winegstreamer: Return E_UNEXPECTED from WMReader_Open when already opened.

dlls/winegstreamer/wm_asyncreader.c

@@ -222,6 +222,13 @@ static HRESULT WINAPI WMReader_Open(IWMReader *iface, const WCHAR *url,
 
     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_file(&reader->reader, url)))
         open_stream(reader, callback, context);
 

dlls/wmvcore/tests/wmvcore.c

@@ -2541,6 +2541,9 @@ static void test_async_reader_file(void)
     ret = WaitForSingleObject(callback.got_opened, 1000);
     ok(!ret, "Wait timed out.\n");
 
+    hr = IWMReader_Open(reader, filename, &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);