[utils/lfs] Use custom configparser wrapper

The main reason is to prevent user configs from being overwritten
and also to only actually write the config file if it has been
modified from within Legendary itself.

Closes #279

legendary/lfs/lgndry.py

@@ -2,12 +2,12 @@
 
 import json
 import os
-import configparser
 import logging
 
 from pathlib import Path
 
 from legendary.models.game import *
+from legendary.utils.config import LGDConf
 from legendary.utils.lfs import clean_filename
 
 
@@ -29,7 +29,7 @@ class LGDLFS:
         # EGS metadata
         self._game_metadata = dict()
         # Config with game specific settings (e.g. start parameters, env variables)
-        self.config = configparser.ConfigParser(comment_prefixes='/', allow_no_value=True)
+        self.config = LGDConf(comment_prefixes='/', allow_no_value=True)
         self.config.optionxform = str
 
         # ensure folders exist.
@@ -65,7 +65,14 @@ class LGDLFS:
                                  f'{e!r}, please remove manually')
 
         # try loading config
-        self.config.read(os.path.join(self.path, 'config.ini'))
+        try:
+            self.config.read(os.path.join(self.path, 'config.ini'))
+        except Exception as e:
+            self.log.error(f'Unable to read configuration file, please ensure that file is valid! '
+                           f'(Error: {repr(e)})')
+            self.log.warning(f'Continuing with blank config in safe-mode...')
+            self.config.read_only = True
+
         # make sure "Legendary" section exists
         if 'Legendary' not in self.config:
             self.config['Legendary'] = dict()
@@ -261,6 +268,16 @@ class LGDLFS:
         return [InstalledGame.from_json(i) for i in self._installed.values()]
 
     def save_config(self):
+        # do not save if in read-only mode or file hasn't changed
+        if self.config.read_only or not self.config.modified:
+            return
+        # if config file has been modified externally, back-up the user-modified version before writing
+        if (modtime := int(os.stat(os.path.join(self.path, 'config.ini')).st_mtime)) != self.config.modtime:
+            new_filename = f'config.{modtime}.ini'
+            self.log.warning(f'Configuration file has been modified while legendary was running, '
+                             f'user-modified config will be renamed to "{new_filename}"...')
+            os.rename(os.path.join(self.path, 'config.ini'), os.path.join(self.path, new_filename))
+
         with open(os.path.join(self.path, 'config.ini'), 'w') as cf:
             self.config.write(cf)
 

legendary/utils/config.py

@@ -0,0 +1,31 @@
+import configparser
+import os
+
+
+class LGDConf(configparser.ConfigParser):
+    def __init__(self, *args, **kwargs):
+        self.modified = False
+        self.read_only = False
+        self.modtime = None
+        super().__init__(*args, **kwargs)
+
+    def read(self, filename):
+        # if config file exists, save modification time
+        if os.path.exists(filename):
+            self.modtime = int(os.stat(filename).st_mtime)
+
+        return super().read(filename)
+
+    def set(self, *args, **kwargs):
+        if self.read_only:
+            return
+
+        self.modified = True
+        super().set(*args, **kwargs)
+
+    def __setitem__(self, key, value):
+        if self.read_only:
+            return
+
+        self.modified = True
+        super().__setitem__(key, value)