Started to refactor the plugin code (moving backend specific stuff into backends/plugins/)

svn-id: r24148

4 files changed, 347 insertions, 0 deletions

diff --git a/backends/module.mk b/backends/module.mk
index 5542d0365a..0e648eb5b7 100644
--- a/backends/module.mk
+++ b/backends/module.mk
@@ -13,6 +13,7 @@ MODULE_OBJS := \
 	midi/quicktime.o \
 	midi/seq.o \
 	midi/windows.o \
+	plugins/posix/posix-provider.o \
 	saves/savefile.o \
 	saves/default/default-saves.o \
 	timer/default/default-timer.o
diff --git a/backends/plugins/dynamic-plugin.h b/backends/plugins/dynamic-plugin.h
new file mode 100644
index 0000000000..59c3af9a61
--- /dev/null
+++ b/backends/plugins/dynamic-plugin.h
@@ -0,0 +1,126 @@
+/* ScummVM - Scumm Interpreter
+ * Copyright (C) 2001  Ludvig Strigeus
+ * Copyright (C) 2001-2006 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * $URL$
+ * $Id$
+ *
+ */
+
+#ifndef BACKENDS_PLUGINS_DYNAMICPLUGIN_H
+#define BACKENDS_PLUGINS_DYNAMICPLUGIN_H
+
+#include "common/stdafx.h"
+#include "base/plugins.h"
+
+
+/** Type of factory functions which make new Engine objects. */
+typedef PluginError (*EngineFactory)(OSystem *syst, Engine **engine);
+
+typedef const char *(*NameFunc)();
+typedef GameDescriptor (*GameIDQueryFunc)(const char *gameid);
+typedef GameList (*GameIDListFunc)();
+typedef DetectedGameList (*DetectFunc)(const FSList &fslist);
+
+
+class DynamicPlugin : public Plugin {
+protected:
+	typedef void (*VoidFunc)();
+	
+	Common::String _name;
+	Common::String _copyright;
+	GameIDQueryFunc _qf;
+	EngineFactory _ef;
+	DetectFunc _df;
+	GameList _games;
+
+	virtual VoidFunc findSymbol(const char *symbol) = 0;
+
+public:
+	DynamicPlugin() : _qf(0), _ef(0), _df(0), _games() {}
+
+	const char *getName() const					{ return _name.c_str(); }
+	const char *getCopyright() const			{ return _copyright.c_str(); }
+
+	PluginError createInstance(OSystem *syst, Engine **engine) const {
+		assert(_ef);
+		return (*_ef)(syst, engine);
+	}
+
+	GameList getSupportedGames() const { return _games; }
+
+	GameDescriptor findGame(const char *gameid) const {
+		assert(_qf);
+		return (*_qf)(gameid);
+	}
+
+	DetectedGameList detectGames(const FSList &fslist) const {
+		assert(_df);
+		return (*_df)(fslist);
+	}
+
+	virtual bool loadPlugin() {
+		// Query the plugin's name
+		NameFunc nameFunc = (NameFunc)findSymbol("PLUGIN_name");
+		if (!nameFunc) {
+			unloadPlugin();
+			return false;
+		}
+		_name = nameFunc();
+	
+		// Query the plugin's copyright
+		nameFunc = (NameFunc)findSymbol("PLUGIN_copyright");
+		if (!nameFunc) {
+			unloadPlugin();
+			return false;
+		}
+		_copyright = nameFunc();
+	
+		// Query the plugin for the game ids it supports
+		GameIDListFunc gameListFunc = (GameIDListFunc)findSymbol("PLUGIN_gameIDList");
+		if (!gameListFunc) {
+			unloadPlugin();
+			return false;
+		}
+		_games = gameListFunc();
+	
+		// Retrieve the gameid query function
+		_qf = (GameIDQueryFunc)findSymbol("PLUGIN_findGameID");
+		if (!_qf) {
+			unloadPlugin();
+			return false;
+		}
+	
+		// 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;
+		}
+	
+		return true;
+	}
+};
+
+#endif
diff --git a/backends/plugins/posix/posix-provider.cpp b/backends/plugins/posix/posix-provider.cpp
new file mode 100644
index 0000000000..bbc03938fe
--- /dev/null
+++ b/backends/plugins/posix/posix-provider.cpp
@@ -0,0 +1,178 @@
+/* ScummVM - Scumm Interpreter
+ * Copyright (C) 2001  Ludvig Strigeus
+ * Copyright (C) 2001-2006 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * $URL$
+ * $Id$
+ *
+ */
+
+#ifdef DYNAMIC_MODULES
+
+#include "backends/plugins/posix/posix-provider.h"
+#include "backends/plugins/dynamic-plugin.h"
+#include "common/fs.h"
+#include "common/util.h"
+
+#if defined(UNIX)
+
+#include <dlfcn.h>
+#define PLUGIN_DIRECTORY	"plugins/"
+
