src/core/ngx_times.c

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