lib/getugroups.c

   1 /* getugroups.c -- return a list of the groups a user is in
   2    Copyright (C) 1990, 1991, 1998 Free Software Foundation.
   3
   4    This program is free software; you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation; either version 2, or (at your option)
   7    any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program; if not, write to the Free Software Foundation,
  16    Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
  17
  18 /* Written by David MacKenzie. */
  19
  20 #ifdef HAVE_CONFIG_H
  21 # include <config.h>
  22 #endif
  23
  24 #include <sys/types.h>
  25 #include <stdio.h> /* grp.h on alpha OSF1 V2.0 uses "FILE *". */
  26 #include <grp.h>
  27
  28 #ifdef HAVE_UNISTD_H
  29 # include <unistd.h>
  30 #endif
  31
  32 /* setgrent, getgrent, and endgrent are not specified by POSIX.1,
  33    so header files might not declare them.
  34    If you don't have them at all, we can't implement this function.
  35    You lose!  */
  36 struct group *getgrent ();
  37
  38 #if defined(STDC_HEADERS) || defined(HAVE_STRING_H)
  39 # include <string.h>
  40 #else
  41 # include <strings.h>
  42 #endif
  43
  44 /* Like `getgroups', but for user USERNAME instead of for
  45    the current process. */
  46
  47 int
  48 getugroups (int maxcount, GETGROUPS_T *grouplist, char *username)
  49 {
  50   struct group *grp;
  51   register char **cp;
  52   register int count = 0;
  53
  54   setgrent ();
  55   while ((grp = getgrent ()) != 0)
  56     for (cp = grp->gr_mem; *cp; ++cp)
  57       if (!strcmp (username, *cp))
  58         {
  59           int n;
  60
  61           /* See if this group number is already on the list.  */
  62           for (n = 0; n < count; ++n)
  63             if (grouplist[n] == grp->gr_gid)
  64               break;
  65
  66           /* If it's a new group number, then try to add it to the list.  */
  67           if (n == count)
  68             {
  69               if (maxcount != 0)
  70                 {
  71                   if (count >= maxcount)
  72                     {
  73                       endgrent ();
  74                       return count;
  75                     }
  76                   grouplist[count] = grp->gr_gid;
  77                 }
  78               count++;
  79             }
  80         }
  81   endgrent ();
  82   return count;
  83 }