = 0; struct ref_lock *lock; files_assert_main_repository(refs, "lock_ref_for_update"); @@ -2758,7 +2319,7 @@ static int lock_ref_for_update(struct files_ref_store *refs, ret = split_head_update(update, transaction, head_ref, affected_refnames, err); if (ret) - return ret; + goto out; } ret = lock_raw_ref(refs, update->refname, mustexist, @@ -2772,7 +2333,7 @@ static int lock_ref_for_update(struct files_ref_store *refs, strbuf_addf(err, "cannot lock ref '%s': %s", original_update_refname(update), reason); free(reason); - return ret; + goto out; } update->backend_data = lock; @@ -2791,10 +2352,12 @@ static int lock_ref_for_update(struct files_ref_store *refs, strbuf_addf(err, "cannot lock ref '%s': " "error reading reference", original_update_refname(update)); - return -1; + ret = TRANSACTION_GENERIC_ERROR; + goto out; } } else if (check_old_oid(update, &lock->old_oid, err)) { - return TRANSACTION_GENERIC_ERROR; + ret = TRANSACTION_GENERIC_ERROR; + goto out; } } else { /* @@ -2808,13 +2371,15 @@ static int lock_ref_for_update(struct files_ref_store *refs, referent.buf, transaction, affected_refnames, err); if (ret) - return ret; + goto out; } } else { struct ref_update *parent_update; - if (check_old_oid(update, &lock->old_oid, err)) - return TRANSACTION_GENERIC_ERROR; + if (check_old_oid(update, &lock->old_oid, err)) { + ret = TRANSACTION_GENERIC_ERROR; + goto out; + } /* * If this update is happening indirectly because of a @@ -2851,7 +2416,8 @@ static int lock_ref_for_update(struct files_ref_store *refs, "cannot update ref '%s': %s", update->refname, write_err); free(write_err); - return TRANSACTION_GENERIC_ERROR; + ret = TRANSACTION_GENERIC_ERROR; + goto out; } else { update->flags |= REF_NEEDS_COMMIT; } @@ -2862,22 +2428,35 @@ static int lock_ref_for_update(struct files_ref_store *refs, * the lockfile is still open. Close it to * free up the file descriptor: */ - if (close_ref(lock)) { + if (close_ref_gently(lock)) { strbuf_addf(err, "couldn't close '%s.lock'", update->refname); - return TRANSACTION_GENERIC_ERROR; + ret = TRANSACTION_GENERIC_ERROR; + goto out; } } - return 0; + +out: + strbuf_release(&referent); + return ret; } +struct files_transaction_backend_data { + struct ref_transaction *packed_transaction; + int packed_refs_locked; +}; + /* * Unlock any references in `transaction` that are still locked, and * mark the transaction closed. */ -static void files_transaction_cleanup(struct ref_transaction *transaction) +static void files_transaction_cleanup(struct files_ref_store *refs, + struct ref_transaction *transaction) { size_t i; + struct files_transaction_backend_data *backend_data = + transaction->backend_data; + struct strbuf err = STRBUF_INIT; for (i = 0; i < transaction->nr; i++) { struct ref_update *update = transaction->updates[i]; @@ -2889,6 +2468,17 @@ static void files_transaction_cleanup(struct ref_transaction *transaction) } } + if (backend_data->packed_transaction && + ref_transaction_abort(backend_data->packed_transaction, &err)) { + error("error aborting transaction: %s", err.buf); + strbuf_release(&err); + } + + if (backend_data->packed_refs_locked) + packed_refs_unlock(refs->packed_ref_store); + + free(backend_data); + transaction->state = REF_TRANSACTION_CLOSED; } @@ -2904,13 +2494,17 @@ static int files_transaction_prepare(struct ref_store *ref_store, struct string_list affected_refnames = STRING_LIST_INIT_NODUP; char *head_ref = NULL; int head_type; - struct object_id head_oid; + struct files_transaction_backend_data *backend_data; + struct ref_transaction *packed_transaction = NULL; assert(err); if (!transaction->nr) goto cleanup; + backend_data = xcalloc(1, sizeof(*backend_data)); + transaction->backend_data = backend_data; + /* * Fail if a refname appears more than once in the * transaction. (If we end up splitting up any updates using @@ -2956,7 +2550,7 @@ static int files_transaction_prepare(struct ref_store *ref_store, */ head_ref = refs_resolve_refdup(ref_store, "HEAD", RESOLVE_REF_NO_RECURSE, - head_oid.hash, &head_type); + NULL, &head_type); if (head_ref && !