3.7.4

3.7.5

#! /bin/sh
# Guess values for system-dependent variables and create Makefiles.
# Generated by GNU Autoconf 2.62 for sqlite 3.7.4.
#
# 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='3.7.4'
PACKAGE_STRING='sqlite 3.7.4'
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 3.7.4 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 3.7.4:";;
   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 3.7.4
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 3.7.4, 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 3.7.4, 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 3.7.4
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."

#! /bin/sh
# Guess values for system-dependent variables and create Makefiles.
# Generated by GNU Autoconf 2.62 for sqlite 3.7.5.
#
# 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='3.7.5'
PACKAGE_STRING='sqlite 3.7.5'
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 3.7.5 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 3.7.5:";;
   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 3.7.5
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 3.7.5, 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 3.7.5, 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 3.7.5
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."

  sqlite3_int64 nDoc;

  if( !*ppStmt ){
    int rc = sqlite3Fts3SelectDoctotal(pTab, ppStmt);
    if( rc!=SQLITE_OK ) return rc;
  }
  pStmt = *ppStmt;


  a = sqlite3_column_blob(pStmt, 0);
  a += sqlite3Fts3GetVarint(a, &nDoc);
  *pnDoc = (u32)nDoc;

  if( paLen ) *paLen = a;
  return SQLITE_OK;

  sqlite3_int64 nDoc;

  if( !*ppStmt ){
    int rc = sqlite3Fts3SelectDoctotal(pTab, ppStmt);
    if( rc!=SQLITE_OK ) return rc;
  }
  pStmt = *ppStmt;
  assert( sqlite3_data_count(pStmt)==1 );

  a = sqlite3_column_blob(pStmt, 0);
  a += sqlite3Fts3GetVarint(a, &nDoc);
  *pnDoc = (u32)nDoc;

  if( paLen ) *paLen = a;
  return SQLITE_OK;

      ** varints, where nCol is the number of columns in the FTS3 table.
      ** The first varint is the number of documents currently stored in
      ** the table. The following nCol varints contain the total amount of
      ** data stored in all rows of each column of the table, from left
      ** to right.
      */
      sqlite3_stmt *pStmt;
      rc = fts3SqlStmt(p, SQL_SELECT_DOCTOTAL, &pStmt, 0);
      if( rc ) return rc;
      if( sqlite3_step(pStmt)==SQLITE_ROW ){
        sqlite3_int64 nDoc = 0;
        sqlite3_int64 nByte = 0;



        const char *a = sqlite3_column_blob(pStmt, 0);
        if( a ){
          const char *pEnd = &a[sqlite3_column_bytes(pStmt, 0)];
          a += sqlite3Fts3GetVarint(a, &nDoc);
          while( a<pEnd ){
            a += sqlite3Fts3GetVarint(a, &nByte);
          }
        }




        pCsr->nRowAvg = (int)(((nByte / nDoc) + pgsz - 1) / pgsz);
      }


      rc = sqlite3_reset(pStmt);
      if( rc!=SQLITE_OK || pCsr->nRowAvg==0 ) return rc;
    }

    /* Assume that a blob flows over onto overflow pages if it is larger
    ** than (pgsz-35) bytes in size (the file-format documentation
    ** confirms this).
    */
    for(iBlock=pReader->iStartBlock; iBlock<=pReader->iLeafEndBlock; iBlock++){

      ** varints, where nCol is the number of columns in the FTS3 table.
      ** The first varint is the number of documents currently stored in
      ** the table. The following nCol varints contain the total amount of
      ** data stored in all rows of each column of the table, from left
      ** to right.
      */
      sqlite3_stmt *pStmt;



      sqlite3_int64 nDoc = 0;
      sqlite3_int64 nByte = 0;
      const char *a;
      rc = sqlite3Fts3SelectDoctotal(p, &pStmt);
      if( rc ) return rc;
      a = sqlite3_column_blob(pStmt, 0);
      if( a ){
        const char *pEnd = &a[sqlite3_column_bytes(pStmt, 0)];
        a += sqlite3Fts3GetVarint(a, &nDoc);
        while( a<pEnd ){
          a += sqlite3Fts3GetVarint(a, &nByte);
        }
      }
      if( nDoc==0 || nByte==0 ){
        sqlite3_reset(pStmt);
        return SQLITE_CORRUPT;
      }


      pCsr->nRowAvg = (int)(((nByte / nDoc) + pgsz) / pgsz);
      assert( pCsr->nRowAvg>0 ); 
      rc = sqlite3_reset(pStmt);
      if( rc!=SQLITE_OK ) return rc;
    }

    /* Assume that a blob flows over onto overflow pages if it is larger
    ** than (pgsz-35) bytes in size (the file-format documentation
    ** confirms this).
    */
    for(iBlock=pReader->iStartBlock; iBlock<=pReader->iLeafEndBlock; iBlock++){

  if( i<0 ){
    sqlite3Error(pErrorDb, SQLITE_ERROR, "unknown database %s", zDb);
    return 0;
  }

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











/*
** Create an sqlite3_backup process to copy the contents of zSrcDb from
** connection handle pSrcDb to zDestDb in pDestDb. If successful, return
** a pointer to the new sqlite3_backup object.
**
** If an error occurs, NULL is returned and an error code and error message
................................................................................
    p->pSrc = findBtree(pDestDb, pSrcDb, zSrcDb);
    p->pDest = findBtree(pDestDb, pDestDb, zDestDb);
    p->pDestDb = pDestDb;
    p->pSrcDb = pSrcDb;
    p->iNext = 1;
    p->isAttached = 0;

    if( 0==p->pSrc || 0==p->pDest ){
      /* One (or both) of the named databases did not exist. An error has
      ** already been written into the pDestDb handle. All that is left

      ** to do here is free the sqlite3_backup structure.
      */
      sqlite3_free(p);
      p = 0;
    }
  }
  if( p ){
    p->pSrc->nBackup++;
................................................................................
        **
        **   * Data stored on the pages immediately following the 
        **     pending-byte page in the source database may need to be
        **     copied into the destination database.
        */
        const i64 iSize = (i64)pgszSrc * (i64)nSrcPage;
        sqlite3_file * const pFile = sqlite3PagerFile(pDestPager);



        assert( pFile );
        assert( (i64)nDestTruncate*(i64)pgszDest >= iSize || (
              nDestTruncate==(int)(PENDING_BYTE_PAGE(p->pDest->pBt)-1)
           && iSize>=PENDING_BYTE && iSize<=PENDING_BYTE+pgszDest
        ));
        if( SQLITE_OK==(rc = sqlite3PagerCommitPhaseOne(pDestPager, 0, 1))
         && SQLITE_OK==(rc = backupTruncateFile(pFile, iSize))
         && SQLITE_OK==(rc = sqlite3PagerSync(pDestPager))
        ){
          i64 iOff;
          i64 iEnd = MIN(PENDING_BYTE + pgszDest, iSize);
          for(
            iOff=PENDING_BYTE+pgszSrc; 
            rc==SQLITE_OK && iOff<iEnd; 
            iOff+=pgszSrc
          ){
            PgHdr *pSrcPg = 0;
            const Pgno iSrcPg = (Pgno)((iOff/pgszSrc)+1);
            rc = sqlite3PagerGet(pSrcPager, iSrcPg, &pSrcPg);
            if( rc==SQLITE_OK ){
              u8 *zData = sqlite3PagerGetData(pSrcPg);
              rc = sqlite3OsWrite(pFile, zData, pgszSrc, iOff);
            }
            sqlite3PagerUnref(pSrcPg);





          }
        }
      }else{
        rc = sqlite3PagerCommitPhaseOne(pDestPager, 0, 0);
      }
  
      /* Finish committing the transaction to the destination database. */

  if( i<0 ){
    sqlite3Error(pErrorDb, SQLITE_ERROR, "unknown database %s", zDb);
    return 0;
  }

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

/*
** Attempt to set the page size of the destination to match the page size
** of the source.
*/
static int setDestPgsz(sqlite3_backup *p){
  int rc;
  rc = sqlite3BtreeSetPageSize(p->pDest,sqlite3BtreeGetPageSize(p->pSrc),-1,0);
  return rc;
}

/*
** Create an sqlite3_backup process to copy the contents of zSrcDb from
** connection handle pSrcDb to zDestDb in pDestDb. If successful, return
** a pointer to the new sqlite3_backup object.
**
** If an error occurs, NULL is returned and an error code and error message
................................................................................
    p->pSrc = findBtree(pDestDb, pSrcDb, zSrcDb);
    p->pDest = findBtree(pDestDb, pDestDb, zDestDb);
    p->pDestDb = pDestDb;
    p->pSrcDb = pSrcDb;
    p->iNext = 1;
    p->isAttached = 0;

    if( 0==p->pSrc || 0==p->pDest || setDestPgsz(p)==SQLITE_NOMEM ){
      /* One (or both) of the named databases did not exist or an OOM
      ** error was hit.  The error has already been written into the
      ** pDestDb handle.  All that is left to do here is free the
      ** sqlite3_backup structure.
      */
      sqlite3_free(p);
      p = 0;
    }
  }
  if( p ){
    p->pSrc->nBackup++;
................................................................................
        **
        **   * Data stored on the pages immediately following the 
        **     pending-byte page in the source database may need to be
        **     copied into the destination database.
        */
        const i64 iSize = (i64)pgszSrc * (i64)nSrcPage;
        sqlite3_file * const pFile = sqlite3PagerFile(pDestPager);
        i64 iOff;
        i64 iEnd;

        assert( pFile );
        assert( (i64)nDestTruncate*(i64)pgszDest >= iSize || (
              nDestTruncate==(int)(PENDING_BYTE_PAGE(p->pDest->pBt)-1)
           && iSize>=PENDING_BYTE && iSize<=PENDING_BYTE+pgszDest
        ));





        iEnd = MIN(PENDING_BYTE + pgszDest, iSize);
        for(
          iOff=PENDING_BYTE+pgszSrc; 
          rc==SQLITE_OK && iOff<iEnd; 
          iOff+=pgszSrc
        ){
          PgHdr *pSrcPg = 0;
          const Pgno iSrcPg = (Pgno)((iOff/pgszSrc)+1);
          rc = sqlite3PagerGet(pSrcPager, iSrcPg, &pSrcPg);
          if( rc==SQLITE_OK ){
            u8 *zData = sqlite3PagerGetData(pSrcPg);
            rc = sqlite3OsWrite(pFile, zData, pgszSrc, iOff);
          }
          sqlite3PagerUnref(pSrcPg);
        }
        if( rc==SQLITE_OK ){
          rc = sqlite3PagerCommitPhaseOne(pDestPager, 0, 1);
          if( rc==SQLITE_OK ){
            rc = backupTruncateFile(pFile, iSize);
          }
        }
      }else{
        rc = sqlite3PagerCommitPhaseOne(pDestPager, 0, 0);
      }
  
      /* Finish committing the transaction to the destination database. */

      pBt->usableSize = usableSize;
      pBt->pageSize = pageSize;
      freeTempSpace(pBt);
      rc = sqlite3PagerSetPagesize(pBt->pPager, &pBt->pageSize,
                                   pageSize-usableSize);
      return rc;
    }
    if( nPageHeader>nPageFile ){
      rc = SQLITE_CORRUPT_BKPT;
      goto page1_init_failed;
    }
    if( usableSize<480 ){
      goto page1_init_failed;
    }
    pBt->pageSize = pageSize;

      pBt->usableSize = usableSize;
      pBt->pageSize = pageSize;
      freeTempSpace(pBt);
      rc = sqlite3PagerSetPagesize(pBt->pPager, &pBt->pageSize,
                                   pageSize-usableSize);
      return rc;
    }
    if( (pBt->db->flags & SQLITE_RecoveryMode)==0 && nPageHeader>nPageFile ){
      rc = SQLITE_CORRUPT_BKPT;
      goto page1_init_failed;
    }
    if( usableSize<480 ){
      goto page1_init_failed;
    }
    pBt->pageSize = pageSize;

  u8 secureDelete;      /* True if secure_delete is enabled */
  u8 initiallyEmpty;    /* Database is empty at start of transaction */
  u8 openFlags;         /* Flags to sqlite3BtreeOpen() */
#ifndef SQLITE_OMIT_AUTOVACUUM
  u8 autoVacuum;        /* True if auto-vacuum is enabled */
  u8 incrVacuum;        /* True if incr-vacuum is enabled */
#endif


  u16 maxLocal;         /* Maximum local payload in non-LEAFDATA tables */
  u16 minLocal;         /* Minimum local payload in non-LEAFDATA tables */
  u16 maxLeaf;          /* Maximum local payload in a LEAFDATA table */
  u16 minLeaf;          /* Minimum local payload in a LEAFDATA table */
  u8 inTransaction;     /* Transaction state */
  u8 doNotUseWAL;       /* If true, do not open write-ahead-log file */
  u32 pageSize;         /* Total number of bytes on a page */
  u32 usableSize;       /* Number of usable bytes on each page */
  int nTransaction;     /* Number of open transactions (read + write) */
  u32 nPage;            /* Number of pages in the database */
  void *pSchema;        /* Pointer to space allocated by sqlite3BtreeSchema() */
  void (*xFreeSchema)(void*);  /* Destructor for BtShared.pSchema */
  sqlite3_mutex *mutex; /* Non-recursive mutex required to access this struct */
................................................................................
/*
** An instance of the following structure is used to hold information
** about a cell.  The parseCellPtr() function fills in this structure
** based on information extract from the raw disk page.
*/
typedef struct CellInfo CellInfo;
struct CellInfo {
  u8 *pCell;     /* Pointer to the start of cell content */
  i64 nKey;      /* The key for INTKEY tables, or number of bytes in key */

  u32 nData;     /* Number of bytes of data */
  u32 nPayload;  /* Total amount of payload */
  u16 nHeader;   /* Size of the cell content header in bytes */
  u16 nLocal;    /* Amount of payload held locally */
  u16 iOverflow; /* Offset to overflow page number.  Zero if no overflow */
  u16 nSize;     /* Size of the cell content on the main b-tree page */
};
................................................................................
  Btree *pBtree;            /* The Btree to which this cursor belongs */
  BtShared *pBt;            /* The BtShared this cursor points to */
  BtCursor *pNext, *pPrev;  /* Forms a linked list of all cursors */
  struct KeyInfo *pKeyInfo; /* Argument passed to comparison function */
  Pgno pgnoRoot;            /* The root page of this tree */
  sqlite3_int64 cachedRowid; /* Next rowid cache.  0 means not valid */
  CellInfo info;            /* A parse of the cell we are pointing at */



  u8 wrFlag;                /* True if writable */
  u8 atLast;                /* Cursor pointing to the last entry */
  u8 validNKey;             /* True if info.nKey is valid */
  u8 eState;                /* One of the CURSOR_XXX constants (see below) */
  void *pKey;      /* Saved key that was cursor's last known position */
  i64 nKey;        /* Size of pKey, or last integer key */
  int skipNext;    /* Prev() is noop if negative. Next() is noop if positive */
#ifndef SQLITE_OMIT_INCRBLOB
  u8 isIncrblobHandle;      /* True if this cursor is an incr. io handle */
  Pgno *aOverflow;          /* Cache of overflow page locations */

#endif
  i16 iPage;                            /* Index of current page in apPage */
  MemPage *apPage[BTCURSOR_MAX_DEPTH];  /* Pages from root to current page */
  u16 aiIdx[BTCURSOR_MAX_DEPTH];        /* Current index in apPage[i] */

};

/*
** Potential values for BtCursor.eState.
**
** CURSOR_VALID:
**   Cursor points to a valid entry. getPayload() etc. may be called.

  u8 secureDelete;      /* True if secure_delete is enabled */
  u8 initiallyEmpty;    /* Database is empty at start of transaction */
  u8 openFlags;         /* Flags to sqlite3BtreeOpen() */
#ifndef SQLITE_OMIT_AUTOVACUUM
  u8 autoVacuum;        /* True if auto-vacuum is enabled */
  u8 incrVacuum;        /* True if incr-vacuum is enabled */
#endif
  u8 inTransaction;     /* Transaction state */
  u8 doNotUseWAL;       /* If true, do not open write-ahead-log file */
  u16 maxLocal;         /* Maximum local payload in non-LEAFDATA tables */
  u16 minLocal;         /* Minimum local payload in non-LEAFDATA tables */
  u16 maxLeaf;          /* Maximum local payload in a LEAFDATA table */
  u16 minLeaf;          /* Minimum local payload in a LEAFDATA table */


  u32 pageSize;         /* Total number of bytes on a page */
  u32 usableSize;       /* Number of usable bytes on each page */
  int nTransaction;     /* Number of open transactions (read + write) */
  u32 nPage;            /* Number of pages in the database */
  void *pSchema;        /* Pointer to space allocated by sqlite3BtreeSchema() */
  void (*xFreeSchema)(void*);  /* Destructor for BtShared.pSchema */
  sqlite3_mutex *mutex; /* Non-recursive mutex required to access this struct */
................................................................................
/*
** An instance of the following structure is used to hold information
** about a cell.  The parseCellPtr() function fills in this structure
** based on information extract from the raw disk page.
*/
typedef struct CellInfo CellInfo;
struct CellInfo {

  i64 nKey;      /* The key for INTKEY tables, or number of bytes in key */
  u8 *pCell;     /* Pointer to the start of cell content */
  u32 nData;     /* Number of bytes of data */
  u32 nPayload;  /* Total amount of payload */
  u16 nHeader;   /* Size of the cell content header in bytes */
  u16 nLocal;    /* Amount of payload held locally */
  u16 iOverflow; /* Offset to overflow page number.  Zero if no overflow */
  u16 nSize;     /* Size of the cell content on the main b-tree page */
};
................................................................................
  Btree *pBtree;            /* The Btree to which this cursor belongs */
  BtShared *pBt;            /* The BtShared this cursor points to */
  BtCursor *pNext, *pPrev;  /* Forms a linked list of all cursors */
  struct KeyInfo *pKeyInfo; /* Argument passed to comparison function */
  Pgno pgnoRoot;            /* The root page of this tree */
  sqlite3_int64 cachedRowid; /* Next rowid cache.  0 means not valid */
  CellInfo info;            /* A parse of the cell we are pointing at */
  i64 nKey;        /* Size of pKey, or last integer key */
  void *pKey;      /* Saved key that was cursor's last known position */
  int skipNext;    /* Prev() is noop if negative. Next() is noop if positive */
  u8 wrFlag;                /* True if writable */
  u8 atLast;                /* Cursor pointing to the last entry */
  u8 validNKey;             /* True if info.nKey is valid */
  u8 eState;                /* One of the CURSOR_XXX constants (see below) */



#ifndef SQLITE_OMIT_INCRBLOB

  Pgno *aOverflow;          /* Cache of overflow page locations */
  u8 isIncrblobHandle;      /* True if this cursor is an incr. io handle */
#endif
  i16 iPage;                            /* Index of current page in apPage */

  u16 aiIdx[BTCURSOR_MAX_DEPTH];        /* Current index in apPage[i] */
  MemPage *apPage[BTCURSOR_MAX_DEPTH];  /* Pages from root to current page */
};

/*
** Potential values for BtCursor.eState.
**
** CURSOR_VALID:
**   Cursor points to a valid entry. getPayload() etc. may be called.

