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subprocess.py
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# subprocess - Subprocesses with accessible I/O streams
#
# For more information about this module, see PEP 324.
#
# Copyright (c) 2003-2005 by Peter Astrand <astrand@lysator.liu.se>
#
# Licensed to PSF under a Contributor Agreement.
# See http://www.python.org/2.4/license for licensing details.
r"""subprocess - Subprocesses with accessible I/O streams
This module allows you to spawn processes, connect to their
input/output/error pipes, and obtain their return codes. This module
intends to replace several other, older modules and functions, like:
os.system
os.spawn*
Information about how the subprocess module can be used to replace these
modules and functions can be found below.
Using the subprocess module
===========================
This module defines one class called Popen:
class Popen(args, bufsize=-1, executable=None,
stdin=None, stdout=None, stderr=None,
preexec_fn=None, close_fds=True, shell=False,
cwd=None, env=None, universal_newlines=False,
startupinfo=None, creationflags=0,
restore_signals=True, start_new_session=False, pass_fds=()):
Arguments are:
args should be a string, or a sequence of program arguments. The
program to execute is normally the first item in the args sequence or
string, but can be explicitly set by using the executable argument.
On POSIX, with shell=False (default): In this case, the Popen class
uses os.execvp() to execute the child program. args should normally
be a sequence. A string will be treated as a sequence with the string
as the only item (the program to execute).
On POSIX, with shell=True: If args is a string, it specifies the
command string to execute through the shell. If args is a sequence,
the first item specifies the command string, and any additional items
will be treated as additional shell arguments.
On Windows: the Popen class uses CreateProcess() to execute the child
program, which operates on strings. If args is a sequence, it will be
converted to a string using the list2cmdline method. Please note that
not all MS Windows applications interpret the command line the same
way: The list2cmdline is designed for applications using the same
rules as the MS C runtime.
bufsize will be supplied as the corresponding argument to the io.open()
function when creating the stdin/stdout/stderr pipe file objects:
0 means unbuffered (read & write are one system call and can return short),
1 means line buffered, any other positive value means use a buffer of
approximately that size. A negative bufsize, the default, means the system
default of io.DEFAULT_BUFFER_SIZE will be used.
stdin, stdout and stderr specify the executed programs' standard
input, standard output and standard error file handles, respectively.
Valid values are PIPE, an existing file descriptor (a positive
integer), an existing file object, and None. PIPE indicates that a
new pipe to the child should be created. With None, no redirection
will occur; the child's file handles will be inherited from the
parent. Additionally, stderr can be STDOUT, which indicates that the
stderr data from the applications should be captured into the same
file handle as for stdout.
On POSIX, if preexec_fn is set to a callable object, this object will be
called in the child process just before the child is executed. The use
of preexec_fn is not thread safe, using it in the presence of threads
could lead to a deadlock in the child process before the new executable
is executed.
If close_fds is true, all file descriptors except 0, 1 and 2 will be
closed before the child process is executed. The default for close_fds
varies by platform: Always true on POSIX. True when stdin/stdout/stderr
are None on Windows, false otherwise.
pass_fds is an optional sequence of file descriptors to keep open between the
parent and child. Providing any pass_fds implicitly sets close_fds to true.
if shell is true, the specified command will be executed through the
shell.
If cwd is not None, the current directory will be changed to cwd
before the child is executed.
On POSIX, if restore_signals is True all signals that Python sets to
SIG_IGN are restored to SIG_DFL in the child process before the exec.
Currently this includes the SIGPIPE, SIGXFZ and SIGXFSZ signals. This
parameter does nothing on Windows.
On POSIX, if start_new_session is True, the setsid() system call will be made
in the child process prior to executing the command.
If env is not None, it defines the environment variables for the new
process.
