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// Copyright 2014 The Bazel Authors. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package com.google.devtools.build.lib.unix;
import com.google.devtools.build.lib.UnixJniLoader;
import java.io.Closeable;
import java.io.FileDescriptor;
import java.io.IOException;
import java.io.InterruptedIOException;
import java.net.SocketException;
import java.net.SocketTimeoutException;
/**
* Abstract superclass for client and server local sockets.
*/
abstract class LocalSocket implements Closeable {
protected enum State {
NEW,
BOUND, // server only
LISTENING, // server only
CONNECTED, // client only
CLOSED,
}
protected LocalSocketAddress address = null;
protected FileDescriptor fd = new FileDescriptor();
protected State state;
protected boolean inputShutdown = false;
protected boolean outputShutdown = false;
/**
* Constructs an unconnected local socket.
*/
protected LocalSocket() throws IOException {
socket(fd);
if (!fd.valid()) {
throw new IOException("Couldn't create socket!");
}
this.state = State.NEW;
}
/**
* Returns the address of the endpoint this socket is bound to.
*
* @return a <code>SocketAddress</code> representing the local endpoint of
* this socket.
*/
public LocalSocketAddress getLocalSocketAddress() {
return address;
}
/**
* Closes this socket. This operation is idempotent.
*
* To be consistent with Java Socket, the shutdown states of the socket are
* not changed. This makes it easier to port applications between Socket and
* LocalSocket.
*
* @throws IOException if an I/O error occurred when closing the socket.
*/
@Override
public synchronized void close() throws IOException {
if (state == State.CLOSED) {
return;
}
// Closes the file descriptor if it has not been closed by the
// input/output streams.
if (!fd.valid()) {
throw new IllegalStateException("LocalSocket.close(-1)");
}
close(fd);
if (fd.valid()) {
throw new IllegalStateException("LocalSocket.close() did not set fd to -1");
}
this.state = State.CLOSED;
}
/**
* Returns the closed state of the ServerSocket.
*
* @return true if the socket has been closed
*/
public synchronized boolean isClosed() {
// If the file descriptor has been closed by the input/output
// streams, marks the socket as closed too.
return state == State.CLOSED;
}
/**
* Returns the connected state of the ClientSocket.
*
* @return true if the socket is currently connected.
*/
public synchronized boolean isConnected() {
return state == State.CONNECTED;
}
protected synchronized void checkConnected() throws SocketException {
if (!isConnected()) {
throw new SocketException("Transport endpoint is not connected");
}
}
protected synchronized void checkNotClosed() throws SocketException {
if (isClosed()) {
throw new SocketException("socket is closed");
}
}
/**
* Returns the shutdown state of the input channel.
*
* @return true is the input channel of the socket is shutdown.
*/
public synchronized boolean isInputShutdown() {
return inputShutdown;
}
/**
* Returns the shutdown state of the output channel.
*
* @return true is the input channel of the socket is shutdown.
*/
public synchronized boolean isOutputShutdown() {
return outputShutdown;
}
protected synchronized void checkInputNotShutdown() throws SocketException {
if (isInputShutdown()) {
throw new SocketException("Socket input is shutdown");
}
}
protected synchronized void checkOutputNotShutdown() throws SocketException {
if (isOutputShutdown()) {
throw new SocketException("Socket output is shutdown");
}
}
static final int SHUT_RD = 0; // Mapped to BSD SHUT_RD in JNI.
static final int SHUT_WR = 1; // Mapped to BSD SHUT_WR in JNI.
public synchronized void shutdownInput() throws IOException {
checkNotClosed();
checkConnected();
checkInputNotShutdown();
inputShutdown = true;
shutdown(fd, SHUT_RD);
}
public synchronized void shutdownOutput() throws IOException {
checkNotClosed();
checkConnected();
checkOutputNotShutdown();
outputShutdown = true;
shutdown(fd, SHUT_WR);
}
////////////////////////////////////////////////////////////////////////
// JNI:
static {
UnixJniLoader.loadJni();
}
// The native calls below are thin wrappers around linux system calls. The
// semantics remains the same except for poll(). See the comments for the
// method.
//
// Note: FileDescriptor is a box for a mutable integer that is visible only
// to native code.
// Generic operations:
protected static native void socket(FileDescriptor server)
throws IOException;
static native void close(FileDescriptor server)
throws IOException;
/**
* Shut down part of a full-duplex connection
* @param code Must be either SHUT_RD or SHUT_WR
*/
static native void shutdown(FileDescriptor fd, int code)
throws IOException;
/**
* This method checks waits for the given file descriptor to become available for read.
* If timeoutMillis passed and there is no activity, a SocketTimeoutException will be thrown.
*/
protected static native void poll(FileDescriptor read, long timeoutMillis)
throws IOException, SocketTimeoutException, InterruptedIOException;
// Server operations:
protected static native void bind(FileDescriptor server, String filename)
throws IOException;
protected static native void listen(FileDescriptor server, int backlog)
throws IOException;
protected static native void accept(FileDescriptor server,
FileDescriptor client)
throws IOException;
// Client operations:
protected static native void connect(FileDescriptor client, String filename)
throws IOException;
}
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