BEGIN LICENSE BLOCK *****
Version: EPL 2.0/GPL 2.0/LGPL 2.1
The contents of this file are subject to the Eclipse Public
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.eclipse.org/legal/epl-v20.html
Software distributed under the License is distributed on an "AS
IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
implied. See the License for the specific language governing
rights and limitations under the License.
Copyright (C) 2007 Ola Bini 
Alternatively, the contents of this file may be used under the terms of
either of the GNU General Public License Version 2 or later (the "GPL"),
or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
in which case the provisions of the GPL or the LGPL are applicable instead
of those above. If you wish to allow use of your version of this file only
under the terms of either the GPL or the LGPL, and not to allow others to
use your version of this file under the terms of the EPL, indicate your
decision by deleting the provisions above and replace them with the notice
and other provisions required by the GPL or the LGPL. If you do not delete
the provisions above, a recipient may use your version of this file under
the terms of any one of the EPL, the GPL or the LGPL.
END LICENSE BLOCK /***** BEGIN LICENSE BLOCK *****
 * Version: EPL 2.0/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Eclipse Public
 * 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.eclipse.org/legal/epl-v20.html
 *
 * Software distributed under the License is distributed on an "AS
 * IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
 * implied. See the License for the specific language governing
 * rights and limitations under the License.
 *
 * Copyright (C) 2007 Ola Bini <ola.bini@gmail.com>
 * 
 * Alternatively, the contents of this file may be used under the terms of
 * either of the GNU General Public License Version 2 or later (the "GPL"),
 * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
 * of those above. If you wish to allow use of your version of this file only
 * under the terms of either the GPL or the LGPL, and not to allow others to
 * use your version of this file under the terms of the EPL, indicate your
 * decision by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL or the LGPL. If you do not delete
 * the provisions above, a recipient may use your version of this file under
 * the terms of any one of the EPL, the GPL or the LGPL.
 ***** END LICENSE BLOCK *****/

package org.jruby.util;

import org.jruby.Ruby;
import org.jruby.RubyArray;
import org.jruby.RubyFixnum;
import org.jruby.RubyModule;
import org.jruby.RubyProc;

import org.jruby.exceptions.MainExitException;
import org.jruby.exceptions.RaiseException;
import org.jruby.runtime.Signature;
import org.jruby.runtime.builtin.IRubyObject;
import org.jruby.runtime.CallBlock;
import org.jruby.runtime.Block;
import org.jruby.runtime.BlockCallback;
import org.jruby.runtime.ThreadContext;

import sun.misc.Signal;
import sun.misc.SignalHandler;

import java.util.HashMap;
import java.util.Map;

Author:
Ola Bini/**
 * @author <a href="mailto:ola.bini@gmail.com">Ola Bini</a>
 */
public class SunSignalFacade implements SignalFacade {
    
Remembers the original signal handlers before JRuby started messing around with them, to emulate Signal.trap(...,"DEFAULT") that's supposed to restore the platform default handler. /**
     * Remembers the original signal handlers before JRuby started messing around with them,
     * to emulate {@code Signal.trap(...,"DEFAULT")} that's supposed to restore the platform
     * default handler.
     */
    private final Map<Signal, SignalHandler> original = new HashMap<>(4);
    private final Map<String, SignalHandler> fakeOriginal = new HashMap<>(4);
    
    private final static class JRubySignalHandler implements SignalHandler {
        private final Ruby runtime;
        private final IRubyObject block;
        private final String signal;
        private final BlockCallback blockCallback;

        public JRubySignalHandler(Ruby runtime, IRubyObject block, String signal) {
            this(runtime, block, null, signal);
        }

        public JRubySignalHandler(Ruby runtime, BlockCallback callback, String signal) {
            this(runtime, null, callback, signal);
        }

        private JRubySignalHandler(Ruby runtime, IRubyObject block, BlockCallback callback, String signal) {
            this.runtime = runtime;
            this.block = block;
            this.blockCallback = callback;
            this.signal = signal;
        }

