+++ /dev/null
- /*
- Unix SMB/CIFS implementation.
-
- trivial database library
-
- Copyright (C) Andrew Tridgell 1999-2005
- Copyright (C) Paul `Rusty' Russell 2000
- Copyright (C) Jeremy Allison 2000-2003
-
- ** NOTE! The following LGPL license applies to the tdb
- ** library. This does NOT imply that all of Samba is released
- ** under the LGPL
-
- This library is free software; you can redistribute it and/or
- modify it under the terms of the GNU Lesser General Public
- License as published by the Free Software Foundation; either
- version 3 of the License, or (at your option) any later version.
-
- This library is distributed in the hope that it will be useful,
- but WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- Lesser General Public License for more details.
-
- You should have received a copy of the GNU Lesser General Public
- License along with this library; if not, see <http://www.gnu.org/licenses/>.
-*/
-
-#include "tdb_private.h"
-
-#define TDB_NEXT_LOCK_ERR ((tdb_off_t)-1)
-
-/* Uses traverse lock: 0 = finish, TDB_NEXT_LOCK_ERR = error,
- other = record offset */
-static tdb_off_t tdb_next_lock(struct tdb_context *tdb, struct tdb_traverse_lock *tlock,
- struct tdb_record *rec)
-{
- int want_next = (tlock->off != 0);
-
- /* Lock each chain from the start one. */
- for (; tlock->hash < tdb->header.hash_size; tlock->hash++) {
- if (!tlock->off && tlock->hash != 0) {
- /* this is an optimization for the common case where
- the hash chain is empty, which is particularly
- common for the use of tdb with ldb, where large
- hashes are used. In that case we spend most of our
- time in tdb_brlock(), locking empty hash chains.
-
- To avoid this, we do an unlocked pre-check to see
- if the hash chain is empty before starting to look
- inside it. If it is empty then we can avoid that
- hash chain. If it isn't empty then we can't believe
- the value we get back, as we read it without a
- lock, so instead we get the lock and re-fetch the
- value below.
-
- Notice that not doing this optimization on the
- first hash chain is critical. We must guarantee
- that we have done at least one fcntl lock at the
- start of a search to guarantee that memory is
- coherent on SMP systems. If records are added by
- others during the search then thats OK, and we
- could possibly miss those with this trick, but we
- could miss them anyway without this trick, so the
- semantics don't change.
-
- With a non-indexed ldb search this trick gains us a
- factor of around 80 in speed on a linux 2.6.x
- system (testing using ldbtest).
- */
- tdb->methods->next_hash_chain(tdb, &tlock->hash);
- if (tlock->hash == tdb->header.hash_size) {
- continue;
- }
- }
-
- if (tdb_lock(tdb, tlock->hash, tlock->lock_rw) == -1)
- return TDB_NEXT_LOCK_ERR;
-
- /* No previous record? Start at top of chain. */
- if (!tlock->off) {
- if (tdb_ofs_read(tdb, TDB_HASH_TOP(tlock->hash),
- &tlock->off) == -1)
- goto fail;
- } else {
- /* Otherwise unlock the previous record. */
- if (tdb_unlock_record(tdb, tlock->off) != 0)
- goto fail;
- }
-
- if (want_next) {
- /* We have offset of old record: grab next */
- if (tdb_rec_read(tdb, tlock->off, rec) == -1)
- goto fail;
- tlock->off = rec->next;
- }
-
- /* Iterate through chain */
- while( tlock->off) {
- tdb_off_t current;
- if (tdb_rec_read(tdb, tlock->off, rec) == -1)
- goto fail;
-
- /* Detect infinite loops. From "Shlomi Yaakobovich" <Shlomi@exanet.com>. */
- if (tlock->off == rec->next) {
- tdb->ecode = TDB_ERR_CORRUPT;
- TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_next_lock: loop detected.\n"));
- goto fail;
- }
-
- if (!TDB_DEAD(rec)) {
- /* Woohoo: we found one! */
- if (tdb_lock_record(tdb, tlock->off) != 0)
- goto fail;
- return tlock->off;
- }
-
- /* Try to clean dead ones from old traverses */
- current = tlock->off;
- tlock->off = rec->next;
- if (!(tdb->read_only || tdb->traverse_read) &&
- tdb_do_delete(tdb, current, rec) != 0)
- goto fail;
- }
- tdb_unlock(tdb, tlock->hash, tlock->lock_rw);
- want_next = 0;
- }
- /* We finished iteration without finding anything */
- tdb->ecode = TDB_SUCCESS;
- return 0;
-
- fail:
- tlock->off = 0;
- if (tdb_unlock(tdb, tlock->hash, tlock->lock_rw) != 0)
- TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_next_lock: On error unlock failed!\n"));
- return TDB_NEXT_LOCK_ERR;
-}
-
-/* traverse the entire database - calling fn(tdb, key, data) on each element.
