/*
 * Copyright (c) 1995, 2018, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 */

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);
 }

 // 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) {
 impl.setConnectionReset();
 } 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.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", "removal"})
 protected void finalize() {}

 /**
 * Perform class load-time initializations.
 */
 private static native void init();
}