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XDR(3)		       FreeBSD Library Functions Manual			XDR(3)

NAME
     xdr, xdr_array, xdr_bool, xdr_bytes, xdr_char, xdr_destroy, xdr_double,
     xdr_enum, xdr_float, xdr_free, xdr_getpos,	xdr_hyper, xdr_inline,
     xdr_int, xdr_long,	xdr_longlong_t,	xdrmem_create, xdr_opaque,
     xdr_pointer, xdrrec_create, xdrrec_endofrecord, xdrrec_eof,
     xdrrec_skiprecord,	xdr_reference, xdr_setpos, xdr_short, xdrstdio_create,
     xdr_string, xdr_u_char, xdr_u_hyper, xdr_u_int, xdr_u_long,
     xdr_u_longlong_t, xdr_u_short, xdr_union, xdr_vector, xdr_void,
     xdr_wrapstring -- library routines	for external data representation

LIBRARY
     Standard C	Library	(libc, -lc)

SYNOPSIS
     #include <rpc/types.h>
     #include <rpc/xdr.h>

     See DESCRIPTION for function declarations.

DESCRIPTION
     These routines allow C programmers	to describe arbitrary data structures
     in	a machine-independent fashion.	Data for remote	procedure calls	are
     transmitted using these routines.

     int
     xdr_array(XDR *xdrs, char **arrp, u_int *sizep, u_int maxsize,
	     u_int elsize, xdrproc_t elproc)

	     A filter primitive	that translates	between	variable-length	arrays
	     and their corresponding external representations.	The arrp argu-
	     ment is the address of the	pointer	to the array, while sizep is
	     the address of the	element	count of the array; this element count
	     cannot exceed maxsize.  The elsize	argument is the	sizeof each of
	     the array's elements, and elproc is an XDR	filter that translates
	     between the array elements' C form, and their external represen-
	     tation.  This routine returns one if it succeeds, zero otherwise.

     int
     xdr_bool(XDR *xdrs, bool_t	*bp)

	     A filter primitive	that translates	between	booleans (C integers)
	     and their external	representations.  When encoding	data, this
	     filter produces values of either one or zero.  This routine
	     returns one if it succeeds, zero otherwise.

     int
     xdr_bytes(XDR *xdrs, char **sp, u_int *sizep, u_int maxsize)

	     A filter primitive	that translates	between	counted	byte strings
	     and their external	representations.  The sp argument is the
	     address of	the string pointer.  The length	of the string is
	     located at	address	sizep; strings cannot be longer	than maxsize.
	     This routine returns one if it succeeds, zero otherwise.

     int
     xdr_char(XDR *xdrs, char *cp)

	     A filter primitive	that translates	between	C characters and their
	     external representations.	This routine returns one if it suc-
	     ceeds, zero otherwise.  Note: encoded characters are not packed,
	     and occupy	4 bytes	each.  For arrays of characters, it is worth-
	     while to consider xdr_bytes(), xdr_opaque() or xdr_string().

     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.

     int
     xdr_double(XDR *xdrs, double *dp)

	     A filter primitive	that translates	between	C double precision
	     numbers and their external	representations.  This routine returns
	     one if it succeeds, zero otherwise.

     int
     xdr_enum(XDR *xdrs, enum_t	*ep)

	     A filter primitive	that translates	between	C enums	(actually
	     integers) and their external representations.  This routine
	     returns one if it succeeds, zero otherwise.

     int
     xdr_float(XDR *xdrs, float	*fp)

	     A filter primitive	that translates	between	C floats and their
	     external representations.	This routine returns one if it suc-
	     ceeds, zero otherwise.

     void
     xdr_free(xdrproc_t	proc, void *objp)

	     Generic freeing routine.  The first argument is the XDR routine
	     for the object being freed.  The second argument is a pointer to
	     the object	itself.	 Note: the pointer passed to this routine is
	     not freed,	but what it points to is freed (recursively).

     u_int
     xdr_getpos(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 fea-
	     ture of XDR streams is that simple	arithmetic works with this
	     number, although the XDR stream instances need not	guarantee
	     this.

     int
     xdr_hyper(XDR *xdrs, quad_t *llp)
	     A filter primitive	that translates	between	ANSI C long long inte-
	     gers and their external representations.  This routine returns
	     one if it succeeds, zero otherwise.

     long *
     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.  Note: pointer is cast to long *.

