#!/opt/bin/perl
#
#########################################################################
#                                                                       #
#   Program to list all unused user and group IDs (UIDs and GIDs)       #
#                                                                       #
#########################################################################
#                                                                       #
#   Version 1.0     -   Written 26.09.95 by Steffen Beyer               #
#                                                                       #
#########################################################################
#                                                                       #
#   Copyright (C) 1995 by software design & management GmbH & Co. KG    #
#                                                                       #
#########################################################################
#
# Some defaults:
#
$version = 'version 1.0';
#
$self = $0;
#
if ($self =~ m!/([^/]+)$!) { $self = $1; }
#
$argc = @ARGV;
#
# Subroutine definitions:
#
sub numerically { $a <=> $b }
#
# Check number of arguments:
#
if ($argc != 2)
{
    die "$self error: wrong number of arguments ($argc instead of 2)!\n";
}
#
# Get and check the two filenames:
#
$file1 = shift;
$file2 = shift;
#
unless (-f $file1)
{
    die "$self error: '$file1' is not a file!\n";
}
#
unless (-f $file2)
{
    die "$self error: '$file2' is not a file!\n";
}
#
unless (-r $file1)
{
    die "$self error: '$file1' is not readable!\n";
}
#
unless (-r $file2)
{
    die "$self error: '$file2' is not readable!\n";
}
#
unless (open(FILE1, "<$file1"))
{
    die "$self error: can't open '$file1': $!\n";
}
#
$state = 0;
#
while (<FILE1>)
{
    if    ($state == 0)
    {
        if (/^UIDs:/) { $state = 1; next; }
    }
    elsif ($state == 1)
    {
        if (/^GIDs:/) { $state = 2; next; }
        if (/^(\d+)$/)
        {
            $uid_list{$1} = 1;
        }
    }
    else
    {
        if (/^(\d+)$/)
        {
            $gid_list{$1} = 1;
        }
    }
}
#
close(FILE1);
#
unless (open(FILE2, "<$file2"))
{
    die "$self error: can't open '$file2': $!\n";
}
#
$state = 0;
#
while (<FILE2>)
{
    if    ($state == 0)
    {
        if (/^UIDs:/) { $state = 1; next; }
    }
    elsif ($state == 1)
    {
        if (/^GIDs:/) { $state = 2; next; }
        if (/^(\d+)$/)
        {
            $uid_list{$1} = 1;
#           if ($uid_list{$1} < 2) { $uid_list{$1} += 2; }
        }
    }
    else
    {
        if (/^(\d+)$/)
        {
            $gid_list{$1} = 1;
#           if ($gid_list{$1} < 2) { $gid_list{$1} += 2; }
        }
    }
}
#
close(FILE2);
#
# Header:
#
print "\n$self $version\n\n";
#
# List the unused UIDs:
#
print "Free UIDs:\n\n";
#
$previous = 0;
#
foreach $uid (sort numerically keys(%uid_list))
{
    if ($uid >= 0)
    {
        $difference = $uid - $previous;
        if ($difference == 1)
        {
            print "$previous ";
        }
        elsif ($difference == 2)
        {
            printf("%d %d ", $previous, $uid - 1);
        }
        elsif ($difference > 2)
        {
            printf("%d..%d ", $previous, $uid - 1);
        }
        else {}
        $previous = $uid + 1;
    }
}
#
print "$previous..*\n\n";
#
# List the unused GIDs:
#
print "Free GIDs:\n\n";
#
$previous = 0;
#
foreach $gid (sort numerically keys(%gid_list))
{
    if ($gid >= 0)
    {
        $difference = $gid - $previous;
        if ($difference == 1)
        {
            print "$previous ";
        }
        elsif ($difference == 2)
        {
            printf("%d %d ", $previous, $gid - 1);
        }
        elsif ($difference > 2)
        {
            printf("%d..%d ", $previous, $gid - 1);
        }
        else {}
        $previous = $gid + 1;
    }
}
#
print "$previous..*\n\n";
#
# Done.
#