usr/src/lib/libcmdutils/common/gid.c

   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 <userdefs.h>
  37 #include <grp.h>
  38 #include <libcmdutils.h>
  39
  40 static int findunusedgid(gid_t start, gid_t stop, gid_t *ret);
  41 static boolean_t isreservedgid(gid_t gid);
  42
  43 /*
  44  * Find the highest unused uid. If the highest unused gid is "stop",
  45  * then attempt to find a hole in the range. Returns 0 on success.
  46  */
  47 int
  48 findnextgid(gid_t start, gid_t stop, gid_t *ret)
  49 {
  50         gid_t gid = start;
  51         struct group *grp;
  52         boolean_t overflow = B_FALSE;
  53
  54         setgrent();
  55         for (grp = getgrent(); grp != NULL; grp = getgrent()) {
  56                 if (isreservedgid(grp->gr_gid))         /* Skip reserved IDs */
  57                         continue;
  58                 if (grp->gr_gid >= gid) {
  59                         if (grp->gr_gid == stop) {      /* Overflow check */
  60                                 overflow = B_TRUE;
  61                                 break;
  62                         }
  63                         gid = grp->gr_gid + 1;
  64                 }
  65         }
  66         if (grp == NULL && errno != 0) {
  67                 endgrent();
  68                 return (-1);
  69         }
  70         endgrent();
  71         if (overflow == B_TRUE)                         /* Find a hole */
  72                 return (findunusedgid(start, stop, ret));
  73         while (isreservedgid(gid) && gid < stop)        /* Skip reserved IDs */
  74                 gid++;
  75         *ret = gid;
  76         return (0);
  77 }
  78
  79 /*
  80  * Check to see whether the gid is a reserved gid
  81  * -- nobody, noaccess or nogroup
  82  */
  83 static boolean_t
  84 isreservedgid(gid_t gid)
  85 {
  86         return (gid == 60001 || gid == 60002 || gid == 65534);
  87 }
  88
  89 /*
  90  * findunusedgid() attempts to return the next valid usable id between the
  91  * supplied upper and lower limits. Returns 0 on success.
  92  */
  93 static int
  94 findunusedgid(gid_t start, gid_t stop, gid_t *ret)
  95 {
  96         gid_t gid;
  97
  98         for (gid = start; gid <= stop; gid++) {
  99                 if (isreservedgid(gid))
 100                         continue;
 101                 if (getgrgid(gid) == NULL) {
 102                         if (errno != 0)
 103                                 return (-1);
 104                         break;
 105                 }
 106         }
 107         if (gid > stop)
 108                 return (-1);
 109         *ret = gid;
 110         return (0);
 111 }