lib/libavb/avb_footer.c

/*
 * Copyright (C) 2016 The Android Open Source Project
 *
 * Permission is hereby granted, free of charge, to any person
 * obtaining a copy of this software and associated documentation
 * files (the "Software"), to deal in the Software without
 * restriction, including without limitation the rights to use, copy,
 * modify, merge, publish, distribute, sublicense, and/or sell copies
 * of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

#include "avb_footer.h"
#include "avb_util.h"

bool avb_footer_validate_and_byteswap(const AvbFooter* src, AvbFooter* dest) {
  avb_memcpy(dest, src, sizeof(AvbFooter));

  dest->version_major = avb_be32toh(dest->version_major);
  dest->version_minor = avb_be32toh(dest->version_minor);

  dest->original_image_size = avb_be64toh(dest->original_image_size);
  dest->vbmeta_offset = avb_be64toh(dest->vbmeta_offset);
  dest->vbmeta_size = avb_be64toh(dest->vbmeta_size);

  /* Check that magic is correct. */
  if (avb_safe_memcmp(dest->magic, AVB_FOOTER_MAGIC, AVB_FOOTER_MAGIC_LEN) !=
      0) {
    avb_error("Footer magic is incorrect.\n");
    return false;
  }

  /* Ensure we don't attempt to access any fields if the footer major
   * version is not supported.
   */
  if (dest->version_major > AVB_FOOTER_VERSION_MAJOR) {
    avb_error("No support for footer version.\n");
    return false;
  }

  return true;
}