\"      @(#)xdr.3n      2.2 88/08/03 4.0 RPCSRC; from 1.16 88/03/14 SMI
\"      $NetBSD: xdr.3,v 1.14 2011/07/08 19:28:22 wiz Exp $
\"
Dd July 4, 2011
Dt XDR 3
Os
Sh NAME
Nm xdr ,
Nm xdr_array ,
Nm xdr_bool ,
Nm xdr_bytes ,
Nm xdr_char ,
Nm xdr_destroy ,
Nm xdr_double ,
Nm xdr_enum ,
Nm xdr_float ,
Nm xdr_free ,
Nm xdr_getpos ,
Nm xdr_hyper ,
Nm xdr_inline ,
Nm xdr_int ,
Nm xdr_long ,
Nm xdr_longlong_t ,
Nm xdrmem_create ,
Nm xdr_opaque ,
Nm xdr_pointer ,
Nm xdrrec_create ,
Nm xdrrec_endofrecord ,
Nm xdrrec_eof ,
Nm xdrrec_skiprecord ,
Nm xdr_reference ,
Nm xdr_setpos ,
Nm xdr_short ,
Nm xdr_sizeof ,
Nm xdrstdio_create ,
Nm xdr_string ,
Nm xdr_u_char ,
Nm xdr_u_hyper ,
Nm xdr_u_long ,
Nm xdr_u_longlong_t ,
Nm xdr_u_short ,
Nm xdr_union ,
Nm xdr_vector ,
Nm xdr_void ,
Nm xdr_wrapstring
Nd library routines for external data representation
Sh SYNOPSIS
Ft int
Fn xdr_array "XDR *xdrs" "char **arrp" "u_int *sizep" "u_int maxsize" \
"u_int elsize" "xdrproc_t elproc"
Ft int
Fn xdr_bool "XDR *xdrs" "bool_t *bp"
Ft int
Fn xdr_bytes "XDR *xdrs" "char **sp" "u_int *sizep" "u_int maxsize"
Ft int
Fn xdr_char "XDR *xdrs" "char *cp"
Ft void
Fn xdr_destroy "XDR *xdrs"
Ft int
Fn xdr_double "XDR *xdrs" "double *dp"
Ft int
Fn xdr_enum "XDR *xdrs" "enum_t *ep"
Ft int
Fn xdr_float "XDR *xdrs" "float *fp"
Ft void
Fn xdr_free "xdrproc_t proc" "char *objp"
Ft u_int
Fn xdr_getpos "XDR *xdrs"
Ft int
Fn xdr_hyper "XDR *xdrs" "longlong_t *llp"
Ft long *
Fn xdr_inline "XDR *xdrs" "int len"
Ft int
Fn xdr_int "XDR *xdrs" "int *ip"
Ft int
Fn xdr_long "XDR *xdrs" "long *lp"
Ft int
Fn xdr_longlong_t "XDR *xdrs" "longlong_t *llp"
Ft void
Fn xdrmem_create "XDR *xdrs" "char *addr" "u_int size" \
"enum xdr_op op"
Ft int
Fn xdr_opaque "XDR *xdrs" "char *cp" "u_int cnt"
Ft int
Fn xdr_pointer "XDR *xdrs" "char **objpp" "u_int objsize" \
"xdrproc_t xdrobj"
Ft void
Fn xdrrec_create "XDR *xdrs" "u_int sendsize" "u_int recvsize" \
"char *handle" "int (*readit)()" "int (*writeit)()"
Ft int
Fn xdrrec_endofrecord "XDR *xdrs" "int sendnow"
Ft int
Fn xdrrec_eof "XDR *xdrs"
Ft int
Fn xdrrec_skiprecord "XDR *xdrs"
Ft int
Fn xdr_reference "XDR *xdrs" "char **pp" "u_int size" \
"xdrproc_t proc"
Ft int
Fn xdr_setpos "XDR *xdrs" "u_int pos"
Ft int
Fn xdr_short "XDR *xdrs" "short *sp"
Ft nsigned long
Fn xdr_sizeof "xdrproc_t func" "void *data"
Ft void
Fn xdrstdio_create "XDR *xdrs" "FILE *file" "enum xdr_op op"
Ft int
Fn xdr_string "XDR *xdrs" "char **sp" "u_int maxsize"
Ft int
Fn xdr_u_char "XDR *xdrs" "unsigned char *ucp"
Ft int
Fn xdr_u_hyper "XDR *xdrs" "u_longlong_t *ullp"
Ft int
Fn xdr_u_int "XDR *xdrs" "unsigned *up"
Ft int
Fn xdr_u_long "XDR *xdrs" "unsigned long *ulp"
Ft int
Fn xdr_u_longlong_t "XDR *xdrs" "u_longlong_t *ullp"
Ft int
Fn xdr_u_short "XDR *xdrs" "unsigned short *usp"
Ft int
Fn xdr_union "XDR *xdrs" "int *dscmp" "char *unp" \
"struct xdr_discrim *choices" "bool_t (*defaultarm)(\|)"
Ft int
Fn xdr_vector "XDR *xdrs" "char *arrp" "u_int size" \
"u_int elsize" "xdrproc_t elproc"
Ft int
Fn xdr_void "void"
Ft int
Fn xdr_wrapstring "XDR *xdrs" "char **sp"
Sh 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.
