lib/util_tdb.c

説明を見る。

/* 
   Unix SMB/CIFS implementation.
   tdb utility functions
   Copyright (C) Andrew Tridgell   1992-1998
   Copyright (C) Rafal Szczesniak  2002
   
   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.
*/

#include "includes.h"
#undef malloc
#undef realloc
#undef calloc
#undef strdup

/* these are little tdb utility functions that are meant to make
   dealing with a tdb database a little less cumbersome in Samba */

static SIG_ATOMIC_T gotalarm;

/***************************************************************
 Signal function to tell us we timed out.
****************************************************************/

static void gotalarm_sig(void)
{
        gotalarm = 1;
}

/***************************************************************
 Make a TDB_DATA and keep the const warning in one place
****************************************************************/

TDB_DATA make_tdb_data(const char *dptr, size_t dsize)
{
        TDB_DATA ret;
        ret.dptr = CONST_DISCARD(char *, dptr);
        ret.dsize = dsize;
        return ret;
}

TDB_DATA string_tdb_data(const char *string)
{
        return make_tdb_data(string, strlen(string));
}

/****************************************************************************
 Lock a chain with timeout (in seconds).
****************************************************************************/

static int tdb_chainlock_with_timeout_internal( TDB_CONTEXT *tdb, TDB_DATA key, unsigned int timeout, int rw_type)
{
        /* Allow tdb_chainlock to be interrupted by an alarm. */
        int ret;
        gotalarm = 0;

        if (timeout) {
                CatchSignal(SIGALRM, SIGNAL_CAST gotalarm_sig);
                tdb_setalarm_sigptr(tdb, &gotalarm);
                alarm(timeout);
        }

        if (rw_type == F_RDLCK)
                ret = tdb_chainlock_read(tdb, key);
        else
                ret = tdb_chainlock(tdb, key);

        if (timeout) {
                alarm(0);
                tdb_setalarm_sigptr(tdb, NULL);
                CatchSignal(SIGALRM, SIGNAL_CAST SIG_IGN);
                if (gotalarm) {
                        DEBUG(0,("tdb_chainlock_with_timeout_internal: alarm (%u) timed out for key %s in tdb %s\n",
                                timeout, key.dptr, tdb_name(tdb)));
                        /* TODO: If we time out waiting for a lock, it might
                         * be nice to use F_GETLK to get the pid of the
                         * process currently holding the lock and print that
                         * as part of the debugging message. -- mbp */
                        return -1;
                }
        }

        return ret;
}

/****************************************************************************
 Write lock a chain. Return -1 if timeout or lock failed.
****************************************************************************/

int tdb_chainlock_with_timeout( TDB_CONTEXT *tdb, TDB_DATA key, unsigned int timeout)
{
        return tdb_chainlock_with_timeout_internal(tdb, key, timeout, F_WRLCK);
}

/****************************************************************************
 Lock a chain by string. Return -1 if timeout or lock failed.
****************************************************************************/

int tdb_lock_bystring(TDB_CONTEXT *tdb, const char *keyval)
{
        TDB_DATA key = make_tdb_data(keyval, strlen(keyval)+1);
        
        return tdb_chainlock(tdb, key);
}

int tdb_lock_bystring_with_timeout(TDB_CONTEXT *tdb, const char *keyval,
                                   int timeout)
{
        TDB_DATA key = make_tdb_data(keyval, strlen(keyval)+1);
        
        return tdb_chainlock_with_timeout(tdb, key, timeout);
}

/****************************************************************************
 Unlock a chain by string.
****************************************************************************/

void tdb_unlock_bystring(TDB_CONTEXT *tdb, const char *keyval)
{
        TDB_DATA key = make_tdb_data(keyval, strlen(keyval)+1);

        tdb_chainunlock(tdb, key);
}

/****************************************************************************
 Read lock a chain by string. Return -1 if timeout or lock failed.
****************************************************************************/

