XDR(3) BSD Library Functions Manual XDR(3)NAME
xdr, xdr_array, xdr_bool, xdr_bytes, xdr_char, xdr_destroy, xdr_double,
xdr_enum, xdr_float, xdr_free, xdr_getpos, xdr_hyper, xdr_inline,
xdr_int, xdr_long, xdr_longlong_t, xdrmem_create, xdr_opaque,
xdr_pointer, xdrrec_create, xdrrec_endofrecord, xdrrec_eof,
xdrrec_skiprecord, xdr_reference, xdr_setpos, xdr_short, xdr_sizeof,
xdrstdio_create, xdr_string, xdr_u_char, xdr_u_hyper, 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
int
xdr_array(XDR *xdrs, char **arrp, u_int *sizep, u_int maxsize,
u_int elsize, xdrproc_t elproc);
int
xdr_bool(XDR *xdrs, bool_t *bp);
int
xdr_bytes(XDR *xdrs, char **sp, u_int *sizep, u_int maxsize);
int
xdr_char(XDR *xdrs, char *cp);
void
xdr_destroy(XDR *xdrs);
int
xdr_double(XDR *xdrs, double *dp);
int
xdr_enum(XDR *xdrs, enum_t *ep);
int
xdr_float(XDR *xdrs, float *fp);
void
xdr_free(xdrproc_t proc, char *objp);
u_int
xdr_getpos(XDR *xdrs);
int
xdr_hyper(XDR *xdrs, longlong_t *llp);
long *
xdr_inline(XDR *xdrs, int len);
int
xdr_int(XDR *xdrs, int *ip);
int
xdr_long(XDR *xdrs, long *lp);
int
xdr_longlong_t(XDR *xdrs, longlong_t *llp);
void
xdrmem_create(XDR *xdrs, char *addr, u_int size, enum xdr_op op);
int
xdr_opaque(XDR *xdrs, char *cp, u_int cnt);
int
xdr_pointer(XDR *xdrs, char **objpp, u_int objsize, xdrproc_t xdrobj);
void
xdrrec_create(XDR *xdrs, u_int sendsize, u_int recvsize, char *handle,
int (*readit)(), int (*writeit)());
int
xdrrec_endofrecord(XDR *xdrs, int sendnow);
int
xdrrec_eof(XDR *xdrs);
int
xdrrec_skiprecord(XDR *xdrs);
int
xdr_reference(XDR *xdrs, char **pp, u_int size, xdrproc_t proc);
int
xdr_setpos(XDR *xdrs, u_int pos);
int
xdr_short(XDR *xdrs, short *sp);
nsigned long
xdr_sizeof(xdrproc_t func, void *data);
void
xdrstdio_create(XDR *xdrs, FILE *file, enum xdr_op op);
int
xdr_string(XDR *xdrs, char **sp, u_int maxsize);
int
xdr_u_char(XDR *xdrs, unsigned char *ucp);
int
xdr_u_hyper(XDR *xdrs, u_longlong_t *ullp);
int
xdr_u_int(XDR *xdrs, unsigned *up);
int
xdr_u_long(XDR *xdrs, unsigned long *ulp);
int
xdr_u_longlong_t(XDR *xdrs, u_longlong_t *ullp);
int
xdr_u_short(XDR *xdrs, unsigned short *usp);
int
xdr_union(XDR *xdrs, int *dscmp, char *unp, struct xdr_discrim *choices,
bool_t (*defaultarm)());
int
xdr_vector(XDR *xdrs, char *arrp, u_int size, u_int elsize,
xdrproc_t elproc);
int
xdr_void(void);
int
xdr_wrapstring(XDR *xdrs, char **sp);
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()
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 representa‐
tion. This routine returns one if it succeeds, zero otherwise.
xdr_bool()
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()
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.
xdr_char()
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 con‐
sider xdr_bytes(), xdr_opaque() or xdr_string().
xdr_destroy()
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()
A filter primitive that translates between C double precision num‐
bers and their external representations. This routine returns one
if it succeeds, zero otherwise.
xdr_enum()
A filter primitive that translates between C enums (actually inte‐
gers) and their external representations. This routine returns one
if it succeeds, zero otherwise.
xdr_float()
A filter primitive that translates between C floats and their exter‐
nal representations. This routine returns one if it succeeds, zero
otherwise.
xdr_free()
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).
xdr_getpos()
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()
A filter primitive that translates between ANSI C long long integers
and their external representations. This routine returns one if it
succeeds, zero otherwise.
xdr_inline()
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 buf‐
fer. Note: pointer is cast to long *.
Warning: xdr_inline() may return NULL if it cannot allocate a con‐
tiguous piece of a buffer. Therefore the behavior may vary among
stream instances; it exists for the sake of efficiency.
xdr_int()
A filter primitive that translates between C integers and their
external representations. This routine returns one if it succeeds,
zero otherwise.
xdr_long()
A filter primitive that translates between C long integers and their
external representations. This routine returns one if it succeeds,
zero otherwise.
xdr_longlong_t()
A filter primitive that translates between ANSI C long long integers
and their external representations. This routine returns one if it
succeeds, zero otherwise.
xdrmem_create()
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()
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()
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.
xdrrec_create()
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 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()
This routine can be invoked only on streams created by
xdrrec_create(). The data in the output buffer is marked as a com‐
pleted 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()
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()
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.
xdr_reference()
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 representa‐
tion. This routine returns one if it succeeds, zero otherwise.
Warning: this routine does not understand NULL pointers. Use
xdr_pointer() instead.
xdr_setpos()
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.
xdr_short()
A filter primitive that translates between C short integers and
their external representations. This routine returns one if it suc‐
ceeds, zero otherwise.
xdr_sizeof()
This routine returns the amount of memory required to encode data
using filter func.
xdrstdio_create()
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(3) on the file stream, but never fclose(3).
xdr_string()
A filter primitive that translates between C strings and their cor‐
responding 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.
xdr_u_char()
A filter primitive that translates between unsigned C characters and
their external representations. This routine returns one if it suc‐
ceeds, zero otherwise.
xdr_u_hyper()
A filter primitive that translates between unsigned ANSI C long long
integers and their external representations. This routine returns
one if it succeeds, zero otherwise.
xdr_u_int()
A filter primitive that translates between C unsigned integers
and their external representations. This routine returns one if it
succeeds, zero otherwise.
xdr_u_long()
A filter primitive that translates between C unsigned long integers
and their external representations. This routine returns one if it
succeeds, zero otherwise.
xdr_u_longlong_t()
A filter primitive that translates between unsigned ANSI C long long
integers and their external representations. This routine returns
one if it succeeds, zero otherwise.
xdr_u_short()
A filter primitive that translates between C unsigned short integers
and their external representations. This routine returns one if it
succeeds, zero otherwise.
xdr_union()
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.
xdr_vector()
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 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 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()
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(3)
The following manuals:
eXternal Data Representation Standard: Protocol Specification.
eXternal Data Representation: Sun Technical Notes.
Sun Microsystems, Inc., USC-ISI, XDR: External Data Representation
Standard, RFC 1014, USC-ISI, 1014.
BSD July 4, 2011 BSD
