diff options
Diffstat (limited to 'Lib/subprocess.py')
| -rw-r--r-- | Lib/subprocess.py | 849 |
1 files changed, 454 insertions, 395 deletions
diff --git a/Lib/subprocess.py b/Lib/subprocess.py index a322829..d3d90ca 100644 --- a/Lib/subprocess.py +++ b/Lib/subprocess.py @@ -191,8 +191,10 @@ 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. +Exceptions defined within this module inherit from SubprocessError. +check_call() and check_output() will raise CalledProcessError if the +called process returns a non-zero return code. TimeoutExpired +be raised if a timeout was specified and expired. Security @@ -340,15 +342,23 @@ mswindows = (sys.platform == "win32") import io import os +import time import traceback import gc import signal import builtins import warnings import errno +try: + from time import monotonic as _time +except ImportError: + from time import time as _time # Exception classes used by this module. -class CalledProcessError(Exception): +class SubprocessError(Exception): pass + + +class CalledProcessError(SubprocessError): """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; @@ -362,10 +372,24 @@ class CalledProcessError(Exception): return "Command '%s' returned non-zero exit status %d" % (self.cmd, self.returncode) +class TimeoutExpired(SubprocessError): + """This exception is raised when the timeout expires while waiting for a + child process. + """ + def __init__(self, cmd, timeout, output=None): + self.cmd = cmd + self.timeout = timeout + self.output = output + + def __str__(self): + return ("Command '%s' timed out after %s seconds" % + (self.cmd, self.timeout)) + + if mswindows: import threading import msvcrt - import _subprocess + import _winapi class STARTUPINFO: dwFlags = 0 hStdInput = None @@ -377,53 +401,49 @@ if mswindows: 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) + import _posixsubprocess + _create_pipe = _posixsubprocess.cloexec_pipe # 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"] + "getoutput", "check_output", "CalledProcessError", "DEVNULL"] 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) + 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) __all__.extend(["CREATE_NEW_CONSOLE", "CREATE_NEW_PROCESS_GROUP", "STD_INPUT_HANDLE", "STD_OUTPUT_HANDLE", "STD_ERROR_HANDLE", "SW_HIDE", "STARTF_USESTDHANDLES", "STARTF_USESHOWWINDOW"]) + + 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 "Handle(%d)" % int(self) + + __del__ = Close + __str__ = __repr__ + try: MAXFD = os.sysconf("SC_OPEN_MAX") except: @@ -448,27 +468,63 @@ def _cleanup(): PIPE = -1 STDOUT = -2 +DEVNULL = -3 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. + except InterruptedError: + continue + + +# 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 _args_from_interpreter_flags(): + """Return a list of command-line arguments reproducing the current + settings in sys.flags and sys.warnoptions.""" + flag_opt_map = { + 'debug': 'd', + # 'inspect': 'i', + # 'interactive': 'i', + 'optimize': 'O', + 'dont_write_bytecode': 'B', + 'no_user_site': 's', + 'no_site': 'S', + 'ignore_environment': 'E', + 'verbose': 'v', + 'bytes_warning': 'b', + 'quiet': 'q', + 'hash_randomization': 'R', + } + args = [] + for flag, opt in flag_opt_map.items(): + v = getattr(sys.flags, flag) + if v > 0: + args.append('-' + opt * v) + for opt in sys.warnoptions: + args.append('-W' + opt) + 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"]) """ - return Popen(*popenargs, **kwargs).wait() + with Popen(*popenargs, **kwargs) as p: + try: + return p.wait(timeout=timeout) + except: + p.kill() + p.wait() + raise def check_call(*popenargs, **kwargs): @@ -477,7 +533,7 @@ def check_call(*popenargs, **kwargs): CalledProcessError. The CalledProcessError object will have the return code in the returncode attribute. - The arguments are the same as for the Popen constructor. Example: + The arguments are the same as for the call function. Example: check_call(["ls", "-l"]) """ @@ -490,7 +546,7 @@ def check_call(*popenargs, **kwargs): return 0 -def check_output(*popenargs, **kwargs): +def check_output(*popenargs, timeout=None, **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 @@ -512,14 +568,20 @@ def check_output(*popenargs, **kwargs): """ 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) + with Popen(*popenargs, stdout=PIPE, **kwargs) as process: + try: + output, unused_err = process.communicate(timeout=timeout) + except TimeoutExpired: + process.kill() + output, unused_err = process.communicate() + raise TimeoutExpired(process.args, timeout, output=output) + except: + process.kill() + process.wait() + raise + retcode = process.poll() + if retcode: + raise CalledProcessError(retcode, process.args, output=output) return output @@ -614,11 +676,19 @@ def getstatusoutput(cmd): >>> 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] + with os.popen('{ ' + cmd + '; } 2>&1', 'r') as pipe: + try: + text = pipe.read() + sts = pipe.close() + except: + process = pipe._proc + process.kill() + process.wait() + raise + if sts is None: + sts = 0 + if text[-1:] == '\n': + text = text[:-1] return sts, text @@ -650,6 +720,8 @@ class Popen(object): _cleanup() self._child_created = False + self._input = None + self._communication_started = False if bufsize is None: bufsize = 0 # Restore default if not isinstance(bufsize, int): @@ -684,6 +756,7 @@ class Popen(object): raise ValueError("creationflags is only supported on Windows " "platforms") + self.args = args self.stdin = None self.stdout = None self.stderr = None @@ -724,7 +797,7 @@ class Popen(object): if p2cwrite != -1: self.stdin = io.open(p2cwrite, 'wb', bufsize) - if self.universal_newlines: + if universal_newlines: self.stdin = io.TextIOWrapper(self.stdin, write_through=True) if c2pread != -1: self.stdout = io.open(c2pread, 'rb', bufsize) @@ -737,7 +810,7 @@ class Popen(object): try: self._execute_child(args, executable, preexec_fn, close_fds, - pass_fds, cwd, env, universal_newlines, + pass_fds, cwd, env, startupinfo, creationflags, shell, p2cread, p2cwrite, c2pread, c2pwrite, @@ -798,19 +871,28 @@ class Popen(object): # 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 communicate(self, input=None): + def communicate(self, input=None, timeout=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 + process to terminate. The optional input argument should be + bytes 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: + 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: @@ -828,15 +910,42 @@ class Popen(object): stderr = _eintr_retry_call(self.stderr.read) self.stderr.close() self.wait() - return (stdout, stderr) + else: + if timeout is not None: + endtime = _time() + timeout + else: + endtime = None + + try: + stdout, stderr = self._communicate(input, endtime, timeout) + finally: + self._communication_started = True - return self._communicate(input) + sts = self.wait(timeout=self._remaining_time(endtime)) + + return (stdout, stderr) def poll(self): 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) + + if mswindows: # # Windows methods @@ -853,11 +962,16 @@ class Popen(object): errread, errwrite = -1, -1 if stdin is None: - p2cread = _subprocess.GetStdHandle(_subprocess.STD_INPUT_HANDLE) + p2cread = _winapi.GetStdHandle(_winapi.STD_INPUT_HANDLE) if p2cread is None: - p2cread, _ = _subprocess.CreatePipe(None, 0) + p2cread, _ = _winapi.CreatePipe(None, 0) + p2cread = Handle(p2cread) + _winapi.CloseHandle(_) elif stdin == PIPE: - p2cread, p2cwrite = _subprocess.CreatePipe(None, 0) + 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: @@ -866,11 +980,16 @@ class Popen(object): p2cread = self._make_inheritable(p2cread) if stdout is None: - c2pwrite = _subprocess.GetStdHandle(_subprocess.STD_OUTPUT_HANDLE) + c2pwrite = _winapi.GetStdHandle(_winapi.STD_OUTPUT_HANDLE) if c2pwrite is None: - _, c2pwrite = _subprocess.CreatePipe(None, 0) + _, c2pwrite = _winapi.CreatePipe(None, 