From 55ab731681a0e89be47defb252d3949620e7fb25 Mon Sep 17 00:00:00 2001
From: Vadim Zeitlin <vadim@wxwidgets.org>
Date: Sat, 6 Jul 2013 18:21:10 +0000
Subject: [PATCH] Fix FILETIME <-> wxDateTime conversions while DST is in
 effect in wxMSW.

The result was (consistently, so the tests still passed) off by an hour when
the program was ran while DST was in effect. Fix this by avoiding the use of
FileTimeToLocalFileTime() and LocalFileTimeToFileTime() and just directly
converting FILETIME values to wxDateTime. Not only this is more correct but
it's also simpler and more efficient as well.

Also add a unit test for wxFileName::SetTimes() too.

Closes #13098.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@74423 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
---
 docs/changes.txt                |  1 +
 src/common/filename.cpp         | 50 +++++++++++----------------------
 tests/filename/filenametest.cpp | 24 ++++++++++++++++
 3 files changed, 41 insertions(+), 34 deletions(-)

diff --git a/docs/changes.txt b/docs/changes.txt
index d29c67521d..c6f93d8848 100644
--- a/docs/changes.txt
+++ b/docs/changes.txt
@@ -711,6 +711,7 @@ wxMSW:
 - Fix filter checks in wxDir::FindFirst/Next() (Catalin Raceanu).
 - Add support for wxICON_AUTH_NEEDED to wxMessageDialog (Chris Spencer).
 - Fix printing too many copies of the document in some cases (John Roberts).
+- Fix DST confusion in wxFileName::{Set,Get}Times().
 
 wxOSX/Cocoa:
 
diff --git a/src/common/filename.cpp b/src/common/filename.cpp
index d6d68aeeb6..44b47f0719 100644
--- a/src/common/filename.cpp
+++ b/src/common/filename.cpp
@@ -93,6 +93,7 @@
 #include "wx/config.h"          // for wxExpandEnvVars
 #include "wx/dynlib.h"
 #include "wx/dir.h"
+#include "wx/longlong.h"
 
 #if defined(__WIN32__) && defined(__MINGW32__)
     #include "wx/msw/gccpriv.h"
@@ -231,49 +232,30 @@ private:
 
 #if wxUSE_DATETIME && defined(__WIN32__) && !defined(__WXMICROWIN__)
 
-// convert between wxDateTime and FILETIME which is a 64-bit value representing
-// the number of 100-nanosecond intervals since January 1, 1601.
+// Convert between wxDateTime and FILETIME which is a 64-bit value representing
+// the number of 100-nanosecond intervals since January 1, 1601 UTC.
+//
+// This is the offset between FILETIME epoch and the Unix/wxDateTime Epoch.
+static wxInt64 EPOCH_OFFSET_IN_MSEC = wxLL(11644473600000);
 
 static void ConvertFileTimeToWx(wxDateTime *dt, const FILETIME &ft)
 {
-    FILETIME ftcopy = ft;
-    FILETIME ftLocal;
-    if ( !::FileTimeToLocalFileTime(&ftcopy, &ftLocal) )
-    {
-        wxLogLastError(wxT("FileTimeToLocalFileTime"));
-    }
-
-    SYSTEMTIME st;
-    if ( !::FileTimeToSystemTime(&ftLocal, &st) )
-    {
-        wxLogLastError(wxT("FileTimeToSystemTime"));
-    }
+    wxLongLong t(ft.dwHighDateTime, ft.dwLowDateTime);
+    t /= 10000; // Convert hundreds of nanoseconds to milliseconds.
+    t -= EPOCH_OFFSET_IN_MSEC;
 