(head_type & REF_ISSYMREF)) { FREE_AND_NULL(head_ref); @@ -2977,6 +2571,41 @@ static int files_transaction_prepare(struct ref_store *ref_store, head_ref, &affected_refnames, err); if (ret) break; + + if (update->flags & REF_DELETING && + !(update->flags & REF_LOG_ONLY) && + !(update->flags & REF_ISPRUNING)) { + /* + * This reference has to be deleted from + * packed-refs if it exists there. + */ + if (!packed_transaction) { + packed_transaction = ref_store_transaction_begin( + refs->packed_ref_store, err); + if (!packed_transaction) { + ret = TRANSACTION_GENERIC_ERROR; + goto cleanup; + } + + backend_data->packed_transaction = + packed_transaction; + } + + ref_transaction_add_update( + packed_transaction, update->refname, + update->flags & ~REF_HAVE_OLD, + update->new_oid.hash, update->old_oid.hash, + NULL); + } + } + + if (packed_transaction) { + if (packed_refs_lock(refs->packed_ref_store, 0, err)) { + ret = TRANSACTION_GENERIC_ERROR; + goto cleanup; + } + backend_data->packed_refs_locked = 1; + ret = ref_transaction_prepare(packed_transaction, err); } cleanup: @@ -2984,7 +2613,7 @@ cleanup: string_list_clear(&affected_refnames, 0); if (ret) - files_transaction_cleanup(transaction); + files_transaction_cleanup(refs, transaction); else transaction->state = REF_TRANSACTION_PREPARED; @@ -2999,9 +2628,10 @@ static int files_transaction_finish(struct ref_store *ref_store, files_downcast(ref_store, 0, "ref_transaction_finish"); size_t i; int ret = 0; - struct string_list refs_to_delete = STRING_LIST_INIT_NODUP; - struct string_list_item *ref_to_delete; struct strbuf sb = STRBUF_INIT; + struct files_transaction_backend_data *backend_data; + struct ref_transaction *packed_transaction; + assert(err); @@ -3010,6 +2640,9 @@ static int files_transaction_finish(struct ref_store *ref_store, return 0; } + backend_data = transaction->backend_data; + packed_transaction = backend_data->packed_transaction; + /* Perform updates first so live commits remain referenced */ for (i = 0; i < transaction->nr; i++) { struct ref_update *update = transaction->updates[i]; @@ -3045,7 +2678,44 @@ static int files_transaction_finish(struct ref_store *ref_store, } } } - /* Perform deletes now that updates are safely completed */ + + /* + * Now that updates are safely completed, we can perform + * deletes. First delete the reflogs of any references that + * will be deleted, since (in the unexpected event of an + * error) leaving a reference without a reflog is less bad + * than leaving a reflog without a reference (the latter is a + * mildly invalid repository state): + */ + for (i = 0; i < transaction->nr; i++) { + struct ref_update *update = transaction->updates[i]; + if (update->flags & REF_DELETING && + !(update->flags & REF_LOG_ONLY) && + !(update->flags & REF_ISPRUNING)) { + strbuf_reset(&sb); + files_reflog_path(refs, &sb, update->refname); + if (!unlink_or_warn(sb.buf)) + try_remove_empty_parents(refs, update->refname, + REMOVE_EMPTY_PARENTS_REFLOG); + } + } + + /* + * Perform deletes now that updates are safely completed. + * + * First delete any packed versions of the references, while + * retaining the packed-refs lock: + */ + if (packed_transaction) { + ret = ref_transaction_commit(packed_transaction, err); + ref_transaction_free(packed_transaction); + packed_transaction = NULL; + backend_data->packed_transaction = NULL; + if (ret) + goto cleanup; + } + + /* Now delete the loose versions of the references: */ for (i = 0; i < transaction->nr; i++) { struct ref_update *update = transaction->updates[i]; struct ref_lock *lock = update->backend_data; @@ -3063,31 +2733,13 @@ static int files_transaction_finish(struct ref_store *ref_store, } update->flags |= REF_DELETED_LOOSE; } - - if (!