/*

 * Copyright (c) 1995, 2017, 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 java.net;

import java.io.FileDescriptor;

import java.io.FileInputStream;

import java.io.IOException;

import java.nio.channels.FileChannel;

import sun.net.ConnectionResetException;

/**

 * This stream extends FileInputStream to implement a

 * SocketInputStream. Note that this class should <b>NOT</b> be

 * public.

 *

 * @author      Jonathan Payne

 * @author      Arthur van Hoff

 */

class SocketInputStream extends FileInputStream

{

    static {

        init();

    }

    private boolean eof;

    private AbstractPlainSocketImpl impl = null;

    private byte temp[];

    private Socket socket = null;

    /**

     * Creates a new SocketInputStream. Can only be called

     * by a Socket. This method needs to hang on to the owner Socket so

     * that the fd will not be closed.

     * @param impl the implemented socket input stream

     */

    SocketInputStream(AbstractPlainSocketImpl impl) throws IOException {

        super(impl.getFileDescriptor());

        this.impl = impl;

        socket = impl.getSocket();

    }

    /**

     * Returns the unique {@link java.nio.channels.FileChannel FileChannel}

     * object associated with this file input stream.</p>

     *

     * The {@code getChannel} method of {@code SocketInputStream}

     * returns {@code null} since it is a socket based stream.</p>

     *

     * @return  the file channel associated with this file input stream

     *

     * @since 1.4

     * @spec JSR-51

     */

    public final FileChannel getChannel() {

        return null;

    }

    /**

     * Reads into an array of bytes at the specified offset using

     * the received socket primitive.

     * @param fd the FileDescriptor

     * @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

     * @param timeout the read timeout in ms

     * @return the actual number of bytes read, -1 is

     *          returned when the end of the stream is reached.

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

     */

    private native int socketRead0(FileDescriptor fd,

                                   byte b[], int off, int len,

                                   int timeout)

        throws IOException;

    // wrap native call to allow instrumentation

    /**

     * Reads into an array of bytes at the specified offset using

     * the received socket primitive.

     * @param fd the FileDescriptor

     * @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

     * @param timeout the read timeout in ms

     * @return the actual number of bytes read, -1 is

     *          returned when the end of the stream is reached.

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

     */

    private int socketRead(FileDescriptor fd,

                           byte b[], int off, int len,

                           int timeout)

        throws IOException {

        return socketRead0(fd, b, off, len, timeout);

    }

    /**

     * Reads into a byte array data from the socket.

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

     * @return the actual number of bytes read, -1 is

     *          returned when the 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 into a byte array <i>b</i> at offset <i>off</i>,

     * <i>length</i> bytes of data.

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

     * @param off the start offset of the data

     * @param length the maximum number of bytes read

     * @return the actual number of bytes read, -1 is

     *          returned when the end of the stream is reached.

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

     */

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

        return read(b, off, length, impl.getTimeout());

    }

    int read(byte b[], int off, int length, int timeout) throws IOException {

        int n;

        // EOF already encountered

        if (eof) {

            return -1;

        }

        // connection reset

        if (impl.isConnectionReset()) {

            throw new SocketException("Connection reset");

        }

        // bounds check

        if (length <= 0 || off < 0 || length > b.length - off) {

            if (length == 0) {

                return 0;

            }

            throw new ArrayIndexOutOfBoundsException("length == " + length

                    + " off == " + off + " buffer length == " + b.length);

        }

        boolean gotReset = false;

        // acquire file descriptor and do the read

        FileDescriptor fd = impl.acquireFD();

        try {

            n = socketRead(fd, b, off, length, timeout);

            if (n > 0) {

                return n;

            }

        } catch (ConnectionResetException rstExc) {

            gotReset = true;

        } finally {

            impl.releaseFD();

        }

        /*

         * We receive a "connection reset" but there may be bytes still

         * buffered on the socket

         */

        if (gotReset) {

            impl.setConnectionResetPending();

            impl.acquireFD();

            try {

                n = socketRead(fd, b, off, length, timeout);

                if (n > 0) {

                    return n;

                }

            } catch (ConnectionResetException rstExc) {

            } finally {

                impl.releaseFD();

            }

        }

        /*

         * If we get here we are at EOF, the socket has been closed,

         * or the connection has been reset.

         */

        if (impl.isClosedOrPending()) {

            throw new SocketException("Socket closed");

        }

        if (impl.isConnectionResetPending()) {

            impl.setConnectionReset();

        }

        if (impl.isConnectionReset()) {

            throw new SocketException("Connection reset");

        }

        eof = true;

        return -1;

    }

    /**

     * Reads a single byte from the socket.

     */

    public int read() throws IOException {

        if (eof) {

            return -1;

        }

        temp = new byte[1];

        int n = read(temp, 0, 1);

        if (n <= 0) {

            return -1;

        }

        return temp[0] & 0xff;

    }

    /**

     * Skips n bytes of input.

     * @param numbytes the number of bytes to skip

     * @return  the actual number of bytes skipped.

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

     */

    public long skip(long numbytes) throws IOException {

        if (numbytes <= 0) {

            return 0;

        }

        long n = numbytes;

        int buflen = (int) Math.min(1024, n);

        byte data[] = new byte[buflen];

        while (n > 0) {

            int r = read(data, 0, (int) Math.min((long) buflen, n));

            if (r < 0) {

                break;

            }

            n -= r;

        }

        return numbytes - n;

    }

    /**

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

     * @return the number of immediately available bytes

     */

    public int available() throws IOException {

        return impl.available();

    }

    /**

     * Closes the stream.

     */

    private boolean closing = false;

    public void close() throws IOException {

        // Prevent recursion. See BugId 4484411

        if (closing)

            return;

        closing = true;

        if (socket != null) {

            if (!socket.isClosed())

                socket.close();

        } else

            impl.close();

        closing = false;

    }

    void setEOF(boolean eof) {

        this.eof = eof;

    }

    /**

     * Overrides finalize, the fd is closed by the Socket.

     */

    @SuppressWarnings("deprecation")

    protected void finalize() {}

    /**

     * Perform class load-time initializations.

     */

    private static native void init();

}