blob: 93f585410c26310319af9f492d5e168e08a36358 [file] [log] [blame]
#!/usr/bin/env python
# Copyright 2007 Google Inc.
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# See the License for the specific language governing permissions and
# limitations under the License.
"""Modify pdb to work with the devappserver2 sandbox."""
import sys
import threading
def install(config):
"""Install the necessary changes to pdb.
Monkeypatch pdb so that it can be used in the devappserver sandbox. Must
be called after the sandbox has been installed but before stdin/stdout
objects have been reassigned.
config: The runtime_config_pb2.Config to use to configure the sandbox.
# Import here (i.e. after sandbox installed) to get the post sandbox pdb.
# Extremely important so that we monkeypatch the same pdb the apps can
# import.
import pdb as pdb_postsandbox
# Save stdin/stdout as the references will not be available when user
# code runs.
real_stdin = sys.stdin
real_stdout = sys.stdout
# Capture the original Pdb so we can forward the __init__ call after
# monkeypatching (if not captured, forwarding the call results in infinite
# recursion).
pdb_premonkeypatch = pdb_postsandbox.Pdb
if config.threadsafe or config.max_instances != 1:
warning = """
* WARNING: please read before using PDB:
lock = threading.Lock()
warning = ''
class _Pdb(pdb_postsandbox.Pdb):
_warning_written = False
# TODO: improve argument handling so if new arguments are added
# in the future or the defaults change, this does not need to be updated.
def __init__(self, completekey='tab', stdin=None, stdout=None, skip=None):
if stdin is None:
stdin = real_stdin
if stdout is None:
stdout = real_stdout
# Pdb is old style class so no super().
pdb_premonkeypatch.__init__(self, completekey, stdin, stdout, skip)
if warning:
with lock:
# Note: while the goal is to write the warning only one time, it
# may be written multiple times (once each per instance).
if not _Pdb._warning_written:
_Pdb._warning_written = True
pdb_postsandbox.Pdb = _Pdb