mount_msdosfs -L ... [odd behaviour ?]

[Chuck Swiger]

Hi, Dan--

On Oct 28, 2010, at 3:45 PM, dan wrote:
> 'mount_msdosfs -L en_US.UTF-8 /dev/da0 local/mnt/'
> 
> executed by a non root-user prints out the following
> 
> "mount_msdosfs: msdosfs_iconv: Operation not permitted"
> 
> and then stops with error 71 on console.
> 
> Later, the same command, executed by the same user, completes correctly if some time before the root user has succesfully issued it and unmounted the device.
> 
> Any clues ? Things I am probably missing ? Does Anyone else notice this (odd) behaviour (if it is odd) ?

It's probably coming from /usr/src/sbin/mount_msdosfs/mount_msdosfs.c:

          if (set_charset(&iov, &iovlen, cs_local, cs_dos) == -1)
            err(EX_OSERR, "msdosfs_iconv");

...since set_charset() tries to load the msdosfs_iconv & libiconv kernel modules:

    if (modfind("msdosfs_iconv") < 0)
        if (kldload("msdosfs_iconv") < 0 || modfind("msdosfs_iconv") < 0) {
            warnx("cannot find or load \"msdosfs_iconv\" kernel module");
            return (-1);
        }

kldload() fails with EPERM if you are not root:

     [EPERM]            You do not have access to read the file or link it
                        with the kernel.  You should be the root user to be
                        able to use the kld system calls.

Once root has loaded these modules, you can invoke mount_msdosfs as a normal user because they are already available.  You can put "kldload msdosfs_iconv" into /etc/rc.local, or maybe tweak /boot/loader.conf to load these at boot if you prefer.

Regards,
-- 
-Chuck