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Subject: cygwin 3.6.0: No signals received after swapcontext() is used
To: cygwin AT cygwin DOT com
Message-ID: <ec6e2050-953f-0d47-c385-cfa598566291@t-online.de>
Date: Thu, 6 Mar 2025 13:24:27 +0100
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From: Christian Franke via Cygwin <cygwin AT cygwin DOT com>
Reply-To: cygwin AT cygwin DOT com
Cc: Christian Franke <Christian DOT Franke AT t-online DOT de>
Sender: "Cygwin" <cygwin-bounces~archive-cygwin=delorie DOT com AT cygwin DOT com>

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Found because 'stress-ng --context 1 ...' always hangs.

The attached testcase uses the example from Linux swapcontext(3) to call 
the context functions.

$ uname -r
3.6.0-0.419.g3c1308ed890e.x86_64

$ gcc -o ctxnosig ctxnosig.c

$ ./ctxnosig # ... and hit ^C
waste_time: started
[^C][SIGINT]
waste_time: returning, sigflag=1
main2: swapcontext(&uctx_main, &uctx_func2)
func2: started
func2: swapcontext(&uctx_func2, &uctx_func1)
func1: started
func1: swapcontext(&uctx_func1, &uctx_func2)
func2: returning
func1: returning
main2: exiting
waste_time: started
[^C][^C][^C][^C][^C][^C][^C][^C][^C][^C]...
waste_time: returning, sigflag=0
main: sleep(5)...
[SIGINT]
[SIGINT]
[^C][SIGINT]
main: sleep(5)=2
main: exiting, 4 SIGINT received


Possibly a minor issue because these functions are obsoleted (last seen 
in POSIX 2004), but at least cygruby*.dll import these:

$ objdump -p /bin/cygruby320.dll | grep context
         00378ca8  <none>  0286  getcontext
         00378e08  <none>  0391  makecontext
         003791c0  <none>  05cd  swapcontext
...

-- 
Regards,
Christian


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