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freebsd/sys/rpc/xdr.h
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Brooks Davis ac5a19ec69 rpc/xdr.h: make xdrproc_t always take two arguments 
The type of xdrproc_t is clearly defined in the comments as a function
with two arguments, an XDR * and a void * (sometimes spelled caddr_t).
It was initialy defined as:

	typedef bool_t (*xdrproc_t)();

At some point people started giving it a non-empty argument list.
Unfortunatly, there has been widespread disagreement about how arguments
are passed.  There seems to have been a widespread view that it should
be allowed to pass three argument function pointer to xdrproc_t.  Most
notable is xdr_string which takes a maximum length parameter. This lead
to all sorts of prototypes (all of which have been present in the
FreeBSD source tree):

FreeBSD userspace (nominally from tirpc, but seemingly local):
	typedef bool_t (*xdrproc_t)(XDR *, ...);
FreeBSD kernel, glibc:
	typedef bool_t (*xdrproc_t)(XDR *, void *, ...);
rcp/xdr.h with _KERNEL defined (not used?):
	typedef bool_t (*xdrproc_t)(XDR *, void *, u_int);
gssrpc (in krb5) and Linux kernel:
	typedef bool_t (*xdrproc_t)(XDR *, void *);

For two argument functions on current ABIs, these all equivalent as
these arguments are passed in registers regardless of decleration and
definition, but we end up with two problems:

   - xdr_free((xdrproc_t)xdr_string, ...) calls xdr_string with no third
     argument and (at least on FreeBSD) may fail to free memory if the
     string is shorter than the value lying around in the third argument
     register.  There are no instance of this in tree, but I found some
     with Debian code search, in particular in OpenAFS.

   - Under CheriABI, variadic arguments are passed in a separate,
     bounded array so theses prototypes aren't equilvalent to the
     non-variadic calling convention of the functions.

The reality is that that xdr_string should not be cast to xdrproc_t and
xdr_wrapstring should be used instead so we do not need to support this
case.  Instances of the former behavior are now extremely rare.

With this change we bring FreeBSD in line with gssrpc and the Linux
Kernel.  Warnings about casts should now be correct and should be fixed.

Bump __FreeBSD_version as some software required adaptation if it is
declaring functions to cast to xdrproc_t.  Update OpenZFS's workaround
of this historic mess accordingly.

Effort:		CHERI upstreaming
Sponsored by:	Innovate UK

Reviewed by:	kib
Differential Revision:	https://reviews.freebsd.org/D54824
2026-01-23 10:35:32 +00:00

