SQLite

3.8.7

srcdir		= @srcdir@
prefix		= @prefix@
exec_prefix	= @exec_prefix@

bindir		= @bindir@
libdir		= @libdir@
datarootdir	= @datarootdir@
datadir		= @datadir@
mandir		= @mandir@
includedir	= @includedir@

DESTDIR		=

PKG_DIR		= $(PACKAGE_NAME)$(PACKAGE_VERSION)

AC_DEFINE(USE_TCL_STUBS, 1, [Use Tcl stubs])
#AC_DEFINE(USE_TK_STUBS, 1, [Use Tk stubs])


#--------------------------------------------------------------------
# Redefine fdatasync as fsync on systems that lack fdatasync
#--------------------------------------------------------------------
#
#AC_CHECK_FUNC(fdatasync, , AC_DEFINE(fdatasync, fsync))
# Check for library functions that SQLite can optionally use.
AC_CHECK_FUNCS([fdatasync usleep fullfsync localtime_r gmtime_r])

AC_FUNC_STRERROR_R


#--------------------------------------------------------------------
# This macro generates a line to use when building a library.  It
# depends on values set by the TEA_ENABLE_SHARED, TEA_ENABLE_SYMBOLS,

	    ])
	    ;;
	FreeBSD-*)
	    # This configuration from FreeBSD Ports.
	    SHLIB_CFLAGS="-fPIC"
	    SHLIB_LD="${CC} -shared"
	    TCL_SHLIB_LD_EXTRAS="-Wl,-soname=\$[@]"
	    TK_SHLIB_LD_EXTRAS="-Wl,-soname,\$[@]"
	    SHLIB_SUFFIX=".so"
	    LDFLAGS=""
	    AS_IF([test $doRpath = yes], [
		CC_SEARCH_FLAGS='-Wl,-rpath,${LIB_RUNTIME_DIR}'
		LD_SEARCH_FLAGS='-Wl,-rpath,${LIB_RUNTIME_DIR}'])
	    AS_IF([test "${TCL_THREADS}" = "1"], [
		# The -pthread needs to go in the LDFLAGS, not LIBS
		LIBS=`echo $LIBS | sed s/-pthread//`
		CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
		LDFLAGS="$LDFLAGS $PTHREAD_LIBS"])
	    case $system in
	    FreeBSD-3.*)
		# Version numbers are dot-stripped by system policy.
		TCL_TRIM_DOTS=`echo ${VERSION} | tr -d .`
		UNSHARED_LIB_SUFFIX='${TCL_TRIM_DOTS}.a'
		SHARED_LIB_SUFFIX='${TCL_TRIM_DOTS}.so'
		TCL_LIB_VERSIONS_OK=nodots
		;;
	    esac
	    ;;
	Darwin-*)
	    CFLAGS_OPTIMIZE="-Os"
	    SHLIB_CFLAGS="-fno-common"
	    # To avoid discrepancies between what headers configure sees during
	    # preprocessing tests and compiling tests, move any -isysroot and
	    # -mmacosx-version-min flags from CFLAGS to CPPFLAGS:

	    LD_SEARCH_FLAGS=""
	    ;;
	SCO_SV-3.2*)
	    AS_IF([test "$GCC" = yes], [
		SHLIB_CFLAGS="-fPIC -melf"
		LDFLAGS="$LDFLAGS -melf -Wl,-Bexport"
	    ], [
		SHLIB_CFLAGS="-Kpic -belf"
		LDFLAGS="$LDFLAGS -belf -Wl,-Bexport"
	    ])
	    SHLIB_LD="ld -G"
	    SHLIB_LD_LIBS=""
	    SHLIB_SUFFIX=".so"
	    CC_SEARCH_FLAGS=""
	    LD_SEARCH_FLAGS=""
	    ;;

	    no_celib=
	    CELIB_DIR=${ac_cv_c_celibconfig}
	    CELIB_DIR=`echo "$CELIB_DIR" | sed -e 's!\\\!/!g'`
	    AC_MSG_RESULT([found $CELIB_DIR])
	fi
    fi
])


# Local Variables:
# mode: autoconf
# End:

#! /bin/sh
# Guess values for system-dependent variables and create Makefiles.
# Generated by GNU Autoconf 2.62 for sqlite 3.8.7.
#
# Copyright (C) 1992, 1993, 1994, 1995, 1996, 1998, 1999, 2000, 2001,
# 2002, 2003, 2004, 2005, 2006, 2007, 2008 Free Software Foundation, Inc.
# This configure script is free software; the Free Software Foundation
# gives unlimited permission to copy, distribute and modify it.
## --------------------- ##
## M4sh Initialization.  ##

MFLAGS=
MAKEFLAGS=
SHELL=${CONFIG_SHELL-/bin/sh}

# Identity of this package.
PACKAGE_NAME='sqlite'
PACKAGE_TARNAME='sqlite'
PACKAGE_VERSION='3.8.7'
PACKAGE_STRING='sqlite 3.8.7'
PACKAGE_BUGREPORT=''

# Factoring default headers for most tests.
ac_includes_default="\
#include <stdio.h>
#ifdef HAVE_SYS_TYPES_H
# include <sys/types.h>

#
# Report the --help message.
#
if test "$ac_init_help" = "long"; then
  # Omit some internal or obsolete options to make the list less imposing.
  # This message is too long to be a string in the A/UX 3.1 sh.
  cat <<_ACEOF
\`configure' configures sqlite 3.8.7 to adapt to many kinds of systems.

Usage: $0 [OPTION]... [VAR=VALUE]...

To assign environment variables (e.g., CC, CFLAGS...), specify them as
VAR=VALUE.  See below for descriptions of some of the useful variables.

Defaults for the options are specified in brackets.

  --build=BUILD     configure for building on BUILD [guessed]
  --host=HOST       cross-compile to build programs to run on HOST [BUILD]
_ACEOF
fi

if test -n "$ac_init_help"; then
  case $ac_init_help in
     short | recursive ) echo "Configuration of sqlite 3.8.7:";;
   esac
  cat <<\_ACEOF

Optional Features:
  --disable-option-checking  ignore unrecognized --enable/--with options
  --disable-FEATURE       do not include FEATURE (same as --enable-FEATURE=no)
  --enable-FEATURE[=ARG]  include FEATURE [ARG=yes]

    cd "$ac_pwd" || { ac_status=$?; break; }
  done
fi

test -n "$ac_init_help" && exit $ac_status
if $ac_init_version; then
  cat <<\_ACEOF
sqlite configure 3.8.7
generated by GNU Autoconf 2.62

Copyright (C) 1992, 1993, 1994, 1995, 1996, 1998, 1999, 2000, 2001,
2002, 2003, 2004, 2005, 2006, 2007, 2008 Free Software Foundation, Inc.
This configure script is free software; the Free Software Foundation
gives unlimited permission to copy, distribute and modify it.
_ACEOF
  exit
fi
cat >config.log <<_ACEOF
This file contains any messages produced by compilers while
running configure, to aid debugging if configure makes a mistake.

It was created by sqlite $as_me 3.8.7, which was
generated by GNU Autoconf 2.62.  Invocation command line was

  $ $0 $@

_ACEOF
exec 5>>config.log
{

exec 6>&1

# Save the log message, to keep $[0] and so on meaningful, and to
# report actual input values of CONFIG_FILES etc. instead of their
# values after options handling.
ac_log="
This file was extended by sqlite $as_me 3.8.7, which was
generated by GNU Autoconf 2.62.  Invocation command line was

  CONFIG_FILES    = $CONFIG_FILES
  CONFIG_HEADERS  = $CONFIG_HEADERS
  CONFIG_LINKS    = $CONFIG_LINKS
  CONFIG_COMMANDS = $CONFIG_COMMANDS
  $ $0 $@

$config_commands

Report bugs to <bug-autoconf@gnu.org>."

_ACEOF
cat >>$CONFIG_STATUS <<_ACEOF || ac_write_fail=1
ac_cs_version="\\
sqlite config.status 3.8.7
configured by $0, generated by GNU Autoconf 2.62,
  with options \\"`$as_echo "$ac_configure_args" | sed 's/^ //; s/[\\""\`\$]/\\\\&/g'`\\"

Copyright (C) 2008 Free Software Foundation, Inc.
This config.status script is free software; the Free Software Foundation
gives unlimited permission to copy, distribute and modify it."

  int *pnToken,                   /* OUT: Number of bytes at *paToken */
  int *piStart,                   /* OUT: Starting offset of token */
  int *piEnd,                     /* OUT: Ending offset of token */
  int *piPos                      /* OUT: Position integer of token */
){
  unicode_cursor *pCsr = (unicode_cursor *)pC;
  unicode_tokenizer *p = ((unicode_tokenizer *)pCsr->base.pTokenizer);
  int iCode = 0;
  char *zOut;
  const unsigned char *z = &pCsr->aInput[pCsr->iOff];
  const unsigned char *zStart = z;
  const unsigned char *zEnd;
  const unsigned char *zTerm = &pCsr->aInput[pCsr->nInput];

  /* Scan past any delimiter characters before the start of the next token.

  ** The most significant 22 bits in each 32-bit value contain the first 
  ** codepoint in the range. The least significant 10 bits are used to store
  ** the size of the range (always at least 1). In other words, the value 
  ** ((C<<22) + N) represents a range of N codepoints starting with codepoint 
  ** C. It is not possible to represent a range larger than 1023 codepoints 
  ** using this format.
  */
  static const unsigned int aEntry[] = {
    0x00000030, 0x0000E807, 0x00016C06, 0x0001EC2F, 0x0002AC07,
    0x0002D001, 0x0002D803, 0x0002EC01, 0x0002FC01, 0x00035C01,
    0x0003DC01, 0x000B0804, 0x000B480E, 0x000B9407, 0x000BB401,
    0x000BBC81, 0x000DD401, 0x000DF801, 0x000E1002, 0x000E1C01,
    0x000FD801, 0x00120808, 0x00156806, 0x00162402, 0x00163C01,
    0x00164437, 0x0017CC02, 0x00180005, 0x00181816, 0x00187802,
    0x00192C15, 0x0019A804, 0x0019C001, 0x001B5001, 0x001B580F,

    0xFFFFFFFF, 0xFC00FFFF, 0xF8000001, 0xF8000001,
  };

  if( c<128 ){
    return ( (aAscii[c >> 5] & (1 << (c & 0x001F)))==0 );
  }else if( c<(1<<22) ){
    unsigned int key = (((unsigned int)c)<<10) | 0x000003FF;
    int iRes = 0;
    int iHi = sizeof(aEntry)/sizeof(aEntry[0]) - 1;
    int iLo = 0;
    while( iHi>=iLo ){
      int iTest = (iHi + iLo) / 2;
      if( key >= aEntry[iTest] ){
        iRes = iTest;
        iLo = iTest+1;

      iLo = iTest+1;
    }else{
      iHi = iTest-1;
    }
  }
  assert( key>=aDia[iRes] );
  return ((c > (aDia[iRes]>>3) + (aDia[iRes]&0x07)) ? c : (int)aChar[iRes]);

}


/*
** Return true if the argument interpreted as a unicode codepoint
** is a diacritical modifier character.
*/
int sqlite3FtsUnicodeIsdiacritic(int c){

      iLo = iTest+1;
    }else{
      iHi = iTest-1;
    }
  }
  assert( key>=aDia[iRes] );
  return ((c > (aDia[iRes]>>3) + (aDia[iRes]&0x07)) ? c : (int)aChar[iRes]);}
  puts "\}"
}

proc print_isdiacritic {zFunc map} {

  set lCode [list]
  foreach m $map {
    foreach {code char} $m {}

  ** codepoint in the range. The least significant 10 bits are used to store
  ** the size of the range (always at least 1). In other words, the value 
  ** ((C<<22) + N) represents a range of N codepoints starting with codepoint 
  ** C. It is not possible to represent a range larger than 1023 codepoints 
  ** using this format.
  */
  }]
  puts -nonewline "  static const unsigned int aEntry\[\] = \{"
  set i 0
  foreach range $lRange {
    foreach {iFirst nRange} $range {}
    set u32 [format "0x%08X" [expr ($iFirst<<10) + $nRange]]

    if {($i % 5)==0} {puts "" ; puts -nonewline "   "}
    puts -nonewline " $u32,"

  an_print_range_array $lRange
  an_print_ascii_bitmap $lRange
  puts {
  if( c<128 ){
    return ( (aAscii[c >> 5] & (1 << (c & 0x001F)))==0 );
  }else if( c<(1<<22) ){
    unsigned int key = (((unsigned int)c)<<10) | 0x000003FF;
    int iRes = 0;
    int iHi = sizeof(aEntry)/sizeof(aEntry[0]) - 1;
    int iLo = 0;
    while( iHi>=iLo ){
      int iTest = (iHi + iLo) / 2;
      if( key >= aEntry[iTest] ){
        iRes = iTest;
        iLo = iTest+1;

*/

/*
** DO NOT EDIT THIS MACHINE GENERATED FILE.
*/
  }]
  puts ""
  puts "#ifndef SQLITE_DISABLE_FTS3_UNICODE"
  puts "#if defined(SQLITE_ENABLE_FTS3) || defined(SQLITE_ENABLE_FTS4)"
  puts ""
  puts "#include <assert.h>"
  puts ""
}

proc print_test_main {} {

if {$::generate_test_code} {
  print_test_isalnum sqlite3FtsUnicodeIsalnum $lRange
  print_fold_test sqlite3FtsUnicodeFold $mappings
  print_test_main 
}

puts "#endif /* defined(SQLITE_ENABLE_FTS3) || defined(SQLITE_ENABLE_FTS4) */"
puts "#endif /* !defined(SQLITE_DISABLE_FTS3_UNICODE) */"

static void writefileFunc(
  sqlite3_context *context,
  int argc,
  sqlite3_value **argv
){
  FILE *out;
  const char *z;

  sqlite3_int64 rc;
  const char *zFile;

  zFile = (const char*)sqlite3_value_text(argv[0]);
  if( zFile==0 ) return;
  out = fopen(zFile, "wb");
  if( out==0 ) return;
  z = (const char*)sqlite3_value_blob(argv[1]);
  if( z==0 ){

    rc = 0;
  }else{

    rc = fwrite(z, 1, sqlite3_value_bytes(argv[1]), out);
  }
  fclose(out);
  sqlite3_result_int64(context, rc);
}


#ifdef _WIN32

    }
    zK2 = (char*)phoneticHash((const unsigned char*)zK1, i);
    if( zK2==0 ){
      sqlite3_free(zK1);
      return SQLITE_NOMEM;
    }
    if( sqlite3_value_type(argv[0])==SQLITE_NULL ){
      if( sqlite3_value_type(argv[1])==SQLITE_NULL ){
        spellfix1DbExec(&rc, db,
               "INSERT INTO \"%w\".\"%w_vocab\"(rank,langid,word,k1,k2) "
               "VALUES(%d,%d,%Q,%Q,%Q)",
               p->zDbName, p->zTableName,
               iRank, iLang, zWord, zK1, zK2
        );
      }else{
        newRowid = sqlite3_value_int64(argv[1]);
        spellfix1DbExec(&rc, db,
               "INSERT INTO \"%w\".\"%w_vocab\"(id,rank,langid,word,k1,k2) "
               "VALUES(%lld,%d,%d,%Q,%Q,%Q)",
               p->zDbName, p->zTableName,
               newRowid, iRank, iLang, zWord, zK1, zK2
        );
      }
      *pRowid = sqlite3_last_insert_rowid(db);
    }else{
      rowid = sqlite3_value_int64(argv[0]);
      newRowid = *pRowid = sqlite3_value_int64(argv[1]);
      spellfix1DbExec(&rc, db,
             "UPDATE \"%w\".\"%w_vocab\" SET id=%lld, rank=%d, langid=%d,"
             " word=%Q, k1=%Q, k2=%Q WHERE id=%lld",

  RtreeNode *pRoot = 0;
  int ii;
  int rc = SQLITE_OK;
  int iCell = 0;

  rtreeReference(pRtree);

  /* Reset the cursor to the same state as rtreeOpen() leaves it in. */
  freeCursorConstraints(pCsr);
  sqlite3_free(pCsr->aPoint);
  memset(pCsr, 0, sizeof(RtreeCursor));
  pCsr->base.pVtab = (sqlite3_vtab*)pRtree;

  pCsr->iStrategy = idxNum;
  if( idxNum==1 ){
    /* Special case - lookup by rowid. */
    RtreeNode *pLeaf;        /* Leaf on which the required cell resides */
    RtreeSearchPoint *p;     /* Search point for the the leaf */
    i64 iRowid = sqlite3_value_int64(argv[0]);
    i64 iNode = 0;
    rc = findLeafNode(pRtree, iRowid, &pLeaf, &iNode);

#   rtree-4.*: Test INSERT
#   rtree-5.*: Test DELETE
#   rtree-6.*: Test UPDATE
#   rtree-7.*: Test renaming an r-tree table.
#   rtree-8.*: Test constrained scans of r-tree data.
#
#   rtree-12.*: Test that on-conflict clauses are supported.
#   rtree-13.*: Test that bug [d2889096e7bdeac6d] has been fixed.
#

ifcapable !rtree {
  finish_test
  return
}

    do_test $testname.2 [list sql_uses_stmt db $sql] $uses
    do_execsql_test $testname.3 { SELECT * FROM t1 ORDER BY idx } $data

    do_test $testname.4 { rtree_check db t1 } 0
    db close
  }
}

#-------------------------------------------------------------------------
# Test that bug [d2889096e7bdeac6d] has been fixed.
#
reset_db
do_execsql_test 13.1 {
  CREATE VIRTUAL TABLE t9 USING rtree(id, xmin, xmax);
  INSERT INTO t9 VALUES(1,0,0);            
  INSERT INTO t9 VALUES(2,0,0);
  SELECT * FROM t9 WHERE id IN (1, 2);
} {1 0.0 0.0 2 0.0 0.0}

do_execsql_test 13.2 {
  WITH r(x) AS (
    SELECT 1 UNION ALL
    SELECT 2 UNION ALL
    SELECT 3
  )
  SELECT * FROM r CROSS JOIN t9 WHERE id=x;
} {1 1 0.0 0.0 2 2 0.0 0.0}

finish_test

# 2014-08-21
#
# 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 contains tests for the r-tree module.
#
# This file contains test cases for the ticket
# [369d57fb8e5ccdff06f197a37147a88f9de95cda] (2014-08-21)
#
#  The following SQL causes an assertion fault while running
#  sqlite3_prepare() on the DELETE statement:
#
#     CREATE TABLE t1(x);
#     CREATE TABLE t2(y);
#     CREATE VIRTUAL TABLE t3 USING rtree(a,b,c);
#     CREATE TRIGGER t2del AFTER DELETE ON t2 WHEN (SELECT 1 from t1) BEGIN 
#       DELETE FROM t3 WHERE a=old.y; 
#     END;
#     DELETE FROM t2 WHERE y=1;
# 

if {![info exists testdir]} {
  set testdir [file join [file dirname [info script]] .. .. test]
} 
source $testdir/tester.tcl
ifcapable !rtree { finish_test ; return }

do_execsql_test rtreeF-1.1 {
  CREATE TABLE t1(x);
  CREATE TABLE t2(y);
  CREATE VIRTUAL TABLE t3 USING rtree(a,b,c);
  CREATE TRIGGER t2dwl AFTER DELETE ON t2 WHEN (SELECT 1 from t1) BEGIN 
    DELETE FROM t3 WHERE a=old.y; 
  END;

  INSERT INTO t1(x) VALUES(999);
  INSERT INTO t2(y) VALUES(1),(2),(3),(4),(5);
  INSERT INTO t3(a,b,c) VALUES(1,2,3),(2,3,4),(3,4,5),(4,5,6),(5,6,7);

  SELECT a FROM t3 ORDER BY a;
  SELECT '|';
  SELECT y FROM t2 ORDER BY y;
} {1 2 3 4 5 | 1 2 3 4 5}
do_execsql_test rtreeF-1.2 {
  DELETE FROM t2 WHERE y=3;

  SELECT a FROM t3 ORDER BY a;
  SELECT '|';
  SELECT y FROM t2 ORDER BY y;
} {1 2 4 5 | 1 2 4 5}
do_execsql_test rtreeF-1.3 {
  DELETE FROM t1;
  DELETE FROM t2 WHERE y=5;

  SELECT a FROM t3 ORDER BY a;
  SELECT '|';
  SELECT y FROM t2 ORDER BY y;
} {1 2 4 5 | 1 2 4}
do_execsql_test rtreeF-1.4 {
  INSERT INTO t1 DEFAULT VALUES;
  DELETE FROM t2 WHERE y=5;

  SELECT a FROM t3 ORDER BY a;
  SELECT '|';
  SELECT y FROM t2 ORDER BY y;
} {1 2 4 5 | 1 2 4}
do_execsql_test rtreeF-1.5 {
  DELETE FROM t2 WHERE y=2;

  SELECT a FROM t3 ORDER BY a;
  SELECT '|';
  SELECT y FROM t2 ORDER BY y;
} {1 4 5 | 1 4}

finish_test

#endif
  sqlite3DbFree(p->db, p);
}

/*
** Implementation of the stat_init(N,K,C) SQL function. The three parameters
** are:
**     N:    The number of columns in the index including the rowid/pk (note 1)
**     K:    The number of columns in the index excluding the rowid/pk.
**     C:    The number of rows in the index (note 2)
**
** Note 1:  In the special case of the covering index that implements a
** WITHOUT ROWID table, N is the number of PRIMARY KEY columns, not the
** total number of columns in the table.
**
** Note 2:  C is only used for STAT3 and STAT4.
**
** For indexes on ordinary rowid tables, N==K+1.  But for indexes on
** WITHOUT ROWID tables, N=K+P where P is the number of columns in the
** PRIMARY KEY of the table.  The covering index that implements the
** original WITHOUT ROWID table as N==K as a special case.
**
** This routine allocates the Stat4Accum object in heap memory. The return 
** value is a pointer to the the Stat4Accum object encoded as a blob (i.e. 
** the size of the blob is sizeof(void*) bytes). 
*/
static void statInit(
  sqlite3_context *context,

** Arguments:
**
**    P     Pointer to the Stat4Accum object created by stat_init()
**    C     Index of left-most column to differ from previous row
**    R     Rowid for the current row.  Might be a key record for
**          WITHOUT ROWID tables.
**
** This SQL function always returns NULL.  It's purpose it to accumulate
** statistical data and/or samples in the Stat4Accum object about the
** index being analyzed.  The stat_get() SQL function will later be used to
** extract relevant information for constructing the sqlite_statN tables.
**
** The R parameter is only used for STAT3 and STAT4
*/
static void statPush(
  sqlite3_context *context,
  int argc,
  sqlite3_value **argv

#define STAT_GET_ROWID 1          /* "rowid" column of stat[34] entry */
#define STAT_GET_NEQ   2          /* "neq" column of stat[34] entry */
#define STAT_GET_NLT   3          /* "nlt" column of stat[34] entry */
#define STAT_GET_NDLT  4          /* "ndlt" column of stat[34] entry */

/*
** Implementation of the stat_get(P,J) SQL function.  This routine is
** used to query statistical information that has been gathered into
** the Stat4Accum object by prior calls to stat_push().  The P parameter
** is a BLOB which is decoded into a pointer to the Stat4Accum objects.
** The content to returned is determined by the parameter J
** which is one of the STAT_GET_xxxx values defined above.
**
** If neither STAT3 nor STAT4 are enabled, then J is always
** STAT_GET_STAT1 and is hence omitted and this routine becomes
** a one-parameter function, stat_get(P), that always returns the
** stat1 table entry information.
*/

  iTabCur = iTab++;
  iIdxCur = iTab++;
  pParse->nTab = MAX(pParse->nTab, iTab);
  sqlite3OpenTable(pParse, iTabCur, iDb, pTab, OP_OpenRead);
  sqlite3VdbeAddOp4(v, OP_String8, 0, regTabname, 0, pTab->zName, 0);

  for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
    int nCol;                     /* Number of columns in pIdx. "N" */

    int addrRewind;               /* Address of "OP_Rewind iIdxCur" */

    int addrNextRow;              /* Address of "next_row:" */
    const char *zIdxName;         /* Name of the index */
    int nColTest;                 /* Number of columns to test for changes */

    if( pOnlyIdx && pOnlyIdx!=pIdx ) continue;
    if( pIdx->pPartIdxWhere==0 ) needTableCnt = 0;
    if( !HasRowid(pTab) && IsPrimaryKeyIndex(pIdx) ){
      nCol = pIdx->nKeyCol;
      zIdxName = pTab->zName;
      nColTest = nCol - 1;
    }else{
      nCol = pIdx->nColumn;
      zIdxName = pIdx->zName;
      nColTest = pIdx->uniqNotNull ? pIdx->nKeyCol-1 : nCol-1;
    }



    /* Populate the register containing the index name. */
    sqlite3VdbeAddOp4(v, OP_String8, 0, regIdxname, 0, zIdxName, 0);
    VdbeComment((v, "Analysis for %s.%s", pTab->zName, zIdxName));

    /*
    ** Pseudo-code for loop that calls stat_push():

    **
    **  chng_addr_0:
    **   regPrev(0) = idx(0)
    **  chng_addr_1:
    **   regPrev(1) = idx(1)
    **  ...
    **
    **  endDistinctTest:
    **   regRowid = idx(rowid)
    **   stat_push(P, regChng, regRowid)
    **   Next csr
    **   if !eof(csr) goto next_row;
    **
    **  end_of_scan:
    */

    /* Make sure there are enough memory cells allocated to accommodate 
    ** the regPrev array and a trailing rowid (the rowid slot is required
    ** when building a record to insert into the sample column of 
    ** the sqlite_stat4 table.  */
    pParse->nMem = MAX(pParse->nMem, regPrev+nColTest);

    /* Open a read-only cursor on the index being analyzed. */
    assert( iDb==sqlite3SchemaToIndex(db, pIdx->pSchema) );
    sqlite3VdbeAddOp3(v, OP_OpenRead, iIdxCur, pIdx->tnum, iDb);
    sqlite3VdbeSetP4KeyInfo(pParse, pIdx);
    VdbeComment((v, "%s", pIdx->zName));

    /* Invoke the stat_init() function. The arguments are:
    ** 
    **    (1) the number of columns in the index including the rowid
    **        (or for a WITHOUT ROWID table, the number of PK columns),
    **    (2) the number of columns in the key without the rowid/pk
    **    (3) the number of rows in the index,
    **
    **
    ** The third argument is only used for STAT3 and STAT4
    */
#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
    sqlite3VdbeAddOp2(v, OP_Count, iIdxCur, regStat4+3);
#endif
    sqlite3VdbeAddOp2(v, OP_Integer, nCol, regStat4+1);
    sqlite3VdbeAddOp2(v, OP_Integer, pIdx->nKeyCol, regStat4+2);
    sqlite3VdbeAddOp3(v, OP_Function, 0, regStat4+1, regStat4);

