lib/util/tdb_wrap.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3    TDB wrap functions
   4
   5    Copyright (C) Andrew Tridgell 2004
   6    Copyright (C) Jelmer Vernooij <jelmer@samba.org> 2007
   7
   8    This program is free software; you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation; either version 3 of the License, or
  11    (at your option) any later version.
  12
  13    This program is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  20 */
  21
  22 #include "includes.h"
  23 #include <tdb.h>
  24 #include "lib/util/dlinklist.h"
  25 #include "lib/util/tdb_wrap.h"
  26 #include <tdb.h>
  27
  28 /*
  29  Log tdb messages via DEBUG().
  30 */
  31 static void tdb_wrap_log(TDB_CONTEXT *tdb, enum tdb_debug_level level,
  32                          const char *format, ...) PRINTF_ATTRIBUTE(3,4);
  33
  34 static void tdb_wrap_log(TDB_CONTEXT *tdb, enum tdb_debug_level level,
  35                          const char *format, ...)
  36 {
  37         va_list ap;
  38         char *ptr = NULL;
  39         int debuglevel = 0;
  40         int ret;
  41
  42         switch (level) {
  43         case TDB_DEBUG_FATAL:
  44                 debuglevel = 0;
  45                 break;
  46         case TDB_DEBUG_ERROR:
  47                 debuglevel = 1;
  48                 break;
  49         case TDB_DEBUG_WARNING:
  50                 debuglevel = 2;
  51                 break;
  52         case TDB_DEBUG_TRACE:
  53                 debuglevel = 5;
  54                 break;
  55         default:
  56                 debuglevel = 0;
  57         }
  58
  59         va_start(ap, format);
  60         ret = vasprintf(&ptr, format, ap);
  61         va_end(ap);
  62
  63         if (ret != -1) {
  64                 const char *name = tdb_name(tdb);
  65                 DEBUG(debuglevel, ("tdb(%s): %s", name ? name : "unnamed", ptr));
  66                 free(ptr);
  67         }
  68 }
  69
  70 struct tdb_wrap_private {
  71         struct tdb_context *tdb;
  72         const char *name;
  73         struct tdb_wrap_private *next, *prev;
  74 };
  75
  76 static struct tdb_wrap_private *tdb_list;
  77
  78 /* destroy the last connection to a tdb */
  79 static int tdb_wrap_private_destructor(struct tdb_wrap_private *w)
  80 {
  81         tdb_close(w->tdb);
  82         DLIST_REMOVE(tdb_list, w);
  83         return 0;
  84 }
  85
  86 static struct tdb_wrap_private *tdb_wrap_private_open(TALLOC_CTX *mem_ctx,
  87                                                       const char *name,
  88                                                       int hash_size,
  89                                                       int tdb_flags,
  90                                                       int open_flags,
  91                                                       mode_t mode)
  92 {
  93         struct tdb_wrap_private *result;
  94         struct tdb_logging_context log_ctx;
  95
  96         result = talloc(mem_ctx, struct tdb_wrap_private);
  97         if (result == NULL) {
  98                 return NULL;
  99         }
 100         result->name = talloc_strdup(result, name);
 101         if (result->name == NULL) {
 102                 goto fail;
 103         }
 104
 105         log_ctx.log_fn = tdb_wrap_log;
 106
 107 #if _SAMBA_BUILD_ == 3
 108         /* This #if _SAMBA_BUILD == 3 is very unfortunate, as it means
 109          * that in the top level build, these options are not
 110          * available for these databases.  However, having two
 111          * different tdb_wrap lists is a worse fate, so this will do
 112          * for now */
 113
 114         if (!lp_use_mmap()) {
 115                 tdb_flags |= TDB_NOMMAP;
 116         }
 117
 118         if ((hash_size == 0) && (name != NULL)) {
 119                 const char *base;
 120                 base = strrchr_m(name, '/');
 121
 122                 if (base != NULL) {
 123                         base += 1;
 124                 } else {
 125                         base = name;
 126                 }
 127                 hash_size = lp_parm_int(-1, "tdb_hashsize", base, 0);
 128         }
 129 #endif
 130
 131         result->tdb = tdb_open_ex(name, hash_size, tdb_flags,
 132                                   open_flags, mode, &log_ctx, NULL);
 133         if (result->tdb == NULL) {
 134                 goto fail;
 135         }
 136         talloc_set_destructor(result, tdb_wrap_private_destructor);
 137         DLIST_ADD(tdb_list, result);
 138         return result;
 139
 140 fail:
 141         TALLOC_FREE(result);
 142         return NULL;
 143 }
 144
 145 /*
 146   wrapped connection to a tdb database
 147   to close just talloc_free() the tdb_wrap pointer
 148  */
 149 struct tdb_wrap *tdb_wrap_open(TALLOC_CTX *mem_ctx,
 150                                const char *name, int hash_size, int tdb_flags,
 151                                int open_flags, mode_t mode)
 152 {
 153         struct tdb_wrap *result;
 154         struct tdb_wrap_private *w;
 155
 156         result = talloc(mem_ctx, struct tdb_wrap);
 157         if (result == NULL) {
 158                 return NULL;
 159         }
 160
 161         for (w=tdb_list;w;w=w->next) {
 162                 if (strcmp(name, w->name) == 0) {
 163                         break;
 164                 }
 165         }
 166
 167         if (w == NULL) {
 168                 w = tdb_wrap_private_open(result, name, hash_size, tdb_flags,
 169                                           open_flags, mode);
 170         } else {
 171                 /*
 172                  * Correctly use talloc_reference: The tdb will be
 173                  * closed when "w" is being freed. The caller never
 174                  * sees "w", so an incorrect use of talloc_free(w)
 175                  * instead of calling talloc_unlink is not possible.
 176                  * To avoid having to refcount ourselves, "w" will
 177                  * have multiple parents that hang off all the
 178                  * tdb_wrap's being returned from here. Those parents
 179                  * can be freed without problem.
 180                  */
 181                 if (talloc_reference(result, w) == NULL) {
 182                         goto fail;
 183                 }
 184         }
 185         if (w == NULL) {
 186                 goto fail;
 187         }
 188         result->tdb = w->tdb;
 189         return result;
 190 fail:
 191         TALLOC_FREE(result);
 192         return NULL;
 193 }
 194