+ /*
+ 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 ntdb
+ ** 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 "private.h"
+#include <ccan/build_assert/build_assert.h>
+
+/* If we were threaded, we could wait for unlock, but we're not, so fail. */
+enum NTDB_ERROR owner_conflict(struct ntdb_context *ntdb, const char *call)
+{
+ return ntdb_logerr(ntdb, NTDB_ERR_LOCK, NTDB_LOG_USE_ERROR,
+ "%s: lock owned by another ntdb in this process.",
+ call);
+}
+
+/* If we fork, we no longer really own locks. */
+bool check_lock_pid(struct ntdb_context *ntdb, const char *call, bool log)
+{
+ /* No locks? No problem! */
+ if (ntdb->file->allrecord_lock.count == 0
+ && ntdb->file->num_lockrecs == 0) {
+ return true;
+ }
+
+ /* No fork? No problem! */
+ if (ntdb->file->locker == getpid()) {
+ return true;
+ }
+
+ if (log) {
+ ntdb_logerr(ntdb, NTDB_ERR_LOCK, NTDB_LOG_USE_ERROR,
+ "%s: fork() detected after lock acquisition!"
+ " (%u vs %u)", call,
+ (unsigned int)ntdb->file->locker,
+ (unsigned int)getpid());
+ }
+ return false;
+}
+
+int ntdb_fcntl_lock(int fd, int rw, off_t off, off_t len, bool waitflag,
+ void *unused)
+{
+ struct flock fl;
+ int ret;
+
+ do {
+ fl.l_type = rw;
+ fl.l_whence = SEEK_SET;
+ fl.l_start = off;
+ fl.l_len = len;
+
+ if (waitflag)
+ ret = fcntl(fd, F_SETLKW, &fl);
+ else
+ ret = fcntl(fd, F_SETLK, &fl);
+ } while (ret != 0 && errno == EINTR);
+ return ret;
+}
+
+int ntdb_fcntl_unlock(int fd, int rw, off_t off, off_t len, void *unused)
+{
+ struct flock fl;
+ int ret;
+
+ do {
+ fl.l_type = F_UNLCK;
+ fl.l_whence = SEEK_SET;
+ fl.l_start = off;
+ fl.l_len = len;
+
+ ret = fcntl(fd, F_SETLKW, &fl);
+ } while (ret != 0 && errno == EINTR);
+ return ret;
+}
+
+static int lock(struct ntdb_context *ntdb,
+ int rw, off_t off, off_t len, bool waitflag)
+{
+ int ret;
+ if (ntdb->file->allrecord_lock.count == 0
+ && ntdb->file->num_lockrecs == 0) {
+ ntdb->file->locker = getpid();
+ }
+
+ ntdb->stats.lock_lowlevel++;
+ ret = ntdb->lock_fn(ntdb->file->fd, rw, off, len, waitflag,
+ ntdb->lock_data);
+ if (!waitflag) {
+ ntdb->stats.lock_nonblock++;
+ if (ret != 0)
+ ntdb->stats.lock_nonblock_fail++;
+ }
+ return ret;
+}
+
+static int unlock(struct ntdb_context *ntdb, int rw, off_t off, off_t len)
+{
+#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!",
+ (int)off, (int)len);
+ abort();
+ }
+
+ fclose(locks);
+#endif
+
+ return ntdb->unlock_fn(ntdb->file->fd, rw, off, len, ntdb->lock_data);
+}
+
+/* a byte range locking function - return 0 on success
+ this functions locks len bytes at the specified offset.
