Source code for subprocess

# 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"""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.

For a complete description of this module see the Python documentation.

Main API
========
run(...): Runs a command, waits for it to complete, then returns a
          CompletedProcess instance.
Popen(...): A class for flexibly executing a command in a new process

Constants
---------
DEVNULL: Special value that indicates that os.devnull should be used
PIPE:    Special value that indicates a pipe should be created
STDOUT:  Special value that indicates that stderr should go to stdout


Older API
=========
call(...): Runs a command, waits for it to complete, then returns
    the return code.
check_call(...): Same as call() but raises CalledProcessError()
    if return code is not 0
check_output(...): Same as check_call() but returns the contents of
    stdout instead of a return code
getoutput(...): Runs a command in the shell, waits for it to complete,
    then returns the output
getstatusoutput(...): Runs a command in the shell, waits for it to complete,
    then returns a (exitcode, output) tuple
"""

import sys
_mswindows = (sys.platform == "win32")

import io
import os
import time
import signal
import builtins
import warnings
import errno
from time import monotonic as _time

# Exception classes used by this module.
[docs]class SubprocessError(Exception): pass
[docs]class CalledProcessError(SubprocessError): """Raised when run() is called with check=True and the process returns a non-zero exit status. Attributes: cmd, returncode, stdout, stderr, output """ def __init__(self, returncode, cmd, output=None, stderr=None): self.returncode = returncode self.cmd = cmd self.output = output self.stderr = stderr def __str__(self): if self.returncode and self.returncode < 0: try: return "Command '%s' died with %r." % ( self.cmd, signal.Signals(-self.returncode)) except ValueError: return "Command '%s' died with unknown signal %d." % ( self.cmd, -self.returncode) else: return "Command '%s' returned non-zero exit status %d." % ( self.cmd, self.returncode) @property def stdout(self): """Alias for output attribute, to match stderr""" return self.output @stdout.setter def stdout(self, value): # There's no obvious reason to set this, but allow it anyway so # .stdout is a transparent alias for .output self.output = value
[docs]class TimeoutExpired(SubprocessError): """This exception is raised when the timeout expires while waiting for a child process. Attributes: cmd, output, stdout, stderr, timeout """ def __init__(self, cmd, timeout, output=None, stderr=None): self.cmd = cmd self.timeout = timeout self.output = output self.stderr = stderr def __str__(self): return ("Command '%s' timed out after %s seconds" % (self.cmd, self.timeout)) @property def stdout(self): return self.output @stdout.setter def stdout(self, value): # There's no obvious reason to set this, but allow it anyway so # .stdout is a transparent alias for .output self.output = value
if _mswindows: import threading import msvcrt import _winapi class STARTUPINFO: def __init__(self, *, dwFlags=0, hStdInput=None, hStdOutput=None, hStdError=None, wShowWindow=0, lpAttributeList=None): self.dwFlags = dwFlags self.hStdInput = hStdInput self.hStdOutput = hStdOutput self.hStdError = hStdError self.wShowWindow = wShowWindow self.lpAttributeList = lpAttributeList or {"handle_list": []} def _copy(self): attr_list = self.lpAttributeList.copy() if 'handle_list' in attr_list: attr_list['handle_list'] = list(attr_list['handle_list']) return STARTUPINFO(dwFlags=self.dwFlags, hStdInput=self.hStdInput, hStdOutput=self.hStdOutput, hStdError=self.hStdError, wShowWindow=self.wShowWindow, lpAttributeList=attr_list) else: import _posixsubprocess import select import selectors import threading # 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) # poll/select have the advantage of not requiring any extra file # descriptor, contrarily to epoll/kqueue (also, they require a single # syscall). if hasattr(selectors, 'PollSelector'): _PopenSelector = selectors.PollSelector else: _PopenSelector = selectors.SelectSelector __all__ = ["Popen", "PIPE", "STDOUT", "call", "check_call", "getstatusoutput", "getoutput", "check_output", "run", "CalledProcessError", "DEVNULL", "SubprocessError", "TimeoutExpired", "CompletedProcess"] # NOTE: We intentionally exclude list2cmdline as it is # considered an internal implementation detail. issue10838. if _mswindows: from _winapi import (CREATE_NEW_CONSOLE, CREATE_NEW_PROCESS_GROUP, STD_INPUT_HANDLE, STD_OUTPUT_HANDLE, STD_ERROR_HANDLE, SW_HIDE, STARTF_USESTDHANDLES, STARTF_USESHOWWINDOW, ABOVE_NORMAL_PRIORITY_CLASS, BELOW_NORMAL_PRIORITY_CLASS, HIGH_PRIORITY_CLASS, IDLE_PRIORITY_CLASS, NORMAL_PRIORITY_CLASS, REALTIME_PRIORITY_CLASS, CREATE_NO_WINDOW, DETACHED_PROCESS, CREATE_DEFAULT_ERROR_MODE, CREATE_BREAKAWAY_FROM_JOB) __all__.extend(["CREATE_NEW_CONSOLE", "CREATE_NEW_PROCESS_GROUP", "STD_INPUT_HANDLE", "STD_OUTPUT_HANDLE", "STD_ERROR_HANDLE", "SW_HIDE", "STARTF_USESTDHANDLES", "STARTF_USESHOWWINDOW", "STARTUPINFO", "ABOVE_NORMAL_PRIORITY_CLASS", "BELOW_NORMAL_PRIORITY_CLASS", "HIGH_PRIORITY_CLASS", "IDLE_PRIORITY_CLASS", "NORMAL_PRIORITY_CLASS", "REALTIME_PRIORITY_CLASS", "CREATE_NO_WINDOW", "DETACHED_PROCESS", "CREATE_DEFAULT_ERROR_MODE", "CREATE_BREAKAWAY_FROM_JOB"]) class Handle(int): closed = False def Close(self, CloseHandle=_winapi.CloseHandle): if not self.closed: self.closed = True CloseHandle(self) def Detach(self): if not self.closed: self.closed = True return int(self) raise ValueError("already closed") def __repr__(self): return "%s(%d)" % (self.