Fix assets path for RetroArch

lutris/runners/libretro.py

@@ -1,5 +1,7 @@
 import os
 from lutris.runners.runner import Runner
+from lutris.util.libretro import RetroConfig
+from lutris.util import system
 from lutris import settings
 
 
@@ -36,6 +38,10 @@ def get_default_config_path():
     return os.path.join(settings.RUNNER_DIR, 'retroarch/retroarch.cfg')
 
 
+def get_default_assets_directory():
+    return os.path.join(settings.RUNNER_DIR, 'retroarch/assets')
+
+
 class libretro(Runner):
     human_name = "libretro"
     description = "Multi system emulator"
@@ -102,10 +108,25 @@ class libretro(Runner):
             super(libretro, self).install(version, downloader, callback)
 
     def get_run_data(self):
+        self.prelaunch()
         return {
             'command': [self.get_executable()] + self.get_runner_parameters()
         }
 
+    def get_config_file(self):
+        return self.runner_config.get('config_file') or get_default_config_path()
+
+    def prelaunch(self):
+        config_file = self.get_config_file()
+        if os.path.exists(config_file):
+            retro_config = RetroConfig(config_file)
+
+            # Change assets path to the Lutris provided one if necessary
+            assets_directory = os.path.expanduser(retro_config['assets_directory'])
+            if system.path_is_empty(assets_directory):
+                retro_config['assets_directory'] = get_default_assets_directory()
+                retro_config.save()
+
     def get_runner_parameters(self):
         parameters = []
         # Fullscreen
@@ -113,9 +134,7 @@ class libretro(Runner):
         if fullscreen:
             parameters.append('--fullscreen')
 
-        config_file = self.runner_config.get('config_file') \
-            or get_default_config_path()
-        parameters.append('--config={}'.format(config_file))
+        parameters.append('--config={}'.format(self.get_config_file()))
         return parameters
 
     def play(self):

lutris/util/libretro.py

@@ -24,7 +24,7 @@ class RetroConfig:
                 value = value.strip("\"")
                 self.config.append((key, value))
 
-    def write(self):
+    def save(self):
         with open(self.config_path, 'w') as config_file:
             for (key, value) in self.config:
                 config_file.write("{} = \"{}\"\n".format(key, value))

lutris/util/system.py

@@ -281,5 +281,12 @@ def path_exists(path):
     return os.path.exists(path)
 
 
+def path_is_empty(path):
+    """Return True is the given path doen't exist or it is an empty directory"""
+    if not path_exists(path):
+        return True
+    return len(os.listdir(path)) == 0
+
+
 def stacktrace():
     traceback.print_stack()