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Unix SMB/CIFS implementation.
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trivial database library
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Copyright (C) Andrew Tridgell 1999-2005
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Copyright (C) Paul `Rusty' Russell 2000
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Copyright (C) Jeremy Allison 2000-2003
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** NOTE! The following LGPL license applies to the tdb
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** library. This does NOT imply that all of Samba is released
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This library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 3 of the License, or (at your option) any later version.
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This library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with this library; if not, see <http://www.gnu.org/licenses/>.
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#include "tdb_private.h"
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/* all contexts, to ensure no double-opens (fcntl locks don't nest!) */
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static struct tdb_context *tdbs = NULL;
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/* This is based on the hash algorithm from gdbm */
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static unsigned int default_tdb_hash(TDB_DATA *key)
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uint32_t value; /* Used to compute the hash value. */
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uint32_t i; /* Used to cycle through random values. */
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/* Set the initial value from the key size. */
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for (value = 0x238F13AF * key->dsize, i=0; i < key->dsize; i++)
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value = (value + (key->dptr[i] << (i*5 % 24)));
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return (1103515243 * value + 12345);
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/* initialise a new database with a specified hash size */
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static int tdb_new_database(struct tdb_context *tdb, int hash_size)
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struct tdb_header *newdb;
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/* We make it up in memory, then write it out if not internal */
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size = sizeof(struct tdb_header) + (hash_size+1)*sizeof(tdb_off_t);
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if (!(newdb = (struct tdb_header *)calloc(size, 1)))
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return TDB_ERRCODE(TDB_ERR_OOM, -1);
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/* Fill in the header */
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newdb->version = TDB_VERSION;
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newdb->hash_size = hash_size;
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if (tdb->flags & TDB_INTERNAL) {
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tdb->map_ptr = (char *)newdb;
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memcpy(&tdb->header, newdb, sizeof(tdb->header));
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/* Convert the `ondisk' version if asked. */
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if (lseek(tdb->fd, 0, SEEK_SET) == -1)
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if (ftruncate(tdb->fd, 0) == -1)
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/* This creates an endian-converted header, as if read from disk */
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memcpy(&tdb->header, newdb, sizeof(tdb->header));
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/* Don't endian-convert the magic food! */
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memcpy(newdb->magic_food, TDB_MAGIC_FOOD, strlen(TDB_MAGIC_FOOD)+1);
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/* we still have "ret == -1" here */
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written = write(tdb->fd, newdb, size);
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if (written == size) {
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} else if (written != -1) {
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/* call write once again, this usually should return -1 and
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* set errno appropriately */
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written = write(tdb->fd, newdb+written, size);
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if (written == size) {
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} else if (written >= 0) {
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/* a second incomplete write - we give up.
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* guessing the errno... */
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static int tdb_already_open(dev_t device,
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struct tdb_context *i;
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for (i = tdbs; i; i = i->next) {
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if (i->device == device && i->inode == ino) {
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/* open the database, creating it if necessary
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The open_flags and mode are passed straight to the open call on the
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database file. A flags value of O_WRONLY is invalid. The hash size
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is advisory, use zero for a default value.
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Return is NULL on error, in which case errno is also set. Don't
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try to call tdb_error or tdb_errname, just do strerror(errno).
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@param name may be NULL for internal databases. */
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struct tdb_context *tdb_open(const char *name, int hash_size, int tdb_flags,
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int open_flags, mode_t mode)
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return tdb_open_ex(name, hash_size, tdb_flags, open_flags, mode, NULL, NULL);
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/* a default logging function */
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static void null_log_fn(struct tdb_context *tdb, enum tdb_debug_level level, const char *fmt, ...) PRINTF_ATTRIBUTE(3, 4);
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static void null_log_fn(struct tdb_context *tdb, enum tdb_debug_level level, const char *fmt, ...)
