LAB 4 IS DONE.

lab/boot/sign.pl

@@ -0,0 +1,23 @@
+#!/usr/bin/perl
+
+open(BB, $ARGV[0]) || die "open $ARGV[0]: $!";
+
+binmode BB;
+my $buf;
+read(BB, $buf, 1000);
+$n = length($buf);
+
+if($n > 510){
+	print STDERR "boot block too large: $n bytes (max 510)\n";
+	exit 1;
+}
+
+print STDERR "boot block is $n bytes (max 510)\n";
+
+$buf .= "\0" x (510-$n);
+$buf .= "\x55\xAA";
+
+open(BB, ">$ARGV[0]") || die "open >$ARGV[0]: $!";
+binmode BB;
+print BB $buf;
+close BB;