sunrpc/create_xid.c

   1 /* Copyright (c) 1998-2023 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, see
  16    <https://www.gnu.org/licenses/>.  */
  17
  18 #include <unistd.h>
  19 #include <stdlib.h>
  20 #include <sys/time.h>
  21 #include <libc-lock.h>
  22 #include <rpc/rpc.h>
  23
  24 /* The RPC code is not threadsafe, but new code should be threadsafe. */
  25
  26 __libc_lock_define_initialized (static, createxid_lock)
  27
  28 static pid_t is_initialized;
  29 static struct drand48_data __rpc_lrand48_data;
  30
  31 unsigned long
  32 _create_xid (void)
  33 {
  34   long int res;
  35
  36   __libc_lock_lock (createxid_lock);
  37
  38   pid_t pid = getpid ();
  39   if (is_initialized != pid)
  40     {
  41       struct timespec now;
  42
  43       __clock_gettime (CLOCK_REALTIME, &now);
  44       __srand48_r (now.tv_sec ^ now.tv_nsec ^ pid,
  45                    &__rpc_lrand48_data);
  46       is_initialized = pid;
  47     }
  48
  49   lrand48_r (&__rpc_lrand48_data, &res);
  50
  51   __libc_lock_unlock (createxid_lock);
  52
  53   return res;
  54 }