create_xid.c

   1 /* Copyright (c) 1998, 2000 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 #define __FORCE_GLIBC
  21 #include <features.h>
  22
  23 #include <unistd.h>
  24 #include <stdlib.h>
  25 #include <sys/time.h>
  26 #include <rpc/rpc.h>
  27
  28
  29 /* The RPC code is not threadsafe, but new code should be threadsafe. */
  30
  31 __UCLIBC_MUTEX_STATIC(mylock, PTHREAD_MUTEX_INITIALIZER);
  32
  33 static smallint is_initialized;
  34 static struct drand48_data __rpc_lrand48_data;
  35
  36 u_long _create_xid (void) attribute_hidden;
  37 u_long _create_xid (void)
  38 {
  39   long res;
  40
  41   __UCLIBC_MUTEX_LOCK(mylock);
  42
  43   if (!is_initialized)
  44     {
  45       struct timeval now;
  46
  47       gettimeofday (&now, (struct timezone *) 0);
  48       srand48_r (now.tv_sec ^ now.tv_usec, &__rpc_lrand48_data);
  49       is_initialized = 1;
  50     }
  51
  52   lrand48_r (&__rpc_lrand48_data, &res);
  53
  54   __UCLIBC_MUTEX_UNLOCK(mylock);
  55
  56   return res;
  57 }