If universal_newlines is true, the file objects stdout and stderr are
opened as a text files, but lines may be terminated by any of '\n',
the Unix end-of-line convention, '\r', the old Macintosh convention or
'\r\n', the Windows convention. All of these external representations
are seen as '\n' by the Python program. Also, the newlines attribute
of the file objects stdout, stdin and stderr are not updated by the
communicate() method.
The startupinfo and creationflags, if given, will be passed to the
underlying CreateProcess() function. They can specify things such as
appearance of the main window and priority for the new process.
(Windows only)
This module also defines some shortcut functions:
call(*popenargs, **kwargs):
Run command with arguments. Wait for command to complete, then
return the returncode attribute.
The arguments are the same as for the Popen constructor. Example:
>>> retcode = subprocess.call(["ls", "-l"])
check_call(*popenargs, **kwargs):
Run command with arguments. Wait for command to complete. If the
exit code was zero then return, otherwise raise
CalledProcessError. The CalledProcessError object will have the
return code in the returncode attribute.
The arguments are the same as for the Popen constructor. Example:
>>> subprocess.check_call(["ls", "-l"])
0
getstatusoutput(cmd):
Return (status, output) of executing cmd in a shell.
Execute the string 'cmd' in a shell with os.popen() and return a 2-tuple
(status, output). cmd is actually run as '{ cmd ; } 2>&1', so that the
returned output will contain output or error messages. A trailing newline
is stripped from the output. The exit status for the command can be
interpreted according to the rules for the C function wait(). Example:
>>> subprocess.getstatusoutput('ls /bin/ls')
(0, '/bin/ls')
>>> subprocess.getstatusoutput('cat /bin/junk')
(256, 'cat: /bin/junk: No such file or directory')
>>> subprocess.getstatusoutput('/bin/junk')
(256, 'sh: /bin/junk: not found')
getoutput(cmd):
Return output (stdout or stderr) of executing cmd in a shell.
Like getstatusoutput(), except the exit status is ignored and the return
value is a string containing the command's output. Example:
>>> subprocess.getoutput('ls /bin/ls')
'/bin/ls'
check_output(*popenargs, **kwargs):
Run command with arguments and return its output as a byte string.
If the exit code was non-zero it raises a CalledProcessError. The
CalledProcessError object will have the return code in the returncode
attribute and output in the output attribute.
The arguments are the same as for the Popen constructor. Example:
>>> output = subprocess.check_output(["ls", "-l", "/dev/null"])
Exceptions
----------
Exceptions raised in the child process, before the new program has
started to execute, will be re-raised in the parent. Additionally,
the exception object will have one extra attribute called
'child_traceback', which is a string containing traceback information
from the childs point of view.
The most common exception raised is OSError. This occurs, for
example, when trying to execute a non-existent file. Applications
should prepare for OSErrors.
A ValueError will be raised if Popen is called with invalid arguments.
check_call() and check_output() will raise CalledProcessError, if the
called process returns a non-zero return code.
Security
--------
Unlike some other popen functions, this implementation will never call
/bin/sh implicitly. This means that all characters, including shell
metacharacters, can safely be passed to child processes.
Popen objects
=============
Instances of the Popen class have the following methods:
poll()
Check if child process has terminated. Returns returncode
attribute.
wait()
Wait for child process to terminate. Returns returncode attribute.
communicate(input=None)
Interact with process: Send data to stdin. Read data from stdout
and stderr, until end-of-file is reached. Wait for process to
terminate. The optional input argument should be a string to be
sent to the child process, or None, if no data should be sent to
the child.
communicate() returns a tuple (stdout, stderr).
Note: The data read is buffered in memory, so do not use this
method if the data size is large or unlimited.
The following attributes are also available:
stdin
If the stdin argument is PIPE, this attribute is a file object
that provides input to the child process. Otherwise, it is None.
stdout
If the stdout argument is PIPE, this attribute is a file object
that provides output from the child process. Otherwise, it is
None.
stderr
If the stderr argument is PIPE, this attribute is file object that
provides error output from the child process. Otherwise, it is
None.
pid
The process ID of the child process.
returncode
The child return code. A None value indicates that the process
hasn't terminated yet. A negative value -N indicates that the
child was terminated by signal N (POSIX only).
