Can't figure out how to use mnt_table_get_root_fs from libmount

[Amit <amit.uttam@gmail.com>]

Hello,

I have a simple program using libmount that simply gets the path of the
root filesystem. I can't seem to get it to work. I always get a
segmentation fault. There is probably something basic that I am missing
but can't figure it out.

#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <assert.h>

#include <libmount.h>

int main(int argc, char *argv[])
{
    struct libmnt_context *cxt;
    struct libmnt_table *tab;
    struct libmnt_fs *fs;

    /* Enable debugging */
    mnt_init_debug(0xffff);

    /* Create new mount context */
    cxt = mnt_new_context();
    if (!cxt)
        printf("Error creating new mount context\n");

    /* A mount table */
    if (mnt_context_get_mtab(cxt, &tab) < 0)
        printf("Error getting mtab\n");

    /* Get the root filesystem */
    if (mnt_table_get_root_fs(tab, &fs) == -1)
        printf("Error getting root fs from mount table\n");

    const char *src = mnt_fs_get_source(fs);

    char *root = mnt_pretty_path(src, NULL);
    printf("root filesystem source (pretty) %s\n", root);

    return 0;
}