diff options
Diffstat (limited to 'source3/tdb/common/tdb.c')
| -rw-r--r-- | source3/tdb/common/tdb.c | 431 |
1 files changed, 431 insertions, 0 deletions
diff --git a/source3/tdb/common/tdb.c b/source3/tdb/common/tdb.c new file mode 100644 index 0000000000..524d404a50 --- /dev/null +++ b/source3/tdb/common/tdb.c @@ -0,0 +1,431 @@ + /* + 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 2 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, write to the Free Software + Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA +*/ + +#include "tdb_private.h" + +TDB_DATA tdb_null; + +/* + increment the tdb sequence number if the tdb has been opened using + the TDB_SEQNUM flag +*/ +static void tdb_increment_seqnum(struct tdb_context *tdb) +{ + tdb_off_t seqnum=0; + + if (!(tdb->flags & TDB_SEQNUM)) { + return; + } + + if (tdb_brlock(tdb, TDB_SEQNUM_OFS, F_WRLCK, F_SETLKW, 1) != 0) { + return; + } + + /* we ignore errors from this, as we have no sane way of + dealing with them. + */ + tdb_ofs_read(tdb, TDB_SEQNUM_OFS, &seqnum); + seqnum++; + tdb_ofs_write(tdb, TDB_SEQNUM_OFS, &seqnum); + + tdb_brlock(tdb, TDB_SEQNUM_OFS, F_UNLCK, F_SETLKW, 1); +} + + +/* Returns 0 on fail. On success, return offset of record, and fills + in rec */ +static tdb_off_t tdb_find(struct tdb_context *tdb, TDB_DATA key, u32 hash, + struct list_struct *r) +{ + tdb_off_t rec_ptr; + + /* read in the hash top */ + if (tdb_ofs_read(tdb, TDB_HASH_TOP(hash), &rec_ptr) == -1) + return 0; + + /* keep looking until we find the right record */ + while (rec_ptr) { + if (tdb_rec_read(tdb, rec_ptr, r) == -1) + return 0; + + if (!TDB_DEAD(r) && hash==r->full_hash && key.dsize==r->key_len) { + char *k; + /* a very likely hit - read the key */ + k = tdb_alloc_read(tdb, rec_ptr + sizeof(*r), + r->key_len); + if (!k) + return 0; + + if (memcmp(key.dptr, k, key.dsize) == 0) { + SAFE_FREE(k); + return rec_ptr; + } + SAFE_FREE(k); + } + rec_ptr = r->next; + } + return TDB_ERRCODE(TDB_ERR_NOEXIST, 0); +} + +/* As tdb_find, but if you succeed, keep the lock */ +tdb_off_t tdb_find_lock_hash(struct tdb_context *tdb, TDB_DATA key, u32 hash, int locktype, + struct list_struct *rec) +{ + u32 rec_ptr; + + if (tdb_lock(tdb, BUCKET(hash), locktype) == -1) + return 0; + if (!(rec_ptr = tdb_find(tdb, key, hash, rec))) + tdb_unlock(tdb, BUCKET(hash), locktype); + return rec_ptr; +} + + +/* update an entry in place - this only works if the new data size + is <= the old data size and the key exists. + on failure return -1. +*/ +static int tdb_update_hash(struct tdb_context *tdb, TDB_DATA key, u32 hash, TDB_DATA dbuf) +{ + struct list_struct rec; + tdb_off_t rec_ptr; + + /* find entry */ + if (!(rec_ptr = tdb_find(tdb, key, hash, &rec))) + return -1; + + /* must be long enough key, data and tailer */ + if (rec.rec_len < key.dsize + dbuf.dsize + sizeof(tdb_off_t)) { + tdb->ecode = TDB_SUCCESS; /* Not really an error */ + return -1; + } + + if (tdb->methods->tdb_write(tdb, rec_ptr + sizeof(rec) + rec.key_len, + dbuf.dptr, dbuf.dsize) == -1) + return -1; + + if (dbuf.dsize != rec.data_len) { + /* update size */ + rec.data_len = dbuf.dsize; + return tdb_rec_write(tdb, rec_ptr, &rec); + } + + return 0; +} + +/* find an entry in the database given a key */ +/* If an entry doesn't exist tdb_err will be set to + * TDB_ERR_NOEXIST. If a key has no data attached + * then the TDB_DATA will have zero length but + * a non-zero pointer + */ +TDB_DATA tdb_fetch(struct tdb_context *tdb, TDB_DATA key) +{ + tdb_off_t rec_ptr; + struct list_struct rec; + TDB_DATA ret; + u32 hash; + + /* find which hash bucket it is in */ + hash = tdb->hash_fn(&key); + if (!