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#!/usr/bin/perl -w
# virt-win-reg
# 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
# 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 Street, Fifth Floor, Boston, MA 02110-1301 USA.
use warnings;
use strict;
use Sys::Guestfs;
use Sys::Guestfs::Lib qw(open_guest);
use Win::Hivex;
use Win::Hivex::Regedit qw(reg_import reg_export);
use Pod::Usage;
use Getopt::Long;
use File::Temp qw/tempdir/;
use File::Basename;
use Locale::TextDomain 'libguestfs';
=encoding utf8
=head1 NAME
virt-win-reg - Export and merge Windows Registry entries from a Windows guest
virt-win-reg domname 'HKLM\Path\To\Subkey'
virt-win-reg domname 'HKLM\Path\To\Subkey' name
virt-win-reg domname 'HKLM\Path\To\Subkey' @
virt-win-reg --merge domname [input.reg ...]
virt-win-reg [--options] disk.img ... # instead of domname
=head1 WARNING
You must I<not> use C<virt-win-reg> with the I<--merge> option on live
virtual machines. If you do this, you I<will> get irreversible disk
corruption in the VM. C<virt-win-reg> tries to stop you from doing
this, but doesn't catch all cases.
Modifying the Windows Registry is an inherently risky operation. The format
is deliberately obscure and undocumented, and Registry changes
can leave the system unbootable. Therefore when using the I<--merge>
option, make sure you have a reliable backup first.
This program can export and merge Windows Registry entries from a
Windows guest.
The first parameter is the libvirt guest name or the raw disk image of
a Windows guest.
If I<--merge> is I<not> specified, then the chosen registry
key is displayed/exported (recursively). For example:
$ virt-win-reg Windows7 'HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft'
You can also display single values from within registry keys,
for example:
$ cvkey='HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion'
$ virt-win-reg Windows7 $cvkey ProductName
Windows 7 Enterprise
With I<--merge>, you can merge a textual regedit file into
the Windows Registry:
$ virt-win-reg --merge Windows7 changes.reg
=head2 NOTE
This program is only meant for simple access to the registry. If you
want to do complicated things with the registry, we suggest you
download the Registry hive files from the guest using L<libguestfs(3)>
or L<guestfish(1)> and access them locally, eg. using L<hivex(3)>,
L<hivexsh(1)> or L<hivexregedit(1)>.
=head1 OPTIONS
=over 4
my $help;
=item B<--help>
Display brief help.
my $version;
=item B<--version>
Display version number and exit.
my $debug;
=item B<--debug>
Enable debugging messages.
my $uri;
=item B<-c URI>
=item B<--connect URI>
If using libvirt, connect to the given I<URI>. If omitted, then we
connect to the default libvirt hypervisor.
If you specify guest block devices directly, then libvirt is not used
at all.
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.
my $merge;
=item B<--merge>
In merge mode, this merges a textual regedit file into the Windows
Registry of the virtual machine. If this flag is I<not> given then
virt-win-reg displays or exports Registry entries instead.
Note that I<--merge> is I<unsafe> to use on live virtual machines, and
will result in disk corruption. However exporting (without this flag)
is always safe.
my $encoding;
=item B<--encoding> UTF-16LE|ASCII
When merging (only), you may need to specify the encoding for strings
to be used in the hive file. This is explained in detail in
L<Win::Hivex::Regedit(3)/ENCODING STRINGS>.
The default is to use UTF-16LE, which should work with recent versions
of Windows.
my $unsafe_printable_strings;
=item B<--unsafe-printable-strings>
When exporting (only), assume strings are UTF-16LE and print them as
strings instead of hex sequences. Remove the final zero codepoint
from strings if present.
This is unsafe and does not preserve the fidelity of strings in the
original Registry for various reasons:
=over 4
=item *
Assumes the original encoding is UTF-16LE. ASCII strings and strings
in other encodings will be corrupted by this transformation.
