ypclnt(3N) DG/UX 5.4R3.00 ypclnt(3N)
NAME
ypclnt, yp_get_default_domain, yp_bind, yp_unbind, yp_match,
yp_first, yp_next, yp_all, yp_order, yp_master, yperr_string,
ypprot_err - Network Information Service client interface
SYNOPSIS AND DESCRIPTION
This package of functions provides an interface to the Network
Information Service (NIS) network lookup service. The package can be
loaded from the standard library, /usr/lib/libc.a. Refer to
ypfiles(4) and ypserv(1M) for an overview of the Network Information
Service, including the definitions of map and domain, and a
description of the various servers, databases, and commands that
comprise the NIS.
All input parameters names begin with in. Output parameters begin
with out. Output parameters of type char ** should be addresses of
uninitialized character pointers. Memory is allocated by the NIS
client package using malloc(3C), and may be freed if the user code
has no continuing need for it. One exception to this is
yp_get_default_domain(). This function retains a static pointer to
outdomain, in case another request for outdomain is made. If you
free this memory, you could cause your process to core dump. For
each outkey and outval, two extra bytes of memory are allocated at
the end that contain NEWLINE and NULL, respectively, but these two
bytes are not reflected in outkeylen or outvallen. indomain and
inmap strings must be non-NULL and NULL-terminated. String
parameters which are accompanied by a count parameter may not be
NULL, but may point to NULL strings, with the count parameter
indicating this. Counted strings need not be NULL-terminated.
All functions in this package of type int return 0 if they succeed,
and a failure code (YPERR_xxxx) otherwise. Failure codes are
described under DIAGNOSTICS below.
yp_bind (indomain);
char *indomain;
To use the NIS services, the client process must be "bound" to
a NIS server that serves the appropriate domain using
yp_bind(). Binding need not be done explicitly by user code;
this is done automatically whenever a NIS lookup function is
called. yp_bind() can be called directly for processes that
make use of a backup strategy (for example, a local file) in
cases when NIS services are not available.
void
yp_unbind (indomain)
char *indomain;
Each binding allocates (uses up) one client process socket
descriptor; each bound domain costs one socket descriptor.
However, multiple requests to the same domain use that same
descriptor. yp_unbind() is available at the client interface
for processes that explicitly manage their socket descriptors
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while accessing multiple domains. The call to yp_unbind()
make the domain unbound, and free all per-process and per-node
resources used to bind it.
If an RPC failure results upon use of a binding, that domain
will be unbound automatically. At that point, the ypclnt
layer will retry forever or until the operation succeeds,
provided that ypbind is running, and either
a) the client process cannot bind a server for the proper
domain, or
b) RPC requests to the server fail.
If an error is not RPC-related, or if ypbind is not running,
or if a bound ypserv process returns any answer (success or
failure), the ypclnt layer will return control to the user
code, either with an error code, or a success code and any
results.
yp_get_default_domain (outdomain);
char **outdomain;
The NIS lookup calls require a map name and a domain name, at
minimum. It is assumed that the client process knows the name
of the map of interest. Client processes should fetch the
node's default domain by calling yp_get_default_domain(), and
use the returned outdomain as the indomain parameter to
successive NIS calls. Because yp_get_default_domain() sets a
static pointer to the outdomain, it is not safe to free
outdomain. Successive calls to yp_get_default_domain() will
use that static pointer to return the outdomain.
yp_match(indomain, inmap, inkey, inkeylen, outval, outvallen)
char *indomain;
char *inmap;
char *inkey;
int inkeylen;
char **outval;
int *outvallen;
yp_match() returns the value associated with a passed key.
This key must be exact; no pattern matching is available.
yp_first(indomain, inmap, outkey, outkeylen, outval, outvallen)
char *indomain;
char *inmap;
char **outkey;
int *outkeylen;
char **outval;
int *outvallen;
yp_first() returns the first key-value pair from the named map
in the named domain.
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yp_next(indomain, inmap, inkey, inkeylen, outkey, outkeylen,
outval, outvallen);
char *indomain;
char *inmap;
char *inkey;
int inkeylen;
char **outkey;
int *outkeylen;
char **outval;
int *outvallen;
yp_next() returns the next key-value pair in a named map. The
inkey parameter should be the outkey returned from an initial
call to yp_first() (to get the second key-value pair) or the
one returned from the nth call to yp_next() (to get the nth +
second key-value pair).
The concept of first (and, for that matter, of next) is
particular to the structure of the NIS map being processing;
there is no relation in retrieval order to either the lexical
order within any original (non-NIS) data base, or to any
obvious numerical sorting order on the keys, values, or key-
value pairs. The only ordering guarantee made is that if the
yp_first() function is called on a particular map, and then
the yp_next() function is repeatedly called on the same map at
the same server until the call fails with a reason of
YPERR_NOMORE, every entry in the data base will be seen
exactly once. Further, if the same sequence of operations is
performed on the same map at the same server, the entries will
be seen in the same order.
