capslock_light.c

#include <Python/Python.h>
#include <stdio.h>
#include <getopt.h>
#include <stdlib.h>
#include <sysexits.h>
#include <time.h>
#include <mach/mach_error.h>

#include <IOKit/IOCFPlugIn.h>
#include <IOKit/hid/IOHIDLib.h>
#include <IOKit/hid/IOHIDUsageTables.h>

static IOHIDElementCookie capslock_cookie = (IOHIDElementCookie)0;
static IOHIDElementCookie numlock_cookie  = (IOHIDElementCookie)0;

io_service_t find_a_keyboard(void);
void         find_led_cookies(IOHIDDeviceInterface122** handle);
void         create_hid_interface(io_object_t hidDevice, IOHIDDeviceInterface*** hdi);
int          manipulate_led(UInt32 whichLED, UInt32 value);

static PyObject *led_setlight(PyObject *self, PyObject *args){
    int value;
    if (!PyArg_ParseTuple(args, "i", &value))
        return NULL;
    if(value==0){
      manipulate_led(kHIDUsage_LED_CapsLock, 0);
    }else{
      manipulate_led(kHIDUsage_LED_CapsLock, 1);
    }
    return Py_None;
}

static PyMethodDef led_methods[] = {
    {"setlight", (PyCFunction)led_setlight, METH_VARARGS, "turn the led on or off"},
    {NULL, NULL, 0, NULL}   /* sentinel */
};

void initled(void) {
  /* Create the module and add the functions */
  Py_InitModule("led", led_methods);
}

void create_hid_interface(io_object_t hidDevice, IOHIDDeviceInterface*** hdi) {
    IOCFPlugInInterface** plugInInterface = NULL;

    io_name_t className;
    HRESULT   plugInResult = S_OK;
    SInt32    score = 0;
    IOReturn  ioReturnValue = kIOReturnSuccess;

    ioReturnValue = IOObjectGetClass(hidDevice, className);

    //print_errmsg_if_io_err(ioReturnValue, "Failed to get class name.");

    ioReturnValue = IOCreatePlugInInterfaceForService(
                        hidDevice, kIOHIDDeviceUserClientTypeID,
                        kIOCFPlugInInterfaceID, &plugInInterface, &score);
    if (ioReturnValue != kIOReturnSuccess) {
        return;
    }

    plugInResult = (*plugInInterface)->QueryInterface(plugInInterface,
                     CFUUIDGetUUIDBytes(kIOHIDDeviceInterfaceID), (LPVOID)hdi);
    //print_errmsg_if_err(plugInResult != S_OK, "Failed to create device interface.\n");

    (*plugInInterface)->Release(plugInInterface);
}


io_service_t find_a_keyboard(void) {
    io_service_t result = (io_service_t)0;

    CFNumberRef usagePageRef = (CFNumberRef)0;
    CFNumberRef usageRef = (CFNumberRef)0;
    CFMutableDictionaryRef matchingDictRef = (CFMutableDictionaryRef)0;

    if (!(matchingDictRef = IOServiceMatching(kIOHIDDeviceKey))) {
        return result;
    }

    UInt32 usagePage = kHIDPage_GenericDesktop;
    UInt32 usage = kHIDUsage_GD_Keyboard;

    if (!(usagePageRef = CFNumberCreate(kCFAllocatorDefault, kCFNumberIntType,
                                        &usagePage))) {
        goto out;
    }

    if (!(usageRef = CFNumberCreate(kCFAllocatorDefault, kCFNumberIntType,
                                    &usage))) {
        goto out;
    }

    CFDictionarySetValue(matchingDictRef, CFSTR(kIOHIDPrimaryUsagePageKey),
                         usagePageRef);
    CFDictionarySetValue(matchingDictRef, CFSTR(kIOHIDPrimaryUsageKey),
                         usageRef);

    result = IOServiceGetMatchingService(kIOMasterPortDefault, matchingDictRef);

out:
    if (usageRef) {
        CFRelease(usageRef);
    }
    if (usagePageRef) {
        CFRelease(usagePageRef);
    }

    return result;
}

void find_led_cookies(IOHIDDeviceInterface122** handle) {
    IOHIDElementCookie cookie;
    CFTypeRef          object;
    long               number;
    long               usage;
    long               usagePage;
    CFArrayRef         elements;
    CFDictionaryRef    element;
    IOReturn           result;

    if (!handle || !(*handle)) {
        return;
    }

    result = (*handle)->copyMatchingElements(handle, NULL, &elements);

    if (result != kIOReturnSuccess) {
        //fprintf(stderr, "Failed to copy cookies.\n");
        exit(1);
    }

