SQLite

/*
** 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.
**
*************************************************************************
** $Id: btree.c,v 1.84 2003/03/19 03:14:01 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.

    rc = freePage(pBt, pPage, iTable);
  }else{
    zeroPage(pBt, pPage);
  }
  sqlitepager_unref(pPage);
  return rc;  
}

#if 0 /* UNTESTED */
/*
** Copy all cell data from one database file into another.
** pages back the freelist.
*/
static int copyCell(Btree *pBtFrom, BTree *pBtTo, Cell *pCell){
  Pager *pFromPager = pBtFrom->pPager;
  OverflowPage *pOvfl;
  Pgno ovfl, nextOvfl;
  Pgno *pPrev;
  int rc = SQLITE_OK;
  MemPage *pNew, *pPrevPg;
  Pgno new;

  if( NKEY(pBtTo, pCell->h) + NDATA(pBtTo, pCell->h) <= MX_LOCAL_PAYLOAD ){
    return SQLITE_OK;
  }
  pPrev = &pCell->ovfl;
  pPrevPg = 0;
  ovfl = SWAB32(pBtTo, pCell->ovfl);
  while( ovfl && rc==SQLITE_OK ){
    rc = sqlitepager_get(pFromPager, ovfl, (void**)&pOvfl);
    if( rc ) return rc;
    nextOvfl = SWAB32(pBtFrom, pOvfl->iNext);
    rc = allocatePage(pBtTo, &pNew, &new, 0);
    if( rc==SQLITE_OK ){
      rc = sqlitepager_write(pNew);
      if( rc==SQLITE_OK ){
        memcpy(pNew, pOvfl, SQLITE_PAGE_SIZE);
        *pPrev = SWAB32(pBtTo, new);
        if( pPrevPg ){
          sqlitepager_unref(pPrevPg);
        }
        pPrev = &pOvfl->iNext;
        pPrevPg = pNew;
      }
    }
    sqlitepager_unref(pOvfl);
    ovfl = nextOvfl;
  }
  if( pPrevPg ){
    sqlitepager_unref(pPrevPg);
  }
  return rc;
}
#endif


#if 0 /* UNTESTED */
/*
** Copy a page of data from one database over to another.
*/
static int copyDatabasePage(
  Btree *pBtFrom,
  Pgno pgnoFrom,
  Btree *pBtTo,
  Pgno *pTo
){
  MemPage *pPageFrom, *pPage;
  Pgno to;
  int rc;
  Cell *pCell;
  int idx;

  rc = sqlitepager_get(pBtFrom->pPager, pgno, (void**)&pPageFrom);
  if( rc ) return rc;
  rc = allocatePage(pBt, &pPage, pTo, 0);
  if( rc==SQLITE_OK ){
    rc = sqlitepager_write(pPage);
  }
  if( rc==SQLITE_OK ){
    memcpy(pPage, pPageFrom, SQLITE_PAGE_SIZE);
    idx = SWAB16(pBt, pPage->u.hdr.firstCell);
    while( idx>0 ){
      pCell = (Cell*)&pPage->u.aDisk[idx];
      idx = SWAB16(pBt, pCell->h.iNext);
      if( pCell->h.leftChild ){
        Pgno newChld;
        rc = copyDatabasePage(pBtFrom, SWAB32(pBtFrom, pCell->h.leftChild),
                              pBtTo, &newChld);
        if( rc ) return rc;
        pCell->h.leftChild = SWAB32(pBtFrom, newChld);
      }
      rc = copyCell(pBtFrom, pBtTo, pCell);
      if( rc ) return rc;
    }
    if( pPage->u.hdr.rightChild ){
      Pgno newChld;
      rc = copyDatabasePage(pBtFrom, SWAB32(pBtFrom, pPage->u.hdr.rightChild), 
                            pBtTo, &newChld);
      if( rc ) return rc;
      pPage->u.hdr.rightChild = SWAB32(pBtTo, newChild);
    }
  }
  sqlitepager_unref(pPage);
  return rc;
}
#endif

/*
** Read the meta-information out of a database file.
*/
int sqliteBtreeGetMeta(Btree *pBt, int *aMeta){
  PageOne *pP1;
  int rc;

**    May you share freely, never taking more than you give.
**
*************************************************************************
** This header file defines the interface that the sqlite B-Tree file
** subsystem.  See comments in the source code for a detailed description
** of what each interface routine does.
**
** @(#) $Id: btree.h,v 1.28 2003/03/19 03:14:01 drh Exp $
*/
#ifndef _BTREE_H_
#define _BTREE_H_

typedef struct Btree Btree;
typedef struct BtCursor BtCursor;

int sqliteBtreeCommitCkpt(Btree*);
int sqliteBtreeRollbackCkpt(Btree*);

int sqliteBtreeCreateTable(Btree*, int*);
int sqliteBtreeCreateIndex(Btree*, int*);
int sqliteBtreeDropTable(Btree*, int);
int sqliteBtreeClearTable(Btree*, int);
int sqliteBtreeCopyTable(Btree *pFrom, int iFrom, Btree *pTo, int iTo);

int sqliteBtreeCursor(Btree*, int iTable, int wrFlag, BtCursor **ppCur);
int sqliteBtreeMoveto(BtCursor*, const void *pKey, int nKey, int *pRes);
int sqliteBtreeDelete(BtCursor*);
int sqliteBtreeInsert(BtCursor*, const void *pKey, int nKey,
                                 const void *pData, int nData);
int sqliteBtreeFirst(BtCursor*, int *pRes);

**     COPY
**     VACUUM
**     BEGIN TRANSACTION
**     COMMIT
**     ROLLBACK
**     PRAGMA
**
** $Id: build.c,v 1.132 2003/03/19 03:14:01 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

  if( v && pParse->nErr==0 ){
    FILE *trace = (db->flags & SQLITE_VdbeTrace)!=0 ? stdout : 0;
    sqliteVdbeTrace(v, trace);
    sqliteVdbeMakeReady(v, xCallback, pParse->pArg, pParse->explain);
    if( pParse->useCallback ){
      if( pParse->explain ){
        rc = sqliteVdbeList(v);
        db->next_cookie = db->aDb[0].schema_cookie;
      }else{
        sqliteVdbeExec(v);
      }
      rc = sqliteVdbeFinalize(v, &pParse->zErrMsg);
      if( rc ) pParse->nErr++;
      pParse->pVdbe = 0;
      pParse->rc = rc;

  }
}

/*
** This routine is called when a commit occurs.
*/
void sqliteCommitInternalChanges(sqlite *db){
  db->aDb[0].schema_cookie = db->next_cookie;
  db->flags &= ~SQLITE_InternChanges;
}

/*
** Remove the memory data structures associated with the given
** Table.  No changes are made to disk by this routine.
**

/*
** Generate code to open the appropriate master table.  The table
** opened will be SQLITE_MASTER for persistent tables and 
** SQLITE_TEMP_MASTER for temporary tables.  The table is opened
** on cursor 0.
*/
void sqliteOpenMasterTable(Vdbe *v, int isTemp){

  sqliteVdbeAddOp(v, OP_Integer, isTemp, 0);


  sqliteVdbeAddOp(v, OP_OpenWrite, 0, 2);


}

/*
** Begin constructing a new table representation in memory.  This is
** the first of several action routines that get called in response
** to a CREATE TABLE statement.  In particular, this routine is called
** after seeing tokens "CREATE" and "TABLE" and the table name.  The

  }
#endif
 

  /* Before trying to create a temporary table, make sure the Btree for
  ** holding temporary tables is open.
  */
  if( isTemp && db->aDb[1].pBt==0 ){
    int rc = sqliteBtreeOpen(0, 0, MAX_PAGES, &db->aDb[1].pBt);
    if( rc!=SQLITE_OK ){
      sqliteSetString(&pParse->zErrMsg, "unable to open a temporary database "
        "file for storing temporary tables", 0);
      pParse->nErr++;
      return;
    }
    if( db->flags & SQLITE_InTrans ){
      rc = sqliteBtreeBeginTrans(db->aDb[1].pBt);
      if( rc!=SQLITE_OK ){
        sqliteSetNString(&pParse->zErrMsg, "unable to get a write lock on "
          "the temporary database file", 0);
        pParse->nErr++;
        return;
      }
    }

** This plan is not completely bullet-proof.  It is possible for
** the schema to change multiple times and for the cookie to be
** set back to prior value.  But schema changes are infrequent
** and the probability of hitting the same cookie value is only
** 1 chance in 2^32.  So we're safe enough.
*/
void sqliteChangeCookie(sqlite *db, Vdbe *v){
  if( db->next_cookie==db->aDb[0].schema_cookie ){
    db->next_cookie = db->aDb[0].schema_cookie + sqliteRandomByte() + 1;
    db->flags |= SQLITE_InternChanges;
    sqliteVdbeAddOp(v, OP_Integer, db->next_cookie, 0);
    sqliteVdbeAddOp(v, OP_SetCookie, 0, 0);
  }
}

