#!/bin/perl

#
# GRED - GRoup EDitor
#
# By: Theo Van Dinter, 95/11/12
#
# This program was written using parts of WPI's C version of the gred program.
# Unfortunately, the C program wouldn't compile on my system due to missing
# routines and such (and various minor errors...), so I rewrote it in Perl...
# It's designed so that users can create groups for themselves, and
# administrate them.  This is useful for project groups that need to work
# together, etc...
#

require "neslib.pl";

$absolute_low=101;		# Don't let Root do stupid things to groups w/
				# GID's lower than this.
$group_low=10000;		# Lowest GID that users can deal with
$group_high=11000;		# Highest GID that users can deal with
$group_file="/etc/group";	# The file with the groups in it (/etc/group)
$group_back="/etc/group~";	# Backup file
$group_lock="/etc/gtmp";	# Lock File for this program
$my_name=getlogin||(getpwuid($<))[0]||die "Can't locate who you are!";

if ( !(-e $group_lock) )	# If the Lock file doesn't exist (a good thing)
{
    open(F,"<$group_file");	# Open and read the group file
    foreach(<F>)
    {
	s/^\s+//;
	s/\s+$//;
	($name,$data)=split(/:/,$_,2);
	$data=~/^.*:(\d+):/;
	$gid=$1;
	$groups{$name}=$data;	# Store it all in a hash array
    }
    close(F);
}
else
{
    die "Can't open group file, it's locked!";
}

for($i=$group_low;$i<=$group_high;$i++)	# Make the holes array
{
    $crap{$i}=1;
}
foreach(sort values(%groups))
{
    s/^.*:(\d+):.+/$1/;
    delete($crap{$_});
}

foreach(sort keys(%crap))
{
    push(@holes,$_);
}
undef(%crap);

if ( !open(F,">$group_lock") )	# Create the lock file
{
    die "Can't create the lock file.\n";
}
print F "\n";
close(F);

$removal_message=<<EOM;

Remember that you should change the group of any files that remain or
the next person to acquire this group number will have group access to
those files.
EOM

$help=<<EOM;			# The help menu
Group Edit program (gred):

This program lets you change your groups or define new ones.

The commands are:

a 	add a user to the selected group.
d 	delete a user from the selected group.
g 	give group control to user.
h or ?	display this message.
i       display information about the current group.
l       display groups of which you are a part.
q	exit and apply the changes.
r	remove the selected group.
x	exit with no changes.
/	select a group.
EOM

if ( $my_name eq "root" )	# I'm the super-user, give me more access!
{
    $group_low=0;
    $group_high=65536;
}

