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Commit | Line | Data |
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7eda085c KZ |
1 | /* |
2 | * hwclock.c | |
3 | * | |
4 | * clock.c was written by Charles Hedrick, hedrick@cs.rutgers.edu, Apr 1992 | |
5 | * Modified for clock adjustments - Rob Hooft <hooft@chem.ruu.nl>, Nov 1992 | |
6 | * Improvements by Harald Koenig <koenig@nova.tat.physik.uni-tuebingen.de> | |
7 | * and Alan Modra <alan@spri.levels.unisa.edu.au>. | |
8 | * | |
9 | * Major rewrite by Bryan Henderson <bryanh@giraffe-data.com>, 96.09.19. | |
10 | * The new program is called hwclock. New features: | |
ef71b8f1 SK |
11 | * |
12 | * - You can set the hardware clock without also modifying the system | |
13 | * clock. | |
14 | * - You can read and set the clock with finer than 1 second precision. | |
15 | * - When you set the clock, hwclock automatically refigures the drift | |
16 | * rate, based on how far off the clock was before you set it. | |
7eda085c KZ |
17 | * |
18 | * Reshuffled things, added sparc code, and re-added alpha stuff | |
19 | * by David Mosberger <davidm@azstarnet.com> | |
9abb2685 | 20 | * and Jay Estabrook <jestabro@amt.tay1.dec.com> |
7eda085c KZ |
21 | * and Martin Ostermann <ost@coments.rwth-aachen.de>, aeb@cwi.nl, 990212. |
22 | * | |
ef71b8f1 | 23 | * Fix for Award 2094 bug, Dave Coffin (dcoffin@shore.net) 11/12/98 |
22853e4a | 24 | * Change of local time handling, Stefan Ring <e9725446@stud3.tuwien.ac.at> |
63cccae4 | 25 | * Change of adjtime handling, James P. Rutledge <ao112@rgfn.epcc.edu>. |
66ee8158 KZ |
26 | * |
27 | * Distributed under GPL | |
7eda085c | 28 | */ |
7eda085c KZ |
29 | /* |
30 | * Explanation of `adjusting' (Rob Hooft): | |
31 | * | |
32 | * The problem with my machine is that its CMOS clock is 10 seconds | |
33 | * per day slow. With this version of clock.c, and my '/etc/rc.local' | |
34 | * reading '/etc/clock -au' instead of '/etc/clock -u -s', this error | |
35 | * is automatically corrected at every boot. | |
36 | * | |
37 | * To do this job, the program reads and writes the file '/etc/adjtime' | |
38 | * to determine the correction, and to save its data. In this file are | |
39 | * three numbers: | |
40 | * | |
ef71b8f1 SK |
41 | * 1) the correction in seconds per day. (So if your clock runs 5 |
42 | * seconds per day fast, the first number should read -5.0) | |
43 | * 2) the number of seconds since 1/1/1970 the last time the program | |
44 | * was used | |
45 | * 3) the remaining part of a second which was leftover after the last | |
46 | * adjustment | |
7eda085c KZ |
47 | * |
48 | * Installation and use of this program: | |
49 | * | |
ef71b8f1 SK |
50 | * a) create a file '/etc/adjtime' containing as the first and only |
51 | * line: '0.0 0 0.0' | |
52 | * b) run 'clock -au' or 'clock -a', depending on whether your cmos is | |
53 | * in universal or local time. This updates the second number. | |
54 | * c) set your system time using the 'date' command. | |
55 | * d) update your cmos time using 'clock -wu' or 'clock -w' | |
56 | * e) replace the first number in /etc/adjtime by your correction. | |
57 | * f) put the command 'clock -au' or 'clock -a' in your '/etc/rc.local' | |
7eda085c KZ |
58 | */ |
59 | ||
7eda085c | 60 | #include <errno.h> |
63cccae4 | 61 | #include <getopt.h> |
33ed2d02 | 62 | #include <limits.h> |
83aa4ad7 | 63 | #include <math.h> |
998f392a SK |
64 | #include <stdarg.h> |
65 | #include <stdio.h> | |
66 | #include <stdlib.h> | |
67 | #include <string.h> | |
63cccae4 | 68 | #include <sysexits.h> |
998f392a SK |
69 | #include <sys/stat.h> |
70 | #include <sys/time.h> | |
71 | #include <time.h> | |
72 | #include <unistd.h> | |
7eda085c | 73 | |
e1f4706d SK |
74 | #define OPTUTILS_EXIT_CODE EX_USAGE |
75 | ||
998f392a | 76 | #include "c.h" |
db116df7 | 77 | #include "closestream.h" |
7eda085c | 78 | #include "nls.h" |
e1f4706d | 79 | #include "optutils.h" |
9d413ecb | 80 | #include "pathnames.h" |
4ac41d61 | 81 | #include "strutils.h" |
c7f75390 | 82 | #include "hwclock.h" |
7c678f81 | 83 | #include "timeutils.h" |
984a6096 | 84 | #include "env.h" |
4aca5fe2 | 85 | #include "xalloc.h" |
7eda085c | 86 | |
88058a71 KZ |
87 | #ifdef HAVE_LIBAUDIT |
88 | #include <libaudit.h> | |
89 | static int hwaudit_fd = -1; | |
88058a71 KZ |
90 | #endif |
91 | ||
7eda085c KZ |
92 | /* The struct that holds our hardware access routines */ |
93 | struct clock_ops *ur; | |
94 | ||
f196fd1a SB |
95 | /* Maximal clock adjustment in seconds per day. |
96 | (adjtime() glibc call has 2145 seconds limit on i386, so it is good enough for us as well, | |
97 | 43219 is a maximal safe value preventing exact_adjustment overflow.) */ | |
98 | #define MAX_DRIFT 2145.0 | |
99 | ||
7eda085c | 100 | struct adjtime { |
ef71b8f1 SK |
101 | /* |
102 | * This is information we keep in the adjtime file that tells us how | |
103 | * to do drift corrections. Elements are all straight from the | |
104 | * adjtime file, so see documentation of that file for details. | |
105 | * Exception is <dirty>, which is an indication that what's in this | |
106 | * structure is not what's in the disk file (because it has been | |
107 | * updated since read from the disk file). | |
108 | */ | |
109 | bool dirty; | |
110 | /* line 1 */ | |
111 | double drift_factor; | |
112 | time_t last_adj_time; | |
113 | double not_adjusted; | |
114 | /* line 2 */ | |
115 | time_t last_calib_time; | |
116 | /* | |
117 | * The most recent time that we set the clock from an external | |
118 | * authority (as opposed to just doing a drift adjustment) | |
119 | */ | |
120 | /* line 3 */ | |
a8775f4e | 121 | enum a_local_utc { UTC = 0, LOCAL, UNKNOWN } local_utc; |
ef71b8f1 SK |
122 | /* |
123 | * To which time zone, local or UTC, we most recently set the | |
124 | * hardware clock. | |
125 | */ | |
7eda085c KZ |
126 | }; |
127 | ||
7eda085c | 128 | /* |
ef71b8f1 SK |
129 | * Almost all Award BIOS's made between 04/26/94 and 05/31/95 have a nasty |
130 | * bug limiting the RTC year byte to the range 94-99. Any year between 2000 | |
131 | * and 2093 gets changed to 2094, every time you start the system. | |
132 | * | |
133 | * With the --badyear option, we write the date to file and hope that the | |
134 | * file is updated at least once a year. I recommend putting this command | |
135 | * "hwclock --badyear" in the monthly crontab, just to be safe. | |
136 | * | |
137 | * -- Dave Coffin 11/12/98 | |
7eda085c | 138 | */ |
ef71b8f1 SK |
139 | static void write_date_to_file(struct tm *tm) |
140 | { | |
141 | FILE *fp; | |
142 | ||
9d413ecb | 143 | if ((fp = fopen(_PATH_LASTDATE, "w"))) { |
ef71b8f1 SK |
144 | fprintf(fp, "%02d.%02d.%04d\n", tm->tm_mday, tm->tm_mon + 1, |
145 | tm->tm_year + 1900); | |
db116df7 SK |
146 | if (close_stream(fp) != 0) |
147 | warn(_("cannot write %s"), _PATH_LASTDATE); | |
ef71b8f1 | 148 | } else |
9d413ecb | 149 | warn(_("cannot write %s"), _PATH_LASTDATE); |
7eda085c KZ |
150 | } |
151 | ||
ef71b8f1 SK |
152 | static void read_date_from_file(struct tm *tm) |
153 | { | |
154 | int last_mday, last_mon, last_year; | |
155 | FILE *fp; | |
156 | ||
9d413ecb | 157 | if ((fp = fopen(_PATH_LASTDATE, "r"))) { |
ef71b8f1 SK |
158 | if (fscanf(fp, "%d.%d.%d\n", &last_mday, &last_mon, &last_year) |
159 | == 3) { | |
160 | tm->tm_year = last_year - 1900; | |
161 | if ((tm->tm_mon << 5) + tm->tm_mday < | |
162 | ((last_mon - 1) << 5) + last_mday) | |
163 | tm->tm_year++; | |
164 | } | |
165 | fclose(fp); | |
166 | } | |
167 | write_date_to_file(tm); | |
7eda085c KZ |
168 | } |
169 | ||
2794995a WP |
170 | /* |
171 | * time_t to timeval conversion. | |
172 | */ | |
173 | static struct timeval t2tv(time_t timet) | |
174 | { | |
175 | struct timeval rettimeval; | |
176 | ||
177 | rettimeval.tv_sec = timet; | |
178 | rettimeval.tv_usec = 0; | |
179 | return rettimeval; | |
180 | } | |
181 | ||
ef71b8f1 SK |
182 | /* |
183 | * The difference in seconds between two times in "timeval" format. | |
184 | */ | |
185 | double time_diff(struct timeval subtrahend, struct timeval subtractor) | |
186 | { | |
187 | return (subtrahend.tv_sec - subtractor.tv_sec) | |
188 | + (subtrahend.tv_usec - subtractor.tv_usec) / 1E6; | |
7eda085c KZ |
189 | } |
190 | ||
ef71b8f1 SK |
191 | /* |
192 | * The time, in "timeval" format, which is <increment> seconds after the | |
193 | * time <addend>. Of course, <increment> may be negative. | |
194 | */ | |
195 | static struct timeval time_inc(struct timeval addend, double increment) | |
196 | { | |
197 | struct timeval newtime; | |
198 | ||
199 | newtime.tv_sec = addend.tv_sec + (int)increment; | |
200 | newtime.tv_usec = addend.tv_usec + (increment - (int)increment) * 1E6; | |
201 | ||
202 | /* | |
203 | * Now adjust it so that the microsecond value is between 0 and 1 | |
204 | * million. | |
205 | */ | |
206 | if (newtime.tv_usec < 0) { | |
207 | newtime.tv_usec += 1E6; | |
208 | newtime.tv_sec -= 1; | |
209 | } else if (newtime.tv_usec >= 1E6) { | |
210 | newtime.tv_usec -= 1E6; | |
211 | newtime.tv_sec += 1; | |
212 | } | |
213 | return newtime; | |
7eda085c KZ |
214 | } |
215 | ||
eb63b9b8 | 216 | static bool |
336f7c5f | 217 | hw_clock_is_utc(const struct hwclock_control *ctl, |
ef71b8f1 SK |
218 | const struct adjtime adjtime) |
219 | { | |
eb63b9b8 KZ |
220 | bool ret; |
221 | ||
336f7c5f | 222 | if (ctl->utc) |
eb63b9b8 | 223 | ret = TRUE; /* --utc explicitly given on command line */ |
336f7c5f | 224 | else if (ctl->local_opt) |
eb63b9b8 KZ |
225 | ret = FALSE; /* --localtime explicitly given */ |
226 | else | |
ef71b8f1 | 227 | /* get info from adjtime file - default is UTC */ |
7894bf0f | 228 | ret = (adjtime.local_utc != LOCAL); |
336f7c5f | 229 | if (ctl->debug) |
eb63b9b8 KZ |
230 | printf(_("Assuming hardware clock is kept in %s time.\n"), |
231 | ret ? _("UTC") : _("local")); | |
232 | return ret; | |
233 | } | |
234 | ||
ef71b8f1 SK |
235 | /* |
236 | * Read the adjustment parameters out of the /etc/adjtime file. | |
237 | * | |
238 | * Return them as the adjtime structure <*adjtime_p>. If there is no | |
239 | * /etc/adjtime file, return defaults. If values are missing from the file, | |
240 | * return defaults for them. | |
241 | * | |