(update->flags & REF_ISPRUNING)) - string_list_append(&refs_to_delete, - lock->ref_name); } } - if (repack_without_refs(refs, &refs_to_delete, err)) { - ret = TRANSACTION_GENERIC_ERROR; - goto cleanup; - } - - /* Delete the reflogs of any references that were deleted: */ - for_each_string_list_item(ref_to_delete, &refs_to_delete) { - strbuf_reset(&sb); - files_reflog_path(refs, &sb, ref_to_delete->string); - if (!unlink_or_warn(sb.buf)) - try_remove_empty_parents(refs, ref_to_delete->string, - REMOVE_EMPTY_PARENTS_REFLOG); - } - clear_loose_ref_cache(refs); cleanup: - files_transaction_cleanup(transaction); + files_transaction_cleanup(refs, transaction); for (i = 0; i < transaction->nr; i++) { struct ref_update *update = transaction->updates[i]; @@ -3105,7 +2757,6 @@ cleanup: } strbuf_release(&sb); - string_list_clear(&refs_to_delete, 0); return ret; } @@ -3113,7 +2764,10 @@ static int files_transaction_abort(struct ref_store *ref_store, struct ref_transaction *transaction, struct strbuf *err) { - files_transaction_cleanup(transaction); + struct files_ref_store *refs = + files_downcast(ref_store, 0, "ref_transaction_abort"); + + files_transaction_cleanup(refs, transaction); return 0; } @@ -3135,6 +2789,7 @@ static int files_initial_transaction_commit(struct ref_store *ref_store, size_t i; int ret = 0; struct string_list affected_refnames = STRING_LIST_INIT_NODUP; + struct ref_transaction *packed_transaction = NULL; assert(err); @@ -3167,6 +2822,12 @@ static int files_initial_transaction_commit(struct ref_store *ref_store, &affected_refnames)) die("BUG: initial ref transaction called with existing refs"); + packed_transaction = ref_store_transaction_begin(refs->packed_ref_store, err); + if (!packed_transaction) { + ret = TRANSACTION_GENERIC_ERROR; + goto cleanup; + } + for (i = 0; i < transaction->nr; i++) { struct ref_update *update = transaction->updates[i]; @@ -3179,32 +2840,31 @@ static int files_initial_transaction_commit(struct ref_store *ref_store, ret = TRANSACTION_NAME_CONFLICT; goto cleanup; } + + /* + * Add a reference creation for this reference to the + * packed-refs transaction: + */ + ref_transaction_add_update(packed_transaction, update->refname, + update->flags & ~REF_HAVE_OLD, + update->new_oid.hash, update->old_oid.hash, + NULL); } - if (lock_packed_refs(refs, 0)) { - strbuf_addf(err, "unable to lock packed-refs file: %s", - strerror(errno)); + if (packed_refs_lock(refs->packed_ref_store, 0, err)) { ret = TRANSACTION_GENERIC_ERROR; goto cleanup; } - for (i = 0; i < transaction->nr; i++) { - struct ref_update *update = transaction->updates[i]; - - if ((update->flags & REF_HAVE_NEW) && - !is_null_oid(&update->new_oid)) - add_packed_ref(refs, update->refname, - &update->new_oid); - } - - if (commit_packed_refs(refs)) { - strbuf_addf(err, "unable to commit packed-refs file: %s", - strerror(errno)); + if (initial_ref_transaction_commit(packed_transaction, err)) { ret = TRANSACTION_GENERIC_ERROR; goto cleanup; } cleanup: + if (packed_transaction) + ref_transaction_free(packed_transaction); + packed_refs_unlock(refs->packed_ref_store); transaction->state = REF_TRANSACTION_CLOSED; string_list_clear(&affected_refnames, 0); return ret; @@ -3333,16 +2993,17 @@ static int files_reflog_expire(struct ref_store *ref_store, !(type & REF_ISSYMREF) && !is_null_oid(&cb.last_kept_oid); - if (close_lock_file(&reflog_lock)) { + if (close_lock_file_gently(&reflog_lock)) { status |= error("couldn't write %s: %s", log_file, strerror(errno)); + rollback_lock_file(&reflog_lock); } else if (update && - (write_in_full(get_lock_file_fd(lock->lk), - oid_to_hex(&cb.last_kept_oid), GIT_SHA1_HEXSZ) != GIT_SHA1_HEXSZ || - write_str_in_full(get_lock_file_fd(lock->lk), "\n") != 1 || - close_ref(lock) < 0)) { + (write_in_full(get_lock_file_fd(&lock->lk), + oid_to_hex(&cb.last_kept_oid), GIT_SHA1_HEXSZ) < 0 || + write_str_in_full(get_lock_file_fd(&lock->lk), "\n") < 0 || + close_ref_gently(lock) < 0)) { status |= error("couldn't write %s", - get_lock_file_path(lock->lk)); + get_lock_file_path(&lock->lk)); rollback_lock_file(&reflog_lock); } else if (commit_lock_file(&reflog_lock)) { status |= error("unable to write reflog '%s' (%s)", @@ -3393,10 +3054,10 @@ struct ref_storage_be refs_be_files = { files_initial_transaction_commit, files_pack_refs, - files_peel_ref, files_create_symref, files_delete_refs, files_rename_ref, + files_copy_ref, files_ref_iterator_begin, files_read_raw_ref, diff --git a/refs/iterator.c b/refs/iterator.c index 4cf449ef66..bd35da4e62 100644 --- a/refs/iterator.c +++ b/refs/iterator.c @@ -25,9 +25,11 @@ int ref_iterator_abort(struct ref_iterator *ref_iterator) } void base_ref_iterator_init(struct ref_iterator *iter, - struct ref_iterator_vtable *vtable) + struct ref_iterator_vtable *vtable, + int ordered) { iter->vtable = vtable; + iter->ordered = !!ordered; iter->refname = NULL; iter->oid = NULL; iter->flags = 0; @@ -72,7 +74,7 @@ struct ref_iterator *empty_ref_iterator_begin(void) struct empty_ref_iterator *iter = xcalloc(1, sizeof(*iter)); struct ref_iterator *ref_iterator = &iter->base; - base_ref_iterator_init(ref_iterator, &empty_ref_iterator_vtable); + base_ref_iterator_init(ref_iterator, &empty_ref_iterator_vtable, 1); return ref_iterator; } @@ -205,6 +207,7 @@ static struct ref_iterator_vtable merge_ref_iterator_vtable = { }; struct ref_iterator *merge_ref_iterator_begin( + int ordered, struct ref_iterator *iter0, struct ref_iterator *iter1, ref_iterator_select_fn *select, void *cb_data) { @@ -219,7 +222,7 @@ struct ref_iterator *merge_ref_iterator_begin( * references through only if they exist in both iterators. */ - base_ref_iterator_init(ref_iterator, &merge_ref_iterator_vtable); + base_ref_iterator_init(ref_iterator, &merge_ref_iterator_vtable, ordered); iter->iter0 = iter0; iter->iter1 = iter1; iter->select = select; @@ -268,9 +271,11 @@ struct ref_iterator *overlay_ref_iterator_begin( } else if (is_empty_ref_iterator(back)) { ref_iterator_abort(back); return front; + } else if (!front->ordered || !back->ordered) { + BUG("overlay_ref_iterator requires ordered inputs"); } - return merge_ref_iterator_begin(front, back, + return merge_ref_iterator_begin(1, front, back, overlay_iterator_select, NULL); } @@ -282,6 +287,20 @@ struct prefix_ref_iterator { int trim; }; +/* Return -1, 0, 1 if refname is before, inside, or after the prefix. */ +static int compare_prefix(const char *refname, const char *prefix) +{ + while (*prefix) { + if (*refname != *prefix) + return ((unsigned char)*refname < (unsigned char)*prefix) ? -1 : +1; + + refname++; + prefix++; + } + + return 0; +} + static int prefix_ref_iterator_advance(struct ref_iterator *ref_iterator) { struct prefix_ref_iterator *iter = @@ -289,9 +308,25 @@ static int prefix_ref_iterator_advance(struct ref_iterator *ref_iterator) int ok; while ((ok = ref_iterator_advance(iter->iter0)) == ITER_OK) { - if (!starts_with(iter->iter0->refname, iter->prefix)) + int cmp = compare_prefix(iter->iter0->refname, iter->prefix); + + if (cmp < 0) continue; + if (cmp > 0) { + /* + * If the source iterator is ordered, then we + * can stop the iteration as soon as we see a + * refname that comes after the prefix: + */ + if (iter->iter0->ordered) { + ok = ref_iterator_abort(iter->iter0); + break; + } else { + continue; + } + } + if (iter->trim) { /* * It is nonsense to trim off characters that @@ -361,7 +396,7 @@ struct ref_iterator *prefix_ref_iterator_begin(struct ref_iterator *iter0, iter = xcalloc(1, sizeof(*iter)); ref_iterator = &iter->base; - base_ref_iterator_init(ref_iterator, &prefix_ref_iterator_vtable); + base_ref_iterator_init(ref_iterator, &prefix_ref_iterator_vtable, iter0->ordered); iter->iter0 = iter0; iter->prefix = xstrdup(prefix); diff --git a/refs/packed-backend.c b/refs/packed-backend.c new file mode 100644 index 0000000000..3279d42c5a --- /dev/null +++ b/refs/packed-backend.c @@ -0,0 +1,1558 @@ +#include "../cache.h" +#include "../config.h" +#include "../refs.h" +#include "refs-internal.h" +#include "packed-backend.h" +#include "../iterator.h" +#include "../lockfile.