On Fri, Oct 18, 2019 at 11:31:15AM +0200, Thomas Huth wrote: > On 22/01/2019 19.10, Eric Blake wrote: > > On 1/22/19 11:23 AM, Daniel P. Berrangé wrote: > > > >> > >>>> On this point though, does anyone know of any platforms we support[1], > >>>> or are likely to support in future, where 'strerror' is *not* thread > >>>> safe ? > >>> > >>> I'm not coming up with one, and I think the problem is independent of > >>> this series (if we DO have a problem, it's a series all its own to > >>> eradicate the use of strerror() in favor of something safer, either > >>> picking strerror_l() or dealing with the glibc vs. BSD differences in > >>> strerror_r()). > >> > >> Agree that its not really something for this series - this just > >> made me think of it again. > > > > Shoot - FreeBSD strerror() is not threadsafe: > > https://github.com/freebsd/freebsd/blob/master/lib/libc/string/strerror.c#L119 > > > > char * > > strerror(int num) > > { > > static char ebuf[NL_TEXTMAX]; > > > > if (strerror_r(num, ebuf, sizeof(ebuf)) != 0) > > errno = EINVAL; > > return (ebuf); > > } > > > >> > >> We went through the scrubbing in libvirt to use the sane, but still > >> tedious to call, variant of strerror_r() many years ago. With luck > >> though it is a worry that can be confined the dustbin of ancient > >> UNIX history....unless someone can point to evidence to the contrary ? > > > > libvirt has it easy - they let gnulib do all the work of futzing around > > with getting a working strerror() despite platform bugs and despite > > glibc's insistence on a non-POSIX signature if _GNU_SOURCE is defined. > > We'll have to do a bit more legwork. > > > > That said, I've added it to: > > https://wiki.qemu.org/Contribute/BiteSizedTasks#Error_checking > > > > if someone wants to do the grunt work. > > I think we should change that task to switch to g_strerror() from glib > instead ... as far as I can see, this is a proper wrapper around > strerror_r(), so we don't have to deal with the implementation oddities > of strerror_r() in QEMU.
Yeah, I think using g_strerror() makes sense. We've just adopted that in libvirt precisely to avoid these platform portability oddities and the really unpleasant API calling convention of strerror_r(). Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