+#elif defined(__DC__)
+#include "dcloader.h"
+#define PLUGIN_DIRECTORY	"/"
+#define PLUGIN_PREFIX		""
+#define PLUGIN_SUFFIX		".PLG"
+
+#elif defined(_WIN32)
+#define PLUGIN_DIRECTORY	""
+#define PLUGIN_PREFIX		""
+#define PLUGIN_SUFFIX		".dll"
+#else
+#error No support for loading plugins on non-unix systems at this point!
+#endif
+
+
+
+class POSIXPlugin : public DynamicPlugin {
+protected:
+	void *_dlHandle;
+	Common::String _filename;
+
+	virtual VoidFunc 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());
+	#else
+	#if defined(_WIN32)
+		void *func = (void *)GetProcAddress((HMODULE)_dlHandle, symbol);
+		if (!func)
+			warning("Failed loading symbol '%s' from plugin '%s'", symbol, _filename.c_str());
+	#else
+	#error TODO
+	#endif
+	#endif
+	
+		// FIXME HACK: This is a HACK to circumvent a clash between the ISO C++
+		// standard and POSIX: ISO C++ disallows casting between function pointers
+		// and data pointers, but dlsym always returns a void pointer. For details,
+		// see e.g. <http://www.trilithium.com/johan/2004/12/problem-with-dlsym/>.
+		assert(sizeof(VoidFunc) == sizeof(func));
+		VoidFunc tmp;
+		memcpy(&tmp, &func, sizeof(VoidFunc));
+		return tmp;
+	}
+
+public:
+	POSIXPlugin(const Common::String &filename)
+		: _dlHandle(0), _filename(filename) {}
+
+	bool loadPlugin() {
+		assert(!_dlHandle);
+	#if defined(UNIX) || defined(__DC__)
+		_dlHandle = dlopen(_filename.c_str(), RTLD_LAZY);
+	
+		if (!_dlHandle) {
+			warning("Failed loading plugin '%s' (%s)", _filename.c_str(), dlerror());
+			return false;
+		}
+	#else
+	#if defined(_WIN32)
+		_dlHandle = LoadLibrary(_filename.c_str());
+	
+		if (!_dlHandle) {
+			warning("Failed loading plugin '%s'", _filename.c_str());
+			return false;
+		}
+	#else
+	#error TODO
+	#endif
+	#endif
+	
+		bool ret = DynamicPlugin::loadPlugin();
+		
+	#ifdef __DC__
+		if (ret)
+			dlforgetsyms(_dlHandle);
+	#endif
+
+		return ret;
+	}
+	void unloadPlugin() {
+		if (_dlHandle) {
+	#if defined(UNIX) || defined(__DC__)
+			if (dlclose(_dlHandle) != 0)
+				warning("Failed unloading plugin '%s' (%s)", _filename.c_str(), dlerror());
+	#elif defined(_WIN32)
+			if (!FreeLibrary((HMODULE)_dlHandle))
+				warning("Failed unloading plugin '%s'", _filename.c_str());
+	#else
+	#error TODO
+	#endif
+		}
+	}
+};
+
+
+POSIXPluginProvider::POSIXPluginProvider() {
+}
+
+POSIXPluginProvider::~POSIXPluginProvider() {
+}
+
+PluginList POSIXPluginProvider::getPlugins() {
+	PluginList pl;
+	
+	
+	// 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.
+
+	// Load all plugins.
+	// Scan for all plugins in this directory
+	FilesystemNode dir(PLUGIN_DIRECTORY);
+	FSList files;
+	if (!dir.listDir(files, FilesystemNode::kListFilesOnly)) {
+		error("Couldn't open plugin directory '%s'", PLUGIN_DIRECTORY);
+	}
+
+	for (FSList::const_iterator i = files.begin(); i != files.end(); ++i) {
+		Common::String name(i->name());
+		if (name.hasPrefix(PLUGIN_PREFIX) && name.hasSuffix(PLUGIN_SUFFIX)) {
+			pl.push_back(new POSIXPlugin(i->path()));
+		}
+	}
+	
+	
+	return pl;
+}
+
+
+#endif // DYNAMIC_MODULES
diff --git a/backends/plugins/posix/posix-provider.h b/backends/plugins/posix/posix-provider.h
new file mode 100644
index 0000000000..2c26751fb1
--- /dev/null
+++ b/backends/plugins/posix/posix-provider.h
@@ -0,0 +1,42 @@
+/* ScummVM - Scumm Interpreter
+ * Copyright (C) 2001  Ludvig Strigeus
+ * Copyright (C) 2001-2006 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * $URL$
+ * $Id$
+ *
+ */
+
+#ifndef BACKENDS_PLUGINS_POSIX_H
+#define BACKENDS_PLUGINS_POSIX_H
+
+#include "common/stdafx.h"
+#include "base/plugins.h"
+
+#ifdef DYNAMIC_MODULES
+
+class POSIXPluginProvider : public PluginProvider {
+public:
+	POSIXPluginProvider();
+	~POSIXPluginProvider();
+
+	virtual PluginList getPlugins();
+};
+
+#endif
+
+#endif