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ngx_times.c
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1 
2 /*
3  * Copyright (C) Igor Sysoev
4  * Copyright (C) Nginx, Inc.
5  */
6 
7 
8 #include <ngx_config.h>
9 #include <ngx_core.h>
10 
11 
12 /*
13  * The time may be updated by signal handler or by several threads.
14  * The time update operations are rare and require to hold the ngx_time_lock.
15  * The time read operations are frequent, so they are lock-free and get time
16  * values and strings from the current slot. Thus thread may get the corrupted
17  * values only if it is preempted while copying and then it is not scheduled
18  * to run more than NGX_TIME_SLOTS seconds.
19  */
20 
21 #define NGX_TIME_SLOTS 64
22 
23 static ngx_uint_t slot;
24 static ngx_atomic_t ngx_time_lock;
25 
26 volatile ngx_msec_t ngx_current_msec;
27 volatile ngx_time_t *ngx_cached_time;
28 volatile ngx_str_t ngx_cached_err_log_time;
29 volatile ngx_str_t ngx_cached_http_time;
30 volatile ngx_str_t ngx_cached_http_log_time;
31 volatile ngx_str_t ngx_cached_http_log_iso8601;
32 
33 #if !(NGX_WIN32)
34 
35 /*
36  * localtime() and localtime_r() are not Async-Signal-Safe functions, therefore,
37  * they must not be called by a signal handler, so we use the cached
38  * GMT offset value. Fortunately the value is changed only two times a year.
39  */
40 
41 static ngx_int_t cached_gmtoff;
42 #endif
43 
44 static ngx_time_t cached_time[NGX_TIME_SLOTS];
45 static u_char cached_err_log_time[NGX_TIME_SLOTS]
46  [sizeof("1970/09/28 12:00:00")];
47 static u_char cached_http_time[NGX_TIME_SLOTS]
48  [sizeof("Mon, 28 Sep 1970 06:00:00 GMT")];
49 static u_char cached_http_log_time[NGX_TIME_SLOTS]
50  [sizeof("28/Sep/1970:12:00:00 +0600")];
51 static u_char cached_http_log_iso8601[NGX_TIME_SLOTS]
52  [sizeof("1970-09-28T12:00:00+06:00")];
53 
54 
55 static char *week[] = { "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat" };
56 static char *months[] = { "Jan", "Feb", "Mar", "Apr", "May", "Jun",
57  "Jul", "Aug", "Sep", "Oct", "Nov", "Dec" };
58 
59 void
60 ngx_time_init(void)
61 {
62  ngx_cached_err_log_time.len = sizeof("1970/09/28 12:00:00") - 1;
63  ngx_cached_http_time.len = sizeof("Mon, 28 Sep 1970 06:00:00 GMT") - 1;
64  ngx_cached_http_log_time.len = sizeof("28/Sep/1970:12:00:00 +0600") - 1;
65  ngx_cached_http_log_iso8601.len = sizeof("1970-09-28T12:00:00+06:00") - 1;
66 
67  ngx_cached_time = &cached_time[0];
68 
69  ngx_time_update();
70 }
71 
72 
73 void
74 ngx_time_update(void)
75 {
76  u_char *p0, *p1, *p2, *p3;
77  ngx_tm_t tm, gmt;
78  time_t sec;
79  ngx_uint_t msec;
80  ngx_time_t *tp;
81  struct timeval tv;
82 
83  if (!ngx_trylock(&ngx_time_lock)) {
84  return;
85  }
86 
87  ngx_gettimeofday(&tv);
88 
89  sec = tv.tv_sec;
90  msec = tv.tv_usec / 1000;
91 
92  ngx_current_msec = (ngx_msec_t) sec * 1000 + msec;
93 
94  tp = &cached_time[slot];
95 
96  if (tp->sec == sec) {
97  tp->msec = msec;
98  ngx_unlock(&ngx_time_lock);
99  return;
100  }
101 
102  if (slot == NGX_TIME_SLOTS - 1) {
103  slot = 0;
104  } else {
105  slot++;
106  }
107 
108  tp = &cached_time[slot];
109 
110  tp->sec = sec;
111  tp->msec = msec;
112 
113  ngx_gmtime(sec, &gmt);
114 
115 
116  p0 = &cached_http_time[slot][0];
117 
118  (void) ngx_sprintf(p0, "%s, %02d %s %4d %02d:%02d:%02d GMT",
119  week[gmt.ngx_tm_wday], gmt.ngx_tm_mday,
