From 7e40de226fee6ef7189e9f024ef373dff581a777 Mon Sep 17 00:00:00 2001
From: M Hotchin <35244463+MHotchin@users.noreply.github.com>
Date: Tue, 27 Oct 2020 03:01:41 -0700
Subject: [PATCH] Fixes #4435 - WiFiClient improperly treats zero data
 available for read as an error (#4448)

---
 libraries/WiFi/src/WiFiClient.cpp | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/libraries/WiFi/src/WiFiClient.cpp b/libraries/WiFi/src/WiFiClient.cpp
index e422b636..52df2731 100644
--- a/libraries/WiFi/src/WiFiClient.cpp
+++ b/libraries/WiFi/src/WiFiClient.cpp
@@ -105,7 +105,7 @@ public:
 
     int read(uint8_t * dst, size_t len){
         if(!dst || !len || (_pos == _fill && !fillBuffer())){
-            return -1;
+            return _failed ? -1 : 0;
         }
         size_t a = _fill - _pos;
         if(len <= a || ((len - a) <= (_size - _fill) && fillBuffer() >= (len - a))){
@@ -346,6 +346,9 @@ int WiFiClient::read()
     if(res < 0) {
         return res;
     }
+    if (res == 0) {  //  No data available.
+        return -1;
+    }
     return data;
 }