Replacing older functions with the subprocess module
====================================================
In this section, "a ==> b" means that b can be used as a replacement
for a.
Note: All functions in this section fail (more or less) silently if
the executed program cannot be found; this module raises an OSError
exception.
In the following examples, we assume that the subprocess module is
imported with "from subprocess import *".
Replacing /bin/sh shell backquote
---------------------------------
output=`mycmd myarg`
==>
output = Popen(["mycmd", "myarg"], stdout=PIPE).communicate()[0]
Replacing shell pipe line
-------------------------
output=`dmesg | grep hda`
==>
p1 = Popen(["dmesg"], stdout=PIPE)
p2 = Popen(["grep", "hda"], stdin=p1.stdout, stdout=PIPE)
output = p2.communicate()[0]
Replacing os.system()
---------------------
sts = os.system("mycmd" + " myarg")
==>
p = Popen("mycmd" + " myarg", shell=True)
pid, sts = os.waitpid(p.pid, 0)
Note:
* Calling the program through the shell is usually not required.
* It's easier to look at the returncode attribute than the
exitstatus.
A more real-world example would look like this:
try:
retcode = call("mycmd" + " myarg", shell=True)
if retcode < 0:
print("Child was terminated by signal", -retcode, file=sys.stderr)
else:
print("Child returned", retcode, file=sys.stderr)
except OSError as e:
print("Execution failed:", e, file=sys.stderr)
Replacing os.spawn*
-------------------
P_NOWAIT example:
pid = os.spawnlp(os.P_NOWAIT, "/bin/mycmd", "mycmd", "myarg")
==>
pid = Popen(["/bin/mycmd", "myarg"]).pid
P_WAIT example:
retcode = os.spawnlp(os.P_WAIT, "/bin/mycmd", "mycmd", "myarg")
==>
retcode = call(["/bin/mycmd", "myarg"])
Vector example:
os.spawnvp(os.P_NOWAIT, path, args)
==>
Popen([path] + args[1:])
Environment example:
os.spawnlpe(os.P_NOWAIT, "/bin/mycmd", "mycmd", "myarg", env)
==>
Popen(["/bin/mycmd", "myarg"], env={"PATH": "/usr/bin"})
"""
import sys
mswindows = (sys.platform == "win32")
import io
import os
import traceback
import gc
import signal
import builtins
import warnings
import errno
# Exception classes used by this module.
class CalledProcessError(Exception):
"""This exception is raised when a process run by check_call() or
check_output() returns a non-zero exit status.
The exit status will be stored in the returncode attribute;
check_output() will also store the output in the output attribute.
"""
def __init__(self, returncode, cmd, output=None):
self.returncode = returncode
self.cmd = cmd
self.output = output
def __str__(self):
return "Command '%s' returned non-zero exit status %d" % (self.cmd, self.returncode)
if mswindows:
import threading
import msvcrt
import _subprocess
class STARTUPINFO:
dwFlags = 0
hStdInput = None
hStdOutput = None
hStdError = None
wShowWindow = 0
class pywintypes:
error = IOError
else:
import select
_has_poll = hasattr(select, 'poll')
import fcntl
import pickle
try:
import _posixsubprocess
except ImportError:
_posixsubprocess = None
warnings.warn("The _posixsubprocess module is not being used. "
"Child process reliability may suffer if your "
"program uses threads.", RuntimeWarning)
