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glibc  2.9
times.c
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00001 /* Copyright (C) 2008 Free Software Foundation, Inc.
00002    This file is part of the GNU C Library.
00003 
00004    The GNU C Library is free software; you can redistribute it and/or
00005    modify it under the terms of the GNU Lesser General Public
00006    License as published by the Free Software Foundation; either
00007    version 2.1 of the License, or (at your option) any later version.
00008 
00009    The GNU C Library is distributed in the hope that it will be useful,
00010    but WITHOUT ANY WARRANTY; without even the implied warranty of
00011    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00012    Lesser General Public License for more details.
00013 
00014    You should have received a copy of the GNU Lesser General Public
00015    License along with the GNU C Library; if not, write to the Free
00016    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
00017    02111-1307 USA.  */
00018 
00019 #include <errno.h>
00020 #include <sys/times.h>
00021 #include <sysdep.h>
00022 
00023 
00024 clock_t
00025 __times (struct tms *buf)
00026 {
00027   INTERNAL_SYSCALL_DECL (err);
00028   clock_t ret = INTERNAL_SYSCALL (times, err, 1, buf);
00029   if (INTERNAL_SYSCALL_ERROR_P (ret, err)
00030       && __builtin_expect (INTERNAL_SYSCALL_ERRNO (ret, err) == EFAULT, 0))
00031     {
00032       /* This might be an error or not.  For architectures which have
00033         no separate return value and error indicators we cannot
00034         distinguish a return value of -1 from an error.  Do it the
00035         hard way.  We crash applications which pass in an invalid BUF
00036         pointer.  */
00037 #define touch(v) \
00038       do {                                                           \
00039        clock_t temp = v;                                             \
00040        asm volatile ("" : "+r" (temp));                              \
00041        v = temp;                                                     \
00042       } while (0)
00043       touch (buf->tms_utime);
00044       touch (buf->tms_stime);
00045       touch (buf->tms_cutime);
00046       touch (buf->tms_cstime);
00047 
00048       /* If we come here the memory is valid and the kernel did not
00049         return an EFAULT error.  Return the value given by the kernel.  */
00050     }
00051 
00052   /* Return value (clock_t) -1 signals an error, but if there wasn't any,
00053      return the following value.  */
00054   if (ret == (clock_t) -1)
00055     return (clock_t) 0;
00056 
00057   return ret;
00058 }
00059 weak_alias (__times, times)