lib/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 <sys/cdefs.h>
  28
  29 #include <assert.h>
  30 #include <libelf.h>
  31
  32 #include "_libelf.h"
  33
  34 LIBELF_VCSID("$Id$");
  35
  36 /*
  37  * Translate to/from the file representation of ELF objects.
  38  *
  39  * Translation could potentially involve the following
  40  * transformations:
  41  *
  42  * - an endianness conversion,
  43  * - a change of layout, as the file representation of ELF objects
  44  *   can differ from their in-memory representation.
  45  * - a change in representation due to a layout version change.
  46  */
  47
  48 Elf_Data *
  49 _libelf_xlate(Elf_Data *dst, const Elf_Data *src, unsigned int encoding,
  50     int elfclass, int direction)
  51 {
  52         int byteswap;
  53         size_t cnt, dsz, fsz, msz;
  54         uintptr_t sb, se, db, de;
  55
  56         if (encoding == ELFDATANONE)
  57                 encoding = LIBELF_PRIVATE(byteorder);
  58
  59         if ((encoding != ELFDATA2LSB && encoding != ELFDATA2MSB) ||
  60             dst == NULL || src == NULL || dst == src)   {
  61                 LIBELF_SET_ERROR(ARGUMENT, 0);
  62                 return (NULL);
  63         }
  64
  65         assert(elfclass == ELFCLASS32 || elfclass == ELFCLASS64);
  66         assert(direction == ELF_TOFILE || direction == ELF_TOMEMORY);
  67
  68         if (dst->d_version != src->d_version) {
  69                 LIBELF_SET_ERROR(UNIMPL, 0);
  70                 return (NULL);
  71         }
  72
  73         if  (src->d_buf == NULL || dst->d_buf == NULL) {
  74                 LIBELF_SET_ERROR(DATA, 0);
  75                 return (NULL);
  76         }
  77
  78         if ((int) src->d_type < 0 || src->d_type >= ELF_T_NUM) {
  79                 LIBELF_SET_ERROR(DATA, 0);
  80                 return (NULL);
  81         }
  82
  83         if ((fsz = (elfclass == ELFCLASS32 ? elf32_fsize : elf64_fsize)
  84             (src->d_type, (size_t) 1, src->d_version)) == 0)
  85                 return (NULL);
  86
  87         msz = _libelf_msize(src->d_type, elfclass, src->d_version);
  88
  89         assert(msz > 0);
  90
  91         if (src->d_size % (direction == ELF_TOMEMORY ? fsz : msz)) {
  92                 LIBELF_SET_ERROR(DATA, 0);
  93                 return (NULL);
  94         }
  95
  96         /*
  97          * Determine the number of objects that need to be converted, and
  98          * the space required for the converted objects in the destination
  99          * buffer.
 100          */
 101         if (direction == ELF_TOMEMORY) {
 102                 cnt = src->d_size / fsz;
 103                 dsz = cnt * msz;
 104         } else {
 105                 cnt = src->d_size / msz;
 106                 dsz = cnt * fsz;
 107         }
 108
 109         if (dst->d_size  <  dsz) {
 110                 LIBELF_SET_ERROR(DATA, 0);
 111                 return (NULL);
 112         }
 113
 114         sb = (uintptr_t) src->d_buf;
 115         se = sb + src->d_size;
 116         db = (uintptr_t) dst->d_buf;
 117         de = db + dst->d_size;
 118
 119         /*
 120          * Check for overlapping buffers.  Note that db == sb is
 121          * allowed.
 122          */
 123         if (db != sb && de > sb && se > db) {
 124                 LIBELF_SET_ERROR(DATA, 0);
 125                 return (NULL);
 126         }
 127
 128         if ((direction == ELF_TOMEMORY ? db : sb) %
 129             _libelf_malign(src->d_type, elfclass)) {
 130                 LIBELF_SET_ERROR(DATA, 0);
 131                 return (NULL);
 132         }
 133
 134         dst->d_type = src->d_type;
 135         dst->d_size = dsz;
 136
 137         byteswap = encoding != LIBELF_PRIVATE(byteorder);
 138
 139         if (src->d_size == 0 ||
 140             (db == sb && !byteswap && fsz == msz))
 141                 return (dst);   /* nothing more to do */
 142
 143         if (!(_libelf_get_translator(src->d_type, direction, elfclass))
 144             (dst->d_buf, dsz, src->d_buf, cnt, byteswap)) {
 145                 LIBELF_SET_ERROR(DATA, 0);
 146                 return (NULL);
 147         }
 148
 149         return (dst);
 150 }