/*

    sqliteVdbeAddOp(v, OP_MakeRecord, 5, 0);
    sqliteVdbeAddOp(v, OP_PutIntKey, 0, 0);
    if( !p->isTemp ){
      sqliteChangeCookie(db, v);
    }
    sqliteVdbeAddOp(v, OP_Close, 0, 0);
    if( pSelect ){
      sqliteVdbeAddOp(v, OP_Integer, p->isTemp, 0);
      sqliteVdbeAddOp(v, OP_OpenWrite, 1, 0);
      pParse->nTab = 2;
      sqliteSelect(pParse, pSelect, SRT_Table, 1, 0, 0, 0);
    }
    sqliteEndWriteOperation(pParse);
  }

  /* Add the table to the in-memory representation of the database.

    sqliteVdbeAddOp(v, OP_String, 0, 0);
    sqliteVdbeChangeP3(v, -1, pTab->zName, P3_STATIC);
    addr = sqliteVdbeAddOp(v, OP_CreateIndex, 0, isTemp);
    sqliteVdbeChangeP3(v, addr, (char*)&pIndex->tnum, P3_POINTER);
    pIndex->tnum = 0;
    if( pTable ){
      sqliteVdbeAddOp(v, OP_Dup, 0, 0);

      sqliteVdbeAddOp(v, OP_Integer, isTemp, 0);

      sqliteVdbeAddOp(v, OP_OpenWrite, 1, 0);

    }
    addr = sqliteVdbeAddOp(v, OP_String, 0, 0);
    if( pStart && pEnd ){
      n = Addr(pEnd->z) - Addr(pStart->z) + 1;
      sqliteVdbeChangeP3(v, addr, pStart->z, n);
    }
    sqliteVdbeAddOp(v, OP_MakeRecord, 5, 0);
    sqliteVdbeAddOp(v, OP_PutIntKey, 0, 0);
    if( pTable ){
      sqliteVdbeAddOp(v, OP_Integer, isTemp, 0);
      sqliteVdbeAddOp(v, OP_OpenRead, 2, pTab->tnum);
      sqliteVdbeChangeP3(v, -1, pTab->zName, P3_STATIC);
      lbl2 = sqliteVdbeMakeLabel(v);
      sqliteVdbeAddOp(v, OP_Rewind, 2, lbl2);
      lbl1 = sqliteVdbeAddOp(v, OP_Recno, 2, 0);
      for(i=0; i<pIndex->nColumn; i++){
        sqliteVdbeAddOp(v, OP_Column, 2, pIndex->aiColumn[i]);
      }

  sqliteDequote(zFile);
  if( sqliteAuthCheck(pParse, SQLITE_INSERT, pTab->zName, zFile)
      || sqliteAuthCheck(pParse, SQLITE_COPY, pTab->zName, zFile) ){
    goto copy_cleanup;
  }
  v = sqliteGetVdbe(pParse);
  if( v ){

    sqliteBeginWriteOperation(pParse, 1, pTab->isTemp);
    addr = sqliteVdbeAddOp(v, OP_FileOpen, 0, 0);
    sqliteVdbeChangeP3(v, addr, pFilename->z, pFilename->n);
    sqliteVdbeDequoteP3(v, addr);
    sqliteVdbeAddOp(v, OP_Integer, pTab->isTemp, 0);
    sqliteVdbeAddOp(v, OP_OpenWrite, 0, pTab->tnum);
    sqliteVdbeChangeP3(v, -1, pTab->zName, P3_STATIC);
    for(i=1, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, i++){
      sqliteVdbeAddOp(v, OP_Integer, pTab->isTemp, 0);
      sqliteVdbeAddOp(v, OP_OpenWrite, i, pIdx->tnum);
      sqliteVdbeChangeP3(v, -1, pIdx->zName, P3_STATIC);
    }
    if( db->flags & SQLITE_CountRows ){
      sqliteVdbeAddOp(v, OP_Integer, 0, 0);  /* Initialize the row count */
    }
    end = sqliteVdbeMakeLabel(v);
    addr = sqliteVdbeAddOp(v, OP_FileRead, pTab->nCol, end);

/*
** Begin a transaction
*/
void sqliteBeginTransaction(Parse *pParse, int onError){
  sqlite *db;

  if( pParse==0 || (db=pParse->db)==0 || db->aDb[0].pBt==0 ) return;
  if( pParse->nErr || sqlite_malloc_failed ) return;
  if( sqliteAuthCheck(pParse, SQLITE_TRANSACTION, "BEGIN", 0) ) return;
  if( db->flags & SQLITE_InTrans ){
    pParse->nErr++;
    sqliteSetString(&pParse->zErrMsg, "cannot start a transaction "
       "within a transaction", 0);
    return;
  }
  sqliteBeginWriteOperation(pParse, 0, 0);
  db->flags |= SQLITE_InTrans;
  db->onError = onError;
}

/*
** Commit a transaction
*/
void sqliteCommitTransaction(Parse *pParse){
  sqlite *db;

  if( pParse==0 || (db=pParse->db)==0 || db->aDb[0].pBt==0 ) return;
  if( pParse->nErr || sqlite_malloc_failed ) return;
  if( sqliteAuthCheck(pParse, SQLITE_TRANSACTION, "COMMIT", 0) ) return;
  if( (db->flags & SQLITE_InTrans)==0 ){
    pParse->nErr++;
    sqliteSetString(&pParse->zErrMsg, 
       "cannot commit - no transaction is active", 0);
    return;
  }
  db->flags &= ~SQLITE_InTrans;
  sqliteEndWriteOperation(pParse);
  db->onError = OE_Default;
}

/*
** Rollback a transaction
*/
void sqliteRollbackTransaction(Parse *pParse){
  sqlite *db;
  Vdbe *v;

  if( pParse==0 || (db=pParse->db)==0 || db->aDb[0].pBt==0 ) return;
  if( pParse->nErr || sqlite_malloc_failed ) return;
  if( sqliteAuthCheck(pParse, SQLITE_TRANSACTION, "ROLLBACK", 0) ) return;
  if( (db->flags & SQLITE_InTrans)==0 ){
    pParse->nErr++;
    sqliteSetString(&pParse->zErrMsg,
       "cannot rollback - no transaction is active", 0);
    return; 
  }
  v = sqliteGetVdbe(pParse);
  if( v ){
    sqliteVdbeAddOp(v, OP_Rollback, 0, 0);
  }
  db->flags &= ~SQLITE_InTrans;
  db->onError = OE_Default;
}

/*
** Generate VDBE code that will verify the schema cookie for all
** named database files.
*/
void sqliteCodeVerifySchema(Parse *pParse){
  int i;
  sqlite *db = pParse->db;
  Vdbe *v = sqliteGetVdbe(pParse);
  for(i=0; i<db->nDb; i++){
    if( db->aDb[i].zName==0 || db->aDb[i].pBt==0 ) continue;
    sqliteVdbeAddOp(v, OP_VerifyCookie, 0, db->aDb[i].schema_cookie);
  }
  pParse->schemaVerified = 1;
}

/*
** Generate VDBE code that prepares for doing an operation that
** might change the database.
**
** This routine starts a new transaction if we are not already within
** a transaction.  If we are already within a transaction, then a checkpoint

*/
void sqliteBeginWriteOperation(Parse *pParse, int setCheckpoint, int tempOnly){
  Vdbe *v;
  v = sqliteGetVdbe(pParse);
  if( v==0 ) return;
  if( pParse->trigStack ) return; /* if this is in a trigger */
  if( (pParse->db->flags & SQLITE_InTrans)==0 ){
    sqliteVdbeAddOp(v, OP_Transaction, 1, 0);
    if( !tempOnly ){
      sqliteVdbeAddOp(v, OP_Transaction, 0, 0);
      sqliteCodeVerifySchema(pParse);
    }
  }else if( setCheckpoint ){
    sqliteVdbeAddOp(v, OP_Checkpoint, 0, 0);
    sqliteVdbeAddOp(v, OP_Checkpoint, 1, 0);
  }
}

/*
** Generate code that concludes an operation that may have changed
** the database.  This is a companion function to BeginWriteOperation().
** If a transaction was started, then commit it.  If a checkpoint was

      sqliteVdbeAddOp(v, OP_ReadCookie, 0, 2);
      addr = sqliteVdbeAddOp(v, OP_Integer, 0, 0);
      sqliteVdbeAddOp(v, OP_Ge, 0, addr+3);
      sqliteVdbeAddOp(v, OP_Negative, 0, 0);
      sqliteVdbeAddOp(v, OP_SetCookie, 0, 2);
      sqliteEndWriteOperation(pParse);
      db->cache_size = db->cache_size<0 ? -size : size;
      sqliteBtreeSetCacheSize(db->aDb[0].pBt, db->cache_size);
    }
  }else

