Preview: windows_utils.py
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/lib64/python3.9/asyncio/windows_utils.py
"""Various Windows specific bits and pieces."""
import sys
if sys.platform != 'win32': # pragma: no cover
raise ImportError('win32 only')
import _winapi
import itertools
import msvcrt
import os
import subprocess
import tempfile
import warnings
__all__ = 'pipe', 'Popen', 'PIPE', 'PipeHandle'
# Constants/globals
BUFSIZE = 8192
PIPE = subprocess.PIPE
STDOUT = subprocess.STDOUT
_mmap_counter = itertools.count()
# Replacement for os.pipe() using handles instead of fds
def pipe(*, duplex=False, overlapped=(True, True), bufsize=BUFSIZE):
"""Like os.pipe() but with overlapped support and using handles not fds."""
address = tempfile.mktemp(
prefix=r'\\.\pipe\python-pipe-{:d}-{:d}-'.format(
os.getpid(), next(_mmap_counter)))
if duplex:
openmode = _winapi.PIPE_ACCESS_DUPLEX
access = _winapi.GENERIC_READ | _winapi.GENERIC_WRITE
obsize, ibsize = bufsize, bufsize
else:
openmode = _winapi.PIPE_ACCESS_INBOUND
access = _winapi.GENERIC_WRITE
obsize, ibsize = 0, bufsize
openmode |= _winapi.FILE_FLAG_FIRST_PIPE_INSTANCE
if overlapped[0]:
openmode |= _winapi.FILE_FLAG_OVERLAPPED
if overlapped[1]:
flags_and_attribs = _winapi.FILE_FLAG_OVERLAPPED
else:
flags_and_attribs = 0
h1 = h2 = None
try:
h1 = _winapi.CreateNamedPipe(
address, openmode, _winapi.PIPE_WAIT,
1, obsize, ibsize, _winapi.NMPWAIT_WAIT_FOREVER, _winapi.NULL)
h2 = _winapi.CreateFile(
address, access, 0, _winapi.NULL, _winapi.OPEN_EXISTING,
flags_and_attribs, _winapi.NULL)
ov = _winapi.ConnectNamedPipe(h1, overlapped=True)
ov.GetOverlappedResult(True)
return h1, h2
except:
if h1 is not None:
_winapi.CloseHandle(h1)
if h2 is not None:
_winapi.CloseHandle(h2)
raise
# Wrapper for a pipe handle
class PipeHandle:
"""Wrapper for an overlapped pipe handle which is vaguely file-object like.
The IOCP event loop can use these instead of socket objects.
"""
def __init__(self, handle):
self._handle = handle
def __repr__(self):
if self._handle is not None:
handle = f'handle={self._handle!r}'
else:
handle = 'closed'
return f'<{self.__class__.__name__} {handle}>'
@property
def handle(self):
return self._handle
def fileno(self):
if self._handle is None:
raise ValueError("I/O operation on closed pipe")
return self._handle
def close(self, *, CloseHandle=_winapi.CloseHandle):
if self._handle is not None:
CloseHandle(self._handle)
self._handle = None
def __del__(self, _warn=warnings.warn):
if self._handle is not None:
_warn(f"unclosed {self!r}", ResourceWarning, source=self)
self.close()
def __enter__(self):
return self
def __exit__(self, t, v, tb):
self.close()
# Replacement for subprocess.Popen using overlapped pipe handles
class Popen(subprocess.Popen):
"""Replacement for subprocess.Popen using overlapped pipe handles.
The stdin, stdout, stderr are None or instances of PipeHandle.
"""
def __init__(self, args, stdin=None, stdout=None, stderr=None, **kwds):
assert not kwds.get('universal_newlines')
assert kwds.get('bufsize', 0) == 0
stdin_rfd = stdout_wfd = stderr_wfd = None
stdin_wh = stdout_rh = stderr_rh = None
if stdin == PIPE:
stdin_rh, stdin_wh = pipe(overlapped=(False, True), duplex=True)
stdin_rfd = msvcrt.open_osfhandle(stdin_rh, os.O_RDONLY)
else:
stdin_rfd = stdin
if stdout == PIPE:
stdout_rh, stdout_wh = pipe(overlapped=(True, False))
stdout_wfd = msvcrt.open_osfhandle(stdout_wh, 0)
else:
stdout_wfd = stdout
if stderr == PIPE:
stderr_rh, stderr_wh = pipe(overlapped=(True, False))
stderr_wfd = msvcrt.open_osfhandle(stderr_wh, 0)
elif stderr == STDOUT:
stderr_wfd = stdout_wfd
else:
stderr_wfd = stderr
try:
super().__init__(args, stdin=stdin_rfd, stdout=stdout_wfd,
stderr=stderr_wfd, **kwds)
except:
for h in (stdin_wh, stdout_rh, stderr_rh):
if h is not None:
_winapi.CloseHandle(h)
raise
else:
if stdin_wh is not None:
self.stdin = PipeHandle(stdin_wh)
if stdout_rh is not None:
self.stdout = PipeHandle(stdout_rh)
if stderr_rh is not None:
self.stderr = PipeHandle(stderr_rh)
finally:
if stdin == PIPE:
os.close(stdin_rfd)
if stdout == PIPE:
os.close(stdout_wfd)
if stderr == PIPE:
os.close(stderr_wfd)
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