GNU bug report logs - #12446
port better to POSIX hosts lacking _setjmp

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Message #34 received at 12446 <at> debbugs.gnu.org (full text, mbox):

From: Paul Eggert <eggert <at> cs.ucla.edu>
To: Eli Zaretskii <eliz <at> gnu.org>
Cc: lekktu <at> gmail.com, 12446 <at> debbugs.gnu.org
Subject: Re: port better to POSIX hosts lacking _setjmp
Date: Sat, 15 Sep 2012 01:55:14 -0700

On 09/15/2012 01:28 AM, Eli Zaretskii wrote:
> So what was the rationale of turning away from _setjmp

Some POSIXish hosts lack _setjmp, but have sigsetjmp,
and their longjmp implementations munge the signal masks.

>> > Messups are trickier, because they involve rare race conditions.
>> > They can occur if Emacs or a system call has set the signal mask to X,
>> > but a longjump unexpectedly changes it to Y, where Y is not equal to X.
> Why is that a messup?

Because Emacs then continues with the wrong sigmask, which can
cause signals to be blocked when they shouldn't be.

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