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	/*
	* Copyright (c) 1995, 2001, Oracle and/or its affiliates. All rights reserved.
	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
	*
	* This code is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 only, as
	* published by the Free Software Foundation. Oracle designates this
	* particular file as subject to the "Classpath" exception as provided
	* by Oracle in the LICENSE file that accompanied this code.
	*
	* This code is distributed in the hope that it will be useful, but WITHOUT
	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
	* version 2 for more details (a copy is included in the LICENSE file that
	* accompanied this code).
	*
	* You should have received a copy of the GNU General Public License version
	* 2 along with this work; if not, write to the Free Software Foundation,
	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
	*
	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*/
	package sun.misc;

	import java.io.PushbackInputStream;
	import java.io.OutputStream;
	import java.io.PrintStream;
	import java.io.IOException;

	/**
	* This class implements a Berkeley uu character decoder. This decoder
	* was made famous by the uudecode program.
	*
	* The basic character coding is algorithmic, taking 6 bits of binary
	* data and adding it to an ASCII ' ' (space) character. This converts
	* these six bits into a printable representation. Note that it depends
	* on the ASCII character encoding standard for english. Groups of three
	* bytes are converted into 4 characters by treating the three bytes
	* a four 6 bit groups, group 1 is byte 1's most significant six bits,
	* group 2 is byte 1's least significant two bits plus byte 2's four
	* most significant bits. etc.
	*
	* In this encoding, the buffer prefix is:
	* <pre>
	* begin [mode] [filename]
	* </pre>
	*
	* This is followed by one or more lines of the form:
	* <pre>
	* (len)(data)(data)(data) ...
	* </pre>
	* where (len) is the number of bytes on this line. Note that groupings
	* are always four characters, even if length is not a multiple of three
	* bytes. When less than three characters are encoded, the values of the
	* last remaining bytes is undefined and should be ignored.
	*
	* The last line of data in a uuencoded buffer is represented by a single
	* space character. This is translated by the decoding engine to a line
	* length of zero. This is immediately followed by a line which contains
	* the word 'end[newline]'
	*
	* If an error is encountered during decoding this class throws a
	* CEFormatException. The specific detail messages are:
	*
	* <pre>
	* "UUDecoder: No begin line."
	* "UUDecoder: Malformed begin line."
	* "UUDecoder: Short Buffer."
	* "UUDecoder: Bad Line Length."
	* "UUDecoder: Missing 'end' line."
	* </pre>
	*
	* @author Chuck McManis
	* @see CharacterDecoder
	* @see UUEncoder
	*/
	public class UUDecoder extends CharacterDecoder {

	/**
	* This string contains the name that was in the buffer being decoded.
	*/
	public String bufferName;

	/**
	* Represents UNIX(tm) mode bits. Generally three octal digits
	* representing read, write, and execute permission of the owner,
	* group owner, and others. They should be interpreted as the bit groups:
	* <pre>
	* (owner) (group) (others)
	* rwx rwx rwx (r = read, w = write, x = execute)
	*</pre>
	*
	*/
	public int mode;


	/**
	* UU encoding specifies 3 bytes per atom.
	*/
	protected int bytesPerAtom() {
	return (3);
	}

	/**
	* All UU lines have 45 bytes on them, for line length of 15*4+1 or 61
	* characters per line.
	*/
	protected int bytesPerLine() {
	return (45);
	}

	/** This is used to decode the atoms */
	private byte decoderBuffer[] = new byte[4];

	/**
	* Decode a UU atom. Note that if l is less than 3 we don't write
	* the extra bits, however the encoder always encodes 4 character
	* groups even when they are not needed.
	*/
	protected void decodeAtom(PushbackInputStream inStream, OutputStream outStream, int l)
	throws IOException {
	int i, c1, c2, c3, c4;
	int a, b, c;
	StringBuffer x = new StringBuffer();

	for (i = 0; i < 4; i++) {
	c1 = inStream.read();
	if (c1 == -1) {
	throw new CEStreamExhausted();
	}
	x.append((char)c1);
	decoderBuffer[i] = (byte) ((c1 - ' ') & 0x3f);
	}
	a = ((decoderBuffer[0] << 2) & 0xfc) \| ((decoderBuffer[1] >>> 4) & 3);
	b = ((decoderBuffer[1] << 4) & 0xf0) \| ((decoderBuffer[2] >>> 2) & 0xf);
	c = ((decoderBuffer[2] << 6) & 0xc0) \| (decoderBuffer[3] & 0x3f);
	outStream.write((byte)(a & 0xff));
	if (l > 1) {
	outStream.write((byte)( b & 0xff));
	}
	if (l > 2) {
	outStream.write((byte)(c&0xff));
	}
	}