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/* $NetBSD: xdr.h,v 1.19 2000/07/17 05:00:45 matt Exp $ */
/*-
* SPDX-License-Identifier: BSD-3-Clause
*
* Copyright (c) 2009, Sun Microsystems, Inc.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
* - Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* - Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
* - Neither the name of Sun Microsystems, Inc. nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
/*
* xdr.h, External Data Representation Serialization Routines.
*
* Copyright (C) 1984, Sun Microsystems, Inc.
*/
#ifndef _KRPC_XDR_H
#define _KRPC_XDR_H
#include <sys/cdefs.h>
struct mbuf;
/*
* XDR provides a conventional way for converting between C data
* types and an external bit-string representation. Library supplied
* routines provide for the conversion on built-in C data types. These
* routines and utility routines defined here are used to help implement
* a type encode/decode routine for each user-defined type.
*
* Each data type provides a single procedure which takes two arguments:
*
* bool_t
* xdrproc(xdrs, argresp)
* XDR *xdrs;
* <type> *argresp;
*
* xdrs is an instance of a XDR handle, to which or from which the data
* type is to be converted. argresp is a pointer to the structure to be
* converted. The XDR handle contains an operation field which indicates
* which of the operations (ENCODE, DECODE * or FREE) is to be performed.
*
* XDR_DECODE may allocate space if the pointer argresp is null. This
* data can be freed with the XDR_FREE operation.
*
* We write only one procedure per data type to make it easy
* to keep the encode and decode procedures for a data type consistent.
* In many cases the same code performs all operations on a user defined type,
* because all the hard work is done in the component type routines.
* decode as a series of calls on the nested data types.
*/
/*
* Xdr operations. XDR_ENCODE causes the type to be encoded into the
* stream. XDR_DECODE causes the type to be extracted from the stream.
* XDR_FREE can be used to release the space allocated by an XDR_DECODE
* request.
*/
enum xdr_op {
XDR_ENCODE=0,
XDR_DECODE=1,
XDR_FREE=2
};
/*
* This is the number of bytes per unit of external data.
*/
#define BYTES_PER_XDR_UNIT (4)
#define RNDUP(x) ((((x) + BYTES_PER_XDR_UNIT - 1) / BYTES_PER_XDR_UNIT) \
* BYTES_PER_XDR_UNIT)
/*
* The XDR handle.
* Contains operation which is being applied to the stream,
* an operations vector for the particular implementation (e.g. see xdr_mem.c),
* and two private fields for the use of the particular implementation.
*/
typedef struct XDR {
enum xdr_op x_op; /* operation; fast additional param */
const struct xdr_ops {
/* get a long from underlying stream */
bool_t (*x_getlong)(struct XDR *, long *);
/* put a long to " */
bool_t (*x_putlong)(struct XDR *, const long *);
/* get some bytes from " */
bool_t (*x_getbytes)(struct XDR *, char *, u_int);
/* put some bytes to " */
bool_t (*x_putbytes)(struct XDR *, const char *, u_int);
/* put mbuf or copy its bytes */
bool_t (*x_putmbuf)(struct XDR *, struct mbuf *);
/* returns bytes off from beginning */
u_int (*x_getpostn)(struct XDR *);
/* lets you reposition the stream */
bool_t (*x_setpostn)(struct XDR *, u_int);
/* buf quick ptr to buffered data */
int32_t *(*x_inline)(struct XDR *, u_int);
/* free privates of this xdr_stream */
void (*x_destroy)(struct XDR *);
bool_t (*x_control)(struct XDR *, int, void *);
} *x_ops;
char * x_public; /* users' data */
void * x_private; /* pointer to private data */
char * x_base; /* private used for position info */
u_int x_handy; /* extra private word */
} XDR;
/*
* A xdrproc_t exists for each data type which is to be encoded or decoded.
*
* The second argument to the xdrproc_t is a pointer to an opaque pointer.
* The opaque pointer generally points to a structure of the data type
* to be decoded. If this pointer is 0, then the type routines should
