[XALANJ-1901] DTMManagerDefault.getDTM() incorrectly returns null

• Type: Bug
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 2.6
• Component/s: DTM
• Security Level: No security risk; visible to anyone (Ordinary problems in Xalan projects. Anybody can view the issue.)
• Environment: Operating System: Other; Platform: All
• Bugzilla Id: 29893
• Assignee: Unassigned
• Reporter: John J. Barton
• Created: 03/Jul/04 05:41
• Updated: 16/Feb/11 23:01

Description

The following suggested fix for
org.apache.xml.dtm.ref.XTMManagerDefault.getDTM()
relates to Bug 22217
NullPointerException in TransformerImpl.run() when reusing XMLFilter object
http://nagoya.apache.org/bugzilla/show_bug.cgi?id=22217

=======================================================================
In the interface file we read:

/*

• $Id: DTMManager.java,v 1.18 2004/02/23 10:29:36 aruny Exp $
  */
  package org.apache.xml.dtm;
  ....
  /**
• Get the instance of DTM that "owns" a node handle.
  *
• @param nodeHandle the nodeHandle.
  *
• @return a non-null DTM reference.
  */
  public abstract DTM getDTM(int nodeHandle);
  ======================================================================
  Note in particular that the return is non-null.

In the implementation we read:
======================================================================

/*

• $Id: DTMManagerDefault.java,v 1.51 2004/02/16 23:06:11 minchau Exp $
  */
  package org.apache.xml.dtm.ref;
  ....
  /**
• Return the DTM object containing a representation of this node.
  *
• @param nodeHandle DTM Handle indicating which node to retrieve
  *
• @return a reference to the DTM object containing this node.
  */
  synchronized public DTM getDTM(int nodeHandle)
  Unknown macro: { try { // Performance critical function. return m_dtms[nodeHandle >>> IDENT_DTM_NODE_BITS]; } catch(java.lang.ArrayIndexOutOfBoundsException e) { if(nodeHandle==DTM.NULL) return null; // Accept as a special case. else throw e; // Programming error; want to know about it. } }

  ====================================================================
  In addition to the "special case", the array m_dtms can have "null"
  values that are returned, contrary to the interface documentation.

Callers of getDTM() use the return value without checking for null,
for example
=======================================================================
/*

• $Id: TransformerImpl.java,v 1.158 2004/02/23 21:33:14 igorh Exp $
  */
  package org.apache.xalan.transformer;
  ...
  public boolean applyTemplateToNode(ElemTemplateElement xslInstruction, //
  xsl:apply-templates or xsl:for-each
  ElemTemplate template, int child)
  throws TransformerException
  {

DTM dtm = m_xcontext.getDTM(child);
short nodeType = dtm.getNodeType(child); <<<<<<<<<<<< NPE!!

boolean isDefaultTextRule = false;
boolean isApplyImports = false;
...
=================================================================
In my opinion getDTM() should be thus:
==================================================================
/**

• Return the DTM object containing a representation of this node.
  *
• @param nodeHandle DTM Handle indicating which node to retrieve
  *
• @return a reference to the DTM object containing this node.
  */
  synchronized public DTM getDTM(int nodeHandle)
  Unknown macro: { // Performance critical function. DTM dtm = m_dtms[nodeHandle >>> IDENT_DTM_NODE_BITS]; if (dtm != null) { return dtm; } else { throw new TransformerException(this.getClass().getName() +" Document Table contains null pointer for nodeHandle="+nodeHandle); } }