    **   regChng = 0
    **   goto next_push_0;
    **
    */
    addrRewind = sqlite3VdbeAddOp1(v, OP_Rewind, iIdxCur);
    VdbeCoverage(v);
    sqlite3VdbeAddOp2(v, OP_Integer, 0, regChng);












    addrNextRow = sqlite3VdbeCurrentAddr(v);

    if( nColTest>0 ){
      int endDistinctTest = sqlite3VdbeMakeLabel(v);
      int *aGotoChng;               /* Array of jump instruction addresses */
      aGotoChng = sqlite3DbMallocRaw(db, sizeof(int)*nColTest);
      if( aGotoChng==0 ) continue;

      /*
      **  next_row:
      **   regChng = 0
      **   if( idx(0) != regPrev(0) ) goto chng_addr_0
      **   regChng = 1
      **   if( idx(1) != regPrev(1) ) goto chng_addr_1
      **   ...
      **   regChng = N
      **   goto endDistinctTest
      */
      sqlite3VdbeAddOp0(v, OP_Goto);
      addrNextRow = sqlite3VdbeCurrentAddr(v);
      if( nColTest==1 && pIdx->nKeyCol==1 && IsUniqueIndex(pIdx) ){
        /* For a single-column UNIQUE index, once we have found a non-NULL
        ** row, we know that all the rest will be distinct, so skip 
        ** subsequent distinctness tests. */
        sqlite3VdbeAddOp2(v, OP_NotNull, regPrev, endDistinctTest);
        VdbeCoverage(v);
      }
      for(i=0; i<nColTest; i++){
        char *pColl = (char*)sqlite3LocateCollSeq(pParse, pIdx->azColl[i]);
        sqlite3VdbeAddOp2(v, OP_Integer, i, regChng);
        sqlite3VdbeAddOp3(v, OP_Column, iIdxCur, i, regTemp);
        aGotoChng[i] = 
        sqlite3VdbeAddOp4(v, OP_Ne, regTemp, 0, regPrev+i, pColl, P4_COLLSEQ);
        sqlite3VdbeChangeP5(v, SQLITE_NULLEQ);
        VdbeCoverage(v);
      }
      sqlite3VdbeAddOp2(v, OP_Integer, nColTest, regChng);
      sqlite3VdbeAddOp2(v, OP_Goto, 0, endDistinctTest);
  
  
      /*
      **  chng_addr_0:
      **   regPrev(0) = idx(0)
      **  chng_addr_1:
      **   regPrev(1) = idx(1)
      **  ...
      */
      sqlite3VdbeJumpHere(v, addrNextRow-1);
      for(i=0; i<nColTest; i++){
        sqlite3VdbeJumpHere(v, aGotoChng[i]);
        sqlite3VdbeAddOp3(v, OP_Column, iIdxCur, i, regPrev+i);
      }
      sqlite3VdbeResolveLabel(v, endDistinctTest);
      sqlite3DbFree(db, aGotoChng);
    }
  
    /*
    **  chng_addr_N:
    **   regRowid = idx(rowid)            // STAT34 only
    **   stat_push(P, regChng, regRowid)  // 3rd parameter STAT34 only
    **   Next csr
    **   if !eof(csr) goto next_row;
    */

#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
    assert( regRowid==(regStat4+2) );
    if( HasRowid(pTab) ){
      sqlite3VdbeAddOp2(v, OP_IdxRowid, iIdxCur, regRowid);
    }else{
      Index *pPk = sqlite3PrimaryKeyIndex(pIdx->pTable);
      int j, k, regKey;

      sqlite3VdbeAddOp2(v, OP_Goto, 1, addrNext); /* P1==1 for end-of-loop */
      sqlite3VdbeJumpHere(v, addrIsNull);
    }
#endif /* SQLITE_ENABLE_STAT3_OR_STAT4 */

    /* End of analysis */
    sqlite3VdbeJumpHere(v, addrRewind);

  }


  /* Create a single sqlite_stat1 entry containing NULL as the index
  ** name and the row count as the content.
  */
  if( pOnlyIdx==0 && needTableCnt ){

  int i = sqlite3FindDbName(pDb, zDb);

  if( i==1 ){
    Parse *pParse;
    int rc = 0;
    pParse = sqlite3StackAllocZero(pErrorDb, sizeof(*pParse));
    if( pParse==0 ){
      sqlite3ErrorWithMsg(pErrorDb, SQLITE_NOMEM, "out of memory");
      rc = SQLITE_NOMEM;
    }else{
      pParse->db = pDb;
      if( sqlite3OpenTempDatabase(pParse) ){
        sqlite3ErrorWithMsg(pErrorDb, pParse->rc, "%s", pParse->zErrMsg);
        rc = SQLITE_ERROR;
      }
      sqlite3DbFree(pErrorDb, pParse->zErrMsg);
      sqlite3ParserReset(pParse);
      sqlite3StackFree(pErrorDb, pParse);
    }
    if( rc ){
      return 0;
    }
  }

  if( i<0 ){
    sqlite3ErrorWithMsg(pErrorDb, SQLITE_ERROR, "unknown database %s", zDb);
    return 0;
  }

  return pDb->aDb[i].pBt;
}

/*

  ** database connection while a backup is in progress may cause
  ** a malfunction or a deadlock.
  */
  sqlite3_mutex_enter(pSrcDb->mutex);
  sqlite3_mutex_enter(pDestDb->mutex);

  if( pSrcDb==pDestDb ){
    sqlite3ErrorWithMsg(
        pDestDb, SQLITE_ERROR, "source and destination must be distinct"
    );
    p = 0;
  }else {
    /* Allocate space for a new sqlite3_backup object...
    ** EVIDENCE-OF: R-64852-21591 The sqlite3_backup object is created by a
    ** call to sqlite3_backup_init() and is destroyed by a call to
    ** sqlite3_backup_finish(). */
    p = (sqlite3_backup *)sqlite3MallocZero(sizeof(sqlite3_backup));
    if( !p ){
      sqlite3Error(pDestDb, SQLITE_NOMEM);
    }
  }

  /* If the allocation succeeded, populate the new object. */
  if( p ){
    p->pSrc = findBtree(pDestDb, pSrcDb, zSrcDb);
    p->pDest = findBtree(pDestDb, pDestDb, zDestDb);

  /* If a transaction is still open on the Btree, roll it back. */
  sqlite3BtreeRollback(p->pDest, SQLITE_OK);

  /* Set the error code of the destination database handle. */
  rc = (p->rc==SQLITE_DONE) ? SQLITE_OK : p->rc;
  if( p->pDestDb ){
    sqlite3Error(p->pDestDb, rc);

    /* Exit the mutexes and free the backup context structure. */
    sqlite3LeaveMutexAndCloseZombie(p->pDestDb);
  }
  sqlite3BtreeLeave(p->pSrc);
  if( p->pDestDb ){
    /* EVIDENCE-OF: R-64852-21591 The sqlite3_backup object is created by a

  p->locked = 1;
}

/*
** Release the BtShared mutex associated with B-Tree handle p and
** clear the p->locked boolean.
*/
static void SQLITE_NOINLINE unlockBtreeMutex(Btree *p){
  BtShared *pBt = p->pBt;
  assert( p->locked==1 );
  assert( sqlite3_mutex_held(pBt->mutex) );
  assert( sqlite3_mutex_held(p->db->mutex) );
  assert( p->db==pBt->db );

  sqlite3_mutex_leave(pBt->mutex);
  p->locked = 0;
}

/* Forward reference */
static void SQLITE_NOINLINE btreeLockCarefully(Btree *p);

/*
** Enter a mutex on the given BTree object.
**
** If the object is not sharable, then no mutex is ever required
** and this routine is a no-op.  The underlying mutex is non-recursive.
** But we keep a reference count in Btree.wantToLock so the behavior
** of this interface is recursive.
**
** To avoid deadlocks, multiple Btrees are locked in the same order
** by all database connections.  The p->pNext is a list of other
** Btrees belonging to the same database connection as the p Btree
** which need to be locked after p.  If we cannot get a lock on
** p, then first unlock all of the others on p->pNext, then wait
** for the lock to become available on p, then relock all of the
** subsequent Btrees that desire a lock.
*/
void sqlite3BtreeEnter(Btree *p){


  /* Some basic sanity checking on the Btree.  The list of Btrees
  ** connected by pNext and pPrev should be in sorted order by
  ** Btree.pBt value. All elements of the list should belong to
  ** the same connection. Only shared Btrees are on the list. */
  assert( p->pNext==0 || p->pNext->pBt>p->pBt );
  assert( p->pPrev==0 || p->pPrev->pBt<p->pBt );
  assert( p->pNext==0 || p->pNext->db==p->db );

  /* Unless the database is sharable and unlocked, then BtShared.db
  ** should already be set correctly. */
  assert( (p->locked==0 && p->sharable) || p->pBt->db==p->db );

  if( !p->sharable ) return;
  p->wantToLock++;
  if( p->locked ) return;
  btreeLockCarefully(p);
}

/* This is a helper function for sqlite3BtreeLock(). By moving
** complex, but seldom used logic, out of sqlite3BtreeLock() and
** into this routine, we avoid unnecessary stack pointer changes
** and thus help the sqlite3BtreeLock() routine to run much faster
** in the common case.
*/
static void SQLITE_NOINLINE btreeLockCarefully(Btree *p){
  Btree *pLater;

  /* In most cases, we should be able to acquire the lock we
  ** want without having to go throught the ascending lock
  ** procedure that follows.  Just be sure not to block.
  */
  if( sqlite3_mutex_try(p->pBt->mutex)==SQLITE_OK ){
    p->pBt->db = p->db;

  lockBtreeMutex(p);
  for(pLater=p->pNext; pLater; pLater=pLater->pNext){
    if( pLater->wantToLock ){
      lockBtreeMutex(pLater);
    }
  }
}


/*
** Exit the recursive mutex on a Btree.
*/
void sqlite3BtreeLeave(Btree *p){
  if( p->sharable ){
    assert( p->wantToLock>0 );

  }

  /* If the client is reading  or writing an index and the schema is
  ** not loaded, then it is too difficult to actually check to see if
  ** the correct locks are held.  So do not bother - just return true.
  ** This case does not come up very often anyhow.
  */
  if( isIndex && (!pSchema || (pSchema->schemaFlags&DB_SchemaLoaded)==0) ){
    return 1;
  }

  /* Figure out the root-page that the lock should be held on. For table
  ** b-trees, this is just the root page of the b-tree being read or
  ** written. For index b-trees, it is the root page of the associated
  ** table.  */

    pCur->eState = CURSOR_REQUIRESEEK;
  }

  invalidateOverflowCache(pCur);
  return rc;
}

/* Forward reference */
static int SQLITE_NOINLINE saveCursorsOnList(BtCursor*,Pgno,BtCursor*);

/*
** Save the positions of all cursors (except pExcept) that are open on
** the table with root-page iRoot.  "Saving the cursor position" means that
** the location in the btree is remembered in such a way that it can be
** moved back to the same spot after the btree has been modified.  This
** routine is called just before cursor pExcept is used to modify the
** table, for example in BtreeDelete() or BtreeInsert().
**
** Implementation note:  This routine merely checks to see if any cursors
** need to be saved.  It calls out to saveCursorsOnList() in the (unusual)
** event that cursors are in need to being saved.
*/
static int saveAllCursors(BtShared *pBt, Pgno iRoot, BtCursor *pExcept){
  BtCursor *p;
  assert( sqlite3_mutex_held(pBt->mutex) );
  assert( pExcept==0 || pExcept->pBt==pBt );
  for(p=pBt->pCursor; p; p=p->pNext){
    if( p!=pExcept && (0==iRoot || p->pgnoRoot==iRoot) ) break;
  }
  return p ? saveCursorsOnList(p, iRoot, pExcept) : SQLITE_OK;
}

/* This helper routine to saveAllCursors does the actual work of saving
** the cursors if and when a cursor is found that actually requires saving.
** The common case is that no cursors need to be saved, so this routine is
** broken out from its caller to avoid unnecessary stack pointer movement.
*/
static int SQLITE_NOINLINE saveCursorsOnList(
  BtCursor *p,           /* The first cursor that needs saving */
  Pgno iRoot,            /* Only save cursor with this iRoot.  Save all if zero */
  BtCursor *pExcept      /* Do not save this cursor */
){
  do{
    if( p!=pExcept && (0==iRoot || p->pgnoRoot==iRoot) ){
      if( p->eState==CURSOR_VALID ){
        int rc = saveCursorPosition(p);
        if( SQLITE_OK!=rc ){
          return rc;
        }
      }else{
        testcase( p->iPage>0 );
        btreeReleaseAllCursorPages(p);
      }
    }
    p = p->pNext;
  }while( p );
  return SQLITE_OK;
}

/*
** Clear the current cursor position.
*/
void sqlite3BtreeClearCursor(BtCursor *pCur){

#define restoreCursorPosition(p) \
  (p->eState>=CURSOR_REQUIRESEEK ? \
         btreeRestoreCursorPosition(p) : \
         SQLITE_OK)

/*
** Determine whether or not a cursor has moved from the position where
** it was last placed, or has been invalidated for any other reason.
** Cursors can move when the row they are pointing at is deleted out
** from under them, for example.  Cursor might also move if a btree
** is rebalanced.
**
** Calling this routine with a NULL cursor pointer returns false.

**
** Use the separate sqlite3BtreeCursorRestore() routine to restore a cursor

** back to where it ought to be if this routine returns true.
*/
int sqlite3BtreeCursorHasMoved(BtCursor *pCur){
  return pCur && pCur->eState!=CURSOR_VALID;
}


/*
** This routine restores a cursor back to its original position after it
** has been moved by some outside activity (such as a btree rebalance or
** a row having been deleted out from under the cursor).  
**
** On success, the *pDifferentRow parameter is false if the cursor is left
** pointing at exactly the same row.  *pDifferntRow is the row the cursor
** was pointing to has been deleted, forcing the cursor to point to some
** nearby row.
**
** This routine should only be called for a cursor that just returned
** TRUE from sqlite3BtreeCursorHasMoved().
*/
int sqlite3BtreeCursorRestore(BtCursor *pCur, int *pDifferentRow){
  int rc;

  assert( pCur!=0 );
  assert( pCur->eState!=CURSOR_VALID );



  rc = restoreCursorPosition(pCur);
  if( rc ){
    *pDifferentRow = 1;
    return rc;
  }
  if( pCur->eState!=CURSOR_VALID || NEVER(pCur->skipNext!=0) ){
    *pDifferentRow = 1;
  }else{
    *pDifferentRow = 0;
  }
  return SQLITE_OK;
}

#ifndef SQLITE_OMIT_AUTOVACUUM
/*
** Given a page number of a regular database page, return the page

** the first two bytes past the cell pointer area since presumably this
** allocation is being made in order to insert a new cell, so we will
** also end up needing a new cell pointer.
*/
static int allocateSpace(MemPage *pPage, int nByte, int *pIdx){
  const int hdr = pPage->hdrOffset;    /* Local cache of pPage->hdrOffset */
  u8 * const data = pPage->aData;      /* Local cache of pPage->aData */

  int top;                             /* First byte of cell content area */
  int gap;        /* First byte of gap between cell pointers and cell content */
  int rc;         /* Integer return code */
  int usableSize; /* Usable size of the page */
  
  assert( sqlite3PagerIswriteable(pPage->pDbPage) );
  assert( pPage->pBt );
  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
  assert( nByte>=0 );  /* Minimum cell size is 4 */
  assert( pPage->nFree>=nByte );
  assert( pPage->nOverflow==0 );
  usableSize = pPage->pBt->usableSize;
  assert( nByte < usableSize-8 );


  assert( pPage->cellOffset == hdr + 12 - 4*pPage->leaf );
  gap = pPage->cellOffset + 2*pPage->nCell;
  assert( gap<=65536 );
  top = get2byte(&data[hdr+5]);
  if( gap>top ){
    if( top==0 ){
      top = 65536;
    }else{
      return SQLITE_CORRUPT_BKPT;
    }
  }



  /* If there is enough space between gap and top for one more cell pointer
  ** array entry offset, and if the freelist is not empty, then search the

  ** freelist looking for a free slot big enough to satisfy the request.


  */
  testcase( gap+2==top );
  testcase( gap+1==top );
  testcase( gap==top );
  if( gap+2<=top && (data[hdr+1] || data[hdr+2]) ){
    int pc, addr;
    for(addr=hdr+1; (pc = get2byte(&data[addr]))>0; addr=pc){
      int size;            /* Size of the free slot */
      if( pc>usableSize-4 || pc<addr+4 ){
        return SQLITE_CORRUPT_BKPT;
      }
      size = get2byte(&data[pc+2]);
      if( size>=nByte ){
        int x = size - nByte;
        testcase( x==4 );
        testcase( x==3 );
        if( x<4 ){
          if( data[hdr+7]>=60 ) goto defragment_page;
          /* Remove the slot from the free-list. Update the number of
          ** fragmented bytes within the page. */
          memcpy(&data[addr], &data[pc], 2);
          data[hdr+7] += (u8)x;
        }else if( size+pc > usableSize ){
          return SQLITE_CORRUPT_BKPT;
        }else{
          /* The slot remains on the free-list. Reduce its size to account
          ** for the portion used by the new allocation. */
          put2byte(&data[pc+2], x);
        }
        *pIdx = pc + x;
        return SQLITE_OK;
      }
    }
  }

  /* The request could not be fulfilled using a freelist slot.  Check
  ** to see if defragmentation is necessary.
  */
  testcase( gap+2+nByte==top );
  if( gap+2+nByte>top ){
defragment_page:
    testcase( pPage->nCell==0 );
    rc = defragmentPage(pPage);
    if( rc ) return rc;
    top = get2byteNotZero(&data[hdr+5]);
    assert( gap+nByte<=top );
  }

  assert( top+nByte <= (int)pPage->pBt->usableSize );
  *pIdx = top;
  return SQLITE_OK;
}

/*
** Return a section of the pPage->aData to the freelist.
** The first byte of the new free block is pPage->aData[iStart]
** and the size of the block is iSize bytes.
**
** Adjacent freeblocks are coalesced.
**
** Note that even though the freeblock list was checked by btreeInitPage(),
** that routine will not detect overlap between cells or freeblocks.  Nor
** does it detect cells or freeblocks that encrouch into the reserved bytes
** at the end of the page.  So do additional corruption checks inside this
** routine and return SQLITE_CORRUPT if any problems are found.
*/
static int freeSpace(MemPage *pPage, u16 iStart, u16 iSize){
  u16 iPtr;                             /* Address of pointer to next freeblock */
  u16 iFreeBlk;                         /* Address of the next freeblock */
  u8 hdr;                               /* Page header size.  0 or 100 */
  u8 nFrag = 0;                         /* Reduction in fragmentation */
  u16 iOrigSize = iSize;                /* Original value of iSize */
  u32 iLast = pPage->pBt->usableSize-4; /* Largest possible freeblock offset */
  u32 iEnd = iStart + iSize;            /* First byte past the iStart buffer */
  unsigned char *data = pPage->aData;   /* Page content */

  assert( pPage->pBt!=0 );
  assert( sqlite3PagerIswriteable(pPage->pDbPage) );
  assert( iStart>=pPage->hdrOffset+6+pPage->childPtrSize );
  assert( iEnd <= pPage->pBt->usableSize );
  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
  assert( iSize>=4 );   /* Minimum cell size is 4 */
  assert( iStart<=iLast );


  /* Overwrite deleted information with zeros when the secure_delete
  ** option is enabled */
  if( pPage->pBt->btsFlags & BTS_SECURE_DELETE ){
    memset(&data[iStart], 0, iSize);
  }

  /* The list of freeblocks must be in ascending order.  Find the 






  ** spot on the list where iStart should be inserted.
  */
  hdr = pPage->hdrOffset;
  iPtr = hdr + 1;
  if( data[iPtr+1]==0 && data[iPtr]==0 ){
    iFreeBlk = 0;  /* Shortcut for the case when the freelist is empty */
  }else{
    while( (iFreeBlk = get2byte(&data[iPtr]))>0 && iFreeBlk<iStart ){

      if( iFreeBlk<iPtr+4 ) return SQLITE_CORRUPT_BKPT;

      iPtr = iFreeBlk;
    }

    if( iFreeBlk>iLast ) return SQLITE_CORRUPT_BKPT;
    assert( iFreeBlk>iPtr || iFreeBlk==0 );
  
    /* At this point:
    **    iFreeBlk:   First freeblock after iStart, or zero if none
    **    iPtr:       The address of a pointer iFreeBlk
    **
    ** Check to see if iFreeBlk should be coalesced onto the end of iStart.
    */
    if( iFreeBlk && iEnd+3>=iFreeBlk ){
      nFrag = iFreeBlk - iEnd;
      if( iEnd>iFreeBlk ) return SQLITE_CORRUPT_BKPT;
      iEnd = iFreeBlk + get2byte(&data[iFreeBlk+2]);
      iSize = iEnd - iStart;
      iFreeBlk = get2byte(&data[iFreeBlk]);
    }
  
    /* If iPtr is another freeblock (that is, if iPtr is not the freelist pointer
    ** in the page header) then check to see if iStart should be coalesced 
    ** onto the end of iPtr.
    */
    if( iPtr>hdr+1 ){




      int iPtrEnd = iPtr + get2byte(&data[iPtr+2]);

      if( iPtrEnd+3>=iStart ){


        if( iPtrEnd>iStart ) return SQLITE_CORRUPT_BKPT;
        nFrag += iStart - iPtrEnd;
        iSize = iEnd - iPtr;
        iStart = iPtr;
      }
    }
    if( nFrag>data[hdr+7] ) return SQLITE_CORRUPT_BKPT;
    data[hdr+7] -= nFrag;
  }
  if( iStart==get2byte(&data[hdr+5]) ){
    /* The new freeblock is at the beginning of the cell content area,
    ** so just extend the cell content area rather than create another
    ** freelist entry */
    if( iPtr!=hdr+1 ) return SQLITE_CORRUPT_BKPT;
    put2byte(&data[hdr+1], iFreeBlk);

    put2byte(&data[hdr+5], iEnd);
  }else{



    /* Insert the new freeblock into the freelist */



    put2byte(&data[iPtr], iStart);

    put2byte(&data[iStart], iFreeBlk);
    put2byte(&data[iStart+2], iSize);
  }
  pPage->nFree += iOrigSize;
  return SQLITE_OK;
}

/*
** Decode the flags byte (the first byte of the header) for a page
** and initialize fields of the MemPage structure accordingly.
**

*/
static Pgno btreePagecount(BtShared *pBt){
  return pBt->nPage;
}
u32 sqlite3BtreeLastPage(Btree *p){
  assert( sqlite3BtreeHoldsMutex(p) );
  assert( ((p->pBt->nPage)&0x8000000)==0 );
  return btreePagecount(p->pBt);
}

/*
** Get a page from the pager and initialize it.  This routine is just a
** convenience wrapper around separate calls to btreeGetPage() and 
** btreeInitPage().
**

  int cellOffset;   /* Address of first cell pointer in data[] */
  u8 *data;         /* The content of the whole page */
  int nSkip = (iChild ? 4 : 0);

  if( *pRC ) return;

  assert( i>=0 && i<=pPage->nCell+pPage->nOverflow );
  assert( MX_CELL(pPage->pBt)<=10921 );
  assert( pPage->nCell<=MX_CELL(pPage->pBt) || CORRUPT_DB );
  assert( pPage->nOverflow<=ArraySize(pPage->apOvfl) );
  assert( ArraySize(pPage->apOvfl)==ArraySize(pPage->aiOvfl) );
  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
  /* The cell should normally be sized correctly.  However, when moving a
  ** malformed cell from a leaf page to an interior page, if the cell size
  ** wanted to be less than 4 but got rounded up to 4 on the leaf, then size
  ** might be less than 8 (leaf-size + pointer) on the interior node.  Hence

int sqlite3BtreeMovetoUnpacked(
  BtCursor*,
  UnpackedRecord *pUnKey,
  i64 intKey,
  int bias,
  int *pRes
);
int sqlite3BtreeCursorHasMoved(BtCursor*);
int sqlite3BtreeCursorRestore(BtCursor*, int*);
int sqlite3BtreeDelete(BtCursor*);
int sqlite3BtreeInsert(BtCursor*, const void *pKey, i64 nKey,
                                  const void *pData, int nData,
                                  int nZero, int bias, int seekResult);
int sqlite3BtreeFirst(BtCursor*, int *pRes);
int sqlite3BtreeLast(BtCursor*, int *pRes);
int sqlite3BtreeNext(BtCursor*, int *pRes);

** auxiliary databases added using the ATTACH command.
**
** See also sqlite3LocateTable().
*/
Table *sqlite3FindTable(sqlite3 *db, const char *zName, const char *zDatabase){
  Table *p = 0;
  int i;

  assert( zName!=0 );

  /* All mutexes are required for schema access.  Make sure we hold them. */
  assert( zDatabase!=0 || sqlite3BtreeHoldsAllMutexes(db) );
  for(i=OMIT_TEMPDB; i<db->nDb; i++){
    int j = (i<2) ? i^1 : i;   /* Search TEMP before MAIN */
    if( zDatabase!=0 && sqlite3StrICmp(zDatabase, db->aDb[j].zName) ) continue;
    assert( sqlite3SchemaMutexHeld(db, j, 0) );
    p = sqlite3HashFind(&db->aDb[j].pSchema->tblHash, zName);
    if( p ) break;
  }
  return p;
}

/*
** Locate the in-memory structure that describes a particular database

** for duplicate index names is done.)  The search order is
** TEMP first, then MAIN, then any auxiliary databases added
** using the ATTACH command.
*/
Index *sqlite3FindIndex(sqlite3 *db, const char *zName, const char *zDb){
  Index *p = 0;
  int i;

  /* All mutexes are required for schema access.  Make sure we hold them. */
  assert( zDb!=0 || sqlite3BtreeHoldsAllMutexes(db) );
  for(i=OMIT_TEMPDB; i<db->nDb; i++){
    int j = (i<2) ? i^1 : i;  /* Search TEMP before MAIN */
    Schema *pSchema = db->aDb[j].pSchema;
    assert( pSchema );
    if( zDb && sqlite3StrICmp(zDb, db->aDb[j].zName) ) continue;
    assert( sqlite3SchemaMutexHeld(db, j, 0) );
    p = sqlite3HashFind(&pSchema->idxHash, zName);
    if( p ) break;
  }
  return p;
}

/*
** Reclaim the memory used by an index

** For the index called zIdxName which is found in the database iDb,
** unlike that index from its Table then remove the index from
** the index hash table and free all memory structures associated
** with the index.
*/
void sqlite3UnlinkAndDeleteIndex(sqlite3 *db, int iDb, const char *zIdxName){
  Index *pIndex;

