xdr_create(S)

xdr_create: xdr_destroy, xdrmem_create, xdrrec_create, xdrstdio_create -- library routines for external data representation stream creation

Synopsis

cc [options] file -lnsl

#include <rpc/xdr.h>

void xdr_destroy(XDR *xdrs);

void xdrmem_create(XDR *xdrs, const caddr_t addr, const u_int size,
	const enum xdr_op op);

void xdrrec_create(XDR *xdrs, const u_int sendsz, const u_int recvsz,
	const caddr_t handle, const int (*readit)(const void *,
	char *, const int), const int (*writeit)(const void *,
	const char *, const int));

void xdrstdio_create(XDR *xdrs, FILE *file, const enum xdr_op op);

Description

XDR library routines allow C programmers to describe arbitrary data structures in a machine-independent fashion. Protocols such as remote procedure calls (RPC) use these routines to describe the format of the data.

These routines deal with the creation of XDR streams. XDR streams have to be created before any data can be translated into XDR format.

Routines

See rpc(NS) for the definition of the XDR, CLIENT, and SVCXPRT data structures.

void
xdr_destroy(XDR *xdrs);

A macro that invokes the destroy routine associated with the XDR stream, xdrs. Destruction usually involves freeing private data structures associated with the stream. Using xdrs after invoking xdr_destroy is undefined.

void
xdrmem_create(XDR *xdrs, const caddr_t addr, const u_int size,
	const enum xdr_op op);

This routine initializes the XDR stream object pointed to by xdrs. The stream's data is written to, or read from, a chunk of memory at location addr whose length is no more than size bytes long. The op determines the direction of the XDR stream (one of XDR_ENCODE, XDR_DECODE, or XDR_FREE).

void
xdrrec_create(XDR *xdrs, const u_int sendsz, const u_int recvsz,
	const caddr_t handle, const int (*readit)(const void *,
	char *, const int), const int (*writeit)(const void *,
	const char *, const int));

This routine initializes the XDR stream object pointed to by xdrs. The stream's data is written to a buffer of size sendsz; a value of 0 indicates the system should use a suitable default. The stream's data is read from a buffer of size recvsz; it too can be set to a suitable default by passing a 0 value. When a stream's output buffer is full, writeit is called. Similarly, when a stream's input buffer is empty, readit is called. The behavior of these two routines is similar to the system calls read(S) and write(S) respectively, except that handle (CLIENT, or SVCXPRT) is passed to the former routines as the first parameter instead of a file descriptor. Note: the XDR stream's op field must be set by the caller.

Note: this XDR stream implements an intermediate record stream. Therefore there are additional bytes in the stream to provide record boundary information.

void
xdrstdio_create(XDR *xdrs, FILE *file, const enum xdr_op op);

This routine initializes the XDR stream object pointed to by xdrs. The XDR stream data is written to, or read from, the standard I/O stream file. The parameter op determines the direction of the XDR stream (either XDR_ENCODE, XDR_DECODE, or XDR_FREE).

Note: the destroy routine associated with such XDR streams calls fflush on the file stream, but never fclose(S).

References

fclose(S), read(S), rpc(NS), write(S), xdr_admin(NS), xdr_complex(NS), xdr_simple(NS)