/*
* The map entries can *almost* be read with programs like cat. However,
* large maps need special programs to read. It is not easy to implement
* a program that can sense the required size of the buffer, and then
* subsequently do a read with the appropriate size. This operation cannot
* be atomic. The best that we can do is to allow the program to do a read
* with an arbitrarily large buffer, and return as much as we can. We can
* return an error code if the buffer is too small (EFBIG), then the program
* can try a bigger buffer.
*/