=item *
Assumes that everything which has type 1 or 2 is really a string
and that everything else is not a string, but the type field in
real Registries is not reliable.
=item *
Loses information about whether a zero codepoint followed the string
in the Registry or not.
This all happens because the Registry itself contains no information
about how strings are encoded (see
L<Win::Hivex::Regedit(3)/ENCODING STRINGS>).
You should only use this option for quick hacking and debugging of the
Registry contents, and I<never> use it if the output is going to be
passed into another program or stored in another Registry.
GetOptions ("help|?" => \$help,
"version" => \$version,
"connect|c=s" => \$uri,
"debug|d" => \$debug,
"format=s" => \$format,
"merge" => \$merge,
"encoding=s" => \$encoding,
"unsafe-printable-strings" => \$unsafe_printable_strings,
) 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";
# virt-win-reg only takes a single disk image ...
die __"no libvirt domain name or disk image given\n" if @ARGV == 0;
my $domname_or_image = shift @ARGV;
warn "launching libguestfs ..." if $debug;
my @lib_args = ([$domname_or_image]);
push @lib_args, address => $uri if $uri;
push @lib_args, rw => 1 if $merge;
push @lib_args, format => $format if defined $format;
my $g = open_guest (@lib_args);
$g->launch ();
warn "inspecting guest ..." if $debug;
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));
if (@roots > 1) {
die __x("{prog}: multiboot operating systems are not supported.\n",
prog => basename ($0))
my %fses = $g->inspect_get_mountpoints ($roots[0]);
my @fses = sort { length $a <=> length $b } keys %fses;
my $mountopts = $merge ? "" : "ro";
foreach (@fses) {
$g->mount_options ($mountopts, $fses{$_}, $_);
my $systemroot = $g->inspect_get_windows_systemroot ($roots[0]);
# Create a working directory to store the downloaded registry files.
my $tmpdir = tempdir (CLEANUP => 1);
# Used when merging (only) to map from the downloaded hiveshortname to
# various properties about the hive. The key is hiveshortname. The
# value is a hashref containing {h} (hive handle) and {hivefile} (full
# hive path on the Windows side).
my %hives;
if (!$merge) { # Export mode.
die __"expecting 1 or 2 more parameters, subkey path and optionally the value to export\n"
if @ARGV < 1 || @ARGV > 2;
my $path = shift @ARGV;
my $name = shift @ARGV; # or undef
# Map this to the hive name. This function dies on failure.
my ($hiveshortname, $hivefile, $prefix);
($hiveshortname, $hivefile, $path, $prefix) = map_path_to_hive ($path);
# Download the chosen hive.
download_hive ($hivefile, $hiveshortname);
# Open it.
my $h = Win::Hivex->open ("$tmpdir/$hiveshortname", debug => $debug);
unless ($name) {
# Export it.
warn "exporting $path from $hiveshortname with prefix $prefix ..."
if $debug;
reg_export ($h, $path, \*STDOUT,
prefix => $prefix,
unsafe_printable_strings => $unsafe_printable_strings);
} else {
# Export a single key using hivexget.
my @args = ("hivexget", "$tmpdir/$hiveshortname", $path, $name);
warn "running ", join (" ", @args), " ..." if $debug;
system (@args) == 0 or die "hivexget failed: $?"
else { # Import mode.
if (@ARGV == 0) {
reg_import (\*STDIN, \&import_mapper, encoding => $encoding);
} else {
foreach (@ARGV) {
open my $fh, $_ or die "open: $_: $!";
reg_import ($fh, \&import_mapper, encoding => $encoding);
# Now we've done importing, commit all the hive handles and
# close them all.
foreach (values %hives) {
my $h = $_->{h};
delete $_->{h};
$h->commit (undef);
# Upload all the downloaded hives.
foreach my $hiveshortname (keys %hives) {
upload_hive ($hiveshortname, $hives{$hiveshortname}->{hivefile})