__class__.__name__, int(self)) __del__ = Close __str__ = __repr__ # 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 DEVNULL = -3 # XXX This function is only used by multiprocessing and the test suite, # but it's here so that it can be imported when Python is compiled without # threads. def _optim_args_from_interpreter_flags(): """Return a list of command-line arguments reproducing the current optimization settings in sys.flags.""" args = [] value = sys.flags.optimize if value > 0: args.append('-' + 'O' * value) return args def _args_from_interpreter_flags(): """Return a list of command-line arguments reproducing the current settings in sys.flags, sys.warnoptions and sys._xoptions.""" flag_opt_map = { 'debug': 'd', # 'inspect': 'i', # 'interactive': 'i', 'dont_write_bytecode': 'B', 'no_user_site': 's', 'no_site': 'S', 'ignore_environment': 'E', 'verbose': 'v', 'bytes_warning': 'b', 'quiet': 'q', # -O is handled in _optim_args_from_interpreter_flags() } args = _optim_args_from_interpreter_flags() for flag, opt in flag_opt_map.items(): v = getattr(sys.flags, flag) if v > 0: args.append('-' + opt * v) # -W options warnopts = sys.warnoptions[:] bytes_warning = sys.flags.bytes_warning xoptions = getattr(sys, '_xoptions', {}) dev_mode = ('dev' in xoptions) if bytes_warning > 1: warnopts.remove("error::BytesWarning") elif bytes_warning: warnopts.remove("default::BytesWarning") if dev_mode: warnopts.remove('default') for opt in warnopts: args.append('-W' + opt) # -X options if dev_mode: args.extend(('-X', 'dev')) for opt in ('faulthandler', 'tracemalloc', 'importtime', 'showalloccount', 'showrefcount', 'utf8'): if opt in xoptions: value = xoptions[opt] if value is True: arg = opt else: arg = '%s=%s' % (opt, value) args.extend(('-X', arg)) return args def call(*popenargs, timeout=None, **kwargs): """Run command with arguments. Wait for command to complete or timeout, then return the returncode attribute. The arguments are the same as for the Popen constructor. Example: retcode = call(["ls", "-l"]) """ with Popen(*popenargs, **kwargs) as p: try: return p.wait(timeout=timeout) except: # Including KeyboardInterrupt, wait handled that. p.kill() # We don't call p.wait() again as p.__exit__ does that for us. raise 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 call function. 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, timeout=None, **kwargs): r"""Run command with arguments and return its output. 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' There is an additional optional argument, "input", allowing you to pass a string to the subprocess's stdin. If you use this argument you may not also use the Popen constructor's "stdin" argument, as it too will be used internally. Example: >>> check_output(["sed", "-e", "s/foo/bar/"], ... input=b"when in the course of fooman events\n") b'when in the course of barman events\n' By default, all communication is in bytes, and therefore any "input" should be bytes, and the return value wil be bytes. If in text mode, any "input" should be a string, and the return value will be a string decoded according to locale encoding, or by "encoding" if set. Text mode is triggered by setting any of text, encoding, errors or universal_newlines. """ if 'stdout' in kwargs: raise ValueError('stdout argument not allowed, it will be overridden.') if 'input' in kwargs and kwargs['input'] is None: # Explicitly passing input=None was previously equivalent to passing an # empty string. That is maintained here for backwards compatibility. kwargs['input'] = '' if kwargs.get('universal_newlines', False) else b'' return run(*popenargs, stdout=PIPE, timeout=timeout, check=True, **kwargs).stdout class CompletedProcess(object): """A process that has finished running. This is returned by run(). Attributes: args: The list or str args passed to run(). returncode: The exit code of the process, negative for signals. stdout: The standard output (None if not captured). stderr: The standard error (None if not captured). """ def __init__(self, args, returncode, stdout=None, stderr=None): self.args = args self.returncode = returncode self.stdout = stdout self.stderr = stderr def __repr__(self): args = ['args={!r}'.format(self.args), 'returncode={!r}'.format(self.returncode)] if self.stdout is not None: args.append('stdout={!r}'.format(self.stdout)) if self.stderr is not None: args.append('stderr={!r}'.format(self.stderr)) return "{}({})".format(type(self).