xdr, xdr_array, xdr_bool, xdr_bytes, xdr_char,
xdr_destroy, xdr_double, xdr_enum, xdr_float, xdr_free,
xdr_functions, xdr_getpos, xdr_hyper, xdr_inline, xdr_int,
xdr_long, xdr_longlong_t, xdr_opaque, xdr_pmap,
xdr_pmaplist, xdr_pointer, xdr_reference, xdr_setpos,
xdr_short, 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, xdrmem_create, xdrrec_create,
xdrrec_endofrecord, xdrrec_eof, xdrrec_skiprecord,
xdrstdio_create - library routines for external data
representation
#include <rpc/xdr.h>
xdr_array(
XDR *xdrs,
char **arrp,
u_int *sizep,
u_int *maxsize,
u_int *elsize,
xdrproc_t elproc ); xdr_bool(
XDR *xdrs,
bool_t bp ); xdr_bytes(
XDR *xdrs,
char **sp,
u_int *sizep,
u_int maxsize ); xdr_char(
XDR *xdrs,
char*cp ); void xdr_destroy(
XDR *xdrs ); xdr_double(
XDR *xdrs,
double *dp ); xdr_enum(
XDR *xdrs,
enum_t *ep ); xdr_float(
XDR *xdrs,
float *fp ); void xdr_free(
xdrproc_t proc,
char *objp ); u_int xdr_getpos(
XDR *xdrs ); xdr_hyper(
XDR *xdrs,
longlong_t *hp ); long *xdr_inline(
XDR *xdrs,
int len ); xdr_int(
XDR *xdrs,
int *ip ); xdr_long(
XDR *xdrs,
long *lp ); xdr_longlong_t(
XDR *xdrs,
longlong_t *hp ); xdr_opaque(
XDR *xdrs,
char *cp,
u_int cnt ); xdr_pmap(
XDR *xdrs,
struct pmap *regs ); xdr_pmaplist(
XDR *xdrs,
struct pmaplist **rp ); xdr_pointer(
XDR *xdrs,
char **objpp,
u_int objsize,
xdrproc_t xdrobj ); xdr_reference(
XDR *xdrs,
char **pp,
u_int size,
xdrproc_t proc ); xdr_setpos(
XDR *xdrs,
u_int pos ); xdr_short(
XDR *xdrs,
short *sp ); xdr_string(
XDR *xdrs,
char **sp,
u_int maxsize ); xdr_u_char(
XDR *xdrs,
unsigned char *ucp ); xdr_u_hyper(
XDR *xdrs,
u_longlong_t *uhp ); xdr_u_int(
XDR *xdrs,
unsigned *up ); xdr_u_long(
XDR *xdrs,
unsigned long *ulp ); xdr_u_longlong_t(
XDR *xdrs,
u_longlong_t *uhp ); xdr_u_short(
XDR *xdrs,
unsigned short *usp ); xdr_union(
XDR *xdrs,
int *dscmp,
char *unp,
struct xdr_discrim *choices,
bool_t (*defaultarm) (void) ); xdr_vector(
XDR *xdrs,
char *arrp,
u_int size,
u_int elsize,
xdrproc_t elproc ); xdr_void(
void ); xdr_wrapstring(
XDR *xdrs,
char **sp ); void xdrmem_create(
XDR *xdrs,
char *addr,
u_int size,
enum xdr_op op ); void xdrrec_create(
XDR *xdrs,
u_int sendsize,
u_int recvsize,
char *handle,
int (*readit) (void),
int (*writeit) (void) ); xdrrec_endofrecord(
XDR *xdrs,
int sendnow ); xdrrec_eof(
XDR *xdrs,
int empty ); xdrrec_skiprecord(
XDR *xdrs ); void xdrstdio_create(
XDR *xdrs,
FILE *file,
enum xdr_op op );
These routines allow C programmers to describe arbitrary
data structures in a machine-independent fashion. Data for
ONC remote procedure calls are transmitted using the following
routines:
A filter primitive that translates between variable-length
arrays and their corresponding external representations.
The arrp parameter 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 parameter is the sizeof 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 (1) if it succeeds, zero
(0) otherwise. A filter primitive that translates between
Booleans (C integers) and their external representations.
When encoding data, this filter produces values of either
one (1) or zero (0). This routine returns one (1) if it
succeeds, zero (0) otherwise. A filter primitive that
translates between counted byte strings and their external
representations. The sp parameter 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 (1) if it succeeds, zero (0) otherwise.
A filter primitive that translates between C characters
and their external representations. This routine
returns one (1) if it succeeds, zero (0) 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(). 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. A filter primitive
that translates between C double-precision numbers
and their external representations. This routine returns
one (1) if it succeeds, zero (0) otherwise. A filter
primitive that translates between C enums (actually integers)
and their external representations. This routine
returns one (1) if it succeeds, zero (0) otherwise. A
filter primitive that translates between C floats and
their external representations. This routine returns one
(1) if it succeeds, zero (0) otherwise. 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).
