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/*
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) {
unsigned 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, TDB_DEBUG_WARNING, "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 = malloc(new_dbuf.dsize);
} else {
dbuf.dptr = 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;
}
|