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Man page of xdr
xdr
Section: C Library Functions (3)
Index
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NAME
xdr, xdr_accepted_reply, xdr_array, xdr_authunix_parms, xdr_bool, xdr_bytes, xdr_callhdr, xdr_callmsg, 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, xdrmem_create, xdr_opaque, xdr_opaque_auth, xdr_pmap, xdr_pmaplist, xdr_pointer, xdrrec_create, xdrrec_endofrecord, xdrrec_eof, xdrrec_skiprecord, xdr_reference, xdr_rejected_reply, xdr_replymsg, xdr_setpos, xdr_short, 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
SYNOPSIS
#include <rpc/xdr.h>
xdr_accepted_reply(xdrs, ar)
XDR *xdrs;
struct accepted_reply *ar;
-
Used for encoding
RPC
reply messages. This routine is useful for users who
wish to generate
RPC-style
messages without using the
RPC
package.
xdr_array(xdrs, arrp, sizep, maxsize, elsize, elproc)
XDR *xdrs;
char **arrp;
u_int *sizep, maxsize, elsize;
xdrproc_t elproc;
-
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
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.
xdr_authunix_parms(xdrs, aupp)
XDR *xdrs;
struct authunix_parms *aupp;
-
Used for describing
UNIX
credentials. This routine is useful for users
who wish to generate these credentials without using the
RPC
authentication package.
xdr_bool(xdrs, bp)
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 (1) or zero (0).
This routine returns one (1) if it succeeds, zero (0) otherwise.
xdr_bytes(xdrs, sp, sizep, maxsize)
XDR *xdrs;
char **sp;
u_int *sizep, maxsize;
-
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.
void
xdr_callhdr(xdrs, chdr)
XDR *xdrs;
struct rpc_msg *chdr;
-
Used for describing
RPC
call header messages.
This routine is useful for users who wish to generate
RPC-style
messages without using the
RPC
package.
xdr_callmsg(xdrs, cmsg)
XDR *xdrs;
struct rpc_msg *cmsg;
-
Used for describing
RPC
call messages.
This routine is useful for users who wish to generate
RPC-style
messages without using the
RPC
package.
xdr_char(xdrs, cp)
XDR *xdrs;
char *cp;
-
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().
void
xdr_destroy(xdrs)
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.
xdr_double(xdrs, dp)
XDR *xdrs;
double *dp;
-
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.
xdr_enum(xdrs, ep)
XDR *xdrs;
enum_t *ep;
-
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.
xdr_float(xdrs, fp)
XDR *xdrs;
float *fp;
-
A filter primitive that translates between C
floats
and their external representations.
This routine returns one (1) if it succeeds, zero (0) otherwise.
void
xdr_free(proc, objp)
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 not freed, but what it points to is
freed (recursively).
u_int
xdr_getpos(xdrs)
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.
xdr_hyper(xdrs, hp)
XDR *xdrs;
longlong_t *hp;
-
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 following section that explains the differences between
xdr_long and xdr_hyper.
long *
xdr_inline(xdrs, len)
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
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(xdrs, ip)
XDR *xdrs;
int *ip;
-
A filter primitive that translates between C integers
and their external representations.
This routine returns one (1) if it succeeds, zero (0) otherwise.
xdr_long(xdrs, lp)
XDR *xdrs;
long *lp;
-
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 language 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 in the context of
XDR
streams a long
type is considered to be 4 bytes. 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 the 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 following section that explains the differences between
xdr_long and xdr_hyper.
xdr_longlong_t(xdrs, hp)
XDR *xdrs;
longlong_t *hp;
-
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 following section that explains the differences between
xdr_long and xdr_hyper.
void
xdrmem_create(xdrs, addr, size, op)
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).
xdr_opaque(xdrs, cp, cnt)
XDR *xdrs;
char *cp;
u_int cnt;
-
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.
xdr_opaque_auth(xdrs, ap)
XDR *xdrs;
struct opaque_auth *ap;
-
Used for describing
RPC
authentication information messages.
