Bug#576537: Incorrect labels generated in /etc/fstab during PATA conversion

[Moritz Muehlenhoff <jmm@inutil.org>]

On Mon, Apr 05, 2010 at 04:48:13PM +0100, Ben Hutchings wrote:
> On Mon, 2010-04-05 at 16:12 +0200, Moritz Muehlenhoff wrote:
> > Package: linux-base
> > Version: 2.6.32-10
> > Severity: normal
> > 
> > The conversion on my Thinkpad X31 seems to have generated incorrect
> > labels, which lead to the home partition not being mounted automatically:
> 
> Oops.
> 
> > This is the /etc/fstab which was generated:
> > 
> > # /etc/fstab: static file system information.
> > #
> > # <file system> <mount point>   <type>  <options>       <dump>  <pass>
> > proc            /proc           proc    defaults        0       0
> > # /dev/hda1       /               ext3    defaults,errors=remount-ro 0       1
> > LABEL=\x2f       /               ext3    defaults,errors=remount-ro 0       1
> > # /dev/hda6       /home           ext3    defaults,noatime 0       2
> > LABEL=\x2fhome       /home           ext3    defaults,noatime 0       2
> > # /dev/hda5       none            swap    sw              0       0
> > UUID=0603958c-bb68-46df-940b-c562b9fdb4aa       none            swap    sw              0       0
> > /dev/fd0        /media/floppy0  auto    rw,user,noauto  0       0
> > /dev/sda        /stick          vfat    rw,user,noauto  0       0
> > 
> > The labels itself seem correct:
> > 
> > root@galadriel:~# e2label /dev/sda1
> > /
> > root@galadriel:~# e2label /dev/sda6
> > /home
> > root@galadriel:~#
> > 
> > I have no idea where "\x2f" instead of "/" is coming from?
> [...]
> 
> /sbin/blkid -o udev /dev/sda1 | grep ^ID_FS_LABEL_ENC
> 
> We definitely do need to escape whitespace and I thought libblkid would
> accept the escaped strings.  Evidently not.  I think we may just have to
> ignore labels with whitespace in, and go for UUIDs on those devices.
> (We already prefer UUIDs but it looks like those partitions don't have
> them.)

At least blkid shows a UUID:

root@galadriel:~# /sbin/blkid -o udev /dev/sda1
ID_FS_LABEL=/
ID_FS_LABEL_ENC=\x2f
ID_FS_UUID=6af102ec-0002-499f-b85d-193ecec7993e
ID_FS_UUID_ENC=6af102ec-0002-499f-b85d-193ecec7993e
ID_FS_SEC_TYPE=ext2
ID_FS_TYPE=ext3

Or was the code which prefers UUIDs over labels added post -10?

The "\x2f" encoding is applied through the blkid_encode_string() 
function from shlibs/blkid/src/encode.c of util-linux:

/**
 * blkid_encode_string:
 * @str: input string to be encoded
 * @str_enc: output string to store the encoded input string
 * @len: maximum size of the output string, which may be
 *       four times as long as the input string
 *
 * Encode all potentially unsafe characters of a string to the
 * corresponding hex value prefixed by '\x'.
 *
 * Returns: 0 if the entire string was copied, non-zero otherwise.
 **/
int blkid_encode_string(const char *str, char *str_enc, size_t len)

Maybe we should convert it back in linux-base.postinst?

Cheers,
        Moritz