virt-inspector

#!/usr/bin/perl -w
# virt-inspector
# Copyright (C) 2010 Red Hat Inc.
#
# 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., 675 Mass Ave, Cambridge, MA 02139, USA.

use warnings;
use strict;

use Sys::Guestfs;
use Sys::Guestfs::Lib qw(open_guest);
use Pod::Usage;
use Getopt::Long;
use File::Temp qw/tempfile/;
use File::Basename;
use XML::Writer;
use Locale::TextDomain 'libguestfs';

=encoding utf8

=head1 NAME

virt-inspector - Display operating system version and other information about a virtual machine

=head1 SYNOPSIS

 virt-inspector [--connect URI] domname

 virt-inspector guest.img [guest.img ...]

=head1 DESCRIPTION

B<virt-inspector> examines a virtual machine or disk image and tries
to determine the version of the operating system and other information
about the virtual machine.

Virt-inspector produces XML output for feeding into other programs.

In the normal usage, use C<virt-inspector domname> where C<domname> is
the libvirt domain (see: C<virsh list --all>).

You can also run virt-inspector directly on disk images from a single
virtual machine.  Use C<virt-inspector guest.img>.  In rare cases a
domain has several block devices, in which case you should list them
one after another, with the first corresponding to the guest's
C</dev/sda>, the second to the guest's C</dev/sdb> and so on.

Virt-inspector can only inspect and report upon I<one domain at a
time>.  To inspect several virtual machines, you have to run
virt-inspector several times (for example, from a shell script
for-loop).

Because virt-inspector needs direct access to guest images, it won't
normally work over remote libvirt connections.

=head1 OPTIONS

=over 4

=cut

my $help;

=item B<--help>

Display brief help.

=cut

my $version;

=item B<--version>

Display version number and exit.

=cut

my $uri;

=item B<--connect URI> | B<-c URI>

If using libvirt, connect to the given I<URI>.  If omitted,
then we connect to the default libvirt hypervisor.

Libvirt is only used if you specify a C<domname> on the
command line.  If you specify guest block devices directly,
then libvirt is not used at all.

=cut

my $format;

=item B<--format> raw

Specify the format of disk images given on the command line.  If this
is omitted then the format is autodetected from the content of the
disk image.

If disk images are requested from libvirt, then this program asks
libvirt for this information.  In this case, the value of the format
parameter is ignored.

If working with untrusted raw-format guest disk images, you should
ensure the format is always specified.

=back

=cut

GetOptions ("help|?" => \$help,
            "version" => \$version,
            "connect|c=s" => \$uri,
            "format=s" => \$format,
    ) or pod2usage (2);
pod2usage (1) if $help;
if ($version) {
    my $g = Sys::Guestfs->new ();
    my %h = $g->version ();
    print "$h{major}.$h{minor}.$h{release}$h{extra}\n";
    exit
}
pod2usage (__"virt-inspector: no image or VM names given") if @ARGV == 0;

my @args = (\@ARGV);
push @args, address => $uri if defined $uri;
push @args, format => $format if defined $format;
my $g = open_guest (@args);

$g->launch ();

my @roots = $g->inspect_os ();
if (@roots == 0) {
    die __x("{prog}: No operating system could be detected inside this disk image.\n\nThis may be because the file is not a disk image, or is not a virtual machine\nimage, or because the OS type is not understood by libguestfs.\n\nIf you feel this is an error, please file a bug report including as much\ninformation about the disk image as possible.\n",
            prog => basename ($0));
}

=head1 XML FORMAT

The virt-inspector XML is described precisely in a RELAX NG schema
which is supplied with libguestfs.  This section is just an overview.

The top-level element is E<lt>operatingsystemsE<gt>, and it contains
one or more E<lt>operatingsystemE<gt> elements.  You would only see
more than one E<lt>operatingsystemE<gt> element if the virtual machine
is multi-boot, which is vanishingly rare in real world VMs.