# When select or poll has indicated that the file is writable,
# we can write up to _PIPE_BUF bytes without risk of blocking.
# POSIX defines PIPE_BUF as >= 512.
_PIPE_BUF = getattr(select, 'PIPE_BUF', 512)
_FD_CLOEXEC = getattr(fcntl, 'FD_CLOEXEC', 1)
def _set_cloexec(fd, cloexec):
old = fcntl.fcntl(fd, fcntl.F_GETFD)
if cloexec:
fcntl.fcntl(fd, fcntl.F_SETFD, old | _FD_CLOEXEC)
else:
fcntl.fcntl(fd, fcntl.F_SETFD, old & ~_FD_CLOEXEC)
if _posixsubprocess:
_create_pipe = _posixsubprocess.cloexec_pipe
else:
def _create_pipe():
fds = os.pipe()
_set_cloexec(fds[0], True)
_set_cloexec(fds[1], True)
return fds
__all__ = ["Popen", "PIPE", "STDOUT", "call", "check_call", "getstatusoutput",
"getoutput", "check_output", "CalledProcessError"]
if mswindows:
from _subprocess import (CREATE_NEW_CONSOLE, CREATE_NEW_PROCESS_GROUP,
STD_INPUT_HANDLE, STD_OUTPUT_HANDLE,
STD_ERROR_HANDLE, SW_HIDE,
STARTF_USESTDHANDLES, STARTF_USESHOWWINDOW)
__all__.extend(["CREATE_NEW_CONSOLE", "CREATE_NEW_PROCESS_GROUP",
"STD_INPUT_HANDLE", "STD_OUTPUT_HANDLE",
"STD_ERROR_HANDLE", "SW_HIDE",
"STARTF_USESTDHANDLES", "STARTF_USESHOWWINDOW"])
try:
MAXFD = os.sysconf("SC_OPEN_MAX")
except:
MAXFD = 256
# This lists holds Popen instances for which the underlying process had not
# exited at the time its __del__ method got called: those processes are wait()ed
# for synchronously from _cleanup() when a new Popen object is created, to avoid
# zombie processes.
_active = []
def _cleanup():
for inst in _active[:]:
res = inst._internal_poll(_deadstate=sys.maxsize)
if res is not None:
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
PIPE = -1
STDOUT = -2
def _eintr_retry_call(func, *args):
while True:
try:
return func(*args)
except (OSError, IOError) as e:
if e.errno == errno.EINTR:
continue
raise
def call(*popenargs, **kwargs):
"""Run command with arguments. Wait for command to complete, then
return the returncode attribute.
The arguments are the same as for the Popen constructor. Example:
retcode = call(["ls", "-l"])
"""
return Popen(*popenargs, **kwargs).wait()
def check_call(*popenargs, **kwargs):
"""Run command with arguments. Wait for command to complete. If
the exit code was zero then return, otherwise raise
CalledProcessError. The CalledProcessError object will have the
return code in the returncode attribute.
The arguments are the same as for the Popen constructor. Example:
check_call(["ls", "-l"])
"""
retcode = call(*popenargs, **kwargs)
if retcode:
cmd = kwargs.get("args")
if cmd is None:
cmd = popenargs[0]
raise CalledProcessError(retcode, cmd)
return 0
def check_output(*popenargs, **kwargs):
r"""Run command with arguments and return its output as a byte string.
If the exit code was non-zero it raises a CalledProcessError. The
CalledProcessError object will have the return code in the returncode
attribute and output in the output attribute.
The arguments are the same as for the Popen constructor. Example:
>>> check_output(["ls", "-l", "/dev/null"])
b'crw-rw-rw- 1 root root 1, 3 Oct 18 2007 /dev/null\n'
The stdout argument is not allowed as it is used internally.
To capture standard error in the result, use stderr=STDOUT.
>>> check_output(["/bin/sh", "-c",
... "ls -l non_existent_file ; exit 0"],
... stderr=STDOUT)
b'ls: non_existent_file: No such file or directory\n'
"""
if 'stdout' in kwargs:
raise ValueError('stdout argument not allowed, it will be overridden.')
process = Popen(*popenargs, stdout=PIPE, **kwargs)
output, unused_err = process.communicate()
retcode = process.poll()
if retcode:
cmd = kwargs.get("args")
if cmd is None:
cmd = popenargs[0]
raise CalledProcessError(retcode, cmd, output=output)
return output
def list2cmdline(seq):
"""
Translate a sequence of arguments into a command line
string, using the same rules as the MS C runtime:
1) Arguments are delimited by white space, which is either a
space or a tab.