120  months[gmt.ngx_tm_mon - 1], gmt.ngx_tm_year,
121  gmt.ngx_tm_hour, gmt.ngx_tm_min, gmt.ngx_tm_sec);
122 
123 #if (NGX_HAVE_GETTIMEZONE)
124 
125  tp->gmtoff = ngx_gettimezone();
126  ngx_gmtime(sec + tp->gmtoff * 60, &tm);
127 
128 #elif (NGX_HAVE_GMTOFF)
129 
130  ngx_localtime(sec, &tm);
131  cached_gmtoff = (ngx_int_t) (tm.ngx_tm_gmtoff / 60);
132  tp->gmtoff = cached_gmtoff;
133 
134 #else
135 
136  ngx_localtime(sec, &tm);
137  cached_gmtoff = ngx_timezone(tm.ngx_tm_isdst);
138  tp->gmtoff = cached_gmtoff;
139 
140 #endif
141 
142 
143  p1 = &cached_err_log_time[slot][0];
144 
145  (void) ngx_sprintf(p1, "%4d/%02d/%02d %02d:%02d:%02d",
146  tm.ngx_tm_year, tm.ngx_tm_mon,
147  tm.ngx_tm_mday, tm.ngx_tm_hour,
148  tm.ngx_tm_min, tm.ngx_tm_sec);
149 
150 
151  p2 = &cached_http_log_time[slot][0];
152 
153  (void) ngx_sprintf(p2, "%02d/%s/%d:%02d:%02d:%02d %c%02d%02d",
154  tm.ngx_tm_mday, months[tm.ngx_tm_mon - 1],
155  tm.ngx_tm_year, tm.ngx_tm_hour,
156  tm.ngx_tm_min, tm.ngx_tm_sec,
157  tp->gmtoff < 0 ? '-' : '+',
158  ngx_abs(tp->gmtoff / 60), ngx_abs(tp->gmtoff % 60));
159 
160  p3 = &cached_http_log_iso8601[slot][0];
161 
162  (void) ngx_sprintf(p3, "%4d-%02d-%02dT%02d:%02d:%02d%c%02d:%02d",
163  tm.ngx_tm_year, tm.ngx_tm_mon,
164  tm.ngx_tm_mday, tm.ngx_tm_hour,
165  tm.ngx_tm_min, tm.ngx_tm_sec,
166  tp->gmtoff < 0 ? '-' : '+',
167  ngx_abs(tp->gmtoff / 60), ngx_abs(tp->gmtoff % 60));
168 
169 
170  ngx_memory_barrier();
171 
172  ngx_cached_time = tp;
173  ngx_cached_http_time.data = p0;
174  ngx_cached_err_log_time.data = p1;
175  ngx_cached_http_log_time.data = p2;
176  ngx_cached_http_log_iso8601.data = p3;
177 
178  ngx_unlock(&ngx_time_lock);
179 }
180 
181 
182 #if !(NGX_WIN32)
183 
184 void
185 ngx_time_sigsafe_update(void)
186 {
187  u_char *p;
188  ngx_tm_t tm;
189  time_t sec;
190  ngx_time_t *tp;
191  struct timeval tv;
192 
193  if (!ngx_trylock(&ngx_time_lock)) {
194  return;
195  }
196 
197  ngx_gettimeofday(&tv);
198 
199  sec = tv.tv_sec;
200 
201  tp = &cached_time[slot];
202 
203  if (tp->sec == sec) {
204  ngx_unlock(&ngx_time_lock);
205  return;
206  }
207 
208  if (slot == NGX_TIME_SLOTS - 1) {
209  slot = 0;
210  } else {
211  slot++;
212  }
213 
214  tp = &cached_time[slot];
215 
216  tp->sec = 0;
217 
218  ngx_gmtime(sec + cached_gmtoff * 60, &tm);
219 
220  p = &cached_err_log_time[slot][0];
221 
222  (void) ngx_sprintf(p, "%4d/%02d/%02d %02d:%02d:%02d",
223  tm.ngx_tm_year, tm.ngx_tm_mon,
224  tm.ngx_tm_mday, tm.ngx_tm_hour,
225  tm.ngx_tm_min, tm.ngx_tm_sec);
226 
227  ngx_memory_barrier();
228 
229  ngx_cached_err_log_time.data = p;
230 
231  ngx_unlock(&ngx_time_lock);
232 }
233 
234 #endif
235 
236 
237 u_char *
238 ngx_http_time(u_char *buf, time_t t)
239 {
240  ngx_tm_t tm;
241 
242  ngx_gmtime(t, &tm);
243 
244  return ngx_sprintf(buf, "%s, %02d %s %4d %02d:%02d:%02d GMT",
245  week[tm.ngx_tm_wday],
246  tm.ngx_tm_mday,
247  months[tm.ngx_tm_mon - 1],
248  tm.ngx_tm_year,
249  tm.ngx_tm_hour,
250  tm.ngx_tm_min,
251  tm.ngx_tm_sec);
252 }
253 
254 
255 u_char *
256 ngx_http_cookie_time(u_char *buf, time_t t)
257 {
258  ngx_tm_t tm;
259 
260  ngx_gmtime(t, &tm);
261 
262  /*
263  * Netscape 3.x does not understand 4-digit years at all and
264  * 2-digit years more than "37"
265  */
266 
267  return ngx_sprintf(buf,
268  (tm.ngx_tm_year > 2037) ?
