.\"     $NetBSD: optstr.9,v 1.6 2023/04/20 10:43:17 uwe Exp $
.\"
.\" Copyright (c) 2006 The NetBSD Foundation, Inc.
.\" All rights reserved.
.\"
.\" This code is derived from software contributed to The NetBSD Foundation
.\" by Julio M. Merino Vidal.
.\"
.\" 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 NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
.\"
.Dd May 20, 2023
.Dt OPTSTR 9
.Os
.
.Sh NAME
.Nm optstr_get ,
.Nm optstr_get_string ,
.Nm optstr_get_number ,
.Nm optstr_get_number_binary ,
.Nm optstr_get_number_hex ,
.Nm optstr_get_macaddr
.Nd Options string management
.
.Sh SYNOPSIS
.In sys/optstr.h
.
.Ft bool
.Fo optstr_get
.Fa "const char *optstr"
.Fa "const char *key"
.Fa "char *buf"
.Fa "size_t bufsize"
.Fc
.
.Ft bool
.Fo optstr_get_string
.Fa "const char *optstr"
.Fa "const char *key"
.Fa "char **result"
.Fc
.
.Ft bool
.Fo optstr_get_number
.Fa "const char *optstr"
.Fa "const char *key"
.Fa "unsigned long *result"
.Fc
.
.Ft bool
.Fo optstr_get_number_binary
.Fa "const char *optstr"
.Fa "const char *key"
.Fa "unsigned long *result"
.Fc
.
.Ft bool
.Fo optstr_get_number_hex
.Fa "const char *optstr"
.Fa "const char *key"
.Fa "unsigned long *result"
.Fc
.
.Ft bool
.Fo optstr_get_macaddr
.Fa "const char *optstr"
.Fa "const char *key"
.Fa "uint8_t result[ETHER_ADDR_LEN]"
.Fc
.
.Sh DESCRIPTION
An options string is a list of key/value pairs represented in textual form.
Each pair is expressed as
.Ar key\^ Ns Li = Ns Ar value
and is separated from other pairs by one or more spaces.
For example:
.Pp
.Dl key1=value1 key2=value2 key3=value3
.Pp
Options strings are used to pass information between userland programs and
the kernel in a binary-agnostic way.
This makes them endianness and ABI independent.
.Sh FUNCTIONS
The following functions are provided to manage options strings:
.Bl -tag -width Fn
.It Fn optstr_get "optstr" "key" "buf" "bufsize"
Scans the
.Fa optstr
options string looking for the key
.Fa key
and stores its value in the buffer pointed to by
.Fa buf
copying a maximum of
.Fa bufsize
bytes.
Returns
.Ql true
if the key was found or
.Ql false
otherwise, in which case
.Fa buf
is left unmodified.
.El
.Pp
The
.Li optstr_get_ Ns Ar item
family of functions provide the ability to scan for the key, and
return the value converted to an appropriate type.
.Pp
.Bl -tag -width Fn -compact
.It Fn optstr_get_string "optstr" "key" "result"
.It Fn optstr_get_number "optstr" "key" "result"
.It Fn optstr_get_number_binary "optstr" "key" "result"
.It Fn optstr_get_number_hex "optstr" "key" "result"
.It Fn optstr_get_macaddr "optstr" "key" "result"
These functions scan the
.Fa optstr
options string looking for the key
.Fa key
and returns the key value converted as per the function name in
.Fa result .
All functions return
.Ql true
if the key was found or
.Ql false
otherwise, in which case
.Fa result
is left unmodified.
.El
.Sh CODE REFERENCES
The options string management functions are implemented within the files
.Pa sys/kern/subr_optstr.c
and
.Pa sys/sys/optstr.h .
.Sh HISTORY
Options strings appeared in
.Nx 4.0 .