Index: posixmodule.c
===================================================================
RCS file: /cvsroot/python/python/dist/src/Modules/posixmodule.c,v
retrieving revision 2.270
diff -c -r2.270 posixmodule.c
*** posixmodule.c	2 Nov 2002 17:42:33 -0000	2.270
--- posixmodule.c	5 Nov 2002 20:34:54 -0000
***************
*** 5048,5053 ****
--- 5048,5060 ----
  	if (!PyArg_ParseTuple(args, "i|si", &fd, &mode, &bufsize))
  		return NULL;
  
+ #ifdef MS_WIN32
+ 	/* MSVC fdopen() crashes with invalid mode, SF #623464 */
+ 	if (mode[0] != 'r' && mode[0] != 'w' && mode[0] != 'a') {
+ 		PyErr_Format(PyExc_ValueError, "invalid file mode '%s'", mode);
+ 		return NULL;
+ 	}
+ #endif
  	Py_BEGIN_ALLOW_THREADS
  	fp = fdopen(fd, mode);
  	Py_END_ALLOW_THREADS