NAME
proplib —
property container object
library
LIBRARY
Property Container Object Library (libprop, -lprop)
SYNOPSIS
#include <prop/proplib.h>
DESCRIPTION
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:
- If you create an object and do not explicitly maintain a
reference to it, you must release it.
- 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.
- 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 release function.
SEE ALSO
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)
HISTORY
The
proplib property container object library first appeared
in
NetBSD 4.0.
CAVEATS
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 following ways:
- The external representation is in base 16, not base 10.
proplib is able to parse base 8, base 10, and base 16
‘integer’ elements.
- Internally, integers are always stored as unsigned
numbers (uint64_t). Therefore, the external representation will never be
negative.
- 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.