Group Membership Expansion: Guidelines for Deployment

Use NGROUPS_MAX compile-time constant (only when portability is required)

A program that must run on any instance of HP-UX, even one without the group membership

expansion enhancement, must be designed such that it does not rely on the ability to associate more

than 20 supplementary groups with a given user or process.

Incorrect handling of supplementary group ID lists

This section describes how some programs’ built-in assumptions about supplementary group ID limits

can prevent them from working with expanded groups.

Use of NGROUPS compile-time constant

The NGROUPS compile-time constant is obsolete and should never be used.

Use of NGROUPS_MAX compile-time constant when retrieving supplementary group IDs

A process may have more supplementary group IDs associated with it than are specified by the

compile-time constant NGROUPS_MAX. The NGROUPS_MAX compile-time constant should not be used

to size storage to be filled in by the getgroups(2) system call, or as the iteration limit when

searching the array of supplementary group IDs filled in by the getgroups(2) system call.

Use of NGROUPS_MAX compile-time constant when setting supplementary group IDs

Privileged applications setting the list of supplementary group IDs with setgroups(2) must not use

NGROUPS_MAX to limit the number of supplementary group IDs they set.

For more information

For additional information see the following HP-UX man pages: getgroups(2), setgroups(2),

initgroups(3), ngroups_max(5), limits(5).

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4AA2-1738ENW, August 2008