sunrpc/create_xid.c

   1 /* Copyright (c) 1998 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Thorsten Kukuk <kukuk@vt.uni-paderborn.de>, 1998.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Library General Public License as
   7    published by the Free Software Foundation; either version 2 of the
   8    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    Library General Public License for more details.
  14
  15    You should have received a copy of the GNU Library General Public
  16    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  17    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  18    Boston, MA 02111-1307, USA. */
  19
  20 #include <unistd.h>
  21 #include <stdlib.h>
  22 #include <sys/time.h>
  23 #include <bits/libc-lock.h>
  24
  25 /* The RPC code is not threadsafe, but new code should be threadsafe. */
  26
  27 __libc_lock_define_initialized (static, createxid_lock)
  28
  29 static int is_initialized;
  30 static struct drand48_data __rpc_lrand48_data;
  31
  32 unsigned long
  33 _create_xid (void)
  34 {
  35   unsigned long res;
  36
  37   __libc_lock_lock (createxid_lock);
  38
  39   if (!is_initialized)
  40     {
  41       struct timeval now;
  42
  43       __gettimeofday (&now, (struct timezone *) 0);
  44       srand48_r (now.tv_sec ^ now.tv_usec, &__rpc_lrand48_data);
  45       is_initialized = 1;
  46     }
  47
  48   lrand48_r (&__rpc_lrand48_data, &res);
  49
  50   __libc_lock_unlock (createxid_lock);
  51
  52   return res;
  53 }