+
+ note that a len of zero means lock to end of file
+*/
+static enum NTDB_ERROR ntdb_brlock(struct ntdb_context *ntdb,
+ int rw_type, ntdb_off_t offset, ntdb_off_t len,
+ enum ntdb_lock_flags flags)
+{
+ int ret;
+
+ if (rw_type == F_WRLCK && (ntdb->flags & NTDB_RDONLY)) {
+ return ntdb_logerr(ntdb, NTDB_ERR_RDONLY, NTDB_LOG_USE_ERROR,
+ "Write lock attempted on read-only database");
+ }
+
+ if (ntdb->flags & NTDB_NOLOCK) {
+ return NTDB_SUCCESS;
+ }
+
+ /* A 32 bit system cannot open a 64-bit file, but it could have
+ * expanded since then: check here. */
+ if ((size_t)(offset + len) != offset + len) {
+ return ntdb_logerr(ntdb, NTDB_ERR_IO, NTDB_LOG_ERROR,
+ "ntdb_brlock: lock on giant offset %llu",
+ (long long)(offset + len));
+ }
+
+ ret = lock(ntdb, rw_type, offset, len, flags & NTDB_LOCK_WAIT);
+ if (ret != 0) {
+ /* Generic lock error. errno set by fcntl.
+ * EAGAIN is an expected return from non-blocking
+ * locks. */
+ if (!(flags & NTDB_LOCK_PROBE)
+ && (errno != EAGAIN && errno != EINTR)) {
+ ntdb_logerr(ntdb, NTDB_ERR_LOCK, NTDB_LOG_ERROR,
+ "ntdb_brlock failed (fd=%d) at"
+ " offset %zu rw_type=%d flags=%d len=%zu:"
+ " %s",
+ ntdb->file->fd, (size_t)offset, rw_type,
+ flags, (size_t)len, strerror(errno));
+ }
+ return NTDB_ERR_LOCK;
+ }
+ return NTDB_SUCCESS;
+}
+
+static enum NTDB_ERROR ntdb_brunlock(struct ntdb_context *ntdb,
+ int rw_type, ntdb_off_t offset, size_t len)
+{
+ if (ntdb->flags & NTDB_NOLOCK) {
+ return NTDB_SUCCESS;
+ }
+
+ if (!check_lock_pid(ntdb, "ntdb_brunlock", false))
+ return NTDB_ERR_LOCK;
+
+ if (unlock(ntdb, rw_type, offset, len) == -1) {
+ return ntdb_logerr(ntdb, NTDB_ERR_LOCK, NTDB_LOG_ERROR,
+ "ntdb_brunlock failed (fd=%d) at offset %zu"
+ " rw_type=%d len=%zu: %s",
+ ntdb->file->fd, (size_t)offset, rw_type,
+ (size_t)len, strerror(errno));
+ }
+ return NTDB_SUCCESS;
+}
+
+/*
+ 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.
+*/
+enum NTDB_ERROR ntdb_allrecord_upgrade(struct ntdb_context *ntdb, off_t start)
+{
+ int count = 1000;
+
+ if (!check_lock_pid(ntdb, "ntdb_transaction_prepare_commit", true))
+ return NTDB_ERR_LOCK;
+
+ if (ntdb->file->allrecord_lock.count != 1) {
+ return ntdb_logerr(ntdb, NTDB_ERR_LOCK, NTDB_LOG_ERROR,
+ "ntdb_allrecord_upgrade failed:"
+ " count %u too high",
+ ntdb->file->allrecord_lock.count);
+ }
+
+ if (ntdb->file->allrecord_lock.off != 1) {
+ return ntdb_logerr(ntdb, NTDB_ERR_LOCK, NTDB_LOG_ERROR,
+ "ntdb_allrecord_upgrade failed:"
+ " already upgraded?");
