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NAMErpc_clnt_calls: clnt_call(), clnt_freeres(), clnt_geterr(), clnt_perrno(), clnt_perror(), clnt_sperrno(), clnt_sperror(), rpc_broadcast(), rpc_broadcast_exp(), rpc_call() — library routines for client side calls SYNOPSIS#include <rpc/rpc.h> enum clnt_stat clnt_call(CLIENT *clnt,
const rpcproc_t procnum,
const xdrproc_t inproc,
const caddr_t in,
const xdrproc_t outproc,
caddr_t out,
const struct timeval tout); bool_t clnt_freeres(CLIENT *clnt,
const xdrproc_t outproc,
caddr_t out); void clnt_geterr(const CLIENT *clnt,
struct rpc_err *errp); void clnt_perrno(const enum clnt_stat stat); void clnt_perror(const CLIENT *clnt,
const char *s); char *clnt_sperrno(const enum clnt_stat stat); char *clnt_sperror(const CLIENT *clnt,
const char *s); enum clnt_stat rpc_broadcast(const rpcprog_t prognum,
const rpcvers_t versnum,
const rpcproc_t procnum,
const xdrproc_t inproc,
const caddr_t in,
const xdrproc_t outproc,
caddr_t out,
const resultproc_t eachresult,
const char *nettype); enum clnt_stat rpc_broadcast_exp(const rpcprog_t prognum,
const rpcvers_t versnum,
const rpcproc_t procnum,
const xdrproc_t xargs,
caddr_t argsp,
const xdrproc_t xresults,
caddr_t resultsp,
const resultproc_t eachresult,
const int inittime,
const int waittime,
const char *nettype); enum clnt_stat rpc_call(const char *host,
const rpcprog_t prognum,
const rpcvers_t versnum,
const rpcproc_t procnum,
const xdrproc_t inproc,
const char *in,
const xdrproc_t outproc,
char *out,
const char *nettype); DESCRIPTIONRPC
library routines allow
C
language programs to make procedure
calls on other machines across the network.
First, the client calls a procedure to send a request to the server.
Upon receipt of the request, the server calls a dispatch routine
to perform the requested service, and then sends back a reply. The
clnt_call(),
rpc_call(),
and
rpc_broadcast()
routines handle the client side of the procedure call.
The remaining routines deal with error handling. Some of the routines take a
CLIENT
handle as one of the parameters.
A
CLIENT
handle can be created by an RPC creation routine such as
clnt_create()
(see
rpc_clnt_create(3N)). These routines are safe for use in multithreaded applications.
CLIENT
handles can be shared between threads, however in this implementation
requests by different threads are serialized (that is, the first
request will receive its results before the second request is sent). The HP-UX implementation of RPC only supports the X/Open Transport
Interface (XTI).
Applications that are written using the Transport Layer Interface
(TLI) and wish to use RPC, must convert their application to XTI. RoutinesSee
rpc(3N)
for the definition of the
CLIENT
data structure. - enum clnt_stat clnt_call()
A function macro that calls the remote procedure
procnum
associated with the client handle,
clnt,
which is obtained with an RPC client creation routine such as
clnt_create()
(see
rpc_clnt_create(3N)).
The parameter
inproc
is the XDR function used to encode the procedure's parameters, and
outproc
is the XDR function used to decode the procedure's results.
in
is the address of the procedure's argument(s), and
out
is the address of where to place the result(s).
tout
is the time allowed for results to be returned, which is overridden by
a time-out set explicitly through
clnt_control()
(see
rpc_clnt_create(3N)). If the remote call succeeds, the status returned is
RPC_SUCCESS.
Otherwise, an appropriate status is returned. - bool_t clnt_freeres()
A function macro that frees any data allocated by the
RPC/XDR system when it decoded the results of an RPC call.
The parameter
out
is the address of the results, and
outproc
is the XDR routine describing the results.
This routine returns
1
if the results were successfully freed; otherwise it returns
0. - void clnt_geterr()
A function macro that copies the error structure out of the client
handle to the structure at address
errp. - void clnt_perrno()
Prints a message to standard error corresponding
to the condition indicated by
stat.
