sys/_types/_mach_port_t.h

mach_port_t - a named port right In user-space, "rights" are represented by the name of the right in the Mach port namespace. Even so, this type is presented as a unique one to more clearly denote the presence of a right coming along with the name. Often, various rights for a port held in a single name space will coalesce and are, therefore, be identified by a single name [this is the case for send and receive rights]. But not always [send-once rights currently get a unique name for each right]. This definition of mach_port_t is only for user-space.

#define _MACH_PORT_T 

typedef __darwin_mach_port_t mach_port_t