plugins.h

/* ScummVM - Graphic Adventure Engine
 *
 * ScummVM is the legal property of its developers, whose names
 * are too numerous to list here. Please refer to the COPYRIGHT
 * file distributed with this source distribution.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

#ifndef BASE_PLUGINS_H
#define BASE_PLUGINS_H

#include "common/array.h"
#include "common/fs.h"
#include "common/str.h"
#include "backends/plugins/elf/version.h"

#if defined(USE_ELF_LOADER) && defined(ELF_LOADER_CXA_ATEXIT)
#include <cxxabi.h>
#endif

#define INCLUDED_FROM_BASE_PLUGINS_H
#include "base/internal_plugins.h"
#undef INCLUDED_FROM_BASE_PLUGINS_H


// Plugin versioning

#define PLUGIN_VERSION 1

enum PluginType {
    PLUGIN_TYPE_ENGINE_DETECTION = 0,
    PLUGIN_TYPE_ENGINE,
    PLUGIN_TYPE_MUSIC,
    PLUGIN_TYPE_DETECTION,
    PLUGIN_TYPE_SCALER,

    PLUGIN_TYPE_MAX
};

// TODO: Make the engine API version depend on ScummVM's version
// because of the back linking (possibly from the checkout revision)
#define PLUGIN_TYPE_ENGINE_DETECTION_VERSION 1
#define PLUGIN_TYPE_ENGINE_VERSION 2
#define PLUGIN_TYPE_MUSIC_VERSION 1
#define PLUGIN_TYPE_DETECTION_VERSION 1
#define PLUGIN_TYPE_SCALER_VERSION 1

extern const int pluginTypeVersions[PLUGIN_TYPE_MAX];


// Plugin linking

// see comments in backends/plugins/elf/elf-provider.cpp
#if defined(USE_ELF_LOADER) && defined(ELF_LOADER_CXA_ATEXIT)
#define PLUGIN_DYNAMIC_DSO_HANDLE \
    uint32 __dso_handle __attribute__((visibility("hidden"))) = 0;
// Exported helper that runs __cxa_finalize from inside the plugin, so the
// &__dso_handle argument is the plugin's own resolved address -- the same one
// GCC embedded in its __cxa_atexit calls. Calling __cxa_finalize from the host
// with a findSymbol() lookup is fragile (see elf-provider.cpp).
#define PLUGIN_DYNAMIC_FINALIZE \
    PLUGIN_EXPORT void PLUGIN_finalize() { __cxxabiv1::__cxa_finalize(&__dso_handle); }
#else
#define PLUGIN_DYNAMIC_DSO_HANDLE
#define PLUGIN_DYNAMIC_FINALIZE
#endif

#ifdef USE_ELF_LOADER
#define PLUGIN_DYNAMIC_BUILD_DATE \
    PLUGIN_EXPORT const char *PLUGIN_getBuildDate() { return gScummVMPluginBuildDate; }
#else
#define PLUGIN_DYNAMIC_BUILD_DATE
#endif

#define REGISTER_PLUGIN_STATIC(ID,TYPE,PLUGINCLASS) \
    extern const PluginType g_##ID##_type; \
    const PluginType g_##ID##_type = TYPE; \
    PluginObject *g_##ID##_getObject() { \
        return new PLUGINCLASS(); \
    } \
    void dummyFuncToAllowTrailingSemicolon_##ID##_()

#ifdef DYNAMIC_MODULES

#define REGISTER_PLUGIN_DYNAMIC(ID,TYPE,PLUGINCLASS) \
    extern "C" { \
        PLUGIN_DYNAMIC_DSO_HANDLE \
        PLUGIN_DYNAMIC_FINALIZE \
        PLUGIN_DYNAMIC_BUILD_DATE \
        PLUGIN_EXPORT int32 PLUGIN_getVersion() { return PLUGIN_VERSION; } \
        PLUGIN_EXPORT int32 PLUGIN_getType() { return TYPE; } \
        PLUGIN_EXPORT int32 PLUGIN_getTypeVersion() { return TYPE##_VERSION; } \
        PLUGIN_EXPORT PluginObject *PLUGIN_getObject() { \
            return new PLUGINCLASS(); \
        } \
    } \
    void dummyFuncToAllowTrailingSemicolon_##ID##_()

#endif // DYNAMIC_MODULES


// Abstract plugins

class PluginObject {
public:
    virtual ~PluginObject() {}

    virtual const char *getName() const = 0;
};

class Plugin {
protected:
    PluginObject *_pluginObject;
    PluginType _type;

public:
    Plugin() : _pluginObject(0), _type(PLUGIN_TYPE_MAX) {}
    virtual ~Plugin() {
        //if (isLoaded())
            //unloadPlugin();
    }

//  virtual bool isLoaded() const = 0; // TODO
    virtual bool loadPlugin() = 0;     // TODO: Rename to load() ?
    virtual void unloadPlugin() = 0;   // TODO: Rename to unload() ?

