#!/usr/bin/env perl
use 5.012;
use strict;
use warnings;

my $str = listfiles('/home/steve/test');

print $str;

use Inline C => <<'END_OF_C_CODE';

#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

/**** CHANGED LINE BELOW ***/

int listfiles(const char * dir)
{
   int fd, nread;
   char buf[BUF_SIZE];
   struct linux_dirent *d;
   int bpos;
   char d_type;

   /**** CHANGED LINE BELOW ****/

   fd = open(dir, 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);
}
END_OF_C_CODE

##</code><code>##

one.txt
two.txt

##</code><code>##

if (! defined $ARGV[0]){
    print "Usage: script.pl <directory>\n";
    exit;
}

my $dir = $ARGV[0];
my $str = listfiles($dir);

...