** 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.
**
*************************************************************************
** $Id: btree.c,v 1.191 2004/09/27 13:19:52 drh Exp $
**
** This file implements a external (disk-based) database using BTrees.
** For a detailed discussion of BTrees, refer to
**
**     Donald E. Knuth, THE ART OF COMPUTER PROGRAMMING, Volume 3:
**     "Sorting And Searching", pages 473-480. Addison-Wesley
**     Publishing Company, Reading, Massachusetts.
................................................................................
  zeroPage(pP1, PTF_INTKEY|PTF_LEAF|PTF_LEAFDATA );
  pBt->pageSizeFixed = 1;
  return SQLITE_OK;
}

/*
** Attempt to start a new transaction. A write-transaction
** is started if the second argument is true, otherwise a read-
** transaction.




**
** A write-transaction must be started before attempting any 
** changes to the database.  None of the following routines 
** will work unless a transaction is started first:
**
**      sqlite3BtreeCreateTable()
**      sqlite3BtreeCreateIndex()
................................................................................
  }

  if( pBt->pPage1==0 ){
    rc = lockBtree(pBt);
  }

  if( rc==SQLITE_OK && wrflag ){
    rc = sqlite3pager_begin(pBt->pPage1->aData);
    if( rc==SQLITE_OK ){
      rc = newDatabase(pBt);
    }
  }

  if( rc==SQLITE_OK ){
    pBt->inTrans = (wrflag?TRANS_WRITE:TRANS_READ);

** 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.
**
*************************************************************************
** $Id: btree.c,v 1.192 2004/10/05 02:41:42 drh Exp $
**
** This file implements a external (disk-based) database using BTrees.
** For a detailed discussion of BTrees, refer to
**
**     Donald E. Knuth, THE ART OF COMPUTER PROGRAMMING, Volume 3:
**     "Sorting And Searching", pages 473-480. Addison-Wesley
**     Publishing Company, Reading, Massachusetts.
................................................................................
  zeroPage(pP1, PTF_INTKEY|PTF_LEAF|PTF_LEAFDATA );
  pBt->pageSizeFixed = 1;
  return SQLITE_OK;
}

/*
** Attempt to start a new transaction. A write-transaction
** is started if the second argument is nonzero, otherwise a read-
** transaction.  If the second argument is 2 or more and exclusive
** transaction is started, meaning that no other process is allowed
** to access the database.  A preexisting transaction may not be
** upgrade to exclusive by calling this routine a second time - the
** exclusivity flag only works for a new transaction.
**
** A write-transaction must be started before attempting any 
** changes to the database.  None of the following routines 
** will work unless a transaction is started first:
**
**      sqlite3BtreeCreateTable()
**      sqlite3BtreeCreateIndex()
................................................................................
  }

  if( pBt->pPage1==0 ){
    rc = lockBtree(pBt);
  }

  if( rc==SQLITE_OK && wrflag ){
    rc = sqlite3pager_begin(pBt->pPage1->aData, wrflag>1);
    if( rc==SQLITE_OK ){
      rc = newDatabase(pBt);
    }
  }

  if( rc==SQLITE_OK ){
    pBt->inTrans = (wrflag?TRANS_WRITE:TRANS_READ);

**     DROP INDEX
**     creating ID lists
**     BEGIN TRANSACTION
**     COMMIT
**     ROLLBACK
**     PRAGMA
**
** $Id: build.c,v 1.255 2004/09/30 14:22:47 drh Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>

/*
** This routine is called when a new SQL statement is beginning to
** be parsed.  Check to see if the schema for the database needs
................................................................................
    }
    sqlite3VdbeOp3(v, OP_MakeRecord, 5, 0, "tttit", P3_STATIC);
    sqlite3VdbeAddOp(v, OP_PutIntKey, 0, 0);
    sqlite3ChangeCookie(db, v, p->iDb);
    sqlite3VdbeAddOp(v, OP_Close, 0, 0);
    sqlite3VdbeOp3(v, OP_ParseSchema, p->iDb, 0,
        sqlite3MPrintf("tbl_name='%q'",p->zName), P3_DYNAMIC);

    sqlite3EndWriteOperation(pParse);
  }

  /* Add the table to the in-memory representation of the database.
  */
  if( db->init.busy && pParse->nErr==0 ){
    Table *pOld;
    FKey *pFKey; 
................................................................................
    if( !isView ){
      sqlite3VdbeAddOp(v, OP_Destroy, pTab->tnum, pTab->iDb);
      for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
        sqlite3VdbeAddOp(v, OP_Destroy, pIdx->tnum, pIdx->iDb);
      }
    }
    sqlite3VdbeOp3(v, OP_DropTable, pTab->iDb, 0, pTab->zName, 0);
    sqlite3EndWriteOperation(pParse);
  }
  sqliteViewResetAll(db, iDb);

exit_drop_table:
  sqlite3SrcListDelete(pName);
}

................................................................................
                      "indexed columns are not unique", P3_STATIC);
      sqlite3VdbeAddOp(v, OP_Next, 2, lbl1);
      sqlite3VdbeResolveLabel(v, lbl2);
      sqlite3VdbeAddOp(v, OP_Close, 2, 0);
      sqlite3VdbeAddOp(v, OP_Close, 1, 0);
      sqlite3ChangeCookie(db, v, iDb);
      sqlite3VdbeAddOp(v, OP_Close, 0, 0);
      sqlite3EndWriteOperation(pParse);
      sqlite3VdbeOp3(v, OP_ParseSchema, iDb, 0,
         sqlite3MPrintf("name='%q'", pIndex->zName), P3_DYNAMIC);
    }
  }

  /* When adding an index to the list of indices for a table, make
  ** sure all indices labeled OE_Replace come after all those labeled
................................................................................
    sqlite3OpenMasterTable(v, pIndex->iDb);
    base = sqlite3VdbeAddOpList(v, ArraySize(dropIndex), dropIndex);
    sqlite3VdbeChangeP3(v, base+1, pIndex->zName, 0);
    sqlite3ChangeCookie(db, v, pIndex->iDb);
    sqlite3VdbeAddOp(v, OP_Close, 0, 0);
    sqlite3VdbeAddOp(v, OP_Destroy, pIndex->tnum, pIndex->iDb);
    sqlite3VdbeOp3(v, OP_DropIndex, pIndex->iDb, 0, pIndex->zName, 0);
    sqlite3EndWriteOperation(pParse);
  }

exit_drop_index:
  sqlite3SrcListDelete(pName);
}

/*
................................................................................
  }
  sqliteFree(pList);
}

/*
** Begin a transaction
*/
void sqlite3BeginTransaction(Parse *pParse){
  sqlite3 *db;
  Vdbe *v;


  if( pParse==0 || (db=pParse->db)==0 || db->aDb[0].pBt==0 ) return;
  if( pParse->nErr || sqlite3_malloc_failed ) return;
  if( sqlite3AuthCheck(pParse, SQLITE_TRANSACTION, "BEGIN", 0, 0) ) return;

  v = sqlite3GetVdbe(pParse);
  if( !v ) return;





  sqlite3VdbeAddOp(v, OP_AutoCommit, 0, 0);
}

/*
** Commit a transaction
*/
void sqlite3CommitTransaction(Parse *pParse){
................................................................................
    sqlite3VdbeAddOp(v, OP_Statement, iDb, 0);
  }
  if( iDb!=1 && pParse->db->aDb[1].pBt!=0 ){
    sqlite3BeginWriteOperation(pParse, setStatement, 1);
  }
}

/*
** Generate code that concludes an operation that may have changed
** the database.  If a statement transaction was started, then emit
** an OP_Commit that will cause the changes to be committed to disk.
**
** Note that checkpoints are automatically committed at the end of
** a statement.  Note also that there can be multiple calls to 
** sqlite3BeginWriteOperation() but there should only be a single
** call to sqlite3EndWriteOperation() at the conclusion of the statement.
*/
void sqlite3EndWriteOperation(Parse *pParse){
  /* Delete me! */
  return;
}

