/*

 * Copyright (c) 1997, 1999, Oracle and/or its affiliates. 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.  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.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package sun.rmi.log;

import java.io.*;

public

class LogInputStream extends InputStream {

    private InputStream in;

    private int length;

    /**

     * Creates a log input file with the specified system dependent

     * file descriptor.

     * @param fd the system dependent file descriptor

     * @param length the total number of bytes allowed to be read

     * @exception IOException If an I/O error has occurred.

     */

    public LogInputStream(InputStream in, int length) throws IOException {

        this.in = in;

        this.length = length;

    }

    /**

     * Reads a byte of data. This method will block if no input is

     * available.

     * @return  the byte read, or -1 if the end of the log or end of the

     *          stream is reached.

     * @exception IOException If an I/O error has occurred.

     */

    public int read() throws IOException {

        if (length == 0)

            return -1;

        int c = in.read();

        length = (c != -1) ? length - 1 : 0;

        return c;

    }

    /**

     * Reads data into an array of bytes.

     * This method blocks until some input is available.

     * @param b the buffer into which the data is read

     * @return  the actual number of bytes read, or -1 if the end of the log

     *          or end of the stream is reached.

     * @exception IOException If an I/O error has occurred.

     */

    public int read(byte b[]) throws IOException {

        return read(b, 0, b.length);

    }

    /**

     * Reads data into an array of bytes.

     * This method blocks until some input is available.

     * @param b the buffer into which the data is read

     * @param off the start offset of the data

     * @param len the maximum number of bytes read

     * @return  the actual number of bytes read, or -1 if the end of the log or

     *          end of the stream is reached.

     * @exception IOException If an I/O error has occurred.

     */

    public int read(byte b[], int off, int len) throws IOException {

        if (length == 0)

            return -1;

        len = (length < len) ? length : len;

        int n = in.read(b, off, len);

        length = (n != -1) ? length - n : 0;

        return n;

    }

    /**

     * Skips n bytes of input.

     * @param n the number of bytes to be skipped

     * @return  the actual number of bytes skipped.

     * @exception IOException If an I/O error has occurred.

     */

    public long skip(long n) throws IOException {

        if (n > Integer.MAX_VALUE)

            throw new IOException("Too many bytes to skip - " + n);

        if (length == 0)

            return 0;

        n = (length < n) ? length : n;

        n = in.skip(n);

        length -= n;

        return n;

    }

    /**

     * Returns the number of bytes that can be read without blocking.

     * @return  the number of available bytes, which is initially

     *          equal to the file size.

     */

    public int available() throws IOException {

        int avail = in.available();

        return (length < avail) ? length : avail;

    }

    /**

     * Closes the input stream.  No further input can be read.

     * the stream.

     */

    public void close() {

        length = 0;

    }

    /**

     * Closes the stream when garbage is collected.

     */

    protected void finalize() throws IOException {

        close();

    }

}