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. A filter
primitive that translates between C long integers and
their external representations. (The typedef longlong_t is
defined as long in the <rpc/types.h> file, which is
included from the <rpc/xdr.h> file.) This routine will
translate all 8 bytes of data to the XDR stream. Note that
this differentiates this routine from xdr_long() in that
they both take a pointer to a long as an argument, while
xdr_long() only translates 4 bytes of data to the XDR
stream. This routine returns one (1) if it succeeds, zero
(0) otherwise.
The xdr_hyper() routine is functionally equivalent
to the xdr_longlong_t() routine.
See the next section for an explanation of the differences
betweenxdr_long() and xdr_hyper(). 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. A filter primitive
that translates between C integers and their
external representations. This routine returns one
(1) if it succeeds, zero (0) otherwise. A filter
primitive that translates between C long integers
and their external representations. This routine
returns one (1) if it succeeds, zero (0) otherwise.
Note that the lp argument must be the C type long.
The amount of data encoded to the XDR stream is
only 4 bytes (not the full 8 bytes of data represented
by the C long type). This is because a long
type is considered to be 4 bytes in the context of
XDR streams. When data is encoded from the XDR
stream, 4 bytes will be received from the XDR
stream; the xdr_long() interface then sign extends
the high-order 4 bytes of the C long type.
Prior to serializing the data on the ENCODE side,
xdr_long() performs a validity check to ensure that
the value represents a valid 32-bit signed number.
This involves determining that the signed value is
no less than the most negative 32-bit signed quantity
(which is the hexadecimal value 0x80000000)
and no greater than the most positive 32-bit signed
quantity (which is the hexadecimal value
0x7fffffff). If the value pointed to by the lp
argument is not within this range, the xdr_long()
interface returns an error.
To translate the full 8 bytes of a C long, use the
xdr_hyper() interface.
See the next section for an explanation of the differences
between xdr_long() and xdr_hyper(). A
filter primitive that translates between C long
integers and their external representations. (The
typedef longlong_t is defined as long in the
<rpc/types.h> file, which is included from the
<rpc/xdr.h> file.) This routine will translate all
8 bytes of data to the XDR stream. Note that this
differentiates this routine from xdr_long() in that
they both take a pointer to a long as an argument,
while xdr_long() only translates 4 bytes of data to
the XDR stream. This routine returns one (1) if it
succeeds, zero (0) otherwise.
The xdr_longlong_t() routine is functionally equivalent
to the xdr_hyper() routine.
See the next section for an explanation of the differences
between xdr_long() and xdr_hyper(). A
filter primitive that translates between fixed size
opaque data and its external representation. The
cp parameter is the address of the opaque object,
and cnt is its size in bytes. This routine returns
one (1) if it succeeds, zero (0) otherwise. Used
for describing parameters to various portmap procedures,
externally. This routine is useful for users
who wish to generate these parameters without using
the pmap interface. Used for describing a list of
port mappings, externally. This routine is useful
for users who wish to generate these parameters
without using the pmap interface. 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. A
primitive that provides pointer chasing within
structures. The pp parameter is the address of the
pointer; size is the sizeof 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
(1) if it succeeds, zero (0) otherwise.
Warning: This routine does not understand NULL
pointers. Use xdr_pointer() instead. A macro that
invokes the set position routine associated with
the XDR stream, xdrs. The pos parameter is a position
value obtained from xdr_getpos(). This routine
returns one (1) if the XDR stream could be repositioned,
and zero (0) 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. A filter
primitive that translates between C short integers
and their external representations. This routine
returns one (1) if it succeeds, zero (0) otherwise.
A filter primitive that translates between C
strings and their corresponding external representations.
Strings cannot be longer than maxsize.
The sp parameter is the address of the string's
pointer. While encoding, if sp is NULL, an error is
returned. While decoding, if *sp is NULL, the necessary
storage is allocated to hold this null-terminated
string and *sp is set to point to this.
This storage can be freed by using xdr_free(). This
routine returns one (1) if it succeeds, zero (0)
otherwise. A filter primitive that translates
between unsigned C characters and their external
representations. This routine returns one (1) if
it succeeds, zero (0) otherwise. A filter primitive
that translates between C unsigned long integers
and their external representations. (The typedef
u_longlong_t is defined as unsigned long in the
<rpc/types.h> file, which is included from the
<rpc/xdr.h> file.) This routine will translate all
8 bytes of data to the XDR stream. Note that this
differentiates this routine from xdr_u_long() in
that they both take a pointer to an unsigned long
as an argument, while xdr_u_long() only translates
4 bytes of data to the XDR stream. This routine
returns one (1) if it succeeds, zero (0) otherwise.
The xdr_u_hyper() routine is functionally equivalent
to the xdr_u_longlong_t() routine.
See the next section for an explanation of the differences
between xdr_long() and xdr_hyper(). A
filter primitive that translates between C unsigned
integers and their external representations. This
routine returns one (1) if it succeeds, zero (0)
otherwise. A filter primitive that translates
between C unsigned long integers and their external
representations. This routine returns one (1) if it
succeeds, zero (0) otherwise.
