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/*******************************************************************************
* Copyright (c) 2007-2019 Wind River Systems, Inc. and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License 2.0
* which accompanies this distribution, and is available at
* https://www.eclipse.org/legal/epl-2.0/
*
* Contributors:
* Wind River Systems - initial API and implementation
*******************************************************************************/
package org.eclipse.tcf.core;
import java.io.IOException;
import org.eclipse.tcf.protocol.IPeer;
/**
* Abstract implementation of IChannel interface for stream oriented transport protocols.
*
* StreamChannel implements communication link connecting two end points (peers).
* The channel asynchronously transmits messages: commands, results and events.
*
* StreamChannel uses escape sequences to represent End-Of-Message and End-Of-Stream markers.
*
* Clients can subclass StreamChannel to support particular stream oriented transport (wire) protocol.
* Also, see ChannelTCP for a concrete IChannel implementation that works on top of TCP sockets as a transport.
*/
public abstract class StreamChannel extends AbstractChannel {
public static final int ESC = 3;
private int bin_data_size;
private final byte[] esc_buf = new byte[0x1000];
private final byte[] inp_buf = new byte[0x4000];
private int inp_buf_pos;
private int inp_buf_len;
public StreamChannel(IPeer remote_peer) {
super(remote_peer);
}
public StreamChannel(IPeer local_peer, IPeer remote_peer) {
super(local_peer, remote_peer);
}
protected abstract int get() throws IOException;
protected abstract void put(int n) throws IOException;
protected int get(byte[] buf) throws IOException {
/* Default implementation - it is expected to be overridden */
int i = 0;
while (i < buf.length) {
int b = get();
if (b < 0) {
if (i == 0) return -1;
break;
}
buf[i++] = (byte)b;
if (i >= bin_data_size) break;
}
return i;
}
protected void put(byte[] buf) throws IOException {
/* Default implementation - it is expected to be overridden */
for (byte b : buf) put(b & 0xff);
}
/**
* @since 1.3
*/
protected void put(byte[] buf, int pos, int len) throws IOException {
/* Default implementation - it is expected to be overridden */
int end = pos + len;
while (pos < end) put(buf[pos++] & 0xff);
}
@Override
protected final int read() throws IOException {
for (;;) {
while (inp_buf_pos >= inp_buf_len) {
inp_buf_len = get(inp_buf);
inp_buf_pos = 0;
if (inp_buf_len < 0) return EOS;
}
int res = inp_buf[inp_buf_pos++] & 0xff;
if (bin_data_size > 0) {
bin_data_size--;
return res;
}
if (res != ESC) return res;
while (inp_buf_pos >= inp_buf_len) {
inp_buf_len = get(inp_buf);
inp_buf_pos = 0;
if (inp_buf_len < 0) return EOS;
}
int n = inp_buf[inp_buf_pos++] & 0xff;
switch (n) {
case 0: return ESC;
case 1: return EOM;
case 2: return EOS;
case 3:
for (int i = 0;; i += 7) {
while (inp_buf_pos >= inp_buf_len) {
inp_buf_len = get(inp_buf);
inp_buf_pos = 0;
if (inp_buf_len < 0) return EOS;
}
int m = inp_buf[inp_buf_pos++] & 0xff;
bin_data_size |= (m & 0x7f) << i;
if ((m & 0x80) == 0) break;
}
break;
default:
throw new IOException("Invalid escape sequence: " + ESC + " " + n);
}
}
}
@Override
protected final void write(int n) throws IOException {
switch (n) {
case ESC:
esc_buf[0] = ESC;
esc_buf[1] = 0;
put(esc_buf, 0, 2);
break;
case EOM:
esc_buf[0] = ESC;
esc_buf[1] = 1;
put(esc_buf, 0, 2);
break;
case EOS:
esc_buf[0] = ESC;
esc_buf[1] = 2;
put(esc_buf, 0, 2);
break;
default:
assert n >= 0 && n <= 0xff;
put(n);
break;
}
}
@Override
protected final void write(byte[] buf) throws IOException {
write(buf, 0, buf.length);
}
@Override
protected final void write(byte[] buf, int pos, int len) throws IOException {
if (len > 32 && isZeroCopySupported()) {
int n = len;
int esc_buf_pos = 0;
esc_buf[esc_buf_pos++] = ESC;
esc_buf[esc_buf_pos++] = 3;
for (;;) {
if (n <= 0x7f) {
esc_buf[esc_buf_pos++] = (byte)n;
break;
}
esc_buf[esc_buf_pos++] = (byte)((n & 0x7f) | 0x80);
n = n >> 7;
}
put(esc_buf, 0, esc_buf_pos);
put(buf, pos, len);
}
else {
int esc_buf_pos = 0;
int end = pos + len;
for (int i = pos; i < end; i++) {
if (esc_buf_pos + 2 > esc_buf.length) {
put(esc_buf, 0, esc_buf_pos);
esc_buf_pos = 0;
}
byte b = buf[i];
esc_buf[esc_buf_pos++] = b;
if (b == ESC) esc_buf[esc_buf_pos++] = 0;
}
put(esc_buf, 0, esc_buf_pos);
}
}
}
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