  "OMIT_AUTOINCREMENT",
#endif
#ifdef SQLITE_OMIT_AUTOINIT
  "OMIT_AUTOINIT",
#endif
#ifdef SQLITE_OMIT_AUTOMATIC_INDEX
  "OMIT_AUTOMATIC_INDEX",



#endif
#ifdef SQLITE_OMIT_AUTOVACUUM
  "OMIT_AUTOVACUUM",
#endif
#ifdef SQLITE_OMIT_BETWEEN_OPTIMIZATION
  "OMIT_BETWEEN_OPTIMIZATION",
#endif

  "OMIT_AUTOINCREMENT",
#endif
#ifdef SQLITE_OMIT_AUTOINIT
  "OMIT_AUTOINIT",
#endif
#ifdef SQLITE_OMIT_AUTOMATIC_INDEX
  "OMIT_AUTOMATIC_INDEX",
#endif
#ifdef SQLITE_OMIT_AUTORESET
  "OMIT_AUTORESET",
#endif
#ifdef SQLITE_OMIT_AUTOVACUUM
  "OMIT_AUTOVACUUM",
#endif
#ifdef SQLITE_OMIT_BETWEEN_OPTIMIZATION
  "OMIT_BETWEEN_OPTIMIZATION",
#endif

  pPager->changeCountDone = pPager->tempFile;

  if( rc==SQLITE_OK ){
    zMaster = pPager->pTmpSpace;
    rc = readMasterJournal(pPager->jfd, zMaster, pPager->pVfs->mxPathname+1);
    testcase( rc!=SQLITE_OK );
  }
  if( rc==SQLITE_OK && !pPager->noSync 
   && (pPager->eState>=PAGER_WRITER_DBMOD || pPager->eState==PAGER_OPEN)
  ){
    rc = sqlite3OsSync(pPager->fd, pPager->syncFlags);
  }
  if( rc==SQLITE_OK ){
    rc = pager_end_transaction(pPager, zMaster[0]!='\0');
    testcase( rc!=SQLITE_OK );
  }
  if( rc==SQLITE_OK && zMaster[0] && res ){
    /* If there was a master journal and this routine will return success,
................................................................................
    rc = pagerUndoCallback((void *)pPager, pList->pgno);
    pList = pNext;
  }

  return rc;
}
























/*
** This function is a wrapper around sqlite3WalFrames(). As well as logging
** the contents of the list of pages headed by pList (connected by pDirty),
** this function notifies any active backup processes that the pages have
** changed. 



*/ 
static int pagerWalFrames(
  Pager *pPager,                  /* Pager object */
  PgHdr *pList,                   /* List of frames to log */
  Pgno nTruncate,                 /* Database size after this commit */
  int isCommit,                   /* True if this is a commit */
  int syncFlags                   /* Flags to pass to OsSync() (or 0) */
){
  int rc;                         /* Return code */




  assert( pPager->pWal );








  rc = sqlite3WalFrames(pPager->pWal, 
      pPager->pageSize, pList, nTruncate, isCommit, syncFlags
  );
  if( rc==SQLITE_OK && pPager->pBackup ){
    PgHdr *p;
    for(p=pList; p; p=p->pDirty){
      sqlite3BackupUpdate(pPager->pBackup, p->pgno, (u8 *)p->pData);
    }
  }

#ifdef SQLITE_CHECK_PAGES
  {
    PgHdr *p;
    for(p=pList; p; p=p->pDirty) pager_set_pagehash(p);
  }
#endif

  return rc;
}

/*
................................................................................
    ** set (set by sqlite3PagerDontWrite()).
    */
    if( pgno<=pPager->dbSize && 0==(pList->flags&PGHDR_DONT_WRITE) ){
      i64 offset = (pgno-1)*(i64)pPager->pageSize;   /* Offset to write */
      char *pData;                                   /* Data to write */    

      assert( (pList->flags&PGHDR_NEED_SYNC)==0 );


      /* Encode the database */
      CODEC2(pPager, pList->pData, pgno, 6, return SQLITE_NOMEM, pData);

      /* Write out the page data. */
      rc = sqlite3OsWrite(pPager->fd, pData, pPager->pageSize, offset);

................................................................................
    pager_set_pagehash(pPg);
  }
}

/*
** This routine is called to increment the value of the database file 
** change-counter, stored as a 4-byte big-endian integer starting at 
** byte offset 24 of the pager file.






**
** If the isDirectMode flag is zero, then this is done by calling 
** sqlite3PagerWrite() on page 1, then modifying the contents of the
** page data. In this case the file will be updated when the current
** transaction is committed.
**
** The isDirectMode flag may only be non-zero if the library was compiled
................................................................................
  UNUSED_PARAMETER(isDirectMode);
#else
# define DIRECT_MODE isDirectMode
#endif

  if( !pPager->changeCountDone && pPager->dbSize>0 ){
    PgHdr *pPgHdr;                /* Reference to page 1 */
    u32 change_counter;           /* Initial value of change-counter field */

    assert( !pPager->tempFile && isOpen(pPager->fd) );

    /* Open page 1 of the file for writing. */
    rc = sqlite3PagerGet(pPager, 1, &pPgHdr);
    assert( pPgHdr==0 || rc==SQLITE_OK );

................................................................................
    ** above is always successful - hence the ALWAYS on rc==SQLITE_OK.
    */
    if( !DIRECT_MODE && ALWAYS(rc==SQLITE_OK) ){
      rc = sqlite3PagerWrite(pPgHdr);
    }

    if( rc==SQLITE_OK ){
      /* Increment the value just read and write it back to byte 24. */
      change_counter = sqlite3Get4byte((u8*)pPager->dbFileVers);
      change_counter++;
      put32bits(((char*)pPgHdr->pData)+24, change_counter);

      /* Also store the SQLite version number in bytes 96..99 and in
      ** bytes 92..95 store the change counter for which the version number
      ** is valid. */
      put32bits(((char*)pPgHdr->pData)+92, change_counter);
      put32bits(((char*)pPgHdr->pData)+96, SQLITE_VERSION_NUMBER);

      /* If running in direct mode, write the contents of page 1 to the file. */
      if( DIRECT_MODE ){
        const void *zBuf;
        assert( pPager->dbFileSize>0 );
        CODEC2(pPager, pPgHdr->pData, 1, 6, rc=SQLITE_NOMEM, zBuf);
        if( rc==SQLITE_OK ){
................................................................................
  int rc;                              /* Return code */
  assert( !MEMDB );
  if( pPager->noSync ){
    rc = SQLITE_OK;
  }else{
    rc = sqlite3OsSync(pPager->fd, pPager->syncFlags);
  }



  return rc;
}

/*
** This function may only be called while a write-transaction is active in
** rollback. If the connection is in WAL mode, this call is a no-op. 
** Otherwise, if the connection does not already have an EXCLUSIVE lock on 
................................................................................
        Pgno nNew = pPager->dbSize - (pPager->dbSize==PAGER_MJ_PGNO(pPager));
        assert( pPager->eState==PAGER_WRITER_DBMOD );
        rc = pager_truncate(pPager, nNew);
        if( rc!=SQLITE_OK ) goto commit_phase_one_exit;
      }
  
      /* Finally, sync the database file. */
      if( !pPager->noSync && !noSync ){
        rc = sqlite3OsSync(pPager->fd, pPager->syncFlags);
      }
      IOTRACE(("DBSYNC %p\n", pPager))
    }
  }

commit_phase_one_exit:
  if( rc==SQLITE_OK && !pagerUseWal(pPager) ){
................................................................................

  if( pagerUseWal(pPager) ){
    int rc2;
    rc = sqlite3PagerSavepoint(pPager, SAVEPOINT_ROLLBACK, -1);
    rc2 = pager_end_transaction(pPager, pPager->setMaster);
    if( rc==SQLITE_OK ) rc = rc2;
  }else if( !isOpen(pPager->jfd) || pPager->eState==PAGER_WRITER_LOCKED ){

    rc = pager_end_transaction(pPager, 0);









  }else{
    rc = pager_playback(pPager, 0);
  }

  assert( pPager->eState==PAGER_READER || rc!=SQLITE_OK );
  assert( rc==SQLITE_OK || rc==SQLITE_FULL || (rc&0xFF)==SQLITE_IOERR );

  pPager->changeCountDone = pPager->tempFile;

  if( rc==SQLITE_OK ){
    zMaster = pPager->pTmpSpace;
    rc = readMasterJournal(pPager->jfd, zMaster, pPager->pVfs->mxPathname+1);
    testcase( rc!=SQLITE_OK );
  }
  if( rc==SQLITE_OK
   && (pPager->eState>=PAGER_WRITER_DBMOD || pPager->eState==PAGER_OPEN)
  ){
    rc = sqlite3PagerSync(pPager);
  }
  if( rc==SQLITE_OK ){
    rc = pager_end_transaction(pPager, zMaster[0]!='\0');
    testcase( rc!=SQLITE_OK );
  }
  if( rc==SQLITE_OK && zMaster[0] && res ){
    /* If there was a master journal and this routine will return success,
................................................................................
    rc = pagerUndoCallback((void *)pPager, pList->pgno);
    pList = pNext;
  }

  return rc;
}


/*
** Update the value of the change-counter at offsets 24 and 92 in
** the header and the sqlite version number at offset 96.
**
** This is an unconditional update.  See also the pager_incr_changecounter()
** routine which only updates the change-counter if the update is actually
** needed, as determined by the pPager->changeCountDone state variable.
*/
static void pager_write_changecounter(PgHdr *pPg){
  u32 change_counter;

  /* Increment the value just read and write it back to byte 24. */
  change_counter = sqlite3Get4byte((u8*)pPg->pPager->dbFileVers)+1;
  put32bits(((char*)pPg->pData)+24, change_counter);

  /* Also store the SQLite version number in bytes 96..99 and in
  ** bytes 92..95 store the change counter for which the version number
  ** is valid. */
  put32bits(((char*)pPg->pData)+92, change_counter);
  put32bits(((char*)pPg->pData)+96, SQLITE_VERSION_NUMBER);
}

/*
** This function is a wrapper around sqlite3WalFrames(). As well as logging
** the contents of the list of pages headed by pList (connected by pDirty),
** this function notifies any active backup processes that the pages have
** changed.
**
** The list of pages passed into this routine is always sorted by page number.
** Hence, if page 1 appears anywhere on the list, it will be the first page.
*/ 
static int pagerWalFrames(
  Pager *pPager,                  /* Pager object */
  PgHdr *pList,                   /* List of frames to log */
  Pgno nTruncate,                 /* Database size after this commit */
  int isCommit,                   /* True if this is a commit */
  int syncFlags                   /* Flags to pass to OsSync() (or 0) */
){
  int rc;                         /* Return code */
#if defined(SQLITE_DEBUG) || defined(SQLITE_CHECK_PAGES)
  PgHdr *p;                       /* For looping over pages */
#endif

  assert( pPager->pWal );
#ifdef SQLITE_DEBUG
  /* Verify that the page list is in accending order */
  for(p=pList; p && p->pDirty; p=p->pDirty){
    assert( p->pgno < p->pDirty->pgno );
  }
#endif

  if( pList->pgno==1 ) pager_write_changecounter(pList);
  rc = sqlite3WalFrames(pPager->pWal, 
      pPager->pageSize, pList, nTruncate, isCommit, syncFlags
  );
  if( rc==SQLITE_OK && pPager->pBackup ){
    PgHdr *p;
    for(p=pList; p; p=p->pDirty){
      sqlite3BackupUpdate(pPager->pBackup, p->pgno, (u8 *)p->pData);
    }
  }

#ifdef SQLITE_CHECK_PAGES
  for(p=pList; p; p=p->pDirty){
    pager_set_pagehash(p);

  }
#endif

  return rc;
}

/*
................................................................................
    ** set (set by sqlite3PagerDontWrite()).
    */
    if( pgno<=pPager->dbSize && 0==(pList->flags&PGHDR_DONT_WRITE) ){
      i64 offset = (pgno-1)*(i64)pPager->pageSize;   /* Offset to write */
      char *pData;                                   /* Data to write */    

      assert( (pList->flags&PGHDR_NEED_SYNC)==0 );
      if( pList->pgno==1 ) pager_write_changecounter(pList);

      /* Encode the database */
      CODEC2(pPager, pList->pData, pgno, 6, return SQLITE_NOMEM, pData);

      /* Write out the page data. */
      rc = sqlite3OsWrite(pPager->fd, pData, pPager->pageSize, offset);

................................................................................
    pager_set_pagehash(pPg);
  }
}

/*
** This routine is called to increment the value of the database file 
** change-counter, stored as a 4-byte big-endian integer starting at 
** byte offset 24 of the pager file.  The secondary change counter at
** 92 is also updated, as is the SQLite version number at offset 96.
**
** But this only happens if the pPager->changeCountDone flag is false.
** To avoid excess churning of page 1, the update only happens once.
** See also the pager_write_changecounter() routine that does an 
** unconditional update of the change counters.
**
** If the isDirectMode flag is zero, then this is done by calling 
** sqlite3PagerWrite() on page 1, then modifying the contents of the
** page data. In this case the file will be updated when the current
** transaction is committed.
**
** The isDirectMode flag may only be non-zero if the library was compiled
................................................................................
  UNUSED_PARAMETER(isDirectMode);
#else
# define DIRECT_MODE isDirectMode
#endif

  if( !pPager->changeCountDone && pPager->dbSize>0 ){
    PgHdr *pPgHdr;                /* Reference to page 1 */


    assert( !pPager->tempFile && isOpen(pPager->fd) );

    /* Open page 1 of the file for writing. */
    rc = sqlite3PagerGet(pPager, 1, &pPgHdr);
    assert( pPgHdr==0 || rc==SQLITE_OK );

................................................................................
    ** above is always successful - hence the ALWAYS on rc==SQLITE_OK.
    */
    if( !DIRECT_MODE && ALWAYS(rc==SQLITE_OK) ){
      rc = sqlite3PagerWrite(pPgHdr);
    }

    if( rc==SQLITE_OK ){
      /* Actually do the update of the change counter */
      pager_write_changecounter(pPgHdr);









      /* If running in direct mode, write the contents of page 1 to the file. */
      if( DIRECT_MODE ){
        const void *zBuf;
        assert( pPager->dbFileSize>0 );
        CODEC2(pPager, pPgHdr->pData, 1, 6, rc=SQLITE_NOMEM, zBuf);
        if( rc==SQLITE_OK ){
................................................................................
  int rc;                              /* Return code */
  assert( !MEMDB );
  if( pPager->noSync ){
    rc = SQLITE_OK;
  }else{
    rc = sqlite3OsSync(pPager->fd, pPager->syncFlags);
  }
  if( isOpen(pPager->fd) ){
    sqlite3OsFileControl(pPager->fd, SQLITE_FCNTL_SYNC, (void *)&rc);
  }
  return rc;
}

/*
** This function may only be called while a write-transaction is active in
** rollback. If the connection is in WAL mode, this call is a no-op. 
** Otherwise, if the connection does not already have an EXCLUSIVE lock on 
................................................................................
        Pgno nNew = pPager->dbSize - (pPager->dbSize==PAGER_MJ_PGNO(pPager));
        assert( pPager->eState==PAGER_WRITER_DBMOD );
        rc = pager_truncate(pPager, nNew);
        if( rc!=SQLITE_OK ) goto commit_phase_one_exit;
      }
  
      /* Finally, sync the database file. */
      if( !noSync ){
        rc = sqlite3PagerSync(pPager);
      }
      IOTRACE(("DBSYNC %p\n", pPager))
    }
  }

commit_phase_one_exit:
  if( rc==SQLITE_OK && !pagerUseWal(pPager) ){
................................................................................

  if( pagerUseWal(pPager) ){
    int rc2;
    rc = sqlite3PagerSavepoint(pPager, SAVEPOINT_ROLLBACK, -1);
    rc2 = pager_end_transaction(pPager, pPager->setMaster);
    if( rc==SQLITE_OK ) rc = rc2;
  }else if( !isOpen(pPager->jfd) || pPager->eState==PAGER_WRITER_LOCKED ){
    int eState = pPager->eState;
    rc = pager_end_transaction(pPager, 0);
    if( !MEMDB && eState>PAGER_WRITER_LOCKED ){
      /* This can happen using journal_mode=off. Move the pager to the error 
      ** state to indicate that the contents of the cache may not be trusted.
      ** Any active readers will get SQLITE_ABORT.
      */
      pPager->errCode = SQLITE_ABORT;
      pPager->eState = PAGER_ERROR;
      return rc;
    }
  }else{
    rc = pager_playback(pPager, 0);
  }

  assert( pPager->eState==PAGER_READER || rc!=SQLITE_OK );
  assert( rc==SQLITE_OK || rc==SQLITE_FULL || (rc&0xFF)==SQLITE_IOERR );

*/

#include "sqliteInt.h"

typedef struct PCache1 PCache1;
typedef struct PgHdr1 PgHdr1;
typedef struct PgFreeslot PgFreeslot;
































/* Each page cache is an instance of the following object.  Every
** open database file (including each in-memory database and each
** temporary or transient database) has a single page cache which
** is an instance of this object.
**
** Pointers to structures of this type are cast and returned as 
** opaque sqlite3_pcache* handles.
*/
struct PCache1 {
  /* Cache configuration parameters. Page size (szPage) and the purgeable
  ** flag (bPurgeable) are set when the cache is created. nMax may be 
  ** modified at any time by a call to the pcache1CacheSize() method.
  ** The global mutex must be held when accessing nMax.
  */

  int szPage;                         /* Size of allocated pages in bytes */
  int bPurgeable;                     /* True if cache is purgeable */
  unsigned int nMin;                  /* Minimum number of pages reserved */
  unsigned int nMax;                  /* Configured "cache_size" value */

  /* Hash table of all pages. The following variables may only be accessed
  ** when the accessor is holding the global mutex (see pcache1EnterMutex() 
  ** and pcache1LeaveMutex()).
  */
  unsigned int nRecyclable;           /* Number of pages in the LRU list */
  unsigned int nPage;                 /* Total number of pages in apHash */
  unsigned int nHash;                 /* Number of slots in apHash[] */
  PgHdr1 **apHash;                    /* Hash table for fast lookup by key */

  unsigned int iMaxKey;               /* Largest key seen since xTruncate() */
................................................................................
  PgFreeslot *pNext;  /* Next free slot */
};

/*
** Global data used by this cache.
*/
static SQLITE_WSD struct PCacheGlobal {
  sqlite3_mutex *mutex;               /* static mutex MUTEX_STATIC_LRU */

  int nMaxPage;                       /* Sum of nMaxPage for purgeable caches */
  int nMinPage;                       /* Sum of nMinPage for purgeable caches */
  int nCurrentPage;                   /* Number of purgeable pages allocated */
  PgHdr1 *pLruHead, *pLruTail;        /* LRU list of unpinned pages */

  /* Variables related to SQLITE_CONFIG_PAGECACHE settings. */
  int szSlot;                         /* Size of each free slot */
  int nSlot;                          /* The number of pcache slots */
  int nFreeSlot;                      /* Number of unused pcache slots */
  int nReserve;                       /* Try to keep nFreeSlot above this */
  void *pStart, *pEnd;                /* Bounds of pagecache malloc range */
  PgFreeslot *pFree;                  /* Free page blocks */
  int isInit;                         /* True if initialized */






} pcache1_g;

/*
** All code in this file should access the global structure above via the
** alias "pcache1". This ensures that the WSD emulation is used when
** compiling for systems that do not support real WSD.
*/
................................................................................
**
**   assert( PGHDR1_TO_PAGE(PAGE_TO_PGHDR1(pCache, X))==X );
*/
#define PGHDR1_TO_PAGE(p)    (void*)(((char*)p) - p->pCache->szPage)
#define PAGE_TO_PGHDR1(c, p) (PgHdr1*)(((char*)p) + c->szPage)

/*
** Macros to enter and leave the global LRU mutex.
*/
#define pcache1EnterMutex() sqlite3_mutex_enter(pcache1.mutex)
#define pcache1LeaveMutex() sqlite3_mutex_leave(pcache1.mutex)

/******************************************************************************/
/******** Page Allocation/SQLITE_CONFIG_PCACHE Related Functions **************/

/*
** This function is called during initialization if a static buffer is 
** supplied to use for the page-cache by passing the SQLITE_CONFIG_PAGECACHE
** verb to sqlite3_config(). Parameter pBuf points to an allocation large
** enough to contain 'n' buffers of 'sz' bytes each.



