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/* Copyright (C) 2008-2022 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <errno.h>
#include <sys/times.h>
#include <sysdep.h>
clock_t
__times (struct tms *buf)
{
clock_t ret = INTERNAL_SYSCALL_CALL (times, buf);
if (INTERNAL_SYSCALL_ERROR_P (ret)
&& __glibc_unlikely (INTERNAL_SYSCALL_ERRNO (ret) == EFAULT)
&& buf)
{
/* This might be an error or not. For architectures which have no
separate return value and error indicators we cannot
distinguish a return value of e.g. (clock_t) -14 from -EFAULT.
Therefore the only course of action is to dereference the user
-supplied structure on a return of (clock_t) -14. This will crash
applications which pass in an invalid non-NULL BUF pointer.
Note that Linux allows BUF to be NULL in which case we skip this. */
#define touch(v) \
do { \
clock_t temp = v; \
asm volatile ("" : "+r" (temp)); \
v = temp; \
} while (0)
touch (buf->tms_utime);
touch (buf->tms_stime);
touch (buf->tms_cutime);
touch (buf->tms_cstime);
/* If we come here the memory is valid and the kernel did not
return an EFAULT error, but rather e.g. (clock_t) -14.
Return the value given by the kernel. */
}
/* On Linux this function never fails except with EFAULT.
POSIX says that returning a value (clock_t) -1 indicates an error,
but on Linux this is simply one of the valid clock values after
clock_t wraps. Therefore when we would return (clock_t) -1, we
instead return (clock_t) 0, and loose a tick of accuracy (having
returned 0 for two consecutive calls even though the clock
advanced). */
if (ret == (clock_t) -1)
return (clock_t) 0;
return ret;
}
weak_alias (__times, times)
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