  /*
  **  PRAGMA cache_size
  **  PRAGMA cache_size=N
  **

      sqliteVdbeAddOp(v, OP_Integer, size, 0);
      sqliteVdbeAddOpList(v, ArraySize(getCacheSize), getCacheSize);
    }else{
      int size = atoi(zRight);
      if( size<0 ) size = -size;
      if( db->cache_size<0 ) size = -size;
      db->cache_size = size;
      sqliteBtreeSetCacheSize(db->aDb[0].pBt, db->cache_size);
    }
  }else

  /*
  **  PRAGMA default_synchronous
  **  PRAGMA default_synchronous=ON|OFF|NORMAL|FULL
  **

        size = -size;
      }
      sqliteVdbeAddOp(v, OP_SetCookie, 0, 2);
      sqliteVdbeAddOp(v, OP_Integer, db->safety_level, 0);
      sqliteVdbeAddOp(v, OP_SetCookie, 0, 3);
      sqliteEndWriteOperation(pParse);
      db->cache_size = size;
      sqliteBtreeSetCacheSize(db->aDb[0].pBt, db->cache_size);
      sqliteBtreeSetSafetyLevel(db->aDb[0].pBt, db->safety_level);
    }
  }else

  /*
  **   PRAGMA synchronous
  **   PRAGMA synchronous=OFF|ON|NORMAL|FULL
  **

      sqliteVdbeAddOpList(v, ArraySize(getSync), getSync);
    }else{
      int size = db->cache_size;
      if( size<0 ) size = -size;
      db->safety_level = getSafetyLevel(zRight)+1;
      if( db->safety_level==1 ) size = -size;
      db->cache_size = size;
      sqliteBtreeSetCacheSize(db->aDb[0].pBt, db->cache_size);
      sqliteBtreeSetSafetyLevel(db->aDb[0].pBt, db->safety_level);
    }
  }else

  if( sqliteStrICmp(zLeft, "trigger_overhead_test")==0 ){
    if( getBoolean(zRight) ){
      always_code_trigger_setup = 1;
    }else{

    }
  }else
#endif

  if( sqliteStrICmp(zLeft, "integrity_check")==0 ){
    static VdbeOp checkDb[] = {
      { OP_SetInsert,   0, 0,        "2"},
      { OP_Integer,     0, 0,        0},   
      { OP_OpenRead,    0, 2,        0},
      { OP_Rewind,      0, 7,        0},
      { OP_Column,      0, 3,        0},    /* 4 */
      { OP_SetInsert,   0, 0,        0},
      { OP_Next,        0, 4,        0},
      { OP_IntegrityCk, 0, 0,        0},    /* 7 */
      { OP_ColumnName,  0, 0,        "integrity_check"},
      { OP_Callback,    1, 0,        0},
      { OP_SetInsert,   1, 0,        "2"},
      { OP_Integer,     1, 0,        0},
      { OP_OpenRead,    1, 2,        0},
      { OP_Rewind,      1, 17,       0},
      { OP_Column,      1, 3,        0},    /* 14 */
      { OP_SetInsert,   1, 0,        0},
      { OP_Next,        1, 14,       0},
      { OP_IntegrityCk, 1, 1,        0},    /* 17 */
      { OP_Callback,    1, 0,        0},
    };
    sqliteVdbeAddOpList(v, ArraySize(checkDb), checkDb);
  }else

  {}
  sqliteFree(zLeft);
  sqliteFree(zRight);
}

**    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 1.46 2003/03/19 03:14:01 drh Exp $
*/
#include "sqliteInt.h"


/*
** Given a table name, find the corresponding table and make sure the
** table is writeable.  Generate an error and return NULL if not.  If

  SrcList *pTabList;     /* A fake FROM clause holding just pTab */
  int end, addr;         /* A couple addresses of generated code */
  int i;                 /* Loop counter */
  WhereInfo *pWInfo;     /* Information about the WHERE clause */
  Index *pIdx;           /* For looping over indices of the table */
  int base;              /* Index of the first available table cursor */
  sqlite *db;            /* Main database structure */


  int row_triggers_exist = 0;
  int oldIdx = -1;

  if( pParse->nErr || sqlite_malloc_failed ){
    pTabList = 0;
    goto delete_from_cleanup;

  */
  if( pWhere==0 && !row_triggers_exist ){
    if( db->flags & SQLITE_CountRows ){
      /* If counting rows deleted, just count the total number of
      ** entries in the table. */
      int endOfLoop = sqliteVdbeMakeLabel(v);
      int addr;
      sqliteVdbeAddOp(v, OP_Integer, pTab->isTemp, 0);
      sqliteVdbeAddOp(v, OP_OpenRead, base, pTab->tnum);
      sqliteVdbeAddOp(v, OP_Rewind, base, sqliteVdbeCurrentAddr(v)+2);
      addr = sqliteVdbeAddOp(v, OP_AddImm, 1, 0);
      sqliteVdbeAddOp(v, OP_Next, base, addr);
      sqliteVdbeResolveLabel(v, endOfLoop);
      sqliteVdbeAddOp(v, OP_Close, base, 0);
    }
    sqliteVdbeAddOp(v, OP_Clear, pTab->tnum, pTab->isTemp);

    /* This is the beginning of the delete loop when there are
    ** row triggers.
    */
    if( row_triggers_exist ){
      addr = sqliteVdbeAddOp(v, OP_ListRead, 0, end);
      sqliteVdbeAddOp(v, OP_Dup, 0, 0);
      sqliteVdbeAddOp(v, OP_Integer, pTab->isTemp, 0);

      sqliteVdbeAddOp(v, OP_OpenRead, base, pTab->tnum);
      sqliteVdbeAddOp(v, OP_MoveTo, base, 0);
      sqliteVdbeAddOp(v, OP_OpenTemp, oldIdx, 0);

      sqliteVdbeAddOp(v, OP_Integer, 13, 0);
      for(i = 0; i<pTab->nCol; i++){
        if( i==pTab->iPKey ){ 
          sqliteVdbeAddOp(v, OP_Recno, base, 0);

    /* Open cursors for the table we are deleting from and all its
    ** indices.  If there are row triggers, this happens inside the
    ** OP_ListRead loop because the cursor have to all be closed
    ** before the trigger fires.  If there are no row triggers, the
    ** cursors are opened only once on the outside the loop.
    */
    pParse->nTab = base + 1;
    sqliteVdbeAddOp(v, OP_Integer, pTab->isTemp, 0);
    sqliteVdbeAddOp(v, OP_OpenWrite, base, pTab->tnum);
    for(i=1, pIdx=pTab->pIndex; pIdx; i++, pIdx=pIdx->pNext){
      sqliteVdbeAddOp(v, OP_Integer, pTab->isTemp, 0);
      sqliteVdbeAddOp(v, OP_OpenWrite, pParse->nTab++, pIdx->tnum);
    }

    /* This is the beginning of the delete loop when there are no
    ** row triggers */
    if( !row_triggers_exist ){ 
      addr = sqliteVdbeAddOp(v, OP_ListRead, 0, end);
    }

**    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 1.73 2003/03/19 03:14:01 drh Exp $
*/
#include "sqliteInt.h"

/*
** This routine is call to handle SQL of the following forms:
**
**    insert into TABLE (IDLIST) values(EXPRLIST)

  int i, j, idx;        /* Loop counters */
  Vdbe *v;              /* Generate code into this virtual machine */
  Index *pIdx;          /* For looping over indices of the table */
  int nColumn;          /* Number of columns in the data */
  int base;             /* First available cursor */
  int iCont, iBreak;    /* Beginning and end of the loop over srcTab */
  sqlite *db;           /* The main database structure */

  int keyColumn = -1;   /* Column that is the INTEGER PRIMARY KEY */
  int endOfLoop;        /* Label for the end of the insertion loop */
  int useTempTable;     /* Store SELECT results in intermediate table */
  int srcTab;           /* Data comes from this temporary cursor if >=0 */
  int iSelectLoop;      /* Address of code that implements the SELECT */
  int iCleanup;         /* Address of the cleanup code */
  int iInsertBlock;     /* Address of the subroutine used to insert data */

    assert( pSelect->pEList );
    nColumn = pSelect->pEList->nExpr;

    /* Set useTempTable to TRUE if the result of the SELECT statement
    ** should be written into a temporary table.  Set to FALSE if each
    ** row of the SELECT can be written directly into the result table.
    */
    opCode = pTab->isTemp ? OP_OpenTemp : OP_OpenRead;
    useTempTable = row_triggers_exist || sqliteVdbeFindOp(v,opCode,pTab->tnum);

    if( useTempTable ){
      /* Generate the subroutine that SELECT calls to process each row of
      ** the result.  Store the result in a temporary table
      */
      srcTab = pParse->nTab++;

    sqliteVdbeAddOp(v, OP_Integer, 0, 0);
    sqliteVdbeAddOp(v, OP_MemStore, iCntMem, 1);
  }

  /* Open tables and indices if there are no row triggers */
  if( !row_triggers_exist ){
    base = pParse->nTab;
    sqliteVdbeAddOp(v, OP_Integer, pTab->isTemp, 0);
    sqliteVdbeAddOp(v, OP_OpenWrite, base, pTab->tnum);
    sqliteVdbeChangeP3(v, -1, pTab->zName, P3_STATIC);
    for(idx=1, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, idx++){
      sqliteVdbeAddOp(v, OP_Integer, pTab->isTemp, 0);
      sqliteVdbeAddOp(v, OP_OpenWrite, idx+base, pIdx->tnum);
      sqliteVdbeChangeP3(v, -1, pIdx->zName, P3_STATIC);
    }
    pParse->nTab += idx;
  }

  /* If the data source is a temporary table, then we have to create
  ** a loop because there might be multiple rows of data.  If the data

        onError, endOfLoop) ){
      goto insert_cleanup;
    }

    /* Open the tables and indices for the INSERT */
    if( !pTab->pSelect ){
      base = pParse->nTab;
      sqliteVdbeAddOp(v, OP_Integer, pTab->isTemp, 0);
      sqliteVdbeAddOp(v, OP_OpenWrite, base, pTab->tnum);
      sqliteVdbeChangeP3(v, -1, pTab->zName, P3_STATIC);
      for(idx=1, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, idx++){
        sqliteVdbeAddOp(v, OP_Integer, pTab->isTemp, 0);
        sqliteVdbeAddOp(v, OP_OpenWrite, idx+base, pIdx->tnum);
        sqliteVdbeChangeP3(v, -1, pIdx->zName, P3_STATIC);
      }
      pParse->nTab += idx;
    }
  }

  /* Push the record number for the new entry onto the stack.  The

**
*************************************************************************
** Main file for the SQLite library.  The routines in this file
** implement the programmer interface to the library.  Routines in
** other files are for internal use by SQLite and should not be
** accessed by users of the library.
**
** $Id: main.c,v 1.115 2003/03/19 03:14:02 drh Exp $
*/
#include "sqliteInt.h"
#include "os.h"
#include <ctype.h>

/*
** A pointer to this structure is used to communicate information

  pTab = sqliteFindTable(db, TEMP_MASTER_NAME);
  if( pTab ){
    pTab->readOnly = 1;
  }

  /* Create a cursor to hold the database open
  */
  if( db->aDb[0].pBt==0 ) return SQLITE_OK;
  rc = sqliteBtreeCursor(db->aDb[0].pBt, 2, 0, &curMain);
  if( rc ){
    sqliteSetString(pzErrMsg, sqlite_error_string(rc), 0);
    sqliteResetInternalSchema(db);
    return rc;
  }

  /* Get the database meta information
  */
  rc = sqliteBtreeGetMeta(db->aDb[0].pBt, meta);
  if( rc ){
    sqliteSetString(pzErrMsg, sqlite_error_string(rc), 0);
    sqliteResetInternalSchema(db);
    sqliteBtreeCloseCursor(curMain);
    return rc;
  }

  db->next_cookie = db->aDb[0].schema_cookie = meta[1];
  db->file_format = meta[2];
  size = meta[3];
  if( size==0 ){ size = MAX_PAGES; }
  db->cache_size = size;
  sqliteBtreeSetCacheSize(db->aDb[0].pBt, size);
  db->safety_level = meta[4];
  if( db->safety_level==0 ) db->safety_level = 2;
  sqliteBtreeSetSafetyLevel(db->aDb[0].pBt, db->safety_level);

  /*
  **     file_format==1    Version 2.1.0.
  **     file_format==2    Version 2.2.0. Add support for INTEGER PRIMARY KEY.
  **     file_format==3    Version 2.6.0. Fix empty-string index bug.
  **     file_format==4    Version 2.7.0. Add support for separate numeric and
  **                       text datatypes.

    return SQLITE_ERROR;
  }

  /* Read the schema information out of the schema tables
  */
  memset(&sParse, 0, sizeof(sParse));
  sParse.db = db;

  sParse.xCallback = sqliteInitCallback;
  sParse.pArg = (void*)&initData;
  sParse.initFlag = 1;
  sParse.useCallback = 1;
  sqliteRunParser(&sParse,
      db->file_format>=2 ? init_script : older_init_script,
      pzErrMsg);
  if( sqlite_malloc_failed ){
    sqliteSetString(pzErrMsg, "out of memory", 0);
    sParse.rc = SQLITE_NOMEM;
    sqliteBtreeRollback(db->aDb[0].pBt);
    sqliteResetInternalSchema(db);
  }
  if( sParse.rc==SQLITE_OK ){
    db->flags |= SQLITE_Initialized;
    sqliteCommitInternalChanges(db);
  }else{
    db->flags &= ~SQLITE_Initialized;

  sqliteHashInit(&db->idxHash, SQLITE_HASH_STRING, 0);
  sqliteHashInit(&db->trigHash, SQLITE_HASH_STRING, 0);
  sqliteHashInit(&db->aFunc, SQLITE_HASH_STRING, 1);
  sqliteHashInit(&db->aFKey, SQLITE_HASH_STRING, 1);
  db->onError = OE_Default;
  db->priorNewRowid = 0;
  db->magic = SQLITE_MAGIC_BUSY;
  db->nDb = 2;
  db->aDb = db->aDbStatic;
  
  /* Open the backend database driver */
  rc = sqliteBtreeOpen(zFilename, 0, MAX_PAGES, &db->aDb[0].pBt);
  if( rc!=SQLITE_OK ){
    switch( rc ){
      default: {
        sqliteSetString(pzErrMsg, "unable to open database: ", zFilename, 0);
      }
    }
    sqliteFree(db);
    sqliteStrRealloc(pzErrMsg);
    return 0;
  }
  db->aDb[0].zName = "main";

  /* Attempt to read the schema */
  sqliteRegisterBuiltinFunctions(db);
  rc = sqliteInit(db, pzErrMsg);
  db->magic = SQLITE_MAGIC_OPEN;
  if( sqlite_malloc_failed ){
    sqlite_close(db);

    db->file_format = 3;
    rc = sqlite_exec(db,
      "BEGIN; SELECT name FROM sqlite_master WHERE type='table';",
      upgrade_3_callback,
      &initData,
      &zErr);
    if( rc==SQLITE_OK ){
      sqliteBtreeGetMeta(db->aDb[0].pBt, meta);
      meta[2] = 4;
      sqliteBtreeUpdateMeta(db->aDb[0].pBt, meta);
      sqlite_exec(db, "COMMIT", 0, 0, 0);
    }
    if( rc!=SQLITE_OK ){
      sqliteSetString(pzErrMsg, 
        "unable to upgrade database to the version 2.6 format",
        zErr ? ": " : 0, zErr, 0);
      sqlite_freemem(zErr);

}

/*
** Close an existing SQLite database
*/
void sqlite_close(sqlite *db){
  HashElem *i;
  int j;
  db->want_to_close = 1;
  if( sqliteSafetyCheck(db) || sqliteSafetyOn(db) ){
    /* printf("DID NOT CLOSE\n"); fflush(stdout); */
    return;
  }
  db->magic = SQLITE_MAGIC_CLOSED;
  for(j=0; j<db->nDb; j++){
    if( db->aDb[j].pBt ){
      sqliteBtreeClose(db->aDb[j].pBt);

    }
  }
  if( db->aDb!=db->aDbStatic ){
    sqliteFree(db->aDb);
  }
  sqliteResetInternalSchema(db);
  for(i=sqliteHashFirst(&db->aFunc); i; i=sqliteHashNext(i)){
    FuncDef *pFunc, *pNext;
    for(pFunc = (FuncDef*)sqliteHashData(i); pFunc; pFunc=pNext){
      pNext = pFunc->pNext;
      sqliteFree(pFunc);
    }
  }

        break;
      }
    }
    zSql++;
  }
  return seenText && isComplete && requireEnd==0;
}

/*
** Rollback all database files.
*/
void sqliteRollbackAll(sqlite *db){
  int i;
  for(i=0; i<db->nDb; i++){
    if( db->aDb[i].pBt ){
      sqliteBtreeRollback(db->aDb[i].pBt);
      db->aDb[i].inTrans = 0;
    }
  }
  sqliteRollbackInternalChanges(db);
}

/*
** This routine does the work of either sqlite_exec() or sqlite_compile().
** It works like sqlite_exec() if pVm==NULL and it works like sqlite_compile()
** otherwise.
*/
static int sqliteMain(

    sqliteSafetyOff(db);
    sqliteSetString(pzErrMsg, "obsolete database file format", 0);
    return SQLITE_ERROR;
  }
  if( db->pVdbe==0 ){ db->nChange = 0; }
  memset(&sParse, 0, sizeof(sParse));
  sParse.db = db;

  sParse.xCallback = xCallback;
  sParse.pArg = pArg;
  sParse.useCallback = ppVm==0;
#ifndef SQLITE_OMIT_TRACE
  if( db->xTrace ) db->xTrace(db->pTraceArg, zSql);
#endif
  sqliteRunParser(&sParse, zSql, pzErrMsg);
  if( sqlite_malloc_failed ){
    sqliteSetString(pzErrMsg, "out of memory", 0);
    sParse.rc = SQLITE_NOMEM;
    sqliteRollbackAll(db);
    sqliteResetInternalSchema(db);
    db->flags &= ~SQLITE_InTrans;

