diff options
| -rw-r--r-- | Doc/library/subprocess.rst | 23 | ||||
| -rw-r--r-- | Lib/subprocess.py | 23 | ||||
| -rw-r--r-- | Lib/test/test_subprocess.py | 25 | ||||
| -rw-r--r-- | Misc/NEWS | 2 |
4 files changed, 66 insertions, 7 deletions
diff --git a/Doc/library/subprocess.rst b/Doc/library/subprocess.rst index 4a12b76227..88eb7846a3 100644 --- a/Doc/library/subprocess.rst +++ b/Doc/library/subprocess.rst @@ -125,12 +125,14 @@ This module defines one class called :class:`Popen`: *stdin*, *stdout* and *stderr* specify the executed programs' standard input, standard output and standard error file handles, respectively. Valid values - are :data:`PIPE`, an existing file descriptor (a positive integer), an - existing :term:`file object`, and ``None``. :data:`PIPE` indicates that a - new pipe to the child should be created. With ``None``, no redirection will - occur; the child's file handles will be inherited from the parent. Additionally, - *stderr* can be :data:`STDOUT`, which indicates that the stderr data from the - applications should be captured into the same file handle as for stdout. + are :data:`PIPE`, :data:`DEVNULL`, an existing file descriptor (a positive + integer), an existing :term:`file object`, and ``None``. :data:`PIPE` + indicates that a new pipe to the child should be created. :data:`DEVNULL` + indicates that the special file :data:`os.devnull` will be used. With ``None``, + no redirection will occur; the child's file handles will be inherited from + the parent. Additionally, *stderr* can be :data:`STDOUT`, which indicates + that the stderr data from the applications should be captured into the same + file handle as for stdout. If *preexec_fn* is set to a callable object, this object will be called in the child process just before the child is executed. @@ -229,6 +231,15 @@ This module defines one class called :class:`Popen`: Added context manager support. +.. data:: DEVNULL + + Special value that can be used as the *stdin*, *stdout* or *stderr* argument + to :class:`Popen` and indicates that the special file :data:`os.devnull` + will be used. + + .. versionadded:: 3.3 + + .. data:: PIPE Special value that can be used as the *stdin*, *stdout* or *stderr* argument diff --git a/Lib/subprocess.py b/Lib/subprocess.py index cc0894544d..0e15f10c66 100644 --- a/Lib/subprocess.py +++ b/Lib/subprocess.py @@ -431,7 +431,7 @@ 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 @@ -456,6 +456,7 @@ def _cleanup(): PIPE = -1 STDOUT = -2 +DEVNULL = -3 def _eintr_retry_call(func, *args): @@ -800,6 +801,10 @@ 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, timeout=None): """Interact with process: Send data to stdin. Read data from @@ -889,6 +894,8 @@ 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: @@ -902,6 +909,8 @@ 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: @@ -917,6 +926,8 @@ 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: @@ -1026,6 +1037,8 @@ 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 @@ -1159,6 +1172,8 @@ 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: @@ -1169,6 +1184,8 @@ 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: @@ -1181,6 +1198,8 @@ 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: @@ -1374,6 +1393,8 @@ 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) diff --git a/Lib/test/test_subprocess.py b/Lib/test/test_subprocess.py index 5f158b9b64..31565432b0 100644 --- a/Lib/test/test_subprocess.py +++ b/Lib/test/test_subprocess.py @@ -323,6 +323,31 @@ class ProcessTestCase(BaseTestCase): rc = subprocess.call([sys.executable, "-c", cmd], stdout=1) self.assertEqual(rc, 2) + def test_stdout_devnull(self): + p = subprocess.Popen([sys.executable, "-c", + 'for i in range(10240):' + 'print("x" * 1024)'], + stdout=subprocess.DEVNULL) + p.wait() + self.assertEqual(p.stdout, None) + + def test_stderr_devnull(self): + p = subprocess.Popen([sys.executable, "-c", + 'import sys\n' + 'for i in range(10240):' + 'sys.stderr.write("x" * 1024)'], + stderr=subprocess.DEVNULL) + p.wait() + self.assertEqual(p.stderr, None) + + def test_stdin_devnull(self): + p = subprocess.Popen([sys.executable, "-c", + 'import sys;' + 'sys.stdin.read(1)'], + stdin=subprocess.DEVNULL) + p.wait() + self.assertEqual(p.stdin, None) + def test_cwd(self): tmpdir = tempfile.gettempdir() # We cannot use os.path.realpath to canonicalize the path, @@ -72,6 +72,8 @@ Core and Builtins Library ------- +- Issue #5870: Add `subprocess.DEVNULL` constant. + - Issue #11133: fix two cases where inspect.getattr_static can trigger code execution. Patch by Andreas Stührk. |