1 /* Copyright (C) 1989, 1991, 1993, 1996 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
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.
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.
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. */
24 #include <sys/types.h>
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. */
31 DEFUN(initgroups, (user, group),
32 CONST char *user AND gid_t group)
34 #if defined (NGROUPS_MAX) && NGROUPS_MAX == 0
36 /* No extra groups allowed. */
44 gid_t groups[NGROUPS_MAX];
46 long int limit = sysconf (_SC_NGROUPS_MAX);
53 /* No fixed limit on groups. Pick a starting buffer size. */
56 groups = __alloca (ngroups * sizeof *groups);
64 while ((g = getgrent ()) != NULL)
65 if (g->gr_gid != group)
69 for (m = g->gr_mem; *m != NULL; ++m)
70 if (!strcmp (*m, user))
75 /* Matched the user. Insert this group. */
76 if (n == ngroups && limit <= 0)
78 /* Need a bigger buffer. */
79 groups = memcpy (__alloca (ngroups * 2 * sizeof *groups),
80 groups, ngroups * sizeof *groups);
84 groups[n++] = g->gr_gid;
87 /* Can't take any more groups; stop searching. */
94 return setgroups (n, groups);