support base64 writes

src/ops/index.js

@@ -577,6 +577,41 @@ export const upload_file = async (
   }
 };
 
+export const write_base64_file = async (
+  conn,
+  handle,
+  remote_path,
+  offset,
+  base64_string,
+  optional_thread_id
+) => {
+  try {
+    const buffer = new Uint8Array(new TextEncoder().encode(base64_string));
+
+    const request = new packet();
+    request.encode_utf8(remote_path);
+    request.encode_ui64(buffer.length);
+    request.encode_buffer(buffer);
+    request.encode_ui64(offset);
+    request.encode_ui64(handle);
+
+    const response = await conn.send(
+      '::RemoteFUSEWriteBase64',
+      request,
+      optional_thread_id
+    );
+    response.decode_ui32(); // Service flags
+
+    const result = response.decode_i32();
+    if (result === buffer.length) {
+      return result;
+    }
+    return Promise.reject(new Error(`'write_base64_file' error: ${result}`));
+  } catch (err) {
+    return Promise.reject(new Error(`'write_base64_file' failed: ${err}`));
+  }
+};
+
 export const write_file = async (
   conn,
   handle,