SQLite

/*
** 2004 April 6
**
** 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 1.152 2004/05/30 20:46:09 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.

  return getPayload(pCur, offset, amt, pBuf, 1);
}

/*
** Return a pointer to payload information from the entry that the 
** pCur cursor is pointing to.  The pointer is to the beginning of
** the key if skipKey==0 and it points to the beginning of data if
** skipKey==1.  The number of bytes of available key/data is written


** into *pAmt.  If *pAmt==0, then the value returned will not be
** a valid pointer.
**
** This routine is an optimization.  It is common for the entire key
** and data to fit on the local page and for there to be no overflow
** pages.  When that is so, this routine can be used to access the
** key and data without making a copy.  If the key and/or data spills
** onto overflow pages, then getPayload() must be used to reassembly
** the key/data and copy it into a preallocated buffer.
**
** The pointer returned by this routine looks directly into the cached
** page of the database.  The data might change or move the next time
** any btree routine is called.
*/
static const unsigned char *fetchPayload(
  BtCursor *pCur,      /* Cursor pointing to entry to read from */
  int *pAmt,           /* Write the number of available bytes here */
  int skipKey          /* read beginning at data if this is true */
){
  unsigned char *aPayload;
  MemPage *pPage;
  Btree *pBt;
  u32 nKey;
  int nLocal;

    nKey = 0;
  }else{
    nKey = pCur->info.nKey;
  }
  if( skipKey ){
    aPayload += nKey;
    nLocal = pCur->info.nLocal - nKey;


  }else{
    nLocal = pCur->info.nLocal;
    if( nLocal>nKey ){
      nLocal = nKey;

    }


  }
  *pAmt = nLocal;
  return aPayload;
}


/*

** For the entry that cursor pCur is point to, return as




** many bytes of the key or data as are available on the local
** b-tree page.  Write the number of available bytes into *pAmt.
**
** The pointer returned is ephemeral.  The key/data may move
** or be destroyed on the next call to any Btree routine.
**
** These routines is used to get quick access to key and data
** in the common case where no overflow pages are used.



*/
const void *sqlite3BtreeKeyFetch(BtCursor *pCur, int *pAmt){
  return (const void*)fetchPayload(pCur, pAmt, 0);
}
const void *sqlite3BtreeDataFetch(BtCursor *pCur, int *pAmt){
  return (const void*)fetchPayload(pCur, pAmt, 1);
}


/*
** Move the cursor down to a new child page.  The newPgno argument is the
** page number of the child page to move to.
*/

        if( nCellKey<nKey ){
          c = -1;
        }else if( nCellKey>nKey ){
          c = +1;
        }else{
          c = 0;
        }
      }else{
        int available;
        pCellKey = fetchPayload(pCur, &available, 0);
        if( available>=nCellKey ){
          c = pCur->xCompare(pCur->pArg, nCellKey, pCellKey, nKey, pKey);
        }else{
          pCellKey = sqliteMallocRaw( nCellKey );
          if( pCellKey==0 ) return SQLITE_NOMEM;
          rc = sqlite3BtreeKey(pCur, 0, nCellKey, pCellKey);
          c = pCur->xCompare(pCur->pArg, nCellKey, pCellKey, nKey, pKey);
          sqliteFree(pCellKey);
          if( rc ) return rc;
        }
      }
      if( c==0 ){
        if( pPage->leafData && !pPage->leaf ){
          lwr = pCur->idx;
          upr = lwr - 1;
          break;
        }else{

**    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 1.49 2004/05/30 20:46:09 drh Exp $
*/
#ifndef _BTREE_H_
#define _BTREE_H_

/* TODO: This definition is just included so other modules compile. It
** needs to be revisited.
*/

int sqlite3BtreeLast(BtCursor*, int *pRes);
int sqlite3BtreeNext(BtCursor*, int *pRes);
int sqlite3BtreeEof(BtCursor*);
int sqlite3BtreeFlags(BtCursor*);
int sqlite3BtreePrevious(BtCursor*, int *pRes);
int sqlite3BtreeKeySize(BtCursor*, i64 *pSize);
int sqlite3BtreeKey(BtCursor*, u32 offset, u32 amt, void*);
const void *sqlite3BtreeKeyFetch(BtCursor*, int *pAmt);
const void *sqlite3BtreeDataFetch(BtCursor*, int *pAmt);
int sqlite3BtreeDataSize(BtCursor*, u32 *pSize);
int sqlite3BtreeData(BtCursor*, u32 offset, u32 amt, void*);

char *sqlite3BtreeIntegrityCheck(Btree*, int *aRoot, int nRoot);
struct Pager *sqlite3BtreePager(Btree*);

