traversing the I/O registry on Mac OS X (iokit)

Makefile

traverse_io_registry: traverse_io_registry.c
	${CC} $^ -framework CoreFoundation -framework IOKit -o $@

traverse_io_registry.c

#include <CoreFoundation/CoreFoundation.h>
#include <IOKit/IOKitLib.h>

static void print_entry(io_registry_entry_t entry);
static void traverse_entry(io_registry_entry_t entry);

static void print_cf_string(CFStringRef cf_string) {
	char * buffer;
	CFIndex len = CFStringGetLength(cf_string);
	buffer = (char *) malloc(sizeof(char) * len + 1);
	CFStringGetCString(cf_string, buffer, len + 1,
			CFStringGetSystemEncoding());
	printf("%s", buffer);
	free(buffer);
}
static void print_cf_number(CFNumberRef cf_number) {
	int number;
	/* TODO rather test CFNumberType, than approximate to int */
	CFNumberGetValue(cf_number, kCFNumberIntType, &number);
	printf("%d", number);
}

static void print_cf_type(CFTypeRef cf_type) {
	CFTypeID type_id;

	type_id = (CFTypeID) CFGetTypeID(cf_type);
	if (type_id == CFStringGetTypeID()) {
		print_cf_string(cf_type);
	} else if (type_id == CFNumberGetTypeID()) {
		print_cf_number(cf_type);
	} else {
		/* unknown Type (TODO) */
		printf("<");
		print_cf_string(CFCopyTypeIDDescription(type_id));
		printf(">");
		/* CFSHOW(type_id) for or
		 * print_cf_string(CFCopyDescription(type_id))
		 */
	}
}
static void print_properties(io_registry_entry_t entry) {
	CFMutableDictionaryRef properties;
	CFIndex count;
	CFTypeRef *keys;
	CFTypeRef *values;
	int i;

	IORegistryEntryCreateCFProperties(entry, &properties,
			kCFAllocatorDefault, kNilOptions);
	count = CFDictionaryGetCount(properties);
	keys = (CFTypeRef *) malloc(sizeof(CFTypeRef) * count);
	values = (CFTypeRef *) malloc(sizeof(CFTypeRef) * count);
	CFDictionaryGetKeysAndValues(properties,
			(const void **) keys, (const void **) values);
	for (i = 0; i < count; i++) {
		printf("\t");
		print_cf_type(keys[i]);
		printf(": ");
		print_cf_type(values[i]);
		printf("\n");
	}
}

static void print_entry(io_registry_entry_t entry) {
	io_name_t name;
	IORegistryEntryGetName(entry, name);
	printf("Starting %s\n", name);
	print_properties(entry);
	traverse_entry(entry);
	printf("Finishing %s\n", name);
}

static void traverse_entry(io_registry_entry_t entry) {
	io_iterator_t childIterator;
	io_object_t child;
	IORegistryEntryGetChildIterator(entry, kIOServicePlane, &childIterator);
	while ((child = IOIteratorNext(childIterator))) {
		print_entry(child);
		IOObjectRelease(child);
	}
	IOObjectRelease(childIterator);
}

int main() {
	mach_port_t masterPort;
	io_registry_entry_t rootEntry;

	IOMasterPort(MACH_PORT_NULL, &masterPort);
	rootEntry = IORegistryGetRootEntry(masterPort);
	print_entry(rootEntry);
}