# Close.
$g->shutdown ();
$g->close ();
exit 0;
# map function passed to reg_import.
sub import_mapper
local $_ = shift;
my ($hiveshortname, $hivefile, $path, $prefix) = map_path_to_hive ($_);
# Need to download this hive?
unless (-f "$tmpdir/$hiveshortname") {
download_hive ($hivefile, $hiveshortname);
my $h = Win::Hivex->open ("$tmpdir/$hiveshortname",
write => 1, debug => $debug);
my %hash = ( h => $h, hivefile => $hivefile );
$hives{$hiveshortname} = \%hash;
return ($hives{$hiveshortname}->{h}, $path);
# Given a path, map that to the name of the hive and the true path
# within that hive.
sub map_path_to_hive
local $_ = shift;
my ($hiveshortname, $hivefile, $path, $prefix);
if (/^\\?(?:HKEY_LOCAL_MACHINE|HKLM)\\SAM(\\.*)?$/i) {
$hiveshortname = "sam";
$hivefile = "$systemroot/system32/config/$hiveshortname";
$path = defined $1 ? $1 : "\\";
elsif (/^\\?(?:HKEY_LOCAL_MACHINE|HKLM)\\SECURITY(\\.*)?$/i) {
$hiveshortname = "security";
$hivefile = "$systemroot/system32/config/$hiveshortname";
$path = defined $1 ? $1 : "\\";
elsif (/^\\?(?:HKEY_LOCAL_MACHINE|HKLM)\\SOFTWARE(\\.*)?$/i) {
$hiveshortname = "software";
$hivefile = "$systemroot/system32/config/$hiveshortname";
$path = defined $1 ? $1 : "\\";
elsif (/^\\?(?:HKEY_LOCAL_MACHINE|HKLM)\\SYSTEM(\\.*)?$/i) {
$hiveshortname = "system";
$hivefile = "$systemroot/system32/config/$hiveshortname";
$path = defined $1 ? $1 : "\\";
elsif (/^\\?(?:HKEY_USERS|HKU)\\.DEFAULT(\\.*)?$/i) {
$hiveshortname = "default";
$hivefile = "$systemroot/system32/config/$hiveshortname";
$path = defined $1 ? $1 : "\\";
elsif (/^\\?(?:HKEY_USERS|HKU)\\(S-1-5-[-\d]+)(\\.*)?$/i) {
my $sid = $1;
$hiveshortname = $sid;
$prefix = "HKEY_USERS\\$sid";
$path = defined $2 ? $2 : "\\";
# This requires a recursive call to download the SOFTWARE hive.
$hivefile = lookup_pip_of_user_sid ($sid) . "/ntuser.dat";
elsif (/^\\?(?:HKEY_USERS|HKU)\\LocalSystem(\\.*)?$/i) {
my $sid = "S-1-5-18";
$hiveshortname = $sid;
$prefix = "HKEY_USERS\\$sid";
$path = defined $1 ? $1 : "\\";
# This requires a recursive call to download the SOFTWARE hive.
$hivefile = lookup_pip_of_user_sid ($sid) . "/ntuser.dat";
elsif (/^\\?(?:HKEY_USERS|HKU)\\LocalService(\\.*)?$/i) {
my $sid = "S-1-5-19";
$hiveshortname = $sid;
$prefix = "HKEY_USERS\\$sid";
$path = defined $1 ? $1 : "\\";
# This requires a recursive call to download the SOFTWARE hive.
$hivefile = lookup_pip_of_user_sid ($sid) . "/ntuser.dat";
elsif (/^\\?(?:HKEY_USERS|HKU)\\NetworkService(\\.*)?$/i) {
my $sid = "S-1-5-20";
$hiveshortname = $sid;
$prefix = "HKEY_USERS\\$sid";
$path = defined $1 ? $1 : "\\";
