popenasync.py

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################################################################################
"""

Modification of http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/440554

"""

#################################### IMPORTS ###################################

import os
import subprocess
import errno
import time
import sys
import unittest
import tempfile

def geterror ():
    return sys.exc_info()[1]

if sys.version_info >= (3,):
    null_byte = '\x00'.encode('ascii')
else:
    null_byte = '\x00'

mswindows = (sys.platform == "win32")

if mswindows:
    if sys.version_info >= (3,):
        # Test date should be in ascii.
        def encode(s):
            return s.encode('ascii', 'ignore')

        def decode(b):
            return b.decode('ascii', 'ignore')
    else:
        # Strings only; do nothing
        def encode(s):
            return s

        def decode(b):
            return b

    try:
        import ctypes
        from ctypes.wintypes import DWORD
        kernel32 = ctypes.windll.kernel32
        TerminateProcess = ctypes.windll.kernel32.TerminateProcess
        def WriteFile(handle, data, ol = None):
            c_written = DWORD()
            success = ctypes.windll.kernel32.WriteFile(handle,
                ctypes.create_string_buffer(encode(data)), len(data),
                ctypes.byref(c_written), ol)
            return ctypes.windll.kernel32.GetLastError(), c_written.value
        def ReadFile(handle, desired_bytes, ol = None):
            c_read = DWORD()
            buffer = ctypes.create_string_buffer(desired_bytes+1)
            success = ctypes.windll.kernel32.ReadFile(handle, buffer,
                desired_bytes, ctypes.byref(c_read), ol)
            buffer[c_read.value] = null_byte
            return ctypes.windll.kernel32.GetLastError(), decode(buffer.value)
        def PeekNamedPipe(handle, desired_bytes):
            c_avail = DWORD()
            c_message = DWORD()
            if desired_bytes > 0:
                c_read = DWORD()
                buffer = ctypes.create_string_buffer(desired_bytes+1)
                success = ctypes.windll.kernel32.PeekNamedPipe(handle, buffer,
                    desired_bytes, ctypes.byref(c_read), ctypes.byref(c_avail),
                    ctypes.byref(c_message))
                buffer[c_read.value] = null_byte
                return decode(buffer.value), c_avail.value, c_message.value
            else:
                success = ctypes.windll.kernel32.PeekNamedPipe(handle, None,
                    desired_bytes, None, ctypes.byref(c_avail),
                    ctypes.byref(c_message))
                return "", c_avail.value, c_message.value

    except ImportError:
        from win32file import ReadFile, WriteFile
        from win32pipe import PeekNamedPipe
        from win32api import TerminateProcess
    import msvcrt

else:
    from signal import SIGINT, SIGTERM, SIGKILL
    import select
    import fcntl

################################### CONSTANTS ##################################

PIPE = subprocess.PIPE

################################################################################

class Popen(subprocess.Popen):
    def __init__(self, *args, **kwargs):
        subprocess.Popen.__init__(self, *args, **kwargs)

    def recv(self, maxsize=None):
        return self._recv('stdout', maxsize)

    def recv_err(self, maxsize=None):
        return self._recv('stderr', maxsize)

    def send_recv(self, input='', maxsize=None):
        return self.send(input), self.recv(maxsize), self.recv_err(maxsize)

    def read_async(self,  wait=.1, e=1, tr=5, stderr=0):
        if tr < 1:
            tr = 1
        x = time.time()+ wait
        y = []
        r = ''
        pr = self.recv
        if stderr:
            pr = self.recv_err
        while time.time() < x or r:
            r = pr()
            if r is None:
                if e:
                    raise Exception("Other end disconnected!")
                else:
                    break
            elif r:
                y.append(r)
            else:
                time.sleep(max((x-time.time())/tr, 0))
        return ''.join(y)

    def send_all(self, data):
        while len(data):
            sent = self.send(data)
            if sent is None:
                raise Exception("Other end disconnected!")
            data = buffer(data, sent)

    def get_conn_maxsize(self, which, maxsize):
        if maxsize is None:
            maxsize = 1024
        elif maxsize < 1:
            maxsize = 1
        return getattr(self, which), maxsize

    def _close(self, which):
        conn = getattr(self, which)
        flags = fcntl.fcntl(conn, fcntl.F_GETFL)
        if not conn.closed:
            fcntl.fcntl(conn, fcntl.F_SETFL, flags & ~os.O_NONBLOCK)
        assert conn.read() == ''
        getattr(self, which).close()
        setattr(self, which, None)

    if mswindows:
        def kill(self):
            # Recipes
            #http://me.in-berlin.de/doc/python/faq/windows.html#how-do-i-emulate-os-kill-in-windows
            #http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/347462

