release/src-rt-6.x.4708/router/samba-3.0.25b/source/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 2 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, write to the Free Software
  24    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  25 */
  26
  27 #include "tdb_private.h"
  28
  29 /* Check the freelist is good and contains no loops.
  30    Very memory intensive - only do this as a consistency
  31    checker. Heh heh - uses an in memory tdb as the storage
  32    for the "seen" record list. For some reason this strikes
  33    me as extremely clever as I don't have to write another tree
  34    data structure implementation :-).
  35  */
  36
  37 static int seen_insert(struct tdb_context *mem_tdb, tdb_off_t rec_ptr)
  38 {
  39         TDB_DATA key, data;
  40
  41         memset(&data, '\0', sizeof(data));
  42         key.dptr = (char *)&rec_ptr;
  43         key.dsize = sizeof(rec_ptr);
  44         return tdb_store(mem_tdb, key, data, TDB_INSERT);
  45 }
  46
  47 int tdb_validate_freelist(struct tdb_context *tdb, int *pnum_entries)
  48 {
  49         struct tdb_context *mem_tdb = NULL;
  50         struct list_struct rec;
  51         tdb_off_t rec_ptr, last_ptr;
  52         int ret = -1;
  53
  54         *pnum_entries = 0;
  55
  56         mem_tdb = tdb_open("flval", tdb->header.hash_size,
  57                                 TDB_INTERNAL, O_RDWR, 0600);
  58         if (!mem_tdb) {
  59                 return -1;
  60         }
  61
  62         if (tdb_lock(tdb, -1, F_WRLCK) == -1) {
  63                 tdb_close(mem_tdb);
  64                 return 0;
  65         }
  66
  67         last_ptr = FREELIST_TOP;
  68
  69         /* Store the FREELIST_TOP record. */
  70         if (seen_insert(mem_tdb, last_ptr) == -1) {
  71                 ret = TDB_ERRCODE(TDB_ERR_CORRUPT, -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                         ret = TDB_ERRCODE(TDB_ERR_CORRUPT, -1);
  88                         goto fail;
  89                 }
  90
  91                 if (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 }