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Subject: Re: No errno set after too many open("/dev/ptmx", ...)
To: cygwin@cygwin.com
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Date: Tue, 1 Apr 2025 14:21:03 +0200
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From: Christian Franke via Cygwin <cygwin@cygwin.com>
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Cc: Christian Franke <Christian.Franke@t-online.de>
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On Mar 30 15:01, Christian Franke wrote:
> Found because 'stress-ng --pty 1' reports "open /dev/ptmx failed, 
> errno=0":
>
> $ uname -r # also with 3.5.7-1 and 3.6.0-1.x86_64
> 3.7.0-0.19.g6c5537c0298e.x86_64
>
> ...
>
> $ gcc -o manyptmx manyptmx.c
>
> $ ./manyptmx
> 3, 2000
> 4, 2000
> ...
> 127, 2000
> 128, 2000
>       0 [main] manyptmx 204 tty_list::allocate: No pty allocated
>                                                       -1, 2000
>

Problem no longer occurs with 3.7.0-0.33.g6e75829e117f. open() now fails 
with EMFILE.

BTW, 'stress-ng --pty 1' then fails because tcdrain(), tcflow() and 
TIOCINQ are not implemented for ptys. Not a problem, I guess.

-- 
Regards,
Christian


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