SQLite

**
*************************************************************************
** 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 1.41 2001/09/23 20:17:55 drh Exp $
*/
#include "sqliteInt.h"
#include "os.h"

/*
** This is the callback routine for the code that initializes the
** database.  Each callback contains the following information:

  /* Allocate the sqlite data structure */
  db = sqliteMalloc( sizeof(sqlite) );
  if( pzErrMsg ) *pzErrMsg = 0;
  if( db==0 ) goto no_mem_on_open;
  sqliteHashInit(&db->tblHash, SQLITE_HASH_STRING, 0);
  sqliteHashInit(&db->idxHash, SQLITE_HASH_STRING, 0);
  db->nextRowid = sqliteRandomInteger(db);
  
  /* Open the backend database driver */
  rc = sqliteBtreeOpen(zFilename, mode, MAX_PAGES, &db->pBe);
  if( rc!=SQLITE_OK ){
    switch( rc ){
      default: {
        if( pzErrMsg ){

** type to the other occurs as necessary.
** 
** Most of the code in this file is taken up by the sqliteVdbeExec()
** function which does the work of interpreting a VDBE program.
** But other routines are also provided to help in building up
** a program instruction by instruction.
**
** $Id: vdbe.c,v 1.76 2001/09/23 20:17:55 drh Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>
#include <unistd.h>

/*
** SQL is translated into a sequence of instructions to be

  if( pLeft ){
    pTail->pNext = pLeft;
  }else if( pRight ){
    pTail->pNext = pRight;
  }
  return sHead.pNext;
}

/*
** Convert an integer into a big-endian integer.  In other words,
** make sure the most significant byte comes first.
*/
static int bigEndian(int x){
  union {
     char zBuf[sizeof(int)];
     int i;
  } ux;
  ux.zBuf[3] = x&0xff;
  ux.zBuf[2] = (x>>8)&0xff;
  ux.zBuf[1] = (x>>16)&0xff;
  ux.zBuf[0] = (x>>24)&0xff;
  return ux.i;
}

/*
** Code contained within the VERIFY() macro is not needed for correct
** execution.  It is there only to catch errors.  So when we compile
** with NDEBUG=1, the VERIFY() code is omitted.
*/
#ifdef NDEBUG

** See also:  MakeKey, SortMakeKey
*/
case OP_MakeIdxKey: {
  char *zNewKey;
  int nByte;
  int nField;
  int i, j;
  u32 iKey;

  nField = pOp->p1;
  VERIFY( if( p->tos+1<nField ) goto not_enough_stack; )
  nByte = sizeof(u32);
  for(i=p->tos-nField+1; i<=p->tos; i++){
    if( aStack[i].flags & STK_Null ){
      nByte++;

      zNewKey[j++] = 0;
    }else{
      memcpy(&zNewKey[j], zStack[i], aStack[i].n);
      j += aStack[i].n;
    }
  }
  Integerify(p, p->tos-nField);
  iKey = bigEndian(aStack[p->tos-nField].i);
  memcpy(&zNewKey[j], &iKey, sizeof(u32));
  PopStack(p, nField+1);
  VERIFY( NeedStack(p, p->tos+1); )
  p->tos++;
  aStack[p->tos].n = nByte;
  aStack[p->tos].flags = STK_Str|STK_Dyn;
  zStack[p->tos] = zNewKey;
  break;

case OP_MoveTo: {
  int i = pOp->p1;
  int tos = p->tos;
  VERIFY( if( tos<0 ) goto not_enough_stack; )
  if( i>=0 && i<p->nCursor && p->aCsr[i].pCursor ){
    int res;
    if( aStack[tos].flags & STK_Int ){
      int iKey = bigEndian(aStack[tos].i);
      sqliteBtreeMoveto(p->aCsr[i].pCursor, 
          (char*)&iKey, sizeof(int), &res);
      p->aCsr[i].lastRecno = aStack[tos].i;
      p->aCsr[i].recnoIsValid = 1;
    }else{
      if( Stringify(p, tos) ) goto no_mem;
      sqliteBtreeMoveto(p->aCsr[i].pCursor, zStack[tos], aStack[tos].n, &res);
      p->aCsr[i].recnoIsValid = 0;
    }

  int i = pOp->p1;
  int tos = p->tos;
  int alreadyExists = 0;
  VERIFY( if( tos<0 ) goto not_enough_stack; )
  if( VERIFY( i>=0 && i<p->nCursor && ) p->aCsr[i].pCursor ){
    int res, rx;
    if( aStack[tos].flags & STK_Int ){
      int iKey = bigEndian(aStack[tos].i);
      rx = sqliteBtreeMoveto(p->aCsr[i].pCursor, 
           (char*)&iKey, sizeof(int), &res);
    }else{
      if( Stringify(p, tos) ) goto no_mem;
      rx = sqliteBtreeMoveto(p->aCsr[i].pCursor,
         zStack[tos], aStack[tos].n, &res);
    }
    alreadyExists = rx==SQLITE_OK && res==0;
  }

    ** hardware failure than for this algorithm to fail.
    **
    ** To promote locality of reference for repetitive inserts, the
    ** first few attempts at chosing a rowid pick values just a little
    ** larger than the previous rowid.  This has been shown experimentally
    ** to double the speed of the COPY operation.
    */
    int res, rx, cnt, x;

    union {
       char zBuf[sizeof(int)];
       int i;
    } ux;
    cnt = 0;
    v = db->nextRowid;
    do{
      if( cnt>5 ){
        v = sqliteRandomInteger(db);
      }else{
        v += sqliteRandomByte(db) + 1;
      }
      if( v==0 ) continue;




      x = bigEndian(v);
      rx = sqliteBtreeMoveto(p->aCsr[i].pCursor, &x, sizeof(int), &res);
      cnt++;
    }while( cnt<1000 && rx==SQLITE_OK && res==0 );
    db->nextRowid = v;
    if( rx==SQLITE_OK && res==0 ){
      rc = SQLITE_FULL;
      goto abort_due_to_error;
    }
  }
  VERIFY( NeedStack(p, p->tos+1); )
  p->tos++;

case OP_Put: {
  int tos = p->tos;
  int nos = p->tos-1;
  int i = pOp->p1;
  VERIFY( if( nos<0 ) goto not_enough_stack; )
  if( VERIFY( i>=0 && i<p->nCursor && ) p->aCsr[i].pCursor!=0 ){
    char *zKey;
    int nKey, iKey;
    if( (aStack[nos].flags & STK_Int)==0 ){
      if( Stringify(p, nos) ) goto no_mem;
      nKey = aStack[nos].n;
      zKey = zStack[nos];
    }else{
      nKey = sizeof(int);
      iKey = bigEndian(aStack[nos].i);
      zKey = (char*)&iKey;
    }
    rc = sqliteBtreeInsert(p->aCsr[i].pCursor, zKey, nKey,
                        zStack[tos], aStack[tos].n);
  }
  POPSTACK;
  POPSTACK;
  break;

  VERIFY( if( NeedStack(p, p->tos) ) goto no_mem; )
  if( VERIFY( i>=0 && i<p->nCursor && ) (pCrsr = p->aCsr[i].pCursor)!=0 ){
    int v;
    if( p->aCsr[i].recnoIsValid ){
      v = p->aCsr[i].lastRecno;
    }else{
      sqliteBtreeKey(pCrsr, 0, sizeof(u32), (char*)&v);
      v = bigEndian(v);
    }
    aStack[tos].i = v;
    aStack[tos].flags = STK_Int;
  }
  break;
}

      memcmp(pCrsr->zKey, pCrsr->zBuf, pCrsr->nKey)!=0
    ){
      pc = pOp->p2 - 1;
      POPSTACK;
    }else{
      int recno;
      sqliteBtreeKey(pCur, pCrsr->nKey, sizeof(u32), (char*)&recno);
      recno = bigEndian(recno);
      p->aCsr[i].lastRecno = aStack[tos].i = recno;
      p->aCsr[i].recnoIsValid = 1;
      aStack[tos].flags = STK_Int;
    }
  }
  break;
}