+ }
+
+ if (ntdb->file->allrecord_lock.owner != ntdb) {
+ return owner_conflict(ntdb, "ntdb_allrecord_upgrade");
+ }
+
+ while (count--) {
+ struct timeval tv;
+ if (ntdb_brlock(ntdb, F_WRLCK, start, 0,
+ NTDB_LOCK_WAIT|NTDB_LOCK_PROBE) == NTDB_SUCCESS) {
+ ntdb->file->allrecord_lock.ltype = F_WRLCK;
+ ntdb->file->allrecord_lock.off = 0;
+ return NTDB_SUCCESS;
+ }
+ 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);
+ }
+
+ if (errno != EAGAIN && errno != EINTR)
+ ntdb_logerr(ntdb, NTDB_ERR_LOCK, NTDB_LOG_ERROR,
+ "ntdb_allrecord_upgrade failed");
+ return NTDB_ERR_LOCK;
+}
+
+static struct ntdb_lock *find_nestlock(struct ntdb_context *ntdb, ntdb_off_t offset,
+ const struct ntdb_context *owner)
+{
+ unsigned int i;
+
+ for (i=0; i<ntdb->file->num_lockrecs; i++) {
+ if (ntdb->file->lockrecs[i].off == offset) {
+ if (owner && ntdb->file->lockrecs[i].owner != owner)
+ return NULL;
+ return &ntdb->file->lockrecs[i];
+ }
+ }
+ return NULL;
+}
+
+enum NTDB_ERROR ntdb_lock_and_recover(struct ntdb_context *ntdb)
+{
+ enum NTDB_ERROR ecode;
+
+ if (!check_lock_pid(ntdb, "ntdb_transaction_prepare_commit", true))
+ return NTDB_ERR_LOCK;
+
+ ecode = ntdb_allrecord_lock(ntdb, F_WRLCK, NTDB_LOCK_WAIT|NTDB_LOCK_NOCHECK,
+ false);
+ if (ecode != NTDB_SUCCESS) {
+ return ecode;
+ }
+
+ ecode = ntdb_lock_open(ntdb, F_WRLCK, NTDB_LOCK_WAIT|NTDB_LOCK_NOCHECK);
+ if (ecode != NTDB_SUCCESS) {
+ ntdb_allrecord_unlock(ntdb, F_WRLCK);
+ return ecode;
+ }
+ ecode = ntdb_transaction_recover(ntdb);
+ ntdb_unlock_open(ntdb, F_WRLCK);
+ ntdb_allrecord_unlock(ntdb, F_WRLCK);
+
+ return ecode;
+}
+
+/* lock an offset in the database. */
+static enum NTDB_ERROR ntdb_nest_lock(struct ntdb_context *ntdb,
+ ntdb_off_t offset, int ltype,
+ enum ntdb_lock_flags flags)
+{
+ struct ntdb_lock *new_lck;
+ enum NTDB_ERROR ecode;
+
+ assert(offset <= (NTDB_HASH_LOCK_START + (1 << ntdb->hash_bits)
+ + ntdb->file->map_size / 8));
+
+ if (ntdb->flags & NTDB_NOLOCK)
+ return NTDB_SUCCESS;
+
+ if (!check_lock_pid(ntdb, "ntdb_nest_lock", true)) {
+ return NTDB_ERR_LOCK;
+ }
+
+ ntdb->stats.locks++;
+
+ new_lck = find_nestlock(ntdb, offset, NULL);
+ if (new_lck) {
+ if (new_lck->owner != ntdb) {
+ return owner_conflict(ntdb, "ntdb_nest_lock");
+ }
+
+ if (new_lck->ltype == F_RDLCK && ltype == F_WRLCK) {
+ return ntdb_logerr(ntdb, NTDB_ERR_LOCK, NTDB_LOG_ERROR,
+ "ntdb_nest_lock:"
+ " offset %zu has read lock",
+ (size_t)offset);
+ }
+ /* Just increment the struct, posix locks don't stack. */