269  "%s, %02d-%s-%d %02d:%02d:%02d GMT":
270  "%s, %02d-%s-%02d %02d:%02d:%02d GMT",
271  week[tm.ngx_tm_wday],
272  tm.ngx_tm_mday,
273  months[tm.ngx_tm_mon - 1],
274  (tm.ngx_tm_year > 2037) ? tm.ngx_tm_year:
275  tm.ngx_tm_year % 100,
276  tm.ngx_tm_hour,
277  tm.ngx_tm_min,
278  tm.ngx_tm_sec);
279 }
280 
281 
282 void
283 ngx_gmtime(time_t t, ngx_tm_t *tp)
284 {
285  ngx_int_t yday;
286  ngx_uint_t n, sec, min, hour, mday, mon, year, wday, days, leap;
287 
288  /* the calculation is valid for positive time_t only */
289 
290  n = (ngx_uint_t) t;
291 
292  days = n / 86400;
293 
294  /* January 1, 1970 was Thursday */
295 
296  wday = (4 + days) % 7;
297 
298  n %= 86400;
299  hour = n / 3600;
300  n %= 3600;
301  min = n / 60;
302  sec = n % 60;
303 
304  /*
305  * the algorithm based on Gauss' formula,
306  * see src/http/ngx_http_parse_time.c
307  */
308 
309  /* days since March 1, 1 BC */
310  days = days - (31 + 28) + 719527;
311 
312  /*
313  * The "days" should be adjusted to 1 only, however, some March 1st's go
314  * to previous year, so we adjust them to 2. This causes also shift of the
315  * last February days to next year, but we catch the case when "yday"
316  * becomes negative.
317  */
318 
319  year = (days + 2) * 400 / (365 * 400 + 100 - 4 + 1);
320 
321  yday = days - (365 * year + year / 4 - year / 100 + year / 400);
322 
323  if (yday < 0) {
324  leap = (year % 4 == 0) && (year % 100 || (year % 400 == 0));
325  yday = 365 + leap + yday;
326  year--;
327  }
328 
329  /*
330  * The empirical formula that maps "yday" to month.
331  * There are at least 10 variants, some of them are:
332  * mon = (yday + 31) * 15 / 459
333  * mon = (yday + 31) * 17 / 520
334  * mon = (yday + 31) * 20 / 612
335  */
336 
337  mon = (yday + 31) * 10 / 306;
338 
339  /* the Gauss' formula that evaluates days before the month */
340 
341  mday = yday - (367 * mon / 12 - 30) + 1;
342 
343  if (yday >= 306) {
344 
345  year++;
346  mon -= 10;
347 
348  /*
349  * there is no "yday" in Win32 SYSTEMTIME
350  *
351  * yday -= 306;
352  */
353 
354  } else {
355 
356  mon += 2;
357 
358  /*
359  * there is no "yday" in Win32 SYSTEMTIME
360  *
361  * yday += 31 + 28 + leap;
362  */
363  }
364 
365  tp->ngx_tm_sec = (ngx_tm_sec_t) sec;
366  tp->ngx_tm_min = (ngx_tm_min_t) min;
367  tp->ngx_tm_hour = (ngx_tm_hour_t) hour;
368  tp->ngx_tm_mday = (ngx_tm_mday_t) mday;
369  tp->ngx_tm_mon = (ngx_tm_mon_t) mon;
370  tp->ngx_tm_year = (ngx_tm_year_t) year;
371  tp->ngx_tm_wday = (ngx_tm_wday_t) wday;
372 }
373 
374 
375 time_t
376 ngx_next_time(time_t when)
377 {
378  time_t now, next;
379  struct tm tm;
380 
381  now = ngx_time();
382 
383  ngx_libc_localtime(now, &tm);
384 
385  tm.tm_hour = (int) (when / 3600);
386  when %= 3600;
387  tm.tm_min = (int) (when / 60);
388  tm.tm_sec = (int) (when % 60);
389 
390  next = mktime(&tm);
391 
392  if (next == -1) {
393  return -1;
394  }
395 
396  if (next - now > 0) {
397  return next;
398  }
399 
400  tm.tm_mday++;
401 
402  /* mktime() should normalize a date (Jan 32, etc) */
403 
404  next = mktime(&tm);
405 
406  if (next != -1) {
407  return next;
408  }
409 
410  return -1;
411 }
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