Thread-safe creation of UNIX domain sockets

[Carlos O'Donell]

On Sat, Dec 27, 2008 at 8:56 AM, Florian Weimer <fw@deneb.enyo.de> wrote:
> Is it possible to create UNIX domain sockets with specific file system
> permissions in a thread-safe way?
>
> In a single-threaded program, it's possible to set the umask to 0777,
> create the socket, restore the umask, and chmod the path to the
> intended permission set.  In a multi-threaded program, this is
> obviously racy.

Please explain the race condition, and why the obvious synchronization
primitives don't help.

Cheers,
Carlos.