winegstreamer: Return E_UNEXPECTED from WMReaderAdvanced2_OpenStream when already opened.

dlls/winegstreamer/wm_asyncreader.c

@@ -725,6 +725,13 @@ static HRESULT WINAPI WMReaderAdvanced2_OpenStream(IWMReaderAdvanced6 *iface,
 
     EnterCriticalSection(&reader->reader.cs);
 
+    if (reader->reader.wg_parser)
+    {
+        LeaveCriticalSection(&reader->reader.cs);
+        WARN("Stream is already open; returning E_UNEXPECTED.\n");
+        return E_UNEXPECTED;
+    }
+
     if (SUCCEEDED(hr = wm_reader_open_stream(&reader->reader, stream)))
         open_stream(reader, callback, context);
 

dlls/wmvcore/tests/wmvcore.c

@@ -2181,6 +2181,9 @@ static void test_async_reader_streaming(void)
     ret = WaitForSingleObject(callback.got_opened, 1000);
     ok(!ret, "Wait timed out.\n");
 
+    hr = IWMReaderAdvanced2_OpenStream(advanced, &stream.IStream_iface, &callback.IWMReaderCallback_iface, (void **)0xdeadbee0);
+    ok(hr == E_UNEXPECTED, "Got hr %#lx.\n", hr);
+
     count = 0xdeadbeef;
     hr = IWMReader_GetOutputCount(reader, &count);
     ok(hr == S_OK, "Got hr %#lx.\n", hr);