+ new_lck->count++;
+ return NTDB_SUCCESS;
+ }
+
+#if 0
+ if (ntdb->file->num_lockrecs
+ && offset >= NTDB_HASH_LOCK_START
+ && offset < NTDB_HASH_LOCK_START + NTDB_HASH_LOCK_RANGE) {
+ return ntdb_logerr(ntdb, NTDB_ERR_LOCK, NTDB_LOG_ERROR,
+ "ntdb_nest_lock: already have a hash lock?");
+ }
+#endif
+ if (ntdb->file->lockrecs == NULL) {
+ new_lck = ntdb->alloc_fn(ntdb->file, sizeof(*ntdb->file->lockrecs),
+ ntdb->alloc_data);
+ } else {
+ new_lck = (struct ntdb_lock *)ntdb->expand_fn(
+ ntdb->file->lockrecs,
+ sizeof(*ntdb->file->lockrecs)
+ * (ntdb->file->num_lockrecs+1),
+ ntdb->alloc_data);
+ }
+ if (new_lck == NULL) {
+ return ntdb_logerr(ntdb, NTDB_ERR_OOM, NTDB_LOG_ERROR,
+ "ntdb_nest_lock:"
+ " unable to allocate %zu lock struct",
+ ntdb->file->num_lockrecs + 1);
+ }
+ ntdb->file->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 */
+ ecode = ntdb_brlock(ntdb, ltype, offset, 1, flags);
+ if (ecode != NTDB_SUCCESS) {
+ return ecode;
+ }
+
+ /* First time we grab a lock, perhaps someone died in commit? */
+ if (!(flags & NTDB_LOCK_NOCHECK)
+ && ntdb->file->num_lockrecs == 0) {
+ ntdb_bool_err berr = ntdb_needs_recovery(ntdb);
+ if (berr != false) {
+ ntdb_brunlock(ntdb, ltype, offset, 1);
+
+ if (berr < 0)
+ return NTDB_OFF_TO_ERR(berr);
+ ecode = ntdb_lock_and_recover(ntdb);
+ if (ecode == NTDB_SUCCESS) {
+ ecode = ntdb_brlock(ntdb, ltype, offset, 1,
+ flags);
+ }
+ if (ecode != NTDB_SUCCESS) {
+ return ecode;
+ }
+ }
+ }
+
+ ntdb->file->lockrecs[ntdb->file->num_lockrecs].owner = ntdb;
+ ntdb->file->lockrecs[ntdb->file->num_lockrecs].off = offset;
+ ntdb->file->lockrecs[ntdb->file->num_lockrecs].count = 1;
+ ntdb->file->lockrecs[ntdb->file->num_lockrecs].ltype = ltype;
+ ntdb->file->num_lockrecs++;
+
+ return NTDB_SUCCESS;
+}
+
+static enum NTDB_ERROR ntdb_nest_unlock(struct ntdb_context *ntdb,
+ ntdb_off_t off, int ltype)
+{
+ struct ntdb_lock *lck;
+ enum NTDB_ERROR ecode;
+
+ if (ntdb->flags & NTDB_NOLOCK)
+ return NTDB_SUCCESS;
+
+ lck = find_nestlock(ntdb, off, ntdb);
+ if ((lck == NULL) || (lck->count == 0)) {
+ return ntdb_logerr(ntdb, NTDB_ERR_LOCK, NTDB_LOG_ERROR,
+ "ntdb_nest_unlock: no lock for %zu",
+ (size_t)off);
+ }
+
+ if (lck->count > 1) {
+ lck->count--;
+ return NTDB_SUCCESS;
+ }
+
+ /*
+ * 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.
+ */
+ ecode = ntdb_brunlock(ntdb, ltype, off, 1);
+
+ /*
+ * Shrink the array by overwriting the element just unlocked with the
+ * last array element.