242 | * return value 0 if all OK, !=0 otherwise. | |
243 | */ | |
336f7c5f SK |
244 | static int read_adjtime(const struct hwclock_control *ctl, |
245 | struct adjtime *adjtime_p) | |
ef71b8f1 SK |
246 | { |
247 | FILE *adjfile; | |
ef71b8f1 SK |
248 | char line1[81]; /* String: first line of adjtime file */ |
249 | char line2[81]; /* String: second line of adjtime file */ | |
250 | char line3[81]; /* String: third line of adjtime file */ | |
ef71b8f1 | 251 | |
a8775f4e | 252 | if (access(ctl->adj_file_name, R_OK) != 0) |
ef71b8f1 | 253 | return 0; |
eb63b9b8 | 254 | |
336f7c5f | 255 | adjfile = fopen(ctl->adj_file_name, "r"); /* open file for reading */ |
ef71b8f1 | 256 | if (adjfile == NULL) { |
336f7c5f | 257 | warn(_("cannot open %s"), ctl->adj_file_name); |
ef71b8f1 | 258 | return EX_OSFILE; |
eb63b9b8 | 259 | } |
7eda085c | 260 | |
ef71b8f1 SK |
261 | if (!fgets(line1, sizeof(line1), adjfile)) |
262 | line1[0] = '\0'; /* In case fgets fails */ | |
263 | if (!fgets(line2, sizeof(line2), adjfile)) | |
264 | line2[0] = '\0'; /* In case fgets fails */ | |
265 | if (!fgets(line3, sizeof(line3), adjfile)) | |
266 | line3[0] = '\0'; /* In case fgets fails */ | |
267 | ||
268 | fclose(adjfile); | |
269 | ||
ef71b8f1 SK |
270 | sscanf(line1, "%lf %ld %lf", |
271 | &adjtime_p->drift_factor, | |
a8775f4e SK |
272 | &adjtime_p->last_adj_time, |
273 | &adjtime_p->not_adjusted); | |
ef71b8f1 | 274 | |
a8775f4e | 275 | sscanf(line2, "%ld", &adjtime_p->last_calib_time); |
ef71b8f1 SK |
276 | |
277 | if (!strcmp(line3, "UTC\n")) { | |
278 | adjtime_p->local_utc = UTC; | |
279 | } else if (!strcmp(line3, "LOCAL\n")) { | |
280 | adjtime_p->local_utc = LOCAL; | |
281 | } else { | |
282 | adjtime_p->local_utc = UNKNOWN; | |
283 | if (line3[0]) { | |
111c05d3 SK |
284 | warnx(_("Warning: unrecognized third line in adjtime file\n" |
285 | "(Expected: `UTC' or `LOCAL' or nothing.)")); | |
ef71b8f1 SK |
286 | } |
287 | } | |
7eda085c | 288 | |
336f7c5f | 289 | if (ctl->debug) { |
ef71b8f1 SK |
290 | printf(_ |
291 | ("Last drift adjustment done at %ld seconds after 1969\n"), | |
292 | (long)adjtime_p->last_adj_time); | |
293 | printf(_("Last calibration done at %ld seconds after 1969\n"), | |
294 | (long)adjtime_p->last_calib_time); | |
295 | printf(_("Hardware clock is on %s time\n"), | |
296 | (adjtime_p->local_utc == | |
297 | LOCAL) ? _("local") : (adjtime_p->local_utc == | |
298 | UTC) ? _("UTC") : _("unknown")); | |
299 | } | |
300 | ||
301 | return 0; | |
302 | } | |
7eda085c | 303 | |
ef71b8f1 SK |
304 | /* |
305 | * Wait until the falling edge of the Hardware Clock's update flag so that | |
306 | * any time that is read from the clock immediately after we return will be | |
307 | * exact. | |
308 | * | |
309 | * The clock only has 1 second precision, so it gives the exact time only | |
310 | * once per second, right on the falling edge of the update flag. | |
311 | * | |
312 | * We wait (up to one second) either blocked waiting for an rtc device or in | |
313 | * a CPU spin loop. The former is probably not very accurate. | |
314 | * | |
315 | * Return 0 if it worked, nonzero if it didn't. | |
316 | */ | |
336f7c5f | 317 | static int synchronize_to_clock_tick(const struct hwclock_control *ctl) |
ef71b8f1 | 318 | { |
63cccae4 | 319 | int rc; |
7eda085c | 320 | |
336f7c5f | 321 | if (ctl->debug) |
ef71b8f1 | 322 | printf(_("Waiting for clock tick...\n")); |
7eda085c | 323 | |
336f7c5f | 324 | rc = ur->synchronize_to_clock_tick(ctl); |
63cccae4 | 325 | |
336f7c5f | 326 | if (ctl->debug) { |
3b96a7ac KZ |
327 | if (rc) |
328 | printf(_("...synchronization failed\n")); | |
329 | else | |
330 | printf(_("...got clock tick\n")); | |
331 | } | |
63cccae4 KZ |
332 | |
333 | return rc; | |
7eda085c KZ |
334 | } |
335 | ||
ef71b8f1 SK |
336 | /* |
337 | * Convert a time in broken down format (hours, minutes, etc.) into standard | |
338 | * unix time (seconds into epoch). Return it as *systime_p. | |
339 | * | |
340 | * The broken down time is argument <tm>. This broken down time is either | |
341 | * in local time zone or UTC, depending on value of logical argument | |
342 | * "universal". True means it is in UTC. | |
343 | * | |
344 | * If the argument contains values that do not constitute a valid time, and | |
345 | * mktime() recognizes this, return *valid_p == false and *systime_p | |
346 | * undefined. However, mktime() sometimes goes ahead and computes a | |
347 | * fictional time "as if" the input values were valid, e.g. if they indicate | |
348 | * the 31st day of April, mktime() may compute the time of May 1. In such a | |
349 | * case, we return the same fictional value mktime() does as *systime_p and | |
350 | * return *valid_p == true. | |
351 | */ | |
7eda085c | 352 | static void |
336f7c5f SK |
353 | mktime_tz(const struct hwclock_control *ctl, struct tm tm, |
354 | bool *valid_p, time_t *systime_p) | |
ef71b8f1 | 355 | { |
336f7c5f | 356 | if (ctl->universal) |
12f1cdda SK |
357 | *systime_p = timegm(&tm); |
358 | else | |
359 | *systime_p = mktime(&tm); | |
360 | if (*systime_p == -1) { | |
ef71b8f1 SK |
361 | /* |
362 | * This apparently (not specified in mktime() documentation) | |
363 | * means the 'tm' structure does not contain valid values | |
364 | * (however, not containing valid values does _not_ imply | |
365 | * mktime() returns -1). | |
366 | */ | |
367 | *valid_p = FALSE; | |
336f7c5f | 368 | if (ctl->debug) |
ef71b8f1 SK |
369 | printf(_("Invalid values in hardware clock: " |
370 | "%4d/%.2d/%.2d %.2d:%.2d:%.2d\n"), | |
371 | tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday, | |
372 | tm.tm_hour, tm.tm_min, tm.tm_sec); | |
373 | } else { | |
374 | *valid_p = TRUE; | |
336f7c5f | 375 | if (ctl->debug) |
ef71b8f1 SK |
376 | printf(_ |
377 | ("Hw clock time : %4d/%.2d/%.2d %.2d:%.2d:%.2d = " | |
378 | "%ld seconds since 1969\n"), tm.tm_year + 1900, | |
379 | tm.tm_mon + 1, tm.tm_mday, tm.tm_hour, tm.tm_min, | |
380 | tm.tm_sec, (long)*systime_p); | |
381 | } | |
7eda085c KZ |
382 | } |
383 | ||
ef71b8f1 SK |
384 | /* |
385 | * Read the hardware clock and return the current time via <tm> argument. | |
386 | * | |
387 | * Use the method indicated by <method> argument to access the hardware | |
388 | * clock. | |
389 | */ | |
cdedde03 | 390 | static int |
336f7c5f SK |
391 | read_hardware_clock(const struct hwclock_control *ctl, |
392 | bool * valid_p, time_t *systime_p) | |
ef71b8f1 SK |
393 | { |
394 | struct tm tm; | |
395 | int err; | |
7eda085c | 396 | |
336f7c5f | 397 | err = ur->read_hardware_clock(ctl, &tm); |
ef71b8f1 SK |
398 | if (err) |
399 | return err; | |
7eda085c | 400 | |
336f7c5f | 401 | if (ctl->badyear) |
ef71b8f1 | 402 | read_date_from_file(&tm); |
7eda085c | 403 | |
336f7c5f | 404 | if (ctl->debug) |
ef71b8f1 SK |
405 | printf(_ |
406 | ("Time read from Hardware Clock: %4d/%.2d/%.2d %02d:%02d:%02d\n"), | |
407 | tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday, tm.tm_hour, | |
408 | tm.tm_min, tm.tm_sec); | |
336f7c5f | 409 | mktime_tz(ctl, tm, valid_p, systime_p); |
cdedde03 | 410 | |
ef71b8f1 | 411 | return 0; |
7eda085c KZ |
412 | } |
413 | ||
ef71b8f1 SK |
414 | /* |
415 | * Set the Hardware Clock to the time <newtime>, in local time zone or UTC, | |
416 | * according to <universal>. | |
417 | */ | |
7eda085c | 418 | static void |
336f7c5f | 419 | set_hardware_clock(const struct hwclock_control *ctl, const time_t newtime) |
ef71b8f1 SK |
420 | { |
421 | struct tm new_broken_time; | |
422 | /* | |
423 | * Time to which we will set Hardware Clock, in broken down format, | |
424 | * in the time zone of caller's choice | |
425 | */ | |
426 | ||
336f7c5f | 427 | if (ctl->universal) |
ef71b8f1 SK |
428 | new_broken_time = *gmtime(&newtime); |
429 | else | |
430 | new_broken_time = *localtime(&newtime); | |
7eda085c | 431 | |
336f7c5f | 432 | if (ctl->debug) |
ef71b8f1 SK |
433 | printf(_("Setting Hardware Clock to %.2d:%.2d:%.2d " |
434 | "= %ld seconds since 1969\n"), | |
435 | new_broken_time.tm_hour, new_broken_time.tm_min, | |
436 | new_broken_time.tm_sec, (long)newtime); | |
7eda085c | 437 | |
336f7c5f | 438 | if (ctl->testing) |
ef71b8f1 SK |
439 | printf(_("Clock not changed - testing only.\n")); |
440 | else { | |
336f7c5f | 441 | if (ctl->badyear) { |
ef71b8f1 SK |
442 | /* |
443 | * Write the real year to a file, then write a fake | |
444 | * year between 1995 and 1998 to the RTC. This way, | |
445 | * Award BIOS boots on 29 Feb 2000 thinking that | |
446 | * it's 29 Feb 1996. | |
447 | */ | |
448 | write_date_to_file(&new_broken_time); | |
449 | new_broken_time.tm_year = | |
450 | 95 + ((new_broken_time.tm_year + 1) & 3); | |
451 | } | |
336f7c5f | 452 | ur->set_hardware_clock(ctl, &new_broken_time); |
ef71b8f1 SK |
453 | } |
454 | } | |
7eda085c | 455 | |
ef71b8f1 SK |
456 | /* |
457 | * Set the Hardware Clock to the time "sethwtime", in local time zone or | |
458 | * UTC, according to "universal". | |
459 | * | |
460 | * Wait for a fraction of a second so that "sethwtime" is the value of the | |
461 | * Hardware Clock as of system time "refsystime", which is in the past. For | |
462 | * example, if "sethwtime" is 14:03:05 and "refsystime" is 12:10:04.5 and | |
463 | * the current system time is 12:10:06.0: Wait .5 seconds (to make exactly 2 | |
464 | * seconds since "refsystime") and then set the Hardware Clock to 14:03:07, | |
465 | * thus getting a precise and retroactive setting of the clock. | |
466 | * | |
467 | * (Don't be confused by the fact that the system clock and the Hardware | |
468 | * Clock differ by two hours in the above example. That's just to remind you | |
469 | * that there are two independent time scales here). | |
470 | * | |
471 | * This function ought to be able to accept set times as fractional times. | |
472 | * Idea for future enhancement. | |
473 | */ | |
7eda085c | 474 | static void |
336f7c5f SK |
475 | set_hardware_clock_exact(const struct hwclock_control *ctl, |
476 | const time_t sethwtime, | |
477 | const struct timeval refsystime) | |
ef71b8f1 | 478 | { |
ef71b8f1 | 479 | /* |
4a44a54b CM |
480 | * The Hardware Clock can only be set to any integer time plus one |
481 | * half second. The integer time is required because there is no | |