__name__, ', '.join(args)) def check_returncode(self): """Raise CalledProcessError if the exit code is non-zero.""" if self.returncode: raise CalledProcessError(self.returncode, self.args, self.stdout, self.stderr) def run(*popenargs, input=None, capture_output=False, timeout=None, check=False, **kwargs): """Run command with arguments and return a CompletedProcess instance. The returned instance will have attributes args, returncode, stdout and stderr. By default, stdout and stderr are not captured, and those attributes will be None. Pass stdout=PIPE and/or stderr=PIPE in order to capture them. If check is True and the exit code was non-zero, it raises a CalledProcessError. The CalledProcessError object will have the return code in the returncode attribute, and output & stderr attributes if those streams were captured. If timeout is given, and the process takes too long, a TimeoutExpired exception will be raised. There is an optional argument "input", allowing you to pass bytes or a string to the subprocess's stdin. If you use this argument you may not also use the Popen constructor's "stdin" argument, as it will be used internally. By default, all communication is in bytes, and therefore any "input" should be bytes, and the stdout and stderr will be bytes. If in text mode, any "input" should be a string, and stdout and stderr will be strings decoded according to locale encoding, or by "encoding" if set. Text mode is triggered by setting any of text, encoding, errors or universal_newlines. The other arguments are the same as for the Popen constructor. """ if input is not None: if 'stdin' in kwargs: raise ValueError('stdin and input arguments may not both be used.') kwargs['stdin'] = PIPE if capture_output: if ('stdout' in kwargs) or ('stderr' in kwargs): raise ValueError('stdout and stderr arguments may not be used ' 'with capture_output.') kwargs['stdout'] = PIPE kwargs['stderr'] = PIPE with Popen(*popenargs, **kwargs) as process: try: stdout, stderr = process.communicate(input, timeout=timeout) except TimeoutExpired: process.kill() stdout, stderr = process.communicate() raise TimeoutExpired(process.args, timeout, output=stdout, stderr=stderr) except: # Including KeyboardInterrupt, communicate handled that. process.kill() # We don't call process.wait() as .__exit__ does that for us. raise retcode = process.poll() if check and retcode: raise CalledProcessError(retcode, process.args, output=stdout, stderr=stderr) return CompletedProcess(process.args, retcode, stdout, stderr) 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. #
[docs]def getstatusoutput(cmd): """Return (exitcode, output) of executing cmd in a shell. Execute the string 'cmd' in a shell with 'check_output' and return a 2-tuple (status, output). The locale encoding is used to decode the output and process newlines. A trailing newline is stripped from the output. The exit status for the command can be interpreted according to the rules for the function 'wait'. Example: >>> import subprocess >>> subprocess.getstatusoutput('ls /bin/ls') (0, '/bin/ls') >>> subprocess.getstatusoutput('cat /bin/junk') (1, 'cat: /bin/junk: No such file or directory') >>> subprocess.getstatusoutput('/bin/junk') (127, 'sh: /bin/junk: not found') >>> subprocess.getstatusoutput('/bin/kill $$') (-15, '') """ try: data = check_output(cmd, shell=True, text=True, stderr=STDOUT) exitcode = 0 except CalledProcessError as ex: data = ex.output exitcode = ex.returncode if data[-1:] == '\n': data = data[:-1] return exitcode, data
[docs]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]
class Popen(object): """ Execute a child program in a new process. For a complete description of the arguments see the Python documentation. Arguments: args: A string, or a sequence of program arguments. bufsize: supplied as the buffering argument to the open() function when creating the stdin/stdout/stderr pipe file objects executable: A replacement program to execute. stdin, stdout and stderr: These specify the executed programs' standard input, standard output and standard error file handles, respectively. preexec_fn: (POSIX only) An object to be called in the child process just before the child is executed. close_fds: Controls closing or inheriting of file descriptors. shell: If true, the command will be executed through the shell. cwd: Sets the current directory before the child is executed. env: Defines the environment variables for the new process. text: If true, decode stdin, stdout and stderr using the given encoding (if set) or the system default otherwise. universal_newlines: Alias of text, provided for backwards compatibility. startupinfo and creationflags (Windows only) restore_signals (POSIX only) start_new_session (POSIX only) pass_fds (POSIX only) encoding and errors: Text mode encoding and error handling to use for file objects stdin, stdout and stderr. Attributes: stdin, stdout, stderr, pid, returncode """ _child_created = False # Set here since __del__ checks it def __init__(self, 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=None, startupinfo=None, creationflags=0, restore_signals=True, start_new_session=False, pass_fds=(), *, encoding=None, errors=None, text=None): """Create new Popen instance.""" _cleanup() # Held while anything is calling waitpid before returncode has been # updated to prevent clobbering returncode if wait() or poll() are # called from multiple threads at once. After acquiring the lock, # code must re-check self.returncode to see if another thread just # finished a waitpid() call. self._waitpid_lock = threading.Lock() self._input = None self._communication_started = 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") else: # POSIX 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.args = args self.stdin = None self.stdout = None self.stderr = None self.pid = None self.returncode = None self.encoding = encoding self.errors = errors # Validate the combinations of text and universal_newlines