Fix for SELinux handling logic (#529)

* Fix for SELinux handling logic

The old procedure was crashing with signal 9 SIGKILL, this should fix that problem

backend/localplatform.py

@@ -43,4 +43,10 @@ def get_log_level() -> int:
     ]
 
 def get_selinux() -> bool:
-    return os.getenv("DECKY_SELINUX", "0") == "1"
+    if ON_LINUX:
+        from subprocess import check_output
+        try:
+          if (check_output("getenforce").decode("ascii").strip("\n") == "Enforcing"): return True
+        except FileNotFoundError:
+          pass
+    return False

backend/updater.py

@@ -209,8 +209,9 @@ class Updater:
                 shutil.move(path.join(getcwd(), download_temp_filename), path.join(getcwd(), download_filename))
                 chmod(path.join(getcwd(), download_filename), 777, False)
                 if get_selinux():
-                    from subprocess import call
+                    from asyncio.subprocess import create_subprocess_exec
-                    call(["chcon", "-t", "bin_t", path.join(getcwd(), download_filename)])
+                    process = await create_subprocess_exec("chcon", "-t", "bin_t", path.join(getcwd(), download_filename))
+                    logger.info(f"Setting the executable flag with chcon returned {await process.wait()}")
 
             logger.info("Updated loader installation.")
             await tab.evaluate_js("window.DeckyUpdater.finish()", False, False)