74 lines
1.9 KiB
C
74 lines
1.9 KiB
C
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/* Copyright (C) 1999-2022 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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#include "ifreq.h"
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void
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__ifreq (struct ifreq **ifreqs, int *num_ifs, int sockfd)
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{
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int fd = sockfd;
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struct ifconf ifc;
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int rq_len;
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int nifs;
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# define RQ_IFS 4
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if (fd < 0)
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fd = __opensock ();
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if (fd < 0)
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{
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*num_ifs = 0;
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*ifreqs = NULL;
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return;
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}
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ifc.ifc_buf = NULL;
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/* We may be able to get the needed buffer size directly, rather than
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guessing. */
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ifc.ifc_buf = NULL;
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ifc.ifc_len = 0;
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if (__ioctl (fd, SIOCGIFCONF, &ifc) < 0 || ifc.ifc_len == 0)
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rq_len = RQ_IFS * sizeof (struct ifreq);
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else
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rq_len = ifc.ifc_len;
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/* Read all the interfaces out of the kernel. */
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ifc.ifc_len = rq_len;
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void *newp = realloc (ifc.ifc_buf, ifc.ifc_len);
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if (newp == NULL
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|| (ifc.ifc_buf = newp, __ioctl (fd, SIOCGIFCONF, &ifc)) < 0)
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{
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free (ifc.ifc_buf);
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if (fd != sockfd)
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__close (fd);
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*num_ifs = 0;
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*ifreqs = NULL;
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return;
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}
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nifs = ifc.ifc_len / sizeof (struct ifreq);
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if (fd != sockfd)
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__close (fd);
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*num_ifs = nifs;
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*ifreqs = realloc (ifc.ifc_buf, nifs * sizeof (struct ifreq));
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}
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