o To support new EA interface with explicit namespaces, introduce two
utility functions which convert between string namespace names and
numeric constants used by the interface. Right now, two namespaces
are supported, EXTATTR_NAMESPACE_SYSTEM ("system") and
EXTATTR_NAMESPACE_USER ("user"). These functions are used by
various userland EA utilities, rather than hard coding the routines
all over the place.Obtained from: TrustedBSD Project