PROPLIB(3) BSD Library Functions Manual PROPLIB(3)
proplib -- property container object library
The proplib library provides an abstract interface for creating and manipulating property
lists. Property lists have object types for boolean values, opaque data, numbers, and
strings. Structure is provided by the array and dictionary collection types.
Property lists can be passed across protection boundaries by translating them to an external
representation. This external representation is an XML document whose format is described
by the following DTD:
Property container objects are reference counted. When an object is created, its reference
count is set to 1. Any code that keeps a reference to an object, including the collection
types (arrays and dictionaries), must ``retain'' the object (increment its reference count).
When that reference is dropped, the object must be ``released'' (reference count
decremented). When an object's reference count drops to 0, it is automatically freed.
The rules for managing reference counts are very simple:
o If you create an object and do not explicitly maintain a reference to it, you must
o If you get a reference to an object from other code and wish to maintain a reference to
it, you must retain the object. You are responsible for releasing the object once you
drop that reference.
o You must never release an object unless you create it or retain it.
Object collections may be iterated by creating a special iterator object. Iterator objects
are special; they may not be retained, and they are released using an iterator-specific
prop_array(3), prop_bool(3), prop_data(3), prop_dictionary(3), prop_dictionary_util(3),
prop_number(3), prop_object(3), prop_send_ioctl(3), prop_send_syscall(3), prop_string(3)
The proplib property container object library first appeared in NetBSD 4.0.
proplib does not have a 'date' object type, and thus will not parse 'date' elements from an
Apple XML property list.
The proplib 'number' object type differs from the Apple XML property list format in the fol-
o The external representation is in base 16, not base 10. proplib is able to parse base
8, base 10, and base 16 'integer' elements.
o Internally, integers are always stored as unsigned numbers (uint64_t). Therefore, the
external representation will never be negative.
o Because floating point numbers are not supported, 'real' elements from an Apple XML
property list will not be parsed.
In order to facilitate use of proplib in kernel, standalone, and user space environments,
the proplib parser is not a real XML parser. It is hard-coded to parse only the property
list external representation.
BSD January 17, 2011 BSD