print "\n";
&print_groups;
while(!$abort && !$quit)	# Menu Loop
{
    print "\n";
    print "[",&pbold,"$selgroup",&poff,"] " if ( $selgroup ne "" );
    print "gred > ";
    ($com)=&getline;		# Get a commandline
    print "\n";
    $ccom="";
    $ccom2="";
    $com=~y/A-Z/a-z/;
    $com=~/^(.)(.*)/;
    $ccom=$1;
    $ccom2=$2;
    $ccom2=~s/^\s+//;
    $ccom2=~s/\s+$//;
    if ( $ccom eq "?" || $ccom eq "h" )	# Help Me! (Menu)
    {
	print "$help";
    }
    elsif ( $ccom eq "i" )	# Group Information
    {
	if ( $selgroup eq "" )
	{
	    print "You haven't selected a group yet!\n";
	}
	else
	{
	    print "Group Name: $selgroup\n";
	    @test=split(/:/,$groups{$selgroup});
	    for($i=0;$i<=$#test;$i++)
	    {
		print "Password  : $test[$i]\n" if ($i==0 && $test[$i] ne "");
		print "GID       : $test[$i]\n" if ( $i==1 );
		if ( $i==2 )
		{
		    print "Members   :";
		    @test2=split(/,/,$test[$i]);
		    foreach(@test2)
		    {
			($n,$p,$u,$g,$q,$c,$g,$d,$s)=getpwnam($_);
			($a)=split(/,/,$g);
			if ( $_ ne $test2[0] )
			{
			    print "\t   ";
			}
			if ( $_ ne $test2[0] )
                        {
			    print " $a ($_)";
			}
			else
			{
			    print " ",&preverse,"$a ($_)",&poff;
			}
			print "\n";
		    }
		}
	    }
	}
    }		
    elsif ( $ccom eq "l" )	# List Groups
    {
	&print_groups;
    }
    elsif ( $ccom eq "a" )	# Add a User
    {
	if ( $selgroup eq "" )
	{
	    print "No group selected.\n";
	}
	else
	{
	    ($pass,$gid,$members)=split(/:/,$groups{$selgroup});
	    if ( !($members=~/^$my_name/i) )
	    {
		print "You aren't the owner of $selgroup!\n";
	    }
	    else
	    {
		if ( $ccom2 eq "" )
                {
		 print "User to add: ";
		 ($user)=&getline;
		 print "\n";
                }
                else
                {
                 $user=$ccom2;
                }
		$user=~y/A-Z/a-z/;
		if ( !getpwnam($user) )	# User not in the passwd file!
		{
		    print "$user doesn't exist!\n";
		}
		elsif ( &member($user,$groups{$selgroup}) )
		{
		    print "$user is already a member of this group.\n";
		}
		else
		{
		    $groups{$selgroup}.=",$user";
		    print "$user added to group.\n";
		    $change=1;
		}
	    }
	}
    }
    elsif ( $ccom eq "d" )	# Remove a User
    {
	if ( $selgroup eq "" )
	{
	    print "No group selected.\n";
	}
	else
	{
	    ($pass,$gid,$members)=split(/:/,$groups{$selgroup});
	    if ( !($members=~/^$my_name/i) )
	    {
		print "You aren't the owner of $selgroup!\n";
	    }
	    else
	    {
	        if ( $ccom2 eq "" )
                {
 		 print "User to remove: ";
		 ($user)=&getline;
		 print "\n";
                }
                else
                {
                 $user=$ccom2;
                }
		$user=~y/A-Z/a-z/;
		$l=&member($user,$members);
		if ( !$l )	# If the user isn't a member ...
		{
		    print "$user doesn't have access to this group!\n";
		}
		elsif ( $user eq $my_name ) # Trying to remove yourself
		{
		    print "You can't remove yourself with this command.\n";
		}
		else
		{
		    $groups{$selgroup}=~s/,$user//;
		    $change=1;
                    print "$used removed from group.\n";
		}
	    }
	}
    }
    elsif ( $ccom eq "g" )	# Give another User control of the group
    {
	if ( $selgroup eq "" )
	{
	    print "No group selected.\n";
	}
	else
	{
	    ($pass,$gid,$members)=split(/:/,$groups{$selgroup});
	    if ( &member($my_name,$members)!=1 )
	    {
		print "You aren't the owner of $selgroup!\n";
	    }
	    elsif ( $gid < $absolute_low )
	    {
		print "GID Access is restricted below $absolute_low.\n";
	    }
	    else
	    {
	        if ( $ccom2 eq "" )
                {
		 print "User for control: ";
		 ($user)=&getline;
		 print "\n";
                }
                else
                {
                 $user=$ccom2;
                }
		$user=~y/A-Z/a-z/;

