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man:xdrmem_create

XDR(3) Linux Programmer's Manual XDR(3)

NAME

     xdr - library routines for external data representation

SYNOPSIS AND DESCRIPTION

     These  routines  allow  C programmers to describe arbitrary data struc-
     tures in a machine-independent  fashion.   Data  for  remote  procedure
     calls are transmitted using these routines.
     The  prototypes  below  are declared in <rpc/xdr.h> and make use of the
     following types:
         typedef int bool_t;
     typedef bool_t (*xdrproc_t) (XDR *, void *,...);
     For the declaration of the XDR type, see <rpc/xdr.h>.
     bool_t xdr_array(XDR *xdrs, char **arrp, unsigned int *sizep,
                      unsigned int maxsize, unsigned int elsize,
                      xdrproc_t elproc);
            A  filter  primitive  that  translates  between  variable-length
            arrays  and  their  corresponding external representations.  The
            argument 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 argument 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 one if it suc-
            ceeds, zero 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  one  or  zero.   This  routine
            returns one if it succeeds, zero otherwise.
     bool_t xdr_bytes(XDR *xdrs, char **sp, unsigned int *sizep,
                      unsigned int maxsize);
            A  filter primitive that translates between counted byte strings
            and their external representations.   The  argument  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 one if it succeeds, zero otherwise.
     bool_t xdr_char(XDR *xdrs, char *cp);
            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   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  invok-
            ing 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 one if it succeeds, zero 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 one if it succeeds, zero otherwise.
     bool_t xdr_float(XDR *xdrs, float *fp);
            A  filter  primitive  that translates between C floats and their
            external representations.  This routine returns one if  it  suc-
            ceeds, zero otherwise.
     void xdr_free(xdrproc_t proc, char *objp);
            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).
     unsigned 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  desir-
            able feature of XDR streams is that simple arithmetic works with
            this number, although the XDR stream instances need not  guaran-
            tee this.
     long *xdr_inline(XDR *xdrs, int len);
            A  macro that invokes the inline 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.
     bool_t xdr_int(XDR *xdrs, int *ip);
            A filter primitive that translates between C integers and  their
            external  representations.   This routine returns one if it suc-
            ceeds, zero 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 one if it
            succeeds, zero otherwise.
     void xdrmem_create(XDR *xdrs, char *addr, unsigned 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).
     bool_t xdr_opaque(XDR *xdrs, char *cp, unsigned int cnt);
            A filter primitive that translates  between  fixed  size  opaque
            data  and  its  external representation.  The argument cp is the
            address of the opaque object, and cnt  is  its  size  in  bytes.
            This routine returns one if it succeeds, zero otherwise.
     bool_t xdr_pointer(XDR *xdrs, char **objpp,
                        unsigned int objsize, xdrproc_t xdrobj);
            Like  xdr_reference()  except  that it serializes null pointers,
            whereas xdr_reference() does not.  Thus, xdr_pointer() can  rep-
            resent recursive data structures, such as binary trees or linked
            lists.
     void xdrrec_create(XDR *xdrs, unsigned int sendsize,
                        unsigned int recvsize, char *handle,
                        int (*readit) (char *, char *, int),
                        int (*writeit) (char *, char *, int));
            This routine initializes the XDR stream  object  pointed  to  by
            xdrs.   The  stream's  data is written to a buffer of size send-
            size; a value of zero indicates the system should use a suitable
            default.   The stream's data is read from a buffer of size recv-
            size; 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,  rea-
            dit 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 argument.  Note: the
            XDR stream's op field must be set by the caller.
            Warning: to read from an XDR stream created by this API,  you'll
            need  to call xdrrec_skiprecord() first before calling any other
            XDR APIs.  This inserts additional bytes in the stream  to  pro-
            vide  record  boundary  information.   Also, XDR streams created
            with different xdr*_create APIs are not compatible for the  same
            reason.
     bool_t xdrrec_endofrecord(XDR *xdrs, int sendnow);
            This  routine  can  be  invoked  only on streams created by xdr-
            rec_create().  The data in the output buffer is marked as a com-
            pleted  record,  and the output buffer is optionally written out
            if sendnow is nonzero.  This routine returns one if it succeeds,
            zero otherwise.
     bool_t xdrrec_eof(XDR *xdrs);
            This  routine  can  be  invoked  only on streams created by xdr-
            rec_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.
     bool_t xdrrec_skiprecord(XDR *xdrs);
            This routine can be invoked only  on  streams  created  by  xdr-
            rec_create().   It tells the XDR implementation that the rest of
            the current record in the stream's input buffer should  be  dis-
            carded.   This  routine  returns one if it succeeds, zero other-
            wise.
     bool_t xdr_reference(XDR *xdrs, char **pp, unsigned int size,
                          xdrproc_t proc);
            A primitive that provides  pointer  chasing  within  structures.
            The  argument  pp  is  the  address  of the pointer; size is the
            sizeof the structure that *pp points to; and proc is an XDR pro-
            cedure  that  filters  the  structure between its C form and its
            external representation.  This routine returns one  if  it  suc-
            ceeds, zero otherwise.
            Warning:  this  routine  does not understand null pointers.  Use
            xdr_pointer() instead.
     xdr_setpos(XDR *xdrs, unsigned int pos);
            A macro that invokes the set position  routine  associated  with
            the  XDR  stream  xdrs.   The  argument  pos is a position value
            obtained from xdr_getpos().  This routine returns one if the XDR
            stream could be repositioned, and zero 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 one if  it
            succeeds, zero 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
            stdio  stream file.  The argument 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(3) on the file stream, but never fclose(3).
     bool_t xdr_string(XDR *xdrs, char **sp, unsigned 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 one if it succeeds,  zero  other-
            wise.
     bool_t xdr_u_char(XDR *xdrs, unsigned char *ucp);
            A filter primitive that translates between unsigned C characters
            and their external representations.  This routine returns one if
            it succeeds, zero 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 one if
            it succeeds, zero otherwise.
     bool_t xdr_u_long(XDR *xdrs, unsigned long *ulp);
            A filter primitive that translates between C unsigned long inte-
            gers and their external representations.  This  routine  returns
            one if it succeeds, zero 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 one if it succeeds, zero otherwise.
     bool_t xdr_union(XDR *xdrs, int *dscmp, char *unp,
                      struct xdr_discrim *choices,
                      xdrproc_t defaultarm);     /* may equal NULL */
            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 argument 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 one if it succeeds, zero otherwise.
     bool_t xdr_vector(XDR *xdrs, char *arrp, unsigned int size,
                       unsigned int elsize, xdrproc_t elproc);
            A filter primitive that translates between  fixed-length  arrays
            and  their corresponding external representations.  The argument
            arrp is the address of the pointer to the array, while  size  is
            the  element  count  of  the  array.  The argument 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 one  if  it  suc-
            ceeds, zero otherwise.
     bool_t xdr_void(void);
            This  routine  always returns one.  It may be passed to RPC rou-
            tines that require a function argument, where nothing is  to  be
            done.
     bool_t xdr_wrapstring(XDR *xdrs, char **sp);
            A  primitive  that  calls  xdr_string(xdrs, sp,MAXUN.UNSIGNED );
            where MAXUN.UNSIGNED is the maximum value of an  unsigned  inte-
            ger.  xdr_wrapstring() is handy because the RPC package passes a
            maximum of two XDR routines as arguments, and xdr_string(),  one
            of the most frequently used primitives, requires three.  Returns
            one if it succeeds, zero otherwise.

