[PATCH] ntdll: Use the true maximum open FDs to set the limit on Mac.

[Charles Davis]

On Tue, Apr 19, 2022 at 11:42 AM Brendan Shanks <bshanks at codeweavers.com> wrote:
>
> Hi Chip,
>
> > On Apr 14, 2022, at 11:29 AM, Chip Davis <cdavis5x at gmail.com> wrote:
> >
> > The actual upper limit is stored in the sysctl(3)
> > "kern.maxfilesperproc". This value may be higher than the value of the
> > OPEN_MAX constant.
> >
> > Using sysconf(3) with _SC_OPEN_MAX just returns the current value of
> > RLIMIT_NOFILE, so that won't work here.
> >
> > Signed-off-by: Chip Davis <cdavis5x at gmail.com>
> > ---
> > Fixing this in the place it *actually* needs to be fixed this time...
> > ---
> > dlls/ntdll/unix/loader.c | 28 ++++++++++++++++++++++------
> > 1 file changed, 22 insertions(+), 6 deletions(-)
> >
> > diff --git a/dlls/ntdll/unix/loader.c b/dlls/ntdll/unix/loader.c
> > index d5867e4aa754..dc54a54a225f 100644
> > --- a/dlls/ntdll/unix/loader.c
> > +++ b/dlls/ntdll/unix/loader.c
> > @@ -452,13 +452,29 @@ static void set_max_limit( int limit )
> >         rlimit.rlim_cur = rlimit.rlim_max;
> >         if (setrlimit( limit, &rlimit ) != 0)
> >         {
> > -#if defined(__APPLE__) && defined(RLIMIT_NOFILE) && defined(OPEN_MAX)
> > -            /* On Leopard, setrlimit(RLIMIT_NOFILE, ...) fails on attempts to set
> > -             * rlim_cur above OPEN_MAX (even if rlim_max > OPEN_MAX). */
> > -            if (limit == RLIMIT_NOFILE && rlimit.rlim_cur > OPEN_MAX)
> > +#if defined(__APPLE__) && defined(RLIMIT_NOFILE) && (defined(OPEN_MAX) || defined(KERN_MAXFILESPERPROC))
>
> Are the OPEN_MAX/KERN_MAXFILESPERPROC ifdefs (and fallback to INT_MAX) necessary? KERN_MAXFILESPERPROC seems to have been present since 10.0 (https://github.com/apple-oss-distributions/xnu/blob/c1dac77fcd1f9be7193cad5411c413ae4cf1102a/bsd/sys/sysctl.h#L287), and OPEN_MAX at least since 10.5 (https://github.com/apple-oss-distributions/xnu/blame/cc9a63552421e7db025ad771974f3e9f479948ad/bsd/sys/syslimits.h#L88).

Huh. Then I guess the #ifdefs aren't needed after all.

>
> Also, I tested this on macOS 12.4 on M1, and the initial setrlimit(RLIMIT_NOFILE, …) call actually succeeds, even though rlim_max is LONG_MAX, way larger than kern.maxfilesperproc. setrlimit() does fail on 10.13 though.

It fails on 10.14, too.