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//
// Nenya library - tools for developing networked games
// Copyright (C) 2002-2012 Three Rings Design, Inc., All Rights Reserved
// https://github.com/threerings/nenya
//
// This library is free software; you can redistribute it and/or modify it
// under the terms of the GNU Lesser General Public License as published
// by the Free Software Foundation; either version 2.1 of the License, or
// (at your option) any later version.
//
// This library 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
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
package com.threerings.util.unsafe;
import com.samskivert.util.RunAnywhere;
import static com.threerings.NenyaLog.log;
/**
* A native library for doing unsafe things. Don't use this library. If
* you must ignore that warning, then be sure you use it sparingly and
* only in very well considered cases.
*/
public class Unsafe
{
/**
* Enables or disables garbage collection. Warning: you will
* be fucked if you leave it disabled for too long. Do not do this
* unless you are dang sure about what you're doing and are prepared
* to test your code on every platform this side of Nantucket.
*
* Calls to this method do not nest. Regardless of how many times
* you disable GC, only one call is required to reenable it.
*/
public static void setGCEnabled (boolean enabled)
{
// we don't support nesting, NOOP if the state doesn't change
if (isLoaded()) {
if (!_initialized && !(_initialized = init())) {
// no joy initializing things
return;
}
if (_initialized && enabled != _gcEnabled) {
_gcEnabled = enabled;
if (_gcEnabled) {
enableGC();
} else {
disableGC();
}
}
}
}
/**
* Causes the current thread to block for the specified number of
* milliseconds. This exists primarily to work around the fact that on
* Linux, {@link Thread#sleep(long)} is only accurate to around 12ms which
* is wholly unacceptable.
*/
public static void sleep (int millis)
{
if (RunAnywhere.isLinux() && isLoaded()) {
nativeSleep(millis);
} else {
try {
Thread.sleep(millis);
} catch (InterruptedException ie) {
log.info("Thread.sleep(" + millis + ") interrupted.");
}
}
}
/**
* Sets the process' uid to the specified value.
*
* @return true if the uid was changed, false if we were unable to do so.
*/
public static boolean setuid (int uid)
{
if (!RunAnywhere.isWindows() && isLoaded()) {
return nativeSetuid(uid);
}
return false;
}
/**
* Sets the process' gid to the specified value.
*
* @return true if the gid was changed, false if we were unable to do so.
*/
public static boolean setgid (int gid)
{
if (!RunAnywhere.isWindows() && isLoaded()) {
return nativeSetgid(gid);
}
return false;
}
/**
* Sets the process' effective uid to the specified value.
*
* @return true if the euid was changed, false if we were unable to do so.
*/
public static boolean seteuid (int uid)
{
if (!RunAnywhere.isWindows() && isLoaded()) {
return nativeSeteuid(uid);
}
return false;
}
/**
* Sets the process' effective gid to the specified value.
*
* @return true if the egid was changed, false if we were unable to do so.
*/
public static boolean setegid (int gid)
{
if (!RunAnywhere.isWindows() && isLoaded()) {
return nativeSetegid(gid);
}
return false;
}
/**
* Returns true if the native library was successfully loaded, and if this is the first time
* it's been checked and it failed, reports the failure.
*/
protected static boolean isLoaded ()
{
if (_loadError != null) {
log.warning("Unable to load 'unsafe' library", "e", _loadError);
_loadError = null;
}
return _loaded;
}
/**
* Reenable garbage collection after a call to {@link #disableGC}.
*/
protected static native void enableGC ();
/**
* Disables garbage collection.
*/
protected static native void disableGC ();
/**
* Sleeps the current thread for the specified number of milliseconds.
*/
protected static native void nativeSleep (int millis);
/**
* Calls through to the native OS system call to change our uid.
*/
protected static native boolean nativeSetuid (int uid);
/**
* Calls through to the native OS system call to change our gid.
*/
protected static native boolean nativeSetgid (int gid);
/**
* Calls through to the native OS system call to change our euid.
*/
protected static native boolean nativeSeteuid (int uid);
/**
* Calls through to the native OS system call to change our egid.
*/
protected static native boolean nativeSetegid (int gid);
/**
* Called to initialize our library.
*/
protected static native boolean init ();
/** The current state of GC enablement. */
protected static boolean _gcEnabled = true;
/** Whether or not we were able to load our library. */
protected static boolean _loaded;
/** Whether or not we were able to initialize our library (i.e. get access to jvmpi) */
protected static boolean _initialized;
/**
* The error that occurred when loading the native library, or null if none occurred or it was
* already reported.
*/
protected static Throwable _loadError;
static {
try {
System.loadLibrary("unsafe");
_loaded = true;
} catch (Throwable t) {
_loadError = t;
}
}
}