lib/tdb/common/freelistcheck.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3
   4    trivial database library
   5
   6    Copyright (C) Jeremy Allison                    2006
   7
   8      ** NOTE! The following LGPL license applies to the tdb
   9      ** library. This does NOT imply that all of Samba is released
  10      ** under the LGPL
  11
  12    This library is free software; you can redistribute it and/or
  13    modify it under the terms of the GNU Lesser General Public
  14    License as published by the Free Software Foundation; either
  15    version 3 of the License, or (at your option) any later version.
  16
  17    This library is distributed in the hope that it will be useful,
  18    but WITHOUT ANY WARRANTY; without even the implied warranty of
  19    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  20    Lesser General Public License for more details.
  21
  22    You should have received a copy of the GNU Lesser General Public
  23    License along with this library; if not, see <http://www.gnu.org/licenses/>.
  24 */
  25
  26 #include "tdb_private.h"
  27
  28 /* Check the freelist is good and contains no loops.
  29    Very memory intensive - only do this as a consistency
  30    checker. Heh heh - uses an in memory tdb as the storage
  31    for the "seen" record list. For some reason this strikes
  32    me as extremely clever as I don't have to write another tree
  33    data structure implementation :-).
  34  */
  35
  36 static int seen_insert(struct tdb_context *mem_tdb, tdb_off_t rec_ptr)
  37 {
  38         TDB_DATA key, data;
  39
  40         memset(&data, '\0', sizeof(data));
  41         key.dptr = (unsigned char *)&rec_ptr;
  42         key.dsize = sizeof(rec_ptr);
  43         return tdb_store(mem_tdb, key, data, TDB_INSERT);
  44 }
  45
  46 _PUBLIC_ int tdb_validate_freelist(struct tdb_context *tdb, int *pnum_entries)
  47 {
  48         struct tdb_context *mem_tdb = NULL;
  49         struct tdb_record rec;
  50         tdb_off_t rec_ptr, last_ptr;
  51         int ret = -1;
  52
  53         *pnum_entries = 0;
  54
  55         mem_tdb = tdb_open("flval", tdb->hash_size,
  56                                 TDB_INTERNAL, O_RDWR, 0600);
  57         if (!mem_tdb) {
  58                 return -1;
  59         }
  60
  61         if (tdb_lock(tdb, -1, F_WRLCK) == -1) {
  62                 tdb_close(mem_tdb);
  63                 return 0;
  64         }
  65
  66         last_ptr = FREELIST_TOP;
  67
  68         /* Store the FREELIST_TOP record. */
  69         if (seen_insert(mem_tdb, last_ptr) == -1) {
  70                 tdb->ecode = TDB_ERR_CORRUPT;
  71                 ret = -1;
  72                 goto fail;
  73         }
  74
  75         /* read in the freelist top */
  76         if (tdb_ofs_read(tdb, FREELIST_TOP, &rec_ptr) == -1) {
  77                 goto fail;
  78         }
  79
  80         while (rec_ptr) {
  81
  82                 /* If we can't store this record (we've seen it
  83                    before) then the free list has a loop and must
  84                    be corrupt. */
  85
  86                 if (seen_insert(mem_tdb, rec_ptr)) {
  87                         tdb->ecode = TDB_ERR_CORRUPT;
  88                         ret = -1;
  89                         goto fail;
  90                 }
  91
  92                 if (tdb_rec_free_read(tdb, rec_ptr, &rec) == -1) {
  93                         goto fail;
  94                 }
  95
  96                 /* move to the next record */
  97                 last_ptr = rec_ptr;
  98                 rec_ptr = rec.next;
  99                 *pnum_entries += 1;
 100         }
 101
 102         ret = 0;
 103
 104   fail:
 105
 106         tdb_close(mem_tdb);
 107         tdb_unlock(tdb, -1, F_WRLCK);
 108         return ret;
 109 }