The first two examples show how Remote Procedure Call (RPC) handles arbitrary data types.
struct simple { int a; short b; } simple;
callrpc(hostname, PROGNUM, VERSNUM, PROCNUM, xdr_simple, &simple ...);
The xdr_simple function is written as:
#include <rpc/rpc.h>
xdr_simple(xdrsp, simplep) XDR *xdrsp; struct simple *simplep; { if (!xdr_int(xdrsp, &simplep->a)) return (0); if (!xdr_short(xdrsp, &simplep->b)) return (0); return (1); }
struct varintarr { int *data; int arrlnth; } arr;
callrpc(hostname, PROGNUM, VERSNUM, PROCNUM, xdr_varintarr, &arr...);
The xdr_varintarr subroutine is defined as:
xdr_varintarr(xdrsp, arrp) XDR *xdrsp; struct varintarr *arrp; { return (xdr_array(xdrsp, &arrp->data, &arrp->arrlnth, MAXLEN, sizeof(int), xdr_int)); }
This routine's parameters are the eXternal Data Representation (XDR) handle (xdrsp ), a pointer to the array (aarp->data ), a pointer to the size of the array (aarp->arrlnth ), the maximum allowable array size (MAXLEN ), the size of each array element (sizeof ), and an XDR routine for handling each array element (xdr_int ).
If the size of the array is known in advance, the programmer can call the xdr_vector subroutine to serialize fixed-length arrays, as in the following example:
int intarr[SIZE];
xdr_intarr(xdrsp, intarr) XDR *xdrsp; int intarr[]; { int i;
return (xdr_vector(xdrsp, intarr, SIZE, sizeof(int), xdr_int)); }
The following example calls the previously written xdr_simple routine as well as the built-in xdr_string and xdr_reference functions. The xdr_reference routine chases pointers.
struct finalexample { char *string; struct simple *simplep; } finalexample;
xdr_finalexample(xdrsp, finalp) XDR *xdrsp; struct finalexample *finalp; {
if (!xdr_string(xdrsp, &finalp->string, MAXSTRLEN)) return (0); if (!xdr_reference(xdrsp, &finalp->simplep, sizeof(struct simple), xdr_simple); return (0); return (1); }