* allocate dynamic storage of the appropriate size and return it.
*/
typedef bool_t (*xdrproc_t)(XDR *, void *);
/*
* Operations defined on a XDR handle
*
* XDR *xdrs;
* long *longp;
* char * addr;
* u_int len;
* u_int pos;
*/
#define XDR_GETLONG(xdrs, longp) \
(*(xdrs)->x_ops->x_getlong)(xdrs, longp)
#define xdr_getlong(xdrs, longp) \
(*(xdrs)->x_ops->x_getlong)(xdrs, longp)
#define XDR_PUTLONG(xdrs, longp) \
(*(xdrs)->x_ops->x_putlong)(xdrs, longp)
#define xdr_putlong(xdrs, longp) \
(*(xdrs)->x_ops->x_putlong)(xdrs, longp)
static __inline int
xdr_getint32(XDR *xdrs, int32_t *ip)
{
long l;
if (!xdr_getlong(xdrs, &l))
return (FALSE);
*ip = (int32_t)l;
return (TRUE);
}
static __inline int
xdr_putint32(XDR *xdrs, int32_t *ip)
{
long l;
l = (long)*ip;
return xdr_putlong(xdrs, &l);
}
#define XDR_GETINT32(xdrs, int32p) xdr_getint32(xdrs, int32p)
#define XDR_PUTINT32(xdrs, int32p) xdr_putint32(xdrs, int32p)
#define XDR_GETBYTES(xdrs, addr, len) \
(*(xdrs)->x_ops->x_getbytes)(xdrs, addr, len)
#define xdr_getbytes(xdrs, addr, len) \
(*(xdrs)->x_ops->x_getbytes)(xdrs, addr, len)
#define XDR_PUTBYTES(xdrs, addr, len) \
(*(xdrs)->x_ops->x_putbytes)(xdrs, addr, len)
#define xdr_putbytes(xdrs, addr, len) \
(*(xdrs)->x_ops->x_putbytes)(xdrs, addr, len)
#define XDR_PUTMBUF(xdrs, mbuf) \
(*(xdrs)->x_ops->x_putmbuf)(xdrs, mbuf)
#define xdr_putmbuf(xdrs, mbuf) \
(*(xdrs)->x_ops->x_putmbuf)(xdrs, mbuf)
#define XDR_GETPOS(xdrs) \
(*(xdrs)->x_ops->x_getpostn)(xdrs)
#define xdr_getpos(xdrs) \
(*(xdrs)->x_ops->x_getpostn)(xdrs)
#define XDR_SETPOS(xdrs, pos) \
(*(xdrs)->x_ops->x_setpostn)(xdrs, pos)
#define xdr_setpos(xdrs, pos) \
(*(xdrs)->x_ops->x_setpostn)(xdrs, pos)
#define XDR_INLINE(xdrs, len) \
(*(xdrs)->x_ops->x_inline)(xdrs, len)
#define xdr_inline(xdrs, len) \
(*(xdrs)->x_ops->x_inline)(xdrs, len)
#define XDR_DESTROY(xdrs) \
if ((xdrs)->x_ops->x_destroy) \
(*(xdrs)->x_ops->x_destroy)(xdrs)
#define xdr_destroy(xdrs) \
if ((xdrs)->x_ops->x_destroy) \
(*(xdrs)->x_ops->x_destroy)(xdrs)
#define XDR_CONTROL(xdrs, req, op) \
(((xdrs)->x_ops->x_control == NULL) ? (FALSE) : \
(*(xdrs)->x_ops->x_control)(xdrs, req, op))
#define xdr_control(xdrs, req, op) XDR_CONTROL(xdrs, req, op)
/*
* Solaris strips the '_t' from these types -- not sure why.
* But, let's be compatible.
*/
#define xdr_rpcvers(xdrs, versp) xdr_uint32_t(xdrs, versp)
#define xdr_rpcprog(xdrs, progp) xdr_uint32_t(xdrs, progp)
#define xdr_rpcproc(xdrs, procp) xdr_uint32_t(xdrs, procp)
#define xdr_rpcprot(xdrs, protp) xdr_uint32_t(xdrs, protp)
#define xdr_rpcport(xdrs, portp) xdr_uint32_t(xdrs, portp)
/*
* Support struct for discriminated unions.
* You create an array of xdrdiscrim structures, terminated with
* an entry with a null procedure pointer. The xdr_union routine gets
* the discriminant value and then searches the array of structures
* for a matching value. If a match is found the associated xdr routine
* is called to handle that part of the union. If there is
* no match, then a default routine may be called.
* If there is no match and no default routine it is an error.
*/
#define NULL_xdrproc_t ((xdrproc_t)0)
struct xdr_discrim {
int value;
xdrproc_t proc;
};
/*
* In-line routines for fast encode/decode of primitive data types.
* Caveat emptor: these use single memory cycles to get the
* data from the underlying buffer, and will fail to operate
* properly if the data is not aligned. The standard way to use these
* is to say:
* if ((buf = XDR_INLINE(xdrs, count)) == NULL)
* return (FALSE);
* <<< macro calls >>>
* where ``count'' is the number of bytes of data occupied
* by the primitive data types.
*
* N.B. and frozen for all time: each data type here uses 4 bytes
* of external representation.
*/
#define IXDR_GET_INT32(buf) ((int32_t)__ntohl((uint32_t)*(buf)++))
#define IXDR_PUT_INT32(buf, v) (*(buf)++ =(int32_t)__htonl((uint32_t)v))
#define IXDR_GET_U_INT32(buf) ((uint32_t)IXDR_GET_INT32(buf))
#define IXDR_PUT_U_INT32(buf, v) IXDR_PUT_INT32((buf), ((int32_t)(v)))
