#!/usr/bin/env python
# -*- coding: utf-8 -*-
# subset of subprocess built-in module using posix_spawn rather than fork.
from __future__ import print_function
from __future__ import absolute_import
import os
import signal
import posix_spawn
PIPE = "42"
class Popen(object):
def __init__(self, args, stdin=None, stdout=None):
self.returncode = None
self.stdout = None
self.stdin = None
# TODO: stderr
file_actions = posix_spawn.FileActions()
if stdout is not None:
# child's stdout, child 2 parent pipe
c2pread, c2pwrite = os.pipe()
# attach child's stdout to writing en of c2p pipe
file_actions.add_dup2(c2pwrite, 1)
# close other end
file_actions.add_close(c2pread)
if stdin is not None:
# child's stdin, parent to child pipe
p2cread, p2cwrite = os.pipe()
# attach child's stdin to reading en of p2c pipe
file_actions.add_dup2(p2cread, 0)
# close other end
file_actions.add_close(p2cwrite)
self.pid = posix_spawn.posix_spawnp(args[0], args, file_actions=file_actions)
if stdout is not None:
self.stdout = os.fdopen(c2pread)
os.close(c2pwrite)
if stdin is not None:
self.stdin = os.fdopen(p2cwrite, 'w')
os.close(p2cread)
def _wait(self):
if self.returncode is None:
self.returncode = os.waitpid(self.pid, 0)[1]
def communicate(self):
if self.stdin is not None:
self.stdin.close()
self.stdin = None
if self.stdout is not None:
stdoutdata = self.stdout.read()
else:
stdoutdata = ""
# TODO
stderrdata = ""
self._wait()
if self.stdout is not None:
self.stdout.close()
self.stdout = None
return (stdoutdata, stderrdata)
def wait(self):
if self.stdin is not None:
self.stdin.close()
self.stdin = None
self._wait()
if self.stdout is not None:
self.stdout.close()
self.stdout = None
return self.returncode
def poll(self):
if self.returncode is None:
pid, ret = os.waitpid(self.pid, os.WNOHANG)
if (pid, ret) != (0, 0):
self.returncode = ret
if self.stdin is not None:
self.stdin.close()
self.stdin = None
if self.stdout is not None:
self.stdout.close()
self.stdout = None
return self.returncode
def kill(self):
os.kill(self.pid, signal.SIGKILL)
if self.stdin is not None:
self.stdin.close()
self.stdin = None
if self.stdout is not None:
self.stdout.close()
self.stdout = None
def call(*args):
cmd = []
if isinstance(args[0], str):
if len(args) == 1:
# oversimplified splitting of arguments,
# TODO: care about use of simple and double quotes
cmd = args[0].split()
else:
cmd = args
elif isinstance(args[0], list) and len(args) == 1:
cmd = args[0]
else:
raise Exception("Wrong arguments passed to subprocess.call")
pid = posix_spawn.posix_spawnp(cmd[0], cmd)
return os.waitpid(pid, 0)
if __name__ == '__main__':
# unit test
p = Popen(["tr", "abc", "def"], stdin=PIPE, stdout=PIPE)
p.stdin.write("blah")
p.stdin.close()
print(p.stdout.read())
p.wait()
p = Popen(["tr", "abc", "def"], stdin=PIPE, stdout=PIPE)
p.stdin.write("blah")
print(p.communicate())
call("echo blah0")
call(["echo", "blah1"])
call("echo", "blah2")