=head2 E<lt>operatingsystemE<gt>

In the E<lt>operatingsystemE<gt> tag are various optional fields that
describe the operating system, its architecture, the descriptive
"product name" string, the type of OS and so on, as in this example:

 <operatingsystems>
   <operatingsystem>
     <root>/dev/sda2</root>
     <name>windows</name>
     <arch>i386</arch>
     <distro>windows</distro>
     <product_name>Windows 7 Enterprise</product_name>
     <major_version>6</major_version>
     <minor_version>1</minor_version>
     <windows_systemroot>/Windows</windows_systemroot>

These fields are derived from the libguestfs inspection API, and
you can find more details in L<guestfs(3)/INSPECTION>.

The E<lt>rootE<gt> element is the root filesystem device, but from the
point of view of libguestfs (block devices may have completely
different names inside the VM itself).

=cut

# Start the XML output.
my $xml = new XML::Writer (DATA_MODE => 1, DATA_INDENT => 2);

$xml->startTag ("operatingsystems");

my $root;
foreach $root (@roots) {
    my %fses = $g->inspect_get_mountpoints ($root);
    my @fses = sort { length $a <=> length $b } keys %fses;
    foreach (@fses) {
        $g->mount_ro ($fses{$_}, $_);
    }

    $xml->startTag ("operatingsystem");

    # Basic OS fields.
    $xml->dataElement (root => canonicalize ($root));

    my ($s, $distro, $major_version);
    $s = $g->inspect_get_type ($root);
    $xml->dataElement (name => $s) if $s ne "unknown";
    $s = $g->inspect_get_arch ($root);
    $xml->dataElement (arch => $s) if $s ne "unknown";
    $distro = $g->inspect_get_distro ($root);
    $xml->dataElement (distro => $distro) if $distro ne "unknown";
    $s = $g->inspect_get_product_name ($root);
    $xml->dataElement (product_name => $s) if $s ne "unknown";
    $major_version = $g->inspect_get_major_version ($root);
    $xml->dataElement (major_version => $major_version);
    $s = $g->inspect_get_minor_version ($root);
    $xml->dataElement (minor_version => $s);

    eval {
        $s = $g->inspect_get_windows_systemroot ($root);
        $xml->dataElement (windows_systemroot => $s);
    };

    # Mountpoints.
    output_mountpoints ($root, \@fses, \%fses);

    # Filesystems.
    output_filesystems ($root);

    # Package format / management and applications.
    output_applications ($root, $distro, $major_version);

    $xml->endTag("operatingsystem");

    $g->umount_all ();
}

# End the XML output.
$xml->endTag ("operatingsystems");
$xml->end ();

=head2 E<lt>mountpointsE<gt>

Un*x-like guests typically have multiple filesystems which are mounted
at various mountpoints, and these are described in the
E<lt>mountpointsE<gt> element which looks like this:

 <operatingsystems>
   <operatingsystem>
     ...
     <mountpoints>
       <mountpoint dev="/dev/vg_f13x64/lv_root">/</mountpoint>
       <mountpoint dev="/dev/sda1">/boot</mountpoint>
     </mountpoints>

As with E<lt>rootE<gt>, devices are from the point of view of
libguestfs, and may have completely different names inside the guest.
Only mountable filesystems appear in this list, not things like swap
devices.

=cut

sub output_mountpoints
{
    local $_;
    my $root = shift;
    my $fskeys = shift;
    my $fshash = shift;

    $xml->startTag ("mountpoints");
    foreach (@$fskeys) {
        $xml->dataElement ("mountpoint", $_,
                           dev => canonicalize ($fshash->{$_}));
    }
    $xml->endTag ("mountpoints");
}

=head2 E<lt>filesystemsE<gt>

E<lt>filesystemsE<gt> is like E<lt>mountpointsE<gt> but covers I<all>
filesystems belonging to the guest, including swap and empty
partitions.  (In the rare case of a multi-boot guest, it covers
filesystems belonging to this OS or shared by this OS and other OSes).

You might see something like this:

 <operatingsystems>
   <operatingsystem>
     ...
     <filesystems>
       <filesystem dev="/dev/vg_f13x64/lv_root">
         <type>ext4</type>
         <label>Fedora-13-x86_64</label>
         <uuid>e6a4db1e-15c2-477b-ac2a-699181c396aa</uuid>
       </filesystem>

The optional elements within E<lt>filesystemE<gt> are the filesystem
type, the label, and the UUID.