2) A string surrounded by double quotation marks is
interpreted as a single argument, regardless of white space
contained within. A quoted string can be embedded in an
argument.
3) A double quotation mark preceded by a backslash is
interpreted as a literal double quotation mark.
4) Backslashes are interpreted literally, unless they
immediately precede a double quotation mark.
5) If backslashes immediately precede a double quotation mark,
every pair of backslashes is interpreted as a literal
backslash. If the number of backslashes is odd, the last
backslash escapes the next double quotation mark as
described in rule 3.
"""
# See
# http://msdn.microsoft.com/en-us/library/17w5ykft.aspx
# or search http://msdn.microsoft.com for
# "Parsing C++ Command-Line Arguments"
result = []
needquote = False
for arg in seq:
bs_buf = []
# Add a space to separate this argument from the others
if result:
result.append(' ')
needquote = (" " in arg) or ("\t" in arg) or not arg
if needquote:
result.append('"')
for c in arg:
if c == '\\':
# Don't know if we need to double yet.
bs_buf.append(c)
elif c == '"':
# Double backslashes.
result.append('\\' * len(bs_buf)*2)
bs_buf = []
result.append('\\"')
else:
# Normal char
if bs_buf:
result.extend(bs_buf)
bs_buf = []
result.append(c)
# Add remaining backslashes, if any.
if bs_buf:
result.extend(bs_buf)
if needquote:
result.extend(bs_buf)
result.append('"')
return ''.join(result)
# Various tools for executing commands and looking at their output and status.
#
# NB This only works (and is only relevant) for POSIX.
def getstatusoutput(cmd):
"""Return (status, output) of executing cmd in a shell.
Execute the string 'cmd' in a shell with os.popen() and return a 2-tuple
(status, output). cmd is actually run as '{ cmd ; } 2>&1', so that the
returned output will contain output or error messages. A trailing newline
is stripped from the output. The exit status for the command can be
interpreted according to the rules for the C function wait(). Example:
>>> import subprocess
>>> subprocess.getstatusoutput('ls /bin/ls')
(0, '/bin/ls')
>>> subprocess.getstatusoutput('cat /bin/junk')
(256, 'cat: /bin/junk: No such file or directory')
>>> subprocess.getstatusoutput('/bin/junk')
(256, 'sh: /bin/junk: not found')
"""
pipe = os.popen('{ ' + cmd + '; } 2>&1', 'r')
text = pipe.read()
sts = pipe.close()
if sts is None: sts = 0
if text[-1:] == '\n': text = text[:-1]
return sts, text
def getoutput(cmd):
"""Return output (stdout or stderr) of executing cmd in a shell.
Like getstatusoutput(), except the exit status is ignored and the return
value is a string containing the command's output. Example:
>>> import subprocess
>>> subprocess.getoutput('ls /bin/ls')
'/bin/ls'
"""
return getstatusoutput(cmd)[1]
_PLATFORM_DEFAULT_CLOSE_FDS = object()
class Popen(object):
def __init__(self, args, bufsize=-1, executable=None,
stdin=None, stdout=None, stderr=None,
preexec_fn=None, close_fds=_PLATFORM_DEFAULT_CLOSE_FDS,
shell=False, cwd=None, env=None, universal_newlines=False,
startupinfo=None, creationflags=0,
restore_signals=True, start_new_session=False,
pass_fds=()):
"""Create new Popen instance."""
