Comment by matheusmoreira

Honestly I don't blame him. Perhaps he's used to read where the number of bytes to read follows the buffer:

https://man7.org/linux/man-pages/man2/read.2.html

  ssize_t read(int fd, void *buf, size_t count);

That's how it works in every sane I/O API I've seen. What's even the point of the size_of_item argument?