Why is max groups set so low (16)?

Samy Al Bahra samy at kerneled.com
Sat Nov 29 13:23:36 PST 2003

On Wed, 26 Nov 2003 13:37:15 +1100 (EST)
Bruce Evans <bde at zeta.org.au> wrote:

> The binary compatibility problems seem to be small.  libc doesn't have
> any references at all to NGROUPS_MAX except in man pages, but that is
> partly because it mostly misspells NGROUPS_MAX as NGROUPS.

This isn't a misspelling, param.h defines the following:
#define NGROUPS         NGROUPS_MAX     /* max number groups */

> getgroups(2) and setgroups(2) are limited by whatever the kernel
> wants, not by their API, although their documentation says that there
> is a compile-time limit

setgroups does not allow a user to be in a a greater number of groups
than NGROUPS. It references this macro directly, meaning, it is a
compile-time limit.

Could you elaborate on what you mean exactly by "whatever the kernel

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