  }
  if( sParse.rc==SQLITE_DONE ) sParse.rc = SQLITE_OK;
  if( sParse.rc!=SQLITE_OK && pzErrMsg && *pzErrMsg==0 ){
    sqliteSetString(pzErrMsg, sqlite_error_string(sParse.rc), 0);
  }
  sqliteStrRealloc(pzErrMsg);
  if( sParse.rc==SQLITE_SCHEMA ){

** a temporary file to be opened and automatically deleted when closed.
*/
int sqlite_open_aux_file(sqlite *db, const char *zName, char **pzErrMsg){
  int rc;
  if( zName && zName[0]==0 ) zName = 0;
  if( sqliteSafetyOn(db) ) goto openaux_misuse;
  sqliteResetInternalSchema(db);
  if( db->aDb[1].pBt!=0 ){
    sqliteBtreeClose(db->aDb[1].pBt);
  }
  rc = sqliteBtreeOpen(zName, 0, MAX_PAGES, &db->aDb[1].pBt);
  if( rc ){
    if( zName==0 ) zName = "a temporary file";
    sqliteSetString(pzErrMsg, "unable to open ", zName, 
      ": ", sqlite_error_string(rc), 0);
    sqliteStrRealloc(pzErrMsg);
    sqliteSafetyOff(db);
    return rc;

  return GetFileAttributes(zFilename) != 0xffffffff;
#endif
#if OS_MAC
  return access(zFilename, 0)==0;
#endif
}


/*
** Change the name of an existing file.
*/
int sqliteOsRename(const char *zOldName, const char *zNewName){
#if OS_UNIX
  if( link(zOldName, zNewName) ){
    return SQLITE_ERROR;
  }
  unlink(zOldName);
  return SQLITE_OK;
#endif
#if OS_WIN
  if( !MoveFile(zOldName, zNewName) ){
    return SQLITE_ERROR;
  }
  return SQLITE_OK;
#endif
#if OS_MAC
  /**** FIX ME ***/
  return SQLITE_ERROR;
#endif
}


/*
** Attempt to open a file for both reading and writing.  If that
** fails, try opening it read-only.  If the file does not exist,
** try to create it.
**
** On success, a handle for the open file is written to *id

# endif
# define SQLITE_TEMPNAME_SIZE _MAX_PATH
# define SQLITE_MIN_SLEEP_MS 17
#endif

int sqliteOsDelete(const char*);
int sqliteOsFileExists(const char*);
int sqliteOsFileRename(const char*, const char*);
int sqliteOsOpenReadWrite(const char*, OsFile*, int*);
int sqliteOsOpenExclusive(const char*, OsFile*, int);
int sqliteOsOpenReadOnly(const char*, OsFile*);
int sqliteOsTempFileName(char*);
int sqliteOsClose(OsFile*);
int sqliteOsRead(OsFile*, void*, int amt);
int sqliteOsWrite(OsFile*, const void*, int amt);

** 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 1.79 2003/03/19 03:14:02 drh Exp $
*/
#include "os.h"         /* Must be first to enable large file support */
#include "sqliteInt.h"
#include "pager.h"
#include <assert.h>
#include <string.h>

** to sqlitepager_write().  In other words, return TRUE if it is ok
** to change the content of the page.
*/
int sqlitepager_iswriteable(void *pData){
  PgHdr *pPg = DATA_TO_PGHDR(pData);
  return pPg->dirty;
}

/*
** Replace the content of a single page with the information in the third
** argument.
*/
int sqlitepager_overwrite(Pager *pPager, Pgno pgno, void *pData){
  void *pPage;
  int rc;

  rc = sqlitepager_get(pPager, pgno, &pPage);
  if( rc==SQLITE_OK ){
    rc = sqlitepager_write(pPage);
    if( rc==SQLITE_OK ){
      memcpy(pPage, pData, SQLITE_PAGE_SIZE);
    }
    sqlitepager_unref(pPage);
  }
  return rc;
}

/*
** A call to this routine tells the pager that it is not necessary to
** write the information on page "pgno" back to the disk, even though
** that page might be marked as dirty.
**
** The overlying software layer calls this routine when all of the data

**    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 1.21 2003/03/19 03:14:02 drh Exp $
*/

/*
** The size of one page
**
** You can change this value to another (reasonable) power of two
** such as 512, 2048, 4096, or 8192 and things will still work.  But

int sqlitepager_get(Pager *pPager, Pgno pgno, void **ppPage);
void *sqlitepager_lookup(Pager *pPager, Pgno pgno);
int sqlitepager_ref(void*);
int sqlitepager_unref(void*);
Pgno sqlitepager_pagenumber(void*);
int sqlitepager_write(void*);
int sqlitepager_iswriteable(void*);
int sqlitepager_overwrite(Pager *pPager, Pgno pgno, void*);
int sqlitepager_pagecount(Pager*);
int sqlitepager_begin(void*);
int sqlitepager_commit(Pager*);
int sqlitepager_rollback(Pager*);
int sqlitepager_isreadonly(Pager*);
int sqlitepager_ckpt_begin(Pager*);
int sqlitepager_ckpt_commit(Pager*);

** sqlite_mprintf() works like printf(), but allocations memory to hold the
** resulting string and returns a pointer to the allocated memory.  Use
** sqliteFree() to release the memory allocated.
*/
char *sqliteMPrintf(const char *zFormat, ...){
  va_list ap;
  struct sgMprintf sMprintf;

  char zBuf[200];

  sMprintf.nChar = 0;
  sMprintf.nAlloc = sizeof(zBuf);
  sMprintf.zText = zBuf;
  sMprintf.zBase = zBuf;
  va_start(ap,zFormat);

**    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 SELECT statements in SQLite.
**
** $Id: select.c,v 1.127 2003/03/19 03:14:02 drh Exp $
*/
#include "sqliteInt.h"


/*
** Allocate a new Select structure and return a pointer to that
** structure.

static int simpleMinMaxQuery(Parse *pParse, Select *p, int eDest, int iParm){
  Expr *pExpr;
  int iCol;
  Table *pTab;
  Index *pIdx;
  int base;
  Vdbe *v;

  int seekOp;
  int cont;
  ExprList eList;
  struct ExprList_item eListItem;

  /* Check to see if this query is a simple min() or max() query.  Return
  ** zero if it is  not.

  /* Generating code to find the min or the max.  Basically all we have
  ** to do is find the first or the last entry in the chosen index.  If
  ** the min() or max() is on the INTEGER PRIMARY KEY, then find the first
  ** or last entry in the main table.
  */
  if( !pParse->schemaVerified && (pParse->db->flags & SQLITE_InTrans)==0 ){

    sqliteCodeVerifySchema(pParse);
  }

  base = p->base;
  sqliteVdbeAddOp(v, OP_Integer, pTab->isTemp, 0);
  sqliteVdbeAddOp(v, OP_OpenRead, base, pTab->tnum);
  sqliteVdbeChangeP3(v, -1, pTab->zName, P3_STATIC);
  if( pIdx==0 ){
    sqliteVdbeAddOp(v, seekOp, base, 0);
  }else{
    sqliteVdbeAddOp(v, OP_Integer, pTab->isTemp, 0);
    sqliteVdbeAddOp(v, OP_OpenRead, base+1, pIdx->tnum);
    sqliteVdbeChangeP3(v, -1, pIdx->zName, P3_STATIC);
    sqliteVdbeAddOp(v, seekOp, base+1, 0);
    sqliteVdbeAddOp(v, OP_IdxRecno, base+1, 0);
    sqliteVdbeAddOp(v, OP_Close, base+1, 0);
    sqliteVdbeAddOp(v, OP_MoveTo, base, 0);
  }
  eList.nExpr = 1;

/*
** 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.
**
*************************************************************************
** Internal interface definitions for SQLite.
**
** @(#) $Id: sqliteInt.h,v 1.163 2003/03/19 03:14:02 drh Exp $
*/
#include "config.h"
#include "sqlite.h"
#include "hash.h"
#include "vdbe.h"
#include "parse.h"
#include "btree.h"

typedef struct Select Select;
typedef struct AggExpr AggExpr;
typedef struct FuncDef FuncDef;
typedef struct Trigger Trigger;
typedef struct TriggerStep TriggerStep;
typedef struct TriggerStack TriggerStack;
typedef struct FKey FKey;
typedef struct Db Db;

/*
** Each database file to be accessed by the system is an instance
** of the following structure.  There are normally two of these structures
** in the sqlite.aDb[] array.  aDb[0] is the main database file and
** aDb[1] is the database file used to hold temporary tables.  But
** additional databases may be attached to the engine.
*/
struct Db {
  char *zName;         /* Name of this database */
  Btree *pBt;          /* The B*Tree structure for this database file */
  int schema_cookie;   /* Database schema version number for this file */
  u8 inTrans;          /* True if a transaction is underway for this backend */
};

