util/UriUtil: move code to SkipUriScheme()

src/util/UriUtil.cxx

@@ -104,18 +104,27 @@ uri_safe_local(const char *uri)
 	}
 }
 
-std::string
-uri_remove_auth(const char *uri)
+gcc_pure
+static const char *
+SkipUriScheme(const char *uri)
 {
-	const char *auth;
 	if (memcmp(uri, "http://", 7) == 0)
-		auth = uri + 7;
+		return uri + 7;
 	else if (memcmp(uri, "https://", 8) == 0)
-		auth = uri + 8;
+		return uri + 8;
 	else if (memcmp(uri, "ftp://", 6) == 0)
-		auth = uri + 6;
+		return uri + 6;
 	else
 		/* unrecognized URI */
+		return nullptr;
+}
+
+std::string
+uri_remove_auth(const char *uri)
+{
+	const char *auth = SkipUriScheme(uri);
+	if (auth == nullptr)
+		/* unrecognized URI */
 		return std::string();
 
 	const char *slash = strchr(auth, '/');