src/xdr_mem.c

/*
 * 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.
 */

#include <config.h>
#include <sys/cdefs.h>

/*
 * xdr_mem.h, XDR implementation using memory buffers.
 *
 * Copyright (C) 1984, Sun Microsystems, Inc.
 *
 * If you have some data to be interpreted as external data representation
 * or to be converted to external data representation in a memory buffer,
 * then this is the package for you.
 *
 */

#include "namespace.h"
#include <sys/types.h>
#if !defined(_WIN32)
#include <netinet/in.h>
#endif

#include <string.h>

#include <rpc/types.h>
#include <misc/portable.h>
#include <rpc/xdr.h>
#include "un-namespace.h"

typedef bool (*dummyfunc3)(XDR *, int, void *);
typedef bool (*dummy_getbufs)(XDR *, xdr_uio *, u_int);
typedef bool (*dummy_putbufs)(XDR *, xdr_uio *, u_int);

static const struct xdr_ops xdrmem_ops_aligned;
static const struct xdr_ops xdrmem_ops_unaligned;

/*
 * The procedure xdrmem_create initializes a stream descriptor for a
 * memory buffer.
 */
void
xdrmem_ncreate(XDR *xdrs, char *addr, u_int size, enum xdr_op op)
{
	xdrs->x_op = op;
	if ((uintptr_t)addr & (sizeof(int32_t) - 1)) {
		xdrs->x_ops = &xdrmem_ops_unaligned;
	} else {
		xdrs->x_ops = &xdrmem_ops_aligned;
		xdrs->x_flags = XDR_FLAG_VIO;
	}
	xdrs->x_public = NULL;
	xdrs->x_private = NULL;
	xdrs->x_lib[0] = NULL;
	xdrs->x_lib[1] = NULL;
	xdrs->x_data = addr;
	xdrs->x_v.vio_base = addr;
	xdrs->x_v.vio_head = addr;
	switch (op) {
	case XDR_ENCODE:
		xdrs->x_v.vio_tail = addr;
		break;
	case XDR_DECODE:
		xdrs->x_v.vio_tail = addr + size;
		break;
	default:
		abort();
		break;
	};
	xdrs->x_v.vio_wrap = addr + size;
	xdrs->x_base = &xdrs->x_v;
}

static bool
xdrmem_getlong_aligned(XDR *xdrs, long *lp)
{
	void *future = xdrs->x_data + sizeof(uint32_t);

	if (future > xdrs->x_v.vio_tail)
		return (false);
	*lp = ntohl(*(u_int32_t *) xdrs->x_data);
	xdrs->x_data = future;
	return (true);
}

static bool
xdrmem_putlong_aligned(XDR *xdrs, const long *lp)
{
	void *future = xdrs->x_data + sizeof(uint32_t);

	if (future > xdrs->x_v.vio_wrap)
		return (false);
	*(u_int32_t *) xdrs->x_data = htonl((u_int32_t) *lp);
	xdrs->x_data = future;
	return (true);
}

/* in glibc 2.14+ x86_64, memcpy no longer tries to handle overlapping areas,
 * see Fedora Bug 691336 (NOTABUG); we dont permit overlapping segments,
 * so memcpy may be a small win over memmove.
 */

static bool
xdrmem_getlong_unaligned(XDR *xdrs, long *lp)
{
	u_int32_t l;
	void *future = xdrs->x_data + sizeof(uint32_t);

	if (future > xdrs->x_v.vio_tail)
		return (false);
	memcpy(&l, xdrs->x_data, sizeof(int32_t));
	*lp = ntohl(l);
	xdrs->x_data = future;
	return (true);
}

static bool
xdrmem_putlong_unaligned(XDR *xdrs, const long *lp)
{
	u_int32_t l;
	void *future = xdrs->x_data + sizeof(uint32_t);

