[Libguestfs] [PATCH 2/2] New API: pwrite-device

[Richard W.M. Jones]

On Sun, Sep 26, 2010 at 07:55:03PM +0100, Richard W.M. Jones wrote:
> +   [InitPartition, Always, TestOutputList (
> +      [["pwrite_device"; "/dev/sda"; "\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000"; "446"];
> +       ["blockdev_rereadpt"; "/dev/sda"];
> +       ["list_partitions"]], [])],

This test probably deserves some more explanation.

InitPartition creates a single partition (/dev/sda1) for the test
environment.

The test code then zaps the MBR partition table, overwriting the table
and the signature with all zeroes.  This Wikipedia page is a helpful
reference:
https://secure.wikimedia.org/wikipedia/en/wiki/Master_Boot_Record

We then tell the kernel to reread the partition table, and list the
partitions (which, being zapped, we expect to be an empty list).

Rich.

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