		if ( !&member($user,$members) )	# User isn't a group member
		{
		    print "$user doesn't have access to this group!\n";
		}
		elsif ( $user eq $my_name ) # User is in control.
		{
		    print "You already have control of this group.\n";
		}
		else		# Change owner of group.
		{
		    @test=split(/,/,$members);
		    $test[0]=$user;
		    for($i=1;$i<=$#test;$i++)
		    {
			if ( $test[$i] eq $user )
			{
			    $test[$i]=$my_name;
			}
		    }
		    $members=join(',',@test);
		    $groups{$selgroup}="$pass:$gid:$members";
		    print "Control of group given to $user.\n";
		    $change=1;
		}
	    }
	}
    }
    elsif ( $ccom eq "/" )	# Select a Group
    {
        if ( $ccom2 eq "" )
        {
	 print "Which Group: ";
	 ($user)=&getline;
	 print "\n";
        }
        else
        {
         $user=$ccom2;
        }
	if ( !defined($groups{$user}) )
	{
	    print "Group $user doesn't exist";
	    if ( $user=~/^\W/ )
	    {
             print ", and the group name must start with an alphabetical char";
	    }
	    elsif ( $user=~/[^0-9a-zA-Z_]/ )
            {
             print ", and the group can only have alphanumeric characters";
            }
	    elsif ( length($user)>20 )
	    {
	     print ", and the group must be 20 characters or less";
	    }
	    elsif ( $#holes == -1 )
	    {
		print ", and there aren't any available GID's";
	    }
	    else
	    {
		print ", create (Y/n)? ";
		$test=&getline;
		$test=~y/NY/ny/;
		$test=~s/^(\w).*$/$1/;
		if ( $test eq "n" )
		{
		    print "\n",&pblink,"Aborted",&poff;
		}
		else
		{
		    print "\nCreating Group $user";
		    $holes[0]=":$holes[0]:$my_name";
		    $groups{$user}=$holes[0];
		    shift(@holes);
		    $selgroup=$user;
		}
	    }
	    print ".\n";
	}
	else
	{
	    ($pass,$gid,$members)=split(/:/,$groups{$user});
	    if ( !&member($my_name,$members) )
	    {
		print "You aren't a member of that group!\n";
	    }
	    elsif ( $gid>$group_high || $gid<$group_low )
            {
	        print "The specified group is outside of the possible range.\n";
            }
	    else
	    {
		print "Group $user selected.\n";
		$selgroup=$user;
	    }
	}
    }
    elsif ( $ccom eq "r" )	# Remove a Group
    {
	if ( $selgroup eq "" )
        {
            print "You haven't selected a group yet!\n";
        }
        else
        {
	 ($pass,$gid,$members)=split(/:/,$groups{$selgroup});
	 if ( &member($my_name,$members)!=1 )
	 {
	     print "You aren't the owner of that group!\n";
	 }
	 elsif ( $gid < $absolute_low )
	 {
	     print "GID Access is restricted below $absolute_low.\n";
	 }
	 else
	 {
	     print "Group $selgroup has been removed.\n";
	     delete($groups{$selgroup});
	     $selgroup="";
	     push(@holes,$gid);
	     @holes=sort @holes;
             $change=1;
	     if ( !$rmgrp )
	     {
		 print $removal_message;
	     }
	     $rmgrp=1;
	 }
        }
    }
    elsif ( $ccom eq "q" )	# Quit
    {
        $quit=1;
    }
    elsif ( $ccom eq "x" )	# Abort
    {
        $abort=1;
    }
    else
    {
        print "Type h for help.\n";
    }
}

if ( $abort )
{
    print "\t",&pblink,"Aborted!",&poff,"\n\n";
}
else
{
    if ( $change )		# Only output file if it's been changed.
    {
     system "/bin/mv","-f",$group_file,$group_back;
     open(F,">$group_file");
     foreach(sort theo1 keys(%groups))
     {
	 print F "$_:$groups{$_}\n";
     }
     print "New Group File Written.\n\n";
     close(F);
     system "/bin/chmod","u=rw,go=r",$group_file;
    }
    else
    {
     print "Group file hasn't changed, no saving is neccesary.\n\n";
    }
}
unlink($group_lock);
exit;

sub print_groups		# Loop to print out group involvment
{
    local($l,$l2,$te);
    $l2=0;
    foreach(sort theo1 keys(%groups))
    {
	$groups{$_}=~/:(\d+):/;
	$te=$1;
	next if ( $te>$group_high || $te<$group_low );
	$l=&member($my_name,$groups{$_});
	if ( $l )
	{
	    $l2++;
	    if ( $l==1 )
	    {
		print "You own group $_\n";
	    }
	    else
	    {
		print "You are a member of group $_\n";
	    }
	}
    }
    print "You aren't a member of any groups.\n" if ( !$l2 );
}

sub theo1			# Sort by GID.
{
    local($t1,$t2);
    $groups{$a}=~/:(.+):/;
    $t1=$1;
    $groups{$b}=~/:(.+):/;
    $t2=$1;
    $t1 <=> $t2;
}

sub member			# Return position of user $us in the group.
{				# 1 is the first position, 0 if not in the
    local($us,$line)=@_;	# group.
    local(@te);
    if ( $line=~/:/ )
    {
	local(@te2)=split(/:/,$line,3);
	$line=$te2[$#te2];
    }
    @te=split(/,/,$line);
    local($l)=-1;
    local($i);
    for($i=0;$i<=$#te;$i++)
    {
	if ( $te[$i] eq $us )
	{
	    $l=$i;
	}
    }
    return(++$l);
}