--- /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"
+
+void tdb_setalarm_sigptr(struct tdb_context *tdb, volatile sig_atomic_t *ptr)
+{
+ tdb->interrupt_sig_ptr = ptr;
+}
+
+static int fcntl_lock(struct tdb_context *tdb,
+ int rw, off_t off, off_t len, bool waitflag)
+{
+ struct flock fl;
+
+ fl.l_type = rw;
+ fl.l_whence = SEEK_SET;
+ fl.l_start = off;
+ fl.l_len = len;
+ fl.l_pid = 0;
+
+ if (waitflag)
+ return fcntl(tdb->fd, F_SETLKW, &fl);
+ else
+ return fcntl(tdb->fd, F_SETLK, &fl);
+}
+
+static int fcntl_unlock(struct tdb_context *tdb, int rw, off_t off, off_t len)
+{
+ struct flock fl;
+#if 0 /* Check they matched up locks and unlocks correctly. */
+ char line[80];
+ FILE *locks;
+ bool found = false;
+
+ locks = fopen("/proc/locks", "r");
+
+ while (fgets(line, 80, locks)) {
+ char *p;
+ int type, start, l;
+
+ /* eg. 1: FLOCK ADVISORY WRITE 2440 08:01:2180826 0 EOF */
+ p = strchr(line, ':') + 1;
+ if (strncmp(p, " POSIX ADVISORY ", strlen(" POSIX ADVISORY ")))
+ continue;
+ p += strlen(" FLOCK ADVISORY ");
+ if (strncmp(p, "READ ", strlen("READ ")) == 0)
+ type = F_RDLCK;
+ else if (strncmp(p, "WRITE ", strlen("WRITE ")) == 0)
+ type = F_WRLCK;
+ else
+ abort();
+ p += 6;
+ if (atoi(p) != getpid())
+ continue;
+ p = strchr(strchr(p, ' ') + 1, ' ') + 1;
+ start = atoi(p);
+ p = strchr(p, ' ') + 1;
+ if (strncmp(p, "EOF", 3) == 0)
+ l = 0;
+ else
+ l = atoi(p) - start + 1;
+
+ if (off == start) {
+ if (len != l) {
+ fprintf(stderr, "Len %u should be %u: %s",
+ (int)len, l, line);
+ abort();
+ }
+ if (type != rw) {
+ fprintf(stderr, "Type %s wrong: %s",
+ rw == F_RDLCK ? "READ" : "WRITE", line);
+ abort();
+ }
+ found = true;
+ break;
+ }
+ }
+
+ if (!found) {
+ fprintf(stderr, "Unlock on %u@%u not found!\n",
+ (int)off, (int)len);
+ abort();
+ }
+
+ fclose(locks);
+#endif
+
+ fl.l_type = F_UNLCK;
+ fl.l_whence = SEEK_SET;
+ fl.l_start = off;
+ fl.l_len = len;
+ fl.l_pid = 0;
+
+ return fcntl(tdb->fd, F_SETLKW, &fl);
+}
+
+/* list -1 is the alloc list, otherwise a hash chain. */
+static tdb_off_t lock_offset(int list)
+{
+ return FREELIST_TOP + 4*list;
+}
+
+/* a byte range locking function - return 0 on success
+ this functions locks/unlocks 1 byte at the specified offset.
+
+ On error, errno is also set so that errors are passed back properly
+ through tdb_open().
