os: support blocking functions on Windows

RayyanAnsari · RayyanAnsari · commit f853e8341e98 · 2023-02-14T22:39:43.000Z
Use the GetNamedPipeHandleState and SetNamedPipeHandleState Win32 API functions to add support for os.get_blocking and os.set_blocking.
diff --git a/Include/internal/pycore_fileutils.h b/Include/internal/pycore_fileutils.h
@@ -160,11 +160,10 @@ 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
@@ -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")
+@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
@@ -0,0 +1 @@
+Add support for the os.get_blocking() and os.set_blocking() functions on Windows.
diff --git a/Modules/clinic/posixmodule.c.h b/Modules/clinic/posixmodule.c.h
diff --git 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
@@ -2470,6 +2470,47 @@ _Py_set_blocking(int fd, int blocking)
     return -1;
 }
 #else   /* MS_WINDOWS */
+int
+_Py_get_blocking(int fd)
+{
+    HANDLE handle;
+    DWORD mode;
+
+    handle = _Py_get_osfhandle(fd);
+    if (handle == INVALID_HANDLE_VALUE) {
+        return -1;
+    }
+
+    if (!GetNamedPipeHandleStateW(handle, &mode, NULL, NULL, NULL, NULL, 0)) {
+        PyErr_SetFromWindowsErr(0);
+        return -1;
+    }
+    return mode & PIPE_WAIT;
+}
+
+int
+_Py_set_blocking(int fd, int blocking)
+{
+    HANDLE handle;
+    DWORD mode;
+
+    handle = _Py_get_osfhandle(fd);
+    if (handle == INVALID_HANDLE_VALUE) {
+        return -1;
+    }
+
+    if (!GetNamedPipeHandleStateW(handle, &mode, NULL, NULL, NULL, NULL, 0)) {
+        PyErr_SetFromWindowsErr(0);
+        return -1;
+    }
+    mode |= blocking ? PIPE_WAIT : PIPE_NOWAIT;
+    if (!SetNamedPipeHandleState(handle, &mode, NULL, NULL)) {
+        PyErr_SetFromWindowsErr(0);
+        return -1;
+    }
+    return 0;
+}
+
 void*
 _Py_get_osfhandle_noraise(int fd)
 {

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1 @@`
	`1`	`+Add support for the os.get_blocking() and os.set_blocking() functions on Windows.`
Original file line number	Diff line number	Diff line change
`@@ -13930,7 +13930,6 @@ os_set_handle_inheritable_impl(PyObject *module, intptr_t handle,`
`13930`	`13930`	`}`
`13931`	`13931`	`#endif /* MS_WINDOWS */`
`13932`	`13932`
`13933`		`-#ifndef MS_WINDOWS`
`13934`	`13933`	`/*[clinic input]`
`13935`	`13934`	`os.get_blocking -> bool`
`13936`	`13935`	`fd: int`
`@@ -13978,7 +13977,6 @@ os_set_blocking_impl(PyObject *module, int fd, int blocking)`
`13978`	`13977`	`return NULL;`
`13979`	`13978`	`Py_RETURN_NONE;`
`13980`	`13979`	`}`
`13981`		`-#endif /* !MS_WINDOWS */`
`13982`	`13980`
`13983`	`13981`
`13984`	`13982`	`/*[clinic input]`