file_manager: relax registration requirements

Use EAFP techniques to test for directory read permission
during registration.  If access fails continue with registration.
This allows users to potentially fix an issue without restarting.
Inotify failures always require a restart to resolve.

Signed-off-by:  Eric Callahan <[email protected]>

moonraker/components/file_manager/file_manager.py

@@ -268,15 +268,29 @@ def register_directory(self,
                 f"Supplied path ({path}) for ({root}) is invalid. Make sure\n"
                 "that the path exists and is not the file system root.")
             return False
-        permissions = os.R_OK
+        # Check Folder Permissions
+        missing_perms = []
+        try:
+            # Test read
+            os.listdir(path)
+        except PermissionError:
+            missing_perms.append("READ")
+        except Exception:
+            logging.exception(f"Error testing read access for root {root}")
         if full_access:
-            permissions |= os.W_OK
+            if (
+                os.access in os.supports_effective_ids and
+                not os.access(path, os.W_OK, effective_ids=True)
+            ):
+                missing_perms.append("WRITE")
             self.full_access_roots.add(root)
-        if not os.access(path, permissions):
-            self.server.add_warning(
-                f"Moonraker does not have permission to access path "
-                f"({path}) for ({root}).")
-            return False
+        if missing_perms:
+            mpstr = " | ".join(missing_perms)
+            self.server.add_log_rollover_item(
+                f"fm_reg_perms_{root}",
+                f"file_manager: Moonraker has detected the following missing "
+                f"permissions for root folder '{root}': {mpstr}"
+            )
         if path != self.file_paths.get(root, ""):
             self.file_paths[root] = path
             self.server.register_static_file_handler(root, path)
@@ -834,8 +848,14 @@ def _parse_upload_args(self,
         if unzip_ufp:
             filename = os.path.splitext(filename)[0] + ".gcode"
             dest_path = os.path.splitext(dest_path)[0] + ".gcode"
-        if os.path.isfile(dest_path) and not os.access(dest_path, os.W_OK):
-            raise self.server.error(f"File is read-only: {dest_path}")
+        if (
+            os.path.isfile(dest_path) and
+            os.access in os.supports_effective_ids and
+            not os.access(dest_path, os.W_OK, effective_ids=True)
+        ):
+            logging.info(
+                f"Destination file exists and appears to be read-only: {dest_path}"
+            )
         return {
             'root': root,
             'filename': filename,
@@ -1811,17 +1831,41 @@ def add_root_watch(self, root: str, root_path: str) -> None:
         try:
             root_node = InotifyRootNode(self, root, root_path)
         except Exception:
+            logging.exception(f"Inotify: failed to create root node '{root}'")
+            self.server.add_warning(
+                f"file_manager: Failed to create inotify root node {root}. "
+                "See moonraker.log for details.",
+                log=False
+            )
             return
         self.watched_roots[root] = root_node
         if self.initialized:
-            mevts = root_node.scan_node()
+            try:
+                mevts = root_node.scan_node()
+            except Exception:
+                logging.exception(f"Inotify: failed to scan root '{root}'")
+                self.server.add_warning(
+                    f"file_manager: Failed to scan inotify root node '{root}'. "
+                    "See moonraker.log for details.",
+                    log=False
+                )
+                return
             self.log_nodes()
             self.event_loop.register_callback(
                 self._notify_root_updated, mevts, root, root_path)
 
     def initialize(self) -> None:
         for root, node in self.watched_roots.items():
-            evts = node.scan_node()
+            try:
+                evts = node.scan_node()
+            except Exception:
+                logging.exception(f"Inotify: failed to scan root '{root}'")
+                self.server.add_warning(
+                    f"file_manager: Failed to scan inotify root node '{root}'. "
+                    "See moonraker.log for details.",
+                    log=False
+                )
+                continue
             if not evts:
                 continue
             root_path = node.get_path()