482 | * interface to set or get a fractional second. The additional half | |
483 | * second is because the Hardware Clock updates to the following | |
484 | * second precisely 500 ms (not 1 second!) after you release the | |
485 | * divider reset (after setting the new time) - see description of | |
486 | * DV2, DV1, DV0 in Register A in the MC146818A data sheet (and note | |
487 | * that although that document doesn't say so, real-world code seems | |
488 | * to expect that the SET bit in Register B functions the same way). | |
489 | * That means that, e.g., when you set the clock to 1:02:03, it | |
490 | * effectively really sets it to 1:02:03.5, because it will update to | |
491 | * 1:02:04 only half a second later. Our caller passes the desired | |
492 | * integer Hardware Clock time in sethwtime, and the corresponding | |
493 | * system time (which may have a fractional part, and which may or may | |
494 | * not be the same!) in refsystime. In an ideal situation, we would | |
495 | * then apply sethwtime to the Hardware Clock at refsystime+500ms, so | |
496 | * that when the Hardware Clock ticks forward to sethwtime+1s half a | |
497 | * second later at refsystime+1000ms, everything is in sync. So we | |
498 | * spin, waiting for gettimeofday() to return a time at or after that | |
499 | * time (refsystime+500ms) up to a tolerance value, initially 1ms. If | |
500 | * we miss that time due to being preempted for some other process, | |
501 | * then we increase the margin a little bit (initially 1ms, doubling | |
502 | * each time), add 1 second (or more, if needed to get a time that is | |
503 | * in the future) to both the time for which we are waiting and the | |
504 | * time that we will apply to the Hardware Clock, and start waiting | |
505 | * again. | |
506 | * | |
507 | * For example, the caller requests that we set the Hardware Clock to | |
508 | * 1:02:03, with reference time (current system time) = 6:07:08.250. | |
509 | * We want the Hardware Clock to update to 1:02:04 at 6:07:09.250 on | |
510 | * the system clock, and the first such update will occur 0.500 | |
511 | * seconds after we write to the Hardware Clock, so we spin until the | |
512 | * system clock reads 6:07:08.750. If we get there, great, but let's | |
513 | * imagine the system is so heavily loaded that our process is | |
514 | * preempted and by the time we get to run again, the system clock | |
515 | * reads 6:07:11.990. We now want to wait until the next xx:xx:xx.750 | |
516 | * time, which is 6:07:12.750 (4.5 seconds after the reference time), | |
517 | * at which point we will set the Hardware Clock to 1:02:07 (4 seconds | |
518 | * after the originally requested time). If we do that successfully, | |
519 | * then at 6:07:13.250 (5 seconds after the reference time), the | |
520 | * Hardware Clock will update to 1:02:08 (5 seconds after the | |
521 | * originally requested time), and all is well thereafter. | |
ef71b8f1 | 522 | */ |
4a44a54b CM |
523 | |
524 | time_t newhwtime = sethwtime; | |
525 | double target_time_tolerance_secs = 0.001; /* initial value */ | |
526 | double tolerance_incr_secs = 0.001; /* initial value */ | |
527 | const double RTC_SET_DELAY_SECS = 0.5; /* 500 ms */ | |
528 | const struct timeval RTC_SET_DELAY_TV = { 0, RTC_SET_DELAY_SECS * 1E6 }; | |
529 | ||
530 | struct timeval targetsystime; | |
531 | struct timeval nowsystime; | |
532 | struct timeval prevsystime = refsystime; | |
533 | double deltavstarget; | |
534 | ||
535 | timeradd(&refsystime, &RTC_SET_DELAY_TV, &targetsystime); | |
536 | ||
537 | while (1) { | |
538 | double ticksize; | |
539 | ||
540 | /* FOR TESTING ONLY: inject random delays of up to 1000ms */ | |
336f7c5f | 541 | if (ctl->debug >= 10) { |
4a44a54b CM |
542 | int usec = random() % 1000000; |
543 | printf(_("sleeping ~%d usec\n"), usec); | |
559a5b6c | 544 | xusleep(usec); |
ea0804b0 SK |
545 | } |
546 | ||
ef71b8f1 | 547 | gettimeofday(&nowsystime, NULL); |
4a44a54b CM |
548 | deltavstarget = time_diff(nowsystime, targetsystime); |
549 | ticksize = time_diff(nowsystime, prevsystime); | |
550 | prevsystime = nowsystime; | |
551 | ||
552 | if (ticksize < 0) { | |
336f7c5f | 553 | if (ctl->debug) |
4a44a54b | 554 | printf(_("time jumped backward %.6f seconds " |
c2114018 | 555 | "to %ld.%06ld - retargeting\n"), |
b68e1f44 SK |
556 | ticksize, nowsystime.tv_sec, |
557 | nowsystime.tv_usec); | |
4a44a54b CM |
558 | /* The retarget is handled at the end of the loop. */ |
559 | } else if (deltavstarget < 0) { | |
560 | /* deltavstarget < 0 if current time < target time */ | |
336f7c5f | 561 | if (ctl->debug >= 2) |
c2114018 | 562 | printf(_("%ld.%06ld < %ld.%06ld (%.6f)\n"), |
b68e1f44 SK |
563 | nowsystime.tv_sec, |
564 | nowsystime.tv_usec, | |
565 | targetsystime.tv_sec, | |
566 | targetsystime.tv_usec, | |
4a44a54b CM |
567 | deltavstarget); |
568 | continue; /* not there yet - keep spinning */ | |
569 | } else if (deltavstarget <= target_time_tolerance_secs) { | |
570 | /* Close enough to the target time; done waiting. */ | |
571 | break; | |
572 | } else /* (deltavstarget > target_time_tolerance_secs) */ { | |
573 | /* | |
574 | * We missed our window. Increase the tolerance and | |
575 | * aim for the next opportunity. | |
576 | */ | |
336f7c5f | 577 | if (ctl->debug) |
c2114018 RM |
578 | printf(_("missed it - %ld.%06ld is too far " |
579 | "past %ld.%06ld (%.6f > %.6f)\n"), | |
b68e1f44 SK |
580 | nowsystime.tv_sec, |
581 | nowsystime.tv_usec, | |
582 | targetsystime.tv_sec, | |
583 | targetsystime.tv_usec, | |
4a44a54b CM |
584 | deltavstarget, |
585 | target_time_tolerance_secs); | |
586 | target_time_tolerance_secs += tolerance_incr_secs; | |
587 | tolerance_incr_secs *= 2; | |
ea0804b0 | 588 | } |
4a44a54b CM |
589 | |
590 | /* | |
591 | * Aim for the same offset (tv_usec) within the second in | |
592 | * either the current second (if that offset hasn't arrived | |
593 | * yet), or the next second. | |
594 | */ | |
595 | if (nowsystime.tv_usec < targetsystime.tv_usec) | |
596 | targetsystime.tv_sec = nowsystime.tv_sec; | |
597 | else | |
598 | targetsystime.tv_sec = nowsystime.tv_sec + 1; | |
599 | } | |
600 | ||
601 | newhwtime = sethwtime | |
602 | + (int)(time_diff(nowsystime, refsystime) | |
603 | - RTC_SET_DELAY_SECS /* don't count this */ | |
604 | + 0.5 /* for rounding */); | |
336f7c5f | 605 | if (ctl->debug) |
c2114018 RM |
606 | printf(_("%ld.%06ld is close enough to %ld.%06ld (%.6f < %.6f)\n" |
607 | "Set RTC to %ld (%ld + %d; refsystime = %ld.%06ld)\n"), | |
b68e1f44 SK |
608 | nowsystime.tv_sec, nowsystime.tv_usec, |
609 | targetsystime.tv_sec, targetsystime.tv_usec, | |
4a44a54b | 610 | deltavstarget, target_time_tolerance_secs, |
b68e1f44 | 611 | newhwtime, sethwtime, |
4a44a54b | 612 | (int)(newhwtime - sethwtime), |
b68e1f44 | 613 | refsystime.tv_sec, refsystime.tv_usec); |
ef71b8f1 | 614 | |
336f7c5f | 615 | set_hardware_clock(ctl, newhwtime); |
7eda085c KZ |
616 | } |
617 | ||
ef71b8f1 | 618 | /* |
ede32597 | 619 | * Put the time "hwctime" on standard output in display format. Except if |
ef71b8f1 SK |
620 | * hclock_valid == false, just tell standard output that we don't know what |
621 | * time it is. | |
ef71b8f1 | 622 | */ |
7eda085c | 623 | static void |
2794995a | 624 | display_time(const bool hclock_valid, struct timeval hwctime) |
ef71b8f1 SK |
625 | { |
626 | if (!hclock_valid) | |
111c05d3 SK |
627 | warnx(_ |
628 | ("The Hardware Clock registers contain values that are " | |
629 | "either invalid (e.g. 50th day of month) or beyond the range " | |
630 | "we can handle (e.g. Year 2095).")); | |
ef71b8f1 | 631 | else { |
7c678f81 KZ |
632 | char buf[ISO_8601_BUFSIZ]; |
633 | ||
634 | strtimeval_iso(&hwctime, ISO_8601_DATE|ISO_8601_TIME|ISO_8601_DOTUSEC| | |
635 | ISO_8601_TIMEZONE|ISO_8601_SPACE, | |
636 | buf, sizeof(buf)); | |
637 | printf("%s\n", buf); | |
ef71b8f1 SK |
638 | } |
639 | } | |
7eda085c | 640 | |
ef71b8f1 SK |
641 | /* |
642 | * Interpret the value of the --date option, which is something like | |
643 | * "13:05:01". In fact, it can be any of the myriad ASCII strings that | |
644 | * specify a time which the "date" program can understand. The date option | |
645 | * value in question is our "dateopt" argument. | |
646 | * | |
647 | * The specified time is in the local time zone. | |
648 | * | |
649 | * Our output, "*time_p", is a seconds-into-epoch time. | |
650 | * | |
651 | * We use the "date" program to interpret the date string. "date" must be | |
652 | * runnable by issuing the command "date" to the /bin/sh shell. That means | |
653 | * in must be in the current PATH. | |
654 | * | |
a7349ee3 | 655 | * If anything goes wrong (and many things can), we return code 10 |
ef71b8f1 SK |
656 | * and arbitrary *time_p. Otherwise, return code is 0 and *time_p is valid. |
657 | */ | |
336f7c5f SK |
658 | static int interpret_date_string(const struct hwclock_control *ctl, |
659 | time_t *const time_p) | |
ef71b8f1 | 660 | { |
6b3cb186 SK |
661 | FILE *date_child_fp = NULL; |
662 | char *date_command = NULL; | |
710684e8 SK |
663 | char *date_resp = NULL; |
664 | size_t len = 0; | |
ef71b8f1 | 665 | const char magic[] = "seconds-into-epoch="; |
6b3cb186 SK |
666 | int retcode = 1; |
667 | long seconds_since_epoch; | |
e8f26419 | 668 | |
336f7c5f | 669 | if (!ctl->date_opt) { |
111c05d3 | 670 | warnx(_("No --date option specified.")); |
6b3cb186 | 671 | return retcode; |
e8f26419 KZ |
672 | } |
673 | ||
674 | /* Quotes in date_opt would ruin the date command we construct. */ | |
9c65888e SK |
675 | if (strchr(ctl->date_opt, '"') != NULL || |
676 | strchr(ctl->date_opt, '`') != NULL || | |
677 | strchr(ctl->date_opt, '$') != NULL) { | |
111c05d3 SK |
678 | warnx(_ |
679 | ("The value of the --date option is not a valid date.\n" | |
9c65888e | 680 | "In particular, it contains illegal character(s).")); |
6b3cb186 | 681 | return retcode; |
e8f26419 KZ |
682 | } |
683 | ||
710684e8 | 684 | xasprintf(&date_command, "date --date=\"%s\" +%s%%s", |
336f7c5f SK |
685 | ctl->date_opt, magic); |
686 | if (ctl->debug) | |
e8f26419 KZ |
687 | printf(_("Issuing date command: %s\n"), date_command); |
688 | ||