if (text is not None and universal_newlines is not None and bool(universal_newlines) != bool(text)): raise SubprocessError('Cannot disambiguate when both text ' 'and universal_newlines are supplied but ' 'different. Pass one or the other.') # 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) self.text_mode = encoding or errors or text or universal_newlines # How long to resume waiting on a child after the first ^C. # There is no right value for this. The purpose is to be polite # yet remain good for interactive users trying to exit a tool. self._sigint_wait_secs = 0.25 # 1/xkcd221.getRandomNumber() self._closed_child_pipe_fds = False try: if p2cwrite != -1: self.stdin = io.open(p2cwrite, 'wb', bufsize) if self.text_mode: self.stdin = io.TextIOWrapper(self.stdin, write_through=True, line_buffering=(bufsize == 1), encoding=encoding, errors=errors) if c2pread != -1: self.stdout = io.open(c2pread, 'rb', bufsize) if self.text_mode: self.stdout = io.TextIOWrapper(self.stdout, encoding=encoding, errors=errors) if errread != -1: self.stderr = io.open(errread, 'rb', bufsize) if self.text_mode: self.stderr = io.TextIOWrapper(self.stderr, encoding=encoding, errors=errors) self._execute_child(args, executable, preexec_fn, close_fds, pass_fds, cwd, env, 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 OSError: pass # Ignore EBADF or other errors. if not self._closed_child_pipe_fds: to_close = [] if stdin == PIPE: to_close.append(p2cread) if stdout == PIPE: to_close.append(c2pwrite) if stderr == PIPE: to_close.append(errwrite) if hasattr(self, '_devnull'): to_close.append(self._devnull) for fd in to_close: try: if _mswindows and isinstance(fd, Handle): fd.Close() else: os.close(fd) except OSError: pass raise @property def universal_newlines(self): # universal_newlines as retained as an alias of text_mode for API # compatibility. bpo-31756 return self.text_mode @universal_newlines.setter def universal_newlines(self, universal_newlines): self.text_mode = bool(universal_newlines) def _translate_newlines(self, data, encoding, errors): data = data.decode(encoding, errors) return data.replace("\r\n", "\n").replace("\r", "\n") def __enter__(self): return self def __exit__(self, exc_type, value, traceback): if self.stdout: self.stdout.close() if self.stderr: self.stderr.close() try: # Flushing a BufferedWriter may raise an error if self.stdin: self.stdin.close() finally: if exc_type == KeyboardInterrupt: # https://bugs.python.org/issue25942 # In the case of a KeyboardInterrupt we assume the SIGINT # was also already sent to our child processes. We can't # block indefinitely as that is not user friendly. # If we have not already waited a brief amount of time in # an interrupted .wait() or .communicate() call, do so here # for consistency. if self._sigint_wait_secs > 0: try: self._wait(timeout=self._sigint_wait_secs) except TimeoutExpired: pass self._sigint_wait_secs = 0 # Note that this has been done. return # resume the KeyboardInterrupt # Wait for the process to terminate, to avoid zombies. self.wait() def __del__(self, _maxsize=sys.maxsize, _warn=warnings.warn): if not self._child_created: # We didn't get to successfully create a child process. return if self.returncode is None: # Not reading subprocess exit status creates a zombie process which # is only destroyed at the parent python process exit _warn("subprocess %s is still running" % self.pid, ResourceWarning, source=self) # 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 _get_devnull(self): if not hasattr(self, '_devnull'): self._devnull = os.open(os.devnull, os.O_RDWR) return self._devnull def _stdin_write(self, input): if input: try: self.stdin.write(input) except BrokenPipeError: pass # communicate() must ignore broken pipe errors. except OSError as exc: if exc.errno == errno.EINVAL: # bpo-19612, bpo-30418: On Windows, stdin.write() fails # with EINVAL if the child process exited or if the child # process is still running but closed the pipe. pass else: raise try: self.stdin.close() except BrokenPipeError: pass # communicate() must ignore broken pipe errors. except OSError as exc: if exc.errno == errno.EINVAL: pass else: raise def communicate(self, input=None, timeout=None): """Interact with process: Send data to stdin and close it. Read data from stdout and stderr, until end-of-file is reached. Wait for process to terminate. The optional "input" argument should be data to be sent to the child process, or None, if no data should be sent to the child. communicate() returns a tuple (stdout, stderr). By default, all communication is in bytes, and therefore any "input" should be bytes, and the (stdout, stderr) will be bytes. If in text mode (indicated by self.text_mode), any "input" should be a string, and (stdout, stderr) will be strings decoded according to locale encoding, or by "encoding" if set. Text mode is triggered by setting any of text, encoding, errors or universal_newlines. """ if self._communication_started and input: raise ValueError("Cannot send input after starting communication") # Optimization: If we are not worried about timeouts, we haven't # started communicating, and we have one or zero pipes, using select() # or threads is unnecessary. if (timeout is None and not self._communication_started and [self.stdin, self.stdout, self.stderr].count(None) >= 2): stdout = None stderr = None if