+ */
+ *lck = ntdb->file->lockrecs[--ntdb->file->num_lockrecs];
+
+ return ecode;
+}
+
+/*
+ get the transaction lock
+ */
+enum NTDB_ERROR ntdb_transaction_lock(struct ntdb_context *ntdb, int ltype)
+{
+ return ntdb_nest_lock(ntdb, NTDB_TRANSACTION_LOCK, ltype, NTDB_LOCK_WAIT);
+}
+
+/*
+ release the transaction lock
+ */
+void ntdb_transaction_unlock(struct ntdb_context *ntdb, int ltype)
+{
+ ntdb_nest_unlock(ntdb, NTDB_TRANSACTION_LOCK, ltype);
+}
+
+/* We only need to lock individual bytes, but Linux merges consecutive locks
+ * so we lock in contiguous ranges. */
+static enum NTDB_ERROR ntdb_lock_gradual(struct ntdb_context *ntdb,
+ int ltype, enum ntdb_lock_flags flags,
+ ntdb_off_t off, ntdb_off_t len)
+{
+ enum NTDB_ERROR ecode;
+ enum ntdb_lock_flags nb_flags = (flags & ~NTDB_LOCK_WAIT);
+
+ if (len <= 1) {
+ /* 0 would mean to end-of-file... */
+ assert(len != 0);
+ /* Single hash. Just do blocking lock. */
+ return ntdb_brlock(ntdb, ltype, off, len, flags);
+ }
+
+ /* First we try non-blocking. */
+ ecode = ntdb_brlock(ntdb, ltype, off, len, nb_flags);
+ if (ecode != NTDB_ERR_LOCK) {
+ return ecode;
+ }
+
+ /* Try locking first half, then second. */
+ ecode = ntdb_lock_gradual(ntdb, ltype, flags, off, len / 2);
+ if (ecode != NTDB_SUCCESS)
+ return ecode;
+
+ ecode = ntdb_lock_gradual(ntdb, ltype, flags,
+ off + len / 2, len - len / 2);
+ if (ecode != NTDB_SUCCESS) {
+ ntdb_brunlock(ntdb, ltype, off, len / 2);
+ }
+ return ecode;
+}
+
+/* lock/unlock entire database. It can only be upgradable if you have some
+ * other way of guaranteeing exclusivity (ie. transaction write lock). */
+enum NTDB_ERROR ntdb_allrecord_lock(struct ntdb_context *ntdb, int ltype,
+ enum ntdb_lock_flags flags, bool upgradable)
+{
+ enum NTDB_ERROR ecode;
+ ntdb_bool_err berr;
+
+ if (ntdb->flags & NTDB_NOLOCK) {
+ return NTDB_SUCCESS;
+ }
+
+ if (!check_lock_pid(ntdb, "ntdb_allrecord_lock", true)) {
+ return NTDB_ERR_LOCK;
+ }
+
+ if (ntdb->file->allrecord_lock.count) {
+ if (ntdb->file->allrecord_lock.owner != ntdb) {
+ return owner_conflict(ntdb, "ntdb_allrecord_lock");
+ }
+
+ if (ltype == F_RDLCK
+ || ntdb->file->allrecord_lock.ltype == F_WRLCK) {
+ ntdb->file->allrecord_lock.count++;
+ return NTDB_SUCCESS;
+ }
+
+ /* a global lock of a different type exists */
+ return ntdb_logerr(ntdb, NTDB_ERR_LOCK, NTDB_LOG_USE_ERROR,
+ "ntdb_allrecord_lock: already have %s lock",
+ ntdb->file->allrecord_lock.ltype == F_RDLCK
+ ? "read" : "write");
+ }
+
+ if (ntdb_has_hash_locks(ntdb)) {
+ /* can't combine global and chain locks */
+ return ntdb_logerr(ntdb, NTDB_ERR_LOCK, NTDB_LOG_USE_ERROR,
+ "ntdb_allrecord_lock:"
+ " already have chain lock");
+ }
+
+ if (upgradable && ltype != F_RDLCK) {
+ /* ntdb error: you can't upgrade a write lock! */
+ return ntdb_logerr(ntdb, NTDB_ERR_LOCK, NTDB_LOG_ERROR,
+ "ntdb_allrecord_lock:"
+ " can't upgrade a write lock");