int tdb_read_lock_bystring_with_timeout(TDB_CONTEXT *tdb, const char *keyval, unsigned int timeout)
{
        TDB_DATA key = make_tdb_data(keyval, strlen(keyval)+1);
        
        return tdb_chainlock_with_timeout_internal(tdb, key, timeout, F_RDLCK);
}

/****************************************************************************
 Read unlock a chain by string.
****************************************************************************/

void tdb_read_unlock_bystring(TDB_CONTEXT *tdb, const char *keyval)
{
        TDB_DATA key = make_tdb_data(keyval, strlen(keyval)+1);
        
        tdb_chainunlock_read(tdb, key);
}


/****************************************************************************
 Fetch a int32 value by a arbitrary blob key, return -1 if not found.
 Output is int32 in native byte order.
****************************************************************************/

int32 tdb_fetch_int32_byblob(TDB_CONTEXT *tdb, const char *keyval, size_t len)
{
        TDB_DATA key = make_tdb_data(keyval, len);
        TDB_DATA data;
        int32 ret;

        data = tdb_fetch(tdb, key);
        if (!data.dptr || data.dsize != sizeof(int32)) {
                SAFE_FREE(data.dptr);
                return -1;
        }

        ret = IVAL(data.dptr,0);
        SAFE_FREE(data.dptr);
        return ret;
}

/****************************************************************************
 Fetch a int32 value by string key, return -1 if not found.
 Output is int32 in native byte order.
****************************************************************************/

int32 tdb_fetch_int32(TDB_CONTEXT *tdb, const char *keystr)
{
        return tdb_fetch_int32_byblob(tdb, keystr, strlen(keystr) + 1);
}

/****************************************************************************
 Store a int32 value by an arbitary blob key, return 0 on success, -1 on failure.
 Input is int32 in native byte order. Output in tdb is in little-endian.
****************************************************************************/

int tdb_store_int32_byblob(TDB_CONTEXT *tdb, const char *keystr, size_t len, int32 v)
{
        TDB_DATA key = make_tdb_data(keystr, len);
        TDB_DATA data;
        int32 v_store;

        SIVAL(&v_store,0,v);
        data.dptr = (char *)&v_store;
        data.dsize = sizeof(int32);

        return tdb_store(tdb, key, data, TDB_REPLACE);
}

/****************************************************************************
 Store a int32 value by string key, return 0 on success, -1 on failure.
 Input is int32 in native byte order. Output in tdb is in little-endian.
****************************************************************************/

int tdb_store_int32(TDB_CONTEXT *tdb, const char *keystr, int32 v)
{
        return tdb_store_int32_byblob(tdb, keystr, strlen(keystr) + 1, v);
}

/****************************************************************************
 Fetch a uint32 value by a arbitrary blob key, return -1 if not found.
 Output is uint32 in native byte order.
****************************************************************************/

BOOL tdb_fetch_uint32_byblob(TDB_CONTEXT *tdb, const char *keyval, size_t len, uint32 *value)
{
        TDB_DATA key = make_tdb_data(keyval, len);
        TDB_DATA data;

        data = tdb_fetch(tdb, key);
        if (!data.dptr || data.dsize != sizeof(uint32)) {
                SAFE_FREE(data.dptr);
                return False;
        }

        *value = IVAL(data.dptr,0);
        SAFE_FREE(data.dptr);
        return True;
}

/****************************************************************************
 Fetch a uint32 value by string key, return -1 if not found.
 Output is uint32 in native byte order.
****************************************************************************/

BOOL tdb_fetch_uint32(TDB_CONTEXT *tdb, const char *keystr, uint32 *value)
{
        return tdb_fetch_uint32_byblob(tdb, keystr, strlen(keystr) + 1, value);
}

/****************************************************************************
 Store a uint32 value by an arbitary blob key, return 0 on success, -1 on failure.
 Input is uint32 in native byte order. Output in tdb is in little-endian.
****************************************************************************/

