Creating a kernel block device to represent a single file

Question

Creating a kernel block device to represent a single file

I would like to create a way to redefine the methods of reading, writing and displaying (on the page) in one file without load to implement the whole new file system.

Therefore, I am exploring the possibility of using a block device. for example, my device will be a dynamic library that can be downloaded by other processes.

So far I have managed to create a device using the following code (written in the macOS kernel extension, but should be compatible with every BSD-based OS).

static struct cdevsw my_device =
{
    // Implement the methods
    .d_open = my_open,
    .d_close = my_close,
    .d_read = my_read,
    ...
};

int my_major_index = cdevsw_add (-1 /* auto select index */, &my_device);
dev = makedev (my_major_index, 0);
void * device_node = devfs_make_node (dev, 
                                      DEVFS_BLOCK, 
                                      UID_ROOT, 
                                      GID_WHEEL, 
                                      MY_PERMISSION, 
                                      "my_device");