How to (pointer).read_string given the offset in an ffi struct?

[cootcraig]

Suppose I have an ffi struct like this:

class RAW_BUF < FFI::Struct
  layout :data, [:uchar, 576]
end

How would I construct a pointer to offset 124 (for example)
in the struct?

I was hoping to use pointer.read_string where the pointer
is constructed as above.

[cootcraig]

I figured out a solution. See this function

  def pointer_from_struct_offset(ffi_struct,offset)
    FFI::Pointer.new(ffi_struct.to_ptr.address + offset)
  end