FsInode_PGET.java

/*
 * This library is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Library General Public License as
 * published by the Free Software Foundation; either version 2 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 Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public
 * License along with this program (see the file COPYING.LIB for more
 * details); if not, write to the Free Software Foundation, Inc.,
 * 675 Mass Ave, Cambridge, MA 02139, USA.
 */
package org.dcache.chimera;

import org.dcache.chimera.posix.Stat;

/**
 * This class has been generalized as a superclass.  The specific operation
 * should be encoded as a concrete {@link FsInodeType}.
 *
 * @author arossi
 */
public abstract class FsInode_PGET extends FsInode {
    protected static final String NEWLINE = "\n\r";

    protected FsInode_PGET(FileSystemProvider fs, long ino, FsInodeType type) {
        super(fs, ino, type);
    }

    @Override
    public int read(long pos, byte[] data, int offset, int len) {
        String value;

        try {
            value = value();
        } catch (ChimeraFsException e) {
            value = "";
        }

        byte[] b = value.getBytes();

        if (pos > b.length) {
            return 0;
        }

        int copyLen = Math.min(len, b.length - (int) pos);
        System.arraycopy(b, (int) pos, data, 0, copyLen);

        return copyLen;
    }

    @Override
    public Stat stat() throws ChimeraFsException {
        Stat ret = super.stat();
        ret.setMode((ret.getMode() & 0000777) | UnixPermission.S_IFREG);
        ret.setSize(value().length());
        // invalidate NFS cache
        ret.setMTime(System.currentTimeMillis());
        return ret;
    }

    @Override
    public int write(long pos, byte[] data, int offset, int len) {
        return -1;
    }

    /*
     * Concrete class should always do work here.  Implementation of specific
     * operation will determine whether the node needs to be stateful or not.
     * Should not return <code>null</code>.
     */
    protected abstract String value() throws ChimeraFsException;
}