flock() LOCK_UN support on Hurd

[Amos Jeffries]

I am facing a small portability issue on Hurd. Specifically missing 
definition of LOCK_UN for use as flock() parameter when compiling
 <http://bazaar.launchpad.net/~squid/squid/4/view/head:/src/base/File.h>

There seems to be work from 2001/2002 and a GSoC from 2014 making 
patches, but these do not appear to be in the current Hurd build on 
Debian through the expected fcntl.h include.

We need the flock() semantic of reliable atomic locking on files for 
multi-process shared file access between otherwise independent processes.

Am I missing something as simple as an include?
or, are there any alternatives available on Hurd?


Amos Jeffries