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XDR(3)                   BSD 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 fash-ion. fashion.
     ion.  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 argument 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 representation.
             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 representa-tions. representations.
             tions.  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 representa-tions. representations.
             tions.  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 succeeds, zero otherwise.  Note: encoded characters are not
             packed, and occupy 4 bytes each.  For arrays of characters, it is worthwhile 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 repre-sentations. representations.
             sentations.  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 rep-resentations. representations.
             resentations.  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 succeeds, 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 rou-tine routine
             tine 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 rou-tine routine
             tine 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.

     int
     xdr_hyper(XDR *xdrs, quad_t *llp)
             A filter primitive that translates between ANSI C long long integers and their external repre-sentations. representations.
             sentations.  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 succeeds, 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 integers and their external repre-sentations. representations.
             sentations.  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 writ-ten written
             ten 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 representa-tion. representation.
             tion.  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 represent 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 writ-ten written
             ten 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 similar 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 addi-tional additional
             tional 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. discarded.
             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 representation.  This routine
             returns one if it succeeds, zero otherwise.

             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 Standard I/O stream file.  The op argument determines the direc-tion direction
             tion 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 represen-tations. representations.
             tations.  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 representa-tions. representations.
             tions.  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 exter-nal external
             nal 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 representa-tions. representations.
             tions.  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 integers and their external repre-sentations. representations.
             sentations.  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 exter-nal external
             nal 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 integers and their external repre-sentations. representations.
             sentations.  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 exter-nal external
             nal 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 argument 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 ele-ments, elements,
             ments, and elproc is an XDR filter that translates between the array elements' C form, and
             their external representation.  This routine returns one if it succeeds, zero otherwise.

     int
     xdr_void(void)

             This routine always returns one.  It may be passed to RPC routines 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 maxi-mum maximum
             mum value of an unsigned integer.  The xdr_wrapstring() function is handy because the RPC pack-age package
             age passes a maximum of two XDR routines as arguments, and xdr_string(), one of the most fre-quently frequently
             quently 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.

BSD                            February 16, 1988                           BSD

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