BOOL tdb_store_uint32_byblob(TDB_CONTEXT *tdb, const char *keystr, size_t len, uint32 value)
{
        TDB_DATA key = make_tdb_data(keystr, len);
        TDB_DATA data;
        uint32 v_store;
        BOOL ret = True;

        SIVAL(&v_store, 0, value);
        data.dptr = (char *)&v_store;
        data.dsize = sizeof(uint32);

        if (tdb_store(tdb, key, data, TDB_REPLACE) == -1)
                ret = False;

        return ret;
}

/****************************************************************************
 Store a uint32 value by string key, return 0 on success, -1 on failure.
 Input is uint32 in native byte order. Output in tdb is in little-endian.
****************************************************************************/

BOOL tdb_store_uint32(TDB_CONTEXT *tdb, const char *keystr, uint32 value)
{
        return tdb_store_uint32_byblob(tdb, keystr, strlen(keystr) + 1, value);
}
/****************************************************************************
 Store a buffer by a null terminated string key.  Return 0 on success, -1
 on failure.
****************************************************************************/

int tdb_store_bystring(TDB_CONTEXT *tdb, const char *keystr, TDB_DATA data, int flags)
{
        TDB_DATA key = make_tdb_data(keystr, strlen(keystr)+1);
        
        return tdb_store(tdb, key, data, flags);
}

/****************************************************************************
 Fetch a buffer using a null terminated string key.  Don't forget to call
 free() on the result dptr.
****************************************************************************/

TDB_DATA tdb_fetch_bystring(TDB_CONTEXT *tdb, const char *keystr)
{
        TDB_DATA key = make_tdb_data(keystr, strlen(keystr)+1);

        return tdb_fetch(tdb, key);
}

/****************************************************************************
 Delete an entry using a null terminated string key. 
****************************************************************************/

int tdb_delete_bystring(TDB_CONTEXT *tdb, const char *keystr)
{
        TDB_DATA key = make_tdb_data(keystr, strlen(keystr)+1);

        return tdb_delete(tdb, key);
}

/****************************************************************************
 Atomic integer change. Returns old value. To create, set initial value in *oldval. 
****************************************************************************/

int32 tdb_change_int32_atomic(TDB_CONTEXT *tdb, const char *keystr, int32 *oldval, int32 change_val)
{
        int32 val;
        int32 ret = -1;

        if (tdb_lock_bystring(tdb, keystr) == -1)
                return -1;

        if ((val = tdb_fetch_int32(tdb, keystr)) == -1) {
                /* The lookup failed */
                if (tdb_error(tdb) != TDB_ERR_NOEXIST) {
                        /* but not because it didn't exist */
                        goto err_out;
                }
                
                /* Start with 'old' value */
                val = *oldval;

        } else {
                /* It worked, set return value (oldval) to tdb data */
                *oldval = val;
        }

        /* Increment value for storage and return next time */
        val += change_val;
                
        if (tdb_store_int32(tdb, keystr, val) == -1)
                goto err_out;

        ret = 0;

  err_out:

        tdb_unlock_bystring(tdb, keystr);
        return ret;
}

/****************************************************************************
 Atomic unsigned integer change. Returns old value. To create, set initial value in *oldval. 
****************************************************************************/

BOOL tdb_change_uint32_atomic(TDB_CONTEXT *tdb, const char *keystr, uint32 *oldval, uint32 change_val)
{
        uint32 val;
        BOOL ret = False;

        if (tdb_lock_bystring(tdb, keystr) == -1)
                return False;

        if (!tdb_fetch_uint32(tdb, keystr, &val)) {
                /* It failed */
                if (tdb_error(tdb) != TDB_ERR_NOEXIST) { 
                        /* and not because it didn't exist */
                        goto err_out;
                }