/* 
** Return the transient sqlite3_value object used for encoding conversions
** during SQL compilation.
*/
sqlite3_value *sqlite3GetTransientValue(sqlite3 *db){
  if( !db->pValue ){
    db->pValue = sqlite3ValueNew();
  }
  return db->pValue;
}

**     DROP INDEX
**     creating ID lists
**     BEGIN TRANSACTION
**     COMMIT
**     ROLLBACK
**     PRAGMA
**
** $Id: build.c,v 1.256 2004/10/05 02:41:42 drh Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>

/*
** This routine is called when a new SQL statement is beginning to
** be parsed.  Check to see if the schema for the database needs
................................................................................
    }
    sqlite3VdbeOp3(v, OP_MakeRecord, 5, 0, "tttit", P3_STATIC);
    sqlite3VdbeAddOp(v, OP_PutIntKey, 0, 0);
    sqlite3ChangeCookie(db, v, p->iDb);
    sqlite3VdbeAddOp(v, OP_Close, 0, 0);
    sqlite3VdbeOp3(v, OP_ParseSchema, p->iDb, 0,
        sqlite3MPrintf("tbl_name='%q'",p->zName), P3_DYNAMIC);


  }

  /* Add the table to the in-memory representation of the database.
  */
  if( db->init.busy && pParse->nErr==0 ){
    Table *pOld;
    FKey *pFKey; 
................................................................................
    if( !isView ){
      sqlite3VdbeAddOp(v, OP_Destroy, pTab->tnum, pTab->iDb);
      for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
        sqlite3VdbeAddOp(v, OP_Destroy, pIdx->tnum, pIdx->iDb);
      }
    }
    sqlite3VdbeOp3(v, OP_DropTable, pTab->iDb, 0, pTab->zName, 0);

  }
  sqliteViewResetAll(db, iDb);

exit_drop_table:
  sqlite3SrcListDelete(pName);
}

................................................................................
                      "indexed columns are not unique", P3_STATIC);
      sqlite3VdbeAddOp(v, OP_Next, 2, lbl1);
      sqlite3VdbeResolveLabel(v, lbl2);
      sqlite3VdbeAddOp(v, OP_Close, 2, 0);
      sqlite3VdbeAddOp(v, OP_Close, 1, 0);
      sqlite3ChangeCookie(db, v, iDb);
      sqlite3VdbeAddOp(v, OP_Close, 0, 0);

      sqlite3VdbeOp3(v, OP_ParseSchema, iDb, 0,
         sqlite3MPrintf("name='%q'", pIndex->zName), P3_DYNAMIC);
    }
  }

  /* When adding an index to the list of indices for a table, make
  ** sure all indices labeled OE_Replace come after all those labeled
................................................................................
    sqlite3OpenMasterTable(v, pIndex->iDb);
    base = sqlite3VdbeAddOpList(v, ArraySize(dropIndex), dropIndex);
    sqlite3VdbeChangeP3(v, base+1, pIndex->zName, 0);
    sqlite3ChangeCookie(db, v, pIndex->iDb);
    sqlite3VdbeAddOp(v, OP_Close, 0, 0);
    sqlite3VdbeAddOp(v, OP_Destroy, pIndex->tnum, pIndex->iDb);
    sqlite3VdbeOp3(v, OP_DropIndex, pIndex->iDb, 0, pIndex->zName, 0);

  }

exit_drop_index:
  sqlite3SrcListDelete(pName);
}

/*
................................................................................
  }
  sqliteFree(pList);
}

/*
** Begin a transaction
*/
void sqlite3BeginTransaction(Parse *pParse, int type){
  sqlite3 *db;
  Vdbe *v;
  int i;

  if( pParse==0 || (db=pParse->db)==0 || db->aDb[0].pBt==0 ) return;
  if( pParse->nErr || sqlite3_malloc_failed ) return;
  if( sqlite3AuthCheck(pParse, SQLITE_TRANSACTION, "BEGIN", 0, 0) ) return;

  v = sqlite3GetVdbe(pParse);
  if( !v ) return;
  if( type!=TK_DEFERRED ){
    for(i=0; i<db->nDb; i++){
      sqlite3VdbeAddOp(v, OP_Transaction, i, (type==TK_EXCLUSIVE)+1);
    }
  }
  sqlite3VdbeAddOp(v, OP_AutoCommit, 0, 0);
}

/*
** Commit a transaction
*/
void sqlite3CommitTransaction(Parse *pParse){
................................................................................
    sqlite3VdbeAddOp(v, OP_Statement, iDb, 0);
  }
  if( iDb!=1 && pParse->db->aDb[1].pBt!=0 ){
    sqlite3BeginWriteOperation(pParse, setStatement, 1);
  }
}
















/* 
** Return the transient sqlite3_value object used for encoding conversions
** during SQL compilation.
*/
sqlite3_value *sqlite3GetTransientValue(sqlite3 *db){
  if( !db->pValue ){
    db->pValue = sqlite3ValueNew();
  }
  return db->pValue;
}

**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains C code routines that are called by the parser
** to handle DELETE FROM statements.
**
** $Id: delete.c,v 1.81 2004/09/19 02:15:25 drh Exp $
*/
#include "sqliteInt.h"

/*
** Look up every table that is named in pSrc.  If any table is not found,
** add an error message to pParse->zErrMsg and return NULL.  If all tables
** are found, return a pointer to the last table.
................................................................................
    if( !row_triggers_exist ){
      for(i=1, pIdx=pTab->pIndex; pIdx; i++, pIdx=pIdx->pNext){
        sqlite3VdbeAddOp(v, OP_Close, iCur + i, pIdx->tnum);
      }
      sqlite3VdbeAddOp(v, OP_Close, iCur, 0);
    }
  }
  sqlite3EndWriteOperation(pParse);

  /*
  ** Return the number of rows that were deleted.
  */
  if( db->flags & SQLITE_CountRows ){
    sqlite3VdbeAddOp(v, OP_Callback, 1, 0);
    sqlite3VdbeSetNumCols(v, 1);

**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains C code routines that are called by the parser
** to handle DELETE FROM statements.
**
** $Id: delete.c,v 1.82 2004/10/05 02:41:42 drh Exp $
*/
#include "sqliteInt.h"

/*
** Look up every table that is named in pSrc.  If any table is not found,
** add an error message to pParse->zErrMsg and return NULL.  If all tables
** are found, return a pointer to the last table.
................................................................................
    if( !row_triggers_exist ){
      for(i=1, pIdx=pTab->pIndex; pIdx; i++, pIdx=pIdx->pNext){
        sqlite3VdbeAddOp(v, OP_Close, iCur + i, pIdx->tnum);
      }
      sqlite3VdbeAddOp(v, OP_Close, iCur, 0);
    }
  }


  /*
  ** Return the number of rows that were deleted.
  */
  if( db->flags & SQLITE_CountRows ){
    sqlite3VdbeAddOp(v, OP_Callback, 1, 0);
    sqlite3VdbeSetNumCols(v, 1);

**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains C code routines that are called by the parser
** to handle INSERT statements in SQLite.
**
** $Id: insert.c,v 1.118 2004/09/19 02:15:26 drh Exp $
*/
#include "sqliteInt.h"

/*
** Set P3 of the most recently inserted opcode to a column affinity
** string for index pIdx. A column affinity string has one character
** for each column in the table, according to the affinity of the column:
................................................................................
    /* Close all tables opened */
    sqlite3VdbeAddOp(v, OP_Close, base, 0);
    for(idx=1, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, idx++){
      sqlite3VdbeAddOp(v, OP_Close, idx+base, 0);
    }
  }

  sqlite3EndWriteOperation(pParse);

