From 96c7ed19ce3f9c6a6c5c15dbfe0e2348dca266dc Mon Sep 17 00:00:00 2001
From: mchesser <michael.chesser@adelaide.edu.au>
Date: Tue, 7 Nov 2023 16:17:06 +1030
Subject: [PATCH] Handle zero-length SYSEX messages

Check that the `storedInputData` buffer is not empty before reading the command ID from the buffer.

Fixes: #151
---
 src/ConfigurableFirmata.cpp | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/ConfigurableFirmata.cpp b/src/ConfigurableFirmata.cpp
index 03f3bbb..6f46656 100644
--- a/src/ConfigurableFirmata.cpp
+++ b/src/ConfigurableFirmata.cpp
@@ -213,6 +213,10 @@ int FirmataClass::available(void)
  */
 void FirmataClass::processSysexMessage(void)
 {
+  if (sysexBytesRead == 0) {
+    return;
+  }
+
   switch (storedInputData[0]) { //first byte in buffer is command
     case REPORT_FIRMWARE:
       printFirmwareVersion();