Prevent macOS generic keyboard driver from hijacking a USB device

I am trying to write a macOS custom level driver in C for a USB device (pentablet with buttons).

This tablet is currently recognized as a shared mouse and a shared keyboard from the system. Since the labels applied to the pentablet buttons are not customizable, I would like to write my own driver for this.

What works:

I can read raw data from hidapi ( http://www.signal11.us/oss/hidapi/ ) from a device that looks something like this:

A   B    C    D    E    F    G    H
10  192  228  50   157  43   0    0

      

        
        
        
      

    

I realized that when using the pen, the column values B-H

change according to position, pressure and click.

My problem:

However, I cannot figure out how to access the buttons of the device. Every time I press one of them their hardcoded key combination is triggered. Since the column values A

never change, I am assuming that the device is still captured as a shared keyboard by the system, and so this column never shows me the currently pressed button and triggers its key combination.

Every time I press one of these buttons, they trigger holding ALT / Option + Shift , in addition, some of them trigger a symbol, and one of them causes the volume to increase.

So my approach was to use a no-coded kext to prevent the system from seizing the device. But that doesn't work either - the device is still captured by the system as a generic keyboard.

I disabled csrutil

and kextload

, having my kext located in /Library/Extensions

, I get a successful message being loaded by the kext:

Warnings:
    Personality CFBundleIdentifier differs from containing kext (not necessarily a mistake, but rarely done):
        Tablet

Code Signing Failure: code signature is invalid
Warnings:
    Personality CFBundleIdentifier differs from containing kext (not necessarily a mistake, but rarely done):
        Tablet

/Library/Extensions/foobartablet.kext appears to be loadable (not including linkage for on-disk libraries).
kext-dev-mode allowing invalid signature -67050 0xFFFFFFFFFFFEFA16 for kext "/Library/Extensions/foobartablet.kext"
kext signature failure override allowing invalid signature -67050 0xFFFFFFFFFFFEFA16 for kext "/Library/Extensions/foobartablet.kext"
Loading /Library/Extensions/foobartablet.kext.

      

        
        
        
      

    

Here's my info.plist

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
    <key>BuildMachineOSBuild</key>
    <string>13C64</string>
    <key>CFBundleDevelopmentRegion</key>
    <string>English</string>
    <key>CFBundleGetInfoString</key>
    <string>1.0 Copyright © Adis Durakovic</string>
    <key>CFBundleIdentifier</key>
    <string>com.adisdurakovic.huitablet</string>
    <key>CFBundleInfoDictionaryVersion</key>
    <string>6.0</string>
    <key>CFBundlePackageType</key>
    <string>KEXT</string>
    <key>CFBundleShortVersionString</key>
    <string>Huion Tablet 1.0</string>
    <key>CFBundleSignature</key>
    <string>????</string>
    <key>CFBundleVersion</key>
    <string>1.0</string>
    <key>DTCompiler</key>
    <string>com.apple.compilers.llvm.clang.1_0</string>
    <key>DTPlatformBuild</key>
    <string>5A2053</string>
    <key>DTPlatformVersion</key>
    <string>GM</string>
    <key>DTSDKBuild</key>
    <string>13A595</string>
    <key>DTSDKName</key>
    <string>macosx10.9</string>
    <key>DTXcode</key>
    <string>0501</string>
    <key>DTXcodeBuild</key>
    <string>5A2053</string>
    <key>IOKitPersonalities</key>
    <dict>
        <key>Tablet</key>
        <dict>
            <key>CFBundleIdentifier</key>
            <string>com.apple.kpi.iokit</string>
            <key>IOClass</key>
            <string>IOService</string>
            <key>IOProviderClass</key>
            <string>IOUSBDevice</string>
            <key>idVendor</key>
            <string>9580</string>
            <key>idProduct</key>
            <string>110</string>
            <key>bcdDevice</key>
            <string>12288</string>
            <key>IOProbeScore</key>
            <integer>200000</integer>
        </dict>
        <key>TabletNew</key>
        <dict>
            <key>CFBundleIdentifier</key>
            <string>com.apple.kpi.iokit</string>
            <key>IOClass</key>
            <string>IOService</string>
            <key>IOProviderClass</key>
            <string>IOUSBHostDevice</string>
            <key>idVendor</key>
            <string>9580</string>
            <key>idProduct</key>
            <string>110</string>
            <key>bcdDevice</key>
            <string>12288</string>
            <key>IOProbeScore</key>
            <integer>300000</integer>
        </dict>
    </dict>
    <key>OSBundleLibraries</key>
    <dict/>
</dict>
</plist>

      

        
        
        
      

    

And here's my output as well ioreg -i -w 0 -l -n "PenTablet"

, which I used to map devices: https://adisdurakovic.com/pentablet.txt

What am I doing wrong here?