Messages in this thread | | | Date | Thu, 19 Feb 2004 22:35:19 -0800 | From | Tim Hockin <> | Subject | Re: PATCH: report NGROUPS_MAX via a sysctl (read-only) |
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On Thu, Feb 19, 2004 at 09:30:28PM -0800, Andrew Morton wrote: > > Attached is a simple patch to expose NGROUPS_MAX via sysctl. > > Why does userspace actually care? You try to do an oversized setgroups(), > so you get an error?
I am systematically tracking down apps that use it. glibc is almost free of it. sysconf() still uses it, but as long as the value compiled into glibc as NGROUPS_MAX is less-than-or-equal-to the current kernel's idea, it meets POSIX, right? If any one goes into their kernel source and lowers NGROUPS_MAX they might break things, but I guess that isn't too big of a worry. Some apps are still assuming that the value they get from sysconf() is the absolute max number of groups. Anyone with libc compiled against an older kernel will see 32, when they could have 64k.
> And why does NGROUPS_MAX still exist, come to that? AFAICT the only thing
Because Linus would not let me set it to INT_MAX. Something about "insanity" ;)
As long as we can convince userspace apps to not trust sysconf() or NGROUPS_MAX constants, I guess we don't *need* it exposed. I guess that's a veto, then?
-- Tim Hockin Sun Microsystems, Linux Software Engineering thockin@sun.com All opinions are my own, not Sun's - 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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