Well, no actually: That still limits you to a gets of BUFSIZ. Just as we often grow the stack with page faults, you could grow the heap with page faults: Moder

Well, no actually: That still limits you to a gets of BUFSIZ. Just as we often grow the stack with page faults, you could grow the heap with page faults: Modern UNIX doesn't because this is another one of those "almost certainly a mistake", but: signal(SIGSEGV, grow); void grow(int _) { sbrk(PAGESZ); } should work.