*/
void sqlite3PCacheBufferSetup(void *pBuf, int sz, int n){
  if( pcache1.isInit ){
    PgFreeslot *p;
    sz = ROUNDDOWN8(sz);
    pcache1.szSlot = sz;
    pcache1.nSlot = pcache1.nFreeSlot = n;
    pcache1.nReserve = n>90 ? 10 : (n/10 + 1);
    pcache1.pStart = pBuf;
    pcache1.pFree = 0;

    while( n-- ){
      p = (PgFreeslot*)pBuf;
      p->pNext = pcache1.pFree;
      pcache1.pFree = p;
      pBuf = (void*)&((char*)pBuf)[sz];
    }
    pcache1.pEnd = pBuf;
................................................................................
}

/*
** Malloc function used within this file to allocate space from the buffer
** configured using sqlite3_config(SQLITE_CONFIG_PAGECACHE) option. If no 
** such buffer exists or there is no space left in it, this function falls 
** back to sqlite3Malloc().



*/
static void *pcache1Alloc(int nByte){
  void *p;
  assert( sqlite3_mutex_held(pcache1.mutex) );
  sqlite3StatusSet(SQLITE_STATUS_PAGECACHE_SIZE, nByte);
  if( nByte<=pcache1.szSlot && pcache1.pFree ){
    assert( pcache1.isInit );

    p = (PgHdr1 *)pcache1.pFree;

    pcache1.pFree = pcache1.pFree->pNext;
    pcache1.nFreeSlot--;

    assert( pcache1.nFreeSlot>=0 );
    sqlite3StatusAdd(SQLITE_STATUS_PAGECACHE_USED, 1);
  }else{

    /* Allocate a new buffer using sqlite3Malloc. Before doing so, exit the
    ** global pcache mutex and unlock the pager-cache object pCache. This is 
    ** so that if the attempt to allocate a new buffer causes the the 
    ** configured soft-heap-limit to be breached, it will be possible to
    ** reclaim memory from this pager-cache.




    */
    pcache1LeaveMutex();
    p = sqlite3Malloc(nByte);
    pcache1EnterMutex();
    if( p ){
      int sz = sqlite3MallocSize(p);
      sqlite3StatusAdd(SQLITE_STATUS_PAGECACHE_OVERFLOW, sz);
    }
    sqlite3MemdebugSetType(p, MEMTYPE_PCACHE);
  }
  return p;
}

/*
** Free an allocated buffer obtained from pcache1Alloc().
*/
static void pcache1Free(void *p){
  assert( sqlite3_mutex_held(pcache1.mutex) );
  if( p==0 ) return;
  if( p>=pcache1.pStart && p<pcache1.pEnd ){
    PgFreeslot *pSlot;

    sqlite3StatusAdd(SQLITE_STATUS_PAGECACHE_USED, -1);
    pSlot = (PgFreeslot*)p;
    pSlot->pNext = pcache1.pFree;
    pcache1.pFree = pSlot;
    pcache1.nFreeSlot++;

    assert( pcache1.nFreeSlot<=pcache1.nSlot );

  }else{
    int iSize;
    assert( sqlite3MemdebugHasType(p, MEMTYPE_PCACHE) );
    sqlite3MemdebugSetType(p, MEMTYPE_HEAP);
    iSize = sqlite3MallocSize(p);
    sqlite3StatusAdd(SQLITE_STATUS_PAGECACHE_OVERFLOW, -iSize);
    sqlite3_free(p);
................................................................................
}

#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
/*
** Return the size of a pcache allocation
*/
static int pcache1MemSize(void *p){
  assert( sqlite3_mutex_held(pcache1.mutex) );
  if( p>=pcache1.pStart && p<pcache1.pEnd ){
    return pcache1.szSlot;
  }else{
    int iSize;
    assert( sqlite3MemdebugHasType(p, MEMTYPE_PCACHE) );
    sqlite3MemdebugSetType(p, MEMTYPE_HEAP);
    iSize = sqlite3MallocSize(p);
................................................................................
static PgHdr1 *pcache1AllocPage(PCache1 *pCache){
  int nByte = sizeof(PgHdr1) + pCache->szPage;
  void *pPg = pcache1Alloc(nByte);
  PgHdr1 *p;
  if( pPg ){
    p = PAGE_TO_PGHDR1(pCache, pPg);
    if( pCache->bPurgeable ){
      pcache1.nCurrentPage++;
    }
  }else{
    p = 0;
  }
  return p;
}

................................................................................
**
** The pointer is allowed to be NULL, which is prudent.  But it turns out
** that the current implementation happens to never call this routine
** with a NULL pointer, so we mark the NULL test with ALWAYS().
*/
static void pcache1FreePage(PgHdr1 *p){
  if( ALWAYS(p) ){

    if( p->pCache->bPurgeable ){
      pcache1.nCurrentPage--;
    }
    pcache1Free(PGHDR1_TO_PAGE(p));
  }
}

/*
** Malloc function used by SQLite to obtain space from the buffer configured
** using sqlite3_config(SQLITE_CONFIG_PAGECACHE) option. If no such buffer
** exists, this function falls back to sqlite3Malloc().
*/
void *sqlite3PageMalloc(int sz){
  void *p;
  pcache1EnterMutex();
  p = pcache1Alloc(sz);
  pcache1LeaveMutex();
  return p;
}

/*
** Free an allocated buffer obtained from sqlite3PageMalloc().
*/
void sqlite3PageFree(void *p){
  pcache1EnterMutex();
  pcache1Free(p);
  pcache1LeaveMutex();
}


/*
** Return true if it desirable to avoid allocating a new page cache
** entry.
**
................................................................................
**
** Or, the heap is used for all page cache memory put the heap is
** under memory pressure, then again it is desirable to avoid
** allocating a new page cache entry in order to avoid stressing
** the heap even further.
*/
static int pcache1UnderMemoryPressure(PCache1 *pCache){
  assert( sqlite3_mutex_held(pcache1.mutex) );
  if( pcache1.nSlot && pCache->szPage<=pcache1.szSlot ){
    return pcache1.nFreeSlot<pcache1.nReserve;
  }else{
    return sqlite3HeapNearlyFull();
  }
}

/******************************************************************************/
/******** General Implementation Functions ************************************/

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

  assert( sqlite3_mutex_held(pcache1.mutex) );

  nNew = p->nHash*2;
  if( nNew<256 ){
    nNew = 256;
  }

  pcache1LeaveMutex();
  if( p->nHash ){ sqlite3BeginBenignMalloc(); }
  apNew = (PgHdr1 **)sqlite3_malloc(sizeof(PgHdr1 *)*nNew);
  if( p->nHash ){ sqlite3EndBenignMalloc(); }
  pcache1EnterMutex();
  if( apNew ){
    memset(apNew, 0, sizeof(PgHdr1 *)*nNew);
    for(i=0; i<p->nHash; i++){
      PgHdr1 *pPage;
      PgHdr1 *pNext = p->apHash[i];
      while( (pPage = pNext)!=0 ){
        unsigned int h = pPage->iKey % nNew;
................................................................................
  }

  return (p->apHash ? SQLITE_OK : SQLITE_NOMEM);
}

/*
** This function is used internally to remove the page pPage from the 
** global LRU list, if is part of it. If pPage is not part of the global
** LRU list, then this function is a no-op.
**
** The global mutex must be held when this function is called.


*/
static void pcache1PinPage(PgHdr1 *pPage){






  assert( sqlite3_mutex_held(pcache1.mutex) );
  if( pPage && (pPage->pLruNext || pPage==pcache1.pLruTail) ){
    if( pPage->pLruPrev ){
      pPage->pLruPrev->pLruNext = pPage->pLruNext;
    }
    if( pPage->pLruNext ){
      pPage->pLruNext->pLruPrev = pPage->pLruPrev;
    }
    if( pcache1.pLruHead==pPage ){
      pcache1.pLruHead = pPage->pLruNext;
    }
    if( pcache1.pLruTail==pPage ){
      pcache1.pLruTail = pPage->pLruPrev;
    }
    pPage->pLruNext = 0;
    pPage->pLruPrev = 0;
    pPage->pCache->nRecyclable--;
  }
}


/*
** Remove the page supplied as an argument from the hash table 
** (PCache1.apHash structure) that it is currently stored in.
**
** The global mutex must be held when this function is called.
*/
static void pcache1RemoveFromHash(PgHdr1 *pPage){
  unsigned int h;
  PCache1 *pCache = pPage->pCache;
  PgHdr1 **pp;


  h = pPage->iKey % pCache->nHash;
  for(pp=&pCache->apHash[h]; (*pp)!=pPage; pp=&(*pp)->pNext);
  *pp = (*pp)->pNext;

  pCache->nPage--;
}

/*
** If there are currently more than pcache.nMaxPage pages allocated, try
** to recycle pages to reduce the number allocated to pcache.nMaxPage.
*/
static void pcache1EnforceMaxPage(void){
  assert( sqlite3_mutex_held(pcache1.mutex) );
  while( pcache1.nCurrentPage>pcache1.nMaxPage && pcache1.pLruTail ){
    PgHdr1 *p = pcache1.pLruTail;

    pcache1PinPage(p);
    pcache1RemoveFromHash(p);
    pcache1FreePage(p);
  }
}

/*
** Discard all pages from cache pCache with a page number (key value) 
** greater than or equal to iLimit. Any pinned pages that meet this 
** criteria are unpinned before they are discarded.
**
** The global mutex must be held when this function is called.
*/
static void pcache1TruncateUnsafe(
  PCache1 *pCache, 
  unsigned int iLimit 
){
  TESTONLY( unsigned int nPage = 0; )      /* Used to assert pCache->nPage is correct */
  unsigned int h;
  assert( sqlite3_mutex_held(pcache1.mutex) );
  for(h=0; h<pCache->nHash; h++){
    PgHdr1 **pp = &pCache->apHash[h]; 
    PgHdr1 *pPage;
    while( (pPage = *pp)!=0 ){
      if( pPage->iKey>=iLimit ){
        pCache->nPage--;
        *pp = pPage->pNext;
................................................................................
** Implementation of the sqlite3_pcache.xInit method.
*/
static int pcache1Init(void *NotUsed){
  UNUSED_PARAMETER(NotUsed);
  assert( pcache1.isInit==0 );
  memset(&pcache1, 0, sizeof(pcache1));
  if( sqlite3GlobalConfig.bCoreMutex ){

    pcache1.mutex = sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_LRU);
  }
  pcache1.isInit = 1;
  return SQLITE_OK;
}

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

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






















  pCache = (PCache1 *)sqlite3_malloc(sizeof(PCache1));
  if( pCache ){
    memset(pCache, 0, sizeof(PCache1));






    pCache->szPage = szPage;
    pCache->bPurgeable = (bPurgeable ? 1 : 0);
    if( bPurgeable ){
      pCache->nMin = 10;
      pcache1EnterMutex();
      pcache1.nMinPage += pCache->nMin;
      pcache1LeaveMutex();
    }
  }
  return (sqlite3_pcache *)pCache;
}

/*
** Implementation of the sqlite3_pcache.xCachesize method. 
**
** Configure the cache_size limit for a cache.
*/
static void pcache1Cachesize(sqlite3_pcache *p, int nMax){
  PCache1 *pCache = (PCache1 *)p;
  if( pCache->bPurgeable ){

    pcache1EnterMutex();
    pcache1.nMaxPage += (nMax - pCache->nMax);
    pCache->nMax = nMax;
    pcache1EnforceMaxPage();
    pcache1LeaveMutex();
  }
}

/*
** Implementation of the sqlite3_pcache.xPagecount method. 
*/
static int pcache1Pagecount(sqlite3_pcache *p){
  int n;

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

/*
** Implementation of the sqlite3_pcache.xFetch method. 
**
** Fetch a page by key value.
................................................................................
**      proceed to step 5. 
**
**   5. Otherwise, allocate and return a new page buffer.
*/
static void *pcache1Fetch(sqlite3_pcache *p, unsigned int iKey, int createFlag){
  unsigned int nPinned;
  PCache1 *pCache = (PCache1 *)p;

  PgHdr1 *pPage = 0;

  assert( pCache->bPurgeable || createFlag!=1 );
  pcache1EnterMutex();
  if( createFlag==1 ) sqlite3BeginBenignMalloc();

  /* Search the hash table for an existing entry. */
  if( pCache->nHash>0 ){
    unsigned int h = iKey % pCache->nHash;
    for(pPage=pCache->apHash[h]; pPage&&pPage->iKey!=iKey; pPage=pPage->pNext);
  }
................................................................................
    pcache1PinPage(pPage);
    goto fetch_out;
  }

  /* Step 3 of header comment. */
  nPinned = pCache->nPage - pCache->nRecyclable;
  if( createFlag==1 && (
        nPinned>=(pcache1.nMaxPage+pCache->nMin-pcache1.nMinPage)
     || nPinned>=(pCache->nMax * 9 / 10)
     || pcache1UnderMemoryPressure(pCache)
  )){
    goto fetch_out;
  }

  if( pCache->nPage>=pCache->nHash && pcache1ResizeHash(pCache) ){
    goto fetch_out;
  }

  /* Step 4. Try to recycle a page buffer if appropriate. */
  if( pCache->bPurgeable && pcache1.pLruTail && (
         (pCache->nPage+1>=pCache->nMax)
      || pcache1.nCurrentPage>=pcache1.nMaxPage
      || pcache1UnderMemoryPressure(pCache)
  )){
    pPage = pcache1.pLruTail;
    pcache1RemoveFromHash(pPage);
    pcache1PinPage(pPage);
    if( pPage->pCache->szPage!=pCache->szPage ){
      pcache1FreePage(pPage);
      pPage = 0;
    }else{

      pcache1.nCurrentPage -= (pPage->pCache->bPurgeable - pCache->bPurgeable);
    }
  }

  /* Step 5. If a usable page buffer has still not been found, 
  ** attempt to allocate a new one. 
  */
  if( !pPage ){

    pPage = pcache1AllocPage(pCache);

  }

  if( pPage ){
    unsigned int h = iKey % pCache->nHash;
    pCache->nPage++;
    pPage->iKey = iKey;
    pPage->pNext = pCache->apHash[h];
................................................................................
  }

fetch_out:
  if( pPage && iKey>pCache->iMaxKey ){
    pCache->iMaxKey = iKey;
  }
  if( createFlag==1 ) sqlite3EndBenignMalloc();
  pcache1LeaveMutex();
  return (pPage ? PGHDR1_TO_PAGE(pPage) : 0);
}


/*
** Implementation of the sqlite3_pcache.xUnpin method.
**
** Mark a page as unpinned (eligible for asynchronous recycling).
*/
static void pcache1Unpin(sqlite3_pcache *p, void *pPg, int reuseUnlikely){
  PCache1 *pCache = (PCache1 *)p;
  PgHdr1 *pPage = PAGE_TO_PGHDR1(pCache, pPg);

 
  assert( pPage->pCache==pCache );
  pcache1EnterMutex();

  /* It is an error to call this function if the page is already 
  ** part of the global LRU list.
  */
  assert( pPage->pLruPrev==0 && pPage->pLruNext==0 );
  assert( pcache1.pLruHead!=pPage && pcache1.pLruTail!=pPage );


  if( reuseUnlikely || pcache1.nCurrentPage>pcache1.nMaxPage ){
    pcache1RemoveFromHash(pPage);
    pcache1FreePage(pPage);
  }else{
    /* Add the page to the global LRU list. Normally, the page is added to
    ** the head of the list (last page to be recycled). However, if the 
    ** reuseUnlikely flag passed to this function is true, the page is added
    ** to the tail of the list (first page to be recycled).
    */
    if( pcache1.pLruHead ){
      pcache1.pLruHead->pLruPrev = pPage;
      pPage->pLruNext = pcache1.pLruHead;
      pcache1.pLruHead = pPage;
    }else{
      pcache1.pLruTail = pPage;
      pcache1.pLruHead = pPage;
    }
    pCache->nRecyclable++;
  }

  pcache1LeaveMutex();
}

/*
** Implementation of the sqlite3_pcache.xRekey method. 
*/
static void pcache1Rekey(
  sqlite3_pcache *p,
................................................................................
  PCache1 *pCache = (PCache1 *)p;
  PgHdr1 *pPage = PAGE_TO_PGHDR1(pCache, pPg);
  PgHdr1 **pp;
  unsigned int h; 
  assert( pPage->iKey==iOld );
  assert( pPage->pCache==pCache );

  pcache1EnterMutex();

  h = iOld%pCache->nHash;
  pp = &pCache->apHash[h];
  while( (*pp)!=pPage ){
    pp = &(*pp)->pNext;
  }
  *pp = pPage->pNext;
................................................................................
  pPage->iKey = iNew;
  pPage->pNext = pCache->apHash[h];
  pCache->apHash[h] = pPage;
  if( iNew>pCache->iMaxKey ){
    pCache->iMaxKey = iNew;
  }

  pcache1LeaveMutex();
}

/*
** Implementation of the sqlite3_pcache.xTruncate method. 
**
** Discard all unpinned pages in the cache with a page number equal to
** or greater than parameter iLimit. Any pinned pages with a page number
** equal to or greater than iLimit are implicitly unpinned.
*/
static void pcache1Truncate(sqlite3_pcache *p, unsigned int iLimit){
  PCache1 *pCache = (PCache1 *)p;
  pcache1EnterMutex();
  if( iLimit<=pCache->iMaxKey ){
    pcache1TruncateUnsafe(pCache, iLimit);
    pCache->iMaxKey = iLimit-1;
  }
  pcache1LeaveMutex();
}

/*
** Implementation of the sqlite3_pcache.xDestroy method. 
**
** Destroy a cache allocated using pcache1Create().
*/
static void pcache1Destroy(sqlite3_pcache *p){
  PCache1 *pCache = (PCache1 *)p;

  assert( pCache->bPurgeable || (pCache->nMax==0 && pCache->nMin==0) );
  pcache1EnterMutex();
  pcache1TruncateUnsafe(pCache, 0);
  pcache1.nMaxPage -= pCache->nMax;
  pcache1.nMinPage -= pCache->nMin;
  pcache1EnforceMaxPage();
  pcache1LeaveMutex();
  sqlite3_free(pCache->apHash);
  sqlite3_free(pCache);
}

/*
** This function is called during initialization (sqlite3_initialize()) to
** install the default pluggable cache module, assuming the user has not
................................................................................
**
** nReq is the number of bytes of memory required. Once this much has
** been released, the function returns. The return value is the total number 
** of bytes of memory released.
*/
int sqlite3PcacheReleaseMemory(int nReq){
  int nFree = 0;


  if( pcache1.pStart==0 ){
    PgHdr1 *p;
    pcache1EnterMutex();
    while( (nReq<0 || nFree<nReq) && ((p=pcache1.pLruTail)!=0) ){
      nFree += pcache1MemSize(PGHDR1_TO_PAGE(p));
      pcache1PinPage(p);
      pcache1RemoveFromHash(p);
      pcache1FreePage(p);
    }
    pcache1LeaveMutex();
  }
  return nFree;
}
#endif /* SQLITE_ENABLE_MEMORY_MANAGEMENT */

#ifdef SQLITE_TEST
/*
................................................................................
  int *pnCurrent,      /* OUT: Total number of pages cached */
  int *pnMax,          /* OUT: Global maximum cache size */
  int *pnMin,          /* OUT: Sum of PCache1.nMin for purgeable caches */
  int *pnRecyclable    /* OUT: Total number of pages available for recycling */
){
  PgHdr1 *p;
  int nRecyclable = 0;
  for(p=pcache1.pLruHead; p; p=p->pLruNext){
    nRecyclable++;
  }
  *pnCurrent = pcache1.nCurrentPage;
  *pnMax = pcache1.nMaxPage;
  *pnMin = pcache1.nMinPage;
  *pnRecyclable = nRecyclable;
}
#endif

*/

#include "sqliteInt.h"

typedef struct PCache1 PCache1;
typedef struct PgHdr1 PgHdr1;
typedef struct PgFreeslot PgFreeslot;
typedef struct PGroup PGroup;

/* Each page cache (or PCache) belongs to a PGroup.  A PGroup is a set 
** of one or more PCaches that are able to recycle each others unpinned
** pages when they are under memory pressure.  A PGroup is an instance of
** the following object.
**
** This page cache implementation works in one of two modes:
**
**   (1)  Every PCache is the sole member of its own PGroup.  There is
**        one PGroup per PCache.
**
**   (2)  There is a single global PGroup that all PCaches are a member
**        of.
**
** Mode 1 uses more memory (since PCache instances are not able to rob
** unused pages from other PCaches) but it also operates without a mutex,
** and is therefore often faster.  Mode 2 requires a mutex in order to be
** threadsafe, but is able recycle pages more efficient.
**
** For mode (1), PGroup.mutex is NULL.  For mode (2) there is only a single
** PGroup which is the pcache1.grp global variable and its mutex is
** SQLITE_MUTEX_STATIC_LRU.
*/
struct PGroup {
  sqlite3_mutex *mutex;          /* MUTEX_STATIC_LRU or NULL */
  int nMaxPage;                  /* Sum of nMax for purgeable caches */
  int nMinPage;                  /* Sum of nMin for purgeable caches */
  int nCurrentPage;              /* Number of purgeable pages allocated */
  PgHdr1 *pLruHead, *pLruTail;   /* LRU list of unpinned pages */
};

/* Each page cache is an instance of the following object.  Every
** open database file (including each in-memory database and each
** temporary or transient database) has a single page cache which
** is an instance of this object.
**
** Pointers to structures of this type are cast and returned as 
** opaque sqlite3_pcache* handles.
*/
struct PCache1 {
  /* Cache configuration parameters. Page size (szPage) and the purgeable
  ** flag (bPurgeable) are set when the cache is created. nMax may be 
  ** modified at any time by a call to the pcache1CacheSize() method.
  ** The PGroup mutex must be held when accessing nMax.
  */
  PGroup *pGroup;                     /* PGroup this cache belongs to */
  int szPage;                         /* Size of allocated pages in bytes */
  int bPurgeable;                     /* True if cache is purgeable */
  unsigned int nMin;                  /* Minimum number of pages reserved */
  unsigned int nMax;                  /* Configured "cache_size" value */

  /* Hash table of all pages. The following variables may only be accessed
  ** when the accessor is holding the PGroup mutex.

