1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License (the "License").
   6  * You may not use this file except in compliance with the License.
   7  *
   8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9  * or http://www.opensolaris.org/os/licensing.
  10  * See the License for the specific language governing permissions
  11  * and limitations under the License.
  12  *
  13  * When distributing Covered Code, include this CDDL HEADER in each
  14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15  * If applicable, add the following below this CDDL HEADER, with the
  16  * fields enclosed by brackets "[]" replaced with your own identifying
  17  * information: Portions Copyright [yyyy] [name of copyright owner]
  18  *
  19  * CDDL HEADER END
  20  */
  21 /*
  22  * Copyright 2007 Sun Microsystems, Inc.  All rights reserved.
  23  * Use is subject to license terms.
  24  */
  25 
  26 /*      Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T     */
  27 /*        All Rights Reserved   */
  28 
  29 /*
  30  * Copyright (c) 2013 RackTop Systems.
  31  */
  32 
  33 #include <errno.h>
  34 #include <sys/types.h>
  35 #include <stdio.h>
  36 #include <grp.h>
  37 #include <libcmdutils.h>
  38 
  39 static int findunusedgid(gid_t start, gid_t stop, gid_t *ret);
  40 static boolean_t isreservedgid(gid_t gid);
  41 
  42 /*
  43  * Find the highest unused uid. If the highest unused gid is "stop",
  44  * then attempt to find a hole in the range. Returns 0 on success.
  45  */
  46 int
  47 findnextgid(gid_t start, gid_t stop, gid_t *ret)
  48 {
  49         gid_t gid = start;
  50         struct group *grp;
  51         boolean_t overflow = B_FALSE;
  52 
  53         setgrent();
  54         for (grp = getgrent(); grp != NULL; grp = getgrent()) {
  55                 if (isreservedgid(grp->gr_gid))              /* Skip reserved IDs */
  56                         continue;
  57                 if (grp->gr_gid >= gid) {
  58                         if (grp->gr_gid == stop) {   /* Overflow check */
  59                                 overflow = B_TRUE;
  60                                 break;
  61                         }
  62                         gid = grp->gr_gid + 1;
  63                 }
  64         }
  65         if (grp == NULL && errno != 0) {
  66                 endgrent();
  67                 return (-1);
  68         }
  69         endgrent();
  70         if (overflow == B_TRUE)                         /* Find a hole */
  71                 return (findunusedgid(start, stop, ret));
  72         while (isreservedgid(gid) && gid < stop)     /* Skip reserved IDs */
  73                 gid++;
  74         *ret = gid;
  75         return (0);
  76 }
  77 
  78 /*
  79  * Check to see whether the gid is a reserved gid
  80  * -- nobody, noaccess or nogroup
  81  */
  82 static boolean_t
  83 isreservedgid(gid_t gid)
  84 {
  85         return (gid == 60001 || gid == 60002 || gid == 65534);
  86 }
  87 
  88 /*
  89  * findunusedgid() attempts to return the next valid usable id between the
  90  * supplied upper and lower limits. Returns 0 on success.
  91  */
  92 static int
  93 findunusedgid(gid_t start, gid_t stop, gid_t *ret)
  94 {
  95         gid_t gid;
  96 
  97         for (gid = start; gid <= stop; gid++) {
  98                 if (isreservedgid(gid))
  99                         continue;
 100                 if (getgrgid(gid) == NULL) {
 101                         if (errno != 0)
 102                                 return (-1);
 103                         break;
 104                 }
 105         }
 106         if (gid > stop)
 107                 return (-1);
 108         *ret = gid;
 109         return (0);
 110 }