forked from Imagelibrary/rtems
<ian@airs.com> to fix this problem: There is a small bug in __rtems_close in c/src/lib/libc/libio.c. It does not check whether the file descriptor it is passed is open. This can cause it to make a null dereference if it is passed a file descriptor which is in the valid range but which was not opened, or which was already closed.