libvlc API symbol loader routines

Change-Id: I6800c7a75dbcdec53119f5f4da341aeb33c9d574

avmedia/source/vlc/wrapper/SymbolLoader.hxx

+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/*
+ * This file is part of the LibreOffice project.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ *
+ * This file incorporates work covered by the following license notice:
+ *
+ *   Licensed to the Apache Software Foundation (ASF) under one or more
+ *   contributor license agreements. See the NOTICE file distributed
+ *   with this work for additional information regarding copyright
+ *   ownership. The ASF licenses this file to you under the Apache
+ *   License, Version 2.0 (the "License"); you may not use this file
+ *   except in compliance with the License. You may obtain a copy of
+ *   the License at http://www.apache.org/licenses/LICENSE-2.0 .
+ */
+#ifndef _SYMBOL_LOADER_HXX
+#define _SYMBOL_LOADER_HXX
+#include <iostream>
+#include <osl/module.h>
+#include <rtl/ustring.hxx>
+
+#define SYM_MAP(a) { #a, (SymbolFunc *)&a }
+
+typedef void (*SymbolFunc) (void);
+
+struct ApiMap
+{
+    const char *symName;
+    SymbolFunc *refValue;
+};
+
+namespace
+{
+    const char *libNames[] = {
+        "libvlc.so.5",
+        "libvlccore.so.5"
+    };
+
+    template<size_t N> static bool
+    tryLink( oslModule &aModule, const char *pName, const ApiMap ( &pMap )[N] )
+    {
+        for (uint i = 0; i < N; ++i)
+        {
+            SymbolFunc aMethod = ( SymbolFunc )osl_getFunctionSymbol
+                ( aModule, OUString::createFromAscii ( pMap[ i ].symName ).pData );
+            if ( !aMethod )
+                return false;
+
+            *pMap[ i ].refValue = aMethod;
+        }
+
+        return true;
+    }
+}
+
+template<size_t N>
+bool InitApiMap( const ApiMap ( &pMap )[N]  )
+{
+    oslModule aModule;
+
+    for (uint j = 0; j < sizeof(libNames) / sizeof(libNames[0]); ++j)
+    {
+        aModule = osl_loadModule( OUString::createFromAscii
+                                  ( libNames[ j ] ).pData,
+                                  SAL_LOADMODULE_DEFAULT );
+
+        if( aModule == NULL)
+            continue;
+
+        tryLink( aModule, libNames[ j ], pMap );
+
+        osl_unloadModule( aModule );
+    }
+
+    return false;
+}
+
+#endif
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */