Use single copy of tdb in both samba3 and samba4.

1 files changed, 553 insertions, 0 deletions

diff --git a/tdb/common/lock.c b/tdb/common/lock.c
new file mode 100644
index 0000000000..f156c0fa7b
--- /dev/null
+++ b/tdb/common/lock.c
@@ -0,0 +1,553 @@
+ /* 
+   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_MARK_LOCK 0x80000000
+
+void tdb_setalarm_sigptr(struct tdb_context *tdb, volatile sig_atomic_t *ptr)
+{
+	tdb->interrupt_sig_ptr = ptr;
+}
+
+/* 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, tdb_off_t offset, 
+	       int rw_type, int lck_type, int probe, size_t len)
+{
+	struct flock fl;
+	int ret;
+
+	if (tdb->flags & TDB_NOLOCK) {
+		return 0;
+	}
+
+	if ((rw_type == F_WRLCK) && (tdb->read_only || tdb->traverse_read)) {
+		tdb->ecode = TDB_ERR_RDONLY;
+		return -1;
+	}
+
+	fl.l_type = rw_type;
+	fl.l_whence = SEEK_SET;
+	fl.l_start = offset;
+	fl.l_len = len;
+	fl.l_pid = 0;
+
+	do {
+		ret = fcntl(tdb->fd,lck_type,&fl);
+
+		/* 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) {
+		/* Generic lock error. errno set by fcntl.
+		 * EAGAIN is an expected return from non-blocking
+		 * locks. */
+		if (!probe && lck_type != F_SETLK) {
+			/* Ensure error code is set for log fun to examine. */
+			tdb->ecode = TDB_ERR_LOCK;
+			TDB_LOG((tdb, TDB_DEBUG_TRACE,"tdb_brlock failed (fd=%d) at offset %d rw_type=%d lck_type=%d len=%d\n", 
+				 tdb->fd, offset, rw_type, lck_type, (int)len));
+		}
+		return TDB_ERRCODE(TDB_ERR_LOCK, -1);
+	}
+	return 0;
+}
+
+
+/*
+  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_brlock_upgrade(struct tdb_context *tdb, tdb_off_t offset, size_t len)
+{
+	int count = 1000;
+	while (count--) {
+		struct timeval tv;
+		if (tdb_brlock(tdb, offset, F_WRLCK, F_SETLKW, 1, len) == 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_brlock_upgrade failed at offset %d\n", offset));
+	return -1;
+}
+
+
+/* lock a list in the database. list -1 is the alloc list */
+static int _tdb_lock(struct tdb_context *tdb, int list, int ltype, int op)
+{
+	struct tdb_lock_type *new_lck;
+	int i;
+	bool mark_lock = ((ltype & TDB_MARK_LOCK) == TDB_MARK_LOCK);
+
+	ltype &= ~TDB_MARK_LOCK;
+
+	/* a global lock allows us to avoid per chain locks */
+	if (tdb->global_lock.count && 
+	    (ltype == tdb->global_lock.ltype || ltype == F_RDLCK)) {
+		return 0;
+	}
+
+	if (tdb->global_lock.count) {
+		return TDB_ERRCODE(TDB_ERR_LOCK, -1);
+	}
+
+	if (list < -1 || list >= (int)tdb->header.hash_size) {
+		TDB_LOG((tdb, TDB_DEBUG_ERROR,"tdb_lock: invalid list %d for ltype=%d\n", 
+			   list, ltype));
+		return -1;
+	}
+	if (tdb->flags & TDB_NOLOCK)
+		return 0;
+
+	for (i=0; i<tdb->num_lockrecs; i++) {
+		if (tdb->lockrecs[i].list == list) {
+			if (tdb->lockrecs[i].count == 0) {
+				/*
+				 * Can't happen, see tdb_unlock(). It should
+				 * be an assert.
+				 */
+				TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_lock: "
+					 "lck->count == 0 for list %d", list));
+			}
+			/*
+			 * Just increment the in-memory struct, posix locks
+			 * don't stack.
+			 */
+			tdb->lockrecs[i].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 (!mark_lock &&
+	    tdb->methods->tdb_brlock(tdb,FREELIST_TOP+4*list, ltype, op,
+				     0, 1)) {
+		return -1;
+	}
+
+	tdb->num_locks++;
+
+	tdb->lockrecs[tdb->num_lockrecs].list = list;
+	tdb->lockrecs[tdb->num_lockrecs].count = 1;
+	tdb->lockrecs[tdb->num_lockrecs].ltype = ltype;
+	tdb->num_lockrecs += 1;
+
+	return 0;
+}
+
+/* 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(tdb, list, ltype, F_SETLKW);
+	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(tdb, list, ltype, F_SETLK);
+}
+
+
+/* unlock the database: returns void because it's too late for errors. */
+	/* changed to return int it may be interesting to know there
+	   has been an error  --simo */
+int tdb_unlock(struct tdb_context *tdb, int list, int ltype)
+{
+	int ret = -1;
+	int i;
+	struct tdb_lock_type *lck = NULL;
+	bool mark_lock = ((ltype & TDB_MARK_LOCK) == TDB_MARK_LOCK);
+
+	ltype &= ~TDB_MARK_LOCK;
+
+	/* a global lock allows us to avoid per chain locks */
+	if (tdb->global_lock.count && 
+	    (ltype == tdb->global_lock.ltype || ltype == F_RDLCK)) {
+		return 0;
+	}
+
+	if (tdb->global_lock.count) {
+		return TDB_ERRCODE(TDB_ERR_LOCK, -1);
+	}
+
+	if (tdb->flags & TDB_NOLOCK)
+		return 0;
+
+	/* Sanity checks */
+	if (list < -1 || list >= (int)tdb->header.hash_size) {
+		TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_unlock: list %d invalid (%d)\n", list, tdb->header.hash_size));
+		return ret;
+	}
+
+	for (i=0; i<tdb->num_lockrecs; i++) {
+		if (tdb->lockrecs[i].list == list) {
+			lck = &tdb->lockrecs[i];
+			break;
+		}
+	}
+
+	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->methods->tdb_brlock(tdb, FREELIST_TOP+4*list, F_UNLCK,
+					       F_SETLKW, 0, 1);
+	}
+	tdb->num_locks--;
+
+	/*
+	 * Shrink the array by overwriting the element just unlocked with the
+	 * last array element.
+	 */
+
+	if (tdb->num_lockrecs > 1) {
+		*lck = tdb->lockrecs[tdb->num_lockrecs-1];
+	}
+	tdb->num_lockrecs -= 1;
+
+	/*
+	 * 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;
+}
+
+/*
+  get the transaction lock
+ */
+int tdb_transaction_lock(struct tdb_context *tdb, int ltype)
+{
+	if (tdb->have_transaction_lock || tdb->global_lock.count) {
+		return 0;
+	}
+	if (tdb->methods->tdb_brlock(tdb, TRANSACTION_LOCK, ltype, 
+				     F_SETLKW, 0, 1) == -1) {
+		TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_lock: failed to get transaction lock\n"));
+		tdb->ecode = TDB_ERR_LOCK;
+		return -1;
+	}
+	tdb->have_transaction_lock = 1;
+	return 0;
+}
+
+/*
+  release the transaction lock
+ */
+int tdb_transaction_unlock(struct tdb_context *tdb)
+{
+	int ret;
+	if (!tdb->have_transaction_lock) {
+		return 0;
+	}
+	ret = tdb->methods->tdb_brlock(tdb, TRANSACTION_LOCK, F_UNLCK, F_SETLKW, 0, 1);
+	if (ret == 0) {
+		tdb->have_transaction_lock = 0;
+	}
+	return ret;
+}
+
+
+
+
+/* lock/unlock entire database */
+static int _tdb_lockall(struct tdb_context *tdb, int ltype, int op)
+{
+	bool mark_lock = ((ltype & TDB_MARK_LOCK) == TDB_MARK_LOCK);
+
+	ltype &= ~TDB_MARK_LOCK;
+
+	/* There are no locks on read-only dbs */
+	if (tdb->read_only || tdb->traverse_read)
+		return TDB_ERRCODE(TDB_ERR_LOCK, -1);
+
+	if (tdb->global_lock.count && tdb->global_lock.ltype == ltype) {
+		tdb->global_lock.count++;
+		return 0;
+	}
+
+	if (tdb->global_lock.count) {
+		/* a global lock of a different type exists */
+		return TDB_ERRCODE(TDB_ERR_LOCK, -1);
+	}
+	
+	if (tdb->num_locks != 0) {
+		/* can't combine global and chain locks */
+		return TDB_ERRCODE(TDB_ERR_LOCK, -1);
+	}
+
+	if (!mark_lock &&
+	    tdb->methods->tdb_brlock(tdb, FREELIST_TOP, ltype, op,
+				     0, 4*tdb->header.hash_size)) {
+		if (op == F_SETLKW) {
+			TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_lockall failed (%s)\n", strerror(errno)));
