firestring_estr_read(3) on Linux
The text 12d3a45a3781, as Debian 8 (Jessie), Debian 7 (Wheezy), Debian 6.0 (Squeeze), Debian 5.0 (Lenny), Debian 4.0 (Etch), Debian 3.1 (Sarge) shipped it. The page shows this text now.
read from a file descriptor into an estring