xdr(3N) DG/UX 4.30 xdr(3N)
NAME
xdr_array, xdr_bool, xdr_bytes, xdr_char, xdr_destroy,
xdr_double, xdr_int, xdr_long, 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_short, xdr_union, xdr_vector, xdr_void,
xdr_wrapstring - library routines for external data
representation
SYNOPSIS AND DESCRIPTION
The XDR library has filter routines for strings (null-
terminated arrays of bytes), structures, unions, arrays, and
the basic C language data types. These routines, allow C
programmers to describe arbitrary data structures in a
machine-independent fashion.
XDR routines a are direction-independent; that is the same
routines are called to serialize data to, or deserialize
data from, an XDR stream. XDR streams are created by the use
of the xdr*_create() functions, and then the pointer to
these streams are passed to many of the other XDR functions.
Data for remote procedure calls are transmitted using these
routines.
#include <rpc/rpc.h>
xdrarray(xdrs, arrp, sizep, maxsize, elsize, elproc)
XDR *xdrs;
char **arrp;
uint *sizep, maxsize, elsize;
xdrproct 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.
xdrbool(xdrs, bp)
XDR *xdrs;
boolt *bp;
A filter primitive that translates between booleans (C
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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.
xdrbytes(xdrs, sp, sizep, maxsize)
XDR *xdrs;
char **sp;
uint *sizep, 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.
xdrchar(xdrs, cp)
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 xdrbytes(), xdropaque() or xdrstring().
void
xdrdestroy(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
xdrdestroy() is undefined.
xdrdouble(xdrs, dp)
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.
xdrenum(xdrs, ep)
XDR *xdrs;
enumt *ep;
A filter primitive that translates between C enums
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(actually integers) and their external representations.
This routine returns one if it succeeds, zero
otherwise.
xdrfloat(xdrs, fp)
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
xdrfree(proc, objp)
xdrproct 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).
uint
xdrgetpos(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.
long *
xdrinline(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: xdrinline() 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.
xdrint(xdrs, ip)
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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.
xdrlong(xdrs, lp)
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
xdrmemcreate(xdrs, addr, size, op)
XDR *xdrs;
char *addr;
uint size;
enum xdrop 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 XDRENCODE,
XDRDECODE, or XDRFREE).
xdropaque(xdrs, cp, cnt)
XDR *xdrs;
char *cp;
uint 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.
xdrpointer(xdrs, objpp, objsize, xdrobj)
XDR *xdrs;
char **objpp;
uint objsize;
xdrproct xdrobj;
Like xdrreference() except that it serializes NULL
pointers, whereas xdrreference() does not. Thus,
xdrpointer() can represent recursive data structures,
such as binary trees or linked lists.
void
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xdrreccreate(xdrs, sendsize, recvsize, handle, readit, writeit)
XDR *xdrs;
uint 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 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.
xdrrecendofrecord(xdrs, sendnow)
XDR *xdrs;
int sendnow;
This routine can be invoked only on streams created by
xdrreccreate(). 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.
xdrreceof(xdrs)
XDR *xdrs;
int empty;
This routine can be invoked only on streams created by
xdrreccreate(). After consuming the rest of the
current record in the stream, this routine returns one
if the stream has no more input, zero otherwise.
xdrrecskiprecord(xdrs)
XDR *xdrs;
This routine can be invoked only on streams created by
xdrreccreate(). 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.
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xdrreference(xdrs, pp, size, proc)
XDR *xdrs;
char **pp;
uint size;
xdrproct 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 xdrpointer() instead.
xdrsetpos(xdrs, pos)
XDR *xdrs;
uint pos;
A macro that invokes the set position routine
associated with the XDR stream xdrs. The parameter pos
is a position value obtained from xdrgetpos(). 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.
xdrshort(xdrs, sp)
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
xdrstdiocreate(xdrs, file, op)
XDR *xdrs;
FILE *file;
enum xdrop 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
XDRENCODE, XDRDECODE, or XDRFREE).
Warning: the destroy routine associated with such XDR
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xdr(3N) DG/UX 4.30 xdr(3N)
streams calls fflush() on the file stream, but never
fclose().
xdrstring(xdrs, sp, maxsize)
XDR
*xdrs;
char **sp;
uint 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.
xdruchar(xdrs, ucp)
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.
xdruint(xdrs, up)
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.
xdrulong(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 if it succeeds, zero otherwise.
xdrushort(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 if it succeeds, zero
otherwise.
xdrunion(xdrs, dscmp, unp, choices, dfault)
XDR *xdrs;
int *dscmp;
char *unp;
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struct xdrdiscrim *choices;
boolt (*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 enumt. Next the union located at unp is
translated. The parameter choices is a pointer to an
array of xdrdiscrim() 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 xdrdiscrim() 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.
xdrvector(xdrs, arrp, size, elsize, elproc)
XDR *xdrs;
char *arrp;
uint size, elsize;
xdrproct 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.
xdrvoid()
This routine always returns one. It may be passed to
RPC routines that require a function parameter, where
nothing is to be done.
xdrwrapstring(xdrs, sp)
XDR *xdrs;
char **sp;
A primitive that calls xdrstring(xdrs, sp,
MAX.UNSIGNED");" where MAX.UNSIGNED is the maximum
value of an unsigned integer. xdrwrapstring() is
handy because the RPC package passes a maximum of two
XDR routines as parameters, and xdrstring(), one of
the most frequently used primitives, requires three.
Returns one if it succeeds, zero otherwise.
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SEE ALSO
rpc(3N).
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