/* Copyright (C) 1999-2018 Free Software Foundation, Inc.

   This file is part of the GNU C Library.

   Contributed by Andreas Jaeger <aj@suse.de>.

   The GNU C Library is free software; you can redistribute it and/or

   modify it under the terms of the GNU Lesser General Public

   License as published by the Free Software Foundation; either

   version 2.1 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

   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public

   License along with the GNU C Library; if not, see

   <http://www.gnu.org/licenses/>.  */

#include "ifreq.h"

void

__ifreq (struct ifreq **ifreqs, int *num_ifs, int sockfd)

{

  int fd = sockfd;

  struct ifconf ifc;

  int rq_len;

  int nifs;

# define RQ_IFS	4

  if (fd < 0)

    fd = __opensock ();

  if (fd < 0)

    {

      *num_ifs = 0;

      *ifreqs = NULL;

      return;

    }

  ifc.ifc_buf = NULL;

  /* We may be able to get the needed buffer size directly, rather than

     guessing.  */

  ifc.ifc_buf = NULL;

  ifc.ifc_len = 0;

  if (__ioctl (fd, SIOCGIFCONF, &ifc) < 0 || ifc.ifc_len == 0)

    rq_len = RQ_IFS * sizeof (struct ifreq);

  else

    rq_len = ifc.ifc_len;

  /* Read all the interfaces out of the kernel.  */

  ifc.ifc_len = rq_len;

  void *newp = realloc (ifc.ifc_buf, ifc.ifc_len);

  if (newp == NULL

      || (ifc.ifc_buf = newp, __ioctl (fd, SIOCGIFCONF, &ifc)) < 0)

    {

      free (ifc.ifc_buf);

      if (fd != sockfd)

	__close (fd);

      *num_ifs = 0;

      *ifreqs = NULL;

      return;

    }

  nifs = ifc.ifc_len / sizeof (struct ifreq);

  if (fd != sockfd)

    __close (fd);

  *num_ifs = nifs;

  *ifreqs = realloc (ifc.ifc_buf, nifs * sizeof (struct ifreq));

}