NAME
xdr_array,
xdr_bool, xdr_bytes,
xdr_char, xdr_destroy,
xdr_double, xdr_enum,
xdr_float, xdr_free,
xdr_getpos, xdr_inline,
xdr_int, xdr_long,
xdr_int64_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_int, xdr_u_long,
xdr_u_int64_t, xdr_u_short,
xdr_union, xdr_vector,
xdr_void, xdr_wrapstring
— library routines for external
data representation
SYNOPSIS
#include
<sys/types.h>
#include <rpc/xdr.h>
int
xdr_array(XDR
*xdrs, char **arrp,
u_int *sizep,
u_int maxsize,
u_int elsize,
xdrproc_t elproc);
int
xdr_bool(XDR
*xdrs, bool_t
*bp);
int
xdr_bytes(XDR
*xdrs, char **sp,
u_int *sizep,
u_int maxsize);
int
xdr_char(XDR
*xdrs, char
*cp);
void
xdr_destroy(XDR
*xdrs);
int
xdr_double(XDR
*xdrs, double
*dp);
int
xdr_enum(XDR
*xdrs, enum_t
*ep);
int
xdr_float(XDR
*xdrs, float
*fp);
void
xdr_free(xdrproc_t
proc, char
*objp);
u_int
xdr_getpos(XDR
*xdrs);
long *
xdr_inline(XDR
*xdrs, int
len);
int
xdr_int(XDR
*xdrs, int
*ip);
int
xdr_long(XDR
*xdrs, long
*lp);
int
xdr_int64_t(XDR
*xdrs, int64_t
*lp);
void
xdrmem_create(XDR
*xdrs, char *addr,
u_int size,
enum xdr_op op);
int
xdr_opaque(XDR
*xdrs, char *cp,
u_int cnt);
int
xdr_pointer(XDR
*xdrs, char
**objpp, u_int
objsize, xdrproc_t
xdrobj);
void
xdrrec_create(XDR
*xdrs, u_int
sendsize, u_int
recvsize, char
*handle, int
(*readit)(), int
(*writeit)());
int
xdrrec_endofrecord(XDR
*xdrs, int
sendnow);
int
xdrrec_eof(XDR
*xdrs);
int
xdrrec_skiprecord(XDR
*xdrs);
int
xdr_reference(XDR
*xdrs, char **pp,
u_int size,
xdrproc_t proc);
int
xdr_setpos(XDR
*xdrs, u_int
pos);
int
xdr_short(XDR
*xdrs, short
*sp);
void
xdrstdio_create(XDR
*xdrs, FILE *file,
enum xdr_op op);
int
xdr_string(XDR
*xdrs, char **sp,
u_int maxsize);
int
xdr_u_char(XDR
*xdrs, unsigned char
*ucp);
int
xdr_u_int(XDR
*xdrs, unsigned int
*up);
int
xdr_u_long(XDR
*xdrs, unsigned long
*ulp);
int
xdr_u_int64_t(XDR
*xdrs, u_int64_t
*ullp);
int
xdr_u_short(XDR
*xdrs, unsigned short
*usp);
int
xdr_union(XDR
*xdrs, int *dscmp,
char *unp,
struct xdr_discrim
*choices, bool_t
(*defaultarm)());
int
xdr_vector(XDR
*xdrs, char *arrp,
u_int size,
u_int elsize,
xdrproc_t elproc);
int
xdr_void(void);
int
xdr_wrapstring(XDR
*xdrs, char
**sp);
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.
xdr_array()
is a filter primitive that translates between variable-length arrays and
their corresponding external representations. The parameter
arrp 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
parameter elsize is the size of 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.
xdr_bool()
is 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.
xdr_bytes()
is a filter primitive that translates between counted byte strings and their
external representations. The parameter sp 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.
xdr_char()
is 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().
xdr_destroy()
is 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.
