xdr — library routines for external data representation
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.
bool_t 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 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
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.
bool_t 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.
bool_t 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
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.
bool_t 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
|
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.
bool_t 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.
bool_t xdr_enum( |
XDR * | xdrs, |
enum_t * | ep) ; |
A filter primitive that translates between C
enum
s
(actually integers) and their external
representations. This routine returns one if it
succeeds, zero otherwise.
bool_t xdr_float( |
XDR * | xdrs, |
float * | fp) ; |
A filter primitive that translates between C
float
s and
their external representations. This routine returns
one if it succeeds, zero otherwise.
void xdr_free( |
xdrproc_t | proc, |
char * | 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
|
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.
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 |
---|---|
|
bool_t 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.
bool_t 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.
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
determines the direction of the XDR stream (either
XDR_ENCODE
,
XDR_DECODE
, or
XDR_FREE
).
bool_t xdr_opaque( |
XDR * | xdrs, |
char * | cp, | |
u_int | cnt) ; |
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.
bool_t 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, | |
char * | 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
parameter.
![]() |
Note |
---|---|
The XDR stream's |
![]() |
Warning |
---|---|
This XDR stream implements an intermediate record stream. Therefore there are additional bytes in the stream to provide record boundary information. |
bool_t 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.
bool_t 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.
bool_t 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.
bool_t xdr_reference( |
XDR * | xdrs, |
char ** | pp, | |
u_int | size, | |
xdrproc_t | proc) ; |
A primitive that provides pointer chasing within
structures. The parameter pp
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 |
bool_t xdr_setpos( |
XDR * | xdrs, |
u_int | pos) ; |
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. |
bool_t 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.
void xdrstdio_create( |
XDR * | xdrs, |
FILE * | file, | |
enum xdr_op | op) ; |
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
parameter op
determines the
direction of the XDR stream (either XDR_ENCODE
, XDR_DECODE
, or XDR_FREE
).
bool_t 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 |
---|---|
|
bool_t 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.
bool_t 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.
bool_t 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.
bool_t 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.
bool_t xdr_union( |
XDR * | xdrs, |
int * | dscmp, | |
char * | unp, | |
struct xdr_discrim * | choices, | |
bool_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 parameter choices
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.
bool_t 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 parameter arrp
is the address
of the pointer to the array, while size
is is the
element count of the array. The parameter elsize
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.
bool_t xdr_void( |
void) ; |
This routine always returns one. It may be passed to RPC routines that require a function parameter, where nothing is to be done.
bool_t 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. 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.
The following manuals:
eXternal Data Representation Standard: Protocol Specification
eXternal Data Representation: Sun Technical Notes
XDR: External Data Representation Standard, RFC 1014, Sun Microsystems, Inc., USC-ISI.
|