/*
** Each database is an instance of the following structure.
**
** The sqlite.file_format is initialized by the database file
** and helps determines how the data in the database file is
** represented.  This field allows newer versions of the library
** to read and write older databases.  The various file formats
** are as follows:
**
**     file_format==1    Version 2.1.0.
**     file_format==2    Version 2.2.0. Add support for INTEGER PRIMARY KEY.
**     file_format==3    Version 2.6.0. Fix empty-string index bug.
**     file_format==4    Version 2.7.0. Add support for separate numeric and
**                       text datatypes.
*/
struct sqlite {
  int nDb;                      /* Number of backends currently in use */
  Db *aDb;                      /* All backends */
  Db aDbStatic[2];              /* Static space for the 2 default backends */
  int flags;                    /* Miscellanous flags. See below */
  u8 file_format;               /* What file format version is this database? */
  u8 safety_level;              /* How aggressive at synching data to disk */
  u8 want_to_close;             /* Close after all VDBEs are deallocated */

  int next_cookie;              /* Next value of aDb[0].schema_cookie */
  int cache_size;               /* Number of pages to use in the cache */
  int nTable;                   /* Number of tables in the database */
  void *pBusyArg;               /* 1st Argument to the busy callback */
  int (*xBusyCallback)(void *,const char*,int);  /* The busy callback */
  Hash tblHash;                 /* All tables indexed by name */
  Hash idxHash;                 /* All (named) indices indexed by name */
  Hash trigHash;                /* All triggers indexed by name */

  int nCol;        /* Number of columns in this table */
  Column *aCol;    /* Information about each column */
  int iPKey;       /* If not less then 0, use aCol[iPKey] as the primary key */
  Index *pIndex;   /* List of SQL indexes on this table. */
  int tnum;        /* Root BTree node for this table (see note above) */
  Select *pSelect; /* NULL for tables.  Points to definition if a view. */
  u8 readOnly;     /* True if this table should not be written by the user */
  u8 isTemp;       /* Index into sqlite.aDb[] of the backend for this table */
  u8 isTransient;  /* True if automatically deleted when VDBE finishes */
  u8 hasPrimKey;   /* True if there exists a primary key */
  u8 keyConf;      /* What to do in case of uniqueness conflict on iPKey */
  Trigger *pTrigger; /* List of SQL triggers on this table */
  FKey *pFKey;       /* Linked list of all foreign keys in this table */
};

/*
** An SQL parser context.  A copy of this structure is passed through
** the parser and down into all the parser action routine in order to
** carry around information that is global to the entire parse.
*/
struct Parse {
  sqlite *db;          /* The main database structure */

  int rc;              /* Return code from execution */
  sqlite_callback xCallback;  /* The callback function */
  void *pArg;          /* First argument to the callback function */
  char *zErrMsg;       /* An error message */
  Token sErrToken;     /* The token at which the error occurred */
  Token sFirstToken;   /* The first token parsed */
  Token sLastToken;    /* The last token parsed */

int sqliteExprCompare(Expr*, Expr*);
int sqliteFuncId(Token*);
int sqliteExprResolveIds(Parse*, int, SrcList*, ExprList*, Expr*);
int sqliteExprAnalyzeAggregates(Parse*, Expr*);
Vdbe *sqliteGetVdbe(Parse*);
int sqliteRandomByte(void);
int sqliteRandomInteger(void);
void sqliteRollbackAll(sqlite*);
void sqliteCodeVerifySchema(Parse*);
void sqliteBeginTransaction(Parse*, int);
void sqliteCommitTransaction(Parse*);
void sqliteRollbackTransaction(Parse*);
int sqliteExprIsConstant(Expr*);
int sqliteExprIsInteger(Expr*, int*);
int sqliteIsRowid(const char*);
void sqliteGenerateRowDelete(sqlite*, Vdbe*, Table*, int, int);

**    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 1.54 2003/03/19 03:14:02 drh Exp $
*/
#include "sqliteInt.h"

/*
** Process an UPDATE statement.
*/
void sqliteUpdate(

  int base;              /* Index of first available table cursor */
  sqlite *db;            /* The database structure */
  Index **apIdx = 0;     /* An array of indices that need updating too */
  char *aIdxUsed = 0;    /* aIdxUsed[i] if the i-th index is used */
  int *aXRef = 0;        /* aXRef[i] is the index in pChanges->a[] of the
                         ** an expression for the i-th column of the table.
                         ** aXRef[i]==-1 if the i-th column is not changed. */

  int chngRecno;         /* True if the record number is being changed */
  Expr *pRecnoExpr;      /* Expression defining the new record number */
  int openAll;           /* True if all indices need to be opened */

  int row_triggers_exist = 0;

  int newIdx      = -1;  /* index of trigger "new" temp table       */

    sqliteVdbeAddOp(v, OP_OpenTemp, newIdx, 0);

    sqliteVdbeAddOp(v, OP_ListRewind, 0, 0);
    addr = sqliteVdbeAddOp(v, OP_ListRead, 0, 0);
    sqliteVdbeAddOp(v, OP_Dup, 0, 0);

    sqliteVdbeAddOp(v, OP_Dup, 0, 0);
    sqliteVdbeAddOp(v, OP_Integer, pTab->isTemp, 0);
    sqliteVdbeAddOp(v, OP_OpenRead, base, pTab->tnum);
    sqliteVdbeAddOp(v, OP_MoveTo, base, 0);

    sqliteVdbeAddOp(v, OP_Integer, 13, 0);
    for(ii = 0; ii < pTab->nCol; ii++){
      if( ii == pTab->iPKey ){
	sqliteVdbeAddOp(v, OP_Recno, base, 0);
      }else{

  /* Rewind the list of records that need to be updated and
  ** open every index that needs updating.  Note that if any
  ** index could potentially invoke a REPLACE conflict resolution 
  ** action, then we need to open all indices because we might need
  ** to be deleting some records.
  */
  sqliteVdbeAddOp(v, OP_Integer, pTab->isTemp, 0);
  sqliteVdbeAddOp(v, OP_OpenWrite, base, pTab->tnum);
  if( onError==OE_Replace ){
    openAll = 1;
  }else{
    openAll = 0;
    for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
      if( pIdx->onError==OE_Replace ){
        openAll = 1;
        break;
      }
    }
  }
  for(i=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, i++){
    if( openAll || aIdxUsed[i] ){
      sqliteVdbeAddOp(v, OP_Integer, pTab->isTemp, 0);
      sqliteVdbeAddOp(v, OP_OpenWrite, base+i+1, pIdx->tnum);
      assert( pParse->nTab>base+i+1 );
    }
  }

  /* Loop over every record that needs updating.  We have to load
  ** the old data for each record to be updated because some columns
  ** might not change and we will need to copy the old value.

**
** 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 1.208 2003/03/19 03:14:02 drh Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>

/*
** The makefile scans this source file and creates the following
** array of string constants which are the names of all VDBE opcodes.

**
** The "sqlite_vm" structure pointer that is returned by sqlite_compile()
** is really a pointer to an instance of this structure.
*/
struct Vdbe {
  sqlite *db;         /* The whole database */
  Vdbe *pPrev,*pNext; /* Linked list of VDBEs with the same Vdbe.db */

  FILE *trace;        /* Write an execution trace here, if not NULL */
  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 */

/*
** Create a new virtual database engine.
*/
Vdbe *sqliteVdbeCreate(sqlite *db){
  Vdbe *p;
  p = sqliteMalloc( sizeof(Vdbe) );
  if( p==0 ) return 0;

  p->db = db;
  if( db->pVdbe ){
    db->pVdbe->pPrev = p;
  }
  p->pNext = db->pVdbe;
  p->pPrev = 0;
  db->pVdbe = p;

}

/*
** Delete an entire VDBE.
*/
void sqliteVdbeDelete(Vdbe *p){
  int i;
  sqlite *db = p->db;
  if( p==0 ) return;
  Cleanup(p);
  if( p->pPrev ){
    p->pPrev->pNext = p->pNext;
  }else{
    assert( p->db->pVdbe==p );
    p->db->pVdbe = p->pNext;
  }
  if( p->pNext ){
    p->pNext->pPrev = p->pPrev;
  }
  p->pPrev = p->pNext = 0;
  if( p->nOpAlloc==0 ){
    p->aOp = 0;
    p->nOp = 0;
  }
  for(i=0; i<p->nOp; i++){
    if( p->aOp[i].p3type==P3_DYNAMIC ){
      sqliteFree(p->aOp[i].p3);
    }
  }
  for(i=2; i<db->nDb; i++){
    if( db->aDb[i].pBt && db->aDb[i].zName==0 ){
      sqliteBtreeClose(db->aDb[i].pBt);
      db->aDb[i].pBt = 0;
      db->aDb[i].inTrans = 0;
    }
  }
  sqliteFree(p->aOp);
  sqliteFree(p->aLabel);
  sqliteFree(p->aStack);
  sqliteFree(p);
}

