diff options
Diffstat (limited to 'butl/timestamp.cxx')
| -rw-r--r-- | butl/timestamp.cxx | 221 |
1 files changed, 134 insertions, 87 deletions
diff --git a/butl/timestamp.cxx b/butl/timestamp.cxx index 2759592..bf02829 100644 --- a/butl/timestamp.cxx +++ b/butl/timestamp.cxx @@ -4,10 +4,10 @@ #include <butl/timestamp> -#include <time.h> // localtime_r(), gmtime_r(), strptime(), timegm() +#include <time.h> // localtime_{r,s}(), gmtime_{r,s}(), strptime(), timegm() #include <errno.h> // EINVAL -#include <ctime> // tm, time_t, strftime(), mktime() +#include <ctime> // tm, time_t, mktime() #include <cstdlib> // strtoull() #include <cassert> #include <iomanip> // put_time(), setw(), dec, right @@ -31,6 +31,7 @@ using namespace std; // of the std::tm argument. // #ifdef __GLIBCXX__ + #include <ctime> // tm, strftime() #include <ostream> @@ -61,8 +62,38 @@ namespace details } using namespace details; + #endif +// Thread-safe implementations of gmtime() and localtime(). +// +// Normally we would provide POSIX function replacement for Windows if the +// original function is absent. However, MinGW GCC can sometimes provide them. +// And so to avoid name clashes we hide them in the details namespace. +// +namespace details +{ + static tm* + gmtime (const time_t* t, tm* r) + { +#ifdef _WIN32 + return gmtime_s (r, t) != 0 ? nullptr : r; +#else + return gmtime_r (t, r); +#endif + } + + static tm* + localtime (const time_t* t, tm* r) + { +#ifdef _WIN32 + return localtime_s (r, t) != 0 ? nullptr : r; +#else + return localtime_r (t, r); +#endif + } +} + namespace butl { ostream& @@ -84,7 +115,9 @@ namespace butl time_t t (system_clock::to_time_t (ts)); std::tm tm; - if ((local ? localtime_r (&t, &tm) : gmtime_r (&t, &tm)) == nullptr) + if ((local + ? details::localtime (&t, &tm) + : details::gmtime (&t, &tm)) == nullptr) throw system_error (errno, system_category ()); using namespace chrono; @@ -214,7 +247,7 @@ namespace butl if (fmt != nullptr) { std::tm tm; - if (gmtime_r (&t, &tm) == nullptr) + if (details::gmtime (&t, &tm) == nullptr) throw system_error (errno, system_category ()); if (t >= 24 * 60 * 60) @@ -260,105 +293,119 @@ namespace butl } } -// VC++ implementation of strptime() via std::get_time(). +// Implementation of strptime() and timegm() for Windows. +// +// Here we have several cases. If this is VC++, then we implement strptime() +// via C++11 std::get_time(). And if this is MINGW GCC (or, more precisely, +// libstdc++), then we have several problems. Firstly, GCC prior to 5 doesn't +// implement std::get_time(). Secondly, GCC 5 and even 6 have buggy +// std::get_time() (it cannot parse single-digit days). So what we are going +// to do in this case is use a FreeBSD-based strptime() implementation. // -// To debug fallback functions with GCC, uncomment the following defines. +#ifdef _WIN32 + +#ifdef __GLIBCXX__ + +// Fallback to a FreeBSD-based implementation. // -//#define _MSC_VER -//#define strptime strptime_ -//#define timegm timegm_ +extern "C" +{ +#include "strptime.c" +} -#ifdef _MSC_VER -#include <ctime> // time_t, tm, mktime(), gmtime() +#else // NOT __GLIBCXX__ + +#include <ctime> // tm #include <locale> #include <clocale> #include <sstream> #include <iomanip> #include <cstring> // strlen() -namespace details +// VC++ std::get_time()-based implementation. +// +static char* +strptime (const char* input, const char* format, tm* time) { - static char* - strptime (const char* input, const char* format, tm* time) - { - istringstream is (input); - - // The original strptime() function behaves according to the process' C - // locale (set with std::setlocale()), which can differ from the process - // C++ locale (set with std::locale::global()). + istringstream is (input); + + // The original strptime() function behaves according to the process' C + // locale (set with std::setlocale()), which can differ from the process C++ + // locale (set with std::locale::global()). + // + is.imbue (locale (setlocale (LC_ALL, nullptr))); + + if (!(is >> get_time (time, format))) + return nullptr; + else + // tellg() behaves as UnformattedInputFunction, so returns failure status + // if eofbit is set. // - is.imbue (locale (setlocale (LC_ALL, nullptr))); + return const_cast<char*> ( + input + (is.eof () + ? strlen (input) + : static_cast<size_t> (is.tellg ()))); +} - if (!