Re: Reading cfdisk partitioned drives

[Matt Davis]

On 5/26/07, Otavio Salvador <address@hidden> wrote:
> "Matt Davis" <address@hidden> writes:
>
> > The oddity that I have have seen, and I am not sure if this is what is
> > causing the funky-ness in #14, but fdisk/cfdisk both read the fs_type
> > from the disk properly.  In my case (using parted 1.8.7), bootsector.c
> > is reading the first 512 bytes of the Fat16 partition starting at 63.
> > Parted, and I have confirmed this via gdb, does not see a boot sector
> > signature starting at those partition offsets, thus when I run parted
> > on the drive I get output with proper drive sizes but no file system
> > information for those drives.  Further, to see if there was any data
> > on that boot sector at all, I performed:
> > `dd if=/dev/hda1 of=boot bs=512 count=1`  And the boot sector was all
> > zeroed out.  Either way that's far off from the 0xAA55 that a fat16
> > should have.  But that still does not explain why fdisk and cfdisk
> > report the fs_types properly.  I assume they are just grabbing those
> > values from the MBR and not the actual boot sector of the hard drive
> > (as parted is doing).
>
> I'm missed here. Have you been able to reproduce it? If yes, that's
> great!

Nope, unable to reproduce it.

> A possible why to get more information about the bug itself is ask for
> the reporters to send the boot sector to us. Can you try it? This way
> we can confirm your guess, can't we?

But I did extract the boot sector from the partition
had to use "dd if=/dev/hda of=blah seek=1 bs=512 count=1"
That had a proper boot signature as well.  But when
fat_bootsector_read() pulls out that same (or what should be that same
piece of data) it gets all zeros.

-Matt