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jeremybenn |
/* FileDescriptor.java -- Opaque file handle class
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Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003, 2004
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Free Software Foundation, Inc.
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This file is part of GNU Classpath.
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GNU Classpath is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GNU Classpath is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU Classpath; see the file COPYING. If not, write to the
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Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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02110-1301 USA.
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Linking this library statically or dynamically with other modules is
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making a combined work based on this library. Thus, the terms and
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conditions of the GNU General Public License cover the whole
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combination.
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As a special exception, the copyright holders of this library give you
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permission to link this library with independent modules to produce an
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executable, regardless of the license terms of these independent
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modules, and to copy and distribute the resulting executable under
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terms of your choice, provided that you also meet, for each linked
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independent module, the terms and conditions of the license of that
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module. An independent module is a module which is not derived from
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or based on this library. If you modify this library, you may extend
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this exception to your version of the library, but you are not
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obligated to do so. If you do not wish to do so, delete this
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exception statement from your version. */
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package java.io;
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import gnu.java.nio.FileChannelImpl;
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import java.nio.channels.ByteChannel;
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import java.nio.channels.FileChannel;
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/**
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* This class represents an opaque file handle as a Java class. It should
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* be used only to pass to other methods that expect an object of this
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* type. No system specific information can be obtained from this object.
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*
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* @author Aaron M. Renn (arenn@urbanophile.com)
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* @author Tom Tromey (tromey@cygnus.com)
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* @date September 24, 1998
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*/
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public final class FileDescriptor
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{
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/**
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* A <code>FileDescriptor</code> representing the system standard input
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* stream. This will usually be accessed through the
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* <code>System.in</code>variable.
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*/
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public static final FileDescriptor in
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= new FileDescriptor (FileChannelImpl.in);
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/**
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* A <code>FileDescriptor</code> representing the system standard output
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* stream. This will usually be accessed through the
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* <code>System.out</code>variable.
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*/
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public static final FileDescriptor out
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= new FileDescriptor (FileChannelImpl.out);
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/**
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* A <code>FileDescriptor</code> representing the system standard error
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* stream. This will usually be accessed through the
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* <code>System.err</code>variable.
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*/
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public static final FileDescriptor err
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= new FileDescriptor (FileChannelImpl.err);
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final ByteChannel channel;
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/**
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* This method is used to initialize an invalid FileDescriptor object.
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*/
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public FileDescriptor()
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{
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channel = null;
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}
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/**
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* This method is used to initialize a FileDescriptor object.
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*/
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FileDescriptor(ByteChannel channel)
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{
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this.channel = channel;
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}
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/**
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* This method forces all data that has not yet been physically written to
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* the underlying storage medium associated with this
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* <code>FileDescriptor</code>
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* to be written out. This method will not return until all data has
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* been fully written to the underlying device. If the device does not
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* support this functionality or if an error occurs, then an exception
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* will be thrown.
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*/
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public void sync () throws SyncFailedException
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{
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if (channel instanceof FileChannel)
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{
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try
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{
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((FileChannel) channel).force(true);
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}
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catch (IOException ex)
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{
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if (ex instanceof SyncFailedException)
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throw (SyncFailedException) ex;
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else
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throw new SyncFailedException(ex.toString());
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}
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}
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}
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/**
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* This methods tests whether or not this object represents a valid open
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* native file handle.
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*
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* @return <code>true</code> if this object represents a valid
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* native file handle, <code>false</code> otherwise
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*/
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public boolean valid ()
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{
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ByteChannel c = channel;
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return (c != null) && (c.isOpen());
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}
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}
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