Added some context to MapViewOfFile exception emit

1 files changed, 6 insertions, 2 deletions

diff --git a/zencore/iobuffer.cpp b/zencore/iobuffer.cpp
index b8dd62840..136c065d0 100644
--- a/zencore/iobuffer.cpp
+++ b/zencore/iobuffer.cpp
@@ -171,6 +171,8 @@ RwLock g_MappingLock;
 void
 IoBufferExtendedCore::Materialize() const
 {
+	using namespace fmt::literals;
+
 	// The synchronization scheme here is very primitive, if we end up with
 	// a lot of contention we can make it more fine-grained
 
@@ -199,16 +201,18 @@ IoBufferExtendedCore::Materialize() const
 
 	const uint64_t MapOffset				= m_FileOffset & ~0xffffull;
 	const uint64_t MappedOffsetDisplacement = m_FileOffset - MapOffset;
+	const uint64_t MapSize					= m_DataBytes + MappedOffsetDisplacement;
 
 	void* MappedBase = MapViewOfFile(m_MmapHandle,
 									 /* dwDesiredAccess */ FILE_MAP_READ,
 									 /* FileOffsetHigh */ uint32_t(MapOffset >> 32),
 									 /* FileOffsetLow */ uint32_t(MapOffset & 0xffFFffFFu),
-									 /* dwNumberOfBytesToMap */ m_DataBytes + MappedOffsetDisplacement);
+									 /* dwNumberOfBytesToMap */ MapSize);
 
 	if (MappedBase == nullptr)
 	{
-		throw std::system_error(std::error_code(::GetLastError(), std::system_category()), "MapViewOfFile failed");
+		throw std::system_error(std::error_code(::GetLastError(), std::system_category()),
+								"MapViewOfFile failed (offset {#x}, size {#x}"_format(MapOffset, MapSize));
 	}
 
 	m_MappedPointer = MappedBase;