_cleanup()
self._child_created = False
if bufsize is None:
bufsize = -1 # Restore default
if not isinstance(bufsize, int):
raise TypeError("bufsize must be an integer")
if mswindows:
if preexec_fn is not None:
raise ValueError("preexec_fn is not supported on Windows "
"platforms")
any_stdio_set = (stdin is not None or stdout is not None or
stderr is not None)
if close_fds is _PLATFORM_DEFAULT_CLOSE_FDS:
if any_stdio_set:
close_fds = False
else:
close_fds = True
elif close_fds and any_stdio_set:
raise ValueError(
"close_fds is not supported on Windows platforms"
" if you redirect stdin/stdout/stderr")
else:
# POSIX
if close_fds is _PLATFORM_DEFAULT_CLOSE_FDS:
close_fds = True
if pass_fds and not close_fds:
warnings.warn("pass_fds overriding close_fds.", RuntimeWarning)
close_fds = True
if startupinfo is not None:
raise ValueError("startupinfo is only supported on Windows "
"platforms")
if creationflags != 0:
raise ValueError("creationflags is only supported on Windows "
"platforms")
self.stdin = None
self.stdout = None
self.stderr = None
self.pid = None
self.returncode = None
self.universal_newlines = universal_newlines
# Input and output objects. The general principle is like
# this:
#
# Parent Child
# ------ -----
# p2cwrite ---stdin---> p2cread
# c2pread <--stdout--- c2pwrite
# errread <--stderr--- errwrite
#
# On POSIX, the child objects are file descriptors. On
# Windows, these are Windows file handles. The parent objects
# are file descriptors on both platforms. The parent objects
# are -1 when not using PIPEs. The child objects are -1
# when not redirecting.
(p2cread, p2cwrite,
c2pread, c2pwrite,
errread, errwrite) = self._get_handles(stdin, stdout, stderr)
# We wrap OS handles *before* launching the child, otherwise a
# quickly terminating child could make our fds unwrappable
# (see #8458).
if mswindows:
if p2cwrite != -1:
p2cwrite = msvcrt.open_osfhandle(p2cwrite.Detach(), 0)
if c2pread != -1:
c2pread = msvcrt.open_osfhandle(c2pread.Detach(), 0)
if errread != -1:
errread = msvcrt.open_osfhandle(errread.Detach(), 0)
if p2cwrite != -1:
self.stdin = io.open(p2cwrite, 'wb', bufsize)
if self.universal_newlines:
self.stdin = io.TextIOWrapper(self.stdin, write_through=True)
if c2pread != -1:
self.stdout = io.open(c2pread, 'rb', bufsize)
if universal_newlines:
self.stdout = io.TextIOWrapper(self.stdout)
if errread != -1:
self.stderr = io.open(errread, 'rb', bufsize)
if universal_newlines:
self.stderr = io.TextIOWrapper(self.stderr)
try:
self._execute_child(args, executable, preexec_fn, close_fds,
pass_fds, cwd, env, universal_newlines,
startupinfo, creationflags, shell,
p2cread, p2cwrite,
c2pread, c2pwrite,
errread, errwrite,
restore_signals, start_new_session)
except:
# Cleanup if the child failed starting.
for f in filter(None, (self.stdin, self.stdout, self.stderr)):
try:
f.close()
except EnvironmentError:
pass # Ignore EBADF or other errors.
# Make sure the child pipes are closed as well.
to_close = []
if stdin == PIPE:
to_close.append(p2cread)
if stdout == PIPE:
to_close.append(c2pwrite)
if stderr == PIPE:
to_close.append(errwrite)
for fd in to_close:
try:
os.close(fd)
except EnvironmentError:
pass
raise
def _translate_newlines(self, data, encoding):
data = data.decode(encoding)
return data.replace("\r\n", "\n").replace("\r", "\n")
def __enter__(self):
return self
def __exit__(self, type, value, traceback):
if self.stdout:
self.stdout.close()
if self.stderr:
self.stderr.close()
if self.stdin:
self.stdin.close()
# Wait for the process to terminate, to avoid zombies.
self.wait()
def __del__(self, _maxsize=sys.maxsize, _active=_active):
# If __init__ hasn't had a chance to execute (e.g. if it
# was passed an undeclared keyword argument), we don't
# have a _child_created attribute at all.
if not getattr(self, '_child_created', False):
# We didn't get to successfully create a child process.
return
# In case the child hasn't been waited on, check if it's done.
self._internal_poll(_deadstate=_maxsize)
if self.returncode is None and _active is not None:
