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/*
* Copyright (C) 2008-2010, Google Inc. and others
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Distribution License v. 1.0 which is available at
* https://www.eclipse.org/org/documents/edl-v10.php.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
package org.eclipse.jgit.transport;
import java.io.IOException;
import java.io.OutputStream;
import java.text.MessageFormat;
import org.eclipse.jgit.internal.JGitText;
/**
* Multiplexes data and progress messages.
* <p>
* This stream is buffered at packet sizes, so the caller doesn't need to wrap
* it in yet another buffered stream.
*
* @since 2.0
*/
public class SideBandOutputStream extends OutputStream {
/** Channel used for pack data. */
public static final int CH_DATA = SideBandInputStream.CH_DATA;
/** Channel used for progress messages. */
public static final int CH_PROGRESS = SideBandInputStream.CH_PROGRESS;
/** Channel used for error messages. */
public static final int CH_ERROR = SideBandInputStream.CH_ERROR;
/** Default buffer size for a small amount of data. */
public static final int SMALL_BUF = 1000;
/** Maximum buffer size for a single packet of sideband data. */
public static final int MAX_BUF = 65520;
static final int HDR_SIZE = 5;
private final OutputStream out;
private final byte[] buffer;
/**
* Number of bytes in {@link #buffer} that are valid data.
* <p>
* Initialized to {@link #HDR_SIZE} if there is no application data in the
* buffer, as the packet header always appears at the start of the buffer.
*/
private int cnt;
/**
* Create a new stream to write side band packets.
*
* @param chan
* channel number to prefix all packets with, so the remote side
* can demultiplex the stream and get back the original data.
* Must be in the range [1, 255].
* @param sz
* maximum size of a data packet within the stream. The remote
* side needs to agree to the packet size to prevent buffer
* overflows. Must be in the range [HDR_SIZE + 1, MAX_BUF).
* @param os
* stream that the packets are written onto. This stream should
* be attached to a SideBandInputStream on the remote side.
*/
public SideBandOutputStream(int chan, int sz, OutputStream os) {
if (chan <= 0 || chan > 255)
throw new IllegalArgumentException(MessageFormat.format(
JGitText.get().channelMustBeInRange1_255,
Integer.valueOf(chan)));
if (sz <= HDR_SIZE)
throw new IllegalArgumentException(MessageFormat.format(
JGitText.get().packetSizeMustBeAtLeast,
Integer.valueOf(sz), Integer.valueOf(HDR_SIZE)));
else if (MAX_BUF < sz)
throw new IllegalArgumentException(MessageFormat.format(
JGitText.get().packetSizeMustBeAtMost, Integer.valueOf(sz),
Integer.valueOf(MAX_BUF)));
out = os;
buffer = new byte[sz];
buffer[4] = (byte) chan;
cnt = HDR_SIZE;
}
void flushBuffer() throws IOException {
if (HDR_SIZE < cnt)
writeBuffer();
}
@Override
public void flush() throws IOException {
flushBuffer();
out.flush();
}
@Override
public void write(byte[] b, int off, int len) throws IOException {
while (0 < len) {
int capacity = buffer.length - cnt;
if (cnt == HDR_SIZE && capacity < len) {
// Our block to write is bigger than the packet size,
// stream it out as-is to avoid unnecessary copies.
PacketLineOut.formatLength(buffer, buffer.length);
out.write(buffer, 0, HDR_SIZE);
out.write(b, off, capacity);
off += capacity;
len -= capacity;
} else {
if (capacity == 0)
writeBuffer();
int n = Math.min(len, capacity);
System.arraycopy(b, off, buffer, cnt, n);
cnt += n;
off += n;
len -= n;
}
}
}
@Override
public void write(int b) throws IOException {
if (cnt == buffer.length)
writeBuffer();
buffer[cnt++] = (byte) b;
}
private void writeBuffer() throws IOException {
PacketLineOut.formatLength(buffer, cnt);
out.write(buffer, 0, cnt);
cnt = HDR_SIZE;
}
}
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