Botan  2.11.0
Crypto and TLS for C++11
calendar.cpp
Go to the documentation of this file.
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 
16 namespace Botan {
17 
18 namespace {
19 
20 std::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 /*
39 Portable replacement for timegm, _mkgmtime, etc
40 
41 Algorithm due to Howard Hinnant
42 
43 See https://howardhinnant.github.io/date_algorithms.html#days_from_civil
44 for details and explaination. The code is slightly simplified by our assumption
45 that the date is at least 1970, which is sufficient for our purposes.
46 */
47 size_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 
60 std::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 
96 std::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_seconds() const
Definition: calendar.h:43
#define BOTAN_IF_CONSTEXPR
Definition: compiler.h:161
calendar_point calendar_value(const std::chrono::system_clock::time_point &time_point)
Definition: calendar.cpp:111
uint32_t get_month() const
Definition: calendar.h:29
uint32_t get_minutes() const
Definition: calendar.h:38
uint32_t get_hour() const
Definition: calendar.h:35
Definition: alg_id.cpp:13
std::string to_string() const
Definition: calendar.cpp:96
uint32_t get_day() const
Definition: calendar.h:32
std::chrono::system_clock::time_point to_std_timepoint() const
Definition: calendar.cpp:60
uint32_t get_year() const
Definition: calendar.h:26