http://bugs.python.org/issue5623

Dynamically discoverd the size of the ioinfo struct used by the crt for its file descriptors.  This should work across all flavors of the CRT.  Thanks to Amaury Forgeot d'Arc
Needs porting to 3.1

Modules/posixmodule.c

@@ -269,6 +269,7 @@ extern int lstat(const char *, struct stat *);
 #include <process.h>
 #endif
 #include "osdefs.h"
+#include <malloc.h>
 #include <windows.h>
 #include <shellapi.h>	/* for ShellExecute() */
 #define popen	_popen
@@ -364,41 +365,15 @@ extern int lstat(const char *, struct stat *);
  * (all of this is to avoid globally modifying the CRT behaviour using
  * _set_invalid_parameter_handler() and _CrtSetReportMode())
  */
-#if _MSC_VER >= 1500 /* VS 2008 */
-typedef struct {
-        intptr_t osfhnd;
-        char osfile;
-        char pipech;
-        int lockinitflag;
-        CRITICAL_SECTION lock;
-#ifndef _SAFECRT_IMPL
-        char textmode : 7;
-        char unicode : 1;
-        char pipech2[2];
-        __int64 startpos;
-        BOOL utf8translations;
-        char dbcsBuffer;
-        BOOL dbcsBufferUsed;
-#endif  /* _SAFECRT_IMPL */
-    }   ioinfo;
-#elif _MSC_VER >= 1400  /* VS 2005 */
+/* The actual size of the structure is determined at runtime.
+ * Only the first items must be present.
+ */
 typedef struct {
         intptr_t osfhnd;
         char osfile;
-        char pipech;
-        int lockinitflag;
-        CRITICAL_SECTION lock;
-#ifndef _SAFECRT_IMPL
-        char textmode : 7;
-        char unicode : 1;
-        char pipech2[2];
-        __int64 startpos;
-        BOOL utf8translations;
-#endif  /* _SAFECRT_IMPL */
-    }   ioinfo;
-#endif
-
-extern __declspec(dllimport) ioinfo * __pioinfo[];
+} my_ioinfo;
+
+extern __declspec(dllimport) char * __pioinfo[];
 #define IOINFO_L2E 5
 #define IOINFO_ARRAY_ELTS   (1 << IOINFO_L2E)
 #define IOINFO_ARRAYS 64
@@ -412,6 +387,19 @@ _PyVerify_fd(int fd)
 {
 	const int i1 = fd >> IOINFO_L2E;
 	const int i2 = fd & ((1 << IOINFO_L2E) - 1);
+    
+	static int sizeof_ioinfo = 0;
+
+	/* Determine the actual size of the ioinfo structure, 
+	 * as used by the CRT loaded in memory
+	 */
+	if (sizeof_ioinfo == 0 && __pioinfo[0] != NULL) {
+		sizeof_ioinfo = _msize(__pioinfo[0]) / IOINFO_ARRAY_ELTS;
+	}
+	if (sizeof_ioinfo == 0) {
+		/* This should not happen... */
+		goto fail;
+	}
 
 	/* See that it isn't a special CLEAR fileno */
 	if (fd != _NO_CONSOLE_FILENO) {
@@ -420,10 +408,13 @@ _PyVerify_fd(int fd)
 		 */
 		if (0 <= i1 && i1 < IOINFO_ARRAYS && __pioinfo[i1] != NULL) {
 			/* finally, check that the file is open */
-			if (__pioinfo[i1][i2].osfile & FOPEN)
+			my_ioinfo* info = (my_ioinfo*)(__pioinfo[i1] + i2 * sizeof_ioinfo);
+			if (info->osfile & FOPEN) {
 				return 1;
+			}
 		}
 	}
+  fail:
 	errno = EBADF;
 	return 0;
 }