  /*
  ** Return the number of rows inserted.
  */
  if( db->flags & SQLITE_CountRows ){
    sqlite3VdbeAddOp(v, OP_MemLoad, iCntMem, 0);
    sqlite3VdbeAddOp(v, OP_Callback, 1, 0);
    sqlite3VdbeSetNumCols(v, 1);

**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains C code routines that are called by the parser
** to handle INSERT statements in SQLite.
**
** $Id: insert.c,v 1.119 2004/10/05 02:41:42 drh Exp $
*/
#include "sqliteInt.h"

/*
** Set P3 of the most recently inserted opcode to a column affinity
** string for index pIdx. A column affinity string has one character
** for each column in the table, according to the affinity of the column:
................................................................................
    /* Close all tables opened */
    sqlite3VdbeAddOp(v, OP_Close, base, 0);
    for(idx=1, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, idx++){
      sqlite3VdbeAddOp(v, OP_Close, idx+base, 0);
    }
  }



  /*
  ** Return the number of rows inserted.
  */
  if( db->flags & SQLITE_CountRows ){
    sqlite3VdbeAddOp(v, OP_MemLoad, iCntMem, 0);
    sqlite3VdbeAddOp(v, OP_Callback, 1, 0);
    sqlite3VdbeSetNumCols(v, 1);

** The pager is used to access a database disk file.  It implements
** atomic commit and rollback through the use of a journal file that
** is separate from the database file.  The pager also implements file
** locking to prevent two processes from writing the same database
** file simultaneously, or one process from reading the database while
** another is writing.
**
** @(#) $Id: pager.c,v 1.166 2004/10/02 20:38:28 drh Exp $
*/
#include "sqliteInt.h"
#include "os.h"
#include "pager.h"
#include <assert.h>
#include <string.h>

................................................................................
** called on an outstanding page which means that the pager must
** be in PAGER_SHARED before it transitions to PAGER_RESERVED.)
** The transition to PAGER_EXCLUSIVE occurs when before any changes
** are made to the database file.  After an sqlite3pager_rollback()
** or sqlite_pager_commit(), the state goes back to PAGER_SHARED.
*/
#define PAGER_UNLOCK      0
#define PAGER_SHARED      1
#define PAGER_RESERVED    2
#define PAGER_EXCLUSIVE   3
#define PAGER_SYNCED      4


















/*
** Each in-memory image of a page begins with the following header.
** This header is only visible to this pager module.  The client
** code that calls pager sees only the data that follows the header.
**
** Client code should call sqlite3pager_write() on a page prior to making
................................................................................
    }
    assert( pPager->pFirstSynced==pPager->pFirst );
  }
#endif

  return rc;
}
































/*
** Given a list of pages (connected by the PgHdr.pDirty pointer) write
** every one of those pages out to the database file and mark them all
** as clean.
*/
static int pager_write_pagelist(PgHdr *pList){
  Pager *pPager;
  int rc;
  int busy = 1;

  if( pList==0 ) return SQLITE_OK;
  pPager = pList->pPager;

  /* At this point there may be either a RESERVED or EXCLUSIVE lock on the
  ** database file. If there is already an EXCLUSIVE lock, the following
  ** calls to sqlite3OsLock() are no-ops.
................................................................................
  **
  ** While the pager is in the RESERVED state, the original database file
  ** is unchanged and we can rollback without having to playback the
  ** journal into the original database file.  Once we transition to
  ** EXCLUSIVE, it means the database file has been changed and any rollback
  ** will require a journal playback.
  */
  do {
    rc = sqlite3OsLock(&pPager->fd, EXCLUSIVE_LOCK);
  }while( rc==SQLITE_BUSY && 
      pPager->pBusyHandler && 
      pPager->pBusyHandler->xFunc && 
      pPager->pBusyHandler->xFunc(pPager->pBusyHandler->pArg, busy++)
  );
  if( rc!=SQLITE_OK ){
    return rc;
  }
  pPager->state = PAGER_EXCLUSIVE;

  while( pList ){
    assert( pList->dirty );
    sqlite3OsSeek(&pPager->fd, (pList->pgno-1)*(i64)pPager->pageSize);
    CODEC(pPager, PGHDR_TO_DATA(pList), pList->pgno, 6);
    TRACE3("STORE %d page %d\n", pPager->fd.h, pList->pgno);
    rc = sqlite3OsWrite(&pPager->fd, PGHDR_TO_DATA(pList), pPager->pageSize);
................................................................................
    return pager_errcode(pPager);
  }

  /* If this is the first page accessed, then get a SHARED lock
  ** on the database file.
  */
  if( pPager->nRef==0 && !pPager->memDb ){
    int busy = 1;
    do {
      rc = sqlite3OsLock(&pPager->fd, SHARED_LOCK);
    }while( rc==SQLITE_BUSY && 
        pPager->pBusyHandler && 
        pPager->pBusyHandler->xFunc && 
        pPager->pBusyHandler->xFunc(pPager->pBusyHandler->pArg, busy++)
    );
    if( rc!=SQLITE_OK ){
      return rc;
    }
    pPager->state = PAGER_SHARED;

    /* If a journal file exists, and there is no RESERVED lock on the
    ** database file, then it either needs to be played back or deleted.
    */
    if( pPager->useJournal && 
        sqlite3OsFileExists(pPager->zJournal) &&
        !sqlite3OsCheckReservedLock(&pPager->fd) 
................................................................................
** master journal file-name at the start of the journal when it is created.
**
** A journal file is opened if this is not a temporary file.  For temporary
** files, the opening of the journal file is deferred until there is an
** actual need to write to the journal.
**
** If the database is already reserved for writing, this routine is a no-op.




*/
int sqlite3pager_begin(void *pData){
  PgHdr *pPg = DATA_TO_PGHDR(pData);
  Pager *pPager = pPg->pPager;
  int rc = SQLITE_OK;
  assert( pPg->nRef>0 );
  assert( pPager->state!=PAGER_UNLOCK );
  if( pPager->state==PAGER_SHARED ){
    assert( pPager->aInJournal==0 );
    if( pPager->memDb ){
      pPager->state = PAGER_EXCLUSIVE;
      pPager->origDbSize = pPager->dbSize;
    }else{
#ifdef SQLITE_BUSY_RESERVED_LOCK
      int busy = 1;
      do {
        rc = sqlite3OsLock(&pPager->fd, RESERVED_LOCK);
      }while( rc==SQLITE_BUSY && 
          pPager->pBusyHandler && 
          pPager->pBusyHandler->xFunc && 
          pPager->pBusyHandler->xFunc(pPager->pBusyHandler->pArg, busy++)
      );
#else
      rc = sqlite3OsLock(&pPager->fd, RESERVED_LOCK);
#endif
      if( rc!=SQLITE_OK ){
        /* We do not call the busy handler when we fail to get a reserved lock.
        ** The only reason we might fail is because another process is holding
        ** the reserved lock.  But the other process will not be able to
        ** release its reserved lock until this process releases its shared
        ** lock.  So we might as well fail in this process, let it release
        ** its shared lock so that the other process can commit.
        */
        return rc;
      }
      pPager->state = PAGER_RESERVED;
      pPager->dirtyCache = 0;
      TRACE2("TRANSACTION %d\n", pPager->fd.h);
      if( pPager->useJournal && !pPager->tempFile ){
        rc = pager_open_journal(pPager);
      }
    }
  }
................................................................................
  ** written to the transaction journal or the ckeckpoint journal
  ** or both.
  **
  ** First check to see that the transaction journal exists and
  ** create it if it does not.
  */
  assert( pPager->state!=PAGER_UNLOCK );
  rc = sqlite3pager_begin(pData);
  if( rc!=SQLITE_OK ){
    return rc;
  }
  assert( pPager->state>=PAGER_RESERVED );
  if( !pPager->journalOpen && pPager->useJournal ){
    rc = pager_open_journal(pPager);
    if( rc!=SQLITE_OK ) return rc;

