#!perl

use warnings;
use Digest::MD5;
use FileHandle;
use File::Basename;
use Win32;
use Win32::Clipboard;

my $md5 = Digest::MD5->new;
my $filename = $ARGV[0];
my $fh = new FileHandle;

if ($fh->open("< $filename")) {
    binmode $fh;  # we'll just assume
    $md5->addfile($fh);
} else {
    Win32::MsgBox("Could not read file $filename\nDoes it exist?", MB_ICONSTOP, "md5sum");
    exit;
}

my $digest = $md5->hexdigest;

my $CLIP = Win32::Clipboard();
$CLIP->Set($digest) or do {
    Win32::MsgBox("Could not set the clipboard. Things are strange here.", MB_ICONSTOP, "md5sum");
    exit;
};

my ($basename,undef,undef) = fileparse($filename);

Win32::MsgBox("The MD5 sum for file \'$basename\' is now in the clipboard:\n\n$digest", MB_ICONINFORMATION, "md5sum");

##</code><code>##

Windows Registry Editor Version 5.00

[HKEY_CLASSES_ROOT\*\shell\MD5 Sum]

[HKEY_CLASSES_ROOT\*\shell\MD5 Sum\command]
@="c:\\projects\\md5sum\\md5sum.exe \"%1\""