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/* Copyright (C) 1989, 1991, 1993, 1996, 1997 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., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA. */
#include <alloca.h>
#include <errno.h>
#include <grp.h>
#include <limits.h>
#include <string.h>
#include <unistd.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
initgroups (user, group)
const char *user;
gid_t group;
{
#if defined NGROUPS_MAX && NGROUPS_MAX == 0
/* No extra groups allowed. */
return 0;
#else
struct group grpbuf, *g;
size_t buflen = sysconf (_SC_GETPW_R_SIZE_MAX);
char *tmpbuf;
size_t n;
size_t ngroups;
gid_t *groups;
int status;
#ifdef NGROUPS_MAX
# define limit NGROUPS_MAX
ngroups = limit;
#else
long int limit = sysconf (_SC_NGROUPS_MAX);
if (limit > 0)
ngroups = limit;
else
/* No fixed limit on groups. Pick a starting buffer size. */
ngroups = 16;
#endif
groups = __alloca (ngroups * sizeof *groups);
tmpbuf = __alloca (buflen);
setgrent ();
n = 0;
groups[n++] = group;
do
{
while ((status = __getgrent_r (&grpbuf, tmpbuf, buflen, &g)) != 0
&& errno == ERANGE)
{
buflen *= 2;
tmpbuf = __alloca (buflen);
}
if (status == 0 && g->gr_gid != group)
{
char **m;
for (m = g->gr_mem; *m != NULL; ++m)
if (strcmp (*m, user) == 0)
{
/* Matches user. Insert this group. */
if (n == ngroups && limit <= 0)
{
/* Need a bigger buffer. */
gid_t *newgrp;
newgrp = __alloca (ngroups * 2 * sizeof *groups);
groups = memcpy (newgrp, groups, ngroups * sizeof *groups);
ngroups *= 2;
}
groups[n++] = g->gr_gid;
if (n == limit)
/* Can't take any more groups; stop searching. */
goto done;
break;
}
}
}
while (status == 0);
done:
endgrent ();
return setgroups (n, groups);
#endif
}
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