cryptix.util.mime

Class Base64InputStream


public class Base64InputStream
extends FilterInputStream

This class implements a BASE64 Character stream encoder as specified in RFC1521, part of the MIME specification as published by the Internet Engineering Task Force (IETF).

Unlike other encoding schemes there is nothing in this encoding that indicates where a buffer starts or ends. In other words, the encoded text simply starts at the first line and ends with the last one.

Copyright © 1995-1997 Systemics Ltd on behalf of the Cryptix Development Team.
All rights reserved.

$Revision: 1.1.1.1 $

Authors:
FH
Raif S. Naffah
Since:
Cryptix 2.2.2
See Also:
cryptix.mime.Base64OutputStream, cryptix.mime.Base64

Field Summary

(package private) static int
CONV_OTHER
(package private) static int
CONV_PAD
(package private) static int
CONV_WHITE

Constructor Summary

Base64InputStream(InputStream is)
Create a Base64InputStream with no checksum.
Base64InputStream(InputStream is, Checksum checksum, int length)
Creates a Base64InputStream that uses the given checksum.
Base64InputStream(InputStream is, boolean check)
If check is true then look for and check a PGP-style checksum immediately after the base64 portion.

Method Summary

int
available()
Returns the number of bytes that can be guaranteed to be read from this input stream without blocking.
void
close()
void
mark(int readlimit)
Does nothing, since this class does not support mark/reset.
boolean
markSupported()
Tests if this input stream supports the mark and reset methods of InputStream, which it does not.
int
read()
Parse input in fours, producing three bytes to outBuf.
int
read(byte[] buffer, int offset, int length)
void
reset()
Always throws an IOException, since this class does not support mark/reset.
long
skip(long n)
Skips over and discards n bytes of data from the input stream.

Field Details

CONV_OTHER

(package private) static final int CONV_OTHER
Field Value:
-3

CONV_PAD

(package private) static final int CONV_PAD
Field Value:
-2

CONV_WHITE

(package private) static final int CONV_WHITE
Field Value:
-1

Constructor Details

Base64InputStream

public Base64InputStream(InputStream is)
Create a Base64InputStream with no checksum.

Base64InputStream

public Base64InputStream(InputStream is,
                         Checksum checksum,
                         int length)
Creates a Base64InputStream that uses the given checksum. The checksum will be length bytes long, where 0 <= length <= 8.

Base64InputStream

public Base64InputStream(InputStream is,
                         boolean check)
If check is true then look for and check a PGP-style checksum immediately after the base64 portion.

Method Details

available

public int available()
            throws IOException
Returns the number of bytes that can be guaranteed to be read from this input stream without blocking. For a Base64InputStream, this is sometimes 0 even when data is available, because we do not read ahead far enough to determine whether the next character is the start of the checksum.

close

public void close()
            throws IOException

mark

public void mark(int readlimit)
Does nothing, since this class does not support mark/reset.

markSupported

public boolean markSupported()
Tests if this input stream supports the mark and reset methods of InputStream, which it does not.
Returns:
false, since this class does not support the mark and reset methods.

read

public int read()
            throws IOException
Parse input in fours, producing three bytes to outBuf. Should only see whitespace or illegal characters on a quadruplet boundary.

When using a checksum, wait for a "=" as the first character of a quadruplet; read sufficient quadruplets for crcLength bytes, and compare with our crc. If the end of the stream is reached at a bad spot, throw EOFException.

If we get the first illegal character on a four byte boundary, return -1 (Java EOF convention). Iff the underlying input stream is an instanceof PushbackInputStream, the illegal character will be pushed back.

See Also:
java.io.PushbackInputStream

read

public int read(byte[] buffer,
                int offset,
                int length)
            throws IOException

reset

public void reset()
            throws IOException
Always throws an IOException, since this class does not support mark/reset.

skip

public long skip(long n)
            throws IOException
Skips over and discards n bytes of data from the input stream. The skip method may, for a variety of reasons, end up skipping over some smaller number of bytes, possibly 0. The actual number of bytes skipped is returned.
Parameters:
n - the number of bytes to be skipped.
Returns:
the actual number of bytes skipped.