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Date: Mon, 30 Jan 2006 17:57:45 -0500 (EST)
From: Igor Peshansky <pechtcha AT cs DOT nyu DOT edu>
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To: cygwin AT cygwin DOT com
Subject: Re: MSYS path behavior in Cygwin
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On Mon, 30 Jan 2006, Brian Dessent wrote:

> tom wrote:
>
> > I guess the two will be mutually exclusive, unless you Cygwin devs see
> > some reason to merge some of Earnie's work.  I'm have to believe
> > there's some reason why it hasn't been done though.  I'm sure it's
> > non-trivial to say the least.
> >
> > Thanks for the help anyways!  Cygwin and msys make life in Win32land
> > bearable.
>
> To do that would go against the grain of what Cygwin is trying to
> accomplish: provide a full posix environment.  So to have
> argument-translation code sort of defeats that purpose since all Cygwin
> programs are supposed to recognise posix paths.
>
> Now in reality, everyone has to run a non-Cygwin program from time to
> time, so of course there will be times where you run up against this.
> But the question becomes, when should the library translate paths, and
> when should it leave them alone?  Because you can't just unconditionally
> do it.  The way MSYS handles this is by assuming that everything in the
> MSYS bin directory is a MSYS binary that can handle posix paths, and
> that everything else is a win32/mingw app that needs win32 paths.  Now
> that's a rather stark and arbitrary distinction.  It works for MSYS
> since it's intended to be a rather minimal system, just enough to build
> packages using auto{conf,make},libtool.  But I think for Cygwin this
> would be way too restrictive.

Unfortunately, sometimes you can't do this even if you know that a Win32
program is being invoked.  The problem is that an arbitrary string with a
"/" in it may or may not be a path to a file -- and the only way to know
is to understand the semantics of the arguments.  Since you don't always
know those semantics, doing this in general is impossible.

> The workaround that I think most people use is a wrapper script that
> essentially just runs "cygpath -w" on each argument and then execs $1.
> So you can type "wrapper win32program /posix/path/to/file" and it ends
> up running "win32program c:/win32/path/to/file".  If you do it right,
> you can make this quite generic, so that you just prepend "wrapper" (or
> whatever you want to call it.)
>
> Below is one that I use in my .bashrc that calls perl.  It's probably
> got bugs, and it's not perfect -- for example if you pass something like
> -I/usr/local/bin it will not know how to translate that.
> [snip]

For more comprehensive behavior, you need to have program-specific wrapper
scripts.  For example, see my Java wrappers in the cygwin-apps CVS:
<http://cygwin.com/cgi-bin/cvsweb.cgi/wrappers/java/?cvsroot=cygwin-apps>.
Notice that even those scripts don't do a complete job, since arguments
given to the Java programs themselves are left as-is (by design, because
those scripts can't just go about mangling arbitrary strings).
	Igor
P.S. Is "dodos" short for "extinct birds"? :-)
-- 
				http://cs.nyu.edu/~pechtcha/
      |\      _,,,---,,_	    pechtcha AT cs DOT nyu DOT edu | igor AT watson DOT ibm DOT com
ZZZzz /,`.-'`'    -.  ;-;;,_		Igor Peshansky, Ph.D. (name changed!)
     |,4-  ) )-,_. ,\ (  `'-'		old name: Igor Pechtchanski
    '---''(_/--'  `-'\_) fL	a.k.a JaguaR-R-R-r-r-r-.-.-.  Meow!

"Las! je suis sot... -Mais non, tu ne l'es pas, puisque tu t'en rends compte."
"But no -- you are no fool; you call yourself a fool, there's proof enough in
that!" -- Rostand, "Cyrano de Bergerac"

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