A newline is appended.
It is normally used after a procedure call fails for a routine
for which a client handle is not needed, for instance
rpc_call(). - void clnt_perror()
Prints a message to the standard error indicating why an RPC call failed;
clnt
is the handle used to do the call.
The message is prepended with string
s
and a colon.
A newline is appended.
It is normally used after a remote procedure call fails
for a routine which requires a client handle,
for instance
clnt_call(). - char *clnt_sperrno()
Takes the same arguments as
clnt_perrno(),
but instead of sending a message to the standard error indicating why an
RPC call failed, returns a pointer to a string that contains the message. clnt_sperrno()
is normally used instead of
clnt_perrno()
when the program does not have a standard error, as a program
running as a server quite likely does not.
clnt_sperrno()
is also used if the programmer does not want the message to be output with
printf()
(see
printf(3S)),
or if a message format different than that supported by
clnt_perrno()
is to be used. Unlike
clnt_sperror()
and
clnt_spcreaterror()
(see
rpc_clnt_create(3N)),
clnt_sperrno()
does not return a pointer to static data.
Therefore, the result is not overwritten on each call. - char *clnt_sperror()
Similar to
clnt_perror(),
except that like
clnt_sperrno(),
it returns a string instead of printing to standard error.
However,
clnt_sperror()
does not append a newline
at the end of the message. clnt_sperror()
returns a pointer to a buffer that is overwritten
on each call.
In multithreaded applications, this buffer is implemented as
thread-specific data. - enum clnt_stat rpc_broadcast()
Similar to
rpc_call(),
except that the call message is broadcast to
all the connectionless transports specified by
nettype.
If
nettype
is
NULL,
it defaults to
netpath.
Each time it receives a response, this routine calls
eachresult(),
whose form is:
bool_t eachresult(
caddr_t out,
const struct netbuf *addr,
const struct netconfig *netconf); where
out
is the same as
out
passed to
rpc_broadcast(),
except that the remote procedure's output is decoded there;
addr
points to the address of the machine that sent the results, and
netconf
is the netconfig structure of the transport on which the remote
server responded.
If
eachresult()
returns
0,
rpc_broadcast()
waits for more replies; otherwise it returns with appropriate status. The broadcast file descriptors are limited in size to the
maximum transfer size of that transport.
For Ethernet, this value is 1500 bytes.
rpc_broadcast()
uses
AUTH_SYS
credentials by default (see
rpc_clnt_auth(3N)). - enum clnt_stat rpc_broadcast_exp()
Similar to
rpc_broadcast(),
except that the initial timeout,
inittime,
and the maximum timeout,
waittime,
are specified in milliseconds. inittime
is the initial time that
rpc_broadcast_exp()
waits before resending the request.
After the first resend, the re-transmission interval
increases exponentially until it exceeds
waittime. - enum clnt_stat rpc_call()
Calls the remote procedure associated with
prognum,
versnum,
and
procnum
on the machine,
host.
The parameter
inproc
is used to encode the procedure's parameters, and
outproc
is used to decode the procedure's results.
in
is the address of the procedure's argument(s), and
out
is the address of where to place the result(s).
nettype
can be any of the values listed on
rpc(3N).
This routine returns
RPC_SUCCESS
if it succeeds, or it returns an appropriate status.
Use the
clnt_perrno()
routine to translate failure status into error messages. The
rpc_call()
function uses the first available transport belonging to the class
nettype
on which it can create a connection.
You do not have control of timeouts or authentication
using this routine.
MULTITHREAD USAGE- Thread Safe:
Yes - Cancel Safe:
Yes - Fork Safe:
No - Async-cancel Safe:
No - Async-signal Safe:
No
These functions can be called safely in a multithreaded environment.
They may be cancellation points in that they call functions that are
cancel points. In a multithreaded environment, these functions are
not safe to be called by a child process after
fork()
and before
exec().
These functions should not be called by a multithreaded application
that supports asynchronous cancellation or asynchronous signals. |
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