201 lines
6.4 KiB
Java
201 lines
6.4 KiB
Java
/*
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* Copyright (c) 1995, 2004, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation. Oracle designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Oracle in the LICENSE file that accompanied this code.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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package sun.misc;
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import java.io.InputStream;
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import java.io.OutputStream;
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import java.io.PrintStream;
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import java.io.IOException;
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/**
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* This class implements a Berkeley uu character encoder. This encoder
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* was made famous by uuencode program.
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*
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* The basic character coding is algorithmic, taking 6 bits of binary
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* data and adding it to an ASCII ' ' (space) character. This converts
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* these six bits into a printable representation. Note that it depends
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* on the ASCII character encoding standard for english. Groups of three
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* bytes are converted into 4 characters by treating the three bytes
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* a four 6 bit groups, group 1 is byte 1's most significant six bits,
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* group 2 is byte 1's least significant two bits plus byte 2's four
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* most significant bits. etc.
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*
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* In this encoding, the buffer prefix is:
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* <pre>
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* begin [mode] [filename]
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* </pre>
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*
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* This is followed by one or more lines of the form:
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* <pre>
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* (len)(data)(data)(data) ...
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* </pre>
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* where (len) is the number of bytes on this line. Note that groupings
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* are always four characters, even if length is not a multiple of three
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* bytes. When less than three characters are encoded, the values of the
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* last remaining bytes is undefined and should be ignored.
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*
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* The last line of data in a uuencoded file is represented by a single
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* space character. This is translated by the decoding engine to a line
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* length of zero. This is immediately followed by a line which contains
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* the word 'end[newline]'
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*
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* @author Chuck McManis
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* @see CharacterEncoder
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* @see UUDecoder
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*/
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public class UUEncoder extends CharacterEncoder {
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/**
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* This name is stored in the begin line.
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*/
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private String bufferName;
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/**
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* Represents UNIX(tm) mode bits. Generally three octal digits representing
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* read, write, and execute permission of the owner, group owner, and
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* others. They should be interpreted as the bit groups:
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* (owner) (group) (others)
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* rwx rwx rwx (r = read, w = write, x = execute)
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*
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* By default these are set to 644 (UNIX rw-r--r-- permissions).
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*/
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private int mode;
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/**
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* Default - buffer begin line will be:
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* <pre>
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* begin 644 encoder.buf
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* </pre>
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*/
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public UUEncoder() {
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bufferName = "encoder.buf";
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mode = 644;
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}
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/**
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* Specifies a name for the encoded buffer, begin line will be:
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* <pre>
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* begin 644 [FNAME]
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* </pre>
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*/
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public UUEncoder(String fname) {
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bufferName = fname;
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mode = 644;
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}
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/**
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* Specifies a name and mode for the encoded buffer, begin line will be:
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* <pre>
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* begin [MODE] [FNAME]
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* </pre>
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*/
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public UUEncoder(String fname, int newMode) {
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bufferName = fname;
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mode = newMode;
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}
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/** number of bytes per atom in uuencoding is 3 */
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protected int bytesPerAtom() {
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return (3);
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}
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/** number of bytes per line in uuencoding is 45 */
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protected int bytesPerLine() {
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return (45);
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}
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/**
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* encodeAtom - take three bytes and encodes them into 4 characters
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* If len is less than 3 then remaining bytes are filled with '1'.
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* This insures that the last line won't end in spaces and potentiallly
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* be truncated.
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*/
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protected void encodeAtom(OutputStream outStream, byte data[], int offset, int len)
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throws IOException {
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byte a, b = 1, c = 1;
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int c1, c2, c3, c4;
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a = data[offset];
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if (len > 1) {
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b = data[offset+1];
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}
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if (len > 2) {
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c = data[offset+2];
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}
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c1 = (a >>> 2) & 0x3f;
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c2 = ((a << 4) & 0x30) | ((b >>> 4) & 0xf);
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c3 = ((b << 2) & 0x3c) | ((c >>> 6) & 0x3);
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c4 = c & 0x3f;
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outStream.write(c1 + ' ');
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outStream.write(c2 + ' ');
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outStream.write(c3 + ' ');
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outStream.write(c4 + ' ');
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return;
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}
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/**
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* Encode the line prefix which consists of the single character. The
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* lenght is added to the value of ' ' (32 decimal) and printed.
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*/
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protected void encodeLinePrefix(OutputStream outStream, int length)
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throws IOException {
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outStream.write((length & 0x3f) + ' ');
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}
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/**
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* The line suffix for uuencoded files is simply a new line.
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*/
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protected void encodeLineSuffix(OutputStream outStream) throws IOException {
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pStream.println();
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}
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/**
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* encodeBufferPrefix writes the begin line to the output stream.
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*/
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protected void encodeBufferPrefix(OutputStream a) throws IOException {
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super.pStream = new PrintStream(a);
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super.pStream.print("begin "+mode+" ");
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if (bufferName != null) {
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super.pStream.println(bufferName);
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} else {
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super.pStream.println("encoder.bin");
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}
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super.pStream.flush();
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}
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/**
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* encodeBufferSuffix writes the single line containing space (' ') and
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* the line containing the word 'end' to the output stream.
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*/
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protected void encodeBufferSuffix(OutputStream a) throws IOException {
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super.pStream.println(" \nend");
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super.pStream.flush();
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}
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}
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