Date: Fri, 28 Nov 2003 08:18:12 +0100
From: Tomas Szepe <szepe@pinerecords.com>
To: Linus Torvalds <torvalds@osdl.org>
Cc: "Richard B. Johnson" <root@chaos.analogic.com>,
       Linux kernel <linux-kernel@vger.kernel.org>, Andries.Brouwer@cwi.nl
Subject: Re: BUG (non-kernel), can hurt developers.
Message-ID: <20031128071812.GA28728@louise.pinerecords.com>
References: <Pine.LNX.4.53.0311261153050.10929@chaos> <Pine.LNX.4.58.0311261021400.1524@home.osdl.org>
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On Nov-26 2003, Wed, 10:29 -0800
Linus Torvalds <torvalds@osdl.org> wrote:

> You can't just randomly use library functions in signal handlers. You can
> only use a very specific "signal-safe" set.
> 
> POSIX lists that set in 3.3.1.3 (3f), and says
> 
> 	"All POSIX.1 functions not in the preceding table and all
> 	 functions defined in the C standard {2} not stated to be callable
> 	 from a signal-catching function are considered to be /unsafe/
> 	 with respect to signals. .."
> 
> typos mine.
> 
> The thing is, they have internal state that makes then non-reentrant (and
> note that even the re-entrant ones might not be signal-safe, since they
> may have deadlock issues: being thread-safe is _not_ the same as being
> signal-safe).

I believe it would be very useful to have this information included in
the standard Linux signal(2) manpage.  (I've just verified it's not in
man-pages-1.60.)

What do you think, Andries?

-- 
Tomas Szepe <szepe@pinerecords.com>
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