RFR: 8196882: VS2017 Hotspot Defined vsnprintf Function Causes C2084 Already Defined Compilation Error

[Marcus Larsson]

Hi Kim,


On 2018-02-25 23:37, Kim Barrett wrote:
>> On Feb 22, 2018, at 8:29 AM, Thomas Stüfe <thomas.stuefe at gmail.com> wrote:
>> Just to voice my preference on this, I am okay with either version (c99 and returning -1 on truncation) but would prefer having only one global function, not two. Especially not a function which exists for the sole purpose of another component.
>>
>> @Kim: thanks for taking my suggestions. I'll take another look when you post a new webrev.
>>
>> Best Regards, Thomas
> Based on discussion, I've changed the new os::vsnprintf and
> os::snprintf to conform to C99.  For POSIX platforms, this just calls
> ::vsnprintf.  For Windows, conditionalized to call ::vsnprintf for
> VS2015 and later; earlier versions emulate that behavior using
> _vsnprintf and _vscprintf.  Improved new gtest-based tests, so we
> should quickly find out if some platform doesn't behave as expected.
>
> I've also removed the now redundant os::log_vsnprintf, and changed
> callers to use os::vsnprintf.
>
> Also changed jio_vsnprintf to use os::vsnprintf, reverting some of the
> ealier change.
>
> An interesting point, which I'm not intending to address with this
> change, is that vsnprintf only returns a negative value to indicate an
> encoding error.  I think encoding errors can only arise when dealing
> with wide characters or strings, e.g. when processing a %lc or %ls
> directive.  I don't think HotSpot code would ever use either of those,
> though perhaps call to jio_vsnprintf from outside HotSpot could.
> Maybe the function we want for internal HotSpot use should return
> unsigned (and internally error on an encoding error), as that might
> simplify usage.
>
> Updated webrevs:
> full: http://cr.openjdk.java.net/~kbarrett/8196882/open.02/
> incr: http://cr.openjdk.java.net/~kbarrett/8196882/open.02.inc/
>
> (Ignore open.01*; open.02.inc is delat from open.00.)

Looks good! Many thanks for fixing.

Marcus