+
+ note that a len of zero means lock to end of file
+*/
+int tdb_brlock(struct tdb_context *tdb,
+ int rw_type, tdb_off_t offset, size_t len,
+ enum tdb_lock_flags flags)
+{
+ int ret;
+
+ if (tdb->flags & TDB_NOLOCK) {
+ return 0;
+ }
+
+ if (flags & TDB_LOCK_MARK_ONLY) {
+ return 0;
+ }
+
+ if ((rw_type == F_WRLCK) && (tdb->read_only || tdb->traverse_read)) {
+ tdb->ecode = TDB_ERR_RDONLY;
+ return -1;
+ }
+
+ do {
+ ret = fcntl_lock(tdb, rw_type, offset, len,
+ flags & TDB_LOCK_WAIT);
+ /* Check for a sigalarm break. */
+ if (ret == -1 && errno == EINTR &&
+ tdb->interrupt_sig_ptr &&
+ *tdb->interrupt_sig_ptr) {
+ break;
+ }
+ } while (ret == -1 && errno == EINTR);
+
+ if (ret == -1) {
+ tdb->ecode = TDB_ERR_LOCK;
+ /* Generic lock error. errno set by fcntl.
+ * EAGAIN is an expected return from non-blocking
+ * locks. */
+ if (!(flags & TDB_LOCK_PROBE) && errno != EAGAIN) {
+ TDB_LOG((tdb, TDB_DEBUG_TRACE,"tdb_brlock failed (fd=%d) at offset %d rw_type=%d flags=%d len=%d\n",
+ tdb->fd, offset, rw_type, flags, (int)len));
+ }
+ return -1;
+ }
+ return 0;
+}
+
+int tdb_brunlock(struct tdb_context *tdb,
+ int rw_type, tdb_off_t offset, size_t len)
+{
+ int ret;
+
+ if (tdb->flags & TDB_NOLOCK) {
+ return 0;
+ }
+
+ do {
+ ret = fcntl_unlock(tdb, rw_type, offset, len);
+ } while (ret == -1 && errno == EINTR);
+
+ if (ret == -1) {
+ TDB_LOG((tdb, TDB_DEBUG_TRACE,"tdb_brunlock failed (fd=%d) at offset %d rw_type=%d len=%d\n",
+ tdb->fd, offset, rw_type, (int)len));
+ }
+ return ret;
+}
+
+/*
+ upgrade a read lock to a write lock. This needs to be handled in a
+ special way as some OSes (such as solaris) have too conservative
+ deadlock detection and claim a deadlock when progress can be
+ made. For those OSes we may loop for a while.
+*/
+int tdb_allrecord_upgrade(struct tdb_context *tdb)
+{
+ int count = 1000;
+
+ if (tdb->allrecord_lock.count != 1) {
+ TDB_LOG((tdb, TDB_DEBUG_ERROR,
+ "tdb_allrecord_upgrade failed: count %u too high\n",
+ tdb->allrecord_lock.count));
+ return -1;
+ }
+
+ if (tdb->allrecord_lock.off != 1) {
+ TDB_LOG((tdb, TDB_DEBUG_ERROR,
+ "tdb_allrecord_upgrade failed: already upgraded?\n"));
+ return -1;
+ }
+
+ while (count--) {
+ struct timeval tv;
+ if (tdb_brlock(tdb, F_WRLCK, FREELIST_TOP, 0,
+ TDB_LOCK_WAIT|TDB_LOCK_PROBE) == 0) {
+ tdb->allrecord_lock.ltype = F_WRLCK;
+ tdb->allrecord_lock.off = 0;
+ return 0;
+ }
+ if (errno != EDEADLK) {
+ break;
+ }
+ /* sleep for as short a time as we can - more portable than usleep() */
+ tv.tv_sec = 0;
+ tv.tv_usec = 1;
+ select(0, NULL, NULL, NULL, &tv);
+ }
+ TDB_LOG((tdb, TDB_DEBUG_TRACE,"tdb_allrecord_upgrade failed\n"));
+ return -1;
+}
+
+static struct tdb_lock_type *find_nestlock(struct tdb_context *tdb,
+ tdb_off_t offset)
+{
+ unsigned int i;
+
+ for (i=0; i<tdb->num_lockrecs; i++) {
+ if (tdb->lockrecs[i].off == offset) {
+ return &tdb->lockrecs[i];
+ }
+ }
+ return NULL;
+}
+
+/* lock an offset in the database. */
+int tdb_nest_lock(struct tdb_context *tdb, uint32_t offset, int ltype,
+ enum tdb_lock_flags flags)
+{
+ struct tdb_lock_type *new_lck;
+
+ if (offset >= lock_offset(tdb->header.hash_size)) {
+ tdb->ecode = TDB_ERR_LOCK;
+ TDB_LOG((tdb, TDB_DEBUG_ERROR,"tdb_lock: invalid offset %u for ltype=%d\n",
+ offset, ltype));
+ return -1;
+ }
+ if (tdb->flags & TDB_NOLOCK)
+ return 0;
+
+ new_lck = find_nestlock(tdb, offset);
+ if (new_lck) {
+ /*
+ * Just increment the in-memory struct, posix locks
+ * don't stack.
