Date: Thu, 20 Apr 2023 16:40:52 +0200
To: Bruno Haible <bruno@clisp.org>
Subject: Re: posix_spawn facility
Message-ID: <ZEFO9ELNzIliSGPv@calimero.vinschen.de>
Mail-Followup-To: Bruno Haible <bruno@clisp.org>, cygwin@cygwin.com
References: <1752276.7aRn1RRit1@nimes> <ZEDmai2kO+dfxWut@xps13>
 <ZED5SOzW5QAkfxje@calimero.vinschen.de> <1853259.CQOukoFCf9@nimes>
 <ZEFKW/rbAS8x4QbV@calimero.vinschen.de>
MIME-Version: 1.0
Content-Disposition: inline
In-Reply-To: <ZEFKW/rbAS8x4QbV@calimero.vinschen.de>
Precedence: list
From: Corinna Vinschen via Cygwin <cygwin@cygwin.com>
Reply-To: cygwin@cygwin.com
Cc: Corinna Vinschen <corinna-cygwin@cygwin.com>, cygwin@cygwin.com
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: 7bit
Errors-To: cygwin-bounces+archive-cygwin=delorie.com@cygwin.com
Sender: "Cygwin" <cygwin-bounces+archive-cygwin=delorie.com@cygwin.com>

On Apr 20 16:21, Corinna Vinschen via Cygwin wrote:
> On Apr 20 12:18, Bruno Haible via Cygwin wrote:
> >      The "inheritable handles" is a data structure that allows for the
> >      arbitrary reshuffling of file descriptors required by posix_spawn
> >      (the addopen, adddup2, addclose actions), i.e. which does the book-
> >      keeping which HANDLE must in the end be open in the parent and which
> >      must in the end be open in the child, and at which position.
> 
> Hmm.  Your code uses lpReserved2 for that, but the functionality is
> one implemented in MSVCRT.  For obvious reasons, Cygwin executables
> are not linked against msvcrt.dll and we're using lpReserved2 for our
> own purposes.

Oh, btw., did you know that there's a newer mechanism for defining
specific inheritable handles to CreateProcess, which is implemented
in kernel32.dll, so it does not depend on MSVCRT?

There's a STARTUPINFOEX structure which allows to specify the 
additional handles.  See

https://learn.microsoft.com/en-us/windows/win32/api/winbase/ns-winbase-startupinfoexa

and the PROC_THREAD_ATTRIBUTE_HANDLE_LIST argument described in

https://learn.microsoft.com/en-us/windows/win32/api/processthreadsapi/nf-processthreadsapi-updateprocthreadattribute


Corinna

-- 
Problem reports:      https://cygwin.com/problems.html
FAQ:                  https://cygwin.com/faq/
Documentation:        https://cygwin.com/docs.html
Unsubscribe info:     https://cygwin.com/ml/#unsubscribe-simple