[Python-checkins] gh-101881: Support (non-)blocking read/write functions on Windows pipes (GH-101882)
zooba
webhook-mailer at python.org
Thu Feb 16 09:52:55 EST 2023
https://github.com/python/cpython/commit/739c026f4488bd2e37d500a2c3d948aaf929b641
commit: 739c026f4488bd2e37d500a2c3d948aaf929b641
branch: main
author: Rayyan Ansari <rayyan at ansari.sh>
committer: zooba <steve.dower at microsoft.com>
date: 2023-02-16T14:52:24Z
summary:
gh-101881: Support (non-)blocking read/write functions on Windows pipes (GH-101882)
* 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.
files:
A Misc/NEWS.d/next/Windows/2023-02-13-18-05-49.gh-issue-101881._TnHzN.rst
A Misc/NEWS.d/next/Windows/2023-02-15-11-08-10.gh-issue-101881.fScr3m.rst
M Doc/library/os.rst
M Include/internal/pycore_fileutils.h
M Lib/test/test_os.py
M Modules/clinic/posixmodule.c.h
M Modules/posixmodule.c
M Python/fileutils.c
diff --git a/Doc/library/os.rst b/Doc/library/os.rst
index fb091176767f..85924d0e4836 100644
--- a/Doc/library/os.rst
+++ b/Doc/library/os.rst
@@ -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
diff --git a/Include/internal/pycore_fileutils.h b/Include/internal/pycore_fileutils.h
index ac89c43d569c..f8e2bf225908 100644
--- a/Include/internal/pycore_fileutils.h
+++ b/Include/internal/pycore_fileutils.h
@@ -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);
diff --git a/Lib/test/test_os.py b/Lib/test/test_os.py
index 387d2581c06f..deea207bfdad 100644
--- a/Lib/test/test_os.py
+++ b/Lib/test/test_os.py
@@ -4099,6 +4099,7 @@ def test_path_t_converter_and_custom_class(self):
@unittest.skipUnless(hasattr(os, 'get_blocking'),
'needs os.get_blocking() and os.set_blocking()')
@unittest.skipIf(support.is_emscripten, "Cannot unset blocking flag")
+ at 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)
diff --git a/Misc/NEWS.d/next/Windows/2023-02-13-18-05-49.gh-issue-101881._TnHzN.rst b/Misc/NEWS.d/next/Windows/2023-02-13-18-05-49.gh-issue-101881._TnHzN.rst
new file mode 100644
index 000000000000..ba58dd4f5cb4
--- /dev/null
+++ b/Misc/NEWS.d/next/Windows/2023-02-13-18-05-49.gh-issue-101881._TnHzN.rst
@@ -0,0 +1 @@
+Add support for the os.get_blocking() and os.set_blocking() functions on Windows.
diff --git a/Misc/NEWS.d/next/Windows/2023-02-15-11-08-10.gh-issue-101881.fScr3m.rst b/Misc/NEWS.d/next/Windows/2023-02-15-11-08-10.gh-issue-101881.fScr3m.rst
new file mode 100644
index 000000000000..099b2c1c07a6
--- /dev/null
+++ b/Misc/NEWS.d/next/Windows/2023-02-15-11-08-10.gh-issue-101881.fScr3m.rst
@@ -0,0 +1 @@
+Handle read and write operations on non-blocking pipes properly on Windows.
diff --git a/Modules/clinic/posixmodule.c.h b/Modules/clinic/posixmodule.c.h
index 5e04507ddd69..dcd25c28370c 100644
--- a/Modules/clinic/posixmodule.c.h
+++ b/Modules/clinic/posixmodule.c.h
@@ -10402,8 +10402,6 @@ os_set_handle_inheritable(PyObject *module, PyObject *const *args, Py_ssize_t na
#endif /* defined(MS_WINDOWS) */
-#if !defined(MS_WINDOWS)
-
PyDoc_STRVAR(os_get_blocking__doc__,
"get_blocking($module, fd, /)\n"
"--\n"
@@ -10439,10 +10437,6 @@ os_get_blocking(PyObject *module, PyObject *arg)
return return_value;
}
-#endif /* !defined(MS_WINDOWS) */
-
-#if !defined(MS_WINDOWS)
-
PyDoc_STRVAR(os_set_blocking__doc__,
"set_blocking($module, fd, blocking, /)\n"
"--\n"
@@ -10482,8 +10476,6 @@ os_set_blocking(PyObject *module, PyObject *const *args, Py_ssize_t nargs)
return return_value;
}
-#endif /* !defined(MS_WINDOWS) */
-
PyDoc_STRVAR(os_DirEntry_is_symlink__doc__,
"is_symlink($self, /)\n"
"--\n"
@@ -11789,14 +11781,6 @@ os_waitstatus_to_exitcode(PyObject *module, PyObject *const *args, Py_ssize_t na
#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 @@ os_waitstatus_to_exitcode(PyObject *module, PyObject *const *args, Py_ssize_t na
#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]*/
diff --git a/Modules/posixmodule.c b/Modules/posixmodule.c
index d9e93473aead..524dc7eb1ccc 100644
--- a/Modules/posixmodule.c
+++ b/Modules/posixmodule.c
@@ -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]
diff --git a/Python/fileutils.c b/Python/fileutils.c
index 22b2257a56d0..897c2f9f4ea1 100644
--- a/Python/fileutils.c
+++ b/Python/fileutils.c
@@ -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 @@ _Py_set_blocking(int fd, int blocking)
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)
{
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