GETGROUPS(2) |
FreeBSD System Calls Manual |
GETGROUPS(2) |
NAME
getgroups —
get group access list
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include < unistd.h>
int
getgroups( int gidsetlen, gid_t *gidset);
DESCRIPTION
The
getgroups() system call gets the current group access list of the user process and stores it in the array
gidset. The
gidsetlen argument indicates the number of entries that may be placed in
gidset. The
getgroups() system call returns the actual number of groups returned in
gidset. At least one and as many as {NGROUPS_MAX}+1 values may be returned. If
gidsetlen is zero,
getgroups() returns the number of supplementary group IDs associated with the calling process without modifying the array pointed to by
gidset.
The value of {NGROUPS_MAX} should be obtained using sysconf(3) to avoid hard-coding it into the executable.
RETURN VALUES
A successful call returns the number of groups in the group set. 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
getgroups() are:
-
[
EINVAL]
-
The argument
gidsetlen is smaller than the number of groups in the group set.
-
[
EFAULT]
-
The argument
gidset specifies an invalid address.
STANDARDS
The
getgroups() system call conforms to IEEE Std 1003.1-2008 (“POSIX.1”).
HISTORY
The
getgroups() system call appeared in
4.2BSD.