Is there anything I can read to learn more about overlaying in C? I was reading, to my limited abilities' limits, 2.11 BSD source and there was a lot of references to overlaying.
On a modern POSIX environment, you can hack together an approximation of an overlay by loading some code to an area of memory, mprotect( ptr, len, PROT_EXEC) the segment, ((int(*)())ptr)() to call the function and if you did everything right, you don't segfault too hard. Later, you can overwrite that area of memory with other code and repeat.
That is a different sort of overlay, a code overlay.
The other example was data, with the compiler assisting by changing local variables to have fixed addresses that get carefully reused for different variables at different times.