  */
  unsigned int nRecyclable;           /* Number of pages in the LRU list */
  unsigned int nPage;                 /* Total number of pages in apHash */
  unsigned int nHash;                 /* Number of slots in apHash[] */
  PgHdr1 **apHash;                    /* Hash table for fast lookup by key */

  unsigned int iMaxKey;               /* Largest key seen since xTruncate() */
................................................................................
  PgFreeslot *pNext;  /* Next free slot */
};

/*
** Global data used by this cache.
*/
static SQLITE_WSD struct PCacheGlobal {
  PGroup grp;                    /* The global PGroup for mode (2) */

  /* Variables related to SQLITE_CONFIG_PAGECACHE settings.  The
  ** szSlot, nSlot, pStart, pEnd, nReserve, and isInit values are all
  ** fixed at sqlite3_initialize() time and do not require mutex protection.
  ** The nFreeSlot and pFree values do require mutex protection.
  */
  int isInit;                    /* True if initialized */
  int szSlot;                    /* Size of each free slot */
  int nSlot;                     /* The number of pcache slots */
  int nReserve;                  /* Try to keep nFreeSlot above this */
  void *pStart, *pEnd;           /* Bounds of pagecache malloc range */
  /* Above requires no mutex.  Use mutex below for variable that follow. */
  sqlite3_mutex *mutex;          /* Mutex for accessing the following: */
  int nFreeSlot;                 /* Number of unused pcache slots */
  PgFreeslot *pFree;             /* Free page blocks */
  /* The following value requires a mutex to change.  We skip the mutex on
  ** reading because (1) most platforms read a 32-bit integer atomically and
  ** (2) even if an incorrect value is read, no great harm is done since this
  ** is really just an optimization. */
  int bUnderPressure;            /* True if low on PAGECACHE memory */
} pcache1_g;

/*
** All code in this file should access the global structure above via the
** alias "pcache1". This ensures that the WSD emulation is used when
** compiling for systems that do not support real WSD.
*/
................................................................................
**
**   assert( PGHDR1_TO_PAGE(PAGE_TO_PGHDR1(pCache, X))==X );
*/
#define PGHDR1_TO_PAGE(p)    (void*)(((char*)p) - p->pCache->szPage)
#define PAGE_TO_PGHDR1(c, p) (PgHdr1*)(((char*)p) + c->szPage)

/*
** Macros to enter and leave the PCache LRU mutex.
*/
#define pcache1EnterMutex(X) sqlite3_mutex_enter((X)->mutex)
#define pcache1LeaveMutex(X) sqlite3_mutex_leave((X)->mutex)

/******************************************************************************/
/******** Page Allocation/SQLITE_CONFIG_PCACHE Related Functions **************/

/*
** This function is called during initialization if a static buffer is 
** supplied to use for the page-cache by passing the SQLITE_CONFIG_PAGECACHE
** verb to sqlite3_config(). Parameter pBuf points to an allocation large
** enough to contain 'n' buffers of 'sz' bytes each.
**
** This routine is called from sqlite3_initialize() and so it is guaranteed
** to be serialized already.  There is no need for further mutexing.
*/
void sqlite3PCacheBufferSetup(void *pBuf, int sz, int n){
  if( pcache1.isInit ){
    PgFreeslot *p;
    sz = ROUNDDOWN8(sz);
    pcache1.szSlot = sz;
    pcache1.nSlot = pcache1.nFreeSlot = n;
    pcache1.nReserve = n>90 ? 10 : (n/10 + 1);
    pcache1.pStart = pBuf;
    pcache1.pFree = 0;
    pcache1.bUnderPressure = 0;
    while( n-- ){
      p = (PgFreeslot*)pBuf;
      p->pNext = pcache1.pFree;
      pcache1.pFree = p;
      pBuf = (void*)&((char*)pBuf)[sz];
    }
    pcache1.pEnd = pBuf;
................................................................................
}

/*
** Malloc function used within this file to allocate space from the buffer
** configured using sqlite3_config(SQLITE_CONFIG_PAGECACHE) option. If no 
** such buffer exists or there is no space left in it, this function falls 
** back to sqlite3Malloc().
**
** Multiple threads can run this routine at the same time.  Global variables
** in pcache1 need to be protected via mutex.
*/
static void *pcache1Alloc(int nByte){
  void *p = 0;
  assert( sqlite3_mutex_notheld(pcache1.grp.mutex) );
  sqlite3StatusSet(SQLITE_STATUS_PAGECACHE_SIZE, nByte);
  if( nByte<=pcache1.szSlot ){

    sqlite3_mutex_enter(pcache1.mutex);
    p = (PgHdr1 *)pcache1.pFree;
    if( p ){
      pcache1.pFree = pcache1.pFree->pNext;
      pcache1.nFreeSlot--;
      pcache1.bUnderPressure = pcache1.nFreeSlot<pcache1.nReserve;
      assert( pcache1.nFreeSlot>=0 );
      sqlite3StatusAdd(SQLITE_STATUS_PAGECACHE_USED, 1);

    }




    sqlite3_mutex_leave(pcache1.mutex);
  }
  if( p==0 ){
    /* Memory is not available in the SQLITE_CONFIG_PAGECACHE pool.  Get
    ** it from sqlite3Malloc instead.
    */

    p = sqlite3Malloc(nByte);

    if( p ){
      int sz = sqlite3MallocSize(p);
      sqlite3StatusAdd(SQLITE_STATUS_PAGECACHE_OVERFLOW, sz);
    }
    sqlite3MemdebugSetType(p, MEMTYPE_PCACHE);
  }
  return p;
}

/*
** Free an allocated buffer obtained from pcache1Alloc().
*/
static void pcache1Free(void *p){

  if( p==0 ) return;
  if( p>=pcache1.pStart && p<pcache1.pEnd ){
    PgFreeslot *pSlot;
    sqlite3_mutex_enter(pcache1.mutex);
    sqlite3StatusAdd(SQLITE_STATUS_PAGECACHE_USED, -1);
    pSlot = (PgFreeslot*)p;
    pSlot->pNext = pcache1.pFree;
    pcache1.pFree = pSlot;
    pcache1.nFreeSlot++;
    pcache1.bUnderPressure = pcache1.nFreeSlot<pcache1.nReserve;
    assert( pcache1.nFreeSlot<=pcache1.nSlot );
    sqlite3_mutex_leave(pcache1.mutex);
  }else{
    int iSize;
    assert( sqlite3MemdebugHasType(p, MEMTYPE_PCACHE) );
    sqlite3MemdebugSetType(p, MEMTYPE_HEAP);
    iSize = sqlite3MallocSize(p);
    sqlite3StatusAdd(SQLITE_STATUS_PAGECACHE_OVERFLOW, -iSize);
    sqlite3_free(p);
................................................................................
}

#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
/*
** Return the size of a pcache allocation
*/
static int pcache1MemSize(void *p){

  if( p>=pcache1.pStart && p<pcache1.pEnd ){
    return pcache1.szSlot;
  }else{
    int iSize;
    assert( sqlite3MemdebugHasType(p, MEMTYPE_PCACHE) );
    sqlite3MemdebugSetType(p, MEMTYPE_HEAP);
    iSize = sqlite3MallocSize(p);
................................................................................
static PgHdr1 *pcache1AllocPage(PCache1 *pCache){
  int nByte = sizeof(PgHdr1) + pCache->szPage;
  void *pPg = pcache1Alloc(nByte);
  PgHdr1 *p;
  if( pPg ){
    p = PAGE_TO_PGHDR1(pCache, pPg);
    if( pCache->bPurgeable ){
      pCache->pGroup->nCurrentPage++;
    }
  }else{
    p = 0;
  }
  return p;
}

................................................................................
**
** The pointer is allowed to be NULL, which is prudent.  But it turns out
** that the current implementation happens to never call this routine
** with a NULL pointer, so we mark the NULL test with ALWAYS().
*/
static void pcache1FreePage(PgHdr1 *p){
  if( ALWAYS(p) ){
    PCache1 *pCache = p->pCache;
    if( pCache->bPurgeable ){
      pCache->pGroup->nCurrentPage--;
    }
    pcache1Free(PGHDR1_TO_PAGE(p));
  }
}

/*
** Malloc function used by SQLite to obtain space from the buffer configured
** using sqlite3_config(SQLITE_CONFIG_PAGECACHE) option. If no such buffer
** exists, this function falls back to sqlite3Malloc().
*/
void *sqlite3PageMalloc(int sz){


  return pcache1Alloc(sz);


}

/*
** Free an allocated buffer obtained from sqlite3PageMalloc().
*/
void sqlite3PageFree(void *p){

  pcache1Free(p);

}


/*
** Return true if it desirable to avoid allocating a new page cache
** entry.
**
................................................................................
**
** Or, the heap is used for all page cache memory put the heap is
** under memory pressure, then again it is desirable to avoid
** allocating a new page cache entry in order to avoid stressing
** the heap even further.
*/
static int pcache1UnderMemoryPressure(PCache1 *pCache){

  if( pcache1.nSlot && pCache->szPage<=pcache1.szSlot ){
    return pcache1.bUnderPressure;
  }else{
    return sqlite3HeapNearlyFull();
  }
}

/******************************************************************************/
/******** General Implementation Functions ************************************/

/*
** 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 int pcache1ResizeHash(PCache1 *p){
  PgHdr1 **apNew;
  unsigned int nNew;
  unsigned int i;

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

  nNew = p->nHash*2;
  if( nNew<256 ){
    nNew = 256;
  }

  pcache1LeaveMutex(p->pGroup);
  if( p->nHash ){ sqlite3BeginBenignMalloc(); }
  apNew = (PgHdr1 **)sqlite3_malloc(sizeof(PgHdr1 *)*nNew);
  if( p->nHash ){ sqlite3EndBenignMalloc(); }
  pcache1EnterMutex(p->pGroup);
  if( apNew ){
    memset(apNew, 0, sizeof(PgHdr1 *)*nNew);
    for(i=0; i<p->nHash; i++){
      PgHdr1 *pPage;
      PgHdr1 *pNext = p->apHash[i];
      while( (pPage = pNext)!=0 ){
        unsigned int h = pPage->iKey % nNew;
................................................................................
  }

  return (p->apHash ? SQLITE_OK : SQLITE_NOMEM);
}

/*
** 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.
**
** The PGroup mutex must be held when this function is called.
**
** If pPage is NULL then this routine is a no-op.
*/
static void pcache1PinPage(PgHdr1 *pPage){
  PCache1 *pCache;
  PGroup *pGroup;

  if( pPage==0 ) return;
  pCache = pPage->pCache;
  pGroup = pCache->pGroup;
  assert( sqlite3_mutex_held(pGroup->mutex) );
  if( pPage->pLruNext || pPage==pGroup->pLruTail ){
    if( pPage->pLruPrev ){
      pPage->pLruPrev->pLruNext = pPage->pLruNext;
    }
    if( pPage->pLruNext ){
      pPage->pLruNext->pLruPrev = pPage->pLruPrev;
    }
    if( pGroup->pLruHead==pPage ){
      pGroup->pLruHead = pPage->pLruNext;
    }
    if( pGroup->pLruTail==pPage ){
      pGroup->pLruTail = pPage->pLruPrev;
    }
    pPage->pLruNext = 0;
    pPage->pLruPrev = 0;
    pPage->pCache->nRecyclable--;
  }
}


/*
** Remove the page supplied as an argument from the hash table 
** (PCache1.apHash structure) that it is currently stored in.
**
** The PGroup mutex must be held when this function is called.
*/
static void pcache1RemoveFromHash(PgHdr1 *pPage){
  unsigned int h;
  PCache1 *pCache = pPage->pCache;
  PgHdr1 **pp;

  assert( sqlite3_mutex_held(pCache->pGroup->mutex) );
  h = pPage->iKey % pCache->nHash;
  for(pp=&pCache->apHash[h]; (*pp)!=pPage; pp=&(*pp)->pNext);
  *pp = (*pp)->pNext;

  pCache->nPage--;
}

/*
** If there are currently more than nMaxPage pages allocated, try
** to recycle pages to reduce the number allocated to nMaxPage.
*/
static void pcache1EnforceMaxPage(PGroup *pGroup){
  assert( sqlite3_mutex_held(pGroup->mutex) );
  while( pGroup->nCurrentPage>pGroup->nMaxPage && pGroup->pLruTail ){
    PgHdr1 *p = pGroup->pLruTail;
    assert( p->pCache->pGroup==pGroup );
    pcache1PinPage(p);
    pcache1RemoveFromHash(p);
    pcache1FreePage(p);
  }
}

/*
** Discard all pages from cache pCache with a page number (key value) 
** greater than or equal to iLimit. Any pinned pages that meet this 
** criteria are unpinned before they are discarded.
**
** The PCache mutex must be held when this function is called.
*/
static void pcache1TruncateUnsafe(
  PCache1 *pCache,             /* The cache to truncate */
  unsigned int iLimit          /* Drop pages with this pgno or larger */
){
  TESTONLY( unsigned int nPage = 0; )  /* To assert pCache->nPage is correct */
  unsigned int h;
  assert( sqlite3_mutex_held(pCache->pGroup->mutex) );
  for(h=0; h<pCache->nHash; h++){
    PgHdr1 **pp = &pCache->apHash[h]; 
    PgHdr1 *pPage;
    while( (pPage = *pp)!=0 ){
      if( pPage->iKey>=iLimit ){
        pCache->nPage--;
        *pp = pPage->pNext;
................................................................................
** Implementation of the sqlite3_pcache.xInit method.
*/
static int pcache1Init(void *NotUsed){
  UNUSED_PARAMETER(NotUsed);
  assert( pcache1.isInit==0 );
  memset(&pcache1, 0, sizeof(pcache1));
  if( sqlite3GlobalConfig.bCoreMutex ){
    pcache1.grp.mutex = sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_LRU);
    pcache1.mutex = sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_PMEM);
  }
  pcache1.isInit = 1;
  return SQLITE_OK;
}

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

/*
** Implementation of the sqlite3_pcache.xCreate method.
**
** Allocate a new cache.
*/
static sqlite3_pcache *pcache1Create(int szPage, int bPurgeable){
  PCache1 *pCache;      /* The newly created page cache */
  PGroup *pGroup;       /* The group the new page cache will belong to */
  int sz;               /* Bytes of memory required to allocate the new cache */

  /*
  ** The seperateCache variable is true if each PCache has its own private
  ** PGroup.  In other words, separateCache is true for mode (1) where no
  ** mutexing is required.
  **
  **   *  Always use a unified cache (mode-2) if ENABLE_MEMORY_MANAGEMENT
  **
  **   *  Always use a unified cache in single-threaded applications
  **
  **   *  Otherwise (if multi-threaded and ENABLE_MEMORY_MANAGEMENT is off)
  **      use separate caches (mode-1)
  */
#if defined(SQLITE_ENABLE_MEMORY_MANAGEMENT) || SQLITE_THREADSAFE==0
  const int separateCache = 0;
#else
  int separateCache = sqlite3GlobalConfig.bCoreMutex>0;
#endif

  sz = sizeof(PCache1) + sizeof(PGroup)*separateCache;
  pCache = (PCache1 *)sqlite3_malloc(sz);
  if( pCache ){
    memset(pCache, 0, sz);
    if( separateCache ){
      pGroup = (PGroup*)&pCache[1];
    }else{
      pGroup = &pcache1_g.grp;
    }
    pCache->pGroup = pGroup;
    pCache->szPage = szPage;
    pCache->bPurgeable = (bPurgeable ? 1 : 0);
    if( bPurgeable ){
      pCache->nMin = 10;
      pcache1EnterMutex(pGroup);
      pGroup->nMinPage += pCache->nMin;
      pcache1LeaveMutex(pGroup);
    }
  }
  return (sqlite3_pcache *)pCache;
}

/*
** Implementation of the sqlite3_pcache.xCachesize method. 
**
** Configure the cache_size limit for a cache.
*/
static void pcache1Cachesize(sqlite3_pcache *p, int nMax){
  PCache1 *pCache = (PCache1 *)p;
  if( pCache->bPurgeable ){
    PGroup *pGroup = pCache->pGroup;
    pcache1EnterMutex(pGroup);
    pGroup->nMaxPage += (nMax - pCache->nMax);
    pCache->nMax = nMax;
    pcache1EnforceMaxPage(pGroup);
    pcache1LeaveMutex(pGroup);
  }
}

/*
** Implementation of the sqlite3_pcache.xPagecount method. 
*/
static int pcache1Pagecount(sqlite3_pcache *p){
  int n;
  PCache1 *pCache = (PCache1*)p;
  pcache1EnterMutex(pCache->pGroup);
  n = pCache->nPage;
  pcache1LeaveMutex(pCache->pGroup);
  return n;
}

/*
** Implementation of the sqlite3_pcache.xFetch method. 
**
** Fetch a page by key value.
................................................................................
**      proceed to step 5. 
**
**   5. Otherwise, allocate and return a new page buffer.
*/
static void *pcache1Fetch(sqlite3_pcache *p, unsigned int iKey, int createFlag){
  unsigned int nPinned;
  PCache1 *pCache = (PCache1 *)p;
  PGroup *pGroup = pCache->pGroup;
  PgHdr1 *pPage = 0;

  assert( pCache->bPurgeable || createFlag!=1 );
  pcache1EnterMutex(pGroup);
  if( createFlag==1 ) sqlite3BeginBenignMalloc();

  /* Search the hash table for an existing entry. */
  if( pCache->nHash>0 ){
    unsigned int h = iKey % pCache->nHash;
    for(pPage=pCache->apHash[h]; pPage&&pPage->iKey!=iKey; pPage=pPage->pNext);
  }
................................................................................
    pcache1PinPage(pPage);
    goto fetch_out;
  }

