diff options
Diffstat (limited to 'refs')
| -rw-r--r-- | refs/debug.c | 15 | ||||
| -rw-r--r-- | refs/files-backend.c | 265 | ||||
| -rw-r--r-- | refs/packed-backend.c | 15 | ||||
| -rw-r--r-- | refs/refs-internal.h | 22 |
4 files changed, 183 insertions, 134 deletions
diff --git a/refs/debug.c b/refs/debug.c index 1a7a9e11cf..8667c64023 100644 --- a/refs/debug.c +++ b/refs/debug.c @@ -239,15 +239,14 @@ debug_ref_iterator_begin(struct ref_store *ref_store, const char *prefix, static int debug_read_raw_ref(struct ref_store *ref_store, const char *refname, struct object_id *oid, struct strbuf *referent, - unsigned int *type) + unsigned int *type, int *failure_errno) { struct debug_ref_store *drefs = (struct debug_ref_store *)ref_store; int res = 0; oidcpy(oid, null_oid()); - errno = 0; res = drefs->refs->be->read_raw_ref(drefs->refs, refname, oid, referent, - type); + type, failure_errno); if (res == 0) { trace_printf_key(&trace_refs, "read_raw_ref: %s: %s (=> %s) type %x: %d\n", @@ -255,7 +254,7 @@ static int debug_read_raw_ref(struct ref_store *ref_store, const char *refname, } else { trace_printf_key(&trace_refs, "read_raw_ref: %s: %d (errno %d)\n", refname, - res, errno); + res, *failure_errno); } return res; } @@ -365,8 +364,8 @@ struct debug_reflog_expiry_should_prune { }; static void debug_reflog_expiry_prepare(const char *refname, - const struct object_id *oid, - void *cb_data) + const struct object_id *oid, + void *cb_data) { struct debug_reflog_expiry_should_prune *prune = cb_data; trace_printf_key(&trace_refs, "reflog_expire_prepare: %s\n", refname); @@ -392,7 +391,7 @@ static void debug_reflog_expiry_cleanup(void *cb_data) } static int debug_reflog_expire(struct ref_store *ref_store, const char *refname, - const struct object_id *oid, unsigned int flags, + unsigned int flags, reflog_expiry_prepare_fn prepare_fn, reflog_expiry_should_prune_fn should_prune_fn, reflog_expiry_cleanup_fn cleanup_fn, @@ -405,7 +404,7 @@ static int debug_reflog_expire(struct ref_store *ref_store, const char *refname, .should_prune = should_prune_fn, .cb_data = policy_cb_data, }; - int res = drefs->refs->be->reflog_expire(drefs->refs, refname, oid, + int res = drefs->refs->be->reflog_expire(drefs->refs, refname, flags, &debug_reflog_expiry_prepare, &debug_reflog_expiry_should_prune_fn, &debug_reflog_expiry_cleanup, diff --git a/refs/files-backend.c b/refs/files-backend.c index 8fa328108a..8d627adf99 100644 --- a/refs/files-backend.c +++ b/refs/files-backend.c @@ -341,9 +341,9 @@ static struct ref_cache *get_loose_ref_cache(struct files_ref_store *refs) return refs->loose; } -static int files_read_raw_ref(struct ref_store *ref_store, - const char *refname, struct object_id *oid, - struct strbuf *referent, unsigned int *type) +static int files_read_raw_ref(struct ref_store *ref_store, const char *refname, + struct object_id *oid, struct strbuf *referent, + unsigned int *type, int *failure_errno) { struct files_ref_store *refs = files_downcast(ref_store, REF_STORE_READ, "read_raw_ref"); @@ -354,7 +354,6 @@ static int files_read_raw_ref(struct ref_store *ref_store, struct stat st; int fd; int ret = -1; - int save_errno; int remaining_retries = 3; *type = 0; @@ -459,10 +458,9 @@ stat_ref: ret = parse_loose_ref_contents(buf, oid, referent, type); out: - save_errno = errno; + *failure_errno = errno; strbuf_release(&sb_path); strbuf_release(&sb_contents); - errno = save_errno; return ret; } @@ -531,7 +529,6 @@ static void unlock_ref(struct ref_lock *lock) static int lock_raw_ref(struct files_ref_store *refs, const char *refname, int mustexist, const struct string_list *extras, - const struct string_list *skip, struct ref_lock **lock_p, struct strbuf *referent, unsigned int *type, @@ -541,6 +538,7 @@ static int lock_raw_ref(struct files_ref_store *refs, struct strbuf ref_file = STRBUF_INIT; int attempts_remaining = 3; int ret = TRANSACTION_GENERIC_ERROR; + int failure_errno; assert(err); files_assert_main_repository(refs, "lock_raw_ref"); @@ -568,7 +566,7 @@ retry: * reason to expect this error to be transitory. */ if (refs_verify_refname_available(&refs->base, refname, - extras, skip, err)) { + extras, NULL, err)) { if (mustexist) { /* * To