.\"     $NetBSD: optstr.9,v 1.4 2008/04/30 13:10:58 martin Exp $
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.Dd August 11, 2007
.Dt OPTSTR 9
.Os
.Sh NAME
.Nm optstr_get
.Nd Options string management
.Sh SYNOPSIS
.In sys/optstr.h
.Ft bool
.Fn optstr_get "const char *optstr" "const char *key" "char *buf" "size_t bufsize"
.Sh DESCRIPTION
An options string is a list of key/value pairs represented in textual form.
Each pair is expressed as
.Sq 'key=value'
and is separated from other pairs by one or more spaces.
For example:
.Bd -literal
key1=value1 key2=value2 key3=value3
.Ed
.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 compact
.It Fn optstr_get "optstr" "key" "buf" "bufsize"
Scans the
.Va optstr
options string looking for the key
.Va key
and stores its value in the buffer pointed to by
.Va buf
copying a maximum of
.Va bufsize
bytes.
Returns
.Sq true
if the key was found or
.Sq false
otherwise, in which case
.Va buf
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 .