Change Windows daylight saving time calculations to...

src/platform-win32.cc

 // Copyright 2006-2008 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 38 matching lines @@
 #define NOMCX
 #endif
 // Require Windows 2000 or higher (this is required for the IsDebuggerPresent
 // function to be present).
 #ifndef _WIN32_WINNT
 #define _WIN32_WINNT 0x500
 #endif
 
 #include <windows.h>
 
+#include <time.h>  // For LocalOffset() implementation.
 #include <mmsystem.h>  // For timeGetTime().
 #include <dbghelp.h>  // For SymLoadModule64 and al.
 #include <tlhelp32.h>  // For Module32First and al.
 
 // These aditional WIN32 includes have to be right here as the #undef's below
 // makes it impossible to have them elsewhere.
 #include <winsock2.h>
 #include <process.h>  // for _beginthreadex()
 #include <stdlib.h>
 
@@ skipping 247 matching lines @@
 }
 
 
 // Initialize timezone information. The timezone information is obtained from
 // windows. If we cannot get the timezone information we fall back to CET.
 // Please notice that this code is not thread-safe.
 void Time::TzSet() {
   // Just return if timezone information has already been initialized.
   if (tz_initialized_) return;
 
+  // Initialize POSIX time zone data.
+  _tzset();
   // Obtain timezone information from operating system.
   memset(&tzinfo_, 0, sizeof(tzinfo_));
   if (GetTimeZoneInformation(&tzinfo_) == TIME_ZONE_ID_INVALID) {
     // If we cannot get timezone information we fall back to CET.
     tzinfo_.Bias = -60;
     tzinfo_.StandardDate.wMonth = 10;
     tzinfo_.StandardDate.wDay = 5;
     tzinfo_.StandardDate.wHour = 3;
     tzinfo_.StandardBias = 0;
     tzinfo_.DaylightDate.wMonth = 3;
@@ skipping 53 matching lines @@
   //
   // To use the clock, we use GetSystemTimeAsFileTime as our base;
   // and then use timeGetTime to extrapolate current time from the
   // start time.  To deal with rollovers, we resync the clock
   // any time when more than kMaxClockElapsedTime has passed or
   // whenever timeGetTime creates a rollover.
 
   static bool initialized = false;
   static TimeStamp init_time;
   static DWORD init_ticks;
-  static const int kHundredNanosecondsPerSecond = 10000;
-  static const int kMaxClockElapsedTime =
-      60*60*24*kHundredNanosecondsPerSecond;  // 1 day
+  static const int64_t kHundredNanosecondsPerSecond = 10000000;
+  static const int64_t kMaxClockElapsedTime =
+      60*kHundredNanosecondsPerSecond;  // 1 minute
 
   // If we are uninitialized, we need to resync the clock.
   bool needs_resync = !initialized;
 
   // Get the current time.
   TimeStamp time_now;
   GetSystemTimeAsFileTime(&time_now.ft_);
   DWORD ticks_now = timeGetTime();
 
   // Check if we need to resync due to clock rollover.
@@ skipping 10 matching lines @@
   }
 
   // Finally, compute the actual time.  Why is this so hard.
   DWORD elapsed = ticks_now - init_ticks;
   this->time_.t_ = init_time.t_ + (static_cast<int64_t>(elapsed) * 10000);
 }
 
 
 // Return the local timezone offset in milliseconds east of UTC. This
 // takes into account whether daylight saving is in effect at the time.
+// Only times in the 32-bit Unix range may be passed to this function.
+// Also, adding the time-zone offset to the input must not overflow.
+// The function EquivalentTime() in date-delay.js guarantees this.
 int64_t Time::LocalOffset() {
   // Initialize timezone information, if needed.
   TzSet();
 
-  // Convert timestamp to date/time components. These are now in UTC
-  // format. NB: Please do not replace the following three calls with one
-  // call to FileTimeToLocalFileTime(), because it does not handle
-  // daylight saving correctly.
-  SYSTEMTIME utc;
-  FileTimeToSystemTime(&ft(), &utc);
+  Time rounded_to_second(*this);
+  rounded_to_second.t() = rounded_to_second.t() / 1000 / kTimeScaler *
+      1000 * kTimeScaler;
+  // Convert to local time using POSIX localtime function.
+  // Windows XP Service Pack 3 made SystemTimeToTzSpecificLocalTime()
+  // very slow.  Other browsers use localtime().
 
-  // Convert to local time, using timezone information.
-  SYSTEMTIME local;
-  SystemTimeToTzSpecificLocalTime(&tzinfo_, &utc, &local);
+  // Convert from JavaScript milliseconds past 1/1/1970 0:00:00 to
+  // POSIX seconds past 1/1/1970 0:00:00.
+  double unchecked_posix_time = rounded_to_second.ToJSTime() / 1000;
+  if (unchecked_posix_time > INT_MAX || unchecked_posix_time < 0) {
+    return 0;
+  }
+  // Because _USE_32BIT_TIME_T is defined, time_t is a 32-bit int.
+  time_t posix_time = static_cast<time_t>(unchecked_posix_time);
 
-  // Convert local time back to a timestamp. This timestamp now
-  // has a bias similar to the local timezone bias in effect
-  // at the time of the original timestamp.
-  Time localtime;
-  SystemTimeToFileTime(&local, &localtime.ft());
+  // Convert to local time, as struct with fields for day, hour, year, etc.
+  tm posix_local_time_struct;
+  if (localtime_s(&posix_local_time_struct, &posix_time)) return 0;
+  // Convert local time in struct to POSIX time as if it were a UTC time.
+  time_t local_posix_time = _mkgmtime(&posix_local_time_struct);
+  Time localtime(1000.0 * local_posix_time);
 
-  // The difference between the new local timestamp and the original
-  // timestamp and is the local timezone offset.
-  return localtime.Diff(this);
+  return localtime.Diff(&rounded_to_second);
 }
 
 
 // Return whether or not daylight savings time is in effect at this time.
 bool Time::InDST() {
   // Initialize timezone information, if needed.
   TzSet();
 
   // Determine if DST is in effect at the specified time.
   bool in_dst = false;
@@ skipping 1102 matching lines @@
 
   // Release the thread handles
   CloseHandle(data_->sampler_thread_);
   CloseHandle(data_->profiled_thread_);
 }
 
 
 #endif  // ENABLE_LOGGING_AND_PROFILING
 
 } }  // namespace v8::internal