Fix exception message corruption.

Using the c_str() of a std::string after the string has been freed is unsafe
and can lead to corrupted error messages in tests, or worse.

1 files changed, 5 insertions, 10 deletions

diff --git a/lib/common/makeexception.pl.in b/lib/common/makeexception.pl.in
index e4018180..498c81b8 100755
--- a/lib/common/makeexception.pl.in
+++ b/lib/common/makeexception.pl.in
@@ -117,6 +117,7 @@ print H <<__E;
 private:
 	unsigned int mSubType;
 	std::string mMessage;
+	std::string mWhat;
 };
 
 #endif // $guardname
@@ -190,21 +191,15 @@ unsigned int ${class}Exception::GetSubType() const throw()
 
 const char * ${class}Exception::what() const throw()
 {
-	std::string what = "${class}";
-
-#ifdef EXCEPTION_CODENAMES_EXTENDED
-	if(mSubType < (sizeof(whats) / sizeof(whats[0])))
-	{
-		what = whats[mSubType];
-	}
-#endif
+	// We need to use a string that will persist after this function exits.
+	mWhat = GetMessage(mSubType);
 
 	if(mMessage != "")
 	{
-		what += ": " + mMessage;
+		mWhat += ": " + mMessage;
 	}
 
-	return what.c_str();
+	return mWhat.c_str();
 }
 
 const char * ${class}Exception::GetMessage(int SubType)