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gh-101881: Support (non-)blocking read/write functions on Windows pipes (GH-101882)

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* fileutils: handle non-blocking pipe IO on Windows

Handle erroring operations on non-blocking pipes by reading the _doserrno code.
Limit writes on non-blocking pipes that are too large.

* Support blocking functions on Windows

Use the GetNamedPipeHandleState and SetNamedPipeHandleState Win32 API functions to add support for os.get_blocking and os.set_blocking.
This commit is contained in:
Rayyan Ansari 2023-02-16 14:52:24 +00:00 • committed by GitHub
parent 36b139af63
commit 739c026f44
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GPG key ID: 4AEE18F83AFDEB23
8 changed files with 107 additions and 25 deletions
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12
Doc/library/os.rst
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@ -1091,13 +1091,17 @@ as internal buffering of data.
See also :func:`set_blocking` and :meth:`socket.socket.setblocking`.
.. availability:: Unix.
.. availability:: Unix, Windows.
The function is limited on Emscripten and WASI, see
:ref:`wasm-availability` for more information.
On Windows, this function is limited to pipes.
.. versionadded:: 3.5
.. versionchanged:: 3.12
Added support for pipes on Windows.
.. function:: isatty(fd, /)
@ -1565,13 +1569,17 @@ or `the MSDN <https://msdn.microsoft.com/en-us/library/z0kc8e3z.aspx>`_ on Windo
See also :func:`get_blocking` and :meth:`socket.socket.setblocking`.
.. availability:: Unix.
.. availability:: Unix, Windows.
The function is limited on Emscripten and WASI, see
:ref:`wasm-availability` for more information.
On Windows, this function is limited to pipes.
.. versionadded:: 3.5
.. versionchanged:: 3.12
Added support for pipes on Windows.
.. data:: SF_NODISKIO
SF_MNOWAIT

4
Include/internal/pycore_fileutils.h
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@ -160,11 +160,11 @@ PyAPI_FUNC(int) _Py_set_inheritable_async_safe(int fd, int inheritable,
PyAPI_FUNC(int) _Py_dup(int fd);
#ifndef MS_WINDOWS
PyAPI_FUNC(int) _Py_get_blocking(int fd);
PyAPI_FUNC(int) _Py_set_blocking(int fd, int blocking);
#else /* MS_WINDOWS */
#ifdef MS_WINDOWS
PyAPI_FUNC(void*) _Py_get_osfhandle_noraise(int fd);
PyAPI_FUNC(void*) _Py_get_osfhandle(int fd);

1
Lib/test/test_os.py
View file

@ -4099,6 +4099,7 @@ class PathTConverterTests(unittest.TestCase):
@unittest.skipUnless(hasattr(os, 'get_blocking'),
'needs os.get_blocking() and os.set_blocking()')
@unittest.skipIf(support.is_emscripten, "Cannot unset blocking flag")
@unittest.skipIf(sys.platform == 'win32', 'Windows only supports blocking on pipes')
class BlockingTests(unittest.TestCase):
def test_blocking(self):
fd = os.open(__file__, os.O_RDONLY)

1
Misc/NEWS.d/next/Windows/2023-02-13-18-05-49.gh-issue-101881._TnHzN.rst Normal file
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@ -0,0 +1 @@
Add support for the os.get_blocking() and os.set_blocking() functions on Windows.

1
Misc/NEWS.d/next/Windows/2023-02-15-11-08-10.gh-issue-101881.fScr3m.rst Normal file
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@ -0,0 +1 @@
Handle read and write operations on non-blocking pipes properly on Windows.

18
Modules/clinic/posixmodule.c.h generated
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@ -10402,8 +10402,6 @@ exit:
#endif /* defined(MS_WINDOWS) */
#if !defined(MS_WINDOWS)
PyDoc_STRVAR(os_get_blocking__doc__,
"get_blocking($module, fd, /)\n"
"--\n"
@ -10439,10 +10437,6 @@ exit:
return return_value;
}
#endif /* !defined(MS_WINDOWS) */
#if !defined(MS_WINDOWS)
PyDoc_STRVAR(os_set_blocking__doc__,
"set_blocking($module, fd, blocking, /)\n"
"--\n"
@ -10482,8 +10476,6 @@ exit:
return return_value;
}
#endif /* !defined(MS_WINDOWS) */
PyDoc_STRVAR(os_DirEntry_is_symlink__doc__,
"is_symlink($self, /)\n"
"--\n"
@ -11789,14 +11781,6 @@ exit:
#define OS_SET_HANDLE_INHERITABLE_METHODDEF
#endif /* !defined(OS_SET_HANDLE_INHERITABLE_METHODDEF) */
#ifndef OS_GET_BLOCKING_METHODDEF
#define OS_GET_BLOCKING_METHODDEF
#endif /* !defined(OS_GET_BLOCKING_METHODDEF) */
#ifndef OS_SET_BLOCKING_METHODDEF
#define OS_SET_BLOCKING_METHODDEF
#endif /* !defined(OS_SET_BLOCKING_METHODDEF) */
#ifndef OS_GETRANDOM_METHODDEF
#define OS_GETRANDOM_METHODDEF
#endif /* !defined(OS_GETRANDOM_METHODDEF) */
@ -11812,4 +11796,4 @@ exit:
#ifndef OS_WAITSTATUS_TO_EXITCODE_METHODDEF
#define OS_WAITSTATUS_TO_EXITCODE_METHODDEF
#endif /* !defined(OS_WAITSTATUS_TO_EXITCODE_METHODDEF) */
/*[clinic end generated code: output=a3f76228b549e8ec input=a9049054013a1b77]*/
/*[clinic end generated code: output=1b0eb6a76b1a0e28 input=a9049054013a1b77]*/

