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The first field of /proc/uptime relies on the CLOCK_BOOTTIME clock which can also be fetched from clock_gettime() API. Improve the test coverage while verifying the monotonicity of CLOCK_BOOTTIME accross both interfaces. Suggested-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/r/20230222144649.624380-9-frederic@kernel.org
60 lines
1.6 KiB
C
60 lines
1.6 KiB
C
/*
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* Copyright © 2018 Alexey Dobriyan <adobriyan@gmail.com>
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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#undef NDEBUG
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#include <assert.h>
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#include <errno.h>
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#include <string.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <time.h>
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#include "proc.h"
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static uint64_t clock_boottime(void)
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{
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struct timespec ts;
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int err;
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err = clock_gettime(CLOCK_BOOTTIME, &ts);
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assert(err >= 0);
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return (ts.tv_sec * 100) + (ts.tv_nsec / 10000000);
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}
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static uint64_t proc_uptime(int fd)
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{
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uint64_t val1, val2;
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char buf[64], *p;
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ssize_t rv;
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/* save "p < end" checks */
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memset(buf, 0, sizeof(buf));
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rv = pread(fd, buf, sizeof(buf), 0);
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assert(0 <= rv && rv <= sizeof(buf));
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buf[sizeof(buf) - 1] = '\0';
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p = buf;
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val1 = xstrtoull(p, &p);
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assert(p[0] == '.');
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assert('0' <= p[1] && p[1] <= '9');
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assert('0' <= p[2] && p[2] <= '9');
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assert(p[3] == ' ');
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val2 = (p[1] - '0') * 10 + p[2] - '0';
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return val1 * 100 + val2;
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}
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