[TUHS] Bugs in V6 'dcheck'

Ronald Natalie ron at ronnatalie.com
Sat May 31 23:23:31 AEST 2014

If I understand what you are saying, it only occurs when you run dcheck with mutliple volumes at one time?
I can't say I EVER did that back in the pre-fsck days.

We did icheck and then dcheck on each disk in sequence.
I don't even think we had a shell script.    It was incumbent on the operator to check each of the system disks and any user volumes that were mounted at the time the system crash.

Bugs are entirely not uncommon.     This is why BSD and JHU and UT had their own distributions.       Having been a V6 UNIX systems programmer at a university back in the day as we had students who found it an extracurricular activity (nobody took computing seriously back then) to break security or just plain crash the system.    Tons of worse bugs than dcheck issues.    

I actually spent some time before they elevated me to system programmer doing some exploration in to problems (authorized by the staff).
I decided to test all the setuid programs against vulnerabilities of playing with the file descriptors before invoking them.      I found a half a dozen problems and mailed of the details before I decided to give up and go home.    The next morning our log had a message about the first eight characters of the system accounting file being corrupted.   I told the guys recovering from that that I might know how that had happened.    They said they figured I would because it was my user  name that was found overwritten on the file.

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