-    dt->Set(st.wDay, wxDateTime::Month(st.wMonth - 1), st.wYear,
-            st.wHour, st.wMinute, st.wSecond, st.wMilliseconds);
+    *dt = wxDateTime(t);
 }
 
 static void ConvertWxToFileTime(FILETIME *ft, const wxDateTime& dt)
 {
-    SYSTEMTIME st;
-    st.wDay = dt.GetDay();
-    st.wMonth = (WORD)(dt.GetMonth() + 1);
-    st.wYear = (WORD)dt.GetYear();
-    st.wHour = dt.GetHour();
-    st.wMinute = dt.GetMinute();
-    st.wSecond = dt.GetSecond();
-    st.wMilliseconds = dt.GetMillisecond();
+    // Undo the conversions above.
+    wxLongLong t(dt.GetValue());
+    t += EPOCH_OFFSET_IN_MSEC;
+    t *= 10000;
 
-    FILETIME ftLocal;
-    if ( !::SystemTimeToFileTime(&st, &ftLocal) )
-    {
-        wxLogLastError(wxT("SystemTimeToFileTime"));
-    }
-
-    if ( !::LocalFileTimeToFileTime(&ftLocal, ft) )
-    {
-        wxLogLastError(wxT("LocalFileTimeToFileTime"));
-    }
+    ft->dwHighDateTime = t.GetHi();
+    ft->dwLowDateTime = t.GetLo();
 }
 
 #endif // wxUSE_DATETIME && __WIN32__
diff --git a/tests/filename/filenametest.cpp b/tests/filename/filenametest.cpp
index 10ef920f39..3117760f13 100644
--- a/tests/filename/filenametest.cpp
+++ b/tests/filename/filenametest.cpp
@@ -35,6 +35,7 @@
 #endif // __UNIX__
 
 #include "testfile.h"
+#include "testdate.h"
 
 // ----------------------------------------------------------------------------
 // test data
@@ -139,6 +140,7 @@ private:
         CPPUNIT_TEST( TestVolumeUniqueName );
         CPPUNIT_TEST( TestCreateTempFileName );
         CPPUNIT_TEST( TestGetTimes );
+        CPPUNIT_TEST( TestSetTimes );
         CPPUNIT_TEST( TestExists );
         CPPUNIT_TEST( TestIsSame );
 #if defined(__UNIX__)
@@ -161,6 +163,7 @@ private:
     void TestVolumeUniqueName();
     void TestCreateTempFileName();
     void TestGetTimes();
+    void TestSetTimes();
     void TestExists();
     void TestIsSame();
 #if defined(__UNIX__)
@@ -664,6 +667,27 @@ void FileNameTestCase::TestGetTimes()
     CPPUNIT_ASSERT(dtAccess.IsEqualUpTo(wxDateTime::Now(), wxTimeSpan(0,1)));
 }
 
+void FileNameTestCase::TestSetTimes()
+{
+    wxFileName fn(wxFileName::CreateTempFileName("filenametest"));
+    CPPUNIT_ASSERT( fn.IsOk() );
+    wxON_BLOCK_EXIT1( wxRemoveFile, fn.GetFullPath() );
+
+    const wxDateTime dtAccess(1, wxDateTime::Jan, 2013);
+    const wxDateTime dtModify(1, wxDateTime::Feb, 2013);
+    const wxDateTime dtCreate(1, wxDateTime::Mar, 2013);
+
+    CPPUNIT_ASSERT( fn.SetTimes(&dtAccess, &dtModify, &dtCreate) );
+
+    wxDateTime dtAccess2,
+               dtModify2,
+               dtCreate2;
+    CPPUNIT_ASSERT( fn.GetTimes(&dtAccess2, &dtModify2, &dtCreate2) );
+    CPPUNIT_ASSERT_EQUAL( dtAccess, dtAccess2 );
+    CPPUNIT_ASSERT_EQUAL( dtModify, dtModify2 );
+    CPPUNIT_ASSERT_EQUAL( dtCreate, dtCreate2 );
+}
+
 void FileNameTestCase::TestExists()
 {
     wxFileName fn(wxFileName::CreateTempFileName("filenametest"));
-- 
2.45.2