a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster/*
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster * Copyright (c) 1998, 2007, Oracle and/or its affiliates. All rights reserved.
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster *
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster * This code is free software; you can redistribute it and/or modify it
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster * under the terms of the GNU General Public License version 2 only, as
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster * published by the Free Software Foundation. Oracle designates this
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster * particular file as subject to the "Classpath" exception as provided
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster * by Oracle in the LICENSE file that accompanied this code.
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster *
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster * This code is distributed in the hope that it will be useful, but WITHOUT
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster * version 2 for more details (a copy is included in the LICENSE file that
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster * accompanied this code).
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster *
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster * You should have received a copy of the GNU General Public License version
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster * 2 along with this work; if not, write to the Free Software Foundation,
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster *
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster * or visit www.oracle.com if you need additional information or have any
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster * questions.
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster */
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Fosterpackage sun.misc;
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Fosterimport java.util.Hashtable;
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster/**
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster * This class provides ANSI/ISO C signal support. A Java program can register
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster * signal handlers for the current process. There are two restrictions:
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster * <ul>
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster * <li>
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster * Java code cannot register a handler for signals that are already used
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster * by the Java VM implementation. The <code>Signal.handle</code>
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster * function raises an <code>IllegalArgumentException</code> if such an attempt
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster * is made.
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster * <li>
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster * When <code>Signal.handle</code> is called, the VM internally registers a
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster * special C signal handler. There is no way to force the Java signal handler
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster * to run synchronously before the C signal handler returns. Instead, when the
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster * VM receives a signal, the special C signal handler creates a new thread
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster * (at priority <code>Thread.MAX_PRIORITY</code>) to
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster * run the registered Java signal handler. The C signal handler immediately
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster * returns. Note that because the Java signal handler runs in a newly created
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster * thread, it may not actually be executed until some time after the C signal
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster * handler returns.
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster * </ul>
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster * <p>
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster * Signal objects are created based on their names. For example:
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster * <blockquote><pre>
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster * new Signal("INT");
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster * </blockquote></pre>
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster * constructs a signal object corresponding to <code>SIGINT</code>, which is
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster * typically produced when the user presses <code>Ctrl-C</code> at the command line.
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster * The <code>Signal</code> constructor throws <code>IllegalArgumentException</code>
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster * when it is passed an unknown signal.
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster * <p>
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster * This is an example of how Java code handles <code>SIGINT</code>:
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster * <blockquote><pre>
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster * SignalHandler handler = new SignalHandler () {
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster * public void handle(Signal sig) {
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster * ... // handle SIGINT
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster * }
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster * };
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster * Signal.handle(new Signal("INT"), handler);
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster * </blockquote></pre>
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster *
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster * @author Sheng Liang
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster * @author Bill Shannon
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster * @see sun.misc.SignalHandler
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster * @since 1.2
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster */
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Fosterpublic final class Signal {
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster private static Hashtable handlers = new Hashtable(4);
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster private static Hashtable signals = new Hashtable(4);
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster private int number;
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster private String name;
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster /* Returns the signal number */
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster public int getNumber() {
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster return number;
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster }
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster /**
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster * Returns the signal name.
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster *
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster * @return the name of the signal.
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster * @see sun.misc.Signal#Signal(String name)
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster */
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster public String getName() {
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster return name;
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster }
a688bcbb4bcff5398fdd29b86f83450257dc0df4Allan Foster
/**
* Compares the equality of two <code>Signal</code> objects.
*
* @param other the object to compare with.
* @return whether two <code>Signal</code> objects are equal.
*/
public boolean equals(Object other) {
if (this == other) {
return true;
}
if (other == null || !(other instanceof Signal)) {
return false;
}
Signal other1 = (Signal)other;
return name.equals(other1.name) && (number == other1.number);
}
/**
* Returns a hashcode for this Signal.
*
* @return a hash code value for this object.
*/
public int hashCode() {
return number;
}
/**
* Returns a string representation of this signal. For example, "SIGINT"
* for an object constructed using <code>new Signal ("INT")</code>.
*
* @return a string representation of the signal
*/
public String toString() {
return "SIG" + name;
}
/**
* Constructs a signal from its name.
*
* @param name the name of the signal.
* @exception IllegalArgumentException unknown signal
* @see sun.misc.Signal#getName()
*/
public Signal(String name) {
number = findSignal(name);
this.name = name;
if (number < 0) {
throw new IllegalArgumentException("Unknown signal: " + name);
}
}
/**
* Registers a signal handler.
*
* @param sig a signal
* @param handler the handler to be registered with the given signal.
* @result the old handler
* @exception IllegalArgumentException the signal is in use by the VM
* @see sun.misc.Signal#raise(Signal sig)
* @see sun.misc.SignalHandler
* @see sun.misc.SignalHandler#SIG_DFL
* @see sun.misc.SignalHandler#SIG_IGN
*/
public static synchronized SignalHandler handle(Signal sig,
SignalHandler handler)
throws IllegalArgumentException {
long newH = (handler instanceof NativeSignalHandler) ?
((NativeSignalHandler)handler).getHandler() : 2;
long oldH = handle0(sig.number, newH);
if (oldH == -1) {
throw new IllegalArgumentException
("Signal already used by VM or OS: " + sig);
}
signals.put(new Integer(sig.number), sig);
synchronized (handlers) {
SignalHandler oldHandler = (SignalHandler)handlers.get(sig);
handlers.remove(sig);
if (newH == 2) {
handlers.put(sig, handler);
}
if (oldH == 0) {
return SignalHandler.SIG_DFL;
} else if (oldH == 1) {
return SignalHandler.SIG_IGN;
} else if (oldH == 2) {
return oldHandler;
} else {
return new NativeSignalHandler(oldH);
}
}
}
/**
* Raises a signal in the current process.
*
* @param sig a signal
* @see sun.misc.Signal#handle(Signal sig, SignalHandler handler)
*/
public static void raise(Signal sig) throws IllegalArgumentException {
if (handlers.get(sig) == null) {
throw new IllegalArgumentException("Unhandled signal: " + sig);
}
raise0(sig.number);
}
/* Called by the VM to execute Java signal handlers. */
private static void dispatch(final int number) {
final Signal sig = (Signal)signals.get(new Integer(number));
final SignalHandler handler = (SignalHandler)handlers.get(sig);
Runnable runnable = new Runnable () {
public void run() {
// Don't bother to reset the priority. Signal handler will
// run at maximum priority inherited from the VM signal
// dispatch thread.
// Thread.currentThread().setPriority(Thread.NORM_PRIORITY);
handler.handle(sig);
}
};
if (handler != null) {
new Thread(runnable, sig + " handler").start();
}
}
/* Find the signal number, given a name. Returns -1 for unknown signals. */
private static native int findSignal(String sigName);
/* Registers a native signal handler, and returns the old handler.
* Handler values:
* 0 default handler
* 1 ignore the signal
* 2 call back to Signal.dispatch
* other arbitrary native signal handlers
*/
private static native long handle0(int sig, long nativeH);
/* Raise a given signal number */
private static native void raise0(int sig);
}