** The pager is used to access a database disk file.  It implements
** atomic commit and rollback through the use of a journal file that
** is separate from the database file.  The pager also implements file
** locking to prevent two processes from writing the same database
** file simultaneously, or one process from reading the database while
** another is writing.
**
** @(#) $Id: pager.c,v 1.167 2004/10/05 02:41:43 drh Exp $
*/
#include "sqliteInt.h"
#include "os.h"
#include "pager.h"
#include <assert.h>
#include <string.h>

................................................................................
** called on an outstanding page which means that the pager must
** be in PAGER_SHARED before it transitions to PAGER_RESERVED.)
** The transition to PAGER_EXCLUSIVE occurs when before any changes
** are made to the database file.  After an sqlite3pager_rollback()
** or sqlite_pager_commit(), the state goes back to PAGER_SHARED.
*/
#define PAGER_UNLOCK      0
#define PAGER_SHARED      1   /* same as SHARED_LOCK */
#define PAGER_RESERVED    2   /* same as RESERVED_LOCK */
#define PAGER_EXCLUSIVE   4   /* same as EXCLUSIVE_LOCK */
#define PAGER_SYNCED      5

/*
** If the SQLITE_BUSY_RESERVED_LOCK macro is set to true at compile-time,
** then failed attempts to get a reserved lock will invoke the busy callback.
** This is off by default.  To see why, consider the following scenario:
** 
** Suppose thread A already has a shared lock and wants a reserved lock.
** Thread B already has a reserved lock and wants an exclusive lock.  If
** both threads are using their busy callbacks, it might be a long time
** be for one of the threads give up and allows the other to proceed.
** But if the thread trying to get the reserved lock gives up quickly
** (if it never invokes its busy callback) then the contention will be
** resolved quickly.
*/
#ifndef SQLITE_BUSY_RESERVED_LOCK
# define SQLITE_BUSY_RESERVED_LOCK 0
#endif

/*
** Each in-memory image of a page begins with the following header.
** This header is only visible to this pager module.  The client
** code that calls pager sees only the data that follows the header.
**
** Client code should call sqlite3pager_write() on a page prior to making
................................................................................
    }
    assert( pPager->pFirstSynced==pPager->pFirst );
  }
#endif

  return rc;
}

/*
** Try to obtain a lock on a file.  Invoke the busy callback if the lock
** is currently not available.  Repeate until the busy callback returns
** false or until the lock succeeds.
**
** Return SQLITE_OK on success and an error code if we cannot obtain
** the lock.
*/
static int pager_wait_on_lock(Pager *pPager, int locktype){
  int rc;
  assert( PAGER_SHARED==SHARED_LOCK );
  assert( PAGER_RESERVED==RESERVED_LOCK );
  assert( PAGER_EXCLUSIVE==EXCLUSIVE_LOCK );
  if( pPager->state>=locktype ){
    rc = SQLITE_OK;
  }else{
    int busy = 1;
    do {
      rc = sqlite3OsLock(&pPager->fd, locktype);
    }while( rc==SQLITE_BUSY && 
        pPager->pBusyHandler && 
        pPager->pBusyHandler->xFunc && 
        pPager->pBusyHandler->xFunc(pPager->pBusyHandler->pArg, busy++)
    );
    if( rc==SQLITE_OK ){
      pPager->state = locktype;
    }
  }
  return rc;
}

/*
** Given a list of pages (connected by the PgHdr.pDirty pointer) write
** every one of those pages out to the database file and mark them all
** as clean.
*/
static int pager_write_pagelist(PgHdr *pList){
  Pager *pPager;
  int rc;


  if( pList==0 ) return SQLITE_OK;
  pPager = pList->pPager;

  /* At this point there may be either a RESERVED or EXCLUSIVE lock on the
  ** database file. If there is already an EXCLUSIVE lock, the following
  ** calls to sqlite3OsLock() are no-ops.
................................................................................
  **
  ** While the pager is in the RESERVED state, the original database file
  ** is unchanged and we can rollback without having to playback the
  ** journal into the original database file.  Once we transition to
  ** EXCLUSIVE, it means the database file has been changed and any rollback
  ** will require a journal playback.
  */

  rc = pager_wait_on_lock(pPager, EXCLUSIVE_LOCK);





  if( rc!=SQLITE_OK ){
    return rc;
  }


  while( pList ){
    assert( pList->dirty );
    sqlite3OsSeek(&pPager->fd, (pList->pgno-1)*(i64)pPager->pageSize);
    CODEC(pPager, PGHDR_TO_DATA(pList), pList->pgno, 6);
    TRACE3("STORE %d page %d\n", pPager->fd.h, pList->pgno);
    rc = sqlite3OsWrite(&pPager->fd, PGHDR_TO_DATA(pList), pPager->pageSize);
................................................................................
    return pager_errcode(pPager);
  }

  /* If this is the first page accessed, then get a SHARED lock
  ** on the database file.
  */
  if( pPager->nRef==0 && !pPager->memDb ){
    rc = pager_wait_on_lock(pPager, SHARED_LOCK);







    if( rc!=SQLITE_OK ){
      return rc;
    }


    /* If a journal file exists, and there is no RESERVED lock on the
    ** database file, then it either needs to be played back or deleted.
    */
    if( pPager->useJournal && 
        sqlite3OsFileExists(pPager->zJournal) &&
        !sqlite3OsCheckReservedLock(&pPager->fd) 
................................................................................
** master journal file-name at the start of the journal when it is created.
**
** A journal file is opened if this is not a temporary file.  For temporary
** files, the opening of the journal file is deferred until there is an
** actual need to write to the journal.
**
** If the database is already reserved for writing, this routine is a no-op.
**
** If exFlag is true, go ahead and get an EXCLUSIVE lock on the file
** immediately instead of waiting until we try to flush the cache.  The
** exFlag is ignored if a transaction is already active.
*/
int sqlite3pager_begin(void *pData, int exFlag){
  PgHdr *pPg = DATA_TO_PGHDR(pData);
  Pager *pPager = pPg->pPager;
  int rc = SQLITE_OK;
  assert( pPg->nRef>0 );
  assert( pPager->state!=PAGER_UNLOCK );
  if( pPager->state==PAGER_SHARED ){
    assert( pPager->aInJournal==0 );
    if( pPager->memDb ){
      pPager->state = PAGER_EXCLUSIVE;
      pPager->origDbSize = pPager->dbSize;
    }else{
      if( SQLITE_BUSY_RESERVED_LOCK || exFlag ){
        rc = pager_wait_on_lock(pPager, RESERVED_LOCK);
      }else{
        rc = sqlite3OsLock(&pPager->fd, RESERVED_LOCK);
      }
      if( rc==SQLITE_OK ){
        pPager->state = PAGER_RESERVED;
        if( exFlag ){
          rc = pager_wait_on_lock(pPager, EXCLUSIVE_LOCK);
        }
      }
      if( rc!=SQLITE_OK ){
        return rc;
      }









      pPager->dirtyCache = 0;
      TRACE2("TRANSACTION %d\n", pPager->fd.h);
      if( pPager->useJournal && !pPager->tempFile ){
        rc = pager_open_journal(pPager);
      }
    }
  }
................................................................................
  ** written to the transaction journal or the ckeckpoint journal
  ** or both.
  **
  ** First check to see that the transaction journal exists and
  ** create it if it does not.
  */
  assert( pPager->state!=PAGER_UNLOCK );
  rc = sqlite3pager_begin(pData, 0);
  if( rc!=SQLITE_OK ){
    return rc;
  }
  assert( pPager->state>=PAGER_RESERVED );
  if( !pPager->journalOpen && pPager->useJournal ){
    rc = pager_open_journal(pPager);
    if( rc!=SQLITE_OK ) return rc;

**    May you share freely, never taking more than you give.
**
*************************************************************************
** This header file defines the interface that the sqlite page cache
** subsystem.  The page cache subsystem reads and writes a file a page
** at a time and provides a journal for rollback.
**
** @(#) $Id: pager.h,v 1.37 2004/07/22 01:19:35 drh Exp $
*/