# Child is still running, keep us alive until we can wait on it.
_active.append(self)
def communicate(self, input=None):
"""Interact with process: Send data to stdin. Read data from
stdout and stderr, until end-of-file is reached. Wait for
process to terminate. The optional input argument should be a
string to be sent to the child process, or None, if no data
should be sent to the child.
communicate() returns a tuple (stdout, stderr)."""
# Optimization: If we are only using one pipe, or no pipe at
# all, using select() or threads is unnecessary.
if [self.stdin, self.stdout, self.stderr].count(None) >= 2:
stdout = None
stderr = None
if self.stdin:
if input:
try:
self.stdin.write(input)
except IOError as e:
if e.errno != errno.EPIPE and e.errno != errno.EINVAL:
raise
self.stdin.close()
elif self.stdout:
stdout = _eintr_retry_call(self.stdout.read)
self.stdout.close()
elif self.stderr:
stderr = _eintr_retry_call(self.stderr.read)
self.stderr.close()
self.wait()
return (stdout, stderr)
return self._communicate(input)
def poll(self):
return self._internal_poll()
if mswindows:
#
# Windows methods
#
def _get_handles(self, stdin, stdout, stderr):
"""Construct and return tuple with IO objects:
p2cread, p2cwrite, c2pread, c2pwrite, errread, errwrite
"""
if stdin is None and stdout is None and stderr is None:
return (-1, -1, -1, -1, -1, -1)
p2cread, p2cwrite = -1, -1
c2pread, c2pwrite = -1, -1
errread, errwrite = -1, -1
if stdin is None:
p2cread = _subprocess.GetStdHandle(_subprocess.STD_INPUT_HANDLE)
if p2cread is None:
p2cread, _ = _subprocess.CreatePipe(None, 0)
elif stdin == PIPE:
p2cread, p2cwrite = _subprocess.CreatePipe(None, 0)
elif isinstance(stdin, int):
p2cread = msvcrt.get_osfhandle(stdin)
else:
# Assuming file-like object
p2cread = msvcrt.get_osfhandle(stdin.fileno())
p2cread = self._make_inheritable(p2cread)
if stdout is None:
c2pwrite = _subprocess.GetStdHandle(_subprocess.STD_OUTPUT_HANDLE)
if c2pwrite is None:
_, c2pwrite = _subprocess.CreatePipe(None, 0)
elif stdout == PIPE:
c2pread, c2pwrite = _subprocess.CreatePipe(None, 0)
elif isinstance(stdout, int):
c2pwrite = msvcrt.get_osfhandle(stdout)
else:
# Assuming file-like object
c2pwrite = msvcrt.get_osfhandle(stdout.fileno())
c2pwrite = self._make_inheritable(c2pwrite)
if stderr is None:
errwrite = _subprocess.GetStdHandle(_subprocess.STD_ERROR_HANDLE)
if errwrite is None:
_, errwrite = _subprocess.CreatePipe(None, 0)
elif stderr == PIPE:
errread, errwrite = _subprocess.CreatePipe(None, 0)
elif stderr == STDOUT:
errwrite = c2pwrite
elif isinstance(stderr, int):
errwrite = msvcrt.get_osfhandle(stderr)
else:
# Assuming file-like object
errwrite = msvcrt.get_osfhandle(stderr.fileno())
errwrite = self._make_inheritable(errwrite)
return (p2cread, p2cwrite,
c2pread, c2pwrite,
errread, errwrite)
def _make_inheritable(self, handle):
"""Return a duplicate of handle, which is inheritable"""
return _subprocess.DuplicateHandle(_subprocess.GetCurrentProcess(),
handle, _subprocess.GetCurrentProcess(), 0, 1,
_subprocess.DUPLICATE_SAME_ACCESS)
def _find_w9xpopen(self):
"""Find and return absolut path to w9xpopen.exe"""
w9xpopen = os.path.join(
os.path.dirname(_subprocess.GetModuleFileName(0)),
"w9xpopen.exe")
if not os.path.exists(w9xpopen):
# Eeek - file-not-found - possibly an embedding
# situation - see if we can locate it in sys.exec_prefix
w9xpopen = os.path.join(os.path.dirname(sys.exec_prefix),
"w9xpopen.exe")
if not os.path.exists(w9xpopen):
raise RuntimeError("Cannot locate w9xpopen.exe, which is "
"needed for Popen to work with your "
"shell or platform.")