0) + c2pwrite = Handle(c2pwrite) + _winapi.CloseHandle(_) elif stdout == PIPE: - c2pread, c2pwrite = _subprocess.CreatePipe(None, 0) + 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: @@ -879,13 +998,18 @@ class Popen(object): c2pwrite = self._make_inheritable(c2pwrite) if stderr is None: - errwrite = _subprocess.GetStdHandle(_subprocess.STD_ERROR_HANDLE) + errwrite = _winapi.GetStdHandle(_winapi.STD_ERROR_HANDLE) if errwrite is None: - _, errwrite = _subprocess.CreatePipe(None, 0) + _, errwrite = _winapi.CreatePipe(None, 0) + errwrite = Handle(errwrite) + _winapi.CloseHandle(_) elif stderr == PIPE: - errread, errwrite = _subprocess.CreatePipe(None, 0) + 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: @@ -900,20 +1024,22 @@ class Popen(object): 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) + h = _winapi.DuplicateHandle( + _winapi.GetCurrentProcess(), handle, + _winapi.GetCurrentProcess(), 0, 1, + _winapi.DUPLICATE_SAME_ACCESS) + return Handle(h) def _find_w9xpopen(self): """Find and return absolut path to w9xpopen.exe""" w9xpopen = os.path.join( - os.path.dirname(_subprocess.GetModuleFileName(0)), + os.path.dirname(_winapi.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 = os.path.join(os.path.dirname(sys.base_exec_prefix), "w9xpopen.exe") if not os.path.exists(w9xpopen): raise RuntimeError("Cannot locate w9xpopen.exe, which is " @@ -923,7 +1049,7 @@ class Popen(object): def _execute_child(self, args, executable, preexec_fn, close_fds, - pass_fds, cwd, env, universal_newlines, + pass_fds, cwd, env, startupinfo, creationflags, shell, p2cread, p2cwrite, c2pread, c2pwrite, @@ -940,17 +1066,17 @@ class Popen(object): if startupinfo is None: startupinfo = STARTUPINFO() if -1 not in (p2cread, c2pwrite, errwrite): - startupinfo.dwFlags |= _subprocess.STARTF_USESTDHANDLES + startupinfo.dwFlags |= _winapi.STARTF_USESTDHANDLES startupinfo.hStdInput = p2cread startupinfo.hStdOutput = c2pwrite startupinfo.hStdError = errwrite if shell: - startupinfo.dwFlags |= _subprocess.STARTF_USESHOWWINDOW - startupinfo.wShowWindow = _subprocess.SW_HIDE + startupinfo.dwFlags |= _winapi.STARTF_USESHOWWINDOW + startupinfo.wShowWindow = _winapi.SW_HIDE comspec = os.environ.get("COMSPEC", "cmd.exe") args = '{} /c "{}"'.format (comspec, args) - if (_subprocess.GetVersion() >= 0x80000000 or + if (_winapi.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 @@ -964,11 +1090,11 @@ class Popen(object): # 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 + creationflags |= _winapi.CREATE_NEW_CONSOLE # Start the process try: - hp, ht, pid, tid = _subprocess.CreateProcess(executable, args, + hp, ht, pid, tid = _winapi.CreateProcess(executable, args, # no special security None, None, int(not close_fds), @@ -995,17 +1121,19 @@ class Popen(object): c2pwrite.Close() if errwrite != -1: errwrite.Close() + if hasattr(self, '_devnull'): + os.close(self._devnull) # Retain the process handle, but close the thread handle self._child_created = True - self._handle = hp + self._handle = Handle(hp) self.pid = pid - ht.Close() + _winapi.CloseHandle(ht) def _internal_poll(self, _deadstate=None, - _WaitForSingleObject=_subprocess.WaitForSingleObject, - _WAIT_OBJECT_0=_subprocess.WAIT_OBJECT_0, - _GetExitCodeProcess=_subprocess.GetExitCodeProcess): + _WaitForSingleObject=_winapi.WaitForSingleObject, + _WAIT_OBJECT_0=_winapi.WAIT_OBJECT_0, + _GetExitCodeProcess=_winapi.GetExitCodeProcess): """Check if child process has terminated. Returns returncode attribute. @@ -1019,13 +1147,21 @@ class Popen(object): return self.returncode - def wait(self): + def wait(self, timeout=None, endtime=None): """Wait for child process to terminate. Returns returncode attribute.""" + if endtime is not None: + timeout = self._remaining_time(endtime) + if timeout is None: + timeout_millis = _winapi.INFINITE + else: + timeout_millis = int(timeout * 1000) if self.returncode is None: - _subprocess.WaitForSingleObject(self._handle, - _subprocess.INFINITE) - self.returncode = _subprocess.GetExitCodeProcess(self._handle) + 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 @@ -1034,22 +1170,23 @@ class Popen(object): fh.close() - def _communicate(self, input): - stdout = None # Return - stderr = None # Return - - if self.stdout: - stdout = [] - stdout_thread = threading.Thread(target=self._readerthread, - args=(self.stdout, stdout)) - stdout_thread.daemon = True - stdout_thread.start() - if self.stderr: - stderr = [] - stderr_thread = threading.Thread(target=self._readerthread, - args=(self.stderr, stderr)) - stderr_thread.daemon = True - stderr_thread.start() + 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: if input is not None: @@ -1060,10 +1197,28 @@ class Popen(object): raise self.stdin.close() + # 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_thread.join() + stdout = self._stdout_buff + self.stdout.close() if self.stderr: - stderr_thread.join() + stderr = self._stderr_buff + self.stderr.close() # All data exchanged. Translate lists into strings. if stdout is not None: @@ -1071,7 +1226,6 @@ class Popen(object): if stderr is not None: stderr = stderr[0] - self.wait() return (stdout, stderr) def send_signal(self, sig): @@ -1090,14 +1244,12 @@ class Popen(object): """Terminates the process """ try: - _subprocess.TerminateProcess(self._handle, 1) - except OSError as e: + _winapi.TerminateProcess(self._handle, 1) + except PermissionError: # ERROR_ACCESS_DENIED (winerror 5) is received when the # process already died. - if e.winerror != 5: - raise - rc = _subprocess.GetExitCodeProcess(self._handle) - if rc == _subprocess.STILL_ACTIVE: + rc = _winapi.GetExitCodeProcess(self._handle) + if rc == _winapi.STILL_ACTIVE: raise self.returncode = rc @@ -1119,6 +1271,8 @@ class Popen(object): pass elif stdin == PIPE: p2cread, p2cwrite = _create_pipe() + elif stdin == DEVNULL: + p2cread = self._get_devnull() elif isinstance(stdin, int): p2cread = stdin else: @@ -1129,6 +1283,8 @@ class Popen(object): pass elif stdout == PIPE: c2pread, c2pwrite = _create_pipe() + elif stdout == DEVNULL: + c2pwrite = self._get_devnull() elif isinstance(stdout, int): c2pwrite = stdout else: @@ -1141,6 +1297,8 @@ class Popen(object): errread, errwrite = _create_pipe() elif stderr == STDOUT: errwrite = c2pwrite + elif stderr == DEVNULL: + errwrite = self._get_devnull() elif isinstance(stderr, int): errwrite = stderr else: @@ -1163,7 +1321,7 @@ class Popen(object): def _execute_child(self, args, executable, preexec_fn, close_fds, - pass_fds, cwd, env, universal_newlines, + pass_fds, cwd, env, startupinfo, creationflags, shell, p2cread, p2cwrite, c2pread, c2pwrite, @@ -1171,7 +1329,7 @@ class Popen(object): restore_signals, start_new_session): """Execute program (POSIX version)""" - if isinstance(args, str): + if isinstance(args, (str, bytes)): args = [args] else: args = list(args) @@ -1191,153 +1349,34 @@ class Popen(object): errpipe_read, errpipe_write = _create_pipe() try: try: - - if _posixsubprocess: - # 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 = [os.fsencode(k) + b'=' + os.fsencode(v) - for k, v in env.items()] - 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, sorted(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 + # 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 = [os.fsencode(k) + b'=' + os.fsencode(v) + for k, v in env.items()] else: - # Pure Python implementation: It is not thread safe. - # This implementation may deadlock in the child if your - # parent process has any other threads running. - - gc_was_enabled = gc.isenabled() - # Disable gc to avoid bug where gc -> file_dealloc -> - # write to stderr -> hang. See issue1336 - gc.disable() - try: - self.pid = os.fork() - except: - if gc_was_enabled: - gc.enable() - raise - self._child_created = True - if self.pid == 0: - # Child - reached_preexec = False - try: - # Close parent's pipe ends - if p2cwrite != -1: - os.close(p2cwrite) - if c2pread != -1: - os.close(c2pread) - if errread != -1: - os.close(errread) - os.close(errpipe_read) - - # When duping fds, if there arises a situation - # where one of the fds is either 0, 1 or 2, it - # is possible that it is overwritten (#12607). - if c2pwrite == 0: - c2pwrite = os.dup(c2pwrite) - if errwrite == 0 or errwrite == 1: - errwrite = os.dup(errwrite) - - # Dup fds for child - def _dup2(a, b): - # dup2() removes the CLOEXEC flag but - # we must do it ourselves if dup2() - # would be a no-op (issue #10806). - if a == b: - _set_cloexec(a, False) - elif a != -1: - os.dup2(a, b) - _dup2(p2cread, 0) - _dup2(c2pwrite, 1) - _dup2(errwrite, 2) - - # Close pipe fds. Make sure we don't close the - # same fd more than once, or standard fds. - closed = set() - for fd in [p2cread, c2pwrite, errwrite]: - if fd > 2 and fd not in closed: - os.close(fd) - closed.add(fd) - - # Close all other fds, if asked for - if close_fds: - fds_to_keep = set(pass_fds) - fds_to_keep.add(errpipe_write) - self._close_fds(fds_to_keep) - - - if cwd is not None: - os.chdir(cwd) - - # This is a copy of Python/pythonrun.c - # _Py_RestoreSignals(). If that were exposed - # as a sys._py_restoresignals func it would be - # better.. but this pure python implementation - # isn't likely to be used much anymore. - if restore_signals: - signals = ('SIGPIPE', 'SIGXFZ', 'SIGXFSZ') - for sig in signals: - if hasattr(signal, sig): - signal.signal(getattr(signal, sig), - signal.SIG_DFL) - - if start_new_session and hasattr(os, 'setsid'): - os.setsid() - - reached_preexec = True - if preexec_fn: - preexec_fn() - - if env is None: - os.execvp(executable, args) - else: - os.execvpe(executable, args, env) - - except: - try: - exc_type, exc_value = sys.exc_info()[:2] - if isinstance(exc_value, OSError): - errno_num = exc_value.errno - else: - errno_num = 0 - if not reached_preexec: - exc_value = "noexec" - message = '%s:%x:%s' % (exc_type.__name__, - errno_num, exc_value) - message = message.encode(errors="surrogatepass") - os.write(errpipe_write, message) - except Exception: - # We MUST not allow anything odd happening - # above to prevent us from exiting below. - pass - - # This exitcode won't be reported to applications - # so it really doesn't matter what we return. - os._exit(255) - - # Parent - if gc_was_enabled: - gc.enable() + 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, sorted(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) @@ -1348,6 +1387,8 @@ class Popen(object): os.close(c2pwrite) if errwrite != -1 and errread != -1: os.close(errwrite) + if hasattr(self, '_devnull'): + os.close(self._devnull) # Wait for exec to fail or succeed; possibly raising an # exception (limited in size) @@ -1437,29 +1478,61 @@ class Popen(object): return self.returncode - def wait(self): + def _try_wait(self, wait_flags): + try: + (pid, sts) = _eintr_retry_call(os.waitpid, self.pid, wait_flags) + except OSError as e: + if e.errno != errno.ECHILD: + raise + # 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=None, endtime=None): """Wait for child process to terminate. Returns returncode attribute.""" - while self.returncode is None: - try: - pid, sts = _eintr_retry_call(os.waitpid, self.pid, 0) - except OSError as e: - if e.errno != errno.ECHILD: - raise - # 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 - # Check the pid and loop as waitpid has been known to return - # 0 even without WNOHANG in odd situations. issue14396. - if pid == self.pid: - self._handle_exitstatus(sts) + if self.returncode is not None: + return self.returncode + + # endtime is preferred to timeout. timeout is only used for + # printing. + if endtime is not None or timeout is not None: + if endtime is None: + endtime = _time() + timeout + elif timeout is None: + timeout = self._remaining_time(endtime) + + if endtime is not None: + # 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: + (pid, sts) = self._try_wait(os.WNOHANG) + assert pid == self.pid or pid == 0 + if pid == self.pid: + self._handle_exitstatus(sts) + break + 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: + (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. issue14396. + if pid == self.pid: + self._handle_exitstatus(sts) return self.returncode - def _communicate(self, input): - if self.stdin: + 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. self.stdin.flush() @@ -1467,9 +1540,13 @@ class Popen(object): self.stdin.close() if _has_poll: - stdout, stderr = self._communicate_with_poll(input) + stdout, stderr = self._communicate_with_poll(input, endtime, + orig_timeout) else: - stdout, stderr = self._communicate_with_select(input) + stdout, stderr = self._communicate_with_select(input, endtime, + orig_timeout) + + self.wait(timeout=self._remaining_time(endtime)) # All data exchanged. Translate lists into strings. if stdout is not None: @@ -1487,67 +1564,92 @@ class Popen(object): stderr = self._translate_newlines(stderr, self.stderr.encoding) - self.wait() return (stdout, stderr) - def _communicate_with_poll(self, input): + 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 self.universal_newlines and input is not None: + self._input = self._input.encode(self.stdin.encoding) + + + def _communicate_with_poll(self, input, endtime, orig_timeout): stdout = None # Return stderr = None # Return - fd2file = {} - fd2output = {} + + if not self._communication_started: + self._fd2file = {} poller = select.poll() def register_and_append(file_obj, eventmask): poller.register(file_obj.fileno(), eventmask) - fd2file[file_obj.fileno()] = file_obj + self._fd2file[file_obj.fileno()] = file_obj def close_unregister_and_remove(fd): poller.unregister(fd) - fd2file[fd].close() - fd2file.pop(fd) + self._fd2file[fd].close() + self._fd2file.pop(fd) if self.stdin and input: register_and_append(self.stdin, select.POLLOUT) + # Only create this mapping if we haven't already. + if not self._communication_started: + self._fd2output = {} + if self.stdout: + self._fd2output[self.stdout.fileno()] = [] + if self.stderr: + self._fd2output[self.stderr.fileno()] = [] + select_POLLIN_POLLPRI = select.POLLIN | select.POLLPRI if self.stdout: register_and_append(self.stdout, select_POLLIN_POLLPRI) - fd2output[self.stdout.fileno()] = stdout = [] + stdout = self._fd2output[self.stdout.fileno()] if self.stderr: register_and_append(self.stderr, select_POLLIN_POLLPRI) - fd2output[self.stderr.fileno()] = stderr = [] + stderr = self._fd2output[self.stderr.fileno()] - input_offset = 0 - while fd2file: + self._save_input(input) + + while self._fd2file: + timeout = self._remaining_time(endtime) + if timeout is not None and timeout < 0: + raise TimeoutExpired(self.args, orig_timeout) try: - ready = poller.poll() + ready = poller.poll(timeout) except select.error as e: if e.args[0] == errno.EINTR: continue raise + 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 fd, mode in ready: if mode & select.POLLOUT: - chunk = input[input_offset : input_offset + _PIPE_BUF] + chunk = self._input[self._input_offset : + self._input_offset + _PIPE_BUF] try: - input_offset += os.write(fd, chunk) + self._input_offset += os.write(fd, chunk) except OSError as e: if e.errno == errno.EPIPE: close_unregister_and_remove(fd) else: raise else: - if input_offset >= len(input): + if self._input_offset >= len(self._input): close_unregister_and_remove(fd) elif mode & select_POLLIN_POLLPRI: data = os.read(fd, 4096) if not data: close_unregister_and_remove(fd) - fd2output[fd].append(data) + self._fd2output[fd].append(data) else: # Ignore hang up or errors. close_unregister_and_remove(fd) @@ -1555,61 +1657,83 @@ class Popen(object): return (stdout, stderr) - def _communicate_with_select(self, input): - read_set = [] - write_set = [] + def _communicate_with_select(self, input, endtime, orig_timeout): + if not self._communication_started: + self._read_set = [] + self._write_set = [] + if self.stdin and input: + self._write_set.append(self.stdin) + if self.stdout: + self._read_set.append(self.stdout) + if self.stderr: + self._read_set.append(self.stderr) + + self._save_input(input) + stdout = None # Return stderr = None # Return - if self.stdin and input: - write_set.append(self.stdin) if self.stdout: - read_set.append(self.stdout) - stdout = [] + if not self._communication_started: + self._stdout_buff = [] + stdout = self._stdout_buff if self.stderr: - read_set.append(self.stderr) - stderr = [] - - input_offset = 0 - while read_set or write_set: + if not self._communication_started: + self._stderr_buff = [] + stderr = self._stderr_buff + + while self._read_set or self._write_set: + timeout = self._remaining_time(endtime) + if timeout is not None and timeout < 0: + raise TimeoutExpired(self.args, orig_timeout) try: - rlist, wlist, xlist = select.select(read_set, write_set, []) + (rlist, wlist, xlist) = \ + select.select(self._read_set, self._write_set, [], + timeout) except select.error as e: if e.args[0] == errno.EINTR: continue raise + # According to the docs, returning three empty lists indicates + # that the timeout expired. + if not (rlist or wlist or xlist): + raise TimeoutExpired(self.args, orig_timeout) + # We also check what time it is ourselves for good measure. + 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! if self.stdin in wlist: - chunk = input[input_offset : input_offset + _PIPE_BUF] + chunk = self._input[self._input_offset : + self._input_offset + _PIPE_BUF] try: bytes_written = os.write(self.stdin.fileno(), chunk) except OSError as e: if e.errno == errno.EPIPE: self.stdin.close() - write_set.remove(self.stdin) + self._write_set.remove(self.stdin) else: raise else: - input_offset += bytes_written - if input_offset >= len(input): + self._input_offset += bytes_written + if self._input_offset >= len(self._input): self.stdin.close() - write_set.remove(self.stdin) + self._write_set.remove(self.stdin) if self.stdout in rlist: data = os.read(self.stdout.fileno(), 1024) if not data: self.stdout.close() - read_set.remove(self.stdout) + self._read_set.remove(self.stdout) stdout.append(data) if self.stderr in rlist: data = os.read(self.stderr.fileno(), 1024) if not data: self.stderr.close() - read_set.remove(self.stderr) + self._read_set.remove(self.stderr) stderr.append(data) return (stdout, stderr) @@ -1629,68 +1753,3 @@ class Popen(object): """Kill the process with SIGKILL """ self.send_signal(signal.SIGKILL) - - -def _demo_posix(): - # - # Example 1: Simple redirection: Get process list - # - plist = Popen(["ps"], stdout=PIPE).communicate()[0] - print("Process list:") - print(plist) - - # - # Example 2: Change uid before executing child - # - if os.getuid() == 0: - p = Popen(["id"], preexec_fn=lambda: os.setuid(100)) - p.wait() - - # - # Example 3: Connecting several subprocesses - # - print("Looking for 'hda'...") - p1 = Popen(["dmesg"], stdout=PIPE) - p2 = Popen(["grep", "hda"], stdin=p1.stdout, stdout=PIPE) - print(repr(p2.communicate()[0])) - - # - # Example 4: Catch execution error - # - print() - print("Trying a weird file...") - try: - print(Popen(["/this/path/does/not/exist"]).communicate()) - except OSError as e: - if e.errno == errno.ENOENT: - print("The file didn't exist. I thought so...") - print("Child traceback:") - print(e.child_traceback) - else: - print("Error", e.errno) - else: - print("Gosh. No error.", file=sys.stderr) - - -def _demo_windows(): - # - # Example 1: Connecting several subprocesses - # - print("Looking for 'PROMPT' in set output...") - p1 = Popen("set", stdout=PIPE, shell=True) - p2 = Popen('find "PROMPT"', stdin=p1.stdout, stdout=PIPE) - print(repr(p2.communicate()[0])) - - # - # Example 2: Simple execution of program - # - print("Executing calc...") - p = Popen("calc") - p.wait() - - -if __name__ == "__main__": - if mswindows: - _demo_windows() - else: - _demo_posix() |