avm1: Prevent panic when close is called in event handler

Also adds a test case for this.

core/src/socket.rs

@@ -321,10 +321,13 @@ impl<'gc> Sockets<'gc> {
                             let xml_socket =
                                 XmlSocket::cast(target.into()).expect("target should be XmlSocket");
 
+                            // Get XmlSocket read buffer.
                             let mut buffer = xml_socket.read_buffer();
                             buffer.extend(data);
 
-                            // Check for a message.
+                            let mut messages = vec![];
+
+                            // Check for messages.
                             while let Some((index, _)) =
                                 buffer.iter().enumerate().find(|(_, &b)| b == 0)
                             {
@@ -332,8 +335,14 @@ impl<'gc> Sockets<'gc> {
                                 // Remove null byte.
                                 let _ = buffer.drain(..1);
 
-                                let message = AvmString::new_utf8_bytes(activation.gc(), &message);
+                                // Store the message in cache.
+                                messages.push(AvmString::new_utf8_bytes(activation.gc(), &message));
+                            }
 
+                            // Drop the reference to the buffer, to make sure the SWF can call with close.
+                            drop(buffer);
+
+                            for message in messages {
                                 let _ = target.call_method(
                                     "onData".into(),
                                     &[message.into()],

tests/tests/swfs/avm1/xml_socket_close_in_handler/output.txt

@@ -0,0 +1,6 @@
+connected
+true
+data:
+Hello!
+Closing socket in onData handler
+Successfully closed socket

tests/tests/swfs/avm1/xml_socket_close_in_handler/socket.json

@@ -0,0 +1,13 @@
+[
+    {
+        "type": "Send",
+        "payload": [ 72, 101, 108, 108, 111, 33, 0 ]
+    },
+    {
+        "type": "Send",
+        "payload": [ 60, 114, 111, 111, 116, 62, 60, 105, 116, 101, 109, 32, 47, 62, 60, 47, 114, 111, 111, 116, 62, 0 ]
+    },
+    {
+        "type": "WaitForDisconnect"
+    }
+]

tests/tests/swfs/avm1/xml_socket_close_in_handler/test.as

@@ -0,0 +1,23 @@
+class Test {
+    static function main() {
+        var socket = new XMLSocket();
+
+        socket.onConnect = function (status:Boolean) {
+            trace("connected");
+            trace(status);
+        };
+
+        socket.onData = function (data:String) {
+            trace("data:")
+            trace(data);
+            trace("Closing socket in onData handler");
+            socket.close();
+            trace("Successfully closed socket");
+        };
+        socket.onClose = function () {
+            trace("closed");
+        };
+
+        socket.connect("localhost", 8001);
+    }
+}

tests/tests/swfs/avm1/xml_socket_close_in_handler/test.toml

@@ -0,0 +1 @@
+num_ticks = 10