/*      $NetBSD: libelf_xlate.c,v 1.5 2024/03/03 17:37:34 christos Exp $        */

/*-
* Copyright (c) 2006,2008 Joseph Koshy
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
*    notice, this list of conditions and the following disclaimer.
* 2. 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.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
*/

#if HAVE_NBTOOL_CONFIG_H
# include "nbtool_config.h"
#endif

#include <sys/cdefs.h>

#include <assert.h>
#include <libelf.h>

#include "_libelf.h"

__RCSID("$NetBSD: libelf_xlate.c,v 1.5 2024/03/03 17:37:34 christos Exp $");
ELFTC_VCSID("Id: libelf_xlate.c 3977 2022-05-01 06:45:34Z jkoshy");

/*
* Translate to/from the file representation of ELF objects.
*
* Translation could potentially involve the following
* transformations:
*
* - an endianness conversion,
* - a change of layout, as the file representation of ELF objects
*   can differ from their in-memory representation.
* - a change in representation due to a layout version change.
*/

Elf_Data *
_libelf_xlate(Elf_Data *dst, const Elf_Data *src, unsigned int encoding,
   int elfclass, int elfmachine, int direction)
{
       int byteswap;
       size_t cnt, dsz, fsz, msz;
       uintptr_t sb, se, db, de;
       _libelf_translator_function *xlator;

       if (encoding == ELFDATANONE)
               encoding = LIBELF_PRIVATE(byteorder);

       if ((encoding != ELFDATA2LSB && encoding != ELFDATA2MSB) ||
           dst == NULL || src == NULL || dst == src)   {
               LIBELF_SET_ERROR(ARGUMENT, 0);
               return (NULL);
       }

       assert(elfclass == ELFCLASS32 || elfclass == ELFCLASS64);
       assert(direction == ELF_TOFILE || direction == ELF_TOMEMORY);

       if (dst->d_version != src->d_version) {
               LIBELF_SET_ERROR(UNIMPL, 0);
               return (NULL);
       }

       if  (src->d_buf == NULL || dst->d_buf == NULL) {
               LIBELF_SET_ERROR(DATA, 0);
               return (NULL);
       }

       if ((int) src->d_type < 0 || src->d_type >= ELF_T_NUM) {
               LIBELF_SET_ERROR(DATA, 0);
               return (NULL);
       }

       if ((fsz = (elfclass == ELFCLASS32 ? elf32_fsize : elf64_fsize)
           (src->d_type, (size_t) 1, src->d_version)) == 0)
               return (NULL);

       if ((msz = _libelf_msize(src->d_type, elfclass, src->d_version)) == 0)
               return (NULL);

       if (src->d_size % (direction == ELF_TOMEMORY ? fsz : msz)) {
               LIBELF_SET_ERROR(DATA, 0);
               return (NULL);
       }

       /*
        * Determine the number of objects that need to be converted, and
        * the space required for the converted objects in the destination
        * buffer.
        */
       if (direction == ELF_TOMEMORY) {
               cnt = (size_t) src->d_size / fsz;
               dsz = cnt * msz;
       } else {
               cnt = (size_t) src->d_size / msz;
               dsz = cnt * fsz;
       }

       if (dst->d_size  <  dsz) {
               LIBELF_SET_ERROR(DATA, 0);
               return (NULL);
       }

       sb = (uintptr_t) src->d_buf;
       se = sb + (size_t) src->d_size;
       db = (uintptr_t) dst->d_buf;
       de = db + (size_t) dst->d_size;

       /*
        * Check for overlapping buffers.  Note that db == sb is
        * allowed.
        */
       if (db != sb && de > sb && se > db) {
               LIBELF_SET_ERROR(DATA, 0);
               return (NULL);
       }

       if ((direction == ELF_TOMEMORY ? db : sb) %
           _libelf_malign(src->d_type, elfclass)) {
               LIBELF_SET_ERROR(DATA, 0);
               return (NULL);
       }

       dst->d_type = src->d_type;
       dst->d_size = dsz;

       byteswap = encoding != LIBELF_PRIVATE(byteorder);

       if (src->d_size == 0 ||
           (db == sb && !byteswap && fsz == msz))
               return (dst);   /* nothing more to do */

       xlator = _libelf_get_translator(src->d_type, direction, elfclass,
           elfmachine);
       if (!xlator(dst->d_buf, dsz, src->d_buf, cnt, byteswap)) {
               LIBELF_SET_ERROR(DATA, 0);
               return (NULL);
       }

       return (dst);
}