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52 lines
1.5 KiB
C
52 lines
1.5 KiB
C
/* Copyright (C) 2000-2017 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, see
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<http://www.gnu.org/licenses/>. */
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#include <errno.h>
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#include <fcntl.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 <not-cancel.h>
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static int itc_usable;
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static int
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has_cpuclock (void)
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{
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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_not_cancel_2 ("/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_not_cancel (fd, buf, sizeof buf) != 2
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|| buf[0] != '0' || buf[1] != '\n')
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newval = -1;
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close_not_cancel_no_status (fd);
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}
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itc_usable = newval;
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}
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return itc_usable;
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}
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