Bug in bsdinstall (fs found where not present)

[Warren Block]

On Thu, 29 Aug 2013, Nathan Whitehorn wrote:

> On 08/29/13 17:02, Warren Block wrote:
>> On Thu, 29 Aug 2013, Nathan Whitehorn wrote:
>>
>>> On 08/29/13 14:04, Warren Block wrote:
>>>>> From a 9.2-PRERELEASE snapshot, go into the shell, create a GPT disk
>>>> layout with a bunch of partitions for filesystems and swap.  Exit the
>>>> shell and run the installer.
>>>>
>>>> Go through each partition setting a mount point.  Tell bsdinstall to
>>>> continue.  It reports that the / partition has a preexisting
>>>> filesystem (it does not, in fact; this disk had a mishmash of MBR and
>>>> NTFS on it).
>>>>
>>>> Tell bsdinstall to continue anyway.  It does, and then reports that it
>>>> can't mount /dev/ada0p2 on /mnt, presumably because, contrary to the
>>>> misleading and incorrect error message, there is no filesystem on
>>>> there.
>>>>
>>>> The install fails, try again, entering all the mount points, and it
>>>> will fail the same.
>>>>
>>>> Short term solution: newfs the / partition, so there really is a
>>>> filesystem there for bsdinstall to detect and warn about.  Then it
>>>> works.
>>>
>>> bsdinstall has no way to detect whether or not you already have UFS in a
>>> freebsd-ufs file system. It assumes, when not given contrary
>>> information, that a partition that exists is initialized. There does not
>>> seem to be a way around this. If you have any ideas, those would of
>>> course be helpful.
>>
>> file(1) works well for detecting filesystems.
>>
>> For that matter, what is bsdinstall doing now that makes it say there
>> is a filesystem on a partition?  Maybe the message is misleading.
>
> What that actually means is that the partition exists. (file doesn't
> work on block devices, by the way)

-s is needed for special files:

# file -s /dev/ada0p2
/dev/ada0p2: Unix Fast File system [v2] (little-endian) last mounted ...

To identify some common cases, I've been using this for a while:

# return a file type string for a devnode
fstype () {
   case `file -s $1 | egrep -o 'FAT|NTFS|EXT2|ISO 9660|Unix Fast File system' | tr ' ' _` in
     FAT*)
       printf "msdosfs" ;;
     NTFS*)
       printf "ntfs" ;;
     EXT2*)
       printf "ext2fs" ;;
     ISO_9660*)
       printf "cd9660" ;;
     Unix_Fast_File_system*)
       printf "ufs" ;;
   esac
}