From de9e8e024b2fd811f10a75ee8933a6d10f5f3cc9 Mon Sep 17 00:00:00 2001
From: Ivan Grokhotkov <ivan@espressif.com>
Date: Fri, 13 Oct 2017 02:17:06 +0800
Subject: [PATCH] pgmspace: zero out memory in strncpy_P (#2633)

strncpy should write 'size' characters, padding with zeroes if src is
shorter than 'size'.
---
 cores/esp8266/pgmspace.cpp | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/cores/esp8266/pgmspace.cpp b/cores/esp8266/pgmspace.cpp
index ed81039f46..e705a32f64 100644
--- a/cores/esp8266/pgmspace.cpp
+++ b/cores/esp8266/pgmspace.cpp
@@ -147,6 +147,7 @@ void* memmem_P(const void* buf, size_t bufSize, PGM_VOID_P findP, size_t findPSi
 
 
 char* strncpy_P(char* dest, PGM_P src, size_t size) {
+    bool size_known = (size != SIZE_IRRELEVANT);
     const char* read = src;
     char* write = dest;
     char ch = '.';
@@ -156,6 +157,14 @@ char* strncpy_P(char* dest, PGM_P src, size_t size) {
         *write++ = ch;
         size--;
     }
+    if (size_known)
+    {
+        while (size > 0)
+        {
+            *write++ = 0;
+            size--;
+        }
+    }
 
     return dest;
 }