Demo: Copy a File Using a Local Buffer

The second of four variants of the file-copy program. This one declares the buffer as a local variable of main(), so it lives on the stack: it appears when main() is entered, disappears when main() returns, and in between nothing allocates or releases it.

Together with the teaching assistant you will fill in the TODOs in copy_file.c, build it and copy a file. Then look at what size says about this binary compared to the global-buffer one, check ulimit -s, and try a bigger BUFFER_SIZE: the stack is the one place among the four where the buffer can simply be too large.