ck_ht_entry_key_length(3) on Linux
The text d14b24dbfc39, as Debian 13 (Trixie), Debian 12 (Bookworm), Debian 11 (Bullseye), Debian 9 (Stretch), Debian 8 (Jessie) shipped it. The page shows this text now.
returns the length of the key specified in the argument