1 /*
2 * sys-time.h - time.h wrapper for localtime_r() and gmtime_r()
3 *
4 * Copyright(c) 2015 Glenn Strauss gstrauss()gluelogic.com All rights reserved
5 * License: BSD 3-clause (same as lighttpd)
6 */
7 #ifndef LI_SYS_TIME_H
8 #define LI_SYS_TIME_H
9 #include "first.h"
10
11 #ifdef HAVE_SYS_TIME_H
12 #include <sys/time.h>/* gettimeofday() */
13 #endif
14 #include <time.h> /* time() localtime_r() gmtime_r() strftime() */
15
16 /*(provide rudimentary localtime_r() and gmtime_r() for platforms lacking)
17 *(Note that 'result' preprocessor arg is repeated, so callers should avoid
18 * side-effects. Also note that there is still a race condition before the
19 * result of localtime()/gmtime() is copied. In any case, this exists here
20 * so that the rest of the code can use localtime_r() and gmtime_r() syntax.
21 * Platforms requiring thread-safety and lacking localtime_r() or gmtime_r()
22 * could turn these into subroutines which take a local mutex to protect the
23 * calls to localtime() or gmtime()) */
24 #ifndef HAVE_LOCALTIME_R
25 #define localtime_r(timep,result) ((*(result) = *(localtime(timep))), (result))
26 #endif
27 #ifndef HAVE_GMTIME_R
28 #define gmtime_r(timep,result) ((*(result) = *(gmtime(timep))), (result))
29 #endif
30
31 #ifndef HAVE_TIMEGM
32 #ifdef _WIN32
33 #define timegm(tm) _mkgmtime(tm)
34 #else
35 __attribute_pure__
36 static inline time_t
37 timegm (const struct tm * const tm);
38 static inline time_t
timegm(const struct tm * const tm)39 timegm (const struct tm * const tm)
40 {
41 int y = tm->tm_year + 1900;
42 int m = tm->tm_mon + 1;
43 int d = tm->tm_mday;
44
45 /* days_from_civil() http://howardhinnant.github.io/date_algorithms.html */
46 y -= m <= 2;
47 int era = y / 400;
48 int yoe = y - era * 400; // [0, 399]
49 int doy = (153 * (m + (m > 2 ? -3 : 9)) + 2) / 5 + d - 1; // [0, 365]
50 int doe = yoe * 365 + yoe / 4 - yoe / 100 + doy; // [0, 146096]
51 int days_since_1970 = era * 146097 + doe - 719468;
52
53 return 60*(60*(24L*days_since_1970+tm->tm_hour)+tm->tm_min)+tm->tm_sec;
54 }
55 #endif
56 #endif
57
58
59 /* non-standard functions created for lighttpd for Y2038 problem
60 * reference: https://en.wikipedia.org/wiki/Year_2038_problem
61 *
62 * lighttpd does not expect to deal with dates earlier than 1970,
63 * and can therefore treat dates earlier than 1970 as having overflowed
64 * 32-bit signed time_t, signifying dates after Tue, 19 Jan 2038 03:14:07 GMT
65 *
66 * 1954, 1982, 2010, 2038 begin on Thu and are two years offset from leap year.
67 * Attempt to adjust a timestamp > INT32_MAX back to a similar year, starting on
68 * same weekday, and being same distance from next leap year; use gmtime_r()
69 * or localtime_r(); and then adjust tm.tm_year back to the year of the original
70 * timestamp. (Note that the calculations here are valid for the specific range
71 * of input timestamps mapped to 1970 and 2099. The year 2000 was a leap year,
72 * so crossing 2000 *does not* require special-casing here, but the year 2100
73 * *is not* a leap year in the Gregorian calendar, so this code is not valid
74 * after 28 Feb 2100. Since the max validity of these kludges could only be
75 * until 7 Feb 2106, this code has chosen not to special-case 2100-2106 and
76 * produces incorrect results after 28 Feb 2100.)
77 */
78 #if HAS_TIME_BITS64
79
80 #define gmtime64_r(timep,result) gmtime_r((timep),(result))
81 #define localtime64_r(timep,result) localtime_r((timep),(result))
82
83 #else /* !HAS_TIME_BITS64 */
84
85 #define gmtime64_r(timep,result) gmtime_y2038_kludge32(*(timep),(result))
86 #define localtime64_r(timep,result) localtime_y2038_kludge32(*(timep),(result))
87
88 static inline struct tm *
89 gmtime_y2038_kludge32 (unix_time64_t t, struct tm *result);
90 static inline struct tm *
gmtime_y2038_kludge32(unix_time64_t t,struct tm * result)91 gmtime_y2038_kludge32 (unix_time64_t t, struct tm *result)
92 {
93 if ((uint64_t)t <= INT32_MAX) {
94 time_t tt = (time_t)t;
95 return gmtime_r(&tt, result);
96 }
97 else {
98 /*(treat negative time as having overflowed 32-bit time_t)*/
99 if (t < 0)
100 t = TIME64_CAST(t);
101 time_t tt = (time_t)(t - 2650838400LL);
102 if (gmtime_r(&tt, result)) {
103 result->tm_year += 84;
104 return result;
105 }
106 else if (t < 3914709247LL) {
107 /*(ok through Tue, 19 Jan 2094 03:14:07 GMT)*/
108 tt = (time_t)(t - 1767225600LL);
109 if (gmtime_r(&tt, result)) {
110 result->tm_year += 56;
111 return result;
112 }
113 }
114
115 /*(choose to forever return gmtime_r() equivalent of
116 * Thu, 01 Jan 1970 00:00:00 GMT)
117 *(returning NULL not expected by lighttpd and might crash)*/
118 tt = 0;
119 gmtime_r(&tt, result);
120 return result;
121 }
122 }
123
124 static inline struct tm *
125 localtime_y2038_kludge32 (unix_time64_t t, struct tm *result);
126 static inline struct tm *
localtime_y2038_kludge32(unix_time64_t t,struct tm * result)127 localtime_y2038_kludge32 (unix_time64_t t, struct tm *result)
128 {
129 if ((uint64_t)t <= INT32_MAX) {
130 time_t tt = (time_t)t;
131 return localtime_r(&tt, result);
132 }
133 else {
134 /*(treat negative time as having overflowed 32-bit time_t)*/
135 if (t < 0)
136 t = TIME64_CAST(t);
137 time_t tt = (time_t)(t - 2650838400LL);
138 if (localtime_r(&tt, result)) {
139 result->tm_year += 84;
140 return result;
141 }
142 else if (t < 3914709247LL) {
143 /*(ok through Tue, 19 Jan 2094 03:14:07 GMT)*/
144 tt = (time_t)(t - 1767225600LL);
145 if (localtime_r(&tt, result)) {
146 result->tm_year += 56;
147 return result;
148 }
149 }
150
151 /*(choose to forever return localtime_r() equivalent of
152 * Thu, 01 Jan 1970 00:00:00 GMT)
153 *(returning NULL not expected by lighttpd and might crash)*/
154 tt = 0;
155 localtime_r(&tt, result);
156 return result;
157 }
158 }
159
160 #endif /* !HAS_TIME_BITS64 */
161
162
163 #endif
164