what is _XOPEN_SOURCE=500 needed for?

[Matthieu Herrb]

Daniel Stone wrote:
> On Fri, May 27, 2005 at 11:50:47PM -0700, Josh Triplett wrote:
> 
>>The optimal solution to this problem would probably be to rewrite the
>>macros in Xpoll.h to use the portable macros FD_SET, FD_CLEAR, FD_ISSET,
>>and FD_ZERO.  Attempting to look at the insides of struct fd_set, and in
>>particular assuming that it has a member fds_bits, is non-portable;
>>defining _*_SOURCE just lets it use this non-portable behavior on some
>>additional platforms.
> 
> 
> Alan, Mathieu, Eric A, others: is this portable to your OS?

Yes. As far as I can tell *BSD, Darwin and Solaris all have them.

-- 
Matthieu Herrb