.\"	$NetBSD: getgrouplist.3,v 1.15 2017/10/24 18:54:03 abhinav Exp $
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.\"     @(#)getgrouplist.3	8.1 (Berkeley) 6/9/93
.\"
.Dd January 6, 2005
.Dt GETGROUPLIST 3
.Os
.Sh NAME
.Nm getgrouplist ,
.Nm getgroupmembership
.Nd calculate group access list
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In unistd.h
.Ft int
.Fn getgrouplist "const char *name" "gid_t basegid" "gid_t *groups" "int *ngroups"
.Ft int
.Fn getgroupmembership "const char *name" "gid_t basegid" "gid_t *groups" "int maxgrp" "int *ngroups"
.Sh DESCRIPTION
The
.Fn getgrouplist
and
.Fn getgroupmembership
functions read through the group database and calculate
the group access list for the user specified in
.Fa name .
The
.Fa basegid
is automatically included in the groups list.
Typically this value is given as
the group number from the password database.
.Pp
The resulting group list is returned in the integer array pointed to by
.Fa groups .
.Pp
For
.Fn getgrouplist ,
the caller specifies the size of the
.Fa groups
array in the integer pointed to by
.Fa ngroups .
.Pp
For
.Fn getgroupmembership ,
the caller specifies the size of the
.Fa groups
array in
.Fa maxgrp .
.Pp
The actual number of groups found is returned in
.Fa ngroups .
.Pp
Duplicate group ids will be suppressed from the result.
.Sh RETURN VALUES
The
.Fn getgrouplist
and
.Fn getgroupmembership
functions
return 0 if successful, and
return \-1 if the size of the group list is too small to
hold all the user's groups.
In the latter case, the
.Fa groups
array will be filled with as many groups as will fit and
.Fa ngroups
will contain the total number of groups found.
.Sh FILES
.Bl -tag -width /etc/group -compact
.It Pa /etc/group
group membership list
.El
.Sh SEE ALSO
.Xr setgroups 2 ,
.Xr initgroups 3 ,
.Xr group 5
.Sh HISTORY
The
.Fn getgrouplist
function first appeared in
.Bx 4.4 .
The
.Fn getgroupmembership
function first appeared in
.Nx 3.0
to address an API deficiency in
.Fn getgrouplist .
.Sh BUGS
The
.Fn getgrouplist
function
uses the routines based on
.Xr getgrent 3 .
If the invoking program uses any of these routines,
the group structure will
be overwritten in the call to
.Fn getgrouplist .