Bl -tag -width xxx
It Fn xdr_array
A filter primitive that translates between variable-length
arrays and their corresponding external representations.
The parameter
Fa arrp
is the address of the pointer to the array, while
Fa sizep
is the address of the element count of the array;
this element count cannot exceed
Fa maxsize .
The parameter
Fa elsize
is the
Em sizeof
each of the array's elements, and
Fa 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.
It Fn 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.
It Fn xdr_bytes
A filter primitive that translates between counted byte
strings and their external representations.
The parameter
Fa sp
is the address of the string pointer.
The length of the string is located at address
Fa sizep ;
strings cannot be longer than
Fa maxsize .
This routine returns one if it succeeds, zero otherwise.
It Fn 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 consider
Fn xdr_bytes ,
Fn xdr_opaque
or
Fn xdr_string .
It Fn xdr_destroy
A macro that invokes the destroy routine associated with the XDR
stream,
Fa xdrs .
Destruction usually involves freeing private data structures
associated with the stream.
Using
Fa xdrs
after invoking
Fn xdr_destroy
is undefined.
It Fn xdr_double
A filter primitive that translates between C double precision numbers
and their external representations.
This routine returns one if it succeeds, zero otherwise.
It Fn xdr_enum
A filter primitive that translates between C enums (actually integers)
and their external representations.
This routine returns one if it succeeds, zero otherwise.
It Fn xdr_float
A filter primitive that translates between C floats
and their external representations.
This routine returns one if it succeeds, zero otherwise.
It Fn 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
Em not
freed, but what it points to
Em is
freed (recursively).
It Fn xdr_getpos
A macro that invokes the get-position routine associated with the XDR
stream,
Fa 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.
It Fn 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.
It Fn xdr_inline
A macro that invokes the in-line routine associated with the XDR
stream,
Fa xdrs .
The routine returns a pointer
to a contiguous piece of the stream's buffer;
Fa len
is the byte length of the desired buffer.
Note: pointer is cast to
Vt "long *" .
Pp
Warning:
Fn xdr_inline
may return
Dv 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.
It Fn xdr_int
A filter primitive that translates between C integers
and their external representations.
This routine returns one if it succeeds, zero otherwise.
It Fn xdr_long
A filter primitive that translates between C long integers
and their external representations.
This routine returns one if it succeeds, zero otherwise.
It Fn 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.
It Fn xdrmem_create
This routine initializes the XDR stream object pointed to by
Fa xdrs .
The stream's data is written to, or read from,
a chunk of memory at location
Fa addr
whose length is no more than
Fa size
bytes long.
The
Fa op
determines the direction of the XDR stream (either
Dv XDR_ENCODE ,
Dv XDR_DECODE ,
or
Dv XDR_FREE ) .
It Fn xdr_opaque
A filter primitive that translates between fixed size opaque data
and its external representation.
The parameter
Fa cp
is the address of the opaque object, and
Fa cnt
is its size in bytes.
This routine returns one if it succeeds, zero otherwise.
It Fn xdr_pointer
Like
Fn xdr_reference
except that it serializes
Dv NULL
pointers, whereas
Fn xdr_reference
does not.
Thus,
Fn xdr_pointer
can represent recursive data structures, such as binary trees or
linked lists.
It Fn xdrrec_create
This routine initializes the XDR stream object pointed to by
Fa xdrs .
The stream's data is written to a buffer of size
Fa sendsize ;
a value of zero indicates the system should use a suitable default.
The stream's data is read from a buffer of size
Fa recvsize ;
it too can be set to a suitable default by passing a zero value.
When a stream's output buffer is full,
Fa writeit
is called.
Similarly, when a stream's input buffer is empty,
Fa readit
is called.