/*
** The default size of a database page.
*/
#ifndef SQLITE_DEFAULT_PAGE_SIZE
# define SQLITE_DEFAULT_PAGE_SIZE 1024
................................................................................
int sqlite3pager_unref(void*);
Pgno sqlite3pager_pagenumber(void*);
int sqlite3pager_write(void*);
int sqlite3pager_iswriteable(void*);
int sqlite3pager_overwrite(Pager *pPager, Pgno pgno, void*);
int sqlite3pager_pagecount(Pager*);
int sqlite3pager_truncate(Pager*,Pgno);
int sqlite3pager_begin(void*);
int sqlite3pager_commit(Pager*);
int sqlite3pager_sync(Pager*,const char *zMaster);
int sqlite3pager_rollback(Pager*);
int sqlite3pager_isreadonly(Pager*);
int sqlite3pager_stmt_begin(Pager*);
int sqlite3pager_stmt_commit(Pager*);
int sqlite3pager_stmt_rollback(Pager*);

**    May you share freely, never taking more than you give.
**
*************************************************************************
** This header file defines the interface that the sqlite page cache
** subsystem.  The page cache subsystem reads and writes a file a page
** at a time and provides a journal for rollback.
**
** @(#) $Id: pager.h,v 1.38 2004/10/05 02:41:43 drh Exp $
*/

/*
** The default size of a database page.
*/
#ifndef SQLITE_DEFAULT_PAGE_SIZE
# define SQLITE_DEFAULT_PAGE_SIZE 1024
................................................................................
int sqlite3pager_unref(void*);
Pgno sqlite3pager_pagenumber(void*);
int sqlite3pager_write(void*);
int sqlite3pager_iswriteable(void*);
int sqlite3pager_overwrite(Pager *pPager, Pgno pgno, void*);
int sqlite3pager_pagecount(Pager*);
int sqlite3pager_truncate(Pager*,Pgno);
int sqlite3pager_begin(void*, int exFlag);
int sqlite3pager_commit(Pager*);
int sqlite3pager_sync(Pager*,const char *zMaster);
int sqlite3pager_rollback(Pager*);
int sqlite3pager_isreadonly(Pager*);
int sqlite3pager_stmt_begin(Pager*);
int sqlite3pager_stmt_commit(Pager*);
int sqlite3pager_stmt_rollback(Pager*);

**
*************************************************************************
** This file contains SQLite's grammar for SQL.  Process this file
** using the lemon parser generator to generate C code that runs
** the parser.  Lemon will also generate a header file containing
** numeric codes for all of the tokens.
**
** @(#) $Id: parse.y,v 1.141 2004/10/04 13:38:09 drh Exp $
*/
%token_prefix TK_
%token_type {Token}
%default_type {Token}
%extra_argument {Parse *pParse}
%syntax_error {
  if( pParse->zErrMsg==0 ){
................................................................................
cmdx ::= cmd.           { sqlite3FinishCoding(pParse); }
explain ::= EXPLAIN.    { sqlite3BeginParse(pParse, 1); }
explain ::= .           { sqlite3BeginParse(pParse, 0); }

///////////////////// Begin and end transactions. ////////////////////////////
//

cmd ::= BEGIN trans_opt.  {sqlite3BeginTransaction(pParse);}
trans_opt ::= .
trans_opt ::= TRANSACTION.
trans_opt ::= TRANSACTION nm.





cmd ::= COMMIT trans_opt.      {sqlite3CommitTransaction(pParse);}
cmd ::= END trans_opt.         {sqlite3CommitTransaction(pParse);}
cmd ::= ROLLBACK trans_opt.    {sqlite3RollbackTransaction(pParse);}

///////////////////// The CREATE TABLE statement ////////////////////////////
//
cmd ::= create_table create_table_args.
................................................................................

// The following directive causes tokens ABORT, AFTER, ASC, etc. to
// fallback to ID if they will not parse as their original value.
// This obviates the need for the "id" nonterminal.
//
%fallback ID
  ABORT AFTER ASC ATTACH BEFORE BEGIN CASCADE CONFLICT
  DATABASE DEFERRED DESC DETACH EACH END EXPLAIN FAIL FOR
  GLOB IGNORE IMMEDIATE INITIALLY INSTEAD LIKE MATCH KEY
  OF OFFSET PRAGMA RAISE REPLACE RESTRICT ROW STATEMENT
  TEMP TRIGGER VACUUM VIEW.

// Define operator precedence early so that this is the first occurance
// of the operator tokens in the grammer.  Keeping the operators together
// causes them to be assigned integer values that are close together,

**
*************************************************************************
** This file contains SQLite's grammar for SQL.  Process this file
** using the lemon parser generator to generate C code that runs
** the parser.  Lemon will also generate a header file containing
** numeric codes for all of the tokens.
**
** @(#) $Id: parse.y,v 1.142 2004/10/05 02:41:43 drh Exp $
*/
%token_prefix TK_
%token_type {Token}
%default_type {Token}
%extra_argument {Parse *pParse}
%syntax_error {
  if( pParse->zErrMsg==0 ){
................................................................................
cmdx ::= cmd.           { sqlite3FinishCoding(pParse); }
explain ::= EXPLAIN.    { sqlite3BeginParse(pParse, 1); }
explain ::= .           { sqlite3BeginParse(pParse, 0); }

///////////////////// Begin and end transactions. ////////////////////////////
//

cmd ::= BEGIN transtype(Y) trans_opt.  {sqlite3BeginTransaction(pParse, Y);}
trans_opt ::= .
trans_opt ::= TRANSACTION.
trans_opt ::= TRANSACTION nm.
%type transtype {int}
transtype(A) ::= .             {A = TK_DEFERRED;}
transtype(A) ::= DEFERRED(X).  {A = @X;}
transtype(A) ::= IMMEDIATE(X). {A = @X;}
transtype(A) ::= EXCLUSIVE(X). {A = @X;}
cmd ::= COMMIT trans_opt.      {sqlite3CommitTransaction(pParse);}
cmd ::= END trans_opt.         {sqlite3CommitTransaction(pParse);}
cmd ::= ROLLBACK trans_opt.    {sqlite3RollbackTransaction(pParse);}

///////////////////// The CREATE TABLE statement ////////////////////////////
//
cmd ::= create_table create_table_args.
................................................................................

// The following directive causes tokens ABORT, AFTER, ASC, etc. to
// fallback to ID if they will not parse as their original value.
// This obviates the need for the "id" nonterminal.
//
%fallback ID
  ABORT AFTER ASC ATTACH BEFORE BEGIN CASCADE CONFLICT
  DATABASE DEFERRED DESC DETACH EACH END EXCLUSIVE EXPLAIN FAIL FOR
  GLOB IGNORE IMMEDIATE INITIALLY INSTEAD LIKE MATCH KEY
  OF OFFSET PRAGMA RAISE REPLACE RESTRICT ROW STATEMENT
  TEMP TRIGGER VACUUM VIEW.

