Environment variable does not work (especially DARCS_EDITOR)

[Glynn Clements]

Simon Marlow wrote:

> > The test program works after applying the following patch to GHC
> > that disables nonblocking mode after the fork and before the exec.

> If we did this, we would also need to re-enable non-blocking mode after
> the rawSystem completes.  Also, this doesn't work well if runProcess is
> used and the Haskell program continues to run while the subprocess is
> executing, because the O_NONBLOCK flag is shared between parent and
> child.

Presumably the Haskell program won't like it very much if the spawned
program disables O_NONBLOCK itself?

Is there a reason (other than performance) why the use of O_NONBLOCK
can't be replaced with calling select/poll before accessing the
descriptor?

Is non-blocking I/O only necessary if you need explicit concurrency?
Or do the runtime or critical libraries require it?

-- 
Glynn Clements <glynn at gclements.plus.com>