Re: [musl] [PATCH] add close_range() syscall wrapper

[Rich Felker <dalias@libc.org>]

On Fri, Sep 01, 2023 at 04:55:53PM +0200, Natanael Copa wrote:
> On Fri, 1 Sep 2023 09:57:34 -0400
> Rich Felker <dalias@libc.org> wrote:
> 
> 
> > > +int close_range(unsigned int first, unsigned int last, int flags)
> > > +{
> > > +	return __syscall_ret(syscall(SYS_close_range, first, last, flags));
> > > +}
> > > -- 
> > > 2.42.0  
> > 
> > This is double-processing errno. You need either return
> > __syscall_ret(__syscall(...)) (note the second __) or just return
> > syscall(...) (the syscall macro without __ automatically does the
> > __syscall_ret).
> 
> Ah, ok, I'll send a v2 patch.
> 
> > Aside from that, I think there's a question whether, if we support
> > this as a function rather than leaving it to the application to use
> > the syscall, we should provide a fallback for ENOSYS. I'm not sure,
> > but it's something that should be considered before adding it.
> 
> It was mentioned earlier that CPython expects close_range() to
> async-safe, and that glibc does not provide fallback. I would prefer
> that musl does not provide fallback.
> 
> https://www.openwall.com/lists/musl/2022/08/18/4

If musl were to provide a fallback it would be AS-safe.

Rich