+ }
+
+ ntdb->stats.locks++;
+again:
+ /* Lock hashes, gradually. */
+ ecode = ntdb_lock_gradual(ntdb, ltype, flags, NTDB_HASH_LOCK_START,
+ 1 << ntdb->hash_bits);
+ if (ecode != NTDB_SUCCESS)
+ return ecode;
+
+ /* Lock free tables: there to end of file. */
+ ecode = ntdb_brlock(ntdb, ltype,
+ NTDB_HASH_LOCK_START + (1 << ntdb->hash_bits),
+ 0, flags);
+ if (ecode != NTDB_SUCCESS) {
+ ntdb_brunlock(ntdb, ltype, NTDB_HASH_LOCK_START,
+ 1 << ntdb->hash_bits);
+ return ecode;
+ }
+
+ ntdb->file->allrecord_lock.owner = ntdb;
+ ntdb->file->allrecord_lock.count = 1;
+ /* If it's upgradable, it's actually exclusive so we can treat
+ * it as a write lock. */
+ ntdb->file->allrecord_lock.ltype = upgradable ? F_WRLCK : ltype;
+ ntdb->file->allrecord_lock.off = upgradable;
+
+ /* Now check for needing recovery. */
+ if (flags & NTDB_LOCK_NOCHECK)
+ return NTDB_SUCCESS;
+
+ berr = ntdb_needs_recovery(ntdb);
+ if (likely(berr == false))
+ return NTDB_SUCCESS;
+
+ ntdb_allrecord_unlock(ntdb, ltype);
+ if (berr < 0)
+ return NTDB_OFF_TO_ERR(berr);
+ ecode = ntdb_lock_and_recover(ntdb);
+ if (ecode != NTDB_SUCCESS) {
+ return ecode;
+ }
+ goto again;
+}
+
+enum NTDB_ERROR ntdb_lock_open(struct ntdb_context *ntdb,
+ int ltype, enum ntdb_lock_flags flags)
+{
+ return ntdb_nest_lock(ntdb, NTDB_OPEN_LOCK, ltype, flags);
+}
+
+void ntdb_unlock_open(struct ntdb_context *ntdb, int ltype)
+{
+ ntdb_nest_unlock(ntdb, NTDB_OPEN_LOCK, ltype);
+}
+
+bool ntdb_has_open_lock(struct ntdb_context *ntdb)
+{
+ return !(ntdb->flags & NTDB_NOLOCK)
+ && find_nestlock(ntdb, NTDB_OPEN_LOCK, ntdb) != NULL;
+}
+
+enum NTDB_ERROR ntdb_lock_expand(struct ntdb_context *ntdb, int ltype)
+{
+ /* Lock doesn't protect data, so don't check (we recurse if we do!) */
+ return ntdb_nest_lock(ntdb, NTDB_EXPANSION_LOCK, ltype,
+ NTDB_LOCK_WAIT | NTDB_LOCK_NOCHECK);
+}
+
+void ntdb_unlock_expand(struct ntdb_context *ntdb, int ltype)
+{
+ ntdb_nest_unlock(ntdb, NTDB_EXPANSION_LOCK, ltype);
+}
+
+/* unlock entire db */
+void ntdb_allrecord_unlock(struct ntdb_context *ntdb, int ltype)
+{
+ if (ntdb->flags & NTDB_NOLOCK)
+ return;
+
+ if (ntdb->file->allrecord_lock.count == 0) {
+ ntdb_logerr(ntdb, NTDB_ERR_LOCK, NTDB_LOG_USE_ERROR,
+ "ntdb_allrecord_unlock: not locked!");
+ return;
+ }
+
+ if (ntdb->file->allrecord_lock.owner != ntdb) {
+ ntdb_logerr(ntdb, NTDB_ERR_LOCK, NTDB_LOG_USE_ERROR,
+ "ntdb_allrecord_unlock: not locked by us!");
+ return;
+ }
+
+ /* Upgradable locks are marked as write locks. */
+ if (ntdb->file->allrecord_lock.ltype != ltype
+ && (!ntdb->file->allrecord_lock.off || ltype != F_RDLCK)) {
+ ntdb_logerr(ntdb, NTDB_ERR_LOCK, NTDB_LOG_ERROR,
+ "ntdb_allrecord_unlock: have %s lock",
+ ntdb->file->allrecord_lock.ltype == F_RDLCK
+ ? "read" : "write");
+ return;
+ }
+
+ if (ntdb->file->allrecord_lock.count > 1) {
+ ntdb->file->allrecord_lock.count--;
+ return;
+ }
+