    CFIndex i;

    for (i = 0; i < CFArrayGetCount(elements); i++) {

        element = CFArrayGetValueAtIndex(elements, i);

        object = (CFDictionaryGetValue(element, CFSTR(kIOHIDElementCookieKey)));
        if (object == 0 || CFGetTypeID(object) != CFNumberGetTypeID()) {
            continue;
        }
        if (!CFNumberGetValue((CFNumberRef) object, kCFNumberLongType,
                              &number)) {
            continue;
        }
        cookie = (IOHIDElementCookie)number;

        object = CFDictionaryGetValue(element, CFSTR(kIOHIDElementUsageKey));
        if (object == 0 || CFGetTypeID(object) != CFNumberGetTypeID()) {
            continue;
        }
        if (!CFNumberGetValue((CFNumberRef)object, kCFNumberLongType,
                              &number)) {
            continue;
        }
        usage = number;

        object = CFDictionaryGetValue(element,CFSTR(kIOHIDElementUsagePageKey));
        if (object == 0 || CFGetTypeID(object) != CFNumberGetTypeID()) {
            continue;
        }
        if (!CFNumberGetValue((CFNumberRef)object, kCFNumberLongType,
                              &number)) {
            continue;
        }
        usagePage = number;

        if (usagePage == kHIDPage_LEDs) {
            switch (usage) {

            case kHIDUsage_LED_NumLock:
                numlock_cookie = cookie;
                break;

            case kHIDUsage_LED_CapsLock:
                capslock_cookie = cookie;
                break;

            default:
                break;
            }
        }
    }

    return;
}


//whichLED = kHIDUsage_LED_CapsLock;
//whichLED = kHIDUsage_LED_NumLock;

int manipulate_led(UInt32 whichLED, UInt32 value) {
    io_service_t           hidService = (io_service_t)0;
    io_object_t            hidDevice = (io_object_t)0;
    IOHIDDeviceInterface **hidDeviceInterface = NULL;
    IOReturn               ioReturnValue = kIOReturnError;
    IOHIDElementCookie     theCookie = (IOHIDElementCookie)0;
    IOHIDEventStruct       theEvent;

    if (!(hidService = find_a_keyboard())) {
        //fprintf(stderr, "No keyboard found.\n");
        return ioReturnValue;
    }

    hidDevice = (io_object_t)hidService;

    create_hid_interface(hidDevice, &hidDeviceInterface);

    find_led_cookies((IOHIDDeviceInterface122 **)hidDeviceInterface);

    ioReturnValue = IOObjectRelease(hidDevice);
    if (ioReturnValue != kIOReturnSuccess) {
        goto out;
    }

    ioReturnValue = kIOReturnError;

    if (hidDeviceInterface == NULL) {
        //fprintf(stderr, "Failed to create HID device interface.\n");
        return ioReturnValue;
    }

    if (whichLED == kHIDUsage_LED_NumLock) {
        theCookie = numlock_cookie;
    } else if (whichLED == kHIDUsage_LED_CapsLock) {
        theCookie = capslock_cookie;
    }

    if (theCookie == 0) {
        ////fprintf(stderr, "Bad or missing LED cookie.\n");
        goto out;
    }

    ioReturnValue = (*hidDeviceInterface)->open(hidDeviceInterface, 0);
    if (ioReturnValue != kIOReturnSuccess) {
        //fprintf(stderr, "Failed to open HID device interface.\n");
        goto out;
    }

    ioReturnValue = (*hidDeviceInterface)->getElementValue(hidDeviceInterface,
                                               theCookie, &theEvent);
    if (ioReturnValue != kIOReturnSuccess) {
        (void)(*hidDeviceInterface)->close(hidDeviceInterface);
        goto out;
    }

    if (value != -1) {
        if (theEvent.value != value) {
            theEvent.value = value;
            ioReturnValue = (*hidDeviceInterface)->setElementValue(
                                hidDeviceInterface, theCookie,
                                &theEvent, 0, 0, 0, 0);
            if (ioReturnValue == kIOReturnSuccess) {
                //fprintf(stdout, "%s\n", (theEvent.value) ? "on" : "off");
            }
        }
    }

    ioReturnValue = (*hidDeviceInterface)->close(hidDeviceInterface);

out:
    (void)(*hidDeviceInterface)->Release(hidDeviceInterface);
    return ioReturnValue;
}

int main (int argc, char **argv) {

  manipulate_led(kHIDUsage_LED_CapsLock, 0);
  //whichLED = ;
  return 0;
}