+ */
+ new_lck->count++;
+ return 0;
+ }
+
+ new_lck = (struct tdb_lock_type *)realloc(
+ tdb->lockrecs,
+ sizeof(*tdb->lockrecs) * (tdb->num_lockrecs+1));
+ if (new_lck == NULL) {
+ errno = ENOMEM;
+ return -1;
+ }
+ tdb->lockrecs = new_lck;
+
+ /* Since fcntl locks don't nest, we do a lock for the first one,
+ and simply bump the count for future ones */
+ if (tdb_brlock(tdb, ltype, offset, 1, flags)) {
+ return -1;
+ }
+
+ tdb->lockrecs[tdb->num_lockrecs].off = offset;
+ tdb->lockrecs[tdb->num_lockrecs].count = 1;
+ tdb->lockrecs[tdb->num_lockrecs].ltype = ltype;
+ tdb->num_lockrecs++;
+
+ return 0;
+}
+
+static int tdb_lock_and_recover(struct tdb_context *tdb)
+{
+ int ret;
+
+ /* We need to match locking order in transaction commit. */
+ if (tdb_brlock(tdb, F_WRLCK, FREELIST_TOP, 0, TDB_LOCK_WAIT)) {
+ return -1;
+ }
+
+ if (tdb_brlock(tdb, F_WRLCK, OPEN_LOCK, 1, TDB_LOCK_WAIT)) {
+ tdb_brunlock(tdb, F_WRLCK, FREELIST_TOP, 0);
+ return -1;
+ }
+
+ ret = tdb_transaction_recover(tdb);
+
+ tdb_brunlock(tdb, F_WRLCK, OPEN_LOCK, 1);
+ tdb_brunlock(tdb, F_WRLCK, FREELIST_TOP, 0);
+
+ return ret;
+}
+
+static bool have_data_locks(const struct tdb_context *tdb)
+{
+ unsigned int i;
+
+ for (i = 0; i < tdb->num_lockrecs; i++) {
+ if (tdb->lockrecs[i].off >= lock_offset(-1))
+ return true;
+ }
+ return false;
+}
+
+static int tdb_lock_list(struct tdb_context *tdb, int list, int ltype,
+ enum tdb_lock_flags waitflag)
+{
+ int ret;
+ bool check = false;
+
+ /* a allrecord lock allows us to avoid per chain locks */
+ if (tdb->allrecord_lock.count &&
+ (ltype == tdb->allrecord_lock.ltype || ltype == F_RDLCK)) {
+ return 0;
+ }
+
+ if (tdb->allrecord_lock.count) {
+ tdb->ecode = TDB_ERR_LOCK;
+ ret = -1;
+ } else {
+ /* Only check when we grab first data lock. */
+ check = !have_data_locks(tdb);
+ ret = tdb_nest_lock(tdb, lock_offset(list), ltype, waitflag);
+
+ if (ret == 0 && check && tdb_needs_recovery(tdb)) {
+ tdb_nest_unlock(tdb, lock_offset(list), ltype, false);
+
+ if (tdb_lock_and_recover(tdb) == -1) {
+ return -1;
+ }
+ return tdb_lock_list(tdb, list, ltype, waitflag);
+ }
+ }
+ return ret;
+}
+
+/* lock a list in the database. list -1 is the alloc list */
+int tdb_lock(struct tdb_context *tdb, int list, int ltype)
+{
+ int ret;
+
+ ret = tdb_lock_list(tdb, list, ltype, TDB_LOCK_WAIT);
+ if (ret) {
+ TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_lock failed on list %d "
