package org.eclipse.cdt.utils.pty;

/*
 * (c) Copyright QNX Software Systems Ltd. 2002.
 * All Rights Reserved.
 */

import java.io.InputStream;
import java.io.IOException;

import org.eclipse.cdt.utils.pty.PTY.MasterFD;

class PTYInputStream extends InputStream {

	MasterFD master;

	/**
	 * Fome a Unix valid file descriptor set a Reader.
	 * @param desc file descriptor.
	 */
	public PTYInputStream(MasterFD fd) {
		master = fd;
	}

	/**
	 * Implementation of read for the InputStream.
	 *
	 * @exception IOException on error.
	 */
	public int read() throws IOException {
		byte b[] = new byte[1];
		if (1 != read(b, 0, 1))
			return -1;
		return (int) b[0];
	}

	/**
	 * @see InputStream#read(byte[], int, int)
	 */
	public int read(byte[] buf, int off, int len) throws IOException {
		if (buf == null) {
			throw new NullPointerException();
		} else if ((off < 0) || (off > buf.length)
					|| (len < 0) || ((off + len) > buf.length)
					|| ((off + len) < 0)) {
			throw new IndexOutOfBoundsException();
		} else if (len == 0) {
			return 0;
		}
		byte[] tmpBuf = new byte[len];

		len = read0(master.getFD(), tmpBuf, len);
		if (len <= 0)
			return -1;

		System.arraycopy(tmpBuf, 0, buf, off, len);
		return len;
	}

	/**
	 * Close the Reader
	 * @exception IOException on error.
	 */
	public void close() throws IOException {
		if (master.getFD() == -1)
			return;
		int status = close0(master.getFD());
		if (status == -1)
			throw new IOException("close error");
		master.setFD(-1);
	}

	private native int read0(int fd, byte[] buf, int len) throws IOException;
	private native int close0(int fd) throws IOException;

	static {
		System.loadLibrary("pty");
	}

}