10.411 getgroups
POSIX specification:
https://pubs.opengroup.org/onlinepubs/9699919799/functions/getgroups.html
Gnulib module: getgroups
Portability problems fixed by Gnulib:
- This function is missing on some platforms:
mingw, MSVC 14.
- On some platforms, this function fails to reject a negative count,
even though that is less than the size that would be returned:
macOS 14, FreeBSD 13.0.
- On NeXTstep 3.2,
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:
- This function is unsafe to call between
fork and exec if
the parent process is multi-threaded.
- 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.
The Gnulib module mgetgroups provides a similar API.