+ "ltype=%d (%s)\n", list, ltype, strerror(errno)));
+ }
+ return ret;
+}
+
+/* lock a list in the database. list -1 is the alloc list. non-blocking lock */
+int tdb_lock_nonblock(struct tdb_context *tdb, int list, int ltype)
+{
+ return tdb_lock_list(tdb, list, ltype, TDB_LOCK_NOWAIT);
+}
+
+
+int tdb_nest_unlock(struct tdb_context *tdb, uint32_t offset, int ltype,
+ bool mark_lock)
+{
+ int ret = -1;
+ struct tdb_lock_type *lck;
+
+ if (tdb->flags & TDB_NOLOCK)
+ return 0;
+
+ /* Sanity checks */
+ if (offset >= lock_offset(tdb->header.hash_size)) {
+ TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_unlock: offset %u invalid (%d)\n", offset, tdb->header.hash_size));
+ return ret;
+ }
+
+ lck = find_nestlock(tdb, offset);
+ if ((lck == NULL) || (lck->count == 0)) {
+ TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_unlock: count is 0\n"));
+ return -1;
+ }
+
+ if (lck->count > 1) {
+ lck->count--;
+ return 0;
+ }
+
+ /*
+ * This lock has count==1 left, so we need to unlock it in the
+ * kernel. We don't bother with decrementing the in-memory array
+ * element, we're about to overwrite it with the last array element
+ * anyway.
+ */
+
+ if (mark_lock) {
+ ret = 0;
+ } else {
+ ret = tdb_brunlock(tdb, ltype, offset, 1);
+ }
+
+ /*
+ * Shrink the array by overwriting the element just unlocked with the
+ * last array element.
+ */
+ *lck = tdb->lockrecs[--tdb->num_lockrecs];
+
+ /*
+ * We don't bother with realloc when the array shrinks, but if we have
+ * a completely idle tdb we should get rid of the locked array.
+ */
+
+ if (tdb->num_lockrecs == 0) {
+ SAFE_FREE(tdb->lockrecs);
+ }
+
+ if (ret)
+ TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_unlock: An error occurred unlocking!\n"));
+ return ret;
+}
+
+int tdb_unlock(struct tdb_context *tdb, int list, int ltype)
+{
+ /* a global lock allows us to avoid per chain locks */
+ if (tdb->allrecord_lock.count &&
+ (ltype == tdb->allrecord_lock.ltype || ltype == F_RDLCK)) {
+ return 0;
+ }
+
+ if (tdb->allrecord_lock.count) {
+ tdb->ecode = TDB_ERR_LOCK;
+ return -1;
+ }
+
+ return tdb_nest_unlock(tdb, lock_offset(list), ltype, false);
+}
+
+/*
+ get the transaction lock
+ */
+int tdb_transaction_lock(struct tdb_context *tdb, int ltype,
+ enum tdb_lock_flags lockflags)
+{
+ return tdb_nest_lock(tdb, TRANSACTION_LOCK, ltype, lockflags);
+}
+
+/*
+ release the transaction lock
+ */
+int tdb_transaction_unlock(struct tdb_context *tdb, int ltype)