=cut

sub output_filesystems
{
    local $_;
    my $root = shift;

    $xml->startTag ("filesystems");

    my @fses = $g->inspect_get_filesystems ($root);
    @fses = sort @fses;
    foreach (@fses) {
        $xml->startTag ("filesystem",
                        dev => canonicalize ($_));

        eval {
            my $type = $g->vfs_type ($_);
            $xml->dataElement (type => $type)
                if defined $type && $type ne "";
        };

        eval {
            my $label = $g->vfs_label ($_);
            $xml->dataElement (label => $label)
                if defined $label && $label ne "";
        };

        eval {
            my $uuid = $g->vfs_uuid ($_);
            $xml->dataElement (uuid => $uuid)
                if defined $uuid && $uuid ne "";
        };

        $xml->endTag ("filesystem");
    }

    $xml->endTag ("filesystems");
}

=head2 E<lt>applicationsE<gt>

The related elements E<lt>package_formatE<gt>,
E<lt>package_managementE<gt> and E<lt>applicationsE<gt> describe
applications installed in the virtual machine.  At the moment we are
only able to list RPMs and Debian packages installed, but in future we
will support other Linux distros and Windows.

E<lt>package_formatE<gt>, if present, describes the packaging
system used.  Typical values would be C<rpm> and C<deb>.

E<lt>package_managementE<gt>, if present, describes the package
manager.  Typical values include C<yum>, C<up2date> and C<apt>

E<lt>applicationsE<gt> lists the packages or applications
installed.

 <operatingsystems>
   <operatingsystem>
     ...
     <applications>
       <application>
         <name>coreutils</name>
         <version>8.5</version>
         <release>1</release>
       </application>

(The version and release fields may not be available for
some package types).

=cut

sub output_applications
{
    local $_;
    my $root = shift;
    my $distro = shift;
    my $major_version = shift;

    # Based on the distro, take a guess at the package format
    # and package management.
    my ($package_format, $package_management);
    if (defined $distro) {
        if ($distro eq "archlinux") {
            $package_format = "pacman";
            $package_management = "pacman";
        }
        elsif ($distro eq "debian" || $distro eq "ubuntu") {
            $package_format = "deb";
            $package_management = "apt";
        }
        elsif ($distro eq "fedora" || $distro eq "meego") {
            $package_format = "rpm";
            $package_management = "yum";
        }
        elsif ($distro eq "gentoo") {
            $package_format = "ebuild";
            $package_management = "portage";
        }
        elsif ($distro eq "pardus") {
            $package_format = "pisi";
            $package_management = "pisi";
        }
        elsif ($distro =~ /redhat/ || $distro =~ /rhel/) {
            if ($major_version >= 5) {
                $package_format = "rpm";
                $package_management = "yum";
            } else {
                $package_format = "rpm";
                $package_management = "up2date";
            }
        }
        # else unknown.
    }

    $xml->dataElement (package_format => $package_format)
        if defined $package_format;
    $xml->dataElement (package_management => $package_management)
        if defined $package_management;

    # Do we know how to get a list of applications?
    if (defined $package_format) {
        if ($package_format eq "rpm") {
            output_applications_rpm ($root);
        }
        elsif ($package_format eq "deb") {
            output_applications_deb ($root);
        }
    }
}

sub output_applications_rpm
{
    local $_;
    my $root = shift;

    # Previous virt-inspector ran the 'rpm' program from the guest.
    # This is insecure, and unnecessary because we can get the same
    # information directly from the RPM database.

    my @applications;

    eval {
        my ($fh, $filename) = tempfile (UNLINK => 1);
        my $fddev = "/dev/fd/" . fileno ($fh);
        $g->download ("/var/lib/rpm/Name", $fddev);
        close $fh or die "close: $!";