the user the relevant error is @@ -611,7 +609,9 @@ retry: 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) { + int myerr = errno; + errno = 0; + if (myerr == ENOENT && --attempts_remaining > 0) { /* * Maybe somebody just deleted one of the * directories leading to ref_file. Try @@ -619,7 +619,7 @@ retry: */ goto retry; } else { - unable_to_lock_message(ref_file.buf, errno, err); + unable_to_lock_message(ref_file.buf, myerr, err); goto error_return; } } @@ -629,9 +629,9 @@ retry: * fear that its value will change. */ - if (files_read_raw_ref(&refs->base, refname, - &lock->old_oid, referent, type)) { - if (errno == ENOENT) { + if (files_read_raw_ref(&refs->base, refname, &lock->old_oid, referent, + type, &failure_errno)) { + if (failure_errno == ENOENT) { if (mustexist) { /* Garden variety missing reference. */ strbuf_addf(err, "unable to resolve reference '%s'", @@ -655,7 +655,7 @@ retry: * reference named "refs/foo/bar/baz". */ } - } else if (errno == EISDIR) { + } else if (failure_errno == EISDIR) { /* * There is a directory in the way. It might have * contained references that have been deleted. If @@ -673,7 +673,7 @@ retry: REMOVE_DIR_EMPTY_ONLY)) { if (refs_verify_refname_available( &refs->base, refname, - extras, skip, err)) { + extras, NULL, err)) { /* * The error message set by * verify_refname_available() is OK. @@ -693,13 +693,13 @@ retry: goto error_return; } } - } else if (errno == EINVAL && (*type & REF_ISBROKEN)) { + } else if (failure_errno == EINVAL && (*type & REF_ISBROKEN)) { strbuf_addf(err, "unable to resolve reference '%s': " "reference broken", refname); goto error_return; } else { strbuf_addf(err, "unable to resolve reference '%s': %s", - refname, strerror(errno)); + refname, strerror(failure_errno)); goto error_return; } @@ -710,7 +710,7 @@ retry: */ if (refs_verify_refname_available( refs->packed_ref_store, refname, - extras, skip, err)) + extras, NULL, err)) goto error_return; } @@ -854,39 +854,112 @@ static struct ref_iterator *files_ref_iterator_begin( } /* - * Verify that the reference locked by lock has the value old_oid - * (unless it is NULL). Fail if the reference doesn't exist and - * mustexist is set. Return 0 on success. On error, write an error - * message to err, set errno, and return a negative value. + * Callback function for raceproof_create_file(). This function is + * expected to do something that makes dirname(path) permanent despite + * the fact that other processes might be cleaning up empty + * directories at the same time. Usually it will create a file named + * path, but alternatively it could create another file in that + * directory, or even chdir() into that directory. The function should + * return 0 if the action was completed successfully. On error, it + * should return a nonzero result and set errno. + * raceproof_create_file() treats two errno values specially: + * + * - ENOENT -- dirname(path) does not exist. In this case, + * raceproof_create_file() tries creating dirname(path) + * (and any parent directories, if necessary) and calls + * the function again. + * + * - EISDIR -- the file already exists and is a directory. In this + * case, raceproof_create_file() removes the directory if + * it is empty (and recursively any empty directories that + * it contains) and calls the function again. + * + * Any other errno causes raceproof_create_file() to fail with the + * callback's return value and errno. + * + * Obviously, this function should be OK with being called again if it + * fails with ENOENT or EISDIR. In other scenarios it will not be + * called again. + */ +typedef int create_file_fn(const char *path, void *cb); + +/* + * Create a file in dirname(path) by calling fn, creating leading + * directories if necessary. Retry a few times in case we are racing + * with another process that is trying to clean up the directory that + * contains path. See the documentation for create_file_fn for more + * details. + * + * Return the value and set the errno that resulted from the most + * recent call of fn. fn is always called at least once, and will be + * called more than once if it returns ENOENT or EISDIR. */ -static int verify_lock(struct