setbuf(3) on macOS
The text 012d99edcdd6, as macOS 14.6, macOS 14.5, macOS 14.4, macOS 14.3, macOS 14.2, macOS 14.1, macOS 14.0, macOS 13.5, macOS 13.4, macOS 13.3, macOS 13.2, macOS 13.1, macOS 13.0, macOS 12.5, macOS 12.4, macOS 12.3, macOS 12.2, macOS 12.1, macOS 12.0.1 shipped it.
stream buffering operations