sunrpc/create_xid.c

   1 /* Copyright (c) 1998, 2000, 2009 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 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 <unistd.h>
  21 #include <stdlib.h>
  22 #include <sys/time.h>
  23 #include <bits/libc-lock.h>
  24 #include <rpc/rpc.h>
  25
  26 /* The RPC code is not threadsafe, but new code should be threadsafe. */
  27
  28 __libc_lock_define_initialized (static, createxid_lock)
  29
  30 static pid_t is_initialized;
  31 static struct drand48_data __rpc_lrand48_data;
  32
  33 unsigned long
  34 _create_xid (void)
  35 {
  36   long int res;
  37
  38   __libc_lock_lock (createxid_lock);
  39
  40   pid_t pid = getpid ();
  41   if (is_initialized != pid)
  42     {
  43       struct timeval now;
  44
  45       __gettimeofday (&now, (struct timezone *) 0);
  46       __srand48_r (now.tv_sec ^ now.tv_usec ^ pid,
  47                    &__rpc_lrand48_data);
  48       is_initialized = pid;
  49     }
  50
  51   lrand48_r (&__rpc_lrand48_data, &res);
  52
  53   __libc_lock_unlock (createxid_lock);
  54
  55   return res;
  56 }