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Diffstat (limited to 'newlib/libc/sys/linux/net/nsdispatch.3')
| -rw-r--r-- | newlib/libc/sys/linux/net/nsdispatch.3 | 231 |
1 files changed, 231 insertions, 0 deletions
diff --git a/newlib/libc/sys/linux/net/nsdispatch.3 b/newlib/libc/sys/linux/net/nsdispatch.3 new file mode 100644 index 000000000..708f97cba --- /dev/null +++ b/newlib/libc/sys/linux/net/nsdispatch.3 @@ -0,0 +1,231 @@ +.\" $NetBSD: nsdispatch.3,v 1.8 1999/03/22 19:44:53 garbled Exp $ +.\" $FreeBSD: src/lib/libc/net/nsdispatch.3,v 1.5 2001/10/01 16:08:56 ru Exp $ +.\" +.\" Copyright (c) 1997, 1998, 1999 The NetBSD Foundation, Inc. +.\" All rights reserved. +.\" +.\" This code is derived from software contributed to The NetBSD Foundation +.\" by Luke Mewburn. +.\" +.\" 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. +.\" 3. All advertising materials mentioning features or use of this software +.\" must display the following acknowledgement: +.\" This product includes software developed by the NetBSD +.\" Foundation, Inc. and its contributors. +.\" 4. Neither the name of The NetBSD Foundation nor the names of its +.\" contributors may be used to endorse or promote products derived +.\" from this software without specific prior written permission. +.\" +.\" 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 January 19, 1999 +.Dt NSDISPATCH 3 +.Os +.Sh NAME +.Nm nsdispatch +.Nd name-service switch dispatcher routine +.Sh LIBRARY +.Lb libc +.Sh SYNOPSIS +.In nsswitch.h +.Ft int +.Fo nsdispatch +.Fa "void *retval" +.Fa "const ns_dtab dtab[]" +.Fa "const char *database" +.Fa "const char *method" +.Fa "const ns_src defaults[]" +.Fa "..." +.Fc +.Sh DESCRIPTION +The +.Fn nsdispatch +function invokes the callback functions specified in +.Va dtab +in the order given in +.Pa /etc/nsswitch.conf +for the database +.Va database +until a successful entry is found. +.Pp +.Va retval +is passed to each callback function to modify as necessary +(to pass back to the caller of +.Fn nsdispatch ) +.Pp +.Va dtab +is an array of +.Va ns_dtab +structures, which have the following format: +.Bd -literal -offset indent +typedef struct { + const char *src; + int (*cb)(void *retval, void *cb_data, va_list ap); + void *cb_data; +} ns_dtab; +.Ed +.Pp +.Bd -ragged -offset indent +For each source type that is implemented, an entry with +.Va src +set to the name of the source, +.Va cb +defined as a function which handles that source, and +.Va cb_data +is used to pass arbritrary data to the callback function. +The last entry in +.Va dtab +should contain +.Dv NULL +values for +.Va src , +.Va cb , +and +.Va cb_data . +.Ed +.Pp +.Va method +is usually the name of the function calling +.Fn nsdispatch . +When dynamic loading is supported, a symbol constructed from +.Va database , +the current source, and +.Va method +will be used as the name to invoke the dynamically loaded function. +.Pp +.Va defaults +contains a list of default sources to try in the case of +a missing or corrupt +.Xr nsswitch.conf 5 , +or if there isn't a relevant entry for +.Va database . +It is an array of +.Va ns_src +structures, which have the following format: +.Bd -literal -offset indent +typedef struct { + const char *src; + u_int32_t flags; +} ns_src; +.Ed +.Pp +.Bd -ragged -offset indent +For each default source type, an entry with +.Va src +set to the name of the source, and +.Va flags +set to the relevant flags +(usually +.Dv NS_SUCCESS ; +refer to +.Sx Callback return values +for more information). +The last entry in +.Va defaults +should have +.Va src +set to +.Dv NULL +and +.Va flags +set to 0. +.Pp +For convenience, a global variable defined as: +.Dl extern const ns_src __nsdefaultsrc[]; +exists which contains a single default entry for +.Sq files +for use by callers which don't require complicated default rules. +.Ed +.Pp +.Sq Va ... +are optional extra arguments, which +are passed to the appropriate callback function as a variable argument +list of the type +.Va va_list . +.Ss Valid source types +Whilst there is support for arbitrary sources, the following +#defines for commonly implementated sources are available: +.Bl -column NS_COMPAT COMPAT -offset indent +.It Sy "#define value" +.It "NSSRC_FILES ""files""" +.It "NSSRC_DNS ""dns""" +.It "NSSRC_NIS ""nis""" +.It "NSSRC_COMPAT ""compat""" +.El +.Pp +Refer to +.Xr nsswitch.conf 5 +for a complete description of what each source type is. +.Pp +.Ss Callback return values +The callback functions should return one of the following values +depending upon status of the lookup: +.Bl -column NS_NOTFOUND -offset indent +.It Sy "Return value Status code" +.It "NS_SUCCESS success" +.It "NS_NOTFOUND notfound" +.It "NS_UNAVAIL unavail" +.It "NS_TRYAGAIN tryagain" +.El +.Pp +Refer to +.Xr nsswitch.conf 5 +for a complete description of what each status code is. +.Pp +.Nm +returns the value of the callback that caused the dispatcher to finish, +or NS_NOTFOUND otherwise. +.Sh SEE ALSO +.Xr hesiod 3 , +.Xr stdarg 3 , +.Xr ypclnt 3 , +.Xr nsswitch.conf 5 +.Sh HISTORY +The +.Nm +routines first appeared in +.Fx 4.1 . +They were imported from the +.Nx +Project, +where they appeared first in +.Nx 1.4 . +.Sh AUTHORS +Luke Mewburn +.Aq lukem@netbsd.org +wrote this freely distributable name-service switch implementation, +using ideas from the +.Tn ULTRIX +.Xr svc.conf 5 +and +.Tn Solaris +.Xr nsswitch.conf 4 +manual pages. +.Sh BUGS +The +.Nm +routines are not thread safe. +This will be rectified in the future. +.Pp +Currently there is no support for dynamically loadable dispatcher callback +functions. +It is anticipated that this will be added in the future in the back-end +without requiring changes to code that invokes +.Fn nsdispatch . |