From db88c828824f38db55e863274137d0f599011511 Mon Sep 17 00:00:00 2001
From: TD-er <gijs.noorlander@gmail.com>
Date: Mon, 18 Mar 2019 01:03:34 +0100
Subject: [PATCH] Fix Small String Optimization misplaced 0 terminator

A fix for some issue introduced in PR #5690
See discussion in https://github.com/esp8266/Arduino/issues/5883
---
 cores/esp8266/WString.cpp       |  5 +++--
 tests/host/core/test_string.cpp | 10 ++++++++++
 2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/cores/esp8266/WString.cpp b/cores/esp8266/WString.cpp
index 4d4fa3bf21..d650e2fa99 100644
--- a/cores/esp8266/WString.cpp
+++ b/cores/esp8266/WString.cpp
@@ -129,6 +129,7 @@ String::~String() {
 // /*********************************************/
 
 inline void String::init(void) {
+    memset(sso_buf, 0, sizeof(sso_buf));
     setSSO(false);
     setCapacity(0);
     setLen(0);
@@ -161,11 +162,11 @@ unsigned char String::changeBuffer(unsigned int maxStrLen) {
             return 1;
         } else { // if bufptr && !sso()
             // Using bufptr, need to shrink into sso_buff
-            char temp[sizeof(sso_buf)];
+            char temp[sizeof(sso_buf)] = {0};
             memcpy(temp, buffer(), maxStrLen);
             free(wbuffer());
             setSSO(true);
-            memcpy(wbuffer(), temp, maxStrLen);
+            memcpy(wbuffer(), temp, sizeof(sso_buf));
             return 1;
         }
     }
diff --git a/tests/host/core/test_string.cpp b/tests/host/core/test_string.cpp
index c2ef68025f..b07b387d07 100644
--- a/tests/host/core/test_string.cpp
+++ b/tests/host/core/test_string.cpp
@@ -83,6 +83,12 @@ TEST_CASE("String constructors", "[core][String]")
     REQUIRE(ssh == "3.14159_abcd");
     String flash = (F("hello from flash"));
     REQUIRE(flash == "hello from flash");
+    const char textarray[6] = {'h', 'e', 'l', 'l', 'o', 0};
+    String hello(textarray);
+    REQUIRE(hello == "hello");
+    String hello2;
+    hello2 = textarray;
+    REQUIRE(hello2 == "hello");
 }
 
 TEST_CASE("String concantenation", "[core][String]")
@@ -360,4 +366,8 @@ TEST_CASE("String SSO works", "[core][String]")
     REQUIRE(s == "0123456789abcdefghijklmnopqrstu");
     REQUIRE(s.length() == 31);
   }
+  s = "0123456789abcde";
+  s = s.substring(s.indexOf('a'));
+  REQUIRE(s == "abcde");
+  REQUIRE(s.length() == 5);
 }