                /* Start with 'old' value */
                val = *oldval;

        } else {
                /* it worked, set return value (oldval) to tdb data */
                *oldval = val;

        }

        /* get a new value to store */
        val += change_val;
                
        if (!tdb_store_uint32(tdb, keystr, val))
                goto err_out;

        ret = True;

  err_out:

        tdb_unlock_bystring(tdb, keystr);
        return ret;
}

/****************************************************************************
 Useful pair of routines for packing/unpacking data consisting of
 integers and strings.
****************************************************************************/

size_t tdb_pack_va(char *buf, int bufsize, const char *fmt, va_list ap)
{
        uint8 bt;
        uint16 w;
        uint32 d;
        int i;
        void *p;
        int len;
        char *s;
        char c;
        char *buf0 = buf;
        const char *fmt0 = fmt;
        int bufsize0 = bufsize;

        while (*fmt) {
                switch ((c = *fmt++)) {
                case 'b': /* unsigned 8-bit integer */
                        len = 1;
                        bt = (uint8)va_arg(ap, int);
                        if (bufsize && bufsize >= len)
                                SSVAL(buf, 0, bt);
                        break;
                case 'w': /* unsigned 16-bit integer */
                        len = 2;
                        w = (uint16)va_arg(ap, int);
                        if (bufsize && bufsize >= len)
                                SSVAL(buf, 0, w);
                        break;
                case 'd': /* signed 32-bit integer (standard int in most systems) */
                        len = 4;
                        d = va_arg(ap, uint32);
                        if (bufsize && bufsize >= len)
                                SIVAL(buf, 0, d);
                        break;
                case 'p': /* pointer */
                        len = 4;
                        p = va_arg(ap, void *);
                        d = p?1:0;
                        if (bufsize && bufsize >= len)
                                SIVAL(buf, 0, d);
                        break;
                case 'P': /* null-terminated string */
                        s = va_arg(ap,char *);
                        w = strlen(s);
                        len = w + 1;
                        if (bufsize && bufsize >= len)
                                memcpy(buf, s, len);
                        break;
                case 'f': /* null-terminated string */
                        s = va_arg(ap,char *);
                        w = strlen(s);
                        len = w + 1;
                        if (bufsize && bufsize >= len)
                                memcpy(buf, s, len);
                        break;
                case 'B': /* fixed-length string */
                        i = va_arg(ap, int);
                        s = va_arg(ap, char *);
                        len = 4+i;
                        if (bufsize && bufsize >= len) {
                                SIVAL(buf, 0, i);
                                memcpy(buf+4, s, i);
                        }
                        break;
                default:
                        DEBUG(0,("Unknown tdb_pack format %c in %s\n", 
                                 c, fmt));
                        len = 0;
                        break;
                }

                buf += len;
                if (bufsize)
                        bufsize -= len;
                if (bufsize < 0)
                        bufsize = 0;
        }

        DEBUG(18,("tdb_pack_va(%s, %d) -> %d\n", 
                 fmt0, bufsize0, (int)PTR_DIFF(buf, buf0)));
        
        return PTR_DIFF(buf, buf0);
}

size_t tdb_pack(char *buf, int bufsize, const char *fmt, ...)
{
        va_list ap;
        size_t result;

        va_start(ap, fmt);
        result = tdb_pack_va(buf, bufsize, fmt, ap);
        va_end(ap);
        return result;
}