+ ntdb->file->allrecord_lock.count = 0;
+ ntdb->file->allrecord_lock.ltype = 0;
+
+ ntdb_brunlock(ntdb, ltype, NTDB_HASH_LOCK_START, 0);
+}
+
+bool ntdb_has_expansion_lock(struct ntdb_context *ntdb)
+{
+ return find_nestlock(ntdb, NTDB_EXPANSION_LOCK, ntdb) != NULL;
+}
+
+bool ntdb_has_hash_locks(struct ntdb_context *ntdb)
+{
+ unsigned int i;
+
+ for (i=0; i<ntdb->file->num_lockrecs; i++) {
+ if (ntdb->file->lockrecs[i].off >= NTDB_HASH_LOCK_START
+ && ntdb->file->lockrecs[i].off < (NTDB_HASH_LOCK_START
+ + (1 << ntdb->hash_bits)))
+ return true;
+ }
+ return false;
+}
+
+static bool ntdb_has_free_lock(struct ntdb_context *ntdb)
+{
+ unsigned int i;
+
+ if (ntdb->flags & NTDB_NOLOCK)
+ return false;
+
+ for (i=0; i<ntdb->file->num_lockrecs; i++) {
+ if (ntdb->file->lockrecs[i].off
+ > NTDB_HASH_LOCK_START + (1 << ntdb->hash_bits))
+ return true;
+ }
+ return false;
+}
+
+enum NTDB_ERROR ntdb_lock_hash(struct ntdb_context *ntdb,
+ unsigned int h,
+ int ltype)
+{
+ unsigned l = NTDB_HASH_LOCK_START + h;
+
+ assert(h < (1 << ntdb->hash_bits));
+
+ /* a allrecord lock allows us to avoid per chain locks */
+ if (ntdb->file->allrecord_lock.count) {
+ if (!check_lock_pid(ntdb, "ntdb_lock_hashes", true))
+ return NTDB_ERR_LOCK;
+
+ if (ntdb->file->allrecord_lock.owner != ntdb)
+ return owner_conflict(ntdb, "ntdb_lock_hashes");
+ if (ltype == ntdb->file->allrecord_lock.ltype
+ || ltype == F_RDLCK) {
+ return NTDB_SUCCESS;
+ }
+
+ return ntdb_logerr(ntdb, NTDB_ERR_LOCK, NTDB_LOG_USE_ERROR,
+ "ntdb_lock_hashes:"
+ " already have %s allrecordlock",
+ ntdb->file->allrecord_lock.ltype == F_RDLCK
+ ? "read" : "write");
+ }
+
+ if (ntdb_has_free_lock(ntdb)) {
+ return ntdb_logerr(ntdb, NTDB_ERR_LOCK, NTDB_LOG_ERROR,
+ "ntdb_lock_hashes: already have free lock");
+ }
+
+ if (ntdb_has_expansion_lock(ntdb)) {
+ return ntdb_logerr(ntdb, NTDB_ERR_LOCK, NTDB_LOG_ERROR,
+ "ntdb_lock_hashes:"
+ " already have expansion lock");
+ }
+
+ return ntdb_nest_lock(ntdb, l, ltype, NTDB_LOCK_WAIT);
+}
+
+enum NTDB_ERROR ntdb_unlock_hash(struct ntdb_context *ntdb,
+ unsigned int h, int ltype)
+{
+ unsigned l = NTDB_HASH_LOCK_START + (h & ((1 << ntdb->hash_bits)-1));
+
+ if (ntdb->flags & NTDB_NOLOCK)
+ return 0;
+
+ /* a allrecord lock allows us to avoid per chain locks */
+ if (ntdb->file->allrecord_lock.count) {
+ if (ntdb->file->allrecord_lock.ltype == F_RDLCK
+ && ltype == F_WRLCK) {
+ return ntdb_logerr(ntdb, NTDB_ERR_LOCK, NTDB_LOG_ERROR,
+ "ntdb_unlock_hashes RO allrecord!");
+ }
+ if (ntdb->file->allrecord_lock.owner != ntdb) {
+ return ntdb_logerr(ntdb, NTDB_ERR_LOCK, NTDB_LOG_USE_ERROR,
+ "ntdb_unlock_hashes:"
+ " not locked by us!");
+ }
+ return NTDB_SUCCESS;
+ }
+
+ return ntdb_nest_unlock(ntdb, l, ltype);
+}
+
+/* Hash locks use NTDB_HASH_LOCK_START + <number of hash entries>..
+ * Then we begin; bucket offsets are sizeof(ntdb_len_t) apart, so we divide.