(rec_ptr = tdb_find_lock_hash(tdb,key,hash,F_RDLCK,&rec))) + return tdb_null; + + ret.dptr = tdb_alloc_read(tdb, rec_ptr + sizeof(rec) + rec.key_len, + rec.data_len); + ret.dsize = rec.data_len; + tdb_unlock(tdb, BUCKET(rec.full_hash), F_RDLCK); + return ret; +} + +/* check if an entry in the database exists + + note that 1 is returned if the key is found and 0 is returned if not found + this doesn't match the conventions in the rest of this module, but is + compatible with gdbm +*/ +static int tdb_exists_hash(struct tdb_context *tdb, TDB_DATA key, u32 hash) +{ + struct list_struct rec; + + if (tdb_find_lock_hash(tdb, key, hash, F_RDLCK, &rec) == 0) + return 0; + tdb_unlock(tdb, BUCKET(rec.full_hash), F_RDLCK); + return 1; +} + +int tdb_exists(struct tdb_context *tdb, TDB_DATA key) +{ + u32 hash = tdb->hash_fn(&key); + return tdb_exists_hash(tdb, key, hash); +} + +/* actually delete an entry in the database given the offset */ +int tdb_do_delete(struct tdb_context *tdb, tdb_off_t rec_ptr, struct list_struct*rec) +{ + tdb_off_t last_ptr, i; + struct list_struct lastrec; + + if (tdb->read_only || tdb->traverse_read) return -1; + + if (tdb_write_lock_record(tdb, rec_ptr) == -1) { + /* Someone traversing here: mark it as dead */ + rec->magic = TDB_DEAD_MAGIC; + return tdb_rec_write(tdb, rec_ptr, rec); + } + if (tdb_write_unlock_record(tdb, rec_ptr) != 0) + return -1; + + /* find previous record in hash chain */ + if (tdb_ofs_read(tdb, TDB_HASH_TOP(rec->full_hash), &i) == -1) + return -1; + for (last_ptr = 0; i != rec_ptr; last_ptr = i, i = lastrec.next) + if (tdb_rec_read(tdb, i, &lastrec) == -1) + return -1; + + /* unlink it: next ptr is at start of record. */ + if (last_ptr == 0) + last_ptr = TDB_HASH_TOP(rec->full_hash); + if (tdb_ofs_write(tdb, last_ptr, &rec->next) == -1) + return -1; + + /* recover the space */ + if (tdb_free(tdb, rec_ptr, rec) == -1) + return -1; + return 0; +} + +/* delete an entry in the database given a key */ +static int tdb_delete_hash(struct tdb_context *tdb, TDB_DATA key, u32 hash) +{ + tdb_off_t rec_ptr; + struct list_struct rec; + int ret; + + if (!(rec_ptr = tdb_find_lock_hash(tdb, key, hash, F_WRLCK, &rec))) + return -1; + ret = tdb_do_delete(tdb, rec_ptr, &rec); + + if (ret == 0) { + tdb_increment_seqnum(tdb); + } + + if (tdb_unlock(tdb, BUCKET(rec.full_hash), F_WRLCK) != 0) + TDB_LOG((tdb, 0, "tdb_delete: WARNING tdb_unlock failed!\n")); + return ret; +} + +int tdb_delete(struct tdb_context *tdb, TDB_DATA key) +{ + u32 hash = tdb->hash_fn(&key); + return tdb_delete_hash(tdb, key, hash); +} + +/* store an element in the database, replacing any existing element + with the same key + + return 0 on success, -1 on failure +*/ +int tdb_store(struct tdb_context *tdb, TDB_DATA key, TDB_DATA dbuf, int flag) +{ + struct list_struct rec; + u32 hash; + tdb_off_t rec_ptr; + char *p = NULL; + int ret = 0; + + if (tdb->read_only || tdb->traverse_read) { + tdb->ecode = TDB_ERR_RDONLY; + return -1; + } + + /* find which hash bucket it is in */ + hash = tdb->hash_fn(&key); + if (tdb_lock(tdb, BUCKET(hash), F_WRLCK) == -1) + return -1; + + /* check for it existing, on insert. */ + if (flag == TDB_INSERT) { + if (tdb_exists_hash(tdb, key, hash)) { + tdb->ecode = TDB_ERR_EXISTS; + goto fail; + } + } else { + /* first try in-place update, on modify or replace. */ + if (tdb_update_hash(tdb, key, hash, dbuf) == 0) + goto out; + if (tdb->ecode == TDB_ERR_NOEXIST && + flag == TDB_MODIFY) { + /* if the record doesn't exist and we are in TDB_MODIFY mode then + we should fail the store */ + goto fail; + } + } + /* reset the error code potentially set by the tdb_update() */ + tdb->ecode = TDB_SUCCESS; + + /* delete any existing record - if it doesn't exist we don't + care. Doing this first reduces fragmentation, and avoids + coalescing with `allocated' block before it's updated. */ + if (flag != TDB_INSERT) + tdb_delete_hash(tdb, key, hash); + + /* Copy key+value *before* allocating free space in case malloc + fails and we are left with a dead spot in the tdb. */ + + if (!