# This requires a recursive call to download the SOFTWARE hive.
$hivefile = lookup_pip_of_user_sid ($sid) . "/ntuser.dat";
elsif (/^\\?(?:HKEY_USERS|HKU)\\(.*?)(\\.*)?$/i) {
$hiveshortname = "user_$1";
$prefix = "HKEY_USERS\\$1";
$path = defined $2 ? $2 : "\\";
# XXX We should probably look this up properly.
if (is_dir_nocase ("/Users/$1")) {
$hivefile = "/Users/$1/ntuser.dat"
} elsif (is_dir_nocase ("/Documents and Settings/$1")) {
$hivefile = "/Documents and Settings/$1/ntuser.dat"
} else {
die __x("virt-win-reg: {p}: cannot find user directory\n",
p => $1)
else {
die __x("virt-win-reg: {p}: not a supported Windows Registry path\n",
p => $_)
return ($hiveshortname, $hivefile, $path, $prefix);
# Given a User SID, consult
# HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\ProfileList\$sid
# and return the ProfileImagePath value.
sub lookup_pip_of_user_sid
local $_;
my $sid = shift;
my $path =
"HKLM\\SOFTWARE\\Microsoft\\Windows NT\\CurrentVersion\\ProfileList\\".
my ($hiveshortname, $hivefile, $prefix);
($hiveshortname, $hivefile, $path, $prefix) = map_path_to_hive ($path);
download_hive ($hivefile, $hiveshortname)
unless -f "$tmpdir/$hiveshortname";
my @args = ("$tmpdir/$hiveshortname", $path, "ProfileImagePath");
warn "running hivexget ", join (" ", @args), " ..." if $debug;
my $fh;
open $fh, "-|", "hivexget", @args
or die "hivexget: see earlier errors: $!";
$_ = <$fh>;
close $fh or die "hivexget: see earlier errors: $!";
# The contents of the registry are a windows path, possibly
# containing %systemroot% and %systemdrive% (on Win XP). Expand
# it and remove some other windows-isms. The caller will do
# case_sensitive_path for us, so we don't need to do that.
sub is_dir_nocase
local $_;
my $dir = shift;
my $windir;
eval { $windir = $g->case_sensitive_path ($dir); };
if ($@) {
return 0;
return $g->is_dir ($windir);
# Download a named hive file. Die on failure.
sub download_hive
local $_;
my $hivefile = shift;
my $hiveshortname = shift;
my $winfile;
eval { $winfile = $g->case_sensitive_path ($hivefile); };
if ($@) {
die __x("virt-win-reg: {p}: file not found in guest: {err}\n",
p => $hivefile, err => $@);
warn "downloading $winfile ..." if $debug;
eval { $g->download ($winfile, "$tmpdir/$hiveshortname"); };
if ($@) {
die __x("virt-win-reg: {p}: could not download registry file: {err}\n",
p => $winfile, err => $@);
# Upload a named hive file. Die on failure.
sub upload_hive
local $_;
my $hiveshortname = shift;
my $hivefile = shift;
my $winfile;
eval { $winfile = $g->case_sensitive_path ($hivefile); };
if ($@) {
die __x("virt-win-reg: {p}: file not found in guest: {err}\n",
p => $hivefile, err => $@);
warn "uploading $winfile ..." if $debug;
eval { $g->upload ("$tmpdir/$hiveshortname", $winfile); };
if ($@) {
die __x("virt-win-reg: {p}: could not upload registry file: {err}\n",
p => $winfile, err => $@);
The program currently supports Windows NT-derived guests starting with
Windows XP through to at least Windows 7.
The following Registry keys are supported:
=over 4
where I<SID> is a Windows User SID (eg. C<S-1-5-18>).
=item C<HKEY_USERS\I<username>>
where I<username> is a local user name (this is a libguestfs extension).
You can use C<HKLM> as a shorthand for C<HKEY_LOCAL_MACHINE>, and
The literal keys C<HKEY_USERS\$SID> and C<HKEY_CURRENT_USER> are not
supported (there is no "current user").