BOOL tdb_pack_append(TALLOC_CTX *mem_ctx, uint8 **buf, size_t *len,
                     const char *fmt, ...)
{
        va_list ap;
        size_t len1, len2;

        va_start(ap, fmt);
        len1 = tdb_pack_va(NULL, 0, fmt, ap);
        va_end(ap);

        if (mem_ctx != NULL) {
                *buf = TALLOC_REALLOC_ARRAY(mem_ctx, *buf, uint8,
                                            (*len) + len1);
        } else {
                *buf = SMB_REALLOC_ARRAY(*buf, uint8, (*len) + len1);
        }

        if (*buf == NULL) {
                return False;
        }

        va_start(ap, fmt);
        len2 = tdb_pack_va((char *)(*buf)+(*len), len1, fmt, ap);
        va_end(ap);

        if (len1 != len2) {
                return False;
        }

        *len += len2;

        return True;
}

/****************************************************************************
 Useful pair of routines for packing/unpacking data consisting of
 integers and strings.
****************************************************************************/

int tdb_unpack(char *buf, int bufsize, const char *fmt, ...)
{
        va_list ap;
        uint8 *bt;
        uint16 *w;
        uint32 *d;
        int len;
        int *i;
        void **p;
        char *s, **b;
        char c;
        char *buf0 = buf;
        const char *fmt0 = fmt;
        int bufsize0 = bufsize;

        va_start(ap, fmt);
        
        while (*fmt) {
                switch ((c=*fmt++)) {
                case 'b':
                        len = 1;
                        bt = va_arg(ap, uint8 *);
                        if (bufsize < len)
                                goto no_space;
                        *bt = SVAL(buf, 0);
                        break;
                case 'w':
                        len = 2;
                        w = va_arg(ap, uint16 *);
                        if (bufsize < len)
                                goto no_space;
                        *w = SVAL(buf, 0);
                        break;
                case 'd':
                        len = 4;
                        d = va_arg(ap, uint32 *);
                        if (bufsize < len)
                                goto no_space;
                        *d = IVAL(buf, 0);
                        break;
                case 'p':
                        len = 4;
                        p = va_arg(ap, void **);
                        if (bufsize < len)
                                goto no_space;
                        /* 
                         * This isn't a real pointer - only a token (1 or 0)
                         * to mark the fact a pointer is present.
                         */

                        *p = (void *)(IVAL(buf, 0) ? (void *)1 : NULL);
                        break;
                case 'P':
                        s = va_arg(ap,char *);
                        len = strlen(buf) + 1;
                        if (bufsize < len || len > sizeof(pstring))
                                goto no_space;
                        memcpy(s, buf, len);
                        break;
                case 'f':
                        s = va_arg(ap,char *);
                        len = strlen(buf) + 1;
                        if (bufsize < len || len > sizeof(fstring))
                                goto no_space;
                        memcpy(s, buf, len);
                        break;
                case 'B':
                        i = va_arg(ap, int *);
                        b = va_arg(ap, char **);
                        len = 4;
                        if (bufsize < len)
                                goto no_space;
                        *i = IVAL(buf, 0);
                        if (! *i) {
                                *b = NULL;
                                break;
                        }
                        len += *i;
                        if (bufsize < len)
                                goto no_space;
                        *b = (char *)SMB_MALLOC(*i);
                        if (! *b)
                                goto no_space;
                        memcpy(*b, buf+4, *i);
                        break;
                default:
                        DEBUG(0,("Unknown tdb_unpack format %c in %s\n", 
                                 c, fmt));

                        len = 0;
                        break;
                }

                buf += len;
                bufsize -= len;
        }

        va_end(ap);

        DEBUG(18,("tdb_unpack(%s, %d) -> %d\n", 
                 fmt0, bufsize0, (int)PTR_DIFF(buf, buf0)));

        return PTR_DIFF(buf, buf0);

 no_space:
        return -1;
}


/****************************************************************************
 Log tdb messages via DEBUG().
****************************************************************************/

static void tdb_log(TDB_CONTEXT *tdb, enum tdb_debug_level level, const char *format, ...)
{
        va_list ap;
        char *ptr = NULL;

        va_start(ap, format);
        vasprintf(&ptr, format, ap);
        va_end(ap);
        
        if (!ptr || !*ptr)
                return;

