YPCLNT(3N-SVR4) RISC/os Reference Manual YPCLNT(3N-SVR4)
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 - NIS client interface
SYNOPSIS
#include <rpcsvc/ypclnt.h>
#include <rpcsvc/ypprot.h>
DESCRIPTION
This package of functions provides an interface to the Net-
work Information Service (NIS) network lookup service. The
package can be loaded from the standard library,
/usr/lib/libnsl.{so,a}. Refer to ypfiles(4) and ypserv(1M)
for an overview of the NIS name services, including the
definitions of map and domain, and a description of the
various servers, databases, and commands that comprise the
NIS name service.
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(3), and may
be freed if the user code has no continuing need for it.
For each outkey and outval, two extra bytes of memory are
allocated at the end that contain NEWLINE and NULL, respec-
tively, 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 accom-
panied 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.
Routines
ypbind (indomain);
char *indomain;
To use the NIS name services, the client process must
be bound to a NIS server that serves the appropriate
domain using ypbind(). Binding need not be done
explicitly by user code; this is done automatically
whenever a NIS lookup function is called. ypbind()
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
ypunbind (indomain)
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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. ypunbind() is avail-
able at the client interface for processes that expli-
citly manage their socket descriptors while accessing
multiple domains. The call to ypunbind() 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
⊕ the client process cannot bind a server for the
proper domain, or
⊕ 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.
ypgetdefaultdomain (outdomain);
char **outdomain;
The NIS lookup calls require a map name and a domain
name, at minimum. It is assumed that the client pro-
cess knows the name of the map of interest. Client
processes should fetch the node's default domain by
calling ypgetdefaultdomain(), and use the returned
outdomain as the indomain parameter to successive NIS
name service calls.
ypmatch(indomain, inmap, inkey, inkeylen, outval, outvallen)
char *indomain;
char *inmap;
char *inkey;
int inkeylen;
char **outval;
int *outvallen;
ypmatch() returns the value associated with a passed
key. This key must be exact; no pattern matching is
available.
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ypfirst(indomain, inmap, outkey, outkeylen, outval, outvallen)
char *indomain;
char *inmap;
char **outkey;
int *outkeylen;
char **outval;
int *outvallen;
ypfirst() returns the first key-value pair from the
named map in the named domain.
ypnext(indomain, inmap, inkey, inkeylen, outkey, outkeylen, outval, outvallen);
char *indomain;
char *inmap;
char *inkey;
int inkeylen;
char **outkey;
int *outkeylen;
char **outval;
int *outvallen;
ypnext() returns the next key-value pair in a named
map. The inkey parameter should be the outkey returned
from an initial call to ypfirst() (to get the second
key-value pair) or the one returned from the nth call
to ypnext() (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 pro-
cessing; there is no relation in retrieval order to
either the lexical order within any original (non-NIS
name service) 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
ypfirst() function is called on a particular map, and
then the ypnext() 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
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solution to enumerating all entries in a map.
ypall(indomain, inmap, incallback);
char *indomain;
char *inmap;
struct ypallcallback *incallback;
ypall() 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. ypall() can be used just like any other
NIS name service 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. The call to ypall() returns only when the
transaction is completed (successfully or unsuccess-
fully), or the foreach function decides that it does
not want to see any more key-value pairs.
The third parameter to ypall() is
struct ypallcallback *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 ypproterr(), below, for
a function which converts a NIS name service 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 ypall() 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-
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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 ypall(). 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.
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 ypall() is then 0.
yporder(indomain, inmap, outorder);
char *indomain;
char *inmap;
int *outorder;
yporder() returns the order number for a map.
ypmaster(indomain, inmap, outname);
char *indomain;
char *inmap;
char **outname;
ypmaster() returns the machine name of the master NIS
server for a map.
char *yperrstring(incode)
int incode;
yperrstring() returns a pointer to an error message
string that is NULL-terminated but contains no period
or NEWLINE.
ypproterr (incode)
unsigned int incode;
ypproterr() takes a NIS name service protocol error
code as input, and returns a ypclnt layer error code,
which may be used in turn as an input to
yperrstring().
FILES
/usr/lib/libyp.a
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SEE ALSO
ypserv(1M), malloc(3), ypupdate(3N), ypfiles(4)
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 */"
#define YPERR_NOMORE
"8 /* no more records in map database */"
#define YPERR_PMAP
"9 /* can't communicate with rpcbinder */"
#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 */"
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#define YPERR_BUSY
"16 /* database busy */"
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