fix: detect bootloader in more difficult cases (#7325)

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

packages/zwave-js/src/lib/test/driver/bootloaderDetection.test.ts

@@ -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