Botan 2.19.2
Crypto and TLS for C&
calendar.cpp
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1/*
2* Calendar Functions
3* (C) 1999-2010,2017 Jack Lloyd
4* (C) 2015 Simon Warta (Kullo GmbH)
5*
6* Botan is released under the Simplified BSD License (see license.txt)
7*/
8
9#include <botan/calendar.h>
10#include <botan/exceptn.h>
11#include <ctime>
12#include <sstream>
13#include <iomanip>
14#include <stdlib.h>
15
16namespace Botan {
17
18namespace {
19
20std::tm do_gmtime(std::time_t time_val)
21 {
22 std::tm tm;
23
24#if defined(BOTAN_TARGET_OS_HAS_WIN32)
25 ::gmtime_s(&tm, &time_val); // Windows
26#elif defined(BOTAN_TARGET_OS_HAS_POSIX1)
27 ::gmtime_r(&time_val, &tm); // Unix/SUSv2
28#else
29 std::tm* tm_p = std::gmtime(&time_val);
30 if (tm_p == nullptr)
31 throw Encoding_Error("time_t_to_tm could not convert");
32 tm = *tm_p;
33#endif
34
35 return tm;
36 }
37
38/*
39Portable replacement for timegm, _mkgmtime, etc
40
41Algorithm due to Howard Hinnant
42
43See https://howardhinnant.github.io/date_algorithms.html#days_from_civil
44for details and explaination. The code is slightly simplified by our assumption
45that the date is at least 1970, which is sufficient for our purposes.
46*/
47size_t days_since_epoch(uint32_t year, uint32_t month, uint32_t day)
48 {
49 if(month <= 2)
50 year -= 1;
51 const uint32_t era = year / 400;
52 const uint32_t yoe = year - era * 400; // [0, 399]
53 const uint32_t doy = (153*(month + (month > 2 ? -3 : 9)) + 2)/5 + day-1; // [0, 365]
54 const uint32_t doe = yoe * 365 + yoe/4 - yoe/100 + doy; // [0, 146096]
55 return era * 146097 + doe - 719468;
56 }
57
58}
59
60std::chrono::system_clock::time_point calendar_point::to_std_timepoint() const
61 {
62 if(get_year() < 1970)
63 throw Invalid_Argument("calendar_point::to_std_timepoint() does not support years before 1970");
64
65 // 32 bit time_t ends at January 19, 2038
66 // https://msdn.microsoft.com/en-us/library/2093ets1.aspx
67 // Throw after 2037 if 32 bit time_t is used
68
69 BOTAN_IF_CONSTEXPR(sizeof(std::time_t) == 4)
70 {
71 if(get_year() > 2037)
72 {
73 throw Invalid_Argument("calendar_point::to_std_timepoint() does not support years after 2037 on this system");
74 }
75 }
76
77 // This upper bound is completely arbitrary
78 if(get_year() >= 2400)
79 {
80 throw Invalid_Argument("calendar_point::to_std_timepoint() does not support years after 2400");
81 }
82
83 const uint64_t seconds_64 = (days_since_epoch(get_year(), get_month(), get_day()) * 86400) +
84 (get_hour() * 60 * 60) + (get_minutes() * 60) + get_seconds();
85
86 const time_t seconds_time_t = static_cast<time_t>(seconds_64);
87
88 if(seconds_64 - seconds_time_t != 0)
89 {
90 throw Invalid_Argument("calendar_point::to_std_timepoint time_t overflow");
91 }
92
93 return std::chrono::system_clock::from_time_t(seconds_time_t);
94 }
95
96std::string calendar_point::to_string() const
97 {
98 // desired format: <YYYY>-<MM>-<dd>T<HH>:<mm>:<ss>
99 std::stringstream output;
100 output << std::setfill('0')
101 << std::setw(4) << get_year() << "-"
102 << std::setw(2) << get_month() << "-"
103 << std::setw(2) << get_day() << "T"
104 << std::setw(2) << get_hour() << ":"
105 << std::setw(2) << get_minutes() << ":"
106 << std::setw(2) << get_seconds();
107 return output.str();
108 }
109
110
112 const std::chrono::system_clock::time_point& time_point)
113 {
114 std::tm tm = do_gmtime(std::chrono::system_clock::to_time_t(time_point));
115
116 return calendar_point(tm.tm_year + 1900,
117 tm.tm_mon + 1,
118 tm.tm_mday,
119 tm.tm_hour,
120 tm.tm_min,
121 tm.tm_sec);
122 }
123
124}
uint32_t get_minutes() const
Definition: calendar.h:38
std::string to_string() const
Definition: calendar.cpp:96
std::chrono::system_clock::time_point to_std_timepoint() const
Definition: calendar.cpp:60
uint32_t get_month() const
Definition: calendar.h:29
uint32_t get_seconds() const
Definition: calendar.h:43
uint32_t get_hour() const
Definition: calendar.h:35
uint32_t get_year() const
Definition: calendar.h:26
uint32_t get_day() const
Definition: calendar.h:32
#define BOTAN_IF_CONSTEXPR
Definition: compiler.h:176
Definition: alg_id.cpp:13
calendar_point calendar_value(const std::chrono::system_clock::time_point &time_point)
Definition: calendar.cpp:111