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|
/*
Unix SMB/Netbios implementation.
Version 3.0
Samba database functions
Copyright (C) Andrew Tridgell 1999-2000
Copyright (C) Luke Kenneth Casson Leighton 2000
Copyright (C) Paul `Rusty' Russell 2000
Copyright (C) Jeremy Allison 2000
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#ifdef STANDALONE
#if HAVE_CONFIG_H
#include <config.h>
#endif
#include <stdlib.h>
#include <stdio.h>
#include <fcntl.h>
#include <unistd.h>
#include <string.h>
#include <fcntl.h>
#include <errno.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include "tdb.h"
#include "spinlock.h"
#else
#include "includes.h"
#endif
#define TDB_MAGIC_FOOD "TDB file\n"
#define TDB_VERSION (0x26011967 + 6)
#define TDB_MAGIC (0x26011999U)
#define TDB_FREE_MAGIC (~TDB_MAGIC)
#define TDB_DEAD_MAGIC (0xFEE1DEAD)
#define TDB_ALIGNMENT 4
#define MIN_REC_SIZE (2*sizeof(struct list_struct) + TDB_ALIGNMENT)
#define DEFAULT_HASH_SIZE 131
#define TDB_PAGE_SIZE 0x2000
#define FREELIST_TOP (sizeof(struct tdb_header))
#define TDB_ALIGN(x,a) (((x) + (a)-1) & ~((a)-1))
#define TDB_BYTEREV(x) (((((x)&0xff)<<24)|((x)&0xFF00)<<8)|(((x)>>8)&0xFF00)|((x)>>24))
#define TDB_DEAD(r) ((r)->magic == TDB_DEAD_MAGIC)
#define TDB_BAD_MAGIC(r) ((r)->magic != TDB_MAGIC && !TDB_DEAD(r))
#define TDB_HASH_TOP(hash) (FREELIST_TOP + (BUCKET(hash)+1)*sizeof(tdb_off))
/* lock offsets */
#define GLOBAL_LOCK 0
#define ACTIVE_LOCK 4
#ifndef MAP_FILE
#define MAP_FILE 0
#endif
#define BUCKET(hash) ((hash) % tdb->header.hash_size)
TDB_DATA tdb_null;
/* all contexts, to ensure no double-opens (fcntl locks don't nest!) */
static TDB_CONTEXT *tdbs = NULL;
static void *tdb_munmap(void *ptr, tdb_len size)
{
#ifdef HAVE_MMAP
munmap(ptr, size);
#endif
return NULL;
}
static void *tdb_mmap(tdb_len size, int read_only, int fd)
{
void *ret = NULL;
#ifdef HAVE_MMAP
ret = mmap(NULL, size, PROT_READ | (read_only ? 0 : PROT_WRITE), MAP_SHARED|MAP_FILE, fd, 0);
if (ret == (void *)-1)
ret = NULL;
#endif
return ret;
}
/* Endian conversion: we only ever deal with 4 byte quantities */
static void *convert(void *buf, u32 size)
{
u32 i, *p = buf;
for (i = 0; i < size / 4; i++) p[i] = TDB_BYTEREV(p[i]);
return buf;
}
#define DOCONV() (tdb->flags & TDB_CONVERT)
#define CONVERT(x) (DOCONV() ? convert(&x, sizeof(x)) : &x)
/* the body of the database is made of one list_struct for the free space
plus a separate data list for each hash value */
struct list_struct {
tdb_off next; /* offset of the next record in the list */
tdb_len rec_len; /* total byte length of record */
tdb_len key_len; /* byte length of key */
tdb_len data_len; /* byte length of data */
u32 full_hash; /* the full 32 bit hash of the key */
u32 magic; /* try to catch errors */
/* the following union is implied:
union {
char record[rec_len];
struct {
char key[key_len];
char data[data_len];
}
u32 totalsize; (tailer)
} */
};
/* a byte range locking function - return 0 on success
this functions locks/unlocks 1 byte at the specified offset */
static int tdb_brlock(TDB_CONTEXT *tdb, tdb_off offset,
int rw_type, int lck_type)
{
struct flock fl;
if (tdb->flags & TDB_NOLOCK) return 0;
if (tdb->read_only) return -1;
fl.l_type = rw_type;
fl.l_whence = SEEK_SET;
fl.l_start = offset;
fl.l_len = 1;
fl.l_pid = 0;
if (fcntl(tdb->fd,lck_type,&fl)) return TDB_ERRCODE(TDB_ERR_LOCK, -1);
return 0;
}
/* lock a list in the database. list -1 is the alloc list */
static int tdb_lock(TDB_CONTEXT *tdb, int list, int ltype)
{
if (list < -1 || list >= (int)tdb->header.hash_size) return -1;
if (tdb->flags & TDB_NOLOCK) return 0;
/* Since fcntl locks don't nest, we do a lock for the first one,
and simply bump the count for future ones */
if (tdb->locked[list+1].count == 0) {
if (tdb->header.rwlocks) {
if (tdb_spinlock(tdb, list, ltype)) return -1;
} else if (tdb_brlock(tdb,FREELIST_TOP+4*list,ltype,F_SETLKW))
return -1;
tdb->locked[list+1].ltype = ltype;
}
tdb->locked[list+1].count++;
return 0;
}
/* unlock the database: returns void because it's too late for errors. */
static void tdb_unlock(TDB_CONTEXT *tdb, int list, int ltype)
{
