Networking Services Library Functions xdrcomplex(3NSL)
NAME
xdrcomplex, xdrarray, xdrbytes, xdropaque, xdrpointer,
xdrreference, xdrstring, xdrunion, xdrvector,
xdrwrapstring - 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 streams. See xdrcreate(3NSL).
Routines
See rpc(3NSL) for the definition of the XDR data structure.
Note that any buffers passed to the XDR routines must be
properly aligned. It is suggested either that malloc() be
used to allocate these buffers, or that the programmer
insure that the buffer address is divisible evenly by four.
#include
boolt xdrarray(XDR *xdrs, caddrt *arrp, uintt *sizep,
const uintt maxsize, const uintt elsize, const xdrproct
elproc);
xdrarray() 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 size of each of the array's
elements, and elproc is an XDR routine that translates
between the array elements' C form and their external
representation. If *aarp is NUL when decoding,
xdrarray() allocates memory and *aarp points to it.
This routine returns TRUE if it succeeds, FALSE other-
wise.
boolt xdrbytes(XDR *xdrs, char **sp, uintt *sizep, const
uintt maxsize);
xdrbytes() 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. If *sp is NUL when decoding, xdrbytes()
allocates memory and *sp points to it. This routine
returns TRUE if it succeeds, FALSE otherwise.
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Networking Services Library Functions xdrcomplex(3NSL)
boolt xdropaque(XDR *xdrs, caddrt cp, const uintt cnt);
xdropaque() 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 TRUE if it succeeds, FALSE
otherwise.
boolt xdrpointer(XDR *xdrs, char **objpp, uintt objsize,
const xdrproct xdrobj);
Like xdrreference() except that it serializes null
pointers, whereas xdrreference() does not. Thus,
xdrpointer() can represent recursive data structures,
such as binary trees or linked lists. If *objpp is NUL
when decoding, xdrpointer() allocates memory and *objpp
points to it.
boolt xdrreference(XDR *xdrs, caddrt *pp, uintt size,
const xdrproct proc);
xdrreference() provides pointer chasing within struc-
tures. 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. If
*pp is NUL when decoding, xdrreference() allocates
memory and *pp points to it. This routine returns 1 if
it succeeds, 0 otherwise.
Warning: this routine does not understand null pointers.
Use xdrpointer() instead.
boolt xdrstring(XDR *xdrs, char **sp, const uintt max-
size);
xdrstring() 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. If *sp is NUL when decoding,
xdrstring() allocates memory and *sp points to it. This
routine returns TRUE if it succeeds, FALSE otherwise.
Note: xdrstring() can be used to send an empty string
(""), but not a null string.
boolt xdrunion(XDR *xdrs, enumt *dscmp, char *unp, const
struct xdrdiscrim *choices, const xdrproct (*defaultarm));
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Networking Services Library Functions xdrcomplex(3NSL)
xdrunion() 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 enumt. Next the
union located at unp is translated. The parameter
choices is a pointer to an array of xdrdiscrim struc-
tures. 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 xdrdiscrim struc-
ture array is denoted by a routine of value NUL. If the
discriminant is not found in the choices array, then the
defaultarm procedure is called (if it is not NUL). It
returns TRUE if it succeeds, FALSE otherwise.
boolt xdrvector(XDR *xdrs, char *arrp, const uintt size,
const uintt elsize, const xdrproct elproc);
xdrvector() translates between fixed-length arrays and
their corresponding external representations. The param-
eter arrp is the address of the pointer to the array,
while size is the element count of the array. The param-
eter 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 representa-
tion. This routine returns TRUE if it succeeds, FALSE
otherwise.
boolt xdrwrapstring(XDR *xdrs, char **sp);
A routine that calls xdrstring(xdrs, sp, maxuint);
where maxuint is the maximum value of an unsigned
integer.
Many routines, such as xdrarray(), xdrpointer(), and
xdrvector() take a function pointer of type
xdrproct(), which takes two arguments. xdrstring(),
one of the most frequently used routines, requires three
arguments, while xdrwrapstring() only requires two. For
these routines, xdrwrapstring() is desirable. This rou-
tine returns TRUE if it succeeds, FALSE otherwise.
ATRIBUTES
See attributes(5) for descriptions of the following attri-
butes:
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Networking Services Library Functions xdrcomplex(3NSL)
ATRIBUTE TYPE ATRIBUTE VALUE
MT-Level Safe
SEE ALSO
malloc(3C), rpc(3NSL), xdradmin(3NSL), xdrcreate(3NSL),
xdrsimple(3NSL), attributes(5)
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