"""Spawn a command with pipes to its stdin, stdout, and optionally stderr.

The normal os.popen(cmd, mode) call spawns a shell command and provides a

file interface to just the input or output of the process depending on

whether mode is 'r' or 'w'.  This module provides the functions popen2(cmd)

and popen3(cmd) which return two or three pipes to the spawned command.

"""

import os

import sys

import warnings

warnings.warn("The popen2 module is deprecated.  Use the subprocess module.",

              DeprecationWarning, stacklevel=2)

__all__ = ["popen2", "popen3", "popen4"]

try:

    MAXFD = os.sysconf('SC_OPEN_MAX')

except (AttributeError, ValueError):

    MAXFD = 256

_active = []

def _cleanup():

    for inst in _active[:]:

        if inst.poll(_deadstate=sys.maxint) >= 0:

            try:

                _active.remove(inst)

            except ValueError:

                # This can happen if two threads create a new Popen instance.

                # It's harmless that it was already removed, so ignore.

                pass

class Popen3:

    """Class representing a child process.  Normally, instances are created

    internally by the functions popen2() and popen3()."""

    sts = -1                    # Child not completed yet

    def __init__(self, cmd, capturestderr=False, bufsize=-1):

        """The parameter 'cmd' is the shell command to execute in a

        sub-process.  On UNIX, 'cmd' may be a sequence, in which case arguments

        will be passed directly to the program without shell intervention (as

        with os.spawnv()).  If 'cmd' is a string it will be passed to the shell

        (as with os.system()).   The 'capturestderr' flag, if true, specifies

        that the object should capture standard error output of the child

        process.  The default is false.  If the 'bufsize' parameter is

        specified, it specifies the size of the I/O buffers to/from the child

        process."""

        _cleanup()

        self.cmd = cmd

        p2cread, p2cwrite = os.pipe()

        c2pread, c2pwrite = os.pipe()

        if capturestderr:

            errout, errin = os.pipe()

        self.pid = os.fork()

        if self.pid == 0:

            # Child

            os.dup2(p2cread, 0)

            os.dup2(c2pwrite, 1)

            if capturestderr:

                os.dup2(errin, 2)

            self._run_child(cmd)

        os.close(p2cread)

        self.tochild = os.fdopen(p2cwrite, 'w', bufsize)

        os.close(c2pwrite)

        self.fromchild = os.fdopen(c2pread, 'r', bufsize)

        if capturestderr:

            os.close(errin)

            self.childerr = os.fdopen(errout, 'r', bufsize)

        else:

            self.childerr = None

    def __del__(self):

        # In case the child hasn't been waited on, check if it's done.

        self.poll(_deadstate=sys.maxint)

        if self.sts < 0:

            if _active is not None:

                # Child is still running, keep us alive until we can wait on it.

                _active.append(self)

    def _run_child(self, cmd):

        if isinstance(cmd, basestring):

            cmd = ['/bin/sh', '-c', cmd]

        os.closerange(3, MAXFD)

        try:

            os.execvp(cmd[0], cmd)

        finally:

            os._exit(1)

    def poll(self, _deadstate=None):

        """Return the exit status of the child process if it has finished,

        or -1 if it hasn't finished yet."""

        if self.sts < 0:

            try:

                pid, sts = os.waitpid(self.pid, os.WNOHANG)

                # pid will be 0 if self.pid hasn't terminated

                if pid == self.pid:

                    self.sts = sts

            except os.error:

                if _deadstate is not None:

                    self.sts = _deadstate

        return self.sts

    def wait(self):

        """Wait for and return the exit status of the child process."""

        if self.sts < 0:

            pid, sts = os.waitpid(self.pid, 0)

            # This used to be a test, but it is believed to be

            # always true, so I changed it to an assertion - mvl

            assert pid == self.pid

            self.sts = sts

        return self.sts

class Popen4(Popen3):

    childerr = None

    def __init__(self, cmd, bufsize=-1):

        _cleanup()

        self.cmd = cmd

        p2cread, p2cwrite = os.pipe()

        c2pread, c2pwrite = os.pipe()

        self.pid = os.fork()

        if self.pid == 0:

            # Child

            os.dup2(p2cread, 0)

            os.dup2(c2pwrite, 1)

            os.dup2(c2pwrite, 2)

            self._run_child(cmd)

        os.close(p2cread)

        self.tochild = os.fdopen(p2cwrite, 'w', bufsize)

        os.close(c2pwrite)

        self.fromchild = os.fdopen(c2pread, 'r', bufsize)

if sys.platform[:3] == "win" or sys.platform == "os2emx":

    # Some things don't make sense on non-Unix platforms.

    del Popen3, Popen4

    def popen2(cmd, bufsize=-1, mode='t'):

        """Execute the shell command 'cmd' in a sub-process. On UNIX, 'cmd' may

        be a sequence, in which case arguments will be passed directly to the

        program without shell intervention (as with os.spawnv()). If 'cmd' is a

        string it will be passed to the shell (as with os.system()). If

        'bufsize' is specified, it sets the buffer size for the I/O pipes. The

        file objects (child_stdout, child_stdin) are returned."""

        w, r = os.popen2(cmd, mode, bufsize)

        return r, w

    def popen3(cmd, bufsize=-1, mode='t'):

        """Execute the shell command 'cmd' in a sub-process. On UNIX, 'cmd' may

        be a sequence, in which case arguments will be passed directly to the

        program without shell intervention (as with os.spawnv()). If 'cmd' is a

        string it will be passed to the shell (as with os.system()). If

        'bufsize' is specified, it sets the buffer size for the I/O pipes. The

        file objects (child_stdout, child_stdin, child_stderr) are returned."""

        w, r, e = os.popen3(cmd, mode, bufsize)

        return r, w, e

    def popen4(cmd, bufsize=-1, mode='t'):

        """Execute the shell command 'cmd' in a sub-process. On UNIX, 'cmd' may

        be a sequence, in which case arguments will be passed directly to the

        program without shell intervention (as with os.spawnv()). If 'cmd' is a

        string it will be passed to the shell (as with os.system()). If

        'bufsize' is specified, it sets the buffer size for the I/O pipes. The

        file objects (child_stdout_stderr, child_stdin) are returned."""

        w, r = os.popen4(cmd, mode, bufsize)

        return r, w

else:

    def popen2(cmd, bufsize=-1, mode='t'):

        """Execute the shell command 'cmd' in a sub-process. On UNIX, 'cmd' may

        be a sequence, in which case arguments will be passed directly to the

        program without shell intervention (as with os.spawnv()). If 'cmd' is a

        string it will be passed to the shell (as with os.system()). If

        'bufsize' is specified, it sets the buffer size for the I/O pipes. The

        file objects (child_stdout, child_stdin) are returned."""

        inst = Popen3(cmd, False, bufsize)

        return inst.fromchild, inst.tochild

    def popen3(cmd, bufsize=-1, mode='t'):

        """Execute the shell command 'cmd' in a sub-process. On UNIX, 'cmd' may

        be a sequence, in which case arguments will be passed directly to the

        program without shell intervention (as with os.spawnv()). If 'cmd' is a

        string it will be passed to the shell (as with os.system()). If

        'bufsize' is specified, it sets the buffer size for the I/O pipes. The

        file objects (child_stdout, child_stdin, child_stderr) are returned."""

        inst = Popen3(cmd, True, bufsize)

        return inst.fromchild, inst.tochild, inst.childerr

    def popen4(cmd, bufsize=-1, mode='t'):

        """Execute the shell command 'cmd' in a sub-process. On UNIX, 'cmd' may

        be a sequence, in which case arguments will be passed directly to the

        program without shell intervention (as with os.spawnv()). If 'cmd' is a

        string it will be passed to the shell (as with os.system()). If

        'bufsize' is specified, it sets the buffer size for the I/O pipes. The

        file objects (child_stdout_stderr, child_stdin) are returned."""

        inst = Popen4(cmd, bufsize)

        return inst.fromchild, inst.tochild

    __all__.extend(["Popen3", "Popen4"])