6516099: InputStream.skipFully(int k) to skip exactly k bytes

[Brent Christian]

Hi, Brian

  562     public void skipNBytes(long n) throws IOException {
  563         if (n > 0 && skip(n) != n) {
  564             throw new EOFException("End of stream before enough 
bytes skipped");
  565         }
  566     }

If an overrided skip() method were to skip < n bytes but not yet be at 
EOF, which I think the skip() spec allows, then wouldn't skipNBytes() 
throw an EOFException ?

-Brent

On 10/16/18 1:52 PM, Brian Burkhalter wrote:
> Hi Roger,
> 
> Updated patch: http://cr.openjdk.java.net/~bpb/6516099/webrev.01/
> 
> Thanks,
> 
> Brian
> 
>> On Oct 16, 2018, at 1:06 PM, Brian Burkhalter <brian.burkhalter at oracle.com> wrote:
>>
>>> On Oct 16, 2018, at 12:53 PM, Roger Riggs <Roger.Riggs at oracle.com <mailto:Roger.Riggs at oracle.com>> wrote:
>>>
>>> InputStream.java:
>>>
>>> 584:  Is there really a case where line 585 would throw the exception?
>>>
>>>   skip(n, true) != n
>>>
>>> With the 2nd argument = true, it will either skip the bytes or throw.
>>> I think you can just call:  "skip(n, true);
>>
>> I think you are correct.
>>
>>> Given subclasses of InputStream that might override skip(n) with a more efficient mechanism
>>> would it make sense to implement skipNBytes in terms of skip(n)?
>>> As is, it always uses read() to skip the bytes, which might not be as efficient as possible
>>> on some streams (for example a very large file) where a seek could be used.
>>
>> That’s a good point. I had some trepidation about the vague wording of skip(n) in terms of how many bytes it actually reads.
>>
>>> test/jdk/java/io/InputStream/Skip.java:
>>>
>>> There is a lot of whitespace in this test, spaces before "," and extra blank lines.
>>
>> Yes it is rather ugly. I chose to leave it as is for initial clarity intending to clean it up later.
>>
>>> 97: "possible result" - does that occur in the tests?  The "possible" is a bit ambiguous especially given the very narrow test case. It would be useful to include the message from the exception.
>>
>> Copy-paste garbage. I’ll update it to include the message.
>