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 /*      Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T     */
  26 /*        All Rights Reserved   */
  27 
  28 
  29 #pragma ident   "%Z%%M% %I%     %E% SMI"        /* SVr4.0 1.5 */
  30 
  31 #include <sys/types.h>
  32 #include <stdio.h>
  33 #include <userdefs.h>
  34 
  35 #include <sys/param.h>
  36 #ifndef MAXUID
  37 #include <limits.h>
  38 #ifdef UID_MAX
  39 #define MAXUID  UID_MAX
  40 #else
  41 #define MAXUID  60000
  42 #endif
  43 #endif
  44 
  45 /*
  46  * Check to see that the gid is not a reserved gid
  47  * -- nobody, noaccess or nogroup
  48  */
  49 static int
  50 isvalidgid(gid_t gid)
  51 {
  52         return (gid != 60001 && gid != 60002 && gid != 65534);
  53 }
  54 
  55 gid_t
  56 findnextgid()
  57 {
  58         FILE *fptr;
  59         gid_t last, next;
  60         gid_t gid;
  61 
  62         /*
  63          * Sort the used GIDs in decreasing order to return MAXUSED + 1
  64          */
  65         if ((fptr = popen("exec sh -c "
  66             "\"getent group|cut -f3 -d:|sort -nr|uniq \" 2>/dev/null",
  67             "r")) == NULL)
  68                 return (-1);
  69 
  70         if (fscanf(fptr, "%u\n", &next) == EOF) {
  71                 (void) pclose(fptr);
  72                 return (DEFRID + 1);
  73         }
  74 
  75         /*
  76          * 'next' is now the highest allocated gid.
  77          *
  78          * The simplest allocation is where we just add one, and obtain
  79          * a valid gid.  If this fails look for a hole in the gid range ..
  80          */
  81 
  82         last = MAXUID;          /* upper limit */
  83         gid = -1;               /* start invalid */
  84         do {
  85                 if (!isvalidgid(next))
  86                         continue;
  87 
  88                 if (next <= DEFRID) {
  89                         if (last != DEFRID + 1)
  90                                 gid = DEFRID + 1;
  91                         break;
  92                 }
  93 
  94                 if ((gid = next + 1) != last) {
  95                         while (!isvalidgid(gid))
  96                                 gid++;
  97                         if (gid > 0 && gid < last)
  98                                 break;
  99                 }
 100 
 101                 gid = -1;
 102                 last = next;
 103 
 104         } while (fscanf(fptr, "%u\n", &next) != EOF);
 105 
 106         (void) pclose(fptr);
 107 
 108         return (gid);
 109 }