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. If the file was + * already sorted, this points at the mmapped contents of the + * file. If not, this points at heap-allocated memory + * containing the contents, sorted. If there were no contents + * (e.g., because the file didn't exist), `buf` and `eof` are + * both NULL. + */ + char *buf, *eof; + + /* The size of the header line, if any; otherwise, 0: */ + size_t header_len; + + /* + * 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->eof = NULL; + snapshot->header_len = 0; +} + +/* + * 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); + refs->store_flags = store_flags; + + refs->path = xstrdup(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) + die("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) + die("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 + GIT_SHA1_HEXSZ + 1; + const char *r2 = e2->start + GIT_SHA1_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 + GIT_SHA1_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->buf + snapshot->header_len; + eof = snapshot->eof; + len = eof - pos; + + if (!len) + return; + + /* + * 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 < GIT_SHA1_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 = new_buffer; + snapshot->eof = new_buffer + len; + snapshot->header_len = 0; + +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 *buf = snapshot->buf + snapshot->header_len; + const char *eof = snapshot->eof; + const char *last_line; + + if (buf == eof) + return; + + last_line = find_start_of_record(buf, eof - 1); + if (*(eof - 1) != '\n' || eof - last_line < GIT_SHA1_HEXSZ + 2) + die_invalid_line(snapshot->refs->path, + last_line, eof - last_line); +} + +/* + * 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. 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); + + switch (mmap_strategy) { + case MMAP_NONE: + 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->eof = snapshot->buf + size; + snapshot->mmapped = 0; + break; + case MMAP_TEMPORARY: + case MMAP_OK: + snapshot->buf = xmmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0); + snapshot->eof = snapshot->buf + size; + snapshot->mmapped = 1; + break; + } + close(fd); + + 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. 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->buf + snapshot->header_len; + + /* + * 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 == '#') { + struct strbuf tmp = STRBUF_INIT; + char *p; + const char *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); + + strbuf_add(&tmp, snapshot->buf, eol - snapshot->buf); + + if (!skip_prefix(tmp.buf, "# 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->header_len = eol + 1 - snapshot->buf; + + string_list_clear(&traits, 0); + strbuf_release(&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->buf + snapshot->header_len); + char *buf_copy = xmalloc(size); + + memcpy(buf_copy, snapshot->buf + snapshot->header_len, size); + clear_snapshot_buffer(snapshot); + snapshot->buf = 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, unsigned char *sha1, + 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_sha1_hex(rec, sha1)) + 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_sha1` + * 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 < GIT_SHA1_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 < GIT_SHA1_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.hash, peeled->hash); + } +} + +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 (!snapshot->buf) + 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); + + if (prefix && *prefix) + start = find_reference_location(snapshot, prefix, 0); + else + start = snapshot->buf + snapshot->header_len; + + 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 unsigned char *sha1, + const unsigned char *peeled) +{ + if (fprintf(fh, "%s %s\n", sha1_to_hex(sha1), refname) < 0 || + (peeled && fprintf(fh, "^%s\n", sha1_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; + } + + /* + * Now that we hold the `packed-refs` lock, make