From 58c6521bbf45bfc4c0d7896247a28fa5d08407ce Mon Sep 17 00:00:00 2001
From: Yeo Kheng Meng <yeokm1@gmail.com>
Date: Tue, 25 Oct 2016 23:17:24 +0800
Subject: [PATCH] Correct issue where sometimes the bytesRead can be -1
 especially when read() is called for the first time

---
 Sources/SwiftSerial.swift | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/Sources/SwiftSerial.swift b/Sources/SwiftSerial.swift
index d7cae99..d489b7a 100644
--- a/Sources/SwiftSerial.swift
+++ b/Sources/SwiftSerial.swift
@@ -380,7 +380,16 @@ extension SerialPort {
         }
 
         let bytesRead = try readBytes(into: buffer, size: length)
-        let data = Data(bytes: buffer, count: bytesRead)
+
+        var data : Data
+
+        if bytesRead > 0 {
+            data = Data(bytes: buffer, count: bytesRead)
+        } else {
+            //This is to avoid the case where bytesRead can be negative causing problems allocating the Data buffer
+       	    data = Data(bytes: buffer, count: 0)
+        }
+
         return data
     }
 
@@ -390,6 +399,7 @@ extension SerialPort {
 
         while remainingBytesToRead > 0 {
             let data = try readData(ofLength: remainingBytesToRead)
+
             if let string = String(data: data, encoding: String.Encoding.utf8) {
                 result += string
                 remainingBytesToRead -= data.count