socket/opensock.c

   1 /* Copyright (C) 1999 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, write to the Free
  16    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  17    02111-1307 USA.  */
  18
  19 #include <stdio.h>
  20 #include <sys/socket.h>
  21 #include <bits/libc-lock.h>
  22
  23 /* Return a socket of any type.  The socket can be used in subsequent
  24    ioctl calls to talk to the kernel.  */
  25 int internal_function
  26 __opensock (void)
  27 {
  28   /* Cache the last AF that worked, to avoid many redundant calls to
  29      socket().  */
  30   static int sock_af = -1;
  31   int fd = -1;
  32   __libc_lock_define_initialized (static, lock);
  33
  34   if (sock_af != -1)
  35     {
  36       fd = __socket (sock_af, SOCK_DGRAM, 0);
  37       if (fd != -1)
  38         return fd;
  39     }
  40
  41   __libc_lock_lock (lock);
  42
  43   if (sock_af != -1)
  44     fd = __socket (sock_af, SOCK_DGRAM, 0);
  45
  46   if (fd == -1)
  47     {
  48 #ifdef AF_INET
  49       fd = __socket (sock_af = AF_INET, SOCK_DGRAM, 0);
  50 #endif
  51 #ifdef AF_INET6
  52       if (fd < 0)
  53         fd = __socket (sock_af = AF_INET6, SOCK_DGRAM, 0);
  54 #endif
  55 #ifdef AF_IPX
  56       if (fd < 0)
  57         fd = __socket (sock_af = AF_IPX, SOCK_DGRAM, 0);
  58 #endif
  59 #ifdef AF_AX25
  60       if (fd < 0)
  61         fd = __socket (sock_af = AF_AX25, SOCK_DGRAM, 0);
  62 #endif
  63 #ifdef AF_APPLETALK
  64       if (fd < 0)
  65         fd = __socket (sock_af = AF_APPLETALK, SOCK_DGRAM, 0);
  66 #endif
  67     }
  68
  69   __libc_lock_unlock (lock);
  70   return fd;
  71 }