The _posixsubprocess module is now required on POSIX.
Remove the pure Python POSIX subprocess implementation. If non-CPython VMs (are there any for 3.x yet?) were somehow depending on this, they already have the exact same set of problems with Python code being executed after os.fork() that _posixsubprocess was written to deal with. They should implement an equivalent outside of Python.
This commit is contained in:
Gregory P. Smith
parent
c80504fb69
commit
59fd1bfcc1
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@ -397,39 +397,14 @@ if mswindows:
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else:
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import select
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_has_poll = hasattr(select, 'poll')
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import fcntl
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import pickle
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try:
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import _posixsubprocess
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except ImportError:
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_posixsubprocess = None
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warnings.warn("The _posixsubprocess module is not being used. "
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"Child process reliability may suffer if your "
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"program uses threads.", RuntimeWarning)
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import _posixsubprocess
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_create_pipe = _posixsubprocess.cloexec_pipe
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# When select or poll has indicated that the file is writable,
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# we can write up to _PIPE_BUF bytes without risk of blocking.
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# POSIX defines PIPE_BUF as >= 512.
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_PIPE_BUF = getattr(select, 'PIPE_BUF', 512)
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_FD_CLOEXEC = getattr(fcntl, 'FD_CLOEXEC', 1)
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def _set_cloexec(fd, cloexec):
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old = fcntl.fcntl(fd, fcntl.F_GETFD)
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if cloexec:
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fcntl.fcntl(fd, fcntl.F_SETFD, old | _FD_CLOEXEC)
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else:
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fcntl.fcntl(fd, fcntl.F_SETFD, old & ~_FD_CLOEXEC)
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if _posixsubprocess:
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_create_pipe = _posixsubprocess.cloexec_pipe
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else:
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def _create_pipe():
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fds = os.pipe()
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_set_cloexec(fds[0], True)
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_set_cloexec(fds[1], True)
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return fds
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__all__ = ["Popen", "PIPE", "STDOUT", "call", "check_call", "getstatusoutput",
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"getoutput", "check_output", "CalledProcessError", "DEVNULL"]
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@ -1267,140 +1242,33 @@ class Popen(object):
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errpipe_read, errpipe_write = _create_pipe()
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try:
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try:
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# We must avoid complex work that could involve
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# malloc or free in the child process to avoid
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# potential deadlocks, thus we do all this here.
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# and pass it to fork_exec()
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if _posixsubprocess:
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# We must avoid complex work that could involve
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# malloc or free in the child process to avoid
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# potential deadlocks, thus we do all this here.
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# and pass it to fork_exec()
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if env:
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env_list = [os.fsencode(k) + b'=' + os.fsencode(v)
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for k, v in env.items()]
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else:
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env_list = None # Use execv instead of execve.
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executable = os.fsencode(executable)
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if os.path.dirname(executable):
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executable_list = (executable,)
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else:
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# This matches the behavior of os._execvpe().
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executable_list = tuple(
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os.path.join(os.fsencode(dir), executable)
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for dir in os.get_exec_path(env))
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fds_to_keep = set(pass_fds)
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fds_to_keep.add(errpipe_write)
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self.pid = _posixsubprocess.fork_exec(
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args, executable_list,
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close_fds, sorted(fds_to_keep), cwd, env_list,
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p2cread, p2cwrite, c2pread, c2pwrite,
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errread, errwrite,
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errpipe_read, errpipe_write,
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restore_signals, start_new_session, preexec_fn)
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if env:
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env_list = [os.fsencode(k) + b'=' + os.fsencode(v)
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for k, v in env.items()]
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else:
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# Pure Python implementation: It is not thread safe.
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# This implementation may deadlock in the child if your
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# parent process has any other threads running.
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gc_was_enabled = gc.isenabled()
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# Disable gc to avoid bug where gc -> file_dealloc ->
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# write to stderr -> hang. See issue1336
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gc.disable()
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try:
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self.pid = os.fork()
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except:
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if gc_was_enabled:
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gc.enable()
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raise
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self._child_created = True
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if self.pid == 0:
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# Child
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try:
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# Close parent's pipe ends
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if p2cwrite != -1:
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os.close(p2cwrite)
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if c2pread != -1:
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os.close(c2pread)
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if errread != -1:
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os.close(errread)
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os.close(errpipe_read)
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# Dup fds for child
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def _dup2(a, b):
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# dup2() removes the CLOEXEC flag but
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# we must do it ourselves if dup2()
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# would be a no-op (issue #10806).