+{
+ return tdb_nest_unlock(tdb, TRANSACTION_LOCK, ltype, false);
+}
+
+/* Returns 0 if all done, -1 if error, 1 if ok. */
+static int tdb_allrecord_check(struct tdb_context *tdb, int ltype,
+ enum tdb_lock_flags flags, bool upgradable)
+{
+ /* There are no locks on read-only dbs */
+ if (tdb->read_only || tdb->traverse_read) {
+ tdb->ecode = TDB_ERR_LOCK;
+ return -1;
+ }
+
+ if (tdb->allrecord_lock.count && tdb->allrecord_lock.ltype == ltype) {
+ tdb->allrecord_lock.count++;
+ return 0;
+ }
+
+ if (tdb->allrecord_lock.count) {
+ /* a global lock of a different type exists */
+ tdb->ecode = TDB_ERR_LOCK;
+ return -1;
+ }
+
+ if (tdb_have_extra_locks(tdb)) {
+ /* can't combine global and chain locks */
+ tdb->ecode = TDB_ERR_LOCK;
+ return -1;
+ }
+
+ if (upgradable && ltype != F_RDLCK) {
+ /* tdb error: you can't upgrade a write lock! */
+ tdb->ecode = TDB_ERR_LOCK;
+ return -1;
+ }
+ return 1;
+}
+
+/* We only need to lock individual bytes, but Linux merges consecutive locks
+ * so we lock in contiguous ranges. */
+static int tdb_chainlock_gradual(struct tdb_context *tdb,
+ int ltype, enum tdb_lock_flags flags,
+ size_t off, size_t len)
+{
+ int ret;
+ enum tdb_lock_flags nb_flags = (flags & ~TDB_LOCK_WAIT);
+
+ if (len <= 4) {
+ /* Single record. Just do blocking lock. */
+ return tdb_brlock(tdb, ltype, off, len, flags);
+ }
+
+ /* First we try non-blocking. */
+ ret = tdb_brlock(tdb, ltype, off, len, nb_flags);
+ if (ret == 0) {
+ return 0;
+ }
+
+ /* Try locking first half, then second. */
+ ret = tdb_chainlock_gradual(tdb, ltype, flags, off, len / 2);
+ if (ret == -1)
+ return -1;
+
+ ret = tdb_chainlock_gradual(tdb, ltype, flags,
+ off + len / 2, len - len / 2);
+ if (ret == -1) {
+ tdb_brunlock(tdb, ltype, off, len / 2);
+ return -1;
+ }
+ return 0;
+}
+
+/* lock/unlock entire database. It can only be upgradable if you have some
+ * other way of guaranteeing exclusivity (ie. transaction write lock).
+ * We do the locking gradually to avoid being starved by smaller locks. */
+int tdb_allrecord_lock(struct tdb_context *tdb, int ltype,
+ enum tdb_lock_flags flags, bool upgradable)
+{
+ switch (tdb_allrecord_check(tdb, ltype, flags, upgradable)) {
+ case -1:
+ return -1;
+ case 0:
+ return 0;
+ }
+
+ /* We cover two kinds of locks:
+ * 1) Normal chain locks. Taken for almost all operations.
+ * 3) Individual records locks. Taken after normal or free
+ * chain locks.
