return NULL;
 
        diff_filespec_load_driver(one);
-       if (!one->driver->textconv)
-               return NULL;
-
-       if (one->driver->textconv_want_cache && !one->driver->textconv_cache) {
-               struct notes_cache *c = xmalloc(sizeof(*c));
-               struct strbuf name = STRBUF_INIT;
-
-               strbuf_addf(&name, "textconv/%s", one->driver->name);
-               notes_cache_init(c, name.buf, one->driver->textconv);
-               one->driver->textconv_cache = c;
-       }
-
-       return one->driver;
+       return userdiff_get_textconv(one->driver);
 }
 
 static void builtin_diff(const char *name_a,
 
                return NULL;
        return userdiff_find_by_name(check.value);
 }
+
+struct userdiff_driver *userdiff_get_textconv(struct userdiff_driver *driver)
+{
+       if (!driver->textconv)
+               return NULL;
+
+       if (driver->textconv_want_cache && !driver->textconv_cache) {
+               struct notes_cache *c = xmalloc(sizeof(*c));
+               struct strbuf name = STRBUF_INIT;
+
+               strbuf_addf(&name, "textconv/%s", driver->name);
+               notes_cache_init(c, name.buf, driver->textconv);
+               driver->textconv_cache = c;
+       }
+
+       return driver;
+}
 
 struct userdiff_driver *userdiff_find_by_name(const char *name);
 struct userdiff_driver *userdiff_find_by_path(const char *path);
 
+struct userdiff_driver *userdiff_get_textconv(struct userdiff_driver *driver);
+
 #endif /* USERDIFF */