**    May you share freely, never taking more than you give.
**
*************************************************************************
** Code for testing the btree.c module in SQLite.  This code
** is not included in the SQLite library.  It is used for automated
** testing of the SQLite library.
**
** $Id: test3.c,v 1.39 2004/05/30 20:46:09 drh Exp $
*/
#include "sqliteInt.h"
#include "pager.h"
#include "btree.h"
#include "tcl.h"
#include <stdlib.h>
#include <string.h>

  void *NotUsed,
  Tcl_Interp *interp,    /* The TCL interpreter that invoked this command */
  int argc,              /* Number of arguments */
  const char **argv      /* Text of each argument */
){
  BtCursor *pCur;
  int n;
  int amt;
  u64 nKey;
  const char *zBuf;
  char zStatic[1000];

  if( argc!=3 ){
    Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0],
       " ID AMT\"", 0);
    return TCL_ERROR;
  }
  if( Tcl_GetInt(interp, argv[1], (int*)&pCur) ) return TCL_ERROR;
  if( Tcl_GetInt(interp, argv[2], &n) ) return TCL_ERROR;
  sqlite3BtreeKeySize(pCur, &nKey);
  zBuf = sqlite3BtreeKeyFetch(pCur, &amt);
  if( zBuf && amt>=n ){
    assert( nKey<sizeof(zStatic) );
    if( n>0 ) nKey = n;
    memcpy(zStatic, zBuf, (int)nKey); 
    zStatic[nKey] = 0;
    Tcl_AppendResult(interp, zStatic, 0);
  }
  return TCL_OK;

  void *NotUsed,
  Tcl_Interp *interp,    /* The TCL interpreter that invoked this command */
  int argc,              /* Number of arguments */
  const char **argv      /* Text of each argument */
){
  BtCursor *pCur;
  int n;
  int amt;
  u32 nData;
  const char *zBuf;
  char zStatic[1000];

  if( argc!=3 ){
    Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0],
       " ID AMT\"", 0);

    return TCL_ERROR;
  }
  if( Tcl_GetInt(interp, argv[1], (int*)&pCur) ) return TCL_ERROR;
  if( Tcl_GetInt(interp, argv[2], &n) ) return TCL_ERROR;
  sqlite3BtreeDataSize(pCur, &nData);
  zBuf = sqlite3BtreeDataFetch(pCur, &amt);
  if( zBuf && amt>=n ){
    assert( nData<sizeof(zStatic) );
    if( n>0 ) nData = n;
    memcpy(zStatic, zBuf, (int)nData); 
    zStatic[nData] = 0;
    Tcl_AppendResult(interp, zStatic, 0);
  }
  return TCL_OK;

**
*************************************************************************
** Utility functions used throughout sqlite.
**
** This file contains functions for allocating memory, comparing
** strings, and stuff like that.
**
** $Id: util.c,v 1.95 2004/05/30 20:46:09 drh Exp $
*/
#include "sqliteInt.h"
#include <stdarg.h>
#include <ctype.h>

/*
** If malloc() ever fails, this global variable gets set to 1.

** Return the number of bytes read.  The value is stored in *v.
*/
int sqlite3GetVarint(const unsigned char *p, u64 *v){
  u32 x;
  u64 x64;
  int n;
  unsigned char c;

  if( ((c = p[0]) & 0x80)==0 ){
    *v = c;
    return 1;
  }
  x = c & 0x7f;

  if( ((c = p[1]) & 0x80)==0 ){
    *v = (x<<7) | c;
    return 2;
  }
  x = (x<<7) | (c&0x7f);

  if( ((c = p[2]) & 0x80)==0 ){
    *v = (x<<7) | c;
    return 3;
  }
  x = (x<<7) | (c&0x7f);

  if( ((c = p[3]) & 0x80)==0 ){
    *v = (x<<7) | c;
    return 4;
  }
  x64 = (x<<7) | (c&0x7f);
  n = 4;
  do{
    c = p[n++];

}

/*
** Read a 32-bit variable-length integer from memory starting at p[0].
** Return the number of bytes read.  The value is stored in *v.
*/
int sqlite3GetVarint32(const unsigned char *p, u32 *v){
  u32 x;
  int n;
  unsigned char c;
  if( ((c = p[0]) & 0x80)==0 ){
    *v = c;
    return 1;
  }
  x = c & 0x7f;
  if( ((c = p[1]) & 0x80)==0 ){
    *v = (x<<7) | c;
    return 2;
  }
  x = (x<<7) | (c&0x7f);
  if( ((c = p[2]) & 0x80)==0 ){
    *v = (x<<7) | c;
    return 3;
  }
  x = (x<<7) | (c&0x7f);
  if( ((c = p[3]) & 0x80)==0 ){
    *v = (x<<7) | c;
    return 4;
  }
  n = 4;
  do{
    x = (x<<7) | ((c = p[n++])&0x7f);
  }while( (c & 0x80)!=0 && n<9 );
  *v = x;
  return n;
}

/*
** Return the number of bytes that will be needed to store the given
** 64-bit integer.

