SQLite

      /* If we cannot get an EXCLUSIVE lock, downgrade the PENDING lock
      ** that we did get back to SHARED. */
      sqlite3OsUnlock(pPager->fd, SQLITE_LOCK_SHARED);
    }
  }
  return rc;
}

#ifdef SQLITE_HAS_CODEC
/*
** This function is called by the wal module when writing page content
** into the log file.
**
** This function returns a pointer to a buffer containing the encrypted
** page content. If a malloc fails, this function may return NULL.
*/
void *sqlite3PagerCodec(PgHdr *pPg){
  void *aData = 0;
  CODEC2(pPg->pPager, pPg->pData, pPg->pgno, 6, return 0, aData);
  return aData;
}
#endif

#endif

#endif /* SQLITE_OMIT_DISKIO */

const char *sqlite3PagerJournalname(Pager*);
int sqlite3PagerNosync(Pager*);
void *sqlite3PagerTempSpace(Pager*);
int sqlite3PagerIsMemdb(Pager*);

/* Functions used to truncate the database file. */
void sqlite3PagerTruncateImage(Pager*,Pgno);

#if defined(SQLITE_HAS_CODEC) && !defined(SQLITE_OMIT_WAL)
void *sqlite3PagerCodec(DbPage *);
#else
#define sqlite3PagerCodec(x) (x->pData)
#endif

/* Functions to support testing and debugging. */
#if !defined(NDEBUG) || defined(SQLITE_TEST)
  Pgno sqlite3PagerPagenumber(DbPage*);
  int sqlite3PagerIswriteable(DbPage*);
#endif
#ifdef SQLITE_TEST

  }
  assert( pWal->szPage==szPage );

  /* Write the log file. */
  for(p=pList; p; p=p->pDirty){
    u32 nDbsize;                  /* Db-size field for frame header */
    i64 iOffset;                  /* Write offset in log file */
    void *pData;
   
   
    iOffset = walFrameOffset(++iFrame, szPage);
    
    /* Populate and write the frame header */
    nDbsize = (isCommit && p->pDirty==0) ? nTruncate : 0;
    if( (pData = sqlite3PagerCodec(p))==0 ) return SQLITE_NOMEM;
    walEncodeFrame(pWal, p->pgno, nDbsize, pData, aFrame);
    rc = sqlite3OsWrite(pWal->pWalFd, aFrame, sizeof(aFrame), iOffset);
    if( rc!=SQLITE_OK ){
      return rc;
    }

    /* Write the page data */
    rc = sqlite3OsWrite(pWal->pWalFd, pData, szPage, iOffset+sizeof(aFrame));
    if( rc!=SQLITE_OK ){
      return rc;
    }
    pLast = p;
  }

  /* Sync the log file if the 'isSync' flag was specified. */
  if( sync_flags ){
    i64 iSegment = sqlite3OsSectorSize(pWal->pWalFd);
    i64 iOffset = walFrameOffset(iFrame+1, szPage);

    assert( isCommit );
    assert( iSegment>0 );

    iSegment = (((iOffset+iSegment-1)/iSegment) * iSegment);
    while( iOffset<iSegment ){
      void *pData;
      if( (pData = sqlite3PagerCodec(pLast))==0 ) return SQLITE_NOMEM;
      walEncodeFrame(pWal, pLast->pgno, nTruncate, pData, aFrame);
      rc = sqlite3OsWrite(pWal->pWalFd, aFrame, sizeof(aFrame), iOffset);
      if( rc!=SQLITE_OK ){
        return rc;
      }

      iOffset += WAL_FRAME_HDRSIZE;
      rc = sqlite3OsWrite(pWal->pWalFd, pData, szPage, iOffset); 
      if( rc!=SQLITE_OK ){
        return rc;
      }
      nLast++;
      iOffset += szPage;
    }

#
#***********************************************************************
# This file contains code used by several different test scripts. The
# code in this file allows testfixture to control another process (or
# processes) to test locking.
#



proc do_multiclient_test {varname script} {

  foreach code [list {
    set ::code2_chan [launch_testfixture]
    set ::code3_chan [launch_testfixture]
    proc code2 {tcl} { testfixture $::code2_chan $tcl }
    proc code3 {tcl} { testfixture $::code3_chan $tcl }

}

# Launch another testfixture process to be controlled by this one. A
# channel name is returned that may be passed as the first argument to proc
# 'testfixture' to execute a command. The child testfixture process is shut
# down by closing the channel.
proc launch_testfixture {} {
  write_main_loop
  set prg [info nameofexec]
  if {$prg eq ""} {
    set prg [file join . testfixture]
  }
  set chan [open "|$prg tf_main.tcl" r+]
  fconfigure $chan -buffering line
  testfixture $chan "sqlite3_test_control_pending_byte $::sqlite_pending_byte"

# Write the main loop for the child testfixture processes into file
# tf_main.tcl. The parent (this script) interacts with the child processes
# via a two way pipe. The parent writes a script to the stdin of the child
# process, followed by the word "OVER" on a line of its own. The child
# process evaluates the script and writes the results to stdout, followed
# by an "OVER" of its own.
#
set main_loop_written 0
proc write_main_loop {} {
  if {$::main_loop_written} return
  set wrapper ""
  if {[sqlite3 -has-codec] && [info exists ::do_not_use_codec]==0} {
    set wrapper "
      rename sqlite3 sqlite_orig
      proc sqlite3 {args} {[info body sqlite3]}
    "
  }

  set fd [open tf_main.tcl w]
  puts $fd [string map [list %WRAPPER% $wrapper] {

    %WRAPPER%
    set script ""
    while {![eof stdin]} {
      flush stdout
      set line [gets stdin]

      if { $line == "OVER" } {
        set rc [catch {eval $script} result]
        puts [list $rc $result]

        puts OVER

        flush stdout
        set script ""
      } else {
        append script $line
        append script "\n"
      }
    }
  }]
  close $fd
  set main_loop_written 1
}

#

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






ifcapable !wal {finish_test ; return }

proc reopen_db {} {
  catch { db close }
  file delete -force test.db test.db-wal test.db-wal-summary
  sqlite3_wal db test.db
}

#

set testdir [file dirname $argv0]
source $testdir/tester.tcl
source $testdir/lock_common.tcl
ifcapable !wal {finish_test ; return }






proc set_tvfs_hdr {file args} {

  # Set $nHdr to the number of bytes in the wal-index header:
  set nHdr 40
  set nInt [expr {$nHdr/4}]

  if {[llength $args]>2} {

    PRAGMA journal_mode = WAL;
    CREATE TABLE t1(x);
    INSERT INTO t1 VALUES(zeroblob(8188*1020));
    CREATE TABLE t2(y);
  }
  execsql {
    PRAGMA wal_checkpoint;
    SELECT rootpage>=8192 FROM sqlite_master WHERE tbl_name = 't2';
  }
} {1}
do_test wal2-8.1.3 {
  execsql {
    PRAGMA cache_size = 10;
    CREATE TABLE t3(z);
    BEGIN;
      INSERT INTO t3 VALUES(randomblob(900));
      INSERT INTO t3 SELECT randomblob(900) FROM t3;