.\"
.\" Copyright (c) 2016 Adam Starak <starak.adam@gmail.com>
.\" All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\" $FreeBSD: releng/12.0/share/man/man9/dnv.9 315801 2017-03-23 05:54:07Z ngie $
.\"
.Dd July 26, 2016
.Dt DNV 9
.Os
.Sh NAME
.Nm dnvlist_get ,
.Nm dnvlist_take
.Nd "API for getting name/value pairs. Nonexistent pairs do not raise an error."
.Sh LIBRARY
.Lb libnv
.Sh SYNOPSIS
.In sys/dnv.h
.Ft bool
.Fn dnvlist_get_bool "const nvlist_t *nvl" "const char *name" "bool defval"
.Ft uint64_t
.Fn dnvlist_get_number "const nvlist_t *nvl" "const char *name" "uint64_t defval"
.Ft char *
.Fn dnvlist_get_string "const nvlist_t *nvl" "const char *name" "const char *defval"
.Ft nvlist_t *
.Fn dnvlist_get_nvlist "const nvlist_t *nvl" "const char *name" "nvlist_t *defval"
.Ft int
.Fn dnvlist_get_descriptor "const nvlist_t *nvl" "const char *name" "int defval"
.Ft void *
.Fn dnvlist_get_binary "const nvlist_t *nvl" "const char *name" "size_t *sizep" "void *defval" "size_t defsize"
.Ft bool
.Fn dnvlist_take_bool "const nvlist_t *nvl" "const char *name" "bool defval"
.Ft uint64_t
.Fn dnvlist_take_number "const nvlist_t *nvl" "const char *name" "uint64_t defval"
.Ft char *
.Fn dnvlist_take_string "const nvlist_t *nvl" "const char *name" "const char *defval"
.Ft nvlist_t *
.Fn dnvlist_take_nvlist "const nvlist_t *nvl" "const char *name" "nvlist_t *defval"
.Ft int
.Fn dnvlist_take_descriptor "const nvlist_t *nvl" "const char *name" "int defval"
.Ft void *
.Fn dnvlist_take_binary "const nvlist_t *nvl" "const char *name" "size_t *sizep" "void *defval" "size_t defsize"
.Sh DESCRIPTION
The
.Nm libnv
library permits easy management of name/value pairs and can send and receive
them over sockets.
For more information, also see
.Xr nv 9 .
.Pp
The
.Nm dnvlist_get
family of functions returns the value associated with the specified name.
If an element of the specified name does not exist, the function returns the
value provided in
.Fa defval .
Returned strings, nvlists, descriptors, binaries, or arrays must not be modified
by the user.
They still belong to the nvlist.
If the nvlist is in an error state, attempts to use any of these functions will
cause the program to abort.
.Pp
The
.Nm dnvlist_take
family of functions returns the value associated with the specified name and
removes the element from the nvlist.
If an element of the supplied name does not exist, the value provided in
.Nm defval
is returned.
When the value is a string, binary, or array value, the caller is
responsible for freeing returned memory with
.Fn free 3 .
When the value is an nvlist, the caller is responsible for destroying the
returned nvlist with
.Fn nvlist_destroy .
When the value is a descriptor, the caller is responsible for closing the
returned descriptor with
.Fn close 2 .
.Sh SEE ALSO
.Xr close 2 ,
.Xr free 3 ,
.Xr nv 9
.Sh HISTORY
The
.Nm dnv
API appeared in
.Fx 11.0 .
.Sh AUTHORS
.An -nosplit
The
.Nm dnv
API was implemented by
.An Pawel Jakub Dawidek Aq Mt pawel@dawidek.net
under sponsorship from the FreeBSD Foundation.
This manual page was written by
.An Adam Starak Aq Mt starak.adam@gmail.com