lookup.subproj/initgroups.3

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  56 .Dd June 4, 1993
  57 .Dt INITGROUPS 3
  58 .Os
  59 .Sh NAME
  60 .Nm initgroups
  61 .Nd initialize group access list
  62 .Sh LIBRARY
  63 Standard system libraries.
  64 .Sh SYNOPSIS
  65 .In unistd.h
  66 .Ft int
  67 .Fn initgroups "const char *name" "int basegid"
  68 .Sh DESCRIPTION
  69 The
  70 .Fn initgroups
  71 function calculates a group access list for the user
  72 specified in
  73 .Fa name .
  74 This group list is then saved in the kernel credentials for the current process.
  75 The
  76 .Fa basegid
  77 is included in the groups list.
  78 Typically this value is given as
  79 the default group associated with the user's account record.
  80 .Pp
  81 This function sets at most 16 group IDs in the process credentials.
  82 This list can be retrieved using the
  83 .Xr getgroups 2
  84 function.
  85 Note that OS X supports group membership in an unlimited number of groups.
  86 The OS X kernel uses the group list stored in the process credentials only
  87 as an initial cache.
  88 Additional group memberships are determined by communication between the operating system and the
  89 .Nm opendirectoryd
  90 daemon.
  91 .Pp
  92 Processes should not use the group ID numbers from
  93 .Xr getgroups 2
  94 to determine a user's group membership.
  95 The list obtained from
  96 .Fn getgroups
  97 may only be a partial list of a user's group membership.
  98 Membership checks should use the
  99 .Xr mbr_gid_to_uuid 3 ,
 100 .Xr mbr_uid_to_uuid 3 ,
 101 and
 102 .Xr mbr_check_membership 3
 103 functions.
 104 .Sh RETURN VALUES
 105 The
 106 .Fn initgroups
 107 function
 108 returns 0 on success.
 109 On failure, this function will return -1 and set
 110 .Va errno
 111 to one of the following values:
 112 .Bl -tag -width ".Bq Er EFAULT"
 113 .It Bq Er EPERM
 114 The caller's effictive UID is not zero.
 115 .It Bq Er EINVAL
 116 Internal error, an invalid array size was supplied to the kernel.
 117 .It Bq Er EFAULT
 118 Internal error, invalid data was supplied to the kernel.
 119 .El
 120 .Sh SEE ALSO
 121 .Xr getgroups 2 ,
 122 .Xr getgrouplist 3 ,
 123 .Xr mbr_gid_to_uuid 3 ,
 124 .Xr mbr_uid_to_uuid 3 ,
 125 .Xr mbr_check_membership 3 .
 126 .Sh HISTORY
 127 The
 128 .Fn initgroups
 129 function appeared in
 130 .Bx 4.2 .