// Define operator precedence early so that this is the first occurance
// of the operator tokens in the grammer.  Keeping the operators together
// causes them to be assigned integer values that are close together,

**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains code used to implement the PRAGMA command.
**
** $Id: pragma.c,v 1.67 2004/09/25 14:39:19 drh Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>

#if defined(SQLITE_DEBUG) || defined(SQLITE_TEST)
# include "pager.h"
# include "btree.h"
................................................................................
      sqlite3BeginWriteOperation(pParse, 0, iDb);
      sqlite3VdbeAddOp(v, OP_Integer, size, 0);
      sqlite3VdbeAddOp(v, OP_ReadCookie, iDb, 2);
      addr = sqlite3VdbeAddOp(v, OP_Integer, 0, 0);
      sqlite3VdbeAddOp(v, OP_Ge, 0, addr+3);
      sqlite3VdbeAddOp(v, OP_Negative, 0, 0);
      sqlite3VdbeAddOp(v, OP_SetCookie, iDb, 2);
      sqlite3EndWriteOperation(pParse);
      pDb->cache_size = size;
      sqlite3BtreeSetCacheSize(pDb->pBt, pDb->cache_size);
    }
  }else

  /*
  **  PRAGMA [database.]page_size

**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains code used to implement the PRAGMA command.
**
** $Id: pragma.c,v 1.68 2004/10/05 02:41:43 drh Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>

#if defined(SQLITE_DEBUG) || defined(SQLITE_TEST)
# include "pager.h"
# include "btree.h"
................................................................................
      sqlite3BeginWriteOperation(pParse, 0, iDb);
      sqlite3VdbeAddOp(v, OP_Integer, size, 0);
      sqlite3VdbeAddOp(v, OP_ReadCookie, iDb, 2);
      addr = sqlite3VdbeAddOp(v, OP_Integer, 0, 0);
      sqlite3VdbeAddOp(v, OP_Ge, 0, addr+3);
      sqlite3VdbeAddOp(v, OP_Negative, 0, 0);
      sqlite3VdbeAddOp(v, OP_SetCookie, iDb, 2);

      pDb->cache_size = size;
      sqlite3BtreeSetCacheSize(pDb->pBt, pDb->cache_size);
    }
  }else

  /*
  **  PRAGMA [database.]page_size

**    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.
**
*************************************************************************
** Internal interface definitions for SQLite.
**
** @(#) $Id: sqliteInt.h,v 1.326 2004/10/04 13:19:24 drh Exp $
*/
#ifndef _SQLITEINT_H_
#define _SQLITEINT_H_

/*
** These #defines should enable >2GB file support on Posix if the
** underlying operating system supports it.  If the OS lacks
................................................................................
int sqlite3ExprResolveIds(Parse*, SrcList*, ExprList*, Expr*);
int sqlite3ExprResolveAndCheck(Parse*,SrcList*,ExprList*,Expr*,int,int*);
int sqlite3ExprAnalyzeAggregates(Parse*, Expr*);
Vdbe *sqlite3GetVdbe(Parse*);
void sqlite3Randomness(int, void*);
void sqlite3RollbackAll(sqlite3*);
void sqlite3CodeVerifySchema(Parse*, int);
void sqlite3BeginTransaction(Parse*);
void sqlite3CommitTransaction(Parse*);
void sqlite3RollbackTransaction(Parse*);
int sqlite3ExprIsConstant(Expr*);
int sqlite3ExprIsInteger(Expr*, int*);
int sqlite3IsRowid(const char*);
void sqlite3GenerateRowDelete(sqlite3*, Vdbe*, Table*, int, int);
void sqlite3GenerateRowIndexDelete(sqlite3*, Vdbe*, Table*, int, char*);
void sqlite3GenerateIndexKey(Vdbe*, Index*, int);
void sqlite3GenerateConstraintChecks(Parse*,Table*,int,char*,int,int,int,int);
void sqlite3CompleteInsertion(Parse*, Table*, int, char*, int, int, int);
void sqlite3OpenTableAndIndices(Parse*, Table*, int, int);
void sqlite3BeginWriteOperation(Parse*, int, int);
void sqlite3EndWriteOperation(Parse*);
Expr *sqlite3ExprDup(Expr*);
void sqlite3TokenCopy(Token*, Token*);
ExprList *sqlite3ExprListDup(ExprList*);
SrcList *sqlite3SrcListDup(SrcList*);
IdList *sqlite3IdListDup(IdList*);
Select *sqlite3SelectDup(Select*);
FuncDef *sqlite3FindFunction(sqlite3*,const char*,int,int,u8,int);

**    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.
**
*************************************************************************
** Internal interface definitions for SQLite.
**
** @(#) $Id: sqliteInt.h,v 1.327 2004/10/05 02:41:43 drh Exp $
*/
#ifndef _SQLITEINT_H_
#define _SQLITEINT_H_

/*
** These #defines should enable >2GB file support on Posix if the
** underlying operating system supports it.  If the OS lacks
................................................................................
int sqlite3ExprResolveIds(Parse*, SrcList*, ExprList*, Expr*);
int sqlite3ExprResolveAndCheck(Parse*,SrcList*,ExprList*,Expr*,int,int*);
int sqlite3ExprAnalyzeAggregates(Parse*, Expr*);
Vdbe *sqlite3GetVdbe(Parse*);
void sqlite3Randomness(int, void*);
void sqlite3RollbackAll(sqlite3*);
void sqlite3CodeVerifySchema(Parse*, int);
void sqlite3BeginTransaction(Parse*, int);
void sqlite3CommitTransaction(Parse*);
void sqlite3RollbackTransaction(Parse*);
int sqlite3ExprIsConstant(Expr*);
int sqlite3ExprIsInteger(Expr*, int*);
int sqlite3IsRowid(const char*);
void sqlite3GenerateRowDelete(sqlite3*, Vdbe*, Table*, int, int);
void sqlite3GenerateRowIndexDelete(sqlite3*, Vdbe*, Table*, int, char*);
void sqlite3GenerateIndexKey(Vdbe*, Index*, int);
void sqlite3GenerateConstraintChecks(Parse*,Table*,int,char*,int,int,int,int);
void sqlite3CompleteInsertion(Parse*, Table*, int, char*, int, int, int);
void sqlite3OpenTableAndIndices(Parse*, Table*, int, int);
void sqlite3BeginWriteOperation(Parse*, int, int);

Expr *sqlite3ExprDup(Expr*);
void sqlite3TokenCopy(Token*, Token*);
ExprList *sqlite3ExprListDup(ExprList*);
SrcList *sqlite3SrcListDup(SrcList*);
IdList *sqlite3IdListDup(IdList*);
Select *sqlite3SelectDup(Select*);
FuncDef *sqlite3FindFunction(sqlite3*,const char*,int,int,u8,int);

*************************************************************************
** An tokenizer for SQL
**
** This file contains C code that splits an SQL input string up into
** individual tokens and sends those tokens one-by-one over to the
** parser for analysis.
**
** $Id: tokenize.c,v 1.89 2004/09/25 15:25:26 drh Exp $
*/
#include "sqliteInt.h"
#include "os.h"
#include <ctype.h>
#include <stdlib.h>

/*
................................................................................
  { "DETACH",            TK_DETACH,       },
  { "DISTINCT",          TK_DISTINCT,     },
  { "DROP",              TK_DROP,         },
  { "END",               TK_END,          },
  { "EACH",              TK_EACH,         },
  { "ELSE",              TK_ELSE,         },
  { "EXCEPT",            TK_EXCEPT,       },

  { "EXPLAIN",           TK_EXPLAIN,      },
  { "FAIL",              TK_FAIL,         },
  { "FOR",               TK_FOR,          },
  { "FOREIGN",           TK_FOREIGN,      },
  { "FROM",              TK_FROM,         },
  { "FULL",              TK_JOIN_KW,      },
  { "GLOB",              TK_GLOB,         },

*************************************************************************
** An tokenizer for SQL
**
** This file contains C code that splits an SQL input string up into
** individual tokens and sends those tokens one-by-one over to the
** parser for analysis.
**
** $Id: tokenize.c,v 1.90 2004/10/05 02:41:43 drh Exp $
*/
#include "sqliteInt.h"
#include "os.h"
#include <ctype.h>
#include <stdlib.h>

