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Reverse Engineering MacOS High Sierra Supplemental Update

cocoaengineering.com

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Re: Reverse Engineering MacOS High Sierra Supplemental Update

#2

Post by atas »

Simple technique for preventing bugs like this: don't copy-paste code. If you find yourself copy-pasting code think twice why you even have to do it (DRY principle) and be aware of the potential consequences. Even if some code has to be duplicate, I am forcing myself to just write it from scratch, exactly for this reason: do you really know that you have updated all your data? And yeah, unit tests would help in spotting this and other things. But aren't unit tests a duplication of your code, already?

UPDATE:

Maybe I should have stated my last question differently. I meant that in the context of checking that the data is correct, it would be the same as writing the duplicate code from scratch.

Re: Reverse Engineering MacOS High Sierra Supplemental Update

#4

Post by IncRnd » 

  if ((err = SSLHashSHA1.update(&hashCtx, &signedParams)) != 0)
      goto fail;
      goto fail;  /* MISTAKE! THIS LINE SHOULD NOT BE HERE */
  if ((err = SSLHashSHA1.final(&hashCtx, &hashOut)) != 0)
      goto fail;
History repeats itself in ever stranger ways. While the effects are different, the original mistake can be quite similar.

Re: Reverse Engineering MacOS High Sierra Supplemental Update

#5

Post by blowski »

atas wrote: post #2

Simple technique for preventing bugs like this: don't copy-paste code. If you find yourself copy-pasting code think twice why you even have to do it (DRY principle) and be aware of the potential consequences. Even if some code has to be duplicate, I am forcing myself to just write it from scratch, exactly for this reason: do you really know that you have updated all your data? And yeah, unit tests would help in spott…

Just to play devil's advocate: sometimes DRY code is harder to understand, which makes it harder to see bugs. Whenever you introduce an abstraction to make your code DRYer, you have to remember the law of leaky abstractions. DRY code is a good principle to follow, but not an absolute law.

Re: Reverse Engineering MacOS High Sierra Supplemental Update

#6

Post by icebraining »

atas wrote: post #2

Simple technique for preventing bugs like this: don't copy-paste code. If you find yourself copy-pasting code think twice why you even have to do it (DRY principle) and be aware of the potential consequences. Even if some code has to be duplicate, I am forcing myself to just write it from scratch, exactly for this reason: do you really know that you have updated all your data? And yeah, unit tests would help in spott…

But aren't unit tests a duplication of your code, already?

No?

Re: Reverse Engineering MacOS High Sierra Supplemental Update

#7

Post by slhck »

atas wrote: post #2

Simple technique for preventing bugs like this: don't copy-paste code. If you find yourself copy-pasting code think twice why you even have to do it (DRY principle) and be aware of the potential consequences. Even if some code has to be duplicate, I am forcing myself to just write it from scratch, exactly for this reason: do you really know that you have updated all your data? And yeah, unit tests would help in spott…

> But aren't unit tests a duplication of your code, already?

No, as you'd only be specifying the input and output state, e.g. the change of a model's attributes or the correctness of a mathematical calculation. The code that implements the (business) logic of going from input to output state should be part of your application, not the test.

Re: Reverse Engineering MacOS High Sierra Supplemental Update

#8

Post by saagarjha »

IncRnd wrote: post #4

if ((err = SSLHashSHA1.update(&hashCtx, &signedParams)) != 0) goto fail; goto fail; /* MISTAKE! THIS LINE SHOULD NOT BE HERE */ if ((err = SSLHashSHA1.final(&hashCtx, &hashOut)) != 0) goto fail; History repeats itself in ever stranger ways. While the effects are different, the original mistake can be quite similar.

This is the SSL bug from iOS 9 for those wondering.

Re: Reverse Engineering MacOS High Sierra Supplemental Update

#9

Post by [deleted] »

atas wrote: post #2

Simple technique for preventing bugs like this: don't copy-paste code. If you find yourself copy-pasting code think twice why you even have to do it (DRY principle) and be aware of the potential consequences. Even if some code has to be duplicate, I am forcing myself to just write it from scratch, exactly for this reason: do you really know that you have updated all your data? And yeah, unit tests would help in spott…

[deleted]

Re: Reverse Engineering MacOS High Sierra Supplemental Update

#10

Post by saagarjha »

sparkpeasy wrote: post #3

Scary to think that the reveal of all passwords on MacOS shoulders on one person's accidental copy + paste of one line.

It’s not a reveal of all the passwords, certainly. It’s only disclosing the disk’s password, and only in the situation provided.
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