*/
int sqliteVdbeExec(
  Vdbe *p                    /* The VDBE */
){
  int pc;                    /* The program counter */
  Op *pOp;                   /* Current operation */
  int rc = SQLITE_OK;        /* Value to return */

  sqlite *db = p->db;        /* The database */
  char **zStack = p->zStack; /* Text stack */
  Stack *aStack = p->aStack; /* Additional stack information */
  char zBuf[100];            /* Space to sprintf() an integer */
#ifdef VDBE_PROFILE
  unsigned long long start;  /* CPU clock count at start of opcode */
  int origPc;                /* Program counter at start of opcode */

/* Opcode: ColumnName P1 * P3
**
** P3 becomes the P1-th column name (first is 0).  An array of pointers
** to all column names is passed as the 4th parameter to the callback.
*/
case OP_ColumnName: {
  assert( pOp->p1>=0 && pOp->p1<p->nOp );
  p->azColName[pOp->p1] = pOp->p3;
  p->nCallback = 0;
  break;
}

/* Opcode: Callback P1 * *
**

    */
    goto abort_due_to_error;
  }
  zStack[tos][aStack[tos].n-1]++;
  break;
}

/* Opcode: Checkpoint P1 * *
**
** Begin a checkpoint.  A checkpoint is the beginning of a operation that
** is part of a larger transaction but which might need to be rolled back
** itself without effecting the containing transaction.  A checkpoint will
** be automatically committed or rollback when the VDBE halts.
**
** The checkpoint is begun on the database file with index P1.  The main
** database file has an index of 0 and the file used for temporary tables
** has an index of 1.
*/
case OP_Checkpoint: {
  int i = pOp->p1;
  if( i>=0 && i<db->nDb && db->aDb[i].pBt ){
    rc = sqliteBtreeBeginCkpt(db->aDb[i].pBt);
  }
  break;
}

/* Opcode: Transaction P1 * *
**
** Begin a transaction.  The transaction ends when a Commit or Rollback
** opcode is encountered.  Depending on the ON CONFLICT setting, the
** transaction might also be rolled back if an error is encountered.
**
** P1 is the index of the database file on which the transaction is
** started.  Index 0 is the main database file and index 1 is the

** file used for temporary tables.
**
** A write lock is obtained on the database file when a transaction is
** started.  No other process can read or write the file while the
** transaction is underway.  Starting a transaction also creates a
** rollback journal.  A transaction must be started before any changes
** can be made to the database.
*/
case OP_Transaction: {
  int busy = 1;







  int i = pOp->p1;
  while( i>=0 && i<db->nDb && db->aDb[i].pBt!=0 && busy ){
    rc = sqliteBtreeBeginTrans(db->aDb[i].pBt);
    switch( rc ){
      case SQLITE_BUSY: {
        if( db->xBusyCallback==0 ){
          p->pc = pc;
          p->undoTransOnError = 1;
          p->rc = SQLITE_BUSY;
          return SQLITE_BUSY;

        break;
      }
      default: {
        goto abort_due_to_error;
      }
    }
  }
  db->aDb[i].inTrans = 1;
  p->undoTransOnError = 1;
  break;
}

/* Opcode: Commit * * *
**
** Cause all modifications to the database that have been made since the
** last Transaction to actually take effect.  No additional modifications
** are allowed until another transaction is started.  The Commit instruction
** deletes the journal file and releases the write lock on the database.
** A read lock continues to be held if there are still cursors open.
*/
case OP_Commit: {
  int i;
  assert( rc==SQLITE_OK );
  for(i=0; rc==SQLITE_OK && i<db->nDb; i++){
    if( db->aDb[i].inTrans ){
      rc = sqliteBtreeCommit(db->aDb[i].pBt);
      db->aDb[i].inTrans = 0;
    }
  }
  if( rc==SQLITE_OK ){
    sqliteCommitInternalChanges(db);
  }else{


    sqliteRollbackAll(db);
  }

  break;
}

/* Opcode: Rollback P1 * *
**
** Cause all modifications to the database that have been made since the
** last Transaction to be undone. The database is restored to its state
** before the Transaction opcode was executed.  No additional modifications
** are allowed until another transaction is started.
**
** P1 is the index of the database file that is committed.  An index of 0
** is used for the main database and an index of 1 is used for the file used
** to hold temporary tables.
**
** This instruction automatically closes all cursors and releases both
** the read and write locks on the indicated database.
*/
case OP_Rollback: {




  sqliteRollbackAll(db);
  break;
}

/* Opcode: ReadCookie P1 P2 *
**

** Read cookie number P2 from database P1 and push it onto the stack.







** P2==0 is the schema version.  P2==1 is the database format.
** P2==2 is the recommended pager cache size, and so forth.  P1==0 is
** the main database file and P1==1 is the database file used to store
** temporary tables.
**
** There must be a read-lock on the database (either a transaction
** must be started or there must be an open cursor) before
** executing this instruction.
*/
case OP_ReadCookie: {
  int i = ++p->tos;
  int aMeta[SQLITE_N_BTREE_META];
  assert( pOp->p2<SQLITE_N_BTREE_META );
  assert( pOp->p1>=0 && pOp->p1<db->nDb );
  assert( db->aDb[pOp->p1].pBt!=0 );
  rc = sqliteBtreeGetMeta(db->aDb[pOp->p1].pBt, aMeta);
  aStack[i].i = aMeta[1+pOp->p2];
  aStack[i].flags = STK_Int;
  break;
}

/* Opcode: SetCookie P1 P2 *
**


** Write the top of the stack into cookie number P2 of database P1.
** P2==0 is the schema version.  P2==1 is the database format.

** P2==2 is the recommended pager cache size, and so forth.  P1==0 is
** the main database file and P1==1 is the database file used to store
** temporary tables.



**
** A transaction must be started before executing this opcode.
*/
case OP_SetCookie: {
  int aMeta[SQLITE_N_BTREE_META];
  assert( pOp->p2<SQLITE_N_BTREE_META );
  assert( pOp->p1>=0 && pOp->p1<db->nDb );
  assert( db->aDb[pOp->p1].pBt!=0 );
  VERIFY( if( p->tos<0 ) goto not_enough_stack; )
  Integerify(p, p->tos)
  rc = sqliteBtreeGetMeta(db->aDb[pOp->p1].pBt, aMeta);
  if( rc==SQLITE_OK ){
    aMeta[1+pOp->p2] = aStack[p->tos].i;
    rc = sqliteBtreeUpdateMeta(db->aDb[pOp->p1].pBt, aMeta);
  }
  POPSTACK;
  break;
}

/* Opcode: VerifyCookie P1 P2 *
**
** Check the value of global database parameter number 0 (the
** schema version) and make sure it is equal to P2.  
** P1 is the database number which is 0 for the main database file
** and 1 for the file holding temporary tables and some higher number
** for auxiliary databases.
**
** The cookie changes its value whenever the database schema changes.
** This operation is used to detect when that the cookie has changed
** and that the current process needs to reread the schema.
**
** Either a transaction needs to have been started or an OP_Open needs
** to be executed (to establish a read lock) before this opcode is
** invoked.
*/
case OP_VerifyCookie: {
  int aMeta[SQLITE_N_BTREE_META];
  assert( pOp->p1>=0 && pOp->p1<db->nDb );
  assert( db->aDb[pOp->p1].zName!=0 );
  rc = sqliteBtreeGetMeta(db->aDb[pOp->p1].pBt, aMeta);
  if( rc==SQLITE_OK && aMeta[1]!=pOp->p2 ){
    sqliteSetString(&p->zErrMsg, "database schema has changed", 0);
    rc = SQLITE_SCHEMA;
  }
  break;
}

/* Opcode: OpenRead P1 P2 P3
**
** Open a read-only cursor for the database table whose root page is
** P2 in a database file.  The database file is determined by an 
** integer from the top of the stack.  0 means the main database and
** 1 means the database used for temporary tables.  Give the new 
** cursor an identifier of P1.  The P1 values need not be contiguous
** but all P1 values should be small integers.  It is an error for
** P1 to be negative.
**
** If P2==0 then take the root page number from the next of the stack.
**
** There will be a read lock on the database whenever there is an
** open cursor.  If the database was unlocked prior to this instruction
** then a read lock is acquired as part of this instruction.  A read
** lock allows other processes to read the database but prohibits
** any other process from modifying the database.  The read lock is
** released when all cursors are closed.  If this instruction attempts
** to get a read lock but fails, the script terminates with an
** SQLITE_BUSY error code.
**
** The P3 value is the name of the table or index being opened.
** The P3 value is not actually used by this opcode and may be
** omitted.  But the code generator usually inserts the index or
** table name into P3 to make the code easier to read.
**
** See also OpenWrite.








