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Date:	Mon, 24 Oct 2011 12:21:03 +0200
From:	Corinna Vinschen <corinna-cygwin AT cygwin DOT com>
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Subject:	Re: 1.7.9: spawn brakes reopening of serial port
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Please, don't http://cygwin.com/acronyms/#TOFU


On Oct 24 12:02, Manuel Wienand wrote:
> Hallo Corinna,
> 
> thanks for the response. Yes, you are right, I missed the fact that
> the child process inherits the file descriptors.
> 
> I took a look at the documentation of exec and just to be clear on the
> descriptor/handler issue:
> - file descriptor are passed down (basically always when calling the
> 'open' function)
> - socket descriptors are *not* passed down (not sure, wasn't in the
> documentation)

All descriptors are passed down, unless the close-on-exec flag has been
set explicitely.

> - handles of semaphores, mutexes, memory maps, message queues are
> *not* passed down.

Uh, "handles" sounds so much like a Windows concept...
As for POSIX IPC objects, they are not inherited by exec'ed processes
and have to be reopened.

> - signal mask, scheduling policies (at leat when using SCHED_FIFO,
> SCHED_RR or SCHED_SPORADIC) and directory streams are passed down
> Is that correct?

Not quite.  For a good overview of what happens in execve, see
http://www.kernel.org/doc/man-pages/online/pages/man2/execve.2.html


Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Project Co-Leader          cygwin AT cygwin DOT com
Red Hat

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