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  ELFTC_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 = (size_t) src->d_size / fsz;
103  		dsz = cnt * msz;
104  	} else {
105  		cnt = (size_t) 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 + (size_t) src->d_size;
116  	db = (uintptr_t) dst->d_buf;
117  	de = db + (size_t) 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  }