Re: [PATCH v21 0/9] MR3103: server: Create and use a desktop shared mapping for GetCursorPos.

[Jinoh Kang (＠iamahuman)]

Jinoh Kang (@iamahuman) commented about server/mapping.c:
> - unsigned int capacity;
> - mem_size_t size;
> - int unix_fd;
> - void *tmp;
> -
> - capacity = session.object_capacity * 3 / 2;
> - size = offsetof(session_shm_t, objects[capacity]);
> - size = (size + page_mask) & ~((mem_size_t)page_mask);
> -
> - unix_fd = get_unix_fd( session_mapping->fd );
> - if (!grow_file( unix_fd, size )) return -1;
> - session_mapping->size = size;
> -
> - if ((tmp = mmap( NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, unix_fd, 0 )) == MAP_FAILED) return -1;
> - munmap( (void *)session.shared, session.shared->size );
> - session.shared = tmp;

1. Ensure `session_mapping->size == session.shared.size` at all times, since we rely on it in the `map_shared_session_section` loop.
   - Note that we don't have to ensure `backing_file[st_size] == session_mapping->size`. It's normal for a section to only have a portion of the backing file.
2. Consistently use `mapping->size` as we've done in `create_session_mapping`.

```suggestion:-4+0
    if ((tmp = mmap( NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, unix_fd, 0 )) == MAP_FAILED) return -1;
    munmap( (void *)session.shared, session_mapping->size );
    session.shared = tmp;

session_mapping->size = size;
```