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

The java.io.StringBufferInputStream.skip(n) method does not work with
large values of n according to the Java language specification.

The Java Language specification
(Version 1.0 - August 1, 1996)
says the following (please see item 22.6.8):

"22.6.8 public long skip(long n)

The actual number k of bytes to be skipped is equal to the smaller of n and
count-pos. The value k is added into pos and k is returned.

Overrides the skip method of InputStream (p. 22.3.4)."


So this method should should not skip more than count-pos bytes. But in fact
it does when n+pos > Long.MAX_VALUE.
Source code fragment is as follows:

if (pos + n > count) {
n = count - pos;

It is clearly seen that overflow occurs in this case.
The evident fix is:

if (n > count - pos) {
n = count - pos;

Here is the minimized test demonstrating the bug:
    

----- test23.java ---------------------------------------
import java.io.*;

public class test23 {

   public static void main( String[] argv ) {
     StringBufferInputStream is = new StringBufferInputStream("0123456789");
     is.skip(3); //make pos =2
      // 7 bytes remained!
     System.out.println("Here must be 7: "+is.skip(Long.MAX_VALUE));
   }
}

----- The output of the test: -------------------------

$JAVA test23
Here must be 7: 9223372036854775807

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