self.stdin: self._stdin_write(input) elif self.stdout: stdout = self.stdout.read() self.stdout.close() elif self.stderr: stderr = self.stderr.read() self.stderr.close() self.wait() else: if timeout is not None: endtime = _time() + timeout else: endtime = None try: stdout, stderr = self._communicate(input, endtime, timeout) except KeyboardInterrupt: # https://bugs.python.org/issue25942 # See the detailed comment in .wait(). if timeout is not None: sigint_timeout = min(self._sigint_wait_secs, self._remaining_time(endtime)) else: sigint_timeout = self._sigint_wait_secs self._sigint_wait_secs = 0 # nothing else should wait. try: self._wait(timeout=sigint_timeout) except TimeoutExpired: pass raise # resume the KeyboardInterrupt finally: self._communication_started = True sts = self.wait(timeout=self._remaining_time(endtime)) return (stdout, stderr) def poll(self): """Check if child process has terminated. Set and return returncode attribute.""" return self._internal_poll() def _remaining_time(self, endtime): """Convenience for _communicate when computing timeouts.""" if endtime is None: return None else: return endtime - _time() def _check_timeout(self, endtime, orig_timeout): """Convenience for checking if a timeout has expired.""" if endtime is None: return if _time() > endtime: raise TimeoutExpired(self.args, orig_timeout) def wait(self, timeout=None): """Wait for child process to terminate; returns self.returncode.""" if timeout is not None: endtime = _time() + timeout try: return self._wait(timeout=timeout) except KeyboardInterrupt: # https://bugs.python.org/issue25942 # The first keyboard interrupt waits briefly for the child to # exit under the common assumption that it also received the ^C # generated SIGINT and will exit rapidly. if timeout is not None: sigint_timeout = min(self._sigint_wait_secs, self._remaining_time(endtime)) else: sigint_timeout = self._sigint_wait_secs self._sigint_wait_secs = 0 # nothing else should wait. try: self._wait(timeout=sigint_timeout) except TimeoutExpired: pass raise # resume the KeyboardInterrupt 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 = _winapi.GetStdHandle(_winapi.STD_INPUT_HANDLE) if p2cread is None: p2cread, _ = _winapi.CreatePipe(None, 0) p2cread = Handle(p2cread) _winapi.CloseHandle(_) elif stdin == PIPE: p2cread, p2cwrite = _winapi.CreatePipe(None, 0) p2cread, p2cwrite = Handle(p2cread), Handle(p2cwrite) elif stdin == DEVNULL: p2cread = msvcrt.get_osfhandle(self._get_devnull()) 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 = _winapi.GetStdHandle(_winapi.STD_OUTPUT_HANDLE) if c2pwrite is None: _, c2pwrite = _winapi.CreatePipe(None, 0) c2pwrite = Handle(c2pwrite) _winapi.CloseHandle(_) elif stdout == PIPE: c2pread, c2pwrite = _winapi.CreatePipe(None, 0) c2pread, c2pwrite = Handle(c2pread), Handle(c2pwrite) elif stdout == DEVNULL: c2pwrite = msvcrt.get_osfhandle(self._get_devnull()) 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 = _winapi.GetStdHandle(_winapi.STD_ERROR_HANDLE) if errwrite is None: _, errwrite = _winapi.CreatePipe(None, 0) errwrite = Handle(errwrite) _winapi.CloseHandle(_) elif stderr == PIPE: errread, errwrite = _winapi.CreatePipe(None, 0) errread, errwrite = Handle(errread), Handle(errwrite) elif stderr == STDOUT: errwrite = c2pwrite elif stderr == DEVNULL: errwrite = msvcrt.get_osfhandle(self._get_devnull()) 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""" h = _winapi.DuplicateHandle( _winapi.GetCurrentProcess(), handle, _winapi.GetCurrentProcess(), 0, 1, _winapi.DUPLICATE_SAME_ACCESS) return Handle(h) def _filter_handle_list(self, handle_list): """Filter out console handles that can't be used in lpAttributeList["handle_list"] and make sure the list isn't empty. This also removes duplicate handles.""" # An handle with it's lowest two bits set might be a special console # handle that if passed in lpAttributeList["handle_list"], will # cause it to fail. return list({handle for handle in handle_list if handle & 0x3 != 0x3 or _winapi.GetFileType(handle) != _winapi.FILE_TYPE_CHAR}) def _execute_child(self, args, executable, preexec_fn, close_fds, pass_fds, cwd, env, 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() else: # bpo-34044: Copy STARTUPINFO since it is modified above, # so the caller can reuse it multiple times. startupinfo = startupinfo._copy() use_std_handles = -1 not in (p2cread, c2pwrite, errwrite) if use_std_handles: startupinfo.dwFlags |= _winapi.STARTF_USESTDHANDLES startupinfo.hStdInput = p2cread startupinfo.hStdOutput = c2pwrite startupinfo.hStdError = errwrite attribute_list = startupinfo.lpAttributeList have_handle_list = bool(attribute_list and "handle_list" in attribute_list and attribute_list["handle_list"]) # If we were given an handle_list or need to create one if have_handle_list or (use_std_handles and close_fds): if attribute_list is None: attribute_list = startupinfo.lpAttributeList = {} handle_list = attribute_list["handle_list"] = \ list(attribute_list.get("handle_list", [])) if use_std_handles: handle_list += [int(p2cread), int(c2pwrite), int(errwrite)] handle_list[:] = self._filter_handle_list(handle_list) if handle_list: if not close_fds: warnings.warn("startupinfo.lpAttributeList['handle_list'] " "overriding close_fds", RuntimeWarning) # When using the handle_list we always request to inherit # handles but the only handles that