            """kill function for Win32"""
            TerminateProcess(int(self._handle), 0) # returns None

        def send(self, input):
            if not self.stdin:
                return None

            try:
                x = msvcrt.get_osfhandle(self.stdin.fileno())
                (errCode, written) = WriteFile(x, input)
            except ValueError:
                return self._close('stdin')
            except (subprocess.pywintypes.error, Exception):
                if geterror()[0] in (109, errno.ESHUTDOWN):
                    return self._close('stdin')
                raise

            return written

        def _recv(self, which, maxsize):
            conn, maxsize = self.get_conn_maxsize(which, maxsize)
            if conn is None:
                return None

            try:
                x = msvcrt.get_osfhandle(conn.fileno())
                (read, nAvail, nMessage) = PeekNamedPipe(x, 0)
                if maxsize < nAvail:
                    nAvail = maxsize
                if nAvail > 0:
                    (errCode, read) = ReadFile(x, nAvail, None)
            except ValueError:
                return self._close(which)
            except (subprocess.pywintypes.error, Exception):
                if geterror()[0] in (109, errno.ESHUTDOWN):
                    return self._close(which)
                raise

            if self.universal_newlines:
                # Translate newlines. For Python 3.x assume read is text.
                # If bytes then another solution is needed.
                read = read.replace("\r\n", "\n").replace("\r", "\n")
            return read

    else:
        def kill(self):
            for i, sig in enumerate([SIGTERM, SIGKILL] * 2):
                if i % 2 == 0: os.kill(self.pid, sig)
                time.sleep((i * (i % 2) / 5.0)  + 0.01)

                killed_pid, stat = os.waitpid(self.pid, os.WNOHANG)
                if killed_pid != 0: return

        def send(self, input):
            if not self.stdin:
                return None

            if not select.select([], [self.stdin], [], 0)[1]:
                return 0

            try:
                written = os.write(self.stdin.fileno(), input)
            except OSError:
                if geterror()[0] == errno.EPIPE: #broken pipe
                    return self._close('stdin')
                raise

            return written

        def _recv(self, which, maxsize):
            conn, maxsize = self.get_conn_maxsize(which, maxsize)
            if conn is None:
                return None

            flags = fcntl.fcntl(conn, fcntl.F_GETFL)
            if not conn.closed:
                fcntl.fcntl(conn, fcntl.F_SETFL, flags| os.O_NONBLOCK)

            try:
                if not select.select([conn], [], [], 0)[0]:
                    return ''

                try:
                    r = conn.read(maxsize)
                except IOError as e:
                    if e.errno == errno.EAGAIN:
                        return ''
                    raise
                if not r:
                    return self._close(which)

                if self.universal_newlines:
                    r = r.replace("\r\n", "\n").replace("\r", "\n")
                return r
            finally:
                if not conn.closed:
                    fcntl.fcntl(conn, fcntl.F_SETFL, flags)

################################################################################

def proc_in_time_or_kill(cmd, time_out, wd = None, env = None):
    proc = Popen (
        cmd, cwd = wd, env = env,
        stdin = subprocess.PIPE, stdout = subprocess.PIPE,
        stderr = subprocess.STDOUT, universal_newlines = 1
    )

    ret_code = None
    response = []

    t = time.time()
    while ret_code is None and ((time.time() -t) < time_out):
        ret_code = proc.poll()
        response += [proc.read_async(wait=0.1, e=0)]

    if ret_code is None:
        ret_code = '"Process timed out (time_out = {} secs) '.format(time_out)
        try:
            proc.kill()
            ret_code += 'and was successfully terminated"'
        except Exception:
            ret_code += ("and termination failed "
                "(exception: {})".format(geterror(),))

    return ret_code, ''.join(response)

################################################################################

class AsyncTest(unittest.TestCase):
    def test_proc_in_time_or_kill(self):
        ret_code, response = proc_in_time_or_kill(
            [sys.executable, '-c', 'while 1: pass'], time_out = 1
        )

        self.assert_( 'rocess timed out' in ret_code )
        self.assert_( 'successfully terminated' in ret_code )

################################################################################

def _example():
    if sys.platform == 'win32':
        shell, commands, tail = ('cmd', ('echo "hello"', 'echo "HELLO WORLD"'),
            '\r\n')
    else:
        shell, commands, tail = ('sh', ('ls', 'echo HELLO WORLD'), '\n')

    a = Popen(shell, stdin=PIPE, stdout=PIPE)
    sys.stdout.write(a.read_async())
    sys.stdout.write(" ")
    for cmd in commands:
        a.send_all(cmd + tail)
        sys.stdout.write(a.read_async())
        sys.stdout.write(" ")
    a.send_all('exit' + tail)
    print (a.read_async(e=0))
    a.wait()

################################################################################

if __name__ == '__main__':
    if 1: unittest.main()
    else: _example()