	     Warning: xdr_inline() may return NULL (0) 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.

     int
     xdr_int(XDR *xdrs,	int *ip)

	     A filter primitive	that translates	between	C integers and their
	     external representations.	This routine returns one if it suc-
	     ceeds, zero otherwise.

     int
     xdr_long(XDR *xdrs, long *lp)

	     A filter primitive	that translates	between	C long integers	and
	     their external representations.  This routine returns one if it
	     succeeds, zero otherwise.

     int
     xdr_longlong_t(XDR	*xdrs, quad_t *llp)
	     A filter primitive	that translates	between	ANSI C long long inte-
	     gers and their external representations.  This routine returns
	     one if it succeeds, zero otherwise.

     void
     xdrmem_create(XDR *xdrs, char *addr, u_int	size, 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 argument determines the direction of	the XDR	stream
	     (either XDR_ENCODE, XDR_DECODE, or	XDR_FREE).

     int
     xdr_opaque(XDR *xdrs, char	*cp, u_int cnt)

	     A filter primitive	that translates	between	fixed size opaque data
	     and its external representation.  The cp argument is the address
	     of	the opaque object, and cnt is its size in bytes.  This routine
	     returns one if it succeeds, zero otherwise.

     int
     xdr_pointer(XDR *xdrs, char **objpp, u_int	objsize, xdrproc_t xdrobj)

	     Like xdr_reference() except that it serializes NULL pointers,
	     whereas xdr_reference() does not.	Thus, xdr_pointer() can	repre-
	     sent recursive data structures, such as binary trees or linked
	     lists.

     void
     xdrrec_create(XDR *xdrs, u_int sendsize, u_int recvsize, void *handle,
	     int (*readit)(), int (*writeit)())

	     This routine initializes the XDR stream object pointed to by
	     xdrs.  The	stream's data is written to a buffer of	size sendsize;
	     a value of	zero indicates the system should use a suitable
	     default.  The stream's data is read from a	buffer of size
	     recvsize; it too can be set to a suitable default by passing a
	     zero 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	simi-
	     lar to the	system calls read(2) and write(2), except that handle
	     is	passed to the former routines as the first argument.  Note:
	     the XDR stream's op field must be set by the caller.

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

     int
     xdrrec_endofrecord(XDR *xdrs, int sendnow)

	     This routine can be invoked only on streams created by
	     xdrrec_create().  The data	in the output buffer is	marked as a
	     completed record, and the output buffer is	optionally written out
	     if	sendnow	is non-zero.  This routine returns one if it succeeds,
	     zero otherwise.

     int
     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 one if	the stream has no more
	     input, zero otherwise.

     int
     xdrrec_skiprecord(XDR *xdrs)

	     This routine can be invoked only on streams created by
	     xdrrec_create().  It tells	the XDR	implementation that the	rest
	     of	the current record in the stream's input buffer	should be dis-
	     carded.  This routine returns one if it succeeds, zero otherwise.

     int
     xdr_reference(XDR *xdrs, char **pp, u_int size, xdrproc_t proc)

	     A primitive that provides pointer chasing within structures.  The
	     pp	argument is the	address	of the pointer;	size is	the sizeof the
	     structure that *pp	points to; and proc is an XDR procedure	that
	     filters the structure between its C form and its external repre-
	     sentation.	 This routine returns one if it	succeeds, zero other-
	     wise.

	     Warning: this routine does	not understand NULL pointers.  Use
	     xdr_pointer() instead.

     int
     xdr_setpos(XDR *xdrs, u_int pos)

	     A macro that invokes the set position routine associated with the
	     XDR stream	xdrs.  The pos argument	is a position value obtained
	     from xdr_getpos().	 This routine returns one if the XDR stream
	     could be repositioned, and	zero 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.

     int
     xdr_short(XDR *xdrs, short	*sp)

	     A filter primitive	that translates	between	C short	integers and
	     their external representations.  This routine returns one if it
	     succeeds, zero otherwise.

