#!/usr/bin/perl
#
# Guillaume Cottenceau (gc@mandrakesoft.com)
#
# Copyright 2002 MandrakeSoft
#
# This software may be freely redistributed under the terms of the GNU
# public license.
#
# 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.
#

sub arch() {
    my $t = `uname -m`;
    chomp $t;
    $t;
}
sub if_($@) {
    my $b = shift;
    $b or return ();
    wantarray || @_ <= 1 or die("if_ called in scalar context with more than one argument " . join(":", caller()));
    wantarray ? @_ : $_[0];
}
sub cat_ { local *F; open F, $_[0] or $_[1] ? die "cat of file $_[0] failed: $!\n" : return; my @l = <F>; wantarray ? @l : join '', @l }
sub member { my $e = shift; foreach (@_) { $e eq $_ and return 1 } 0 }

@known_boot_loaders = qw(lilo grub yaboot);

# keep this in sync with DrakX
@MBR_signatures = (
    [ 'empty', 0, "\0\0\0\0" ],
    [ 'grub', 0x6,  "GRUB" ],
    [ 'grub', 0, "\xEBG", 0x17d, "stage1 \0" ],
    [ 'grub', 0, "\xEBH", 0x17e, "stage1 \0" ],
    [ 'grub', 0, "\xEBH", 0x18a, "stage1 \0" ],
    [ 'grub', 0, "\xEBH", 0x181, "GRUB \0" ],
    [ 'lilo', 0x2,  "LILO" ],
    [ 'lilo', 0x6,  "LILO" ],
if_(arch() =~ /ppc/,
    map { [ 'yaboot', 0, "PM", 0x200 * $_ + 0x10, "bootstrap\0" ] } 0 .. 61
),
);

sub typeFromMagic {
    my $f = shift;
    local *F; sysopen F, $f, 0 or return;

    my $tmp;
  M: foreach (@MBR_signatures) {
	my ($name, @l) = @$_;
	while (@l) {
	    my ($offset, $signature) = splice(@l, 0, 2);
	    sysseek(F, $offset, 0) or next M;
	    sysread(F, $tmp, length $signature);
	    $tmp eq $signature or next M;
	}
	return $name;
    }
    return 0;
}


my (undef, undef, @parts) = cat_('/proc/partitions');

my @possibilities;

P: foreach (@parts) {
    my (undef, undef, $blocks, $dev) = split or next;
    next if $blocks <= 1;
    my $type = typeFromMagic("/dev/$dev");
    $type && member($type, @known_boot_loaders) and push @possibilities, [ $dev, $type ];
}

my $choice;

if (!@possibilities) {
    print "No known Linux bootloader has been found, nothing to do.\n";
} elsif (@possibilities == 1) {
    print "I've found a Linux bootloader only on </dev/$possibilities[0]->[0]>.\n\n";
    $choice = $possibilities[0];
} else {
    print "I've found the following Linux bootloaders:\n";
    my $i;
    print "\t", ++$i, ": <$_->[1]> \ton <$_->[0]>\n" foreach @possibilities;
    print "\n";
    print "Which disk/partition do you want to overwrite with the Windows bootloader?\n";
    print "\t<enter the number or press 'n' and Enter to cancel> ";
    <STDIN> !~ /^(\d+)$/i && $1 >= 1 and $choice = $possibilities[$1-1];
}

if ($choice) {
    print "I'm going to overwrite bootloader on </dev/$choice->[0]> with
Windows bootloader.

Ok? <press Enter to continue, 'n' and Enter to cancel> ";
    <STDIN> =~ /^n/i and exit 0;
    
    system("/bin/dd if=/usr/lib/extipl/aldebaran.bin of=/dev/$choice->[0]\n") and print "\tFailed!\n";
}

#-------------------------------------------------
#- $Log$
#- Revision 1.1  2002/02/27 13:31:30  gc
#- add "restore Windows Boot Loader" to rescue
#-
#-