Given a mount path, retrieve a USB device name

- (NSString *) deviceNameWithMountPath:(NSString *)mountPath
{
	OSStatus err;
	FSRef ref;
	FSVolumeRefNum actualVolume;
	err = FSPathMakeRef ( (const UInt8 *) [mountPath fileSystemRepresentation], &ref, NULL );
 
	// get a FSVolumeRefNum from mountPath
	if ( noErr == err ) {
		FSCatalogInfo   catalogInfo;
		err = FSGetCatalogInfo ( &ref,
								 kFSCatInfoVolume,
								 &catalogInfo,
								 NULL,
								 NULL,
								 NULL
								 );
		if ( noErr == err ) {
			actualVolume = catalogInfo.volume;
		}
	}
 
	// now let's get the device name
	GetVolParmsInfoBuffer volumeParms;
	HParamBlockRec pb;
 
	// Use the volume reference number to retrieve the volume parameters. See the documentation
	// on PBHGetVolParmsSync for other possible ways to specify a volume.
	pb.ioParam.ioNamePtr = NULL;
	pb.ioParam.ioVRefNum = actualVolume;
	pb.ioParam.ioBuffer = (Ptr) &volumeParms;
	pb.ioParam.ioReqCount = sizeof(volumeParms);
 
	// A version 4 GetVolParmsInfoBuffer contains the BSD node name in the vMDeviceID field.
	// It is actually a char * value. This is mentioned in the header CoreServices/CarbonCore/Files.h.
	err = PBHGetVolParmsSync(&pb);
 
	NSString *bsdName = [NSString stringWithCString:(char *)volumeParms.vMDeviceID];
 
	// after this we traverse the IORegistry to try to find the device that has the same BDS name
	NSString			*deviceName=nil;
	CFDictionaryRef		matchingDict = NULL;
	io_iterator_t       devIter = nil;
	io_service_t        ioDeviceObj	= nil;
	IOReturn            kr;
	CFTypeRef			data;
 
	matchingDict = IOServiceMatching(kIOUSBDeviceClassName);
	if (matchingDict == NULL) {
		NSLog(@"BusProber: error in -refresh at IOServiceMatching() - dictionary was NULL");
		return nil;
	}
 
	kr = IOServiceGetMatchingServices(kIOMasterPortDefault, matchingDict, &devIter);
	if (kr != kIOReturnSuccess) {
		NSLog(@"BusProber: error in -refresh at IOServiceGetMatchingServices()");
		return nil;
	}
 
	while (ioDeviceObj = IOIteratorNext(devIter))
	{
 
		data = IORegistryEntrySearchCFProperty(ioDeviceObj, kIOServicePlane, CFSTR("BSD Name"), kCFAllocatorDefault, kIORegistryIterateRecursively);
 
		if ([[(NSString*)data substringToIndex:5] isEqualToString:[bsdName substringToIndex:5]]) {
			io_name_t devName;
			IORegistryEntryGetName(ioDeviceObj, devName);
			deviceName = [NSString stringWithCString:devName];
 
			IOObjectRelease(ioDeviceObj);
			break;
		}
 
		IOObjectRelease(ioDeviceObj);
	}
 
	return deviceName;
}