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, Version 1.0 only
   6  * (the "License").  You may not use this file except in compliance
   7  * with the License.
   8  *
   9  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
  10  * or http://www.opensolaris.org/os/licensing.
  11  * See the License for the specific language governing permissions
  12  * and limitations under the License.
  13  *
  14  * When distributing Covered Code, include this CDDL HEADER in each
  15  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  16  * If applicable, add the following below this CDDL HEADER, with the
  17  * fields enclosed by brackets "[]" replaced with your own identifying
  18  * information: Portions Copyright [yyyy] [name of copyright owner]
  19  *
  20  * CDDL HEADER END
  21  */
  22 /*
  23  * Copyright (c) 1997-2001 by Sun Microsystems, Inc.
  24  * All rights reserved.
  25  */
  26 
  27 /*      Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T     */
  28 /*        All Rights Reserved   */
  29 
  30 /*
  31  * Copyright (c) 2013 RackTop Systems.
  32  */
  33 
  34 #include <errno.h>
  35 #include <sys/types.h>
  36 #include <stdio.h>
  37 #include <pwd.h>
  38 #include <libcmdutils.h>
  39 
  40 static int findunuseduid(uid_t start, uid_t stop, uid_t *ret);
  41 static boolean_t isreserveduid(uid_t uid);
  42 
  43 /*
  44  * Find the highest unused uid. If the highest unused uid is "stop",
  45  * then attempt to find a hole in the range. Returns 0 on success.
  46  */
  47 int
  48 findnextuid(uid_t start, uid_t stop, uid_t *ret)
  49 {
  50         uid_t uid = start;
  51         struct passwd *pwd;
  52         boolean_t overflow = B_FALSE;
  53 
  54         setpwent();
  55         for (pwd = getpwent(); pwd != NULL; pwd = getpwent()) {
  56                 if (isreserveduid(pwd->pw_uid))              /* Skip reserved IDs */
  57                         continue;
  58                 if (pwd->pw_uid >= uid) {
  59                         if (pwd->pw_uid == stop) {   /* Overflow check */
  60                                 overflow = B_TRUE;
  61                                 break;
  62                         }
  63                         uid = pwd->pw_uid + 1;
  64                 }
  65         }
  66         if (pwd == NULL && errno != 0) {
  67                 endpwent();
  68                 return (-1);
  69         }
  70         endpwent();
  71         if (overflow == B_TRUE)                         /* Find a hole */
  72                 return (findunuseduid(start, stop, ret));
  73         while (isreserveduid(uid) && uid < stop)     /* Skip reserved IDs */
  74                 uid++;
  75         *ret = uid;
  76         return (0);
  77 }
  78 
  79 /*
  80  * Check to see whether the uid is a reserved uid
  81  * -- nobody, noaccess or nobody4
  82  */
  83 static boolean_t
  84 isreserveduid(uid_t uid)
  85 {
  86         return (uid == 60001 || uid == 60002 || uid == 65534);
  87 }
  88 
  89 /*
  90  * findunuseduid() 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 findunuseduid(uid_t start, uid_t stop, uid_t *ret)
  95 {
  96         uid_t uid;
  97 
  98         for (uid = start; uid <= stop; uid++) {
  99                 if (isreserveduid(uid))
 100                         continue;
 101                 if (getpwuid(uid) == NULL) {
 102                         if (errno != 0)
 103                                 return (-1);
 104                         break;
 105                 }
 106         }
 107         if (uid > stop)
 108                 return (-1);
 109         *ret = uid;
 110         return (0);
 111 }