/* Copyright (c) 2010, 2021, Oracle and/or its affiliates.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License, version 2.0,
   as published by the Free Software Foundation.

   This program is also distributed with certain software (including
   but not limited to OpenSSL) that is licensed under separate terms,
   as designated in a particular file or component or in included license
   documentation.  The authors of MySQL hereby grant you an additional
   permission to link the program and your derivative works with the
   separately licensed software that they have included with MySQL.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License, version 2.0, for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA */

/**
  @file windeps/sunrpc/xdr_mem.c
  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 <string.h>
#include <limits.h>
#include <rpc/rpc.h>

static bool_t xdrmem_getlong (XDR *, long *);
static bool_t xdrmem_putlong (XDR *, const long *);
static bool_t xdrmem_getbytes (XDR *, caddr_t, u_int);
static bool_t xdrmem_putbytes (XDR *, const char *, u_int);
static u_int xdrmem_getpos (const XDR *);
static bool_t xdrmem_setpos (XDR *, u_int);
static int32_t *xdrmem_inline (XDR *, u_int);
static void xdrmem_destroy (XDR *);
static bool_t xdrmem_getint32 (XDR *, int32_t *);
static bool_t xdrmem_putint32 (XDR *, const int32_t *);

static const struct xdr_ops xdrmem_ops =
{
  xdrmem_getlong,
  xdrmem_putlong,
  xdrmem_getbytes,
  xdrmem_putbytes,
  xdrmem_getpos,
  xdrmem_setpos,
  xdrmem_inline,
  xdrmem_destroy,
  xdrmem_getint32,
  xdrmem_putint32
};

/*
 * The procedure xdrmem_create initializes a stream descriptor for a
 * memory buffer.
 */
void
xdrmem_create (XDR *xdrs, const caddr_t addr, u_int size, enum xdr_op op)
{
  xdrs->x_op = op;
  /* We have to add the const since the `struct xdr_ops' in `struct XDR'
     is not `const'.  */
  xdrs->x_ops = (struct xdr_ops *) &xdrmem_ops;
  xdrs->x_private = xdrs->x_base = addr;
  xdrs->x_handy = size;
}
INTDEF(xdrmem_create)

/*
 * Nothing needs to be done for the memory case.  The argument is clearly
 * const.
 */

static void
xdrmem_destroy (XDR *xdrs)
{
}

/*
 * Gets the next word from the memory referenced by xdrs and places it
 * in the long pointed to by lp.  It then increments the private word to
 * point at the next element.  Neither object pointed to is const
 */
static bool_t
xdrmem_getlong (XDR *xdrs, long *lp)
{
  if (xdrs->x_handy < 4)
    return FALSE;
  xdrs->x_handy -= 4;
  *lp = (int32_t) ntohl ((*((int32_t *) (xdrs->x_private))));
  xdrs->x_private += 4;
  return TRUE;
}

/*
 * Puts the long pointed to by lp in the memory referenced by xdrs.  It
 * then increments the private word to point at the next element.  The
 * long pointed at is const
 */
static bool_t
xdrmem_putlong (XDR *xdrs, const long *lp)
{
  if (xdrs->x_handy < 4)
    return FALSE;
  xdrs->x_handy -= 4;
  *(int32_t *) xdrs->x_private = htonl (*lp);
  xdrs->x_private += 4;
  return TRUE;
}

/*
 * Gets an unaligned number of bytes from the xdrs structure and writes them
 * to the address passed in addr.  Be very careful when calling this routine
 * as it could leave the xdrs pointing to an unaligned structure which is not
 * a good idea.  None of the things pointed to are const.
 */
static bool_t
xdrmem_getbytes (XDR *xdrs, caddr_t addr, u_int len)
{
  if (xdrs->x_handy < len)
    return FALSE;
  xdrs->x_handy -= len;
  memcpy (addr, xdrs->x_private, len);
  xdrs->x_private += len;
  return TRUE;
}

/*
 * The complementary function to the above.  The same warnings apply about
 * unaligned data.  The source address is const.
 */
static bool_t
xdrmem_putbytes (XDR *xdrs, const char *addr, u_int len)
{
  if (xdrs->x_handy < len)
    return FALSE;
  xdrs->x_handy -= len;
  memcpy (xdrs->x_private, addr, len);
  xdrs->x_private += len;
  return TRUE;
}

/*
 * Not sure what this one does.  But it clearly doesn't modify the contents
 * of xdrs.  **FIXME** does this not assume u_int == u_long?
 */
static u_int
xdrmem_getpos (const XDR *xdrs)
{
  return (u_long) xdrs->x_private - (u_long) xdrs->x_base;
}

/*
 * xdrs modified
 */
static bool_t
xdrmem_setpos (xdrs, pos)
     XDR *xdrs;
     u_int pos;
{
  caddr_t newaddr = xdrs->x_base + pos;
  caddr_t lastaddr = xdrs->x_private + xdrs->x_handy;
  size_t handy = lastaddr - newaddr;

  if (newaddr > lastaddr
      || newaddr < xdrs->x_base
      || handy != (u_int) handy)
    return FALSE;

  xdrs->x_private = newaddr;
  xdrs->x_handy = (u_int) handy;
  return TRUE;
}

/*
 * xdrs modified
 */
static int32_t *
xdrmem_inline (XDR *xdrs, u_int len)
{
  int32_t *buf = 0;

  if (xdrs->x_handy >= len)
    {
      xdrs->x_handy -= len;
      buf = (int32_t *) xdrs->x_private;
      xdrs->x_private += len;
    }
  return buf;
}

/*
 * Gets the next word from the memory referenced by xdrs and places it
 * in the int pointed to by ip.  It then increments the private word to
 * point at the next element.  Neither object pointed to is const
 */
static bool_t
xdrmem_getint32 (XDR *xdrs, int32_t *ip)
{
  if (xdrs->x_handy < 4)
    return FALSE;
  xdrs->x_handy -= 4;
  *ip = ntohl ((*((int32_t *) (xdrs->x_private))));
  xdrs->x_private += 4;
  return TRUE;
}

/*
 * Puts the long pointed to by lp in the memory referenced by xdrs.  It
 * then increments the private word to point at the next element.  The
 * long pointed at is const
 */
static bool_t
xdrmem_putint32 (XDR *xdrs, const int32_t *ip)
{
  if (xdrs->x_handy < 4)
    return FALSE;
  xdrs->x_handy -= 4;
  *(int32_t *) xdrs->x_private = htonl (*ip);
  xdrs->x_private += 4;
  return TRUE;
}
