On Thu, 7 Nov 2024 12:09:25 +0000 Mailer <vine24683...@gmail.com> wrote: > On Thu, 7 Nov 2024 12:23:08 +0100 > Maxime Devos <maximede...@telenet.be> wrote: > > ‘atexit’ functions are run at ‘exit’. ‘exit’ can be run from signal > > handlers (*). Since the hook runs Scheme code, it could do a lot of > > AC-unsafe things, resulting in problems. > > > > (*) glibc documentation says ‘exit’ is AC-unsafe, but this is > > unsupported by POSIX AFAICT. OTOH the same applies to even ‘malloc’, > > so likely I’m looking in the wrong places. > > I think you meant async-signal-safe (AS-safe). 'exit' is not a-s-s and > cannot be called in a signal handler (for example it can flush buffers) > whereas '_exit' is a-s-s. Furthermore a registered handler cannot > itself safely call 'exit'. > > I believe the main reason that use of 'atexit' or 'on_exit' is > discouraged is that it does not handle abnormal process termination. > (Registered handlers also don't run on termination by '_exit', but that > is usually what you want.)
I believe also that use of 'atexit' is discouraged in dynamically linked libraries because of the uncertain timing of the unloading of the library, but I think in fact glibc is OK with this, so I guess it may depend on your libc. Chris