Prior to serializing the data on the ENCODE side,
xdr_u_long() performs a validity check to insure
that the value represents a valid 32-bit unsigned
number. This involves determining that the unsigned
value is no greater than the largest 32-bit
unsigned quantity (which is the hexadecimal value
0xffffffff). If the value pointed to by the ulp
argument is not within this range, the xdr_u_long()
interface returns an error.
For DECODE operations, the 32-bit unsigned value is
sign extended into the 64-bit unsigned long
referred to by the ulp argument.
Note that this routine actually translates 4 bytes
of the data to or from the XDR stream. Refer to the
description of xdr_long() for a more detailed
explanation. A filter primitive that translates
between C unsigned long integers and their external
representations. (The typedef u_longlong_t is
defined as unsigned long in the <rpc/types.h> file,
which is included from the <rpc/xdr.h> file.) This
routine will translate all 8 bytes of data to the
XDR stream. Note that this differentiates this
routine from xdr_u_long() in that they both take a
pointer to an unsigned long as an argument, while
xdr_u_long() only translates 4 bytes of data to the
XDR stream. This routine returns one (1) if it succeeds,
zero (0) otherwise.
The xdr_u_longlong routine is functionally equivalent
to the xdr_u_hyper() routine.
See the next section for an explanation of the differences
between xdr_long() and xdr_hyper(). A
filter primitive that translates between C unsigned
short integers and their external representations.
This routine returns one (1) if it succeeds, zero
(0) otherwise. 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
parameter 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 any of the values, the associated proc is
called to translate the union. The end of the
xdr_discrim structure array is denoted by a NULL
pointer. If the discriminant is not found in the
choices array, then the defaultarm procedure is
called (if it is not NULL). Returns one (1) if it
succeeds, zero (0) otherwise. A filter primitive
that translates between fixed-length arrays and
their corresponding external representations. The
arrp parameter is the address of the array, while
size is the element count of the array. The elsize
parameter is the sizeof 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 (1) if
it succeeds, zero (0) otherwise. This routine
always returns one (1). It may be passed to RPC
routines that require a function parameter, but
where nothing is to be done. A primitive that
calls xdr_string(xdrs,sp,MAXUNSIGNED); where
MAXUNSIGNED is the maximum value of an unsigned
integer. The xdr_wrapstring() primitive 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. The sp parameter is the address of the
pointer to the string. While decoding, if sp is
NULL, the necessary storage is allocated to hold
the null-terminated string and sp is set to point
to this. This storage can be freed by using
xdr_free(). Returns one (1) if it succeeds, zero
(0) otherwise. 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). 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 (0) 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 (0) 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. The XDR stream's
op field must be set by the caller. The sendsize
and recvsize parameters should be multiples of 4.
Warning: This XDR stream implements an intermediate
record stream. Therefore there are additional bytes
in the stream to provide record boundary information.
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 nonzero. This routine returns one (1) if it succeeds,
zero (0) otherwise. 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 (1) if the
stream has no more input, zero (0) otherwise. 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 (1) if it succeeds, zero (0) otherwise.
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 parameter 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().
Differences Between xdr_long and xdr_hyper Routines [Toc] [Back]
On Tru64 UNIX platforms, the C programming language and
the XDR routines apply different conventions to the definitions
of the long data type.
On Tru64 UNIX platforms, the C programming language
applies the following conventions for int and long data
types:
---------------------------
Data Type bits bytes
---------------------------
int 32 4 bytes
long 64 8 bytes
---------------------------
The XDR routines apply the following conventions:
---------------------------
Data Type bits bytes
---------------------------
int 32 4 bytes
long 32 4 bytes
hyper 64 8 bytes
---------------------------
The xdr_long() and xdr_u_long() interfaces serialize 4
bytes of data. The xdr_hyper() and xdr_u_hyper() interfaces
serialize 8 bytes of data.
On Tru64 UNIX systems, the second argument to both
xdr_long() and xdr_hyper() must be either a pointer or of
the C language type long (8 bytes). When xdr_hyper() is
called with a parameter that points to a long, all 8 bytes
are serialized. In contrast, when xdr_long() is called
with a parameter that points to a long, only the low-order
4 bytes are serialized.
When calling xdr_long() on the DECODE operation, the upper
4 bytes of the long are sign extended in accordance with
the high-order bit of the lower 4-byte quantity. This is
necessary to maintain the XDR convention of xdr_long()
serializing 4 bytes.
If you want all 8 bytes to be serialized, use the
xdr_hyper() interface.
The xdr_longlong_t() and xdr_u_longlong_t() interfaces
perform the same function as the xdr_hyper() and the
xdr_u_hyper() interfaces, respectively.
Routines: rpc(3), rpc_clnt(3), rpc_misc(3), rpc_svc(3),
rpc_xdr(3)
xdr(3)
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