Disk: Predictable behavior for zero length reads

disk/diskreaddriver.cpp

@@ -6,6 +6,9 @@ using namespace icsneo::Disk;
 
 optional<uint64_t> ReadDriver::readLogicalDisk(Communication& com, device_eventhandler_t report,
 	uint64_t pos, uint8_t* into, uint64_t amount, std::chrono::milliseconds timeout) {
+	if(amount == 0)
+		return 0;
+
 	optional<uint64_t> ret;
 
 	// Read into here if we can't read directly into the user buffer

disk/diskwritedriver.cpp

@@ -9,6 +9,9 @@ const APIEvent::Severity WriteDriver::NonatomicSeverity = APIEvent::Severity::Ev
 
 optional<uint64_t> WriteDriver::writeLogicalDisk(Communication& com, device_eventhandler_t report, ReadDriver& readDriver,
 	uint64_t pos, const uint8_t* from, uint64_t amount, std::chrono::milliseconds timeout) {
+	if(amount == 0)
+		return 0;
+
 	optional<uint64_t> ret;
 
 	const uint32_t idealBlockSize = getBlockSizeBounds().second;