From bb45bee7f870989bc7688f4ef4f82f7bb5581c0e Mon Sep 17 00:00:00 2001
From: Frank <91616163+softhack007@users.noreply.github.com>
Date: Sun, 27 Aug 2023 23:01:55 +0200
Subject: [PATCH] oappend() debug message when buffer is full

oappend() silently discards strings when the buffer is full, leading to strange effects like half-working UI pages.

The new debug message will help developers to understand what could be wrong.
---
 wled00/util.cpp | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/wled00/util.cpp b/wled00/util.cpp
index b8dea2555..57f221d43 100644
--- a/wled00/util.cpp
+++ b/wled00/util.cpp
@@ -148,8 +148,14 @@ bool oappendi(int i)
 bool oappend(const char* txt)
 {
   uint16_t len = strlen(txt);
-  if (olen + len >= SETTINGS_STACK_BUF_SIZE)
+  if (olen + len >= SETTINGS_STACK_BUF_SIZE) {
+#ifdef WLED_DEBUG
+    DEBUG_PRINT(F("oappend() buffer overflow. Cannnot append "));
+    DEBUG_PRINT(len); DEBUG_PRINT(F(" bytes \t\""));
+    DEBUG_PRINT(txt); DEBUG_PRINTLN(F("\""));
+#endif
     return false;        // buffer full
+  }
   strcpy(obuf + olen, txt);
   olen += len;
   return true;