if (tdb->flags & TDB_NOLOCK) return;
/* Sanity checks */
if (list < -1 || list >= (int)tdb->header.hash_size) return;
if (tdb->locked[list+1].count==0) return;
if (tdb->locked[list+1].count == 1) {
/* Down to last nested lock: unlock underneath */
if (tdb->header.rwlocks) tdb_spinunlock(tdb, list, ltype);
else tdb_brlock(tdb, FREELIST_TOP+4*list, F_UNLCK, F_SETLKW);
}
tdb->locked[list+1].count--;
}
/* This is based on the hash agorithm from gdbm */
static u32 tdb_hash(TDB_DATA *key)
{
u32 value; /* Used to compute the hash value. */
u32 i; /* Used to cycle through random values. */
/* Set the initial value from the key size. */
for (value = 0x238F13AF * key->dsize, i=0; i < key->dsize; i++)
value = (value + (key->dptr[i] << (i*5 % 24)));
return (1103515243 * value + 12345);
}
/* check for an out of bounds access - if it is out of bounds then
see if the database has been expanded by someone else and expand
if necessary */
static int tdb_oob(TDB_CONTEXT *tdb, tdb_off offset)
{
struct stat st;
if (offset <= tdb->map_size) return 0;
if (tdb->flags & TDB_INTERNAL) return 0;
fstat(tdb->fd, &st);
if (st.st_size <= (size_t)offset) return TDB_ERRCODE(TDB_ERR_IO, -1);
/* Unmap, update size, remap */
if (tdb->map_ptr) tdb->map_ptr=tdb_munmap(tdb->map_ptr, tdb->map_size);
tdb->map_size = st.st_size;
if (!(tdb->flags & TDB_NOMMAP))
tdb->map_ptr = tdb_mmap(tdb->map_size, tdb->read_only,tdb->fd);
return 0;
}
/* write a lump of data at a specified offset */
static int tdb_write(TDB_CONTEXT *tdb, tdb_off off, void *buf, tdb_len len)
{
if (tdb_oob(tdb, off + len) != 0) return -1;
if (tdb->map_ptr) memcpy(off + (char *)tdb->map_ptr, buf, len);
else if (lseek(tdb->fd, off, SEEK_SET) != off
|| write(tdb->fd, buf, len) != (ssize_t)len)
return TDB_ERRCODE(TDB_ERR_IO, -1);
return 0;
}
/* read a lump of data at a specified offset, maybe convert */
static int tdb_read(TDB_CONTEXT *tdb,tdb_off off,void *buf,tdb_len len,int cv)
{
if (tdb_oob(tdb, off + len) != 0) return -1;
if (tdb->map_ptr) memcpy(buf, off + (char *)tdb->map_ptr, len);
else if (lseek(tdb->fd, off, SEEK_SET) != off
|| read(tdb->fd, buf, len) != (ssize_t)len)
return TDB_ERRCODE(TDB_ERR_IO, -1);
if (cv) convert(buf, len);
return 0;
}
/* read a lump of data, allocating the space for it */
static char *tdb_alloc_read(TDB_CONTEXT *tdb, tdb_off offset, tdb_len len)
{
char *buf;
if (!(buf = malloc(len))) return TDB_ERRCODE(TDB_ERR_OOM, buf);
if (tdb_read(tdb, offset, buf, len, 0) == -1) {
free(buf);
return NULL;
}
return buf;
}
/* read/write a tdb_off */
static int ofs_read(TDB_CONTEXT *tdb, tdb_off offset, tdb_off *d)
{
return tdb_read(tdb, offset, (char*)d, sizeof(*d), DOCONV());
}
static int ofs_write(TDB_CONTEXT *tdb, tdb_off offset, tdb_off *d)
{
tdb_off off = *d;
return tdb_write(tdb, offset, CONVERT(off), sizeof(*d));
}
/* read/write a record */
static int rec_read(TDB_CONTEXT *tdb, tdb_off offset, struct list_struct *rec)
{
if (tdb_read(tdb, offset, rec, sizeof(*rec),DOCONV()) == -1) return -1;
if (TDB_BAD_MAGIC(rec)) return TDB_ERRCODE(TDB_ERR_CORRUPT, -1);
return tdb_oob(tdb, rec->next);
}
static int rec_write(TDB_CONTEXT *tdb, tdb_off offset, struct list_struct *rec)
{
struct list_struct r = *rec;
return tdb_write(tdb, offset, CONVERT(r), sizeof(r));
}
/* read a freelist record and check for simple errors */
static int rec_free_read(TDB_CONTEXT *tdb, tdb_off off, struct list_struct*rec)
{
if (tdb_read(tdb, off, rec, sizeof(*rec),DOCONV()) == -1) return -1;
if (rec->magic != TDB_FREE_MAGIC) {
#ifdef TDB_DEBUG
printf("bad magic 0x%08x at offset %d\n",
rec->magic, off);
#endif
return TDB_ERRCODE(TDB_ERR_CORRUPT, -1);
}
if (tdb_oob(tdb, rec->next) != 0) return -1;
return 0;
}
/* update a record tailer (must hold allocation lock) */
static int update_tailer(TDB_CONTEXT *tdb, tdb_off offset,
const struct list_struct *rec)
{
tdb_off totalsize;
/* Offset of tailer from record header */
totalsize = sizeof(*rec) + rec->rec_len;
return ofs_write(tdb, offset + totalsize - sizeof(tdb_off),
&totalsize);
}
#ifdef TDB_DEBUG
void tdb_printfreelist(TDB_CONTEXT *tdb)
{
long total_free = 0;
