#!/usr/bin/perl -w

# From: Dean Gaudet <dean@arctic.org>
#
# cheap hack that sits in a pipeline to do bandwidth limiting...
# use it for stuff like:
#
# tar cf - . | throttle 12 1024 | ssh remote 'cd dest; tar xBf -'

use strict;

$#ARGV == 1 || die "usage: $0 kbytes-per-sec buffer-size\n";

my $kbytes = shift;
my $bufsiz = shift;

my $interpacket_delay = ($bufsiz/1024.0)/$kbytes;

my $buf;
my $total = 0;
while (sysread(STDIN, $buf, $bufsiz) > 0) {
    while ($buf ne '') {
    	my $amt = syswrite(STDOUT, $buf);
	defined($amt) || die "error writing: $!\n";
	$total += $amt;
	printf STDERR "%15u\r", $total;
	$buf = substr($buf,$amt);
    }
    select(undef, undef, undef, $interpacket_delay);
}