bpo-30555: Fix WindowsConsoleIO fails in the presence of fd redirection (GH-1927)

This works by not caching the handle and instead getting the handle from
the file descriptor each time, so that if the actual handle changes by
fd redirection closing/opening the console handle beneath our feet, we
will keep working correctly.

2 files changed, 8 insertions, 21 deletions

diff --git a/PC/_testconsole.c b/PC/_testconsole.c
index b62f21c..db84f73 100644
--- a/PC/_testconsole.c
+++ b/PC/_testconsole.c
@@ -13,10 +13,10 @@
 #include <fcntl.h>
 
  /* The full definition is in iomodule. We reproduce
- enough here to get the handle, which is all we want. */
+ enough here to get the fd, which is all we want. */
 typedef struct {
     PyObject_HEAD
-    HANDLE handle;
+    int fd;
 } winconsoleio;
 
 
@@ -67,7 +67,10 @@ _testconsole_write_input_impl(PyObject *module, PyObject *file,
         prec->Event.KeyEvent.uChar.UnicodeChar = *p;
     }
 
-    HANDLE hInput = ((winconsoleio*)file)->handle;
+    HANDLE hInput = _Py_get_osfhandle(((winconsoleio*)file)->fd);
+    if (hInput == INVALID_HANDLE_VALUE)
+        goto error;
+
     DWORD total = 0;
     while (total < size) {
         DWORD wrote;
diff --git a/PC/msvcrtmodule.c b/PC/msvcrtmodule.c
index b7ff20a..0591497 100644
--- a/PC/msvcrtmodule.c
+++ b/PC/msvcrtmodule.c
@@ -177,19 +177,11 @@ static long
 msvcrt_open_osfhandle_impl(PyObject *module, void *handle, int flags)
 /*[clinic end generated code: output=b2fb97c4b515e4e6 input=d5db190a307cf4bb]*/
 {
-    int fd;
-
     if (PySys_Audit("msvcrt.open_osfhandle", "Ki", handle, flags) < 0) {
         return -1;
     }
 
-    _Py_BEGIN_SUPPRESS_IPH
-    fd = _open_osfhandle((intptr_t)handle, flags);
-    _Py_END_SUPPRESS_IPH
-    if (fd == -1)
-        PyErr_SetFromErrno(PyExc_OSError);
-
-    return fd;
+    return _Py_open_osfhandle(handle, flags);
 }
 
 /*[clinic input]
@@ -207,19 +199,11 @@ static void *
 msvcrt_get_osfhandle_impl(PyObject *module, int fd)
 /*[clinic end generated code: output=aca01dfe24637374 input=5fcfde9b17136aa2]*/
 {
-    intptr_t handle = -1;
-
     if (PySys_Audit("msvcrt.get_osfhandle", "(i)", fd) < 0) {
         return NULL;
     }
 
-    _Py_BEGIN_SUPPRESS_IPH
-    handle = _get_osfhandle(fd);
-    _Py_END_SUPPRESS_IPH
-    if (handle == -1)
-        PyErr_SetFromErrno(PyExc_OSError);
-
-    return (HANDLE)handle;
+    return _Py_get_osfhandle(fd);
 }
 
 /* Console I/O */