  Hash *pHash;

  assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
  pHash = &db->aDb[iDb].pSchema->idxHash;

  pIndex = sqlite3HashInsert(pHash, zIdxName, 0);
  if( ALWAYS(pIndex) ){
    if( pIndex->pTable->pIndex==pIndex ){
      pIndex->pTable->pIndex = pIndex->pNext;
    }else{
      Index *p;
      /* Justification of ALWAYS();  The index must be on the list of
      ** indices. */

  /* Delete all indices associated with this table. */
  for(pIndex = pTable->pIndex; pIndex; pIndex=pNext){
    pNext = pIndex->pNext;
    assert( pIndex->pSchema==pTable->pSchema );
    if( !db || db->pnBytesFreed==0 ){
      char *zName = pIndex->zName; 
      TESTONLY ( Index *pOld = ) sqlite3HashInsert(
         &pIndex->pSchema->idxHash, zName, 0
      );
      assert( db==0 || sqlite3SchemaMutexHeld(db, 0, pIndex->pSchema) );
      assert( pOld==pIndex || pOld==0 );
    }
    freeIndex(db, pIndex);
  }

  assert( db!=0 );
  assert( iDb>=0 && iDb<db->nDb );
  assert( zTabName );
  assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
  testcase( zTabName[0]==0 );  /* Zero-length table names are allowed */
  pDb = &db->aDb[iDb];
  p = sqlite3HashInsert(&pDb->pSchema->tblHash, zTabName, 0);

  sqlite3DeleteTable(db, p);
  db->flags |= SQLITE_InternChanges;
}

/*
** Given a token, return a string that consists of the text of that
** token.  Space to hold the returned string

  /* Add the table to the in-memory representation of the database.
  */
  if( db->init.busy ){
    Table *pOld;
    Schema *pSchema = p->pSchema;
    assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
    pOld = sqlite3HashInsert(&pSchema->tblHash, p->zName, p);

    if( pOld ){
      assert( p==pOld );  /* Malloc must have failed inside HashInsert() */
      db->mallocFailed = 1;
      return;
    }
    pParse->pNewTable = 0;
    db->flags |= SQLITE_InternChanges;

      assert( pTable->aCol==0 );
      pTable->nCol = pSelTab->nCol;
      pTable->aCol = pSelTab->aCol;
      pSelTab->nCol = 0;
      pSelTab->aCol = 0;
      sqlite3DeleteTable(db, pSelTab);
      assert( sqlite3SchemaMutexHeld(db, 0, pTable->pSchema) );
      pTable->pSchema->schemaFlags |= DB_UnresetViews;
    }else{
      pTable->nCol = 0;
      nErr++;
    }
    sqlite3SelectDelete(db, pSel);
  } else {
    nErr++;

  }
  pFKey->isDeferred = 0;
  pFKey->aAction[0] = (u8)(flags & 0xff);            /* ON DELETE action */
  pFKey->aAction[1] = (u8)((flags >> 8 ) & 0xff);    /* ON UPDATE action */

  assert( sqlite3SchemaMutexHeld(db, 0, p->pSchema) );
  pNextTo = (FKey *)sqlite3HashInsert(&p->pSchema->fkeyHash, 
      pFKey->zTo, (void *)pFKey
  );
  if( pNextTo==pFKey ){
    db->mallocFailed = 1;
    goto fk_end;
  }
  if( pNextTo ){
    assert( pNextTo->pPrevTo==0 );

  if( memRootPage<0 ) sqlite3VdbeAddOp2(v, OP_Clear, tnum, iDb);
  sqlite3VdbeAddOp4(v, OP_OpenWrite, iIdx, tnum, iDb, 
                    (char *)pKey, P4_KEYINFO);
  sqlite3VdbeChangeP5(v, OPFLAG_BULKCSR|((memRootPage>=0)?OPFLAG_P2ISREG:0));

  addr1 = sqlite3VdbeAddOp2(v, OP_SorterSort, iSorter, 0); VdbeCoverage(v);
  assert( pKey!=0 || db->mallocFailed || pParse->nErr );
  if( IsUniqueIndex(pIndex) && pKey!=0 ){
    int j2 = sqlite3VdbeCurrentAddr(v) + 3;
    sqlite3VdbeAddOp2(v, OP_Goto, 0, j2);
    addr2 = sqlite3VdbeCurrentAddr(v);
    sqlite3VdbeAddOp4Int(v, OP_SorterCompare, iSorter, j2, regRecord,
                         pIndex->nKeyCol); VdbeCoverage(v);
    sqlite3UniqueConstraint(pParse, OE_Abort, pIndex);
  }else{
    addr2 = sqlite3VdbeCurrentAddr(v);
  }
  sqlite3VdbeAddOp2(v, OP_SorterData, iSorter, regRecord);
  sqlite3VdbeAddOp3(v, OP_IdxInsert, iIdx, regRecord, 1);
  sqlite3VdbeChangeP5(v, OPFLAG_USESEEKRESULT);

    ** If there are different collating sequences or if the columns of
    ** the constraint occur in different orders, then the constraints are
    ** considered distinct and both result in separate indices.
    */
    Index *pIdx;
    for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
      int k;
      assert( IsUniqueIndex(pIdx) );
      assert( pIdx->idxType!=SQLITE_IDXTYPE_APPDEF );
      assert( IsUniqueIndex(pIndex) );

      if( pIdx->nKeyCol!=pIndex->nKeyCol ) continue;
      for(k=0; k<pIdx->nKeyCol; k++){
        const char *z1;
        const char *z2;
        if( pIdx->aiColumn[k]!=pIndex->aiColumn[k] ) break;
        z1 = pIdx->azColl[k];

  /* Link the new Index structure to its table and to the other
  ** in-memory database structures. 
  */
  if( db->init.busy ){
    Index *p;
    assert( sqlite3SchemaMutexHeld(db, 0, pIndex->pSchema) );
    p = sqlite3HashInsert(&pIndex->pSchema->idxHash, 
                          pIndex->zName, pIndex);

    if( p ){
      assert( p==pIndex );  /* Malloc must have failed */
      db->mallocFailed = 1;
      goto exit_create_index;
    }
    db->flags |= SQLITE_InternChanges;
    if( pTblName!=0 ){

  ** 6 and each subsequent value (if any) is 5.  */
  memcpy(&a[1], aVal, nCopy*sizeof(LogEst));
  for(i=nCopy+1; i<=pIdx->nKeyCol; i++){
    a[i] = 23;                    assert( 23==sqlite3LogEst(5) );
  }

  assert( 0==sqlite3LogEst(1) );
  if( IsUniqueIndex(pIdx) ) a[pIdx->nKeyCol] = 0;
}

/*
** This routine will drop an existing named index.  This routine
** implements the DROP INDEX statement.
*/
void sqlite3DropIndex(Parse *pParse, SrcList *pName, int ifExists){

*/
static CollSeq *findCollSeqEntry(
  sqlite3 *db,          /* Database connection */
  const char *zName,    /* Name of the collating sequence */
  int create            /* Create a new entry if true */
){
  CollSeq *pColl;

  pColl = sqlite3HashFind(&db->aCollSeq, zName);

  if( 0==pColl && create ){
    int nName = sqlite3Strlen30(zName);
    pColl = sqlite3DbMallocZero(db, 3*sizeof(*pColl) + nName + 1);
    if( pColl ){
      CollSeq *pDel = 0;
      pColl[0].zName = (char*)&pColl[3];
      pColl[0].enc = SQLITE_UTF8;
      pColl[1].zName = (char*)&pColl[3];
      pColl[1].enc = SQLITE_UTF16LE;
      pColl[2].zName = (char*)&pColl[3];
      pColl[2].enc = SQLITE_UTF16BE;
      memcpy(pColl[0].zName, zName, nName);
      pColl[0].zName[nName] = 0;
      pDel = sqlite3HashInsert(&db->aCollSeq, pColl[0].zName, pColl);

      /* If a malloc() failure occurred in sqlite3HashInsert(), it will 
      ** return the pColl pointer to be deleted (because it wasn't added
      ** to the hash table).
      */
      assert( pDel==0 || pDel==pColl );
      if( pDel!=0 ){

  for(pElem=sqliteHashFirst(&temp1); pElem; pElem=sqliteHashNext(pElem)){
    Table *pTab = sqliteHashData(pElem);
    sqlite3DeleteTable(0, pTab);
  }
  sqlite3HashClear(&temp1);
  sqlite3HashClear(&pSchema->fkeyHash);
  pSchema->pSeqTab = 0;
  if( pSchema->schemaFlags & DB_SchemaLoaded ){
    pSchema->iGeneration++;
    pSchema->schemaFlags &= ~DB_SchemaLoaded;
  }
}

/*
** Find and return the schema associated with a BTree.  Create
** a new one if necessary.
*/

  
    /* Unless this is a view, open cursors for the table we are 
    ** deleting from and all its indices. If this is a view, then the
    ** only effect this statement has is to fire the INSTEAD OF 
    ** triggers.
    */
    if( !isView ){
      testcase( IsVirtual(pTab) );
      sqlite3OpenTableAndIndices(pParse, pTab, OP_OpenWrite, iTabCur, aToOpen,
                                 &iDataCur, &iIdxCur);
      assert( pPk || IsVirtual(pTab) || iDataCur==iTabCur );
      assert( pPk || IsVirtual(pTab) || iIdxCur==iDataCur+1 );
    }
  
    /* Set up a loop over the rowids/primary-keys that were found in the
    ** where-clause loop above.
    */
    if( okOnePass ){
      /* Just one row.  Hence the top-of-loop is a no-op */
      assert( nKey==nPk );  /* OP_Found will use an unpacked key */
      assert( !IsVirtual(pTab) );
      if( aToOpen[iDataCur-iTabCur] ){
        assert( pPk!=0 );
        sqlite3VdbeAddOp4Int(v, OP_NotFound, iDataCur, addrBypass, iKey, nKey);
        VdbeCoverage(v);
      }
    }else if( pPk ){
      addrLoop = sqlite3VdbeAddOp1(v, OP_Rewind, iEphCur); VdbeCoverage(v);

  if( op==TK_REGISTER ) op = p->op2;
  switch( op ){
    case TK_INTEGER:
    case TK_STRING:
    case TK_FLOAT:
    case TK_BLOB:
      return 0;
    case TK_COLUMN:
      assert( p->pTab!=0 );
      return p->iColumn>=0 && p->pTab->aCol[p->iColumn].notNull==0;
    default:
      return 1;
  }
}

/*
** Return TRUE if the given expression is a constant which would be

** address of the new instruction.
*/
int sqlite3CodeOnce(Parse *pParse){
  Vdbe *v = sqlite3GetVdbe(pParse);      /* Virtual machine being coded */
  return sqlite3VdbeAddOp1(v, OP_Once, pParse->nOnce++);
}

/*
** Generate code that checks the left-most column of index table iCur to see if
** it contains any NULL entries.  Cause the register at regHasNull to be set
** to a non-NULL value if iCur contains no NULLs.  Cause register regHasNull
** to be set to NULL if iCur contains one or more NULL values.
*/
static void sqlite3SetHasNullFlag(Vdbe *v, int iCur, int regHasNull){
  int j1;
  sqlite3VdbeAddOp2(v, OP_Integer, 0, regHasNull);
  j1 = sqlite3VdbeAddOp1(v, OP_Rewind, iCur); VdbeCoverage(v);
  sqlite3VdbeAddOp3(v, OP_Column, iCur, 0, regHasNull);
  sqlite3VdbeChangeP5(v, OPFLAG_TYPEOFARG);
  VdbeComment((v, "first_entry_in(%d)", iCur));
  sqlite3VdbeJumpHere(v, j1);
}


#ifndef SQLITE_OMIT_SUBQUERY
/*
** The argument is an IN operator with a list (not a subquery) on the 
** right-hand side.  Return TRUE if that list is constant.
*/
static int sqlite3InRhsIsConstant(Expr *pIn){
  Expr *pLHS;
  int res;
  assert( !ExprHasProperty(pIn, EP_xIsSelect) );
  pLHS = pIn->pLeft;
  pIn->pLeft = 0;
  res = sqlite3ExprIsConstant(pIn);
  pIn->pLeft = pLHS;
  return res;
}
#endif

/*
** This function is used by the implementation of the IN (...) operator.
** The pX parameter is the expression on the RHS of the IN operator, which
** might be either a list of expressions or a subquery.
**
** The job of this routine is to find or create a b-tree object that can
** be used either to test for membership in the RHS set or to iterate through
** all members of the RHS set, skipping duplicates.
**
** A cursor is opened on the b-tree object that is the RHS of the IN operator
** and pX->iTable is set to the index of that cursor.
**
** The returned value of this function indicates the b-tree type, as follows:
**
**   IN_INDEX_ROWID      - The cursor was opened on a database table.
**   IN_INDEX_INDEX_ASC  - The cursor was opened on an ascending index.
**   IN_INDEX_INDEX_DESC - The cursor was opened on a descending index.
**   IN_INDEX_EPH        - The cursor was opened on a specially created and
**                         populated epheremal table.
**   IN_INDEX_NOOP       - No cursor was allocated.  The IN operator must be
**                         implemented as a sequence of comparisons.
**
** An existing b-tree might be used if the RHS expression pX is a simple
** subquery such as:
**
**     SELECT <column> FROM <table>
**
** If the RHS of the IN operator is a list or a more complex subquery, then
** an ephemeral table might need to be generated from the RHS and then
** pX->iTable made to point to the ephermeral table instead of an
** existing table.
**
** The inFlags parameter must contain exactly one of the bits
** IN_INDEX_MEMBERSHIP or IN_INDEX_LOOP.  If inFlags contains
** IN_INDEX_MEMBERSHIP, then the generated table will be used for a
** fast membership test.  When the IN_INDEX_LOOP bit is set, the
** IN index will be used to loop over all values of the RHS of the
** IN operator.
**
** When IN_INDEX_LOOP is used (and the b-tree will be used to iterate
** through the set members) then the b-tree must not contain duplicates.
** An epheremal table must be used unless the selected <column> is guaranteed
** to be unique - either because it is an INTEGER PRIMARY KEY or it
** has a UNIQUE constraint or UNIQUE index.
**
** When IN_INDEX_MEMBERSHIP is used (and the b-tree will be used 
** for fast set membership tests) then an epheremal table must 
** be used unless <column> is an INTEGER PRIMARY KEY or an index can 
** be found with <column> as its left-most column.
**
** If the IN_INDEX_NOOP_OK and IN_INDEX_MEMBERSHIP are both set and
** if the RHS of the IN operator is a list (not a subquery) then this
** routine might decide that creating an ephemeral b-tree for membership
** testing is too expensive and return IN_INDEX_NOOP.  In that case, the
** calling routine should implement the IN operator using a sequence
** of Eq or Ne comparison operations.
**
** When the b-tree is being used for membership tests, the calling function
** might need to know whether or not the RHS side of the IN operator

** contains a NULL.  If prRhsHasNull is not a NULL pointer and 
** if there is any chance that the (...) might contain a NULL value at
** runtime, then a register is allocated and the register number written
** to *prRhsHasNull. If there is no chance that the (...) contains a
** NULL value, then *prRhsHasNull is left unchanged.
**
** If a register is allocated and its location stored in *prRhsHasNull, then


** the value in that register will be NULL if the b-tree contains one or more




** NULL values, and it will be some non-NULL value if the b-tree contains no

** NULL values.



*/
#ifndef SQLITE_OMIT_SUBQUERY
int sqlite3FindInIndex(Parse *pParse, Expr *pX, u32 inFlags, int *prRhsHasNull){
  Select *p;                            /* SELECT to the right of IN operator */
  int eType = 0;                        /* Type of RHS table. IN_INDEX_* */
  int iTab = pParse->nTab++;            /* Cursor of the RHS table */
  int mustBeUnique;                     /* True if RHS must be unique */
  Vdbe *v = sqlite3GetVdbe(pParse);     /* Virtual machine being coded */

  assert( pX->op==TK_IN );
  mustBeUnique = (inFlags & IN_INDEX_LOOP)!=0;

  /* Check to see if an existing table or index can be used to
  ** satisfy the query.  This is preferable to generating a new 
  ** ephemeral table.
  */
  p = (ExprHasProperty(pX, EP_xIsSelect) ? pX->x.pSelect : 0);
  if( ALWAYS(pParse->nErr==0) && isCandidateForInOpt(p) ){

      ** it is not, it is not possible to use any index.
      */
      int affinity_ok = sqlite3IndexAffinityOk(pX, pTab->aCol[iCol].affinity);

      for(pIdx=pTab->pIndex; pIdx && eType==0 && affinity_ok; pIdx=pIdx->pNext){
        if( (pIdx->aiColumn[0]==iCol)
         && sqlite3FindCollSeq(db, ENC(db), pIdx->azColl[0], 0)==pReq
         && (!mustBeUnique || (pIdx->nKeyCol==1 && IsUniqueIndex(pIdx)))
        ){
          int iAddr = sqlite3CodeOnce(pParse); VdbeCoverage(v);
          sqlite3VdbeAddOp3(v, OP_OpenRead, iTab, pIdx->tnum, iDb);
          sqlite3VdbeSetP4KeyInfo(pParse, pIdx);
          VdbeComment((v, "%s", pIdx->zName));
          assert( IN_INDEX_INDEX_DESC == IN_INDEX_INDEX_ASC+1 );
          eType = IN_INDEX_INDEX_ASC + pIdx->aSortOrder[0];

          if( prRhsHasNull && !pTab->aCol[iCol].notNull ){
            *prRhsHasNull = ++pParse->nMem;
            sqlite3SetHasNullFlag(v, iTab, *prRhsHasNull);
          }
          sqlite3VdbeJumpHere(v, iAddr);
        }
      }
    }
  }

  /* If no preexisting index is available for the IN clause
  ** and IN_INDEX_NOOP is an allowed reply
  ** and the RHS of the IN operator is a list, not a subquery
  ** and the RHS is not contant or has two or fewer terms,
  ** then it is not worth creating an ephermeral table to evaluate
  ** the IN operator so return IN_INDEX_NOOP.
  */
  if( eType==0
   && (inFlags & IN_INDEX_NOOP_OK)
   && !ExprHasProperty(pX, EP_xIsSelect)
   && (!sqlite3InRhsIsConstant(pX) || pX->x.pList->nExpr<=2)
  ){
    eType = IN_INDEX_NOOP;
  }
     

  if( eType==0 ){
    /* Could not find an existing table or index to use as the RHS b-tree.
    ** We will have to generate an ephemeral table to do the job.
    */
    u32 savedNQueryLoop = pParse->nQueryLoop;
    int rMayHaveNull = 0;
    eType = IN_INDEX_EPH;
    if( inFlags & IN_INDEX_LOOP ){



      pParse->nQueryLoop = 0;
      if( pX->pLeft->iColumn<0 && !ExprHasProperty(pX, EP_xIsSelect) ){
        eType = IN_INDEX_ROWID;
      }
    }else if( prRhsHasNull ){
      *prRhsHasNull = rMayHaveNull = ++pParse->nMem;
    }
    sqlite3CodeSubselect(pParse, pX, rMayHaveNull, eType==IN_INDEX_ROWID);
    pParse->nQueryLoop = savedNQueryLoop;
  }else{
    pX->iTable = iTab;
  }
  return eType;

** to be of the form "<rowid> IN (?, ?, ?)", where <rowid> is a reference
** to some integer key column of a table B-Tree. In this case, use an
** intkey B-Tree to store the set of IN(...) values instead of the usual
** (slower) variable length keys B-Tree.
**
** If rMayHaveNull is non-zero, that means that the operation is an IN
** (not a SELECT or EXISTS) and that the RHS might contains NULLs.


** All this routine does is initialize the register given by rMayHaveNull
** to NULL.  Calling routines will take care of changing this register
** value to non-NULL if the RHS is NULL-free.




**
** For a SELECT or EXISTS operator, return the register that holds the
** result.  For IN operators or if an error occurs, the return value is 0.
*/
#ifndef SQLITE_OMIT_SUBQUERY
int sqlite3CodeSubselect(
  Parse *pParse,          /* Parsing context */
  Expr *pExpr,            /* The IN, SELECT, or EXISTS operator */
  int rHasNullFlag,       /* Register that records whether NULLs exist in RHS */
  int isRowid             /* If true, LHS of IN operator is a rowid */
){
  int jmpIfDynamic = -1;                      /* One-time test address */
  int rReg = 0;                           /* Register storing resulting */
  Vdbe *v = sqlite3GetVdbe(pParse);
  if( NEVER(v==0) ) return 0;
  sqlite3ExprCachePush(pParse);

  /* This code must be run in its entirety every time it is encountered
  ** if any of the following is true:
  **
  **    *  The right-hand side is a correlated subquery
  **    *  The right-hand side is an expression list containing variables
  **    *  We are inside a trigger
  **
  ** If all of the above are false, then we can run this code just once
  ** save the results, and reuse the same result on subsequent invocations.
  */
  if( !ExprHasProperty(pExpr, EP_VarSelect) ){
    jmpIfDynamic = sqlite3CodeOnce(pParse); VdbeCoverage(v);
  }

#ifndef SQLITE_OMIT_EXPLAIN
  if( pParse->explain==2 ){
    char *zMsg = sqlite3MPrintf(
        pParse->db, "EXECUTE %s%s SUBQUERY %d", jmpIfDynamic>=0?"":"CORRELATED ",
        pExpr->op==TK_IN?"LIST":"SCALAR", pParse->iNextSelectId
    );
    sqlite3VdbeAddOp4(v, OP_Explain, pParse->iSelectId, 0, 0, zMsg, P4_DYNAMIC);
  }
#endif

  switch( pExpr->op ){
    case TK_IN: {
      char affinity;              /* Affinity of the LHS of the IN */
      int addr;                   /* Address of OP_OpenEphemeral instruction */
      Expr *pLeft = pExpr->pLeft; /* the LHS of the IN operator */
      KeyInfo *pKeyInfo = 0;      /* Key information */





      affinity = sqlite3ExprAffinity(pLeft);

      /* Whether this is an 'x IN(SELECT...)' or an 'x IN(<exprlist>)'
      ** expression it is handled the same way.  An ephemeral table is 
      ** filled with single-field index keys representing the results
      ** from the SELECT or the <exprlist>.
      **

      if( ExprHasProperty(pExpr, EP_xIsSelect) ){
        /* Case 1:     expr IN (SELECT ...)
        **
        ** Generate code to write the results of the select into the temporary
        ** table allocated and opened above.
        */
        Select *pSelect = pExpr->x.pSelect;
        SelectDest dest;
        ExprList *pEList;

        assert( !isRowid );
        sqlite3SelectDestInit(&dest, SRT_Set, pExpr->iTable);
        dest.affSdst = (u8)affinity;
        assert( (pExpr->iTable&0x0000FFFF)==pExpr->iTable );
        pSelect->iLimit = 0;
        testcase( pSelect->selFlags & SF_Distinct );
        pSelect->selFlags &= ~SF_Distinct;
        testcase( pKeyInfo==0 ); /* Caused by OOM in sqlite3KeyInfoAlloc() */
        if( sqlite3Select(pParse, pSelect, &dest) ){
          sqlite3KeyInfoUnref(pKeyInfo);
          return 0;
        }
        pEList = pSelect->pEList;
        assert( pKeyInfo!=0 ); /* OOM will cause exit after sqlite3Select() */
        assert( pEList!=0 );
        assert( pEList->nExpr>0 );
        assert( sqlite3KeyInfoIsWriteable(pKeyInfo) );
        pKeyInfo->aColl[0] = sqlite3BinaryCompareCollSeq(pParse, pExpr->pLeft,
                                                         pEList->a[0].pExpr);
      }else if( ALWAYS(pExpr->x.pList!=0) ){

          assert( sqlite3KeyInfoIsWriteable(pKeyInfo) );
          pKeyInfo->aColl[0] = sqlite3ExprCollSeq(pParse, pExpr->pLeft);
        }

        /* Loop through each expression in <exprlist>. */
        r1 = sqlite3GetTempReg(pParse);
        r2 = sqlite3GetTempReg(pParse);
        if( isRowid ) sqlite3VdbeAddOp2(v, OP_Null, 0, r2);
        for(i=pList->nExpr, pItem=pList->a; i>0; i--, pItem++){
          Expr *pE2 = pItem->pExpr;
          int iValToIns;

          /* If the expression is not constant then we will need to
          ** disable the test that was generated above that makes sure
          ** this code only executes once.  Because for a non-constant
          ** expression we need to rerun this code each time.
          */
          if( jmpIfDynamic>=0 && !sqlite3ExprIsConstant(pE2) ){
            sqlite3VdbeChangeToNoop(v, jmpIfDynamic);
            jmpIfDynamic = -1;
          }

          /* Evaluate the expression and insert it into the temp table */
          if( isRowid && sqlite3ExprIsInteger(pE2, &iValToIns) ){
            sqlite3VdbeAddOp3(v, OP_InsertInt, pExpr->iTable, r2, iValToIns);
          }else{
            r3 = sqlite3ExprCodeTarget(pParse, pE2, r1);

      assert( pExpr->op==TK_EXISTS || pExpr->op==TK_SELECT );

      assert( ExprHasProperty(pExpr, EP_xIsSelect) );
      pSel = pExpr->x.pSelect;
      sqlite3SelectDestInit(&dest, 0, ++pParse->nMem);
      if( pExpr->op==TK_SELECT ){
        dest.eDest = SRT_Mem;
        dest.iSdst = dest.iSDParm;
        sqlite3VdbeAddOp2(v, OP_Null, 0, dest.iSDParm);
        VdbeComment((v, "Init subquery result"));
      }else{
        dest.eDest = SRT_Exists;
        sqlite3VdbeAddOp2(v, OP_Integer, 0, dest.iSDParm);
        VdbeComment((v, "Init EXISTS result"));
      }
      sqlite3ExprDelete(pParse->db, pSel->pLimit);
      pSel->pLimit = sqlite3PExpr(pParse, TK_INTEGER, 0, 0,
                                  &sqlite3IntTokens[1]);
      pSel->iLimit = 0;
      if( sqlite3Select(pParse, pSel, &dest) ){
        return 0;
      }
      rReg = dest.iSDParm;
      ExprSetVVAProperty(pExpr, EP_NoReduce);
      break;
    }
  }

  if( rHasNullFlag ){
    sqlite3SetHasNullFlag(v, pExpr->iTable, rHasNullFlag);
  }

  if( jmpIfDynamic>=0 ){
    sqlite3VdbeJumpHere(v, jmpIfDynamic);
  }
  sqlite3ExprCachePop(pParse);

  return rReg;
}
#endif /* SQLITE_OMIT_SUBQUERY */

#ifndef SQLITE_OMIT_SUBQUERY
/*
** Generate code for an IN expression.
**
**      x IN (SELECT ...)
**      x IN (value, value, ...)
**
** The left-hand side (LHS) is a scalar expression.  The right-hand side (RHS)
** is an array of zero or more values.  The expression is true if the LHS is
** contained within the RHS.  The value of the expression is unknown (NULL)
** if the LHS is NULL or if the LHS is not contained within the RHS and the
** RHS contains one or more NULL values.
**
** This routine generates code that jumps to destIfFalse if the LHS is not 
** contained within the RHS.  If due to NULLs we cannot determine if the LHS
** is contained in the RHS then jump to destIfNull.  If the LHS is contained
** within the RHS then fall through.
*/
static void sqlite3ExprCodeIN(
  Parse *pParse,        /* Parsing and code generating context */
  Expr *pExpr,          /* The IN expression */

