fbbd9655e5
Renumber cluase 4 to 3, per what everybody else did when BSD granted them permission to remove clause 3. My insistance on keeping the same numbering for legal reasons is too pedantic, so give up on that point. Submitted by: Jan Schaumann <jschauma@stevens.edu> Pull Request: https://github.com/freebsd/freebsd/pull/96
258 lines
6.3 KiB
Groff
258 lines
6.3 KiB
Groff
.\" $NetBSD: nsdispatch.3,v 1.8 1999/03/22 19:44:53 garbled Exp $
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.\"
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.\" Copyright (c) 1997, 1998, 1999 The NetBSD Foundation, Inc.
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.\" All rights reserved.
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.\"
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.\" This code is derived from software contributed to The NetBSD Foundation
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.\" by Luke Mewburn.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. Neither the name of The NetBSD Foundation nor the names of its
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.\" contributors may be used to endorse or promote products derived
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.\" from this software without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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.\" POSSIBILITY OF SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd April 4, 2010
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.Dt NSDISPATCH 3
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.Os
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.Sh NAME
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.Nm nsdispatch
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.Nd name-service switch dispatcher routine
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.In sys/types.h
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.In stdarg.h
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.In nsswitch.h
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.Ft int
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.Fo nsdispatch
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.Fa "void *retval"
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.Fa "const ns_dtab dtab[]"
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.Fa "const char *database"
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.Fa "const char *method_name"
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.Fa "const ns_src defaults[]"
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.Fa "..."
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.Fc
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.Sh DESCRIPTION
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The
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.Fn nsdispatch
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function invokes the methods specified in
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.Va dtab
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in the order given by
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.Xr nsswitch.conf 5
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for the database
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.Va database
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until a successful entry is found.
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.Pp
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.Va retval
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is passed to each method to modify as necessary, to pass back results to
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the caller of
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.Fn nsdispatch .
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.Pp
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Each method has the function signature described by the typedef:
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.Pp
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.Ft typedef int
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.Fn \*(lp*nss_method\*(rp "void *retval" "void *mdata" "va_list *ap" ;
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.Pp
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.Va dtab
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is an array of
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.Va ns_dtab
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structures, which have the following format:
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.Bd -literal -offset indent
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typedef struct _ns_dtab {
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const char *src;
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nss_method method;
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void *mdata;
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} ns_dtab;
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.Ed
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.Pp
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The
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.Fa dtab
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array should consist of one entry for each source type that is
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implemented, with
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.Va src
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as the name of the source,
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.Va method
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as a function which handles that source, and
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.Va mdata
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as a handle on arbitrary data to be passed to the method.
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The last entry in
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.Va dtab
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should contain
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.Dv NULL
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values for
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.Va src ,
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.Va method ,
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and
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.Va mdata .
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.Pp
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Additionally, methods may be implemented in NSS modules, in
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which case they are selected using the
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.Fa database
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and
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.Fa method_name
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arguments along with the configured source.
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(The methods supplied via
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.Fa dtab
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take priority over those implemented in NSS modules in the event
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of a conflict.)
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.Pp
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.Va defaults
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contains a list of default sources to try if
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.Xr nsswitch.conf 5
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is missing or corrupted, or if there is no relevant entry for
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.Va database .
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It is an array of
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.Va ns_src
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structures, which have the following format:
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.Bd -literal -offset indent
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typedef struct _ns_src {
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const char *src;
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uint32_t flags;
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} ns_src;
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.Ed
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.Pp
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The
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.Fa defaults
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array should consist of one entry for each source to be configured by
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default indicated by
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.Va src ,
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and
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.Va flags
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set to the criterion desired
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(usually
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.Dv NS_SUCCESS ;
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refer to
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.Sx Method return values
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for more information).
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The last entry in
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.Va defaults
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should have
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.Va src
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set to
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.Dv NULL
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and
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.Va flags
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set to 0.
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.Pp
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For convenience, a global variable defined as:
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.Pp
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.Dl extern const ns_src __nsdefaultsrc[];
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.Pp
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exists which contains a single default entry for the source
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.Sq files
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that may be used by callers which do not require complicated default
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rules.
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.Pp
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.Sq Va ...
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are optional extra arguments, which are passed to the appropriate method
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as a variable argument list of the type
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.Vt va_list .
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.Ss Valid source types
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While there is support for arbitrary sources, the following
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#defines for commonly implemented sources are available:
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.Bl -column NSSRC_COMPAT compat -offset indent
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.It Sy "#define value"
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.It Dv NSSRC_FILES Ta \&"files\&"
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.It Dv NSSRC_DB Ta \&"db\&"
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.It Dv NSSRC_DNS Ta \&"dns\&"
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.It Dv NSSRC_NIS Ta \&"nis\&"
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.It Dv NSSRC_COMPAT Ta \&"compat\&"
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.El
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.Pp
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Refer to
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.Xr nsswitch.conf 5
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for a complete description of what each source type is.
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.Ss Method return values
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The
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.Vt nss_method
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functions must return one of the following values depending upon status
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of the lookup:
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.Bl -column "Return value" "Status code"
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.It Sy "Return value Status code"
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.It Dv NS_SUCCESS Ta success
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.It Dv NS_NOTFOUND Ta notfound
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.It Dv NS_UNAVAIL Ta unavail
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.It Dv NS_TRYAGAIN Ta tryagain
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.It Dv NS_RETURN Ta -none-
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.El
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.Pp
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Refer to
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.Xr nsswitch.conf 5
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for a complete description of each status code.
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.Pp
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The
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.Fn nsdispatch
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function returns the value of the method that caused the dispatcher to
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terminate, or
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.Dv NS_NOTFOUND
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otherwise.
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.Sh NOTES
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.Fx Ns 's
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.Lb libc
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provides stubs for compatibility with NSS modules
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written for the
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.Tn GNU
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C Library
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.Nm nsswitch
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interface.
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However, these stubs only support the use of the
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.Dq Li passwd
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and
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.Dq Li group
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databases.
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.Sh SEE ALSO
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.Xr hesiod 3 ,
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.Xr stdarg 3 ,
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.Xr nsswitch.conf 5 ,
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.Xr yp 8
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.Sh HISTORY
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The
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.Fn nsdispatch
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function first appeared in
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.Fx 5.0 .
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It was imported from the
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.Nx
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Project,
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where it appeared first in
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.Nx 1.4 .
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Support for NSS modules first appeared in
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.Fx 5.1 .
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.Sh AUTHORS
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.An Luke Mewburn Aq Mt lukem@netbsd.org
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wrote this freely-distributable name-service switch implementation,
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using ideas from the
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.Tn ULTRIX
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svc.conf(5)
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and
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.Tn Solaris
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nsswitch.conf(4)
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manual pages.
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The
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.Fx
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Project
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added the support for threads and NSS modules, and normalized the uses
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of
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.Fn nsdispatch
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within the standard C library.
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