- return -1 on error or the record count traversed
- if fn is NULL then it is not called
- a non-zero return value from fn() indicates that the traversal should stop
- */
-static int tdb_traverse_internal(struct tdb_context *tdb,
- tdb_traverse_func fn, void *private_data,
- struct tdb_traverse_lock *tl)
-{
- TDB_DATA key, dbuf;
- struct tdb_record rec;
- int ret = 0, count = 0;
- tdb_off_t off;
-
- /* This was in the initializaton, above, but the IRIX compiler
- * did not like it. crh
- */
- tl->next = tdb->travlocks.next;
-
- /* fcntl locks don't stack: beware traverse inside traverse */
- tdb->travlocks.next = tl;
-
- /* tdb_next_lock places locks on the record returned, and its chain */
- while ((off = tdb_next_lock(tdb, tl, &rec)) != 0) {
- if (off == TDB_NEXT_LOCK_ERR) {
- ret = -1;
- goto out;
- }
- count++;
- /* now read the full record */
- key.dptr = tdb_alloc_read(tdb, tl->off + sizeof(rec),
- rec.key_len + rec.data_len);
- if (!key.dptr) {
- ret = -1;
- if (tdb_unlock(tdb, tl->hash, tl->lock_rw) != 0)
- goto out;
- if (tdb_unlock_record(tdb, tl->off) != 0)
- TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_traverse: key.dptr == NULL and unlock_record failed!\n"));
- goto out;
- }
- key.dsize = rec.key_len;
- dbuf.dptr = key.dptr + rec.key_len;
- dbuf.dsize = rec.data_len;
-
- tdb_trace_1rec_retrec(tdb, "traverse", key, dbuf);
-
- /* Drop chain lock, call out */
- if (tdb_unlock(tdb, tl->hash, tl->lock_rw) != 0) {
- ret = -1;
- SAFE_FREE(key.dptr);
- goto out;
- }
- if (fn && fn(tdb, key, dbuf, private_data)) {
- /* They want us to terminate traversal */
- tdb_trace_ret(tdb, "tdb_traverse_end", count);
- if (tdb_unlock_record(tdb, tl->off) != 0) {
- TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_traverse: unlock_record failed!\n"));;
- ret = -1;
- }
- SAFE_FREE(key.dptr);
- goto out;
- }
- SAFE_FREE(key.dptr);
- }
- tdb_trace(tdb, "tdb_traverse_end");
-out:
- tdb->travlocks.next = tl->next;
- if (ret < 0)
- return -1;
- else
- return count;
-}
-
-
-/*
- a write style traverse - temporarily marks the db read only
-*/
-int tdb_traverse_read(struct tdb_context *tdb,
- tdb_traverse_func fn, void *private_data)
-{
- struct tdb_traverse_lock tl = { NULL, 0, 0, F_RDLCK };
- int ret;
-
- /* we need to get a read lock on the transaction lock here to
- cope with the lock ordering semantics of solaris10 */
- if (tdb_transaction_lock(tdb, F_RDLCK)) {
- return -1;
- }
-
- tdb->traverse_read++;
- tdb_trace(tdb, "tdb_traverse_read_start");
- ret = tdb_traverse_internal(tdb, fn, private_data, &tl);
- tdb->traverse_read--;
-
- tdb_transaction_unlock(tdb, F_RDLCK);
-
- return ret;
-}
-
-/*
- a write style traverse - needs to get the transaction lock to
- prevent deadlocks
-
- WARNING: The data buffer given to the callback fn does NOT meet the
- alignment restrictions malloc gives you.