2
Modules/posixmodule.c
View file

@ -13930,7 +13930,6 @@ os_set_handle_inheritable_impl(PyObject *module, intptr_t handle,
}
#endif /* MS_WINDOWS */
#ifndef MS_WINDOWS
/*[clinic input]
os.get_blocking -> bool
fd: int
@ -13978,7 +13977,6 @@ os_set_blocking_impl(PyObject *module, int fd, int blocking)
return NULL;
Py_RETURN_NONE;
}
#endif /* !MS_WINDOWS */
/*[clinic input]

93
Python/fileutils.c
View file

@ -1750,7 +1750,15 @@ _Py_read(int fd, void *buf, size_t count)
Py_BEGIN_ALLOW_THREADS
errno = 0;
#ifdef MS_WINDOWS
_doserrno = 0;
n = read(fd, buf, (int)count);
// read() on a non-blocking empty pipe fails with EINVAL, which is
// mapped from the Windows error code ERROR_NO_DATA.
if (n < 0 && errno == EINVAL) {
if (_doserrno == ERROR_NO_DATA) {
errno = EAGAIN;
}
}
#else
n = read(fd, buf, count);
#endif
@ -1804,6 +1812,7 @@ _Py_write_impl(int fd, const void *buf, size_t count, int gil_held)
}
}
}
#endif
if (count > _PY_WRITE_MAX) {
count = _PY_WRITE_MAX;
@ -1814,7 +1823,18 @@ _Py_write_impl(int fd, const void *buf, size_t count, int gil_held)
Py_BEGIN_ALLOW_THREADS
errno = 0;
#ifdef MS_WINDOWS
n = write(fd, buf, (int)count);
// write() on a non-blocking pipe fails with ENOSPC on Windows if
// the pipe lacks available space for the entire buffer.
int c = (int)count;
do {
_doserrno = 0;
n = write(fd, buf, c);
if (n >= 0 || errno != ENOSPC || _doserrno != 0) {
break;
}
errno = EAGAIN;
c /= 2;
} while (c > 0);
#else
n = write(fd, buf, count);
#endif
@ -1829,7 +1849,18 @@ _Py_write_impl(int fd, const void *buf, size_t count, int gil_held)
do {
errno = 0;
#ifdef MS_WINDOWS
n = write(fd, buf, (int)count);
// write() on a non-blocking pipe fails with ENOSPC on Windows if
// the pipe lacks available space for the entire buffer.
int c = (int)count;
do {
_doserrno = 0;
n = write(fd, buf, c);
if (n >= 0 || errno != ENOSPC || _doserrno != 0) {
break;
}
errno = EAGAIN;
c /= 2;
} while (c > 0);
#else
n = write(fd, buf, count);
#endif
@ -2450,6 +2481,64 @@ error:
return -1;
}
#else /* MS_WINDOWS */
int
_Py_get_blocking(int fd)
{
HANDLE handle;
DWORD mode;
BOOL success;
handle = _Py_get_osfhandle(fd);
if (handle == INVALID_HANDLE_VALUE) {
return -1;
}
Py_BEGIN_ALLOW_THREADS
success = GetNamedPipeHandleStateW(handle, &mode,
NULL, NULL, NULL, NULL, 0);
Py_END_ALLOW_THREADS
if (!success) {
PyErr_SetFromWindowsErr(0);
return -1;
}
return !(mode & PIPE_NOWAIT);
}
int
_Py_set_blocking(int fd, int blocking)
{
HANDLE handle;
DWORD mode;
BOOL success;
handle = _Py_get_osfhandle(fd);
if (handle == INVALID_HANDLE_VALUE) {
return -1;
}
Py_BEGIN_ALLOW_THREADS
success = GetNamedPipeHandleStateW(handle, &mode,
NULL, NULL, NULL, NULL, 0);
if (success) {
if (blocking) {
mode &= ~PIPE_NOWAIT;
}
else {
mode |= PIPE_NOWAIT;
}
success = SetNamedPipeHandleState(handle, &mode, NULL, NULL);
}
Py_END_ALLOW_THREADS
if (!success) {
PyErr_SetFromWindowsErr(0);
return -1;
}
return 0;
}
void*
_Py_get_osfhandle_noraise(int fd)
{