/*
................................................................................
  { "DETACH",            TK_DETACH,       },
  { "DISTINCT",          TK_DISTINCT,     },
  { "DROP",              TK_DROP,         },
  { "END",               TK_END,          },
  { "EACH",              TK_EACH,         },
  { "ELSE",              TK_ELSE,         },
  { "EXCEPT",            TK_EXCEPT,       },
  { "EXCLUSIVE",         TK_EXCLUSIVE,    },
  { "EXPLAIN",           TK_EXPLAIN,      },
  { "FAIL",              TK_FAIL,         },
  { "FOR",               TK_FOR,          },
  { "FOREIGN",           TK_FOREIGN,      },
  { "FROM",              TK_FROM,         },
  { "FULL",              TK_JOIN_KW,      },
  { "GLOB",              TK_GLOB,         },

    sqlite3VdbeChangeP3(v, addr+6, pAll->z, pAll->n);
    if( nt->iDb!=0 ){
      sqlite3ChangeCookie(db, v, nt->iDb);
    }
    sqlite3VdbeAddOp(v, OP_Close, 0, 0);
    sqlite3VdbeOp3(v, OP_ParseSchema, nt->iDb, 0, 
       sqlite3MPrintf("type='trigger' AND name='%q'", nt->name), P3_DYNAMIC);
    sqlite3EndWriteOperation(pParse);
  }

  if( db->init.busy ){
    Table *pTab;
    sqlite3HashInsert(&db->aDb[nt->iDb].trigHash, 
                     nt->name, strlen(nt->name)+1, nt);
    pTab = sqlite3LocateTable(pParse, nt->table, db->aDb[nt->iTabDb].zName);

    sqlite3VdbeChangeP3(v, addr+6, pAll->z, pAll->n);
    if( nt->iDb!=0 ){
      sqlite3ChangeCookie(db, v, nt->iDb);
    }
    sqlite3VdbeAddOp(v, OP_Close, 0, 0);
    sqlite3VdbeOp3(v, OP_ParseSchema, nt->iDb, 0, 
       sqlite3MPrintf("type='trigger' AND name='%q'", nt->name), P3_DYNAMIC);

  }

  if( db->init.busy ){
    Table *pTab;
    sqlite3HashInsert(&db->aDb[nt->iDb].trigHash, 
                     nt->name, strlen(nt->name)+1, nt);
    pTab = sqlite3LocateTable(pParse, nt->table, db->aDb[nt->iTabDb].zName);

**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains C code routines that are called by the parser
** to handle UPDATE statements.
**
** $Id: update.c,v 1.89 2004/09/19 02:15:26 drh Exp $
*/
#include "sqliteInt.h"

/*
** Process an UPDATE statement.
**
**   UPDATE OR IGNORE table_wxyz SET a=b, c=d WHERE e<5 AND f NOT NULL;
................................................................................
    }
    sqlite3VdbeAddOp(v, OP_Close, iCur, 0);
  }else{
    sqlite3VdbeAddOp(v, OP_Close, newIdx, 0);
    sqlite3VdbeAddOp(v, OP_Close, oldIdx, 0);
  }

  sqlite3EndWriteOperation(pParse);

  /*
  ** Return the number of rows that were changed.
  */
  if( db->flags & SQLITE_CountRows && !pParse->trigStack ){
    sqlite3VdbeAddOp(v, OP_Callback, 1, 0);
    sqlite3VdbeSetNumCols(v, 1);
    sqlite3VdbeSetColName(v, 0, "rows updated", P3_STATIC);

**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains C code routines that are called by the parser
** to handle UPDATE statements.
**
** $Id: update.c,v 1.90 2004/10/05 02:41:43 drh Exp $
*/
#include "sqliteInt.h"

/*
** Process an UPDATE statement.
**
**   UPDATE OR IGNORE table_wxyz SET a=b, c=d WHERE e<5 AND f NOT NULL;
................................................................................
    }
    sqlite3VdbeAddOp(v, OP_Close, iCur, 0);
  }else{
    sqlite3VdbeAddOp(v, OP_Close, newIdx, 0);
    sqlite3VdbeAddOp(v, OP_Close, oldIdx, 0);
  }



  /*
  ** Return the number of rows that were changed.
  */
  if( db->flags & SQLITE_CountRows && !pParse->trigStack ){
    sqlite3VdbeAddOp(v, OP_Callback, 1, 0);
    sqlite3VdbeSetNumCols(v, 1);
    sqlite3VdbeSetColName(v, 0, "rows updated", P3_STATIC);

**
** Various scripts scan this source file in order to generate HTML
** documentation, headers files, or other derived files.  The formatting
** of the code in this file is, therefore, important.  See other comments
** in this file for details.  If in doubt, do not deviate from existing
** commenting and indentation practices when changing or adding code.
**
** $Id: vdbe.c,v 1.416 2004/10/04 13:19:24 drh Exp $
*/
#include "sqliteInt.h"
#include "os.h"
#include <ctype.h>
#include "vdbeInt.h"

/*
................................................................................
** file used for temporary tables.
**
** If P2 is non-zero, then a write-transaction is started.  A RESERVED lock is
** obtained on the database file when a write-transaction is started.  No
** other process can start another write transaction while this transaction is
** underway.  Starting a write transaction also creates a rollback journal. A
** write transaction must be started before any changes can be made to the
** database.

**
** If P2 is zero, then a read-lock is obtained on the database file.
*/
case OP_Transaction: {
  int i = pOp->p1;
  Btree *pBt;

**
** Various scripts scan this source file in order to generate HTML
** documentation, headers files, or other derived files.  The formatting
** of the code in this file is, therefore, important.  See other comments
** in this file for details.  If in doubt, do not deviate from existing
** commenting and indentation practices when changing or adding code.
**
** $Id: vdbe.c,v 1.417 2004/10/05 02:41:43 drh Exp $
*/
#include "sqliteInt.h"
#include "os.h"
#include <ctype.h>
#include "vdbeInt.h"

/*
................................................................................
** file used for temporary tables.
**
** If P2 is non-zero, then a write-transaction is started.  A RESERVED lock is
** obtained on the database file when a write-transaction is started.  No
** other process can start another write transaction while this transaction is
** underway.  Starting a write transaction also creates a rollback journal. A
** write transaction must be started before any changes can be made to the
** database.  If P2 is 2 or greater then an EXCLUSIVE lock is also obtained
** on the file.
**
** If P2 is zero, then a read-lock is obtained on the database file.
*/
case OP_Transaction: {
  int i = pOp->p1;
  Btree *pBt;

# 2001 September 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.  The
# focus of this script is database locks and the operation of the
# DEFERRED, IMMEDIATE, and EXCLUSIVE keywords as modifiers to the
# BEGIN command.
#
# $Id: lock3.test,v 1.1 2004/10/05 02:41:43 drh Exp $


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

# Establish two connections to the same database.  Put some
# sample data into the database.
#
do_test lock3-1.1 {
  sqlite3 db2 test.db
  execsql {
    CREATE TABLE t1(a);
    INSERT INTO t1 VALUES(1);
  }
  execsql {
    SELECT * FROM t1
  } db2
} 1

# Get a deferred lock on the database using one connection.  The
# other connection should still be able to write.
#
do_test lock3-2.1 {
  execsql {BEGIN DEFERRED TRANSACTION}
  execsql {INSERT INTO t1 VALUES(2)} db2
  execsql {END TRANSACTION}
  execsql {SELECT * FROM t1}
} {1 2}

# Get an immediate lock on the database using one connection.  The
# other connection should be able to read the database but not write
# it.
#
do_test lock3-3.1 {
  execsql {BEGIN IMMEDIATE TRANSACTION}
  catchsql {SELECT * FROM t1} db2
} {0 {1 2}}
do_test lock3-3.2 {
  catchsql {INSERT INTO t1 VALUES(3)} db2
} {1 {database is locked}}
do_test lock3-3.3 {
  execsql {END TRANSACTION}
} {}


