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 "ccan/str/str.h"
  25 #include "lib/util/debug.h"
  26 #include "tdb_wrap.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 lctx;
  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         lctx.log_fn = tdb_wrap_log;
 106         lctx.log_private = NULL;
 107
 108         result->tdb = tdb_open_ex(name, hash_size, tdb_flags,
 109                                   open_flags, mode, &lctx, NULL);
 110         if (result->tdb == NULL) {
 111                 goto fail;
 112         }
 113         talloc_set_destructor(result, tdb_wrap_private_destructor);
 114         DLIST_ADD(tdb_list, result);
 115         return result;
 116
 117 fail:
 118         TALLOC_FREE(result);
 119         return NULL;
 120 }
 121
 122 /*
 123   wrapped connection to a tdb database
 124   to close just talloc_free() the tdb_wrap pointer
 125  */
 126 struct tdb_wrap *tdb_wrap_open(TALLOC_CTX *mem_ctx,
 127                                const char *name, int hash_size, int tdb_flags,
 128                                int open_flags, mode_t mode)
 129 {
 130         struct tdb_wrap *result;
 131         struct tdb_wrap_private *w;
 132
 133         /* If they specify a .ntdb extension, but the code hasn't been
 134          * converted, we want to complain. */
 135         if (name && strends(name, ".ntdb")) {
 136                 DEBUG(2, ("tdb(%s): This code does not yet understand ntdb.  Please report.\n", name));
 137                 return NULL;
 138         }
 139
 140         result = talloc(mem_ctx, struct tdb_wrap);
 141         if (result == NULL) {
 142                 return NULL;
 143         }
 144
 145         for (w=tdb_list;w;w=w->next) {
 146                 if (strcmp(name, w->name) == 0) {
 147                         break;
 148                 }
 149         }
 150
 151         if (w == NULL) {
 152
 153                 if (tdb_flags & TDB_MUTEX_LOCKING) {
 154                         if (!tdb_runtime_check_for_robust_mutexes()) {
 155                                 tdb_flags &= ~TDB_MUTEX_LOCKING;
 156                         }
 157                 }
 158
 159                 w = tdb_wrap_private_open(result, name, hash_size, tdb_flags,
 160                                           open_flags, mode);
 161         } else {
 162                 /*
 163                  * Correctly use talloc_reference: The tdb will be
 164                  * closed when "w" is being freed. The caller never
 165                  * sees "w", so an incorrect use of talloc_free(w)
 166                  * instead of calling talloc_unlink is not possible.
 167                  * To avoid having to refcount ourselves, "w" will
 168                  * have multiple parents that hang off all the
 169                  * tdb_wrap's being returned from here. Those parents
 170                  * can be freed without problem.
 171                  */
 172                 if (talloc_reference(result, w) == NULL) {
 173                         goto fail;
 174                 }
 175         }
 176         if (w == NULL) {
 177                 goto fail;
 178         }
 179         result->tdb = w->tdb;
 180         return result;
 181 fail:
 182         TALLOC_FREE(result);
 183         return NULL;
 184 }