Under conditions of heavy server load or server failure, it is
possible for the domain to become unbound, then bound once
again (perhaps to a different server) while a client is
running. This can cause a break in one of the enumeration
rules; specific entries may be seen twice by the client, or
not at all. This approach protects the client from error
messages that would otherwise be returned in the midst of the
enumeration. The next paragraph describes a better solution
to enumerating all entries in a map.
yp_all(indomain, inmap, incallback);
char *indomain;
char *inmap;
struct ypall_callback incallback;
yp_all() provides a way to transfer an entire map from server
to client in a single request using TCP (rather than UDP as
with other functions in this package). The entire transaction
take place as a single RPC request and response. You can use
yp_all() just like any other NIS procedure, identify the map
in the normal manner, and supply the name of a function which
will be called to process each key-value pair within the map.
You return from the call to yp_all() only when the transaction
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is completed (successfully or unsuccessfully), or your foreach
function decides that it does not want to see any more key-
value pairs.
The third parameter to yp_all() is
struct ypall_callback *incallback {
int (*foreach)();
char *data;
};
The function foreach is called
foreach(instatus, inkey, inkeylen, inval, invallen, indata);
int instatus;
char *inkey;
int inkeylen;
char *inval;
int invallen;
char *indata;
The instatus parameter will hold one of the return status
values defined in <rpcsvc/yp_prot.h> -- either YP_TRUE or an
error code. (See ypprot_err(), below, for a function which
converts a NIS protocol error code to a ypclnt layer error
code.)
The key and value parameters are somewhat different than
defined in the synopsis section above. First, the memory
pointed to by the inkey and inval parameters is private to the
yp_all() function, and is overwritten with the arrival of each
new key-value pair. It is the responsibility of the foreach
function to do something useful with the contents of that
memory, but it does not own the memory itself. Key and value
objects presented to the foreach function look exactly as they
do in the server's map -- if they were not NEWLINE-terminated
or NULL-terminated in the map, they will not be here either.
The indata parameter is the contents of the incallback->data
element passed to yp_all(). The data element of the callback
structure may be used to share state information between the
foreach function and the mainline code. Its use is optional,
and no part of the NIS client package inspects its contents --
cast it to something useful, or ignore it as you see fit.
The foreach function is a Boolean. It should return zero to
indicate that it wants to be called again for further received
key-value pairs, or non-zero to stop the flow of key-value
pairs. If foreach returns a non-zero value, it is not called
again; the functional value of yp_all() is then 0.
yp_order(indomain, inmap, outorder);
char *indomain;
char *inmap;
int *outorder;
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yp_order() returns the order number for a map.
yp_master(indomain, inmap, outname);
char *indomain;
char *inmap;
char **outname;
yp_master() returns the machine name of the master NIS server
for a map.
char *yperr_string(incode)
int incode;
yperr_string() returns a pointer to an error message string
that is NULL-terminated but contains no period or NEWLINE.
ypprot_err (incode)
unsigned int incode;
ypprot_err() takes a NIS protocol error code as input, and
returns a ypclnt layer error code, which may be used in turn
as an input to yperr_string().
FILES
/usr/include/rpcsvc/ypclnt.h
/usr/include/rpcsvc/yp_prot.h
/usr/lib/libc.a
DIAGNOSTICS
All integer functions return 0 if the requested operation is
successful, or one of the following errors if the operation fails.
#define YPERR_BADARGS
1 /* args to function are bad */
#define YPERR_RPC
2 /* RPC failure - domain has been unbound */
#define YPERR_DOMAIN
3 /* can't bind to server on this domain */
#define YPERR_MAP
4 /* no such map in server's domain */
#define YPERR_KEY
5 /* no such key in map */
#define YPERR_YPERR
6 /* internal yp server or client error */
#define YPERR_RESRC
7 /* resource allocation failure */
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#define YPERR_NOMORE
8 /* no more records in map database */
#define YPERR_PMAP
9 /* can't communicate with portmapper */
#define YPERR_YPBIND
10 /* can't communicate with ypbind */
#define YPERR_YPSERV
11 /* can't communicate with ypserv */
#define YPERR_NODOM
12 /* local domain name not set */
#define YPERR_BADDBfR
13 /* yp database is bad */
#define YPERR_VERSfR
14 /* yp version mismatch */
#define YPERR_ACCESS
15 /* access violation */
#define YPERR_BUSY
16 /* database busy */
SEE ALSO
ypserv(1M), malloc(3C), yp_update(3R), ypfiles(4).
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