size_t SDL_RWread(struct SDL_RWops* context,
                  void*             ptr,
                  size_t            size,
                  size_t            maxnum)

SDL_RWops *rw = SDL_RWFromFile("test.bin","r");
if (rw != NULL)
{
    extern Uint8 buf[256];
    SDL_RWread(rw, buf, sizeof (buf), 1);
    SDL_RWclose(rw);
}

char* file_read(const char* filename)
{
    SDL_RWops *rw = SDL_RWFromFile(filename, "rb");
    if (rw == NULL) return NULL;

    Sint64 res_size = SDL_RWsize(rw);
    char* res = (char*)malloc(res_size + 1);

    Sint64 nb_read_total = 0, nb_read = 1;
    char* buf = res;
    while (nb_read_total < res_size && nb_read != 0)
    {
        nb_read = SDL_RWread(rw, buf, 1, (res_size - nb_read_total));
        nb_read_total += nb_read;
        buf += nb_read;
    }
    SDL_RWclose(rw);
    if (nb_read_total != res_size)
    {
        free(res);
        return NULL;
    }

    res[nb_read_total] = '\0';
    return res;
}