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66 lines
1.8 KiB
C
66 lines
1.8 KiB
C
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/* Copyright (C) 2000, 2001, 2003 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, write to the Free
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Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
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02111-1307 USA. */
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#include <errno.h>
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#include <time.h>
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#include <unistd.h>
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#include <sys/stat.h>
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#include <sys/types.h>
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#include <fcntl.h>
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int
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clock_getcpuclockid (pid_t pid, clockid_t *clock_id)
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{
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/* We don't allow any process ID but our own. */
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if (pid != 0 && pid != getpid ())
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return EPERM;
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static int itc_usable;
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int retval = ENOENT;
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if (__builtin_expect (itc_usable == 0, 0))
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{
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int newval = 1;
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int fd = open ("/proc/sal/itc_drift", O_RDONLY);
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if (__builtin_expect (fd != -1, 1))
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{
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char buf[16];
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/* We expect the file to contain a single digit followed by
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a newline. If the format changes we better not rely on
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the file content. */
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if (read (fd, buf, sizeof buf) != 2 || buf[0] != '0'
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|| buf[1] != '\n')
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newval = -1;
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close (fd);
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}
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itc_usable = newval;
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}
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if (itc_usable > 0)
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{
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/* Store the number. */
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*clock_id = CLOCK_PROCESS_CPUTIME_ID;
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retval = 0;
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}
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return retval;
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}
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