  /* Compute the RHS.   After this step, the table with cursor
  ** pExpr->iTable will contains the values that make up the RHS.
  */
  v = pParse->pVdbe;
  assert( v!=0 );       /* OOM detected prior to this routine */
  VdbeNoopComment((v, "begin IN expr"));
  eType = sqlite3FindInIndex(pParse, pExpr,
                             IN_INDEX_MEMBERSHIP | IN_INDEX_NOOP_OK,
                             destIfFalse==destIfNull ? 0 : &rRhsHasNull);

  /* Figure out the affinity to use to create a key from the results
  ** of the expression. affinityStr stores a static string suitable for
  ** P4 of OP_MakeRecord.
  */
  affinity = comparisonAffinity(pExpr);

  /* Code the LHS, the <expr> from "<expr> IN (...)".
  */
  sqlite3ExprCachePush(pParse);
  r1 = sqlite3GetTempReg(pParse);
  sqlite3ExprCode(pParse, pExpr->pLeft, r1);

  /* If sqlite3FindInIndex() did not find or create an index that is
  ** suitable for evaluating the IN operator, then evaluate using a
  ** sequence of comparisons.
  */
  if( eType==IN_INDEX_NOOP ){
    ExprList *pList = pExpr->x.pList;
    CollSeq *pColl = sqlite3ExprCollSeq(pParse, pExpr->pLeft);
    int labelOk = sqlite3VdbeMakeLabel(v);
    int r2, regToFree;
    int regCkNull = 0;
    int ii;
    assert( !ExprHasProperty(pExpr, EP_xIsSelect) );
    if( destIfNull!=destIfFalse ){
      regCkNull = sqlite3GetTempReg(pParse);
      sqlite3VdbeAddOp3(v, OP_BitAnd, r1, r1, regCkNull);
    }
    for(ii=0; ii<pList->nExpr; ii++){
      r2 = sqlite3ExprCodeTemp(pParse, pList->a[ii].pExpr, &regToFree);
      if( regCkNull && sqlite3ExprCanBeNull(pList->a[ii].pExpr) ){
        sqlite3VdbeAddOp3(v, OP_BitAnd, regCkNull, r2, regCkNull);
      }
      if( ii<pList->nExpr-1 || destIfNull!=destIfFalse ){
        sqlite3VdbeAddOp4(v, OP_Eq, r1, labelOk, r2,
                          (void*)pColl, P4_COLLSEQ);
        VdbeCoverageIf(v, ii<pList->nExpr-1);
        VdbeCoverageIf(v, ii==pList->nExpr-1);
        sqlite3VdbeChangeP5(v, affinity);
      }else{
        assert( destIfNull==destIfFalse );
        sqlite3VdbeAddOp4(v, OP_Ne, r1, destIfFalse, r2,
                          (void*)pColl, P4_COLLSEQ); VdbeCoverage(v);
        sqlite3VdbeChangeP5(v, affinity | SQLITE_JUMPIFNULL);
      }
      sqlite3ReleaseTempReg(pParse, regToFree);
    }
    if( regCkNull ){
      sqlite3VdbeAddOp2(v, OP_IsNull, regCkNull, destIfNull); VdbeCoverage(v);
      sqlite3VdbeAddOp2(v, OP_Goto, 0, destIfFalse);
    }
    sqlite3VdbeResolveLabel(v, labelOk);
    sqlite3ReleaseTempReg(pParse, regCkNull);
  }else{
  
    /* If the LHS is NULL, then the result is either false or NULL depending
    ** on whether the RHS is empty or not, respectively.
    */
    if( sqlite3ExprCanBeNull(pExpr->pLeft) ){
      if( destIfNull==destIfFalse ){
        /* Shortcut for the common case where the false and NULL outcomes are
        ** the same. */
        sqlite3VdbeAddOp2(v, OP_IsNull, r1, destIfNull); VdbeCoverage(v);
      }else{
        int addr1 = sqlite3VdbeAddOp1(v, OP_NotNull, r1); VdbeCoverage(v);
        sqlite3VdbeAddOp2(v, OP_Rewind, pExpr->iTable, destIfFalse);
        VdbeCoverage(v);
        sqlite3VdbeAddOp2(v, OP_Goto, 0, destIfNull);
        sqlite3VdbeJumpHere(v, addr1);
      }
    }
  
    if( eType==IN_INDEX_ROWID ){
      /* In this case, the RHS is the ROWID of table b-tree
      */
      sqlite3VdbeAddOp2(v, OP_MustBeInt, r1, destIfFalse); VdbeCoverage(v);
      sqlite3VdbeAddOp3(v, OP_NotExists, pExpr->iTable, destIfFalse, r1);
      VdbeCoverage(v);
    }else{
      /* In this case, the RHS is an index b-tree.
      */
      sqlite3VdbeAddOp4(v, OP_Affinity, r1, 1, 0, &affinity, 1);
  
      /* If the set membership test fails, then the result of the 
      ** "x IN (...)" expression must be either 0 or NULL. If the set
      ** contains no NULL values, then the result is 0. If the set 
      ** contains one or more NULL values, then the result of the
      ** expression is also NULL.
      */
      assert( destIfFalse!=destIfNull || rRhsHasNull==0 );
      if( rRhsHasNull==0 ){
        /* This branch runs if it is known at compile time that the RHS
        ** cannot contain NULL values. This happens as the result
        ** of a "NOT NULL" constraint in the database schema.
        **
        ** Also run this branch if NULL is equivalent to FALSE
        ** for this particular IN operator.
        */
        sqlite3VdbeAddOp4Int(v, OP_NotFound, pExpr->iTable, destIfFalse, r1, 1);
        VdbeCoverage(v);
      }else{
        /* In this branch, the RHS of the IN might contain a NULL and
        ** the presence of a NULL on the RHS makes a difference in the
        ** outcome.
        */
        int j1;
  
        /* First check to see if the LHS is contained in the RHS.  If so,
        ** then the answer is TRUE the presence of NULLs in the RHS does
        ** not matter.  If the LHS is not contained in the RHS, then the
        ** answer is NULL if the RHS contains NULLs and the answer is
        ** FALSE if the RHS is NULL-free.
        */
        j1 = sqlite3VdbeAddOp4Int(v, OP_Found, pExpr->iTable, 0, r1, 1);
        VdbeCoverage(v);







        sqlite3VdbeAddOp2(v, OP_IsNull, rRhsHasNull, destIfNull);


        VdbeCoverage(v);

        sqlite3VdbeAddOp2(v, OP_Goto, 0, destIfFalse);
        sqlite3VdbeJumpHere(v, j1);


      }




    }
  }
  sqlite3ReleaseTempReg(pParse, r1);
  sqlite3ExprCachePop(pParse);
  VdbeComment((v, "end IN expr"));
}
#endif /* SQLITE_OMIT_SUBQUERY */

    case TK_AS: {
      inReg = sqlite3ExprCodeTarget(pParse, pExpr->pLeft, target);
      break;
    }
#ifndef SQLITE_OMIT_CAST
    case TK_CAST: {
      /* Expressions of the form:   CAST(pLeft AS token) */

      inReg = sqlite3ExprCodeTarget(pParse, pExpr->pLeft, target);













      if( inReg!=target ){
        sqlite3VdbeAddOp2(v, OP_SCopy, inReg, target);
        inReg = target;
      }
      sqlite3VdbeAddOp2(v, OP_Cast, target,
                        sqlite3AffinityType(pExpr->u.zToken, 0));
      testcase( usedAsColumnCache(pParse, inReg, inReg) );
      sqlite3ExprCacheAffinityChange(pParse, inReg, 1);
      break;
    }
#endif /* SQLITE_OMIT_CAST */
    case TK_LT:
    case TK_LE:

      assert( TK_NOTNULL==OP_NotNull ); testcase( op==TK_NOTNULL );
      sqlite3VdbeAddOp2(v, OP_Integer, 1, target);
      r1 = sqlite3ExprCodeTemp(pParse, pExpr->pLeft, &regFree1);
      testcase( regFree1==0 );
      addr = sqlite3VdbeAddOp1(v, op, r1);
      VdbeCoverageIf(v, op==TK_ISNULL);
      VdbeCoverageIf(v, op==TK_NOTNULL);
      sqlite3VdbeAddOp2(v, OP_Integer, 0, target);
      sqlite3VdbeJumpHere(v, addr);
      break;
    }
    case TK_AGG_FUNCTION: {
      AggInfo *pInfo = pExpr->pAggInfo;
      if( pInfo==0 ){
        assert( !ExprHasProperty(pExpr, EP_IntValue) );

        pFarg = pExpr->x.pList;
      }
      nFarg = pFarg ? pFarg->nExpr : 0;
      assert( !ExprHasProperty(pExpr, EP_IntValue) );
      zId = pExpr->u.zToken;
      nId = sqlite3Strlen30(zId);
      pDef = sqlite3FindFunction(db, zId, nId, nFarg, enc, 0);
      if( pDef==0 || pDef->xFunc==0 ){
        sqlite3ErrorMsg(pParse, "unknown function: %.*s()", nId, zId);
        break;
      }

      /* Attempt a direct implementation of the built-in COALESCE() and
      ** IFNULL() functions.  This avoids unnecessary evalation of
      ** arguments past the first non-NULL argument.

    assert( nCol>1 );
    aiCol = (int *)sqlite3DbMallocRaw(pParse->db, nCol*sizeof(int));
    if( !aiCol ) return 1;
    *paiCol = aiCol;
  }

  for(pIdx=pParent->pIndex; pIdx; pIdx=pIdx->pNext){
    if( pIdx->nKeyCol==nCol && IsUniqueIndex(pIdx) ){ 
      /* pIdx is a UNIQUE index (or a PRIMARY KEY) and has the right number
      ** of columns. If each indexed column corresponds to a foreign key
      ** column of pFKey, then this index is a winner.  */

      if( zKey==0 ){
        /* If zKey is NULL, then this foreign key is implicitly mapped to 
        ** the PRIMARY KEY of table pParent. The PRIMARY KEY index may be 

** Calling this function with table "t1" as an argument returns a pointer
** to the FKey structure representing the foreign key constraint on table
** "t2". Calling this function with "t2" as the argument would return a
** NULL pointer (as there are no FK constraints for which t2 is the parent
** table).
*/
FKey *sqlite3FkReferences(Table *pTab){

  return (FKey *)sqlite3HashFind(&pTab->pSchema->fkeyHash, pTab->zName);
}

/*
** The second argument is a Trigger structure allocated by the 
** fkActionTrigger() routine. This function deletes the Trigger structure
** and all of its sub-components.
**

    /* Remove the FK from the fkeyHash hash table. */
    if( !db || db->pnBytesFreed==0 ){
      if( pFKey->pPrevTo ){
        pFKey->pPrevTo->pNextTo = pFKey->pNextTo;
      }else{
        void *p = (void *)pFKey->pNextTo;
        const char *z = (p ? pFKey->pNextTo->zTo : pFKey->zTo);
        sqlite3HashInsert(&pTab->pSchema->fkeyHash, z, p);
      }
      if( pFKey->pNextTo ){
        pFKey->pNextTo->pPrevTo = pFKey->pPrevTo;
      }
    }

    /* EV: R-30323-21917 Each foreign key constraint in SQLite is

/*
** 2002 February 23
**
** 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 contains the C-language implementions for many of the SQL
** functions of SQLite.  (Some function, and in particular the date and

** time functions, are implemented separately.)


*/
#include "sqliteInt.h"
#include <stdlib.h>
#include <assert.h>
#include "vdbeInt.h"

/*

  }
  pH->count = 0;
}

/*
** The hashing function.
*/
static unsigned int strHash(const char *z){
  unsigned int h = 0;
  unsigned char c;
  while( (c = (unsigned char)*z++)!=0 ){
    h = (h<<3) ^ h ^ sqlite3UpperToLower[c];

  }
  return h;
}


/* Link pNew element into the hash table pH.  If pEntry!=0 then also
** insert pNew into the pEntry hash bucket.

  if( new_ht==0 ) return 0;
  sqlite3_free(pH->ht);
  pH->ht = new_ht;
  pH->htsize = new_size = sqlite3MallocSize(new_ht)/sizeof(struct _ht);
  memset(new_ht, 0, new_size*sizeof(struct _ht));
  for(elem=pH->first, pH->first=0; elem; elem = next_elem){
    unsigned int h = strHash(elem->pKey) % new_size;
    next_elem = elem->next;
    insertElement(pH, &new_ht[h], elem);
  }
  return 1;
}

/* This function (for internal use only) locates an element in an
** hash table that matches the given key.  The hash for this key is
** also computed and returned in the *pH parameter.
*/
static HashElem *findElementWithHash(
  const Hash *pH,     /* The pH to be searched */
  const char *pKey,   /* The key we are searching for */

  unsigned int *pHash /* Write the hash value here */
){
  HashElem *elem;                /* Used to loop thru the element list */
  int count;                     /* Number of elements left to test */
  unsigned int h;                /* The computed hash */

  if( pH->ht ){
    struct _ht *pEntry;
    h = strHash(pKey) % pH->htsize;
    pEntry = &pH->ht[h];
    elem = pEntry->chain;
    count = pEntry->count;
  }else{
    h = 0;
    elem = pH->first;
    count = pH->count;
  }
  *pHash = h;
  while( count-- ){
    assert( elem!=0 );
    if( sqlite3StrICmp(elem->pKey,pKey)==0 ){ 
      return elem;
    }
    elem = elem->next;
  }
  return 0;
}

    assert( pH->first==0 );
    assert( pH->count==0 );
    sqlite3HashClear(pH);
  }
}

/* Attempt to locate an element of the hash table pH with a key
** that matches pKey.  Return the data for this element if it is
** found, or NULL if there is no match.
*/
void *sqlite3HashFind(const Hash *pH, const char *pKey){
  HashElem *elem;    /* The element that matches key */
  unsigned int h;    /* A hash on key */

  assert( pH!=0 );
  assert( pKey!=0 );






  elem = findElementWithHash(pH, pKey, &h);
  return elem ? elem->data : 0;
}

/* Insert an element into the hash table pH.  The key is pKey
** and the data is "data".
**
** If no element exists with a matching key, then a new
** element is created and NULL is returned.
**
** If another element already exists with the same key, then the
** new data replaces the old data and the old data is returned.
** The key is not copied in this instance.  If a malloc fails, then
** the new data is returned and the hash table is unchanged.
**
** If the "data" parameter to this function is NULL, then the
** element corresponding to "key" is removed from the hash table.
*/
void *sqlite3HashInsert(Hash *pH, const char *pKey, void *data){
  unsigned int h;       /* the hash of the key modulo hash table size */
  HashElem *elem;       /* Used to loop thru the element list */
  HashElem *new_elem;   /* New element added to the pH */

  assert( pH!=0 );
  assert( pKey!=0 );






  elem = findElementWithHash(pH,pKey,&h);
  if( elem ){
    void *old_data = elem->data;
    if( data==0 ){
      removeElementGivenHash(pH,elem,h);
    }else{
      elem->data = data;
      elem->pKey = pKey;

    }
    return old_data;
  }
  if( data==0 ) return 0;
  new_elem = (HashElem*)sqlite3Malloc( sizeof(HashElem) );
  if( new_elem==0 ) return data;
  new_elem->pKey = pKey;

  new_elem->data = data;
  pH->count++;
  if( pH->count>=10 && pH->count > 2*pH->htsize ){
    if( rehash(pH, pH->count*2) ){
      assert( pH->htsize>0 );
      h = strHash(pKey) % pH->htsize;
    }
  }



  insertElement(pH, pH->ht ? &pH->ht[h] : 0, new_elem);

  return 0;
}

**
** Again, this structure is intended to be opaque, but it can't really
** be opaque because it is used by macros.
*/
struct HashElem {
  HashElem *next, *prev;       /* Next and previous elements in the table */
  void *data;                  /* Data associated with this element */
  const char *pKey;            /* Key associated with this element */
};

/*
** Access routines.  To delete, insert a NULL pointer.
*/
void sqlite3HashInit(Hash*);
void *sqlite3HashInsert(Hash*, const char *pKey, void *pData);
void *sqlite3HashFind(const Hash*, const char *pKey);
void sqlite3HashClear(Hash*);

/*
** Macros for looping over all elements of a hash table.  The idiom is
** like this:
**
**   Hash h;

** or the first index for WITHOUT ROWID tables) if it is non-negative.
** If iBase is negative, then allocate the next available cursor.
**
** For a rowid table, *piDataCur will be exactly one less than *piIdxCur.
** For a WITHOUT ROWID table, *piDataCur will be somewhere in the range
** of *piIdxCurs, depending on where the PRIMARY KEY index appears on the
** pTab->pIndex list.
**
** If pTab is a virtual table, then this routine is a no-op and the
** *piDataCur and *piIdxCur values are left uninitialized.
*/
int sqlite3OpenTableAndIndices(
  Parse *pParse,   /* Parsing context */
  Table *pTab,     /* Table to be opened */
  int op,          /* OP_OpenRead or OP_OpenWrite */
  int iBase,       /* Use this for the table cursor, if there is one */
  u8 *aToOpen,     /* If not NULL: boolean for each table and index */
  int *piDataCur,  /* Write the database source cursor number here */
  int *piIdxCur    /* Write the first index cursor number here */
){
  int i;
  int iDb;
  int iDataCur;
  Index *pIdx;
  Vdbe *v;

  assert( op==OP_OpenRead || op==OP_OpenWrite );
  if( IsVirtual(pTab) ){
    /* This routine is a no-op for virtual tables. Leave the output
    ** variables *piDataCur and *piIdxCur uninitialized so that valgrind
    ** can detect if they are used by mistake in the caller. */
    return 0;
  }
  iDb = sqlite3SchemaToIndex(pParse->db, pTab->pSchema);
  v = sqlite3GetVdbe(pParse);
  assert( v!=0 );
  if( iBase<0 ) iBase = pParse->nTab;
  iDataCur = iBase++;

     && ((pDestCol->zDflt==0)!=(pSrcCol->zDflt==0) 
         || (pDestCol->zDflt && strcmp(pDestCol->zDflt, pSrcCol->zDflt)!=0))
    ){
      return 0;    /* Default values must be the same for all columns */
    }
  }
  for(pDestIdx=pDest->pIndex; pDestIdx; pDestIdx=pDestIdx->pNext){
    if( IsUniqueIndex(pDestIdx) ){
      destHasUniqueIdx = 1;
    }
    for(pSrcIdx=pSrc->pIndex; pSrcIdx; pSrcIdx=pSrcIdx->pNext){
      if( xferCompatibleIndex(pDestIdx, pSrcIdx) ) break;
    }
    if( pSrcIdx==0 ){
      return 0;    /* pDestIdx has no corresponding index in pSrc */

  char **azCols = 0;          /* Names of result columns */
  int callbackIsInit;         /* True if callback data is initialized */

  if( !sqlite3SafetyCheckOk(db) ) return SQLITE_MISUSE_BKPT;
  if( zSql==0 ) zSql = "";

  sqlite3_mutex_enter(db->mutex);
  sqlite3Error(db, SQLITE_OK);
  while( rc==SQLITE_OK && zSql[0] ){
    int nCol;
    char **azVals = 0;

    pStmt = 0;
    rc = sqlite3_prepare_v2(db, zSql, -1, &pStmt, &zLeftover);
    assert( rc==SQLITE_OK || pStmt==0 );

            if( !azVals[i] && sqlite3_column_type(pStmt, i)!=SQLITE_NULL ){
              db->mallocFailed = 1;
              goto exec_out;
            }
          }
        }
        if( xCallback(pArg, nCol, azVals, azCols) ){
          /* EVIDENCE-OF: R-38229-40159 If the callback function to
          ** sqlite3_exec() returns non-zero, then sqlite3_exec() will
          ** return SQLITE_ABORT. */
          rc = SQLITE_ABORT;
          sqlite3VdbeFinalize((Vdbe *)pStmt);
          pStmt = 0;
          sqlite3Error(db, SQLITE_ABORT);
          goto exec_out;
        }
      }

      if( rc!=SQLITE_ROW ){
        rc = sqlite3VdbeFinalize((Vdbe *)pStmt);
        pStmt = 0;

  if( rc!=SQLITE_OK && ALWAYS(rc==sqlite3_errcode(db)) && pzErrMsg ){
    int nErrMsg = 1 + sqlite3Strlen30(sqlite3_errmsg(db));
    *pzErrMsg = sqlite3Malloc(nErrMsg);
    if( *pzErrMsg ){
      memcpy(*pzErrMsg, sqlite3_errmsg(db), nErrMsg);
    }else{
      rc = SQLITE_NOMEM;
      sqlite3Error(db, SQLITE_NOMEM);
    }
  }else if( pzErrMsg ){
    *pzErrMsg = 0;
  }

  assert( (rc&db->errMask)==rc );
  sqlite3_mutex_leave(db->mutex);
  return rc;
}

    }else{
      xInit = (int(*)(sqlite3*,char**,const sqlite3_api_routines*))
              wsdAutoext.aExt[i];
    }
    sqlite3_mutex_leave(mutex);
    zErrmsg = 0;
    if( xInit && (rc = xInit(db, &zErrmsg, &sqlite3Apis))!=0 ){
      sqlite3ErrorWithMsg(db, rc,
            "automatic extension loading failed: %s", zErrmsg);
      go = 0;
    }
    sqlite3_free(zErrmsg);
  }
}

}

/*
** Close an existing SQLite database
*/
static int sqlite3Close(sqlite3 *db, int forceZombie){
  if( !db ){
    /* EVIDENCE-OF: R-63257-11740 Calling sqlite3_close() or
    ** sqlite3_close_v2() with a NULL pointer argument is a harmless no-op. */
    return SQLITE_OK;
  }
  if( !sqlite3SafetyCheckSickOrOk(db) ){
    return SQLITE_MISUSE_BKPT;
  }
  sqlite3_mutex_enter(db->mutex);

  */
  sqlite3VtabRollback(db);

  /* Legacy behavior (sqlite3_close() behavior) is to return
  ** SQLITE_BUSY if the connection can not be closed immediately.
  */
  if( !forceZombie && connectionIsBusy(db) ){
    sqlite3ErrorWithMsg(db, SQLITE_BUSY, "unable to close due to unfinalized "
       "statements or unfinished backups");
    sqlite3_mutex_leave(db->mutex);
    return SQLITE_BUSY;
  }

#ifdef SQLITE_ENABLE_SQLLOG
  if( sqlite3GlobalConfig.xSqllog ){

      pMod->xDestroy(pMod->pAux);
    }
    sqlite3DbFree(db, pMod);
  }
  sqlite3HashClear(&db->aModule);
#endif

  sqlite3Error(db, SQLITE_OK); /* Deallocates any cached error strings. */
  sqlite3ValueFree(db->pErr);
  sqlite3CloseExtensions(db);

  db->magic = SQLITE_MAGIC_ERROR;

  /* The temp-database schema is allocated differently from the other schema
  ** objects (using sqliteMalloc() directly, instead of sqlite3BtreeSchema()).