tdb_off offset, rec_ptr, last_ptr;
struct list_struct rec, lastrec, newrec;
tdb_lock(tdb, -1, F_WRLCK);
last_ptr = 0;
offset = FREELIST_TOP;
/* read in the freelist top */
if (ofs_read(tdb, offset, &rec_ptr) == -1) {
return;
}
printf("freelist top=[0x%08x]\n", rec_ptr );
while (rec_ptr) {
if (tdb_read(tdb, rec_ptr, (char *)&rec, sizeof(rec), DOCONV()) == -1) {
return;
}
if (rec.magic != TDB_FREE_MAGIC) {
printf("bad magic 0x%08x in free list\n", rec.magic);
return;
}
printf("entry offset=[0x%08x], rec.rec_len = [0x%08x (%d)]\n", rec.next, rec.rec_len, rec.rec_len );
total_free += rec.rec_len;
/* move to the next record */
rec_ptr = rec.next;
}
printf("total rec_len = [0x%08x (%d)]\n", total_free, total_free );
tdb_unlock(tdb, -1, F_WRLCK);
}
#endif
/* Remove an element from the freelist. Must have alloc lock. */
static int remove_from_freelist(TDB_CONTEXT *tdb, tdb_off off, tdb_off next)
{
tdb_off last_ptr, i;
/* read in the freelist top */
last_ptr = FREELIST_TOP;
while (ofs_read(tdb, last_ptr, &i) != -1 && i != 0) {
if (i == off) {
/* We've found it! */
return ofs_write(tdb, last_ptr, &next);
}
/* Follow chain (next offset is at start of record) */
last_ptr = i;
}
return TDB_ERRCODE(TDB_ERR_CORRUPT, -1);
}
/* Add an element into the freelist. Merge adjacent records if
neccessary. */
static int tdb_free(TDB_CONTEXT *tdb, tdb_off offset, struct list_struct *rec)
{
tdb_off right, left;
/* Allocation and tailer lock */
if (tdb_lock(tdb, -1, F_WRLCK) != 0) return -1;
/* Look right first (I'm an Australian, dammit) */
right = offset + sizeof(*rec) + rec->rec_len;
if (tdb_oob(tdb, right + sizeof(*rec)) == 0) {
struct list_struct r;
if (tdb_read(tdb, right, &r, sizeof(r), DOCONV()) == -1)
goto fail;
/* If it's free, expand to include it. */
if (r.magic == TDB_FREE_MAGIC) {
if (remove_from_freelist(tdb, right, r.next) == -1)
goto fail;
rec->rec_len += sizeof(r) + r.rec_len;
}
}
/* Look left */
left = offset - 4;
if (left > TDB_HASH_TOP(tdb->header.hash_size-1)) {
struct list_struct l;
tdb_off leftsize;
/* Read in tailer and jump back to header */
if (ofs_read(tdb, left, &leftsize) == -1) goto fail;
left = offset - leftsize;
/* Now read in record */
if (tdb_read(tdb, left, &l, sizeof(l), DOCONV()) == -1)
goto fail;
/* If it's free, expand to include it. */
if (l.magic == TDB_FREE_MAGIC) {
if (remove_from_freelist(tdb, left, l.next) == -1)
goto fail;
offset = left;
rec->rec_len += leftsize;
}
}
if (update_tailer(tdb, offset, rec) == -1) goto fail;
/* Now, prepend to free list */
rec->magic = TDB_FREE_MAGIC;
if (ofs_read(tdb, FREELIST_TOP, &rec->next) == -1) goto fail;
if (rec_write(tdb, offset, rec) == -1) goto fail;
if (ofs_write(tdb, FREELIST_TOP, &offset) == -1) goto fail;
/* And we're done. */
tdb_unlock(tdb, -1, F_WRLCK);
return 0;
fail:
tdb_unlock(tdb, -1, F_WRLCK);
return -1;
}
/* expand the database at least size bytes by expanding the underlying
file and doing the mmap again if necessary */
static int tdb_expand(TDB_CONTEXT *tdb, tdb_off size)
{
struct list_struct rec;
tdb_off offset;
char b = 0;
if (tdb_lock(tdb, -1, F_WRLCK) == -1) return 0;
/* must know about any previous expansions by another process */
tdb_oob(tdb, tdb->map_size + 1);
/* always make room for at least 10 more records, and round
the database up to a multiple of TDB_PAGE_SIZE */
size = TDB_ALIGN(tdb->map_size + size*10, TDB_PAGE_SIZE) - tdb->map_size;
if (!(tdb->flags & TDB_INTERNAL) && tdb->map_ptr)
tdb->map_ptr = tdb_munmap(tdb->map_ptr, tdb->map_size);
/*
* We must ensure the file is unmapped before doing this
* to ensure consistency with systems like OpenBSD where
* writes and mmaps are not consistent.
*/
/* expand the file itself */
if (!(tdb->flags & TDB_INTERNAL)) {
if (lseek(tdb->fd, tdb->map_size + size - 1, SEEK_SET)!=tdb->map_size + size - 1)
goto fail;
if (write(tdb->fd, &b, 1) != 1)
goto fail;
}
tdb->map_size += size;
if (tdb->flags & TDB_INTERNAL)
tdb->map_ptr = realloc(tdb->map_ptr, tdb->map_size);
/*
* We must ensure the file is remapped before adding the space
* to ensure consistency with systems like OpenBSD where
* writes and mmaps are not consistent.