+		}
+		return -1;
+	}
+
+	tdb->global_lock.count = 1;
+	tdb->global_lock.ltype = ltype;
+
+	return 0;
+}
+
+
+
+/* unlock entire db */
+static int _tdb_unlockall(struct tdb_context *tdb, int ltype)
+{
+	bool mark_lock = ((ltype & TDB_MARK_LOCK) == TDB_MARK_LOCK);
+
+	ltype &= ~TDB_MARK_LOCK;
+
+	/* There are no locks on read-only dbs */
+	if (tdb->read_only || tdb->traverse_read) {
+		return TDB_ERRCODE(TDB_ERR_LOCK, -1);
+	}
+
+	if (tdb->global_lock.ltype != ltype || tdb->global_lock.count == 0) {
+		return TDB_ERRCODE(TDB_ERR_LOCK, -1);
+	}
+
+	if (tdb->global_lock.count > 1) {
+		tdb->global_lock.count--;
+		return 0;
+	}
+
+	if (!mark_lock &&
+	    tdb->methods->tdb_brlock(tdb, FREELIST_TOP, F_UNLCK, F_SETLKW, 
+				     0, 4*tdb->header.hash_size)) {
+		TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_unlockall failed (%s)\n", strerror(errno)));
+		return -1;
+	}
+
+	tdb->global_lock.count = 0;
+	tdb->global_lock.ltype = 0;
+
+	return 0;
+}
+
+/* lock entire database with write lock */
+int tdb_lockall(struct tdb_context *tdb)
+{
+	return _tdb_lockall(tdb, F_WRLCK, F_SETLKW);
+}
+
+/* lock entire database with write lock - mark only */
+int tdb_lockall_mark(struct tdb_context *tdb)
+{
+	return _tdb_lockall(tdb, F_WRLCK | TDB_MARK_LOCK, F_SETLKW);
+}
+
+/* unlock entire database with write lock - unmark only */
+int tdb_lockall_unmark(struct tdb_context *tdb)
+{
+	return _tdb_unlockall(tdb, F_WRLCK | TDB_MARK_LOCK);
+}
+
+/* lock entire database with write lock - nonblocking varient */
+int tdb_lockall_nonblock(struct tdb_context *tdb)
+{
+	return _tdb_lockall(tdb, F_WRLCK, F_SETLK);
+}
+
+/* unlock entire database with write lock */
+int tdb_unlockall(struct tdb_context *tdb)
+{
+	return _tdb_unlockall(tdb, F_WRLCK);
+}
+
+/* lock entire database with read lock */
+int tdb_lockall_read(struct tdb_context *tdb)
+{
+	return _tdb_lockall(tdb, F_RDLCK, F_SETLKW);
+}
+
+/* lock entire database with read lock - nonblock varient */
+int tdb_lockall_read_nonblock(struct tdb_context *tdb)
+{
+	return _tdb_lockall(tdb, F_RDLCK, F_SETLK);
+}
+
+/* unlock entire database with read lock */
+int tdb_unlockall_read(struct tdb_context *tdb)
+{
+	return _tdb_unlockall(tdb, F_RDLCK);
+}
+
+/* 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)
+{
+	return tdb_lock(tdb, BUCKET(tdb->hash_fn(&key)), F_WRLCK);
+}
+
+/* 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)
+{
+	return tdb_lock_nonblock(tdb, BUCKET(tdb->hash_fn(&key)), F_WRLCK);
+}
+
+/* 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)
+{
+	return tdb_lock(tdb, BUCKET(tdb->hash_fn(&key)), F_WRLCK | TDB_MARK_LOCK);
+}
+
+/* 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)
+{
+	return tdb_unlock(tdb, BUCKET(tdb->hash_fn(&key)), F_WRLCK | TDB_MARK_LOCK);
+}
+
+int tdb_chainunlock(struct tdb_context *tdb, TDB_DATA key)
+{
+	return tdb_unlock(tdb, BUCKET(tdb->hash_fn(&key)), F_WRLCK);
+}
+
+int tdb_chainlock_read(struct tdb_context *tdb, TDB_DATA key)
+{
+	return tdb_lock(tdb, BUCKET(tdb->hash_fn(&key)), F_RDLCK);
+}
+
+int tdb_chainunlock_read(struct tdb_context *tdb, TDB_DATA 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->global_lock.count) {
+		return 0;
+	}
+	return off ? tdb->methods->tdb_brlock(tdb, off, F_RDLCK, F_SETLKW, 0, 1) : 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;
+	return tdb->methods->tdb_brlock(tdb, off, F_WRLCK, F_SETLK, 1, 1);
+}
+
+/*
+  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_unlock_record(struct tdb_context *tdb, tdb_off_t off)
+{
+	return tdb->methods->tdb_brlock(tdb, off, F_UNLCK, F_SETLK, 0, 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->global_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->methods->tdb_brlock(tdb, off, F_UNLCK, F_SETLKW, 0, 1) : 0);
+}