ref_store *ref_store, struct ref_lock *lock, - const struct object_id *old_oid, int mustexist, - struct strbuf *err) +static int raceproof_create_file(const char *path, create_file_fn fn, void *cb) { - assert(err); + /* + * The number of times we will try to remove empty directories + * in the way of path. This is only 1 because if another + * process is racily creating directories that conflict with + * us, we don't want to fight against them. + */ + int remove_directories_remaining = 1; - if (refs_read_ref_full(ref_store, lock->ref_name, - mustexist ? RESOLVE_REF_READING : 0, - &lock->old_oid, NULL)) { - if (old_oid) { - int save_errno = errno; - strbuf_addf(err, "can't verify ref '%s'", lock->ref_name); - errno = save_errno; - return -1; - } else { - oidclr(&lock->old_oid); - return 0; - } - } - if (old_oid && !oideq(&lock->old_oid, old_oid)) { - strbuf_addf(err, "ref '%s' is at %s but expected %s", - lock->ref_name, - oid_to_hex(&lock->old_oid), - oid_to_hex(old_oid)); - errno = EBUSY; - return -1; + /* + * The number of times that we will try to create the + * directories containing path. We are willing to attempt this + * more than once, because another process could be trying to + * clean up empty directories at the same time as we are + * trying to create them. + */ + int create_directories_remaining = 3; + + /* A scratch copy of path, filled lazily if we need it: */ + struct strbuf path_copy = STRBUF_INIT; + + int ret, save_errno; + + /* Sanity check: */ + assert(*path); + +retry_fn: + ret = fn(path, cb); + save_errno = errno; + if (!ret) + goto out; + + if (errno == EISDIR && remove_directories_remaining-- > 0) { + /* + * A directory is in the way. Maybe it is empty; try + * to remove it: + */ + if (!path_copy.len) + strbuf_addstr(&path_copy, path); + + if (!remove_dir_recursively(&path_copy, REMOVE_DIR_EMPTY_ONLY)) + goto retry_fn; + } else if (errno == ENOENT && create_directories_remaining-- > 0) { + /* + * Maybe the containing directory didn't exist, or + * maybe it was just deleted by a process that is + * racing with us to clean up empty directories. Try + * to create it: + */ + enum scld_error scld_result; + + if (!path_copy.len) + strbuf_addstr(&path_copy, path); + + do { + scld_result = safe_create_leading_directories(path_copy.buf); + if (scld_result == SCLD_OK) + goto retry_fn; + } while (scld_result == SCLD_VANISHED && create_directories_remaining-- > 0); } - return 0; + +out: + strbuf_release(&path_copy); + errno = save_errno; + return ret; } static int remove_empty_directories(struct strbuf *path) @@ -910,64 +983,27 @@ static int create_reflock(const char *path, void *cb) /* * Locks a ref returning the lock on success and NULL on failure. - * On failure errno is set to something meaningful. */ static struct ref_lock *lock_ref_oid_basic(struct files_ref_store *refs, - const char *refname, - const struct object_id *old_oid, - const struct string_list *extras, - const struct string_list *skip, - unsigned int flags, int *type, + const char *refname, int *type, struct strbuf *err) { struct strbuf ref_file = STRBUF_INIT; struct ref_lock *lock; - int last_errno = 0; - int mustexist = (old_oid && !is_null_oid(old_oid)); - int resolve_flags = RESOLVE_REF_NO_RECURSE; - int resolved; files_assert_main_repository(refs, "lock_ref_oid_basic"); assert(err); CALLOC_ARRAY(lock, 1); - if (mustexist) - resolve_flags |= RESOLVE_REF_READING; - if (flags & REF_DELETING) - resolve_flags |= RESOLVE_REF_ALLOW_BAD_NAME; - files_ref_path(refs, &ref_file, refname); - resolved = !!refs_resolve_ref_unsafe(&refs->base, - refname, resolve_flags, - &lock->old_oid, type); - if (!resolved && errno == EISDIR) { - /* - * we are trying to lock foo but we used to - * have foo/bar which now does not exist; - * it is normal for the empty directory 'foo' - * to remain. - */ - if (remove_empty_directories(&ref_file)) { - last_errno = errno; - if (!refs_verify_refname_available( - &refs->base, - refname, extras, skip, err)) - strbuf_addf(err, "there are still refs under '%s'", - refname); - goto error_return; - } - resolved = !!refs_resolve_ref_unsafe(&refs->base, - refname, resolve_flags, - &lock->old_oid, type); - } - if (!resolved) { - last_errno = errno; - if (last_errno != ENOTDIR || - !refs_verify_refname_available(&refs->base, refname, - extras, skip, err)) + if (!refs_resolve_ref_unsafe(&refs->base, refname, + RESOLVE_REF_NO_RECURSE, + &lock->old_oid, type)) { + if (!refs_verify_refname_available(&refs->base, refname, + NULL, NULL, err)) strbuf_addf(err, "unable to resolve reference '%s': %s", - refname, strerror(last_errno)); + refname, strerror(errno)); goto error_return; } @@ -980,23 +1016,20 @@ static struct ref_lock *lock_ref_oid_basic(struct files_ref_store *refs, */ if (is_null_oid(&lock->old_oid) && refs_verify_refname_available(refs->packed_ref_store, refname, - extras, skip, err)) { - last_errno = ENOTDIR; + NULL, NULL, err)) goto error_return; - } lock->ref_name = xstrdup(refname); 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; } - if (verify_lock(&refs->base, lock, old_oid, mustexist, err)) { - last_errno = errno; - goto error_return; - } + if (refs_read_ref_full(&refs->base, lock->ref_name, + 0, + &lock->old_oid, NULL)) + oidclr(&lock->old_oid); goto out; error_return: @@ -1005,7 +1038,6 @@ static struct ref_lock *lock_ref_oid_basic(struct files_ref_store *refs, out: strbuf_release(&ref_file); - errno = last_errno; return lock; } @@ -1415,8 +1447,7 @@ static int files_copy_or_rename_ref(struct ref_store *ref_store, logmoved = log; - lock = lock_ref_oid_basic(refs, newrefname, NULL, NULL, NULL, - REF_NO_DEREF, NULL, &err); + lock = lock_ref_oid_basic(refs, newrefname, NULL, &err); if (!lock) { if (copy) error("unable to copy '%s' to '%s': %s", oldrefname, newrefname, err.buf); @@ -1438,8 +1469,7 @@ static int files_copy_or_rename_ref(struct ref_store *ref_store, goto out; rollback: - lock = lock_ref_oid_basic(refs, oldrefname, NULL, NULL, NULL, - REF_NO_DEREF, NULL, &err); + lock = lock_ref_oid_basic(refs, oldrefname, NULL, &err); if (!lock) { error("unable to lock %s for rollback: %s", oldrefname, err.buf); strbuf_release(&err); @@ -1846,9 +1876,7 @@ static int files_create_symref(struct ref_store *ref_store, struct ref_lock *lock; int ret; - lock = lock_ref_oid_basic(refs, refname, NULL, - NULL, NULL, REF_NO_DEREF, NULL, - &err); + lock = lock_ref_oid_basic(refs, refname, NULL, &err); if (!lock) { error("%s", err.buf); strbuf_release(&err); @@ -2416,7 +2444,7 @@ static int lock_ref_for_update(struct files_ref_store *refs, } ret = lock_raw_ref(refs, update->refname, mustexist, - affected_refnames, NULL, + affected_refnames, &lock, &referent, &update->type, err); if (ret) { @@ -3037,7 +3065,7 @@ static int expire_reflog_ent(struct object_id *ooid, struct object_id *noid, } static int files_reflog_expire(struct ref_store *ref_store, - const char *refname, const struct object_id *oid, + const char *refname, unsigned int flags, reflog_expiry_prepare_fn prepare_fn, reflog_expiry_should_prune_fn should_prune_fn, @@ -3054,6 +3082,7 @@ static int files_reflog_expire(struct ref_store *ref_store, int status = 0; int type; struct strbuf err = STRBUF_INIT; + const struct object_id *oid; memset(&cb, 0, sizeof(cb)); cb.flags = flags; @@ -3065,14 +3094,26 @@ static int files_reflog_expire(struct ref_store *ref_store, * reference itself, plus we might need to update the * reference if --updateref was specified: */ - lock = lock_ref_oid_basic(refs, refname, oid, - NULL, NULL, REF_NO_DEREF, - &type, &err); + lock = lock_ref_oid_basic(refs, refname, &type, &err); if (!lock) { error("cannot lock ref '%s': %s", refname, err.buf); strbuf_release(&err); return -1; } + oid = &lock->old_oid; + + /* + * When refs are deleted, their reflog is deleted before the + * ref itself is deleted. This is because there is no separate + * lock for reflog; instead we take a lock on the ref with + * lock_ref_oid_basic(). + * + * If a race happens and the reflog doesn't exist after we've + * acquired the lock that's OK. We've got nothing more to do; + * We were asked to delete the reflog, but someone else + * deleted it! The caller doesn't care that we deleted it, + * just that it is deleted. So we can return successfully. + */ if (!refs_reflog_exists(ref_store, refname)) { unlock_ref(lock); return 0; diff --git a/refs/packed-backend.c