IOKit and getting unique ID's

Question

I am using: IOServiceGetMatchingServices

kr = IOServiceGetMatchingServices(kIOMasterPortDefault,
IOServiceNameMatching("AppleUSBEHCI"), &io_objects);

I am looking for how I find out information about the internal HD as the above will prob USB device.

I cannot seem to find a list or anything that would tell me this.

Essentially I am looking for a way to get a unique ID from the system. On Windows the other developer uses the hard disk id.

Can anyone shed some light on these values?

Answer 1

On the command line, you can use the ioreg tool to explore the IO Kit registry. For Lion or Older, you can also use the convenient IORegistryExplorer GUI tool from Apple's Hardware IO Tools package. (it crashes on Mountain Lion)

For looking at internal hard drive properties, this is a pretty good start:

ioreg -irc IOAHCIBlockStorageDevice -w 0

Which on my MacBook Air yields:

+-o IOAHCIBlockStorageDevice  <class IORegistryEntry:IOService:IOBlockStorageDevice:IOAHCIBlockStorageDevice, id 0x100000216, registered, matched, active, busy 0 (472 ms), retain 7>
  | {
  |   "IOCFPlugInTypes" = {"24514B7A-2804-11D6-8A02-003065704866"="SMARTLib.plugin"}
  |   "device-type" = "Generic"
  |   "IOStorageFeatures" = {"Unmap"=Yes}
  |   "Device Characteristics" = {"Logical Block Size"=512,"Product Name"="APPLE SSD TS256C                        ","Medium Type"="Solid State","Physical Block Size"=512,"SATA Features"=23,"Serial Number"="        X06S10H7THRZ","Product Revision Level"="CJAA0201"}
  |   "Protocol Characteristics" = {"Physical Interconnect"="SATA","Physical Interconnect Location"="Internal"}
  |   "SMART Capable" = Yes
  |   "IOMinimumSegmentAlignmentByteCount" = 4
  | }
  | 
  +-o IOBlockStorageDriver  <class IORegistryEntry:IOService:IOStorage:IOBlockStorageDriver, id 0x100000219, registered, matched, active, busy 0 (471 ms), retain 8>
    +-o APPLE SSD TS256C Media  <class IORegistryEntry:IOService:IOStorage:IOMedia, id 0x10000021a, registered, matched, active, busy 0 (471 ms), retain 11>
      +-o IOMediaBSDClient  <class IORegistryEntry:IOService:IOMediaBSDClient, id 0x10000021b, registered, matched, active, busy 0 (0 ms), retain 6>
      +-o IOGUIDPartitionScheme  <class IORegistryEntry:IOService:IOStorage:IOPartitionScheme:IOGUIDPartitionScheme, id 0x10000021d, !registered, !matched, active, busy 0 (3 ms), retain 8>
        +-o EFI system partition@1  <class IORegistryEntry:IOService:IOStorage:IOMedia, id 0x100000263, registered, matched, active, busy 0 (0 ms), retain 9>
        | +-o IOMediaBSDClient  <class IORegistryEntry:IOService:IOMediaBSDClient, id 0x100000266, registered, matched, active, busy 0 (0 ms), retain 6>
        +-o Customer@2  <class IORegistryEntry:IOService:IOStorage:IOMedia, id 0x100000264, registered, matched, active, busy 0 (2 ms), retain 11>
        | +-o IOMediaBSDClient  <class IORegistryEntry:IOService:IOMediaBSDClient, id 0x100000267, registered, matched, active, busy 0 (0 ms), retain 7>
        +-o Recovery HD@3  <class IORegistryEntry:IOService:IOStorage:IOMedia, id 0x100000265, registered, matched, active, busy 0 (3 ms), retain 9>
          +-o IOMediaBSDClient  <class IORegistryEntry:IOService:IOMediaBSDClient, id 0x100000268, registered, matched, active, busy 0 (0 ms), retain 6>

You can get at these properties programmatically via the IOKit user library as you've already discovered for USB.

At a somewhat higher level, some of the information is also available via the Disk Arbitration Framework, via the DADiskCopyDescription function. The device properties exposed via this function don't seem to be documented outside the DADisk.h header file, but they're fairly self-explanatory, e.g.:

extern const CFStringRef kDADiskDescriptionDeviceGUIDKey;      /* ( CFData       ) */
extern const CFStringRef kDADiskDescriptionDeviceInternalKey;  /* ( CFBoolean    ) */
extern const CFStringRef kDADiskDescriptionDeviceModelKey;     /* ( CFString     ) */
extern const CFStringRef kDADiskDescriptionDevicePathKey;      /* ( CFString     ) */
extern const CFStringRef kDADiskDescriptionDeviceProtocolKey;  /* ( CFString     ) */
extern const CFStringRef kDADiskDescriptionDeviceRevisionKey;  /* ( CFString     ) */
extern const CFStringRef kDADiskDescriptionDeviceUnitKey;      /* ( CFNumber     ) */
extern const CFStringRef kDADiskDescriptionDeviceVendorKey;    /* ( CFString     ) */

Answer 2

I believe what you want to do is to look at the device descriptor and see if it has a serial number. It is up to the device to supply a serial number, and it's possible that the number may not be unique if it is provided at all. If the device has a custom descriptor, there may be useful in there too.

See the following on descriptors: http://www.beyondlogic.org/usbnutshell/usb5.shtml

There appears to be a property to get the serial number on the HID Device wrapper class:

https://developer.apple.com/library/mac/#documentation/IOKit/Reference/IOHIDBase_header_reference/Reference/reference.html#//apple_ref/doc/uid/TP40012400

If that doesn't work, there should be a way to get direct access to the USB device and request the data you need.