#!/usr/bin/perl
#
# Reads /etc/grouplist, in form
# group:description:owner:manager1,manager2,manager3:home-directory
# (as many or few managers as you like)
# Modifies /etc/grouplist by adding or removing managers &c,
# and /etc/group by adding or removing members.

# Copyright (C)1995-8 Ian Jackson <ijackson@chiark.greenend.org.uk>

# This 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.

# It 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.

sub usage {
    &unlock;
    &p_out;
    print(<<END) || die "groupmanage: write usage: $!\n";
groupmanage: $_[0]
  usage:
    groupmanage <groupname> [--info]
    groupmanage <groupname> <action> [<action> ...]
    groupmanage <groupname> --create [<action> <action> ...]
  actions:
       --clear
       --add <username> <username> ...
       --remove <username> <username> ...
       --manager-clear
       --manager-add <username> <username> ...
       --manager-remove <username> <username> ...
       --title <string>
       --owner <username>  [root only]
END
    exit(1);
}

@ARGV || &usage('too few arguments');

if ($>) {
    exec 'userv','root','groupmanage',@ARGV;
    &quit("unable to execute userv to gain root privilege: $!");
}

chdir("/etc") || die "groupmanage: chdir /etc: $!\n";

$groupname= shift(@ARGV);
$groupname =~ y/\n//d;

$groupname =~ m/^\w[-0-9A-Za-z]*$/ ||
    &quit("first argument is invalid - must be group name");

@ARGV || push(@ARGV,'--info');

if ($ARGV[0] eq '--info') {
    @ARGV == 1 || &usage('no arguments allowed after --info');
    &p_out;
    &load;
    &checkexists;
    &display;
    &p_out;
    exit(0);
}

$callinguser= exists $ENV{'USERV_UID'} ? $ENV{'USERV_UID'} : $<;

%opt= ('user-create','0',
       'user-create-minunameu','5',
       'user-create-min','10000',
       'user-create-max','19999',
       'user-create-nameintitle','0',
       'user-create-maxperu','5');
%ovalid=  ('user-create','boolean',
           'user-create-minunameu','number',
           'user-create-min','number',
           'user-create-max','number',
           'user-create-nameintitle','boolean',
           'user-create-maxperu','number');

sub ov_boolean {
    $cov= $_ eq 'yes' ? 1 :
          $_ eq 'no' ? 0 :
          &quit("groupmanage.conf:$.: bad boolean value");
}

sub ov_number {
    m/^[0-9]{1,10}$/ || &quit("groupmanage.conf:$.: bad numerical value");
}

open(GMC,"groupmanage.conf") || &quit("read groupmanage.conf: $!");
while (<GMC>) {
    next if m/^\#/ || !m/\S/;
    s/\s*\n$//;
    s/^\s*([-0-9a-z]+)\s*// || &quit("groupmanage.conf:$.: bad option format");
    $co= $1;
    defined($opt{$co}) || &quit("groupmanage.conf:$.: unknown option $co");
    $cov= $_;
    $ovf= 'ov_'.$ovalid{$co};
    &$ovf;
    $opt{$co}= $cov;
}
close(GMC);

sub naming {
    $callinguser || return;
    &p_out;
    print(STDERR <<END) || &quit("write err re name: $!");
groupmanage: groups you create must be named after you ...
    <usernamepart>-<identifier>
 You must quote at least $opt{'user-create-minunameu'} chars of your username $createby
 (or all of it if it is shorter).
END
    exit(1);
}

if ($ARGV[0] eq '--create') {
    $opt{'user-create'} || !$callinguser ||
        &quit("group creation by users disabled by administrator");
    length($groupname) <= 8 || &quit("group names must be 8 chars or fewer");
    $groupname =~ m/^([-0-9A-Za-z]+)-([0-9a-z]+)$/ || &naming;
    $upart= $1;
    $idpart= $2;
    $!=0; (@pw= getpwuid($callinguser))
	|| &quit("cannot get your passwd entry: $!");
    $createby= $pw[0];
    $upart eq $createby ||
        (length($upart) >= $opt{'user-create-minunameu'} &&
         substr($createby,0,length($upart)) eq $upart)
            || &naming;
    $create= 1;
    shift(@ARGV);
}

&lock;
&load;

if ($create) {
    $bythisowner < $opt{'user-create-maxperu'} ||
        &quit("you already have $bythisowner group(s)");
    $groupfileix==-1 || &quit("group already exists, cannot create it");
    $grouplistix==-1 || &quit("group is already in grouplist, cannot create it");
    for ($gid= $opt{'user-create-min'};
         $gid < $opt{'user-create-max'} && defined(getgrgid($gid));
         $gid++) { }
    $gid <= $opt{'user-create-max'} || &quit("out of gids to use, contact admin");
    $password=''; @members=($createby);
    $description= "${createby}'s -- user-defined, no title";
    $owner= $createby; @managers=(); @members= ($createby);
    $groupfileix=$#groupfile+1;
    $grouplistix=$#grouplist+1;
    &p("created group $groupname");
} else {
    &checkexists;
    &p("modifying group $groupname");
}

&weare($owner) || grep(&weare($_),@managers) || !$callinguser ||
    &quit("you may not manage $groupname");

