** *id unchanged.
*/
static int unixOpenDirectory(
  OsFile *id,
  const char *zDirname
){
  unixFile *pFile = (unixFile*)id;
  if( pFile==0 ){
    /* Do not open the directory if the corresponding file is not already
    ** open. */
    return SQLITE_CANTOPEN;
  }
  SET_THREADID(pFile);
  assert( pFile->dirfd<0 );
  pFile->dirfd = open(zDirname, O_RDONLY|O_BINARY, 0);
  if( pFile->dirfd<0 ){
    return SQLITE_CANTOPEN; 
  }
  OSTRACE3("OPENDIR %-3d %s\n", pFile->dirfd, zDirname);
................................................................................
*/
static int seekAndRead(unixFile *id, void *pBuf, int cnt){
  int got;
  i64 newOffset;
  TIMER_START;
#if defined(USE_PREAD)
  got = pread(id->h, pBuf, cnt, id->offset);

#elif defined(USE_PREAD64)
  got = pread64(id->h, pBuf, cnt, id->offset);

#else
  newOffset = lseek(id->h, id->offset, SEEK_SET);

  if( newOffset!=id->offset ){
    return -1;
  }
  got = read(id->h, pBuf, cnt);
#endif
  TIMER_END;
  OSTRACE5("READ    %-3d %5d %7lld %d\n", id->h, got, id->offset, TIMER_ELAPSED);
................................................................................
** bytes were read successfully and SQLITE_IOERR if anything goes
** wrong.
*/
static int unixRead(OsFile *id, void *pBuf, int amt){
  int got;
  assert( id );
  got = seekAndRead((unixFile*)id, pBuf, amt);
  SimulateIOError( got = -1 );
  if( got==amt ){
    return SQLITE_OK;
  }else if( got<0 ){
    return SQLITE_IOERR_READ;
  }else{
    memset(&((char*)pBuf)[got], 0, amt-got);
    return SQLITE_IOERR_SHORT_READ;

** *id unchanged.
*/
static int unixOpenDirectory(
  OsFile *id,
  const char *zDirname
){
  unixFile *pFile = (unixFile*)id;
  assert( pFile!=0 );




  SET_THREADID(pFile);
  assert( pFile->dirfd<0 );
  pFile->dirfd = open(zDirname, O_RDONLY|O_BINARY, 0);
  if( pFile->dirfd<0 ){
    return SQLITE_CANTOPEN; 
  }
  OSTRACE3("OPENDIR %-3d %s\n", pFile->dirfd, zDirname);
................................................................................
*/
static int seekAndRead(unixFile *id, void *pBuf, int cnt){
  int got;
  i64 newOffset;
  TIMER_START;
#if defined(USE_PREAD)
  got = pread(id->h, pBuf, cnt, id->offset);
  SimulateIOError( got = -1 );
#elif defined(USE_PREAD64)
  got = pread64(id->h, pBuf, cnt, id->offset);
  SimulateIOError( got = -1 );
#else
  newOffset = lseek(id->h, id->offset, SEEK_SET);
  SimulateIOError( newOffset-- );
  if( newOffset!=id->offset ){
    return -1;
  }
  got = read(id->h, pBuf, cnt);
#endif
  TIMER_END;
  OSTRACE5("READ    %-3d %5d %7lld %d\n", id->h, got, id->offset, TIMER_ELAPSED);
................................................................................
** bytes were read successfully and SQLITE_IOERR if anything goes
** wrong.
*/
static int unixRead(OsFile *id, void *pBuf, int amt){
  int got;
  assert( id );
  got = seekAndRead((unixFile*)id, pBuf, amt);

  if( got==amt ){
    return SQLITE_OK;
  }else if( got<0 ){
    return SQLITE_IOERR_READ;
  }else{
    memset(&((char*)pBuf)[got], 0, amt-got);
    return SQLITE_IOERR_SHORT_READ;

** The pager is used to access a database disk file.  It implements
** atomic commit and rollback through the use of a journal file that
** is separate from the database file.  The pager also implements file
** locking to prevent two processes from writing the same database
** file simultaneously, or one process from reading the database while
** another is writing.
**
** @(#) $Id: pager.c,v 1.323 2007/04/05 17:15:53 danielk1977 Exp $
*/
#ifndef SQLITE_OMIT_DISKIO
#include "sqliteInt.h"
#include "os.h"
#include "pager.h"
#include <assert.h>
#include <string.h>
................................................................................
**
** If the current size of the database file is 0 but a journal file
** exists, that is probably an old journal left over from a prior
** database with the same name.  Just delete the journal.
*/
static int hasHotJournal(Pager *pPager){
  if( !pPager->useJournal ) return 0;
  if( !sqlite3OsFileExists(pPager->zJournal) ) return 0;


  if( sqlite3OsCheckReservedLock(pPager->fd) ) return 0;


  if( sqlite3PagerPagecount(pPager)==0 ){
    sqlite3OsDelete(pPager->zJournal);
    return 0;
  }else{
    return 1;
  }
}

