The integral datatypes used in the system calls are
implemented as 32 bit values in this protocol.
unsigned long are implemented as 64 bit types.
See Limits, for corresponding MIN and MAX values (similar to those in limits.h) to allow range checking on host and target.
time_t datatypes are defined as seconds since the Epoch.
All integral datatypes transferred as part of a memory read or write of a
structured datatype e.g. a
struct stat have to be given in big endian