$action= 'none';
while (@ARGV) {
    $_= shift(@ARGV);
    if (m/^--(add|remove)$/) {
        $action= $1; $clist= 'members'; $what= 'member';
    } elsif (m/^--owner$/) {
	!$callinguser || &quit("only root may change owner");
	@ARGV || &usage("no username owner after --owner");
	$owner= shift(@ARGV);
	&p("owner set to $owner");
    } elsif (m/^--manager-(add|remove)$/) {
        $action= $1; $clist= 'managers'; $what= 'manager';
    } elsif (m/^--clear$/) {
        &p('cleared list of members');
        @members=(); $action='none'; $memc++;
    } elsif (m/^--manager-clear$/) {
        &p('cleared list of managers');
        @managers=(); $action='none';
    } elsif (m/^--title$/) {
        &weare($owner) || !$callinguser ||
	    &quit("only group's owner ($owner) may change title");
        @ARGV || &usage("no title after --title");
        $_= shift(@ARGV); y/\020-\176//cd; y/:\\//d;
        if ($opt{'user-create-nameintitle'} &&
            $gid >= $opt{'user-create-min'} && $gid <= $opt{'user-create-max'}) {
            $_= "${owner}'s -- $_";
        }
        $description= $_;
        &p("title set to $description");
    } elsif (m/^-/) {
        &usage("unknown option $_");
    } elsif (m/^\w[-0-9A-Za-z]*$/) {
        y/\n//d;
        $chgu=$_;
        (@pw= getpwnam($chgu)) || &quit("username $chgu does not exist");
        eval "\@l = \@$clist; 1" || &quit("internal error: $@");
        $already= grep($_ eq $chgu, @l);
        if ($action eq 'add') {
            if ($already) {
                &p("$chgu already $what");
            } else {
                &p("added $what $chgu");
                push(@l,$chgu);
                $memc+= ($clist eq 'members');
            }
        } elsif ($action eq 'remove') {
            if ($already) {
                &p("removed $what $chgu");
                @l= grep($_ ne $chgu, @l);
                $memc+= ($clist eq 'members');
            } else {
                &p("$chgu is already not $what");
            }
        } else {
            &usage("username found but no action to take for them");
        }
        eval "\@$clist = \@l; 1" || &quit("internal error: $@");
    } else {
        &usage("bad username or option $_");
    }
}
&p("nb: a change to group membership only takes effect at the user's next login")
    if $memc;
$groupfile[$groupfileix]=
    "$groupname:$password:$gid:".join(',',@members)."\n";
$grouplist[$grouplistix]=
    "$groupname:$description:$owner:".join(',',@managers).":$homedir\n";
&save('group',@groupfile);
&save('grouplist',@grouplist);
unlink('gtmp') || &quit("unlock group (remove gtmp): $!");
&p_out;
exit(0);

sub load {
    open(GF,"< group") || &quit("read group: $!");
    @groupfile=<GF>; close(GF);
    $groupfileix=-1;
    for ($i=0; $i<=$#groupfile; $i++) {
        $_= $groupfile[$i]; s/\n$//;
        next if m/^\#/;
        m/^(\w[-0-9A-Za-z]*):([^:]*):(\d+):([-0-9A-Za-z,]*)$/ ||
            &quit("bad entry in group: $_");
        $gname2gid{$1}=$3;
        next unless $1 eq $groupname;
        $groupfileix<0 || &quit("duplicate entries in group");
        $groupfileix= $i;
        $password= $2;
        $gid= $3;
        @members= split(/,/,$4);
    }
    open(GL,"< grouplist") || &quit("read grouplist: $!");
    @grouplist=<GL>; close(GL);
    $grouplistix=-1;
    for ($i=0; $i<=$#grouplist; $i++) {
        $_= $grouplist[$i]; s/\n$//;
        next if m/^\#/;
        m/^(\w[-0-9A-Za-z]*):([^:]*):(\w[-0-9A-Za-z]*):([-0-9A-Za-z,]*):([^:]*)$/ ||
            &quit("bad entry in grouplist: $_");
        $bythisowner++ if ($create && $3 eq $createby &&
                           $gname2gid{$1} >= $opt{'user-create-min'} &&
                           $gname2gid{$1} <= $opt{'user-create-max'});
        next unless $1 eq $groupname;
        $grouplistix<0 || &quit("duplicate entries in grouplist");
        $grouplistix= $i;
        $description= $2;
        $owner= $3;
        $homedir= $5;
        @managers= split(/,/,$4);
    }
}

sub checkexists {
    $grouplistix>=0 || &quit("no entry in grouplist for $groupname");
    $groupfileix>=0 || &quit("no entry in group for $groupname");
}

sub weare {
    return 0 if $_[0] eq '';
    @pw= getpwnam($_[0]);
    return @pw && $pw[2] == $callinguser ? 1 : 0;
}

sub save {
    $filename= shift(@_);
    unlink("$filename~");
    open(DUMP,"> $filename.new") || &quit("create new $filename: $!");
    print(DUMP @_) || &quit("write new $filename: $!");
    close(DUMP) || &quit("close new $filename: $!");
    link("$filename","$filename~") || &quit("create backup $filename: $!");
    rename("$filename.new","$filename") || &quit("install new $filename: $!");
}

sub quit {
    &unlock;
    &p_out;
    die "groupmanage: @_\n";
}

sub lock {
    link('group','gtmp') || &quit("create gtmp: $!");
    $locked++;
}

sub unlock {
    return unless $locked;
    $locked--;
    unlink('gtmp') || warn("unlock group file (remove gtmp): $!\n");
}

sub display {
    print(<<END) || &quit("write to stdout: $!\n");
group       $groupname
gid         $gid
description $description
owner       $owner
managers    @managers
members     @members
homedir     $homedir
END
}

sub p_out {
    print(STDOUT "$stdout_string") || &quit("write to stdout: $!\n");
    $stdout_string= '';
}

sub p {
    $stdout_string.= $_[0]."\n";
}