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struct tdb_context *tdb_open_ex(const char *name, int hash_size, int tdb_flags,
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int open_flags, mode_t mode,
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const struct tdb_logging_context *log_ctx,
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tdb_hash_func hash_fn)
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struct tdb_context *tdb;
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int rev = 0, locked = 0;
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if (!(tdb = (struct tdb_context *)calloc(1, sizeof *tdb))) {
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tdb->flags = tdb_flags;
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tdb->open_flags = open_flags;
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tdb->log.log_fn = null_log_fn;
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tdb->log.log_private = NULL;
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tdb->hash_fn = hash_fn ? hash_fn : default_tdb_hash;
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/* cache the page size */
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tdb->page_size = getpagesize();
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if (tdb->page_size <= 0) {
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tdb->page_size = 0x2000;
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tdb->max_dead_records = (tdb_flags & TDB_VOLATILE) ? 5 : 0;
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if ((open_flags & O_ACCMODE) == O_WRONLY) {
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TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_open_ex: can't open tdb %s write-only\n",
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hash_size = DEFAULT_HASH_SIZE;
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if ((open_flags & O_ACCMODE) == O_RDONLY) {
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/* read only databases don't do locking or clear if first */
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tdb->flags |= TDB_NOLOCK;
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tdb->flags &= ~TDB_CLEAR_IF_FIRST;
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/* internal databases don't mmap or lock, and start off cleared */
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if (tdb->flags & TDB_INTERNAL) {
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tdb->flags |= (TDB_NOLOCK | TDB_NOMMAP);
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tdb->flags &= ~TDB_CLEAR_IF_FIRST;
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if (tdb_new_database(tdb, hash_size) != 0) {
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TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_open_ex: tdb_new_database failed!"));
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if ((tdb->fd = open(name, open_flags, mode)) == -1) {
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TDB_LOG((tdb, TDB_DEBUG_WARNING, "tdb_open_ex: could not open file %s: %s\n",
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name, strerror(errno)));
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goto fail; /* errno set by open(2) */
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/* on exec, don't inherit the fd */
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v = fcntl(tdb->fd, F_GETFD, 0);
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fcntl(tdb->fd, F_SETFD, v | FD_CLOEXEC);
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/* ensure there is only one process initialising at once */
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if (tdb->methods->tdb_brlock(tdb, GLOBAL_LOCK, F_WRLCK, F_SETLKW, 0, 1) == -1) {
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TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_open_ex: failed to get global lock on %s: %s\n",
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name, strerror(errno)));
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goto fail; /* errno set by tdb_brlock */
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/* we need to zero database if we are the only one with it open */
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if ((tdb_flags & TDB_CLEAR_IF_FIRST) &&
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(locked = (tdb->methods->tdb_brlock(tdb, ACTIVE_LOCK, F_WRLCK, F_SETLK, 0, 1) == 0))) {
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open_flags |= O_CREAT;
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if (ftruncate(tdb->fd, 0) == -1) {
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TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_open_ex: "
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"failed to truncate %s: %s\n",
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name, strerror(errno)));
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goto fail; /* errno set by ftruncate */
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if (read(tdb->fd, &tdb->header, sizeof(tdb->header)) != sizeof(tdb->header)
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|| strcmp(tdb->header.magic_food, TDB_MAGIC_FOOD) != 0
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|| (tdb->header.version != TDB_VERSION
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&& !(rev = (tdb->header.version==TDB_BYTEREV(TDB_VERSION))))) {
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/* its not a valid database - possibly initialise it */
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if (!(open_flags & O_CREAT) || tdb_new_database(tdb, hash_size) == -1) {
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errno = EIO; /* ie bad format or something */
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rev = (tdb->flags & TDB_CONVERT);
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vp = (unsigned char *)&tdb->header.version;
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vertest = (((uint32_t)vp[0]) << 24) | (((uint32_t)vp[1]) << 16) |
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(((uint32_t)vp[2]) << 8) | (uint32_t)vp[3];
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tdb->flags |= (vertest==TDB_VERSION) ? TDB_BIGENDIAN : 0;
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tdb->flags &= ~TDB_CONVERT;
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tdb->flags |= TDB_CONVERT;
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tdb_convert(&tdb->header, sizeof(tdb->header));
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if (fstat(tdb->fd, &st) == -1)
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if (tdb->header.rwlocks != 0) {
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TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_open_ex: spinlocks no longer supported\n"));
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/* Is it already in the open list? If so, fail. */
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if (tdb_already_open(st.st_dev, st.st_ino)) {
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TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_open_ex: "
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"%s (%d,%d) is already open in this process\n",
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name, (int)st.st_dev, (int)st.st_ino));
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if (!(tdb->name = (char *)strdup(name))) {
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tdb->map_size = st.st_size;
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tdb->device = st.st_dev;
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tdb->inode = st.st_ino;
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if (tdb->methods->tdb_brlock(tdb, ACTIVE_LOCK, F_UNLCK, F_SETLK, 0, 1) == -1) {
