curl_mime_filedata(3) on macOS
The text b1b2fcb0bae7, as macOS 26.5, macOS 26.4, macOS 26.3, macOS 26.2, macOS 26.1, macOS 26.0, macOS 15.6, macOS 15.5, macOS 15.4, macOS 15.3, macOS 15.2, macOS 15.1, macOS 15.0, macOS 14.6, macOS 14.5 shipped it. The page shows this text now.
set a mime part's body data from a file contents