#!/usr/bin/perl

use Socket;

$proto=getprotobyname('tcp');
if (!$proto)
{
    die "getprotobyname failed: $!";
}
socket(FINGER, PF_INET, SOCK_STREAM, $proto) || die "socket failed: $!";
select((select(FINGER), $|=1)[0]);
$port=getservbyname('finger', 'tcp');
if (!$port)
{
    die "getservbyname failed: $!";
}
$host=inet_aton("finger.kernel.org");
if (!$host)
{
    die "inet_aton failed: $!";
}
$sin=sockaddr_in($port, $host);
if (!$sin)
{
    die "sockaddr_in failed: $!";
}
connect(FINGER, $sin) || die "connect failed: $!";

print FINGER "\n";
while (<FINGER>)
{
    chomp;
    if (/^\s*The latest \*?(stable|beta)\*? version of the Linux kernel is:\s*(\d+\.\d+\.\d+\w*)\s*$/o)
    {
        $version{$1}=$2;
    }
}

close(FINGER);

if (!defined($version{'stable'}))
{
    print STDERR "failed to determine latest kernel version!\n";
    exit 1;
}

if (-f "/proc/sys/kernel/osrelease")
{
    open(RELEASE, "</proc/sys/kernel/osrelease");
    $version{'local'}=<RELEASE>;
    close(RELEASE);
}
else # I don't know what to do, so fall back to uname.
{
    $version{'local'}=`uname -r`;
}
chomp $version{'local'};

if ($version{'local'} gt $version{'stable'})
{
    if (defined($version{'beta'}))
    {
        if ($version{'local'} lt $version{'beta'})
        {
            print "kernel version $version{'beta'} is available\n";
        }
        elsif ($version{'local'} eq $version{'beta'})
        {
            print "running latest beta kernel\n";
        }
        else
        {
            print "running newer beta kernel than the latest?!?\n";
        }
    }
    else
    {
        print "running newer stable kernel than the latest?!?\n";
    }
}
elsif ($version{'local'} eq $version{'stable'})
{
    print "running latest stable kernel\n";
}
else
{
    print "kernel version $version{'stable'} is available\n";
}