Fix conversion from FILETIME to file_time_type when using libstdc++

src/internal/dateutil.cpp

@@ -20,31 +20,40 @@ using FileTimeDuration = std::chrono::duration< int64_t, FileTimeTickRate >;
 // Seconds between 01/01/1601 (NT epoch) and 01/01/1970 (Unix epoch):
 constexpr std::chrono::seconds nt_to_unix_epoch{ -11644473600 };
 
-#ifndef _WIN32
+#if defined( BIT7Z_USE_STANDARD_FILESYSTEM ) && defined( __GLIBCXX__ )
+// Seconds between 01/01/1970 (Unix epoch) and 01/01/2174 (libstdc++'s file_clock epoch).
+constexpr std::chrono::seconds libstdcpp_file_clock_epoch{ -6437664000 };
+#endif
 
+#ifndef _WIN32
 auto FILETIME_to_file_time_type( FILETIME fileTime ) -> fs::file_time_type {
     const FileTimeDuration fileTimeDuration{
-        ( static_cast< int64_t >( fileTime.dwHighDateTime ) << 32 ) + fileTime.dwLowDateTime
+        ( static_cast< std::uint64_t >( fileTime.dwHighDateTime ) << 32ull ) + fileTime.dwLowDateTime
     };
 
-    const auto unixEpoch = fileTimeDuration + nt_to_unix_epoch;
-    return fs::file_time_type{ std::chrono::duration_cast< std::chrono::system_clock::duration >( unixEpoch ) };
+    const auto unixFileTime = fileTimeDuration + nt_to_unix_epoch;
+    const auto systemFileTime = std::chrono::duration_cast< fs::file_time_type::clock::duration >( unixFileTime );
+#if defined( BIT7Z_USE_STANDARD_FILESYSTEM ) && defined( __GLIBCXX__ )
+    return fs::file_time_type{ systemFileTime + libstdcpp_file_clock_epoch };
+#else
+    return fs::file_time_type{ systemFileTime };
+#endif
 }
 
-auto time_to_FILETIME( std::time_t timeValue ) -> FILETIME {
+auto time_to_FILETIME( std::time_t value ) -> FILETIME {
     // NOLINTNEXTLINE(*-magic-numbers)
-    const uint64_t timeInSeconds = ( static_cast< uint64_t >( timeValue ) * 10000000ull ) + 116444736000000000;
+    const std::uint64_t timeInSeconds = ( static_cast< std::uint64_t >( value ) * 10000000ull ) + 116444736000000000ull;
     FILETIME fileTime{};
     fileTime.dwLowDateTime = static_cast< DWORD >( timeInSeconds );
-    fileTime.dwHighDateTime = static_cast< DWORD >( timeInSeconds >> 32 );
+    fileTime.dwHighDateTime = static_cast< DWORD >( timeInSeconds >> 32ull );
     return fileTime;
 }
 
 #endif
 
 auto FILETIME_to_time_type( FILETIME fileTime ) -> time_type {
     const FileTimeDuration fileTimeDuration{
-        ( static_cast< int64_t >( fileTime.dwHighDateTime ) << 32 ) + fileTime.dwLowDateTime
+        ( static_cast< std::uint64_t >( fileTime.dwHighDateTime ) << 32ull ) + fileTime.dwLowDateTime
     };
 
     const auto unixEpoch = fileTimeDuration + nt_to_unix_epoch;

src/internal/dateutil.hpp

@@ -23,7 +23,7 @@ namespace bit7z {
 
 auto FILETIME_to_file_time_type( FILETIME fileTime ) -> fs::file_time_type;
 
-auto time_to_FILETIME( std::time_t timeValue ) -> FILETIME;
+auto time_to_FILETIME( std::time_t value ) -> FILETIME;
 
 #endif