/*
* @(#)UUEncoder.java 1.8 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 encoder. This encoder
* was made famous by uuencode 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 file 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]'
*
* @version 1.8, 08 Oct 1995
* @author Chuck McManis
* @see CharacterEncoder
* @see UUDecoder
*/
public class UUEncoder extends CharacterEncoder {
/**
* This name is stored in the begin line.
*/
private 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:
* (owner) (group) (others)
* rwx rwx rwx (r = read, w = write, x = execute)
*
* By default these are set to 644 (UNIX rw-r--r-- permissions).
*/
private int mode;
/**
* Default - buffer begin line will be:
* <pre>
* begin 644 encoder.buf
* </pre>
*/
public UUEncoder() {
bufferName = "encoder.buf";
mode = 644;
}
/**
* Specifies a name for the encoded bufer, begin line will be:
* <pre>
* begin 644 [FNAME]
* </pre>
*/
public UUEncoder(String fname) {
bufferName = fname;
mode = 644;
}
/**
* Specifies a name and mode for the encoded bufer, begin line will be:
* <pre>
* begin [MODE] [FNAME]
* </pre>
*/
public UUEncoder(String fname, int newMode) {
bufferName = fname;
mode = newMode;
}
/** number of bytes per atom in uuencoding is 3 */
int bytesPerAtom() {
return (3);
}
/** number of bytes per line in uuencoding is 45 */
int bytesPerLine() {
return (45);
}
/**
* encodeAtom - take three bytes and encodes them into 4 characters
* If len is less than 3 then remaining bytes are filled with '1'.
* This insures that the last line won't end in spaces and potentiallly
* be truncated.
*/
void encodeAtom(OutputStream outStream, byte data[], int offset, int len)
throws IOException {
byte a, b = 1, c = 1;
int c1, c2, c3, c4;
a = data[offset];
if (len > 1) {
b = data[offset+1];
}
if (len > 2) {
c = data[offset+2];
}
c1 = (a >>> 2) & 0xff;
c2 = ((a << 4) & 0x30) | ((b >>> 4) & 0xf);
c3 = ((b << 2) & 0x3c) | ((c >>> 6) & 0x3);
c4 = c & 0x3f;
outStream.write(c1 + ' ');
outStream.write(c2 + ' ');
outStream.write(c3 + ' ');
outStream.write(c4 + ' ');
return;
}
/**
* Encode the line prefix which consists of the single character. The
* lenght is added to the value of ' ' (32 decimal) and printed.
*/
void encodeLinePrefix(OutputStream outStream, int length)
throws IOException {
outStream.write((length & 0x3f) + ' ');
}
/**
* The line suffix for uuencoded files is simply a new line.
*/
void encodeLineSuffix(OutputStream outStream) throws IOException {
pStream.println();
}
/**
* encodeBufferPrefix writes the begin line to the output stream.
*/
void encodeBufferPrefix(OutputStream a) throws IOException {
super.pStream = new PrintStream(a);
super.pStream.print("begin "+mode+" ");
if (bufferName != null) {
super.pStream.println(bufferName);
} else {
super.pStream.println("encoder.bin");
}
super.pStream.flush();
}
/**
* encodeBufferSuffix writes the single line containing space (' ') and
* the line containing the word 'end' to the output stream.
*/
void encodeBufferSuffix(OutputStream a) throws IOException {
super.pStream.println(" \nend");
super.pStream.flush();
}
}