sure that our + * snapshot matches the current version of the file. Normally + * `get_snapshot()` does that for us, but that function + * assumes that when the file is locked, any existing snapshot + * is still valid. We've just locked the file, but it might + * have changed the moment *before* we locked it. + */ + validate_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)) + die("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)) + die("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 (oidcmp(&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->hash, + peel_error ? NULL : peeled.hash)) + 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.hash, + peeled.hash); + + if (write_packed_entry(out, update->refname, + update->new_oid.hash, + peel_error ? NULL : peeled.hash)) + 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; +} + +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) +{ + die("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) +{ + die("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) +{ + die("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) +{ + die("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 unsigned char *sha1, + 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 +}; diff --git a/refs/packed-backend.h b/refs/packed-backend.h new file mode 100644 index 0000000000..61687e408a --- /dev/null +++ b/refs/packed-backend.h @@ -0,0 +1,26 @@ +#ifndef REFS_PACKED_BACKEND_H +#define REFS_PACKED_BACKEND_H + +/* + * Support for storing references in a `packed-refs` file. + * + * Note that this backend doesn't check for D/F conflicts, because it + * doesn't care about them. But usually it should be wrapped in a + * `files_ref_store` that prevents D/F conflicts from being created, + * even among packed refs. + */ + +struct ref_store *packed_ref_store_create(const char *path, + unsigned int store_flags); + +/* + * Lock the packed-refs file for writing. Flags is passed to + * hold_lock_file_for_update(). Return 0 on success. On errors, write + * an error message to `err` and return a nonzero value. + */ +int packed_refs_lock(struct ref_store *ref_store, int flags, struct strbuf *err); + +void packed_refs_unlock(struct ref_store *ref_store); +int packed_refs_is_locked(struct ref_store *ref_store); + +#endif /* REFS_PACKED_BACKEND_H */ diff --git a/refs/ref-cache.c b/refs/ref-cache.c index 76bb723c86..4f850e1b5c 100644 --- a/refs/ref-cache.c +++ b/refs/ref-cache.c @@ -38,7 +38,6 @@ struct ref_entry *create_ref_entry(const char *refname, FLEX_ALLOC_STR(ref, name, refname); oidcpy(&ref->u.value.oid, oid); - oidclr(&ref->u.value.peeled); ref->flag = flag; return ref; } @@ -491,49 +490,10 @@ static int cache_ref_iterator_advance(struct ref_iterator *ref_iterator) } } -enum peel_status peel_entry(struct ref_entry *entry, int repeel) -{ - enum peel_status status; - - if (entry->flag & REF_KNOWS_PEELED) { - if (repeel) { - entry->flag &= ~REF_KNOWS_PEELED; - oidclr(&entry->u.value.peeled); - } else { - return is_null_oid(&entry->u.value.peeled) ? - PEEL_NON_TAG : PEEL_PEELED; - } - } - if (entry->flag & REF_ISBROKEN) - return PEEL_BROKEN; - if (entry->flag & REF_ISSYMREF) - return PEEL_IS_SYMREF; - - status = peel_object(entry->u.value.oid.hash, entry->u.value.peeled.hash); - if (status == PEEL_PEELED || status == PEEL_NON_TAG) - entry->flag |= REF_KNOWS_PEELED; - return status; -} - static int cache_ref_iterator_peel(struct ref_iterator *ref_iterator, struct object_id *peeled) { - struct cache_ref_iterator *iter = - (struct cache_ref_iterator *)ref_iterator; - struct cache_ref_iterator_level *level; - struct ref_entry *entry; - - level = &iter->levels[iter->levels_nr - 1]; - - if (level->index == -1) - die("BUG: peel called before advance for cache iterator"); - - entry = level->dir->entries[level->index]; - - if (peel_entry(entry, 0)) - return -1; - oidcpy(peeled, &entry->u.value.peeled); - return 0; + return peel_object(ref_iterator->oid->hash, peeled->hash); } static