Fixed error handling of invalid XSL transformations

* xalan is segfaulting in XalanDOMString constructor when the static member "XalanLocator::getSystemId" is returning null-pointer
** this should seemingly be handled by passing a pointer to the static constant m_dummy but this sadly fails to prevent the segfault
** the patch provided by this commit fixes the problem for now but I cannot guarantee that this wont cause any side effects in a other context
* Adapted TransformationFacade to handle errors during transformation compilation
** errors generated during transformation compilation are returned through the generate member method
** throwing an exeception during TransformationFacade construction would require additional error handling in the calling code
* Added xalan::ProblemListener functionality to the ErrorHandler class
** XSLT problems passed to the ProblemListener are returned alongside to and treated as all other transformation errors

2 files changed, 80 insertions, 1 deletions

diff --git a/src/support/error_handler.cc b/src/support/error_handler.cc
index db54225..2ca721d 100644
--- a/src/support/error_handler.cc
+++ b/src/support/error_handler.cc
@@ -4,6 +4,7 @@
 
 #include <iostream>
 
+#include "support/xalan_string.h"
 #include "support/xerces_string_guard.h"
 
 namespace {
@@ -47,6 +48,52 @@ void ErrorHandler::fatalError(const xercesc::SAXParseException& exception) {
 
 void ErrorHandler::resetErrors() { }
 
+void ErrorHandler::problem(
+	xalan::ProblemListenerBase::eSource,
+	xalan::ProblemListenerBase::eClassification,
+	const xalan::XalanDOMString& message,
+	const xalan::Locator*,
+	const xalan::XalanNode*
+) {
+	this->constructErrorCache();
+
+	this->error_cache_->emplace_back(
+		"XSLT problem: " + toString(message)
+	);
+}
+
+void ErrorHandler::problem(
+	xalan::ProblemListenerBase::eSource,
+	xalan::ProblemListenerBase::eClassification,
+	const xalan::XalanNode*,
+	const xalan::ElemTemplateElement*,
+	const xalan::XalanDOMString& message,
+	const xalan::XalanDOMChar*,
+	xalan::XalanFileLoc,
+	xalan::XalanFileLoc
+) {
+	this->constructErrorCache();
+
+	this->error_cache_->emplace_back(
+		"XSLT problem: " + toString(message)
+	);
+}
+
+void ErrorHandler::problem(
+	xalan::ProblemListenerBase::eSource,
+	xalan::ProblemListenerBase::eClassification,
+	const xalan::XalanDOMString& message,
+	const xalan::XalanNode*
+) {
+	this->constructErrorCache();
+
+	this->error_cache_->emplace_back(
+		"XSLT problem: " + toString(message)
+	);
+}
+
+void ErrorHandler::setPrintWriter(xalan::PrintWriter*) { }
+
 auto ErrorHandler::getCachedErrors() -> error_cache_ptr {
 	return error_cache_ptr(this->error_cache_.release());
 }
diff --git a/src/support/error_handler.h b/src/support/error_handler.h
index 77a46d8..02d741e 100644
--- a/src/support/error_handler.h
+++ b/src/support/error_handler.h
@@ -2,14 +2,18 @@
 #define INPUTXSLT_SRC_SUPPORT_ERROR_HANDLER_H_
 
 #include <xercesc/sax/ErrorHandler.hpp>
+#include <xalanc/XSLT/ProblemListener.hpp>
 
 #include <memory>
 #include <vector>
 #include <string>
 
+#include "common.h"
+
 namespace InputXSLT {
 
-class ErrorHandler : public xercesc::ErrorHandler {
+class ErrorHandler : public xercesc::ErrorHandler,
+                     public xalan::ProblemListener {
 	public:
 		typedef std::vector<std::string> error_cache;
 		typedef std::unique_ptr<error_cache> error_cache_ptr;
@@ -21,6 +25,34 @@ class ErrorHandler : public xercesc::ErrorHandler {
 		virtual void fatalError(const xercesc::SAXParseException&);
 		virtual void resetErrors();
 
+		virtual void problem(
+			xalan::ProblemListenerBase::eSource,
+			xalan::ProblemListenerBase::eClassification,
+			const xalan::XalanDOMString&,
+			const xalan::Locator*,
+			const xalan::XalanNode*
+		);
+
+		virtual void problem(
+			xalan::ProblemListenerBase::eSource,
+			xalan::ProblemListenerBase::eClassification,
+			const xalan::XalanNode*,
+			const xalan::ElemTemplateElement*,
+			const xalan::XalanDOMString&,
+			const xalan::XalanDOMChar*,
+			xalan::XalanFileLoc,
+			xalan::XalanFileLoc
+		);
+
+		virtual void problem(
+			xalan::ProblemListenerBase::eSource,
+			xalan::ProblemListenerBase::eClassification,
+			const xalan::XalanDOMString&,
+			const xalan::XalanNode*
+		);
+
+		virtual void setPrintWriter(xalan::PrintWriter*);
+
 		error_cache_ptr getCachedErrors();
 
 	private: