open port params separate for mac

Sources/SwiftSerial.swift

@@ -233,16 +233,24 @@ public class SerialPort {
             throw PortError.mustReceiveOrTransmit
         }
 
+        var readWriteParam : Int32
+
         if receive && transmit {
-            fileDescriptor = open(path, O_RDWR | O_NOCTTY)
+            readWriteParam = O_RDWR
         } else if receive {
-            fileDescriptor = open(path, O_RDONLY | O_NOCTTY)
+            readWriteParam = O_RDONLY
         } else if transmit {
-            fileDescriptor = open(path, O_WRONLY | O_NOCTTY)
+            readWriteParam = O_WRONLY
         } else {
             fatalError()
         }
 
+    #if os(Linux)
+        fileDescriptor = open(path, readWriteParam | O_NOCTTY)
+    #elseif os(OSX)
+        fileDescriptor = open(path, readWriteParam | O_NOCTTY | O_EXLOCK | O_NONBLOCK)
+    #endif
+
         // Throw error if open() failed
         if fileDescriptor == PortError.failedToOpen.rawValue {
             throw PortError.failedToOpen
@@ -259,10 +267,13 @@ public class SerialPort {
                             useHardwareFlowControl: Bool = false,
                             useSoftwareFlowControl: Bool = false,
                             processOutput: Bool = false) {
+        print("top")
+        
         guard let fileDescriptor = fileDescriptor else {
             return
         }
 
+
         // Set up the control structure
         var settings = termios()