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 "system/filesys.h"
  24 #include "lib/util/dlinklist.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 = { .log_fn = tdb_wrap_log };
  95
  96         result = talloc_pooled_object(mem_ctx, struct tdb_wrap_private,
  97                                       1, strlen(name)+1);
  98         if (result == NULL) {
  99                 return NULL;
 100         }
 101         /* Doesn't fail, see talloc_pooled_object */
 102         result->name = talloc_strdup(result, name);
 103
 104         /*
 105          * TDB files don't make sense after execve()
 106          */
 107         open_flags |= O_CLOEXEC;
 108
 109         result->tdb = tdb_open_ex(name, hash_size, tdb_flags,
 110                                   open_flags, mode, &lctx, NULL);
 111         if (result->tdb == NULL) {
 112                 goto fail;
 113         }
 114         talloc_set_destructor(result, tdb_wrap_private_destructor);
 115         DLIST_ADD(tdb_list, result);
 116         return result;
 117
 118 fail:
 119         TALLOC_FREE(result);
 120         return NULL;
 121 }
 122
 123 /*
 124   wrapped connection to a tdb database
 125   to close just talloc_free() the tdb_wrap pointer
 126  */
 127 struct tdb_wrap *tdb_wrap_open(TALLOC_CTX *mem_ctx,
 128                                const char *name, int hash_size, int tdb_flags,
 129                                int open_flags, mode_t mode)
 130 {
 131         struct tdb_wrap *result;
 132         struct tdb_wrap_private *w;
 133
 134         if (name == NULL) {
 135                 errno = EINVAL;
 136                 return NULL;
 137         }
 138
 139         result = talloc(mem_ctx, struct tdb_wrap);
 140         if (result == NULL) {
 141                 return NULL;
 142         }
 143
 144         for (w=tdb_list;w;w=w->next) {
 145                 if (strcmp(name, w->name) == 0) {
 146                         break;
 147                 }
 148         }
 149
 150         if (w == NULL) {
 151
 152                 if (tdb_flags & TDB_MUTEX_LOCKING) {
 153                         if (!tdb_runtime_check_for_robust_mutexes()) {
 154                                 tdb_flags &= ~TDB_MUTEX_LOCKING;
 155                         }
 156                 }
 157
 158                 w = tdb_wrap_private_open(result, name, hash_size, tdb_flags,
 159                                           open_flags, mode);
 160         } else {
 161                 /*
 162                  * Correctly use talloc_reference: The tdb will be
 163                  * closed when "w" is being freed. The caller never
 164                  * sees "w", so an incorrect use of talloc_free(w)
 165                  * instead of calling talloc_unlink is not possible.
 166                  * To avoid having to refcount ourselves, "w" will
 167                  * have multiple parents that hang off all the
 168                  * tdb_wrap's being returned from here. Those parents
 169                  * can be freed without problem.
 170                  */
 171                 if (talloc_reference(result, w) == NULL) {
 172                         goto fail;
 173                 }
 174         }
 175         if (w == NULL) {
 176                 goto fail;
 177         }
 178         result->tdb = w->tdb;
 179         return result;
 180 fail:
 181         TALLOC_FREE(result);
 182         return NULL;
 183 }