MCUboot directly references struct flash_area members in certain places

[Cpt-Seablue]

MCUBoot version: 2.1.0

We are trying to port MCUBoot to our C++ based SDK. As a part of the porting process, we planned to provide a forward declaration of struct flash_area and then define the struct in C++ code.

However, doing this causes a compilation error in file bootutil_misc.c, on line 176:

.../third-party/mcuboot/repo/boot/bootutil/src/bootutil_misc.c:176:12: error: invalid use of undefined type 'const struct flash_area'
  176 |     if (fap->fa_id == FLASH_AREA_IMAGE_SCRATCH) {

If the problematic line is rewritten as below, the issue is solved.

if(flash_area_get_id(fap) == FLASH_AREA_IMAGE_SCRATCH) {

This seems like an obvious oversight, because the PORTING document says that MCUBoot should never access flash_area directly, and instead accessor functions are used. Also in the same bootutil_misc.c file, accessor functions are used, including flash_area_get_id().

While researching the issue, I found a PR about this exact problem #1929. It was reviewed, accepted but then never merged. It is now auto-closed by the bot.