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plugins.cpp

/* ScummVM - Scumm Interpreter
 * Copyright (C) 2001  Ludvig Strigeus
 * Copyright (C) 2001-2004 The ScummVM project
 *
 * 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 2
 * 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, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 *
 * $Header: /cvsroot/scummvm/scummvm/base/plugins.cpp,v 1.35 2004/08/29 19:08:08 marcus_c Exp $
 *
 */

#include "stdafx.h"
#include "backends/fs/fs.h"
#include "base/gameDetector.h"
#include "base/plugins.h"
#include "base/engine.h"
#include "common/util.h"

/** Type of factory functions which make new Engine objects. */
typedef Engine *(*EngineFactory)(GameDetector *detector, OSystem *syst);

typedef const char *(*NameFunc)();
typedef GameList (*TargetListFunc)();
typedef DetectedGameList (*DetectFunc)(const FSList &fslist);


#ifdef DYNAMIC_MODULES

#ifdef UNIX
#include <dlfcn.h>
#define DYNAMIC_PLUGIN_PATH(name) (name "/lib" name ".so")
#else
#ifdef __DC__
#include "dcloader.h"
#define DYNAMIC_PLUGIN_PATH(name) (name ".plg")
#else
#error No support for loading plugins on non-unix systems at this point!
#endif
#endif

#endif


#pragma mark -

GameSettings Plugin::findGame(const char *gameName) const {
      // Find the GameSettings for this game
      assert(gameName);
      GameList games = getSupportedGames();
      GameSettings result = {NULL, NULL, 0};
      for (GameList::iterator g = games.begin(); g != games.end(); ++g) {
            if (!scumm_stricmp(g->name, gameName)) {
                  result = *g;
                  break;
            }
      }
      return result;
}

#pragma mark -

class StaticPlugin : public Plugin {
      const char *_name;
      EngineFactory _ef;
      DetectFunc _df;
      GameList _games;
public:
      StaticPlugin(const char *name, GameList games, EngineFactory ef, DetectFunc df)
            : _name(name), _ef(ef), _df(df), _games(games) {
      }

      const char *getName() const                           { return _name; }

      Engine *createInstance(GameDetector *detector, OSystem *syst) const {
            return (*_ef)(detector, syst);
      }

      GameList getSupportedGames() const { return _games; }
      DetectedGameList detectGames(const FSList &fslist) const {
            return (*_df)(fslist);
      }
};

#pragma mark -

#ifdef DYNAMIC_MODULES

class DynamicPlugin : public Plugin {
      void *_dlHandle;
      Common::String _filename;

      Common::String _name;
      EngineFactory _ef;
      DetectFunc _df;
      GameList _games;

      void *findSymbol(const char *symbol);

public:
      DynamicPlugin(const char *filename)
            : _dlHandle(0), _filename(filename), _ef(0), _df(0), _games() {}

      const char *getName() const                           { return _name.c_str(); }

      Engine *createInstance(GameDetector *detector, OSystem *syst) const {
            assert(_ef);
            return (*_ef)(detector, syst);
      }

      GameList getSupportedGames() const { return _games; }
      DetectedGameList detectGames(const FSList &fslist) const {
            assert(_df);
            return (*_df)(fslist);
      }

      bool loadPlugin();
      void unloadPlugin();
};

void *DynamicPlugin::findSymbol(const char *symbol) {
#if defined(UNIX)||defined(__DC__)
      void *func = dlsym(_dlHandle, symbol);
      if (!func)
            warning("Failed loading symbol '%s' from plugin '%s' (%s)", symbol, _filename.c_str(), dlerror());
      return func;
#else
#error TODO
#endif
}

bool DynamicPlugin::loadPlugin() {
      assert(!_dlHandle);
      _dlHandle = dlopen(_filename.c_str(), RTLD_LAZY);

      if (!_dlHandle) {
            warning("Failed loading plugin '%s' (%s)", _filename.c_str(), dlerror());
            return false;
      }

      // Query the plugin's name
      NameFunc nameFunc = (NameFunc)findSymbol("PLUGIN_name");
      if (!nameFunc) {
            unloadPlugin();
            return false;
      }
      _name = nameFunc();

      // Query the plugin for the targets it supports
      TargetListFunc gameListFunc = (TargetListFunc)findSymbol("PLUGIN_getSupportedGames");
      if (!gameListFunc) {
            unloadPlugin();
            return false;
      }
      _games = gameListFunc();