*/
if (!(tdb->flags & TDB_NOMMAP)) {
tdb->map_ptr = tdb_mmap(tdb->map_size, 0, tdb->fd);
/* We're ok if this fails and returns NULL, as we'll
fallback to read/write here. */
}
/* form a new freelist record */
memset(&rec,'\0',sizeof(rec));
rec.rec_len = size - sizeof(rec);
/* link it into the free list */
offset = tdb->map_size - size;
if (tdb_free(tdb, offset, &rec) == -1) goto fail;
tdb_unlock(tdb, -1, F_WRLCK);
return 0;
fail:
tdb_unlock(tdb, -1, F_WRLCK);
return -1;
}
/* allocate some space from the free list. The offset returned points
to a unconnected list_struct within the database with room for at
least length bytes of total data
0 is returned if the space could not be allocated
*/
static tdb_off tdb_allocate(TDB_CONTEXT *tdb, tdb_len length,
struct list_struct *rec)
{
tdb_off rec_ptr, last_ptr, newrec_ptr;
struct list_struct newrec;
if (tdb_lock(tdb, -1, F_WRLCK) == -1) return 0;
/* Extra bytes required for tailer */
length += sizeof(tdb_off);
again:
last_ptr = FREELIST_TOP;
/* read in the freelist top */
if (ofs_read(tdb, FREELIST_TOP, &rec_ptr) == -1) goto fail;
/* keep looking until we find a freelist record big enough */
while (rec_ptr) {
if (rec_free_read(tdb, rec_ptr, rec) == -1) goto fail;
if (rec->rec_len >= length) {
/* found it - now possibly split it up */
if (rec->rec_len > length + MIN_REC_SIZE) {
/* Length of left piece */
length = TDB_ALIGN(length, TDB_ALIGNMENT);
/* Right piece to go on free list */
newrec.rec_len = rec->rec_len
- (sizeof(*rec) + length);
newrec_ptr = rec_ptr + sizeof(*rec) + length;
/* And left record is shortened */
rec->rec_len = length;
} else
newrec_ptr = 0;
/* Remove allocated record from the free list */
if (ofs_write(tdb, last_ptr, &rec->next) == -1)
goto fail;
/* Update header: do this before we drop alloc
lock, otherwise tdb_free() might try to
merge with us, thinking we're free.
(Thanks Jeremy Allison). */
rec->magic = TDB_MAGIC;
if (rec_write(tdb, rec_ptr, rec) == -1)
goto fail;
/* Did we create new block? */
if (newrec_ptr) {
/* Update allocated record tailer (we
shortened it). */
if (update_tailer(tdb, rec_ptr, rec) == -1)
goto fail;
/* Free new record */
if (tdb_free(tdb, newrec_ptr, &newrec) == -1)
goto fail;
}
/* all done - return the new record offset */
tdb_unlock(tdb, -1, F_WRLCK);
return rec_ptr;
}
/* move to the next record */
last_ptr = rec_ptr;
rec_ptr = rec->next;
}
/* we didn't find enough space. See if we can expand the
database and if we can then try again */
if (tdb_expand(tdb, length + sizeof(*rec)) == 0) goto again;
fail:
tdb_unlock(tdb, -1, F_WRLCK);
return 0;
}
/* initialise a new database with a specified hash size */
static int tdb_new_database(TDB_CONTEXT *tdb, int hash_size)
{
struct tdb_header *newdb;
int size, ret;
/* We make it up in memory, then write it out if not internal */
size = sizeof(struct tdb_header) + (hash_size+1)*sizeof(tdb_off);
if (!(newdb = calloc(size, 1))) return TDB_ERRCODE(TDB_ERR_OOM, -1);
/* Fill in the header */
newdb->version = TDB_VERSION;
newdb->hash_size = hash_size;
#ifdef USE_SPINLOCKS
newdb->rwlocks = size;
#endif
if (tdb->flags & TDB_INTERNAL) {
tdb->map_size = size;
tdb->map_ptr = (char *)newdb;
memcpy(&tdb->header, newdb, sizeof(tdb->header));
/* Convert the `ondisk' version if asked. */
CONVERT(*newdb);
return 0;
}
lseek(tdb->fd, 0, SEEK_SET);
ftruncate(tdb->fd, 0);
/* This creates an endian-converted header, as if read from disk */
CONVERT(*newdb);
memcpy(&tdb->header, newdb, sizeof(tdb->header));
/* Don't endian-convert the magic food! */
memcpy(newdb->magic_food, TDB_MAGIC_FOOD, strlen(TDB_MAGIC_FOOD)+1);
if (write(tdb->fd, newdb, size) != size) ret = -1;
else ret = tdb_create_rwlocks(tdb->fd, hash_size);
free(newdb);
return ret;
}
/* Returns 0 on fail. On success, return offset of record, and fills
in rec */
static tdb_off tdb_find(TDB_CONTEXT *tdb, TDB_DATA key, u32 hash,
struct list_struct *r)
{
tdb_off rec_ptr;
/* read in the hash top */
if (ofs_read(tdb, TDB_HASH_TOP(hash), &rec_ptr) == -1) return 0;
/* keep looking until we find the right record */
while (rec_ptr) {
if (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) {
free(k);
return rec_ptr;
}
free(k);
}
rec_ptr = r->next;
}
return TDB_ERRCODE(TDB_ERR_NOEXIST, 0);
}
/* If they do lockkeys, check that this hash is one they locked */
static int tdb_keylocked(TDB_CONTEXT *tdb, u32 hash)
{
u32 i;
if (!tdb->lockedkeys) return 1;
for (i = 0; i < tdb->lockedkeys[0]; i++)
if (tdb->lockedkeys[i+1] == hash) return 1;
return TDB_ERRCODE(TDB_ERR_NOLOCK, 0);
}
/* As tdb_find, but if you succeed, keep the lock */
static tdb_off tdb_find_lock(TDB_CONTEXT *tdb, TDB_DATA key, int locktype,
struct list_struct *rec)
{
u32 hash, rec_ptr;
hash = tdb_hash(&key);
if (!tdb_keylocked(tdb, hash)) return 0;
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;
}
enum TDB_ERROR tdb_error(TDB_CONTEXT *tdb)
{
return tdb->ecode;
}
static struct tdb_errname {
enum TDB_ERROR ecode; const char *estring;
} emap[] = { {TDB_SUCCESS, "Success"},
{TDB_ERR_CORRUPT, "Corrupt database"},
{TDB_ERR_IO, "IO Error"},
{TDB_ERR_LOCK, "Locking error"},
{TDB_ERR_OOM, "Out of memory"},
{TDB_ERR_EXISTS, "Record exists"},
{TDB_ERR_NOLOCK, "Lock exists on other keys"},
{TDB_ERR_NOEXIST, "Record does not exist"} };
/* Error string for the last tdb error */
const char *tdb_errorstr(TDB_CONTEXT *tdb)
{
u32 i;
for (i = 0; i < sizeof(emap) / sizeof(struct tdb_errname); i++)
if (tdb->ecode == emap[i].ecode) return emap[i].estring;
return "Invalid error code";
}
/* 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(TDB_CONTEXT *tdb, TDB_DATA key, TDB_DATA dbuf)
{
struct list_struct rec;
tdb_off rec_ptr;
int ret = -1;
/* find entry */
if (!(rec_ptr = tdb_find_lock(tdb, key, F_WRLCK, &rec))) return -1;
/* must be long enough key, data and tailer */
if (rec.rec_len < key.dsize + dbuf.dsize + sizeof(tdb_off)) goto out;
if (tdb_write(tdb, rec_ptr + sizeof(rec) + rec.key_len,
dbuf.dptr, dbuf.dsize) == -1)
goto out;
if (dbuf.dsize != rec.data_len) {
/* update size */
rec.data_len = dbuf.dsize;
ret = rec_write(tdb, rec_ptr, &rec);
}
else ret = 0;
out:
tdb_unlock(tdb, BUCKET(rec.full_hash), F_WRLCK);
return ret;
}
/* find an entry in the database given a key */
TDB_DATA tdb_fetch(TDB_CONTEXT *tdb, TDB_DATA key)
{
tdb_off rec_ptr;
struct list_struct rec;
TDB_DATA ret;
/* find which hash bucket it is in */
if (!(rec_ptr = tdb_find_lock(tdb,key,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
*/
int tdb_exists(TDB_CONTEXT *tdb, TDB_DATA key)
{
struct list_struct rec;
if (tdb_find_lock(tdb, key, F_RDLCK, &rec) == 0) return 0;
tdb_unlock(tdb, BUCKET(rec.full_hash), F_RDLCK);
return 1;
}
/* record lock stops delete underneath */
static int lock_record(TDB_CONTEXT *tdb, tdb_off off)
{
return off ? tdb_brlock(tdb, off, F_RDLCK, F_SETLKW) : 0;
}
/* write locks override our own fcntl readlocks, so check it here */
static int write_lock_record(TDB_CONTEXT *tdb, tdb_off off)
{
struct tdb_traverse_lock *i;
for (i = &tdb->travlocks; i; i = i->next) if (i->off == off) return -1;
return tdb_brlock(tdb, off, F_WRLCK, F_SETLK);
}
static int write_unlock_record(TDB_CONTEXT *tdb, tdb_off off)
{
return tdb_brlock(tdb, off, F_UNLCK, F_SETLK);
}
/* fcntl locks don't stack: avoid unlocking someone else's */
static int unlock_record(TDB_CONTEXT *tdb, tdb_off off)
{
struct tdb_traverse_lock *i;
u32 count = 0;
if (off == 0) return 0;
for (i = &tdb->travlocks; i; i = i->next) if (i->off == off) count++;
return (count == 1 ? tdb_brlock(tdb, off, F_UNLCK, F_SETLKW) : 0);
}
/* actually delete an entry in the database given the offset */
static int do_delete(TDB_CONTEXT *tdb, tdb_off rec_ptr, struct list_struct*rec)
{
tdb_off last_ptr, i;
struct list_struct lastrec;
if (tdb->read_only) return -1;
if (write_lock_record(tdb, rec_ptr) == -1) {
/* Someone traversing here: mark it as dead */
rec->magic = TDB_DEAD_MAGIC;
return rec_write(tdb, rec_ptr, rec);
}
write_unlock_record(tdb, rec_ptr);
/* find previous record in hash chain */
if (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 (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 (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;
}
/* Uses traverse lock: 0 = finish, -1 = error, other = record offset */
static int tdb_next_lock(TDB_CONTEXT *tdb, struct tdb_traverse_lock *tlock,
struct list_struct *rec)
{
int want_next = (tlock->off != 0);
/* No traversal allows if you've called tdb_lockkeys() */
if (tdb->lockedkeys) return TDB_ERRCODE(TDB_ERR_NOLOCK, -1);
/* Lock each chain from the start one. */
for (; tlock->hash < tdb->header.hash_size; tlock->hash++) {
if (tdb_lock(tdb, tlock->hash, F_WRLCK) == -1) return -1;
/* No previous record? Start at top of chain. */
if (!tlock->off) {
if (ofs_read(tdb, TDB_HASH_TOP(tlock->hash),
&tlock->off) == -1)
goto fail;
} else {
/* Otherwise unlock the previous record. */
unlock_record(tdb, tlock->off);
}
if (want_next) {
/* We have offset of old record: grab next */
if (rec_read(tdb, tlock->off, rec) == -1) goto fail;
tlock->off = rec->next;
}
/* Iterate through chain */
while( tlock->off) {
tdb_off current;
if (rec_read(tdb, tlock->off, rec) == -1) goto fail;
if (!TDB_DEAD(rec)) {
/* Woohoo: we found one! */
lock_record(tdb, tlock->off);
return tlock->off;
}
/* Try to clean dead ones from old traverses */
current = tlock->off;
tlock->off = rec->next;
do_delete(tdb, current, rec);
}
tdb_unlock(tdb, tlock->hash, F_WRLCK);
want_next = 0;
}
/* We finished iteration without finding anything */
return TDB_ERRCODE(TDB_SUCCESS, 0);
fail:
tlock->off = 0;
tdb_unlock(tdb, tlock->hash, F_WRLCK);
return -1;
}
/* traverse the entire database - calling fn(tdb, key, data) on each element.
