#!/usr/bin/perl -w
# 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 Win::Hivex;
use Win::Hivex::Regedit qw(reg_import reg_export);

use Pod::Usage;
use Getopt::Long;

=encoding utf8

=head1 NAME

hivexregedit - Merge and export Registry changes from regedit-format files.

=head1 SYNOPSIS

 hivexregedit --merge [--prefix prefix] [--encoding enc] \
         hivefile [regfile]

 hivexregedit --export [--prefix prefix] hivefile key > regfile

=head1 DESCRIPTION

Please note hivexregedit is a low-level tool for manipulating hive
files directly.  To merge or export registry changes to Windows
virtual machines it's better to use L<virt-win-reg(1)>.

Given a local binary ("hive") file, there are two modes.  C<--merge>
imports (merges) changes from a regedit-format file into the hive.  It
is similar to using the C</s> switch in Windows regedit.exe.

C<--export> exports a Registry key (recursively) into the regedit format.

=head2 ENCODING

C<hivexregedit> expects that regedit files have already been re-encoded
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 re-encode the
whole file before or after processing.

To re-encode a file from Windows format to Linux (before processing it
with the C<--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 using C<--export> 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 C<--merge> it.

=head2 SHELL QUOTING

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.

=head2 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:

 $ hivexregedit --export SYSTEM '\Select'
 [\Select]
 "Current"=dword:00000001
 "Default"=dword:00000001
 "Failed"=dword:00000000
 "LastKnownGood"=dword:00000002

"Current" is the one which Windows will choose when it boots.

Similarly, other C<Current...> keys in the path may need to
be replaced.

=head1 EXAMPLE

 $ virt-cat WindowsGuest /Windows/System32/config/software > software.hive
 $ hivexregedit --export \
     --prefix 'HKEY_LOCAL_MACHINE\SOFTWARE' \
     software.hive '\Microsoft' > ms-keys.reg

 $ hivexregedit --merge system.hive \
     --prefix 'HKEY_LOCAL_MACHINE\SYSTEM' additions.reg

=head1 OPTIONS

=over 4

=cut

my $help;

=item B<--help>

Display help.

=cut

my $debug;

=item B<--debug>

Enable debugging in the hivex library.  This is useful for diagnosing
bugs and also malformed hive files.

=cut

my $merge;

=item B<--merge>

 hivexregedit --merge [--prefix prefix] [--encoding enc] \
         hivefile [regfile]

Merge C<regfile> (a regedit-format text file) into the hive
C<hivefile>.  If C<regfile> is omitted, then the program reads from
standard input.  (Also you can give multiple input files).

C<--prefix> specifies the Windows Registry prefix.  It is almost
always necessary to use this when dealing with real hive files.

C<--encoding> specifies the encoding for unmarked strings in the
input.  It defaults to C<UTF-16LE> which should work for recent
versions of Windows.  Another possibility is to use C<ASCII>.

=cut

my $export;

=item B<--export>

 hivexregedit --export [--prefix prefix] hivefile key > regfile

C<key> is a path within the hive C<hivefile>.  (The key should not
contain any prefix and should be quoted to defend backslashes from the
shell).  The key is exported, recursively, to standard output in the
textual regedit format.

C<--prefix> specifies the Windows Registry prefix.  It is almost
always necessary to use this when dealing with real hive files.

=cut

my $prefix;

=item B<--prefix> prefix

Hive files and Windows Registry key names are indirectly related.  For
example, inside the software hive, all keys are stored relative to
C<HKEY_LOCAL_MACHINE\SOFTWARE>.  Thus
C<HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft> appears in the hive file as
C<\Microsoft>.

The hive format itself does not store this prefix, so you have to
supply it based on outside knowledge.  (L<virt-win-reg(1)>, amongst
other things, already knows about this).

Usually it is sufficient to pass the parameter
C<--prefix 'HKEY_LOCAL_MACHINE\SOFTWARE'> or similar when doing
merges and exports.

=cut

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.

=back

=cut

GetOptions ("help|?" => \$help,
            "debug" => \$debug,
            "merge|import" => \$merge,
            "export" => \$export,
            "prefix=s" => \$prefix,
            "encoding=s" => \$encoding,
    ) or pod2usage (2);
pod2usage (1) if $help;

if ($merge && $export) {
    die "hivexregedit: cannot use --merge and --export at the same time\n"
}

unless ($merge || $export) {
    die "hivexregedit: use --merge or --export, see the manpage for help\n"
}

if ($export && defined $encoding) {
    die "hivexregedit: --encoding has no effect when used with --export\n"
}

if ($merge) {                   # --merge (reg_import)
    if (@ARGV < 1) {
        die "hivexregedit --merge hivefile [input.reg ...]\n"
    }

    my $hivefile = shift @ARGV;

    my $h = Win::Hivex->open ($hivefile, write => 1, debug => $debug);

    # Read from stdin unless other files have been specified.
    unshift (@ARGV, '-') unless @ARGV;

    foreach (@ARGV) {
        open FILE, $_ or die "$_: $!";
        reg_import (\*FILE, sub {
            local $_ = shift;
            # Remove prefix from the start of the path, matching
            # case insensitively.
            if (defined $prefix) {
                my $len = length $prefix;
                if (length $_ >= $len &&
                    lc (substr ($_, 0, $len)) eq lc ($prefix)) {
                    $_ = substr ($_, $len);
                }
            }
            ($h, $_)
        });
    }

    $h->commit (undef);
} else {                        # --export (reg_export)
    if (@ARGV != 2) {
        die "hivexregedit --export hivefile key\n"
    }

    my $hivefile = shift @ARGV;
    my $key = shift @ARGV;

    my $h = Win::Hivex->open ($hivefile, debug => $debug);

    print "Windows Registry Editor Version 5.00\n\n";

    reg_export ($h, $key, \*STDOUT, prefix => $prefix);
}

=head1 SEE ALSO

L<virt-win-reg(1)>,
L<Win::Hivex::Regedit(3)>,
L<Win::Hivex(3)>,
L<hivexsh(1)>,
L<dos2unix(1)>,
L<unix2dos(1)>,
L<iconv(1)>,
L<http://libguestfs.org/>.

=head1 AUTHOR

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

=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.