+
−/* provide consistent interface to getgroups for systems that don't allow N==0
+
−
+
−   Copyright (C) 1996, 1999, 2003, 2006-2013 Free Software Foundation, Inc.
+
−
+
−   This program is free software: you can redistribute it and/or modify
+
−   it under the terms of the GNU General Public License as published by
+
−   the Free Software Foundation; either version 3 of the License, or
+
−   (at your option) any later version.
+
−
+
−   This program 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 General Public License for more details.
+
−
+
−   You should have received a copy of the GNU General Public License
+
−   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
−
+
−/* written by Jim Meyering */
+
−
+
−#include <config.h>
+
−
+
−#include <unistd.h>
+
−
+
−#include <errno.h>
+
−#include <stdlib.h>
+
−#include <stdint.h>
+
−
+
−#if !HAVE_GETGROUPS
+
−
+
−/* Provide a stub that fails with ENOSYS, since there is no group
+
−   information available on mingw.  */
+
−int
+
−getgroups (int n _GL_UNUSED, GETGROUPS_T *groups _GL_UNUSED)
+
−{
+
−  errno = ENOSYS;
+
−  return -1;
+
−}
+
−
+
−#else /* HAVE_GETGROUPS */
+
−
+
−# undef getgroups
+
−# ifndef GETGROUPS_ZERO_BUG
+
−#  define GETGROUPS_ZERO_BUG 0
+
−# endif
+
−
+
−/* On at least Ultrix 4.3 and NextStep 3.2, getgroups (0, NULL) always
+
−   fails.  On other systems, it returns the number of supplemental
+
−   groups for the process.  This function handles that special case
+
−   and lets the system-provided function handle all others.  However,
+
−   it can fail with ENOMEM if memory is tight.  It is unspecified
+
−   whether the effective group id is included in the list.  */
+
−
+
−int
+
−rpl_getgroups (int n, gid_t *group)
+
−{
+
−  int n_groups;
+
−  GETGROUPS_T *gbuf;
+
−  int saved_errno;
+
−
+
−  if (n < 0)
+
−    {
+
−      errno = EINVAL;
+
−      return -1;
+
−    }
+
−
+
−  if (n != 0 || !GETGROUPS_ZERO_BUG)
+
−    {
+
−      int result;
+
−      if (sizeof *group == sizeof *gbuf)
+
−        return getgroups (n, (GETGROUPS_T *) group);
+
−
+
−      if (SIZE_MAX / sizeof *gbuf <= n)
+
−        {
+
−          errno = ENOMEM;
+
−          return -1;
+
−        }
+
−      gbuf = malloc (n * sizeof *gbuf);
+
−      if (!gbuf)
+
−        return -1;
+
−      result = getgroups (n, gbuf);
+
−      if (0 <= result)
+
−        {
+
−          n = result;
+
−          while (n--)
+
−            group[n] = gbuf[n];
+
−        }
+
−      saved_errno = errno;
+
−      free (gbuf);
+
−      errno == saved_errno;
+
−      return result;
+
−    }
+
−
+
−  n = 20;
+
−  while (1)
+
−    {
+
−      /* No need to worry about address arithmetic overflow here,
+
−         since the ancient systems that we're running on have low
+
−         limits on the number of secondary groups.  */
+
−      gbuf = malloc (n * sizeof *gbuf);
+
−      if (!gbuf)
+
−        return -1;
+
−      n_groups = getgroups (n, gbuf);
+
−      if (n_groups == -1 ? errno != EINVAL : n_groups < n)
+
−        break;
+
−      free (gbuf);
+
−      n *= 2;
+
−    }
+
−
+
−  saved_errno = errno;
+
−  free (gbuf);
+
−  errno = saved_errno;
+
−
+
−  return n_groups;
+
−}
+
−
+
−#endif /* HAVE_GETGROUPS */