fix --stdout-errors handling

When using --stdout-errors, the messages written to stdout contained garbage.

Inside vfprintf(), each va_arg() consumes one entry from the va_args.
Trying to use the same va_args variable again results in undefined behavior
as subsequent va_arg() invocations continue to read from memory past the
actual variable space.

Instead, a copy has to be made with va_copy() and this be used for
outputting to stdout.

heimdall/source/Interface.cpp

@@ -92,74 +92,86 @@ void Interface::Print(const char *format, ...)
 
 void Interface::PrintWarning(const char *format, ...)
 {
-	va_list args;
-	va_start(args, format);
-
-	fprintf(stderr, "WARNING: ");
-	vfprintf(stderr, format, args);
-	fflush(stderr);
+	va_list stderrArgs;
+	va_start(stderrArgs, format);
 
 	if (stdoutErrors)
 	{
+		va_list stdoutArgs;
+		va_copy(stdoutArgs, stderrArgs);
 		fprintf(stdout, "WARNING: ");
-		vfprintf(stdout, format, args);
+		vfprintf(stdout, format, stdoutArgs);
 		fflush(stdout);
+		va_end(stdoutArgs);
 	}
 
-	va_end(args);
+	fprintf(stderr, "WARNING: ");
+	vfprintf(stderr, format, stderrArgs);
+	fflush(stderr);
+
+	va_end(stderrArgs);
 }
 
 void Interface::PrintWarningSameLine(const char *format, ...)
 {
-	va_list args;
-	va_start(args, format);
-
-	vfprintf(stderr, format, args);
-	fflush(stderr);
+	va_list stderrArgs;
+	va_start(stderrArgs, format);
 
 	if (stdoutErrors)
 	{
-		vfprintf(stdout, format, args);
+		va_list stdoutArgs;
+		va_copy(stdoutArgs, stderrArgs);
+		vfprintf(stdout, format, stdoutArgs);
 		fflush(stdout);
+		va_end(stdoutArgs);
 	}
 
-	va_end(args);
+	vfprintf(stderr, format, stderrArgs);
+	fflush(stderr);
+
+	va_end(stderrArgs);
 }
 
 void Interface::PrintError(const char *format, ...)
 {
-	va_list args;
-	va_start(args, format);
-
-	fprintf(stderr, "ERROR: ");
-	vfprintf(stderr, format, args);
-	fflush(stderr);
+	va_list stderrArgs;
+	va_start(stderrArgs, format);
 
 	if (stdoutErrors)
 	{
+		va_list stdoutArgs;
+		va_copy(stdoutArgs, stderrArgs);
 		fprintf(stdout, "ERROR: ");
-		vfprintf(stdout, format, args);
+		vfprintf(stdout, format, stdoutArgs);
 		fflush(stdout);
+		va_end(stdoutArgs);
 	}
 
-	va_end(args);
+	fprintf(stderr, "ERROR: ");
+	vfprintf(stderr, format, stderrArgs);
+	fflush(stderr);
+
+	va_end(stderrArgs);
 }
 
 void Interface::PrintErrorSameLine(const char *format, ...)
 {
-	va_list args;
-	va_start(args, format);
-
-	vfprintf(stderr, format, args);
-	fflush(stderr);
+	va_list stderrArgs;
+	va_start(stderrArgs, format);
 
 	if (stdoutErrors)
 	{
-		vfprintf(stdout, format, args);
+		va_list stdoutArgs;
+		va_copy(stdoutArgs, stderrArgs);
+		vfprintf(stdout, format, stdoutArgs);
 		fflush(stdout);
+		va_end(stdoutArgs);
 	}
 
-	va_end(args);
+	vfprintf(stderr, format, stderrArgs);
+	fflush(stderr);
+
+	va_end(stderrArgs);
 }
 
 void Interface::PrintVersion(void)