**
** 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 1.349 2004/05/30 20:46:09 drh Exp $
*/
#include "sqliteInt.h"
#include "os.h"
#include <ctype.h>
#include "vdbeInt.h"

/*

      pTos++;
      pTos->flags = MEM_Null;
    }
    break;
  }

  affinity = (pOp->p1>>8)&0xFF;
  if( affinity ){
    applyAffinity(pNos, affinity, db->enc);
    applyAffinity(pTos, affinity, db->enc);
  }

  assert( pOp->p3type==P3_COLLSEQ || pOp->p3==0 );
  res = sqlite3MemCompare(pNos, pTos, (CollSeq*)pOp->p3);
  switch( pOp->opcode ){
    case OP_Eq:    res = res==0;     break;
    case OP_Ne:    res = res!=0;     break;
    case OP_Lt:    res = res<0;      break;

  /* Read and parse the table header.  Store the results of the parse
  ** into the record header cache fields of the cursor.
  */
  if( pC && pC->cacheValid ){
    aType = pC->aType;
    aOffset = pC->aOffset;
  }else{
    int avail;    /* Number of bytes of available data */
    if( pC && pC->aType ){
      aType = pC->aType;
    }else{
      aType = sqliteMallocRaw( 2*nField*sizeof(aType) );
    }
    aOffset = &aType[nField];
    if( aType==0 ){
      goto no_mem;
    }

    /* Figure out how many bytes are in the header */
    if( zRec ){
      zData = zRec;
    }else{

      if( pC->keyAsData ){
        zData = (char*)sqlite3BtreeKeyFetch(pCrsr, &avail);
      }else{
        zData = (char*)sqlite3BtreeDataFetch(pCrsr, &avail);
      }
    }
    idx = sqlite3GetVarint32(zData, &szHdr);

    /* Get the complete header text */
    if( !zRec && avail<idx ){
      rc = sqlite3VdbeMemFromBtree(pCrsr, 0, szHdr, pC->keyAsData, &sMem);
      if( rc!=SQLITE_OK ){
        goto abort_due_to_error;
      }
      zData = sMem.z;
    }

){
  int len;

  len = sqlite3VdbeSerialTypeLen(serial_type);
  assert( serial_type!=0 );
  if( serial_type<=5 ){
    /* Integer and Real */
    if( serial_type<=3 ){
      /* 32-bit integer type.  This is handled by a special case for
      ** performance reasons. */
      int v = buf[0];
      int n;
      if( v&0x80 ){
        v |= -256;
      }
      for(n=1; n<len; n++){
        v = (v<<8) | buf[n];
      }
      pMem->flags = MEM_Int;
      pMem->i = v;
      return n;
    }else{
      u64 v = 0;
      int n;

      if( buf[0]&0x80 ){
        v = -1;
      }
      for(n=0; n<len; n++){
        v = (v<<8) | buf[n];
      }
      if( serial_type==5 ){
        pMem->flags = MEM_Real;
        pMem->r = *(double*)&v;
      }else{
        pMem->flags = MEM_Int;
        pMem->i = *(i64*)&v;
      }
    }
  }else if( serial_type>=12 ){
    /* String or blob */
    pMem->z = (char *)buf;
    pMem->n = len;
    if( serial_type&0x01 ){
      pMem->flags = MEM_Str | MEM_Ephem;

int sqlite3VdbeMemFromBtree(
  BtCursor *pCur,   /* Cursor pointing at record to retrieve. */
  int offset,       /* Offset from the start of data to return bytes from. */
  int amt,          /* Number of bytes to return. */
  int key,          /* If true, retrieve from the btree key, not data. */
  Mem *pMem         /* OUT: Return data in this Mem structure. */
){
  char *zData;      /* Data from the btree layer */
  int available;    /* Number of bytes available on the local btree page */

  if( key ){
    zData = (char *)sqlite3BtreeKeyFetch(pCur, &available);
  }else{
    zData = (char *)sqlite3BtreeDataFetch(pCur, &available);
  }

  pMem->n = amt;
  if( offset+amt<=available ){
    pMem->z = &zData[offset];
    pMem->flags = MEM_Blob|MEM_Ephem;
  }else{
    int rc;
    if( amt>NBFS-2 ){
      zData = (char *)sqliteMallocRaw(amt+2);
      if( !zData ){