getgroups
=========

POSIX specification:
 http://www.opengroup.org/onlinepubs/9699919799/functions/getgroups.html

Gnulib module: getgroups

Portability problems fixed by Gnulib:

  * This function is missing on some platforms: mingw, MSVC 9.

  * On some platforms, this function fails to reject a negative count, even though that is less than the size that would be returned: FreeBSD 7.2.

  * On Ultrix 4.3, getgroups (0, NULL) always fails.  See macro AC_FUNC_GETGROUPS.

  * On very old systems, this function operated on an array of int, even though that was a different size than an array of gid_t.

Portability problems not fixed by Gnulib:

  * It is unspecified whether the effective group id will be included in the returned list, nor whether the list will be sorted in any particular order.  For that matter, some platforms include the effective group id twice, if it is also a member of the current supplemental group ids.