Fixes issue4653 - Correctly specify the buffer size to FormatMessageW and

correctly check for errors on two CreateFileMapping calls.

PC/bdist_wininst/extract.c

@@ -127,7 +127,7 @@ char *map_new_file(DWORD flags, char *filename,
 
     CloseHandle(hFile);
 
-    if (hFileMapping == INVALID_HANDLE_VALUE) {
+    if (hFileMapping == NULL) {
         if (notify)
             notify(SYSTEM_ERROR,
                    "CreateFileMapping (%s)", filename);

PC/bdist_wininst/install.c

@@ -1019,7 +1019,7 @@ static char *MapExistingFile(char *pathname, DWORD *psize)
                                       NULL, PAGE_READONLY, 0, 0, NULL);
     CloseHandle(hFile);
 
-    if (hFileMapping == INVALID_HANDLE_VALUE)
+    if (hFileMapping == NULL)
         return NULL;
 
     data = MapViewOfFile(hFileMapping,

Python/dynload_win.c

@@ -235,7 +235,7 @@ dl_funcptr _PyImport_GetDynLoadWindows(const char *shortname,
                            SUBLANG_DEFAULT),
                            /* Default language */
                 theInfo, /* the buffer */
-                sizeof(theInfo), /* the buffer size */
+                sizeof(theInfo) / sizeof(wchar_t), /* size in wchars */
                 NULL); /* no additional format args. */
 
             /* Problem: could not get the error message.