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TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_open_ex: "
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"failed to take ACTIVE_LOCK on %s: %s\n",
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name, strerror(errno)));
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/* We always need to do this if the CLEAR_IF_FIRST flag is set, even if
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we didn't get the initial exclusive lock as we need to let all other
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users know we're using it. */
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if (tdb_flags & TDB_CLEAR_IF_FIRST) {
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/* leave this lock in place to indicate it's in use */
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if (tdb->methods->tdb_brlock(tdb, ACTIVE_LOCK, F_RDLCK, F_SETLKW, 0, 1) == -1)
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/* if needed, run recovery */
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if (tdb_transaction_recover(tdb) == -1) {
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/* Internal (memory-only) databases skip all the code above to
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* do with disk files, and resume here by releasing their
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* global lock and hooking into the active list. */
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if (tdb->methods->tdb_brlock(tdb, GLOBAL_LOCK, F_UNLCK, F_SETLKW, 0, 1) == -1)
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{ int save_errno = errno;
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if (tdb->flags & TDB_INTERNAL)
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SAFE_FREE(tdb->map_ptr);
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SAFE_FREE(tdb->name);
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if (close(tdb->fd) != 0)
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TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_open_ex: failed to close tdb->fd on error!\n"));
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* Set the maximum number of dead records per hash chain
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void tdb_set_max_dead(struct tdb_context *tdb, int max_dead)
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tdb->max_dead_records = max_dead;
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* @returns -1 for error; 0 for success.
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int tdb_close(struct tdb_context *tdb)
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struct tdb_context **i;
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if (tdb->transaction) {
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tdb_transaction_cancel(tdb);
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if (tdb->flags & TDB_INTERNAL)
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SAFE_FREE(tdb->map_ptr);
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SAFE_FREE(tdb->name);
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ret = close(tdb->fd);
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SAFE_FREE(tdb->lockrecs);
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/* Remove from contexts list */
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for (i = &tdbs; *i; i = &(*i)->next) {
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memset(tdb, 0, sizeof(*tdb));
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/* register a loging function */
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void tdb_set_logging_function(struct tdb_context *tdb,
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const struct tdb_logging_context *log_ctx)
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void *tdb_get_logging_private(struct tdb_context *tdb)
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return tdb->log.log_private;
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/* reopen a tdb - this can be used after a fork to ensure that we have an independent
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seek pointer from our parent and to re-establish locks */
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int tdb_reopen(struct tdb_context *tdb)
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if (tdb->flags & TDB_INTERNAL) {
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return 0; /* Nothing to do. */
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if (tdb->num_locks != 0 || tdb->global_lock.count) {
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TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_reopen: reopen not allowed with locks held\n"));
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if (tdb->transaction != 0) {
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TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_reopen: reopen not allowed inside a transaction\n"));
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if (tdb_munmap(tdb) != 0) {
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TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_reopen: munmap failed (%s)\n", strerror(errno)));
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if (close(tdb->fd) != 0)
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TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_reopen: WARNING closing tdb->fd failed!\n"));
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tdb->fd = open(tdb->name, tdb->open_flags & ~(O_CREAT|O_TRUNC), 0);
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TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_reopen: open failed (%s)\n", strerror(errno)));
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if ((tdb->flags & TDB_CLEAR_IF_FIRST) &&
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(tdb->methods->tdb_brlock(tdb, ACTIVE_LOCK, F_RDLCK, F_SETLKW, 0, 1) == -1)) {
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TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_reopen: failed to obtain active lock\n"));
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if (fstat(tdb->fd, &st) != 0) {
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TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_reopen: fstat failed (%s)\n", strerror(errno)));
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if (st.st_ino != tdb->inode || st.st_dev != tdb->device) {
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TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_reopen: file dev/inode has changed!\n"));
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/* reopen all tdb's */
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int tdb_reopen_all(int parent_longlived)
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struct tdb_context *tdb;
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for (tdb=tdbs; tdb; tdb = tdb->next) {
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* If the parent is longlived (ie. a
469
* parent daemon architecture), we know
470
* it will keep it's active lock on a
471
* tdb opened with CLEAR_IF_FIRST. Thus
472
* for child processes we don't have to
473
* add an active lock. This is essential
474
* to improve performance on systems that
475
* keep POSIX locks as a non-scalable data
476
* structure in the kernel.
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if (parent_longlived) {
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/* Ensure no clear-if-first. */
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tdb->flags &= ~TDB_CLEAR_IF_FIRST;
483
if (tdb_reopen(tdb) != 0)
added
removed
lib/tdb/common/open.c