** The pager is used to access a database disk file.  It implements
** atomic commit and rollback through the use of a journal file that
** is separate from the database file.  The pager also implements file
** locking to prevent two processes from writing the same database
** file simultaneously, or one process from reading the database while
** another is writing.
**
** @(#) $Id: pager.c,v 1.324 2007/04/06 18:23:18 drh Exp $
*/
#ifndef SQLITE_OMIT_DISKIO
#include "sqliteInt.h"
#include "os.h"
#include "pager.h"
#include <assert.h>
#include <string.h>
................................................................................
**
** If the current size of the database file is 0 but a journal file
** exists, that is probably an old journal left over from a prior
** database with the same name.  Just delete the journal.
*/
static int hasHotJournal(Pager *pPager){
  if( !pPager->useJournal ) return 0;
  if( !sqlite3OsFileExists(pPager->zJournal) ){
    return 0;
  }
  if( sqlite3OsCheckReservedLock(pPager->fd) ){
    return 0;
  }
  if( sqlite3PagerPagecount(pPager)==0 ){
    sqlite3OsDelete(pPager->zJournal);
    return 0;
  }else{
    return 1;
  }
}

# 2007 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.
#
#***********************************************************************
# This file implements regression tests for SQLite library.  The
# focus of this script is database locks.
#
# $Id: lock4.test,v 1.3 2007/04/06 18:23:19 drh Exp $


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

# Initialize the test.db database so that it is non-empty
#
do_test lock4-1.1 {
  db eval {CREATE TABLE t1(x)}
  file delete -force test2.db test2.db-journal
  sqlite3 db2 test2.db
  db2 eval {CREATE TABLE t2(x)}
  db2 close
  list [file size test.db] [file size test2.db]
} {2048 2048}

# Create a script to drive a separate process that will
#
#     1.  Create a second database test2.db
#     2.  Get an exclusive lock on test2.db
#     3.  Add an entry to test.db in table t1, waiting as necessary.
#     4.  Commit the change to test2.db.
#
# Meanwhile, this process will:
# 
#     A.  Get an exclusive lock on test.db
#     B.  Attempt to read from test2.db but get an SQLITE_BUSY error.
#     C.  Commit the changes to test.db thus alloing the other process
#         to continue.
#
do_test lock4-1.2 {
  set out [open test2-script.tcl w]
  puts $out "set sqlite_pending_byte [set sqlite_pending_byte]"
  puts $out {
     sqlite3 db2 test2.db
     db2 eval {
        BEGIN;
        INSERT INTO t2 VALUES(2);
     }
     sqlite3 db test.db
     db timeout 1000000
     db eval {
        INSERT INTO t1 VALUES(2);
     }
     db2 eval COMMIT
     exit
  }
  close $out
  db eval {
     BEGIN;
     INSERT INTO t1 VALUES(1);
  }
  exec [info nameofexec] ./test2-script.tcl &
  while {![file exists test2.db-journal]} {
    after 10
  }
  sqlite3 db2 test2.db
  catchsql {
    INSERT INTO t2 VALUES(1)
  } db2
} {1 {database is locked}}
do_test lock4-1.3 {
  db eval {
     COMMIT;
  }
  while {[file exists test2.db-journal]} {
    after 10
  }
  db2 eval {
     SELECT * FROM t2
  }
} {2}

    
do_test lock4-999.1 {
  rename db2 {}
} {}

finish_test

/* For tracing reduce actions, the names of all rules are required.
*/
static const char *const yyRuleName[] = {
%%
};
#endif /* NDEBUG */

/*
** This function returns the symbolic name associated with a token
** value.
*/
const char *ParseTokenName(int tokenType){
#ifndef NDEBUG
  if( tokenType>0 && tokenType<(sizeof(yyTokenName)/sizeof(yyTokenName[0])) ){
    return yyTokenName[tokenType];
  }else{
    return "Unknown";
  }
#else
  return "";
#endif
}

#if YYSTACKDEPTH<=0
/*
** Try to increase the size of the parser stack.
*/
static void yyGrowStack(yyParser *p){
  int newSize;

/* For tracing reduce actions, the names of all rules are required.
*/
static const char *const yyRuleName[] = {
%%
};
#endif /* NDEBUG */

















#if YYSTACKDEPTH<=0
/*
** Try to increase the size of the parser stack.
*/
static void yyGrowStack(yyParser *p){
  int newSize;