From 9f71f47e6f214b4451ab56fc31954d6a755a362d Mon Sep 17 00:00:00 2001
From: Frank <91616163+softhack007@users.noreply.github.com>
Date: Thu, 14 Dec 2023 15:58:45 +0100
Subject: [PATCH] oappend robustness improvement

obuf is reset to nullptr in some cases
---
 wled00/util.cpp | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/wled00/util.cpp b/wled00/util.cpp
index fb8b5e59..520f4bb4 100644
--- a/wled00/util.cpp
+++ b/wled00/util.cpp
@@ -148,11 +148,14 @@ bool oappendi(int i)
 bool oappend(const char* txt)
 {
   uint16_t len = strlen(txt);
-  if (olen + len >= SETTINGS_STACK_BUF_SIZE) {
-    USER_PRINT(F("oappend() error: buffer full. Increase SETTINGS_STACK_BUF_SIZE for "));
-    USER_PRINTF("%2u bytes \t\"", len /*1 + olen + len - SETTINGS_STACK_BUF_SIZE*/);
-    USER_PRINT(txt);
-    USER_PRINTLN(F("\""));
+  if ((obuf == nullptr) || (olen + len >= SETTINGS_STACK_BUF_SIZE)) { // sanity checks
+	if (obuf == nullptr) { USER_PRINTLN(F("oappend() error: obuf == nullptr."));
+	} else {
+	  USER_PRINT(F("oappend() error: buffer full. Increase SETTINGS_STACK_BUF_SIZE for "));
+      USER_PRINTF("%2u bytes \t\"", len /*1 + olen + len - SETTINGS_STACK_BUF_SIZE*/);
+      USER_PRINT(txt);
+      USER_PRINTLN(F("\""));
+	}
     return false;        // buffer full
   }
   strcpy(obuf + olen, txt);