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Message-ID:	<51C1EAA3.6040307@etr-usa.com>
Date:	Wed, 19 Jun 2013 11:30:11 -0600
From:	Warren Young <warren AT etr-usa DOT com>
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To:	cygwin AT cygwin DOT com
Subject:	Re: Adding MSYS functionality to Cygwin
References:	<CABEPuQJDLjtbcLig1isTUJgb6RBCD8LNShbm9mTPcb9WM5S5fw AT mail DOT gmail DOT com> <51C0B08E DOT 8080900 AT etr-usa DOT com> <CABEPuQJJpRfPKSwZ7M0eTOdp1HxDcmvuy1=qXFHBw-8kLkZ1ZQ AT mail DOT gmail DOT com> <51C0D956 DOT 4090905 AT etr-usa DOT com> <20130619020234 DOT GA3669 AT ednor DOT casa DOT cgf DOT cx>
In-Reply-To:	<20130619020234.GA3669@ednor.casa.cgf.cx>

On 6/18/2013 20:02, Christopher Faylor wrote:
> On Tue, Jun 18, 2013 at 04:04:06PM -0600, Warren Young wrote:
>> It would be possible, though somewhat evil, for Cygwin's exec()
>> implementation to peek at the DLL dependency list of a program before
>> starting it, and from that infer whether it should automatically
>> translate paths.
>
> Cygwin already does this.  It detects whether the program it is about
> to run uses the Cygwin DLL and, if not, makes decisions on how to
> handle exec.  It would be relatively easy to extend this.

Well, given that we're already paying the "peek" cost, I don't have any 
objection to making exec() take longer for the native Windows case only.

Do you know how you want to cope with my contrived "xcopy /bin a b" 
example?  The point of the example, of course, is that "/bin" looks like 
a real, existing POSIX path, but isn't.

 From Chuck's explanation of MSYS, looks like "/b /i /n" would also get 
caught in their heuristics, since it apparently doesn't do file 
existence checks.  (Else, Chuck's dumpbin example wouldn't need a 
workaround.)

File existence checks would fix that, but would then prevent this from 
doing what you want:

     $ notepad ~/tmp/newfile.txt

So, it looks like MSYS is right not to try file existence checks.

(Yes, I realize you can rewrite my xcopy example using dashes for the 
flags.  That's beside the broader point, which is that not all things 
that look like POSIX paths are such.)

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