Re: Mojave User Space Virtual Driver (HAL plugin) and enabling Microphone input
Re: Mojave User Space Virtual Driver (HAL plugin) and enabling Microphone input
- Subject: Re: Mojave User Space Virtual Driver (HAL plugin) and enabling Microphone input
- From: email@hidden
- Date: Wed, 22 May 2019 12:05:41 +0100
Hi Eric,
Thank you for your quick feedback. I really apologise for having to ask this
question, but can you confirm your drivers do actually read input via the core
audio API on Mojave, when part of the /usr/sbin/coreaudiod daemon? I ask
because this is specifically a Mojave issue, so any driver you wrote that
worked in the past may have stopped working since Mojave. I did debug through
my driver to find the samples coming out of the core audio api were
unexpectedly silent, and did prove the same audio interface does work with a
micro-phone-authorisation-enabled app. So the only reason I currently see for
the samples received by the driver to be silent, but only on Mojave, is lack of
micro-phone usage permission.
Can anyone else confirm Eric’s assertion that this should work without explicit
user permission on Mojave?
Best Regards,
Nicolas
> On 22 May 2019, at 10:05, Eric Gorouben <email@hidden> wrote:
>
>
> Hi Nicolas
>
> As far as I know, it is possible, and there is no necessary workaround. I’ve
> written drivers for many devices using this API, and never had this problem.
> There is probably another problem in your implementation.
>
> Good luck
> Eric Gorouben
>
>> Le 22 mai 2019 à 10:51, email@hidden <mailto:email@hidden> a écrit :
>>
>> Hello esteemed colleagues,
>>
>> Context: Mojave has extra security in place that requires explicit user
>> authorisation in order for an app to be allowed to received microphone
>> input. If that permission is not present, then all input from *any* audio
>> interface device is silenced when the app uses the core audio API to read
>> input. In order to enable input, the app needs to use the appropriate
>> notarisations or add a NSMicrophoneUsageDescription key to its plist. The
>> first time the app is run, the user will then be shown a popup to ask if
>> they wish to enable usage of the microphone by that app. That permission
>> then gets stored into the permissions database and is resettable by the
>> tccutil command line utility. So far so good.
>>
>> Now consider a user-space HAL-plugin virtual driver based on the
>> coreaudio/AudioServerPlugin.h configuration. Since the driver is not a kext,
>> it has to use user-space APIs to do anything with audio. But in order to
>> read input via core audio api's, it has to have explicit user permission,
>> which (as I understand it) is impossible to grant because the coreaudiod is
>> forbidden from raising anything GUI or popup related: A Catch-22.
>>
>> So my question is pretty fundamental:
>>
>> Is it now impossible to read audio input in a user-space HAL plugin virtual
>> driver in Mojave, or is there some hitherto undocumented driver-specific
>> work-around that could enable audio input?
>>
>> If it is impossible by design rather than accident, I would appreciate an
>> Apple-insider explaining the context of that design, because this would be a
>> pretty fundamental downgrading of the HAL technology.
>>
>> Best Regards,
>> Nicolas Haynes
>>
>>
>>
>>
>>
>>
>>
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