GETGROUPS(2)
NAME
getgroups − get group access list
USAGE
#include <sys/param.h>
ngroups = getgroups(gidsetlen, gidset)
int ngroups, gidsetlen, *gidset;
DESCRIPTION
Getgroups obtains the current group access list of the user process and stores it in the array gidset. The parameter gidsetlen indicates the number of entries that may be placed in gidset. Getgroups returns the actual number of groups returned in gidset. No more than NGROUPS, as defined in <sys/param.h>, will ever be returned.
RETURN VALUE
A value of zero indicates that the call succeeded, and that the number of elements of gidset and the set itself were returned. A value of −1 indicates that an error occurred, and the error code is stored in the global variable errno.
ERRORS
The possible errors for getgroup are:
[EINVAL] The argument gidsetlen is smaller than the number of groups in the group set.
[EFAULT] The arguments ngroups or gidset specify invalid addresses.