Review JDK-8010837 - TEST_BUG: java/io/FileInputStream/LargeFileAvailable.java fails intermittently

[Dan Xu]

I see. So we will need clarify the spec and make corresponding changes. 
I think as long as we don't trigger exceptions and just return 0 will be 
backward-compatible, right?

-Dan


On 03/30/2013 10:23 AM, Alan Bateman wrote:
> On 26/03/2013 19:29, Dan Xu wrote:
>> Hi All,
>>
>> In the old JVM function, os::available, it could return negative 
>> values because lseek() allows the file offset to be set beyond the 
>> end of a file. In the previous change of removing jvm functions, I 
>> wasn't aware of that and regardnegative values as invalid and return 
>> 0, which causes this test failed if it handles negative values. This 
>> fixaddressedthis problem and added a new testcase to ensure the 
>> correctbehaviour when available() encounters negative values.
>>
>> Webrev: http://cr.openjdk.java.net/~dxu/8010837/webrev/
>>
>> Thanks,
>>
>> -Dan
> I see this has already been pushed but I think it requires further 
> discussion. I think it would be surprising if available() returned 
> anything other than 0 for this case. You can't read a negative number 
> of bytes, and with a normal InputStream then a negative skip is a 
> no-op. So minimally we will need a spec clarification to make it clear 
> how available() should behave when the file position is beyond the 
> current file size. I just checked Channels.newInputStream and it does 
> return 0 for this case. I also checked the FileInputStream.skip method 
> and it seems to differ from its spec in that it allows a negative skip 
> if the resulting file position is >= 0. I'll create bugs for these 
> issues (assuming there aren't existing bugs on these topics area).
>
> -Alan.