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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, xdr_sizeof,
     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
             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 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
             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 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
             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 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
             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 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
             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 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
             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 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
             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 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
             discarded.  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.

     unsigned long
     xdr_sizeof(xdrproc_t func, void *data)

             This routine returns the amount of memory required to encode data
             using filter func.

     #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
             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
             integers 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
             integers 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
             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 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_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 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.

HISTORY
     The xdr_sizeof function first appeared in FreeBSD 9.0.

FreeBSD 11.0-PRERELEASE        February 16, 1988       FreeBSD 11.0-PRERELEASE

NAME | LIBRARY | SYNOPSIS | DESCRIPTION | SEE ALSO | HISTORY

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