will be inherited are # the ones in the handle_list close_fds = False if shell: startupinfo.dwFlags |= _winapi.STARTF_USESHOWWINDOW startupinfo.wShowWindow = _winapi.SW_HIDE comspec = os.environ.get("COMSPEC", "cmd.exe") args = '{} /c "{}"'.format (comspec, args) # Start the process try: hp, ht, pid, tid = _winapi.CreateProcess(executable, args, # no special security None, None, int(not close_fds), creationflags, env, os.fspath(cwd) if cwd is not None else None, startupinfo) 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() if hasattr(self, '_devnull'): os.close(self._devnull) # Prevent a double close of these handles/fds from __init__ # on error. self._closed_child_pipe_fds = True # Retain the process handle, but close the thread handle self._child_created = True self._handle = Handle(hp) self.pid = pid _winapi.CloseHandle(ht) def _internal_poll(self, _deadstate=None, _WaitForSingleObject=_winapi.WaitForSingleObject, _WAIT_OBJECT_0=_winapi.WAIT_OBJECT_0, _GetExitCodeProcess=_winapi.GetExitCodeProcess): """Check if child process has terminated. Returns returncode attribute. This method is called by __del__, so it can only refer to objects in its local scope. """ if self.returncode is None: if _WaitForSingleObject(self._handle, 0) == _WAIT_OBJECT_0: self.returncode = _GetExitCodeProcess(self._handle) return self.returncode def _wait(self, timeout): """Internal implementation of wait() on Windows.""" if timeout is None: timeout_millis = _winapi.INFINITE else: timeout_millis = int(timeout * 1000) if self.returncode is None: # API note: Returns immediately if timeout_millis == 0. result = _winapi.WaitForSingleObject(self._handle, timeout_millis) if result == _winapi.WAIT_TIMEOUT: raise TimeoutExpired(self.args, timeout) self.returncode = _winapi.GetExitCodeProcess(self._handle) return self.returncode def _readerthread(self, fh, buffer): buffer.append(fh.read()) fh.close() def _communicate(self, input, endtime, orig_timeout): # Start reader threads feeding into a list hanging off of this # object, unless they've already been started. if self.stdout and not hasattr(self, "_stdout_buff"): self._stdout_buff = [] self.stdout_thread = \ threading.Thread(target=self._readerthread, args=(self.stdout, self._stdout_buff)) self.stdout_thread.daemon = True self.stdout_thread.start() if self.stderr and not hasattr(self, "_stderr_buff"): self._stderr_buff = [] self.stderr_thread = \ threading.Thread(target=self._readerthread, args=(self.stderr, self._stderr_buff)) self.stderr_thread.daemon = True self.stderr_thread.start() if self.stdin: self._stdin_write(input) # Wait for the reader threads, or time out. If we time out, the # threads remain reading and the fds left open in case the user # calls communicate again. if self.stdout is not None: self.stdout_thread.join(self._remaining_time(endtime)) if self.stdout_thread.is_alive(): raise TimeoutExpired(self.args, orig_timeout) if self.stderr is not None: self.stderr_thread.join(self._remaining_time(endtime)) if self.stderr_thread.is_alive(): raise TimeoutExpired(self.args, orig_timeout) # Collect the output from and close both pipes, now that we know # both have been read successfully. stdout = None stderr = None if self.stdout: stdout = self._stdout_buff self.stdout.close() if self.stderr: stderr = self._stderr_buff self.stderr.close() # All data exchanged. Translate lists into strings. if stdout is not None: stdout = stdout[0] if stderr is not None: stderr = stderr[0] return (stdout, stderr) def send_signal(self, sig): """Send a signal to the process.""" # Don't signal a process that we know has already died. if self.returncode is not None: return if sig == signal.SIGTERM: self.terminate() elif sig == signal.CTRL_C_EVENT: os.kill(self.pid, signal.CTRL_C_EVENT) elif sig == signal.CTRL_BREAK_EVENT: os.kill(self.pid, signal.CTRL_BREAK_EVENT) else: raise ValueError("Unsupported signal: {}".format(sig)) def terminate(self): """Terminates the process.""" # Don't terminate a process that we know has already died. if self.returncode is not None: return try: _winapi.TerminateProcess(self._handle, 1) except PermissionError: # ERROR_ACCESS_DENIED (winerror 5) is received when the # process already died. rc = _winapi.GetExitCodeProcess(self._handle) if rc == _winapi.STILL_ACTIVE: raise self.returncode = rc kill = terminate else: # # POSIX methods # def _get_handles(self, stdin, stdout, stderr): """Construct and return tuple with IO objects: p2cread, p2cwrite, c2pread, c2pwrite, errread, errwrite """ p2cread, p2cwrite = -1, -1 c2pread, c2pwrite = -1, -1 errread, errwrite = -1, -1 if stdin is None: pass elif stdin == PIPE: p2cread, p2cwrite = os.pipe() elif stdin == DEVNULL: p2cread = self._get_devnull() elif isinstance(stdin, int): p2cread = stdin else: # Assuming file-like object p2cread = stdin.fileno() if stdout is None: pass elif stdout == PIPE: c2pread, c2pwrite = os.pipe() elif stdout == DEVNULL: c2pwrite = self._get_devnull() elif isinstance(stdout, int): c2pwrite = stdout else: # Assuming file-like object c2pwrite = stdout.fileno() if stderr is None: pass elif stderr == PIPE: errread, errwrite = os.pipe() elif stderr == STDOUT: if c2pwrite != -1: errwrite = c2pwrite else: # child's stdout is not set, use parent's stdout errwrite = sys.