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  }