XDR(3R) XDR(3R)
xdr - External Data Representation (XDR) library routines
SYNOPSIS AND DESCRIPTION [Toc] [Back] 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.
#include <rpc/rpc.h>
bool_t
xdr_array(XDR *xdrs, caddr_t *arrp, u_int *sizep,
u_int maxsize, u_int elsize, xdrproc_t 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 1 if it succeeds, 0 otherwise.
bool_t
xdr_bool(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 1 or 0. This routine returns 1 if it
succeeds, 0 otherwise.
bool_t
xdr_bytes(XDR *xdrs, char **sp, u_int *sizep,
u_int 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
1 if it succeeds, 0 otherwise.
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XDR(3R) XDR(3R)
bool_t
xdr_char(XDR *xdrs, char *cp)
A filter primitive that translates between C characters and their
external representations. This routine returns 1 if it succeeds, 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(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.
bool_t
xdr_double(XDR *xdrs, double *dp)
A filter primitive that translates between C double precision
numbers and their external representations. This routine returns 1
if it succeeds, 0 otherwise.
bool_t
xdr_enum(XDR *xdrs, enum_t *ep)
A filter primitive that translates between C enums (actually
integers) and their external representations. This routine returns
1 if it succeeds, 0 otherwise.
bool_t
xdr_float(XDR *xdrs, float *fp)
A filter primitive that translates between C floats and their
external representations. This routine returns 1 if it succeeds, 0
otherwise.
void
xdr_free(xdrproc_t proc, char *objp)
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XDR(3R) XDR(3R)
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(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 *
xdr_inline(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: the 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.
bool_t
xdr_int(XDR *xdrs, int *ip)
A filter primitive that translates between C integers and their
external representations. This routine returns 1 if it succeeds, 0
otherwise.
bool_t
xdr_long(XDR *xdrs, long *lp)
A filter primitive that translates between C long integers and their
external representations. This routine returns 1 if it succeeds, 0
otherwise.
Warning: In the IRIX 64-bit ABI, this routine may be somewhat
misleading. The external representation of a long integer is defined
by the XDR standard to be a 32 bit encoding, but in the IRIX 64-bit
ABI, a long integer is 64 bits. Hence, in the IRIX 64-bit ABI, long
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XDR(3R) XDR(3R)
integers are truncated by xdr_long(), and xdr_long() is only useful
for encoding/decoding values in the range of -2147483648 to
2147483647.
bool_t
xdr_longlong_t(XDR *xdrs, __int64_t *ulp)
A filter primitive that translates between C 64-bit integers and
their external representations. This routine returns 1 if it
succeeds, 0 otherwise.
bool_t
xdr_opaque(XDR *xdrs, void *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 1 if it succeeds, 0 otherwise.
bool_t
xdr_pointer(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.
bool_t
xdr_reference(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
filters the structure between its C form and its external
representation. This routine returns 1 if it succeeds, 0 otherwise.
Warning: this routine does not understand NULL pointers. Use
xdr_pointer() instead.
bool_t
xdr_setpos(XDR *xdrs, u_int pos)
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XDR(3R) XDR(3R)
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 1 if the XDR stream could
be repositioned, and 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.
bool_t
xdr_short(XDR *xdrs, short *sp)
A filter primitive that translates between C short integers and
their external representations. This routine returns 1 if it
succeeds, 0 otherwise.
bool_t
xdr_string(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. Note: sp is the address of the string's pointer.
This routine returns 1 if it succeeds, 0 otherwise.
bool_t
xdr_u_char(XDR *xdrs, unsigned char *cp)
A filter primitive that translates between unsigned C characters and
their external representations. This routine returns 1 if it
succeeds, 0 otherwise.
bool_t
xdr_u_int(XDR *xdrs, unsigned *up)
A filter primitive that translates between C unsigned integers and
their external representations. This routine returns 1 if it
succeeds, 0 otherwise.
bool_t
xdr_u_long(XDR *xdrs, unsigned long *ulp)
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XDR(3R) XDR(3R)
A filter primitive that translates between C unsigned long integers
and their external representations. This routine returns 1 if it
succeeds, 0 otherwise.
Warning: In the IRIX 64-bit ABI, this routine may be somewhat
misleading. The external representation of an unsigned long integer
is defined by the XDR standard to be a 32 bit encoding, but in the
IRIX 64-bit ABI, an unsigned long integer is 64 bits. Hence, in the
IRIX 64-bit ABI, unsigned long integers are truncated by
xdr_u_long(), and xdr_u_long() is only useful for encoding/decoding
values in the range of 0 to 4294967295.
bool_t
xdr_u_longlong_t(XDR *xdrs, __uint64_t *ulp)
A filter primitive that translates between C unsigned 64-bit
integers and their external representations. This routine returns 1
if it succeeds, 0 otherwise.
bool_t
xdr_u_short(XDR *xdrs, unsigned short *usp)
A filter primitive that translates between C unsigned short integers
and their external representations. This routine returns 1 if it
succeeds, 0 otherwise.
bool_t
xdr_union(XDR *xdrs, enum_t *dscmp, void *unp,
struct xdr_discrim *choices, xdrproc_t dfault)
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 1
if it succeeds, 0 otherwise.
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XDR(3R) XDR(3R)
bool_t
xdr_vector(XDR *xdrs, char *arrp,
u_int size, u_int elsize, xdrproc_t 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 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 1 if it succeeds, 0 otherwise.
bool_t
xdr_void(XDR *xdrs, void *v)
This routine always returns 1. It may be passed to RPC routines
that require a function parameter, where nothing is to be done.
bool_t
xdr_wrapstring(XDR *xdrs, char **sp)
A primitive that calls
xdr_string(xdrs, sp, UINT_MAX);
where UINT_MAX is the maximum value of an unsigned integer, as
defined in <limits.h>. 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 1 if it succeeds, 0 otherwise.
void
xdrmem_create(XDR *xdrs, void *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).
void
xdrrec_create(XDR *xdrs, u_int sendsize, u_int recvsize,
void *handle,
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XDR(3R) XDR(3R)
int (*readit)(void *, void *, u_int),
int (*writeit)(void *, void *, u_int))
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 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 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.
bool_t
xdrrec_endofrecord(XDR *xdrs, bool_t 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 1 if it succeeds, 0
otherwise.
bool_t
xdrrec_eof(XDR *xdrs)
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 1 if the stream has no more input,
0 otherwise.
int
xdrrec_readbytes(XDR *xdrs, caddr_t addr, u_int len)
This routine reads data from the stream. It behaves like the read(2)
system call against a pipe - it returns up to the number of bytes
requested and a return of zero indicates end-of-record. A -1 means
something very bad happened.
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XDR(3R) XDR(3R)
bool_t
xdrrec_skiprecord(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 1 if it succeeds, 0 otherwise.
void
xdrstdio_create(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(3S) on the file stream, but never fclose(3S).
rpc(3R), IRIX Network Programming Guide.
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