@lcamtuf This code has a lot of problems. Like the race vuln in /bin/mkdir.
In pdp-11 Unix, mkdir was a suid-root program that did a mknod to create the directory, and then a chown to change its ownership to other-than-root. But something else could rename the directory after the mknod, and replace it with a link to, e.g., /etc/passwd, which would then get chowned.
On later versions with ^Z job control, a ^Z on mkdir had good odds of catching it between the two syscalls; no code required.
@universalhub No, that one runs on Metro-North.
(They also have heritage units, this one in similar livery.)
@tante But this is how open source itself got started -- RMS implementing GNU Emacs incorporating large chunks of Gosling Emacs's code (against terms of its license), later rewriting but preserving the interfaces, and writing gcc having access to the source of lcc, and very likely pcc. (Yes, Gosling rewrote RMS's earlier work.)
"Clean room" has never been a requirement of copyright law. It's a defensive tactic going above and beyond legal requirements to fend off particularly vicious litigants.
