mntctl/statfs congruency

congruent.c

#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
#include <sys/types.h>
#include <sys/mntctl.h>
#include <sys/vmount.h>
#include <sys/statfs.h>

int main(void) {
        int needsize, ret;
        struct vmount *mounts;
        struct statfs64 fs;
        mntctl (MCTL_QUERY, sizeof(needsize), &needsize);
        mounts = malloc(needsize);
        ret = mntctl (MCTL_QUERY, needsize, mounts);

        for (int i = 0; i < ret; i++) {
                statfs64 (vmt2dataptr(mounts, VMT_STUB), &fs);
                printf ("FS mounted on %s has a vmount.vmt_gfstype %d and statfs64.f_vfstype of %d\n", vmt2dataptr(mounts, VMT_STUB), mounts->vmt_gfstype, fs.f_vfstype);
                mounts = (void*)mounts + mounts->vmt_length;
        }

        return 0;
}