src/walltime_func.h

   1 /*
   2  * This file is part of OpenTTD.
   3  * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
   4  * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
   5  * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
   6  */
   7
   8  /** @file walltime_func.h Functionality related to the time of the clock on your wall. */
   9
  10 #ifndef WALLTIME_FUNC_H
  11 #define WALLTIME_FUNC_H
  12
  13 #include <ctime>
  14
  15 /** Helper for safely converting a std::time_t to a local time std::tm using localtime_s. */
  16 struct LocalTimeToStruct {
  17         static inline std::tm ToTimeStruct(std::time_t time_since_epoch)
  18         {
  19                 std::tm time = {};
  20 #ifdef _WIN32
  21                 /* Windows has swapped the parameters around for localtime_s. */
  22                 localtime_s(&time, &time_since_epoch);
  23 #else
  24                 localtime_r(&time_since_epoch, &time);
  25 #endif
  26                 return time;
  27         }
  28 };
  29
  30 /** Helper for safely converting a std::time_t to a UTC time std::tm using gmtime_s. */
  31 struct UTCTimeToStruct {
  32         static inline std::tm ToTimeStruct(std::time_t time_since_epoch)
  33         {
  34                 std::tm time = {};
  35 #ifdef _WIN32
  36                 /* Windows has swapped the parameters around for gmtime_s. */
  37                 gmtime_s(&time, &time_since_epoch);
  38 #else
  39                 gmtime_r(&time_since_epoch, &time);
  40 #endif
  41                 return time;
  42         }
  43 };
  44
  45 /**
  46  * Container for wall clock time related functionality not directly provided by C++.
  47  * @tparam T The type of the time-to-struct implementation class.
  48  */
  49 template <typename T>
  50 struct Time {
  51         /**
  52          * Format the current time with the given strftime format specifiers.
  53          * @param buffer The buffer to write the time string to.
  54          * @param last   The last element in the buffer.
  55          * @param format The format according to strftime format specifiers.
  56          * @return The number of characters that were written to the buffer.
  57          */
  58         static inline size_t Format(char *buffer, const char *last, const char *format) NOACCESS(2) WARN_TIME_FORMAT(3)
  59         {
  60                 std::tm time_struct = T::ToTimeStruct(time(nullptr));
  61 #ifndef _MSC_VER
  62                 /* GCC bug #39438; unlike for printf where the appropriate attribute prevent the
  63                  * "format non literal" warning, that does not happen for strftime. Even though
  64                  * format warnings will be created for invalid strftime formats. */
  65 #pragma GCC diagnostic push
  66 #pragma GCC diagnostic ignored "-Wformat-nonliteral"
  67 #endif /* _MSC_VER */
  68                 return strftime(buffer, last - buffer, format, &time_struct);
  69 #ifndef _MSC_VER
  70 #pragma GCC diagnostic pop
  71 #endif /* _MSC_VER */
  72         }
  73 };
  74
  75 /** Wall clock time functionality using the local time zone. */
  76 using LocalTime = Time<LocalTimeToStruct>;
  77 /** Wall clock time functionality using the UTC time zone. */
  78 using UTCTime = Time<UTCTimeToStruct>;
  79
  80 #endif