From: Michael Tremer <michael.tremer@ipfire.org>
Date: Sun, 5 Feb 2023 19:00:29 +0000 (+0000)
Subject: Parse the kernel command line
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=078a04b7257e92f1e100b609f28e3ff82fd068d7;p=people%2Fms%2Fbricklayer.git

Parse the kernel command line

This allows to change any configuration values, but mainly tries to
figure out whether we are being launched on a serial console.

Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>
---

diff --git a/src/python/__init__.py b/src/python/__init__.py
index 16c4d84..6c2f78a 100644
--- a/src/python/__init__.py
+++ b/src/python/__init__.py
@@ -20,6 +20,7 @@
 
 import logging
 import os
+import shlex
 import subprocess
 import sys
 import tempfile
@@ -80,10 +81,15 @@ class Bricklayer(object):
 			# Default timezone
 			"timezone" : "UTC",
 
-			# Enable the serial console
-			"serial-console" : False,
+			# Serial Console
+			"serial-console"          : False,
+			"serial-console-device"   : "ttyS0",
+			"serial-console-baudrate" : 115200,
 		}
 
+		# Parse the kernel command line
+		self._read_cmdline()
+
 		# Read OS information
 		self.os = self._read_os_release()
 
@@ -333,3 +339,65 @@ class Bricklayer(object):
 
 		# Return all supported bootloaders
 		return [bl for bl in _bootloaders if bl.supported]
+
+	def _read_cmdline(self):
+		"""
+			This function parses the kernel command line
+		"""
+		with open("/proc/cmdline") as f:
+			# Read the entire content
+			line = f.readline()
+
+		# Process line for line...
+		for word in shlex.split(line):
+			# Split each word
+			key, delim, value = word.partition("=")
+
+			# Skip any keywords
+			if not key or not value:
+				continue
+
+			if key.startswith("bricklayer."):
+				self._cmdline_handle_keyword(key[11:], value)
+
+			elif key == "console":
+				self._cmdline_handle_console(value)
+
+	def _cmdline_handle_keyword(self, key, value):
+		"""
+			Sets any configuration values from the commandline
+		"""
+		self.settings[key] = value
+
+	def _cmdline_handle_console(self, value):
+		"""
+			Parses the console= kernel parameter
+		"""
+		# Fetch the first part which is the device name
+		device, delim, options = value.partition(",")
+
+		# Break if this option does NOT configure a serial console
+		if not device.startswith("ttyS"):
+			return
+
+		# This function does not properly handle all cases, but I think this
+		# is good enough for now...
+
+		# Remove the "n8" suffix
+		options = options.removesuffix("n8")
+
+		# The rest should
+		try:
+			baudrate = int(options)
+		except (TypeError, ValueError):
+			baudrate = None
+
+		# Store everything in settings
+		self.settings |= {
+			"serial-console"        : True,
+			"serial-console-device" : device,
+		}
+
+		# Store baudrate if set
+		if baurate:
+			self.settings["serial-console-baudrate"] = baudrate