Preliminary tests to implement drutil's optical disc drive numbering in C

disc_drive_numbers.c

#include <IOKit/IOKitLib.h>
#include <IOKit/IOBSD.h>
#include <IOKit/storage/IOCDMedia.h>
#include <IOKit/storage/IOCDBlockStorageDevice.h>
#include <CoreFoundation/CoreFoundation.h>

#define MAXPATHLEN 1024

static void find_cd_media(io_iterator_t *mediaIterator)
{
	mach_port_t         masterPort;
	CFMutableDictionaryRef   classesToMatch;

	IOMasterPort(MACH_PORT_NULL, &masterPort);
	classesToMatch = IOServiceMatching(kIOCDMediaClass);
	IOServiceGetMatchingServices(masterPort, classesToMatch, mediaIterator);
}

static void find_cd_block_devices(io_iterator_t *deviceIterator)
{
	mach_port_t         masterPort;
	CFMutableDictionaryRef   classesToMatch;

	IOMasterPort(MACH_PORT_NULL, &masterPort);
	classesToMatch = IOServiceMatching(kIOCDBlockStorageDeviceClass);
	IOServiceGetMatchingServices(masterPort, classesToMatch, deviceIterator);
}

static int get_device_file_path(io_object_t nextMedia, char * deviceFilePath)
{
        CFTypeRef deviceFilePathAsCFString;

	*deviceFilePath = '\0';
        deviceFilePathAsCFString = IORegistryEntryCreateCFProperty(nextMedia,
				CFSTR(kIOBSDNameKey), kCFAllocatorDefault, 0);

	if (deviceFilePathAsCFString)
	{
		if (CFStringGetCString(deviceFilePathAsCFString, deviceFilePath,
			   MAXPATHLEN, kCFStringEncodingASCII)) {
			return 1;
		}
		CFRelease(deviceFilePathAsCFString);
	}
	return 0;
}

static int print_object_class(io_object_t object)
{
	io_name_t className;
	IOObjectGetClass(object, className);
	fprintf(stderr, "\tclass name: %s\n", className);
}

static void print_info_for_objects(io_iterator_t objectIterator)
{
	io_object_t nextObject;
	char device_name[MAXPATHLEN+1] = "\0";
	int index = 0;
	while ((nextObject = IOIteratorNext(objectIterator))) {
		fprintf(stderr, "drive %d:\n", ++index);
		if (get_device_file_path(nextObject, device_name))
			fprintf(stderr, "\tdevice name: %s\n", device_name);
		print_object_class(nextObject);
		IOObjectRelease(nextObject);
	}
}

int main() {
	io_iterator_t objectIterator;

	fprintf(stderr, "detected media:\n");
	find_cd_media(&objectIterator);
	print_info_for_objects(objectIterator);

	fprintf(stderr, "detected CD block devices:\n");
	find_cd_block_devices(&objectIterator);
	print_info_for_objects(objectIterator);
}

Makefile

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