689 | date_child_fp = popen(date_command, "r"); | |
690 | if (date_child_fp == NULL) { | |
111c05d3 | 691 | warn(_("Unable to run 'date' program in /bin/sh shell. " |
e8f26419 | 692 | "popen() failed")); |
6b3cb186 | 693 | goto out; |
e8f26419 KZ |
694 | } |
695 | ||
710684e8 SK |
696 | if (getline(&date_resp, &len, date_child_fp) < 0) { |
697 | warn(_("getline() failed")); | |
6b3cb186 | 698 | goto out; |
710684e8 | 699 | } |
336f7c5f | 700 | if (ctl->debug) |
e8f26419 | 701 | printf(_("response from date command = %s\n"), date_resp); |
ef71b8f1 | 702 | if (strncmp(date_resp, magic, sizeof(magic) - 1) != 0) { |
111c05d3 | 703 | warnx(_("The date command issued by %s returned " |
e8f26419 KZ |
704 | "unexpected results.\n" |
705 | "The command was:\n %s\n" | |
111c05d3 SK |
706 | "The response was:\n %s"), |
707 | program_invocation_short_name, date_command, date_resp); | |
6b3cb186 SK |
708 | goto out; |
709 | } | |
710 | ||
711 | if (sscanf(date_resp + sizeof(magic) - 1, "%ld", &seconds_since_epoch) < 1) { | |
712 | warnx(_("The date command issued by %s returned " | |
713 | "something other than an integer where the " | |
714 | "converted time value was expected.\n" | |
715 | "The command was:\n %s\n" | |
716 | "The response was:\n %s\n"), | |
717 | program_invocation_short_name, date_command, date_resp); | |
e8f26419 | 718 | } else { |
6b3cb186 SK |
719 | retcode = 0; |
720 | *time_p = seconds_since_epoch; | |
721 | if (ctl->debug) | |
722 | printf(_("date string %s equates to " | |
723 | "%ld seconds since 1969.\n"), | |
724 | ctl->date_opt, *time_p); | |
e8f26419 | 725 | } |
6b3cb186 | 726 | out: |
710684e8 SK |
727 | free(date_command); |
728 | free(date_resp); | |
6b3cb186 SK |
729 | if (date_child_fp) |
730 | pclose(date_child_fp); | |
e8f26419 | 731 | |
63cccae4 | 732 | return retcode; |
7eda085c KZ |
733 | } |
734 | ||
ef71b8f1 SK |
735 | /* |
736 | * Set the System Clock to time 'newtime'. | |
737 | * | |
738 | * Also set the kernel time zone value to the value indicated by the TZ | |
739 | * environment variable and/or /usr/lib/zoneinfo/, interpreted as tzset() | |
740 | * would interpret them. | |
741 | * | |
d17a12a3 WP |
742 | * If this is the first call of settimeofday since boot, then this also sets |
743 | * the kernel variable persistent_clock_is_local so that NTP 11 minute mode | |
744 | * will update the Hardware Clock with the proper timescale. If the Hardware | |
745 | * Clock's timescale configuration is changed then a reboot is required for | |
746 | * persistent_clock_is_local to be updated. | |
747 | * | |
ef71b8f1 SK |
748 | * EXCEPT: if hclock_valid is false, just issue an error message saying |
749 | * there is no valid time in the Hardware Clock to which to set the system | |
750 | * time. | |
751 | * | |
752 | * If 'testing' is true, don't actually update anything -- just say we would | |
753 | * have. | |
754 | */ | |
9abb2685 | 755 | static int |
336f7c5f SK |
756 | set_system_clock(const struct hwclock_control *ctl, const bool hclock_valid, |
757 | const struct timeval newtime) | |
ef71b8f1 SK |
758 | { |
759 | int retcode; | |
760 | ||
761 | if (!hclock_valid) { | |
111c05d3 SK |
762 | warnx(_ |
763 | ("The Hardware Clock does not contain a valid time, so " | |
764 | "we cannot set the System Time from it.")); | |
ef71b8f1 SK |
765 | retcode = 1; |
766 | } else { | |
d17a12a3 | 767 | const struct timeval *tv_null = NULL; |
ef71b8f1 SK |
768 | struct tm *broken; |
769 | int minuteswest; | |
d17a12a3 | 770 | int rc = 0; |
ef71b8f1 | 771 | |
2794995a | 772 | broken = localtime(&newtime.tv_sec); |
48d7b13a | 773 | #ifdef HAVE_TM_GMTOFF |
ef71b8f1 | 774 | minuteswest = -broken->tm_gmtoff / 60; /* GNU extension */ |
22853e4a | 775 | #else |
ef71b8f1 SK |
776 | minuteswest = timezone / 60; |
777 | if (broken->tm_isdst) | |
778 | minuteswest -= 60; | |
22853e4a | 779 | #endif |
9abb2685 | 780 | |
336f7c5f | 781 | if (ctl->debug) { |
ef71b8f1 SK |
782 | printf(_("Calling settimeofday:\n")); |
783 | printf(_("\ttv.tv_sec = %ld, tv.tv_usec = %ld\n"), | |
b68e1f44 | 784 | newtime.tv_sec, newtime.tv_usec); |
ef71b8f1 SK |
785 | printf(_("\ttz.tz_minuteswest = %d\n"), minuteswest); |
786 | } | |
336f7c5f | 787 | if (ctl->testing) { |
ef71b8f1 SK |
788 | printf(_ |
789 | ("Not setting system clock because running in test mode.\n")); | |
790 | retcode = 0; | |
791 | } else { | |
792 | const struct timezone tz = { minuteswest, 0 }; | |
793 | ||
d17a12a3 WP |
794 | /* Set kernel persistent_clock_is_local so that 11 minute |
795 | * mode does not clobber the Hardware Clock with UTC. This | |
796 | * is only available on first call of settimeofday after boot. | |
797 | */ | |
336f7c5f | 798 | if (!ctl->universal) |
d17a12a3 WP |
799 | rc = settimeofday(tv_null, &tz); |
800 | if (!rc) | |
801 | rc = settimeofday(&newtime, &tz); | |
ef71b8f1 SK |
802 | if (rc) { |
803 | if (errno == EPERM) { | |
111c05d3 SK |
804 | warnx(_ |
805 | ("Must be superuser to set system clock.")); | |
ef71b8f1 SK |
806 | retcode = EX_NOPERM; |
807 | } else { | |
111c05d3 | 808 | warn(_("settimeofday() failed")); |
ef71b8f1 SK |
809 | retcode = 1; |
810 | } | |
811 | } else | |
812 | retcode = 0; | |
813 | } | |
814 | } | |
815 | return retcode; | |
7eda085c KZ |
816 | } |
817 | ||
ef71b8f1 SK |
818 | /* |
819 | * Reset the System Clock from local time to UTC, based on its current value | |
820 | * and the timezone unless universal is TRUE. | |
821 | * | |
822 | * Also set the kernel time zone value to the value indicated by the TZ | |
823 | * environment variable and/or /usr/lib/zoneinfo/, interpreted as tzset() | |
824 | * would interpret them. | |
825 | * | |
826 | * If 'testing' is true, don't actually update anything -- just say we would | |
827 | * have. | |
828 | */ | |
336f7c5f | 829 | static int set_system_clock_timezone(const struct hwclock_control *ctl) |
ef71b8f1 SK |
830 | { |
831 | int retcode; | |
832 | struct timeval tv; | |
833 | struct tm *broken; | |
834 | int minuteswest; | |
ef71b8f1 SK |
835 | |
836 | gettimeofday(&tv, NULL); | |
336f7c5f | 837 | if (ctl->debug) { |
ef71b8f1 SK |
838 | struct tm broken_time; |
839 | char ctime_now[200]; | |
840 | ||
841 | broken_time = *gmtime(&tv.tv_sec); | |
842 | strftime(ctime_now, sizeof(ctime_now), "%Y/%m/%d %H:%M:%S", | |
843 | &broken_time); | |
b68e1f44 | 844 | printf(_("Current system time: %ld = %s\n"), tv.tv_sec, |
ef71b8f1 SK |
845 | ctime_now); |
846 | } | |
7eda085c | 847 | |
ef71b8f1 | 848 | broken = localtime(&tv.tv_sec); |
88a3372e | 849 | #ifdef HAVE_TM_GMTOFF |
ef71b8f1 | 850 | minuteswest = -broken->tm_gmtoff / 60; /* GNU extension */ |
88a3372e | 851 | #else |
ef71b8f1 SK |
852 | minuteswest = timezone / 60; |
853 | if (broken->tm_isdst) | |
854 | minuteswest -= 60; | |
88a3372e SJR |
855 | #endif |
856 | ||
336f7c5f | 857 | if (ctl->debug) { |
ef71b8f1 SK |
858 | struct tm broken_time; |
859 | char ctime_now[200]; | |
860 | ||
839be2ba | 861 | gettimeofday(&tv, NULL); |
336f7c5f | 862 | if (!ctl->universal) |
839be2ba KZ |
863 | tv.tv_sec += minuteswest * 60; |
864 | ||
ef71b8f1 SK |
865 | broken_time = *gmtime(&tv.tv_sec); |
866 | strftime(ctime_now, sizeof(ctime_now), "%Y/%m/%d %H:%M:%S", | |
867 | &broken_time); | |
868 | ||
869 | printf(_("Calling settimeofday:\n")); | |
870 | printf(_("\tUTC: %s\n"), ctime_now); | |
871 | printf(_("\ttv.tv_sec = %ld, tv.tv_usec = %ld\n"), | |
b68e1f44 | 872 | tv.tv_sec, tv.tv_usec); |
ef71b8f1 SK |
873 | printf(_("\ttz.tz_minuteswest = %d\n"), minuteswest); |
874 | } | |
336f7c5f | 875 | if (ctl->testing) { |
ef71b8f1 SK |
876 | printf(_ |
877 | ("Not setting system clock because running in test mode.\n")); | |
878 | retcode = 0; | |
879 | } else { | |
910a0900 | 880 | const struct timezone tz_utc = { 0, 0 }; |
ef71b8f1 | 881 | const struct timezone tz = { minuteswest, 0 }; |
839be2ba | 882 | const struct timeval *tv_null = NULL; |
910a0900 TG |
883 | int rc = 0; |
884 | ||
885 | /* The first call to settimeofday after boot will assume the systemtime | |
886 | * is in localtime, and adjust it according to the given timezone to | |
887 | * compensate. If the systemtime is in fact in UTC, then this is wrong | |
888 | * so we first do a dummy call to make sure the time is not shifted. | |
889 | */ | |
336f7c5f | 890 | if (ctl->universal) |
910a0900 TG |
891 | rc = settimeofday(tv_null, &tz_utc); |
892 | ||
893 | /* Now we set the real timezone. Due to the above dummy call, this will | |
894 | * only warp the systemtime if the RTC is not in UTC. */ | |
895 | if (!rc) | |
896 | rc = settimeofday(tv_null, &tz); | |
88a3372e | 897 | |
ef71b8f1 SK |
898 | if (rc) { |
899 | if (errno == EPERM) { | |
111c05d3 SK |
900 | warnx(_ |
901 | ("Must be superuser to set system clock.")); | |
ef71b8f1 SK |
902 | retcode = EX_NOPERM; |
903 | } else { | |
111c05d3 | 904 | warn(_("settimeofday() failed")); |
ef71b8f1 SK |
905 | retcode = 1; |
906 | } | |
907 | } else | |
908 | retcode = 0; | |
909 | } | |
910 | return retcode; | |
911 | } | |
912 | ||
913 | /* | |
f276d71a WP |
914 | * Refresh the last calibrated and last adjusted timestamps in <*adjtime_p> |
915 | * to facilitate future drift calculations based on this set point. | |
ef71b8f1 | 916 | * |
f276d71a WP |
917 | * With the --update-drift option: |
918 | * Update the drift factor in <*adjtime_p> based on the fact that the | |
919 | * Hardware Clock was just calibrated to <nowtime> and before that was | |
920 | * set to the <hclocktime> time scale. | |
ef71b8f1 SK |
921 | * |
922 | * EXCEPT: if <hclock_valid> is false, assume Hardware Clock was not set | |
923 | * before to anything meaningful and regular adjustments have not been done, | |
924 | * so don't adjust the drift factor. | |
925 | */ | |
7eda085c | 926 | static void |
336f7c5f SK |
927 | adjust_drift_factor(const struct hwclock_control *ctl, |
928 | struct adjtime *adjtime_p, | |
2794995a | 929 | const struct timeval nowtime, |
ef71b8f1 | 930 | const bool hclock_valid, |
336f7c5f | 931 | const struct timeval hclocktime) |
ef71b8f1 | 932 | { |
336f7c5f SK |
933 | if (!ctl->update) { |
934 | if (ctl->debug) | |
f276d71a WP |
935 | printf(_("Not adjusting drift factor because the " |
936 | "--update-drift option was not used.\n")); | |