  }
}

/*
** Return a static string containing the name corresponding to the error code
** specified in the argument.
*/
#if (defined(SQLITE_DEBUG) && SQLITE_OS_WIN) || defined(SQLITE_TEST)
const char *sqlite3ErrName(int rc){
  const char *zName = 0;
  int i, origRc = rc;
  for(i=0; i<2 && zName==0; i++, rc &= 0xff){
    switch( rc ){
      case SQLITE_OK:                 zName = "SQLITE_OK";                break;
      case SQLITE_ERROR:              zName = "SQLITE_ERROR";             break;

      case SQLITE_IOERR_FSYNC:        zName = "SQLITE_IOERR_FSYNC";       break;
      case SQLITE_IOERR_DIR_FSYNC:    zName = "SQLITE_IOERR_DIR_FSYNC";   break;
      case SQLITE_IOERR_TRUNCATE:     zName = "SQLITE_IOERR_TRUNCATE";    break;
      case SQLITE_IOERR_FSTAT:        zName = "SQLITE_IOERR_FSTAT";       break;
      case SQLITE_IOERR_UNLOCK:       zName = "SQLITE_IOERR_UNLOCK";      break;
      case SQLITE_IOERR_RDLOCK:       zName = "SQLITE_IOERR_RDLOCK";      break;
      case SQLITE_IOERR_DELETE:       zName = "SQLITE_IOERR_DELETE";      break;

      case SQLITE_IOERR_NOMEM:        zName = "SQLITE_IOERR_NOMEM";       break;
      case SQLITE_IOERR_ACCESS:       zName = "SQLITE_IOERR_ACCESS";      break;
      case SQLITE_IOERR_CHECKRESERVEDLOCK:
                                zName = "SQLITE_IOERR_CHECKRESERVEDLOCK"; break;
      case SQLITE_IOERR_LOCK:         zName = "SQLITE_IOERR_LOCK";        break;
      case SQLITE_IOERR_CLOSE:        zName = "SQLITE_IOERR_CLOSE";       break;
      case SQLITE_IOERR_DIR_CLOSE:    zName = "SQLITE_IOERR_DIR_CLOSE";   break;

  ** and there are active VMs, then return SQLITE_BUSY. If a function
  ** is being overridden/deleted but there are no active VMs, allow the
  ** operation to continue but invalidate all precompiled statements.
  */
  p = sqlite3FindFunction(db, zFunctionName, nName, nArg, (u8)enc, 0);
  if( p && (p->funcFlags & SQLITE_FUNC_ENCMASK)==enc && p->nArg==nArg ){
    if( db->nVdbeActive ){
      sqlite3ErrorWithMsg(db, SQLITE_BUSY, 
        "unable to delete/modify user-function due to active statements");
      assert( !db->mallocFailed );
      return SQLITE_BUSY;
    }else{
      sqlite3ExpirePreparedStatements(db);
    }
  }

  sqlite3_mutex_enter(db->mutex);
  if( zDb && zDb[0] ){
    iDb = sqlite3FindDbName(db, zDb);
  }
  if( iDb<0 ){
    rc = SQLITE_ERROR;
    sqlite3ErrorWithMsg(db, SQLITE_ERROR, "unknown database: %s", zDb);
  }else{
    rc = sqlite3Checkpoint(db, iDb, eMode, pnLog, pnCkpt);
    sqlite3Error(db, rc);
  }
  rc = sqlite3ApiExit(db, rc);
  sqlite3_mutex_leave(db->mutex);
  return rc;
#endif
}

  }
  sqlite3_mutex_enter(db->mutex);
  if( db->mallocFailed ){
    z = (void *)outOfMem;
  }else{
    z = sqlite3_value_text16(db->pErr);
    if( z==0 ){
      sqlite3ErrorWithMsg(db, db->errCode, sqlite3ErrStr(db->errCode));
      z = sqlite3_value_text16(db->pErr);
    }
    /* A malloc() may have failed within the call to sqlite3_value_text16()
    ** above. If this is the case, then the db->mallocFailed flag needs to
    ** be cleared before returning. Do this directly, instead of via
    ** sqlite3ApiExit(), to avoid setting the database handle error message.
    */

  u8 enc,
  void* pCtx,
  int(*xCompare)(void*,int,const void*,int,const void*),
  void(*xDel)(void*)
){
  CollSeq *pColl;
  int enc2;

  
  assert( sqlite3_mutex_held(db->mutex) );

  /* If SQLITE_UTF16 is specified as the encoding type, transform this
  ** to one of SQLITE_UTF16LE or SQLITE_UTF16BE using the
  ** SQLITE_UTF16NATIVE macro. SQLITE_UTF16 is not used internally.
  */

  /* Check if this call is removing or replacing an existing collation 
  ** sequence. If so, and there are active VMs, return busy. If there
  ** are no active VMs, invalidate any pre-compiled statements.
  */
  pColl = sqlite3FindCollSeq(db, (u8)enc2, zName, 0);
  if( pColl && pColl->xCmp ){
    if( db->nVdbeActive ){
      sqlite3ErrorWithMsg(db, SQLITE_BUSY, 
        "unable to delete/modify collation sequence due to active statements");
      return SQLITE_BUSY;
    }
    sqlite3ExpirePreparedStatements(db);
    invalidateCachedKeyInfo(db);

    /* If collation sequence pColl was created directly by a call to
    ** sqlite3_create_collation, and not generated by synthCollSeq(),
    ** then any copies made by synthCollSeq() need to be invalidated.
    ** Also, collation destructor - CollSeq.xDel() - function may need
    ** to be called.
    */ 
    if( (pColl->enc & ~SQLITE_UTF16_ALIGNED)==enc2 ){
      CollSeq *aColl = sqlite3HashFind(&db->aCollSeq, zName);
      int j;
      for(j=0; j<3; j++){
        CollSeq *p = &aColl[j];
        if( p->enc==pColl->enc ){
          if( p->xDel ){
            p->xDel(p->pUser);
          }
          p->xCmp = 0;
        }
      }
    }
  }

  pColl = sqlite3FindCollSeq(db, (u8)enc2, zName, 1);
  if( pColl==0 ) return SQLITE_NOMEM;
  pColl->xCmp = xCompare;
  pColl->pUser = pCtx;
  pColl->xDel = xDel;
  pColl->enc = (u8)(enc2 | (enc & SQLITE_UTF16_ALIGNED));
  sqlite3Error(db, SQLITE_OK);
  return SQLITE_OK;
}


/*
** This array defines hard upper bounds on limit values.  The
** initializer must be kept in sync with the SQLITE_LIMIT_*
** #defines in sqlite3.h.
*/
static const int aHardLimit[] = {
  SQLITE_MAX_LENGTH,
  SQLITE_MAX_SQL_LENGTH,
  SQLITE_MAX_COLUMN,
  SQLITE_MAX_EXPR_DEPTH,
  SQLITE_MAX_COMPOUND_SELECT,
  SQLITE_MAX_VDBE_OP,
  SQLITE_MAX_FUNCTION_ARG,
  SQLITE_MAX_ATTACHED,
  SQLITE_MAX_LIKE_PATTERN_LENGTH,
  SQLITE_MAX_VARIABLE_NUMBER,      /* IMP: R-38091-32352 */
  SQLITE_MAX_TRIGGER_DEPTH,
};

/*
** Make sure the hard limits are set to reasonable values
*/
#if SQLITE_MAX_LENGTH<100

  createCollation(db, "NOCASE", SQLITE_UTF8, 0, nocaseCollatingFunc, 0);

  /* Parse the filename/URI argument. */
  db->openFlags = flags;
  rc = sqlite3ParseUri(zVfs, zFilename, &flags, &db->pVfs, &zOpen, &zErrMsg);
  if( rc!=SQLITE_OK ){
    if( rc==SQLITE_NOMEM ) db->mallocFailed = 1;
    sqlite3ErrorWithMsg(db, rc, zErrMsg ? "%s" : 0, zErrMsg);
    sqlite3_free(zErrMsg);
    goto opendb_out;
  }

  /* Open the backend database driver */
  rc = sqlite3BtreeOpen(db->pVfs, zOpen, db, &db->aDb[0].pBt, 0,
                        flags | SQLITE_OPEN_MAIN_DB);
  if( rc!=SQLITE_OK ){
    if( rc==SQLITE_IOERR_NOMEM ){
      rc = SQLITE_NOMEM;
    }
    sqlite3Error(db, rc);
    goto opendb_out;
  }
  db->aDb[0].pSchema = sqlite3SchemaGet(db, db->aDb[0].pBt);
  db->aDb[1].pSchema = sqlite3SchemaGet(db, 0);


  /* The default safety_level for the main database is 'full'; for the temp

    goto opendb_out;
  }

  /* Register all built-in functions, but do not attempt to read the
  ** database schema yet. This is delayed until the first time the database
  ** is accessed.
  */
  sqlite3Error(db, SQLITE_OK);
  sqlite3RegisterBuiltinFunctions(db);

  /* Load automatic extensions - extensions that have been registered
  ** using the sqlite3_automatic_extension() API.
  */
  rc = sqlite3_errcode(db);
  if( rc==SQLITE_OK ){

  */
#ifdef SQLITE_DEFAULT_LOCKING_MODE
  db->dfltLockMode = SQLITE_DEFAULT_LOCKING_MODE;
  sqlite3PagerLockingMode(sqlite3BtreePager(db->aDb[0].pBt),
                          SQLITE_DEFAULT_LOCKING_MODE);
#endif

  if( rc ) sqlite3Error(db, rc);

  /* Enable the lookaside-malloc subsystem */
  setupLookaside(db, 0, sqlite3GlobalConfig.szLookaside,
                        sqlite3GlobalConfig.nLookaside);

  sqlite3_wal_autocheckpoint(db, SQLITE_DEFAULT_WAL_AUTOCHECKPOINT);

  if( SQLITE_OK==rc && !pTab ){
    sqlite3DbFree(db, zErrMsg);
    zErrMsg = sqlite3MPrintf(db, "no such table column: %s.%s", zTableName,
        zColumnName);
    rc = SQLITE_ERROR;
  }
  sqlite3ErrorWithMsg(db, rc, (zErrMsg?"%s":0), zErrMsg);
  sqlite3DbFree(db, zErrMsg);
  rc = sqlite3ApiExit(db, rc);
  sqlite3_mutex_leave(db->mutex);
  return rc;
}
#endif

#ifdef SQLITE_VDBE_COVERAGE
      typedef void (*branch_callback)(void*,int,u8,u8);
      sqlite3GlobalConfig.xVdbeBranch = va_arg(ap,branch_callback);
      sqlite3GlobalConfig.pVdbeBranchArg = va_arg(ap,void*);
#endif
      break;
    }

    /*   sqlite3_test_control(SQLITE_TESTCTRL_ISINIT);
    **
    ** Return SQLITE_OK if SQLite has been initialized and SQLITE_ERROR if
    ** not.
    */
    case SQLITE_TESTCTRL_ISINIT: {
      if( sqlite3GlobalConfig.isInit==0 ) rc = SQLITE_ERROR;
      break;
    }

  }
  va_end(ap);
#endif /* SQLITE_OMIT_BUILTIN_TEST */
  return rc;
}

** embedded processor.
*/
void *sqlite3ScratchMalloc(int n){
  void *p;
  assert( n>0 );

  sqlite3_mutex_enter(mem0.mutex);
  sqlite3StatusSet(SQLITE_STATUS_SCRATCH_SIZE, n);
  if( mem0.nScratchFree && sqlite3GlobalConfig.szScratch>=n ){
    p = mem0.pScratchFree;
    mem0.pScratchFree = mem0.pScratchFree->pNext;
    mem0.nScratchFree--;
    sqlite3StatusAdd(SQLITE_STATUS_SCRATCH_USED, 1);

    sqlite3_mutex_leave(mem0.mutex);
  }else{
    sqlite3_mutex_leave(mem0.mutex);
    p = sqlite3Malloc(n);
    if( sqlite3GlobalConfig.bMemstat && p ){
      sqlite3_mutex_enter(mem0.mutex);

      sqlite3StatusAdd(SQLITE_STATUS_SCRATCH_OVERFLOW, sqlite3MallocSize(p));
      sqlite3_mutex_leave(mem0.mutex);



    }
    sqlite3MemdebugSetType(p, MEMTYPE_SCRATCH);
  }
  assert( sqlite3_mutex_notheld(mem0.mutex) );


#if SQLITE_THREADSAFE==0 && !defined(NDEBUG)

    sqlite3StatusAdd(SQLITE_STATUS_MALLOC_COUNT, -1);
    sqlite3GlobalConfig.m.xFree(p);
    sqlite3_mutex_leave(mem0.mutex);
  }else{
    sqlite3GlobalConfig.m.xFree(p);
  }
}

/*
** Add the size of memory allocation "p" to the count in
** *db->pnBytesFreed.
*/
static SQLITE_NOINLINE void measureAllocationSize(sqlite3 *db, void *p){
  *db->pnBytesFreed += sqlite3DbMallocSize(db,p);
}

/*
** Free memory that might be associated with a particular database
** connection.
*/
void sqlite3DbFree(sqlite3 *db, void *p){
  assert( db==0 || sqlite3_mutex_held(db->mutex) );
  if( p==0 ) return;
  if( db ){
    if( db->pnBytesFreed ){
      measureAllocationSize(db, p);
      return;
    }
    if( isLookaside(db, p) ){
      LookasideSlot *pBuf = (LookasideSlot*)p;
#if SQLITE_DEBUG
      /* Trash all content in the buffer being freed */
      memset(p, 0xaa, db->lookaside.sz);

  va_start(ap, zFormat);
  z = sqlite3VMPrintf(db, zFormat, ap);
  va_end(ap);
  sqlite3DbFree(db, *pz);
  *pz = z;
}

/*
** Take actions at the end of an API call to indicate an OOM error
*/
static SQLITE_NOINLINE int apiOomError(sqlite3 *db){
  db->mallocFailed = 0;
  sqlite3Error(db, SQLITE_NOMEM);
  return SQLITE_NOMEM;
}

/*
** This function must be called before exiting any API function (i.e. 
** returning control to the user) that has called sqlite3_malloc or
** sqlite3_realloc.
**
** The returned value is normally a copy of the second argument to this
** function. However, if a malloc() failure has occurred since the previous
** invocation SQLITE_NOMEM is returned instead. 
**
** If the first argument, db, is not NULL and a malloc() error has occurred,
** then the connection error-code (the value returned by sqlite3_errcode())
** is set to SQLITE_NOMEM.
*/
int sqlite3ApiExit(sqlite3* db, int rc){
  /* If the db handle is not NULL, then we must hold the connection handle
  ** mutex here. Otherwise the read (and possible write) of db->mallocFailed 
  ** is unsafe, as is the call to sqlite3Error().
  */
  assert( !db || sqlite3_mutex_held(db->mutex) );
  if( db==0 ) return rc & 0xff;
  if( db->mallocFailed || rc==SQLITE_IOERR_NOMEM ){
    return apiOomError(db);


  }
  return rc & db->errMask;
}

}

/*
** Retrieve a pointer to a static mutex or allocate a new dynamic one.
*/
sqlite3_mutex *sqlite3_mutex_alloc(int id){
#ifndef SQLITE_OMIT_AUTOINIT
  if( id<=SQLITE_MUTEX_RECURSIVE && sqlite3_initialize() ) return 0;
#endif
  return sqlite3GlobalConfig.mutex.xMutexAlloc(id);
}

sqlite3_mutex *sqlite3MutexAlloc(int id){
  if( !sqlite3GlobalConfig.bCoreMutex ){
    return 0;

/*
** The sqlite3_mutex_alloc() routine allocates a new
** mutex and returns a pointer to it.  If it returns NULL
** that means that a mutex could not be allocated. 
*/
static sqlite3_mutex *debugMutexAlloc(int id){
  static sqlite3_debug_mutex aStatic[SQLITE_MUTEX_STATIC_APP3 - 1];
  sqlite3_debug_mutex *pNew = 0;
  switch( id ){
    case SQLITE_MUTEX_FAST:
    case SQLITE_MUTEX_RECURSIVE: {
      pNew = sqlite3Malloc(sizeof(*pNew));
      if( pNew ){
        pNew->id = id;

** to sqlite3_mutex_alloc() is one of these integer constants:
**
** <ul>
** <li>  SQLITE_MUTEX_FAST
** <li>  SQLITE_MUTEX_RECURSIVE
** <li>  SQLITE_MUTEX_STATIC_MASTER
** <li>  SQLITE_MUTEX_STATIC_MEM
** <li>  SQLITE_MUTEX_STATIC_OPEN
** <li>  SQLITE_MUTEX_STATIC_PRNG
** <li>  SQLITE_MUTEX_STATIC_LRU
** <li>  SQLITE_MUTEX_STATIC_PMEM
** <li>  SQLITE_MUTEX_STATIC_APP1
** <li>  SQLITE_MUTEX_STATIC_APP2
** <li>  SQLITE_MUTEX_STATIC_APP3
** </ul>
**
** The first two constants cause sqlite3_mutex_alloc() to create
** a new mutex.  The new mutex is recursive when SQLITE_MUTEX_RECURSIVE
** is used but not necessarily so when SQLITE_MUTEX_FAST is used.
** The mutex implementation does not need to make a distinction
** between SQLITE_MUTEX_RECURSIVE and SQLITE_MUTEX_FAST if it does

** or SQLITE_MUTEX_RECURSIVE) is used then sqlite3_mutex_alloc()
** returns a different mutex on every call.  But for the static 
** mutex types, the same mutex is returned on every call that has
** the same type number.
*/
static sqlite3_mutex *pthreadMutexAlloc(int iType){
  static sqlite3_mutex staticMutexes[] = {
    SQLITE3_MUTEX_INITIALIZER,
    SQLITE3_MUTEX_INITIALIZER,
    SQLITE3_MUTEX_INITIALIZER,
    SQLITE3_MUTEX_INITIALIZER,
    SQLITE3_MUTEX_INITIALIZER,
    SQLITE3_MUTEX_INITIALIZER,
    SQLITE3_MUTEX_INITIALIZER,
    SQLITE3_MUTEX_INITIALIZER,
    SQLITE3_MUTEX_INITIALIZER
  };

/*
** 2007 August 14
**
** 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 contains the C functions that implement mutexes for Win32.
*/
#include "sqliteInt.h"

#if SQLITE_OS_WIN
/*
** Include code that is common to all os_*.c files
*/
#include "os_common.h"

/*
** Include the header file for the Windows VFS.
*/
#include "os_win.h"
#endif

/*
** The code in this file is only used if we are compiling multithreaded
** on a Win32 system.
*/
#ifdef SQLITE_MUTEX_W32

/*
** Each recursive mutex is an instance of the following structure.
*/
struct sqlite3_mutex {
  CRITICAL_SECTION mutex;    /* Mutex controlling the lock */
  int id;                    /* Mutex type */
#ifdef SQLITE_DEBUG
  volatile int nRef;         /* Number of enterances */
  volatile DWORD owner;      /* Thread holding this mutex */
  volatile int trace;        /* True to trace changes */
#endif
};







/*








** These are the initializer values used when declaring a "static" mutex
** on Win32.  It should be noted that all mutexes require initialization
** on the Win32 platform.






*/
#define SQLITE_W32_MUTEX_INITIALIZER { 0 }

#ifdef SQLITE_DEBUG
#define SQLITE3_MUTEX_INITIALIZER { SQLITE_W32_MUTEX_INITIALIZER, 0, \
                                    0L, (DWORD)0, 0 }
#else










#define SQLITE3_MUTEX_INITIALIZER { SQLITE_W32_MUTEX_INITIALIZER, 0 }
#endif

#ifdef SQLITE_DEBUG
/*
** The sqlite3_mutex_held() and sqlite3_mutex_notheld() routine are
** intended for use only inside assert() statements.
*/
static int winMutexHeld(sqlite3_mutex *p){
  return p->nRef!=0 && p->owner==GetCurrentThreadId();
}

static int winMutexNotheld2(sqlite3_mutex *p, DWORD tid){
  return p->nRef==0 || p->owner!=tid;
}

static int winMutexNotheld(sqlite3_mutex *p){
  DWORD tid = GetCurrentThreadId();
  return winMutexNotheld2(p, tid);
}
#endif


/*
** Initialize and deinitialize the mutex subsystem.
*/
static sqlite3_mutex winMutex_staticMutexes[] = {
  SQLITE3_MUTEX_INITIALIZER,
  SQLITE3_MUTEX_INITIALIZER,
  SQLITE3_MUTEX_INITIALIZER,
  SQLITE3_MUTEX_INITIALIZER,
  SQLITE3_MUTEX_INITIALIZER,
  SQLITE3_MUTEX_INITIALIZER,
  SQLITE3_MUTEX_INITIALIZER,
  SQLITE3_MUTEX_INITIALIZER,
  SQLITE3_MUTEX_INITIALIZER
};

static int winMutex_isInit = 0;
static int winMutex_isNt = -1; /* <0 means "need to query" */

/* As the winMutexInit() and winMutexEnd() functions are called as part
** of the sqlite3_initialize() and sqlite3_shutdown() processing, the
** "interlocked" magic used here is probably not strictly necessary.

*/
static LONG SQLITE_WIN32_VOLATILE winMutex_lock = 0;

int sqlite3_win32_is_nt(void); /* os_win.c */
void sqlite3_win32_sleep(DWORD milliseconds); /* os_win.c */

static int winMutexInit(void){
  /* The first to increment to 1 does actual initialization */
  if( InterlockedCompareExchange(&winMutex_lock, 1, 0)==0 ){
    int i;
    for(i=0; i<ArraySize(winMutex_staticMutexes); i++){
#if SQLITE_OS_WINRT
      InitializeCriticalSectionEx(&winMutex_staticMutexes[i].mutex, 0, 0);
#else
      InitializeCriticalSection(&winMutex_staticMutexes[i].mutex);
#endif
    }
    winMutex_isInit = 1;
  }else{
    /* Another thread is (in the process of) initializing the static
    ** mutexes */
    while( !winMutex_isInit ){
      sqlite3_win32_sleep(1);
    }
  }
  return SQLITE_OK;
}

static int winMutexEnd(void){
  /* The first to decrement to 0 does actual shutdown
  ** (which should be the last to shutdown.) */
  if( InterlockedCompareExchange(&winMutex_lock, 0, 1)==1 ){
    if( winMutex_isInit==1 ){
      int i;
      for(i=0; i<ArraySize(winMutex_staticMutexes); i++){
        DeleteCriticalSection(&winMutex_staticMutexes[i].mutex);
      }
      winMutex_isInit = 0;
    }
  }
  return SQLITE_OK;
}

/*
** The sqlite3_mutex_alloc() routine allocates a new
** mutex and returns a pointer to it.  If it returns NULL
** that means that a mutex could not be allocated.  SQLite
** will unwind its stack and return an error.  The argument
** to sqlite3_mutex_alloc() is one of these integer constants:
**
** <ul>
** <li>  SQLITE_MUTEX_FAST
** <li>  SQLITE_MUTEX_RECURSIVE
** <li>  SQLITE_MUTEX_STATIC_MASTER
** <li>  SQLITE_MUTEX_STATIC_MEM
** <li>  SQLITE_MUTEX_STATIC_OPEN
** <li>  SQLITE_MUTEX_STATIC_PRNG
** <li>  SQLITE_MUTEX_STATIC_LRU
** <li>  SQLITE_MUTEX_STATIC_PMEM
** <li>  SQLITE_MUTEX_STATIC_APP1
** <li>  SQLITE_MUTEX_STATIC_APP2
** <li>  SQLITE_MUTEX_STATIC_APP3
** </ul>
**
** The first two constants cause sqlite3_mutex_alloc() to create
** a new mutex.  The new mutex is recursive when SQLITE_MUTEX_RECURSIVE
** is used but not necessarily so when SQLITE_MUTEX_FAST is used.
** The mutex implementation does not need to make a distinction
** between SQLITE_MUTEX_RECURSIVE and SQLITE_MUTEX_FAST if it does

** may add additional static mutexes.  Static mutexes are for internal
** use by SQLite only.  Applications that use SQLite mutexes should
** use only the dynamic mutexes returned by SQLITE_MUTEX_FAST or
** SQLITE_MUTEX_RECURSIVE.
**
** Note that if one of the dynamic mutex parameters (SQLITE_MUTEX_FAST
** or SQLITE_MUTEX_RECURSIVE) is used then sqlite3_mutex_alloc()
** returns a different mutex on every call.  But for the static
** mutex types, the same mutex is returned on every call that has
** the same type number.
*/
static sqlite3_mutex *winMutexAlloc(int iType){
  sqlite3_mutex *p;

  switch( iType ){
    case SQLITE_MUTEX_FAST:
    case SQLITE_MUTEX_RECURSIVE: {
      p = sqlite3MallocZero( sizeof(*p) );
      if( p ){
#ifdef SQLITE_DEBUG
        p->id = iType;
#ifdef SQLITE_WIN32_MUTEX_TRACE_DYNAMIC
        p->trace = 1;
#endif
#endif
#if SQLITE_OS_WINRT
        InitializeCriticalSectionEx(&p->mutex, 0, 0);
#else
        InitializeCriticalSection(&p->mutex);
#endif
      }
      break;
    }
    default: {

      assert( iType-2 >= 0 );
      assert( iType-2 < ArraySize(winMutex_staticMutexes) );
      assert( winMutex_isInit==1 );
      p = &winMutex_staticMutexes[iType-2];
#ifdef SQLITE_DEBUG
      p->id = iType;
#ifdef SQLITE_WIN32_MUTEX_TRACE_STATIC
      p->trace = 1;
#endif
#endif
      break;
    }
  }
  return p;
}


/*
** This routine deallocates a previously
** allocated mutex.  SQLite is careful to deallocate every
** mutex that it allocates.
*/
static void winMutexFree(sqlite3_mutex *p){
  assert( p );
#ifdef SQLITE_DEBUG
  assert( p->nRef==0 && p->owner==0 );
  assert( p->id==SQLITE_MUTEX_FAST || p->id==SQLITE_MUTEX_RECURSIVE );
#endif
  assert( winMutex_isInit==1 );
  DeleteCriticalSection(&p->mutex);
  sqlite3_free(p);
}

/*
** The sqlite3_mutex_enter() and sqlite3_mutex_try() routines attempt
** to enter a mutex.  If another thread is already within the mutex,
** sqlite3_mutex_enter() will block and sqlite3_mutex_try() will return
** SQLITE_BUSY.  The sqlite3_mutex_try() interface returns SQLITE_OK
** upon successful entry.  Mutexes created using SQLITE_MUTEX_RECURSIVE can
** be entered multiple times by the same thread.  In such cases the,
** mutex must be exited an equal number of times before another thread
** can enter.  If the same thread tries to enter any other kind of mutex
** more than once, the behavior is undefined.
*/
static void winMutexEnter(sqlite3_mutex *p){
#if defined(SQLITE_DEBUG) || defined(SQLITE_TEST)
  DWORD tid = GetCurrentThreadId();
#endif
#ifdef SQLITE_DEBUG
  assert( p );
  assert( p->id==SQLITE_MUTEX_RECURSIVE || winMutexNotheld2(p, tid) );
#else
  assert( p );
#endif
  assert( winMutex_isInit==1 );
  EnterCriticalSection(&p->mutex);
#ifdef SQLITE_DEBUG
  assert( p->nRef>0 || p->owner==0 );
  p->owner = tid;
  p->nRef++;
  if( p->trace ){
    OSTRACE(("ENTER-MUTEX tid=%lu, mutex=%p (%d), nRef=%d\n",
             tid, p, p->trace, p->nRef));
  }
#endif
}

static int winMutexTry(sqlite3_mutex *p){
#if defined(SQLITE_DEBUG) || defined(SQLITE_TEST)
  DWORD tid = GetCurrentThreadId();
#endif
  int rc = SQLITE_BUSY;
  assert( p );
  assert( p->id==SQLITE_MUTEX_RECURSIVE || winMutexNotheld2(p, tid) );
  /*
  ** The sqlite3_mutex_try() routine is very rarely used, and when it
  ** is used it is merely an optimization.  So it is OK for it to always
  ** fail.
  **
  ** The TryEnterCriticalSection() interface is only available on WinNT.
  ** And some windows compilers complain if you try to use it without
  ** first doing some #defines that prevent SQLite from building on Win98.
  ** For that reason, we will omit this optimization for now.  See
  ** ticket #2685.
  */
#if defined(_WIN32_WINNT) && _WIN32_WINNT >= 0x0400
  assert( winMutex_isInit==1 );
  assert( winMutex_isNt>=-1 && winMutex_isNt<=1 );
  if( winMutex_isNt<0 ){
    winMutex_isNt = sqlite3_win32_is_nt();
  }
  assert( winMutex_isNt==0 || winMutex_isNt==1 );
  if( winMutex_isNt && TryEnterCriticalSection(&p->mutex) ){
#ifdef SQLITE_DEBUG
    p->owner = tid;
    p->nRef++;
#endif
    rc = SQLITE_OK;
  }
#else
  UNUSED_PARAMETER(p);
#endif
#ifdef SQLITE_DEBUG
  if( p->trace ){
    OSTRACE(("TRY-MUTEX tid=%lu, mutex=%p (%d), owner=%lu, nRef=%d, rc=%s\n",
             tid, p, p->trace, p->owner, p->nRef, sqlite3ErrName(rc)));
  }
#endif
  return rc;
}

/*
** The sqlite3_mutex_leave() routine exits a mutex that was
** previously entered by the same thread.  The behavior
** is undefined if the mutex is not currently entered or
** is not currently allocated.  SQLite will never do either.
*/
static void winMutexLeave(sqlite3_mutex *p){
#if defined(SQLITE_DEBUG) || defined(SQLITE_TEST)
  DWORD tid = GetCurrentThreadId();
#endif
  assert( p );
#ifdef SQLITE_DEBUG
  assert( p->nRef>0 );
  assert( p->owner==tid );
  p->nRef--;
  if( p->nRef==0 ) p->owner = 0;
  assert( p->nRef==0 || p->id==SQLITE_MUTEX_RECURSIVE );
#endif
  assert( winMutex_isInit==1 );
  LeaveCriticalSection(&p->mutex);
#ifdef SQLITE_DEBUG
  if( p->trace ){
    OSTRACE(("LEAVE-MUTEX tid=%lu, mutex=%p (%d), nRef=%d\n",
             tid, p, p->trace, p->nRef));
  }
#endif
}

sqlite3_mutex_methods const *sqlite3DefaultMutex(void){
  static const sqlite3_mutex_methods sMutex = {
    winMutexInit,

    winMutexHeld,
    winMutexNotheld
#else
    0,
    0
#endif
  };

  return &sMutex;
}

#endif /* SQLITE_MUTEX_W32 */

      removeFromBlockedList(db);
      addToBlockedList(db);
    }
  }

  leaveMutex();
  assert( !db->mallocFailed );
  sqlite3ErrorWithMsg(db, rc, (rc?"database is deadlocked":0));
  sqlite3_mutex_leave(db->mutex);
  return rc;
}

