SQLite

#endif
          rc = getOverflowPage(pBt, nextPage, 0, &nextPage);
        offset -= ovflSize;
      }else{
        /* Need to read this page properly. It contains some of the
        ** range of data that is being read (eOp==0) or written (eOp!=0).
        */
#ifdef SQLITE_DIRECT_OVERFLOW_READ
        sqlite3_file *fd;
#endif
        int a = amt;
        if( a + offset > ovflSize ){
          a = ovflSize - offset;
        }

#ifdef SQLITE_DIRECT_OVERFLOW_READ
        /* If all the following are true:
        **
        **   1) this is a read operation, and 
        **   2) data is required from the start of this overflow page, and
        **   3) the database is file-backed, and
        **   4) there is no open write-transaction, and
        **   5) the database is not a WAL database,
        **
        ** then data can be read directly from the database file into the
        ** output buffer, bypassing the page-cache altogether. This speeds
        ** up loading large records that span many overflow pages.
        */
        if( eOp==0                                             /* (1) */
         && offset==0                                          /* (2) */
         && pBt->inTransaction==TRANS_READ                     /* (4) */
         && (fd = sqlite3PagerFile(pBt->pPager))->pMethods     /* (3) */
         && pBt->pPage1->aData[19]==0x01                       /* (5) */
        ){
          u8 aSave[4];
          u8 *aWrite = &pBuf[-4];
          memcpy(aSave, aWrite, 4);
          rc = sqlite3OsRead(fd, aWrite, a+4, pBt->pageSize * (nextPage-1));
          nextPage = get4byte(aWrite);
          memcpy(aWrite, aSave, 4);
        }else
#endif

        {
          DbPage *pDbPage;
          rc = sqlite3PagerGet(pBt->pPager, nextPage, &pDbPage);
          if( rc==SQLITE_OK ){
            aPayload = sqlite3PagerGetData(pDbPage);
            nextPage = get4byte(aPayload);



            rc = copyPayload(&aPayload[offset+4], pBuf, a, eOp, pDbPage);
            sqlite3PagerUnref(pDbPage);
            offset = 0;
          }
        }
        amt -= a;
        pBuf += a;

      }
    }
  }

  if( rc==SQLITE_OK && amt>0 ){
    return SQLITE_CORRUPT_BKPT;
  }

#endif

#ifdef SQLITE_DEBUG
  Tcl_SetVar2(interp, "sqlite_options", "debug", "1", TCL_GLOBAL_ONLY);
#else
  Tcl_SetVar2(interp, "sqlite_options", "debug", "0", TCL_GLOBAL_ONLY);
#endif

#ifdef SQLITE_DIRECT_OVERFLOW_READ
  Tcl_SetVar2(interp, "sqlite_options", "direct_read", "1", TCL_GLOBAL_ONLY);
#else
  Tcl_SetVar2(interp, "sqlite_options", "direct_read", "0", TCL_GLOBAL_ONLY);
#endif

#ifdef SQLITE_DISABLE_DIRSYNC
  Tcl_SetVar2(interp, "sqlite_options", "dirsync", "0", TCL_GLOBAL_ONLY);
#else
  Tcl_SetVar2(interp, "sqlite_options", "dirsync", "1", TCL_GLOBAL_ONLY);
#endif

# Do not use a codec for tests in this file, as the database file is
# manipulated directly using tcl scripts (using the [hexio_write] command).
#
do_not_use_codec

# We must have the page_size pragma for these tests to work.
#
ifcapable !pager_pragmas||direct_read {
  finish_test
  return
}

# Create a database with an overflow page.
#
do_test corrupt3-1.1 {

# Test the pagers response to the b-tree layer requesting illegal page 
# numbers:
#
#   + The locking page,
#   + Page 0,
#   + A page with a page number greater than (2^31-1).
#
# These tests will not work if SQLITE_DIRECT_OVERFLOW_READ is defined. In
# that case IO errors are sometimes reported instead of SQLITE_CORRUPT.
#
ifcapable !direct_read {
do_test pager1-18.1 {
  faultsim_delete_and_reopen
  db func a_string a_string
  execsql { 
    PRAGMA page_size = 1024;
    CREATE TABLE t1(a, b);
    INSERT INTO t1 VALUES(a_string(500), a_string(200));

  set root [db one "SELECT rootpage FROM sqlite_master"]
  db close

  hexio_write test.db [expr ($root-1)*1024 + 8] 00000000
  sqlite3 db test.db
  catchsql { SELECT length(x) FROM t1 }
} {1 {database disk image is malformed}}
}

do_test pager1-19.1 {
  sqlite3 db ""
  db func a_string a_string
  execsql {
    PRAGMA page_size = 512;
    PRAGMA auto_vacuum = 1;

# pager optimizations implemented in version 3.3.14 work.
#
# $Id: pageropt.test,v 1.5 2008/08/20 14:49:25 danielk1977 Exp $

set testdir [file dirname $argv0]
source $testdir/tester.tcl

ifcapable {!pager_pragmas||secure_delete||direct_read} {
  finish_test
  return
}

# Run the SQL statement supplied by the argument and return
# the results.  Prepend four integers to the beginning of the
# result which are