scan.c

#include <stdio.h>
#include <IOKit/IOCFPlugIn.h>
#include <IOKit/hid/IOHIDKeys.h>
#include <CoreFoundation/CoreFoundation.h>

int main(void)
{
    IOReturn result = kIOReturnSuccess;
    io_iterator_t hidObjectIterator = 0;
    io_object_t hidDevice = IO_OBJECT_NULL;
    CFMutableDictionaryRef hidMatchDictionary = 0;
    CFMutableDictionaryRef hidProperties = 0;

    hidMatchDictionary = IOServiceMatching(kIOHIDDeviceKey);
    result = IOServiceGetMatchingServices(kIOMasterPortDefault,
            hidMatchDictionary,
            &hidObjectIterator);
    if ((result != kIOReturnSuccess) || (hidObjectIterator == 0)) {
        printf("Can't obtain an IO iterator\n");
        exit(1);
    }

    while ((hidDevice = IOIteratorNext(hidObjectIterator))) {
        hidProperties = 0;
        int vendor = 0, product = 0;
        result = IORegistryEntryCreateCFProperties(hidDevice, &hidProperties,
                kCFAllocatorDefault, kNilOptions);
        if ((result == KERN_SUCCESS) && hidProperties) {
            CFNumberRef vendorRef, productRef;

            vendorRef = CFDictionaryGetValue(hidProperties, CFSTR(kIOHIDVendorIDKey));
            productRef = CFDictionaryGetValue(hidProperties, CFSTR(kIOHIDProductIDKey));
            if (vendorRef) {
                CFNumberGetValue(vendorRef, kCFNumberIntType, &vendor);
                CFRelease(vendorRef);
            }
            if (productRef) {
                CFNumberGetValue(productRef, kCFNumberIntType, &product);
                CFRelease(productRef);
            }
        }
        printf("Got a device: vendor %04x, product %04x\n", vendor, product);
        IOObjectRelease(hidDevice);
    }

    IOObjectRelease(hidObjectIterator);
    return 0;
}