HID report dumper for MacOS

hid_report_dumper.c

#include <curses.h>

#include <CoreFoundation/CoreFoundation.h>

#include <IOKit/hid/IOHIDManager.h>
#include <IOKit/hid/IOHIDKeys.h>

struct keyboard_handler {
    uint8_t hid_report_buffer[1024];
    int index;
    int report_count;
};

static void got_hid_report(void *context, IOReturn result, void *sender,
			   IOHIDReportType type, uint32_t reportID, uint8_t *report,
			   CFIndex reportLength)
{
    struct keyboard_handler* handler = (struct keyboard_handler*) context;
    handler->report_count++;
    move(handler->index + 1, 0);
    clrtoeol();

    printw("%i [%.5i] context=%p, reportID=%i reportLength=%li ",
	   handler->index, handler->report_count, context, reportID, reportLength);
    int i = 0;
    for (i = 0; i < reportLength; i++) {
	if (report[i]) {
	    attron(COLOR_PAIR(1));
	}
	printw(" %.2x", report[i]);
	if (report[i]) {
	    attroff(COLOR_PAIR(1));
	}
    }
    if (report[0] == 0x1 || report[0] == 0x10) {
	endwin();
	exit(0);
    }

    refresh();
}

static void match_callback(void *context, IOReturn result,
			   void *sender, IOHIDDeviceRef device)
{
    static int captured_devices = 0;
    static int failed_captures = 0;

    // dump instead of capturing
    if (false)
    {
	{
	    CFTypeRef o = IOHIDDeviceGetProperty(
		device, CFSTR(kIOHIDDeviceUsagePairsKey));
	    printf("\tkIOHIDDeviceUsagePairsKey = %p\n", o);
	    CFShow(o);
	}

	{
	    CFTypeRef o = IOHIDDeviceGetProperty(
		device, CFSTR(kIOHIDElementKey));
	    printf("\tkIOHIDElementKey = %p\n", o);
	    CFShow(o);
	}

	return;
    }

    IOReturn r = IOHIDDeviceOpen(device, kIOHIDOptionsTypeSeizeDevice);
    if (r == kIOReturnSuccess) {
	struct keyboard_handler *handler =
	    (struct keyboard_handler*) malloc(sizeof(*handler));
	memset(handler, 0x00, sizeof(*handler));
	handler->index = captured_devices++;
	IOHIDDeviceRegisterInputReportCallback(
	    device,
	    handler->hid_report_buffer,
	    sizeof(handler->hid_report_buffer),
	    &got_hid_report,
	    (void*) handler);

	move(handler->index + 1, 0);
	printw("%i <no reports yet>", handler->index);

    }
    else {
	failed_captures++;
    }

    move(0, 0);
    clrtoeol();
    printw("Seized %i devices", captured_devices);
    if (failed_captures) {
	printw(" (%i failed)", failed_captures);
    }
    refresh();
}

static void match_set(CFMutableDictionaryRef dict, CFStringRef key, int value) {
    CFNumberRef number = CFNumberCreate(
	kCFAllocatorDefault, kCFNumberIntType, &value);
    CFDictionarySetValue(dict, key, number);
    CFRelease(number);
}

static CFDictionaryRef matching_dictionary_create(int vendorID,
						  int productID,
						  int usagePage,
						  int usage)
{
    CFMutableDictionaryRef match = CFDictionaryCreateMutable(
	kCFAllocatorDefault, 0,
	&kCFTypeDictionaryKeyCallBacks,
	&kCFTypeDictionaryValueCallBacks);

    if (vendorID) {
	match_set(match, CFSTR(kIOHIDVendorIDKey), vendorID);
    }
    if (productID) {
	match_set(match, CFSTR(kIOHIDProductIDKey), productID);
    }
    if (usagePage) {
	match_set(match, CFSTR(kIOHIDDeviceUsagePageKey), usagePage);
    }
    if (usage) {
	match_set(match, CFSTR(kIOHIDDeviceUsageKey), usage);
    }

    return match;
}

int main() {
    initscr();
    start_color();
    use_default_colors();
    init_pair(1, COLOR_RED, -1);

    IOHIDManagerRef hidManager = IOHIDManagerCreate(
	kCFAllocatorDefault, kIOHIDOptionsTypeNone);

    IOHIDManagerRegisterDeviceMatchingCallback(
	hidManager, match_callback, NULL);

    IOHIDManagerScheduleWithRunLoop(
	hidManager, CFRunLoopGetMain(), kCFRunLoopCommonModes);

    // all keyboards
    CFDictionaryRef match = matching_dictionary_create(0, 0, 1, 6);

    // kinesis
    /* CFDictionaryRef match = matching_dictionary_create(0x05f3, 0x0007, 0, 0); */

    // noppoo
    /* CFDictionaryRef match = matching_dictionary_create(0x1006, 0x0022, 1, 6); */
    
    IOHIDManagerSetDeviceMatching(hidManager, match);
    CFRelease(match);

    CFRunLoopRun();
}