int cache_ref_iterator_abort(struct ref_iterator *ref_iterator) @@ -574,7 +534,7 @@ struct ref_iterator *cache_ref_iterator_begin(struct ref_cache *cache, iter = xcalloc(1, sizeof(*iter)); ref_iterator = &iter->base; - base_ref_iterator_init(ref_iterator, &cache_ref_iterator_vtable); + base_ref_iterator_init(ref_iterator, &cache_ref_iterator_vtable, 1); ALLOC_GROW(iter->levels, 10, iter->levels_alloc); iter->levels_nr = 1; diff --git a/refs/ref-cache.h b/refs/ref-cache.h index 794f000fd3..eda65e73ed 100644 --- a/refs/ref-cache.h +++ b/refs/ref-cache.h @@ -38,14 +38,6 @@ struct ref_value { * referred to by the last reference in the symlink chain. */ struct object_id oid; - - /* - * If REF_KNOWS_PEELED, then this field holds the peeled value - * of this reference, or null if the reference is known not to - * be peelable. See the documentation for peel_ref() for an - * exact definition of "peelable". - */ - struct object_id peeled; }; /* @@ -97,21 +89,14 @@ struct ref_dir { * public values; see refs.h. */ -/* - * The field ref_entry->u.value.peeled of this value entry contains - * the correct peeled value for the reference, which might be - * null_sha1 if the reference is not a tag or if it is broken. - */ -#define REF_KNOWS_PEELED 0x10 - /* ref_entry represents a directory of references */ -#define REF_DIR 0x20 +#define REF_DIR 0x10 /* * Entry has not yet been read from disk (used only for REF_DIR * entries representing loose references) */ -#define REF_INCOMPLETE 0x40 +#define REF_INCOMPLETE 0x20 /* * A ref_entry represents either a reference or a "subdirectory" of @@ -245,23 +230,11 @@ struct ref_entry *find_ref_entry(struct ref_dir *dir, const char *refname); * Start iterating over references in `cache`. If `prefix` is * specified, only include references whose names start with that * prefix. If `prime_dir` is true, then fill any incomplete - * directories before beginning the iteration. + * directories before beginning the iteration. The output is ordered + * by refname. */ struct ref_iterator *cache_ref_iterator_begin(struct ref_cache *cache, const char *prefix, int prime_dir); -/* - * Peel the entry (if possible) and return its new peel_status. If - * repeel is true, re-peel the entry even if there is an old peeled - * value that is already stored in it. - * - * It is OK to call this function with a packed reference entry that - * might be stale and might even refer to an object that has since - * been garbage-collected. In such a case, if the entry has - * REF_KNOWS_PEELED then leave the status unchanged and return - * PEEL_PEELED or PEEL_NON_TAG; otherwise, return PEEL_INVALID. - */ -enum peel_status peel_entry(struct ref_entry *entry, int repeel); - #endif /* REFS_REF_CACHE_H */ diff --git a/refs/refs-internal.h b/refs/refs-internal.h index 192f9f85c9..448de4bccb 100644 --- a/refs/refs-internal.h +++ b/refs/refs-internal.h @@ -62,6 +62,12 @@ #define REF_DELETED_LOOSE 0x200 /* + * Return the length of time to retry acquiring a loose reference lock + * before giving up, in milliseconds: + */ +long get_files_ref_lock_timeout_ms(void); + +/* * Return true iff refname is minimally safe. "Safe" here means that * deleting a loose reference by this name will not do any damage, for * example by causing a file that is not a reference to be deleted. @@ -77,6 +83,15 @@ */ int refname_is_safe(const char *refname); +/* + * Helper function: return true if refname, which has the specified + * oid and flags, can be resolved to an object in the database. If the + * referred-to object does not exist, emit a warning and return false. + */ +int ref_resolves_to_object(const char *refname, + const struct object_id *oid, + unsigned int flags); + enum peel_status { /* object was peeled successfully: */ PEEL_PEELED = 0, @@ -227,6 +242,7 @@ struct ref_transaction { size_t alloc; size_t nr; enum ref_transaction_state state; + void *backend_data; }; /* @@ -313,6 +329,13 @@ int refs_rename_ref_available(struct ref_store *refs, */ struct ref_iterator { struct ref_iterator_vtable *vtable; + + /* + * Does this `ref_iterator` iterate over references in order + * by refname? + */ + unsigned int ordered : 1; + const char *refname; const struct object_id *oid; unsigned int flags; @@ -358,7 +381,7 @@ int is_empty_ref_iterator(struct ref_iterator *ref_iterator); * which the refname begins with prefix. If trim is non-zero, then * trim that many characters off the beginning of each refname. flags * can be DO_FOR_EACH_INCLUDE_BROKEN to include broken references in - * the iteration. + * the iteration. The output is ordered by refname. */ struct ref_iterator *refs_ref_iterator_begin( struct ref_store *refs, @@ -384,9 +407,11 @@ typedef enum iterator_selection ref_iterator_select_fn( * Iterate over the entries from iter0 and iter1, with the values * interleaved as directed by the select function. The iterator takes * ownership of iter0 and iter1 and frees them when the iteration is - * over. + * over. A derived class should set `ordered` to 1 or 0 based on + * whether it generates its output in order by reference name. */ struct ref_iterator *merge_ref_iterator_begin( + int ordered, struct ref_iterator *iter0, struct ref_iterator *iter1, ref_iterator_select_fn *select, void *cb_data); @@ -415,6 +440,8 @@ struct ref_iterator *overlay_ref_iterator_begin( * As an convenience to callers, if prefix is the empty string and * trim is zero, this function returns iter0 directly, without * wrapping it. + * + * The resulting ref_iterator is ordered if iter0 is. */ struct ref_iterator *prefix_ref_iterator_begin(struct ref_iterator *iter0, const char *prefix, @@ -425,11 +452,14 @@ struct ref_iterator *prefix_ref_iterator_begin(struct ref_iterator *iter0, /* * Base class constructor for ref_iterators. Initialize the * ref_iterator part of iter, setting its vtable pointer as specified. + * `ordered` should be set to 1 if the iterator will iterate over + * references in order by refname; otherwise it should be set to 0. * This is meant to be called only by the initializers of derived * classes. */ void base_ref_iterator_init(struct ref_iterator *iter, - struct ref_iterator_vtable *vtable); + struct ref_iterator_vtable *vtable, + int ordered); /* * Base class destructor for ref_iterators. Destroy the ref_iterator @@ -532,8 +562,6 @@ typedef int ref_transaction_commit_fn(struct ref_store *refs, struct strbuf *err); typedef int pack_refs_fn(struct ref_store *ref_store, unsigned int flags); -typedef int peel_ref_fn(struct ref_store *ref_store, - const char *refname, unsigned char *sha1); typedef int create_symref_fn(struct ref_store *ref_store, const char *ref_target, const char *refs_heads_master, @@ -543,12 +571,16 @@ typedef int delete_refs_fn(struct ref_store *ref_store, const char *msg, typedef int rename_ref_fn(struct ref_store *ref_store, const char *oldref, const char *newref, const char *logmsg); +typedef int copy_ref_fn(struct ref_store *ref_store, + const char *oldref, const char *newref, + const char *logmsg); /* * Iterate over the references in `ref_store` whose names start with * `prefix`. `prefix` is matched as a literal string, without regard * for path separators. If prefix is NULL or the empty string, iterate - * over all references in `ref_store`. + * over all references in `ref_store`. The output is ordered by + * refname. */ typedef struct ref_iterator *ref_iterator_begin_fn( struct ref_store *ref_store, @@ -637,10 +669,10 @@ struct ref_storage_be { ref_transaction_commit_fn *initial_transaction_commit; pack_refs_fn *pack_refs; - peel_ref_fn *peel_ref; create_symref_fn *create_symref; delete_refs_fn *delete_refs; rename_ref_fn *rename_ref; + copy_ref_fn *copy_ref; ref_iterator_begin_fn *iterator_begin; read_raw_ref_fn *read_raw_ref; @@ -655,6 +687,7 @@ struct ref_storage_be { }; extern struct ref_storage_be refs_be_files; +extern struct ref_storage_be refs_be_packed; /* * A representation of the reference store for the main repository or |