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Name

nis_groups, nis_ismember, nis_addmember, nis_removemember, nis_creategroup, nis_destroygroup, nis_verifygroup, nis_print_group_entry, nis_map_group, __nis_map_group - NIS+ group manipulation functions

Synopsis

cc [ flag... ] file... -lnsl [ library... ]

#include <rpcsvc/nis.h>

bool_t nis_ismember(const nis_name principal, const nis_name group);

nis_error nis_addmember(const nis_name member, const nis_name group);

nis_error nis_removemember(const nis_name member, const nis_name group);

nis_error nis_creategroup(const nis_name group, const u_long flags);

nis_error nis_destroygroup(const nis_name group);

void nis_print_group_entry(const nis_name group);

nis_error nis_verifygroup(const nis_name group);

MT-Level

MT-Safe

Description

These functions manipulate NIS+ groups. They are used by NIS+ clients and servers, and are the interfaces to the group authorization object.

The names of NIS+ groups are syntactically similar to names of NIS+ objects but they occupy a separate namespace. A group named "a.b.c.d." is represented by a NIS+ group object named "a.groups_dir.b.c.d."; the functions described here all expect the name of the group, not the name of the corresponding group object.

There are three types of group members:

Any member may be made negative by prefixing it with a minus sign (’-’). A group may thus contain explicit, implicit, recursive, negative explicit, negative implicit, and negative recursive members.

A principal is considered to belong to a group if it belongs to at least one non-negative group member of the group and belongs to no negative group members.

The nis_ismember() function returns TRUE if it can establish that principal belongs to group; otherwise it returns FALSE.

The nis_addmember() and nis_removemember() functions add or remove a member. They do not check whether the member is valid. The user must have read and modify rights for the group in question.

The nis_creategroup() and nis_destroygroup() functions create and destroy group objects. The user must have create or destroy rights, respectively, for the groups_dir directory in the appropriate domain. The parameter flags to nis_creategroup() is currently unused and should be set to zero.

The nis_print_group_entry() function lists a group’s members on the standard output.

The nis_verifygroup() function returns NIS_SUCCESS if the given group exists, otherwise it returns an error code.

Examples

Simple Memberships

Given a group sadsouls.oz. with members tinman.oz., lion.oz., and scarecrow.oz., the function call

bool_var = nis_ismember("lion.oz.", "sadsouls.oz.");

will return 1 (TRUE) and the function call

bool_var = nis_ismember("toto.oz.", "sadsouls.oz.");

will return 0 (FALSE).

Implicit Memberships

Given a group baddies.oz., with members wickedwitch.west.oz. and *.monkeys.west.oz., the function call

bool_var = nis_ismember("hogan.monkeys.west.oz.", "baddies.oz.");

will return 1 (TRUE) because any principal from the monkeys.west.oz. domain belongs to the implicit group *.monkeys.west.oz., but the function call

bool_var = nis_ismember("hogan.big.monkeys.west.oz.", "baddies.oz.");

will return 0 (FALSE).

Recursive Memberships

Given a group goodandbad.oz., with members toto.kansas, @sadsouls.oz., and @baddies.oz., and the groups sadsouls.oz. and baddies.oz. defined above, the function call

bool_var = nis_ismember("wickedwitch.west.oz.", "goodandbad.oz.");

will return 1 (TRUE), because wickedwitch.west.oz. is a member of the baddies.oz. group which is recursively included in the goodandbad.oz. group.

See Also

nisgrpadm(1) , nis_objects(3N)

Notes

These functions only accept fully-qualified NIS+ names.

A group is represented by a NIS+ object (see nis_objects(3N) ) with a variant part that is defined in the group_obj structure. It contains the following fields: 


u_long    gr_flags;    /* Interpretation Flags 
            (currently unused) */
struct {
    u_int    gr_members_len;    
    nis_name    *gr_members_val; 
} gr_members;        /* Array of members */

NIS+ servers and clients maintain a local cache of expanded groups to enhance their performance when checking for group membership. Should the membership of a group change, servers and clients with that group cached will not see the change until either the group cache has expired or it is explicitly flushed. A server’s cache may be flushed programmatically by calling the nis_servstate() function with tag TAG_GCACHE and a value of 1.

There are currently no known methods for nis_ismember(), nis_print_group_entry(), and nis_verifygroup() to get their answers from only the master server.

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