/*
* @(#)UUDecoder.java 1.6 95/10/08 Chuck McManis
*
* Copyright (c) 1994 Sun Microsystems, Inc. All Rights Reserved.
*
* Permission to use, copy, modify, and distribute this software
* and its documentation for NON-COMMERCIAL purposes and without
* fee is hereby granted provided that this copyright notice
* appears in all copies. Please refer to the file "copyright.html"
* for further important copyright and licensing information.
*
* SUN MAKES NO REPRESENTATIONS OR WARRANTIES ABOUT THE SUITABILITY OF
* THE SOFTWARE, EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
* TO THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
* PARTICULAR PURPOSE, OR NON-INFRINGEMENT. SUN SHALL NOT BE LIABLE FOR
* ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING OR
* DISTRIBUTING THIS SOFTWARE OR ITS DERIVATIVES.
*/
package sun.misc;
import java.io.InputStream;
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>
*
* @version 1.6, 08 Oct 1995
* @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.
*/
int bytesPerAtom() {
return (3);
}
/**
* All UU lines have 45 bytes on them, for line length of 15*4+1 or 61
* characters per line.
*/
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.
*/
void decodeAtom(InputStream 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.
*/
void decodeBufferPrefix(InputStream 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);
}
/**
* 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.
*/
int decodeLinePrefix(InputStream inStream, OutputStream outStream) throws IOException {
int c;
c = inStream.read();
if (c == ' ') {
c = inStream.read(); /* discard the trailing <newline> */
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.
*/
void decodeLineSuffix(InputStream inStream, OutputStream outStream) throws IOException {
int c;
while (true) {
c = inStream.read();
if (c == -1) {
throw new CEStreamExhausted();
}
if (c == '\n') {
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.
*/
void decodeBufferSuffix(InputStream 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.");
}
}
}