From: Eric Wong <normalperson@...>
Date: 2011-04-13T07:37:06+09:00
Subject: [ruby-core:35730] Re: mvm branch status?

Charles Oliver Nutter <headius@headius.com> wrote:
> On Sun, Apr 10, 2011 at 11:28 PM, Urabe Shyouhei <shyouhei@ruby-lang.org> wrote:
> > What C APIs are safe to use with MVM is not fully certain yet. ��For instance
> > there are process-global states other than C global variables like current
> > directory, signal masks, ... We are still exploring.
> 
> For current directory, JRuby maintains that separately and any calls
> that are sensitive to cwd are modified to use this per-runtime value.
> Because we share the JVM, we can't safely chdir the entire process, so
> this was really the only way.
> 
> I'm not sure how MRI would do the same, since it is much more
> dependent on low-level C APIs and their expectation of per-process
> cwd.

POSIX.1-2008 has openat(), renameat(), chownat(), etc.., which can be
used for implementing per-thread/VM working directories.  It might take
a while for more platforms to support them, but Linux has had them
for a few years.

-- 
Eric Wong