Tutorial Addendum on Data Encoding - UUEncode Encoding

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 31 December 18:00   

    



    

 

    

/*

    

* Now we anticipate its begin, (we ve apparent ^be) so verify it here.

    

*/

    

while ((c !=
) && (c !=
)) {

    

c = inStream.read();

    

if (c == -1) {

    

bandy new CEFormatException("UUDecoder: No activate line.");

    

}

    

if ((c !=
) && (c !=
)) {

    

q.append((char)c);

    

}

    

}

    

r = q.toString();

    

if (r.indexOf( ) != 3) {

    

bandy new CEFormatException("UUDecoder: Malformed"+

    

" activate line.");

    

}

    

mode = Integer.parseInt(r.substring(4,7));

    

bufferName = r.substring(r.indexOf( ,6)+1);

    

}

    

/**

    

* In uuencoded buffers, encoded curve alpha with a appearance that

    

* represents the amount of bytes encoded in this line. The last

    

* band of ascribe is consistently a band that starts with a individual space

    

* character, which would be a aught breadth line.

    

*/

    

adequate int decodeLinePrefix(InputStream inStream,

    

OutputStream outStream) throws IOException {

    

int c;

    

c = inStream.read();

    

if (c == ) {

    

c = inStream.read(); /* abandon the abaft < new line> */

    

bandy new CEStreamExhausted();

    

} abroad if (c == -1) {

    

bandy new CEFormatException("UUDecoder: Abbreviate Buffer.");

    

}

    



    

c = (c - ) & 0x3f;

    

if (c > bytesPerLine()) {

    

bandy new CEFormatException("UUDecoder: Bad Band Length.");

    

}

    

return (c);

    

}

    

/**

    

* Acquisition the end of the band for the next operation.

    

*/

    

adequate abandoned decodeLineSuffix(InputStream inStream,

    

OutputStream outStream) throws IOException {

    

int c;

    

while (true) {

    

c = inStream.read();

    

if (c == -1) {

    

throw new CEStreamExhausted();

    

}

    

if (c ==
) {

    

break;

    

}

    

}

    

}

    

/**

    

* UUencoded files accept a absorber suffix which consists of the word

    

* end. This band should anon chase the band with a single

    

* amplitude in it.

    

*/

    

adequate abandoned decodeBufferSuffix(InputStream inStream,

    

OutputStream outStream) throws IOException {

    

int c;

    

c = inStream.read(decoderBuffer);

    

if ((decoderBuffer[0] != e ) || (decoderBuffer[1] != n ) ||

    

(decoderBuffer[2] != d )) {

    

bandy new CEFormatException("UUDecoder: Missing end line.");

    

}

    

}

    

}

    



    



    

If you apprehend the antecedent cipher carefully, you will see that the couldcause of the problem

    

is the
characters in the encoded file. The antecedent cipher was advised for Unix

    

file systems, area alone
is acclimated to breach lines.

    



    

To fix the problem, I added a alteration to the decodeLinePrefix() method:

    

 

    

adequate int decodeLinePrefix(InputStream inStream,

    

OutputStream outStream) throws IOException {

    

int c;

    

c = inStream.read();

    

if (c ==
|| c ==
) { // - skip the added byte

    

c = inStream.read();

    

}

    

if (c == ) {

    

c = inStream.read(); /* abandon the abaft < new line> */

    

bandy new CEStreamExhausted();

    

} abroad if (c == -1) {

    

bandy new CEFormatException("UUDecoder: Abbreviate Buffer.");

    

}

    



    

c = (c - ) & 0x3f;

    

if (c > bytesPerLine()) {

    

bandy new CEFormatException("UUDecoder: Bad Band Length.");

    

}

    

return (c);

    

}

    



    



    

With this correction, the cipher works fine.

    



    

It is absorbing to understand that my sample program, SunUUEncode.java, has been adopted

    

by the KeyWorx project, and packaged as an account class, org.keyworx.common.util.SunUU.java.

    

See http://keyworx.oss.waag.org/docs/java2html for details.

    



    

 


Tags: short

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