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Overview
Comment:Fix a potential database corruption following DROP TABLE when the pending byte page corresponds to a ptrmap page. This situation cannot happen in a real deployment - but it still needs to be fixed. (CVS 6897)
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SHA1: 6242db39f7f4ead5017bf684139d1f8312799f81
User & Date: drh 2009-07-15 18:15:23.000
Context
2009-07-16
12:41
Remove an unused variable from sqlite3ExprListDup(). Ticket #3973. (CVS 6898) (check-in: 17c05aefd6 user: drh tags: trunk)
2009-07-15
18:15
Fix a potential database corruption following DROP TABLE when the pending byte page corresponds to a ptrmap page. This situation cannot happen in a real deployment - but it still needs to be fixed. (CVS 6897) (check-in: 6242db39f7 user: drh tags: trunk)
17:25
Simplifications to btree.c in support of structural testing. Renamed the "skip" field of the BtCursor object to "skipNext" to make it easier to search for places where it is used. (CVS 6896) (check-in: d3897235d7 user: drh tags: trunk)
Changes
Unified Diff Ignore Whitespace Patch
Changes to src/btree.c. 
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/*
** 2004 April 6
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** $Id: btree.c,v 1.689 2009/07/15 17:25:46 drh Exp $
**
** This file implements a external (disk-based) database using BTrees.
** See the header comment on "btreeInt.h" for additional information.
** Including a description of file format and an overview of operation.
*/
#include "btreeInt.h"













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/*
** 2004 April 6
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** $Id: btree.c,v 1.690 2009/07/15 18:15:23 drh Exp $
**
** This file implements a external (disk-based) database using BTrees.
** See the header comment on "btreeInt.h" for additional information.
** Including a description of file format and an overview of operation.
*/
#include "btreeInt.h"
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      /* Set the new 'max-root-page' value in the database header. This
      ** is the old value less one, less one more if that happens to
      ** be a root-page number, less one again if that is the
      ** PENDING_BYTE_PAGE.
      */
      maxRootPgno--;
      if( maxRootPgno==PENDING_BYTE_PAGE(pBt) ){
        maxRootPgno--;
      }
      if( maxRootPgno==PTRMAP_PAGENO(pBt, maxRootPgno) ){
        maxRootPgno--;
      }
      assert( maxRootPgno!=PENDING_BYTE_PAGE(pBt) );

      rc = sqlite3BtreeUpdateMeta(p, 4, maxRootPgno);
    }else{
      rc = freePage(pPage);








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      /* Set the new 'max-root-page' value in the database header. This
      ** is the old value less one, less one more if that happens to
      ** be a root-page number, less one again if that is the
      ** PENDING_BYTE_PAGE.
      */
      maxRootPgno--;
      while( maxRootPgno==PENDING_BYTE_PAGE(pBt)


             || PTRMAP_ISPAGE(pBt, maxRootPgno) ){
        maxRootPgno--;
      }
      assert( maxRootPgno!=PENDING_BYTE_PAGE(pBt) );

      rc = sqlite3BtreeUpdateMeta(p, 4, maxRootPgno);
    }else{
      rc = freePage(pPage);
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