contrib/elftoolchain/libelf/libelf_xlate.c

   1 /*-
   2  * Copyright (c) 2006,2008 Joseph Koshy
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  *
  14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  24  * SUCH DAMAGE.
  25  */
  26
  27 #include <assert.h>
  28 #include <libelf.h>
  29
  30 #include "_libelf.h"
  31
  32 ELFTC_VCSID("$Id: libelf_xlate.c 3174 2015-03-27 17:13:41Z emaste $");
  33
  34 /*
  35  * Translate to/from the file representation of ELF objects.
  36  *
  37  * Translation could potentially involve the following
  38  * transformations:
  39  *
  40  * - an endianness conversion,
  41  * - a change of layout, as the file representation of ELF objects
  42  *   can differ from their in-memory representation.
  43  * - a change in representation due to a layout version change.
  44  */
  45
  46 Elf_Data *
  47 _libelf_xlate(Elf_Data *dst, const Elf_Data *src, unsigned int encoding,
  48     int elfclass, int direction)
  49 {
  50         int byteswap;
  51         size_t cnt, dsz, fsz, msz;
  52         uintptr_t sb, se, db, de;
  53
  54         if (encoding == ELFDATANONE)
  55                 encoding = LIBELF_PRIVATE(byteorder);
  56
  57         if ((encoding != ELFDATA2LSB && encoding != ELFDATA2MSB) ||
  58             dst == NULL || src == NULL || dst == src)   {
  59                 LIBELF_SET_ERROR(ARGUMENT, 0);
  60                 return (NULL);
  61         }
  62
  63         assert(elfclass == ELFCLASS32 || elfclass == ELFCLASS64);
  64         assert(direction == ELF_TOFILE || direction == ELF_TOMEMORY);
  65
  66         if (dst->d_version != src->d_version) {
  67                 LIBELF_SET_ERROR(UNIMPL, 0);
  68                 return (NULL);
  69         }
  70
  71         if  (src->d_buf == NULL || dst->d_buf == NULL) {
  72                 LIBELF_SET_ERROR(DATA, 0);
  73                 return (NULL);
  74         }
  75
  76         if ((int) src->d_type < 0 || src->d_type >= ELF_T_NUM) {
  77                 LIBELF_SET_ERROR(DATA, 0);
  78                 return (NULL);
  79         }
  80
  81         if ((fsz = (elfclass == ELFCLASS32 ? elf32_fsize : elf64_fsize)
  82             (src->d_type, (size_t) 1, src->d_version)) == 0)
  83                 return (NULL);
  84
  85         msz = _libelf_msize(src->d_type, elfclass, src->d_version);
  86
  87         assert(msz > 0);
  88
  89         if (src->d_size % (direction == ELF_TOMEMORY ? fsz : msz)) {
  90                 LIBELF_SET_ERROR(DATA, 0);
  91                 return (NULL);
  92         }
  93
  94         /*
  95          * Determine the number of objects that need to be converted, and
  96          * the space required for the converted objects in the destination
  97          * buffer.
  98          */
  99         if (direction == ELF_TOMEMORY) {
 100                 cnt = (size_t) src->d_size / fsz;
 101                 dsz = cnt * msz;
 102         } else {
 103                 cnt = (size_t) src->d_size / msz;
 104                 dsz = cnt * fsz;
 105         }
 106
 107         if (dst->d_size  <  dsz) {
 108                 LIBELF_SET_ERROR(DATA, 0);
 109                 return (NULL);
 110         }
 111
 112         sb = (uintptr_t) src->d_buf;
 113         se = sb + (size_t) src->d_size;
 114         db = (uintptr_t) dst->d_buf;
 115         de = db + (size_t) dst->d_size;
 116
 117         /*
 118          * Check for overlapping buffers.  Note that db == sb is
 119          * allowed.
 120          */
 121         if (db != sb && de > sb && se > db) {
 122                 LIBELF_SET_ERROR(DATA, 0);
 123                 return (NULL);
 124         }
 125
 126         if ((direction == ELF_TOMEMORY ? db : sb) %
 127             _libelf_malign(src->d_type, elfclass)) {
 128                 LIBELF_SET_ERROR(DATA, 0);
 129                 return (NULL);
 130         }
 131
 132         dst->d_type = src->d_type;
 133         dst->d_size = dsz;
 134
 135         byteswap = encoding != LIBELF_PRIVATE(byteorder);
 136
 137         if (src->d_size == 0 ||
 138             (db == sb && !byteswap && fsz == msz))
 139                 return (dst);   /* nothing more to do */
 140
 141         if (!(_libelf_get_translator(src->d_type, direction, elfclass))
 142             (dst->d_buf, dsz, src->d_buf, cnt, byteswap)) {
 143                 LIBELF_SET_ERROR(DATA, 0);
 144                 return (NULL);
 145         }
 146
 147         return (dst);
 148 }