From: "Theodore Ts'o" <tytso@mit.edu>
To: Mike Fleetwood <mike.fleetwood@googlemail.com>
Cc: util-linux@vger.kernel.org
Subject: Re: blkid identifying whole disk ntfs as both ntfs and msdos partition table
Date: Tue, 2 Jul 2019 14:14:39 -0400 [thread overview]
Message-ID: <20190702181439.GB3032@mit.edu> (raw)
In-Reply-To: <CAMU1PDhRJRwawuSZ3x+NEAQx47afOhcSUw6wTsdcbNoz4th1hA@mail.gmail.com>
On Tue, Jul 02, 2019 at 11:43:34AM +0100, Mike Fleetwood wrote:
> Hi,
>
> Tested with mkntfs from ntfsprogs and blkid and wipefs from util-linux git HEAD.
> Test case:
>
> # mkntfs -Q -F /dev/sdb
> /dev/sdb is entire device, not just one partition.
> mkntfs forced anyway.
> Cluster size has been automatically set to 4096 bytes.
> Creating NTFS volume structures.
> mkntfs completed successfully. Have a nice day.
> # ./blkid --version
> lt-blkid from util-linux 2.34.24-e3bb9 (libblkid 2.34.24, 14-Jun-2019)
> # ./blkid /dev/sdb
> /dev/sdb: UUID="3B64D28A5CF89146" TYPE="ntfs" PTTYPE="dos"
> # ./wipefs /dev/sdb
> DEVICE OFFSET TYPE UUID LABEL
> sdb 0x3 ntfs 3B64D28A5CF89146
> sdb 0x1fe dos
So what we call the dos partition table, Microsoft calls the "boot
sector", and it's not necessarily a partition table at all. (Note
also that normally, Microsoft won't let you put an ntfs file system on
the whole disk --- and you had to force this with mkntfs -F. It's
actually a bad idea, because some versions of Windows will see what it
thinks is an empty disk, and the contents of that whole disk file
system can be very easily overwritten by a confused Windows OS.)
You can see this in include/layout.h in the ntfs-3g sources.
This is a pretty broad and general confusion; fdisk will get confused
and think it is an empty dos partition table, and blkid will as well.
I suspect the right answer here is if the oem_id is "NTFS ", we should
not consider it a dos partition table at all, even if there is an "end
of boot sector" magic value of 0xaa55 at the end of the sector.
- Ted
next prev parent reply other threads:[~2019-07-02 18:14 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-02 10:43 blkid identifying whole disk ntfs as both ntfs and msdos partition table Mike Fleetwood
2019-07-02 18:14 ` Theodore Ts'o [this message]
2019-07-02 19:06 ` Karel Zak
2019-07-17 11:16 ` Karel Zak
2019-07-18 20:10 ` Mike Fleetwood
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