__stdout__.fileno() elif stderr == DEVNULL: errwrite = self._get_devnull() elif isinstance(stderr, int): errwrite = stderr else: # Assuming file-like object errwrite = stderr.fileno() return (p2cread, p2cwrite, c2pread, c2pwrite, errread, errwrite) def _execute_child(self, args, executable, preexec_fn, close_fds, pass_fds, cwd, env, startupinfo, creationflags, shell, p2cread, p2cwrite, c2pread, c2pwrite, errread, errwrite, restore_signals, start_new_session): """Execute program (POSIX version)""" if isinstance(args, (str, bytes)): args = [args] else: args = list(args) if shell: # On Android the default shell is at '/system/bin/sh'. unix_shell = ('/system/bin/sh' if hasattr(sys, 'getandroidapilevel') else '/bin/sh') args = [unix_shell, "-c"] + args if executable: args[0] = executable if executable is None: executable = args[0] orig_executable = executable # For transferring possible exec failure from child to parent. # Data format: "exception name:hex errno:description" # Pickle is not used; it is complex and involves memory allocation. errpipe_read, errpipe_write = os.pipe() # errpipe_write must not be in the standard io 0, 1, or 2 fd range. low_fds_to_close = [] while errpipe_write < 3: low_fds_to_close.append(errpipe_write) errpipe_write = os.dup(errpipe_write) for low_fd in low_fds_to_close: os.close(low_fd) try: try: # We must avoid complex work that could involve # malloc or free in the child process to avoid # potential deadlocks, thus we do all this here. # and pass it to fork_exec() if env is not None: env_list = [] for k, v in env.items(): k = os.fsencode(k) if b'=' in k: raise ValueError("illegal environment variable name") env_list.append(k + b'=' + os.fsencode(v)) else: env_list = None # Use execv instead of execve. executable = os.fsencode(executable) if os.path.dirname(executable): executable_list = (executable,) else: # This matches the behavior of os._execvpe(). executable_list = tuple( os.path.join(os.fsencode(dir), executable) for dir in os.get_exec_path(env)) fds_to_keep = set(pass_fds) fds_to_keep.add(errpipe_write) self.pid = _posixsubprocess.fork_exec( args, executable_list, close_fds, tuple(sorted(map(int, fds_to_keep))), cwd, env_list, p2cread, p2cwrite, c2pread, c2pwrite, errread, errwrite, errpipe_read, errpipe_write, restore_signals, start_new_session, preexec_fn) self._child_created = True finally: # be sure the FD is closed no matter what os.close(errpipe_write) # self._devnull is not always defined. devnull_fd = getattr(self, '_devnull', None) if p2cread != -1 and p2cwrite != -1 and p2cread != devnull_fd: os.close(p2cread) if c2pwrite != -1 and c2pread != -1 and c2pwrite != devnull_fd: os.close(c2pwrite) if errwrite != -1 and errread != -1 and errwrite != devnull_fd: os.close(errwrite) if devnull_fd is not None: os.close(devnull_fd) # Prevent a double close of these fds from __init__ on error. self._closed_child_pipe_fds = True # Wait for exec to fail or succeed; possibly raising an # exception (limited in size) errpipe_data = bytearray() while True: part = os.read(errpipe_read, 50000) errpipe_data += part if not part or len(errpipe_data) > 50000: break finally: # be sure the FD is closed no matter what os.close(errpipe_read) if errpipe_data: try: pid, sts = os.waitpid(self.pid, 0) if pid == self.pid: self._handle_exitstatus(sts) else: self.returncode = sys.maxsize except ChildProcessError: pass try: exception_name, hex_errno, err_msg = ( errpipe_data.split(b':', 2)) # The encoding here should match the encoding # written in by the subprocess implementations # like _posixsubprocess err_msg = err_msg.decode() except ValueError: exception_name = b'SubprocessError' hex_errno = b'0' err_msg = 'Bad exception data from child: {!r}'.format( bytes(errpipe_data)) child_exception_type = getattr( builtins, exception_name.decode('ascii'), SubprocessError) if issubclass(child_exception_type, OSError) and hex_errno: errno_num = int(hex_errno, 16) child_exec_never_called = (err_msg == "noexec") if child_exec_never_called: err_msg = "" # The error must be from chdir(cwd). err_filename = cwd else: err_filename = orig_executable if errno_num != 0: err_msg = os.strerror(errno_num) if errno_num == errno.ENOENT: err_msg += ': ' + repr(err_filename) raise child_exception_type(errno_num, err_msg, err_filename) raise child_exception_type(err_msg) def _handle_exitstatus(self, sts, _WIFSIGNALED=os.WIFSIGNALED, _WTERMSIG=os.WTERMSIG, _WIFEXITED=os.WIFEXITED, _WEXITSTATUS=os.WEXITSTATUS, _WIFSTOPPED=os.WIFSTOPPED, _WSTOPSIG=os.WSTOPSIG): """All callers to this function MUST hold self._waitpid_lock.""" # This method is called (indirectly) by __del__, so it cannot # refer to anything outside of its local scope. if _WIFSIGNALED(sts): self.returncode = -_WTERMSIG(sts) elif _WIFEXITED(sts): self.returncode = _WEXITSTATUS(sts) elif _WIFSTOPPED(sts): self.returncode = -_WSTOPSIG(sts) else: # Should never happen raise SubprocessError("Unknown child exit status!") def _internal_poll(self, _deadstate=None, _waitpid=os.waitpid, _WNOHANG=os.WNOHANG, _ECHILD=errno.ECHILD): """Check if child process has terminated. Returns returncode attribute. This method is called by __del__, so it cannot reference anything outside of the local scope (nor can any methods it calls). """ if self.returncode is None: if not self._waitpid_lock.acquire(False): # Something else is busy calling waitpid. Don't allow two # at once. We know nothing yet. return None try: if self.returncode