[boost] Bug in boost 1.32: date_time/microsec_time_clock.hpp

From: martin troxler (martin.troxler_at_[hidden])
Date: 2005-05-12 03:37:25

It is possible, that the following line 
 
       boost::posix_time::ptime now = boost::posix_time::microsec_clock::local_time(); 
 
which invokes 
 
  template<class time_type> 
  class microsec_clock 
  { 
      static time_type local_time() { 
          timeval tv; 
          gettimeofday(&tv, 0); //gettimeofday does not support TZ adjust on Linux. 
          return create_time(&tv); 
      } 
 
      static time_type create_time(timeval* tv) { 
          time_t t = tv->tv_sec; 
          boost::uint32_t fs = tv->tv_usec; 
          ::std::time(&t); 
         tm* curr = localtime(&t); 
         .... 
 
returns a time with 1s off its correct value. 
 
The reason for this bug is the line with 
::std::time(&t); 
 
that overwrites the second value just a few µs after the call to gettimofday. 
This new second value is used together with the fs value from gettimeofday. 
 
Example: 
tv from gettimofday: 12345s/999998 µs 
t from std::time: 12346s 
resulting time: 12346s/999998 µs !!!! 
 
Question: Why this call to std::time? I commented it out and it worked. 
 
Regards 
Martin