(p = (char *)malloc(key.dsize + dbuf.dsize))) { + tdb->ecode = TDB_ERR_OOM; + goto fail; + } + + memcpy(p, key.dptr, key.dsize); + if (dbuf.dsize) + memcpy(p+key.dsize, dbuf.dptr, dbuf.dsize); + + /* we have to allocate some space */ + if (!(rec_ptr = tdb_allocate(tdb, key.dsize + dbuf.dsize, &rec))) + goto fail; + + /* Read hash top into next ptr */ + if (tdb_ofs_read(tdb, TDB_HASH_TOP(hash), &rec.next) == -1) + goto fail; + + rec.key_len = key.dsize; + rec.data_len = dbuf.dsize; + rec.full_hash = hash; + rec.magic = TDB_MAGIC; + + /* write out and point the top of the hash chain at it */ + if (tdb_rec_write(tdb, rec_ptr, &rec) == -1 + || tdb->methods->tdb_write(tdb, rec_ptr+sizeof(rec), p, key.dsize+dbuf.dsize)==-1 + || tdb_ofs_write(tdb, TDB_HASH_TOP(hash), &rec_ptr) == -1) { + /* Need to tdb_unallocate() here */ + goto fail; + } + + tdb_increment_seqnum(tdb); + + out: + SAFE_FREE(p); + tdb_unlock(tdb, BUCKET(hash), F_WRLCK); + return ret; +fail: + ret = -1; + goto out; +} + + +/* Append to an entry. Create if not exist. */ +int tdb_append(struct tdb_context *tdb, TDB_DATA key, TDB_DATA new_dbuf) +{ + u32 hash; + TDB_DATA dbuf; + int ret = -1; + + /* find which hash bucket it is in */ + hash = tdb->hash_fn(&key); + if (tdb_lock(tdb, BUCKET(hash), F_WRLCK) == -1) + return -1; + + dbuf = tdb_fetch(tdb, key); + + if (dbuf.dptr == NULL) { + dbuf.dptr = (char *)malloc(new_dbuf.dsize); + } else { + dbuf.dptr = (char *)realloc(dbuf.dptr, + dbuf.dsize + new_dbuf.dsize); + } + + if (dbuf.dptr == NULL) { + tdb->ecode = TDB_ERR_OOM; + goto failed; + } + + memcpy(dbuf.dptr + dbuf.dsize, new_dbuf.dptr, new_dbuf.dsize); + dbuf.dsize += new_dbuf.dsize; + + ret = tdb_store(tdb, key, dbuf, 0); + +failed: + tdb_unlock(tdb, BUCKET(hash), F_WRLCK); + SAFE_FREE(dbuf.dptr); + return ret; +} + + +/* + return the name of the current tdb file + useful for external logging functions +*/ +const char *tdb_name(struct tdb_context *tdb) +{ + return tdb->name; +} + +/* + return the underlying file descriptor being used by tdb, or -1 + useful for external routines that want to check the device/inode + of the fd +*/ +int tdb_fd(struct tdb_context *tdb) +{ + return tdb->fd; +} + +/* + return the current logging function + useful for external tdb routines that wish to log tdb errors +*/ +tdb_log_func tdb_log_fn(struct tdb_context *tdb) +{ + return tdb->log_fn; +} + + +/* + get the tdb sequence number. Only makes sense if the writers opened + with TDB_SEQNUM set. Note that this sequence number will wrap quite + quickly, so it should only be used for a 'has something changed' + test, not for code that relies on the count of the number of changes + made. If you want a counter then use a tdb record. + + The aim of this sequence number is to allow for a very lightweight + test of a possible tdb change. +*/ +int tdb_get_seqnum(struct tdb_context *tdb) +{ + tdb_off_t seqnum=0; + + tdb_ofs_read(tdb, TDB_SEQNUM_OFS, &seqnum); + return seqnum; +} + +int tdb_hash_size(struct tdb_context *tdb) +{ + return tdb->header.hash_size; +} |