[Bug 1329] New - SAX2XMLReaderImpl leaks XMLBuffers

[bu...@apache.org]

http://nagoya.apache.org/bugzilla/show_bug.cgi?id=1329

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+ +============================================================================+
+ | SAX2XMLReaderImpl leaks XMLBuffers                                         |
+ +----------------------------------------------------------------------------+
+ |        Bug #: 1329                        Product: Xerces-C                |
+ |       Status: NEW                         Version: 1.4                     |
+ |   Resolution:                            Platform: PC                      |
+ |     Severity: Major                    OS/Version:                         |
+ |     Priority:                           Component: SAX/SAX2                |
+ +----------------------------------------------------------------------------+
+ |  Assigned To: xerces-c-dev@xml.apache.org                                  |
+ |  Reported By: aneilson@webplan.com                                         |
+ |      CC list: Cc:                                                          |
+ +----------------------------------------------------------------------------+
+ |          URL:                                                              |
+ +============================================================================+
+ |                              DESCRIPTION                                   |
+ Overview Description:
+ The implementations of SAX2XMLReaderImpl::startElement and 
+ SAX2XMLReaderImpl::endElement will leak buffers in the case where the 
+ ContentHandler throws an exception. If you reuse instances of the same 
+ XMLReader repeatedly, XMLBufferManager::bidOnBuffer will eventually throw an 
+ XMLExcepts::BufMgr_NoMoreBuffers.
+ 
+ Steps to Reproduce:
+ The following sample code illustrates this problem (built using Microsoft 
+ Visual C++ 6 SP5):
+ //-----------------------------------------------------------------------------
+ // SAX2BufferLeak.cpp - demonstrates a bug in Xerces-c 1.4.0
+ #include "stdafx.h"
+ 
+ #include <iostream>
+ 
+ #include <util/PlatformUtils.hpp>
+ #include <sax2/DefaultHandler.hpp>
+ #include <sax2/XMLReaderFactory.hpp>
+ #include <framework/MemBufInputSource.hpp>
+ 
+ using namespace std;
+ 
+ 
+ class ErrorThrowingContentHandler : public DefaultHandler
+ {
+ public:
+ 
+     virtual void startElement(	
+ 		const XMLCh* const uri,
+ 		const XMLCh* const localname,
+ 		const XMLCh* const qname,
+ 		const Attributes&  attributes)
+ 	{
+ 		throw true;
+ 	};
+ 
+     virtual void fatalError(const SAXParseException& exception)
+ 	{
+ 		throw exception;
+ 	};
+ 
+ };
+ 
+ 
+ int main(int argc, char* argv[])
+ {
+ 	XMLPlatformUtils::Initialize();
+ 
+ 	SAX2XMLReader* reader = XMLReaderFactory::createXMLReader();
+ 	
+ 	ErrorThrowingContentHandler* handler = new ErrorThrowingContentHandler
+ ();
+ 	reader->setContentHandler(handler);
+ 	reader->setErrorHandler(handler);
+ 
+ 	for (size_t i = 0; i < 35; i++)
+ 	{
+ 		MemBufInputSource is((XMLByte*)"<x:e1 
+ xmlns:x=\"urn:mynamespace\"></x:e1>", 39, L"FakeSystemID");
+ 
+ 		try
+ 		{
+ 			reader->parse(is);
+ 		}
+ 		catch(bool)
+ 		{
+ 			// Do nothing - we expect this to happen
+ 		}
+ 		catch(SAXParseException& e)
+ 		{
+ 			wcout	<< L"SAXParseException"  << endl
+ 					<< L"i=" << i << endl
+ 					<< L"Message: " << e.getMessage() << 
+ endl;
+ 			break;
+ 		}
+ 	}
+ 
+ 	XMLPlatformUtils::Terminate();
+ 
+ 	return 0;
+ }
+ //-----------------------------------------------------------------------------
+ 
+ This program will print the following on the console:
+ 
+ SAXParseException
+ i=31
+ Message: An exception occured! Type:RuntimeException, Message:The buffer manager
+  cannot provide any more buffers
+ 
+ Expected Results:
+ The above program should print out nothing.
+ 
+ Additional Information:
+ SAX2XMLReaderImpl does not manage the fStringBuffer, fPrefixes and prefixCounts 
+ members properly in the case where:
+ 
+ - The document uses namespaces.
+ - An errorHandler stops the parse by throwing an exception.
+ 
+ This problem only becomes apparent when you attempt to reuse a SAX2XMLReader 
+ repeatedly. The case in point is in the SOAP service we have implemented. It 
+ maintains a thread pool with a complete SAX pipeline setup on each thread. This 
+ is critical for performance reasons (and is a generally good approch when 
+ possible).
+ 
+ Possible solutions include try/catch blocks to SAX2XMLReader::startElement and 
+ SAX2XMLReader::endElement, or simply ensuring the the fStringBuffer, fPrefixes 
+ and prefixCount (any others?) are reset properly on each reuse of the parser.

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