Subj : Re: async signal safety?
To   : comp.programming.threads
From : Marcin 'Qrczak' Kowalczyk
Date : Tue Jan 11 2005 08:32 pm

Alexander Terekhov <terekhov@web.de> writes:

> Marcin 'Qrczak' Kowalczyk wrote:
>
> [... errno ...]
>> > Is it okay to save it on signal handler entry and restore on exit?
>> 
>> Yes.
>
> Sez who?

http://www.opengroup.org/onlinepubs/007904875/functions/sigaction.html

"Note in particular that even the "safe" functions may modify errno;
the signal-catching function, if not executing as an independent
thread, may want to save and restore its value."

This suggests that this usage was indeed intended. If it works in
practice, it should have been specified more clearly.

If it doesn't, this paragraph should be removed, but then it should
be clarified what happens when you call an async-signal-safe function
which modifies errno from a signal handler.

-- 
   __("<         Marcin Kowalczyk
   \__/       qrczak@knm.org.pl
    ^^     http://qrnik.knm.org.pl/~qrczak/

.