sysdeps/generic/ifreq.h

   1 /* Copyright (C) 1999,2002 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Andreas Jaeger <aj@suse.de>.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 #include <stdio.h>
  21 #include <stdlib.h>
  22 #include <unistd.h>
  23 #include <net/if.h>
  24 #include <sys/socket.h>
  25 #include <sys/ioctl.h>
  26
  27
  28 static inline void
  29 __ifreq (struct ifreq **ifreqs, int *num_ifs, int sockfd)
  30 {
  31   int fd = sockfd;
  32   struct ifconf ifc;
  33   int rq_len;
  34   int nifs;
  35 # define RQ_IFS 4
  36
  37   if (fd < 0)
  38     fd = __opensock ();
  39   if (fd < 0)
  40     {
  41       *num_ifs = 0;
  42       *ifreqs = NULL;
  43       return;
  44     }
  45
  46   ifc.ifc_buf = NULL;
  47   rq_len = RQ_IFS * sizeof (struct ifreq);
  48   do
  49     {
  50       ifc.ifc_len = rq_len;
  51       ifc.ifc_buf = realloc (ifc.ifc_buf, ifc.ifc_len);
  52       if (ifc.ifc_buf == NULL || __ioctl (fd, SIOCGIFCONF, &ifc) < 0)
  53         {
  54           if (ifc.ifc_buf)
  55             free (ifc.ifc_buf);
  56
  57           if (fd != sockfd)
  58             __close (fd);
  59           *num_ifs = 0;
  60           *ifreqs = NULL;
  61           return;
  62         }
  63       rq_len *= 2;
  64     }
  65   while (rq_len < sizeof (struct ifreq) + ifc.ifc_len);
  66
  67   nifs = ifc.ifc_len / sizeof (struct ifreq);
  68
  69   if (fd != sockfd)
  70     __close (fd);
  71
  72   *num_ifs = nifs;
  73   *ifreqs = realloc (ifc.ifc_buf, nifs * sizeof (struct ifreq));
  74 }
  75
  76
  77 static inline void
  78 __if_freereq (struct ifreq *ifreqs, int num_ifs)
  79 {
  80   free (ifreqs);
  81 }