lib/ldb/ldb_tdb/ldb_tdb_wrap.c

   1 /*
   2    ldb database library
   3
   4    Copyright (C) Andrew Tridgell  2005
   5
   6      ** NOTE! The following LGPL license applies to the ldb
   7      ** library. This does NOT imply that all of Samba is released
   8      ** under the LGPL
   9
  10    This library is free software; you can redistribute it and/or
  11    modify it under the terms of the GNU Lesser General Public
  12    License as published by the Free Software Foundation; either
  13    version 3 of the License, or (at your option) any later version.
  14
  15    This library is distributed in the hope that it will be useful,
  16    but WITHOUT ANY WARRANTY; without even the implied warranty of
  17    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  18    Lesser General Public License for more details.
  19
  20    You should have received a copy of the GNU Lesser General Public
  21    License along with this library; if not, see <http://www.gnu.org/licenses/>.
  22 */
  23
  24 #include "ldb_tdb.h"
  25 #include "dlinklist.h"
  26
  27 static void ltdb_log_fn(struct tdb_context *tdb, enum tdb_debug_level level, const char *fmt, ...) PRINTF_ATTRIBUTE(3, 4);
  28 static void ltdb_log_fn(struct tdb_context *tdb, enum tdb_debug_level level, const char *fmt, ...)
  29 {
  30         va_list ap;
  31         const char *name = tdb_name(tdb);
  32         struct ldb_context *ldb = talloc_get_type(tdb_get_logging_private(tdb), struct ldb_context);
  33         enum ldb_debug_level ldb_level;
  34         char *message;
  35
  36         if (ldb == NULL)
  37                 return;
  38
  39         va_start(ap, fmt);
  40         message = talloc_vasprintf(ldb, fmt, ap);
  41         va_end(ap);
  42
  43         switch (level) {
  44         case TDB_DEBUG_FATAL:
  45                 ldb_level = LDB_DEBUG_FATAL;
  46                 break;
  47         case TDB_DEBUG_ERROR:
  48                 ldb_level = LDB_DEBUG_ERROR;
  49                 break;
  50         case TDB_DEBUG_WARNING:
  51                 ldb_level = LDB_DEBUG_WARNING;
  52                 break;
  53         case TDB_DEBUG_TRACE:
  54                 ldb_level = LDB_DEBUG_TRACE;
  55                 break;
  56         default:
  57                 ldb_level = LDB_DEBUG_FATAL;
  58         }
  59
  60         ldb_debug(ldb, ldb_level, "ltdb: tdb(%s): %s", name, message);
  61         talloc_free(message);
  62 }
  63
  64 /*
  65   the purpose of this code is to work around the braindead posix locking
  66   rules, to allow us to have a ldb open more than once while allowing
  67   locking to work
  68
  69   TDB2 handles multiple opens, so we don't have this problem there.
  70 */
  71
  72 struct ltdb_wrap {
  73         struct ltdb_wrap *next, *prev;
  74         struct tdb_context *tdb;
  75         dev_t device;
  76         ino_t inode;
  77         pid_t pid;
  78 };
  79
  80 static struct ltdb_wrap *tdb_list;
  81
  82 /* destroy the last connection to a tdb */
  83 static int ltdb_wrap_destructor(struct ltdb_wrap *w)
  84 {
  85         tdb_close(w->tdb);
  86         DLIST_REMOVE(tdb_list, w);
  87         return 0;
  88 }
  89
  90 /*
  91   wrapped connection to a tdb database. The caller should _not_ free
  92   this as it is not a talloc structure (as tdb does not use talloc
  93   yet). It will auto-close when the caller frees the mem_ctx that is
  94   passed to this call
  95  */
  96 struct tdb_context *ltdb_wrap_open(TALLOC_CTX *mem_ctx,
  97                                    const char *path, int hash_size,
  98                                    int tdb_flags,
  99                                    int open_flags, mode_t mode,
 100                                    struct ldb_context *ldb)
 101 {
 102         struct ltdb_wrap *w;
 103         struct tdb_logging_context lctx;
 104         struct stat st;
 105
 106         if (stat(path, &st) == 0) {
 107                 for (w=tdb_list;w;w=w->next) {
 108                         if (st.st_dev == w->device && st.st_ino == w->inode) {
 109                                 pid_t pid = getpid();
 110                                 int ret;
 111                                 if (!talloc_reference(mem_ctx, w)) {
 112                                         return NULL;
 113                                 }
 114                                 if (w->pid != pid) {
 115                                         ret = tdb_reopen(w->tdb);
 116                                         if (ret != 0) {
 117                                                 /*
 118                                                  * Avoid use-after-free:
 119                                                  * on fail the TDB
 120                                                  * is closed!
 121                                                  */
 122                                                 DLIST_REMOVE(tdb_list,
 123                                                              w);
 124                                                 return NULL;
 125                                         }
 126                                         w->pid = pid;
 127                                 }
 128                                 return w->tdb;
 129                         }
 130                 }
 131         }
 132
 133         w = talloc(mem_ctx, struct ltdb_wrap);
 134         if (w == NULL) {
 135                 return NULL;
 136         }
 137
 138         lctx.log_fn = ltdb_log_fn;
 139         lctx.log_private = ldb;
 140         w->tdb = tdb_open_ex(path, hash_size, tdb_flags, open_flags, mode,
 141                              &lctx, NULL);
 142         if (w->tdb == NULL) {
 143                 talloc_free(w);
 144                 return NULL;
 145         }
 146
 147         if (fstat(tdb_fd(w->tdb), &st) != 0) {
 148                 tdb_close(w->tdb);
 149                 talloc_free(w);
 150                 return NULL;
 151         }
 152
 153         w->device = st.st_dev;
 154         w->inode  = st.st_ino;
 155         w->pid    = getpid();
 156
 157         talloc_set_destructor(w, ltdb_wrap_destructor);
 158
 159         DLIST_ADD(tdb_list, w);
 160
 161         return w->tdb;
 162 }