/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/*
* $Id: StackGuard.java 468645 2006-10-28 06:57:24Z minchau $
*/
package org.apache.xalan.transformer;
import javax.xml.transform.TransformerException;
import org.apache.xalan.res.XSLMessages;
import org.apache.xalan.templates.Constants;
import org.apache.xalan.templates.ElemTemplate;
import org.apache.xalan.templates.ElemTemplateElement;
import org.apache.xml.utils.ObjectStack;
/**
* Class to guard against recursion getting too deep.
*/
public class StackGuard
{
/**
* Used for infinite loop check. If the value is -1, do not
* check for infinite loops. Anyone who wants to enable that
* check should change the value of this variable to be the
* level of recursion that they want to check. Be careful setting
* this variable, if the number is too low, it may report an
* infinite loop situation, when there is none.
* Post version 1.0.0, we'll make this a runtime feature.
*/
private int m_recursionLimit = -1;
TransformerImpl m_transformer;
/**
* Get the recursion limit.
* Used for infinite loop check. If the value is -1, do not
* check for infinite loops. Anyone who wants to enable that
* check should change the value of this variable to be the
* level of recursion that they want to check. Be careful setting
* this variable, if the number is too low, it may report an
* infinite loop situation, when there is none.
* Post version 1.0.0, we'll make this a runtime feature.
*
* @return The recursion limit.
*/
public int getRecursionLimit()
{
return m_recursionLimit;
}
/**
* Set the recursion limit.
* Used for infinite loop check. If the value is -1, do not
* check for infinite loops. Anyone who wants to enable that
* check should change the value of this variable to be the
* level of recursion that they want to check. Be careful setting
* this variable, if the number is too low, it may report an
* infinite loop situation, when there is none.
* Post version 1.0.0, we'll make this a runtime feature.
*
* @param limit The recursion limit.
*/
public void setRecursionLimit(int limit)
{
m_recursionLimit = limit;
}
/**
* Constructor StackGuard
*
*/
public StackGuard(TransformerImpl transformerImpl)
{
m_transformer = transformerImpl;
}
/**
* Overide equal method for StackGuard objects
*
*/
public int countLikeTemplates(ElemTemplate templ, int pos)
{
ObjectStack elems = m_transformer.getCurrentTemplateElements();
int count = 1;
for (int i = pos-1; i >= 0; i--)
{
if((ElemTemplateElement)elems.elementAt(i) == templ)
count++;
}
return count;
}
/**
* Get the next named or match template down from and including
* the given position.
* @param pos the current index position in the stack.
* @return null if no matched or named template found, otherwise
* the next named or matched template at or below the position.
*/
private ElemTemplate getNextMatchOrNamedTemplate(int pos)
{
ObjectStack elems = m_transformer.getCurrentTemplateElements();
for (int i = pos; i >= 0; i--)
{
ElemTemplateElement elem = (ElemTemplateElement) elems.elementAt(i);
if(null != elem)
{
if(elem.getXSLToken() == Constants.ELEMNAME_TEMPLATE)
{
return (ElemTemplate)elem;
}
}
}
return null;
}
/**
* Check if we are in an infinite loop
*
* @throws TransformerException
*/
public void checkForInfinateLoop() throws TransformerException
{
int nTemplates = m_transformer.getCurrentTemplateElementsCount();
if(nTemplates < m_recursionLimit)
return;
if(m_recursionLimit <= 0)
return; // Safety check.
// loop from the top index down to the recursion limit (I don't think
// there's any need to go below that).
for (int i = (nTemplates - 1); i >= m_recursionLimit; i--)
{
ElemTemplate template = getNextMatchOrNamedTemplate(i);
if(null == template)
break;
int loopCount = countLikeTemplates(template, i);
if (loopCount >= m_recursionLimit)
{
// throw new TransformerException("Template nesting too deep. nesting = "+loopCount+
// ", template "+((null == template.getName()) ? "name = " : "match = ")+
// ((null != template.getName()) ? template.getName().toString()
// : template.getMatch().getPatternString()));
String idIs = XSLMessages.createMessage(((null != template.getName()) ? "nameIs" : "matchPatternIs"), null);
Object[] msgArgs = new Object[]{ new Integer(loopCount), idIs,
((null != template.getName()) ? template.getName().toString()
: template.getMatch().getPatternString()) };
String msg = XSLMessages.createMessage("recursionTooDeep", msgArgs);
throw new TransformerException(msg);
}
}
}
}