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#!/usr/bin/env python
class Request:
Commands = {}
@staticmethod
def Register(name):
def decorate(cls):
Request.Commands[name] = cls
return cls
return decorate
@staticmethod
def ReadCommand(shell):
cmd = shell.read_line().strip()
request = Request.Commands[cmd](shell)
return request
def __init__(self, shell):
self.shell = shell
def read_params(self):
pass
def execute(self):
raise NotImplementedError()
@Request.Register("noop")
class NoopRequest(Request):
def execute(self):
pass
@Request.Register("ping")
class PingRequest(Request):
def execute(self):
self.shell.status("ALIVE")
@Request.Register("exit")
class ExitRequest(Request):
def execute(self):
self.shell.exit()
@Request.Register("glob")
class GlobRequest(Request):
def read_params(self):
self.pattern = self.shell.read_line()
def execute(self):
from glob import glob
results = glob(self.pattern)
self.shell.write("%i\n" % len(results))
for result in results:
self.shell.write(result+"\n")
@Request.Register("exec")
class ExecRequest(Request):
def read_params(self):
self.cmd = self.shell.read_line()
def execute(self):
from subprocess import Popen, PIPE
proc = Popen(self.cmd, shell=True, stdout=PIPE, stderr=PIPE, bufsize=-1)
stdout, stderr = proc.communicate()
self.shell.write("%i\n" % proc.returncode)
self.shell.write_blob(stdout)
self.shell.write_blob(stderr)
class Shell:
def __init__(self, input_stream, output_stream, status_stream,
bork_action = None):
self.__input_stream__ = input_stream
self.__output_stream__ = output_stream
self.__status_stream__ = status_stream
self.__bork_action__ = bork_action or self.exit
self.__exit__ = False
self.__req_counter__ = 0
def loop(self):
while self.__exit__ == False:
self.show_prompt()
try: request = Request.ReadCommand(self)
except KeyboardInterrupt:
self.exit()
except KeyError:
self.status("UNKNOWN COMMAND");
self.bork()
else:
try: request.read_params()
except KeyboardInterrupt:
pass
else:
self.__req_counter__ += 1
try:
request.execute()
except KeyboardInterrupt:
self.status("INTERRUPTED");
def exit(self):
self.__exit__ = True
def bork(self):
self.__bork_action__()
def show_prompt(self):
self.write("#%i#\n" % self.__req_counter__)
def status(self, str):
print >> self.__status_stream__, str
def write(self, msg):
self.__output_stream__.write(msg)
def write_blob(self, blob):
self.write("%i\n" % len(blob))
self.write(str(blob)+"\n")
def read_line(self):
while True:
try:
return self.__input_stream__.readline().strip()
except IOError:
pass
def read_blob(self, length):
try:
blob = self.__input_stream__.read(length)
assert self.__input_stream__.read(1) == "\n"
except:
raise IOError()
else:
return blob
if __name__ == "__main__":
from sys import stdin, stdout, stderr, exit
from signal import signal, SIGUSR1
def handler(signum, frame):
print >> stderr, "ALIVE"
signal(SIGUSR1, handler)
def bork():
exit(-1)
Shell(stdin, stdout, stderr, bork_action = bork).loop()
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