937 | } else if (!hclock_valid) { | |
336f7c5f | 938 | if (ctl->debug) |
63cccae4 KZ |
939 | printf(_("Not adjusting drift factor because the " |
940 | "Hardware Clock previously contained " | |
941 | "garbage.\n")); | |
942 | } else if (adjtime_p->last_calib_time == 0) { | |
336f7c5f | 943 | if (ctl->debug) |
63cccae4 KZ |
944 | printf(_("Not adjusting drift factor because last " |
945 | "calibration time is zero,\n" | |
946 | "so history is bad and calibration startover " | |
947 | "is necessary.\n")); | |
bbb4c273 | 948 | } else if ((hclocktime.tv_sec - adjtime_p->last_calib_time) < 4 * 60 * 60) { |
336f7c5f | 949 | if (ctl->debug) |
63cccae4 | 950 | printf(_("Not adjusting drift factor because it has " |
bbb4c273 | 951 | "been less than four hours since the last " |
63cccae4 | 952 | "calibration.\n")); |
c6ea9ef6 | 953 | } else { |
63cccae4 | 954 | /* |
f276d71a WP |
955 | * At adjustment time we drift correct the hardware clock |
956 | * according to the contents of the adjtime file and refresh | |
957 | * its last adjusted timestamp. | |
63cccae4 | 958 | * |
f276d71a WP |
959 | * At calibration time we set the Hardware Clock and refresh |
960 | * both timestamps in <*adjtime_p>. | |
63cccae4 | 961 | * |
f276d71a WP |
962 | * Here, with the --update-drift option, we also update the |
963 | * drift factor in <*adjtime_p>. | |
63cccae4 KZ |
964 | * |
965 | * Let us do computation in doubles. (Floats almost suffice, | |
966 | * but 195 days + 1 second equals 195 days in floats.) | |
967 | */ | |
968 | const double sec_per_day = 24.0 * 60.0 * 60.0; | |
63cccae4 | 969 | double factor_adjust; |
f196fd1a | 970 | double drift_factor; |
2794995a | 971 | struct timeval last_calib; |
63cccae4 | 972 | |
2794995a | 973 | last_calib = t2tv(adjtime_p->last_calib_time); |
ede32597 WP |
974 | /* |
975 | * Correction to apply to the current drift factor. | |
976 | * | |
977 | * Simplified: uncorrected_drift / days_since_calibration. | |
978 | * | |
979 | * hclocktime is fully corrected with the current drift factor. | |
980 | * Its difference from nowtime is the missed drift correction. | |
981 | */ | |
2794995a WP |
982 | factor_adjust = time_diff(nowtime, hclocktime) / |
983 | (time_diff(nowtime, last_calib) / sec_per_day); | |
63cccae4 | 984 | |
f196fd1a | 985 | drift_factor = adjtime_p->drift_factor + factor_adjust; |
83aa4ad7 | 986 | if (fabs(drift_factor) > MAX_DRIFT) { |
336f7c5f | 987 | if (ctl->debug) |
f196fd1a SB |
988 | printf(_("Clock drift factor was calculated as " |
989 | "%f seconds/day.\n" | |
990 | "It is far too much. Resetting to zero.\n"), | |
991 | drift_factor); | |
992 | drift_factor = 0; | |
993 | } else { | |
336f7c5f | 994 | if (ctl->debug) |
a36a9026 WP |
995 | printf(_("Clock drifted %f seconds in the past " |
996 | "%f seconds\nin spite of a drift factor of " | |
f196fd1a SB |
997 | "%f seconds/day.\n" |
998 | "Adjusting drift factor by %f seconds/day\n"), | |
2794995a WP |
999 | time_diff(nowtime, hclocktime), |
1000 | time_diff(nowtime, last_calib), | |
f196fd1a SB |
1001 | adjtime_p->drift_factor, factor_adjust); |
1002 | } | |
1003 | ||
1004 | adjtime_p->drift_factor = drift_factor; | |
63cccae4 | 1005 | } |
2794995a | 1006 | adjtime_p->last_calib_time = nowtime.tv_sec; |
9abb2685 | 1007 | |
2794995a | 1008 | adjtime_p->last_adj_time = nowtime.tv_sec; |
9abb2685 | 1009 | |
63cccae4 | 1010 | adjtime_p->not_adjusted = 0; |
9abb2685 | 1011 | |
63cccae4 | 1012 | adjtime_p->dirty = TRUE; |
7eda085c KZ |
1013 | } |
1014 | ||
ef71b8f1 | 1015 | /* |
ede32597 WP |
1016 | * Calculate the drift correction currently needed for the |
1017 | * Hardware Clock based on the last time it was adjusted, | |
1018 | * and the current drift factor, as stored in the adjtime file. | |
ef71b8f1 | 1019 | * |
ede32597 | 1020 | * The total drift adjustment needed is stored at tdrift_p. |
ef71b8f1 | 1021 | * |
ef71b8f1 | 1022 | */ |
7eda085c | 1023 | static void |
336f7c5f SK |
1024 | calculate_adjustment(const struct hwclock_control *ctl, |
1025 | const double factor, | |
ef71b8f1 SK |
1026 | const time_t last_time, |
1027 | const double not_adjusted, | |
2794995a | 1028 | const time_t systime, struct timeval *tdrift_p) |
ef71b8f1 SK |
1029 | { |
1030 | double exact_adjustment; | |
7eda085c | 1031 | |
ef71b8f1 SK |
1032 | exact_adjustment = |
1033 | ((double)(systime - last_time)) * factor / (24 * 60 * 60) | |
1034 | + not_adjusted; | |
1030c325 | 1035 | tdrift_p->tv_sec = (time_t) floor(exact_adjustment); |
2794995a WP |
1036 | tdrift_p->tv_usec = (exact_adjustment - |
1037 | (double)tdrift_p->tv_sec) * 1E6; | |
336f7c5f | 1038 | if (ctl->debug) { |
b68e1f44 SK |
1039 | printf(P_("Time since last adjustment is %ld second\n", |
1040 | "Time since last adjustment is %ld seconds\n", | |
1041 | (systime - last_time)), | |
1042 | (systime - last_time)); | |
c2114018 | 1043 | printf(_("Calculated Hardware Clock drift is %ld.%06ld seconds\n"), |
b68e1f44 | 1044 | tdrift_p->tv_sec, tdrift_p->tv_usec); |
ef71b8f1 | 1045 | } |
7eda085c KZ |
1046 | } |
1047 | ||
ef71b8f1 SK |
1048 | /* |
1049 | * Write the contents of the <adjtime> structure to its disk file. | |
1050 | * | |
1051 | * But if the contents are clean (unchanged since read from disk), don't | |
1052 | * bother. | |
1053 | */ | |
336f7c5f SK |
1054 | static void save_adjtime(const struct hwclock_control *ctl, |
1055 | const struct adjtime *adjtime) | |
ef71b8f1 | 1056 | { |
4aca5fe2 SK |
1057 | char *content; /* Stuff to write to disk file */ |
1058 | FILE *fp; | |
1059 | int err = 0; | |
7eda085c | 1060 | |
4aca5fe2 SK |
1061 | if (!adjtime->dirty) |
1062 | return; | |
ef71b8f1 | 1063 | |
4aca5fe2 SK |
1064 | xasprintf(&content, "%f %ld %f\n%ld\n%s\n", |
1065 | adjtime->drift_factor, | |
1066 | adjtime->last_adj_time, | |
1067 | adjtime->not_adjusted, | |
1068 | adjtime->last_calib_time, | |
1069 | (adjtime->local_utc == LOCAL) ? "LOCAL" : "UTC"); | |
1070 | ||
1071 | if (ctl->testing) { | |
1072 | printf(_ | |
1073 | ("Not updating adjtime file because of testing mode.\n")); | |
1074 | printf(_("Would have written the following to %s:\n%s"), | |
1075 | ctl->adj_file_name, content); | |
1076 | free(content); | |
1077 | return; | |
1078 | } | |
1079 | ||
1080 | fp = fopen(ctl->adj_file_name, "w"); | |
1081 | if (fp == NULL) { | |
1082 | warn(_("Could not open file with the clock adjustment parameters " | |
1083 | "in it (%s) for writing"), ctl->adj_file_name); | |
1084 | err = 1; | |
1085 | } else if (fputs(content, fp) < 0 || close_stream(fp) != 0) { | |
1086 | warn(_("Could not update file with the clock adjustment " | |
1087 | "parameters (%s) in it"), ctl->adj_file_name); | |
1088 | err = 1; | |
ef71b8f1 | 1089 | } |
4aca5fe2 SK |
1090 | free(content); |
1091 | if (err) | |
1092 | warnx(_("Drift adjustment parameters not updated.")); | |
ef71b8f1 | 1093 | } |
7eda085c | 1094 | |
ef71b8f1 SK |
1095 | /* |
1096 | * Do the adjustment requested, by 1) setting the Hardware Clock (if | |
1097 | * necessary), and 2) updating the last-adjusted time in the adjtime | |
1098 | * structure. | |
1099 | * | |
1100 | * Do not update anything if the Hardware Clock does not currently present a | |
1101 | * valid time. | |
1102 | * | |
ede32597 | 1103 | * <hclock_valid> means the Hardware Clock contains a valid time. |
ef71b8f1 | 1104 | * |
ede32597 | 1105 | * <hclocktime> is the drift corrected time read from the Hardware Clock. |
ef71b8f1 | 1106 | * |
ede32597 WP |
1107 | * <read_time> was the system time when the <hclocktime> was read, which due |
1108 | * to computational delay could be a short time ago. It is used to define a | |
1109 | * trigger point for setting the Hardware Clock. The fractional part of the | |
1110 | * Hardware clock set time is subtracted from read_time to 'refer back', or | |
1111 | * delay, the trigger point. Fractional parts must be accounted for in this | |
1112 | * way, because the Hardware Clock can only be set to a whole second. | |
ef71b8f1 SK |
1113 | * |
1114 | * <universal>: the Hardware Clock is kept in UTC. | |
1115 | * | |
1116 | * <testing>: We are running in test mode (no updating of clock). | |
1117 | * | |
ef71b8f1 | 1118 | */ |
7eda085c | 1119 | static void |
336f7c5f | 1120 | do_adjustment(const struct hwclock_control *ctl, struct adjtime *adjtime_p, |
2794995a | 1121 | const bool hclock_valid, const struct timeval hclocktime, |
336f7c5f | 1122 | const struct timeval read_time) |
ef71b8f1 SK |
1123 | { |
1124 | if (!hclock_valid) { | |
111c05d3 SK |
1125 | warnx(_("The Hardware Clock does not contain a valid time, " |
1126 | "so we cannot adjust it.")); | |
ef71b8f1 SK |
1127 | adjtime_p->last_calib_time = 0; /* calibration startover is required */ |
1128 | adjtime_p->last_adj_time = 0; | |
1129 | adjtime_p->not_adjusted = 0; | |
1130 | adjtime_p->dirty = TRUE; | |
1131 | } else if (adjtime_p->last_adj_time == 0) { | |
336f7c5f | 1132 | if (ctl->debug) |
f55b4b45 KZ |
1133 | printf(_("Not setting clock because last adjustment time is zero, " |
1134 | "so history is bad.\n")); | |
83aa4ad7 | 1135 | } else if (fabs(adjtime_p->drift_factor) > MAX_DRIFT) { |
336f7c5f | 1136 | if (ctl->debug) |
f55b4b45 KZ |
1137 | printf(_("Not setting clock because drift factor %f is far too high.\n"), |
1138 | adjtime_p->drift_factor); | |
ef71b8f1 | 1139 | } else { |
336f7c5f | 1140 | set_hardware_clock_exact(ctl, hclocktime.tv_sec, |
2794995a | 1141 | time_inc(read_time, |
336f7c5f | 1142 | -(hclocktime.tv_usec / 1E6))); |
2794995a WP |
1143 | adjtime_p->last_adj_time = hclocktime.tv_sec; |
1144 | adjtime_p->not_adjusted = 0; | |
1145 | adjtime_p->dirty = TRUE; | |
ef71b8f1 | 1146 | } |
7eda085c KZ |
1147 | } |
1148 | ||
336f7c5f | 1149 | static void determine_clock_access_method(const struct hwclock_control *ctl) |
ef71b8f1 SK |
1150 | { |
1151 | ur = NULL; | |
7eda085c | 1152 | |
336f7c5f | 1153 | if (ctl->directisa) |
ef71b8f1 | 1154 | ur = probe_for_cmos_clock(); |
465e9973 | 1155 | #ifdef __linux__ |
ef71b8f1 | 1156 | if (!ur) |
336f7c5f | 1157 | ur = probe_for_rtc_clock(ctl); |
465e9973 | 1158 | #endif |
8f729d60 SK |
1159 | if (ur) { |
1160 | if (ctl->debug) | |
1161 | puts(ur->interface_name); | |
7eda085c | 1162 | |
8f729d60 SK |
