baseimage-tutorial-framework/lib/tfw/components/history_monitor.py

106 lines
3.0 KiB
Python

# Copyright (C) 2018 Avatao.com Innovative Learning Kft.
# All Rights Reserved. See LICENSE file for details.
from os.path import dirname
from re import findall
from re import compile as compileregex
from abc import ABC, abstractmethod
from watchdog.events import PatternMatchingEventHandler
from tfw.mixins.callback_mixin import CallbackMixin
from tfw.mixins.observer_mixin import ObserverMixin
from tfw.decorators.rate_limiter import RateLimiter
class CallbackEventHandler(PatternMatchingEventHandler, ABC):
def __init__(self, files, *callbacks):
super().__init__(files)
self.callbacks = callbacks
@RateLimiter(rate_per_second=2)
def on_modified(self, event):
for callback in self.callbacks:
callback()
class HistoryMonitor(CallbackMixin, ObserverMixin, ABC):
"""
Abstract class capable of monitoring and parsing a history file such as
bash HISTFILEs. Monitoring means detecting when the file was changed and
notifying subscribers about new content in the file.
This is useful for monitoring CLI sessions.
To specify a custom HistoryMonitor inherit from this class and override the
command pattern property and optionally the sanitize_command method.
See examples below.
"""
def __init__(self, histfile):
self.histfile = histfile
self._history = []
self._last_length = len(self._history)
self.observer.schedule(
CallbackEventHandler(
[self.histfile],
self._fetch_history,
self._invoke_callbacks
),
dirname(self.histfile)
)
@property
def history(self):
return self._history
def _fetch_history(self):
self._last_length = len(self._history)
with open(self.histfile, 'r') as ifile:
pattern = compileregex(self.command_pattern)
data = ifile.read()
self._history = [
self.sanitize_command(command)
for command in findall(pattern, data)
]
@property
@abstractmethod
def command_pattern(self):
raise NotImplementedError
def sanitize_command(self, command):
# pylint: disable=no-self-use
return command
def _invoke_callbacks(self):
if self._last_length < len(self._history):
self._execute_callbacks(self.history)
class BashMonitor(HistoryMonitor):
"""
HistoryMonitor for monitoring bash CLI sessions.
This requires the following to be set in bash
(note that this is done automatically by TFW):
PROMPT_COMMAND="history -a"
shopt -s cmdhist
shopt -s histappend
unset HISTCONTROL
"""
@property
def command_pattern(self):
return r'.+'
def sanitize_command(self, command):
return command.strip()
class GDBMonitor(HistoryMonitor):
"""
HistoryMonitor to monitor GDB sessions.
For this to work "set trace-commands on" must be set in GDB.
"""
@property
def command_pattern(self):
return r'(?<=\n)\+(.+)\n'