ATTRIBUTES

     For  an  explanation  of  the  terms  used   in   this   section,   see
     attributes(7).
     allbox;  lbw31  lb lb l l l.  Interface Attribute Value T{ xdr_array(),
     xdr_bool(),
     xdr_bytes(), xdr_char(),
     xdr_destroy(), xdr_double(),
     xdr_enum(), xdr_float(),
     xdr_free(), xdr_getpos(),
     xdr_inline(), xdr_int(),
     xdr_long(), xdrmem_create(),
     xdr_opaque(), xdr_pointer(),
     xdrrec_create(), xdrrec_eof(),
     xdrrec_endofrecord(),
     xdrrec_skiprecord(),
     xdr_reference(), xdr_setpos(),
     xdr_short(), xdrstdio_create(),
     xdr_string(), xdr_u_char(),
     xdr_u_int(), xdr_u_long(),
     xdr_u_short(), xdr_union(),
     xdr_vector(), xdr_void(),
     xdr_wrapstring() T}   Thread safety  MT-Safe

SEE ALSO

     rpc(3)
     The following manuals:
            eXternal Data Representation Standard: Protocol Specification
            eXternal Data Representation: Sun Technical Notes
            XDR:  External  Data  Representation  Standard,  RFC 1014,   Sun
            Microsystems, Inc., USC-ISI.

COLOPHON

     This  page  is  part of release 4.16 of the Linux man-pages project.  A
     description of the project, information about reporting bugs,  and  the
     latest     version     of     this    page,    can    be    found    at
     https://www.kernel.org/doc/man-pages/.
                                2017-09-15                            XDR(3)
/data/webs/external/dokuwiki/data/pages/man/xdrmem_create.txt · Last modified: 2019/05/17 09:32 by 127.0.0.1

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