1163 | } else { |
1164 | if (ctl->debug) | |
ef71b8f1 | 1165 | printf(_("No usable clock interface found.\n")); |
8f729d60 SK |
1166 | warnx(_("Cannot access the Hardware Clock via " |
1167 | "any known method.")); | |
1168 | if (!ctl->debug) | |
1169 | warnx(_("Use the --debug option to see the " | |
1170 | "details of our search for an access " | |
1171 | "method.")); | |
1172 | hwclock_exit(ctl, EX_SOFTWARE); | |
ef71b8f1 | 1173 | } |
7eda085c KZ |
1174 | } |
1175 | ||
ef71b8f1 SK |
1176 | /* |
1177 | * Do all the normal work of hwclock - read, set clock, etc. | |
1178 | * | |
1179 | * Issue output to stdout and error message to stderr where appropriate. | |
1180 | * | |
1181 | * Return rc == 0 if everything went OK, rc != 0 if not. | |
1182 | */ | |
63cccae4 | 1183 | static int |
336f7c5f SK |
1184 | manipulate_clock(const struct hwclock_control *ctl, const time_t set_time, |
1185 | const struct timeval startup_time, struct adjtime *adjtime) | |
ef71b8f1 | 1186 | { |
ef71b8f1 SK |
1187 | /* The time at which we read the Hardware Clock */ |
1188 | struct timeval read_time; | |
1189 | /* | |
1190 | * The Hardware Clock gives us a valid time, or at | |
1191 | * least something close enough to fool mktime(). | |
1192 | */ | |
1193 | bool hclock_valid = FALSE; | |
1194 | /* | |
ede32597 WP |
1195 | * Tick synchronized time read from the Hardware Clock and |
1196 | * then drift correct for all operations except --show. | |
ef71b8f1 | 1197 | */ |
2794995a | 1198 | struct timeval hclocktime = { 0, 0 }; |
ede32597 | 1199 | /* Total Hardware Clock drift correction needed. */ |
2794995a | 1200 | struct timeval tdrift; |
ef71b8f1 | 1201 | /* local return code */ |
23341bd4 | 1202 | int rc = 0; |
ef71b8f1 | 1203 | |
a18f17ad KZ |
1204 | if (!ctl->systz && !ctl->predict && ur->get_permissions()) |
1205 | return EX_NOPERM; | |
ef71b8f1 | 1206 | |
336f7c5f SK |
1207 | if ((ctl->set || ctl->systohc || ctl->adjust) && |
1208 | (adjtime->local_utc == UTC) != ctl->universal) { | |
1209 | adjtime->local_utc = ctl->universal ? UTC : LOCAL; | |
1210 | adjtime->dirty = TRUE; | |
ef71b8f1 | 1211 | } |
9abb2685 | 1212 | |
336f7c5f SK |
1213 | if (ctl->show || ctl->get || ctl->adjust || ctl->hctosys |
1214 | || (!ctl->noadjfile && !ctl->systz && !ctl->predict)) { | |
ef71b8f1 | 1215 | /* data from HW-clock are required */ |
336f7c5f | 1216 | rc = synchronize_to_clock_tick(ctl); |
ef71b8f1 SK |
1217 | |
1218 | /* | |
0f32118e SK |
1219 | * We don't error out if the user is attempting to set the |
1220 | * RTC and synchronization timeout happens - the RTC could | |
1221 | * be functioning but contain invalid time data so we still | |
1222 | * want to allow a user to set the RTC time. | |
ef71b8f1 | 1223 | */ |
0f32118e | 1224 | if (rc == RTC_BUSYWAIT_FAILED && !ctl->set && !ctl->systohc) |
ef71b8f1 SK |
1225 | return EX_IOERR; |
1226 | gettimeofday(&read_time, NULL); | |
1227 | ||
1228 | /* | |
1229 | * If we can't synchronize to a clock tick, | |
1230 | * we likely can't read from the RTC so | |
1231 | * don't bother reading it again. | |
1232 | */ | |
1233 | if (!rc) { | |
336f7c5f SK |
1234 | rc = read_hardware_clock(ctl, &hclock_valid, |
1235 | &hclocktime.tv_sec); | |
1236 | if (rc && !ctl->set && !ctl->systohc) | |
ef71b8f1 SK |
1237 | return EX_IOERR; |
1238 | } | |
cdedde03 | 1239 | } |
ede32597 WP |
1240 | /* |
1241 | * Calculate Hardware Clock drift for --predict with the user | |
1242 | * supplied --date option time, and with the time read from the | |
1243 | * Hardware Clock for all other operations. Apply drift correction | |
1244 | * to the Hardware Clock time for everything except --show and | |
1245 | * --predict. For --predict negate the drift correction, because we | |
1246 | * want to 'predict' a future Hardware Clock time that includes drift. | |
1247 | */ | |
336f7c5f SK |
1248 | hclocktime = ctl->predict ? t2tv(set_time) : hclocktime; |
1249 | calculate_adjustment(ctl, adjtime->drift_factor, | |
1250 | adjtime->last_adj_time, | |
1251 | adjtime->not_adjusted, | |
2794995a | 1252 | hclocktime.tv_sec, &tdrift); |
336f7c5f | 1253 | if (!ctl->show && !ctl->predict) |
2794995a | 1254 | hclocktime = time_inc(tdrift, hclocktime.tv_sec); |
336f7c5f | 1255 | if (ctl->show || ctl->get) { |
2794995a WP |
1256 | display_time(hclock_valid, |
1257 | time_inc(hclocktime, -time_diff | |
1258 | (read_time, startup_time))); | |
336f7c5f SK |
1259 | } else if (ctl->set) { |
1260 | set_hardware_clock_exact(ctl, set_time, startup_time); | |
1261 | if (!ctl->noadjfile) | |
1262 | adjust_drift_factor(ctl, adjtime, | |
2794995a WP |
1263 | time_inc(t2tv(set_time), time_diff |
1264 | (read_time, startup_time)), | |
336f7c5f SK |
1265 | hclock_valid, hclocktime); |
1266 | } else if (ctl->adjust) { | |
2794995a | 1267 | if (tdrift.tv_sec > 0 || tdrift.tv_sec < -1) |
336f7c5f SK |
1268 | do_adjustment(ctl, adjtime, hclock_valid, |
1269 | hclocktime, read_time); | |
2794995a WP |
1270 | else |
1271 | printf(_("Needed adjustment is less than one second, " | |
1272 | "so not setting clock.\n")); | |
336f7c5f | 1273 | } else if (ctl->systohc) { |
ef71b8f1 SK |
1274 | struct timeval nowtime, reftime; |
1275 | /* | |
1276 | * We can only set_hardware_clock_exact to a | |
1277 | * whole seconds time, so we set it with | |
1278 | * reference to the most recent whole | |
1279 | * seconds time. | |
1280 | */ | |
1281 | gettimeofday(&nowtime, NULL); | |
1282 | reftime.tv_sec = nowtime.tv_sec; | |
1283 | reftime.tv_usec = 0; | |
336f7c5f SK |
1284 | set_hardware_clock_exact(ctl, (time_t) reftime.tv_sec, reftime); |
1285 | if (!ctl->noadjfile) | |
1286 | adjust_drift_factor(ctl, adjtime, nowtime, | |
1287 | hclock_valid, hclocktime); | |
1288 | } else if (ctl->hctosys) { | |
1289 | rc = set_system_clock(ctl, hclock_valid, hclocktime); | |
ef71b8f1 SK |
1290 | if (rc) { |
1291 | printf(_("Unable to set system clock.\n")); | |
1292 | return rc; | |
1293 | } | |
336f7c5f SK |
1294 | } else if (ctl->systz) { |
1295 | rc = set_system_clock_timezone(ctl); | |
ef71b8f1 SK |
1296 | if (rc) { |
1297 | printf(_("Unable to set system clock.\n")); | |
1298 | return rc; | |
1299 | } | |
336f7c5f | 1300 | } else if (ctl->predict) { |
66af1c0f WP |
1301 | hclocktime = time_inc(hclocktime, (double) |
1302 | -(tdrift.tv_sec + tdrift.tv_usec / 1E6)); | |
336f7c5f | 1303 | if (ctl->debug) { |
ef71b8f1 SK |
1304 | printf(_ |
1305 | ("At %ld seconds after 1969, RTC is predicted to read %ld seconds after 1969.\n"), | |
b68e1f44 | 1306 | set_time, hclocktime.tv_sec); |
ef71b8f1 | 1307 | } |
2794995a | 1308 | display_time(TRUE, hclocktime); |
ef71b8f1 | 1309 | } |
336f7c5f SK |
1310 | if (!ctl->noadjfile) |
1311 | save_adjtime(ctl, adjtime); | |
ef71b8f1 | 1312 | return 0; |
7eda085c KZ |
1313 | } |
1314 | ||
ef71b8f1 SK |
1315 | /* |
1316 | * Get or set the Hardware Clock epoch value in the kernel, as appropriate. | |
1317 | * <getepoch>, <setepoch>, and <epoch> are hwclock invocation options. | |
1318 | * | |
1319 | * <epoch> == -1 if the user did not specify an "epoch" option. | |
1320 | */ | |
465e9973 | 1321 | #ifdef __linux__ |
390c72eb SK |
1322 | /* |
1323 | * Maintenance note: This should work on non-Alpha machines, but the | |
1324 | * evidence today (98.03.04) indicates that the kernel only keeps the epoch | |
1325 | * value on Alphas. If that is ever fixed, this function should be changed. | |
1326 | */ | |
1327 | # ifndef __alpha__ | |
7eda085c | 1328 | static void |
336f7c5f | 1329 | manipulate_epoch(const struct hwclock_control *ctl __attribute__((__unused__))) |
ef71b8f1 | 1330 | { |
111c05d3 SK |
1331 | warnx(_("The kernel keeps an epoch value for the Hardware Clock " |
1332 | "only on an Alpha machine.\nThis copy of hwclock was built for " | |
1333 | "a machine other than Alpha\n(and thus is presumably not running " | |
1334 | "on an Alpha now). No action taken.")); | |
390c72eb SK |
1335 | } |
1336 | # else | |
1337 | static void | |
336f7c5f | 1338 | manipulate_epoch(const struct hwclock_control *ctl) |
390c72eb | 1339 | { |
336f7c5f | 1340 | if (ctl->getepoch) { |
ef71b8f1 SK |
1341 | unsigned long epoch; |
1342 | ||
336f7c5f | 1343 | if (get_epoch_rtc(ctl, &epoch, 0)) |
111c05d3 SK |
1344 | warnx(_ |
1345 | ("Unable to get the epoch value from the kernel.")); | |
ef71b8f1 SK |
1346 | else |
1347 | printf(_("Kernel is assuming an epoch value of %lu\n"), | |
1348 | epoch); | |
336f7c5f SK |
1349 | } else if (ctl->setepoch) { |
1350 | if (ctl->epoch_option == 0) | |
111c05d3 SK |
1351 | warnx(_ |
1352 | ("To set the epoch value, you must use the 'epoch' " | |
1353 | "option to tell to what value to set it.")); | |
336f7c5f | 1354 | else if (ctl->testing) |
ef71b8f1 | 1355 | printf(_ |
e8c00034 | 1356 | ("Not setting the epoch to %lu - testing only.\n"), |
336f7c5f SK |
1357 | ctl->epoch_option); |
1358 | else if (set_epoch_rtc(ctl)) | |
ef71b8f1 SK |
1359 | printf(_ |
1360 | ("Unable to set the epoch value in the kernel.\n")); | |
1361 | } | |
7eda085c | 1362 | } |
390c72eb SK |
1363 | # endif /* __alpha__ */ |
1364 | #endif /* __linux__ */ | |
7eda085c | 1365 | |
ef71b8f1 SK |
1366 | static void out_version(void) |
1367 | { | |
f6277500 | 1368 | printf(UTIL_LINUX_VERSION); |
63cccae4 KZ |
1369 | } |
1370 | ||
eb63b9b8 | 1371 | /* |
ef71b8f1 SK |
1372 | * usage - Output (error and) usage information |
1373 | * | |
1374 | * This function is called both directly from main to show usage information | |
1375 | * and as fatal function from shhopt if some argument is not understood. In | |
1376 | * case of normal usage info FMT should be NULL. In that case the info is | |
1377 | * printed to stdout. If FMT is given usage will act like fprintf( stderr, | |
1378 | * fmt, ... ), show a usage information and terminate the program | |
1379 | * afterwards. | |
1380 | */ | |
336f7c5f | 1381 | static void usage(const struct hwclock_control *ctl, const char *fmt, ...) |
ef71b8f1 SK |
1382 | { |
1383 | FILE *usageto; | |
1384 | va_list ap; | |
1385 | ||
1386 | usageto = fmt ? stderr : stdout; | |
1387 | ||
db433bf7 | 1388 | fputs(USAGE_HEADER, usageto); |
49deeeac KZ |
1389 | fputs(_(" hwclock [function] [option...]\n"), usageto); |
1390 | ||
451dbcfa BS |
