source: vendor/3.6.0/lib/util/tdb_wrap.c

/* 
   Unix SMB/CIFS implementation.
   TDB wrap functions

   Copyright (C) Andrew Tridgell 2004
   Copyright (C) Jelmer Vernooij <jelmer@samba.org> 2007
   
   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 3 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, see <http://www.gnu.org/licenses/>.
*/

#include "includes.h"
#include <tdb.h>
#include "lib/util/dlinklist.h"
#include "lib/util/tdb_wrap.h"
#include <tdb.h>

/*
 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;
        int ret;

        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;
        }               

        va_start(ap, format);
        ret = vasprintf(&ptr, format, ap);
        va_end(ap);

        if (ret != -1) {
                const char *name = tdb_name(tdb);
                DEBUG(debuglevel, ("tdb(%s): %s", name ? name : "unnamed", ptr));
                free(ptr);
        }
}

struct tdb_wrap_private {
        struct tdb_context *tdb;
        const char *name;
        struct tdb_wrap_private *next, *prev;
};

static struct tdb_wrap_private *tdb_list;

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

static struct tdb_wrap_private *tdb_wrap_private_open(TALLOC_CTX *mem_ctx,
                                                      const char *name,
                                                      int hash_size,
                                                      int tdb_flags,
                                                      int open_flags,
                                                      mode_t mode)
{
        struct tdb_wrap_private *result;
        struct tdb_logging_context log_ctx;

        result = talloc(mem_ctx, struct tdb_wrap_private);
        if (result == NULL) {
                return NULL;
        }
        result->name = talloc_strdup(result, name);
        if (result->name == NULL) {
                goto fail;
        }

        log_ctx.log_fn = tdb_wrap_log;

#if _SAMBA_BUILD_ == 3  
        /* This #if _SAMBA_BUILD == 3 is very unfortunate, as it means
         * that in the top level build, these options are not
         * available for these databases.  However, having two
         * different tdb_wrap lists is a worse fate, so this will do
         * for now */

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

        if ((hash_size == 0) && (name != NULL)) {
                const char *base;
                base = strrchr_m(name, '/');

                if (base != NULL) {
                        base += 1;
                } else {
                        base = name;
                }
                hash_size = lp_parm_int(-1, "tdb_hashsize", base, 0);
        }
#endif

        result->tdb = tdb_open_ex(name, hash_size, tdb_flags,
                                  open_flags, mode, &log_ctx, NULL);
        if (result->tdb == NULL) {
                goto fail;
        }
        talloc_set_destructor(result, tdb_wrap_private_destructor);
        DLIST_ADD(tdb_list, result);
        return result;

fail:
        TALLOC_FREE(result);
        return NULL;
}

/*
  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 *result;
        struct tdb_wrap_private *w;

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

        for (w=tdb_list;w;w=w->next) {
                if (strcmp(name, w->name) == 0) {
                        break;
                }
        }

        if (w == NULL) {
                w = tdb_wrap_private_open(result, name, hash_size, tdb_flags,
                                          open_flags, mode);
        } else {
                /*
                 * Correctly use talloc_reference: The tdb will be
                 * closed when "w" is being freed. The caller never
                 * sees "w", so an incorrect use of talloc_free(w)
                 * instead of calling talloc_unlink is not possible.
                 * To avoid having to refcount ourselves, "w" will
                 * have multiple parents that hang off all the
                 * tdb_wrap's being returned from here. Those parents
                 * can be freed without problem.
                 */
                if (talloc_reference(result, w) == NULL) {
                        goto fail;
                }
        }
        if (w == NULL) {
                goto fail;
        }
        result->tdb = w->tdb;
        return result;
fail:
        TALLOC_FREE(result);
        return NULL;
}