7.8

1 files changed, 70 insertions, 2 deletions

diff --git a/zen/format_unit.cpp b/zen/format_unit.cpp
index cfaaa329..cb92f1e4 100644
--- a/zen/format_unit.cpp
+++ b/zen/format_unit.cpp
@@ -8,7 +8,7 @@
 #include "basic_math.h"
 #include "i18n.h"
 #include "time.h"
-#include <cwchar>  //swprintf
+#include <cwchar> //swprintf
 #include <ctime>
 #include <cstdio>
 
@@ -293,7 +293,7 @@ std::wstring zen::utcToLocalTimeString(std::int64_t utcTime)
     auto errorMsg = [&] { return _("Error") + L" (time_t: " + numberTo<std::wstring>(utcTime) + L")"; };
 
 #ifdef ZEN_WIN
-    FILETIME lastWriteTimeUtc = timetToFileTime(utcTime); //convert ansi C time to FILETIME
+    const FILETIME lastWriteTimeUtc = timetToFileTime(utcTime); //convert ansi C time to FILETIME
 
     SYSTEMTIME systemTimeLocal = {};
 
@@ -342,3 +342,71 @@ std::wstring zen::utcToLocalTimeString(std::int64_t utcTime)
     std::wstring dateString = formatTime<std::wstring>(L"%x  %X", loc);
     return !dateString.empty() ? dateString : errorMsg();
 }
+
+
+#ifdef ZEN_WIN_VISTA_AND_LATER
+Opt<std::int64_t> zen::mtpVariantTimetoUtc(double localVarTime) //returns empty on error
+{
+    SYSTEMTIME localSystemTime = {};
+    if (!::VariantTimeToSystemTime(localVarTime,      //_In_  DOUBLE       vtime,
+                                   &localSystemTime)) //_Out_ LPSYSTEMTIME lpSystemTime
+        return NoValue();
+
+    /*
+    Windows Explorer isn't even consistent within itself: the modification time shown in the details list is calculated differently than the
+    one shown in MTP file properties => different result shown for files from a DST interval distinct from the current one.
+    -> Variant 1 matches the calculation of Explorer's details list and produces stable results irrespective of currently selected DST
+    -> Explorer uses different algorithms for MTP and FAT file systems! FAT's local time jumps between DST intervals in Explorer (since Vista)!
+    */
+#if 1
+    SYSTEMTIME utcSystemTime = {};
+    if (!::TzSpecificLocalTimeToSystemTime(nullptr,          //_In_opt_ LPTIME_ZONE_INFORMATION lpTimeZoneInformation,
+                                           &localSystemTime, //_In_     LPSYSTEMTIME            lpLocalTime,
+                                           &utcSystemTime))  //_Out_    LPSYSTEMTIME            lpUniversalTime
+        return NoValue();
+
+    FILETIME utcFiletime = {};
+    if (!::SystemTimeToFileTime(&utcSystemTime, //_In_  const SYSTEMTIME *lpSystemTime,
+                                &utcFiletime))  //_Out_       LPFILETIME lpFileTime
+        return NoValue();
+
+#else
+    FILETIME localFiletime = {};
+    if (!::SystemTimeToFileTime(&localSystemTime, //_In_  const SYSTEMTIME *lpSystemTime,
+                                &localFiletime))  //_Out_       LPFILETIME lpFileTime
+        return NoValue();
+
+    FILETIME utcFiletime = {};
+    if (!LocalFileTimeToFileTime(&localFiletime, //_In_  const FILETIME   *lpLocalFileTime,
+                                 &utcFiletime))  //_Out_       LPFILETIME lpFileTime
+        return NoValue();
+
+#endif
+
+    return filetimeToTimeT(utcFiletime);
+}
+
+
+Opt<double> zen::utcToMtpVariantTime(std::int64_t utcTime) //returns empty on error
+{
+    const FILETIME lastWriteTimeUtc = timetToFileTime(utcTime); //convert ansi C time to FILETIME
+
+    SYSTEMTIME systemTimeUtc = {};
+    if (!::FileTimeToSystemTime(&lastWriteTimeUtc, //__in   const FILETIME *lpFileTime,
+                                &systemTimeUtc))   //__out  LPSYSTEMTIME lpSystemTime
+        return NoValue();
+
+    SYSTEMTIME systemTimeLocal = {};
+    if (!::SystemTimeToTzSpecificLocalTime(nullptr,           //__in_opt  LPTIME_ZONE_INFORMATION lpTimeZone,
+                                           &systemTimeUtc,    //__in      LPSYSTEMTIME lpUniversalTime,
+                                           &systemTimeLocal)) //__out     LPSYSTEMTIME lpLocalTime
+        return NoValue();
+
+    double localVarTime = 0;
+    if (!SystemTimeToVariantTime(&systemTimeLocal, //_In_  LPSYSTEMTIME lpSystemTime,
+                                 &localVarTime))   //_Out_ DOUBLE       *pvtime
+        return NoValue();
+
+    return localVarTime;
+}
+#endif
\ No newline at end of file