C<virt-win-reg> expects that regedit files have already been reencoded
in the local encoding. Usually on Linux hosts, this means UTF-8 with
Unix-style line endings. Since Windows regedit files are often in
UTF-16LE with Windows-style line endings, you may need to reencode the
whole file before or after processing.
To reencode a file from Windows format to Linux (before processing it
with the I<--merge> option), you would do something like this:
iconv -f utf-16le -t utf-8 < win.reg | dos2unix > linux.reg
To go in the opposite direction, after exporting and before sending
the file to a Windows user, do something like this:
unix2dos linux.reg | iconv -f utf-8 -t utf-16le > win.reg
For more information about encoding, see L<Win::Hivex::Regedit(3)>.
If you are unsure about the current encoding, use the L<file(1)>
command. Recent versions of Windows regedit.exe produce a UTF-16LE
file with Windows-style (CRLF) line endings, like this:
$ file software.reg
software.reg: Little-endian UTF-16 Unicode text, with very long lines,
with CRLF line terminators
This file would need conversion before you could I<--merge> it.
=head1 CurrentControlSet etc.
Registry keys like C<CurrentControlSet> don't really exist in the
Windows Registry at the level of the hive file, and therefore you
cannot modify these.
C<CurrentControlSet> is usually an alias for C<ControlSet001>. In
some circumstances it might refer to another control set. The way
to find out is to look at the C<HKLM\SYSTEM\Select> key:
# virt-win-reg WindowsGuest 'HKLM\SYSTEM\Select'
"Current" is the one which Windows will choose when it boots.
Similarly, other C<Current...> keys in the path may need to
be replaced.
To delete a whole registry key, use the syntax:
To delete a single value within a key, use the syntax:
Note that some of these tips modify the guest disk image. The guest
I<must> be shut off, else you will get disk corruption.
Prepare a DOS batch script, VBScript or executable. Upload this using
L<guestfish(1)>. For this example the script is called C<test.bat>
and it is uploaded into C<C:\>:
guestfish -i -d WindowsGuest upload test.bat /test.bat
Prepare a regedit file containing the registry change:
cat > test.reg <<'EOF'
In this example we use the key C<RunOnce> which means that the script
will run precisely once when the first user logs in. If you want it
to run every time a user logs in, replace C<RunOnce> with C<Run>.
Now update the registry:
virt-win-reg --merge WindowsGuest test.reg
This section assumes you are familiar with Windows services, and you
either have a program which handles the Windows Service Control
Protocol directly or you want to run any program using a service
wrapper like SrvAny or the free RHSrvAny.
First upload the program and optionally the service wrapper. In this
case the test program is called C<test.exe> and we are using the
RHSrvAny wrapper:
guestfish -i -d WindowsGuest <<EOF
upload rhsrvany.exe /rhsrvany.exe
upload test.exe /test.exe
Prepare a regedit file containing the registry changes. In this
example, the first registry change is needed for the service itself or
the service wrapper (if used). The second registry change is only
needed because I am using the RHSrvAny service wrapper.
cat > service.reg <<'EOF'
=over 4
=item *
For use of C<ControlSet001> see the section above in this manual page.
You may need to adjust this according to the control set that is in
use by the guest.
=item *
C<"ObjectName"> controls the privileges that the service will have.
An alternative is C<"ObjectName"="LocalSystem"> which would be the
most privileged account.
=item *
For the meaning of the magic numbers, see this Microsoft KB article:
Update the registry:
virt-win-reg --merge WindowsGuest service.reg
Be careful when passing parameters containing C<\> (backslash) in the
shell. Usually you will have to use 'single quotes' or double
backslashes (but not both) to protect them from the shell.
Paths and value names are case-insensitive.
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
=head1 AUTHOR
Richard W.M. Jones L<>
Copyright (C) 2010 Red Hat Inc.
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