1.\" $NetBSD: proplib.3,v 1.9 2020/06/06 21:25:59 thorpej Exp $ 2.\" 3.\" Copyright (c) 2006 The NetBSD Foundation, Inc. 4.\" All rights reserved. 5.\" 6.\" This code is derived from software contributed to The NetBSD Foundation 7.\" by Jason R. Thorpe. 8.\" 9.\" Redistribution and use in source and binary forms, with or without 10.\" modification, are permitted provided that the following conditions 11.\" are met: 12.\" 1. Redistributions of source code must retain the above copyright 13.\" notice, this list of conditions and the following disclaimer. 14.\" 2. Redistributions in binary form must reproduce the above copyright 15.\" notice, this list of conditions and the following disclaimer in the 16.\" documentation and/or other materials provided with the distribution. 17.\" 18.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 19.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 20.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 21.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 22.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 23.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 24.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 25.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 26.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 27.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 28.\" POSSIBILITY OF SUCH DAMAGE. 29.\" 30.Dd June 2, 2020 31.Dt PROPLIB 3 32.Os 33.Sh NAME 34.Nm proplib 35.Nd property container object library 36.Sh LIBRARY 37.Lb libprop 38.Sh SYNOPSIS 39.In prop/proplib.h 40.Sh DESCRIPTION 41The 42.Nm 43library provides an abstract interface for creating and manipulating 44property lists. 45Property lists have object types for boolean values, opaque data, numbers, 46and strings. 47Structure is provided by the array and dictionary collection types. 48.Pp 49Property lists can be passed across protection boundaries by translating 50them to an external representation. 51This external representation is an XML document whose format is described 52by the following DTD: 53.Bd -literal -offset indent 54.Lk http://www.apple.com/DTDs/PropertyList-1.0.dtd 55.Ed 56.Pp 57Property container objects are reference counted. 58When an object is created, its reference count is set to 1. 59Any code that keeps a reference to an object, including the collection 60types 61.Pq arrays and dictionaries , 62must 63.Dq retain 64the object 65.Pq increment its reference count . 66When that reference is dropped, the object must be 67.Dq released 68.Pq reference count decremented . 69When an object's reference count drops to 0, it is automatically freed. 70.Pp 71The rules for managing reference counts are very simple: 72.Bl -bullet 73.It 74If you create an object and do not explicitly maintain a reference to it, 75you must release it. 76.It 77If you get a reference to an object from other code and wish to maintain 78a reference to it, you must retain the object. 79You are responsible for 80releasing the object once you drop that reference. 81.It 82You must never release an object unless you create it or retain it. 83.El 84.Pp 85Object collections may be iterated by creating a special iterator object. 86Iterator objects are special; they may not be retained, and they are 87released using an iterator-specific release function. 88.Sh SEE ALSO 89.Xr prop_array 3 , 90.Xr prop_array_util 3 , 91.Xr prop_bool 3 , 92.Xr prop_data 3 , 93.Xr prop_dictionary 3 , 94.Xr prop_dictionary_util 3 , 95.Xr prop_number 3 , 96.Xr prop_object 3 , 97.Xr prop_send_ioctl 3 , 98.Xr prop_send_syscall 3 , 99.Xr prop_string 3 100.Sh HISTORY 101The 102.Nm 103property container object library first appeared in 104.Nx 4.0 . 105.Sh CAVEATS 106.Nm 107does not have a 108.Sq date 109object type, and thus will not parse 110.Sq date 111elements from an Apple XML property list. 112.Pp 113The 114.Nm 115.Sq number 116object type differs from the Apple XML property list format in the following 117ways: 118.Bl -bullet 119.It 120The external representation is in base 16, not base 10. 121.Nm 122is able to parse base 8, base 10, and base 16 123.Sq integer 124elements. 125.It 126Internally, integers are always stored as unsigned numbers 127.Pq uintmax_t . 128Therefore, the external representation will never be negative. 129.It 130Because floating point numbers are not supported, 131.Sq real 132elements from an Apple XML property list will not be parsed. 133.El 134.Pp 135In order to facilitate use of 136.Nm 137in kernel, standalone, and user space environments, the 138.Nm 139parser is not a real XML parser. 140It is hard-coded to parse only the property list external representation. 141