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/* Copyright (C) 1989, 1991, 1993, 1996 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB. If
not, write to the Free Software Foundation, Inc., 675 Mass Ave,
Cambridge, MA 02139, USA. */
#include <ansidecl.h>
#include <unistd.h>
#include <string.h>
#include <grp.h>
#include <limits.h>
#include <sys/types.h>
/* Initialize the group set for the current user
by reading the group database and using all groups
of which USER is a member. Also include GROUP. */
int
DEFUN(initgroups, (user, group),
CONST char *user AND gid_t group)
{
#if defined (NGROUPS_MAX) && NGROUPS_MAX == 0
/* No extra groups allowed. */
return 0;
#else
struct group *g;
register size_t n;
#ifdef NGROUPS_MAX
gid_t groups[NGROUPS_MAX];
#else
long int limit = sysconf (_SC_NGROUPS_MAX);
gid_t *groups;
size_t ngroups;
if (limit > 0)
ngroups = limit;
else
/* No fixed limit on groups. Pick a starting buffer size. */
ngroups = 16;
groups = __alloca (ngroups * sizeof *groups);
#endif
setgrent ();
n = 0;
groups[n++] = group;
while ((g = getgrent ()) != NULL)
if (g->gr_gid != group)
{
register char **m;
for (m = g->gr_mem; *m != NULL; ++m)
if (!strcmp (*m, user))
break;
if (*m == NULL)
{
/* Matched the user. Insert this group. */
if (n == ngroups && limit <= 0)
{
/* Need a bigger buffer. */
groups = memcpy (__alloca (ngroups * 2 * sizeof *groups),
groups, ngroups * sizeof *groups);
ngroups *= 2;
}
groups[n++] = g->gr_gid;
if (n == limit)
/* Can't take any more groups; stop searching. */
break;
}
}
endgrent ();
return setgroups (n, groups);
#endif
}
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