  /* Step 3 of header comment. */
  nPinned = pCache->nPage - pCache->nRecyclable;
  if( createFlag==1 && (
        nPinned>=(pGroup->nMaxPage+pCache->nMin-pGroup->nMinPage)
     || nPinned>=(pCache->nMax * 9 / 10)
     || pcache1UnderMemoryPressure(pCache)
  )){
    goto fetch_out;
  }

  if( pCache->nPage>=pCache->nHash && pcache1ResizeHash(pCache) ){
    goto fetch_out;
  }

  /* Step 4. Try to recycle a page buffer if appropriate. */
  if( pCache->bPurgeable && pGroup->pLruTail && (
         (pCache->nPage+1>=pCache->nMax)
      || pGroup->nCurrentPage>=pGroup->nMaxPage
      || pcache1UnderMemoryPressure(pCache)
  )){
    pPage = pGroup->pLruTail;
    pcache1RemoveFromHash(pPage);
    pcache1PinPage(pPage);
    if( pPage->pCache->szPage!=pCache->szPage ){
      pcache1FreePage(pPage);
      pPage = 0;
    }else{
      pGroup->nCurrentPage -= 
               (pPage->pCache->bPurgeable - pCache->bPurgeable);
    }
  }

  /* Step 5. If a usable page buffer has still not been found, 
  ** attempt to allocate a new one. 
  */
  if( !pPage ){
    pcache1LeaveMutex(pGroup);
    pPage = pcache1AllocPage(pCache);
    pcache1EnterMutex(pGroup);
  }

  if( pPage ){
    unsigned int h = iKey % pCache->nHash;
    pCache->nPage++;
    pPage->iKey = iKey;
    pPage->pNext = pCache->apHash[h];
................................................................................
  }

fetch_out:
  if( pPage && iKey>pCache->iMaxKey ){
    pCache->iMaxKey = iKey;
  }
  if( createFlag==1 ) sqlite3EndBenignMalloc();
  pcache1LeaveMutex(pGroup);
  return (pPage ? PGHDR1_TO_PAGE(pPage) : 0);
}


/*
** Implementation of the sqlite3_pcache.xUnpin method.
**
** Mark a page as unpinned (eligible for asynchronous recycling).
*/
static void pcache1Unpin(sqlite3_pcache *p, void *pPg, int reuseUnlikely){
  PCache1 *pCache = (PCache1 *)p;
  PgHdr1 *pPage = PAGE_TO_PGHDR1(pCache, pPg);
  PGroup *pGroup = pCache->pGroup;
 
  assert( pPage->pCache==pCache );
  pcache1EnterMutex(pGroup);

  /* It is an error to call this function if the page is already 
  ** part of the PGroup LRU list.
  */
  assert( pPage->pLruPrev==0 && pPage->pLruNext==0 );

  assert( pGroup->pLruHead!=pPage && pGroup->pLruTail!=pPage );

  if( reuseUnlikely || pGroup->nCurrentPage>pGroup->nMaxPage ){
    pcache1RemoveFromHash(pPage);
    pcache1FreePage(pPage);
  }else{
    /* Add the page to the PGroup LRU list. */




    if( pGroup->pLruHead ){
      pGroup->pLruHead->pLruPrev = pPage;
      pPage->pLruNext = pGroup->pLruHead;
      pGroup->pLruHead = pPage;
    }else{
      pGroup->pLruTail = pPage;
      pGroup->pLruHead = pPage;
    }
    pCache->nRecyclable++;
  }

  pcache1LeaveMutex(pCache->pGroup);
}

/*
** Implementation of the sqlite3_pcache.xRekey method. 
*/
static void pcache1Rekey(
  sqlite3_pcache *p,
................................................................................
  PCache1 *pCache = (PCache1 *)p;
  PgHdr1 *pPage = PAGE_TO_PGHDR1(pCache, pPg);
  PgHdr1 **pp;
  unsigned int h; 
  assert( pPage->iKey==iOld );
  assert( pPage->pCache==pCache );

  pcache1EnterMutex(pCache->pGroup);

  h = iOld%pCache->nHash;
  pp = &pCache->apHash[h];
  while( (*pp)!=pPage ){
    pp = &(*pp)->pNext;
  }
  *pp = pPage->pNext;
................................................................................
  pPage->iKey = iNew;
  pPage->pNext = pCache->apHash[h];
  pCache->apHash[h] = pPage;
  if( iNew>pCache->iMaxKey ){
    pCache->iMaxKey = iNew;
  }

  pcache1LeaveMutex(pCache->pGroup);
}

/*
** Implementation of the sqlite3_pcache.xTruncate method. 
**
** Discard all unpinned pages in the cache with a page number equal to
** or greater than parameter iLimit. Any pinned pages with a page number
** equal to or greater than iLimit are implicitly unpinned.
*/
static void pcache1Truncate(sqlite3_pcache *p, unsigned int iLimit){
  PCache1 *pCache = (PCache1 *)p;
  pcache1EnterMutex(pCache->pGroup);
  if( iLimit<=pCache->iMaxKey ){
    pcache1TruncateUnsafe(pCache, iLimit);
    pCache->iMaxKey = iLimit-1;
  }
  pcache1LeaveMutex(pCache->pGroup);
}

/*
** Implementation of the sqlite3_pcache.xDestroy method. 
**
** Destroy a cache allocated using pcache1Create().
*/
static void pcache1Destroy(sqlite3_pcache *p){
  PCache1 *pCache = (PCache1 *)p;
  PGroup *pGroup = pCache->pGroup;
  assert( pCache->bPurgeable || (pCache->nMax==0 && pCache->nMin==0) );
  pcache1EnterMutex(pGroup);
  pcache1TruncateUnsafe(pCache, 0);
  pGroup->nMaxPage -= pCache->nMax;
  pGroup->nMinPage -= pCache->nMin;
  pcache1EnforceMaxPage(pGroup);
  pcache1LeaveMutex(pGroup);
  sqlite3_free(pCache->apHash);
  sqlite3_free(pCache);
}

/*
** This function is called during initialization (sqlite3_initialize()) to
** install the default pluggable cache module, assuming the user has not
................................................................................
**
** nReq is the number of bytes of memory required. Once this much has
** been released, the function returns. The return value is the total number 
** of bytes of memory released.
*/
int sqlite3PcacheReleaseMemory(int nReq){
  int nFree = 0;
  assert( sqlite3_mutex_notheld(pcache1.grp.mutex) );
  assert( sqlite3_mutex_notheld(pcache1.mutex) );
  if( pcache1.pStart==0 ){
    PgHdr1 *p;
    pcache1EnterMutex(&pcache1.grp);
    while( (nReq<0 || nFree<nReq) && ((p=pcache1.grp.pLruTail)!=0) ){
      nFree += pcache1MemSize(PGHDR1_TO_PAGE(p));
      pcache1PinPage(p);
      pcache1RemoveFromHash(p);
      pcache1FreePage(p);
    }
    pcache1LeaveMutex(&pcache1.grp);
  }
  return nFree;
}
#endif /* SQLITE_ENABLE_MEMORY_MANAGEMENT */

#ifdef SQLITE_TEST
/*
................................................................................
  int *pnCurrent,      /* OUT: Total number of pages cached */
  int *pnMax,          /* OUT: Global maximum cache size */
  int *pnMin,          /* OUT: Sum of PCache1.nMin for purgeable caches */
  int *pnRecyclable    /* OUT: Total number of pages available for recycling */
){
  PgHdr1 *p;
  int nRecyclable = 0;
  for(p=pcache1.grp.pLruHead; p; p=p->pLruNext){
    nRecyclable++;
  }
  *pnCurrent = pcache1.grp.nCurrentPage;
  *pnMax = pcache1.grp.nMaxPage;
  *pnMin = pcache1.grp.nMinPage;
  *pnRecyclable = nRecyclable;
}
#endif

** chunks (say 1MB at a time), may reduce file-system fragmentation and
** improve performance on some systems.
**
** The [SQLITE_FCNTL_FILE_POINTER] opcode is used to obtain a pointer
** to the [sqlite3_file] object associated with a particular database
** connection.  See the [sqlite3_file_control()] documentation for
** additional information.






*/
#define SQLITE_FCNTL_LOCKSTATE        1
#define SQLITE_GET_LOCKPROXYFILE      2
#define SQLITE_SET_LOCKPROXYFILE      3
#define SQLITE_LAST_ERRNO             4
#define SQLITE_FCNTL_SIZE_HINT        5
#define SQLITE_FCNTL_CHUNK_SIZE       6
#define SQLITE_FCNTL_FILE_POINTER     7



/*
** CAPI3REF: Mutex Handle
**
** The mutex module within SQLite defines [sqlite3_mutex] to be an
** abstract type for a mutex object.  The SQLite core never looks
................................................................................
**
** ^(<dt>[SQLITE_OPEN_READWRITE]</dt>
** <dd>The database is opened for reading and writing if possible, or reading
** only if the file is write protected by the operating system.  In either
** case the database must already exist, otherwise an error is returned.</dd>)^
**
** ^(<dt>[SQLITE_OPEN_READWRITE] | [SQLITE_OPEN_CREATE]</dt>
** <dd>The database is opened for reading and writing, and is creates it if
** it does not already exist. This is the behavior that is always used for
** sqlite3_open() and sqlite3_open16().</dd>)^
** </dl>
**
** If the 3rd parameter to sqlite3_open_v2() is not one of the
** combinations shown above or one of the combinations shown above combined
** with the [SQLITE_OPEN_NOMUTEX], [SQLITE_OPEN_FULLMUTEX],
................................................................................
*/
const char *sqlite3_sql(sqlite3_stmt *pStmt);

/*
** CAPI3REF: Determine If An SQL Statement Writes The Database
**
** ^The sqlite3_stmt_readonly(X) interface returns true (non-zero) if 
** and only if the [prepared statement] X is makes no direct changes to
** the content of the database file.
**
** Note that [application-defined SQL functions] or
** [virtual tables] might change the database indirectly as a side effect.  
** ^(For example, if an application defines a function "eval()" that 
** calls [sqlite3_exec()], then the following SQL statement would
** change the database file through side-effects:
................................................................................
** [SQLITE_MISUSE] means that the this routine was called inappropriately.
** Perhaps it was called on a [prepared statement] that has
** already been [sqlite3_finalize | finalized] or on one that had
** previously returned [SQLITE_ERROR] or [SQLITE_DONE].  Or it could
** be the case that the same database connection is being used by two or
** more threads at the same moment in time.
**
** For all versions of SQLite up to and including 3.6.23.1, it was required
** after sqlite3_step() returned anything other than [SQLITE_ROW] that
** [sqlite3_reset()] be called before any subsequent invocation of
** sqlite3_step().  Failure to invoke [sqlite3_reset()] in this way would
** result in an [SQLITE_MISUSE] return from sqlite3_step().  But after
** version 3.6.23.1, sqlite3_step() began calling [sqlite3_reset()] 
** automatically in this circumstance rather than returning [SQLITE_MISUSE].  




**
** <b>Goofy Interface Alert:</b> In the legacy interface, the sqlite3_step()
** API always returns a generic error code, [SQLITE_ERROR], following any
** error other than [SQLITE_BUSY] and [SQLITE_MISUSE].  You must call
** [sqlite3_reset()] or [sqlite3_finalize()] in order to find one of the
** specific [error codes] that better describes the error.
** We admit that this is a goofy design.  The problem has been fixed
................................................................................
#define SQLITE_MUTEX_RECURSIVE        1
#define SQLITE_MUTEX_STATIC_MASTER    2
#define SQLITE_MUTEX_STATIC_MEM       3  /* sqlite3_malloc() */
#define SQLITE_MUTEX_STATIC_MEM2      4  /* NOT USED */
#define SQLITE_MUTEX_STATIC_OPEN      4  /* sqlite3BtreeOpen() */
#define SQLITE_MUTEX_STATIC_PRNG      5  /* sqlite3_random() */
#define SQLITE_MUTEX_STATIC_LRU       6  /* lru page list */
#define SQLITE_MUTEX_STATIC_LRU2      7  /* lru page list */


/*
** CAPI3REF: Retrieve the mutex for a database connection
**
** ^This interface returns a pointer the [sqlite3_mutex] object that 
** serializes access to the [database connection] given in the argument
** when the [threading mode] is Serialized.
................................................................................
**
** ^SQLite invokes the xCreate() method to construct a new cache instance.
** SQLite will typically create one cache instance for each open database file,
** though this is not guaranteed. ^The
** first parameter, szPage, is the size in bytes of the pages that must
** be allocated by the cache.  ^szPage will not be a power of two.  ^szPage
** will the page size of the database file that is to be cached plus an
** increment (here called "R") of about 100 or 200.  SQLite will use the
** extra R bytes on each page to store metadata about the underlying
** database page on disk.  The value of R depends
** on the SQLite version, the target platform, and how SQLite was compiled.
** ^R is constant for a particular build of SQLite.  ^The second argument to


** xCreate(), bPurgeable, is true if the cache being created will
** be used to cache database pages of a file stored on disk, or
** false if it is used for an in-memory database. The cache implementation
** does not have to do anything special based with the value of bPurgeable;
** it is purely advisory.  ^On a cache where bPurgeable is false, SQLite will
** never invoke xUnpin() except to deliberately delete a page.
** ^In other words, calls to xUnpin() on a cache with bPurgeable set to
................................................................................
** 8-byte boundary. The page to be fetched is determined by the key. ^The
** mimimum key value is 1.  After it has been retrieved using xFetch, the page 
** is considered to be "pinned".
**
** If the requested page is already in the page cache, then the page cache
** implementation must return a pointer to the page buffer with its content
** intact.  If the requested page is not already in the cache, then the
** behavior of the cache implementation should use the value of the createFlag
** parameter to help it determined what action to take:
**
** <table border=1 width=85% align=center>
** <tr><th> createFlag <th> Behaviour when page is not already in cache
** <tr><td> 0 <td> Do not allocate a new page.  Return NULL.
** <tr><td> 1 <td> Allocate a new page if it easy and convenient to do so.
**                 Otherwise return NULL.

** chunks (say 1MB at a time), may reduce file-system fragmentation and
** improve performance on some systems.
**
** The [SQLITE_FCNTL_FILE_POINTER] opcode is used to obtain a pointer
** to the [sqlite3_file] object associated with a particular database
** connection.  See the [sqlite3_file_control()] documentation for
** additional information.
**
** The [SQLITE_FCNTL_SYNC] opcode is used internally. SQLite calls
** the file-control method with this opcode immediately after the database
** file is synced, or if the database is running in synchronous=off mode
** immediately after it would have been synced otherwise. This makes it
** easier to write special VFS modules that depend on the xSync call.
*/
#define SQLITE_FCNTL_LOCKSTATE        1
#define SQLITE_GET_LOCKPROXYFILE      2
#define SQLITE_SET_LOCKPROXYFILE      3
#define SQLITE_LAST_ERRNO             4
#define SQLITE_FCNTL_SIZE_HINT        5
#define SQLITE_FCNTL_CHUNK_SIZE       6
#define SQLITE_FCNTL_FILE_POINTER     7
#define SQLITE_FCNTL_SYNC             8


/*
** CAPI3REF: Mutex Handle
**
** The mutex module within SQLite defines [sqlite3_mutex] to be an
** abstract type for a mutex object.  The SQLite core never looks
................................................................................
**
** ^(<dt>[SQLITE_OPEN_READWRITE]</dt>
** <dd>The database is opened for reading and writing if possible, or reading
** only if the file is write protected by the operating system.  In either
** case the database must already exist, otherwise an error is returned.</dd>)^
**
** ^(<dt>[SQLITE_OPEN_READWRITE] | [SQLITE_OPEN_CREATE]</dt>
** <dd>The database is opened for reading and writing, and is created if
** it does not already exist. This is the behavior that is always used for
** sqlite3_open() and sqlite3_open16().</dd>)^
** </dl>
**
** If the 3rd parameter to sqlite3_open_v2() is not one of the
** combinations shown above or one of the combinations shown above combined
** with the [SQLITE_OPEN_NOMUTEX], [SQLITE_OPEN_FULLMUTEX],
................................................................................
*/
const char *sqlite3_sql(sqlite3_stmt *pStmt);

/*
** CAPI3REF: Determine If An SQL Statement Writes The Database
**
** ^The sqlite3_stmt_readonly(X) interface returns true (non-zero) if 
** and only if the [prepared statement] X makes no direct changes to
** the content of the database file.
**
** Note that [application-defined SQL functions] or
** [virtual tables] might change the database indirectly as a side effect.  
** ^(For example, if an application defines a function "eval()" that 
** calls [sqlite3_exec()], then the following SQL statement would
** change the database file through side-effects:
................................................................................
** [SQLITE_MISUSE] means that the this routine was called inappropriately.
** Perhaps it was called on a [prepared statement] that has
** already been [sqlite3_finalize | finalized] or on one that had
** previously returned [SQLITE_ERROR] or [SQLITE_DONE].  Or it could
** be the case that the same database connection is being used by two or
** more threads at the same moment in time.
**
** For all versions of SQLite up to and including 3.6.23.1, a call to
** [sqlite3_reset()] was required after sqlite3_step() returned anything
** other than [SQLITE_ROW] before any subsequent invocation of
** sqlite3_step().  Failure to reset the prepared statement using 
** [sqlite3_reset()] would result in an [SQLITE_MISUSE] return from
** sqlite3_step().  But after version 3.6.23.1, sqlite3_step() began
** calling [sqlite3_reset()] automatically in this circumstance rather
** than returning [SQLITE_MISUSE].  This is not considered a compatibility
** break because any application that ever receives an SQLITE_MISUSE error
** is broken by definition.  The [SQLITE_OMIT_AUTORESET] compile-time option
** can be used to restore the legacy behavior.
**
** <b>Goofy Interface Alert:</b> In the legacy interface, the sqlite3_step()
** API always returns a generic error code, [SQLITE_ERROR], following any
** error other than [SQLITE_BUSY] and [SQLITE_MISUSE].  You must call
** [sqlite3_reset()] or [sqlite3_finalize()] in order to find one of the
** specific [error codes] that better describes the error.
** We admit that this is a goofy design.  The problem has been fixed
................................................................................
#define SQLITE_MUTEX_RECURSIVE        1
#define SQLITE_MUTEX_STATIC_MASTER    2
#define SQLITE_MUTEX_STATIC_MEM       3  /* sqlite3_malloc() */
#define SQLITE_MUTEX_STATIC_MEM2      4  /* NOT USED */
#define SQLITE_MUTEX_STATIC_OPEN      4  /* sqlite3BtreeOpen() */
#define SQLITE_MUTEX_STATIC_PRNG      5  /* sqlite3_random() */
#define SQLITE_MUTEX_STATIC_LRU       6  /* lru page list */
#define SQLITE_MUTEX_STATIC_LRU2      7  /* NOT USED */
#define SQLITE_MUTEX_STATIC_PMEM      7  /* sqlite3PageMalloc() */

/*
** CAPI3REF: Retrieve the mutex for a database connection
**
** ^This interface returns a pointer the [sqlite3_mutex] object that 
** serializes access to the [database connection] given in the argument
** when the [threading mode] is Serialized.
................................................................................
**
** ^SQLite invokes the xCreate() method to construct a new cache instance.
** SQLite will typically create one cache instance for each open database file,
** though this is not guaranteed. ^The
** first parameter, szPage, is the size in bytes of the pages that must
** be allocated by the cache.  ^szPage will not be a power of two.  ^szPage
** will the page size of the database file that is to be cached plus an
** increment (here called "R") of less than 250.  SQLite will use the
** extra R bytes on each page to store metadata about the underlying
** database page on disk.  The value of R depends
** on the SQLite version, the target platform, and how SQLite was compiled.
** ^(R is constant for a particular build of SQLite. Except, there are two
** distinct values of R when SQLite is compiled with the proprietary
** ZIPVFS extension.)^  ^The second argument to
** xCreate(), bPurgeable, is true if the cache being created will
** be used to cache database pages of a file stored on disk, or
** false if it is used for an in-memory database. The cache implementation
** does not have to do anything special based with the value of bPurgeable;
** it is purely advisory.  ^On a cache where bPurgeable is false, SQLite will
** never invoke xUnpin() except to deliberately delete a page.
** ^In other words, calls to xUnpin() on a cache with bPurgeable set to
................................................................................
** 8-byte boundary. The page to be fetched is determined by the key. ^The
** mimimum key value is 1.  After it has been retrieved using xFetch, the page 
** is considered to be "pinned".
**
** If the requested page is already in the page cache, then the page cache
** implementation must return a pointer to the page buffer with its content
** intact.  If the requested page is not already in the cache, then the
** cache implementation should use the value of the createFlag
** parameter to help it determined what action to take:
**
** <table border=1 width=85% align=center>
** <tr><th> createFlag <th> Behaviour when page is not already in cache
** <tr><td> 0 <td> Do not allocate a new page.  Return NULL.
** <tr><td> 1 <td> Allocate a new page if it easy and convenient to do so.
**                 Otherwise return NULL.

