As a showcase of how you can use qemu-io's exit code to determine
success or failure (same for qemu-img), this test is changed to use
qemu_io_silent() instead of qemu_io(), and to assert the exit code
instead of logging the filtered result.
One real advantage of this is that in case of an error, you get a
backtrace that helps you locate the issue in the test file quickly.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 20180509194302.21585-6-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
COR across nodes (that is, you have some filter node between the
actually COR target and the node that performs the COR) cannot reliably
work together with the permission system when there is no explicit COR
node that can request the WRITE_UNCHANGED permission for its child.
This is because COR (currently) sneaks its requests by the usual
permission checks, so it can work without a WRITE* permission; but if
there is a filter node in between, that will re-issue the request, which
then passes through the usual check -- and if nobody has requested a
WRITE_UNCHANGED permission, that check will fail.
There is no real direct fix apart from hoping that there is someone who
has requested that permission; in case of just the qemu-io HMP command
(and no guest device), however, that is not the case. The real real fix
is to implement the copy-on-read flag through an implicitly added COR
node. Such a node can request the necessary permissions as shown in
this test.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-id: 20180421132929.21610-10-mreitz@redhat.com
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
Max Reitz