/*
** This function is called while stepping or preparing a statement 
** associated with connection db. The operation will return SQLITE_LOCKED

#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <time.h>
#include <sys/time.h>
#include <errno.h>
#if !defined(SQLITE_OMIT_WAL) || SQLITE_MAX_MMAP_SIZE>0
# include <sys/mman.h>
#endif


#if SQLITE_ENABLE_LOCKING_STYLE || OS_VXWORKS
# include <sys/ioctl.h>
# if OS_VXWORKS
#  include <semaphore.h>
#  include <limits.h>
# else
#  include <sys/file.h>
#  include <sys/param.h>

/*
** On some systems, calls to fchown() will trigger a message in a security
** log if they come from non-root processes.  So avoid calling fchown() if
** we are not running as root.
*/
static int posixFchown(int fd, uid_t uid, gid_t gid){
#if OS_VXWORKS
  return 0;
#else
  return geteuid() ? 0 : fchown(fd,uid,gid);
#endif
}

/* Forward reference */
static int openDirectory(const char*, int*);
static int unixGetpagesize(void);

/*

  { "fcntl",        (sqlite3_syscall_ptr)fcntl,      0  },
#define osFcntl     ((int(*)(int,int,...))aSyscall[7].pCurrent)

  { "read",         (sqlite3_syscall_ptr)read,       0  },
#define osRead      ((ssize_t(*)(int,void*,size_t))aSyscall[8].pCurrent)

#if defined(USE_PREAD) || (SQLITE_ENABLE_LOCKING_STYLE && !OS_VXWORKS)
  { "pread",        (sqlite3_syscall_ptr)pread,      0  },
#else
  { "pread",        (sqlite3_syscall_ptr)0,          0  },
#endif
#define osPread     ((ssize_t(*)(int,void*,size_t,off_t))aSyscall[9].pCurrent)

#if defined(USE_PREAD64)
  { "pread64",      (sqlite3_syscall_ptr)pread64,    0  },
#else
  { "pread64",      (sqlite3_syscall_ptr)0,          0  },
#endif
#define osPread64   ((ssize_t(*)(int,void*,size_t,off_t))aSyscall[10].pCurrent)

  { "write",        (sqlite3_syscall_ptr)write,      0  },
#define osWrite     ((ssize_t(*)(int,const void*,size_t))aSyscall[11].pCurrent)

#if defined(USE_PREAD) || (SQLITE_ENABLE_LOCKING_STYLE && !OS_VXWORKS)
  { "pwrite",       (sqlite3_syscall_ptr)pwrite,     0  },
#else
  { "pwrite",       (sqlite3_syscall_ptr)0,          0  },
#endif
#define osPwrite    ((ssize_t(*)(int,const void*,size_t,off_t))\
                    aSyscall[12].pCurrent)

        (sqliteIOErr == SQLITE_IOERR_CHECKRESERVEDLOCK) ){
      return SQLITE_BUSY;
    }
    /* else fall through */
  case EPERM: 
    return SQLITE_PERM;
    










#if EOPNOTSUPP!=ENOTSUP
  case EOPNOTSUPP: 
    /* something went terribly awry, unless during file system support 
     * introspection, in which it actually means what it says */
#endif
#ifdef ENOTSUP
  case ENOTSUP: 

  return SQLITE_OK;
}

/*
** Return TRUE if pFile has been renamed or unlinked since it was first opened.
*/
static int fileHasMoved(unixFile *pFile){
#if OS_VXWORKS
  return pFile->pInode!=0 && pFile->pId!=pFile->pInode->fileId.pId;
#else
  struct stat buf;
  return pFile->pInode!=0 &&
      (osStat(pFile->zPath, &buf)!=0 || buf.st_ino!=pFile->pInode->fileId.ino);
#endif
}


/*
** Check a unixFile that is a database.  Verify the following:
**
** (1) There is exactly one hard link on the file

  if( pFile->eFileLock>SHARED_LOCK ){
    reserved = 1;
  }
  
  /* Otherwise see if some other process holds it. */
  if( !reserved ){
    sem_t *pSem = pFile->pInode->pSem;


    if( sem_trywait(pSem)==-1 ){
      int tErrno = errno;
      if( EAGAIN != tErrno ){
        rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_CHECKRESERVEDLOCK);
        pFile->lastErrno = tErrno;
      } else {

** access the file.
**
** This routine will only increase a lock.  Use the sqlite3OsUnlock()
** routine to lower a locking level.
*/
static int semLock(sqlite3_file *id, int eFileLock) {
  unixFile *pFile = (unixFile*)id;

  sem_t *pSem = pFile->pInode->pSem;
  int rc = SQLITE_OK;

  /* if we already have a lock, it is exclusive.  
  ** Just adjust level and punt on outta here. */
  if (pFile->eFileLock > NO_LOCK) {
    pFile->eFileLock = eFileLock;

  const char *zPath,        /* Name of file to be deleted */
  int dirSync               /* If true, fsync() directory after deleting file */
){
  int rc = SQLITE_OK;
  UNUSED_PARAMETER(NotUsed);
  SimulateIOError(return SQLITE_IOERR_DELETE);
  if( osUnlink(zPath)==(-1) ){
    if( errno==ENOENT
#if OS_VXWORKS
        || errno==0x380003
#endif
    ){
      rc = SQLITE_IOERR_DELETE_NOENT;
    }else{
      rc = unixLogError(SQLITE_IOERR_DELETE, "unlink", zPath);
    }
    return rc;
  }
#ifndef SQLITE_DISABLE_DIRSYNC

#endif

#ifndef NTDDI_WINBLUE
#  define NTDDI_WINBLUE                     0x06030000
#endif

/*
** Check to see if the GetVersionEx[AW] functions are deprecated on the
** target system.  GetVersionEx was first deprecated in Win8.1.




*/
#ifndef SQLITE_WIN32_GETVERSIONEX
#  if defined(NTDDI_VERSION) && NTDDI_VERSION >= NTDDI_WINBLUE
#    define SQLITE_WIN32_GETVERSIONEX   0   /* GetVersionEx() is deprecated */
#  else
#    define SQLITE_WIN32_GETVERSIONEX   1   /* GetVersionEx() is current */
#  endif
#endif

/*
** This constant should already be defined (in the "WinDef.h" SDK file).
*/
#ifndef MAX_PATH

#endif

/*
** This macro is used when a local variable is set to a value that is
** [sometimes] not used by the code (e.g. via conditional compilation).
*/
#ifndef UNUSED_VARIABLE_VALUE
#  define UNUSED_VARIABLE_VALUE(x)      (void)(x)
#endif

/*
** Returns the character that should be used as the directory separator.
*/
#ifndef winGetDirSep
#  define winGetDirSep()                '\\'

WINBASEAPI BOOL WINAPI UnmapViewOfFile(LPCVOID);
#endif /* SQLITE_WIN32_FILEMAPPING_API && !defined(SQLITE_OMIT_WAL) */

/*
** Some Microsoft compilers lack this definition.
*/
#ifndef INVALID_FILE_ATTRIBUTES
# define INVALID_FILE_ATTRIBUTES ((DWORD)-1)
#endif

#ifndef FILE_FLAG_MASK
# define FILE_FLAG_MASK          (0xFF3C0000)
#endif

#ifndef FILE_ATTRIBUTE_MASK

#ifndef SQLITE_OMIT_WAL
  winShm *pShm;           /* Instance of shared memory on this file */
#endif
  const char *zPath;      /* Full pathname of this file */
  int szChunk;            /* Chunk size configured by FCNTL_CHUNK_SIZE */
#if SQLITE_OS_WINCE
  LPWSTR zDeleteOnClose;  /* Name of file to delete when closing */
  HANDLE hMutex;          /* Mutex used to control access to shared lock */
  HANDLE hShared;         /* Shared memory segment used for locking */
  winceLock local;        /* Locks obtained by this instance of winFile */
  winceLock *shared;      /* Global shared lock memory for the file  */
#endif
#if SQLITE_MAX_MMAP_SIZE>0
  int nFetchOut;                /* Number of outstanding xFetch references */
  HANDLE hMap;                  /* Handle for accessing memory mapping */

** 1:   Operating system is Win9x.
** 2:   Operating system is WinNT.
**
** In order to facilitate testing on a WinNT system, the test fixture
** can manually set this value to 1 to emulate Win98 behavior.
*/
#ifdef SQLITE_TEST
LONG SQLITE_WIN32_VOLATILE sqlite3_os_type = 0;
#else

static LONG SQLITE_WIN32_VOLATILE sqlite3_os_type = 0;
#endif

#ifndef SYSCALL
#  define SYSCALL sqlite3_syscall_ptr
#endif

/*

#else
  { "CreateFileMappingFromApp", (SYSCALL)0,                      0 },
#endif

#define osCreateFileMappingFromApp ((HANDLE(WINAPI*)(HANDLE, \
        LPSECURITY_ATTRIBUTES,ULONG,ULONG64,LPCWSTR))aSyscall[75].pCurrent)

/*
** NOTE: On some sub-platforms, the InterlockedCompareExchange "function"
**       is really just a macro that uses a compiler intrinsic (e.g. x64).
**       So do not try to make this is into a redefinable interface.
*/
#if defined(InterlockedCompareExchange)
  { "InterlockedCompareExchange", (SYSCALL)0,                    0 },

#define osInterlockedCompareExchange InterlockedCompareExchange
#else
  { "InterlockedCompareExchange", (SYSCALL)InterlockedCompareExchange, 0 },

#define osInterlockedCompareExchange ((LONG(WINAPI*)(LONG \
        SQLITE_WIN32_VOLATILE*, LONG,LONG))aSyscall[76].pCurrent)
#endif /* defined(InterlockedCompareExchange) */

}; /* End of the overrideable system calls */

/*
** This is the xSetSystemCall() method of sqlite3_vfs for all of the
** "win32" VFSes.  Return SQLITE_OK opon successfully updating the
** system call pointer, or SQLITE_NOTFOUND if there is no configurable
** system call named zName.

#if !defined(SQLITE_WIN32_GETVERSIONEX) || !SQLITE_WIN32_GETVERSIONEX
# define osIsNT()  (1)
#elif SQLITE_OS_WINCE || SQLITE_OS_WINRT || !defined(SQLITE_WIN32_HAS_ANSI)
# define osIsNT()  (1)
#elif !defined(SQLITE_WIN32_HAS_WIDE)
# define osIsNT()  (0)
#else
# define osIsNT()  ((sqlite3_os_type==2) || sqlite3_win32_is_nt())
#endif

/*
** This function determines if the machine is running a version of Windows
** based on the NT kernel.
*/
int sqlite3_win32_is_nt(void){
#if defined(SQLITE_WIN32_GETVERSIONEX) && SQLITE_WIN32_GETVERSIONEX
  if( osInterlockedCompareExchange(&sqlite3_os_type, 0, 0)==0 ){
#if !SQLITE_OS_WINRT && defined(SQLITE_WIN32_HAS_WIDE) && \
        defined(NTDDI_VERSION) && NTDDI_VERSION >= NTDDI_WIN8
    OSVERSIONINFOW sInfo;
    sInfo.dwOSVersionInfoSize = sizeof(sInfo);
    osGetVersionExW(&sInfo);
    osInterlockedCompareExchange(&sqlite3_os_type,
        (sInfo.dwPlatformId == VER_PLATFORM_WIN32_NT) ? 2 : 1, 0);
#elif defined(SQLITE_WIN32_HAS_ANSI)
    OSVERSIONINFOA sInfo;
    sInfo.dwOSVersionInfoSize = sizeof(sInfo);
    osGetVersionExA(&sInfo);
    osInterlockedCompareExchange(&sqlite3_os_type,
        (sInfo.dwPlatformId == VER_PLATFORM_WIN32_NT) ? 2 : 1, 0);
#endif

  }
  return osInterlockedCompareExchange(&sqlite3_os_type, 2, 2)==2;
#elif SQLITE_TEST
  return osInterlockedCompareExchange(&sqlite3_os_type, 2, 2)==2;
#else
  return 1;

#endif
}

#ifdef SQLITE_WIN32_MALLOC
/*
** Allocate nBytes of memory.
*/
static void *winMemMalloc(int nBytes){
  HANDLE hHeap;

void sqlite3MemSetDefault(void){
  sqlite3_config(SQLITE_CONFIG_MALLOC, sqlite3MemGetWin32());
}
#endif /* SQLITE_WIN32_MALLOC */

/*
** Convert a UTF-8 string to Microsoft Unicode (UTF-16?).
**
** Space to hold the returned string is obtained from malloc.
*/
static LPWSTR winUtf8ToUnicode(const char *zFilename){
  int nChar;
  LPWSTR zWideFilename;

  }
  return zFilename;
}

/*
** Convert an ANSI string to Microsoft Unicode, based on the
** current codepage settings for file apis.
**
** Space to hold the returned string is obtained
** from sqlite3_malloc.
*/
static LPWSTR winMbcsToUnicode(const char *zFilename){
  int nByte;
  LPWSTR zMbcsFilename;
  int codepage = osAreFileApisANSI() ? CP_ACP : CP_OEMCP;

  }
  zFilenameUtf8 = winUnicodeToUtf8(zTmpWide);
  sqlite3_free(zTmpWide);
  return zFilenameUtf8;
}

/*
** Convert UTF-8 to multibyte character string.  Space to hold the
** returned string is obtained from sqlite3_malloc().
*/
char *sqlite3_win32_utf8_to_mbcs(const char *zFilename){
  char *zFilenameMbcs;
  LPWSTR zTmpWide;

  zTmpWide = winUtf8ToUnicode(zFilename);

/*
**
** This function - winLogErrorAtLine() - is only ever called via the macro
** winLogError().
**
** This routine is invoked after an error occurs in an OS function.
** It logs a message using sqlite3_log() containing the current value of
** error code and, if possible, the human-readable equivalent from
** FormatMessage.
**
** The first argument passed to the macro should be the error code that
** will be returned to SQLite (e.g. SQLITE_IOERR_DELETE, SQLITE_CANTOPEN).
** The two subsequent arguments should be the name of the OS function that
** failed and the associated file-system path, if any.
*/
#define winLogError(a,b,c,d)   winLogErrorAtLine(a,b,c,d,__LINE__)
static int winLogErrorAtLine(
  int errcode,                    /* SQLite error code */
  DWORD lastErrno,                /* Win32 last error */

  );

  return errcode;
}

/*
** The number of times that a ReadFile(), WriteFile(), and DeleteFile()
** will be retried following a locking error - probably caused by
** antivirus software.  Also the initial delay before the first retry.
** The delay increases linearly with each retry.
*/
#ifndef SQLITE_WIN32_IOERR_RETRY
# define SQLITE_WIN32_IOERR_RETRY 10
#endif
#ifndef SQLITE_WIN32_IOERR_RETRY_DELAY

}

/*
** Log a I/O error retry episode.
*/
static void winLogIoerr(int nRetry){
  if( nRetry ){
    sqlite3_log(SQLITE_IOERR,
      "delayed %dms for lock/sharing conflict",
      winIoerrRetryDelay*nRetry*(nRetry+1)/2
    );
  }
}

#if SQLITE_OS_WINCE

    sqlite3_free(zName);
    return winLogError(SQLITE_IOERR, pFile->lastErrno,
                       "winceCreateLock1", zFilename);
  }

  /* Acquire the mutex before continuing */
  winceMutexAcquire(pFile->hMutex);

  /* Since the names of named mutexes, semaphores, file mappings etc are
  ** case-sensitive, take advantage of that by uppercasing the mutex name
  ** and using that as the shared filemapping name.
  */
  osCharUpperW(zName);
  pFile->hShared = osCreateFileMappingW(INVALID_HANDLE_VALUE, NULL,
                                        PAGE_READWRITE, 0, sizeof(winceLock),
                                        zName);

  /* Set a flag that indicates we're the first to create the memory so it
  ** must be zero-initialized */
  lastErrno = osGetLastError();
  if (lastErrno == ERROR_ALREADY_EXISTS){
    bInit = FALSE;
  }

  sqlite3_free(zName);

  /* If we succeeded in making the shared memory handle, map it. */
  if( pFile->hShared ){
    pFile->shared = (winceLock*)osMapViewOfFile(pFile->hShared,
             FILE_MAP_READ|FILE_MAP_WRITE, 0, 0, sizeof(winceLock));
    /* If mapping failed, close the shared memory handle and erase it */
    if( !pFile->shared ){
      pFile->lastErrno = osGetLastError();
      winLogError(SQLITE_IOERR, pFile->lastErrno,
                  "winceCreateLock2", zFilename);
      bLogged = TRUE;

      bLogged = TRUE;
    }
    winceMutexRelease(pFile->hMutex);
    osCloseHandle(pFile->hMutex);
    pFile->hMutex = NULL;
    return SQLITE_IOERR;
  }

  /* Initialize the shared memory if we're supposed to */
  if( bInit ){
    memset(pFile->shared, 0, sizeof(winceLock));
  }

  winceMutexRelease(pFile->hMutex);
  return SQLITE_OK;

    }

    /* De-reference and close our copy of the shared memory handle */
    osUnmapViewOfFile(pFile->shared);
    osCloseHandle(pFile->hShared);

    /* Done with the mutex */
    winceMutexRelease(pFile->hMutex);
    osCloseHandle(pFile->hMutex);
    pFile->hMutex = NULL;
  }
}

/*
** An implementation of the LockFile() API of Windows for CE
*/
static BOOL winceLockFile(
  LPHANDLE phFile,
  DWORD dwFileOffsetLow,
  DWORD dwFileOffsetHigh,
  DWORD nNumberOfBytesToLockLow,

** Some Microsoft compilers lack this definition.
*/
#ifndef INVALID_SET_FILE_POINTER
# define INVALID_SET_FILE_POINTER ((DWORD)-1)
#endif

/*
** Move the current position of the file handle passed as the first
** argument to offset iOffset within the file. If successful, return 0.
** Otherwise, set pFile->lastErrno and return non-zero.
*/
static int winSeekFile(winFile *pFile, sqlite3_int64 iOffset){
#if !SQLITE_OS_WINRT
  LONG upperBits;                 /* Most sig. 32 bits of new offset */
  LONG lowerBits;                 /* Least sig. 32 bits of new offset */
  DWORD dwRet;                    /* Value returned by SetFilePointer() */
  DWORD lastErrno;                /* Value returned by GetLastError() */

  OSTRACE(("SEEK file=%p, offset=%lld\n", pFile->h, iOffset));

  upperBits = (LONG)((iOffset>>32) & 0x7fffffff);
  lowerBits = (LONG)(iOffset & 0xffffffff);

  /* API oddity: If successful, SetFilePointer() returns a dword
  ** containing the lower 32-bits of the new file-offset. Or, if it fails,
  ** it returns INVALID_SET_FILE_POINTER. However according to MSDN,
  ** INVALID_SET_FILE_POINTER may also be a valid new offset. So to determine
  ** whether an error has actually occurred, it is also necessary to call
  ** GetLastError().
  */
  dwRet = osSetFilePointer(pFile->h, lowerBits, &upperBits, FILE_BEGIN);

  if( (dwRet==INVALID_SET_FILE_POINTER
      && ((lastErrno = osGetLastError())!=NO_ERROR)) ){
    pFile->lastErrno = lastErrno;

#if SQLITE_OS_WINCE
#define WINCE_DELETION_ATTEMPTS 3
  winceDestroyLock(pFile);
  if( pFile->zDeleteOnClose ){
    int cnt = 0;
    while(
           osDeleteFileW(pFile->zDeleteOnClose)==0
        && osGetFileAttributesW(pFile->zDeleteOnClose)!=0xffffffff
        && cnt++ < WINCE_DELETION_ATTEMPTS
    ){
       sqlite3_win32_sleep(100);  /* Wait a little before trying again */
    }
    sqlite3_free(pFile->zDeleteOnClose);
  }
#endif

*/
static int winDeviceCharacteristics(sqlite3_file *id){
  winFile *p = (winFile*)id;
  return SQLITE_IOCAP_UNDELETABLE_WHEN_OPEN |
         ((p->ctrlFlags & WINFILE_PSOW)?SQLITE_IOCAP_POWERSAFE_OVERWRITE:0);
}

/*
** Windows will only let you create file view mappings
** on allocation size granularity boundaries.
** During sqlite3_os_init() we do a GetSystemInfo()
** to get the granularity size.
*/
static SYSTEM_INFO winSysInfo;

#ifndef SQLITE_OMIT_WAL

/*
** Helper functions to obtain and relinquish the global mutex. The
** global mutex is used to protect the winLockInfo objects used by
** this file, all of which may be shared by multiple threads.
**
** Function winShmMutexHeld() is used to assert() that the global mutex
** is held when required. This function is only used as part of assert()
** statements. e.g.
**
**   winShmEnterMutex()
**     assert( winShmMutexHeld() );
**   winShmLeaveMutex()
*/
static void winShmEnterMutex(void){

** point to a single instance of this object.  In other words, each
** log-summary is opened only once per process.
**
** winShmMutexHeld() must be true when creating or destroying
** this object or while reading or writing the following fields:
**
**      nRef
**      pNext
**
** The following fields are read-only after the object is created:
**
**      fid
**      zFilename
**
** Either winShmNode.mutex must be held or winShmNode.nRef==0 and
** winShmMutexHeld() is true when reading or writing any other field
** in this structure.
**

    rc = winUnlockFile(&pFile->hFile.h, ofst, 0, nByte, 0);
  }else{
    /* Initialize the locking parameters */
    DWORD dwFlags = LOCKFILE_FAIL_IMMEDIATELY;
    if( lockType == _SHM_WRLCK ) dwFlags |= LOCKFILE_EXCLUSIVE_LOCK;
    rc = winLockFile(&pFile->hFile.h, dwFlags, ofst, 0, nByte, 0);
  }

  if( rc!= 0 ){
    rc = SQLITE_OK;
  }else{
    pFile->lastErrno =  osGetLastError();
    rc = SQLITE_BUSY;
  }

  pNew = sqlite3MallocZero( sizeof(*pShmNode) + nName + 17 );
  if( pNew==0 ){
    sqlite3_free(p);
    return SQLITE_IOERR_NOMEM;
  }
  pNew->zFilename = (char*)&pNew[1];
  sqlite3_snprintf(nName+15, pNew->zFilename, "%s-shm", pDbFd->zPath);
  sqlite3FileSuffix3(pDbFd->zPath, pNew->zFilename);

  /* Look to see if there is an existing winShmNode that can be used.
  ** If no matching winShmNode currently exists, create a new one.
  */
  winShmEnterMutex();
  for(pShmNode = winShmNodeList; pShmNode; pShmNode=pShmNode->pNext){
    /* TBD need to come up with better match here.  Perhaps

                 SQLITE_OPEN_WAL | SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE,
                 0);
    if( SQLITE_OK!=rc ){
      goto shm_open_err;
    }

    /* Check to see if another process is holding the dead-man switch.
    ** If not, truncate the file to zero length.
    */
    if( winShmSystemLock(pShmNode, _SHM_WRLCK, WIN_SHM_DMS, 1)==SQLITE_OK ){
      rc = winTruncate((sqlite3_file *)&pShmNode->hFile, 0);
      if( rc!=SQLITE_OK ){
        rc = winLogError(SQLITE_IOERR_SHMOPEN, osGetLastError(),
                         "winOpenShm", pDbFd->zPath);
      }

  pDbFd->pShm = p;
  winShmLeaveMutex();

  /* The reference count on pShmNode has already been incremented under
  ** the cover of the winShmEnterMutex() mutex and the pointer from the
  ** new (struct winShm) object to the pShmNode has been set. All that is
  ** left to do is to link the new object into the linked list starting
  ** at pShmNode->pFirst. This must be done while holding the pShmNode->mutex
  ** mutex.
  */
  sqlite3_mutex_enter(pShmNode->mutex);
  p->pNext = pShmNode->pFirst;
  pShmNode->pFirst = p;
  sqlite3_mutex_leave(pShmNode->mutex);
  return SQLITE_OK;

  /* Jump here on any error */
shm_open_err:
  winShmSystemLock(pShmNode, _SHM_UNLCK, WIN_SHM_DMS, 1);
  winShmPurge(pDbFd->pVfs, 0);      /* This call frees pShmNode if required */
  sqlite3_free(p);
  sqlite3_free(pNew);
  winShmLeaveMutex();
  return rc;
}

/*
** Close a connection to shared-memory.  Delete the underlying
** storage if deleteFlag is true.
*/
static int winShmUnmap(
  sqlite3_file *fd,          /* Database holding shared memory */
  int deleteFlag             /* Delete after closing if true */
){
  winFile *pDbFd;       /* Database holding shared-memory */

      rc = SQLITE_OK;
    }

    /* Undo the local locks */
    if( rc==SQLITE_OK ){
      p->exclMask &= ~mask;
      p->sharedMask &= ~mask;
    }
  }else if( flags & SQLITE_SHM_SHARED ){
    u16 allShared = 0;  /* Union of locks held by connections other than "p" */

    /* Find out which shared locks are already held by sibling connections.
    ** If any sibling already holds an exclusive lock, go ahead and return
    ** SQLITE_BUSY.
    */

    */
    for(pX=pShmNode->pFirst; pX; pX=pX->pNext){
      if( (pX->exclMask & mask)!=0 || (pX->sharedMask & mask)!=0 ){
        rc = SQLITE_BUSY;
        break;
      }
    }

    /* Get the exclusive locks at the system level.  Then if successful
    ** also mark the local connection as being locked.
    */
    if( rc==SQLITE_OK ){
      rc = winShmSystemLock(pShmNode, _SHM_WRLCK, ofst+WIN_SHM_BASE, n);
      if( rc==SQLITE_OK ){
        assert( (p->sharedMask & mask)==0 );
        p->exclMask |= mask;
      }
    }
  }
  sqlite3_mutex_leave(pShmNode->mutex);
  OSTRACE(("SHM-LOCK pid=%lu, id=%d, sharedMask=%03x, exclMask=%03x, rc=%s\n",
           osGetCurrentProcessId(), p->id, p->sharedMask, p->exclMask,
           sqlite3ErrName(rc)));
  return rc;
}

/*
** Implement a memory barrier or memory fence on shared memory.
**
** All loads and stores begun before the barrier must complete before
** any load or store begun after the barrier.
*/
static void winShmBarrier(
  sqlite3_file *fd          /* Database holding the shared memory */
){
  UNUSED_PARAMETER(fd);
  /* MemoryBarrier(); // does not work -- do not know why not */
  winShmEnterMutex();
  winShmLeaveMutex();
}

