Tribblix: manual page: xdr

XDR_ADMIN(3NSL) Networking Services Library Functions XDR_ADMIN(3NSL)

NAME

xdr_admin, xdr_control, xdr_getpos, xdr_inline, xdrrec_endofrecord,
xdrrec_eof, xdrrec_readbytes, xdrrec_skiprecord, xdr_setpos,
xdr_sizeof - library routines for external data representation

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 specifically with the management of the XDR
stream.

Routines

See rpc(3NSL) for the definition of the XDR data structure. Note that
any buffers passed to the XDR routines must be properly aligned. It
is suggested either that malloc(3C) be used to allocate these
buffers, or that the programmer insure that the buffer address is
divisible evenly by four.

#include <rpc/xdr.h>

bool_t xdr_control(XDR *xdrs, int req, void *info);

A function macro to change or retrieve various information about
an XDR stream. req indicates the type of operation and info is a
pointer to the information. The supported values of req is
XDR_GET_BYTES_AVAIL and its argument type is xdr_bytesrec *. They
return the number of bytes left unconsumed in the stream and a
flag indicating whether or not this is the last fragment.

uint_t xdr_getpos(const XDR *xdrs);

A macro that invokes the get-position routine associated with the
XDR stream, xdrs. The routine returns an unsigned integer, which
indicates the position of the XDR byte stream. A desirable
feature of XDR streams is that simple arithmetic works with this
number, although the XDR stream instances need not guarantee
this. Therefore, applications written for portability should not
depend on this feature.

rpc_inline_t *xdr_inline(XDR *xdrs, int len);

A macro that invokes the in-line routine associated with the XDR
stream, xdrs. The routine returns a pointer to a contiguous piece
of the stream's buffer; len is the byte length of the desired
buffer.

Warning: xdr_inline() may return NULL if it cannot allocate a
contiguous piece of a buffer. Therefore the behavior may vary
among stream instances; it exists for the sake of efficiency, and
applications written for portability should not depend on this
feature.

bool_t xdrrec_endofrecord(XDR *xdrs, bool_t sendnow);

This routine can be invoked only on streams created by
xdrrec_create(). See xdr_create(3NSL). The data in the output
buffer is marked as a completed record, and the output buffer is
optionally written out if sendnow is TRUE. This routine returns
TRUE if it succeeds, FALSE otherwise.

bool_t xdrrec_eof(XDR *xdrs);

This routine can be invoked only on streams created by
xdrrec_create(). After consuming the rest of the current record
in the stream, this routine returns TRUE if there is no more data
in the stream's input buffer. It returns FALSE if there is
additional data in the stream's input buffer.

uint_t xdrrec_readbytes(XDR *xdrs, caddr_t addr, uint_t nbytes);

This routine can be invoked only on streams created by
xdrrec_create(). It attempts to read nbytes bytes from the XDR
stream into the buffer pointed to by addr. Upon success this
routine returns the number of bytes read. Upon failure, it
returns -1. A return value of 0 indicates an end of record.

bool_t xdrrec_skiprecord(XDR *xdrs);

This routine can be invoked only on streams created by
xdrrec_create(). See xdr_create(3NSL). It tells the XDR
implementation that the rest of the current record in the
stream's input buffer should be discarded. This routine returns
TRUE if it succeeds, FALSE otherwise.

bool_t xdr_setpos(XDR *xdrs, const uint_t pos);

A macro that invokes the set position routine associated with the
XDR stream xdrs. The parameter pos is a position value obtained
from xdr_getpos(). This routine returns TRUE if the XDR stream
was repositioned, and FALSE otherwise.

Warning: it is difficult to reposition some types of XDR streams,
so this routine may fail with one type of stream and succeed with
another. Therefore, applications written for portability should
not depend on this feature.

uint_t xdr_sizeof(xdrproc_t func, void *data);

This routine returns the number of bytes required to encode data
using the XDR filter function func, excluding potential overhead
such as RPC headers or record markers. 0 is returned on error.
This information might be used to select between transport
protocols, or to determine the buffer size for various lower
levels of RPC client and server creation routines, or to allocate
storage when XDR is used outside of the RPC subsystem.

ATTRIBUTES

NAME

DESCRIPTION

Routines

ATTRIBUTES

SEE ALSO