#define _GNU_SOURCE
#include <dirent.h>     /* Defines DT_* constants */
#include <fcntl.h>
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <sys/syscall.h>

#define handle_error(msg) \
       do { perror(msg); exit(EXIT_FAILURE); } while (0)

struct linux_dirent {
   long           d_ino;
   off_t          d_off;
   unsigned short d_reclen;
   char           d_name[];
};

#define BUF_SIZE 1024*1024*5

int
main(int argc, char *argv[])
{
   int fd, nread;
   char buf[BUF_SIZE];
   struct linux_dirent *d;
   int bpos;
   char d_type;

   fd = open(argc > 1 ? argv[1] : ".", O_RDONLY | O_DIRECTORY);
   if (fd == -1)
       handle_error("open");

   for ( ; ; ) {
       nread = syscall(SYS_getdents, fd, buf, BUF_SIZE);
       if (nread == -1)
           handle_error("getdents");

       if (nread == 0)
           break;

       for (bpos = 0; bpos < nread;) {
           d = (struct linux_dirent *) (buf + bpos);
           if (d->d_ino != 0) printf("%s\n", (char *) d->d_name);
           bpos += d->d_reclen;
       }
   }

   exit(EXIT_SUCCESS);
}

##</code><code>##

struct linux_dirent {
   unsigned long  d_ino;     /* Inode number 32*/
   unsigned long  d_off;     /* Offset to next linux_dirent 32*/
   unsigned short d_reclen;  /* Length of this linux_dirent 16*/
   char           d_name[];  /* Filename (null-terminated) */
                     /* length is actually (d_reclen - 2 -
                        offsetof(struct linux_dirent, d_name)) */
}

##</code><code>##

#!/usr/bin/env perl
use warnings;
use strict;
use Cwd;
use File::Spec;
use Data::Dumper;
use Fcntl;
use Convert::Binary::C;
use constant BUF_SIZE => 4096;
use lib
'/home/myself/perl5/perls/perl-5.20.1/lib/site_perl/5.20.3/i686-linux/sys';
require 'syscall.ph';

my $dir = File::Spec->catdir( getcwd(), 'test' );
sysopen( my $fd, $dir, O_RDONLY | O_DIRECTORY );
my $buf = "\0" x 128;
$! = 0;
my $converter = Convert::Binary::C->new();
my $struct = <<CODE;
  struct foo {
    long d_ino;
    unsigned long d_off;
    unsigned short d_reclen;
    char d_name[];
  };
CODE
$converter->parse($struct);
my $read = syscall( &SYS_getdents, fileno($fd), $buf, BUF_SIZE );

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

#print Dumper($read), "\n";
#print Dumper($buf), "\n";
close($fd);
my $data = $converter->unpack( 'foo', $buf );
print Dumper($data);

##</code><code>##

#!/usr/bin/env perl
use warnings;
use strict;
use File::Spec;
use Getopt::Std;
use Fcntl;
use constant BUF_SIZE => 4096;
use lib
'/home/myself/perl5/perls/perl-5.20.1/lib/site_perl/5.20.3/i686-linux/sys';
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 );

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: $!";
    }

    last if ( $read == 0 );

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

        #print $name, "\n" if ( $ino != 0 );
        unless ( ( $name eq '.' ) or ( $name eq '..' ) ) {
            my $path = File::Spec->catfile( $opts{d}, $name );
            unlink $path or die "Cannot remove $path: $!";
        }
        substr( $buf, 0, $len ) = '';
        $read -= $len;
    }

}

close($fd);