return -1 on error or the record count traversed
if fn is NULL then it is not called
a non-zero return value from fn() indicates that the traversal should stop
*/
int tdb_traverse(TDB_CONTEXT *tdb, tdb_traverse_func fn, void *state)
{
TDB_DATA key, dbuf;
struct list_struct rec;
struct tdb_traverse_lock tl = { NULL, 0, 0 };
int ret, count = 0;
/* This was in the initializaton, above, but the IRIX compiler
* did not like it. crh
*/
tl.next = tdb->travlocks.next;
/* fcntl locks don't stack: beware traverse inside traverse */
tdb->travlocks.next = &tl;
/* tdb_next_lock places locks on the record returned, and its chain */
while ((ret = tdb_next_lock(tdb, &tl, &rec)) > 0) {
count++;
/* now read the full record */
key.dptr = tdb_alloc_read(tdb, tl.off + sizeof(rec),
rec.key_len + rec.data_len);
if (!key.dptr) {
tdb_unlock(tdb, tl.hash, F_WRLCK);
unlock_record(tdb, tl.off);
tdb->travlocks.next = tl.next;
return -1;
}
key.dsize = rec.key_len;
dbuf.dptr = key.dptr + rec.key_len;
dbuf.dsize = rec.data_len;
/* Drop chain lock, call out */
tdb_unlock(tdb, tl.hash, F_WRLCK);
if (fn && fn(tdb, key, dbuf, state)) {
/* They want us to terminate traversal */
unlock_record(tdb, tl.off);
tdb->travlocks.next = tl.next;
free(key.dptr);
return count;
}
free(key.dptr);
}
tdb->travlocks.next = tl.next;
if (ret < 0) return -1;
else return count;
}
/* find the first entry in the database and return its key */
TDB_DATA tdb_firstkey(TDB_CONTEXT *tdb)
{
TDB_DATA key;
struct list_struct rec;
/* release any old lock */
unlock_record(tdb, tdb->travlocks.off);
tdb->travlocks.off = tdb->travlocks.hash = 0;
if (tdb_next_lock(tdb, &tdb->travlocks, &rec) <= 0) return tdb_null;
/* now read the key */
key.dsize = rec.key_len;
key.dptr =tdb_alloc_read(tdb,tdb->travlocks.off+sizeof(rec),key.dsize);
tdb_unlock(tdb, BUCKET(tdb->travlocks.hash), F_WRLCK);
return key;
}
/* find the next entry in the database, returning its key */
TDB_DATA tdb_nextkey(TDB_CONTEXT *tdb, TDB_DATA oldkey)
{
u32 oldhash;
TDB_DATA key = tdb_null;
struct list_struct rec;
char *k = NULL;
/* Is locked key the old key? If so, traverse will be reliable. */
if (tdb->travlocks.off) {
if (tdb_lock(tdb,tdb->travlocks.hash,F_WRLCK)) return tdb_null;
if (rec_read(tdb, tdb->travlocks.off, &rec) == -1
|| !(k = tdb_alloc_read(tdb,tdb->travlocks.off+sizeof(rec),
rec.key_len))
|| memcmp(k, oldkey.dptr, oldkey.dsize) != 0) {
/* No, it wasn't: unlock it and start from scratch */
unlock_record(tdb, tdb->travlocks.off);
tdb_unlock(tdb, tdb->travlocks.hash, F_WRLCK);
tdb->travlocks.off = 0;
}
if (k)
free(k);
}
if (!tdb->travlocks.off) {
/* No previous element: do normal find, and lock record */
tdb->travlocks.off = tdb_find_lock(tdb, oldkey, F_WRLCK, &rec);
if (!tdb->travlocks.off) return tdb_null;
tdb->travlocks.hash = BUCKET(rec.full_hash);
lock_record(tdb, tdb->travlocks.off);
}
oldhash = tdb->travlocks.hash;
/* Grab next record: locks chain and returned record,
unlocks old record */
if (tdb_next_lock(tdb, &tdb->travlocks, &rec) > 0) {
key.dsize = rec.key_len;
key.dptr = tdb_alloc_read(tdb, tdb->travlocks.off+sizeof(rec),
key.dsize);
/* Unlock the chain of this new record */
tdb_unlock(tdb, tdb->travlocks.hash, F_WRLCK);
}
/* Unlock the chain of old record */
tdb_unlock(tdb, BUCKET(oldhash), F_WRLCK);
return key;
}
/* delete an entry in the database given a key */
int tdb_delete(TDB_CONTEXT *tdb, TDB_DATA key)
{
tdb_off rec_ptr;
struct list_struct rec;
int ret;
if (!(rec_ptr = tdb_find_lock(tdb, key, F_WRLCK, &rec))) return -1;
ret = do_delete(tdb, rec_ptr, &rec);
tdb_unlock(tdb, BUCKET(rec.full_hash), F_WRLCK);
