Re: Per-descriptor state

[Joerg Sonnenberger <joerg%bec.de@localhost>]

On Thu, May 04, 2023 at 09:58:49AM +0100, Robert Swindells wrote:
> 
> David Holland <dholland-tech%netbsd.org@localhost> wrote:
> >On Sun, Apr 30, 2023 at 09:44:49AM -0400, Mouse wrote:
> > > > Close-on-fork is apparently either coming or already here, not sure
> > > > which, but it's also per-descriptor.
> > > 
> > > I should probably add that here, then, though use cases will likely be
> > > rare.  I can think of only one program I wrote where it'd be useful; I
> > > created a "close these fds post-fork" data structure internally.
> >
> >I can't think of any at all; to begin with it's limited to forks that
> >don't exec, and unless just using it for convenience as you're
> >probably suggesting, it only applies when also using threads, and if
> >one's using threads why is one also using forks? So it seems like it's
> >limited to badly designed libraries that want to fork behind the
> >caller's back instead of setting up their forks at initialization
> >time. Or something.
> 
> Or it is needed for a little used application called Firefox.

For a sandbox, something like closefrom is actually much preferred as
you don't know what else has opened file descriptors. I really question
the sanity of close-on-fork...

Joerg