xdr_double()
is a filter primitive that translates between C
double precision numbers and their external
representations. This routine returns one if it succeeds, zero
otherwise.
xdr_enum()
is a filter primitive that translates between the C
enum type (actually an integer) and its external
representations. This routine returns one if it succeeds, zero
otherwise.
xdr_float()
is a filter primitive that translates between the C
float type and its external representations. This
routine returns one if it succeeds, zero otherwise.
xdr_free()
is a 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).
xdr_getpos()
is 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.
xdr_inline()
is 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 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.
xdr_int()
is a filter primitive that translates between C integers and their external
representations. This routine returns one if it succeeds, zero
otherwise.
xdr_long()
is a filter primitive that translates between C long
integers and their external representations. This routine returns one if it
succeeds, zero otherwise.
xdr_int64_t()
is a filter primitive that translates between C
int64_t integers and their external representations.
This routine returns one if it succeeds, zero otherwise.
xdrmem_create()
is a routine which 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 determines the direction of the XDR stream (either
XDR_ENCODE, XDR_DECODE, or
XDR_FREE).
xdr_opaque()
is a filter primitive that translates between fixed size opaque data and its
external representation. The parameter cp is the
address of the opaque object, and cnt is its size in
bytes. This routine returns one if it succeeds, zero otherwise.
xdr_pointer()
is 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.
xdrrec_create()
is a routine which 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()
and
write(),
except that handle is passed to the former routines as
the first parameter. 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.
xdrrec_endofrecord()
is a routine which 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.
xdrrec_eof()
is a routine which 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.
xdrrec_skiprecord()
is a routine which 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.
xdr_reference()
is a primitive that provides pointer chasing within structures. The
parameter pp is the address of the pointer;
size is the size of 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.
xdr_setpos()
is a macro that invokes the set position routine associated with the XDR
stream xdrs. The parameter pos
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.
xdr_short()
is a filter primitive that translates between C
short integers and their external representations.
This routine returns one if it succeeds, zero otherwise.
xdrstdio_create()
is a routine which 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 parameter
op 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()
on the file stream, but never
fclose().
xdr_string()
is 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.
xdr_u_char()
is a filter primitive that translates between
unsigned C characters and their external
representations. This routine returns one if it succeeds, zero
otherwise.
xdr_u_int()
is a filter primitive that translates between C
unsigned integers and their external
representations. This routine returns one if it succeeds, zero
otherwise.
xdr_u_long()
is a filter primitive that translates between C unsigned
long integers and their external representations. This routine
returns one if it succeeds, zero otherwise.
xdr_u_int64_t()
is a filter primitive that translates between C
u_int64_t integers and their external
representations. This routine returns one if it succeeds, zero
otherwise.
xdr_u_short()
is a filter primitive that translates between C unsigned
short integers and their external representations. This routine
returns one if it succeeds, zero otherwise.
xdr_union()
is 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 parameter
choices is a pointer to an array of
struct 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 struct
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.
xdr_vector()
is a filter primitive that translates between fixed-length arrays and their
corresponding external representations. The parameter
arrp is the address of the pointer to the array, while
size is the element count of the array. The parameter
elsize is the size of 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.
xdr_void()
is a routine which always returns one. It may be passed to RPC routines that
require a function parameter, but where nothing is to be done.
xdr_wrapstring()
is a primitive that calls
xdr_string(xdrs,
sp, MAXUN.UNSIGNED) where
MAXUN.UNSIGNED is the maximum value of an unsigned
integer. xdr_wrapstring() is handy because the RPC
package passes a maximum of two XDR routines as parameters, and
xdr_string(), one of the most frequently used
primitives, requires three. Returns one if it succeeds, zero otherwise.
SEE ALSO
eXternal Data Representation Standard: Protocol Specification.
eXternal Data Representation: Sun Technical Notes.
STANDARDS
XDR: External Data Representation Standard, RFC 1014, Sun Microsystems, Inc., June 1987.