driver settings: Add load_driver_settings_file()

Allows loading an already opened driver settings file (by FD).

headers/os/drivers/driver_settings.h

@@ -24,6 +24,7 @@ extern "C" {
 #endif
 
 extern void			*load_driver_settings(const char *driverName);
+extern void			*load_driver_settings_file(int fd);
 extern status_t		unload_driver_settings(void *handle);
 
 extern void			*parse_driver_settings_string(const char *settingsString);

src/system/libroot/os/driver_settings.cpp

@@ -409,8 +409,10 @@ new_settings(char *buffer, const char *driverName)
 	handle->text = buffer;
 
 #ifdef _KERNEL_MODE
-	handle->ref_count = 1;
+	if (driverName != NULL) {
-	strlcpy(handle->name, driverName, sizeof(handle->name));
+		handle->ref_count = 1;
+		strlcpy(handle->name, driverName, sizeof(handle->name));
+	}
 #endif
 
 	if (parse_settings(handle) == B_OK)
@@ -801,6 +803,13 @@ load_driver_settings(const char *driverName)
 }
 
 
+void*
+load_driver_settings_file(int fd)
+{
+	return load_driver_settings_from_file(fd, NULL);
+}
+
+
 /*!
 	Returns a new driver_settings handle that has the parsed contents
 	of the passed string.