[XERCESC-1207] XMLScanner::scanCharData fills XMLBuffer until out of memory

• Type: Bug
• Status: Closed
• Priority: Critical
• Resolution: Fixed
• Affects Version/s: 2.5.0
• Component/s: Non-Validating Parser
• Assignee: Unassigned
• Reporter: Dan Rosen
• Created: 10/May/04 17:51
• Updated: 29/Sep/04 19:39
• Resolved: 29/Sep/04 19:39

Description

When parsing an XML file consisting primarily of very large (hundreds of megabytes) blocks of contiguous character data, XMLScanner::scanCharData() happily attempts to build a single XMLBuffer containing all the data. Eventually the buffer becomes so large that the reallocation within XMLBuffer::insureCapacity() fails, causing std::bad_alloc to be thrown, or a crash in memcpy (depending on compiler). The fundamental problem seems to be that there is no upper bound imposed on buffer length.

In the SAX model, it is acceptable to issue multiple ContentHandler::characters() callbacks for a single contiguous block of data. The only restriction on how this should be implemented is that all characters in any single event must come from the same external entity; no further behavior is specified. So it would be perfectly conformant to the SAX model to set an upper bound on the size of a single characters() event.

(As far as I understand, allowing an upper bound in XMLScanner::scanCharData() would not affect the DOM)

I'd propose that an upper bound for character buffer size be added as an optional parameter (with some reasonable value as a default), either in the constructor of the parser or in useScanner(), and that that parameter be used to inform XMLScanner::scanCharData() when to force a call to sendCharData() to dump the buffer to its client.