#endif

#ifdef SQLITE_OMIT_AUTOMATIC_INDEX
  Tcl_SetVar2(interp, "sqlite_options", "autoindex", "0", TCL_GLOBAL_ONLY);
#else
  Tcl_SetVar2(interp, "sqlite_options", "autoindex", "1", TCL_GLOBAL_ONLY);
#endif







#ifdef SQLITE_OMIT_AUTOVACUUM
  Tcl_SetVar2(interp, "sqlite_options", "autovacuum", "0", TCL_GLOBAL_ONLY);
#else
  Tcl_SetVar2(interp, "sqlite_options", "autovacuum", "1", TCL_GLOBAL_ONLY);
#endif /* SQLITE_OMIT_AUTOVACUUM */
#if !defined(SQLITE_DEFAULT_AUTOVACUUM)

#endif

#ifdef SQLITE_OMIT_AUTOMATIC_INDEX
  Tcl_SetVar2(interp, "sqlite_options", "autoindex", "0", TCL_GLOBAL_ONLY);
#else
  Tcl_SetVar2(interp, "sqlite_options", "autoindex", "1", TCL_GLOBAL_ONLY);
#endif

#ifdef SQLITE_OMIT_AUTORESET
  Tcl_SetVar2(interp, "sqlite_options", "autoreset", "0", TCL_GLOBAL_ONLY);
#else
  Tcl_SetVar2(interp, "sqlite_options", "autoreset", "1", TCL_GLOBAL_ONLY);
#endif

#ifdef SQLITE_OMIT_AUTOVACUUM
  Tcl_SetVar2(interp, "sqlite_options", "autovacuum", "0", TCL_GLOBAL_ONLY);
#else
  Tcl_SetVar2(interp, "sqlite_options", "autovacuum", "1", TCL_GLOBAL_ONLY);
#endif /* SQLITE_OMIT_AUTOVACUUM */
#if !defined(SQLITE_DEFAULT_AUTOVACUUM)

  pFd = (TestvfsFd *)ckalloc(sizeof(TestvfsFd) + PARENTVFS(pVfs)->szOsFile);
  memset(pFd, 0, sizeof(TestvfsFd) + PARENTVFS(pVfs)->szOsFile);
  pFd->pShm = 0;
  pFd->pShmId = 0;
  pFd->zFilename = zName;
  pFd->pVfs = pVfs;
  pFd->pReal = (sqlite3_file *)&pFd[1];

  pTestfile->pFd = pFd;

  /* Evaluate the Tcl script: 
  **
  **   SCRIPT xOpen FILENAME
  **
  ** If the script returns an SQLite error code other than SQLITE_OK, an

  pFd = (TestvfsFd *)ckalloc(sizeof(TestvfsFd) + PARENTVFS(pVfs)->szOsFile);
  memset(pFd, 0, sizeof(TestvfsFd) + PARENTVFS(pVfs)->szOsFile);
  pFd->pShm = 0;
  pFd->pShmId = 0;
  pFd->zFilename = zName;
  pFd->pVfs = pVfs;
  pFd->pReal = (sqlite3_file *)&pFd[1];
  memset(pTestfile, 0, sizeof(TestvfsFile));
  pTestfile->pFd = pFd;

  /* Evaluate the Tcl script: 
  **
  **   SCRIPT xOpen FILENAME
  **
  ** If the script returns an SQLite error code other than SQLITE_OK, an

** The cursor can seek to a BTree entry with a particular key, or
** loop over all entries of the Btree.  You can also insert new BTree
** entries or retrieve the key or data from the entry that the cursor
** is currently pointing to.
** 
** Every cursor that the virtual machine has open is represented by an
** instance of the following structure.
**
** If the VdbeCursor.isTriggerRow flag is set it means that this cursor is
** really a single row that represents the NEW or OLD pseudo-table of
** a row trigger.  The data for the row is stored in VdbeCursor.pData and
** the rowid is in VdbeCursor.iKey.
*/
struct VdbeCursor {
  BtCursor *pCursor;    /* The cursor structure of the backend */


  int iDb;              /* Index of cursor database in db->aDb[] (or -1) */
  i64 lastRowid;        /* Last rowid from a Next or NextIdx operation */


  Bool zeroed;          /* True if zeroed out and ready for reuse */
  Bool rowidIsValid;    /* True if lastRowid is valid */
  Bool atFirst;         /* True if pointing to first entry */
  Bool useRandomRowid;  /* Generate new record numbers semi-randomly */
  Bool nullRow;         /* True if pointing to a row with no data */
  Bool deferredMoveto;  /* A call to sqlite3BtreeMoveto() is needed */
  Bool isTable;         /* True if a table requiring integer keys */
  Bool isIndex;         /* True if an index containing keys only - no data */
  Bool isOrdered;       /* True if the underlying table is BTREE_UNORDERED */
  i64 movetoTarget;     /* Argument to the deferred sqlite3BtreeMoveto() */
  Btree *pBt;           /* Separate file holding temporary table */
  int pseudoTableReg;   /* Register holding pseudotable content. */
  KeyInfo *pKeyInfo;    /* Info about index keys needed by index cursors */
  int nField;           /* Number of fields in the header */
  i64 seqCount;         /* Sequence counter */
  sqlite3_vtab_cursor *pVtabCursor;  /* The cursor for a virtual table */
  const sqlite3_module *pModule;     /* Module for cursor pVtabCursor */




  /* Result of last sqlite3BtreeMoveto() done by an OP_NotExists or 
  ** OP_IsUnique opcode on this cursor. */
  int seekResult;

  /* Cached information about the header for the data record that the
  ** cursor is currently pointing to.  Only valid if cacheStatus matches
................................................................................
** A value for VdbeCursor.cacheValid that means the cache is always invalid.
*/
#define CACHE_STALE 0

/*
** Internally, the vdbe manipulates nearly all SQL values as Mem
** structures. Each Mem struct may cache multiple representations (string,
** integer etc.) of the same value.  A value (and therefore Mem structure)
** has the following properties:
**
** Each value has a manifest type. The manifest type of the value stored
** in a Mem struct is returned by the MemType(Mem*) macro. The type is
** one of SQLITE_NULL, SQLITE_INTEGER, SQLITE_REAL, SQLITE_TEXT or
** SQLITE_BLOB.
*/
struct Mem {



  union {
    i64 i;              /* Integer value. */
    int nZero;          /* Used when bit MEM_Zero is set in flags */
    FuncDef *pDef;      /* Used only when flags==MEM_Agg */
    RowSet *pRowSet;    /* Used only when flags==MEM_RowSet */
    VdbeFrame *pFrame;  /* Used when flags==MEM_Frame */
  } u;
  double r;           /* Real value */
  sqlite3 *db;        /* The associated database connection */
  char *z;            /* String or BLOB value */
  int n;              /* Number of characters in string value, excluding '\0' */
  u16 flags;          /* Some combination of MEM_Null, MEM_Str, MEM_Dyn, etc. */
  u8  type;           /* One of SQLITE_NULL, SQLITE_TEXT, SQLITE_INTEGER, etc */
  u8  enc;            /* SQLITE_UTF8, SQLITE_UTF16BE, SQLITE_UTF16LE */
#ifdef SQLITE_DEBUG
  Mem *pScopyFrom;    /* This Mem is a shallow copy of pScopyFrom */
  void *pFiller;      /* So that sizeof(Mem) is a multiple of 8 */
................................................................................
** No other flags may be set in this case.
**
** If the MEM_Str flag is set then Mem.z points at a string representation.
** Usually this is encoded in the same unicode encoding as the main
** database (see below for exceptions). If the MEM_Term flag is also
** set, then the string is nul terminated. The MEM_Int and MEM_Real 
** flags may coexist with the MEM_Str flag.
**
** Multiple of these values can appear in Mem.flags.  But only one
** at a time can appear in Mem.type.
*/
#define MEM_Null      0x0001   /* Value is NULL */
#define MEM_Str       0x0002   /* Value is a string */
#define MEM_Int       0x0004   /* Value is an integer */
#define MEM_Real      0x0008   /* Value is a real number */
#define MEM_Blob      0x0010   /* Value is a BLOB */
#define MEM_RowSet    0x0020   /* Value is a RowSet object */
................................................................................
  VdbeFunc *pVdbeFunc;  /* Auxilary data, if created. */
  Mem s;                /* The return value is stored here */
  Mem *pMem;            /* Memory cell used to store aggregate context */
  int isError;          /* Error code returned by the function. */
  CollSeq *pColl;       /* Collating sequence */
};

/*
** A Set structure is used for quick testing to see if a value
** is part of a small set.  Sets are used to implement code like
** this:
**            x.y IN ('hi','hoo','hum')
*/
typedef struct Set Set;
struct Set {
  Hash hash;             /* A set is just a hash table */
  HashElem *prev;        /* Previously accessed hash elemen */
};

/*
** An instance of the virtual machine.  This structure contains the complete
** state of the virtual machine.
**
** The "sqlite3_stmt" structure pointer that is returned by sqlite3_compile()
** is really a pointer to an instance of this structure.
**
** The Vdbe.inVtabMethod variable is set to non-zero for the duration of
** any virtual table method invocations made by the vdbe program. It is
** set to 2 for xDestroy method calls and 1 for all other methods. This
** variable is used for two purposes: to allow xDestroy methods to execute
** "DROP TABLE" statements and to prevent some nasty side effects of
** malloc failure when SQLite is invoked recursively by a virtual table 
** method function.
*/
struct Vdbe {
  sqlite3 *db;            /* The database connection that owns this statement */
  Vdbe *pPrev,*pNext;     /* Linked list of VDBEs with the same Vdbe.db */
  int nOp;                /* Number of instructions in the program */
  int nOpAlloc;           /* Number of slots allocated for aOp[] */
  Op *aOp;                /* Space to hold the virtual machine's program */
  int nLabel;             /* Number of labels used */
  int nLabelAlloc;        /* Number of slots allocated in aLabel[] */
  int *aLabel;            /* Space to hold the labels */

  Mem **apArg;            /* Arguments to currently executing user function */
  Mem *aColName;          /* Column names to return */
  Mem *pResultSet;        /* Pointer to an array of results */






  u16 nResColumn;         /* Number of columns in one row of the result set */
  u16 nCursor;            /* Number of slots in apCsr[] */



  VdbeCursor **apCsr;     /* One element of this array for each open cursor */
  u8 errorAction;         /* Recovery action to do in case of an error */
  u8 okVar;               /* True if azVar[] has been initialized */
  ynVar nVar;             /* Number of entries in aVar[] */
  Mem *aVar;              /* Values for the OP_Variable opcode. */
  char **azVar;           /* Name of variables */
  u32 magic;              /* Magic number for sanity checking */
  int nMem;               /* Number of memory locations currently allocated */
  Mem *aMem;              /* The memory locations */

  u32 cacheCtr;           /* VdbeCursor row cache generation counter */
  int pc;                 /* The program counter */
  int rc;                 /* Value to return */
  char *zErrMsg;          /* Error message written here */

  u8 explain;             /* True if EXPLAIN present on SQL command */
  u8 changeCntOn;         /* True to update the change-counter */
  u8 expired;             /* True if the VM needs to be recompiled */
  u8 runOnlyOnce;         /* Automatically expire on reset */
  u8 minWriteFileFormat;  /* Minimum file format for writable database files */
  u8 inVtabMethod;        /* See comments above */
  u8 usesStmtJournal;     /* True if uses a statement journal */
  u8 readOnly;            /* True for read-only statements */
  u8 isPrepareV2;         /* True if prepared with prepare_v2() */
  int nChange;            /* Number of db changes made since last reset */
  int btreeMask;          /* Bitmask of db->aDb[] entries referenced */
  i64 startTime;          /* Time when query started - used for profiling */
  BtreeMutexArray aMutex; /* An array of Btree used here and needing locks */
  int aCounter[3];        /* Counters used by sqlite3_stmt_status() */

  char *zSql;             /* Text of the SQL statement that generated this */
  void *pFree;            /* Free this when deleting the vdbe */

  i64 nFkConstraint;      /* Number of imm. FK constraints this VM */
  i64 nStmtDefCons;       /* Number of def. constraints when stmt started */
  int iStatement;         /* Statement number (or 0 if has not opened stmt) */


#ifdef SQLITE_DEBUG
  FILE *trace;            /* Write an execution trace here, if not NULL */
#endif
  VdbeFrame *pFrame;      /* Parent frame */
  VdbeFrame *pDelFrame;   /* List of frame objects to free on VM reset */
  int nFrame;             /* Number of frames in pFrame list */
  u32 expmask;            /* Binding to these vars invalidates VM */

** The cursor can seek to a BTree entry with a particular key, or
** loop over all entries of the Btree.  You can also insert new BTree
** entries or retrieve the key or data from the entry that the cursor
** is currently pointing to.
** 
** Every cursor that the virtual machine has open is represented by an
** instance of the following structure.





*/
struct VdbeCursor {
  BtCursor *pCursor;    /* The cursor structure of the backend */
  Btree *pBt;           /* Separate file holding temporary table */
  KeyInfo *pKeyInfo;    /* Info about index keys needed by index cursors */
  int iDb;              /* Index of cursor database in db->aDb[] (or -1) */

  int pseudoTableReg;   /* Register holding pseudotable content. */
  int nField;           /* Number of fields in the header */
  Bool zeroed;          /* True if zeroed out and ready for reuse */
  Bool rowidIsValid;    /* True if lastRowid is valid */
  Bool atFirst;         /* True if pointing to first entry */
  Bool useRandomRowid;  /* Generate new record numbers semi-randomly */
  Bool nullRow;         /* True if pointing to a row with no data */
  Bool deferredMoveto;  /* A call to sqlite3BtreeMoveto() is needed */
  Bool isTable;         /* True if a table requiring integer keys */
  Bool isIndex;         /* True if an index containing keys only - no data */
  Bool isOrdered;       /* True if the underlying table is BTREE_UNORDERED */






  sqlite3_vtab_cursor *pVtabCursor;  /* The cursor for a virtual table */
  const sqlite3_module *pModule;     /* Module for cursor pVtabCursor */
  i64 seqCount;         /* Sequence counter */
  i64 movetoTarget;     /* Argument to the deferred sqlite3BtreeMoveto() */
  i64 lastRowid;        /* Last rowid from a Next or NextIdx operation */

  /* Result of last sqlite3BtreeMoveto() done by an OP_NotExists or 
  ** OP_IsUnique opcode on this cursor. */
  int seekResult;

  /* Cached information about the header for the data record that the
  ** cursor is currently pointing to.  Only valid if cacheStatus matches
................................................................................
** A value for VdbeCursor.cacheValid that means the cache is always invalid.
*/
#define CACHE_STALE 0

/*
** Internally, the vdbe manipulates nearly all SQL values as Mem
** structures. Each Mem struct may cache multiple representations (string,
** integer etc.) of the same value.






*/
struct Mem {
  sqlite3 *db;        /* The associated database connection */
  char *z;            /* String or BLOB value */
  double r;           /* Real value */
  union {
    i64 i;              /* Integer value used when MEM_Int is set in flags */
    int nZero;          /* Used when bit MEM_Zero is set in flags */
    FuncDef *pDef;      /* Used only when flags==MEM_Agg */
    RowSet *pRowSet;    /* Used only when flags==MEM_RowSet */
    VdbeFrame *pFrame;  /* Used when flags==MEM_Frame */
  } u;



  int n;              /* Number of characters in string value, excluding '\0' */
  u16 flags;          /* Some combination of MEM_Null, MEM_Str, MEM_Dyn, etc. */
  u8  type;           /* One of SQLITE_NULL, SQLITE_TEXT, SQLITE_INTEGER, etc */
  u8  enc;            /* SQLITE_UTF8, SQLITE_UTF16BE, SQLITE_UTF16LE */
#ifdef SQLITE_DEBUG
  Mem *pScopyFrom;    /* This Mem is a shallow copy of pScopyFrom */
  void *pFiller;      /* So that sizeof(Mem) is a multiple of 8 */
................................................................................
** No other flags may be set in this case.
**
** If the MEM_Str flag is set then Mem.z points at a string representation.
** Usually this is encoded in the same unicode encoding as the main
** database (see below for exceptions). If the MEM_Term flag is also
** set, then the string is nul terminated. The MEM_Int and MEM_Real 
** flags may coexist with the MEM_Str flag.



