From e4f72cf3cec4c018b180fe53b427fedc3883cc6e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ole=20Andr=C3=A9=20Vadla=20Ravn=C3=A5s?= <oleavr@gmail.com>
Date: Fri, 31 May 2024 12:14:59 +0200
Subject: [PATCH] gumjs: Support returning value and binary data from RPC
 methods
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Co-authored-by: Håvard Sørbø <havard@hsorbo.no>
---
 bindings/gumjs/runtime/message-dispatcher.js | 16 +++++++++-------
 tests/gumjs/script.c                         | 14 ++++++++++++++
 2 files changed, 23 insertions(+), 7 deletions(-)

diff --git a/bindings/gumjs/runtime/message-dispatcher.js b/bindings/gumjs/runtime/message-dispatcher.js
index 6661d0414..c1d1ba2fc 100644
--- a/bindings/gumjs/runtime/message-dispatcher.js
+++ b/bindings/gumjs/runtime/message-dispatcher.js
@@ -67,13 +67,15 @@ function MessageDispatcher() {
     }
   }
 
-  function reply(id, type, result, params) {
-    params = params || [];
-
-    if (result instanceof ArrayBuffer)
-      send(['frida:rpc', id, type, undefined].concat(params), result);
-    else
-      send(['frida:rpc', id, type, result].concat(params));
+  function reply(id, type, result, params = []) {
+    if (Array.isArray(result) && result.length === 2 && result[1] instanceof ArrayBuffer) {
+      const [value, data] = result;
+      send(['frida:rpc', id, type, value, ...params], data);
+    } else if (result instanceof ArrayBuffer) {
+      send(['frida:rpc', id, type, undefined, ...params], result);
+    } else {
+      send(['frida:rpc', id, type, result, ...params]);
+    }
   }
 
   function dispatchMessages() {
diff --git a/tests/gumjs/script.c b/tests/gumjs/script.c
index 59600eed7..b442a428b 100644
--- a/tests/gumjs/script.c
+++ b/tests/gumjs/script.c
@@ -52,6 +52,7 @@ TESTLIST_BEGIN (script)
     TESTENTRY (method_can_return_null)
     TESTENTRY (method_can_receive_binary_data)
     TESTENTRY (method_can_return_binary_data)
+    TESTENTRY (method_can_return_value_and_binary_data)
     TESTENTRY (method_list_can_be_queried)
     TESTENTRY (calling_inexistent_method_should_throw_error)
   TESTGROUP_END ()
@@ -6072,6 +6073,19 @@ TESTCASE (method_can_return_binary_data)
       "59 6f");
 }
 
+TESTCASE (method_can_return_value_and_binary_data)
+{
+  COMPILE_AND_LOAD_SCRIPT (
+      "rpc.exports.read = () => {"
+          "const buf = Memory.allocUtf8String(\"Yo\");"
+          "return [{meta: 'data'}, buf.readByteArray(2)];"
+      "};");
+  POST_MESSAGE ("[\"frida:rpc\",42,\"call\",\"read\",[]]");
+  EXPECT_SEND_MESSAGE_WITH_PAYLOAD_AND_DATA (
+      "[\"frida:rpc\",42,\"ok\",{\"meta\":\"data\"}]",
+      "59 6f");
+}
+
 TESTCASE (method_list_can_be_queried)
 {
   COMPILE_AND_LOAD_SCRIPT ("rpc.exports = { a() {}, b() {}, c() {} };");