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				.\"
				.\" Copyright (c) 2016 Adam Starak <starak.adam@gmail.com>
				.\" All rights reserved.
				.\"
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				.\" 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.
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				.\" 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
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				.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
				.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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				.\" $FreeBSD$
				.\"
				.Dd July 26, 2016
				.Dt CNV 9
				.Os
				.Sh NAME
				.Nm cnvlist_get,
				.Nm cnvlist_take,
				.Nm cnvlist_free,
				.Nd "API for managing name/value pairs by cookie."
				.Sh LIBRARY
				.Lb libnv
				.Sh SYNOPSIS
				.In sys/cnv.h
				.Ft bool
				.Fn cnvlist_get_bool "void *cookiep"
				.Ft uint64_t
				.Fn cnvlist_get_number "void *cookiep"
				.Ft "const char *"
				.Fn cnvlist_get_string "void *cookiep"
				.Ft "const nvlist_t *"
				.Fn cnvlist_get_nvlist "void *cookiep"
				.Ft "const void *"
				.Fn cnvlist_get_binary "void cookiep" "size_t sizep"
				.Ft "const bool *"
				.Fn cnvlist_get_bool_array "void cookiep" "size_t nitemsp"
				.Ft "const uint64_t *"
				.Fn cnvlist_get_number_array "void cookiep" "size_t nitemsp"
				.Ft "const char * const *"
				.Fn cnvlist_get_string_array "void cookiep" "size_t nitemsp"
				.Ft "const nvlist_t * const *"
				.Fn cnvlist_get_nvlist_array "void cookiep" "size_t nitemsp"
				.Ft int
				.Fn cnvlist_get_descriptor "void *cookiep"
				.Ft "const int *"
				.Fn cnvlist_get_descriptor_array "void cookiep" "size_t nitemsp"
				.\"
				.Ft bool
				.Fn cnvlist_take_bool "void *cookiep"
				.Ft uint64_t
				.Fn cnvlist_take_number "void *cookiep"
				.Ft "const char *"
				.Fn cnvlist_take_string "void *cookiep"
				.Ft "const nvlist_t *"
				.Fn cnvlist_take_nvlist "void *cookiep"
				.Ft "const void *"
				.Fn cnvlist_take_binary "void cookiep" "size_t sizep"
				.Ft "const bool *"
				.Fn cnvlist_take_bool_array "void cookiep" "size_t nitemsp"
				.Ft "const uint64_t *"
				.Fn cnvlist_take_number_array "void cookiep" "size_t nitemsp"
				.Ft "const char * const *"
				.Fn cnvlist_take_string_array "void cookiep" "size_t nitemsp"
				.Ft "const nvlist_t * const *"
				.Fn cnvlist_take_nvlist_array "void cookiep" "size_t nitemsp"
				.Ft int
				.Fn cnvlist_take_descriptor "void *cookiep"
				.Ft "const int *'
				.Fn cnvlist_take_descriptor_array "void cookiep" "size_t nitemsp"
				.\"
				.Ft void
				.Fn cnvlist_free_null "nvlist_t nvl" "void cookiep"
				.Ft void
				.Fn cnvlist_free_bool "nvlist_t nvl" "void cookiep"
				.Ft void
				.Fn cnvlist_free_number "nvlist_t nvl" "void cookiep"
				.Ft void
				.Fn cnvlist_free_string "nvlist_t nvl" "void cookiep"
				.Ft void
				.Fn cnvlist_free_nvlist "nvlist_t nvl" "void cookiep"
				.Ft void
				.Fn cnvlist_free_descriptor "nvlist_t nvl" "void cookiep"
				.Ft void
				.Fn cnvlist_free_binary "nvlist_t nvl" "void cookiep"
				.Ft void
				.Fn cnvlist_free_bool_array "nvlist_t nvl" "void cookiep"
				.Ft void
				.Fn cnvlist_free_number_array "nvlist_t nvl" "void cookiep"
				.Ft void
				.Fn cnvlist_free_string_array "nvlist_t nvl" "void cookiep"
				.Ft void
				.Fn cnvlist_free_nvlist_array "nvlist_t nvl" "void cookiep"
				.Ft void
				.Fn cnvlist_free_descriptor_array "nvlist_t nvl" "void cookiep"
				.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 concept of cookies is explained in
				.Fn nvlist_next ,
				.Fn nvlist_get_parent ,
				and
				.Fn nvlist_get_pararr
				from
				.Xr nv 9 .
				.Pp
				The
				.Nm cnvlist_get
				family of functions obtains the value associated with the given cookie.
				Returned strings, nvlists, descriptors, binaries, or arrays must not be modified
				by the user, since they still belong to the nvlist.
				The nvlist must not be in an error state.
				.Pp
				The
				.Nm cnvlist_take
				family of functions returns the value associated with the given cookie and
				removes the element from the nvlist.
				When the value is a string, binary, or array value, the caller is responsible
				for freeing the 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 the
				.Fn close 2 .
				.Pp
				The
				.Nm cnvlist_free
				family of functions removes an element of the supplied cookie and frees all
				resources.
				If an element of the given cookie has the wrong type or does not exist, the
				program
				is aborted.
				.Sh EXAMPLE
				The following example demonstrates how to deal with cnvlist API.
				.Bd -literal
				int type;
				void cookie, scookie, *bcookie;
				nvlist_t *nvl;
				char *name;

				nvl = nvlist_create(0);
				nvlist_add_bool(nvl, "test", 1 == 2);
				nvlist_add_string(nvl, "test2", "cnvlist");
				cookie = NULL;

				while (nvlist_next(nvl, &type, &cookie) != NULL) {
				switch (type) {
				case NV_TYPE_BOOL:
				printf("test: %d\\n", cnvlist_get_bool(cookie));
				bcookie = cookie;
				break;
				case NV_TYPE_STRING:
				printf("test2: %s\\n", cnvlist_get_string(cookie));
				scookie = cookie;
				break;
				}
				}

				name = cnvlist_take_string(nvl, scookie);
				cnvlist_free_bool(nvl, bcookie);

				printf("test2: %s\\n", name);
				free(name);

				printf("nvlist_empty = %d\\n", nvlist_empty(nvl));
				nvlist_destroy(nvl);

				return (0);
				.Ed
				.Sh SEE ALSO
				.Xr nv 9 ,
				.Xr close 2 ,
				.Xr free 3
				.Sh AUTHORS
				.An -nosplit
				The
				.Nm cnv
				API was created during the Google Summer Of Code 2016 by