move PathNotAllowed to helpers/errors.py

PathNotAllowed lived in borg.legacy.remote, but borg serve --rest
(non-legacy) now also raises it via check_rest_restrictions, which made
non-legacy code import from the legacy package just for an exception.

It is a generic "repository path not allowed" error, so move it next to
the other cross-cutting Error subclasses in helpers/errors.py and
re-export it from helpers. Pure relocation; exit code stays 83.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/borg/archiver/serve_cmd.py

@@ -1,7 +1,7 @@
 import os
 
 from ..constants import *  # NOQA
-from ..helpers import Error
+from ..helpers import Error, PathNotAllowed
 from ..legacy.remote import RepositoryServer
 
 from ..logger import create_logger
@@ -38,8 +38,6 @@ class ServeMixIn:
 
     @staticmethod
     def check_rest_restrictions(backend, restrict_to_paths, restrict_to_repositories):
-        from ..legacy.remote import PathNotAllowed
-
         if not (restrict_to_paths or restrict_to_repositories):
             return
         if not backend.startswith("FILE:"):

src/borg/helpers/__init__.py

@@ -13,7 +13,7 @@ from ..constants import *  # NOQA
 
 from .datastruct import StableDict, Buffer, EfficientCollectionQueue
 from .errors import Error, ErrorWithTraceback, IntegrityError, DecompressionError, CancelledByUser, CommandError
-from .errors import RTError, modern_ec
+from .errors import RTError, PathNotAllowed, modern_ec
 from .errors import BorgWarning, FileChangedWarning, BackupWarning, IncludePatternNeverMatchedWarning
 from .errors import BackupError, BackupOSError, BackupRaceConditionError, BackupItemExcluded
 from .errors import BackupPermissionError, BackupIOError, BackupFileNotFoundError

src/borg/helpers/errors.py

@@ -76,6 +76,12 @@ class CommandError(Error):
     exit_mcode = 4
 
 
+class PathNotAllowed(Error):
+    """Repository path not allowed: {}."""
+
+    exit_mcode = 83
+
+
 class BorgWarning:
     """Warning: {}"""
 

src/borg/legacy/remote.py

@@ -16,7 +16,7 @@ from subprocess import Popen, PIPE
 import borg.logger
 from .. import __version__
 from ..constants import *  # NOQA
-from ..helpers import Error, ErrorWithTraceback, IntegrityError
+from ..helpers import Error, ErrorWithTraceback, IntegrityError, PathNotAllowed
 from ..helpers import bin_to_hex
 from ..helpers import get_limited_unpacker
 from ..helpers import replace_placeholders
@@ -55,12 +55,6 @@ class ConnectionClosedWithHint(ConnectionClosed):
     exit_mcode = 81
 
 
-class PathNotAllowed(Error):
-    """Repository path not allowed: {}."""
-
-    exit_mcode = 83
-
-
 class InvalidRPCMethod(Error):
     """RPC method {} is not valid."""
 

src/borg/testsuite/legacyrepository_test.py

@@ -8,10 +8,11 @@ import pytest
 from ..legacy.hashindex import NSIndex1
 from ..helpers import Location
 from ..helpers import IntegrityError
+from ..helpers import PathNotAllowed
 from ..helpers import msgpack
 from ..fslocking import Lock, LockFailed
 from ..platformflags import is_win32
-from ..legacy.remote import LegacyRemoteRepository, InvalidRPCMethod, PathNotAllowed
+from ..legacy.remote import LegacyRemoteRepository, InvalidRPCMethod
 from ..legacy.repository import LegacyRepository, LoggedIO
 from ..legacy.repository import MAGIC, MAX_DATA_SIZE, TAG_DELETE, TAG_PUT, TAG_COMMIT
 from ..compress import CNONE