        DEBUG((int)level, ("tdb(%s): %s", tdb_name(tdb) ? tdb_name(tdb) : "unnamed", ptr));
        SAFE_FREE(ptr);
}

/****************************************************************************
 Like tdb_open() but also setup a logging function that redirects to
 the samba DEBUG() system.
****************************************************************************/

TDB_CONTEXT *tdb_open_log(const char *name, int hash_size, int tdb_flags,
                          int open_flags, mode_t mode)
{
        TDB_CONTEXT *tdb;
        struct tdb_logging_context log_ctx;

        if (!lp_use_mmap())
                tdb_flags |= TDB_NOMMAP;

        log_ctx.log_fn = tdb_log;
        log_ctx.log_private = NULL;

        tdb = tdb_open_ex(name, hash_size, tdb_flags, 
                          open_flags, mode, &log_ctx, NULL);
        if (!tdb)
                return NULL;

        return tdb;
}

/****************************************************************************
 Allow tdb_delete to be used as a tdb_traversal_fn.
****************************************************************************/

int tdb_traverse_delete_fn(TDB_CONTEXT *the_tdb, TDB_DATA key, TDB_DATA dbuf,
                     void *state)
{
    return tdb_delete(the_tdb, key);
}



/**
 * Search across the whole tdb for keys that match the given pattern
 * return the result as a list of keys
 *
 * @param tdb pointer to opened tdb file context
 * @param pattern searching pattern used by fnmatch(3) functions
 *
 * @return list of keys found by looking up with given pattern
 **/
TDB_LIST_NODE *tdb_search_keys(TDB_CONTEXT *tdb, const char* pattern)
{
        TDB_DATA key, next;
        TDB_LIST_NODE *list = NULL;
        TDB_LIST_NODE *rec = NULL;
        
        for (key = tdb_firstkey(tdb); key.dptr; key = next) {
                /* duplicate key string to ensure null-termination */
                char *key_str = (char*) SMB_STRNDUP(key.dptr, key.dsize);
                if (!key_str) {
                        DEBUG(0, ("tdb_search_keys: strndup() failed!\n"));
                        smb_panic("strndup failed!\n");
                }
                
                DEBUG(18, ("checking %s for match to pattern %s\n", key_str, pattern));
                
                next = tdb_nextkey(tdb, key);

                /* do the pattern checking */
                if (fnmatch(pattern, key_str, 0) == 0) {
                        rec = SMB_MALLOC_P(TDB_LIST_NODE);
                        ZERO_STRUCTP(rec);

                        rec->node_key = key;
        
                        DLIST_ADD_END(list, rec, TDB_LIST_NODE *);
                
                        DEBUG(18, ("checking %s matched pattern %s\n", key_str, pattern));
                } else {
                        free(key.dptr);
                }
                
                /* free duplicated key string */
                free(key_str);
        }
        
        return list;

}


/**
 * Free the list returned by tdb_search_keys
 *
 * @param node list of results found by tdb_search_keys
 **/
void tdb_search_list_free(TDB_LIST_NODE* node)
{
        TDB_LIST_NODE *next_node;
        
        while (node) {
                next_node = node->next;
                SAFE_FREE(node->node_key.dptr);
                SAFE_FREE(node);
                node = next_node;
        };
}

/****************************************************************************
 tdb_store, wrapped in a transaction. This way we make sure that a process
 that dies within writing does not leave a corrupt tdb behind.
****************************************************************************/

int tdb_trans_store(struct tdb_context *tdb, TDB_DATA key, TDB_DATA dbuf,
                    int flag)
{
        int res;

        if ((res = tdb_transaction_start(tdb)) != 0) {
                DEBUG(5, ("tdb_transaction_start failed\n"));
                return res;
        }

        if ((res = tdb_store(tdb, key, dbuf, flag)) != 0) {
                DEBUG(10, ("tdb_store failed\n"));
                if (tdb_transaction_cancel(tdb) != 0) {
                        smb_panic("Cancelling transaction failed\n");
                }
                return res;
        }