    PluginType getType() const;
    const char *getName() const;

    template <class T>
    T &get() const {
        T *pluginObject = dynamic_cast<T *>(_pluginObject);
        if (!pluginObject) {
            error("Invalid cast of plugin %s", getName());
        }
        return *pluginObject;
    }

    virtual Common::Path getFileName() const { return Common::Path(); }
};

class StaticPlugin : public Plugin {
public:
    StaticPlugin(PluginObject *pluginobject, PluginType type);
    ~StaticPlugin();
    virtual bool loadPlugin();
    virtual void unloadPlugin();
};


typedef Common::Array<Plugin *> PluginList;

class PluginProvider {
public:
    virtual ~PluginProvider() {}

    virtual PluginList getPlugins() = 0;

    virtual bool isFilePluginProvider() { return false; }
};

#ifdef DYNAMIC_MODULES

class FilePluginProvider : public PluginProvider {
public:
    virtual PluginList getPlugins();

    bool isFilePluginProvider() { return true; }

protected:
    virtual Plugin *createPlugin(const Common::FSNode &node) const = 0;

    virtual bool isPluginFilename(const Common::FSNode &node) const;

    virtual void addCustomDirectories(Common::FSList &dirs) const;
};

#endif // DYNAMIC_MODULES

#define PluginMan PluginManager::instance()

class PluginManager {
protected:
    typedef Common::Array<PluginProvider *> ProviderList;

    PluginList _pluginsInMem[PLUGIN_TYPE_MAX];
    ProviderList _providers;

    bool tryLoadPlugin(Plugin *plugin);
    void addToPluginsInMemList(Plugin *plugin);
    const Plugin *findLoadedPlugin(const Common::String &engineId);

    static PluginManager *_instance;
    PluginManager();

    void unloadAllPlugins();
public:
    virtual ~PluginManager();

    static void destroy() { delete _instance; _instance = 0; }
    static PluginManager &instance();

    void addPluginProvider(PluginProvider *pp);

    const Plugin *findEnginePlugin(const Common::String &engineId);

    // Functions used by the uncached PluginManager
    virtual void init() {}
    virtual void loadFirstPlugin() {}
    virtual bool loadNextPlugin() { return false; }
    virtual bool loadPluginFromEngineId(const Common::String &engineId) { return false; }
    virtual void updateConfigWithFileName(const Common::String &engineId) {}
    virtual void loadDetectionPlugin() {}
    virtual void unloadDetectionPlugin() {}

    // Functions used only by the cached PluginManager
    virtual void loadAllPlugins();
    virtual void loadAllPluginsOfType(PluginType type);

    void unloadPluginsExcept(PluginType type, const Plugin *plugin, bool deletePlugin = true);

    const PluginList &getPlugins(PluginType t) { return _pluginsInMem[t]; }
};

class PluginManagerUncached : public PluginManager {
protected:
    friend class PluginManager;
    PluginList _allEnginePlugins;
    Plugin  *_detectionPlugin;
    PluginList::iterator _currentPlugin;

    bool _isDetectionLoaded;

    PluginManagerUncached() : _detectionPlugin(nullptr), _currentPlugin(nullptr), _isDetectionLoaded(false) {}
    bool loadPluginByFileName(const Common::Path &filename);

public:
    virtual ~PluginManagerUncached();
    void init() override;
    void loadFirstPlugin() override;
    bool loadNextPlugin() override;
    bool loadPluginFromEngineId(const Common::String &engineId) override;
    void updateConfigWithFileName(const Common::String &engineId) override;
#ifndef DETECTION_STATIC
    void loadDetectionPlugin() override;
    void unloadDetectionPlugin() override;
#endif

    void loadAllPlugins() override {}   // we don't allow these
    void loadAllPluginsOfType(PluginType type) override {}
};

#endif