Sanitize relative paths server-side

backend/sync_server/src/utils.rs

@@ -0,0 +1,12 @@
+/// Sanitize the document's path to allow all clients to create the same path in
+/// their filesystem. If we didn't do this server-side, client's would need to
+/// deal with mapping invalid names to valid ones and then back.
+pub fn sanitize_path(path: &str) -> String {
+    let options = sanitize_filename::Options {
+        truncate: true,
+        windows: true, // Windows is the lowest common denominator
+        replacement: "",
+    };
+
+    sanitize_filename::sanitize_with_options(path, options)
+}