+ * The result is that on 32 bit systems we don't use lock values > 2^31 on
+ * files that are less than 4GB.
+ */
+static ntdb_off_t free_lock_off(const struct ntdb_context *ntdb,
+ ntdb_off_t b_off)
+{
+ return NTDB_HASH_LOCK_START + (1 << ntdb->hash_bits)
+ + b_off / sizeof(ntdb_off_t);
+}
+
+enum NTDB_ERROR ntdb_lock_free_bucket(struct ntdb_context *ntdb, ntdb_off_t b_off,
+ enum ntdb_lock_flags waitflag)
+{
+ assert(b_off >= sizeof(struct ntdb_header));
+
+ if (ntdb->flags & NTDB_NOLOCK)
+ return 0;
+
+ /* a allrecord lock allows us to avoid per chain locks */
+ if (ntdb->file->allrecord_lock.count) {
+ if (!check_lock_pid(ntdb, "ntdb_lock_free_bucket", true))
+ return NTDB_ERR_LOCK;
+
+ if (ntdb->file->allrecord_lock.owner != ntdb) {
+ return owner_conflict(ntdb, "ntdb_lock_free_bucket");
+ }
+
+ if (ntdb->file->allrecord_lock.ltype == F_WRLCK)
+ return 0;
+ return ntdb_logerr(ntdb, NTDB_ERR_LOCK, NTDB_LOG_ERROR,
+ "ntdb_lock_free_bucket with"
+ " read-only allrecordlock!");
+ }
+
+#if 0 /* FIXME */
+ if (ntdb_has_expansion_lock(ntdb)) {
+ return ntdb_logerr(ntdb, NTDB_ERR_LOCK, NTDB_LOG_ERROR,
+ "ntdb_lock_free_bucket:"
+ " already have expansion lock");
+ }
+#endif
+
+ return ntdb_nest_lock(ntdb, free_lock_off(ntdb, b_off), F_WRLCK,
+ waitflag);
+}
+
+void ntdb_unlock_free_bucket(struct ntdb_context *ntdb, ntdb_off_t b_off)
+{
+ if (ntdb->file->allrecord_lock.count)
+ return;
+
+ ntdb_nest_unlock(ntdb, free_lock_off(ntdb, b_off), F_WRLCK);
+}
+
+_PUBLIC_ enum NTDB_ERROR ntdb_lockall(struct ntdb_context *ntdb)
+{
+ return ntdb_allrecord_lock(ntdb, F_WRLCK, NTDB_LOCK_WAIT, false);
+}
+
+_PUBLIC_ void ntdb_unlockall(struct ntdb_context *ntdb)
+{
+ ntdb_allrecord_unlock(ntdb, F_WRLCK);
+}
+
+_PUBLIC_ enum NTDB_ERROR ntdb_lockall_read(struct ntdb_context *ntdb)
+{
+ return ntdb_allrecord_lock(ntdb, F_RDLCK, NTDB_LOCK_WAIT, false);
+}
+
+_PUBLIC_ void ntdb_unlockall_read(struct ntdb_context *ntdb)
+{
+ ntdb_allrecord_unlock(ntdb, F_RDLCK);
+}
+
+void ntdb_lock_cleanup(struct ntdb_context *ntdb)
+{
+ unsigned int i;
+
+ /* We don't want to warn: they're allowed to close ntdb after fork. */
+ if (!check_lock_pid(ntdb, "ntdb_close", false))
+ return;
+
+ while (ntdb->file->allrecord_lock.count
+ && ntdb->file->allrecord_lock.owner == ntdb) {
+ ntdb_allrecord_unlock(ntdb, ntdb->file->allrecord_lock.ltype);
+ }
+
+ for (i=0; i<ntdb->file->num_lockrecs; i++) {
+ if (ntdb->file->lockrecs[i].owner == ntdb) {
+ ntdb_nest_unlock(ntdb,
+ ntdb->file->lockrecs[i].off,
+ ntdb->file->lockrecs[i].ltype);
+ i--;
+ }
+ }
+}
projects / ccan / blobdiff