alloca() function allocates
size bytes of space in the stack frame of the caller.
This temporary space is automatically freed on return.
alloca() function returns a pointer to the beginning
of the allocated space.
alloca() function is unsafe because it cannot ensure
that the pointer returned points to a valid and usable block of memory. The
allocation made may exceed the bounds of the stack, or even go further into
other objects in memory, and
alloca() cannot determine
such an error. Avoid
alloca() with large unbounded