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Re: snprintf(3) and friends async-signal safety?
On Wed, 22 Dec 2010 18:07:50 +0200
Jean-Yves Migeon <jeanyves.migeon%free.fr@localhost> wrote:
> Hi list,
> While working on my msgfmt thingy for dd(1) , I found that
> snprintf(3) gets used in summary(), which is a function that can be
> called via the SIGINFO handler.
> Unfortunately, I am not quite certain of what I read; a quick look at
> snprintf(3) code in libc/stdio makes me believe that the function is
> _not_ async signal safe (it is not listed in signal(7) either), but is
> still used in as-is in dd(1).
> Question is: is it really safe to use it in a signal handler inside
> Jean-Yves Migeon
Well you could hangle Unix signals synchronously by using a thread which waits
for signals with sigwait(). Usually you block certain signals in main thread,
then one (signal catching) thread calls sigwait() waiting for a signal. When
the signal arrives, signal catching thread stops/restarts other threads,
depending on what the signal was meant to do.
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