XDR(3N)XDR(3N)NAME
xdr_array, xdr_bool, xdr_bytes, xdr_char, xdr_destroy,
xdr_double, xdr_enum, xdr_float, xdr_free, xdr_getpos,
xdr_inline, xdr_int, xdr_long, xdrmem_create, xdr_opaque,
xdr_pointer, xdrrec_create, xdrrec_endofrecord, xdr-
rec_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
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.
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 vari-
able-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 rep-
resentation. This routine returns one if it suc-
ceeds, zero otherwise.
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 or zero. This routine returns one if it
succeeds, zero 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 parameter sp is the address of the string
pointer. The length of the string is located at
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XDR(3N)XDR(3N)
address sizep; strings cannot be longer than max-
size. This routine returns one if it succeeds,
zero otherwise.
xdr_char(xdrs, cp)
XDR *xdrs;
char *cp;
A filter primitive that translates between C char-
acters 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(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 representa-
tions. This routine returns one if it succeeds,
zero otherwise.
xdr_enum(xdrs, ep)
XDR *xdrs;
enum_t *ep;
A filter primitive that translates between C enums
(actually integers) and their external representa-
tions. This routine returns one if it succeeds,
zero 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 if it succeeds, zero otherwise.
void
xdr_free(proc, objp)
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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 asso-
ciated with the XDR stream, xdrs. The routine
returns an unsigned integer, which indicates the
position of the XDR byte stream. A desirable fea-
ture of XDR streams is that simple arithmetic works
with this number, although the XDR stream instances
need not guarantee this.
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 (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.
xdr_int(xdrs, ip)
XDR *xdrs;
int *ip;
A filter primitive that translates between C inte-
gers and their external representations. This rou-
tine returns one if it succeeds, zero 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 if it succeeds, zero otherwise.
void
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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 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.
xdr_pointer(xdrs, objpp, objsize, xdrobj)
XDR *xdrs;
char **objpp;
u_int objsize;
xdrproc_t xdrobj;
Like xdr_reference() execpt that it serializes NULL
pointers, whereas xdr_reference() does not. Thus,
xdr_pointer() can represent recursive data struc-
tures, 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 indi-
cates the system should use a suitable default. The
stream's data is read from a buffer of size recv-
size; 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
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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.
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 if it succeeds, zero
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 if the stream has no more input, zero
otherwise.
xdrrec_skiprecord(xdrs)
XDR *xdrs;
This routine can be invoked only on streams created
by xdrrec_create(). It tells the XDR implementa-
tion 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.
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 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 fil-
ters 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.
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xdr_setpos(xdrs, pos)
XDR *xdrs;
u_int pos;
A macro that invokes the set position routine asso-
ciated 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.
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 if it succeeds, zero 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 parameter op 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 represen-
tations. Strings cannot be longer than maxsize.
Note: sp is the address of the string's pointer.
This routine returns one if it succeeds, zero oth-
erwise.
xdr_u_char(xdrs, ucp)
XDR *xdrs;
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unsigned char *ucp;
A filter primitive that translates between unsigned
C characters and their external representations.
This routine returns one if it succeeds, zero oth-
erwise.
xdr_u_int(xdrs, up)
XDR *xdrs;
unsigned *up;
A filter primitive that translates between C
unsigned integers and their external representa-
tions. This routine returns one if it succeeds,
zero otherwise.
xdr_u_long(xdrs, ulp)
XDR *xdrs;
unsigned long *ulp;
A filter primitive that translates between C
unsigned long integers and their external represen-
tations. This routine returns one if it succeeds,
zero otherwise.
xdr_u_short(xdrs, usp)
XDR *xdrs;
unsigned short *usp;
A filter primitive that translates between C
unsigned short integers and their external repre-
sentations. This routine returns one if it suc-
ceeds, zero 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 dis-
criminated C union and its corresponding external
representation. It first translates the discrimi-
nant of the union located at dscmp. This discrimi-
nant 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
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choices array, then the defaultarm procedure is
called (if it is not NULL). Returns one if it suc-
ceeds, zero 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 rep-
resentations. The parameter arrp is the address of
the pointer to the array, while size is is the ele-
ment 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 representa-
tion. This routine returns one if it succeeds,
zero otherwise.
xdr_void()
This routine always returns one. 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,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 suc-
ceeds, zero otherwise.
SEE ALSOrpc(3N)
The following manuals:
eXternal Data Representation Standard: Protocol
Specification
eXternal Data Representation: Sun Technical Notes
XDR: External Data Representation Standard,
RFC1014, Sun Microsystems, Inc., USC-ISI.
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