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Member "chrony-3.5/rtc.c" (10 May 2019, 5906 Bytes) of package /linux/misc/chrony-3.5.tar.gz:


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    1 /*
    2   chronyd/chronyc - Programs for keeping computer clocks accurate.
    3 
    4  **********************************************************************
    5  * Copyright (C) Richard P. Curnow  1997-2003
    6  * 
    7  * This program is free software; you can redistribute it and/or modify
    8  * it under the terms of version 2 of the GNU General Public License as
    9  * published by the Free Software Foundation.
   10  * 
   11  * This program is distributed in the hope that it will be useful, but
   12  * WITHOUT ANY WARRANTY; without even the implied warranty of
   13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   14  * General Public License for more details.
   15  * 
   16  * You should have received a copy of the GNU General Public License along
   17  * with this program; if not, write to the Free Software Foundation, Inc.,
   18  * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
   19  * 
   20  **********************************************************************
   21 
   22   =======================================================================
   23 
   24   */
   25 
   26 #include "config.h"
   27 
   28 #include "sysincl.h"
   29 
   30 #include "rtc.h"
   31 #include "local.h"
   32 #include "logging.h"
   33 #include "conf.h"
   34 
   35 #if defined LINUX && defined FEAT_RTC
   36 #include "rtc_linux.h"
   37 #endif /* defined LINUX */
   38 
   39 /* ================================================== */
   40 
   41 static int driver_initialised = 0;
   42 static int driver_preinit_ok = 0;
   43 
   44 static struct {
   45   int  (*init)(void);
   46   void (*fini)(void);
   47   int  (*time_pre_init)(time_t driftfile_time);
   48   void (*time_init)(void (*after_hook)(void*), void *anything);
   49   void (*start_measurements)(void);
   50   int  (*write_parameters)(void);
   51   int  (*get_report)(RPT_RTC_Report *report);
   52   int  (*trim)(void);
   53 } driver =
   54 {
   55 #if defined LINUX && defined FEAT_RTC
   56   RTC_Linux_Initialise,
   57   RTC_Linux_Finalise,
   58   RTC_Linux_TimePreInit,
   59   RTC_Linux_TimeInit,
   60   RTC_Linux_StartMeasurements,
   61   RTC_Linux_WriteParameters,
   62   RTC_Linux_GetReport,
   63   RTC_Linux_Trim
   64 #else
   65   NULL,
   66   NULL,
   67   NULL,
   68   NULL,
   69   NULL,
   70   NULL,
   71   NULL,
   72   NULL
   73 #endif 
   74 };
   75      
   76 /* ================================================== */
   77 /* Get the last modification time of the driftfile */
   78 
   79 static time_t
   80 get_driftfile_time(void)
   81 {
   82   struct stat buf;
   83   char *drift_file;
   84 
   85   drift_file = CNF_GetDriftFile();
   86   if (!drift_file)
   87     return 0;
   88 
   89   if (stat(drift_file, &buf))
   90     return 0;
   91 
   92   return buf.st_mtime;
   93 }
   94 
   95 /* ================================================== */
   96 /* Set the system time to the driftfile time if it's in the future */
   97 
   98 static void
   99 apply_driftfile_time(time_t t)
  100 {
  101   struct timespec now;
  102 
  103   LCL_ReadCookedTime(&now, NULL);
  104 
  105   if (now.tv_sec < t) {
  106     if (LCL_ApplyStepOffset(now.tv_sec - t))
  107       LOG(LOGS_INFO, "System time restored from driftfile");
  108   }
  109 }
  110 
  111 /* ================================================== */
  112 
  113 void
  114 RTC_Initialise(int initial_set)
  115 {
  116   time_t driftfile_time;
  117   char *file_name;
  118 
  119   /* If the -s option was specified, try to do an initial read of the RTC and
  120      set the system time to it.  Also, read the last modification time of the
  121      driftfile (i.e. system time when chronyd was previously stopped) and set
  122      the system time to it if it's in the future to bring the clock closer to
  123      the true time when the RTC is broken (e.g. it has no battery), is missing,
  124      or there is no RTC driver. */
  125   if (initial_set) {
  126     driftfile_time = get_driftfile_time();
  127 
  128     if (driver.time_pre_init && driver.time_pre_init(driftfile_time)) {
  129       driver_preinit_ok = 1;
  130     } else {
  131       driver_preinit_ok = 0;
  132       if (driftfile_time)
  133         apply_driftfile_time(driftfile_time);
  134     }
  135   }
  136 
  137   driver_initialised = 0;
  138 
  139   /* This is how we tell whether the user wants to load the RTC
  140      driver, if he is on a machine where it is an option. */
  141   file_name = CNF_GetRtcFile();
  142 
  143   if (file_name) {
  144     if (CNF_GetRtcSync()) {
  145       LOG_FATAL("rtcfile directive cannot be used with rtcsync");
  146     }
  147 
  148     if (driver.init) {
  149       if ((driver.init)()) {
  150         driver_initialised = 1;
  151       }
  152     } else {
  153       LOG(LOGS_ERR, "RTC not supported on this operating system");
  154     }
  155   }
  156 }
  157 
  158 /* ================================================== */
  159 
  160 void
  161 RTC_Finalise(void)
  162 {
  163   if (driver.fini) {
  164     (driver.fini)();
  165   }
  166 }
  167 
  168 /* ================================================== */
  169 /* Start the processing to get a single measurement from the real time
  170    clock, and use it to trim the system time, based on knowing the
  171    drift rate of the RTC and the error the last time we set it.  If the
  172    TimePreInit routine has succeeded, we can be sure that the trim required
  173    is not *too* large.
  174 
  175    We are called with a hook to a function to be called after the
  176    initialisation is complete.  We also call this if we cannot do the
  177    initialisation. */
  178 
  179 void
  180 RTC_TimeInit(void (*after_hook)(void *), void *anything)
  181 {
  182   if (driver_initialised && driver_preinit_ok) {
  183     (driver.time_init)(after_hook, anything);
  184   } else {
  185     (after_hook)(anything);
  186   }
  187 }
  188 
  189 /* ================================================== */
  190 /* Start the RTC measurement process */
  191 
  192 void
  193 RTC_StartMeasurements(void)
  194 {
  195   if (driver_initialised) {
  196     (driver.start_measurements)();
  197   }
  198   /* Benign if driver not present */
  199 }
  200 
  201 /* ================================================== */
  202 /* Write RTC information out to RTC file.  Return 0 for success, 1 if
  203    RTC driver not running, or 2 if the file cannot be written. */
  204 
  205 int
  206 RTC_WriteParameters(void)
  207 {
  208   if (driver_initialised) {
  209     return (driver.write_parameters)();
  210   } else {
  211     return RTC_ST_NODRV;
  212   }
  213 }
  214 
  215 /* ================================================== */
  216 
  217 int
  218 RTC_GetReport(RPT_RTC_Report *report)
  219 {
  220   if (driver_initialised) {
  221     return (driver.get_report)(report);
  222   } else {
  223     return 0;
  224   }
  225 }
  226 
  227 /* ================================================== */
  228 
  229 int
  230 RTC_Trim(void)
  231 {
  232   if (driver_initialised) {
  233     return (driver.trim)();
  234   } else {
  235     return 0;
  236   }
  237 }
  238 
  239 /* ================================================== */
  240