*/
#define MEM_Null      0x0001   /* Value is NULL */
#define MEM_Str       0x0002   /* Value is a string */
#define MEM_Int       0x0004   /* Value is an integer */
#define MEM_Real      0x0008   /* Value is a real number */
#define MEM_Blob      0x0010   /* Value is a BLOB */
#define MEM_RowSet    0x0020   /* Value is a RowSet object */
................................................................................
  VdbeFunc *pVdbeFunc;  /* Auxilary data, if created. */
  Mem s;                /* The return value is stored here */
  Mem *pMem;            /* Memory cell used to store aggregate context */
  int isError;          /* Error code returned by the function. */
  CollSeq *pColl;       /* Collating sequence */
};













/*
** An instance of the virtual machine.  This structure contains the complete
** state of the virtual machine.
**
** The "sqlite3_stmt" structure pointer that is returned by sqlite3_prepare()
** is really a pointer to an instance of this structure.
**
** The Vdbe.inVtabMethod variable is set to non-zero for the duration of
** any virtual table method invocations made by the vdbe program. It is
** set to 2 for xDestroy method calls and 1 for all other methods. This
** variable is used for two purposes: to allow xDestroy methods to execute
** "DROP TABLE" statements and to prevent some nasty side effects of
** malloc failure when SQLite is invoked recursively by a virtual table 
** method function.
*/
struct Vdbe {
  sqlite3 *db;            /* The database connection that owns this statement */



  Op *aOp;                /* Space to hold the virtual machine's program */



  Mem *aMem;              /* The memory locations */
  Mem **apArg;            /* Arguments to currently executing user function */
  Mem *aColName;          /* Column names to return */
  Mem *pResultSet;        /* Pointer to an array of results */
  int nMem;               /* Number of memory locations currently allocated */
  int nOp;                /* Number of instructions in the program */
  int nOpAlloc;           /* Number of slots allocated for aOp[] */
  int nLabel;             /* Number of labels used */
  int nLabelAlloc;        /* Number of slots allocated in aLabel[] */
  int *aLabel;            /* Space to hold the labels */
  u16 nResColumn;         /* Number of columns in one row of the result set */
  u16 nCursor;            /* Number of slots in apCsr[] */
  u32 magic;              /* Magic number for sanity checking */
  char *zErrMsg;          /* Error message written here */
  Vdbe *pPrev,*pNext;     /* Linked list of VDBEs with the same Vdbe.db */
  VdbeCursor **apCsr;     /* One element of this array for each open cursor */



  Mem *aVar;              /* Values for the OP_Variable opcode. */
  char **azVar;           /* Name of variables */



  ynVar nVar;             /* Number of entries in aVar[] */
  u32 cacheCtr;           /* VdbeCursor row cache generation counter */
  int pc;                 /* The program counter */
  int rc;                 /* Value to return */
  u8 errorAction;         /* Recovery action to do in case of an error */
  u8 okVar;               /* True if azVar[] has been initialized */
  u8 explain;             /* True if EXPLAIN present on SQL command */
  u8 changeCntOn;         /* True to update the change-counter */
  u8 expired;             /* True if the VM needs to be recompiled */
  u8 runOnlyOnce;         /* Automatically expire on reset */
  u8 minWriteFileFormat;  /* Minimum file format for writable database files */
  u8 inVtabMethod;        /* See comments above */
  u8 usesStmtJournal;     /* True if uses a statement journal */
  u8 readOnly;            /* True for read-only statements */
  u8 isPrepareV2;         /* True if prepared with prepare_v2() */
  int nChange;            /* Number of db changes made since last reset */
  int btreeMask;          /* Bitmask of db->aDb[] entries referenced */
  int iStatement;         /* Statement number (or 0 if has not opened stmt) */

  int aCounter[3];        /* Counters used by sqlite3_stmt_status() */
  BtreeMutexArray aMutex; /* An array of Btree used here and needing locks */
#ifndef SQLITE_OMIT_TRACE
  i64 startTime;          /* Time when query started - used for profiling */
#endif
  i64 nFkConstraint;      /* Number of imm. FK constraints this VM */
  i64 nStmtDefCons;       /* Number of def. constraints when stmt started */

  char *zSql;             /* Text of the SQL statement that generated this */
  void *pFree;            /* Free this when deleting the vdbe */
#ifdef SQLITE_DEBUG
  FILE *trace;            /* Write an execution trace here, if not NULL */
#endif
  VdbeFrame *pFrame;      /* Parent frame */
  VdbeFrame *pDelFrame;   /* List of frame objects to free on VM reset */
  int nFrame;             /* Number of frames in pFrame list */
  u32 expmask;            /* Binding to these vars invalidates VM */

static int sqlite3Step(Vdbe *p){
  sqlite3 *db;
  int rc;

  assert(p);
  if( p->magic!=VDBE_MAGIC_RUN ){
    /* We used to require that sqlite3_reset() be called before retrying
    ** sqlite3_step() after any error.  But after 3.6.23, we changed this
    ** so that sqlite3_reset() would be called automatically instead of
    ** throwing the error.











    */


    sqlite3_reset((sqlite3_stmt*)p);






  }

  /* Check that malloc() has not failed. If it has, return early. */
  db = p->db;
  if( db->mallocFailed ){
    p->rc = SQLITE_NOMEM;
    return SQLITE_NOMEM;
................................................................................
    ** this assert() from failing, when building with SQLITE_DEBUG defined
    ** using gcc, force nullMem to be 8-byte aligned using the magical
    ** __attribute__((aligned(8))) macro.  */
    static const Mem nullMem 
#if defined(SQLITE_DEBUG) && defined(__GNUC__)
      __attribute__((aligned(8))) 
#endif
      = {{0}, (double)0, 0, "", 0, MEM_Null, SQLITE_NULL, 0, 0, 0 };

    if( pVm && ALWAYS(pVm->db) ){
      sqlite3_mutex_enter(pVm->db->mutex);
      sqlite3Error(pVm->db, SQLITE_RANGE, 0);
    }
    pOut = (Mem*)&nullMem;
  }

static int sqlite3Step(Vdbe *p){
  sqlite3 *db;
  int rc;

  assert(p);
  if( p->magic!=VDBE_MAGIC_RUN ){
    /* We used to require that sqlite3_reset() be called before retrying
    ** sqlite3_step() after any error or after SQLITE_DONE.  But beginning
    ** with version 3.7.0, we changed this so that sqlite3_reset() would
    ** be called automatically instead of throwing the SQLITE_MISUSE error.
    ** This "automatic-reset" change is not technically an incompatibility, 
    ** since any application that receives an SQLITE_MISUSE is broken by
    ** definition.
    **
    ** Nevertheless, some published applications that were originally written
    ** for version 3.6.23 or earlier do in fact depend on SQLITE_MISUSE 
    ** returns, and the so were broken by the automatic-reset change.  As a
    ** a work-around, the SQLITE_OMIT_AUTORESET compile-time restores the
    ** legacy behavior of returning SQLITE_MISUSE for cases where the 
    ** previous sqlite3_step() returned something other than a SQLITE_LOCKED
    ** or SQLITE_BUSY error.
    */
#ifdef SQLITE_OMIT_AUTORESET
    if( p->rc==SQLITE_BUSY || p->rc==SQLITE_LOCKED ){
      sqlite3_reset((sqlite3_stmt*)p);
    }else{
      return SQLITE_MISUSE_BKPT;
    }
#else
    sqlite3_reset((sqlite3_stmt*)p);
#endif
  }

  /* Check that malloc() has not failed. If it has, return early. */
  db = p->db;
  if( db->mallocFailed ){
    p->rc = SQLITE_NOMEM;
    return SQLITE_NOMEM;
................................................................................
    ** this assert() from failing, when building with SQLITE_DEBUG defined
    ** using gcc, force nullMem to be 8-byte aligned using the magical
    ** __attribute__((aligned(8))) macro.  */
    static const Mem nullMem 
#if defined(SQLITE_DEBUG) && defined(__GNUC__)
      __attribute__((aligned(8))) 
#endif
      = {0, "", (double)0, {0}, 0, MEM_Null, SQLITE_NULL, 0, 0, 0 };

    if( pVm && ALWAYS(pVm->db) ){
      sqlite3_mutex_enter(pVm->db->mutex);
      sqlite3Error(pVm->db, SQLITE_RANGE, 0);
    }
    pOut = (Mem*)&nullMem;
  }

} {SQLITE_DONE}
do_test capi2-1.7 {
  list [sqlite3_column_count $VM] [get_row_values $VM] [get_column_names $VM]
} {2 {} {name rowid text INTEGER}}

# This used to be SQLITE_MISUSE.  But now we automatically reset prepared
# statements.

do_test capi2-1.8 {
  sqlite3_step $VM
} {SQLITE_ROW}






# Update: In v2, once SQLITE_MISUSE is returned the statement handle cannot
# be interrogated for more information. However in v3, since the column
# count, names and types are determined at compile time, these are still
# accessible after an SQLITE_MISUSE error.
do_test capi2-1.9 {
  sqlite3_reset $VM

} {SQLITE_DONE}
do_test capi2-1.7 {
  list [sqlite3_column_count $VM] [get_row_values $VM] [get_column_names $VM]
} {2 {} {name rowid text INTEGER}}

# This used to be SQLITE_MISUSE.  But now we automatically reset prepared
# statements.
ifcapable autoreset {
  do_test capi2-1.8 {
    sqlite3_step $VM
  } {SQLITE_ROW}
} else {
  do_test capi2-1.8 {
    sqlite3_step $VM
  } {SQLITE_MISUSE}
}

# Update: In v2, once SQLITE_MISUSE is returned the statement handle cannot
# be interrogated for more information. However in v3, since the column
# count, names and types are determined at compile time, these are still
# accessible after an SQLITE_MISUSE error.
do_test capi2-1.9 {
  sqlite3_reset $VM

} {4}
do_test exclusive2-3.5 {
  execsql {
    PRAGMA locking_mode = normal;
    INSERT INTO t1 VALUES(randstr(10, 400));
  }
  readPagerChangeCounter test.db
} {4}
do_test exclusive2-3.6 {
  execsql {
    INSERT INTO t1 VALUES(randstr(10, 400));
  }
  readPagerChangeCounter test.db
} {5}
sqlite3_soft_heap_limit $cmdlinearg(soft-heap-limit)

finish_test

} {4}
do_test exclusive2-3.5 {
  execsql {
    PRAGMA locking_mode = normal;
    INSERT INTO t1 VALUES(randstr(10, 400));
  }
  readPagerChangeCounter test.db
} {5}
do_test exclusive2-3.6 {
  execsql {
    INSERT INTO t1 VALUES(randstr(10, 400));
  }
  readPagerChangeCounter test.db
} {6}
sqlite3_soft_heap_limit $cmdlinearg(soft-heap-limit)

finish_test

    INSERT INTO one VALUES(1, 2, 3);
  }
} {1}
do_test fkey2-17.1.2 {
  set STMT [sqlite3_prepare_v2 db "INSERT INTO two VALUES(4, 5, 6)" -1 dummy]
  sqlite3_step $STMT
} {SQLITE_CONSTRAINT}

do_test fkey2-17.1.3 {
  sqlite3_step $STMT
} {SQLITE_CONSTRAINT}





do_test fkey2-17.1.4 {
  sqlite3_finalize $STMT
} {SQLITE_CONSTRAINT}
do_test fkey2-17.1.5 {
  execsql {
    INSERT INTO one VALUES(2, 3, 4);
    INSERT INTO one VALUES(3, 4, 5);

    INSERT INTO one VALUES(1, 2, 3);
  }
} {1}
do_test fkey2-17.1.2 {
  set STMT [sqlite3_prepare_v2 db "INSERT INTO two VALUES(4, 5, 6)" -1 dummy]
  sqlite3_step $STMT
} {SQLITE_CONSTRAINT}
ifcapable autoreset {
  do_test fkey2-17.1.3 {
    sqlite3_step $STMT
  } {SQLITE_CONSTRAINT}
} else {
  do_test fkey2-17.1.3 {
    sqlite3_step $STMT
  } {SQLITE_MISUSE}
}
do_test fkey2-17.1.4 {
  sqlite3_finalize $STMT
} {SQLITE_CONSTRAINT}
do_test fkey2-17.1.5 {
  execsql {
    INSERT INTO one VALUES(2, 3, 4);
    INSERT INTO one VALUES(3, 4, 5);

  SELECT typeof(matchinfo(t10)), length(matchinfo(t10)) FROM t10 WHERE docid=1;
} {blob 0}
do_execsql_test 7.4 {
  SELECT typeof(matchinfo(t10)), length(matchinfo(t10)) 
  FROM t10 WHERE t10 MATCH 'record'
} {blob 20 blob 20}












































finish_test

  SELECT typeof(matchinfo(t10)), length(matchinfo(t10)) FROM t10 WHERE docid=1;
} {blob 0}
do_execsql_test 7.4 {
  SELECT typeof(matchinfo(t10)), length(matchinfo(t10)) 
  FROM t10 WHERE t10 MATCH 'record'
} {blob 20 blob 20}

#-------------------------------------------------------------------------
# Test a special case - matchinfo('nxa') with many zero length documents. 
# Special because "x" internally uses a statement used by both "n" and "a". 
# This was causing a problem at one point in the obscure case where the
# total number of bytes of data stored in an fts3 table was greater than
# the number of rows. i.e. when the following query returns true:
#
#   SELECT sum(length(content)) < count(*) FROM fts4table;
#
do_execsql_test 8.1 {
  CREATE VIRTUAL TABLE t11 USING fts4;
  INSERT INTO t11(t11) VALUES('nodesize=24');
  INSERT INTO t11 VALUES('quitealongstringoftext');
  INSERT INTO t11 VALUES('anotherquitealongstringoftext');
  INSERT INTO t11 VALUES('athirdlongstringoftext');
  INSERT INTO t11 VALUES('andonemoreforgoodluck');
}
do_test 8.2 {
  for {set i 0} {$i < 200} {incr i} {
    execsql { INSERT INTO t11 VALUES('') }
  }
  execsql { INSERT INTO t11(t11) VALUES('optimize') }
} {}
do_execsql_test 8.3 {
  SELECT mit(matchinfo(t11, 'nxa')) FROM t11 WHERE t11 MATCH 'a*'
} {{204 1 3 3 0} {204 1 3 3 0} {204 1 3 3 0}}

# Corruption related tests.
do_execsql_test  8.4.1.1 { UPDATE t11_stat SET value = X'0000'; }
do_catchsql_test 8.5.1.2 {
  SELECT mit(matchinfo(t11, 'nxa')) FROM t11 WHERE t11 MATCH 'a*'
} {1 {database disk image is malformed}}

do_execsql_test  8.4.2.1 { UPDATE t11_stat SET value = X'00'; }
do_catchsql_test 8.5.2.2 {
  SELECT mit(matchinfo(t11, 'nxa')) FROM t11 WHERE t11 MATCH 'a*'
} {1 {database disk image is malformed}}

do_execsql_test  8.4.3.1 { UPDATE t11_stat SET value = NULL; }
do_catchsql_test 8.5.3.2 {
  SELECT mit(matchinfo(t11, 'nxa')) FROM t11 WHERE t11 MATCH 'a*'
} {1 {database disk image is malformed}}

finish_test

do_test jrnlmode3-1.2 {
  db eval {
    BEGIN;
    INSERT INTO t1 VALUES(2);
    ROLLBACK;
    SELECT * FROM t1;
  }
} {1 2}

db close
file delete -force test.db test.db-journal
sqlite3 db test.db

do_test jrnlmode3-2.1 {
  db eval {
................................................................................
do_test jrnlmode3-2.2 {
  db eval {
    BEGIN;
    INSERT INTO t1 VALUES(2);
    ROLLBACK;
    SELECT * FROM t1;
  }
} {1 2}

# Test cases to verify that we can move from any journal_mode
# to any other, as long as we are not in a transaction.  Verify
# that we cannot change journal_mode while a transaction is active.
#
set all_journal_modes {delete persist truncate memory off}
set cnt 0
................................................................................
        CREATE TABLE t1(x);
        BEGIN;
        INSERT INTO t1 VALUES($cnt);
      }
      db eval "PRAGMA journal_mode=$tojmode"
    } $fromjmode

    # Rollback the transaction.  Verify that the rollback occurred
    # if journal_mode!=OFF.
    #
    do_test jrnlmode3-3.$cnt.4 {
      db eval {
        ROLLBACK;
        SELECT * FROM t1;
      }
    } [expr {$fromjmode=="off"?$cnt:""}]

    # Now change the journal mode again.  This time the new mode
    # should take.
    #
    do_test jrnlmode3-3.$cnt.5 {
      db eval "PRAGMA journal_mode=$tojmode"
    } $tojmode
................................................................................
        BEGIN;
        INSERT INTO t1 VALUES(1);
      }
      db eval ROLLBACK
      db eval {
        SELECT * FROM t1;
      }
    } [expr {$tojmode=="off"?"1":""}]
  }
}

finish_test

do_test jrnlmode3-1.2 {
  db eval {
    BEGIN;
    INSERT INTO t1 VALUES(2);
    ROLLBACK;
    SELECT * FROM t1;
  }
} {1}

db close
file delete -force test.db test.db-journal
sqlite3 db test.db

do_test jrnlmode3-2.1 {
  db eval {
................................................................................
do_test jrnlmode3-2.2 {
  db eval {
    BEGIN;
    INSERT INTO t1 VALUES(2);
    ROLLBACK;
    SELECT * FROM t1;
  }
} {1}

# Test cases to verify that we can move from any journal_mode
# to any other, as long as we are not in a transaction.  Verify
# that we cannot change journal_mode while a transaction is active.
#
set all_journal_modes {delete persist truncate memory off}
set cnt 0
................................................................................
        CREATE TABLE t1(x);
        BEGIN;
        INSERT INTO t1 VALUES($cnt);
      }
      db eval "PRAGMA journal_mode=$tojmode"
    } $fromjmode

    # Rollback the transaction.  

    #
    do_test jrnlmode3-3.$cnt.4 {
      db eval {
        ROLLBACK;
        SELECT * FROM t1;
      }
    } {}

    # Now change the journal mode again.  This time the new mode
    # should take.
    #
    do_test jrnlmode3-3.$cnt.5 {
      db eval "PRAGMA journal_mode=$tojmode"
    } $tojmode
................................................................................
        BEGIN;
        INSERT INTO t1 VALUES(1);
      }
      db eval ROLLBACK
      db eval {
        SELECT * FROM t1;
      }
    } {}
  }
}

finish_test

db close
sqlite3_shutdown
sqlite3_config_pagecache [expr 1024+$xtra_size] 20
sqlite3_initialize
reset_highwater_marks
build_test_db memsubsys1-2 {PRAGMA page_size=1024}
#show_memstats

do_test memsubsys1-2.3 {
  set pg_ovfl [lindex [sqlite3_status SQLITE_STATUS_PAGECACHE_OVERFLOW 0] 2]
} [expr ($AUTOVACUUM+$TEMP_STORE>=2)*1024]
do_test memsubsys1-2.4 {
  set pg_used [lindex [sqlite3_status SQLITE_STATUS_PAGECACHE_USED 0] 2]
} 20
do_test memsubsys1-2.5 {
  set s_used [lindex [sqlite3_status SQLITE_STATUS_SCRATCH_USED 0] 2]
} 0

db close
sqlite3_shutdown
sqlite3_config_pagecache [expr 1024+$xtra_size] 20
sqlite3_initialize
reset_highwater_marks
build_test_db memsubsys1-2 {PRAGMA page_size=1024}
#show_memstats
set MEMORY_MANAGEMENT $sqlite_options(memorymanage)
do_test memsubsys1-2.3 {
  set pg_ovfl [lindex [sqlite3_status SQLITE_STATUS_PAGECACHE_OVERFLOW 0] 2]
} [expr ($AUTOVACUUM+$TEMP_STORE+$MEMORY_MANAGEMENT>=3)*1024]
do_test memsubsys1-2.4 {
  set pg_used [lindex [sqlite3_status SQLITE_STATUS_PAGECACHE_USED 0] 2]
} 20
do_test memsubsys1-2.5 {
  set s_used [lindex [sqlite3_status SQLITE_STATUS_SCRATCH_USED 0] 2]
} 0

      clear_mutex_counters
      sqlite3 db test.db -nomutex 0 -fullmutex 0
      catchsql { CREATE TABLE abc(a, b, c) }
      db eval {
        INSERT INTO abc VALUES(1, 2, 3);
      }
    } {}


  
    do_test mutex1.2.$mode.3 {
      mutex_counters counters
  
      set res [list]
      foreach {key value} [array get counters] {
        if {$key ne "total" && $value > 0} {
          lappend res $key

      clear_mutex_counters
      sqlite3 db test.db -nomutex 0 -fullmutex 0
      catchsql { CREATE TABLE abc(a, b, c) }
      db eval {
        INSERT INTO abc VALUES(1, 2, 3);
      }
    } {}
    ifcapable !memorymanage {
      regsub { static_lru} $mutexes {} mutexes
    }
    do_test mutex1.2.$mode.3 {
      mutex_counters counters
  
      set res [list]
      foreach {key value} [array get counters] {
        if {$key ne "total" && $value > 0} {
          lappend res $key

do_catchsql_test pager1-14.1.2 {
  BEGIN;
    INSERT INTO t1 VALUES(3, 4);
  ROLLBACK;
} {0 {}}
do_execsql_test pager1-14.1.3 {
  SELECT * FROM t1;
} {1 2 3 4}
do_catchsql_test pager1-14.1.4 {
  BEGIN;
    INSERT INTO t1(rowid, a, b) SELECT a+3, b, b FROM t1;
    INSERT INTO t1(rowid, a, b) SELECT a+3, b, b FROM t1;
} {1 {PRIMARY KEY must be unique}}
do_execsql_test pager1-14.1.5 {
  COMMIT;
  SELECT * FROM t1;
} {1 2 3 4 2 2 4 4}

