BSD is dying

Robert Watson rwatson at
Thu Jul 28 15:41:14 BST 2005

On Thu, 28 Jul 2005, Paul Richards wrote:

> On Thu, Jul 28, 2005 at 03:05:25PM +0100, Robert Watson wrote:
>> Not that we shouldn't work to make it better, but I think that there are
>> some fundamental missing pieces, and those pieces aren't at the OS level.
> Actually I think they are. Unix hackers are ultra conservative when it 
> comes to fundamentally changing the "unix way". If it was left to the 
> choice of unix hackers then email would remain strictly text based.
> Would spotlight be a realistic possibility in FreeBSD. It requires 
> hooking into the kernel filesystem API and indexing files as they're 
> changed. That sort of digression from unix thinking is virtually unheard 
> of in the traditional BSD environments. We have very poor sound support 
> or gadget support, whereas Linux is very good and OS X is virtually 
> flawless.

The big problem with introducing Spotlight on a system like FreeBSD (or 
Linux for that matter) is actually the underlying file system.  Files in 
both Linux and FreeBSD don't have names, names instead point at files. 
The hook APIs in the Darwin kernel to support notification of changes for 
Spotlight rely heavily on HFS+ providing a "strong" name space.  I don't 
see that any of the Linux file systems of note have this capability 
either, although Hans is always waving his hands in this direction.

The lack of a strong name space in UNIX is endemic to (or more accurately, 
a feature of) its design.  It's the same thing that allows us to do hard 
linking, and files without names.  I've given this matter a fare amount of 
thought, as this becomes a specific issue when working with OS security, 
as what you would like to be able to do is key access control and 
monitoring to the names for objects that are meaningful to users.  Since 
names don't exist in UNIX, this results in a lot of nasty edge case 

Using a BSD VFS actually makes this issue somewhat tricky for Apple also, 
and you'll find that the underlying mechanisms for Spotlight break down 
when it comes to almost any writable file system other than HFS+.  For 
example, it doesn't work with NFS home directories.  HFS+'s heritage of a 
strong name space comes from its desktop roots, and as a result, features 
like hard links are poorly supported in OS X, and if you actually use 
them, you will often break Spotlight. :-)

Robert N M Watson

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