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Comment by ChuckMcM | Hacker News Reader

Thank you, nice concise explanation.

In an enterprise or company, when it is growing from startup to market gorilla, there are often tales of screw ups like this that happened to some poor sysadmin or programmer. And the company develops a sort of genetic memory of what not to do. Like children, companies that learn the 'dangerous' things early before they can do real harm, grow up to be less likely to do something really stupid later in their existence.

But I don't know what vector could be used to pass this sort of cultural knowledge between ethereum contract writers from generation to generation. It needs a 'book of sins' that everyone can read and contribute to in order to insure that new contracts won't suffer the problems of the early ones.

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One effort along these lines is the Consensys best practices document:

https://consensys.github.io/smart-contract-best-practices/

That looks like it is headed in the right direction. I observe that in companies there are stories (often with particpant's names) which exemplify bad practices. Part of the motivation to do better seems to come from not wanting to be the person in one of these stories.

Interesting point. A lot of these practices can in fact be backed up by stories, and maybe that's a good idea.

Reminds me of Google's blameless postmortem culture.

Except with lots of blame on display to ruin the culture.

In the "Known Attacks" section, they advocate using a mutex to prevent reentrant situations, but they're using a boolean, setting it to true before the operation and setting it to false afterwards. This is not secure -- it's possible for two threads to set it to true at the same time! You need to use an atomic concurrency operation like compare-and-swap [1] to implement a mutex.

[1] https://en.wikipedia.org/wiki/Compare-and-swap

The Ethereum VM is single threaded, so this isn't actually a problem

Back in the dual floppy drive days, I vividly remember getting the diskcopy a: b: right but accidentally placed the blank in a:.

I vividly remember doing it a second time some months later. But never again.

In my defense I was an idiot and was 8 or 9 years old, so fortunately it was just some shareware game disk that I was trying to copy for a friend only to lose my only copy.

The error made here is in an enormously more complex domain, but kind feels like they just accidentally low-level formatted an important diskette.

Yeah, I guess we all learned to write-protect the floppies the hard way... When you lose data you become a bit more paranoid about making mistakes. Fortunatelly floppies could be protected with a bit of tape.

I never understood why you would ever write-protect a floppy. Then again, I had a Mac 512k with a single floppy drive. (Insert Disk A; CRANK WHIRR GRIND SPIT; Insert Disk B; WHIRR WHIRR CRANK GRIND SPIT; Insert Disk A...)

Or rather, without a bit of tape. Tape was for writing, that's why many commercial disks shipped with the window permanently open.

You are thinking of 3.5" floppies. They are speaking of 5.25" floppies. They are the opposite.

Oh huh, those were before my time so I didn't know that, thanks.

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