From 7de7ef8e8c80fa8bf54739d613038a982564c4df Mon Sep 17 00:00:00 2001
From: Frank <91616163+softhack007@users.noreply.github.com>
Date: Mon, 3 Jul 2023 17:00:43 +0200
Subject: [PATCH] fix some crashes when changing presets

This fixes some of the crashes I had when changing presets.

still not a full solution ...
---
 wled00/FX_fcn.cpp | 5 +++--
 wled00/json.cpp   | 4 ++--
 2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/wled00/FX_fcn.cpp b/wled00/FX_fcn.cpp
index 2550853cb..a3383640b 100644
--- a/wled00/FX_fcn.cpp
+++ b/wled00/FX_fcn.cpp
@@ -90,7 +90,7 @@ Segment::Segment(const Segment &orig) {
   if (orig.name) { name = new char[strlen(orig.name)+1]; if (name) strcpy(name, orig.name); }
   if (orig.data) { if (allocateData(orig._dataLen)) memcpy(data, orig.data, orig._dataLen); }
   if (orig._t)   { _t = new Transition(orig._t->_dur, orig._t->_briT, orig._t->_cctT, orig._t->_colorT); }
-  if (orig.leds && !Segment::_globalLeds) { leds = (CRGB*)malloc(sizeof(CRGB)*length()); if (leds) memcpy(leds, orig.leds, sizeof(CRGB)*length()); }
+  if (orig.leds && !Segment::_globalLeds && length() > 0) { leds = (CRGB*)malloc(sizeof(CRGB)*length()); if (leds) memcpy(leds, orig.leds, sizeof(CRGB)*length()); }
 }
 
 // move constructor
@@ -125,7 +125,7 @@ Segment& Segment::operator= (const Segment &orig) {
     if (orig.name) { name = new char[strlen(orig.name)+1]; if (name) strcpy(name, orig.name); }
     if (orig.data) { if (allocateData(orig._dataLen)) memcpy(data, orig.data, orig._dataLen); }
     if (orig._t)   { _t = new Transition(orig._t->_dur, orig._t->_briT, orig._t->_cctT, orig._t->_colorT); }
-    if (orig.leds && !Segment::_globalLeds) { leds = (CRGB*)malloc(sizeof(CRGB)*length()); if (leds) memcpy(leds, orig.leds, sizeof(CRGB)*length()); }
+    if (orig.leds && !Segment::_globalLeds && length() > 0) { leds = (CRGB*)malloc(sizeof(CRGB)*length()); if (leds) memcpy(leds, orig.leds, sizeof(CRGB)*length()); }
   }
   return *this;
 }
@@ -547,6 +547,7 @@ uint16_t Segment::virtualLength() const {
   }
 #endif
   uint16_t groupLen = groupLength();
+  if (groupLen < 1) groupLen = 1;          // prevent division by zero - better safe than sorry ...
   uint16_t vLength = (length() + groupLen - 1) / groupLen;
   if (mirror) vLength = (vLength + 1) /2;  // divide by 2 if mirror, leave at least a single LED
   return vLength;
diff --git a/wled00/json.cpp b/wled00/json.cpp
index ef74267d4..0d9dd7268 100644
--- a/wled00/json.cpp
+++ b/wled00/json.cpp
@@ -34,7 +34,7 @@ bool deserializeSegment(JsonObject elem, byte it, byte presetId)
 
   uint16_t start = elem["start"] | seg.start;
   if (stop < 0) {
-    uint16_t len = elem["len"];
+    int len = elem["len"];
     stop = (len > 0) ? start + len : seg.stop;
   }
   // 2D segments
@@ -473,7 +473,7 @@ void serializeSegment(JsonObject& root, Segment& seg, byte id, bool forPreset, b
       root[F("stopY")]  = seg.stopY;
     }
   }
-  if (!forPreset) root["len"] = seg.stop - seg.start;
+  if (!forPreset) root["len"] = (seg.stop >= seg.start) ? (seg.stop - seg.start) : 0;
   root["grp"]    = seg.grouping;
   root[F("spc")] = seg.spacing;
   root[F("of")]  = seg.offset;