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/*
* Copyright (C) 2003-2009 JNode.org
* 2009,2010 Matthias Treydte <mt@waldheinz.de>
*
* 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.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
package de.waldheinz.fs;
import java.io.IOException;
import java.nio.ByteBuffer;
/**
* A FsFile is a representation of a single block of bytes on a filesystem. It
* is comparable to an inode in Unix.
*
* An FsFile does not have any knowledge of who is using this file. It is also
* possible that the system uses a single FsFile instance to create two
* inputstream's for two different principals.
*
* @author Ewout Prangsma <epr at jnode.org>
*/
public interface FsFile extends FsObject {
/**
* Gets the length (in bytes) of this file.
*
* @return the file size
*/
public long getLength();
/**
* Sets the length of this file.
*
* @param length the new length of this file
* @throws IOException on error updating the file size
*/
public void setLength(long length) throws IOException;
/**
* Reads from this file into the specified {@code ByteBuffer}. The
* first byte read will be put into the buffer at it's
* {@link ByteBuffer#position() position}, and the number of bytes read
* will equal the buffer's {@link ByteBuffer#remaining() remaining} bytes.
*
* @param offset the offset into the file where to start reading
* @param dest the destination buffer where to put the bytes that were read
* @throws IOException on read error
*/
public void read(long offset, ByteBuffer dest) throws IOException;
/**
* Writes to this file taking the data to write from the specified
* {@code ByteBuffer}. This method will read the buffer's
* {@link ByteBuffer#remaining() remaining} bytes starting at it's
* {@link ByteBuffer#position() position}.
*
* @param offset the offset into the file where the first byte will be
* written
* @param src the source buffer to read the data from
* @throws ReadOnlyException if the file is read-only
* @throws IOException on write error
*/
public void write(long offset, ByteBuffer src)
throws ReadOnlyException, IOException;
/**
* Flush any possibly cached data to the disk.
*
* @throws IOException on error flushing
*/
public void flush() throws IOException;
}
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