+ *
+ * It is (1) which cause the starvation problem, so we're only
+ * gradual for that. */
+ if (tdb_chainlock_gradual(tdb, ltype, flags, FREELIST_TOP,
+ tdb->header.hash_size * 4) == -1) {
+ return -1;
+ }
+
+ /* Grab individual record locks. */
+ if (tdb_brlock(tdb, ltype, lock_offset(tdb->header.hash_size), 0,
+ flags) == -1) {
+ tdb_brunlock(tdb, ltype, FREELIST_TOP,
+ tdb->header.hash_size * 4);
+ return -1;
+ }
+
+ tdb->allrecord_lock.count = 1;
+ /* If it's upgradable, it's actually exclusive so we can treat
+ * it as a write lock. */
+ tdb->allrecord_lock.ltype = upgradable ? F_WRLCK : ltype;
+ tdb->allrecord_lock.off = upgradable;
+
+ if (tdb_needs_recovery(tdb)) {
+ bool mark = flags & TDB_LOCK_MARK_ONLY;
+ tdb_allrecord_unlock(tdb, ltype, mark);
+ if (mark) {
+ tdb->ecode = TDB_ERR_LOCK;
+ TDB_LOG((tdb, TDB_DEBUG_ERROR,
+ "tdb_lockall_mark cannot do recovery\n"));
+ return -1;
+ }
+ if (tdb_lock_and_recover(tdb) == -1) {
+ return -1;
+ }
+ return tdb_allrecord_lock(tdb, ltype, flags, upgradable);
+ }
+
+ return 0;
+}
+
+
+
+/* unlock entire db */
+int tdb_allrecord_unlock(struct tdb_context *tdb, int ltype, bool mark_lock)
+{
+ /* There are no locks on read-only dbs */
+ if (tdb->read_only || tdb->traverse_read) {
+ tdb->ecode = TDB_ERR_LOCK;
+ return -1;
+ }
+
+ if (tdb->allrecord_lock.count == 0) {
+ tdb->ecode = TDB_ERR_LOCK;
+ return -1;
+ }
+
+ /* Upgradable locks are marked as write locks. */
+ if (tdb->allrecord_lock.ltype != ltype
+ && (!tdb->allrecord_lock.off || ltype != F_RDLCK)) {
+ tdb->ecode = TDB_ERR_LOCK;
+ return -1;
+ }
+
+ if (tdb->allrecord_lock.count > 1) {
+ tdb->allrecord_lock.count--;
+ return 0;
+ }
+
+ if (!mark_lock && tdb_brunlock(tdb, ltype, FREELIST_TOP, 0)) {
+ TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_unlockall failed (%s)\n", strerror(errno)));
+ return -1;
+ }
+
+ tdb->allrecord_lock.count = 0;
+ tdb->allrecord_lock.ltype = 0;
+
+ return 0;
+}
+
+/* lock entire database with write lock */
+int tdb_lockall(struct tdb_context *tdb)
+{
+ tdb_trace(tdb, "tdb_lockall");
+ return tdb_allrecord_lock(tdb, F_WRLCK, TDB_LOCK_WAIT, false);
+}
+
+/* lock entire database with write lock - mark only */
+int tdb_lockall_mark(struct tdb_context *tdb)
+{
+ tdb_trace(tdb, "tdb_lockall_mark");
+ return tdb_allrecord_lock(tdb, F_WRLCK, TDB_LOCK_MARK_ONLY, false);
+}
+
+/* unlock entire database with write lock - unmark only */
+int tdb_lockall_unmark(struct tdb_context *tdb)
+{
+ tdb_trace(tdb, "tdb_lockall_unmark");
+ return tdb_allrecord_unlock(tdb, F_WRLCK, true);
+}
+
+/* lock entire database with write lock - nonblocking varient */
+int tdb_lockall_nonblock(struct tdb_context *tdb)
+{
+ int ret = tdb_allrecord_lock(tdb, F_WRLCK, TDB_LOCK_NOWAIT, false);
+ tdb_trace_ret(tdb, "tdb_lockall_nonblock", ret);
+ return ret;
+}
+
+/* unlock entire database with write lock */
+int tdb_unlockall(struct tdb_context *tdb)
+{
+ tdb_trace(tdb, "tdb_unlockall");
+ return tdb_allrecord_unlock(tdb, F_WRLCK, false);