return ret;
}
/* store an element in the database, replacing any existing element
with the same key
return 0 on success, -1 on failure
*/
int tdb_store(TDB_CONTEXT *tdb, TDB_DATA key, TDB_DATA dbuf, int flag)
{
struct list_struct rec;
u32 hash;
tdb_off rec_ptr;
char *p = NULL;
int ret = 0;
/* find which hash bucket it is in */
hash = tdb_hash(&key);
if (!tdb_keylocked(tdb, hash)) return -1;
if (tdb_lock(tdb, BUCKET(hash), F_WRLCK) == -1) return -1;
/* check for it existing, on insert. */
if (flag == TDB_INSERT) {
if (tdb_exists(tdb, key)) {
tdb->ecode = TDB_ERR_EXISTS;
goto fail;
}
} else {
/* first try in-place update, on modify or replace. */
if (tdb_update(tdb, key, dbuf) == 0) goto out;
if (flag == TDB_MODIFY && tdb->ecode == TDB_ERR_NOEXIST)
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(tdb, key);
/* 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);
memcpy(p+key.dsize, dbuf.dptr, dbuf.dsize);
/* now we're into insert / modify / replace of a record which
* we know could not be optimised by an in-place store (for
* various reasons). */
if (!(rec_ptr = tdb_allocate(tdb, key.dsize + dbuf.dsize, &rec)))
goto fail;
/* Read hash top into next ptr */
if (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 (rec_write(tdb, rec_ptr, &rec) == -1
|| tdb_write(tdb, rec_ptr+sizeof(rec), p, key.dsize+dbuf.dsize)==-1
|| ofs_write(tdb, TDB_HASH_TOP(hash), &rec_ptr) == -1) {
fail:
/* Need to tdb_unallocate() here */
ret = -1;
}
out:
free(p);
tdb_unlock(tdb, BUCKET(hash), F_WRLCK);
return ret;
}
/* open the database, creating it if necessary
The open_flags and mode are passed straight to the open call on the
database file. A flags value of O_WRONLY is invalid. The hash size
is advisory, use zero for a default value.
return is NULL on error */
TDB_CONTEXT *tdb_open(char *name, int hash_size, int tdb_flags,
int open_flags, mode_t mode)
{
TDB_CONTEXT tdb, *ret, *i;
struct stat st;
int rev = 0, locked;
memset(&tdb, 0, sizeof(tdb));
tdb.fd = -1;
tdb.name = NULL;
tdb.map_ptr = NULL;
tdb.lockedkeys = NULL;
tdb.flags = tdb_flags;
if ((open_flags & O_ACCMODE) == O_WRONLY) goto fail;
if (hash_size == 0) hash_size = DEFAULT_HASH_SIZE;
if ((open_flags & O_ACCMODE) == O_RDONLY) {
tdb.read_only = 1;
/* read only databases don't do locking */
tdb.flags |= TDB_NOLOCK;
}
/* internal databases don't mmap or lock, and start off cleared */
if (tdb.flags & TDB_INTERNAL) {
tdb.flags |= (TDB_NOLOCK | TDB_NOMMAP);
tdb.flags &= ~TDB_CLEAR_IF_FIRST;
tdb_new_database(&tdb, hash_size);
goto internal;
}
if ((tdb.fd = open(name, open_flags, mode)) == -1) goto fail;
/* ensure there is only one process initialising at once */
tdb_brlock(&tdb, GLOBAL_LOCK, F_WRLCK, F_SETLKW);
/* we need to zero database if we are the only one with it open */
if ((locked = (tdb_brlock(&tdb, ACTIVE_LOCK, F_WRLCK, F_SETLK) == 0))
&& (tdb_flags & TDB_CLEAR_IF_FIRST)) {
open_flags |= O_CREAT;
ftruncate(tdb.fd, 0);
}
if (read(tdb.fd, &tdb.header, sizeof(tdb.header)) != sizeof(tdb.header)
|| strcmp(tdb.header.magic_food, TDB_MAGIC_FOOD) != 0
|| (tdb.header.version != TDB_VERSION
&& !(rev = (tdb.header.version==TDB_BYTEREV(TDB_VERSION))))) {
/* its not a valid database - possibly initialise it */
if (!(open_flags & O_CREAT)
|| tdb_new_database(&tdb, hash_size) == -1) goto fail;
rev = (tdb.flags & TDB_CONVERT);
}
if (!rev) tdb.flags &= ~TDB_CONVERT;
else {
tdb.flags |= TDB_CONVERT;
convert(&tdb.header, sizeof(tdb.header));
}
fstat(tdb.fd, &st);
/* Is it already in the open list? If so, fail. */
for (i = tdbs; i; i = i->next) {
