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/* Copyright (C) 1999-2021 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
<https://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));
}
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