feat: config store

Load a config.json file from the root of the littlefs flash filesystem.

Signed-off-by: Matthias Blankertz <matthias@blankertz.org>

software/src/utils/__init__.py

@@ -2,6 +2,7 @@
 # Copyright (c) 2025 Matthias Blankertz <matthias@blankertz.org>
 
 from utils.buttons import Buttons
+from utils.config import Configuration
 from utils.leds import LedManager
 from utils.mbrpartition import MBRPartition
 from utils.pinindex import get_pin_index
@@ -9,5 +10,5 @@ from utils.playlistdb import BTreeDB, BTreeFileManager
 from utils.sdcontext import SDContext
 from utils.timer import TimerManager
 
-__all__ = ["BTreeDB", "BTreeFileManager", "Buttons", "get_pin_index", "LedManager", "MBRPartition", "SDContext",
+__all__ = ["BTreeDB", "BTreeFileManager", "Buttons", "Configuration", "get_pin_index", "LedManager", "MBRPartition",
-           "TimerManager"]
+           "SDContext", "TimerManager"]

software/src/utils/config.py

@@ -0,0 +1,44 @@
+# SPDX-License-Identifier: MIT
+# Copyright (c) 2025 Matthias Blankertz <matthias@blankertz.org>
+
+from errno import ENOENT
+import json
+import os
+
+
+class Configuration:
+    DEFAULT_CONFIG = {
+    }
+
+    def __init__(self, config_path='/config.json'):
+        self.config_path = config_path
+        try:
+            with open(self.config_path, 'r') as conf_file:
+                self.config = json.load(conf_file)
+        except OSError as ex:
+            if ex.errno == ENOENT:
+                self.config = Configuration.DEFAULT_CONFIG
+                self._save()
+            else:
+                raise
+        except ValueError as ex:
+            print(f"Warning: Could not load configuration {self.config_path}:\n{ex}")
+            self._move_config_to_backup()
+            self.config = Configuration.DEFAULT_CONFIG
+
+    def _move_config_to_backup(self):
+        # Remove old backup
+        try:
+            os.remove(self.config_path + '.bup')
+            os.rename(self.config_path, self.config_path + '.bup')
+        except OSError as ex:
+            if ex.errno != ENOENT:
+                raise
+        os.sync()
+
+    def _save(self):
+        with open(self.config_path + '.new', 'w') as conf_file:
+            json.dump(self.config, conf_file)
+        self._move_config_to_backup()
+        os.rename(self.config_path + '.new', self.config_path)
+        os.sync()