ioctl: Make data object usable from python

[benzea]

So, things are not usable from python. Thing still broken:

• We need the old _ref/_unref functions for API compatibility if we use a GObject, not sure how to do that. Or can we use a boxed type?
• The length of data is not tagged in the GIR

So, kinda works, but you can't actually read the memory. And, not sure if maybe a ctypes.memmove shouldn't be workable instead.

The bindings cannot deal with a struct object, as it is not a boxed type and it'll try to ref/unref using g_object_ref. Probably this is fixable in another way, but this works.

Also, the python bindings cannot modify the byte data directly, so add an update method that is essentially a glorified memcpy.

[martinpitt]

Marking as draft until this works. Thanks!

[benzea]

This works now, I believe. Adding the update/retrieve methods isn't really elegant, but I couldn't convince vala to put the array lenght information into the GIR information correctly (no idea if that is even possible). And even if, we still need something like the update method anyway.

[benzea]

OK, also verified that the libusb tests still work fine after the ABI change (without recompile).

[benzea]

Do you have some example how to use this? I'm happy to help with turning that into a test in test-umockdev.py. Is that parallel to t_ioctl_custom() in test-umockdev-vala.vala? Otherwise I'm afraid this will just bitrot and get broken.

Yeah, a short test would be good, and something parallel to t_ioctl_custom is the right thing, yes. I think we can do something really minimal that just uses the new retrieve/update functions.

Yeah, it is pretty simple. My "existing user" was looking again a bit into the thermald test setup that I was hacking on at one point. Where I have the following code:

...
        self.acpi_thermal_rel_handler = UMockdev.IoctlBase()
        self.acpi_thermal_rel_handler.connect("handle-ioctl", self.acpi_thermal_rel_ioctl)

        self.testbed.attach_ioctl('/dev/acpi_thermal_rel', self.acpi_thermal_rel_handler)
...

    def acpi_thermal_rel_ioctl(self, handler, client):
        request = client.get_request()

        if request in (ioctls.ACPI_THERMAL_GET_ART_COUNT, ioctls.ACPI_THERMAL_GET_ART_LEN, ioctls.ACPI_THERMAL_GET_ART):
            print('ART')
            if self.acpi_art[0] < 0:
                client.complete(-1, -self.acpi_art[0])
                return True

            arg = client.get_arg()

            if request == ioctls.ACPI_THERMAL_GET_ART_COUNT:
                i = struct.pack('l', self.acpi_art[0])
                data = arg.resolve(0, len(i));
                data.update(0, i)
            elif request == ioctls.ACPI_THERMAL_GET_ART_LEN:
                i = struct.pack('l', len(self.acpi_art[1]))
                data = arg.resolve(0, len(i));
                data.update(0, i)
            elif request == ioctls.ACPI_THERMAL_GET_ART:
                data = arg.resolve(0, len(self.acpi_art[1]))
                data.update(0, self.acpi_art[1])

            client.complete(0, 0)
            return True

        elif request in (ioctls.ACPI_THERMAL_GET_TRT_COUNT, ioctls.ACPI_THERMAL_GET_TRT_LEN, ioctls.ACPI_THERMAL_GET_TRT):
            if self.acpi_trt[0] < 0:
                client.complete(-1, -self.acpi_trt[0])
                return True

            arg = client.get_arg()

            if request == ioctls.ACPI_THERMAL_GET_TRT_COUNT:
                i = struct.pack('l', self.acpi_trt[0])
                data = arg.resolve(0, len(i));
                print('TRT COUNT user side is:', data.retrieve(0))
                data.update(0, i)
            elif request == ioctls.ACPI_THERMAL_GET_TRT_LEN:
                i = struct.pack('l', len(self.acpi_trt[1]))
                data = arg.resolve(0, len(i));
                data.update(0, i)
            elif request == ioctls.ACPI_THERMAL_GET_TRT:
                data = arg.resolve(0, len(self.acpi_trt[1]))
                data.update(0, self.acpi_trt[1])

            client.complete(0, 0)
            return True

        return False

Let me see if I can hack up something quickly

[benzea]

Very cool, thank you!

I am a bit disappointed at myself for not checking the python (or GIR) output properly before the ioctl stuff got merged ... :-)

[benzea]

Hmm, should i merge this, or do you want to do so before the next time you make a release?

[martinpitt]

Ah sorry -- I wasnt' sure if you are done with this. Sure!

[benzea]

Nah, I think it is ready, and simply had forgotten about it again :-)