Discerning between files and folders on a shared drive under Linux

Question

I am trying to list all the files in a certain directory on a shared drive using the following code:

#include <iostream>
#include <string>

#include "dirent.h"

int main ()
{
    DIR *directoryHandle = opendir("./temp/");
    if (NULL != directoryHandle)
    {
        dirent *entry = readdir(directoryHandle);
        while (NULL != entry)
        {
            //skip directories and select only files (hopefully)
            if ((DT_DIR != entry->d_type) && (DT_REG == entry->d_type || DT_UNKNOWN == entry->d_type))
            {
                std::cout << "Name: " << entry->d_name << " Type:" << std::to_string(entry->d_type) << std::endl;
            }

            //go to next entry
            entry = readdir(directoryHandle);
        }
        closedir(directoryHandle);
    }

    return 0;
}

The problem is that entry->d_type contains DT_UNKNOWN for directories as well as for files in the ./temp/ directory.

Is there any (reliable) linux-specific way to try and read each entry and determine if it's a file or directory?

The output of cat /etc/SuSE-release is:

SUSE Linux Enterprise Desktop 11 (x86_64) VERSION = 11 PATCHLEVEL = 1

The Linux version is: 2.6.32.59-0.7-default

Still, I expect this code to work on other platforms as well.

What does "shared drive" mean here? smb,nfs, sshfs etc.? oh and you are confusing the kernel version with the distro version. — PlasmaHH, Sep 11 '12 at 15:01
Ups... I'm not that experienced with the Linux system. The output of `df -T` indicates `nfs4` for that drive. — Mihai Todor, Sep 11 '12 at 15:04

pb2q · Accepted Answer · 2012-09-11T22:04:12.897

6

Use stat. You'll get a struct stat with an st_mode field, and macros S_ISDIR/S_ISREG:

isDirectory = S_ISDIR(statBuf.st_mode);
isFile = S_ISREG(statBuf.st_mode);

See man 2 stat. Include sys/stat.h.

edited Sep 11 '12 at 22:04

answered Sep 11 '12 at 15:08

pb2q

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score 5 · Answer 2 · answered Sep 11 '12 at 15:08

5

If you are getting DT_UNKNOWN you're going to have to go ahead and call lstat() and inspect the st_mode field to determine if this is a file, directory, or symlink. If you don't care about symlinks, use stat() instead.

answered Sep 11 '12 at 15:08

Hasturkun

35,395
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score 3 · Answer 3 · edited Sep 11 '12 at 15:09

3

There's the boost filesystem library that has a command is_directory. Using such a library would certainly make the code work on other platforms as well but I'm not sure if it will work for your specific problem.

edited Sep 11 '12 at 15:09

Fred Foo

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answered Sep 11 '12 at 15:06

denahiro

1,211
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10

I prefer not to create a dependency on boost::filesystem at this point... – Mihai Todor Sep 11 '12 at 15:07
+1 for Boost::FS, it's a great library and much easier to use than `dirent.h`. – Fred Foo Sep 11 '12 at 15:09
@MihaiTodor Well that's a design choice and it's your design so that's that. I think I'm sometimes a bit trigger happy when including boost libraries. – denahiro Sep 11 '12 at 15:14

Software_Designer · Answer 4 · 2012-09-11T15:17:32.687

Give this a try. It list files in a directory minus the folders :

#include <dirent.h> 
#include <stdio.h> 
# include <sys/types.h>
# include <sys/mode.h>
# include <stat.h>

DIR           *d;
struct dirent *dir;
struct stat s;
d = opendir("./temp/");

if (d)
{
  while ((dir = readdir(d)))
  {
    if (stat(dir->d_name,&s) != 0) {
        /* is this a regular file? */
        if ((s.st_mode & S_IFMT) == S_IFREG)
            printf("%s\n", dir->d_name);

    }
  }
  closedir(d);
}

score -2 · Answer 5 · answered Jan 29 '14 at 02:25

-2

unsigned char isFolder =0x4;
DIR Dir;
struct dirent *DirEntry;
Dir = opendir("c:/test/")

while(Dir=readdir(Dir))
{
    cout << DirEntry->d_name;
    if ( DirEntry->d_type == isFolder)
    {
    cout <<"Found a Directory : " << DirEntry->d_name << endl;
    } 
}

answered Jan 29 '14 at 02:25

user3247032

1

So, how's this different from my code? DT_DIR is defined as 0x4... – Mihai Todor Jan 29 '14 at 08:59

Discerning between files and folders on a shared drive under Linux

5 Answers5