RFR(XS): 8198906: JDK-8196882 breaks VS2013 Win32 builds

[Thomas Stüfe]

On Fri, Mar 2, 2018 at 2:45 AM, David Holmes <david.holmes at oracle.com>
wrote:

> On 2/03/2018 6:29 AM, Kim Barrett wrote:
>
>> Please review this change to fix a build failure on Win32 when using
>> VS2013 (and likely earlier).  In os::vsnprintf, cast the int result to
>> size_t for comparison with the buffer size, after having verified the
>> result is non-negative.
>>
>
> Seems harmless.
>
> I'm not sure why this failure doesn't occur with VS2013 Win64 builds.
>>
>
> I'm a bit confused how a function that takes a parameter indicating the
> number of characters to write, and then returns the number of characters
> written, can use two different, and potentially different sized, types! On
> 64-bit size_t would be 64-bit but int is 32-bit, so how can you possibly
> always return the correct count? Granted it may not be a practical concern,
> but from a typing perspective this seems seriously messed up. Further
> size_t is unsigned so has twice the range of int - so even on 32-bit this
> doesn't make sense.
>
> Am I missing something?
>

One problem is that the result type must be signed to be able to represent
error cases as well. So even if it were ssize_t it would not cover the
whole range of the input size_t.

Thanks,
> David
>
>
> CR:
>> https://bugs.openjdk.java.net/browse/JDK-8198906
>>
>> Webrev:
>> http://cr.openjdk.java.net/~kbarrett/8198906/open.00/
>>
>> Testing:
>> VS2013 Win64 still builds.  I don't have access to Win32, but the
>> change is pretty simple.
>>
>>
>>