XMLReader Destructor attempting to deallocate NULL pointer

[Neil Sherman <ns...@aimltd.co.uk>]

Hi all!

I have a function that is attempting to parse an XML document in the
form of a string, the code for this function is as follows:

// Initialise variables
	vl_MemBufID_str  = "prodInfo";

// Create a new memory buffer input source
	vl_MemBufInput_ptr = boost::shared_ptr<MemBufInputSource> (
					new
MemBufInputSource(reinterpret_cast<const 
						XMLByte*>
(cp_Document_str.c_str()), 
					 static_cast<m>
(cp_Document_str.size()),
vl_MemBufID_str.c_str(), 
					false));

// Convert the MemBufInputSource to a DomInputSource
	vl_InputWrapper_ptr = boost::shared_ptr<Wrapper4InputSource> (
								new 
	
Wrapper4InputSource(vl_MemBufInput_ptr.get(), 
					false));

	try
		{
// Reset the document pool
		Pvm_Parser->resetDocumentPool();

// Parse the XML string
		Pvl_DomDocument =
Pvm_Parser->parse(*vl_InputWrapper_ptr.get());

// Create a new XMLDocument
		vl_XmlDocument_ptr = boost::shared_ptr<Ctxw_XmlDocument>
(
								new
Ctxw_XmlDocument 
	
(Pvl_DomDocument));

I can continuously use this code to parse documents for about 1 1/2 days
or so and then my program will crash.  The actual crash occurs in the
destructor of XMLReader:

XMLReader::~XMLReader()
{
    fMemoryManager->deallocate(fEncodingStr);
    fMemoryManager->deallocate(fPublicId);		// <-- Crash
    fMemoryManager->deallocate(fSystemId);
    delete fStream;
    delete fTranscoder;
}

It appears it is attempting to deallocate a NULL pointer (fPublicId).
If I inspect the rest of the class it all looks ok so dosent really look
like memory corruption?  I also don't understand how the code appears to
work successfully for 1 1/2 days prior to seeing this error ?

The actual stack trace is as follows:

Xercesc_2_5::XMLReader::~XMLReader() Line 425
Xercesc_2_5::XMLReader::`scalar deleting destructor'() + 0xf
Xercesc_2_5::ReaderMgr::reset() Line 970 + 0x1f
Xercesc_2_5::IGXMLScanner::scanDocument(const xerces_2_5::InputSource
&src={...}) Line 339
Xercesc_2_5::AbstractDOMParser::parse(const xerces_2_5::InputSource &
source={...}) Line 471
Xercesc_2_5::DOMBuilderImpl::parse(const xercesc_2_5::DOMInputSource &
source={...}) Line 469
Ctxw_XmlParser::ReadXml(const
std::basic_string<char,std::char_traits<char>,std::allocator<char>>&
cp_Document_str={...}) Line 881 + 0x48
...
...

I am using version 2.5 of Xerces taken from the nightly build on the
27/07/2004.  The parser I am creating is a DOMBuilder and is created in
the class constructor with the following code :


// Create the implementation string
	bool vl_Success_bl = XMLString::transcode("LS", 
				vl_TempStr_c, 99);

// Get the DOM implementation
	Pvl_DOMImplementation = 
	DOMImplementationRegistry::getDOMImplementation(vl_TempStr_c);

// Create a new Xerces parser
	Pvm_Parser = boost::shared_ptr<DOMBuilder> 
	((dynamic_cast<DOMImplementationLS*>(Pvl_DOMImplementation))->
	createDOMBuilder(DOMImplementationLS::MODE_SYNCHRONOUS, 0));

// Set the error handler
	SetXmlErrorHandler (vm_ErrorHandler);



If there is any further information I can provide that would be useful
please let me know.

Any pointers to the potential problem would be greatly appreciated, 

Many thanks

Neil


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