      // Retrieve the factory function
      _ef = (EngineFactory)findSymbol("PLUGIN_createEngine");
      if (!_ef) {
            unloadPlugin();
            return false;
      }

      // Retrieve the detector function
      _df = (DetectFunc)findSymbol("PLUGIN_detectGames");
      if (!_df) {
            unloadPlugin();
            return false;
      }

#ifdef __DC__
      dlforgetsyms(_dlHandle);
#endif

      return true;
}

void DynamicPlugin::unloadPlugin() {
      if (_dlHandle) {
            if (dlclose(_dlHandle) != 0)
                  warning("Failed unloading plugin '%s' (%s)", _filename.c_str(), dlerror());
      }
}

#endif      // DYNAMIC_MODULES

#pragma mark -

PluginManager::PluginManager() {
}

PluginManager::~PluginManager() {
      // Explicitly unload all loaded plugins
      unloadPlugins();
}

void PluginManager::loadPlugins() {
#ifdef DYNAMIC_MODULES
      // Load dynamic plugins
      // TODO... this is right now just a nasty hack. 
      // This should search one or multiple directories for all plugins it can
      // find (to this end, we maybe should use a special prefix/suffix; e.g.
      // instead of libscumm.so, use scumm.engine or scumm.plugin etc.).
      //
      // The list of directories to search could be e.g.:
      // User specified (via config file), ".", "./plugins", "$(prefix)/lib".
      //
      // We also need to add code which ensures what we are looking at is
      // a) a ScummVM engine and b) matches the version of the executable.
      // Hence one more symbol should be exported by plugins which returns
      // the "ABI" version the plugin was built for, and we can compare that
      // to the ABI version of the executable.
      #define LOAD_MODULE(name, NAME) \
            tryLoadPlugin(new DynamicPlugin(DYNAMIC_PLUGIN_PATH(name)));
#else
      // "Loader" for the static plugins
      #define LOAD_MODULE(name, NAME) \
            tryLoadPlugin(new StaticPlugin(name, Engine_##NAME##_gameList(), Engine_##NAME##_create, Engine_##NAME##_detectGames));
#endif

      // Load all plugins.
      // Right now the list is hardcoded. On the long run, of course it should
      // automatically be determined.
#ifndef DISABLE_SCUMM
      LOAD_MODULE("scumm", SCUMM);
#endif

#ifndef DISABLE_SIMON
      LOAD_MODULE("simon", SIMON);
#endif

#ifndef DISABLE_SKY
      LOAD_MODULE("sky", SKY);
#endif

#ifndef DISABLE_SWORD1
      LOAD_MODULE("sword1", SWORD1);
#endif

#ifndef DISABLE_SWORD2
      LOAD_MODULE("sword2", SWORD2);
#endif

#ifndef DISABLE_QUEEN
      LOAD_MODULE("queen", QUEEN);
#endif

#ifndef DISABLE_KYRA
      LOAD_MODULE("kyra", KYRA);
#endif

#ifndef DISABLE_SAGA
      LOAD_MODULE("saga", SAGA);
#endif
}

void PluginManager::unloadPlugins() {
      unloadPluginsExcept(NULL);
}

void PluginManager::unloadPluginsExcept(const Plugin *plugin) {
      Plugin *found = NULL;
      uint i;
      for (i = 0; i < _plugins.size(); i++) {
            if (_plugins[i] == plugin) {
                  found = _plugins[i];
            } else {
                  _plugins[i]->unloadPlugin();
                  delete _plugins[i];
            }
      }
      _plugins.clear();
      if (found != NULL) {
            _plugins.push_back(found);
      }
}

bool PluginManager::tryLoadPlugin(Plugin *plugin) {
      assert(plugin);
      // Try to load the plugin
      if (plugin->loadPlugin()) {
            // If successful, add it to the list of known plugins and return.
            _plugins.push_back(plugin);
            return true;
      } else {
            // Failed to load the plugin
            delete plugin;
            return false;
      }
}

DetectedGameList PluginManager::detectGames(const FSList &fslist) const {
      DetectedGameList candidates;

      // Iterate over all known games and for each check if it might be
      // the game in the presented directory.
      PluginList::const_iterator iter;
      for (iter = _plugins.begin(); iter != _plugins.end(); ++iter) {
            candidates.push_back((*iter)->detectGames(fslist));
      }
      
      return candidates;
}

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