[Boost-bugs] [Boost C++ Libraries] #6361: integer overflow in boost::chrono::process_real_cpu_clock::now() under Windows 32bits

Subject: [Boost-bugs] [Boost C++ Libraries] #6361: integer overflow in boost::chrono::process_real_cpu_clock::now() under Windows 32bits
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2012-01-05 17:27:06

#6361: integer overflow in boost::chrono::process_real_cpu_clock::now() under
Windows 32bits
---------------------------------+------------------------------------------
 Reporter:  ivan.lelann@…        |       Owner:  viboes 
     Type:  Bugs                 |      Status:  new    
Milestone:  To Be Determined     |   Component:  chrono 
  Version:  Boost 1.48.0         |    Severity:  Problem
 Keywords:                       |  
---------------------------------+------------------------------------------
 As of 1.48 Boost.Chrono contains code below for
 boost::chrono::process_real_cpu_clock::now()
 (boost\chrono\detail\inlined\win\process_cpu_clocks.hpp)

     clock_t c = ::clock();
     /* ... */
     return time_point(
       duration(c*(1000000000l/CLOCKS_PER_SEC))
     );

 duration::rep is int64/nanoseconds, clock_t is long. This is under VS2008,
 Win XP 32bits.
 I think "c" should be cast to duration::rep before being multiplied.

 C-style cast fixed the problem for me.
 Howard Hinnant suggested following cleaner fix on the mailing list :

 typedef ratio_divide<giga, ratio<CLOCKS_PER_SEC>>::type R;
 return time_point(
   duration(static_cast<rep>(c)*R::num/R::den)
 );

 NB: This appears at least twice in this file. It also appears in "mac" and
 "posix" folders though I cannot say if it is problematic on this
 platforms.

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/6361>
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