Re: A few Windows build fixes

[Eli Zaretskii <eliz@gnu.org>]

> From: Stefan Monnier <monnier@iro.umontreal.ca>
> Cc: andrewjmoreton@gmail.com,  emacs-devel@gnu.org
> Date: Wed, 07 Sep 2011 08:50:37 -0400
> 
> > The "mounted" file names, if we want or need to support them, will
> > have to be looked up in the mount list taken from "mount -m".
> 
> FWIW, in that example, the mount point was "/some/where is mounted on /"
> (and as it turns out the "mounted on /" is a case not handled by
> cygwin-mount.el).  So /home/foo really meant /some/where/home/foo, but
> to figure that out, we'd first have to decide whether to interpret
> /home/foo as a Cygwin name or as a native name.

File names on Emacs seldom come as "/foo/bar" without a drive letter.
So we can guess these names are Cygwin names.  But even if we don't
want to guess, checking for existent of a directory that is directly
under / is very fast, even on Windows.  So we could check that always,
and probably need a user variable to turn that off (for users who,
like me, will never install Cygwin).

> >> I thought we still had problems delivering signals to them.
> > You are right, we don't support sending Posix signals to Cygwin
> > programs.  But where is that a real problem?  Emacs does know how to
> > interrupt a subprocess, and the way it does that should work with
> > Cygwin programs as well, albeit with less flexibility.  After all,
> > Cygwin programs are just specialized Windows applications.
> 
> It is a cause of problems for the SSL/TLS support (when we use
> gnutls-cli rather than the gnutls DLL), for example.

If someone writes code to deliver signals to Cygwin processes, I'm
sure we will accept the patches.  I know nothing about that except
that it uses some Cygwin-specific magic.