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PROPLIB(3)              NetBSD Library Functions Manual             PROPLIB(3)


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.  There are two formats availavble for
     external representation:

     ·   An XML document whose format is described by the following DTD:

                     http://www.apple.com/DTDs/PropertyList-1.0.dtd

     ·   A JSON document whose format is described by RFC 8259.

     Property container objects are reference counted.  When an object is cre-
     ated, 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 auto-
     matically 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 main-
         tain a reference to it, you must retain the object.  You are respon-
         sible 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_array_util(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.  Support for the JSON serialization format was added in
     NetBSD 11.0.


CAVEATS

     proplib does not have a `date' object type, and thus will not parse
     `date' elements from an Apple XML property list.

     proplib does not have a `null' object type, and thus will not parse
     `null' elements from a JSON document.

     The proplib `number' object type differs from the Apple XML property list
     format in the following ways:

     ·   The external representation for unsigned numbers is in base 16, not
         base 10.  proplib is able to parse base 8, base 10, and base 16
         `integer' elements.  Signed numbers are represented in base 10.

     ·   proplib does not support floating point numbers, so `real' elements
         from an Apple XML property list will not be parsed.

     Similarly, proplib does not parse floating point numbers (as described in
     RFC 8259) in JSON documents.  For JSON documents, all numbers are repre-
     sented in base 10.

     JSON does not have an opaque data element that is functionally equivalent
     to the `data' elements in XML property lists.  As such, a property list
     containing `data' objects cannot be externalized into a JSON document.

     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.

NetBSD 10.99                    April 20, 2025                    NetBSD 10.99