b/refs/packed-backend.c index f8aa97d799..47247a1491 100644 --- a/refs/packed-backend.c +++ b/refs/packed-backend.c @@ -724,9 +724,9 @@ static struct snapshot *get_snapshot(struct packed_ref_store *refs) return refs->snapshot; } -static int packed_read_raw_ref(struct ref_store *ref_store, - const char *refname, struct object_id *oid, - struct strbuf *referent, unsigned int *type) +static int packed_read_raw_ref(struct ref_store *ref_store, const char *refname, + struct object_id *oid, struct strbuf *referent, + unsigned int *type, int *failure_errno) { struct packed_ref_store *refs = packed_downcast(ref_store, REF_STORE_READ, "read_raw_ref"); @@ -739,7 +739,7 @@ static int packed_read_raw_ref(struct ref_store *ref_store, if (!rec) { /* refname is not a packed reference. */ - errno = ENOENT; + *failure_errno = ENOENT; return -1; } @@ -1600,6 +1600,7 @@ static int packed_for_each_reflog_ent(struct ref_store *ref_store, const char *refname, each_reflog_ent_fn fn, void *cb_data) { + BUG("packed reference store does not support reflogs"); return 0; } @@ -1608,12 +1609,14 @@ static int packed_for_each_reflog_ent_reverse(struct ref_store *ref_store, each_reflog_ent_fn fn, void *cb_data) { + BUG("packed reference store does not support reflogs"); return 0; } static int packed_reflog_exists(struct ref_store *ref_store, const char *refname) { + BUG("packed reference store does not support reflogs"); return 0; } @@ -1627,17 +1630,19 @@ static int packed_create_reflog(struct ref_store *ref_store, static int packed_delete_reflog(struct ref_store *ref_store, const char *refname) { + BUG("packed reference store does not support reflogs"); return 0; } static int packed_reflog_expire(struct ref_store *ref_store, - const char *refname, const struct object_id *oid, + const char *refname, 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) { + BUG("packed reference store does not support reflogs"); return 0; } diff --git a/refs/refs-internal.h b/refs/refs-internal.h index 3155708345..ddd6d7f8eb 100644 --- a/refs/refs-internal.h +++ b/refs/refs-internal.h @@ -593,7 +593,7 @@ typedef int create_reflog_fn(struct ref_store *ref_store, const char *refname, int force_create, struct strbuf *err); typedef int delete_reflog_fn(struct ref_store *ref_store, const char *refname); typedef int reflog_expire_fn(struct ref_store *ref_store, - const char *refname, const struct object_id *oid, + const char *refname, unsigned int flags, reflog_expiry_prepare_fn prepare_fn, reflog_expiry_should_prune_fn should_prune_fn, @@ -620,11 +620,15 @@ typedef int reflog_expire_fn(struct ref_store *ref_store, * properly-formatted or even safe reference name. NEITHER INPUT NOR * OUTPUT REFERENCE NAMES ARE VALIDATED WITHIN THIS FUNCTION. * - * Return 0 on success. If the ref doesn't exist, set errno to ENOENT - * and return -1. If the ref exists but is neither a symbolic ref nor - * an object ID, it is broken; set REF_ISBROKEN in type, set errno to - * EINVAL, and return -1. If there is another error reading the ref, - * set errno appropriately and return -1. + * Return 0 on success, or -1 on failure. If the ref exists but is neither a + * symbolic ref nor an object ID, it is broken. In this case set REF_ISBROKEN in + * type, and return -1 (failure_errno should not be ENOENT) + * + * failure_errno provides errno codes that are interpreted beyond error + * reporting. The following error codes have special meaning: + * * ENOENT: the ref doesn't exist + * * EISDIR: ref name is a directory + * * ENOTDIR: ref prefix is not a directory * * Backend-specific flags might be set in type as well, regardless of * outcome. @@ -638,9 +642,9 @@ typedef int reflog_expire_fn(struct ref_store *ref_store, * - in all other cases, referent will be untouched, and therefore * refname will still be valid and unchanged. */ -typedef int read_raw_ref_fn(struct ref_store *ref_store, - const char *refname, struct object_id *oid, - struct strbuf *referent, unsigned int *type); +typedef int read_raw_ref_fn(struct ref_store *ref_store, const char *refname, + struct object_id *oid, struct strbuf *referent, + unsigned int *type, int *failure_errno); struct ref_storage_be { struct ref_storage_be *next; |