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/* Copyright (C) 2000, 2001, 2003 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, write to the Free
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA. */
#include <errno.h>
#include <time.h>
#include <unistd.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <fcntl.h>
int
clock_getcpuclockid (pid_t pid, clockid_t *clock_id)
{
/* We don't allow any process ID but our own. */
if (pid != 0 && pid != getpid ())
return EPERM;
static int itc_usable;
int retval = ENOENT;
if (__builtin_expect (itc_usable == 0, 0))
{
int newval = 1;
int fd = open ("/proc/sal/itc_drift", O_RDONLY);
if (__builtin_expect (fd != -1, 1))
{
char buf[16];
/* We expect the file to contain a single digit followed by
a newline. If the format changes we better not rely on
the file content. */
if (read (fd, buf, sizeof buf) != 2 || buf[0] != '0'
|| buf[1] != '\n')
newval = -1;
close (fd);
}
itc_usable = newval;
}
if (itc_usable > 0)
{
/* Store the number. */
*clock_id = CLOCK_PROCESS_CPUTIME_ID;
retval = 0;
}
return retval;
}
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