c44346096c
Add a new clock driver that doesn't actually try to adjust the clock. It allows chronyd to run without the capability to adjust/set the system clock, e.g. in some containers. It can be enabled by the -x option.
140 lines
3.2 KiB
C
140 lines
3.2 KiB
C
/*
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chronyd/chronyc - Programs for keeping computer clocks accurate.
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**********************************************************************
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* Copyright (C) Miroslav Lichvar 2017
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of version 2 of the GNU General Public License as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful, but
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* 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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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*
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**********************************************************************
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=======================================================================
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Null clock driver for operation with no clock control.
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*/
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#include "config.h"
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#include "sysincl.h"
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#include "sys_null.h"
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#include "local.h"
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#include "localp.h"
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#include "logging.h"
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#include "util.h"
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/* Current frequency offset of the system clock (in ppm) */
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static double freq;
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/* Offset of the system clock at the last update */
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static double offset_register;
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/* Time of the last update */
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static struct timespec last_update;
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/* Minimum interval between updates when frequency is constant */
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#define MIN_UPDATE_INTERVAL 1000.0
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/* ================================================== */
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static void
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update_offset(void)
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{
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struct timespec now;
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double duration;
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LCL_ReadRawTime(&now);
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duration = UTI_DiffTimespecsToDouble(&now, &last_update);
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offset_register += 1.0e-6 * freq * duration;
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last_update = now;
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DEBUG_LOG("System clock offset=%e freq=%f", offset_register, freq);
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}
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/* ================================================== */
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static double
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read_frequency(void)
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{
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return freq;
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}
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/* ================================================== */
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static double
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set_frequency(double freq_ppm)
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{
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update_offset();
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freq = freq_ppm;
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return freq;
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}
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/* ================================================== */
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static void
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accrue_offset(double offset, double corr_rate)
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{
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offset_register += offset;
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}
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/* ================================================== */
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static int
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apply_step_offset(double offset)
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{
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return 0;
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}
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/* ================================================== */
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static void
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offset_convert(struct timespec *raw, double *corr, double *err)
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{
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double duration;
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duration = UTI_DiffTimespecsToDouble(raw, &last_update);
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if (duration > MIN_UPDATE_INTERVAL) {
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update_offset();
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duration = 0.0;
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}
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*corr = -1.0e-6 * freq * duration - offset_register;
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if (err)
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*err = 0.0;
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}
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/* ================================================== */
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void
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SYS_Null_Initialise(void)
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{
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offset_register = 0.0;
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LCL_ReadRawTime(&last_update);
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lcl_RegisterSystemDrivers(read_frequency, set_frequency, accrue_offset,
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apply_step_offset, offset_convert, NULL, NULL);
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LOG(LOGS_INFO, "Disabled control of system clock");
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}
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/* ================================================== */
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void
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SYS_Null_Finalise(void)
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{
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}
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