        if ((res = tdb_transaction_commit(tdb)) != 0) {
                DEBUG(5, ("tdb_transaction_commit failed\n"));
        }

        return res;
}

/****************************************************************************
 tdb_delete, wrapped in a transaction. This way we make sure that a process
 that dies within deleting does not leave a corrupt tdb behind.
****************************************************************************/

int tdb_trans_delete(struct tdb_context *tdb, TDB_DATA key)
{
        int res;

        if ((res = tdb_transaction_start(tdb)) != 0) {
                DEBUG(5, ("tdb_transaction_start failed\n"));
                return res;
        }

        if ((res = tdb_delete(tdb, key)) != 0) {
                DEBUG(10, ("tdb_delete failed\n"));
                if (tdb_transaction_cancel(tdb) != 0) {
                        smb_panic("Cancelling transaction failed\n");
                }
                return res;
        }

        if ((res = tdb_transaction_commit(tdb)) != 0) {
                DEBUG(5, ("tdb_transaction_commit failed\n"));
        }

        return res;
}

/*
 Log tdb messages via DEBUG().
*/
static void tdb_wrap_log(TDB_CONTEXT *tdb, enum tdb_debug_level level, 
                         const char *format, ...) PRINTF_ATTRIBUTE(3,4);

static void tdb_wrap_log(TDB_CONTEXT *tdb, enum tdb_debug_level level, 
                         const char *format, ...)
{
        va_list ap;
        char *ptr = NULL;
        int debuglevel = 0;

        va_start(ap, format);
        vasprintf(&ptr, format, ap);
        va_end(ap);
        
        switch (level) {
        case TDB_DEBUG_FATAL:
                debuglevel = 0;
                break;
        case TDB_DEBUG_ERROR:
                debuglevel = 1;
                break;
        case TDB_DEBUG_WARNING:
                debuglevel = 2;
                break;
        case TDB_DEBUG_TRACE:
                debuglevel = 5;
                break;
        default:
                debuglevel = 0;
        }               

        if (ptr != NULL) {
                const char *name = tdb_name(tdb);
                DEBUG(debuglevel, ("tdb(%s): %s", name ? name : "unnamed", ptr));
                free(ptr);
        }
}

static struct tdb_wrap *tdb_list;

/* destroy the last connection to a tdb */
static int tdb_wrap_destructor(struct tdb_wrap *w)
{
        tdb_close(w->tdb);
        DLIST_REMOVE(tdb_list, w);
        return 0;
}                                

/*
  wrapped connection to a tdb database
  to close just talloc_free() the tdb_wrap pointer
 */
struct tdb_wrap *tdb_wrap_open(TALLOC_CTX *mem_ctx,
                               const char *name, int hash_size, int tdb_flags,
                               int open_flags, mode_t mode)
{
        struct tdb_wrap *w;
        struct tdb_logging_context log_ctx;
        log_ctx.log_fn = tdb_wrap_log;

        for (w=tdb_list;w;w=w->next) {
                if (strcmp(name, w->name) == 0) {
                        /*
                         * Yes, talloc_reference is exactly what we want
                         * here. Otherwise we would have to implement our own
                         * reference counting.
                         */
                        return talloc_reference(mem_ctx, w);
                }
        }

        w = talloc(mem_ctx, struct tdb_wrap);
        if (w == NULL) {
                return NULL;
        }

        if (!(w->name = talloc_strdup(w, name))) {
                talloc_free(w);
                return NULL;
        }

        w->tdb = tdb_open_ex(name, hash_size, tdb_flags, 
                             open_flags, mode, &log_ctx, NULL);
        if (w->tdb == NULL) {
                talloc_free(w);
                return NULL;
        }

        talloc_set_destructor(w, tdb_wrap_destructor);

        DLIST_ADD(tdb_list, w);

        return w;
}

---