(is >> get_time (time, format))) - return nullptr; - else - // tellg () behaves as UnformattedInputFunction, so returns failure - // status if eofbit is set. - // - return const_cast<char*> ( - input + (is.eof () - ? strlen (input) - : static_cast<size_t> (is.tellg ()))); - } +#endif // __GLIBCXX__ - static time_t - timegm (tm* ctm) - { - const time_t e (static_cast<time_t> (-1)); +#include <ctime> // time_t, tm, mktime() - // We will use an example to explain how it works. Say *ctm contains 9 AM - // of some day. Note that no time zone information is available. - // - // Convert it to the time from Epoch as if it's in the local time zone. - // - ctm->tm_isdst = -1; - time_t t (mktime (ctm)); - if (t == e) - return e; - - // Let's say we are in Moscow, and t contains the time passed from Epoch - // till 9 AM MSK. But that is not what we need. What we need is the time - // passed from Epoch till 9 AM GMT. This is some bigger number, as it takes - // longer to achieve the same calendar time for more Western location. So - // we need to find that offset, and increment t with it to obtain the - // desired value. The offset is effectively the time difference between MSK - // and GMT time zones. - // - tm gtm; - if (gmtime_r (&t, >m) == nullptr) - return e; - - // gmtime_r() being called for the timepoint t returns 6 AM. So now we - // have *ctm and gtm, which value difference (3 hours) reflects the - // desired offset. The only problem is that we can not deduct gtm from - // *ctm, to get the offset expressed as time_t. To do that we need to apply - // to both of them the same conversion function transforming std::tm to - // std::time_t. The mktime() can do that, so the expression (mktime(ctm) - - // mktime(>m)) calculates the desired offset. - // - // To ensure mktime() works exactly the same way for both cases, we need - // to reset Daylight Saving Time flag for each of *ctm and gtm. - // - ctm->tm_isdst = 0; - time_t lt (mktime (ctm)); - if (lt == e) - return e; - - gtm.tm_isdst = 0; - time_t gt (mktime (>m)); - if (gt == e) - return e; - - // C11 standard specifies time_t to be a real type (integer and real - // floating types are collectively called real types). So we can not - // consider it to be signed. - // - return lt > gt ? t + (lt - gt) : t - (gt - lt); - } +static time_t +timegm (tm* ctm) +{ + const time_t e (static_cast<time_t> (-1)); + + // We will use an example to explain how it works. Say *ctm contains 9 AM of + // some day. Note that no time zone information is available. + // + // Convert it to the time from Epoch as if it's in the local time zone. + // + ctm->tm_isdst = -1; + time_t t (mktime (ctm)); + if (t == e) + return e; + + // Let's say we are in Moscow, and t contains the time passed from Epoch till + // 9 AM MSK. But that is not what we need. What we need is the time passed + // from Epoch till 9 AM GMT. This is some bigger number, as it takes longer + // to achieve the same calendar time for more Western location. So we need to + // find that offset, and increment t with it to obtain the desired value. The + // offset is effectively the time difference between MSK and GMT time zones. + // + tm gtm; + if (details::gmtime (&t, >m) == nullptr) + return e; + + // gmtime() being called for the timepoint t returns 6 AM. So now we have + // *ctm and gtm, which value difference (3 hours) reflects the desired + // offset. The only problem is that we can not deduct gtm from *ctm, to get + // the offset expressed as time_t. To do that we need to apply to both of + // them the same conversion function transforming std::tm to std::time_t. The + // mktime() can do that, so the expression (mktime(ctm) - mktime(>m)) + // calculates the desired offset. + // + // To ensure mktime() works exactly the same way for both cases, we need to + // reset Daylight Saving Time flag for each of *ctm and gtm. + // + ctm->tm_isdst = 0; + time_t lt (mktime (ctm)); + if (lt == e) + return e; + + gtm.tm_isdst = 0; + time_t gt (mktime (>m)); + if (gt == e) + return e; + + // C11 standard specifies time_t to be a real type (integer and real floating + // types are collectively called real types). So we can not consider it to be + // signed. + // + return lt > gt ? t + (lt - gt) : t - (gt - lt); } -using namespace details; -#endif +#endif // _WIN32 namespace butl { |