The behavior of these two routines is similar to the system calls
Xr read 2
and
Xr write 2 ,
except that
Fa handle
is passed to the former routines as the first parameter.
Note: the XDR stream's
Fa op
field must be set by the caller.
Pp
Warning: this XDR stream implements an intermediate record stream.
Therefore there are additional bytes in the stream
to provide record boundary information.
It Fn xdrrec_endofrecord
This routine can be invoked only on streams created by
Fn xdrrec_create .
The data in the output buffer is marked as a completed record,
and the output buffer is optionally written out if
Fa sendnow
is non-zero.
This routine returns one if it succeeds, zero otherwise.
It Fn xdrrec_eof
This routine can be invoked only on streams created by
Fn 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.
It Fn xdrrec_skiprecord
This routine can be invoked only on streams created by
Fn 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.
It Fn xdr_reference
A primitive that provides pointer chasing within structures.
The parameter
Fa pp
is the address of the pointer;
Fa size
is the
Em sizeof
the structure that
Fa *pp
points to; and
Fa 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.
Pp
Warning: this routine does not understand
Dv NULL
pointers.
Use
Fn xdr_pointer
instead.
It Fn xdr_setpos
A macro that invokes the set position routine associated with the XDR
stream
Fa xdrs .
The parameter
Fa pos
is a position value obtained from
Fn xdr_getpos .
This routine returns one if the XDR stream could be repositioned,
and zero otherwise.
Pp
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.
It Fn xdr_short
A filter primitive that translates between C short integers
and their external representations.
This routine returns one if it succeeds, zero otherwise.
It Fn xdr_sizeof
This routine returns the amount of memory required to encode
Fa data
using filter
Fa func .
It Fn xdrstdio_create
This routine initializes the XDR stream object pointed to by
Fa xdrs .
The XDR stream data is written to, or read from, the Standard I/O
stream
Fa file .
The parameter
Fa op
determines the direction of the XDR stream (either
Dv XDR_ENCODE ,
Dv XDR_DECODE ,
or
Dv XDR_FREE ) .
Pp
Warning: the destroy routine associated with such XDR streams calls
Xr fflush 3
on the file stream, but never
Xr fclose 3 .
It Fn xdr_string
A filter primitive that translates between C strings and
their corresponding external representations.
Strings cannot be longer than
Fa maxsize .
Note:
Fa sp
is the address of the string's pointer.
This routine returns one if it succeeds, zero otherwise.
It Fn xdr_u_char
A filter primitive that translates between unsigned C characters
and their external representations.
This routine returns one if it succeeds, zero otherwise.
It Fn 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.
It Fn 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.
It Fn 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.
It Fn 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.
It Fn 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.
It Fn 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
Fa dscmp .
This discriminant is always an enum_t.
Next the union located at
Fa unp
is translated.
The parameter
Fa choices
is a pointer to an array of
Fn xdr_discrim
structures.
Each structure contains an ordered pair of
Fa [ value ,
Fa proc ] .
If the union's discriminant is equal to the associated
Fa value ,
then the
Fa proc
is called to translate the union.
The end of the
Fn xdr_discrim
structure array is denoted by a routine of value
Dv NULL .
If the discriminant is not found in the
Fa choices
array, then the
Fa defaultarm
procedure is called (if it is not
Dv NULL ) .
Returns one if it succeeds, zero otherwise.
It Fn xdr_vector
A filter primitive that translates between fixed-length
arrays and their corresponding external representations.
The parameter
Fa arrp
is the address of the pointer to the array, while
Fa size
is the element count of the array.
The parameter
Fa elsize
is the
Em sizeof
each of the array's elements, and
Fa 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.
It Fn 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.
It Fn xdr_wrapstring
A primitive that calls
Fn xdr_string "xdrs" "sp" "MAXUN.UNSIGNED" ;
where
Dv MAXUN.UNSIGNED
is the maximum value of an unsigned integer.
Fn xdr_wrapstring
is handy because the RPC package passes a maximum of two XDR
routines as parameters, and
Fn xdr_string ,
one of the most frequently used primitives, requires three.
Returns one if it succeeds, zero otherwise.
El
Sh SEE ALSO
Xr rpc 3
Pp
The following manuals:
Rs
%B "eXternal Data Representation Standard: Protocol Specification"
Re
Rs
%B "eXternal Data Representation: Sun Technical Notes"
Re
Rs
%A Sun Microsystems, Inc., USC-ISI
%T "XDR: External Data Representation Standard"
%R "RFC 1014, USC-ISI"
%V 1014
Re

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