diff options
Diffstat (limited to 'src/util/time.cpp')
-rw-r--r-- | src/util/time.cpp | 43 |
1 files changed, 43 insertions, 0 deletions
diff --git a/src/util/time.cpp b/src/util/time.cpp index 295806c54a..9631c115e9 100644 --- a/src/util/time.cpp +++ b/src/util/time.cpp @@ -33,6 +33,49 @@ int64_t GetTime() return now; } +bool ChronoSanityCheck() +{ + // std::chrono::system_clock.time_since_epoch and time_t(0) are not guaranteed + // to use the Unix epoch timestamp, prior to C++20, but in practice they almost + // certainly will. Any differing behavior will be assumed to be an error, unless + // certain platforms prove to consistently deviate, at which point we'll cope + // with it by adding offsets. + + // Create a new clock from time_t(0) and make sure that it represents 0 + // seconds from the system_clock's time_since_epoch. Then convert that back + // to a time_t and verify that it's the same as before. + const time_t time_t_epoch{}; + auto clock = std::chrono::system_clock::from_time_t(time_t_epoch); + if (std::chrono::duration_cast<std::chrono::seconds>(clock.time_since_epoch()).count() != 0) { + return false; + } + + time_t time_val = std::chrono::system_clock::to_time_t(clock); + if (time_val != time_t_epoch) { + return false; + } + + // Check that the above zero time is actually equal to the known unix timestamp. + struct tm epoch; +#ifdef HAVE_GMTIME_R + if (gmtime_r(&time_val, &epoch) == nullptr) { +#else + if (gmtime_s(&epoch, &time_val) != 0) { +#endif + return false; + } + + if ((epoch.tm_sec != 0) || + (epoch.tm_min != 0) || + (epoch.tm_hour != 0) || + (epoch.tm_mday != 1) || + (epoch.tm_mon != 0) || + (epoch.tm_year != 70)) { + return false; + } + return true; +} + template <typename T> T GetTime() { |