From 93091f5cd0567832316171a1a3ec5f69c779c85a Mon Sep 17 00:00:00 2001
From: Dominic Griesel <dominic.griesel@nabucasa.com>
Date: Sun, 27 Oct 2024 22:13:08 +0100
Subject: [PATCH] fix: detect bootloader in more difficult cases

---
 .../src/serialport/ZWaveSerialPortBase.ts     | 22 ++++++++++++++++---
 .../test/driver/bootloaderDetection.test.ts   |  7 +++---
 2 files changed, 23 insertions(+), 6 deletions(-)

diff --git a/packages/serial/src/serialport/ZWaveSerialPortBase.ts b/packages/serial/src/serialport/ZWaveSerialPortBase.ts
index 50bf85b7ae8b..2c880173e0f3 100644
--- a/packages/serial/src/serialport/ZWaveSerialPortBase.ts
+++ b/packages/serial/src/serialport/ZWaveSerialPortBase.ts
@@ -161,9 +161,25 @@ export class ZWaveSerialPortBase extends PassThrough {
 				const str = (data as Buffer).toString("ascii")
 					// like .trim(), but including null bytes
 					.replaceAll(/^[\s\0]+|[\s\0]+$/g, "");
-				this.mode = str.startsWith(bootloaderMenuPreamble)
-					? ZWaveSerialMode.Bootloader
-					: ZWaveSerialMode.SerialAPI;
+
+				if (str.startsWith(bootloaderMenuPreamble)) {
+					// We're sure we're in bootloader mode
+					this.mode = ZWaveSerialMode.Bootloader;
+				} else if (
+					(data as Buffer).every((b) =>
+						b === 0x00
+						|| b === 0x0a
+						|| b === 0x0d
+						|| (b >= 0x20 && b <= 0x7e)
+					) && (data as Buffer).some((b) => b >= 0x20 && b <= 0x7e)
+				) {
+					// Only printable line breaks, null bytes and at least one printable ASCII character
+					// --> We're pretty sure we're in bootloader mode
+					this.mode = ZWaveSerialMode.Bootloader;
+				} else {
+					// We're in Serial API mode
+					this.mode = ZWaveSerialMode.SerialAPI;
+				}
 			}
 
 			// On Windows, writing to the parsers immediately seems to lag the event loop
diff --git a/packages/zwave-js/src/lib/test/driver/bootloaderDetection.test.ts b/packages/zwave-js/src/lib/test/driver/bootloaderDetection.test.ts
index 3d36d73752c3..537768a09b6f 100644
--- a/packages/zwave-js/src/lib/test/driver/bootloaderDetection.test.ts
+++ b/packages/zwave-js/src/lib/test/driver/bootloaderDetection.test.ts
@@ -6,7 +6,7 @@ integrationTest(
 	"The bootloader is detected when received in smaller chunks",
 	{
 		// Reproduction for issue #7316
-		// debug: true,
+		debug: true,
 
 		additionalDriverOptions: {
 			allowBootloaderOnly: true,
@@ -19,12 +19,13 @@ integrationTest(
 					// 	ctrl.length === 1
 					// 	&& (ctrl[0] === MessageHeaders.NAK || ctrl[0] === 0x32)
 					// ) {
+					// I've seen logs with as few as 5 bytes in the first chunk
 					self.serial.emitData(
-						Buffer.from("\0\r\nGecko Bootloa", "ascii"),
+						Buffer.from("\0\r\nGeck", "ascii"),
 					);
 					await wait(20);
 					self.serial.emitData(Buffer.from(
-						`der v2.05.01
+						`o Bootloader v2.05.01
 1. upload gbl
 2. run
 3. ebl info