#-------------------------------------------------------------------------
# Test opening and closing the pager sub-system with different values
# for the sqlite3_vfs.szOsFile variable.
#
faultsim_delete_and_reopen
do_execsql_test pager1-15.0 {

do_catchsql_test pager1-14.1.2 {
  BEGIN;
    INSERT INTO t1 VALUES(3, 4);
  ROLLBACK;
} {0 {}}
do_execsql_test pager1-14.1.3 {
  SELECT * FROM t1;
} {1 2}
do_catchsql_test pager1-14.1.4 {
  BEGIN;
    INSERT INTO t1(rowid, a, b) SELECT a+3, b, b FROM t1;
    INSERT INTO t1(rowid, a, b) SELECT a+3, b, b FROM t1;
} {1 {PRIMARY KEY must be unique}}
do_execsql_test pager1-14.1.5 {
  COMMIT;
  SELECT * FROM t1;
} {1 2 2 2}

#-------------------------------------------------------------------------
# Test opening and closing the pager sub-system with different values
# for the sqlite3_vfs.szOsFile variable.
#
faultsim_delete_and_reopen
do_execsql_test pager1-15.0 {

    CREATE TABLE t1(a, b);
    PRAGMA journal_mode = off;
    BEGIN;
      INSERT INTO t1 VALUES(1, 2);
    ROLLBACK;
    SELECT * FROM t1;
  }
} {off 1 2}
do_test pager2-2.2 {
  faultsim_delete_and_reopen
  execsql {
    PRAGMA auto_vacuum = incremental;
    PRAGMA page_size = 1024;
    PRAGMA journal_mode = off;
    CREATE TABLE t1(a, b);

    CREATE TABLE t1(a, b);
    PRAGMA journal_mode = off;
    BEGIN;
      INSERT INTO t1 VALUES(1, 2);
    ROLLBACK;
    SELECT * FROM t1;
  }
} {off}
do_test pager2-2.2 {
  faultsim_delete_and_reopen
  execsql {
    PRAGMA auto_vacuum = incremental;
    PRAGMA page_size = 1024;
    PRAGMA journal_mode = off;
    CREATE TABLE t1(a, b);

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

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









# The pcache module limits the number of pages available to purgeable
# caches to the sum of the 'cache_size' values for the set of open
# caches. This block of tests, pcache-1.*, test that the library behaves
# corrctly when it is forced to exceed this limit.
#
do_test pcache-1.1 {

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

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

# Only works with a mode-2 pcache where all pcaches share a single set
# of pages.
#
ifcapable {!memorymanage && threadsafe} {
  finish_test
  return
}

# The pcache module limits the number of pages available to purgeable
# caches to the sum of the 'cache_size' values for the set of open
# caches. This block of tests, pcache-1.*, test that the library behaves
# corrctly when it is forced to exceed this limit.
#
do_test pcache-1.1 {

        INSERT INTO t1 VALUES(13, 14);
        SAVEPOINT s1;
          INSERT INTO t1 VALUES(15, 16);
        ROLLBACK TO s1;
      ROLLBACK;
      SELECT * FROM t1;
    }
  } {1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16}
}

db close
file delete test.db
do_multiclient_test tn {
  do_test savepoint-14.$tn.1 {
    sql1 {

        INSERT INTO t1 VALUES(13, 14);
        SAVEPOINT s1;
          INSERT INTO t1 VALUES(15, 16);
        ROLLBACK TO s1;
      ROLLBACK;
      SELECT * FROM t1;
    }
  } {1 2 3 4 5 6 7 8 9 10 11 12}
}

db close
file delete test.db
do_multiclient_test tn {
  do_test savepoint-14.$tn.1 {
    sql1 {

# 2011 January 15
#
# The author disclaims copyright to this source code.  In place of
# a legal notice, here is a blessing:
#
#    May you do good and not evil.
#    May you find forgiveness for yourself and forgive others.
#    May you share freely, never taking more than you give.
#
#***********************************************************************
# This file implements regression tests for SQLite library.
#
# This file implements tests to verify that ticket [5d863f876e] has been
# fixed.  
#

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

do_multiclient_test tn {
  do_test $tn.1 {
    sql1 {
      CREATE TABLE t1(a, b);
      CREATE INDEX i1 ON t1(a, b);
      INSERT INTO t1 VALUES(1, 2);
      INSERT INTO t1 VALUES(3, 4);
      PRAGMA journal_mode = WAL;
      VACUUM;
      PRAGMA journal_mode = DELETE;
    }
  } {wal delete}

  do_test $tn.2 {
    sql2 { SELECT * FROM t1 } 
  } {1 2 3 4}

  do_test $tn.3 {
    sql1 {
      INSERT INTO t1 VALUES(5, 6);
      PRAGMA journal_mode = WAL;
      VACUUM;
      PRAGMA journal_mode = DELETE;
    }
  } {wal delete}

  do_test $tn.2 {
    sql2 { PRAGMA integrity_check }
  } {ok}
}


finish_test

# Get the fossil-scm check-in date from the "D" card of $TOP/manifest.
#
set in [open $TOP/manifest]
set zDate {}
while {![eof $in]} {
  set line [gets $in]
  if {[regexp {^D (2.*[0-9])} $line all date]} {
    set zDate [string map {T { }} $date]
    break
  }
}
close $in

# Set up patterns for recognizing API declarations.

# Get the fossil-scm check-in date from the "D" card of $TOP/manifest.
#
set in [open $TOP/manifest]
set zDate {}
while {![eof $in]} {
  set line [gets $in]
  if {[regexp {^D (2[-0-9T:]+)} $line all date]} {
    set zDate [string map {T { }} $date]
    break
  }
}
close $in

# Set up patterns for recognizing API declarations.

  list $rc \
       [regexp {Error: missing argument for option: -nullvalue} $res]
} {1 1}

# -version             show SQLite version
do_test shell1-1.16.1 {
  catchcmd "-version test.db" "" 
} {0 3.7.3}

#----------------------------------------------------------------------------
# Test cases shell1-2.*: Basic "dot" command token parsing.
#

# check first token handling
do_test shell1-2.1.1 {

  list $rc \
       [regexp {Error: missing argument for option: -nullvalue} $res]
} {1 1}

# -version             show SQLite version
do_test shell1-1.16.1 {
  catchcmd "-version test.db" "" 
} {0 3.7.5}

#----------------------------------------------------------------------------
# Test cases shell1-2.*: Basic "dot" command token parsing.
#

# check first token handling
do_test shell1-2.1.1 {

** Read content from the file.
**
** Space to hold the content is obtained from malloc() and needs to be
** freed by the caller.
*/
static unsigned char *getContent(int ofst, int nByte){
  unsigned char *aData;
  aData = malloc(nByte);
  if( aData==0 ) out_of_memory();

  lseek(db, ofst, SEEK_SET);
  read(db, aData, nByte);
  return aData;
}

/*
** Print a range of bytes as hex and as ascii.
................................................................................
  print_decode_line(aData, 80, 4, "meta[10]");
  print_decode_line(aData, 84, 4, "meta[11]");
  print_decode_line(aData, 88, 4, "meta[12]");
  print_decode_line(aData, 92, 4, "Change counter for version number");
  print_decode_line(aData, 96, 4, "SQLite version number");
}

/*
































































































** Create a description for a single cell.


*/
static int describeCell(unsigned char cType, unsigned char *a, char **pzDesc){





  int i;
  int nDesc = 0;
  int n = 0;
  int leftChild;
  i64 nPayload;
  i64 rowid;

  static char zDesc[100];
  i = 0;
  if( cType<=5 ){
    leftChild = ((a[0]*256 + a[1])*256 + a[2])*256 + a[3];
    a += 4;
    n += 4;
    sprintf(zDesc, "left-child: %d ", leftChild);
    nDesc = strlen(zDesc);
  }
  if( cType!=5 ){
    i = decodeVarint(a, &nPayload);
    a += i;
    n += i;
    sprintf(&zDesc[nDesc], "sz: %lld ", nPayload);
    nDesc += strlen(&zDesc[nDesc]);



  }
  if( cType==5 || cType==13 ){
    i = decodeVarint(a, &rowid);
    a += i;
    n += i;
    sprintf(&zDesc[nDesc], "rowid: %lld ", rowid);
    nDesc += strlen(&zDesc[nDesc]);
  }











  *pzDesc = zDesc;
  return n;
}

/*
** Decode a btree page
*/
static void decode_btree_page(unsigned char *a, int pgno, int hdrSize){





  const char *zType = "unknown";
  int nCell;
  int i;
  int iCellPtr;



  switch( a[0] ){
    case 2:  zType = "index interior node";  break;
    case 5:  zType = "table interior node";  break;
    case 10: zType = "index leaf";           break;
    case 13: zType = "table leaf";           break;







  }
  printf("Decode of btree page %d:\n", pgno);
  print_decode_line(a, 0, 1, zType);
  print_decode_line(a, 1, 2, "Offset to first freeblock");
  print_decode_line(a, 3, 2, "Number of cells on this page");
  nCell = a[3]*256 + a[4];
  print_decode_line(a, 5, 2, "Offset to cell content area");
................................................................................
  print_decode_line(a, 7, 1, "Fragmented byte count");
  if( a[0]==2 || a[0]==5 ){
    print_decode_line(a, 8, 4, "Right child");
    iCellPtr = 12;
  }else{
    iCellPtr = 8;
  }










  for(i=0; i<nCell; i++){
    int cofst = iCellPtr + i*2;
    char *zDesc;


    cofst = a[cofst]*256 + a[cofst+1];
    describeCell(a[0], &a[cofst-hdrSize], &zDesc);









    printf(" %03x: cell[%d] %s\n", cofst, i, zDesc);
  }






}

/*
** Decode a freelist trunk page.
*/
static void decode_trunk_page(
  int pgno,             /* The page number */
................................................................................
  fprintf(stderr, "Usage %s FILENAME ?args...?\n\n", argv0);
  fprintf(stderr,
    "args:\n"
    "    dbheader        Show database header\n"
    "    NNN..MMM        Show hex of pages NNN through MMM\n"
    "    NNN..end        Show hex of pages NNN through end of file\n"
    "    NNNb            Decode btree page NNN\n"


    "    NNNt            Decode freelist trunk page NNN\n"
    "    NNNtd           Show leave freelist pages on the decode\n"
    "    NNNtr           Recurisvely decode freelist starting at NNN\n"
  );
}

int main(int argc, char **argv){
................................................................................
          nByte = pagesize-100;
        }else{
          hdrSize = 0;
          ofst = (iStart-1)*pagesize;
          nByte = pagesize;
        }
        a = getContent(ofst, nByte);
        decode_btree_page(a, iStart, hdrSize);
        free(a);
        continue;
      }else if( zLeft && zLeft[0]=='t' ){
        unsigned char *a;
        int detail = 0;
        int recursive = 0;
        int i;

** Read content from the file.
**
** Space to hold the content is obtained from malloc() and needs to be
** freed by the caller.
*/
static unsigned char *getContent(int ofst, int nByte){
  unsigned char *aData;
  aData = malloc(nByte+32);
  if( aData==0 ) out_of_memory();
  memset(aData, 0, nByte+32);
  lseek(db, ofst, SEEK_SET);
  read(db, aData, nByte);
  return aData;
}

/*
** Print a range of bytes as hex and as ascii.
................................................................................
  print_decode_line(aData, 80, 4, "meta[10]");
  print_decode_line(aData, 84, 4, "meta[11]");
  print_decode_line(aData, 88, 4, "meta[12]");
  print_decode_line(aData, 92, 4, "Change counter for version number");
  print_decode_line(aData, 96, 4, "SQLite version number");
}

/*
** Describe cell content.
*/
static int describeContent(
  unsigned char *a,       /* Cell content */
  int nLocal,             /* Bytes in a[] */
  char *zDesc             /* Write description here */
){
  int nDesc = 0;
  int n, i, j;
  i64 x, v;
  const unsigned char *pData;
  const unsigned char *pLimit;
  char sep = ' ';

  pLimit = &a[nLocal];
  n = decodeVarint(a, &x);
  pData = &a[x];
  a += n;
  i = x - n;
  while( i>0 && pData<=pLimit ){
    n = decodeVarint(a, &x);
    a += n;
    i -= n;
    nLocal -= n;
    zDesc[0] = sep;
    sep = ',';
    nDesc++;
    zDesc++;
    if( x==0 ){
      sprintf(zDesc, "*");     /* NULL is a "*" */
    }else if( x>=1 && x<=6 ){
      v = (signed char)pData[0];
      pData++;
      switch( x ){
        case 6:  v = (v<<16) + (pData[0]<<8) + pData[1];  pData += 2;
        case 5:  v = (v<<16) + (pData[0]<<8) + pData[1];  pData += 2;
        case 4:  v = (v<<8) + pData[0];  pData++;
        case 3:  v = (v<<8) + pData[0];  pData++;
        case 2:  v = (v<<8) + pData[0];  pData++;
      }
      sprintf(zDesc, "%lld", v);
    }else if( x==7 ){
      sprintf(zDesc, "real");
      pData += 8;
    }else if( x==8 ){
      sprintf(zDesc, "0");
    }else if( x==9 ){
      sprintf(zDesc, "1");
    }else if( x>=12 ){
      int size = (x-12)/2;
      if( (x&1)==0 ){
        sprintf(zDesc, "blob(%d)", size);
      }else{
        sprintf(zDesc, "txt(%d)", size);
      }
      pData += size;
    }
    j = strlen(zDesc);
    zDesc += j;
    nDesc += j;
  }
  return nDesc;
}

/*
** Compute the local payload size given the total payload size and
** the page size.
*/
static int localPayload(i64 nPayload, char cType){
  int maxLocal;
  int minLocal;
  int surplus;
  int nLocal;
  if( cType==13 ){
    /* Table leaf */
    maxLocal = pagesize-35;
    minLocal = (pagesize-12)*32/255-23;
  }else{
    maxLocal = (pagesize-12)*64/255-23;
    minLocal = (pagesize-12)*32/255-23;
  }
  if( nPayload>maxLocal ){
    surplus = minLocal + (nPayload-minLocal)%(pagesize-4);
    if( surplus<=maxLocal ){
      nLocal = surplus;
    }else{
      nLocal = minLocal;
    }
  }else{
    nLocal = nPayload;
  }
  return nLocal;
}
  

/*
** Create a description for a single cell.
**
** The return value is the local cell size.
*/
static int describeCell(
  unsigned char cType,    /* Page type */
  unsigned char *a,       /* Cell content */
  int showCellContent,    /* Show cell content if true */
  char **pzDesc           /* Store description here */
){
  int i;
  int nDesc = 0;
  int n = 0;
  int leftChild;
  i64 nPayload;
  i64 rowid;
  int nLocal;
  static char zDesc[1000];
  i = 0;
  if( cType<=5 ){
    leftChild = ((a[0]*256 + a[1])*256 + a[2])*256 + a[3];
    a += 4;
    n += 4;
    sprintf(zDesc, "lx: %d ", leftChild);
    nDesc = strlen(zDesc);
  }
  if( cType!=5 ){
    i = decodeVarint(a, &nPayload);
    a += i;
    n += i;
    sprintf(&zDesc[nDesc], "n: %lld ", nPayload);
    nDesc += strlen(&zDesc[nDesc]);
    nLocal = localPayload(nPayload, cType);
  }else{
    nPayload = nLocal = 0;
  }
  if( cType==5 || cType==13 ){
    i = decodeVarint(a, &rowid);
    a += i;
    n += i;
    sprintf(&zDesc[nDesc], "r: %lld ", rowid);
    nDesc += strlen(&zDesc[nDesc]);
  }
  if( nLocal<nPayload ){
    int ovfl;
    unsigned char *b = &a[nLocal];
    ovfl = ((b[0]*256 + b[1])*256 + b[2])*256 + b[3];
    sprintf(&zDesc[nDesc], "ov: %d ", ovfl);
    nDesc += strlen(&zDesc[nDesc]);
    n += 4;
  }
  if( showCellContent && cType!=5 ){
    nDesc += describeContent(a, nLocal, &zDesc[nDesc-1]);
  }
  *pzDesc = zDesc;
  return nLocal+n;
}

/*
** Decode a btree page
*/
static void decode_btree_page(
  unsigned char *a,   /* Page content */
  int pgno,           /* Page number */
  int hdrSize,        /* Size of the page header.  0 or 100 */
  char *zArgs         /* Flags to control formatting */
){
  const char *zType = "unknown";
  int nCell;
  int i, j;
  int iCellPtr;
  int showCellContent = 0;
  int showMap = 0;
  char *zMap = 0;
  switch( a[0] ){
    case 2:  zType = "index interior node";  break;
    case 5:  zType = "table interior node";  break;
    case 10: zType = "index leaf";           break;
    case 13: zType = "table leaf";           break;
  }
  while( zArgs[0] ){
    switch( zArgs[0] ){
      case 'c': showCellContent = 1;  break;
      case 'm': showMap = 1;          break;
    }
    zArgs++;
  }
  printf("Decode of btree page %d:\n", pgno);
  print_decode_line(a, 0, 1, zType);
  print_decode_line(a, 1, 2, "Offset to first freeblock");
  print_decode_line(a, 3, 2, "Number of cells on this page");
  nCell = a[3]*256 + a[4];
  print_decode_line(a, 5, 2, "Offset to cell content area");
................................................................................
  print_decode_line(a, 7, 1, "Fragmented byte count");
  if( a[0]==2 || a[0]==5 ){
    print_decode_line(a, 8, 4, "Right child");
    iCellPtr = 12;
  }else{
    iCellPtr = 8;
  }
  if( nCell>0 ){
    printf(" key: lx=left-child n=payload-size r=rowid\n");
  }
  if( showMap ){
    zMap = malloc(pagesize);
    memset(zMap, '.', pagesize);
    memset(zMap, '1', hdrSize);
    memset(&zMap[hdrSize], 'H', iCellPtr);
    memset(&zMap[hdrSize+iCellPtr], 'P', 2*nCell);
  }
  for(i=0; i<nCell; i++){
    int cofst = iCellPtr + i*2;
    char *zDesc;
    int n;

    cofst = a[cofst]*256 + a[cofst+1];
    n = describeCell(a[0], &a[cofst-hdrSize], showCellContent, &zDesc);
    if( showMap ){
      char zBuf[30];
      memset(&zMap[cofst], '*', n);
      zMap[cofst] = '[';
      zMap[cofst+n-1] = ']';
      sprintf(zBuf, "%d", i);
      j = strlen(zBuf);
      if( j<=n-2 ) memcpy(&zMap[cofst+1], zBuf, j);
    }
    printf(" %03x: cell[%d] %s\n", cofst, i, zDesc);
  }
  if( showMap ){
    for(i=0; i<pagesize; i+=64){
      printf(" %03x: %.64s\n", i, &zMap[i]);
    }
    free(zMap);
  }  
}

/*
** Decode a freelist trunk page.
*/
static void decode_trunk_page(
  int pgno,             /* The page number */
................................................................................
  fprintf(stderr, "Usage %s FILENAME ?args...?\n\n", argv0);
  fprintf(stderr,
    "args:\n"
    "    dbheader        Show database header\n"
    "    NNN..MMM        Show hex of pages NNN through MMM\n"
    "    NNN..end        Show hex of pages NNN through end of file\n"
    "    NNNb            Decode btree page NNN\n"
    "    NNNbc           Decode btree page NNN and show content\n"
    "    NNNbm           Decode btree page NNN and show a layout map\n"
    "    NNNt            Decode freelist trunk page NNN\n"
    "    NNNtd           Show leave freelist pages on the decode\n"
    "    NNNtr           Recurisvely decode freelist starting at NNN\n"
  );
}

int main(int argc, char **argv){
................................................................................
          nByte = pagesize-100;
        }else{
          hdrSize = 0;
          ofst = (iStart-1)*pagesize;
          nByte = pagesize;
        }
        a = getContent(ofst, nByte);
        decode_btree_page(a, iStart, hdrSize, &zLeft[1]);
        free(a);
        continue;
      }else if( zLeft && zLeft[0]=='t' ){
        unsigned char *a;
        int detail = 0;
        int recursive = 0;
        int i;