1 2 /* 3 * Copyright (C) Igor Sysoev 4 * Copyright (C) NGINX, Inc. 5 */ 6 7 #ifndef _NXT_UNIX_TIME_H_INCLUDED_ 8 #define _NXT_UNIX_TIME_H_INCLUDED_ 9 10 11 typedef uint64_t nxt_nsec_t; 12 typedef int64_t nxt_nsec_int_t; 13 #define NXT_INFINITE_NSEC ((nxt_nsec_t) -1) 14 15 16 typedef struct { 17 nxt_time_t sec; 18 nxt_uint_t nsec; 19 } nxt_realtime_t; 20 21 22 /* 23 * nxt_monotonic_time_t includes nxt_realtime_t to eliminate 24 * surplus gettimeofday() call on platform without monotonic time. 25 */ 26 27 typedef struct { 28 nxt_realtime_t realtime; 29 nxt_nsec_t monotonic; 30 nxt_nsec_t update; 31 32 #if !(NXT_HAVE_CLOCK_MONOTONIC || NXT_SOLARIS || NXT_HPUX || NXT_MACOSX) 33 nxt_nsec_t previous; 34 #endif 35 } nxt_monotonic_time_t; 36 37 38 NXT_EXPORT void nxt_realtime(nxt_realtime_t *now); 39 NXT_EXPORT void nxt_monotonic_time(nxt_monotonic_time_t *now); 40 NXT_EXPORT void nxt_localtime(nxt_time_t s, struct tm *tm); 41 NXT_EXPORT void nxt_timezone_update(void); 42 43 /* 44 * Both localtime() and localtime_r() are not Async-Signal-Safe, therefore, 45 * they can not be used in signal handlers. Since Daylight Saving Time (DST) 46 * state changes no more than twice a year, a simple workaround is to use 47 * a previously cached GMT offset value and nxt_gmtime(): 48 * 49 * nxt_gmtime(GMT seconds + GMT offset, tm); 50 * 51 * GMT offset with account of current DST state can be obtained only 52 * using localtime()'s struct tm because: 53 * 54 * 1) gettimeofday() does not return GMT offset at almost all platforms. 55 * MacOSX returns a value cached after the first localtime() call. 56 * AIX returns GMT offset without account of DST state and indicates 57 * only that timezone has DST, but does not indicate current DST state. 58 * 59 * 2) There are the "timezone" and "daylight" variables on Linux, Solaris, 60 * HP-UX, IRIX, and other systems. The "daylight" variable indicates 61 * only that timezone has DST, but does not indicate current DST state. 62 * 63 * 3) Solaris and IRIX have the "altzone" variable which contains GMT offset 64 * for timezone with DST applied, but without account of DST state. 65 * 66 * 4) There is the "struct tm.tm_gmtoff" field on BSD systems and modern Linux. 67 * This field contains GMT offset with account of DST state. 68 * 69 * 5) The "struct tm.tm_isdst" field returned by localtime() indicates 70 * current DST state on all platforms. This field may have three values: 71 * positive means DST in effect, zero means DST is not in effect, and 72 * negative means DST state is unknown. 73 */ 74 75 #if (NXT_HAVE_TM_GMTOFF) 76 77 #define nxt_timezone(tm) \ 78 ((tm)->tm_gmtoff) 79 80 #elif (NXT_HAVE_ALTZONE) 81 82 #define nxt_timezone(tm) \ 83 (-(((tm)->tm_isdst > 0) ? altzone : timezone)) 84 85 #else 86 87 #define nxt_timezone(tm) \ 88 (-(((tm)->tm_isdst > 0) ? timezone + 3600 : timezone)) 89 90 #endif 91 92 93 typedef uint32_t nxt_msec_t; 94 typedef int32_t nxt_msec_int_t; 95 #define NXT_INFINITE_MSEC ((nxt_msec_t) -1) 96 97 98 /* 99 * Since nxt_msec_t values are stored just in 32 bits, they overflow 100 * every 49 days. This signed subtraction takes into account that overflow. 101 * "nxt_msec_diff(m1, m2) < 0" means that m1 is lesser than m2. 102 */ 103 #define nxt_msec_diff(m1, m2) \ 104 ((int32_t) ((m1) - (m2))) 105 106 107 #endif /* _NXT_UNIX_TIME_H_INCLUDED_ */ 108