You didn't really ask a question, so I assumed that you were wondering how to fix the C code to get it to do what you want. It looks like you copy/pasted code from different sources or examples online (by the looks of it). In your listfiles() function, you're using argc, argv which is wrong (those are command line arguments, which belong to a main() function in a program. They don't have any use inside of a non-entry-point library, which is essentially what you've got here). I changed the parameter list to a single const char * dir, then changed the argv[1] to dir. I've inserted comments in the C code of what was changed:

#!/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); } whil
+e (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

[download]

Output:

one.txt
two.txt

[download]

Now, if you want to be able to send in a directory as an argument, do it in Perl:

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

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

...

[download]

You may want to do extra argument checking in Perl, or you can just let the back end report any issues with bad dir names.

In reply to Re: using syscalls in perl through inline c by stevieb
in thread using syscalls in perl through inline c by ofer

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.