	/**
	* For uuencoded buffers, the data begins with a line of the form:
	* begin MODE FILENAME
	* This line always starts in column 1.
	*/
	protected void decodeBufferPrefix(PushbackInputStream inStream, OutputStream outStream) throws IOException {
	int c;
	StringBuffer q = new StringBuffer(32);
	String r;
	boolean sawNewLine;

	/*
	* This works by ripping through the buffer until it finds a 'begin'
	* line or the end of the buffer.
	*/
	sawNewLine = true;
	while (true) {
	c = inStream.read();
	if (c == -1) {
	throw new CEFormatException("UUDecoder: No begin line.");
	}
	if ((c == 'b') && sawNewLine){
	c = inStream.read();
	if (c == 'e') {
	break;
	}
	}
	sawNewLine = (c == '\n') \|\| (c == '\r');
	}

	/*
	* Now we think its begin, (we've seen ^be) so verify it here.
	*/
	while ((c != '\n') && (c != '\r')) {
	c = inStream.read();
	if (c == -1) {
	throw new CEFormatException("UUDecoder: No begin line.");
	}
	if ((c != '\n') && (c != '\r')) {
	q.append((char)c);
	}
	}
	r = q.toString();
	if (r.indexOf(' ') != 3) {
	throw new CEFormatException("UUDecoder: Malformed begin line.");
	}
	mode = Integer.parseInt(r.substring(4,7));
	bufferName = r.substring(r.indexOf(' ',6)+1);
	/*
	* Check for \n after \r
	*/
	if (c == '\r') {
	c = inStream.read ();
	if ((c != '\n') && (c != -1))
	inStream.unread (c);
	}
	}

	/**
	* In uuencoded buffers, encoded lines start with a character that
	* represents the number of bytes encoded in this line. The last
	* line of input is always a line that starts with a single space
	* character, which would be a zero length line.
	*/
	protected int decodeLinePrefix(PushbackInputStream inStream, OutputStream outStream) throws IOException {
	int c;

	c = inStream.read();
	if (c == ' ') {
	c = inStream.read(); /* discard the (first)trailing CR or LF */
	c = inStream.read(); /* check for a second one */
	if ((c != '\n') && (c != -1))
	inStream.unread (c);
	throw new CEStreamExhausted();
	} else if (c == -1) {
	throw new CEFormatException("UUDecoder: Short Buffer.");
	}

	c = (c - ' ') & 0x3f;
	if (c > bytesPerLine()) {
	throw new CEFormatException("UUDecoder: Bad Line Length.");
	}
	return (c);
	}


	/**
	* Find the end of the line for the next operation.
	* The following sequences are recognized as end-of-line
	* CR, CR LF, or LF
	*/
	protected void decodeLineSuffix(PushbackInputStream inStream, OutputStream outStream) throws IOException {
	int c;
	while (true) {
	c = inStream.read();
	if (c == -1) {
	throw new CEStreamExhausted();
	}
	if (c == '\n') {
	break;
	}
	if (c == '\r') {
	c = inStream.read();
	if ((c != '\n') && (c != -1)) {
	inStream.unread (c);
	}
	break;
	}
	}
	}

	/**
	* UUencoded files have a buffer suffix which consists of the word
	* end. This line should immediately follow the line with a single
	* space in it.
	*/
	protected void decodeBufferSuffix(PushbackInputStream inStream, OutputStream outStream) throws IOException {
	int c;

	c = inStream.read(decoderBuffer);
	if ((decoderBuffer[0] != 'e') \|\| (decoderBuffer[1] != 'n') \|\|
	(decoderBuffer[2] != 'd')) {
	throw new CEFormatException("UUDecoder: Missing 'end' line.");
	}
	}

	}

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