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;
  39
  40         key.dptr = (unsigned char *)&rec_ptr;
  41         key.dsize = sizeof(rec_ptr);
  42         return tdb_store(mem_tdb, key, tdb_null, TDB_INSERT);
  43 }
  44
  45 _PUBLIC_ int tdb_validate_freelist(struct tdb_context *tdb, int *pnum_entries)
  46 {
  47         struct tdb_context *mem_tdb = NULL;
  48         struct tdb_record rec;
  49         tdb_off_t rec_ptr, last_ptr;
  50         int ret = -1;
  51
  52         *pnum_entries = 0;
  53
  54         mem_tdb = tdb_open("flval", tdb->hash_size,
  55                                 TDB_INTERNAL, O_RDWR, 0600);
  56         if (!mem_tdb) {
  57                 return -1;
  58         }
  59
  60         if (tdb_lock(tdb, -1, F_WRLCK) == -1) {
  61                 tdb_close(mem_tdb);
  62                 return 0;
  63         }
  64
  65         last_ptr = FREELIST_TOP;
  66
  67         /* Store the FREELIST_TOP record. */
  68         if (seen_insert(mem_tdb, last_ptr) == -1) {
  69                 tdb->ecode = TDB_ERR_CORRUPT;
  70                 ret = -1;
  71                 goto fail;
  72         }
  73
  74         /* read in the freelist top */
  75         if (tdb_ofs_read(tdb, FREELIST_TOP, &rec_ptr) == -1) {
  76                 goto fail;
  77         }
  78
  79         while (rec_ptr) {
  80
  81                 /* If we can't store this record (we've seen it
  82                    before) then the free list has a loop and must
  83                    be corrupt. */
  84
  85                 if (seen_insert(mem_tdb, rec_ptr)) {
  86                         tdb->ecode = TDB_ERR_CORRUPT;
  87                         ret = -1;
  88                         goto fail;
  89                 }
  90
  91                 if (tdb_rec_free_read(tdb, rec_ptr, &rec) == -1) {
  92                         goto fail;
  93                 }
  94
  95                 /* move to the next record */
  96                 last_ptr = rec_ptr;
  97                 rec_ptr = rec.next;
  98                 *pnum_entries += 1;
  99         }
 100
 101         ret = 0;
 102
 103   fail:
 104
 105         tdb_close(mem_tdb);
 106         tdb_unlock(tdb, -1, F_WRLCK);
 107         return ret;
 108 }