xdr_union()--Translate between Unions and Their XDR

 #include <rpc/xdr.h>

 bool_t xdr_union(XDR *xdrs,
                  enum_t *dscmp,
                  char *unp,
                  const struct xdr_discrim *choices,
                  const xdrproc_t (*defaultarm));

The xdr_union() function is a filter primitive that translates between discriminated C unions and their corresponding external representations.

Parameters

xdrs  (Input) 

A pointer to the External Data Representation (XDR) stream handle.

dscmp  (Input) 

The address of the union's discriminant. The discriminant is an enumeration (enum_t) value.

unp  (I/O) 

The address of the union.

choices  (Input) 

A pointer to an array of xdr_discrim structures.

defaultarm  (Input) 

A structure provided in case no discriminants are found. This parameter can have a null value.

Authorities

No authorization is required.

Return Value

Error Conditions

None.

Error Messages

Usage Notes

The size of any enum data types passed to the xdr_union() must be defined as 4 bytes.

Example

The following example shows how xdr_union() is used.

Note: By using the code examples, you agree to the terms of the Code license and disclaimer information.

#include <stdio.h>
#include <xdr.h>

#pragma enum size(4)   /* Set enum size to 4 bytes */

typedef enum time_type {END=0,DC,CT} time_type ;

#pragma enum size()   /* Reset enum size */

typedef union time_value
{
        int   discrete_time;
        float continuous_time;
} time_value ;

typedef struct time
{
        time_type  type;
        time_value value;
} time;

bool_t xdr_time(XDR *xdrs, time *p_time)
{
        struct xdr_discrim handlers[] =
        {
                {DT,(xdrproc_t)xdr_int},
                {CT,(xdrproc_t)xdr_float},
                {END,NULL}
        };
        return
xdr_union(xdrs,(enum_t *)(&(p_time->type)),
(caddr_t)&(p_time->value),handlers,NULL);
}

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