is not None: return self.returncode # Another thread waited. pid, sts = _waitpid(self.pid, _WNOHANG) if pid == self.pid: self._handle_exitstatus(sts) except OSError as e: if _deadstate is not None: self.returncode = _deadstate elif e.errno == _ECHILD: # This happens if SIGCLD is set to be ignored or # waiting for child processes has otherwise been # disabled for our process. This child is dead, we # can't get the status. # http://bugs.python.org/issue15756 self.returncode = 0 finally: self._waitpid_lock.release() return self.returncode def _try_wait(self, wait_flags): """All callers to this function MUST hold self._waitpid_lock.""" try: (pid, sts) = os.waitpid(self.pid, wait_flags) except ChildProcessError: # This happens if SIGCLD is set to be ignored or waiting # for child processes has otherwise been disabled for our # process. This child is dead, we can't get the status. pid = self.pid sts = 0 return (pid, sts) def _wait(self, timeout): """Internal implementation of wait() on POSIX.""" if self.returncode is not None: return self.returncode if timeout is not None: endtime = _time() + timeout # Enter a busy loop if we have a timeout. This busy loop was # cribbed from Lib/threading.py in Thread.wait() at r71065. delay = 0.0005 # 500 us -> initial delay of 1 ms while True: if self._waitpid_lock.acquire(False): try: if self.returncode is not None: break # Another thread waited. (pid, sts) = self._try_wait(os.WNOHANG) assert pid == self.pid or pid == 0 if pid == self.pid: self._handle_exitstatus(sts) break finally: self._waitpid_lock.release() remaining = self._remaining_time(endtime) if remaining <= 0: raise TimeoutExpired(self.args, timeout) delay = min(delay * 2, remaining, .05) time.sleep(delay) else: while self.returncode is None: with self._waitpid_lock: if self.returncode is not None: break # Another thread waited. (pid, sts) = self._try_wait(0) # Check the pid and loop as waitpid has been known to # return 0 even without WNOHANG in odd situations. # http://bugs.python.org/issue14396. if pid == self.pid: self._handle_exitstatus(sts) return self.returncode def _communicate(self, input, endtime, orig_timeout): if self.stdin and not self._communication_started: # Flush stdio buffer. This might block, if the user has # been writing to .stdin in an uncontrolled fashion. try: self.stdin.flush() except BrokenPipeError: pass # communicate() must ignore BrokenPipeError. if not input: try: self.stdin.close() except BrokenPipeError: pass # communicate() must ignore BrokenPipeError. stdout = None stderr = None # Only create this mapping if we haven't already. if not self._communication_started: self._fileobj2output = {} if self.stdout: self._fileobj2output[self.stdout] = [] if self.stderr: self._fileobj2output[self.stderr] = [] if self.stdout: stdout = self._fileobj2output[self.stdout] if self.stderr: stderr = self._fileobj2output[self.stderr] self._save_input(input) if self._input: input_view = memoryview(self._input) with _PopenSelector() as selector: if self.stdin and input: selector.register(self.stdin, selectors.EVENT_WRITE) if self.stdout: selector.register(self.stdout, selectors.EVENT_READ) if self.stderr: selector.register(self.stderr, selectors.EVENT_READ) while selector.get_map(): timeout = self._remaining_time(endtime) if timeout is not None and timeout < 0: raise TimeoutExpired(self.args, orig_timeout) ready = selector.select(timeout) self._check_timeout(endtime, orig_timeout) # XXX Rewrite these to use non-blocking I/O on the file # objects; they are no longer using C stdio! for key, events in ready: if key.fileobj is self.stdin: chunk = input_view[self._input_offset : self._input_offset + _PIPE_BUF] try: self._input_offset += os.write(key.fd, chunk) except BrokenPipeError: selector.unregister(key.fileobj) key.fileobj.close() else: if self._input_offset >= len(self._input): selector.unregister(key.fileobj) key.fileobj.close() elif key.fileobj in (self.stdout, self.stderr): data = os.read(key.fd, 32768) if not data: selector.unregister(key.fileobj) key.fileobj.close() self._fileobj2output[key.fileobj].append(data) self.wait(timeout=self._remaining_time(endtime)) # All data exchanged. Translate lists into strings. if stdout is not None: stdout = b''.join(stdout) if stderr is not None: stderr = b''.join(stderr) # Translate newlines, if requested. # This also turns bytes into strings. if self.text_mode: if stdout is not None: stdout = self._translate_newlines(stdout, self.stdout.encoding, self.stdout.errors) if stderr is not None: stderr = self._translate_newlines(stderr, self.stderr.encoding, self.stderr.errors) return (stdout, stderr) def _save_input(self, input): # This method is called from the _communicate_with_*() methods # so that if we time out while communicating, we can continue # sending input if we retry. if self.stdin and self._input is None: self._input_offset = 0 self._input = input if input is not None and self.text_mode: self._input = self._input.encode(self.stdin.encoding, self.stdin.errors) def send_signal(self, sig): """Send a signal to the process.""" # Skip signalling a process that we know has already died. if self.returncode is None: os.kill(self.pid, sig) def terminate(self): """Terminate the process with SIGTERM """ self.send_signal(signal.SIGTERM) def kill(self): """Kill the process with SIGKILL """ self.send_signal(signal.SIGKILL)