sunrpc/create_xid.c

   1 /* Copyright (c) 1998-2021 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, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #include <unistd.h>
  20 #include <stdlib.h>
  21 #include <sys/time.h>
  22 #include <libc-lock.h>
  23 #include <rpc/rpc.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 pid_t is_initialized;
  30 static struct drand48_data __rpc_lrand48_data;
  31
  32 unsigned long
  33 _create_xid (void)
  34 {
  35   long int res;
  36
  37   __libc_lock_lock (createxid_lock);
  38
  39   pid_t pid = getpid ();
  40   if (is_initialized != pid)
  41     {
  42       struct timespec now;
  43
  44       __clock_gettime (CLOCK_REALTIME, &now);
  45       __srand48_r (now.tv_sec ^ now.tv_nsec ^ pid,
  46                    &__rpc_lrand48_data);
  47       is_initialized = pid;
  48     }
  49
  50   lrand48_r (&__rpc_lrand48_data, &res);
  51
  52   __libc_lock_unlock (createxid_lock);
  53
  54   return res;
  55 }