• Amberskin@europe.pub
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    2 days ago

    Just to boast my old timer credentials.

    There is an utility program in IBM’s mainframe operating system, z/OS, that has been there since the 60s.

    It has just one assembly code instruction: a BR 14, which means basically ‘return’.

    The first version was bugged and IBM had to issue a PTF (patch) to fix it.

    • DaPorkchop_@lemmy.ml
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      2 days ago

      Okay, you can’t just drop that bombshell without elaborating. What sort of bug could exist in a program which contains a single return instruction?!?

      • Amberskin@europe.pub
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        2 days ago

        It didn’t clear the return code. In mainframe jobs, successful executions are expected to return zero (in the machine R15 register).

        So in this case fixing the bug required to add an instruction instead of removing one.

    • Rose@slrpnk.net
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      2 days ago

      Reminds me of how in some old Unix system, /bin/true was a shell script.

      …well, if it needs to just be a program that returns 0, that’s a reasonable thing to do. An empty shell script returns 0.

      Of course, since this was an old proprietary Unix system, the shell script had a giant header comment that said this is proprietary information and if you disclose this the lawyers will come at ya like a ton of bricks. …never mind that this was a program that literally does nothing.