/*
** This function is called to obtain a pointer to region iRegion of the
** shared-memory associated with the database file fd. Shared-memory regions
** are numbered starting from zero. Each shared-memory region is szRegion
** bytes in size.
**
** If an error occurs, an error code is returned and *pp is set to NULL.
**
** Otherwise, if the isWrite parameter is 0 and the requested shared-memory
** region has not been allocated (by any client, including one running in a
** separate process), then *pp is set to NULL and SQLITE_OK returned. If
** isWrite is non-zero and the requested shared-memory region has not yet
** been allocated, it is allocated by this function.
**
** If the shared-memory region has already been allocated or is allocated by
** this call as described above, then it is mapped into this processes
** address space (if it is not already), *pp is set to point to the mapped
** memory and SQLITE_OK returned.
*/
static int winShmMap(
  sqlite3_file *fd,               /* Handle open on database file */
  int iRegion,                    /* Region to retrieve */
  int szRegion,                   /* Size of regions */
  int isWrite,                    /* True to extend file if necessary */

      goto shmpage_out;
    }
    pShmNode->aRegion = apNew;

    while( pShmNode->nRegion<=iRegion ){
      HANDLE hMap = NULL;         /* file-mapping handle */
      void *pMap = 0;             /* Mapped memory region */

#if SQLITE_OS_WINRT
      hMap = osCreateFileMappingFromApp(pShmNode->hFile.h,
          NULL, PAGE_READWRITE, nByte, NULL
      );
#elif defined(SQLITE_WIN32_HAS_WIDE)
      hMap = osCreateFileMappingW(pShmNode->hFile.h,
          NULL, PAGE_READWRITE, 0, nByte, NULL
      );
#elif defined(SQLITE_WIN32_HAS_ANSI)
      hMap = osCreateFileMappingA(pShmNode->hFile.h,
          NULL, PAGE_READWRITE, 0, nByte, NULL
      );
#endif
      OSTRACE(("SHM-MAP-CREATE pid=%lu, region=%d, size=%d, rc=%s\n",
               osGetCurrentProcessId(), pShmNode->nRegion, nByte,
               hMap ? "ok" : "failed"));
      if( hMap ){

  OSTRACE(("UNMAP-FILE pid=%lu, pFile=%p, rc=SQLITE_OK\n",
           osGetCurrentProcessId(), pFile));
  return SQLITE_OK;
}

/*
** Memory map or remap the file opened by file-descriptor pFd (if the file
** is already mapped, the existing mapping is replaced by the new). Or, if
** there already exists a mapping for this file, and there are still
** outstanding xFetch() references to it, this function is a no-op.
**
** If parameter nByte is non-negative, then it is the requested size of
** the mapping to create. Otherwise, if nByte is less than zero, then the
** requested size is the size of the file on disk. The actual size of the
** created mapping is either the requested size or the value configured
** using SQLITE_FCNTL_MMAP_SIZE, whichever is smaller.
**
** SQLITE_OK is returned if no error occurs (even if the mapping is not
** recreated as a result of outstanding references) or an SQLite error
** code otherwise.
*/
static int winMapfile(winFile *pFd, sqlite3_int64 nByte){

      return SQLITE_IOERR_FSTAT;
    }
  }
  if( nMap>pFd->mmapSizeMax ){
    nMap = pFd->mmapSizeMax;
  }
  nMap &= ~(sqlite3_int64)(winSysInfo.dwPageSize - 1);

  if( nMap==0 && pFd->mmapSize>0 ){
    winUnmapfile(pFd);
  }
  if( nMap!=pFd->mmapSize ){
    void *pNew = 0;
    DWORD protect = PAGE_READONLY;
    DWORD flags = FILE_MAP_READ;

** iOff. The mapping must be valid for at least nAmt bytes.
**
** If such a pointer can be obtained, store it in *pp and return SQLITE_OK.
** Or, if one cannot but no error occurs, set *pp to 0 and return SQLITE_OK.
** Finally, if an error does occur, return an SQLite error code. The final
** value of *pp is undefined in this case.
**
** If this function does return a pointer, the caller must eventually
** release the reference by calling winUnfetch().
*/
static int winFetch(sqlite3_file *fd, i64 iOff, int nAmt, void **pp){
#if SQLITE_MAX_MMAP_SIZE>0
  winFile *pFd = (winFile*)fd;   /* The underlying database file */
#endif
  *pp = 0;

  OSTRACE(("FETCH pid=%lu, pFile=%p, pp=%p, *pp=%p, rc=SQLITE_OK\n",
           osGetCurrentProcessId(), fd, pp, *pp));
  return SQLITE_OK;
}

/*
** If the third argument is non-NULL, then this function releases a
** reference obtained by an earlier call to winFetch(). The second
** argument passed to this function must be the same as the corresponding
** argument that was passed to the winFetch() invocation.
**
** Or, if the third argument is NULL, then this function is being called
** to inform the VFS layer that, according to POSIX, any existing mapping
** may now be invalid and should be unmapped.
*/
static int winUnfetch(sqlite3_file *fd, i64 iOff, void *p){
#if SQLITE_MAX_MMAP_SIZE>0
  winFile *pFd = (winFile*)fd;   /* The underlying database file */

  /* If p==0 (unmap the entire file) then there must be no outstanding
  ** xFetch references. Or, if p!=0 (meaning it is an xFetch reference),
  ** then there must be at least one outstanding.  */
  assert( (p==0)==(pFd->nFetchOut==0) );

  /* If p!=0, it must match the iOff value. */
  assert( p==0 || p==&((u8 *)pFd->pMapRegion)[iOff] );

  size_t i, j;
  int nPre = sqlite3Strlen30(SQLITE_TEMP_FILE_PREFIX);
  int nMax, nBuf, nDir, nLen;
  char *zBuf;

  /* It's odd to simulate an io-error here, but really this is just
  ** using the io-error infrastructure to test that SQLite handles this
  ** function failing.
  */
  SimulateIOError( return SQLITE_IOERR );

  /* Allocate a temporary buffer to store the fully qualified file
  ** name for the temporary file.  If this fails, we cannot continue.
  */
  nMax = pVfs->mxPathname; nBuf = nMax + 2;

  if( !winMakeEndInDirSep(nDir+1, zBuf) ){
    sqlite3_free(zBuf);
    OSTRACE(("TEMP-FILENAME rc=SQLITE_ERROR\n"));
    return winLogError(SQLITE_ERROR, 0, "winGetTempname4", 0);
  }

  /*
  ** Check that the output buffer is large enough for the temporary file
  ** name in the following format:
  **
  **   "<temporary_directory>/etilqs_XXXXXXXXXXXXXXX\0\0"
  **
  ** If not, return SQLITE_ERROR.  The number 17 is used here in order to
  ** account for the space used by the 15 character random suffix and the
  ** two trailing NUL characters.  The final directory separator character

  int isDelete     = (flags & SQLITE_OPEN_DELETEONCLOSE);
  int isCreate     = (flags & SQLITE_OPEN_CREATE);
  int isReadonly   = (flags & SQLITE_OPEN_READONLY);
  int isReadWrite  = (flags & SQLITE_OPEN_READWRITE);

#ifndef NDEBUG
  int isOpenJournal = (isCreate && (
        eType==SQLITE_OPEN_MASTER_JOURNAL
     || eType==SQLITE_OPEN_MAIN_JOURNAL
     || eType==SQLITE_OPEN_WAL
  ));
#endif

  OSTRACE(("OPEN name=%s, pFile=%p, flags=%x, pOutFlags=%p\n",
           zUtf8Name, id, flags, pOutFlags));

  /* Check the following statements are true:
  **
  **   (a) Exactly one of the READWRITE and READONLY flags must be set, and
  **   (b) if CREATE is set, then READWRITE must also be set, and
  **   (c) if EXCLUSIVE is set, then CREATE must also be set.
  **   (d) if DELETEONCLOSE is set, then CREATE must also be set.
  */
  assert((isReadonly==0 || isReadWrite==0) && (isReadWrite || isReadonly));
  assert(isCreate==0 || isReadWrite);
  assert(isExclusive==0 || isCreate);
  assert(isDelete==0 || isCreate);

  /* The main DB, main journal, WAL file and master journal are never
  ** automatically deleted. Nor are they ever temporary files.  */
  assert( (!isDelete && zName) || eType!=SQLITE_OPEN_MAIN_DB );
  assert( (!isDelete && zName) || eType!=SQLITE_OPEN_MAIN_JOURNAL );
  assert( (!isDelete && zName) || eType!=SQLITE_OPEN_MASTER_JOURNAL );
  assert( (!isDelete && zName) || eType!=SQLITE_OPEN_WAL );

  /* Assert that the upper layer has set one of the "file-type" flags. */
  assert( eType==SQLITE_OPEN_MAIN_DB      || eType==SQLITE_OPEN_TEMP_DB
       || eType==SQLITE_OPEN_MAIN_JOURNAL || eType==SQLITE_OPEN_TEMP_JOURNAL
       || eType==SQLITE_OPEN_SUBJOURNAL   || eType==SQLITE_OPEN_MASTER_JOURNAL
       || eType==SQLITE_OPEN_TRANSIENT_DB || eType==SQLITE_OPEN_WAL
  );

  assert( pFile!=0 );
  memset(pFile, 0, sizeof(winFile));
  pFile->h = INVALID_HANDLE_VALUE;

#if SQLITE_OS_WINRT
  if( !zUtf8Name && !sqlite3_temp_directory ){
    sqlite3_log(SQLITE_ERROR,
        "sqlite3_temp_directory variable should be set for WinRT");
  }
#endif

  /* If the second argument to this function is NULL, generate a
  ** temporary file name to use
  */
  if( !zUtf8Name ){
    assert( isDelete && !isOpenJournal );
    rc = winGetTempname(pVfs, &zTmpname);
    if( rc!=SQLITE_OK ){
      OSTRACE(("OPEN name=%s, rc=%s", zUtf8Name, sqlite3ErrName(rc)));
      return rc;

  if( isReadWrite ){
    dwDesiredAccess = GENERIC_READ | GENERIC_WRITE;
  }else{
    dwDesiredAccess = GENERIC_READ;
  }

  /* SQLITE_OPEN_EXCLUSIVE is used to make sure that a new file is
  ** created. SQLite doesn't use it to indicate "exclusive access"
  ** as it is usually understood.
  */
  if( isExclusive ){
    /* Creates a new file, only if it does not already exist. */
    /* If the file exists, it fails. */
    dwCreationDisposition = CREATE_NEW;
  }else if( isCreate ){

  if( h==INVALID_HANDLE_VALUE ){
    pFile->lastErrno = lastErrno;
    winLogError(SQLITE_CANTOPEN, pFile->lastErrno, "winOpen", zUtf8Name);
    sqlite3_free(zConverted);
    sqlite3_free(zTmpname);
    if( isReadWrite && !isExclusive ){
      return winOpen(pVfs, zName, id,
         ((flags|SQLITE_OPEN_READONLY) &
                     ~(SQLITE_OPEN_CREATE|SQLITE_OPEN_READWRITE)),
         pOutFlags);
    }else{
      return SQLITE_CANTOPEN_BKPT;
    }
  }

    return SQLITE_IOERR_NOMEM;
  }
  if( osIsNT() ){
    int cnt = 0;
    WIN32_FILE_ATTRIBUTE_DATA sAttrData;
    memset(&sAttrData, 0, sizeof(sAttrData));
    while( !(rc = osGetFileAttributesExW((LPCWSTR)zConverted,
                             GetFileExInfoStandard,
                             &sAttrData)) && winRetryIoerr(&cnt, &lastErrno) ){}
    if( rc ){
      /* For an SQLITE_ACCESS_EXISTS query, treat a zero-length file
      ** as if it does not exist.
      */
      if(    flags==SQLITE_ACCESS_EXISTS
          && sAttrData.nFileSizeHigh==0
          && sAttrData.nFileSizeLow==0 ){
        attr = INVALID_FILE_ATTRIBUTES;
      }else{
        attr = sAttrData.dwFileAttributes;
      }
    }else{
      winLogIoerr(cnt);

*/
static int winFullPathname(
  sqlite3_vfs *pVfs,            /* Pointer to vfs object */
  const char *zRelative,        /* Possibly relative input path */
  int nFull,                    /* Size of output buffer in bytes */
  char *zFull                   /* Output buffer */
){

#if defined(__CYGWIN__)
  SimulateIOError( return SQLITE_ERROR );
  UNUSED_PARAMETER(nFull);
  assert( nFull>=pVfs->mxPathname );
  if ( sqlite3_data_directory && !winIsVerbatimPathname(zRelative) ){
    /*
    ** NOTE: We are dealing with a relative path name and the data

/*
** Find the current time (in Universal Coordinated Time).  Write into *piNow
** the current time and date as a Julian Day number times 86_400_000.  In
** other words, write into *piNow the number of milliseconds since the Julian
** epoch of noon in Greenwich on November 24, 4714 B.C according to the
** proleptic Gregorian calendar.
**
** On success, return SQLITE_OK.  Return SQLITE_ERROR if the time and date
** cannot be found.
*/
static int winCurrentTimeInt64(sqlite3_vfs *pVfs, sqlite3_int64 *piNow){
  /* FILETIME structure is a 64-bit value representing the number of
     100-nanosecond intervals since January 1, 1601 (= JD 2305813.5).
  */
  FILETIME ft;
  static const sqlite3_int64 winFiletimeEpoch = 23058135*(sqlite3_int64)8640000;
#ifdef SQLITE_TEST
  static const sqlite3_int64 unixEpoch = 24405875*(sqlite3_int64)8640000;
#endif
  /* 2^32 - to avoid use of LL and warnings in gcc */
  static const sqlite3_int64 max32BitValue =
      (sqlite3_int64)2000000000 + (sqlite3_int64)2000000000 +
      (sqlite3_int64)294967296;

#if SQLITE_OS_WINCE
  SYSTEMTIME time;
  osGetSystemTime(&time);
  /* if SystemTimeToFileTime() fails, it returns zero. */
  if (!osSystemTimeToFileTime(&time,&ft)){
    return SQLITE_ERROR;
  }
#else
  osGetSystemTimeAsFileTime( &ft );
#endif

  *piNow = winFiletimeEpoch +
            ((((sqlite3_int64)ft.dwHighDateTime)*max32BitValue) +
               (sqlite3_int64)ft.dwLowDateTime)/(sqlite3_int64)10000;

#ifdef SQLITE_TEST
  if( sqlite3_current_time ){
    *piNow = 1000*(sqlite3_int64)sqlite3_current_time + unixEpoch;
  }
#endif

    winGetSystemCall,    /* xGetSystemCall */
    winNextSystemCall,   /* xNextSystemCall */
  };
#endif

  /* Double-check that the aSyscall[] array has been constructed
  ** correctly.  See ticket [bb3a86e890c8e96ab] */
  assert( ArraySize(aSyscall)==77 );

  /* get memory map allocation granularity */
  memset(&winSysInfo, 0, sizeof(SYSTEM_INFO));
#if SQLITE_OS_WINRT
  osGetNativeSystemInfo(&winSysInfo);
#else
  osGetSystemInfo(&winSysInfo);
#endif
  assert( winSysInfo.dwAllocationGranularity>0 );
  assert( winSysInfo.dwPageSize>0 );

  sqlite3_vfs_register(&winVfs, 1);

#if defined(SQLITE_WIN32_HAS_WIDE)
  sqlite3_vfs_register(&winLongPathVfs, 0);
#endif

  return SQLITE_OK;
}

int sqlite3_os_end(void){
#if SQLITE_OS_WINRT
  if( sleepObj!=NULL ){
    osCloseHandle(sleepObj);
    sleepObj = NULL;
  }
#endif
  return SQLITE_OK;
}

#endif /* SQLITE_OS_WIN */

** Determine if we are dealing with WinRT, which provides only a subset of
** the full Win32 API.
*/
#if !defined(SQLITE_OS_WINRT)
# define SQLITE_OS_WINRT 0
#endif

/*
** For WinCE, some API function parameters do not appear to be declared as
** volatile.
*/
#if SQLITE_OS_WINCE
# define SQLITE_WIN32_VOLATILE
#else
# define SQLITE_WIN32_VOLATILE volatile
#endif

#endif /* _OS_WIN_H_ */

   && jrnlSize>pPager->journalOff
  ){
    rc = sqlite3OsTruncate(pPager->jfd, pPager->journalOff);
  }
  return rc;
}
















/*
** Discard the entire contents of the in-memory page-cache.
*/
static void pager_reset(Pager *pPager){
  sqlite3BackupRestart(pPager->pBackup);
  sqlite3PcacheClear(pPager->pPCache);
}

      }
    }
  }

#ifdef SQLITE_CHECK_PAGES
  sqlite3PcacheIterateDirty(pPager->pPCache, pager_set_pagehash);
  if( pPager->dbSize==0 && sqlite3PcacheRefCount(pPager->pPCache)>0 ){
    PgHdr *p = sqlite3PagerLookup(pPager, 1);
    if( p ){
      p->pageHash = 0;
      sqlite3PagerUnrefNotNull(p);
    }
  }
#endif

  ** 2008-04-14:  When attempting to vacuum a corrupt database file, it
  ** is possible to fail a statement on a database that does not yet exist.
  ** Do not attempt to write if database file has never been opened.
  */
  if( pagerUseWal(pPager) ){
    pPg = 0;
  }else{
    pPg = sqlite3PagerLookup(pPager, pgno);
  }
  assert( pPg || !MEMDB );
  assert( pPager->eState!=PAGER_OPEN || pPg==0 );
  PAGERTRACE(("PLAYBACK %d page %d hash(%08x) %s\n",
           PAGERID(pPager), pgno, pager_datahash(pPager->pageSize, (u8*)aData),
           (isMainJrnl?"main-journal":"sub-journal")
  ));

    if( rc==SQLITE_OK ){
      pager_reset(pPager);
      pPager->dbSize = (Pgno)((nByte+pageSize-1)/pageSize);
      pPager->pageSize = pageSize;
      sqlite3PageFree(pPager->pTmpSpace);
      pPager->pTmpSpace = pNew;
      rc = sqlite3PcacheSetPageSize(pPager->pPCache, pageSize);
    }
  }

  *pPageSize = pPager->pageSize;
  if( rc==SQLITE_OK ){
    if( nReserve<0 ) nReserve = pPager->nReserve;
    assert( nReserve>=0 && nReserve<1000 );

  **
  ** The doNotSpill ROLLBACK and OFF bits inhibits all cache spilling
  ** regardless of whether or not a sync is required.  This is set during
  ** a rollback or by user request, respectively.
  **
  ** Spilling is also prohibited when in an error state since that could
  ** lead to database corruption.   In the current implementaton it 
  ** is impossible for sqlite3PcacheFetch() to be called with createFlag==3
  ** while in the error state, hence it is impossible for this routine to
  ** be called in the error state.  Nevertheless, we include a NEVER()
  ** test for the error state as a safeguard against future changes.
  */
  if( NEVER(pPager->errCode) ) return SQLITE_OK;
  testcase( pPager->doNotSpill & SPILLFLAG_ROLLBACK );
  testcase( pPager->doNotSpill & SPILLFLAG_OFF );

  */
  if( rc==SQLITE_OK ){
    assert( pPager->memDb==0 );
    rc = sqlite3PagerSetPagesize(pPager, &szPageDflt, -1);
    testcase( rc!=SQLITE_OK );
  }

  /* Initialize the PCache object. */
  if( rc==SQLITE_OK ){
    assert( nExtra<1000 );
    nExtra = ROUND8(nExtra);
    rc = sqlite3PcacheOpen(szPageDflt, nExtra, !memDb,
                           !memDb?pagerStress:0, (void *)pPager, pPager->pPCache);
  }

  /* If an error occurred above, free the  Pager structure and close the file.
  */
  if( rc!=SQLITE_OK ){

    sqlite3OsClose(pPager->fd);
    sqlite3PageFree(pPager->pTmpSpace);
    sqlite3_free(pPager);
    return rc;
  }







  PAGERTRACE(("OPEN %d %s\n", FILEHANDLEID(pPager->fd), pPager->zFilename));
  IOTRACE(("OPEN %p %s\n", pPager, pPager->zFilename))

  pPager->useJournal = (u8)useJournal;
  /* pPager->stmtOpen = 0; */
  /* pPager->stmtInUse = 0; */
  /* pPager->nRef = 0; */

  }

  /* If the pager is in the error state, return an error immediately. 
  ** Otherwise, request the page from the PCache layer. */
  if( pPager->errCode!=SQLITE_OK ){
    rc = pPager->errCode;
  }else{

    if( bMmapOk && pagerUseWal(pPager) ){
      rc = sqlite3WalFindFrame(pPager->pWal, pgno, &iFrame);
      if( rc!=SQLITE_OK ) goto pager_acquire_err;
    }

    if( bMmapOk && iFrame==0 ){
      void *pData = 0;

      rc = sqlite3OsFetch(pPager->fd, 
          (i64)(pgno-1) * pPager->pageSize, pPager->pageSize, &pData
      );

      if( rc==SQLITE_OK && pData ){
        if( pPager->eState>PAGER_READER ){
          pPg = sqlite3PagerLookup(pPager, pgno);
        }
        if( pPg==0 ){
          rc = pagerAcquireMapPage(pPager, pgno, pData, &pPg);
        }else{
          sqlite3OsUnfetch(pPager->fd, (i64)(pgno-1)*pPager->pageSize, pData);
        }
        if( pPg ){
          assert( rc==SQLITE_OK );
          *ppPage = pPg;
          return SQLITE_OK;
        }
      }
      if( rc!=SQLITE_OK ){
        goto pager_acquire_err;
      }
    }

    {
      sqlite3_pcache_page *pBase;
      pBase = sqlite3PcacheFetch(pPager->pPCache, pgno, 3);
      if( pBase==0 ){
        rc = sqlite3PcacheFetchStress(pPager->pPCache, pgno, &pBase);
        if( rc!=SQLITE_OK ) goto pager_acquire_err;
      }
      pPg = *ppPage = sqlite3PcacheFetchFinish(pPager->pPCache, pgno, pBase);
      if( pPg==0 ) rc = SQLITE_NOMEM;
    }
  }

  if( rc!=SQLITE_OK ){
    /* Either the call to sqlite3PcacheFetch() returned an error or the
    ** pager was already in the error-state when this function was called.
    ** Set pPg to 0 and jump to the exception handler.  */
    pPg = 0;

** See also sqlite3PagerGet().  The difference between this routine
** and sqlite3PagerGet() is that _get() will go to the disk and read
** in the page if the page is not already in cache.  This routine
** returns NULL if the page is not in cache or if a disk I/O error 
** has ever happened.
*/
DbPage *sqlite3PagerLookup(Pager *pPager, Pgno pgno){
  sqlite3_pcache_page *pPage;
  assert( pPager!=0 );
  assert( pgno!=0 );
  assert( pPager->pPCache!=0 );

  pPage = sqlite3PcacheFetch(pPager->pPCache, pgno, 0);
  return sqlite3PcacheFetchFinish(pPager->pPCache, pgno, pPage);
}

/*
** Release a page reference.
**
** If the number of references to the page drop to zero, then the
** page is added to the LRU list.  When all references to all pages

  /* Update the database size and return.
  */
  if( pPager->dbSize<pPg->pgno ){
    pPager->dbSize = pPg->pgno;
  }
  return rc;
}

/*
** This is a variant of sqlite3PagerWrite() that runs when the sector size
** is larger than the page size.  SQLite makes the (reasonable) assumption that
** all bytes of a sector are written together by hardware.  Hence, all bytes of
** a sector need to be journalled in case of a power loss in the middle of
** a write.
**
** Usually, the sector size is less than or equal to the page size, in which
** case pages can be individually written.  This routine only runs in the exceptional
** case where the page size is smaller than the sector size.
*/
static SQLITE_NOINLINE int pagerWriteLargeSector(PgHdr *pPg){
  int rc = SQLITE_OK;            /* Return code */
  Pgno nPageCount;               /* Total number of pages in database file */
  Pgno pg1;                      /* First page of the sector pPg is located on. */
  int nPage = 0;                 /* Number of pages starting at pg1 to journal */
  int ii;                        /* Loop counter */
  int needSync = 0;              /* True if any page has PGHDR_NEED_SYNC */
  Pager *pPager = pPg->pPager;   /* The pager that owns pPg */
  Pgno nPagePerSector = (pPager->sectorSize/pPager->pageSize);

  /* Set the doNotSpill NOSYNC bit to 1. This is because we cannot allow
  ** a journal header to be written between the pages journaled by
  ** this function.
  */
  assert( !MEMDB );
  assert( (pPager->doNotSpill & SPILLFLAG_NOSYNC)==0 );
  pPager->doNotSpill |= SPILLFLAG_NOSYNC;

  /* This trick assumes that both the page-size and sector-size are
  ** an integer power of 2. It sets variable pg1 to the identifier
  ** of the first page of the sector pPg is located on.
  */
  pg1 = ((pPg->pgno-1) & ~(nPagePerSector-1)) + 1;

  nPageCount = pPager->dbSize;
  if( pPg->pgno>nPageCount ){
    nPage = (pPg->pgno - pg1)+1;
  }else if( (pg1+nPagePerSector-1)>nPageCount ){
    nPage = nPageCount+1-pg1;
  }else{
    nPage = nPagePerSector;
  }
  assert(nPage>0);
  assert(pg1<=pPg->pgno);
  assert((pg1+nPage)>pPg->pgno);

  for(ii=0; ii<nPage && rc==SQLITE_OK; ii++){
    Pgno pg = pg1+ii;
    PgHdr *pPage;
    if( pg==pPg->pgno || !sqlite3BitvecTest(pPager->pInJournal, pg) ){
      if( pg!=PAGER_MJ_PGNO(pPager) ){
        rc = sqlite3PagerGet(pPager, pg, &pPage);
        if( rc==SQLITE_OK ){
          rc = pager_write(pPage);
          if( pPage->flags&PGHDR_NEED_SYNC ){
            needSync = 1;
          }
          sqlite3PagerUnrefNotNull(pPage);
        }
      }
    }else if( (pPage = sqlite3PagerLookup(pPager, pg))!=0 ){
      if( pPage->flags&PGHDR_NEED_SYNC ){
        needSync = 1;
      }
      sqlite3PagerUnrefNotNull(pPage);
    }
  }

  /* If the PGHDR_NEED_SYNC flag is set for any of the nPage pages 
  ** starting at pg1, then it needs to be set for all of them. Because
  ** writing to any of these nPage pages may damage the others, the
  ** journal file must contain sync()ed copies of all of them
  ** before any of them can be written out to the database file.
  */
  if( rc==SQLITE_OK && needSync ){
    assert( !MEMDB );
    for(ii=0; ii<nPage; ii++){
      PgHdr *pPage = sqlite3PagerLookup(pPager, pg1+ii);
      if( pPage ){
        pPage->flags |= PGHDR_NEED_SYNC;
        sqlite3PagerUnrefNotNull(pPage);
      }
    }
  }

  assert( (pPager->doNotSpill & SPILLFLAG_NOSYNC)!=0 );
  pPager->doNotSpill &= ~SPILLFLAG_NOSYNC;
  return rc;
}

