C++, libxslt: Freeing the stylesheet document after freeing the style sheet results in crash

Question

I'm using libxml2 with libxslt for XML processing from a C++ program. For transforming XML documents with XSL, I use the following function (error handling removed):

xmlDocPtr
transformXmlDocument(
    const xmlDocPtr inputDocument,
    const std::string& stylesheetString
    ) {

    exsltRegisterAll();

    // Read the stylesheet document.
    xmlDocPtr stylesheetDocument = xmlReadMemory(
            stylesheetString.c_str(),
            stylesheetString.length(),
            "stylesheet.xsd",
            0, // No encoding set - get it from the file header.
            0  // No further options.
    );

    // Parse the stylesheet
    xsltStylesheetPtr stylesheet = xsltParseStylesheetDoc(stylesheetDocument);

    // Transform the document
    xmlDocPtr result = xsltApplyStylesheet(stylesheet, inputDocument, 0);

    // Free used resources
    xsltFreeStylesheet(stylesheet);
    xsltCleanupGlobals();

    // Here the program crashes
    xmlFreeDoc(stylesheetDocument);

    return result;
}

The problem is that the program crashes with an access violation (glibc says: free(): invalid pointer: 0x00000000026d8090 *) in the second last line.

I can't find any hints in the docs that xsltFreeStylesheet also frees the underlying document or something, so what is wrong here?

Answer 1

xsltFreeStylesheet also frees the underlying document or something

The fine manual has some hints which would suggest that there's indeed a chance of this scenario happening.