initgroups(3) [mojave man page]

INITGROUPS(3)						   BSD Library Functions Manual 					     INITGROUPS(3)

NAME

     initgroups -- initialize group access list

LIBRARY

     Standard system libraries.

SYNOPSIS

     #include <unistd.h>

     int
     initgroups(const char *name, int basegid);

DESCRIPTION

     The initgroups() function calculates a group access list for the user specified in name.  This group list is then saved in the kernel creden-
     tials for the current process.  The basegid is included in the groups list.  Typically this value is given as the default group associated
     with the user's account record.

     This function sets at most 16 group IDs in the process credentials.  This list can be retrieved using the getgroups(2) function.  Note that
     OS X supports group membership in an unlimited number of groups.  The OS X kernel uses the group list stored in the process credentials only
     as an initial cache.  Additional group memberships are determined by communication between the operating system and the opendirectoryd dae-
     mon.

     Processes should not use the group ID numbers from getgroups(2) to determine a user's group membership.  The list obtained from getgroups()
     may only be a partial list of a user's group membership.  Membership checks should use the mbr_gid_to_uuid(3), mbr_uid_to_uuid(3), and
     mbr_check_membership(3) functions.

RETURN VALUES

     The initgroups() function returns 0 on success.  On failure, this function will return -1 and set errno to one of the following values:

     [EPERM]   The caller's effictive UID is not zero.

     [EINVAL]  Internal error, an invalid array size was supplied to the kernel.

     [EFAULT]  Internal error, invalid data was supplied to the kernel.

SEE ALSO

     getgroups(2), getgrouplist(3), mbr_gid_to_uuid(3), mbr_uid_to_uuid(3), mbr_check_membership(3).

HISTORY

     The initgroups() function appeared in 4.2BSD.

BSD
								   June 4, 1993 							       BSD

GETGROUPLIST(3) 					   BSD Library Functions Manual 					   GETGROUPLIST(3)

NAME

     getgrouplist, getgroupmembership, -- calculate group access list

LIBRARY

     Standard C Library (libc, -lc)

SYNOPSIS

     #include <unistd.h>

     int
     getgrouplist(const char *name, gid_t basegid, gid_t *groups, int *ngroups);

     int
     getgroupmembership(const char *name, gid_t basegid, gid_t *groups, int maxgrp, int *ngroups);

DESCRIPTION

     The getgrouplist() and getgroupmembership() functions read through the group database and calculate the group access list for the user speci-
     fied in name.  The basegid is automatically included in the groups list.  Typically this value is given as the group number from the password
     database.

     The resulting group list is returned in the integer array pointed to by groups.

     For getgrouplist(), the caller specifies the size of the groups array in the integer pointed to by ngroups.

     For getgroupmembership(), the caller specifies the size of the groups array in maxgrp.

     The actual number of groups found is returned in ngroups.

     Duplicate group ids will be suppressed from the result.

RETURN VALUES

     The getgrouplist() and getgroupmembership() functions return 0 if successful, and return -1 if the size of the group list is too small to
     hold all the user's groups.  In the latter case, the groups array will be filled with as many groups as will fit and ngroups will contain the
     total number of groups found.

FILES

     /etc/group  group membership list

SEE ALSO

     setgroups(2), initgroups(3), group(5)

HISTORY

     The getgrouplist() function first appeared in 4.4BSD.  The getgroupmembership() function first appeared in NetBSD 3.0 to address an API defi-
     ciency in getgrouplist().

BUGS

     The getgrouplist() function uses the routines based on getgrent(3).  If the invoking program uses any of these routines, the group structure
     will be overwritten in the call to getgrouplist().

BSD
								  January 6, 2005							       BSD