Re: RFR 9: 8155808: Process.getInputStream().skip() method is faulty

[Roger Riggs]

Hi Pavel,

On 6/17/2016 5:03 AM, Pavel Rappo wrote:
Hi Roger,
Do we need PipeInputStream to be a java.io.FileInputStream? Can we get away with
it being an InputStream? If so, then we could use a simple delegation which
would allow us to avoid code duplication (the implementation of `skip` is almost
identical to one in InputStream):
Subclassing is the normal (one) way to override/augment behavior of an 
existing class.
And I was looking for a minimal change since there have been many issues 
in this area.
Also, I avoided the extra object and performance overhead of delegation 
by extending FIS.

Roger

     private static class PipeInputStream extends InputStream {

         private final FileInputStream fis;

         PipeInputStream(FileDescriptor fd) {
             fis = new FileInputStream(fd);
         }

         @Override
         public int read() throws IOException {
             return fis.read();
         }

         @Override
         public int read(byte[] b) throws IOException {
             return fis.read(b);
         }

         @Override
         public int read(byte[] b, int off, int len) throws IOException {
             return fis.read(b, off, len);
         }

         @Override
         public void close() throws IOException {
             fis.close();
         }

         @Override
         public int available() throws IOException {
             return fis.available();
         }
     }

Thanks,
-Pavel

On 13 Jun 2016, at 16:06, Roger Riggs <roger.ri...@oracle.com> wrote:

A latent issue with Process InputStreams support for the skip method was 
reported[1].

Though the InputStream returned is a BufferedInputStream, in some cases,
the skip method calls FileInputStream.seek on the pipe containing output
from the process but the pipes do not support seek.  The proposed fix is to 
override
the skip method to implement skip as reading the bytes instead of invoking seek.

Please review and comment:

Webrev:

http://cr.openjdk.java.net/~rriggs/webrev-skip-8155808/index.html

Issue:

  [1] https://bugs.openjdk.java.net/browse/JDK-8155808

Thanks, Roger