     #ifdef _STDIO_H_
     /*	XDR using stdio	library	*/
     void
     xdrstdio_create(XDR *xdrs,	FILE *file, enum xdr_op	op)
     #endif

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

	     Warning: the destroy routine associated with such XDR streams
	     calls fflush(3) on	the file stream, but never fclose(3).

     int
     xdr_string(XDR *xdrs, char	**sp, u_int maxsize)

	     A filter primitive	that translates	between	C strings and their
	     corresponding external representations.  Strings cannot be	longer
	     than maxsize.  Note: sp is	the address of the string's pointer.
	     This routine returns one if it succeeds, zero otherwise.

     int
     xdr_u_char(XDR *xdrs, unsigned char *ucp)

	     A filter primitive	that translates	between	unsigned C characters
	     and their external	representations.  This routine returns one if
	     it	succeeds, zero otherwise.

     int
     xdr_u_hyper(XDR *xdrs, u_quad_t *ullp)
	     A filter primitive	that translates	between	unsigned ANSI C	long
	     long integers and their external representations.	This routine
	     returns one if it succeeds, zero otherwise.

     int
     xdr_u_int(XDR *xdrs, unsigned *up)

	     A filter primitive	that translates	between	C unsigned integers
	     and their external	representations.  This routine returns one if
	     it	succeeds, zero otherwise.

     int
     xdr_u_long(XDR *xdrs, unsigned long *ulp)

	     A filter primitive	that translates	between	C unsigned long	inte-
	     gers and their external representations.  This routine returns
	     one if it succeeds, zero otherwise.

     int
     xdr_u_longlong_t(XDR *xdrs, u_quad_t *ullp)
	     A filter primitive	that translates	between	unsigned ANSI C	long
	     long integers and their external representations.	This routine
	     returns one if it succeeds, zero otherwise.

     int
     xdr_u_short(XDR *xdrs, unsigned short *usp)

	     A filter primitive	that translates	between	C unsigned short inte-
	     gers and their external representations.  This routine returns
	     one if it succeeds, zero otherwise.

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

	     A filter primitive	that translates	between	a discriminated	C
	     union and its corresponding external representation.  It first
	     translates	the discriminant of the	union located at dscmp.	 This
	     discriminant is always an enum_t.	Next the union located at unp
	     is	translated.  The choices argument is a pointer to an array of
	     xdr_discrim structures.  Each structure contains an ordered pair
	     of	[value,	proc].	If the union's discriminant is equal to	the
	     associated	value, then the	proc() is called to translate the
	     union.  The end of	the xdr_discrim	structure array	is denoted by
	     a routine of value	NULL.  If the discriminant is not found	in the
	     choices array, then the defaultarm() procedure is called (if it
	     is	not NULL).  Returns one	if it succeeds,	zero otherwise.

     int
     xdr_vector(XDR *xdrs, char	*arrp, u_int size, u_int elsize,
	     xdrproc_t elproc)

	     A filter primitive	that translates	between	fixed-length arrays
	     and their corresponding external representations.	The arrp argu-
	     ment is the address of the	pointer	to the array, while size is
	     the element count of the array.  The elsize argument is the
	     sizeof each of the	array's	elements, and elproc is	an XDR filter
	     that translates between the array elements' C form, and their
	     external representation.  This routine returns one	if it suc-
	     ceeds, zero otherwise.

     int
     xdr_void(void)

	     This routine always returns one.  It may be passed	to RPC rou-
	     tines that	require	a function argument, where nothing is to be
	     done.

     int
     xdr_wrapstring(XDR	*xdrs, char **sp)

	     A primitive that calls xdr_string(xdrs, sp, MAXUN.UNSIGNED);
	     where MAXUN.UNSIGNED is the maximum value of an unsigned integer.
	     The xdr_wrapstring() function is handy because the	RPC package
	     passes a maximum of two XDR routines as arguments,	and
	     xdr_string(), one of the most frequently used primitives,
	     requires three.  Returns one if it	succeeds, zero otherwise.

SEE ALSO
     rpc(3)

     eXternal Data Representation Standard: Protocol Specification.

     eXternal Data Representation: Sun Technical Notes.

     XDR: External Data	Representation Standard, Sun Microsystems, Inc.,
     USC-ISI, RFC1014.

FreeBSD	9.2		       February	16, 1988		   FreeBSD 9.2

NAME | LIBRARY | SYNOPSIS | DESCRIPTION | SEE ALSO

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