NetBSD/lib/libc/gen/getgrouplist.3

.\"	$NetBSD: getgrouplist.3,v 1.8 2002/02/07 07:00:12 ross Exp $
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.\"     @(#)getgrouplist.3	8.1 (Berkeley) 6/9/93
.\"
.Dd April 25, 1999
.Dt GETGROUPLIST 3
.Os
.Sh NAME
.Nm getgrouplist
.Nd calculate group access list
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.Fd #include \*[Lt]unistd.h\*[Gt]
.Ft int
.Fn getgrouplist "const char *name" "gid_t basegid" "gid_t *groups" "int *ngroups"
.Sh DESCRIPTION
The
.Fn getgrouplist
function reads through the group database and calculates
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 .
The caller specifies the size of the
.Fa groups
array in the integer pointed to by
.Fa ngroups ;
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
function
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.
.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
.Sh HISTORY
The
.Fn getgrouplist
function first appeared in
.Bx 4.4 .
.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 .
.Pp
In the case where the group array is too small and duplicate gids
have been suppressed, the returned
.Fa ngroups
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.