if (i->device == st.st_dev && i->inode == st.st_ino) {
errno = EBUSY;
close(tdb.fd);
return NULL;
}
}
/* map the database and fill in the return structure */
tdb.name = (char *)strdup(name);
tdb.map_size = st.st_size;
tdb.device = st.st_dev;
tdb.inode = st.st_ino;
tdb.locked = calloc(tdb.header.hash_size+1, sizeof(tdb.locked[0]));
if (!tdb.locked) goto fail;
if (!(tdb.flags & TDB_NOMMAP))
tdb.map_ptr = tdb_mmap(st.st_size, tdb.read_only, tdb.fd);
if (locked) {
tdb_clear_spinlocks(&tdb);
tdb_brlock(&tdb, ACTIVE_LOCK, F_UNLCK, F_SETLK);
}
/* leave this lock in place to indicate it's in use */
tdb_brlock(&tdb, ACTIVE_LOCK, F_RDLCK, F_SETLKW);
internal:
if (!(ret = malloc(sizeof(tdb)))) goto fail;
*ret = tdb;
tdb_brlock(&tdb, GLOBAL_LOCK, F_UNLCK, F_SETLKW);
ret->next = tdbs;
tdbs = ret;
return ret;
fail:
if (tdb.name) free(tdb.name);
if (tdb.fd != -1) close(tdb.fd);
if (tdb.map_ptr) tdb_munmap(tdb.map_ptr, tdb.map_size);
return NULL;
}
/* close a database */
int tdb_close(TDB_CONTEXT *tdb)
{
TDB_CONTEXT **i;
int ret = 0;
if (tdb->map_ptr) {
if (tdb->flags & TDB_INTERNAL) free(tdb->map_ptr);
else tdb_munmap(tdb->map_ptr, tdb->map_size);
}
if (tdb->name) free(tdb->name);
if (tdb->fd != -1) {
ret = close(tdb->fd);
}
if (tdb->locked) free(tdb->locked);
if (tdb->lockedkeys) free(tdb->lockedkeys);
/* Remove from contexts list */
for (i = &tdbs; *i; i = &(*i)->next) {
if (*i == tdb) {
*i = tdb->next;
break;
}
}
memset(tdb, 0, sizeof(*tdb));
free(tdb);
return ret;
}
/* lock/unlock entire database */
int tdb_lockall(TDB_CONTEXT *tdb)
{
u32 i;
/* There are no locks on read-only dbs */
if (tdb->read_only) return TDB_ERRCODE(TDB_ERR_LOCK, -1);
if (tdb->lockedkeys) return TDB_ERRCODE(TDB_ERR_NOLOCK, -1);
for (i = 0; i < tdb->header.hash_size; i++)
if (tdb_lock(tdb, i, F_WRLCK))
break;
/* If error, release locks we have... */
if (i < tdb->header.hash_size) {
u32 j;
for ( j = 0; j < i; j++)
tdb_unlock(tdb, j, F_WRLCK);
return TDB_ERRCODE(TDB_ERR_NOLOCK, -1);
}
return 0;
}
void tdb_unlockall(TDB_CONTEXT *tdb)
{
u32 i;
for (i=0; i < tdb->header.hash_size; i++) tdb_unlock(tdb, i, F_WRLCK);
}
int tdb_lockkeys(TDB_CONTEXT *tdb, u32 number, TDB_DATA keys[])
{
u32 i, j, hash;
/* Can't lock more keys if already locked */
if (tdb->lockedkeys) return TDB_ERRCODE(TDB_ERR_NOLOCK, -1);
if (!(tdb->lockedkeys = malloc(sizeof(u32) * (number+1))))
return TDB_ERRCODE(TDB_ERR_OOM, -1);
/* First number in array is # keys */
tdb->lockedkeys[0] = number;
/* Insertion sort by bucket */
for (i = 0; i < number; i++) {
hash = tdb_hash(&keys[i]);
for (j = 0;
j < i && BUCKET(tdb->lockedkeys[j+1]) < BUCKET(hash);
j++);
memmove(&tdb->lockedkeys[j+2], &tdb->lockedkeys[j+1],
sizeof(u32) * (i-j));
tdb->lockedkeys[j+1] = hash;
}
/* Finally, lock in order */
for (i = 0; i < number; i++)
if (tdb_lock(tdb, i, F_WRLCK))
break;
/* If error, release locks we have... */
if (i < number) {
for ( j = 0; j < i; j++)
tdb_unlock(tdb, j, F_WRLCK);
free(tdb->lockedkeys);
tdb->lockedkeys = NULL;
return TDB_ERRCODE(TDB_ERR_NOLOCK, -1);
}
return 0;
}
/* Unlock the keys previously locked by tdb_lockkeys() */
void tdb_unlockkeys(TDB_CONTEXT *tdb)
{
u32 i;
for (i = 0; i < tdb->lockedkeys[0]; i++)
tdb_unlock(tdb, tdb->lockedkeys[i+1], F_WRLCK);
free(tdb->lockedkeys);
tdb->lockedkeys = NULL;
}
/* 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(TDB_CONTEXT *tdb, TDB_DATA key)
{
return tdb_lock(tdb, BUCKET(tdb_hash(&key)), F_WRLCK);
}
void tdb_chainunlock(TDB_CONTEXT *tdb, TDB_DATA key)
{
tdb_unlock(tdb, BUCKET(tdb_hash(&key)), F_WRLCK);
}
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