This bug was found by St.Petersburg Java SQE team (by Stanislav Avzan).

The java.io.InputStream.skip(long n) method works wrong with negative n,
or, to be more exact, if (int) n is negative.

It throws NegativeArraySizeException in this case.
But Java Language Specification doesn't mention this possibility.
It states very briefly:
"22.3.4 public long skip(long n) throws IOException

The general contract of skip is that it makes an attempt to skip over n
bytes of data from the input stream, discarding the skipped bytes.
However, it may skip over some smaller number of bytes, possibly
zero. This may result from any of a number of conditions; reaching end
of file before n bytes have been skipped is only one possibility. The
actual number of bytes skipped is returned."

Here is the example demonstrating the bug:
----Test.java---------------------
import java.io.*;

public class Test {

public static void main( String argv[] ) {

 MyInputStream in = new MyInputStream();
 long skipped;
 try {
   skipped = in.skip(-23);
   System.out.println("0 bytes should be skipped: "+skipped);
 } catch (IOException e) {
   System.out.println("IOException is thrown - possible result");
 } catch (Throwable e) {
   System.out.println("Unexpected "+e+" is thrown!");
 }
}

}

class MyInputStream extends InputStream {
public int read() { return 0; }
public int available() { return 0; }
}
-----Output------------------------
Unexpected java.lang.NegativeArraySizeException is thrown!
----------------------------------



Name: saC57035 Date: 12/02/96


The similar bug is found in LineNumberInputStream as well.
Attention please! All these bugs aren't fixed in 1.1 release!


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