1391 | fputs(USAGE_SEPARATOR, usageto); |
1392 | fputs(_("Query or set the hardware clock.\n"), usageto); | |
1393 | ||
49deeeac | 1394 | fputs(_("\nFunctions:\n"), usageto); |
cc5ec693 KZ |
1395 | fputs(_(" -h, --help show this help text and exit\n" |
1396 | " -r, --show read hardware clock and print result\n" | |
ede32597 | 1397 | " --get read hardware clock and print drift corrected result\n" |
cc5ec693 KZ |
1398 | " --set set the RTC to the time given with --date\n"), usageto); |
1399 | fputs(_(" -s, --hctosys set the system time from the hardware clock\n" | |
1400 | " -w, --systohc set the hardware clock from the current system time\n" | |
1401 | " --systz set the system time based on the current timezone\n" | |
1402 | " --adjust adjust the RTC to account for systematic drift since\n" | |
c2f0a856 | 1403 | " the clock was last set or adjusted\n"), usageto); |
465e9973 | 1404 | #ifdef __linux__ |
cc5ec693 KZ |
1405 | fputs(_(" --getepoch print out the kernel's hardware clock epoch value\n" |
1406 | " --setepoch set the kernel's hardware clock epoch value to the \n" | |
1407 | " value given with --epoch\n"), usageto); | |
465e9973 | 1408 | #endif |
cc5ec693 KZ |
1409 | fputs(_(" --predict predict RTC reading at time given with --date\n" |
1410 | " -V, --version display version information and exit\n"), usageto); | |
49deeeac | 1411 | |
db433bf7 | 1412 | fputs(USAGE_OPTIONS, usageto); |
cc5ec693 KZ |
1413 | fputs(_(" -u, --utc the hardware clock is kept in UTC\n" |
1414 | " --localtime the hardware clock is kept in local time\n"), usageto); | |
465e9973 | 1415 | #ifdef __linux__ |
cc5ec693 | 1416 | fputs(_(" -f, --rtc <file> special /dev/... file to use instead of default\n"), usageto); |
465e9973 | 1417 | #endif |
49deeeac | 1418 | fprintf(usageto, _( |
cc5ec693 KZ |
1419 | " --directisa access the ISA bus directly instead of %s\n" |
1420 | " --badyear ignore RTC's year because the BIOS is broken\n" | |
1421 | " --date <time> specifies the time to which to set the hardware clock\n" | |
1422 | " --epoch <year> specifies the year which is the beginning of the\n" | |
1423 | " hardware clock's epoch value\n"), _PATH_RTC_DEV); | |
49deeeac | 1424 | fprintf(usageto, _( |
fc56c363 KZ |
1425 | " --update-drift update drift factor in %1$s (requires\n" |
1426 | " --set or --systohc)\n" | |
1427 | " --noadjfile do not access %1$s; this requires the use of\n" | |
cc5ec693 KZ |
1428 | " either --utc or --localtime\n" |
1429 | " --adjfile <file> specifies the path to the adjust file;\n" | |
fc56c363 | 1430 | " the default is %1$s\n"), _PATH_ADJTIME); |
cc5ec693 KZ |
1431 | fputs(_(" --test do not update anything, just show what would happen\n" |
1432 | " -D, --debug debugging mode\n" "\n"), usageto); | |
eb63b9b8 | 1433 | #ifdef __alpha__ |
49deeeac KZ |
1434 | fputs(_(" -J|--jensen, -A|--arc, -S|--srm, -F|--funky-toy\n" |
1435 | " tell hwclock the type of Alpha you have (see hwclock(8))\n" | |
1436 | "\n"), usageto); | |
eb63b9b8 KZ |
1437 | #endif |
1438 | ||
ef71b8f1 | 1439 | if (fmt) { |
ef71b8f1 | 1440 | va_start(ap, fmt); |
4f899788 | 1441 | vfprintf(usageto, fmt, ap); |
ef71b8f1 SK |
1442 | va_end(ap); |
1443 | } | |
9abb2685 | 1444 | |
4f899788 | 1445 | fflush(usageto); |
336f7c5f | 1446 | hwclock_exit(ctl, fmt ? EX_USAGE : EX_OK); |
eb63b9b8 KZ |
1447 | } |
1448 | ||
63cccae4 KZ |
1449 | /* |
1450 | * Returns: | |
1451 | * EX_USAGE: bad invocation | |
1452 | * EX_NOPERM: no permission | |
1453 | * EX_OSFILE: cannot open /dev/rtc or /etc/adjtime | |
1454 | * EX_IOERR: ioctl error getting or setting the time | |
1455 | * 0: OK (or not) | |
1456 | * 1: failure | |
1457 | */ | |
ef71b8f1 SK |
1458 | int main(int argc, char **argv) |
1459 | { | |
336f7c5f | 1460 | struct hwclock_control ctl = { 0 }; |
63cccae4 | 1461 | struct timeval startup_time; |
336f7c5f | 1462 | struct adjtime adjtime = { 0 }; |
ef71b8f1 SK |
1463 | /* |
1464 | * The time we started up, in seconds into the epoch, including | |
1465 | * fractions. | |
1466 | */ | |
1467 | time_t set_time = 0; /* Time to which user said to set Hardware Clock */ | |
63cccae4 | 1468 | int rc, c; |
7eda085c | 1469 | |
dade002a KZ |
1470 | /* Long only options. */ |
1471 | enum { | |
1472 | OPT_ADJFILE = CHAR_MAX + 1, | |
1473 | OPT_BADYEAR, | |
1474 | OPT_DATE, | |
1475 | OPT_DIRECTISA, | |
1476 | OPT_EPOCH, | |
2794995a | 1477 | OPT_GET, |
dade002a KZ |
1478 | OPT_GETEPOCH, |
1479 | OPT_LOCALTIME, | |
1480 | OPT_NOADJFILE, | |
1481 | OPT_PREDICT_HC, | |
1482 | OPT_SET, | |
1483 | OPT_SETEPOCH, | |
1484 | OPT_SYSTZ, | |
f276d71a WP |
1485 | OPT_TEST, |
1486 | OPT_UPDATE | |
dade002a | 1487 | }; |
33ed2d02 SK |
1488 | |
1489 | static const struct option longopts[] = { | |
1490 | {"adjust", 0, 0, 'a'}, | |
1491 | {"help", 0, 0, 'h'}, | |
1492 | {"show", 0, 0, 'r'}, | |
1493 | {"hctosys", 0, 0, 's'}, | |
1494 | {"utc", 0, 0, 'u'}, | |
1495 | {"version", 0, 0, 'v'}, | |
1496 | {"systohc", 0, 0, 'w'}, | |
1497 | {"debug", 0, 0, 'D'}, | |
1498 | #ifdef __alpha__ | |
1499 | {"ARC", 0, 0, 'A'}, | |
1500 | {"arc", 0, 0, 'A'}, | |
1501 | {"Jensen", 0, 0, 'J'}, | |
1502 | {"jensen", 0, 0, 'J'}, | |
1503 | {"SRM", 0, 0, 'S'}, | |
1504 | {"srm", 0, 0, 'S'}, | |
1505 | {"funky-toy", 0, 0, 'F'}, | |
1506 | #endif | |
1507 | {"set", 0, 0, OPT_SET}, | |
1508 | #ifdef __linux__ | |
1509 | {"getepoch", 0, 0, OPT_GETEPOCH}, | |
1510 | {"setepoch", 0, 0, OPT_SETEPOCH}, | |
1511 | #endif | |
1512 | {"noadjfile", 0, 0, OPT_NOADJFILE}, | |
1513 | {"localtime", 0, 0, OPT_LOCALTIME}, | |
1514 | {"badyear", 0, 0, OPT_BADYEAR}, | |
1515 | {"directisa", 0, 0, OPT_DIRECTISA}, | |
1516 | {"test", 0, 0, OPT_TEST}, | |
1517 | {"date", 1, 0, OPT_DATE}, | |
1518 | {"epoch", 1, 0, OPT_EPOCH}, | |
1519 | #ifdef __linux__ | |
1520 | {"rtc", 1, 0, 'f'}, | |
1521 | #endif | |
1522 | {"adjfile", 1, 0, OPT_ADJFILE}, | |
1523 | {"systz", 0, 0, OPT_SYSTZ}, | |
1524 | {"predict-hc", 0, 0, OPT_PREDICT_HC}, | |
2794995a | 1525 | {"get", 0, 0, OPT_GET}, |
f276d71a | 1526 | {"update-drift",0, 0, OPT_UPDATE}, |
33ed2d02 SK |
1527 | {NULL, 0, NULL, 0} |
1528 | }; | |
1529 | ||
a7349ee3 | 1530 | static const ul_excl_t excl[] = { /* rows and cols in ASCII order */ |
dade002a | 1531 | { 'a','r','s','w', |
2794995a WP |
1532 | OPT_GET, OPT_GETEPOCH, OPT_PREDICT_HC, |
1533 | OPT_SET, OPT_SETEPOCH, OPT_SYSTZ }, | |
dade002a KZ |
1534 | { 'u', OPT_LOCALTIME}, |
1535 | { OPT_ADJFILE, OPT_NOADJFILE }, | |
f276d71a | 1536 | { OPT_NOADJFILE, OPT_UPDATE }, |
dade002a KZ |
1537 | { 0 } |
1538 | }; | |
1539 | int excl_st[ARRAY_SIZE(excl)] = UL_EXCL_STATUS_INIT; | |
1540 | ||
63cccae4 KZ |
1541 | /* Remember what time we were invoked */ |
1542 | gettimeofday(&startup_time, NULL); | |
7eda085c | 1543 | |
88058a71 KZ |
1544 | #ifdef HAVE_LIBAUDIT |
1545 | hwaudit_fd = audit_open(); | |
1546 | if (hwaudit_fd < 0 && !(errno == EINVAL || errno == EPROTONOSUPPORT || | |
1547 | errno == EAFNOSUPPORT)) { | |
ef71b8f1 SK |
1548 | /* |
1549 | * You get these error codes only when the kernel doesn't | |
1550 | * have audit compiled in. | |
1551 | */ | |
111c05d3 | 1552 | warnx(_("Unable to connect to audit system")); |
88058a71 KZ |
1553 | return EX_NOPERM; |
1554 | } | |
1555 | #endif | |
63cccae4 | 1556 | setlocale(LC_ALL, ""); |
66ee8158 | 1557 | #ifdef LC_NUMERIC |
ef71b8f1 SK |
1558 | /* |
1559 | * We need LC_CTYPE and LC_TIME and LC_MESSAGES, but must avoid | |
1560 | * LC_NUMERIC since it gives problems when we write to /etc/adjtime. | |
1561 | * - gqueri@mail.dotcom.fr | |
1562 | */ | |
63cccae4 | 1563 | setlocale(LC_NUMERIC, "C"); |
66ee8158 | 1564 | #endif |
63cccae4 KZ |
1565 | bindtextdomain(PACKAGE, LOCALEDIR); |
1566 | textdomain(PACKAGE); | |
db116df7 | 1567 | atexit(close_stdout); |
63cccae4 | 1568 | |
dade002a | 1569 | while ((c = getopt_long(argc, argv, |
92931ab2 | 1570 | "?hvVDarsuwAJSFf:", longopts, NULL)) != -1) { |
dade002a KZ |
1571 | |
1572 | err_exclusive_options(c, longopts, excl, excl_st); | |
1573 | ||
63cccae4 KZ |
1574 | switch (c) { |
1575 | case 'D': | |
336f7c5f | 1576 | ctl.debug++; |
63cccae4 KZ |
1577 | break; |
1578 | case 'a': | |
336f7c5f | 1579 | ctl.adjust = 1; |
63cccae4 KZ |
1580 | break; |
1581 | case 'r': | |
336f7c5f | 1582 | ctl.show = 1; |
63cccae4 KZ |
1583 | break; |
1584 | case 's': | |
336f7c5f | 1585 | ctl.hctosys = 1; |
63cccae4 KZ |
1586 | break; |
1587 | case 'u': | |
336f7c5f | 1588 | ctl.utc = 1; |
63cccae4 KZ |
1589 | break; |
1590 | case 'w': | |
336f7c5f | 1591 | ctl.systohc = 1; |
63cccae4 KZ |
1592 | break; |
1593 | #ifdef __alpha__ | |
1594 | case 'A': | |
336f7c5f | 1595 | ctl.ARCconsole = 1; |
63cccae4 KZ |
1596 | break; |
1597 | case 'J': | |
336f7c5f | 1598 | ctl.Jensen = 1; |
63cccae4 KZ |
1599 | break; |
1600 | case 'S': | |
336f7c5f | 1601 | ctl.SRM = 1; |
63cccae4 KZ |
1602 | break; |
1603 | case 'F': | |
336f7c5f | 1604 | ctl.funky_toy = 1; |
63cccae4 KZ |
1605 | break; |
1606 | #endif | |
33ed2d02 | 1607 | case OPT_SET: |
336f7c5f | 1608 | ctl.set = 1; |
63cccae4 | 1609 | break; |
465e9973 | 1610 | #ifdef __linux__ |
33ed2d02 | 1611 | case OPT_GETEPOCH: |
336f7c5f | 1612 | ctl.getepoch = 1; |
63cccae4 | 1613 | break; |
33ed2d02 | 1614 | case OPT_SETEPOCH: |
336f7c5f | 1615 | ctl.setepoch = 1; |
63cccae4 | 1616 | break; |
465e9973 | 1617 | #endif |
33ed2d02 | 1618 | case OPT_NOADJFILE: |
336f7c5f | 1619 | ctl.noadjfile = 1; |
63cccae4 | 1620 | break; |
33ed2d02 | 1621 | case OPT_LOCALTIME: |
336f7c5f | 1622 | ctl.local_opt = 1; /* --localtime */ |
63cccae4 | 1623 | break; |
33ed2d02 | 1624 | case OPT_BADYEAR: |
336f7c5f | 1625 | ctl.badyear = 1; |
63cccae4 | 1626 | break; |
33ed2d02 | 1627 | case OPT_DIRECTISA: |
336f7c5f | 1628 | ctl.directisa = 1; |
63cccae4 | 1629 | break; |
33ed2d02 | 1630 | case OPT_TEST: |
336f7c5f | 1631 | ctl.testing = 1; /* --test */ |
63cccae4 | 1632 | break; |
33ed2d02 | 1633 | case OPT_DATE: |
336f7c5f | 1634 | ctl.date_opt = optarg; /* --date */ |
63cccae4 | 1635 | break; |
33ed2d02 | 1636 | case OPT_EPOCH: |
336f7c5f | 1637 | ctl.epoch_option = /* --epoch */ |
99c95585 | 1638 | strtoul_or_err(optarg, _("invalid epoch argument")); |
63cccae4 | 1639 | break; |
33ed2d02 | 1640 | case OPT_ADJFILE: |
336f7c5f | 1641 | ctl.adj_file_name = optarg; /* --adjfile */ |
