xdr_complex(3N)xdr_complex(3N)NAME
xdr_complex: xdr_array, xdr_bytes, xdr_opaque, xdr_pointer,
xdr_reference, xdr_string, xdr_union, xdr_vector, xdr_wrapstring-
library routines for external data representation
DESCRIPTION
XDR library routines allow C programmers to describe complex data
structures in a machine-independent fashion. Protocols such as remote
procedure calls (RPC) use these routines to describe the format of the
data. These routines are the XDR library routines for complex data
structures. They require the creation of XDR stream [see
xdr_create(3N)].
Routines
See rpc(3N) for the definition of the XDR data structure.
#include <rpc/xdr.h>
bool_t
xdr_array(XDR *xdrs, caddr_t *arrp, u_int *sizep,
const u_int maxsize, const u_int elsize,
const xdrproc_t elproc);
xdr_array 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 routine that translates between the
array elements' C form and their external representation. This
routine returns 1 if it succeeds, 0 otherwise.
bool_t
xdr_bytes(XDR *xdrs, char **sp, u_int *sizep,
const u_int maxsize);
xdr_bytes 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.
bool_t
xdr_opaque(XDR *xdrs, caddr_t cp, const u_int cnt);
xdr_opaque 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.
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xdr_complex(3N)xdr_complex(3N)
bool_t
xdr_pointer(XDR *xdrs, char **objpp, u_int objsize,
const 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, caddr_t *pp, u_int size,
const xdrproc_t proc);
xdr_reference 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
translates the structure between its C form and its external
representation. This routine returns 1 if it succeeds, 0 otherwise.
Note: this routine does not understand NULL pointers. Use
xdr_pointer instead.
bool_t
xdr_string(XDR *xdrs, char **sp, const u_int maxsize);
xdr_string 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_union(XDR *xdrs, enum_t *dscmp, char *unp,
const struct xdr_discrim *choices,
const bool_t (*defaultarm)(const XDR *, const char *,
const int));
xdr_union 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.
bool_t
xdr_vector(XDR *xdrs, char *arrp, const u_int size,
const u_int elsize, const xdrproc_t elproc);
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xdr_complex(3N)xdr_complex(3N)
xdr_vector 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 routine that translates
between the array elements' C form and their external
representation. This routine returns 1 if it succeeds, 0 otherwise.
bool_t
xdr_wrapstring(XDR *xdrs, char **sp);
A routine that calls xdr_string(xdrs, sp, maxuint); where maxuint is
the maximum value of an unsigned integer.
Many routines, such as xdr_array, xdr_pointer and xdr_vector take a
function pointer of type xdrproc_t, which takes two arguments.
xdr_string, one of the most frequently used routines, requires three
arguments, while xdr_wrapstring only requires two. For these
routines, xdr_wrapstring is desirable. This routine returns 1 if it
succeeds, 0 otherwise.
SEE ALSOrpc(3N), xdr_admin(3N), xdr_create(3N), xdr_simple(3N)
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