.\" $NetBSD: getgrouplist.3,v 1.7 2001/09/16 02:30:24 wiz Exp $
.\" Copyright (c) 1991, 1993
.\" The Regents of the University of California. All rights reserved.
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\" notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice, this list of conditions and the following disclaimer in the
.\" documentation and/or other materials provided with the distribution.
.\" 3. All advertising materials mentioning features or use of this software
.\" must display the following acknowledgement:
.\" This product includes software developed by the University of
.\" California, Berkeley and its contributors.
.\" 4. Neither the name of the University nor the names of its contributors
.\" may be used to endorse or promote products derived from this software
.\" without specific prior written permission.
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\" @(#)getgrouplist.3 8.1 (Berkeley) 6/9/93
.Dd April 25, 1999
.Dt GETGROUPLIST 3
.Nd calculate group access list
.Fd #include <unistd.h>
.Fn getgrouplist "const char *name" "gid_t basegid" "gid_t *groups" "int *ngroups"
function reads through the group database and calculates
the group access list for the user specified in
.Fa name .
is automatically included in the groups list.
Typically this value is given as
the group number from the password database.
The resulting group list is returned in the integer array pointed to by
.Fa groups .
The caller specifies the size of the
array in the integer pointed to by
.Fa ngroups ;
the actual number of groups found is returned in
.Fa ngroups .
Duplicate group ids will be suppressed from the result.
.Sh RETURN VALUES
returns \-1 if the size of the group list is too small to
hold all the user's groups.
Here, the group array will be filled with as many groups as will fit.
.Bl -tag -width /etc/group -compact
.It Pa /etc/group
group membership list
.Sh SEE ALSO
.Xr setgroups 2 ,
.Xr initgroups 3
function first appeared in
.Bx 4.4 .
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 .
In the case where the group array is too small and duplicate gids
have been suppressed, the returned
will be too large by a factor of the difference between the given
size and the number of matches.
This is not considered to be a major problem, since it's still going
to be a smaller figure than when duplicates were not suppressed.