src/java.base/share/classes/sun/nio/ch/FileDispatcher.java

/*
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 * 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.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle 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.
 *
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package sun.nio.ch;

import java.io.FileDescriptor;
import java.io.IOException;
import java.nio.channels.SelectableChannel;

abstract class FileDispatcher extends NativeDispatcher {

    public static final int NO_LOCK = -1;       // Failed to lock
    public static final int LOCKED = 0;         // Obtained requested lock
    public static final int RET_EX_LOCK = 1;    // Obtained exclusive lock
    public static final int INTERRUPTED = 2;    // Request interrupted

    /**
     * Sets or reports this file's position
     * If offset is -1, the current position is returned
     * otherwise the position is set to offset.
     */
    abstract long seek(FileDescriptor fd, long offset) throws IOException;

    abstract int force(FileDescriptor fd, boolean metaData) throws IOException;

    abstract int truncate(FileDescriptor fd, long size) throws IOException;

    abstract long size(FileDescriptor fd) throws IOException;

    abstract int lock(FileDescriptor fd, boolean blocking, long pos, long size,
                       boolean shared) throws IOException;

    abstract void release(FileDescriptor fd, long pos, long size)
        throws IOException;

    /**
     * Returns a dup of fd if a file descriptor is required for
     * memory-mapping operations, otherwise returns an invalid
     * FileDescriptor (meaning a newly allocated FileDescriptor)
     */
    abstract FileDescriptor duplicateForMapping(FileDescriptor fd)
        throws IOException;

    abstract boolean canTransferToDirectly(SelectableChannel sc);

    abstract boolean transferToDirectlyNeedsPositionLock();

    abstract int setDirectIO(FileDescriptor fd, String path);
}