        # Read the database with the Berkeley DB dump tool.
        my $cmd = "db_dump -p '$filename'";
        open PIPE, "$cmd |" or die "close: $!";
        while (<PIPE>) {
            chomp;
            last if /^HEADER=END$/;
        }
        while (<PIPE>) {
            chomp;
            last if /^DATA=END$/;

            # First character on each data line is a space.
            if (length $_ > 0 && substr ($_, 0, 1) eq ' ') {
                $_ = substr ($_, 1);
            }
            # Name should never contain non-printable chars.
            die "name contains non-printable chars" if /\\/;
            push @applications, $_;

            $_ = <PIPE>; # discard value
        }
        close PIPE or die "close: $!";
    };
    if (!$@ && @applications > 0) {
        @applications = sort @applications;
        $xml->startTag ("applications");
        foreach (@applications) {
            $xml->startTag ("application");
            $xml->dataElement (name => $_);
            $xml->endTag ("application");
        }
        $xml->endTag ("applications");
    }
}

sub output_applications_deb
{
    local $_;
    my $root = shift;

    my @applications;

    eval {
        my ($fh, $filename) = tempfile (UNLINK => 1);
        my $fddev = "/dev/fd/" . fileno ($fh);
        $g->download ("/var/lib/dpkg/status", $fddev);
        close $fh or die "close: $!";

        # Read the file.  Each package is separated by a blank line.
        open FILE, $filename or die "$filename: $!";
        my ($name, $installed, $version, $release);
        while (<FILE>) {
            chomp;
            if (/^Package: (.*)/) {
                $name = $1;
            } elsif (/^Status: .*\binstalled\b/) {
                $installed = 1;
            } elsif (/^Version: (.*?)-(.*)/) {
                $version = $1;
                $release = $2;
            } elsif ($_ eq "") {
                if ($installed &&
                    defined $name && defined $version && defined $release) {
                    push @applications, [ $name, $version, $release ];
                }
                $name = undef;
                $installed = undef;
                $version = undef;
                $release = undef;
            }
        }
        close FILE or die "$filename: $!";
    };
    if (!$@ && @applications > 0) {
        @applications = sort { $a->[0] cmp $b->[0] } @applications;
        $xml->startTag ("applications");
        foreach (@applications) {
            $xml->startTag ("application");
            $xml->dataElement (name => $_->[0]);
            $xml->dataElement (version => $_->[1]);
            $xml->dataElement (release => $_->[2]);
            $xml->endTag ("application");
        }
        $xml->endTag ("applications");
    }
}

# The reverse of device name translation, see
# BLOCK DEVICE NAMING in guestfs(3).
sub canonicalize
{
    local $_ = shift;

    if (m{^/dev/[hv]d([a-z]\d)$}) {
        return "/dev/sd$1";
    }
    $_;
}

=head1 USING XPATH

You can use the XPath query language, and/or the xpath tool, in order
to select parts of the XML.

For example:

 $ virt-inspector Guest | xpath //filesystems
 Found 1 nodes:
 -- NODE --
 <filesystems>
      <filesystem dev="/dev/vg_f13x64/lv_root">
        <type>ext4</type>
 [etc]

 $ virt-inspector Guest | \
     xpath "string(//filesystem[@dev='/dev/sda1']/type)"
 Query didn't return a nodeset. Value: ext4

=head1 SHELL QUOTING

Libvirt guest names can contain arbitrary characters, some of which
have meaning to the shell such as C<#> and space.  You may need to
quote or escape these characters on the command line.  See the shell
manual page L<sh(1)> for details.

=head1 SEE ALSO

L<guestfs(3)>,
L<guestfish(1)>,
L<Sys::Guestfs(3)>,
L<Sys::Guestfs::Lib(3)>,
L<Sys::Virt(3)>,
L<http://www.w3.org/TR/xpath/>,
L<http://libguestfs.org/>.

=head1 AUTHORS

=over 4

=item *

Richard W.M. Jones L<http://people.redhat.com/~rjones/>

=item *

Matthew Booth L<mbooth@redhat.com>

=back

=head1 COPYRIGHT

Copyright (C) 2010 Red Hat Inc.

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., 675 Mass Ave, Cambridge, MA 02139, USA.