Filename: ///usr/bin/linux-version

#!/usr/bin/perl

# Copyright 2011 Ben Hutchings
#
# This program 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 of the License, or
# (at your option) any later version.
#
# This program 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.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

use strict;
use warnings;

use DebianLinux qw(version_cmp image_list);

sub usage {
    my $fh = shift;
    print $fh (<< "EOT");
Usage: $0 compare VERSION1 OP VERSION2
       $0 sort [--reverse] [VERSION1 VERSION2 ...]
       $0 list [--paths]

The version arguments should be kernel version strings as shown by
'uname -r' and used in filenames.

The valid comparison operators are: lt le eq ge gt
EOT
}

sub usage_error {
    usage(*STDERR{IO});
    exit 2;
}

sub compare_versions {
    my %op_map = qw(lt < le <= eq == ge >= gt >);

    # Check arguments
    if (@_ != 3) {
	usage_error();
    }
    my ($left, $op, $right) = @_;
    if (!exists($op_map{$op})) {
	usage_error();
    }

    my $sign = version_cmp($left, $right);
    exit !eval("$sign ${op_map{$op}} 0");
}

sub sort_versions {
    # Check for --reverse option
    my $sign = 1;
    if (@_ >= 1 and $_[0] eq '--reverse') {
	$sign = -1;
	shift;
    }

    # Collect versions from argv or stdin (with optional suffix after a space)
    my @versions;
    if (@_) {
	@versions = map({[$_, "\n"]} @_);
    } else {
	while (<STDIN>) {
	    /^([^ ]*)(.*\n?)$/ or die;
	    push @versions, [$1, $2];
	}
    }

    for (sort({version_cmp($a->[0], $b->[0]) * $sign} @versions)) {
	print @$_;
    }
    exit 0;
}

sub list_versions {
    my $show_paths;

    if (@_ == 1 and $_[0] eq '--paths') {
	$show_paths = 1;
    } elsif (@_ != 0) {
	usage_error();
    }

    for (image_list()) {
	my ($version, $path) = @$_;
	if ($show_paths) {
	    print "$version $path\n";
	} else {
	    print "$version\n";
	}
    }
    exit 0;
}

if (@ARGV == 0) {
    usage_error();
}

my $command = shift;
if ($command eq 'help' or grep({$_ eq '--help'} $command, @ARGV)) {
    usage(*STDOUT{IO});
    exit 0;
} elsif ($command eq 'compare') {
    compare_versions(@ARGV);
} elsif ($command eq 'sort') {
    sort_versions(@ARGV);
} elsif ($command eq 'list') {
    list_versions(@ARGV);
}
usage_error();

./Ninja\.