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 = { .log_fn = tdb_wrap_log };
  94
  95         result = talloc_pooled_object(mem_ctx, struct tdb_wrap_private,
  96                                       1, strlen(name)+1);
  97         if (result == NULL) {
  98                 return NULL;
  99         }
 100         /* Doesn't fail, see talloc_pooled_object */
 101         result->name = talloc_strdup(result, name);
 102
 103         result->tdb = tdb_open_ex(name, hash_size, tdb_flags,
 104                                   open_flags, mode, &lctx, NULL);
 105         if (result->tdb == NULL) {
 106                 goto fail;
 107         }
 108         talloc_set_destructor(result, tdb_wrap_private_destructor);
 109         DLIST_ADD(tdb_list, result);
 110         return result;
 111
 112 fail:
 113         TALLOC_FREE(result);
 114         return NULL;
 115 }
 116
 117 /*
 118   wrapped connection to a tdb database
 119   to close just talloc_free() the tdb_wrap pointer
 120  */
 121 struct tdb_wrap *tdb_wrap_open(TALLOC_CTX *mem_ctx,
 122                                const char *name, int hash_size, int tdb_flags,
 123                                int open_flags, mode_t mode)
 124 {
 125         struct tdb_wrap *result;
 126         struct tdb_wrap_private *w;
 127
 128         if (name == NULL) {
 129                 errno = EINVAL;
 130                 return NULL;
 131         }
 132
 133         result = talloc(mem_ctx, struct tdb_wrap);
 134         if (result == NULL) {
 135                 return NULL;
 136         }
 137
 138         for (w=tdb_list;w;w=w->next) {
 139                 if (strcmp(name, w->name) == 0) {
 140                         break;
 141                 }
 142         }
 143
 144         if (w == NULL) {
 145
 146                 if (tdb_flags & TDB_MUTEX_LOCKING) {
 147                         if (!tdb_runtime_check_for_robust_mutexes()) {
 148                                 tdb_flags &= ~TDB_MUTEX_LOCKING;
 149                         }
 150                 }
 151
 152                 w = tdb_wrap_private_open(result, name, hash_size, tdb_flags,
 153                                           open_flags, mode);
 154         } else {
 155                 /*
 156                  * Correctly use talloc_reference: The tdb will be
 157                  * closed when "w" is being freed. The caller never
 158                  * sees "w", so an incorrect use of talloc_free(w)
 159                  * instead of calling talloc_unlink is not possible.
 160                  * To avoid having to refcount ourselves, "w" will
 161                  * have multiple parents that hang off all the
 162                  * tdb_wrap's being returned from here. Those parents
 163                  * can be freed without problem.
 164                  */
 165                 if (talloc_reference(result, w) == NULL) {
 166                         goto fail;
 167                 }
 168         }
 169         if (w == NULL) {
 170                 goto fail;
 171         }
 172         result->tdb = w->tdb;
 173         return result;
 174 fail:
 175         TALLOC_FREE(result);
 176         return NULL;
 177 }