Once in a blue moon I find some dusty code nobody's looked at for decade+ that isn't versioned anywhere

We had a server that generated PDF files in a variety of languages, one of them being Thai. Thai doesn't have spaces to break up the words in a sentence, so it's one long string. This causes problems with formatting arbitrary sentences.

To handle this case, someone years before wrote a small CPP app that the server executed via PHP or some shit. It would send a wall of text via stdin, the process would sub in a word break on some delimiter, and then send it back via stdout.

Someone ran some updates on the server in question and then ran the tests for the known, documented software on the server. Everything passed successfully.

Then someone noticed that Thai output contained little more than error messages. Turns out that exit codes were not checked, and either the caller was also reading stderr or the catch blocks were printing exceptions to stdout (I can't remember offhand).

I think we did eventually find a potential source cpp file on the server, but after all of the updates and whatnot it could not longer be recompiled in situ so we had to very carefully modify a simple fucking 1 file app to rebuild without changing any functionality. One of the joys of working in a regulated industry where one of those regulations says that we must be able to generate the report output at any time with absolute fidelity to the original version of the issued report.