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glibc  2.9
create_xid.c
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00001 /* Copyright (c) 1998, 2000 Free Software Foundation, Inc.
00002    This file is part of the GNU C Library.
00003    Contributed by Thorsten Kukuk <kukuk@vt.uni-paderborn.de>, 1998.
00004 
00005    The GNU C Library is free software; you can redistribute it and/or
00006    modify it under the terms of the GNU Lesser General Public
00007    License as published by the Free Software Foundation; either
00008    version 2.1 of the License, or (at your option) any later version.
00009 
00010    The GNU C Library is distributed in the hope that it will be useful,
00011    but WITHOUT ANY WARRANTY; without even the implied warranty of
00012    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00013    Lesser General Public License for more details.
00014 
00015    You should have received a copy of the GNU Lesser General Public
00016    License along with the GNU C Library; if not, write to the Free
00017    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
00018    02111-1307 USA.  */
00019 
00020 #include <unistd.h>
00021 #include <stdlib.h>
00022 #include <sys/time.h>
00023 #include <bits/libc-lock.h>
00024 #include <rpc/rpc.h>
00025 
00026 /* The RPC code is not threadsafe, but new code should be threadsafe. */
00027 
00028 __libc_lock_define_initialized (static, createxid_lock)
00029 
00030 static int is_initialized;
00031 static struct drand48_data __rpc_lrand48_data;
00032 
00033 unsigned long
00034 _create_xid (void)
00035 {
00036   long int res;
00037 
00038   __libc_lock_lock (createxid_lock);
00039 
00040   if (!is_initialized)
00041     {
00042       struct timeval now;
00043 
00044       __gettimeofday (&now, (struct timezone *) 0);
00045       __srand48_r (now.tv_sec ^ now.tv_usec, &__rpc_lrand48_data);
00046       is_initialized = 1;
00047     }
00048 
00049   lrand48_r (&__rpc_lrand48_data, &res);
00050 
00051   __libc_lock_unlock (createxid_lock);
00052 
00053   return res;
00054 }