/*
** Mark a data page as writeable. This routine must be called before 
** making changes to a page. The caller must check the return value 
** of this function and be careful not to change any page data unless 
** this routine returns SQLITE_OK.
**
** The difference between this function and pager_write() is that this
** function also deals with the special case where 2 or more pages
** fit on a single disk sector. In this case all co-resident pages
** must have been written to the journal file before returning.
**
** If an error occurs, SQLITE_NOMEM or an IO error code is returned
** as appropriate. Otherwise, SQLITE_OK.
*/
int sqlite3PagerWrite(PgHdr *pPg){





  assert( (pPg->flags & PGHDR_MMAP)==0 );
  assert( pPg->pPager->eState>=PAGER_WRITER_LOCKED );
  assert( pPg->pPager->eState!=PAGER_ERROR );
  assert( assert_pager_state(pPg->pPager) );

  if( pPg->pPager->sectorSize > (u32)pPg->pPager->pageSize ){






    return pagerWriteLargeSector(pPg);



















  }else{













    return pager_write(pPg);


  }


































}

/*
** Return TRUE if the page given in the argument was previously passed
** to sqlite3PagerWrite().  In other words, return TRUE if it is ok
** to change the content of the page.
*/

  /* If the cache contains a page with page-number pgno, remove it
  ** from its hash chain. Also, if the PGHDR_NEED_SYNC flag was set for 
  ** page pgno before the 'move' operation, it needs to be retained 
  ** for the page moved there.
  */
  pPg->flags &= ~PGHDR_NEED_SYNC;
  pPgOld = sqlite3PagerLookup(pPager, pgno);
  assert( !pPgOld || pPgOld->nRef==1 );
  if( pPgOld ){
    pPg->flags |= (pPgOld->flags&PGHDR_NEED_SYNC);
    if( MEMDB ){
      /* Do not discard pages from an in-memory database since we might
      ** need to rollback later.  Just move the page out of the way. */
      sqlite3PcacheMove(pPgOld, pPager->dbSize+1);

  for(p=pCache->pDirtyTail; p!=pCache->pSynced; p=p->pDirtyPrev){
    assert( p->nRef || (p->flags&PGHDR_NEED_SYNC) );
  }
  return (p==0 || p->nRef || (p->flags&PGHDR_NEED_SYNC)==0);
}
#endif /* !NDEBUG && SQLITE_ENABLE_EXPENSIVE_ASSERT */

/* Allowed values for second argument to pcacheManageDirtyList() */
#define PCACHE_DIRTYLIST_REMOVE   1    /* Remove pPage from dirty list */
#define PCACHE_DIRTYLIST_ADD      2    /* Add pPage to the dirty list */
#define PCACHE_DIRTYLIST_FRONT    3    /* Move pPage to the front of the list */

/*
** Manage pPage's participation on the dirty list.  Bits of the addRemove
** argument determines what operation to do.  The 0x01 bit means first
** remove pPage from the dirty list.  The 0x02 means add pPage back to
** the dirty list.  Doing both moves pPage to the front of the dirty list.
*/
static void pcacheManageDirtyList(PgHdr *pPage, u8 addRemove){
  PCache *p = pPage->pCache;

  if( addRemove & PCACHE_DIRTYLIST_REMOVE ){
    assert( pPage->pDirtyNext || pPage==p->pDirtyTail );
    assert( pPage->pDirtyPrev || pPage==p->pDirty );
  
    /* Update the PCache1.pSynced variable if necessary. */
    if( p->pSynced==pPage ){
      PgHdr *pSynced = pPage->pDirtyPrev;
      while( pSynced && (pSynced->flags&PGHDR_NEED_SYNC) ){
        pSynced = pSynced->pDirtyPrev;
      }
      p->pSynced = pSynced;
    }
  
    if( pPage->pDirtyNext ){
      pPage->pDirtyNext->pDirtyPrev = pPage->pDirtyPrev;
    }else{
      assert( pPage==p->pDirtyTail );
      p->pDirtyTail = pPage->pDirtyPrev;
    }
    if( pPage->pDirtyPrev ){
      pPage->pDirtyPrev->pDirtyNext = pPage->pDirtyNext;
    }else{
      assert( pPage==p->pDirty );
      p->pDirty = pPage->pDirtyNext;
      if( p->pDirty==0 && p->bPurgeable ){
        assert( p->eCreate==1 );
        p->eCreate = 2;
      }
    }
    pPage->pDirtyNext = 0;
    pPage->pDirtyPrev = 0;

    expensive_assert( pcacheCheckSynced(p) );
  }
  if( addRemove & PCACHE_DIRTYLIST_ADD ){







    assert( pPage->pDirtyNext==0 && pPage->pDirtyPrev==0 && p->pDirty!=pPage );
  
    pPage->pDirtyNext = p->pDirty;
    if( pPage->pDirtyNext ){
      assert( pPage->pDirtyNext->pDirtyPrev==0 );
      pPage->pDirtyNext->pDirtyPrev = pPage;
    }else if( p->bPurgeable ){
      assert( p->eCreate==2 );
      p->eCreate = 1;
    }
    p->pDirty = pPage;
    if( !p->pDirtyTail ){
      p->pDirtyTail = pPage;
    }
    if( !p->pSynced && 0==(pPage->flags&PGHDR_NEED_SYNC) ){
      p->pSynced = pPage;
    }
    expensive_assert( pcacheCheckSynced(p) );
  }
}

/*
** Wrapper around the pluggable caches xUnpin method. If the cache is
** being used for an in-memory database, this function is a no-op.
*/
static void pcacheUnpin(PgHdr *p){

  if( p->pCache->bPurgeable ){
    if( p->pgno==1 ){
      p->pCache->pPage1 = 0;
    }
    sqlite3GlobalConfig.pcache2.xUnpin(p->pCache->pCache, p->pPage, 0);
  }
}

/*
** Compute the number of pages of cache requested.
*/
static int numberOfCachePages(PCache *p){
  if( p->szCache>=0 ){
    return p->szCache;
  }else{
    return (int)((-1024*(i64)p->szCache)/(p->szPage+p->szExtra));
  }
}

/*************************************************** General Interfaces ******
**
** Initialize and shutdown the page cache subsystem. Neither of these 
** functions are threadsafe.

/*
** Create a new PCache object. Storage space to hold the object
** has already been allocated and is passed in as the p pointer. 
** The caller discovers how much space needs to be allocated by 
** calling sqlite3PcacheSize().
*/
int sqlite3PcacheOpen(
  int szPage,                  /* Size of every page */
  int szExtra,                 /* Extra space associated with each page */
  int bPurgeable,              /* True if pages are on backing store */
  int (*xStress)(void*,PgHdr*),/* Call to try to make pages clean */
  void *pStress,               /* Argument to xStress */
  PCache *p                    /* Preallocated space for the PCache */
){
  memset(p, 0, sizeof(PCache));
  p->szPage = 1;
  p->szExtra = szExtra;
  p->bPurgeable = bPurgeable;
  p->eCreate = 2;
  p->xStress = xStress;
  p->pStress = pStress;
  p->szCache = 100;
  return sqlite3PcacheSetPageSize(p, szPage);
}

/*
** Change the page size for PCache object. The caller must ensure that there
** are no outstanding page references when this function is called.
*/
int sqlite3PcacheSetPageSize(PCache *pCache, int szPage){
  assert( pCache->nRef==0 && pCache->pDirty==0 );
  if( pCache->szPage ){
    sqlite3_pcache *pNew;
    pNew = sqlite3GlobalConfig.pcache2.xCreate(
                szPage, pCache->szExtra + sizeof(PgHdr), pCache->bPurgeable
    );
    if( pNew==0 ) return SQLITE_NOMEM;
    sqlite3GlobalConfig.pcache2.xCachesize(pNew, numberOfCachePages(pCache));
    if( pCache->pCache ){
      sqlite3GlobalConfig.pcache2.xDestroy(pCache->pCache);
    }
    pCache->pCache = pNew;
    pCache->pPage1 = 0;

    pCache->szPage = szPage;
  }






  return SQLITE_OK;


}


/*
** Try to obtain a page from the cache.
**
** This routine returns a pointer to an sqlite3_pcache_page object if
** such an object is already in cache, or if a new one is created.
** This routine returns a NULL pointer if the object was not in cache
** and could not be created.
**
** The createFlags should be 0 to check for existing pages and should
** be 3 (not 1, but 3) to try to create a new page.
**
** If the createFlag is 0, then NULL is always returned if the page
** is not already in the cache.  If createFlag is 1, then a new page
** is created only if that can be done without spilling dirty pages
** and without exceeding the cache size limit.
**
** The caller needs to invoke sqlite3PcacheFetchFinish() to properly
** initialize the sqlite3_pcache_page object and convert it into a
** PgHdr object.  The sqlite3PcacheFetch() and sqlite3PcacheFetchFinish()
** routines are split this way for performance reasons. When separated
** they can both (usually) operate without having to push values to
** the stack on entry and pop them back off on exit, which saves a
** lot of pushing and popping.
*/
sqlite3_pcache_page *sqlite3PcacheFetch(
  PCache *pCache,       /* Obtain the page from this cache */
  Pgno pgno,            /* Page number to obtain */
  int createFlag        /* If true, create page if it does not exist already */

){


  int eCreate;

  assert( pCache!=0 );
  assert( pCache->pCache!=0 );
  assert( createFlag==3 || createFlag==0 );
  assert( pgno>0 );




















  /* eCreate defines what to do if the page does not exist.
  **    0     Do not allocate a new page.  (createFlag==0)
  **    1     Allocate a new page if doing so is inexpensive.
  **          (createFlag==1 AND bPurgeable AND pDirty)
  **    2     Allocate a new page even it doing so is difficult.
  **          (createFlag==1 AND !(bPurgeable AND pDirty)
  */
  eCreate = createFlag & pCache->eCreate;
  assert( eCreate==0 || eCreate==1 || eCreate==2 );
  assert( createFlag==0 || pCache->eCreate==eCreate );
  assert( createFlag==0 || eCreate==1+(!pCache->bPurgeable||!pCache->pDirty) );
  return sqlite3GlobalConfig.pcache2.xFetch(pCache->pCache, pgno, eCreate);
}

/*
** If the sqlite3PcacheFetch() routine is unable to allocate a new
** page because new clean pages are available for reuse and the cache
** size limit has been reached, then this routine can be invoked to 
** try harder to allocate a page.  This routine might invoke the stress
** callback to spill dirty pages to the journal.  It will then try to
** allocate the new page and will only fail to allocate a new page on
** an OOM error.
**
** This routine should be invoked only after sqlite3PcacheFetch() fails.
*/
int sqlite3PcacheFetchStress(
  PCache *pCache,                 /* Obtain the page from this cache */
  Pgno pgno,                      /* Page number to obtain */
  sqlite3_pcache_page **ppPage    /* Write result here */
){
  PgHdr *pPg;
  if( pCache->eCreate==2 ) return 0;


  /* Find a dirty page to write-out and recycle. First try to find a 
  ** page that does not require a journal-sync (one with PGHDR_NEED_SYNC
  ** cleared), but if that is not possible settle for any other 
  ** unreferenced dirty page.
  */
  expensive_assert( pcacheCheckSynced(pCache) );
  for(pPg=pCache->pSynced; 
      pPg && (pPg->nRef || (pPg->flags&PGHDR_NEED_SYNC)); 
      pPg=pPg->pDirtyPrev
  );
  pCache->pSynced = pPg;
  if( !pPg ){
    for(pPg=pCache->pDirtyTail; pPg && pPg->nRef; pPg=pPg->pDirtyPrev);
  }
  if( pPg ){
    int rc;
#ifdef SQLITE_LOG_CACHE_SPILL
    sqlite3_log(SQLITE_FULL, 
                "spill page %d making room for %d - cache used: %d/%d",
                pPg->pgno, pgno,
                sqlite3GlobalConfig.pcache.xPagecount(pCache->pCache),
                numberOfCachePages(pCache));
#endif
    rc = pCache->xStress(pCache->pStress, pPg);
    if( rc!=SQLITE_OK && rc!=SQLITE_BUSY ){
      return rc;
    }
  }

  *ppPage = sqlite3GlobalConfig.pcache2.xFetch(pCache->pCache, pgno, 2);
  return *ppPage==0 ? SQLITE_NOMEM : SQLITE_OK;
}

/*
** This is a helper routine for sqlite3PcacheFetchFinish()
**
** In the uncommon case where the page being fetched has not been
** initialized, this routine is invoked to do the initialization.
** This routine is broken out into a separate function since it
** requires extra stack manipulation that can be avoided in the common
** case.
*/
static SQLITE_NOINLINE PgHdr *pcacheFetchFinishWithInit(
  PCache *pCache,             /* Obtain the page from this cache */
  Pgno pgno,                  /* Page number obtained */
  sqlite3_pcache_page *pPage  /* Page obtained by prior PcacheFetch() call */
){
  PgHdr *pPgHdr;
  assert( pPage!=0 );
  pPgHdr = (PgHdr*)pPage->pExtra;

  assert( pPgHdr->pPage==0 );
 memset(pPgHdr, 0, sizeof(PgHdr));
  pPgHdr->pPage = pPage;
  pPgHdr->pData = pPage->pBuf;
  pPgHdr->pExtra = (void *)&pPgHdr[1];
  memset(pPgHdr->pExtra, 0, pCache->szExtra);
  pPgHdr->pCache = pCache;
  pPgHdr->pgno = pgno;
  return sqlite3PcacheFetchFinish(pCache,pgno,pPage);
}

/*
** This routine converts the sqlite3_pcache_page object returned by
** sqlite3PcacheFetch() into an initialized PgHdr object.  This routine
** must be called after sqlite3PcacheFetch() in order to get a usable
** result.
*/
PgHdr *sqlite3PcacheFetchFinish(
  PCache *pCache,             /* Obtain the page from this cache */
  Pgno pgno,                  /* Page number obtained */
  sqlite3_pcache_page *pPage  /* Page obtained by prior PcacheFetch() call */
){
  PgHdr *pPgHdr;

  if( pPage==0 ) return 0;
  pPgHdr = (PgHdr *)pPage->pExtra;

  if( !pPgHdr->pPage ){
    return pcacheFetchFinishWithInit(pCache, pgno, pPage);
  }
  if( 0==pPgHdr->nRef ){
    pCache->nRef++;
  }
  pPgHdr->nRef++;
  if( pgno==1 ){
    pCache->pPage1 = pPgHdr;
  }

  return pPgHdr;

}

/*
** Decrement the reference count on a page. If the page is clean and the
** reference count drops to 0, then it is made elible for recycling.
*/
void SQLITE_NOINLINE sqlite3PcacheRelease(PgHdr *p){
  assert( p->nRef>0 );
  p->nRef--;
  if( p->nRef==0 ){

    p->pCache->nRef--;
    if( (p->flags&PGHDR_DIRTY)==0 ){
      pcacheUnpin(p);
    }else{
      /* Move the page to the head of the dirty list. */

      pcacheManageDirtyList(p, PCACHE_DIRTYLIST_FRONT);
    }
  }
}

/*
** Increase the reference count of a supplied page by 1.
*/
void sqlite3PcacheRef(PgHdr *p){
  assert(p->nRef>0);
  p->nRef++;
}

/*
** Drop a page from the cache. There must be exactly one reference to the
** page. This function deletes that reference, so after it returns the
** page pointed to by p is invalid.
*/
void sqlite3PcacheDrop(PgHdr *p){

  assert( p->nRef==1 );
  if( p->flags&PGHDR_DIRTY ){
    pcacheManageDirtyList(p, PCACHE_DIRTYLIST_REMOVE);
  }

  p->pCache->nRef--;
  if( p->pgno==1 ){
    p->pCache->pPage1 = 0;
  }
  sqlite3GlobalConfig.pcache2.xUnpin(p->pCache->pCache, p->pPage, 1);
}

/*
** Make sure the page is marked as dirty. If it isn't dirty already,
** make it so.
*/
void sqlite3PcacheMakeDirty(PgHdr *p){
  p->flags &= ~PGHDR_DONT_WRITE;
  assert( p->nRef>0 );
  if( 0==(p->flags & PGHDR_DIRTY) ){
    p->flags |= PGHDR_DIRTY;
    pcacheManageDirtyList(p, PCACHE_DIRTYLIST_ADD);
  }
}

/*
** Make sure the page is marked as clean. If it isn't clean already,
** make it so.
*/
void sqlite3PcacheMakeClean(PgHdr *p){
  if( (p->flags & PGHDR_DIRTY) ){
    pcacheManageDirtyList(p, PCACHE_DIRTYLIST_REMOVE);
    p->flags &= ~(PGHDR_DIRTY|PGHDR_NEED_SYNC);
    if( p->nRef==0 ){
      pcacheUnpin(p);
    }
  }
}

void sqlite3PcacheMove(PgHdr *p, Pgno newPgno){
  PCache *pCache = p->pCache;
  assert( p->nRef>0 );
  assert( newPgno>0 );
  sqlite3GlobalConfig.pcache2.xRekey(pCache->pCache, p->pPage, p->pgno,newPgno);
  p->pgno = newPgno;
  if( (p->flags&PGHDR_DIRTY) && (p->flags&PGHDR_NEED_SYNC) ){

    pcacheManageDirtyList(p, PCACHE_DIRTYLIST_FRONT);
  }
}

/*
** Drop every cache entry whose page number is greater than "pgno". The
** caller must ensure that there are no outstanding references to any pages
** other than page 1 with a page number greater than pgno.

  }
}

/*
** Close a cache.
*/
void sqlite3PcacheClose(PCache *pCache){
  assert( pCache->pCache!=0 );
  sqlite3GlobalConfig.pcache2.xDestroy(pCache->pCache);

}

/* 
** Discard the contents of the cache.
*/
void sqlite3PcacheClear(PCache *pCache){
  sqlite3PcacheTruncate(pCache, 0);

  return p->nRef;
}

/* 
** Return the total number of pages in the cache.
*/
int sqlite3PcachePagecount(PCache *pCache){

  assert( pCache->pCache!=0 );
  return sqlite3GlobalConfig.pcache2.xPagecount(pCache->pCache);


}

#ifdef SQLITE_TEST
/*
** Get the suggested cache-size value.
*/
int sqlite3PcacheGetCachesize(PCache *pCache){
  return numberOfCachePages(pCache);
}
#endif

/*
** Set the suggested cache-size value.
*/
void sqlite3PcacheSetCachesize(PCache *pCache, int mxPage){
  assert( pCache->pCache!=0 );
  pCache->szCache = mxPage;

  sqlite3GlobalConfig.pcache2.xCachesize(pCache->pCache,
                                         numberOfCachePages(pCache));

}

/*
** Free up as much memory as possible from the page cache.
*/
void sqlite3PcacheShrink(PCache *pCache){
  assert( pCache->pCache!=0 );
  sqlite3GlobalConfig.pcache2.xShrink(pCache->pCache);

}

#if defined(SQLITE_CHECK_PAGES) || defined(SQLITE_DEBUG)
/*
** For all dirty pages currently in the cache, invoke the specified
** callback. This is only used if the SQLITE_CHECK_PAGES macro is
** defined.

*/
void sqlite3PCacheBufferSetup(void *, int sz, int n);

/* Create a new pager cache.
** Under memory stress, invoke xStress to try to make pages clean.
** Only clean and unpinned pages can be reclaimed.
*/
int sqlite3PcacheOpen(
  int szPage,                    /* Size of every page */
  int szExtra,                   /* Extra space associated with each page */
  int bPurgeable,                /* True if pages are on backing store */
  int (*xStress)(void*, PgHdr*), /* Call to try to make pages clean */
  void *pStress,                 /* Argument to xStress */
  PCache *pToInit                /* Preallocated space for the PCache */
);

/* Modify the page-size after the cache has been created. */
int sqlite3PcacheSetPageSize(PCache *, int);

/* Return the size in bytes of a PCache object.  Used to preallocate
** storage space.
*/
int sqlite3PcacheSize(void);

/* One release per successful fetch.  Page is pinned until released.
** Reference counted. 
*/
sqlite3_pcache_page *sqlite3PcacheFetch(PCache*, Pgno, int createFlag);
int sqlite3PcacheFetchStress(PCache*, Pgno, sqlite3_pcache_page**);
PgHdr *sqlite3PcacheFetchFinish(PCache*, Pgno, sqlite3_pcache_page *pPage);
void sqlite3PcacheRelease(PgHdr*);

void sqlite3PcacheDrop(PgHdr*);         /* Remove page from cache */
void sqlite3PcacheMakeDirty(PgHdr*);    /* Make sure page is marked dirty */
void sqlite3PcacheMakeClean(PgHdr*);    /* Mark a single page as clean */
void sqlite3PcacheCleanAll(PCache*);    /* Mark all dirty list pages as clean */

/*
** This function is used to resize the hash table used by the cache passed
** as the first argument.
**
** The PCache mutex must be held when this function is called.
*/
static void pcache1ResizeHash(PCache1 *p){
  PgHdr1 **apNew;
  unsigned int nNew;
  unsigned int i;

  assert( sqlite3_mutex_held(p->pGroup->mutex) );

  nNew = p->nHash*2;

        apNew[h] = pPage;
      }
    }
    sqlite3_free(p->apHash);
    p->apHash = apNew;
    p->nHash = nNew;
  }


}

/*
** This function is used internally to remove the page pPage from the 
** PGroup LRU list, if is part of it. If pPage is not part of the PGroup
** LRU list, then this function is a no-op.
**

*/
static void pcache1Shutdown(void *NotUsed){
  UNUSED_PARAMETER(NotUsed);
  assert( pcache1.isInit!=0 );
  memset(&pcache1, 0, sizeof(pcache1));
}

/* forward declaration */
static void pcache1Destroy(sqlite3_pcache *p);

/*
** Implementation of the sqlite3_pcache.xCreate method.
**
** Allocate a new cache.
*/
static sqlite3_pcache *pcache1Create(int szPage, int szExtra, int bPurgeable){
  PCache1 *pCache;      /* The newly created page cache */

    }else{
      pGroup = &pcache1.grp;
    }
    pCache->pGroup = pGroup;
    pCache->szPage = szPage;
    pCache->szExtra = szExtra;
    pCache->bPurgeable = (bPurgeable ? 1 : 0);
    pcache1EnterMutex(pGroup);
    pcache1ResizeHash(pCache);
    if( bPurgeable ){
      pCache->nMin = 10;

      pGroup->nMinPage += pCache->nMin;
      pGroup->mxPinned = pGroup->nMaxPage + 10 - pGroup->nMinPage;
    }
    pcache1LeaveMutex(pGroup);
    if( pCache->nHash==0 ){
      pcache1Destroy((sqlite3_pcache*)pCache);
      pCache = 0;
    }
  }
  return (sqlite3_pcache *)pCache;
}

/*
** Implementation of the sqlite3_pcache.xCachesize method. 

  PCache1 *pCache = (PCache1*)p;
  pcache1EnterMutex(pCache->pGroup);
  n = pCache->nPage;
  pcache1LeaveMutex(pCache->pGroup);
  return n;
}


/*
** Implement steps 3, 4, and 5 of the pcache1Fetch() algorithm described
** in the header of the pcache1Fetch() procedure.
**
** This steps are broken out into a separate procedure because they are
** usually not needed, and by avoiding the stack initialization required
** for these steps, the main pcache1Fetch() procedure can run faster.
*/
static SQLITE_NOINLINE PgHdr1 *pcache1FetchStage2(
  PCache1 *pCache, 
  unsigned int iKey, 
  int createFlag
){
  unsigned int nPinned;
  PGroup *pGroup = pCache->pGroup;
  PgHdr1 *pPage = 0;

  /* Step 3: Abort if createFlag is 1 but the cache is nearly full */
  assert( pCache->nPage >= pCache->nRecyclable );
  nPinned = pCache->nPage - pCache->nRecyclable;
  assert( pGroup->mxPinned == pGroup->nMaxPage + 10 - pGroup->nMinPage );
  assert( pCache->n90pct == pCache->nMax*9/10 );
  if( createFlag==1 && (
        nPinned>=pGroup->mxPinned
     || nPinned>=pCache->n90pct
     || pcache1UnderMemoryPressure(pCache)
  )){
    return 0;
  }

  if( pCache->nPage>=pCache->nHash ) pcache1ResizeHash(pCache);
  assert( pCache->nHash>0 && pCache->apHash );

  /* Step 4. Try to recycle a page. */
  if( pCache->bPurgeable && pGroup->pLruTail && (
         (pCache->nPage+1>=pCache->nMax)
      || pGroup->nCurrentPage>=pGroup->nMaxPage
      || pcache1UnderMemoryPressure(pCache)
  )){
    PCache1 *pOther;
    pPage = pGroup->pLruTail;
    assert( pPage->isPinned==0 );
    pcache1RemoveFromHash(pPage);
    pcache1PinPage(pPage);
    pOther = pPage->pCache;

    /* We want to verify that szPage and szExtra are the same for pOther
    ** and pCache.  Assert that we can verify this by comparing sums. */
    assert( (pCache->szPage & (pCache->szPage-1))==0 && pCache->szPage>=512 );
    assert( pCache->szExtra<512 );
    assert( (pOther->szPage & (pOther->szPage-1))==0 && pOther->szPage>=512 );
    assert( pOther->szExtra<512 );

    if( pOther->szPage+pOther->szExtra != pCache->szPage+pCache->szExtra ){
      pcache1FreePage(pPage);
      pPage = 0;
    }else{
      pGroup->nCurrentPage -= (pOther->bPurgeable - pCache->bPurgeable);
    }
  }

  /* Step 5. If a usable page buffer has still not been found, 
  ** attempt to allocate a new one. 
  */
  if( !pPage ){
    if( createFlag==1 ) sqlite3BeginBenignMalloc();
    pPage = pcache1AllocPage(pCache);
    if( createFlag==1 ) sqlite3EndBenignMalloc();
  }

  if( pPage ){
    unsigned int h = iKey % pCache->nHash;
    pCache->nPage++;
    pPage->iKey = iKey;
    pPage->pNext = pCache->apHash[h];
    pPage->pCache = pCache;
    pPage->pLruPrev = 0;
    pPage->pLruNext = 0;
    pPage->isPinned = 1;
    *(void **)pPage->page.pExtra = 0;
    pCache->apHash[h] = pPage;
    if( iKey>pCache->iMaxKey ){
      pCache->iMaxKey = iKey;
    }
  }
  return pPage;
}

/*
** Implementation of the sqlite3_pcache.xFetch method. 
**
** Fetch a page by key value.
**
** Whether or not a new page may be allocated by this function depends on
** the value of the createFlag argument.  0 means do not allocate a new