#!/usr/bin/perl
#
# Add user to group and preserve existing groups
#
# smb_addtogroup username groupname
#
# Michiel Broek <mbroek@mbse.eu>
#
# This script is free software; you can redistribute it and/or modify it
# under the terms of the GNU General Public License as published by the
# Free Software Foundation; either version 2, or (at your option) any
# later version.
#
# This script is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
# General Public License for more details.
# 
# You should have received a copy of the GNU General Public License
# along with MB BBS; see the file COPYING.  If not, write to the Free
# Software Foundation, 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
#

$username = $ARGV[0];
$groupname = $ARGV[1];
$group_exist = 0;
$group_already = 0;

if ($#ARGV ne 1)
{
  print "Usage: $0 username groupname\n";
  exit -1;
}

# Read existing groups and do some checks
#
open(GLIST, "/etc/group") || die "open /etc/group failed! $!\n";
while (<GLIST>) {
  chop ($_);
  split(':', $_);
  # Check if the group exists
  if ($_[0] eq  $groupname)
  {
    $group_exist = 1;
  }
  next unless $_[3];
  if ( $_[3] =~ /$username(.*)/i )
  {
    push(@groups, $_[0]);
    if ($_[0] eq $groupname)
    {
       $group_already = 1;
    }
  }
}
close (GLIST);

if ($group_exist == 0)
{
  print "group '$groupname' doesn't exist\n";
  exit -1;
}

if ($group_already == 1)
{
  print "Already in group '$groupname'\n";
  exit -1;
}

# Build list of groups to set
$setgroups = $groupname;
foreach (@groups)
{
  $setgroups = $setgroups.",".$_;
}

system ("/usr/sbin/usermod -G '$setgroups' $username");