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if a == b:
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_set_cloexec(a, False)
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elif a != -1:
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os.dup2(a, b)
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_dup2(p2cread, 0)
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_dup2(c2pwrite, 1)
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_dup2(errwrite, 2)
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# Close pipe fds. Make sure we don't close the
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# same fd more than once, or standard fds.
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closed = set()
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for fd in [p2cread, c2pwrite, errwrite]:
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if fd > 2 and fd not in closed:
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os.close(fd)
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closed.add(fd)
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# Close all other fds, if asked for
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if close_fds:
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fds_to_keep = set(pass_fds)
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fds_to_keep.add(errpipe_write)
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self._close_fds(fds_to_keep)
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if cwd is not None:
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os.chdir(cwd)
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# This is a copy of Python/pythonrun.c
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# _Py_RestoreSignals(). If that were exposed
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# as a sys._py_restoresignals func it would be
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# better.. but this pure python implementation
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# isn't likely to be used much anymore.
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if restore_signals:
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signals = ('SIGPIPE', 'SIGXFZ', 'SIGXFSZ')
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for sig in signals:
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if hasattr(signal, sig):
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signal.signal(getattr(signal, sig),
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signal.SIG_DFL)
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if start_new_session and hasattr(os, 'setsid'):
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os.setsid()
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if preexec_fn:
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preexec_fn()
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if env is None:
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os.execvp(executable, args)
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else:
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os.execvpe(executable, args, env)
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except:
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try:
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exc_type, exc_value = sys.exc_info()[:2]
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if isinstance(exc_value, OSError):
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errno_num = exc_value.errno
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else:
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errno_num = 0
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message = '%s:%x:%s' % (exc_type.__name__,
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errno_num, exc_value)
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message = message.encode(errors="surrogatepass")
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os.write(errpipe_write, message)
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except Exception:
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# We MUST not allow anything odd happening
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# above to prevent us from exiting below.
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pass
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# This exitcode won't be reported to applications
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# so it really doesn't matter what we return.
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os._exit(255)
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# Parent
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if gc_was_enabled:
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gc.enable()
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env_list = None # Use execv instead of execve.
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executable = os.fsencode(executable)
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if os.path.dirname(executable):
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executable_list = (executable,)
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else:
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# This matches the behavior of os._execvpe().
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executable_list = tuple(
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os.path.join(os.fsencode(dir), executable)
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for dir in os.get_exec_path(env))
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fds_to_keep = set(pass_fds)
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fds_to_keep.add(errpipe_write)
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self.pid = _posixsubprocess.fork_exec(
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args, executable_list,
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close_fds, sorted(fds_to_keep), cwd, env_list,
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p2cread, p2cwrite, c2pread, c2pwrite,
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errread, errwrite,
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errpipe_read, errpipe_write,
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restore_signals, start_new_session, preexec_fn)
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finally:
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# be sure the FD is closed no matter what
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os.close(errpipe_write)
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@ -1495,28 +1495,6 @@ class ProcessTestCaseNoPoll(ProcessTestCase):
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ProcessTestCase.tearDown(self)
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@unittest.skipUnless(getattr(subprocess, '_posixsubprocess', False),
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"_posixsubprocess extension module not found.")
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class ProcessTestCasePOSIXPurePython(ProcessTestCase, POSIXProcessTestCase):
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@classmethod
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def setUpClass(cls):
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global subprocess
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assert subprocess._posixsubprocess
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# Reimport subprocess while forcing _posixsubprocess to not exist.
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with support.check_warnings(('.*_posixsubprocess .* not being used.*',
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RuntimeWarning)):
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subprocess = support.import_fresh_module(
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'subprocess', blocked=['_posixsubprocess'])
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assert not subprocess._posixsubprocess
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@classmethod
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def tearDownClass(cls):
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global subprocess
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# Reimport subprocess as it should be, restoring order to the universe.
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subprocess = support.import_fresh_module('subprocess')
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assert subprocess._posixsubprocess
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class HelperFunctionTests(unittest.TestCase):
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@unittest.skipIf(mswindows, "errno and EINTR make no sense on windows")
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def test_eintr_retry_call(self):
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