+}
+
+/* lock entire database with read lock */
+int tdb_lockall_read(struct tdb_context *tdb)
+{
+ tdb_trace(tdb, "tdb_lockall_read");
+ return tdb_allrecord_lock(tdb, F_RDLCK, TDB_LOCK_WAIT, false);
+}
+
+/* lock entire database with read lock - nonblock varient */
+int tdb_lockall_read_nonblock(struct tdb_context *tdb)
+{
+ int ret = tdb_allrecord_lock(tdb, F_RDLCK, TDB_LOCK_NOWAIT, false);
+ tdb_trace_ret(tdb, "tdb_lockall_read_nonblock", ret);
+ return ret;
+}
+
+/* unlock entire database with read lock */
+int tdb_unlockall_read(struct tdb_context *tdb)
+{
+ tdb_trace(tdb, "tdb_unlockall_read");
+ return tdb_allrecord_unlock(tdb, F_RDLCK, false);
+}
+
+/* lock/unlock one hash chain. This is meant to be used to reduce
+ contention - it cannot guarantee how many records will be locked */
+int tdb_chainlock(struct tdb_context *tdb, TDB_DATA key)
+{
+ int ret = tdb_lock(tdb, BUCKET(tdb->hash_fn(&key)), F_WRLCK);
+ tdb_trace_1rec(tdb, "tdb_chainlock", key);
+ return ret;
+}
+
+/* lock/unlock one hash chain, non-blocking. This is meant to be used
+ to reduce contention - it cannot guarantee how many records will be
+ locked */
+int tdb_chainlock_nonblock(struct tdb_context *tdb, TDB_DATA key)
+{
+ int ret = tdb_lock_nonblock(tdb, BUCKET(tdb->hash_fn(&key)), F_WRLCK);
+ tdb_trace_1rec_ret(tdb, "tdb_chainlock_nonblock", key, ret);
+ return ret;
+}
+
+/* mark a chain as locked without actually locking it. Warning! use with great caution! */
+int tdb_chainlock_mark(struct tdb_context *tdb, TDB_DATA key)
+{
+ int ret = tdb_nest_lock(tdb, lock_offset(BUCKET(tdb->hash_fn(&key))),
+ F_WRLCK, TDB_LOCK_MARK_ONLY);
+ tdb_trace_1rec(tdb, "tdb_chainlock_mark", key);
+ return ret;
+}
+
+/* unmark a chain as locked without actually locking it. Warning! use with great caution! */
+int tdb_chainlock_unmark(struct tdb_context *tdb, TDB_DATA key)
+{
+ tdb_trace_1rec(tdb, "tdb_chainlock_unmark", key);
+ return tdb_nest_unlock(tdb, lock_offset(BUCKET(tdb->hash_fn(&key))),
+ F_WRLCK, true);
+}
+
+int tdb_chainunlock(struct tdb_context *tdb, TDB_DATA key)
+{
+ tdb_trace_1rec(tdb, "tdb_chainunlock", key);
+ return tdb_unlock(tdb, BUCKET(tdb->hash_fn(&key)), F_WRLCK);
+}
+
+int tdb_chainlock_read(struct tdb_context *tdb, TDB_DATA key)
+{
+ int ret;
+ ret = tdb_lock(tdb, BUCKET(tdb->hash_fn(&key)), F_RDLCK);
+ tdb_trace_1rec(tdb, "tdb_chainlock_read", key);
+ return ret;
+}
+
+int tdb_chainunlock_read(struct tdb_context *tdb, TDB_DATA key)
+{
+ tdb_trace_1rec(tdb, "tdb_chainunlock_read", key);
+ return tdb_unlock(tdb, BUCKET(tdb->hash_fn(&key)), F_RDLCK);
+}
+
+
+
+/* record lock stops delete underneath */
+int tdb_lock_record(struct tdb_context *tdb, tdb_off_t off)
+{
+ if (tdb->allrecord_lock.count) {
+ return 0;
+ }
+ return off ? tdb_brlock(tdb, F_RDLCK, off, 1, TDB_LOCK_WAIT) : 0;
+}
+
+/*
+ Write locks override our own fcntl readlocks, so check it here.
+ Note this is meant to be F_SETLK, *not* F_SETLKW, as it's not
+ an error to fail to get the lock here.
