NetBSD/common/lib/libprop/prop_data.3
thorpej a792b8435e Improvements to the problib(3) API:
==> Provide a much more complete set of setters and getters for different
    value types in the prop_array_util(3) and prop_dictionary_util(3)
    functions.

==> Overhaul the prop_data(3), prop_number(3), and prop_string(3) APIs
    to be easier to use and less awkwardly named,  Deprecate the old
    awkward names, and produce link-time warnings when they are referenced.

==> Deprecate mutable prop_data(3) and prop_string(3) objects.  The old
    APIs that support them still exist, but will now produce link-time
    warnings when used.

==> When the new prop_string(3) API is used, strings are internally
    de-duplicated as a memory footprint optimization.

==> Provide a rich set of bounds-checked gettter functions in and a
    corresponding set of convenience setters in the prop_number(3) API.

==> Add a new prop_bool_value(3) function that is equivalent to
    prop_bool_true(3), but aligned with the new "value" routines in
    prop_data(3), prop_string(3), and prop_number(3).
2020-06-06 21:25:59 +00:00

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.\" $NetBSD: prop_data.3,v 1.9 2020/06/06 21:25:59 thorpej Exp $
.\"
.\" Copyright (c) 2006, 2020 The NetBSD Foundation, Inc.
.\" All rights reserved.
.\"
.\" This code is derived from software contributed to The NetBSD Foundation
.\" by Jason R. Thorpe.
.\"
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.\" modification, are permitted provided that the following conditions
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.Dd June 2, 2020
.Dt PROP_DATA 3
.Os
.Sh NAME
.Nm prop_data ,
.Nm prop_data_create_copy ,
.Nm prop_data_create_nocopy ,
.Nm prop_data_copy ,
.Nm prop_data_size ,
.Nm prop_data_value ,
.Nm prop_data_copy_value ,
.Nm prop_data_equals ,
.Nm prop_data_equals_data
.Nd opaque data value property object
.Sh LIBRARY
.Lb libprop
.Sh SYNOPSIS
.In prop/proplib.h
.\"
.Ft prop_data_t
.Fn prop_data_create_copy "const void *blob" "size_t len"
.Ft prop_data_t
.Fn prop_data_create_nocopy "const void *blob" "size_t len"
.\"
.Ft prop_data_t
.Fn prop_data_copy "prop_data_t data"
.\"
.Ft const void *
.Fn prop_data_value "prop_data_t data"
.Ft bool
.Fn prop_data_copy_value "prop_data_t data" "void *buf" "size_t buflen"
.\"
.Ft size_t
.Fn prop_data_size "prop_data_t data"
.\"
.Ft bool
.Fn prop_data_equals "prop_data_t dat1" "prop_data_t dat2"
.Ft bool
.Fn prop_data_equals_data "prop_data_t data" "const void *blob" "size_t len"
.Sh DESCRIPTION
The
.Nm
family of functions operate on an opaque data value property object type.
.Bl -tag -width "xxxxx"
.It Fn prop_data_create_copy "const void *blob" "size_t len"
Create a data object that contains a copy of
.Fa blob
with size
.Fa len .
Returns
.Dv NULL
on failure.
.It Fn prop_data_create_nocopy "const void *blob" "size_t len"
Similar to
.Fn prop_data_create_copy ,
but is allowed to not create aan internal copy of the opaque data, instead
referencing the buffer passed by the caller.
Caution must be exercised because data objects can have an indefinite
lifespan.
The caller must therefore ensure that the provided buffer reference will
also be valid indefinitely.
This is provided as a memory optimization; it is not guaranteed that
the returned data object will reference the provided buffer, and thus
callers should not rely on this behavior.
Returns
.Dv NULL
on failure.
.It Fn prop_data_copy "prop_data_t data"
Copy a data object.
If the data object being copied is an external data reference,
then the copy also references the same external data.
Returns
.Dv NULL
on failure.
.It Fn prop_data_size "prop_data_t data"
Returns the size of the data object.
If the supplied object isn't a data object, zero is returned.
.It Fn prop_data_value "prop_data_t data"
Returns a reference to the data object's buffer.
If the supplied object isn't a data object or
if the data container is empty,
.Dv NULL
is returned.
.It Fn prop_data_copy_value "prop_data_t data" "void *buf" "size_t buflen"
Copies the contents of the data object into the supplied buffer of the
specified size.
Returns
.Dv true
if the copy succeeds and
.Dv false
iff the supplied buffer is not large enough or if the object is not a
data object.
.It Fn prop_data_equals "prop_data_t dat1" "prop_data_t dat2"
Returns
.Dv true
if the two data objects are equivalent.
If at least one of the supplied objects isn't a data object,
.Dv false
is returned.
.It Fn prop_data_equals_data "prop_data_t data" "const void *blob" "size_t len"
Returns
.Dv true
if the data object's value is equivalent to
.Fa blob
with size
.Fa len .
If the supplied object isn't a data object,
.Dv false
is returned.
.El
.Sh SEE ALSO
.Xr prop_array 3 ,
.Xr prop_bool 3 ,
.Xr prop_dictionary 3 ,
.Xr prop_number 3 ,
.Xr prop_object 3 ,
.Xr prop_string 3 ,
.Xr proplib 3
.Sh HISTORY
The
.Xr proplib 3
property container object library first appeared in
.Nx 4.0 .
Support for mutable data objects was deprecated in
.Nx 10.0 .