	if (future > xdrs->x_v.vio_wrap)
		return (false);
	l = htonl((u_int32_t) *lp);
	memcpy(xdrs->x_data, &l, sizeof(int32_t));
	xdrs->x_data = future;
	return (true);
}

static bool
xdrmem_getbytes(XDR *xdrs, char *addr, u_int len)
{
	void *future = xdrs->x_data + len;

	if (future > xdrs->x_v.vio_tail)
		return (false);
	memmove(addr, xdrs->x_data, len);
	xdrs->x_data = future;
	return (true);
}

static bool
xdrmem_putbytes(XDR *xdrs, const char *addr, u_int len)
{
	void *future = xdrs->x_data + len;

	if (future > xdrs->x_v.vio_wrap)
		return (false);
	memmove(xdrs->x_data, addr, len);
	xdrs->x_data = future;
	return (true);
}

static u_int
xdrmem_getpos(XDR *xdrs)
{
	/* update the most recent data length, just in case */
	xdr_tail_update(xdrs);

	return ((uintptr_t)xdrs->x_data - (uintptr_t)xdrs->x_v.vio_head);
}

static bool
xdrmem_setpos(XDR *xdrs, u_int pos)
{
	void *newaddr = xdrs->x_v.vio_head + pos;

	/* update the most recent data length, just in case */
	xdr_tail_update(xdrs);

	if (newaddr > xdrs->x_v.vio_wrap)
		return (false);
	xdrs->x_data = newaddr;
	return (true);
}

static int32_t *
xdrmem_inline_aligned(XDR *xdrs, u_int len)
{
	int32_t *buf = (int32_t *)xdrs->x_data;
	void *future = xdrs->x_data + len;

	switch (xdrs->x_op) {
	case XDR_ENCODE:
		if (future <= xdrs->x_v.vio_wrap) {
			xdrs->x_data = future;
			xdr_tail_update(xdrs);
			/* temporarily backward compatible */
			xdrs->x_handy = xdrs->x_v.vio_wrap - xdrs->x_data;
			return (buf);
		}
		break;
	case XDR_DECODE:
		/* re-consuming bytes in a stream
		 * (after SETPOS/rewind) */
		if (future <= xdrs->x_v.vio_tail) {
			xdrs->x_data = future;
			/* temporarily backward compatible */
			xdrs->x_handy = xdrs->x_v.vio_tail - xdrs->x_data;
			return (buf);
		}
		break;
	default:
		abort();
		break;
	};

	return (NULL);
}

/* ARGSUSED */
static int32_t *
xdrmem_inline_unaligned(XDR *xdrs, u_int len)
{
	return (NULL);
}

/* ARGSUSED */
static void xdrmem_destroy(XDR *xdrs)
{
}

static bool
xdrmem_noop(void)
{
	return (false);
}

static const struct xdr_ops xdrmem_ops_aligned = {
	xdrmem_getlong_aligned,
	xdrmem_putlong_aligned,
	xdrmem_getbytes,
	xdrmem_putbytes,
	xdrmem_getpos,
	xdrmem_setpos,
	xdrmem_inline_aligned,
	xdrmem_destroy,
	(dummyfunc3) xdrmem_noop,	/* x_control */
	(dummy_getbufs) xdrmem_noop,	/* x_getbufs */
	(dummy_putbufs) xdrmem_noop,	/* x_putbufs */
};

static const struct xdr_ops xdrmem_ops_unaligned = {
	xdrmem_getlong_unaligned,
	xdrmem_putlong_unaligned,
	xdrmem_getbytes,
	xdrmem_putbytes,
	xdrmem_getpos,
	xdrmem_setpos,
	xdrmem_inline_unaligned,
	xdrmem_destroy,
	(dummyfunc3) xdrmem_noop,	/* x_control */
	(dummy_getbufs) xdrmem_noop,	/* x_getbufs */
	(dummy_putbufs) xdrmem_noop,	/* x_putbufs */
};