da82f6fe | 1642 | break; |
33ed2d02 | 1643 | case OPT_SYSTZ: |
336f7c5f | 1644 | ctl.systz = 1; /* --systz */ |
88a3372e | 1645 | break; |
33ed2d02 | 1646 | case OPT_PREDICT_HC: |
336f7c5f | 1647 | ctl.predict = 1; /* --predict-hc */ |
2e5627fa | 1648 | break; |
2794995a | 1649 | case OPT_GET: |
336f7c5f | 1650 | ctl.get = 1; /* --get */ |
2794995a | 1651 | break; |
f276d71a | 1652 | case OPT_UPDATE: |
336f7c5f | 1653 | ctl.update = 1; /* --update-drift */ |
f276d71a | 1654 | break; |
465e9973 | 1655 | #ifdef __linux__ |
88681c5f | 1656 | case 'f': |
336f7c5f | 1657 | ctl.rtc_dev_name = optarg; /* --rtc */ |
88681c5f | 1658 | break; |
465e9973 | 1659 | #endif |
ef71b8f1 | 1660 | case 'v': /* --version */ |
63cccae4 KZ |
1661 | case 'V': |
1662 | out_version(); | |
1663 | return 0; | |
ef71b8f1 | 1664 | case 'h': /* --help */ |
336f7c5f | 1665 | case '?': |
677ec86c | 1666 | default: |
336f7c5f | 1667 | usage(&ctl, NULL); |
63cccae4 KZ |
1668 | } |
1669 | } | |
7eda085c | 1670 | |
63cccae4 KZ |
1671 | argc -= optind; |
1672 | argv += optind; | |
eb63b9b8 | 1673 | |
88058a71 | 1674 | #ifdef HAVE_LIBAUDIT |
336f7c5f SK |
1675 | if (!ctl.testing) { |
1676 | if (ctl.adjust || ctl.hctosys || ctl.systohc || | |
1677 | ctl.set || ctl.setepoch) { | |
1678 | ctl.hwaudit_on = 1; | |
88058a71 KZ |
1679 | } |
1680 | } | |
1681 | #endif | |
63cccae4 | 1682 | if (argc > 0) { |
336f7c5f | 1683 | usage(&ctl, _("%s takes no non-option arguments. " |
111c05d3 SK |
1684 | "You supplied %d.\n"), program_invocation_short_name, |
1685 | argc); | |
63cccae4 | 1686 | } |
7eda085c | 1687 | |
336f7c5f SK |
1688 | if (!ctl.adj_file_name) |
1689 | ctl.adj_file_name = _PATH_ADJTIME; | |
da82f6fe | 1690 | |
336f7c5f | 1691 | if (ctl.noadjfile && !ctl.utc && !ctl.local_opt) { |
111c05d3 SK |
1692 | warnx(_("With --noadjfile, you must specify " |
1693 | "either --utc or --localtime")); | |
336f7c5f | 1694 | hwclock_exit(&ctl, EX_USAGE); |
63cccae4 | 1695 | } |
7eda085c | 1696 | #ifdef __alpha__ |
336f7c5f SK |
1697 | set_cmos_epoch(&ctl); |
1698 | set_cmos_access(&ctl); | |
7eda085c KZ |
1699 | #endif |
1700 | ||
336f7c5f SK |
1701 | if (ctl.set || ctl.predict) { |
1702 | rc = interpret_date_string(&ctl, &set_time); | |
63cccae4 KZ |
1703 | /* (time-consuming) */ |
1704 | if (rc != 0) { | |
111c05d3 SK |
1705 | warnx(_("No usable set-to time. " |
1706 | "Cannot set clock.")); | |
336f7c5f | 1707 | hwclock_exit(&ctl, EX_USAGE); |
63cccae4 KZ |
1708 | } |
1709 | } | |
7eda085c | 1710 | |
336f7c5f SK |
1711 | if (!(ctl.show | ctl.set | ctl.systohc | ctl.hctosys | |
1712 | ctl.systz | ctl.adjust | ctl.getepoch | ctl.setepoch | | |
92931ab2 | 1713 | ctl.predict | ctl.get)) |
336f7c5f | 1714 | ctl.show = 1; /* default to show */ |
63cccae4 | 1715 | |
465e9973 | 1716 | #ifdef __linux__ |
336f7c5f SK |
1717 | if (ctl.getepoch || ctl.setepoch) { |
1718 | manipulate_epoch(&ctl); | |
1719 | hwclock_exit(&ctl, EX_OK); | |
63cccae4 | 1720 | } |
465e9973 | 1721 | #endif |
63cccae4 | 1722 | |
336f7c5f | 1723 | if (ctl.debug) |
63cccae4 | 1724 | out_version(); |
111c05d3 | 1725 | |
8f729d60 | 1726 | if (!ctl.systz && !ctl.predict) |
336f7c5f | 1727 | determine_clock_access_method(&ctl); |
63cccae4 | 1728 | |
336f7c5f SK |
1729 | if (!ctl.noadjfile && !(ctl.systz && (ctl.utc || ctl.local_opt))) { |
1730 | if ((rc = read_adjtime(&ctl, &adjtime)) != 0) | |
1731 | hwclock_exit(&ctl, rc); | |
1732 | } else | |
1733 | /* Avoid writing adjtime file if we don't have to. */ | |
1734 | adjtime.dirty = FALSE; | |
1735 | ctl.universal = hw_clock_is_utc(&ctl, adjtime); | |
92931ab2 | 1736 | rc = manipulate_clock(&ctl, set_time, startup_time, &adjtime); |
336f7c5f | 1737 | hwclock_exit(&ctl, rc); |
ef71b8f1 | 1738 | return rc; /* Not reached */ |
7eda085c KZ |
1739 | } |
1740 | ||
336f7c5f SK |
1741 | void __attribute__((__noreturn__)) |
1742 | hwclock_exit(const struct hwclock_control *ctl | |
1743 | #ifndef HAVE_LIBAUDIT | |
1744 | __attribute__((__unused__)) | |
1745 | #endif | |
1746 | , int status) | |
88058a71 | 1747 | { |
48e7ed5e | 1748 | #ifdef HAVE_LIBAUDIT |
336f7c5f | 1749 | if (ctl->hwaudit_on) { |
88058a71 | 1750 | audit_log_user_message(hwaudit_fd, AUDIT_USYS_CONFIG, |
fbed7e09 | 1751 | "op=change-system-time", NULL, NULL, NULL, |
ef71b8f1 | 1752 | status ? 0 : 1); |
88058a71 KZ |
1753 | close(hwaudit_fd); |
1754 | } | |
48e7ed5e | 1755 | #endif |
88058a71 KZ |
1756 | exit(status); |
1757 | } | |
88058a71 | 1758 | |
ef71b8f1 SK |
1759 | /* |
1760 | * History of this program: | |
1761 | * | |
1762 | * 98.08.12 BJH Version 2.4 | |
1763 | * | |
1764 | * Don't use century byte from Hardware Clock. Add comments telling why. | |
1765 | * | |
1766 | * 98.06.20 BJH Version 2.3. | |
1767 | * | |
1768 | * Make --hctosys set the kernel timezone from TZ environment variable | |
1769 | * and/or /usr/lib/zoneinfo. From Klaus Ripke (klaus@ripke.com). | |
1770 | * | |
1771 | * 98.03.05 BJH. Version 2.2. | |
1772 | * | |
1773 | * Add --getepoch and --setepoch. | |
1774 | * | |
1775 | * Fix some word length things so it works on Alpha. | |
1776 | * | |
1777 | * Make it work when /dev/rtc doesn't have the interrupt functions. In this | |
1778 | * case, busywait for the top of a second instead of blocking and waiting | |
1779 | * for the update complete interrupt. | |
1780 | * | |
1781 | * Fix a bunch of bugs too numerous to mention. | |
1782 | * | |
1783 | * 97.06.01: BJH. Version 2.1. Read and write the century byte (Byte 50) of | |
1784 | * the ISA Hardware Clock when using direct ISA I/O. Problem discovered by | |
1785 | * job (jei@iclnl.icl.nl). | |
1786 | * | |
1787 | * Use the rtc clock access method in preference to the KDGHWCLK method. | |
1788 | * Problem discovered by Andreas Schwab <schwab@LS5.informatik.uni-dortmund.de>. | |
1789 | * | |
1790 | * November 1996: Version 2.0.1. Modifications by Nicolai Langfeldt | |
1791 | * (janl@math.uio.no) to make it compile on linux 1.2 machines as well as | |
1792 | * more recent versions of the kernel. Introduced the NO_CLOCK access method | |
455fe9a0 | 1793 | * and wrote feature test code to detect absence of rtc headers. |
ef71b8f1 SK |
1794 | * |
1795 | *************************************************************************** | |
1796 | * Maintenance notes | |
1797 | * | |
1798 | * To compile this, you must use GNU compiler optimization (-O option) in | |
1799 | * order to make the "extern inline" functions from asm/io.h (inb(), etc.) | |
1800 | * compile. If you don't optimize, which means the compiler will generate no | |
1801 | * inline functions, the references to these functions in this program will | |
1802 | * be compiled as external references. Since you probably won't be linking | |
1803 | * with any functions by these names, you will have unresolved external | |
1804 | * references when you link. | |
1805 | * | |
ef71b8f1 SK |
1806 | * Here's some info on how we must deal with the time that elapses while |
1807 | * this program runs: There are two major delays as we run: | |
1808 | * | |
1809 | * 1) Waiting up to 1 second for a transition of the Hardware Clock so | |
1810 | * we are synchronized to the Hardware Clock. | |
1811 | * 2) Running the "date" program to interpret the value of our --date | |
1812 | * option. | |
1813 | * | |
1814 | * Reading the /etc/adjtime file is the next biggest source of delay and | |
1815 | * uncertainty. | |
1816 | * | |
1817 | * The user wants to know what time it was at the moment he invoked us, not | |
1818 | * some arbitrary time later. And in setting the clock, he is giving us the | |
1819 | * time at the moment we are invoked, so if we set the clock some time | |
1820 | * later, we have to add some time to that. | |
1821 | * | |
1822 | * So we check the system time as soon as we start up, then run "date" and | |
1823 | * do file I/O if necessary, then wait to synchronize with a Hardware Clock | |
1824 | * edge, then check the system time again to see how much time we spent. We | |
1825 | * immediately read the clock then and (if appropriate) report that time, | |
1826 | * and additionally, the delay we measured. | |
1827 | * | |
1828 | * If we're setting the clock to a time given by the user, we wait some more | |
1829 | * so that the total delay is an integral number of seconds, then set the | |
1830 | * Hardware Clock to the time the user requested plus that integral number | |
1831 | * of seconds. N.B. The Hardware Clock can only be set in integral seconds. | |
1832 | * | |
1833 | * If we're setting the clock to the system clock value, we wait for the | |
1834 | * system clock to reach the top of a second, and then set the Hardware | |
1835 | * Clock to the system clock's value. | |
1836 | * | |
1837 | * Here's an interesting point about setting the Hardware Clock: On my | |
1838 | * machine, when you set it, it sets to that precise time. But one can | |
1839 | * imagine another clock whose update oscillator marches on a steady one | |
1840 | * second period, so updating the clock between any two oscillator ticks is | |
1841 | * the same as updating it right at the earlier tick. To avoid any | |
1842 | * complications that might cause, we set the clock as soon as possible | |
1843 | * after an oscillator tick. | |
1844 | * | |
1845 | * About synchronizing to the Hardware Clock when reading the time: The | |
1846 | * precision of the Hardware Clock counters themselves is one second. You | |
1847 | * can't read the counters and find out that is 12:01:02.5. But if you | |
1848 | * consider the location in time of the counter's ticks as part of its | |
1849 | * value, then its precision is as infinite as time is continuous! What I'm | |
1850 | * saying is this: To find out the _exact_ time in the hardware clock, we | |
1851 | * wait until the next clock tick (the next time the second counter changes) | |
1852 | * and measure how long we had to wait. We then read the value of the clock | |
1853 | * counters and subtract the wait time and we know precisely what time it | |
1854 | * was when we set out to query the time. | |
1855 | * | |
1856 | * hwclock uses this method, and considers the Hardware Clock to have | |
1857 | * infinite precision. | |
ef71b8f1 | 1858 | */ |