lib/tdb_wrap/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 "replace.h"
  23 #include "lib/util/dlinklist.h"
  24 #include "lib/util/debug.h"
  25 #include "tdb_wrap.h"
  26
  27 /*
  28  Log tdb messages via DEBUG().
  29 */
  30 static void tdb_wrap_log(TDB_CONTEXT *tdb, enum tdb_debug_level level,
  31                          const char *format, ...) PRINTF_ATTRIBUTE(3,4);
  32
  33 static void tdb_wrap_log(TDB_CONTEXT *tdb, enum tdb_debug_level level,
  34                          const char *format, ...)
  35 {
  36         va_list ap;
  37         char *ptr = NULL;
  38         int debuglevel = 0;
  39         int ret;
  40
  41         switch (level) {
  42         case TDB_DEBUG_FATAL:
  43                 debuglevel = 0;
  44                 break;
  45         case TDB_DEBUG_ERROR:
  46                 debuglevel = 1;
  47                 break;
  48         case TDB_DEBUG_WARNING:
  49                 debuglevel = 2;
  50                 break;
  51         case TDB_DEBUG_TRACE:
  52                 debuglevel = 5;
  53                 break;
  54         default:
  55                 debuglevel = 0;
  56         }
  57
  58         va_start(ap, format);
  59         ret = vasprintf(&ptr, format, ap);
  60         va_end(ap);
  61
  62         if (ret != -1) {
  63                 const char *name = tdb_name(tdb);
  64                 DEBUG(debuglevel, ("tdb(%s): %s", name ? name : "unnamed", ptr));
  65                 free(ptr);
  66         }
  67 }
  68
  69 struct tdb_wrap_private {
  70         struct tdb_context *tdb;
  71         const char *name;
  72         struct tdb_wrap_private *next, *prev;
  73 };
  74
  75 static struct tdb_wrap_private *tdb_list;
  76
  77 /* destroy the last connection to a tdb */
  78 static int tdb_wrap_private_destructor(struct tdb_wrap_private *w)
  79 {
  80         tdb_close(w->tdb);
  81         DLIST_REMOVE(tdb_list, w);
  82         return 0;
  83 }
  84
  85 static struct tdb_wrap_private *tdb_wrap_private_open(TALLOC_CTX *mem_ctx,
  86                                                       const char *name,
  87                                                       int hash_size,
  88                                                       int tdb_flags,
  89                                                       int open_flags,
  90                                                       mode_t mode)
  91 {
  92         struct tdb_wrap_private *result;
  93         struct tdb_logging_context lctx;
  94
  95         result = talloc(mem_ctx, struct tdb_wrap_private);
  96         if (result == NULL) {
  97                 return NULL;
  98         }
  99         result->name = talloc_strdup(result, name);
 100         if (result->name == NULL) {
 101                 goto fail;
 102         }
 103
 104         lctx.log_fn = tdb_wrap_log;
 105         lctx.log_private = NULL;
 106
 107         result->tdb = tdb_open_ex(name, hash_size, tdb_flags,
 108                                   open_flags, mode, &lctx, NULL);
 109         if (result->tdb == NULL) {
 110                 goto fail;
 111         }
 112         talloc_set_destructor(result, tdb_wrap_private_destructor);
 113         DLIST_ADD(tdb_list, result);
 114         return result;
 115
 116 fail:
 117         TALLOC_FREE(result);
 118         return NULL;
 119 }
 120
 121 /*
 122   wrapped connection to a tdb database
 123   to close just talloc_free() the tdb_wrap pointer
 124  */
 125 struct tdb_wrap *tdb_wrap_open(TALLOC_CTX *mem_ctx,
 126                                const char *name, int hash_size, int tdb_flags,
 127                                int open_flags, mode_t mode)
 128 {
 129         struct tdb_wrap *result;
 130         struct tdb_wrap_private *w;
 131
 132         if (name == NULL) {
 133                 errno = EINVAL;
 134                 return NULL;
 135         }
 136
 137         result = talloc(mem_ctx, struct tdb_wrap);
 138         if (result == NULL) {
 139                 return NULL;
 140         }
 141
 142         for (w=tdb_list;w;w=w->next) {
 143                 if (strcmp(name, w->name) == 0) {
 144                         break;
 145                 }
 146         }
 147
 148         if (w == NULL) {
 149
 150                 if (tdb_flags & TDB_MUTEX_LOCKING) {
 151                         if (!tdb_runtime_check_for_robust_mutexes()) {
 152                                 tdb_flags &= ~TDB_MUTEX_LOCKING;
 153                         }
 154                 }
 155
 156                 w = tdb_wrap_private_open(result, name, hash_size, tdb_flags,
 157                                           open_flags, mode);
 158         } else {
 159                 /*
 160                  * Correctly use talloc_reference: The tdb will be
 161                  * closed when "w" is being freed. The caller never
 162                  * sees "w", so an incorrect use of talloc_free(w)
 163                  * instead of calling talloc_unlink is not possible.
 164                  * To avoid having to refcount ourselves, "w" will
 165                  * have multiple parents that hang off all the
 166                  * tdb_wrap's being returned from here. Those parents
 167                  * can be freed without problem.
 168                  */
 169                 if (talloc_reference(result, w) == NULL) {
 170                         goto fail;
 171                 }
 172         }
 173         if (w == NULL) {
 174                 goto fail;
 175         }
 176         result->tdb = w->tdb;
 177         return result;
 178 fail:
 179         TALLOC_FREE(result);
 180         return NULL;
 181 }