grp/initgroups.c

   1 /* Copyright (C) 1989, 1991, 1993 Free Software Foundation, Inc.
   2 This file is part of the GNU C Library.
   3
   4 The GNU C Library is free software; you can redistribute it and/or
   5 modify it under the terms of the GNU Library General Public License as
   6 published by the Free Software Foundation; either version 2 of the
   7 License, or (at your option) any later version.
   8
   9 The GNU C Library 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 GNU
  12 Library General Public License for more details.
  13
  14 You should have received a copy of the GNU Library General Public
  15 License along with the GNU C Library; see the file COPYING.LIB.  If
  16 not, write to the Free Software Foundation, Inc., 675 Mass Ave,
  17 Cambridge, MA 02139, USA.  */
  18
  19 #include <ansidecl.h>
  20 #include <unistd.h>
  21 #include <string.h>
  22 #include <grp.h>
  23 #include <limits.h>
  24 #include <sys/types.h>
  25
  26
  27 /* Initialize the group set for the current user
  28    by reading the group database and using all groups
  29    of which USER is a member.  Also include GROUP.  */
  30 int
  31 DEFUN(initgroups, (user, group),
  32       CONST char *user AND gid_t group)
  33 {
  34 #ifdef NGROUPS_MAX
  35 #if NGROUPS_MAX == 0
  36   return 0;
  37 #else
  38   static PTR info = NULL;
  39   register FILE *stream;
  40   register struct group *g;
  41   gid_t groups[NGROUPS_MAX];
  42   register size_t n;
  43
  44   if (info == NULL)
  45     {
  46       info = __grpalloc();
  47       if (info == NULL)
  48         return -1;
  49     }
  50
  51   stream = __grpopen();
  52   if (stream == NULL)
  53     return -1;
  54
  55   n = 0;
  56   groups[n++] = group;
  57
  58   while (n < NGROUPS_MAX && (g = __grpread(stream, info)) != NULL)
  59     if (g->gr_gid != group)
  60       {
  61         register char **m;
  62
  63         for (m = g->gr_mem; *m != NULL; ++m)
  64           if (!strcmp(*m, user))
  65             groups[n++] = g->gr_gid;
  66       }
  67
  68   return setgroups(n, groups);
  69 #endif
  70 #else
  71   return 0;
  72 #endif
  73 }