diff options
Diffstat (limited to 'Lib/subprocess.py')
| -rw-r--r-- | Lib/subprocess.py | 449 |
1 files changed, 288 insertions, 161 deletions
diff --git a/Lib/subprocess.py b/Lib/subprocess.py index b3fb935..e4bb78e 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 @@ -340,6 +342,7 @@ mswindows = (sys.platform == "win32") import io import os +import time import traceback import gc import signal @@ -348,7 +351,10 @@ import warnings import errno # 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; @@ -362,6 +368,20 @@ 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 @@ -412,7 +432,7 @@ else: 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 @@ -437,6 +457,7 @@ def _cleanup(): PIPE = -1 STDOUT = -2 +DEVNULL = -3 def _eintr_retry_call(func, *args): @@ -449,15 +470,21 @@ def _eintr_retry_call(func, *args): raise -def call(*popenargs, **kwargs): - """Run command with arguments. Wait for command to complete, then - return the returncode attribute. +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() + p = Popen(*popenargs, **kwargs) + try: + return p.wait(timeout=timeout) + except TimeoutExpired: + p.kill() + p.wait() + raise def check_call(*popenargs, **kwargs): @@ -466,7 +493,7 @@ 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"]) """ @@ -479,7 +506,7 @@ 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 @@ -502,13 +529,15 @@ 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() + try: + output, unused_err = process.communicate(timeout=timeout) + except TimeoutExpired: + process.kill() + output, unused_err = process.communicate() + raise TimeoutExpired(process.args, timeout, output=output) retcode = process.poll() if retcode: - cmd = kwargs.get("args") - if cmd is None: - cmd = popenargs[0] - raise CalledProcessError(retcode, cmd, output=output) + raise CalledProcessError(retcode, process.args, output=output) return output @@ -639,6 +668,8 @@ 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): @@ -673,6 +704,7 @@ class Popen(object): raise ValueError("creationflags is only supported on Windows " "platforms") + self.args = args self.stdin = None self.stdout = None self.stderr = None @@ -768,8 +800,12 @@ 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 @@ -778,9 +814,14 @@ class Popen(object): 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: @@ -798,15 +839,42 @@ class Popen(object): stderr = self.stderr.read() self.stderr.close() self.wait() - return (stdout, stderr) + else: + if timeout is not None: + endtime = time.time() + timeout + else: + endtime = None - return self._communicate(input) + try: + stdout, stderr = self._communicate(input, endtime, timeout) + finally: + self._communication_started = True + + 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.time() + + + def _check_timeout(self, endtime, orig_timeout): + """Convenience for checking if a timeout has expired.""" + if endtime is None: + return + if time.time() > endtime: + raise TimeoutExpired(self.args, orig_timeout) + + if mswindows: # # Windows methods @@ -828,6 +896,8 @@ class Popen(object): p2cread, _ = _subprocess.CreatePipe(None, 0) elif stdin == PIPE: p2cread, p2cwrite = _subprocess.CreatePipe(None, 0) + elif stdin == DEVNULL: + p2cread = msvcrt.get_osfhandle(self._get_devnull()) elif isinstance(stdin, int): p2cread = msvcrt.get_osfhandle(stdin) else: @@ -841,6 +911,8 @@ class Popen(object): _, c2pwrite = _subprocess.CreatePipe(None, 0) elif stdout == PIPE: c2pread, c2pwrite = _subprocess.CreatePipe(None, 0) + elif stdout == DEVNULL: + c2pwrite = msvcrt.get_osfhandle(self._get_devnull()) elif isinstance(stdout, int): c2pwrite = msvcrt.get_osfhandle(stdout) else: @@ -856,6 +928,8 @@ class Popen(object): errread, errwrite = _subprocess.CreatePipe(None, 0) 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: @@ -965,6 +1039,8 @@ 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 @@ -989,12 +1065,20 @@ 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 = _subprocess.INFINITE + else: + timeout_millis = int(timeout * 1000) if self.returncode is None: - _subprocess.WaitForSingleObject(self._handle, - _subprocess.INFINITE) + result = _subprocess.WaitForSingleObject(self._handle, + timeout_millis) + if result == _subprocess.WAIT_TIMEOUT: + raise TimeoutExpired(self.args, timeout) self.returncode = _subprocess.GetExitCodeProcess(self._handle) return self.returncode @@ -1004,22 +1088,23 @@ 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: @@ -1030,10 +1115,28 @@ 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.isAlive(): + raise TimeoutExpired(self.args, orig_timeout) + if self.stderr is not None: + self.stderr_thread.join(self._remaining_time(endtime)) + if self.stderr_thread.isAlive(): + 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: @@ -1041,7 +1144,6 @@ class Popen(object): if stderr is not None: stderr = stderr[0] - self.wait() return (stdout, stderr) def send_signal(self, sig): @@ -1079,6 +1181,8 @@ 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: @@ -1089,6 +1193,8 @@ 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: @@ -1101,6 +1207,8 @@ 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: @@ -1131,7 +1239,7 @@ 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) @@ -1294,6 +1402,8 @@ 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) @@ -1371,25 +1481,57 @@ 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.""" - if 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. - sts = 0 + 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.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) + elif self.returncode is None: + (pid, sts) = self._try_wait(0) 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() @@ -1397,9 +1539,13 @@ 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: @@ -1417,67 +1563,87 @@ class Popen(object): stderr = self._translate_newlines(stderr, self.stderr.encoding) - self.wait() return (stdout, stderr) - def _communicate_with_poll(self, input): + 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 = [] - - input_offset = 0 - while fd2file: + stderr = self._fd2output[self.stderr.fileno()] + + # Save the input here 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: + self._input = self._input.encode(self.stdin.encoding) + + 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) @@ -1485,61 +1651,87 @@ 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) + + if self.stdin and self._input is None: + self._input_offset = 0 + self._input = input + if self.universal_newlines: + self._input = self._input.encode(self.stdin.encoding) + 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) @@ -1559,68 +1751,3 @@ 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() |