rtc.c

   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_initialised) {
 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