SQLite

/*
** 2003 Feb 4
**
** 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_rb.c,v 1.19 2004/01/12 00:21:52 drh Exp $
** $Id: btree_rb.c,v 1.20 2004/01/12 00:38:18 drh Exp $
**
** This file implements an in-core database using Red-Black balanced
** binary trees.
** 
** It was contributed to SQLite by anonymous on 2003-Feb-04 23:24:49 UTC.
*/
#include "btree.h"

  if( checkReadLocks(pCur) ){
    return SQLITE_LOCKED; /* The table pCur points to has a read lock */
  }

  /* Take a copy of the input data now, in case we need it for the 
   * replace case */
  pData = sqliteMallocRaw(nData);
  if( pData==0 ) return SQLITE_NOMEM;
  if( sqlite_malloc_failed ) return SQLITE_NOMEM;
  memcpy(pData, pDataInput, nData);

  /* Move the cursor to a node near the key to be inserted. If the key already
   * exists in the table, then (match == 0). In this case we can just replace
   * the data associated with the entry, we don't need to manipulate the tree.
   * 
   * If there is no exact match, then the cursor points at what would be either
   * the predecessor (match == -1) or successor (match == 1) of the
   * searched-for key, were it to be inserted. The new node becomes a child of
   * this node.
   * 
   * The new node is initially red.
   */
  memRbtreeMoveto( pCur, pKey, nKey, &match);
  if( match ){
    BtRbNode *pNode = sqliteMalloc(sizeof(BtRbNode));
    if( pNode==0 ) return SQLITE_NOMEM;
    pNode->nKey = nKey;
    pNode->pKey = sqliteMallocRaw(nKey);
    if( pNode->pKey==0 ) return SQLITE_NOMEM;
    if( sqlite_malloc_failed ) return SQLITE_NOMEM;
    memcpy(pNode->pKey, pKey, nKey);
    pNode->nData = nData;
    pNode->pData = pData; 
    if( pCur->pNode ){
      switch( match ){
        case -1:
          assert( !pCur->pNode->pRight );

    if( pCur->pRbtree->eTransState != TRANS_ROLLBACK ){
      BtRollbackOp *pOp = sqliteMalloc( sizeof(BtRollbackOp) );
      if( pOp==0 ) return SQLITE_NOMEM;
      pOp->eOp = ROLLBACK_DELETE;
      pOp->iTab = pCur->iTree;
      pOp->nKey = pNode->nKey;
      pOp->pKey = sqliteMallocRaw( pOp->nKey );
      if( pOp->pKey==0 ) return SQLITE_NOMEM;
      if( sqlite_malloc_failed ) return SQLITE_NOMEM;
      memcpy( pOp->pKey, pNode->pKey, pOp->nKey );
      btreeLogRollbackOp(pCur->pRbtree, pOp);
    }

  }else{ 
    /* No need to insert a new node in the tree, as the key already exists.
     * Just clobber the current nodes data. */

    /* Set up a rollback-op in case we have to roll this operation back */
    if( pCur->pRbtree->eTransState != TRANS_ROLLBACK ){
      BtRollbackOp *pOp = sqliteMalloc( sizeof(BtRollbackOp) );
      if( pOp==0 ) return SQLITE_NOMEM;
      pOp->iTab = pCur->iTree;
      pOp->nKey = pCur->pNode->nKey;
      pOp->pKey = sqliteMallocRaw( pOp->nKey );
      if( pOp->pKey==0 ) return SQLITE_NOMEM;
      if( sqlite_malloc_failed ) return SQLITE_NOMEM;
      memcpy( pOp->pKey, pCur->pNode->pKey, pOp->nKey );
      pOp->nData = pCur->pNode->nData;
      pOp->pData = pCur->pNode->pData;
      pOp->eOp = ROLLBACK_INSERT;
      btreeLogRollbackOp(pCur->pRbtree, pOp);
    }else{
      sqliteFree( pCur->pNode->pData );