        public void handle(Signal signal) {
            ThreadContext context = runtime.getCurrentContext();
            IRubyObject oldExc = runtime.getGlobalVariables().get("$!"); // Save $!
            try {
                RubyFixnum signum = runtime.newFixnum(signal.getNumber());
                if (block != null) {
                    block.callMethod(context, "call", signum);
                } else {
                    blockCallback.call(context, signum, Block.NULL_BLOCK);
                }
            } catch(RaiseException e) {
                try {
                    runtime.getThread().callMethod(context, "main")
                        .callMethod(context, "raise", e.getException());
                } catch(Exception ignored) {}
                runtime.getGlobalVariables().set("$!", oldExc); // Restore $!
            } catch (MainExitException mee) {
                runtime.getThreadService().getMainThread().kill();
            } finally {
                Signal.handle(new Signal(this.signal), this);
            }
        }
    }

    public IRubyObject trap(final IRubyObject recv, IRubyObject blk, IRubyObject sig) {
        return trap(recv.getRuntime(), new JRubySignalHandler(recv.getRuntime(), blk, sig.toString()));
    }
        
    public IRubyObject trap(final Ruby runtime, BlockCallback blk, String sig) {
        return trap(runtime, new JRubySignalHandler(runtime, blk, sig));
    }

    private IRubyObject trap(final Ruby runtime, final JRubySignalHandler handler) {
        return trap(runtime,handler.signal, handler);
    }

    public IRubyObject restorePlatformDefault(IRubyObject recv, IRubyObject sig) {
        SignalHandler handler;
        Ruby runtime = recv.getRuntime();
        try {
            synchronized (original) {
                handler = original.get(new Signal(sig.toString()));
            }
        } catch (IllegalArgumentException e) {
            handler = null;
        }
        if (handler != null) {
            return trap(runtime, sig.toString(), handler);
        } else {
            // JRuby hasn't touched this signal handler, so it should be the platform default already
            // We still need to return the handler if one exists, though.

            synchronized (fakeOriginal) {
                handler = fakeOriginal.remove(sig.toString());
            }
            return getSignalResult(runtime, handler, true);
        }
    }

    public IRubyObject restoreOSDefault(IRubyObject recv, IRubyObject sig) {
        return trap(recv.getRuntime(), sig.toString(), SignalHandler.SIG_DFL);
    }

    public IRubyObject ignore(IRubyObject recv, IRubyObject sig) {
        return trap(recv.getRuntime(), sig.toString(), SignalHandler.SIG_IGN);
    }

    private IRubyObject trap(final Ruby runtime, final String signalName, final SignalHandler handler) {
        boolean handled;

        SignalHandler oldHandler;
        Signal signal;
        try {
            signal = new Signal(signalName);
            oldHandler = Signal.handle(signal, handler);
            synchronized (original) {
                if (!original.containsKey(signal))
                    original.put(signal, oldHandler);
            }
            handled = true;
        } catch (IllegalArgumentException e) {
            signal = null;
            oldHandler = fakeOriginal.get(signalName);
            synchronized (fakeOriginal) {
                fakeOriginal.put(signalName, handler);
            }
            // EXIT is a special pseudo-signal. We want to mark this signal as handled if so.
            handled = signalName.equals("EXIT");
        }

        return getSignalResult(runtime, oldHandler, handled);
    }

    private static IRubyObject getSignalResult(final Ruby runtime, final SignalHandler oldHandler, boolean handled) {
        IRubyObject[] retVals = new IRubyObject[] { null, runtime.newBoolean(handled) };
        BlockCallback callback = null;

        if (oldHandler instanceof JRubySignalHandler) {
            JRubySignalHandler jsHandler = (JRubySignalHandler) oldHandler;
            if (jsHandler.blockCallback != null) {
                callback = jsHandler.blockCallback;
            } else {
                retVals[0] = jsHandler.block;
                return RubyArray.newArrayMayCopy(runtime, retVals);
            }
        }

        if (callback == null) {
            if (oldHandler == SignalHandler.SIG_DFL) {
                retVals[0] = runtime.newString("SYSTEM_DEFAULT");
            } else if (oldHandler == SignalHandler.SIG_IGN) {
                retVals[0] = runtime.newString("IGNORE");
            } else {
                retVals[0] = runtime.newString("DEFAULT");
            }
        } else {
            Block block = CallBlock.newCallClosure(runtime.getCurrentContext(),
                    runtime.getModule("Signal"), Signature.NO_ARGUMENTS, callback);
            retVals[0] = RubyProc.newProc(runtime, block, block.type);
        }

        return RubyArray.newArrayMayCopy(runtime, retVals);
    }

}// SunSignalFacade