275 lines
9.1 KiB
Java
275 lines
9.1 KiB
Java
/*
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* Copyright (c) 1995, 2001, 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.PushbackInputStream;
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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 decoder. This decoder
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* was made famous by the uudecode 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 buffer 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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* If an error is encountered during decoding this class throws a
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* CEFormatException. The specific detail messages are:
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*
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* <pre>
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* "UUDecoder: No begin line."
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* "UUDecoder: Malformed begin line."
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* "UUDecoder: Short Buffer."
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* "UUDecoder: Bad Line Length."
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* "UUDecoder: Missing 'end' line."
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* </pre>
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*
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* @author Chuck McManis
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* @see CharacterDecoder
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* @see UUEncoder
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*/
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public class UUDecoder extends CharacterDecoder {
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/**
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* This string contains the name that was in the buffer being decoded.
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*/
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public String bufferName;
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/**
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* Represents UNIX(tm) mode bits. Generally three octal digits
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* representing read, write, and execute permission of the owner,
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* group owner, and others. They should be interpreted as the bit groups:
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* <pre>
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* (owner) (group) (others)
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* rwx rwx rwx (r = read, w = write, x = execute)
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*</pre>
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*
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*/
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public int mode;
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/**
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* UU encoding specifies 3 bytes per atom.
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*/
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protected int bytesPerAtom() {
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return (3);
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}
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/**
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* All UU lines have 45 bytes on them, for line length of 15*4+1 or 61
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* characters per line.
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*/
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protected int bytesPerLine() {
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return (45);
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}
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/** This is used to decode the atoms */
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private byte decoderBuffer[] = new byte[4];
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/**
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* Decode a UU atom. Note that if l is less than 3 we don't write
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* the extra bits, however the encoder always encodes 4 character
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* groups even when they are not needed.
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*/
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protected void decodeAtom(PushbackInputStream inStream, OutputStream outStream, int l)
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throws IOException {
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int i, c1, c2, c3, c4;
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int a, b, c;
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StringBuffer x = new StringBuffer();
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for (i = 0; i < 4; i++) {
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c1 = inStream.read();
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if (c1 == -1) {
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throw new CEStreamExhausted();
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}
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x.append((char)c1);
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decoderBuffer[i] = (byte) ((c1 - ' ') & 0x3f);
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}
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a = ((decoderBuffer[0] << 2) & 0xfc) | ((decoderBuffer[1] >>> 4) & 3);
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b = ((decoderBuffer[1] << 4) & 0xf0) | ((decoderBuffer[2] >>> 2) & 0xf);
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c = ((decoderBuffer[2] << 6) & 0xc0) | (decoderBuffer[3] & 0x3f);
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outStream.write((byte)(a & 0xff));
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if (l > 1) {
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outStream.write((byte)( b & 0xff));
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}
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if (l > 2) {
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outStream.write((byte)(c&0xff));
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}
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}
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/**
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* For uuencoded buffers, the data begins with a line of the form:
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* begin MODE FILENAME
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* This line always starts in column 1.
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*/
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protected void decodeBufferPrefix(PushbackInputStream inStream, OutputStream outStream) throws IOException {
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int c;
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StringBuffer q = new StringBuffer(32);
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String r;
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boolean sawNewLine;
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/*
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* This works by ripping through the buffer until it finds a 'begin'
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* line or the end of the buffer.
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*/
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sawNewLine = true;
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while (true) {
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c = inStream.read();
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if (c == -1) {
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throw new CEFormatException("UUDecoder: No begin line.");
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}
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if ((c == 'b') && sawNewLine){
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c = inStream.read();
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if (c == 'e') {
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break;
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}
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}
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sawNewLine = (c == '\n') || (c == '\r');
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}
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/*
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* Now we think its begin, (we've seen ^be) so verify it here.
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*/
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while ((c != '\n') && (c != '\r')) {
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c = inStream.read();
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if (c == -1) {
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throw new CEFormatException("UUDecoder: No begin line.");
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}
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if ((c != '\n') && (c != '\r')) {
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q.append((char)c);
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}
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}
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r = q.toString();
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if (r.indexOf(' ') != 3) {
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throw new CEFormatException("UUDecoder: Malformed begin line.");
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}
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mode = Integer.parseInt(r.substring(4,7));
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bufferName = r.substring(r.indexOf(' ',6)+1);
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/*
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* Check for \n after \r
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*/
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if (c == '\r') {
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c = inStream.read ();
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if ((c != '\n') && (c != -1))
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inStream.unread (c);
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}
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}
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/**
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* In uuencoded buffers, encoded lines start with a character that
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* represents the number of bytes encoded in this line. The last
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* line of input is always a line that starts with a single space
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* character, which would be a zero length line.
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*/
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protected int decodeLinePrefix(PushbackInputStream inStream, OutputStream outStream) throws IOException {
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int c;
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c = inStream.read();
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if (c == ' ') {
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c = inStream.read(); /* discard the (first)trailing CR or LF */
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c = inStream.read(); /* check for a second one */
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if ((c != '\n') && (c != -1))
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inStream.unread (c);
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throw new CEStreamExhausted();
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} else if (c == -1) {
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throw new CEFormatException("UUDecoder: Short Buffer.");
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}
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c = (c - ' ') & 0x3f;
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if (c > bytesPerLine()) {
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throw new CEFormatException("UUDecoder: Bad Line Length.");
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}
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return (c);
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}
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/**
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* Find the end of the line for the next operation.
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* The following sequences are recognized as end-of-line
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* CR, CR LF, or LF
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*/
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protected void decodeLineSuffix(PushbackInputStream inStream, OutputStream outStream) throws IOException {
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int c;
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while (true) {
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c = inStream.read();
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if (c == -1) {
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throw new CEStreamExhausted();
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}
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if (c == '\n') {
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break;
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}
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if (c == '\r') {
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c = inStream.read();
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if ((c != '\n') && (c != -1)) {
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inStream.unread (c);
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}
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break;
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}
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}
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}
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/**
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* UUencoded files have a buffer suffix which consists of the word
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* end. This line should immediately follow the line with a single
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* space in it.
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*/
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protected void decodeBufferSuffix(PushbackInputStream inStream, OutputStream outStream) throws IOException {
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int c;
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c = inStream.read(decoderBuffer);
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if ((decoderBuffer[0] != 'e') || (decoderBuffer[1] != 'n') ||
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(decoderBuffer[2] != 'd')) {
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throw new CEFormatException("UUDecoder: Missing 'end' line.");
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}
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}
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}
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