+*/
+int tdb_write_lock_record(struct tdb_context *tdb, tdb_off_t off)
+{
+ struct tdb_traverse_lock *i;
+ for (i = &tdb->travlocks; i; i = i->next)
+ if (i->off == off)
+ return -1;
+ if (tdb->allrecord_lock.count) {
+ if (tdb->allrecord_lock.ltype == F_WRLCK) {
+ return 0;
+ }
+ return -1;
+ }
+ return tdb_brlock(tdb, F_WRLCK, off, 1, TDB_LOCK_NOWAIT|TDB_LOCK_PROBE);
+}
+
+int tdb_write_unlock_record(struct tdb_context *tdb, tdb_off_t off)
+{
+ if (tdb->allrecord_lock.count) {
+ return 0;
+ }
+ return tdb_brunlock(tdb, F_WRLCK, off, 1);
+}
+
+/* fcntl locks don't stack: avoid unlocking someone else's */
+int tdb_unlock_record(struct tdb_context *tdb, tdb_off_t off)
+{
+ struct tdb_traverse_lock *i;
+ uint32_t count = 0;
+
+ if (tdb->allrecord_lock.count) {
+ return 0;
+ }
+
+ if (off == 0)
+ return 0;
+ for (i = &tdb->travlocks; i; i = i->next)
+ if (i->off == off)
+ count++;
+ return (count == 1 ? tdb_brunlock(tdb, F_RDLCK, off, 1) : 0);
+}
+
+bool tdb_have_extra_locks(struct tdb_context *tdb)
+{
+ unsigned int extra = tdb->num_lockrecs;
+
+ /* A transaction holds the lock for all records. */
+ if (!tdb->transaction && tdb->allrecord_lock.count) {
+ return true;
+ }
+
+ /* We always hold the active lock if CLEAR_IF_FIRST. */
+ if (find_nestlock(tdb, ACTIVE_LOCK)) {
+ extra--;
+ }
+
+ /* In a transaction, we expect to hold the transaction lock */
+ if (tdb->transaction && find_nestlock(tdb, TRANSACTION_LOCK)) {
+ extra--;
+ }
+
+ return extra;
+}
+
+/* The transaction code uses this to remove all locks. */
+void tdb_release_transaction_locks(struct tdb_context *tdb)
+{
+ unsigned int i, active = 0;
+
+ if (tdb->allrecord_lock.count != 0) {
+ tdb_brunlock(tdb, tdb->allrecord_lock.ltype, FREELIST_TOP, 0);
+ tdb->allrecord_lock.count = 0;
+ }
+
+ for (i=0;i<tdb->num_lockrecs;i++) {
+ struct tdb_lock_type *lck = &tdb->lockrecs[i];
+
+ /* Don't release the active lock! Copy it to first entry. */
+ if (lck->off == ACTIVE_LOCK) {
+ tdb->lockrecs[active++] = *lck;
+ } else {
+ tdb_brunlock(tdb, lck->ltype, lck->off, 1);
+ }
+ }
+ tdb->num_lockrecs = active;
+ if (tdb->num_lockrecs == 0) {
+ SAFE_FREE(tdb->lockrecs);
+ }
+}
+
+int tdb_transaction_write_lock_mark(struct tdb_context *tdb)
+{
+ return tdb_transaction_lock(tdb, F_WRLCK, TDB_LOCK_MARK_ONLY);
+}
+
+int tdb_transaction_write_lock(struct tdb_context *tdb)
+{
+ return tdb_transaction_lock(tdb, F_WRLCK, 0);
+}
+
+int tdb_transaction_write_unlock(struct tdb_context *tdb)
+{
+ return tdb_transaction_unlock(tdb, F_WRLCK);
+}
+
+int tdb_transaction_write_lock_unmark(struct tdb_context *tdb)
+{
+ return tdb_nest_unlock(tdb, TRANSACTION_LOCK, F_WRLCK, true);
+}
git.samba.org / obnox / samba / samba-obnox.git / blobdiff