-*/
-int tdb_traverse(struct tdb_context *tdb,
- tdb_traverse_func fn, void *private_data)
-{
- struct tdb_traverse_lock tl = { NULL, 0, 0, F_WRLCK };
- int ret;
-
- if (tdb->read_only || tdb->traverse_read) {
- return tdb_traverse_read(tdb, fn, private_data);
- }
-
- if (tdb_transaction_lock(tdb, F_WRLCK)) {
- return -1;
- }
-
- tdb->traverse_write++;
- tdb_trace(tdb, "tdb_traverse_start");
- ret = tdb_traverse_internal(tdb, fn, private_data, &tl);
- tdb->traverse_write--;
-
- tdb_transaction_unlock(tdb, F_WRLCK);
-
- return ret;
-}
-
-
-/* find the first entry in the database and return its key */
-TDB_DATA tdb_firstkey(struct tdb_context *tdb)
-{
- TDB_DATA key;
- struct tdb_record rec;
- tdb_off_t off;
-
- /* release any old lock */
- if (tdb_unlock_record(tdb, tdb->travlocks.off) != 0)
- return tdb_null;
- tdb->travlocks.off = tdb->travlocks.hash = 0;
- tdb->travlocks.lock_rw = F_RDLCK;
-
- /* Grab first record: locks chain and returned record. */
- off = tdb_next_lock(tdb, &tdb->travlocks, &rec);
- if (off == 0 || off == TDB_NEXT_LOCK_ERR) {
- tdb_trace_retrec(tdb, "tdb_firstkey", tdb_null);
- return tdb_null;
- }
- /* now read the key */
- key.dsize = rec.key_len;
- key.dptr =tdb_alloc_read(tdb,tdb->travlocks.off+sizeof(rec),key.dsize);
-
- tdb_trace_retrec(tdb, "tdb_firstkey", key);
-
- /* Unlock the hash chain of the record we just read. */
- if (tdb_unlock(tdb, tdb->travlocks.hash, tdb->travlocks.lock_rw) != 0)
- TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_firstkey: error occurred while tdb_unlocking!\n"));
- return key;
-}
-
-/* find the next entry in the database, returning its key */
-TDB_DATA tdb_nextkey(struct tdb_context *tdb, TDB_DATA oldkey)
-{
- uint32_t oldhash;
- TDB_DATA key = tdb_null;
- struct tdb_record rec;
- unsigned char *k = NULL;
- tdb_off_t off;
-
- /* Is locked key the old key? If so, traverse will be reliable. */
- if (tdb->travlocks.off) {
- if (tdb_lock(tdb,tdb->travlocks.hash,tdb->travlocks.lock_rw))
- return tdb_null;
- if (tdb_rec_read(tdb, tdb->travlocks.off, &rec) == -1
- || !(k = tdb_alloc_read(tdb,tdb->travlocks.off+sizeof(rec),
- rec.key_len))
- || memcmp(k, oldkey.dptr, oldkey.dsize) != 0) {
- /* No, it wasn't: unlock it and start from scratch */
- if (tdb_unlock_record(tdb, tdb->travlocks.off) != 0) {
- tdb_trace_1rec_retrec(tdb, "tdb_nextkey",
- oldkey, tdb_null);
- SAFE_FREE(k);
- return tdb_null;
- }
- if (tdb_unlock(tdb, tdb->travlocks.hash, tdb->travlocks.lock_rw) != 0) {
- SAFE_FREE(k);
- return tdb_null;
- }
- tdb->travlocks.off = 0;
- }
-
- SAFE_FREE(k);
- }
-
- if (!tdb->travlocks.off) {
- /* No previous element: do normal find, and lock record */
- tdb->travlocks.off = tdb_find_lock_hash(tdb, oldkey, tdb->hash_fn(&oldkey), tdb->travlocks.lock_rw, &rec);
- if (!tdb->travlocks.off) {
- tdb_trace_1rec_retrec(tdb, "tdb_nextkey", oldkey, tdb_null);
- return tdb_null;
- }
- tdb->travlocks.hash = BUCKET(rec.full_hash);
- if (tdb_lock_record(tdb, tdb->travlocks.off) != 0) {
- TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_nextkey: lock_record failed (%s)!\n", strerror(errno)));
- return tdb_null;
- }
- }
- oldhash = tdb->travlocks.hash;
-
- /* Grab next record: locks chain and returned record,
- unlocks old record */
- off = tdb_next_lock(tdb, &tdb->travlocks, &rec);
- if (off != TDB_NEXT_LOCK_ERR && off != 0) {
- key.dsize = rec.key_len;
- key.dptr = tdb_alloc_read(tdb, tdb->travlocks.off+sizeof(rec),
- key.dsize);
- /* Unlock the chain of this new record */
- if (tdb_unlock(tdb, tdb->travlocks.hash, tdb->travlocks.lock_rw) != 0)
- TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_nextkey: WARNING tdb_unlock failed!\n"));
- }
- /* Unlock the chain of old record */
- if (tdb_unlock(tdb, BUCKET(oldhash), tdb->travlocks.lock_rw) != 0)
- TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_nextkey: WARNING tdb_unlock failed!\n"));
- tdb_trace_1rec_retrec(tdb, "tdb_nextkey", oldkey, key);
- return key;
-}
-
projects / ccan / blobdiff