NAME
xdr_admin, xdr_control, xdr_getpos, xdr_inline, xdrrec_endofrecord, xdrrec_eof, xdrrec_readbytes, xdrrec_skiprecord, xdr_setpos, xdr_sizeof — library routines for external data representation
SYNOPSIS
#include <rpc/xdr.h>
bool_t xdr_control(XDR *xdrs,
int req,
void *info);
u_int xdr_getpos(const XDR *xdrs);
long *xdr_inline(XDR *xdrs,
const int len);
bool_t xdrrec_endofrecord(XDR *xdrs,
int sendnow);
bool_t xdrrec_eof(XDR *xdrs);
int xdrrec_readbytes(XDR *xdrs,
caddr_t addr, u_int nbytes);
bool_t xdrrec_skiprecord(XDR *xdrs);
bool_t xdr_setpos(XDR *xdrs,
const u_int pos);
unsigned long xdr_sizeof(xdrproc_t func,
void *data);
DESCRIPTION
XDR library routines allow C programmers to describe
arbitrary 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 deal specifically with the management of the
XDR stream.
Routines
See
rpc(3N)
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(3C)
be used to allocate these buffers or that the programmer insure
that the buffer address is divisible evenly by four.
- bool_t xdr_control()
A function macro to change or retrieve various information
about an XDR stream.
req
indicates the type of operation and
info
is a pointer to the information.
The supported value of
req
is
XDR_GET_BYTES_AVAIL
and its argument type is
xdr_bytesrec *.
It returns the number of bytes left unconsumed in the stream and a
flag indicating whether or not this is the last fragment.
- u_int 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.
Therefore, applications written for portability should not
depend on this feature.
- long *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 buffer.
Note: 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, and applications written for
portability should not depend on this feature.
- bool_t xdrrec_endofrecord()
This routine can be invoked only on streams created by
xdrrec_create()
(see
xdr_create(3N)).
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
TRUE
if it succeeds,
FALSE
otherwise.
- bool_t 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
TRUE
if there is no more data in the stream's input buffer.
It returns
FALSE
if there is additional data in the stream's input buffer.
- int xdrrec_readbytes()
This routine can be invoked only on streams created by
xdrrec_create().
It attempts to read
nbytes
bytes from the XDR stream into the buffer pointed to by
addr.
Upon success this routine returns the number of bytes read,
-1
on failure.
A return value of
0
indicates an end of record.
- bool_t xdrrec_skiprecord()
This routine can be invoked only on streams created by
xdrrec_create()
(see
xdr_create(3N)).
It tells the XDR implementation that the rest of the current record
in the stream's input buffer should be discarded.
This routine returns
TRUE
if it succeeds,
FALSE
otherwise.
- bool_t 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
TRUE
if the XDR stream was repositioned, and
FALSE
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.
Therefore, applications written for
portability should not depend on this feature.
- unsigned long xdr_sizeof()
This routine returns the number of bytes required to encode
data
using the XDR filter function
func,
excluding potential overhead such as RPC headers or record markers.
0
(zero) is returned on error.
This information might be used to select between transport protocols,
or to determine the buffer size for various lower levels of RPC
client and server creation routines, or to allocate storage when XDR
is used outside of the RPC subsystem.
MULTITHREAD USAGE
- Thread Safe:
Yes
- Cancel Safe:
Yes
- Fork Safe:
No
- Async-cancel Safe:
No
- Async-signal Safe:
No
These functions can be called safely in a multithreaded environment.
They may be cancellation points in that they call functions that are
cancel points.
In a multithreaded environment, these functions are
not safe to be called by a child process after
fork()
and before
exec().
These functions should not be called by a multithreaded application
that supports asynchronous cancellation or asynchronous signals.
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