return w9xpopen
def _execute_child(self, args, executable, preexec_fn, close_fds,
pass_fds, cwd, env, universal_newlines,
startupinfo, creationflags, shell,
p2cread, p2cwrite,
c2pread, c2pwrite,
errread, errwrite,
unused_restore_signals, unused_start_new_session):
"""Execute program (MS Windows version)"""
assert not pass_fds, "pass_fds not supported on Windows."
if not isinstance(args, str):
args = list2cmdline(args)
# Process startup details
if startupinfo is None:
startupinfo = STARTUPINFO()
if -1 not in (p2cread, c2pwrite, errwrite):
startupinfo.dwFlags |= _subprocess.STARTF_USESTDHANDLES
startupinfo.hStdInput = p2cread
startupinfo.hStdOutput = c2pwrite
startupinfo.hStdError = errwrite
if shell:
startupinfo.dwFlags |= _subprocess.STARTF_USESHOWWINDOW
startupinfo.wShowWindow = _subprocess.SW_HIDE
comspec = os.environ.get("COMSPEC", "cmd.exe")
args = '{} /c "{}"'.format (comspec, args)
if (_subprocess.GetVersion() >= 0x80000000 or
os.path.basename(comspec).lower() == "command.com"):
# Win9x, or using command.com on NT. We need to
# use the w9xpopen intermediate program. For more
# information, see KB Q150956
# (http://web.archive.org/web/20011105084002/http://support.microsoft.com/support/kb/articles/Q150/9/56.asp)
w9xpopen = self._find_w9xpopen()
args = '"%s" %s' % (w9xpopen, args)
# Not passing CREATE_NEW_CONSOLE has been known to
# cause random failures on win9x. Specifically a
# dialog: "Your program accessed mem currently in
# use at xxx" and a hopeful warning about the
# stability of your system. Cost is Ctrl+C won't
# kill children.
creationflags |= _subprocess.CREATE_NEW_CONSOLE
# Start the process
try:
hp, ht, pid, tid = _subprocess.CreateProcess(executable, args,
# no special security
None, None,
int(not close_fds),
creationflags,
env,
cwd,
startupinfo)
except pywintypes.error as e:
# Translate pywintypes.error to WindowsError, which is
# a subclass of OSError. FIXME: We should really
# translate errno using _sys_errlist (or similar), but
# how can this be done from Python?
raise WindowsError(*e.args)
finally:
# Child is launched. Close the parent's copy of those pipe
# handles that only the child should have open. You need
# to make sure that no handles to the write end of the
# output pipe are maintained in this process or else the
# pipe will not close when the child process exits and the
# ReadFile will hang.
if p2cread != -1:
p2cread.Close()
if c2pwrite != -1:
c2pwrite.Close()
if errwrite != -1:
errwrite.Close()
# Retain the process handle, but close the thread handle
self._child_created = True
self._handle = hp