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/*
* Some portions of this file have been modified by Robert Hanson hansonr.at.stolaf.edu 2012-2017
* for use in SwingJS via transpilation into JavaScript using Java2Script.
* Copyright 1995-2007 Sun Microsystems, Inc. All Rights Reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Sun designates this
* particular file as subject to the "Classpath" exception as provided
* by Sun in the LICENSE file that accompanied this code.
*
* This code 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
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
* CA 95054 USA or visit www.sun.com if you need additional information or
* have any questions.
*/
package jsjava.io;
import jsjava.util.concurrent.atomic.AtomicInteger;
/**
* Instances of the file descriptor class serve as an opaque handle
* to the underlying machine-specific structure representing an open
* file, an open socket, or another source or sink of bytes. The
* main practical use for a file descriptor is to create a
* <code>FileInputStream</code> or <code>FileOutputStream</code> to
* contain it.
* <p>
* Applications should not create their own file descriptors.
*
* @author Pavani Diwanji
* @see java.io.FileInputStream
* @see java.io.FileOutputStream
* @since JDK1.0
*/
public final class FileDescriptor {
private int fd;
/**
* A counter for tracking the FIS/FOS/RAF instances that
* use this FileDescriptor. The FIS/FOS.finalize() will not release
* the FileDescriptor if it is still under user by a stream.
*/
private AtomicInteger useCount;
/**
* Constructs an (invalid) FileDescriptor
* object.
*/
public /**/ FileDescriptor() {
fd = -1;
useCount = new AtomicInteger();
}
private /* */ FileDescriptor(int fd) {
this.fd = fd;
useCount = new AtomicInteger();
}
/**
* A handle to the standard input stream. Usually, this file
* descriptor is not used directly, but rather via the input stream
* known as <code>System.in</code>.
*
* @see java.lang.System#in
*/
public static final FileDescriptor in = new FileDescriptor(0);
/**
* A handle to the standard output stream. Usually, this file
* descriptor is not used directly, but rather via the output stream
* known as <code>System.out</code>.
* @see java.lang.System#out
*/
public static final FileDescriptor out = new FileDescriptor(1);
/**
* A handle to the standard error stream. Usually, this file
* descriptor is not used directly, but rather via the output stream
* known as <code>System.err</code>.
*
* @see java.lang.System#err
*/
public static final FileDescriptor err = new FileDescriptor(2);
/**
* Tests if this file descriptor object is valid.
*
* @return <code>true</code> if the file descriptor object represents a
* valid, open file, socket, or other active I/O connection;
* <code>false</code> otherwise.
*/
public boolean valid() {
return fd != -1;
}
// /**
// * Force all system buffers to synchronize with the underlying
// * device. This method returns after all modified data and
// * attributes of this FileDescriptor have been written to the
// * relevant device(s). In particular, if this FileDescriptor
// * refers to a physical storage medium, such as a file in a file
// * system, sync will not return until all in-memory modified copies
// * of buffers associated with this FileDescriptor have been
// * written to the physical medium.
// *
// * sync is meant to be used by code that requires physical
// * storage (such as a file) to be in a known state For
// * example, a class that provided a simple transaction facility
// * might use sync to ensure that all changes to a file caused
// * by a given transaction were recorded on a storage medium.
// *
// * sync only affects buffers downstream of this FileDescriptor. If
// * any in-memory buffering is being done by the application (for
// * example, by a BufferedOutputStream object), those buffers must
// * be flushed into the FileDescriptor (for example, by invoking
// * OutputStream.flush) before that data will be affected by sync.
// *
// * @exception SyncFailedException
// * Thrown when the buffers cannot be flushed,
// * or because the system cannot guarantee that all the
// * buffers have been synchronized with physical media.
// * @since JDK1.1
// */
// public native void sync() throws SyncFailedException;
//
// /* This routine initializes JNI field offsets for the class */
// private static native void initIDs();
//
// static {
// initIDs();
// }
//
// // Set up JavaIOFileDescriptorAccess in SharedSecrets
// static {
// sun.misc.SharedSecrets.setJavaIOFileDescriptorAccess(
// new sun.misc.JavaIOFileDescriptorAccess() {
// public void set(FileDescriptor obj, int fd) {
// obj.fd = fd;
// }
//
// public int get(FileDescriptor obj) {
// return obj.fd;
// }
// }
// );
// }
// pacakge private methods used by FIS,FOS and RAF
int incrementAndGetUseCount() {
return useCount.incrementAndGet();
}
int decrementAndGetUseCount() {
return useCount.decrementAndGet();
}
}