mac_prepare,
    mac_prepare_type,
    mac_prepare_file_label,
    mac_prepare_ifnet_label,
    mac_prepare_process_label —
    allocate appropriate storage for
    mac_t
#include
    <sys/mac.h>
int
  
  mac_prepare(mac_t
    *mac, const char
    *elements);
int
  
  mac_prepare_type(mac_t
    *mac, const char
    *name);
int
  
  mac_prepare_file_label(mac_t
    *mac);
int
  
  mac_prepare_ifnet_label(mac_t
    *mac);
int
  
  mac_prepare_process_label(mac_t
    *mac);
The mac_prepare family of functions
    allocates the appropriate amount of storage and initializes
    *mac for use by
    mac_get(3).
    When the resulting label is passed into the
    mac_get(3)
    functions, the kernel will attempt to fill in the label elements specified
    when the label was prepared. Elements are specified in a nul-terminated
    string, using commas to delimit fields. Element names may be prefixed with
    the ‘?’ character to indicate that a
    failure by the kernel to retrieve that element should not be considered
    fatal.
The
    mac_prepare()
    function accepts a list of policy names as a parameter, and allocates the
    storage to fit those label elements accordingly. The remaining functions in
    the family make use of system defaults defined in
    mac.conf(5)
    instead of an explicit elements argument, deriving the
    default from the specified object type.
mac_prepare_type()
    allocates the storage to fit an object label of the type specified by the
    name argument. The
    mac_prepare_file_label(),
    mac_prepare_ifnet_label(),
    and
    mac_prepare_process_label()
    functions are equivalent to invocations of
    mac_prepare_type() with arguments of
    "file", "ifnet", and "process"
  respectively.
Upon successful completion, the value 0 is returned;
    otherwise the value -1 is returned and the global variable
    errno is set to indicate the error.
POSIX.1e is described in IEEE POSIX.1e draft 17.
Support for Mandatory Access Control was introduced in
    FreeBSD 5.0 as part of the TrustedBSD Project.
    Support for generic object types first appeared in FreeBSD
    5.2.