Recursively list directories in C

This is an example C program demonstrating recursively printing out directories using readdir. See dirent for the structure of a Unix directory entry.

#include <stdlib.h>
#include <stdio.h>
#include <sys/types.h>
#include <string.h>
#include <errno.h>
/* "readdir" etc. are defined here. */
#include <dirent.h>
/* limits.h defines "PATH_MAX". */
#include <limits.h>

/* List the files in "dir_name". */

static void
list_dir (const char * dir_name)
{
    DIR * d;

    /* Open the directory specified by "dir_name". */

    d = opendir (dir_name);

    /* Check it was opened. */
    if (! d) {
        fprintf (stderr, "Cannot open directory '%s': %s\n",
                 dir_name, strerror (errno));
        exit (EXIT_FAILURE);
    }
    while (1) {
        struct dirent * entry;
        const char * d_name;

        /* "Readdir" gets subsequent entries from "d". */
        entry = readdir (d);
        if (! entry) {
            /* There are no more entries in this directory, so break
               out of the while loop. */
            break;
        }
        d_name = entry->d_name;
        /* Print the name of the file and directory. */
	printf ("%s/%s\n", dir_name, d_name);

#if 0
	/* If you don't want to print the directories, use the
	   following line: */

        if (! (entry->d_type & DT_DIR)) {
	    printf ("%s/%s\n", dir_name, d_name);
	}

#endif /* 0 */


        if (entry->d_type & DT_DIR) {

            /* Check that the directory is not "d" or d's parent. */
            
            if (strcmp (d_name, "..") != 0 &&
                strcmp (d_name, ".") != 0) {
                int path_length;
                char path[PATH_MAX];
 
                path_length = snprintf (path, PATH_MAX,
                                        "%s/%s", dir_name, d_name);
                printf ("%s\n", path);
                if (path_length >= PATH_MAX) {
                    fprintf (stderr, "Path length has got too long.\n");
                    exit (EXIT_FAILURE);
                }
                /* Recursively call "list_dir" with the new path. */
                list_dir (path);
            }
	}
    }
    /* After going through all the entries, close the directory. */
    if (closedir (d)) {
        fprintf (stderr, "Could not close '%s': %s\n",
                 dir_name, strerror (errno));
        exit (EXIT_FAILURE);
    }
}

int main ()
{
    list_dir ("/usr/share/games");
    return 0;
}

(download)

The output of the example looks like this:

/usr/share/games/.
/usr/share/games/..
/usr/share/games/fortune
/usr/share/games/fortune
/usr/share/games/fortune/.
/usr/share/games/fortune/..
/usr/share/games/fortune/fortunes
/usr/share/games/fortune/fortunes.dat
/usr/share/games/fortune/freebsd-tips
/usr/share/games/fortune/freebsd-tips.dat
/usr/share/games/fortune/gerrold.limerick
/usr/share/games/fortune/gerrold.limerick.dat
/usr/share/games/fortune/limerick
/usr/share/games/fortune/limerick.dat
/usr/share/games/fortune/murphy
/usr/share/games/fortune/murphy-o
/usr/share/games/fortune/murphy-o.dat
/usr/share/games/fortune/murphy.dat
/usr/share/games/fortune/startrek
/usr/share/games/fortune/startrek.dat
/usr/share/games/fortune/zippy
/usr/share/games/fortune/zippy.dat