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 1.136 2004/05/14 15:27:28 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.

static int initPage(
  MemPage *pPage,        /* The page to be initialized */
  MemPage *pParent       /* The parent.  Might be NULL */
){
  int c, pc, i, hdr;
  unsigned char *data;
  int usableSize;
  /* int sumCell = 0;       // Total size of all cells */


  assert( pPage->pBt!=0 );
  assert( pParent==0 || pParent->pBt==pPage->pBt );
  assert( pPage->pgno==sqlite3pager_pagenumber(pPage->aData) );
  assert( pPage->aData == &((unsigned char*)pPage)[-pPage->pBt->pageSize] );
  assert( pPage->pParent==0 || pPage->pParent==pParent );
  assert( pPage->pParent==pParent || !pPage->isInit );
  if( pPage->isInit ) return SQLITE_OK;
  if( pPage->pParent==0 && pParent!=0 ){
    pPage->pParent = pParent;
    sqlite3pager_ref(pParent->aData);
  }

  pPage->nCell = pPage->nCellAlloc = 0;
  assert( pPage->hdrOffset==(pPage->pgno==1 ? 100 : 0) );
  hdr = pPage->hdrOffset;
  data = pPage->aData;
  c = data[hdr];
  pPage->intKey = (c & (PTF_INTKEY|PTF_LEAFDATA))!=0;
  pPage->zeroData = (c & PTF_ZERODATA)!=0;

  }
  if( resizeCellArray(pPage, pPage->nCell) ){
    return SQLITE_NOMEM;
  }
  pc = get2byte(&data[hdr+3]);
  for(i=0; pc>0; i++){
    pPage->aCell[i] = &data[pc];
    /* sumCell += cellSize(pPage, &data[pc]); */
    pc = get2byte(&data[pc]);
  }

  /* Compute the total free space on the page */
  pPage->nFree = data[hdr+5];
  pc = get2byte(&data[hdr+1]);
  while( pc>0 ){
    int next, size;
    if( pc>=usableSize ) return SQLITE_CORRUPT;
    next = get2byte(&data[pc]);
    size = get2byte(&data[pc+2]);
    if( next>0 && next<=pc+size+3 ) return SQLITE_CORRUPT;
    pPage->nFree += size;
    pc = next;
  }
  if( pPage->nFree>=usableSize ) return SQLITE_CORRUPT;

  /* Sanity check:  Cells and freespace and header must sum to the size
  ** a page.
  if( sumCell+pPage->nFree+hdr+10-pPage->leaf*4 != usableSize ){
    return SQLITE_CORRUPT;
  }
  */

  pPage->isInit = 1;
  pageIntegrity(pPage);
  return SQLITE_OK;
}

/*

  Btree *pBt,          /* The database file */
  Pgno pgno,           /* Number of the page to get */
  MemPage **ppPage,    /* Write the page pointer here */
  MemPage *pParent     /* Parent of the page */
){
  int rc;
  rc = getPage(pBt, pgno, ppPage);
  if( rc==SQLITE_OK && (*ppPage)->isInit==0 ){
    rc = initPage(*ppPage, pParent);
  }
  return rc;
}

/*
** Release a MemPage.  This should be called once for each prior

**
** 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 1.291 2004/05/14 15:27:29 drh Exp $
*/
#include "sqliteInt.h"
#include "os.h"
#include <ctype.h>
#include "vdbeInt.h"

/*

    }else{
      zData = (char *)sqlite3BtreeDataFetch(pCrsr, max_space);
    }
    if( !zData ){
      /* This code will run very infrequently (e.g. tables with several
      ** hundred columns).
      */
      zData = (char *)sqliteMallocRaw(offset+max_space);
      if( !zData ){
        rc = SQLITE_NOMEM;
        goto abort_due_to_error;
      }
      if( pC->keyAsData ){
        rc = sqlite3BtreeKey(pCrsr, 0, max_space, zData);
      }else{

    }
  }

  /* Dynamically allocate space for the aTypes array. and read all
  ** the serial types for the record. At the end of this block variable
  ** offset is set to the offset to the start of Data0 in the record.
  */
  aTypes = (u64 *)sqliteMallocRaw(sizeof(u64)*nFields);
  if( !aTypes ){
    if( freeZdata ){
      sqliteFree(zData);
      freeZdata = 0;
    }
    rc = SQLITE_NOMEM;
    goto abort_due_to_error;

    */
    if( pC->keyAsData ){
      zData = (char *)sqlite3BtreeKeyFetch(pCrsr, offset+len);
    }else{
      zData = (char *)sqlite3BtreeDataFetch(pCrsr, offset+len);
    }
    if( !zData && len>0 ){
      zData = (char *)sqliteMallocRaw(len);
      if( !zData ){
        sqliteFree(aTypes);
        rc = SQLITE_NOMEM;
        goto abort_due_to_error;
      }
      if( pC->keyAsData ){
        rc = sqlite3BtreeKey(pCrsr, offset, len, zData);

  if( nBytes>MAX_BYTES_PER_ROW ){
    rc = SQLITE_TOOBIG;
    goto abort_due_to_error;
  }

  /* Allocate space for the new record. */
  zNewRecord = sqliteMallocRaw(nBytes);
  if( !zNewRecord ){
    rc = SQLITE_NOMEM;
    goto abort_due_to_error;
  }

  /* Write the record */
  zCsr = zNewRecord;

  
  if( nByte>MAX_BYTES_PER_ROW ){
    rc = SQLITE_TOOBIG;
    goto abort_due_to_error;
  }

  /* Allocate space for the new key */
  zKey = (char *)sqliteMallocRaw(nByte);
  if( !zKey ){
    rc = SQLITE_NOMEM;
    goto abort_due_to_error;
  }
  
  /* Build the key in the buffer pointed to by zKey. */
  for(pRec=pData0; pRec<=pTos; pRec++){

  if( nCellKey<=0 ){
    *res = 0;
    return SQLITE_OK;
  }

  pCellKey = (unsigned char *)sqlite3BtreeKeyFetch(pCur, nCellKey);
  if( !pCellKey ){
    pCellKey = (unsigned char *)sqliteMallocRaw(nCellKey);
    if( !pCellKey ){
      return SQLITE_NOMEM;
    }
    freeCellKey = 1;
    rc = sqlite3BtreeKey(pCur, 0, nCellKey, pCellKey);
    if( rc!=SQLITE_OK ){
      sqliteFree(pCellKey);

  *res = sqlite3VdbeKeyCompare(pC, len, pCellKey, nKey, pKey);
  
  if( freeCellKey ){
    sqliteFree(pCellKey);
  }
  return SQLITE_OK;
}