This routine is useful for users who wish to generate
RPC-style
messages without using the
RPC
package.
xdr_pmap(xdrs, regs)
XDR *xdrs;
struct pmap *regs;
-
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.
xdr_pmaplist(xdrs, rp)
XDR *xdrs;
struct pmaplist **rp;
-
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.
xdr_pointer(xdrs, objpp, objsize, xdrobj)
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(xdrs, sendsize, recvsize, handle, readit, writeit)
XDR *xdrs;
u_int sendsize, recvsize;
char *handle;
int (*readit) (), (*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 (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.
xdrrec_endofrecord(xdrs, sendnow)
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 (1) if it succeeds, zero (0)
otherwise.
xdrrec_eof(xdrs)
XDR *xdrs;
int empty;
-
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.
xdrrec_skiprecord(xdrs)
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 (1) if it succeeds, zero (0) otherwise.
xdr_reference(xdrs, pp, size, proc)
XDR *xdrs;
char **pp;
u_int size;
xdrproc_t proc;
-
A primitive that provides pointer chasing within structures.
The pp parameter
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 (1) if it succeeds, zero (0) otherwise.
-
Warning: this routine does not understand
NULL
pointers. Use
xdr_pointer()
instead.
xdr_rejected_reply(xdrs, rr)
XDR *xdrs;
struct rejected_reply *rr;
-
Used for describing
RPC
reply messages.
This routine is useful for users who want to generate
RPC-style
messages without using the
RPC
package.
xdr_replymsg(xdrs, rmsg)
XDR *xdrs;
struct rpc_msg *rmsg;
-
Used for describing
RPC
reply messages.
This routine is useful for users who want to generate
RPC-style
messages without using the
RPC
package.
xdr_setpos(xdrs, pos)
XDR *xdrs;
u_int pos;
-
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.
xdr_short(xdrs, sp)
XDR *xdrs;
short *sp;
-
A filter primitive that translates between C
short
integers and their external representations.
This routine returns one (1) if it succeeds, zero (0) otherwise.
void
xdrstdio_create(xdrs, file, op)
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 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().
xdr_string(xdrs, sp, maxsize)
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. The sp parameter
is the address of the string's pointer. 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.
xdr_u_char(xdrs, ucp)
XDR *xdrs;
unsigned char *ucp;
-
A filter primitive that translates between
unsigned
C characters and their external representations.
This routine returns one (1) if it succeeds, zero (0) otherwise.
xdr_u_hyper(xdrs, uhp)
XDR *xdrs;
u_longlong_t *uhp;
-
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 following section that explains the differences between
xdr_long and xdr_hyper.
xdr_u_int(xdrs, up)
XDR *xdrs;
unsigned *up;
-
A filter primitive that translates between C
unsigned
integers and their external representations.
This routine returns one (1) if it succeeds, zero (0) otherwise.
xdr_u_long(xdrs, ulp)
XDR *xdrs;
unsigned long *ulp;
-
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 the 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.
xdr_u_longlong_t(xdrs, uhp)
XDR *xdrs;
u_longlong_t *uhp;
-
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 following section that explains the differences between
xdr_long and xdr_hyper.
xdr_u_short(xdrs, usp)
XDR *xdrs;
unsigned short *usp;
-
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.
xdr_union(xdrs, dscmp, unp, choices, dfault)
XDR *xdrs;
int *dscmp;
char *unp;
struct xdr_discrim *choices;
bool_t (*defaultarm) (); /* may equal NULL */
-
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.
xdr_vector(xdrs, arrp, size, elsize, elproc)
XDR *xdrs;
char *arrp;
u_int size, elsize;
xdrproc_t elproc;
-
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
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.
xdr_void()
-
This routine always returns one (1).
It may be passed to
RPC
routines that require a function parameter,
where nothing is to be done.
xdr_wrapstring(xdrs, sp)
XDR *xdrs;
char **sp;
-
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.
Differences Between xdr_long and xdr_hyper Routines
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() 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 the xdr_u_longlong_t perform the same
function as the xdr_hyper and the xdr_u_hyper interfaces
respectively.
DESCRIPTION
These routines allow C programmers to describe
arbitrary data structures in a machine-independent fashion.
Data for ONC remote procedure calls are transmitted using these
routines.
RELATED INFORMATION
Routines: rpc(3)
delim off
Index
- NAME
-
- SYNOPSIS
-
- Differences Between xdr_long and xdr_hyper Routines
-
- DESCRIPTION
-
- RELATED INFORMATION
-
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Time: 02:41:50 GMT, October 02, 2010