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XDR(3) |
FreeBSD Library Functions Manual |
XDR(3) |
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
Standard C Library (libc, -lc)
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.
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.
The xdr_sizeof function first appeared in
FreeBSD 9.0.
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