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*
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* Copyright (C) 2008 JRuby project
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package org.jruby.ext.ffi.io;
import org.jruby.Ruby;
import jnr.posix.LibC;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.channels.ByteChannel;
/**
* An implementation of ByteChannel that reads from and writes to a native unix
* file descriptor.
*/
public class FileDescriptorByteChannel implements ByteChannel {
private final LibC libc;
private final int fd;
private volatile boolean isOpen = true;
private static LibC libc(Ruby runtime) {
LibC libc = runtime.getPosix().libc();
if (libc == null) {
throw runtime.newNotImplementedError("native access not enabled");
}
return libc;
}
/**
* Creates a new <tt>FileDescriptorByteChannel</tt>.
*
* @param fd The native unix fd to read/write.
*/
public FileDescriptorByteChannel(Ruby runtime, int fd) {
this.fd = fd;
this.libc = libc(runtime);
}
/**
* Reads data from the native unix file descriptor.
* @param dst The destination <tt>ByteBuffer</tt> to place read bytes in.
* @return The number of bytes read.
*
* @throws java.io.IOException If an error occurred during reading.
*/
public int read(ByteBuffer dst) throws IOException {
if (!isOpen) {
throw new IOException("Not open");
}
int n = libc.read(fd, dst, dst.remaining());
if (n > 0) {
dst.position(dst.position() + n);
} else if (n == 0) {
return -1; // EOF
}
return n;
}
/**
* Writes data to the native unix file descriptor.
*
* @param src The source <tt>ByteBuffer</tt> to write to the file descriptor.
* @return The number of bytes written.
*
* @throws java.io.IOException If an error occurred during writing.
*/
public int write(ByteBuffer src) throws IOException {
if (!isOpen) {
throw new IOException("Not open");
}
int n = libc.write(fd, src, src.remaining());
if (n > 0) {
src.position(src.position() + n);
}
return n;
}
/**
* Tests if the ByteChannel is open.
*
* @return <tt>true</tt> if the Channel is still open
*/
public boolean isOpen() {
return isOpen;
}
/**
* Closes the <tt>Channel</tt>.
* <p>
* This closes the underlying native file descriptor.
* </p>
* @throws java.io.IOException
*/
public void close() throws IOException {
if (!isOpen) {
throw new IllegalStateException("file already closed");
}
isOpen = false;
libc.close(fd);
}
}