*/
/* Opcode: OpenWrite P1 P2 P3
**
** Open a read/write cursor named P1 on the table or index whose root
** page is P2.  If P2==0 then take the root page number from the stack.
**
** This instruction works just like OpenRead except that it opens the cursor
** in read/write mode.  For a given table, there can be one or more read-only
** cursors or a single read/write cursor but not both.
**
** See also OpenRead.
*/







case OP_OpenRead:

case OP_OpenWrite: {

  int busy = 0;
  int i = pOp->p1;
  int tos = p->tos;
  int p2 = pOp->p2;
  int wrFlag;
  Btree *pX;
  int iDb;




  
  VERIFY( if( tos<0 ) goto not_enough_stack; );
  Integerify(p, tos);
  iDb = p->aStack[tos].i;
  tos--;
  VERIFY( if( iDb<0 || iDb>=db->nDb ) goto bad_instruction; );
  VERIFY( if( db->aDb[iDb].pBt==0 ) goto bad_instruction; );
  pX = db->aDb[iDb].pBt;
  wrFlag = pOp->opcode==OP_OpenWrite;
  if( p2<=0 ){
    VERIFY( if( tos<0 ) goto not_enough_stack; );
    Integerify(p, tos);
    p2 = p->aStack[tos].i;
    POPSTACK;
    if( p2<2 ){
      sqliteSetString(&p->zErrMsg, "root page number less than 2", 0);
      rc = SQLITE_INTERNAL;
      break;

        goto abort_due_to_error;
      }
    }
  }while( busy );
  if( p2<=0 ){
    POPSTACK;
  }
  POPSTACK;
  break;
}

/* Opcode: OpenTemp P1 P2 *
**
** Open a new cursor that points to a table or index in a temporary
** database file.  The temporary file is opened read/write even if 

** The table being destroyed is in the main database file if P2==0.  If
** P2==1 then the table to be clear is in the auxiliary database file
** that is used to store tables create using CREATE TEMPORARY TABLE.
**
** See also: Clear
*/
case OP_Destroy: {
  sqliteBtreeDropTable(db->aDb[pOp->p2].pBt, pOp->p1);
  break;
}

/* Opcode: Clear P1 P2 *
**
** Delete all contents of the database table or index whose root page
** in the database file is given by P1.  But, unlike Destroy, do not
** remove the table or index from the database file.
**
** The table being clear is in the main database file if P2==0.  If
** P2==1 then the table to be clear is in the auxiliary database file
** that is used to store tables create using CREATE TEMPORARY TABLE.
**
** See also: Destroy
*/
case OP_Clear: {
  sqliteBtreeClearTable(db->aDb[pOp->p2].pBt, pOp->p1);
  break;
}

/* Opcode: CreateTable * P2 P3
**
** Allocate a new table in the main database file if P2==0 or in the
** auxiliary database file if P2==1.  Push the page number

** See documentation on OP_CreateTable for additional information.
*/
case OP_CreateIndex:
case OP_CreateTable: {
  int i = ++p->tos;
  int pgno;
  assert( pOp->p3!=0 && pOp->p3type==P3_POINTER );
  assert( pOp->p2>=0 && pOp->p2<db->nDb );
  assert( db->aDb[pOp->p2].pBt!=0 );
  if( pOp->opcode==OP_CreateTable ){
    rc = sqliteBtreeCreateTable(db->aDb[pOp->p2].pBt, &pgno);
  }else{
    rc = sqliteBtreeCreateIndex(db->aDb[pOp->p2].pBt, &pgno);
  }
  if( rc==SQLITE_OK ){
    aStack[i].i = pgno;
    aStack[i].flags = STK_Int;
    *(u32*)pOp->p3 = pgno;
    pOp->p3 = 0;
  }

  nRoot = sqliteHashCount(&pSet->hash);
  aRoot = sqliteMallocRaw( sizeof(int)*(nRoot+1) );
  if( aRoot==0 ) goto no_mem;
  for(j=0, i=sqliteHashFirst(&pSet->hash); i; i=sqliteHashNext(i), j++){
    toInt((char*)sqliteHashKey(i), &aRoot[j]);
  }
  aRoot[j] = 0;
  z = sqliteBtreeIntegrityCheck(db->aDb[pOp->p2].pBt, aRoot, nRoot);
  if( z==0 || z[0]==0 ){
    if( z ) sqliteFree(z);
    zStack[tos] = "ok";
    aStack[tos].n = 3;
    aStack[tos].flags = STK_Str | STK_Static;
  }else{
    zStack[tos] = z;

/*
** Clean up the VDBE after execution.  Return an integer which is the
** result code.
*/
int sqliteVdbeFinalize(Vdbe *p, char **pzErrMsg){
  sqlite *db = p->db;

  int i, rc;

  if( p->magic!=VDBE_MAGIC_RUN && p->magic!=VDBE_MAGIC_HALT ){
    sqliteSetString(pzErrMsg, sqlite_error_string(SQLITE_MISUSE), 0);
    return SQLITE_MISUSE;
  }
  if( p->zErrMsg ){
    if( pzErrMsg && *pzErrMsg==0 ){
      *pzErrMsg = p->zErrMsg;
    }else{
      sqliteFree(p->zErrMsg);
    }
    p->zErrMsg = 0;
  }
  Cleanup(p);
  if( p->rc!=SQLITE_OK ){
    switch( p->errorAction ){
      case OE_Abort: {
        if( !p->undoTransOnError ){
          for(i=0; i<db->nDb; i++){
            if( db->aDb[i].pBt ){
              sqliteBtreeRollbackCkpt(db->aDb[i].pBt);

            }
          }
          break;
        }
        /* Fall through to ROLLBACK */
      }
      case OE_Rollback: {
        sqliteRollbackAll(db);

        db->flags &= ~SQLITE_InTrans;
        db->onError = OE_Default;
        break;
      }
      default: {
        if( p->undoTransOnError ){
          sqliteRollbackAll(db);

          db->flags &= ~SQLITE_InTrans;
          db->onError = OE_Default;
        }
        break;
      }
    }
    sqliteRollbackInternalChanges(db);
  }
  for(i=0; i<db->nDb; i++){
    if( db->aDb[i].pBt ){
      sqliteBtreeCommitCkpt(db->aDb[i].pBt);

    }
  }
  assert( p->tos<p->pc || sqlite_malloc_failed==1 );
#ifdef VDBE_PROFILE
  {
    FILE *out = fopen("vdbe_profile.out", "a");
    if( out ){
      int i;
      fprintf(out, "---- ");

**    May you share freely, never taking more than you give.
**
*************************************************************************
** This module contains C code that generates VDBE code used to process
** the WHERE clause of SQL statements.  Also found here are subroutines
** to generate VDBE code to evaluate expressions.
**
** $Id: where.c,v 1.73 2003/03/19 03:14:03 drh Exp $
*/
#include "sqliteInt.h"

/*
** The query generator uses an array of instances of this structure to
** help it analyze the subexpressions of the WHERE clause.  Each WHERE
** clause subexpression is separated from the others by an AND operator.

       *ppOrderBy = 0;
     }
  }

  /* Open all tables in the pTabList and all indices used by those tables.
  */
  for(i=0; i<pTabList->nSrc; i++){

    Table *pTab;

    pTab = pTabList->a[i].pTab;
    if( pTab->isTransient || pTab->pSelect ) continue;
    sqliteVdbeAddOp(v, OP_Integer, pTab->isTemp, 0);
    sqliteVdbeAddOp(v, OP_OpenRead, base+i, pTab->tnum);
    sqliteVdbeChangeP3(v, -1, pTab->zName, P3_STATIC);
    if( i==0 && !pParse->schemaVerified &&
          (pParse->db->flags & SQLITE_InTrans)==0 ){

      sqliteCodeVerifySchema(pParse);
    }
    if( pWInfo->a[i].pIdx!=0 ){
      sqliteVdbeAddOp(v, OP_Integer, pTab->isTemp, 0);
      sqliteVdbeAddOp(v, OP_OpenRead,
                      pWInfo->a[i].iCur, pWInfo->a[i].pIdx->tnum);
      sqliteVdbeChangeP3(v, -1, pWInfo->a[i].pIdx->zName, P3_STATIC);
    }
  }

  /* Generate the code to do the search
  */
  loopMask = 0;

#
# Run this Tcl script to generate the sqlite.html file.
#
set rcsid {$Id: arch.tcl,v 1.9 2003/03/19 03:14:03 drh Exp $}

puts {<html>
<head>
  <title>Architecture of SQLite</title>
</head>
<body bgcolor=white>
<h1 align=center>

the tokenizer to call the parser.  YACC has it backwards.</p>

<h2>Parser</h2>

<p>The parser is the piece that assigns meaning to tokens based on
their context.  The parser for SQLite is generated using the
<a href="http://www.hwaci.com/sw/lemon/">Lemon</a> LALR(1) parser
generator.  Lemon does the same job as YACC/BISON, but it uses
a different input syntax which is less error-prone.
Lemon also generates a parser which is reentrant and thread-safe.
And lemon defines the concept of a non-terminal destructor so
that it does not leak memory when syntax errors are encountered.
The source file that drives Lemon is found in <b>parse.y</b>.</p>

<p>Because