Messages in this thread | | | Date | Tue, 24 Feb 2004 17:14:51 -0800 | From | Tim Hockin <> | Subject | Re: PATCH: report NGROUPS_MAX via a sysctl (read-only) |
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On Wed, Feb 25, 2004 at 11:29:27AM +1030, Glen Turner wrote: > The mere existence of the value means it can be used correctly > in application code for sanity checking.
Andrew seems to have picked it up for -mm. I sent a patch to glibc-bugs (is that the right place? any libc folk?) to use the new sysctl in sysconf(_SC_NGROUPS_MAX). So if/when all those releases converge, you should be able to get the kernel's idea of NGROUPS_MAX from sysconf(_SC_NGROUPS_MAX);
> Returning INT_MAX for NGROUPS_MAX isn't wrong, but you > then can't blame user space for making inefficient choices > if the kernel limit is actually smaller.
Well, if the kernel HAS no limit, then NGROUPS_MAX really is INT_MAX. There are not many legit uses I can think of for userspace to actually care about NGROUPS_MAX. Just the current number of groups, which is easily gotten via setgroups().
Now that the sysctl is in, it's a very tiny patch to make ngroups_max actually raisable/ by sysctl, though it is debatable whether it is useful AT ALL, and dubious whether it is safe to lower that value after any apps are running.
-- Tim Hockin thockin@hockin.org Soon anyone who's not on the World Wide Web will qualify for a government subsidy for the home-pageless. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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