UUDecoderStreampublic class UUDecoderStream extends FilterInputStream | This class implements a UUDecoder. It is implemented as
a FilterInputStream, so one can just wrap this class around
any input stream and read bytes from this filter. The decoding
is done as the bytes are read out. |
| Fields Summary |
|---|
| private String | name | | private int | mode | | private byte[] | buffer | | private int | bufsize | | private int | index | | private boolean | gotPrefix | | private boolean | gotEnd | | private LineInputStream | lin |
| Constructors Summary |
|---|
public UUDecoderStream(InputStream in)Create a UUdecoder that decodes the specified input stream
super(in);
lin = new LineInputStream(in);
buffer = new byte[45]; // max decoded chars in a line = 45
|
| Methods Summary |
|---|
| public int | available()
// This is only an estimate, since in.available()
// might include CRLFs too ..
return ((in.available() * 3)/4 + (bufsize-index));
| | private boolean | decode()
if (gotEnd)
return false;
bufsize = 0;
String line;
do {
line = lin.readLine();
/*
* Improperly encoded data sometimes omits the zero length
* line that starts with a space character, we detect the
* following "end" line here.
*/
if (line == null)
throw new IOException("Missing End");
if (line.regionMatches(true, 0, "end", 0, 3)) {
gotEnd = true;
return false;
}
} while (line.length() == 0);
int count = line.charAt(0);
if (count < ' ")
throw new IOException("Buffer format error");
/*
* The first character in a line is the number of original (not
* the encoded atoms) characters in the line. Note that all the
* code below has to handle the <SPACE> character that indicates
* end of encoded stream.
*/
count = (count - ' ") & 0x3f;
if (count == 0) {
line = lin.readLine();
if (line == null || !line.regionMatches(true, 0, "end", 0, 3))
throw new IOException("Missing End");
gotEnd = true;
return false;
}
int need = ((count * 8)+5)/6;
//System.out.println("count " + count + ", need " + need + ", len " + line.length());
if (line.length() < need + 1)
throw new IOException("Short buffer error");
int i = 1;
byte a, b;
/*
* A correct uuencoder always encodes 3 characters at a time, even
* if there aren't 3 characters left. But since some people out
* there have broken uuencoders we handle the case where they
* don't include these "unnecessary" characters.
*/
while (bufsize < count) {
// continue decoding until we get 'count' decoded chars
a = (byte)((line.charAt(i++) - ' ") & 0x3f);
b = (byte)((line.charAt(i++) - ' ") & 0x3f);
buffer[bufsize++] = (byte)(((a << 2) & 0xfc) | ((b >>> 4) & 3));
if (bufsize < count) {
a = b;
b = (byte)((line.charAt(i++) - ' ") & 0x3f);
buffer[bufsize++] =
(byte)(((a << 4) & 0xf0) | ((b >>> 2) & 0xf));
}
if (bufsize < count) {
a = b;
b = (byte)((line.charAt(i++) - ' ") & 0x3f);
buffer[bufsize++] = (byte)(((a << 6) & 0xc0) | (b & 0x3f));
}
}
return true;
| | public int | getMode()Get the "mode" field from the prefix. This is the permission
mode of the source file.
readPrefix();
return mode;
| | public java.lang.String | getName()Get the "name" field from the prefix. This is meant to
be the pathname of the decoded file
readPrefix();
return name;
| | public boolean | markSupported()
return false;
| | public int | read()Read the next decoded byte from this input stream. The byte
is returned as an int in the range 0
to 255. If no byte is available because the end of
the stream has been reached, the value -1 is returned.
This method blocks until input data is available, the end of the
stream is detected, or an exception is thrown.
if (index >= bufsize) {
readPrefix();
if (!decode())
return -1;
index = 0; // reset index into buffer
}
return buffer[index++] & 0xff; // return lower byte
| | public int | read(byte[] buf, int off, int len)
int i, c;
for (i = 0; i < len; i++) {
if ((c = read()) == -1) {
if (i == 0) // At end of stream, so we should
i = -1; // return -1, NOT 0.
break;
}
buf[off+i] = (byte)c;
}
return i;
| | private void | readPrefix()UUencoded streams start off with the line:
"begin "
Search for this prefix and gobble it up.
if (gotPrefix) // got the prefix
return;
String s;
for (;;) {
// read till we get the prefix: "begin MODE FILENAME"
s = lin.readLine(); // NOTE: readLine consumes CRLF pairs too
if (s == null)
throw new IOException("UUDecoder error: No Begin");
if (s.regionMatches(true, 0, "begin", 0, 5)) {
try {
mode = Integer.parseInt(s.substring(6,9));
} catch (NumberFormatException ex) {
throw new IOException("UUDecoder error: " + ex.toString());
}
name = s.substring(10);
gotPrefix = true;
return;
}
}
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