#!/usr/bin/perl -w

=head1 NAME

xen-list-images - List all the created and configured Xen images.

=head1 SYNOPSIS

  xen-list-image [options]

  Help Options:
   --help     Show this scripts help information.
   --manual   Read this scripts manual.
   --version  Show the version number and exit.

  Testing options:
   --test     Specify an alternate Xen configuration directory.

=head1 OPTIONS

=over 8

=item B<--help>
Show the scripts help information.

=item B<--manual>
Read the manual.

=item B<--test>
This flag causes the script to load the Xen configuration files from a different directory than the default of B</etc/xen>.

=item B<--version>
Show the version number and exit.

=back


=head1 DESCRIPTION

  xen-list-images is a simple script which will display all the
 Xen images which have been created.

  This works by iterating over all files matching the pattern
 B</etc/xen/*.cfg> which is what the B<xen-create-image> script would
 create.

  For each instance which has been created we'll display the name,
 and then either the IP address configured, or "DHCP" to denote
 a dynamic host.

=cut

=head1 TODO

  It should be possible to determine the disk(s) used by the images,
 and then display their sizes.

  Along with the memory allocated, etc.

=cut


=head1 AUTHOR


 Steve
 --
 http://www.steve.org.uk/

 $Id: xen-list-images,v 1.12 2006/08/16 09:42:44 steve Exp $

=cut


=head1 LICENSE

Copyright (c) 2005-2006 by Steve Kemp.  All rights reserved.

This module is free software;
you can redistribute it and/or modify it under
the same terms as Perl itself.
The LICENSE file contains the full text of the license.

=cut


use strict;
use English;
use File::Temp qw/ tempdir /;
use Getopt::Long;
use Pod::Usage;


#
#  Configuration options, initially read from the configuration files
# but may be overridden by the command line.
#
#  Command line flags *always* take precedence over the configuration file.
#
my %CONFIG;

#
#  Default prefix
#
$CONFIG{'prefix'} = "/etc/xen";

#
# Release number.
#
my $RELEASE = '2.3';



#
#  Read the global configuration file if it exists.
#
if ( -e "/etc/xen-tools/xen-tools.conf" )
{
    readConfigurationFile( "/etc/xen-tools/xen-tools.conf" );
}


#
#  Parse command line arguments, these override the values from the
# configuration file.
#
parseCommandLineArguments();


#
#  Read all the xen configuration files.
#
my @instances = findXenInstances();


#
#  Now process each instance.
#
my $count = 0;
foreach my $instance ( @instances )
{
    if ( $count ) { print "\n"; }

    displayInstance( $instance );
    $count += 1;
}


#
#  All done.
#
exit;



=begin doc

  Read the configuration file specified.

=end doc

=cut

sub readConfigurationFile
{
    my ($file) = ( @_ );

    open( FILE, "<", $file ) or die "Cannot read file '$file' - $!";

    my $line       = "";

    while (defined($line = <FILE>) )
    {
        chomp $line;
       if ($line =~ s/\\$//)
       {
           $line .= <FILE>;
           redo unless eof(FILE);
       }

       # Skip lines beginning with comments
       next if ( $line =~ /^([ \t]*)\#/ );

       # Skip blank lines
       next if ( length( $line ) < 1 );

       # Strip trailing comments.
       if ( $line =~ /(.*)\#(.*)/ )
       {
           $line = $1;
       }

       # Find variable settings
       if ( $line =~ /([^=]+)=([^\n]+)/ )
       {
           my $key = $1;
           my $val = $2;

           # Strip leading and trailing whitespace.
           $key =~ s/^\s+//;
           $key =~ s/\s+$//;
           $val =~ s/^\s+//;
           $val =~ s/\s+$//;

           # Store value.
           $CONFIG{ $key } = $val;
       }
    }

    close( FILE );
}




=begin doc

  Parse the arguments specified upon the command line.

=end doc

=cut

sub parseCommandLineArguments
{
    my $HELP    = 0;
    my $MANUAL  = 0;
    my $VERSION        = 0;

    #  Parse options.
    #
    GetOptions(
              "test=s",     \$CONFIG{'prefix'},
              "help",       \$HELP,
              "manual",     \$MANUAL,
              "version",    \$VERSION
             );

    pod2usage(1) if $HELP;
    pod2usage(-verbose => 2 ) if $MANUAL;


    if ( $VERSION )
    {
       my $REVISION      = '$Revision: 1.12 $';

       if ( $REVISION =~ /1.([0-9.]+) / )
       {
           $REVISION = $1;
       }

       print "xen-list-images release $RELEASE - CVS: $REVISION\n";
       exit;

    }
}



=begin doc

  Return an array containing the names of each xen configuration
 file we found.

=end doc

=cut

sub findXenInstances
{
    my @found;

    foreach my $file ( sort( glob( $CONFIG{'prefix'} . "/*.cfg" ) ) )
    {
        push @found, $file if ( -e $file );
    }

    return( @found );
}



=begin doc

  Show details about the the Xen instance contained in the given
 configuration file.

=end doc

=cut

sub displayInstance
{
    my ( $file ) = ( @_ );

    #
    #  Read each line.
    #
    open( FILY, "<", $file );
    my @LINES = <FILY>;
    close( FILY );

    #
    #  Is it dynamic?
    #
    my $dhcp = 0;
    my $ip   = '';
    my $name = '';
    my $mem  = 0;

    foreach my $line ( @LINES )
    {
        if ( $line =~ /^\s*dhcp\s*=\s*"dhcp\"/i )
        {
            $dhcp = 1;
        }
        if ( $line =~ /^\s*name\s*=\s*["']([^'"]+)['"]/i )
        {
            $name = $1;
        }
        if ( $line =~ /.*memory[^0-9]*([0-9]+)/i )
        {
            $mem = $1;
        }
        if ( $line =~ /ip=([0-9\.]+)/ )
        {
            $ip = $1;
        }
    }

    print "Name: $name\n";
    print "Memory: $mem\n";
    print "IP: $ip\n" if length( $ip );
    print "DHCP\n" if $dhcp;

}