#define IXDR_GET_UINT32(buf) ((uint32_t)IXDR_GET_INT32(buf))
#define IXDR_PUT_UINT32(buf, v) IXDR_PUT_INT32((buf), ((int32_t)(v)))
#define IXDR_GET_LONG(buf) ((long)__ntohl((uint32_t)*(buf)++))
#define IXDR_PUT_LONG(buf, v) (*(buf)++ =(int32_t)__htonl((uint32_t)v))
#define IXDR_GET_BOOL(buf) ((bool_t)IXDR_GET_LONG(buf))
#define IXDR_GET_ENUM(buf, t) ((t)IXDR_GET_LONG(buf))
#define IXDR_GET_U_LONG(buf) ((u_long)IXDR_GET_LONG(buf))
#define IXDR_GET_SHORT(buf) ((short)IXDR_GET_LONG(buf))
#define IXDR_GET_U_SHORT(buf) ((u_short)IXDR_GET_LONG(buf))
#define IXDR_PUT_BOOL(buf, v) IXDR_PUT_LONG((buf), (v))
#define IXDR_PUT_ENUM(buf, v) IXDR_PUT_LONG((buf), (v))
#define IXDR_PUT_U_LONG(buf, v) IXDR_PUT_LONG((buf), (v))
#define IXDR_PUT_SHORT(buf, v) IXDR_PUT_LONG((buf), (v))
#define IXDR_PUT_U_SHORT(buf, v) IXDR_PUT_LONG((buf), (v))
/*
* These are the "generic" xdr routines.
*/
__BEGIN_DECLS
extern bool_t xdr_void(XDR *, void *);
extern bool_t xdr_int(XDR *, int *);
extern bool_t xdr_u_int(XDR *, u_int *);
extern bool_t xdr_long(XDR *, long *);
extern bool_t xdr_u_long(XDR *, u_long *);
extern bool_t xdr_short(XDR *, short *);
extern bool_t xdr_u_short(XDR *, u_short *);
extern bool_t xdr_int16_t(XDR *, int16_t *);
extern bool_t xdr_uint16_t(XDR *, uint16_t *);
extern bool_t xdr_int32_t(XDR *, int32_t *);
extern bool_t xdr_uint32_t(XDR *, uint32_t *);
extern bool_t xdr_int64_t(XDR *, int64_t *);
extern bool_t xdr_uint64_t(XDR *, uint64_t *);
extern bool_t xdr_bool(XDR *, bool_t *);
extern bool_t xdr_enum(XDR *, enum_t *);
extern bool_t xdr_array(XDR *, char **, u_int *, u_int, u_int, xdrproc_t);
extern bool_t xdr_bytes(XDR *, char **, u_int *, u_int);
extern bool_t xdr_opaque(XDR *, char *, u_int);
extern bool_t xdr_string(XDR *, char **, u_int);
extern bool_t xdr_union(XDR *, enum_t *, char *, const struct xdr_discrim *, xdrproc_t);
extern bool_t xdr_char(XDR *, char *);
extern bool_t xdr_u_char(XDR *, u_char *);
extern bool_t xdr_vector(XDR *, char *, u_int, u_int, xdrproc_t);
extern bool_t xdr_float(XDR *, float *);
extern bool_t xdr_double(XDR *, double *);
extern bool_t xdr_quadruple(XDR *, long double *);
extern bool_t xdr_reference(XDR *, char **, u_int, xdrproc_t);
extern bool_t xdr_pointer(XDR *, char **, u_int, xdrproc_t);
extern bool_t xdr_wrapstring(XDR *, char **);
extern void xdr_free(xdrproc_t, void *);
extern bool_t xdr_hyper(XDR *, quad_t *);
extern bool_t xdr_u_hyper(XDR *, u_quad_t *);
extern bool_t xdr_longlong_t(XDR *, quad_t *);
extern bool_t xdr_u_longlong_t(XDR *, u_quad_t *);
extern unsigned long xdr_sizeof(xdrproc_t func, void *data);
__END_DECLS
/*
* Common opaque bytes objects used by many rpc protocols;
* declared here due to commonality.
*/
#define MAX_NETOBJ_SZ 1024
struct netobj {
u_int n_len;
char *n_bytes;
};
typedef struct netobj netobj;
extern bool_t xdr_netobj(XDR *, struct netobj *);
/*
* These are XDR control operators
*/
#define XDR_GET_BYTES_AVAIL 1
#define XDR_PEEK 2
#define XDR_SKIPBYTES 3
struct xdr_bytesrec {
bool_t xc_is_last_record;
size_t xc_num_avail;
};
typedef struct xdr_bytesrec xdr_bytesrec;
/*
* These are the public routines for the various implementations of
* xdr streams.
*/
__BEGIN_DECLS
/* XDR using memory buffers */
extern void xdrmem_create(XDR *, char *, u_int, enum xdr_op);
/* XDR using mbufs */
extern void xdrmbuf_create(XDR *, struct mbuf *, enum xdr_op);
extern struct mbuf * xdrmbuf_getall(XDR *);
/* XDR pseudo records for tcp */
extern void xdrrec_create(XDR *, u_int, u_int, void *,
int (*)(void *, void *, int),
int (*)(void *, void *, int));
/* make end of xdr record */
extern bool_t xdrrec_endofrecord(XDR *, int);
/* move to beginning of next record */
extern bool_t xdrrec_skiprecord(XDR *);
/* true if no more input */
extern bool_t xdrrec_eof(XDR *);
extern u_int xdrrec_readbytes(XDR *, caddr_t, u_int);
__END_DECLS
#endif /* !_KRPC_XDR_H */
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