# Get an exclusive lock on the database using one connection.  The
# other connection should be unable to read or write the database.
#
do_test lock3-4.1 {
  execsql {BEGIN EXCLUSIVE TRANSACTION}
  catchsql {SELECT * FROM t1} db2
} {1 {database is locked}}
do_test lock3-4.2 {
  catchsql {INSERT INTO t1 VALUES(3)} db2
} {1 {database is locked}}
do_test lock3-4.3 {
  execsql {END TRANSACTION}
} {}

catch {db2 close}

finish_test

#    May you find forgiveness for yourself and forgive others.
#    May you share freely, never taking more than you give.
#
#***********************************************************************
# This file implements regression tests for SQLite library.  The
# focus of this script is page cache subsystem.
#
# $Id: pager2.test,v 1.3 2004/09/08 20:13:06 drh Exp $


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

if {[info commands pager_open]!=""} {
db close
................................................................................
  set v [catch {
    page_write $::g1 "Page-One"
  } msg]
  lappend v $msg
} {0 {}}
do_test pager2-2.15 {
  pager_stats $::p1
} {ref 1 page 1 max 10 size 1 state 3 err 0 hit 1 miss 1 ovfl 0}
do_test pager2-2.16 {
  page_read $::g1
} {Page-One}
do_test pager2-2.17 {
  set v [catch {
    pager_commit $::p1
  } msg]
................................................................................
      }
    }
    set res
  } {}
  do_test pager2-4.5.$i.1 {
    page_write $g1 "Page-1 v$i"
    lrange [pager_stats $p1] 8 9
  } {state 3}
  do_test pager2-4.5.$i.2 {
    for {set j 2} {$j<=20} {incr j} {
      set gx [page_get $p1 $j]
      page_write $gx "Page-$j v$i"
      page_unref $gx
      if {$j==$i} {
        pager_stmt_begin $p1
................................................................................
      }
    }
    set res
  } {}
  do_test pager2-4.5.$i.5 {
    page_write $g1 "Page-1 v$i"
    lrange [pager_stats $p1] 8 9
  } {state 3}
  do_test pager2-4.5.$i.6 {
    for {set j 2} {$j<=20} {incr j} {
      set gx [page_get $p1 $j]
      page_write $gx "Page-$j v$i"
      page_unref $gx
      if {$j==$i} {
        pager_stmt_begin $p1

#    May you find forgiveness for yourself and forgive others.
#    May you share freely, never taking more than you give.
#
#***********************************************************************
# This file implements regression tests for SQLite library.  The
# focus of this script is page cache subsystem.
#
# $Id: pager2.test,v 1.4 2004/10/05 02:41:43 drh Exp $


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

if {[info commands pager_open]!=""} {
db close
................................................................................
  set v [catch {
    page_write $::g1 "Page-One"
  } msg]
  lappend v $msg
} {0 {}}
do_test pager2-2.15 {
  pager_stats $::p1
} {ref 1 page 1 max 10 size 1 state 4 err 0 hit 1 miss 1 ovfl 0}
do_test pager2-2.16 {
  page_read $::g1
} {Page-One}
do_test pager2-2.17 {
  set v [catch {
    pager_commit $::p1
  } msg]
................................................................................
      }
    }
    set res
  } {}
  do_test pager2-4.5.$i.1 {
    page_write $g1 "Page-1 v$i"
    lrange [pager_stats $p1] 8 9
  } {state 4}
  do_test pager2-4.5.$i.2 {
    for {set j 2} {$j<=20} {incr j} {
      set gx [page_get $p1 $j]
      page_write $gx "Page-$j v$i"
      page_unref $gx
      if {$j==$i} {
        pager_stmt_begin $p1
................................................................................
      }
    }
    set res
  } {}
  do_test pager2-4.5.$i.5 {
    page_write $g1 "Page-1 v$i"
    lrange [pager_stats $p1] 8 9
  } {state 4}
  do_test pager2-4.5.$i.6 {
    for {set j 2} {$j<=20} {incr j} {
      set gx [page_get $p1 $j]
      page_write $gx "Page-$j v$i"
      page_unref $gx
      if {$j==$i} {
        pager_stmt_begin $p1

#
# Run this Tcl script to generate the sqlite.html file.
#
set rcsid {$Id: lang.tcl,v 1.72 2004/09/08 13:06:21 drh Exp $}
source common.tcl
header {Query Language Understood by SQLite}
puts {
<h2>SQL As Understood By SQLite</h2>

<p>The SQLite library understands most of the standard SQL
language.  But it does <a href="omitted.html">omit some features</a>
................................................................................
<p>There is a compile-time limit of 10 attached database files.</p>
}


Section {BEGIN TRANSACTION} transaction

Syntax {sql-statement} {
BEGIN [TRANSACTION [<name>]]
}
Syntax {sql-statement} {
END [TRANSACTION [<name>]]
}
Syntax {sql-statement} {
COMMIT [TRANSACTION [<name>]]
}
................................................................................
ROLLBACK if the database is closed or if an error occurs
and the ROLLBACK conflict resolution algorithm is specified.
See the documention on the <a href="#conflict">ON CONFLICT</a>
clause for additional information about the ROLLBACK
conflict resolution algorithm.
</p>





































<p>
The COMMIT command does not actually perform a commit until all
pending SQL commands finish.  Thus if two or more SELECT statements
are in the middle of processing and a COMMIT is executed, the commit
will not actually occur until all SELECT statements finish.
</p>

#
# Run this Tcl script to generate the sqlite.html file.
#
set rcsid {$Id: lang.tcl,v 1.73 2004/10/05 02:41:43 drh Exp $}
source common.tcl
header {Query Language Understood by SQLite}
puts {
<h2>SQL As Understood By SQLite</h2>

<p>The SQLite library understands most of the standard SQL
language.  But it does <a href="omitted.html">omit some features</a>
................................................................................
<p>There is a compile-time limit of 10 attached database files.</p>
}


Section {BEGIN TRANSACTION} transaction

Syntax {sql-statement} {
BEGIN [ DEFERRED | IMMEDIATE | EXCLUSIVE ] [TRANSACTION [<name>]]
}
Syntax {sql-statement} {
END [TRANSACTION [<name>]]
}
Syntax {sql-statement} {
COMMIT [TRANSACTION [<name>]]
}
................................................................................
ROLLBACK if the database is closed or if an error occurs
and the ROLLBACK conflict resolution algorithm is specified.
See the documention on the <a href="#conflict">ON CONFLICT</a>
clause for additional information about the ROLLBACK
conflict resolution algorithm.
</p>

<p>
In SQLite version 3.0.8 and later, transactions can be deferred,
immediate, or exclusive.  Deferred means that no locks are acquired
on the database until the database is first accessed.  Thus with a
deferred transaction, the BEGIN statement itself does nothing.  Locks
are not acquired until the first read or write operation.  The first read
operation against a database creates a SHARED lock and the first
write operation creates a RESERVED lock.   Because the acquisition of
locks is deferred until they are needed, it is possible that another
thread or process could create a separate transaction and write to
the database after the BEGIN on the current thread has executed.
If the transation is immediate, then RESERVED locks
are acquired on all databases as soon as the BEGIN command is
executed, without waiting for the
database to be used.  After a BEGIN IMMEDIATE, you are guaranteed that
no other thread or process will be able to write to the database or
do a BEGIN IMMEDIATE or BEGIN EXCLUSIVE.  Other processes can continue
to read from the database, however.  An exclusive transaction causes
EXCLUSIVE locks to be acquired on all databases.  After a BEGIN
EXCLUSIVE, you are guaranteed that no other thread or process will
be able to read or write the database until the transaction is
complete.
</p>

<p>
A description of the meaning of SHARED, RESERVED, and EXCLUSIVE locks
is available <a href="lockingv3.html">separately</a>.
</p>

<p>
The default behavior for SQLite version 3.0.8 is a
deferred transaction.  For SQLite version 3.0.0 through 3.0.7,
deferred is the only kind of transaction available.  For SQLite
version 2.8 and earlier, all transactions are exclusive.
</p>

<p>
The COMMIT command does not actually perform a commit until all
pending SQL commands finish.  Thus if two or more SELECT statements
are in the middle of processing and a COMMIT is executed, the commit
will not actually occur until all SELECT statements finish.
</p>