[smartmontools-support]darwin support for smartctl

[Geoff K. <ge...@ge...>]

I wrote a quick darwin_os.c using the Panther APIs for accessing SMART 
information.  It was interesting, mostly because of all the trouble I 
found.  I attach it below.

There's lots of stuff it doesn't support.  They fall into three 
categories:

- Could be implemented, but hasn't been done yet:
   - Listing available devices
   - checking the power mode (I think)
   - support for SCSI (I think)
   - support for Escalade controllers (maybe)

- Can't be implemented easily without more OS support:
   - running immediate offline, conveyance, or selective tests
   - running any test in capture mode
   - aborting tests
   - switching on automatic offline testing

- Are implemented, but don't work due to OS bugs:
   - switching off SMART (switching *on* works fine)
   - switching off auto-save (but why would you want to?)
   - running the short test (that leaves you with only the extended test)

The last set have been filed in Apple's bug tracking system and so 
hopefully will be fixed.

However, some things do work well.  All the informational output is 
available, unless you want something that only an offline test updates. 
  I even have a new drive for the database; my laptop has a 
small-form-factor Hitachi drive.