Fix incorrect error when logfile exists and is writeable in non-write…

…able dir

Ref #937, ref #941, ref #666

irrd/daemon/main.py

@@ -99,12 +99,15 @@ def main():
         os.setegid(gid)
         os.seteuid(uid)
         if staged_logfile_path:
-            staged_logfile_dir = Path(staged_logfile_path).parent
-            if not os.access(staged_logfile_dir, os.W_OK, effective_ids=True):
-                logging.critical(
-                    f"Unable to start: logfile {staged_logfile_path} not writable by UID {uid} / GID {gid}"
-                )
-                return
+            # First check if a writable file already exists, if not,
+            # if we have permission to create the file.
+            if not os.access(staged_logfile_path, os.W_OK, effective_ids=True):
+                staged_logfile_dir = Path(staged_logfile_path).parent
+                if not os.access(staged_logfile_dir, os.W_OK, effective_ids=True):
+                    logging.critical(
+                        f"Unable to start: logfile {staged_logfile_path} not writable by UID {uid} / GID {gid}"
+                    )
+                    return
 
     with daemon.DaemonContext(**daemon_kwargs):
         config_init(args.config_file_path)