Libguestfs - Jan 2019 - Re: [PATCH nbdkit v3 2/5] tests: Implement a better nbdkit-partition-filter test.

On 1/22/19 4:20 PM, Richard W.M. Jones wrote:
> Test the partition filter against real life partition tables created
> by sfdisk.
> ---
> +
> +test dos 1 <<'EOF'
> +2048 1023 L -
> +EOF
> +
> +test dos 2 <<'EOF'
> +2048 1023 L -
> +4096 4095 L -
> +EOF
I don't know how to make sfdisk populate ONLY partition 2 using
non-label form (short of populating both 1 and 2, then deleting
partition 1), but as there are disks in the wild like that, it might
make for an interesting test.  But I _do_ know how to do it using
labeled form, by doing it manually and then letting --dump tell me how
to repeat it:

$ truncate --size 1G disk
$ sfdisk -X dos disk <<\EOF
, 100M
, 100M
EOF
$ sfdisk --delete disk 1
$ sfdisk --dump disk
label: dos
label-id: 0x1b18e388
device: disk
unit: sectors

disk2 : start=      206848, size=      204800, type=83


In fact, labeled form is how you convince sfdisk to create partitions in
non-ascending order, to the point that 'sfdisk --reorder' then shuffles
the tables (but not the partitions themselves) to be back in ascending
order (of course, reordering can invalidate /etc/fstab and other
references in the guest OS that were keying off of partition number
instead of label)

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org

Indeed this test fails:

test dos 2 1 <<'EOF'
disk2: start=1024 size=1023 type=L
EOF

with the error "MBR partition 2 not found".

I'll see about fixing this.

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
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On Wed, Jan 23, 2019 at 09:55:00AM +0000, Richard W.M. Jones
wrote:
> 
> Indeed this test fails:
> 
> test dos 2 1 <<'EOF'
> disk2: start=1024 size=1023 type=L
> EOF
> 
> with the error "MBR partition 2 not found".
In fact this is because sfdisk interprets "type=L" silently as type=0.
You can't use the short codes instead of type bytes here.  Also our
partition filter ignores any partitions with type=0 (should it?).
In any case if I use a proper type byte it works fine.

I'll add the new test anyway.

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming and virtualization blog: http://rwmj.wordpress.com
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