From a7ee6054b5b4cfe0dc9011d76ee1f119cf4b8fa2 Mon Sep 17 00:00:00 2001
From: s-hadinger <49731213+s-hadinger@users.noreply.github.com>
Date: Fri, 17 Jan 2025 22:26:46 +0100
Subject: [PATCH] Berry 'serial.read()' read only 'n' bytes (#22835)

---
 CHANGELOG.md                                           | 1 +
 tasmota/tasmota_xdrv_driver/xdrv_52_3_berry_serial.ino | 8 ++++++++
 2 files changed, 9 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 0dee27a08..8c20391b0 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -9,6 +9,7 @@ All notable changes to this project will be documented in this file.
 - Command `FileLog 10..14` to enable logging to filesystem using up to 16 log files of 100kB (`#define FILE_LOG_SIZE 100`)
 - I2S Opus stream and file support for opus/aac (#22795)
 - I2S command I2sLoop (#22807)
+- Berry `serial.read()` read only `n` bytes
 
 ### Breaking Changed
 
diff --git a/tasmota/tasmota_xdrv_driver/xdrv_52_3_berry_serial.ino b/tasmota/tasmota_xdrv_driver/xdrv_52_3_berry_serial.ino
index e0efe5ae0..7b0809217 100644
--- a/tasmota/tasmota_xdrv_driver/xdrv_52_3_berry_serial.ino
+++ b/tasmota/tasmota_xdrv_driver/xdrv_52_3_berry_serial.ino
@@ -143,10 +143,18 @@ extern "C" {
   int32_t b_serial_read(struct bvm *vm) {
     be_getmember(vm, 1, ".p");
     TasmotaSerial * ser = (TasmotaSerial *) be_tocomptr(vm, -1);
+    int32_t max_lex = -1;     // -1 means unlimited
+    int32_t argc = be_top(vm); // Get the number of arguments
+    if (argc >= 2 && be_isint(vm, 2)) {
+      max_lex = be_toint(vm, 2);
+    }
     if (ser) {
       int32_t len = ser->available();
       if (len < 0) { len = 0; }
       if (len > 0) {
+        if (max_lex >= 0 && len > max_lex) {
+          len = max_lex;
+        }
         // read bytes on stack
         char * rx_buf = new char[len];
         len = ser->read(rx_buf, len);