#!/usr/bin/env perl
use warnings;
use strict;
use File::Spec;
use Getopt::Std;
use Fcntl;
use constant BUF_SIZE => 1024 * 1024 * 5;
require 'syscall.ph';

my %opts;

getopts( 'd:', \%opts );

die 'option -d <DIRECTORY> is required'
  unless ( ( exists( $opts{d} ) ) and ( defined( $opts{d} ) ) );

sysopen( my $fd, $opts{d}, O_RDONLY | O_DIRECTORY );
open( my $out, '>:raw', 'perldata.bin' ) or die $!;

while (1) {

    my $buf = "\0" x BUF_SIZE;
    my $read = syscall( &SYS_getdents, fileno($fd), $buf, BUF_SIZE );

    if ( ( $read == -1 ) and ( $! != 0 ) ) {
        die "failed to syscal getdents: $!";
    }

    print $out($buf);
    close($out);
    last;

=pod
    last if ( $read == 0 );

    while ( $read != 0 ) {
        my ( $ino, $off, $len, $name ) = unpack( "LLSZ*", $buf );

        unless ( ( $name eq '.' ) or ( $name eq '..' ) ) {
            my $path = File::Spec->catfile( $opts{d}, $name );
            print $path,"\n";
        }
        substr( $buf, 0, $len ) = '';
        $read -= $len;
    }
=cut

}