Avoid collisions between parallel installations of Cygwin

Corinna Vinschen corinna-cygwin@cygwin.com
Tue Oct 13 07:54:00 GMT 2009


On Oct 12 20:47, Charles Wilson wrote:
> cgf wrote:
> > I'd feel better about the change if it wasn't the default but could be
> > turned on by a knowledgeable user. 
> 
> But if it is NOT the default, then 3PP installations would still
> interfere with "the real" cygwin, unless the user "turns on" this
> feature manually.

That's exactly the problem.  The policy change is done by implementing
this feature at all.  You gain the advantage by the fact that it's
possible to run multiple Cygwin's in parallel.

> > and that could be used *by knowledgeable users* to control their cygwin
> > behavior.  Or, we could even create a tool to place that information
> > into a "capabilities" section in the DLL itself.
> 
> Oh, wait: I see. So "the real" cygwin would default to the current
> behavior, but it would be up to 3PPs to ensure that THEIR cygwin
> installation DOES turn on the new feature.
> 
> We'd still get interference, if the 3PP *doesn't* do this.  And if they
> DO do it, then we have UNknowledgable end users with a copy of cygwin on
> their system that has this "feature" enabled...and they didn't do it,
> and don't know about it.
> 
> Is this a good thing?
> 
> Probably. Any problems would be because the end user used the 3PP tools
> to <do something> and then tried to <do something else> with the "real"
> cygwin, or vice versa.  That's a 3PP integration issue -- e.g. Somebody
> Else's Problem.

If you make this feature optional, *and* default to off, the entire
potential advantage is moot.  The one Cygwin installation we're
interested in, the net distribution, does not use it, so it's the one
prominent Cygwin installation which will fail as before if 3PPs
forget or just don't know about this feature.  Or don't care.  Or,
are simply using a 1.5 based Cygwin and pipe names still clash.

If this feature should make any sense, it's important that the net
distro DLL uses it by default.  If the feature is made optional and
3PPs don't use it, it's their DLLs which will fail when used together,
but not ours.


Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Project Co-Leader          cygwin AT cygwin DOT com
Red Hat



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