The mac_get_file system call returns the label associated with a file specified by pathname. The mac_get_link function is the same as mac_get_file, except that it does not follow symlinks.
The mac_get_fd system call returns the label associated with an object referenced by the specified file descriptor. Note that in the case of a file system socket, the label returned will be the socket label, which may be different from the label of the on-disk node acting as a rendezvous for the socket. The mac_get_peer system call returns the label associated with the remote endpoint of a socket; the exact semantics of this call will depend on the protocol domain, communications type, and endpoint; typically this label will be cached when a connection-oriented protocol instance is first set up, and is undefined for datagram protocols.
The mac_get_pid and mac_get_proc system calls return the process label associated with an arbitrary process ID, or the current process.
Label storage for use with these calls must first be allocated and prepared using the mac_prepare(3) functions. When an application is done using a label, the memory may be returned using mac_free(3).