5 ms·

But these are bit-for-bit identical.

dataflow 5y ago
Edit: You're talking about the Backblaze binaries? Yeah that's why I said Clang's is almost bit-for-bit identical, so it's clear to everyone it's not 100% the same as the Backblaze situation. Not sure what your complaint is about my comment though? It's still practically the same problem, and you can solve it just as well with the argv[0] tricks or whatever. Or are you saying your heuristic for determining the underlying engineering quality changes its output based on 1 bit flip? Identical executables is awful engineering, but a few bytes different (out of 90MB) is great engineering?
- somehnguy 5y ago
  The 'these' being referenced here are the Backblaze executables, not your clang executables.
- monsieurbanana 5y ago
  They're not saying the clang are bit by bit identical, but the blackblaze ones.
- jfrunyon 5y ago
  Not sure why you think clang having multiple not-identical executables is relevant to Backblaze having multiple identical executables.
  - dataflow 5y ago
    > Not sure why you think clang having multiple not-identical executables is relevant to Backblaze having multiple identical executables. Really? You genuinely don't see why I would think a case with >99.99% identical executables might be relevant to a case with 100% identical executables?
    - 300bps 5y ago
      I genuinely don’t see why either. With 100% identical executables, there does not appear to be a good reason to have multiple copies under any circumstance. With anything < 100% identical, well, maybe there’s a good reason to have multiples. Who knows? Id probably give someone the benefit of the doubt and figure there was some engineering challenge that made it faster/easier to do it that way. So yes, 100% identical is completely different than almost 100% identical.
      - dataflow 5y ago
        > So yes, 100% identical is completely different than almost 100% identical. They're completely (!) different? And you're saying this despite the fact that the comment I replied to was discussing cases where one could "just execute one binary n times (with different argv[0] if they'd like)"... which is something you can do with different executables just as well as with identical ones? It's not just a little different but completely different? So different that not only you don't see any similarity, but you also cannot fathom why I might think there's some similarity?!
        notthathardbro 5y ago
        No, actually. And your incredulous doubling-down is, well, making it more obvious that you seem to be missing the point. If they're 99% the same, it's generously easy to assume that there's a material difference. That assumption is completely nonsensical if they're 100% identical. So no, for the sake of every bit of context in this conversation, it does not make sense that you'd bring up an unrelated scenario of "similar" binaries.
        dang 5y ago
        Would you please stop posting in the flamewar style to HN? It's not what this site is for, and it destroys what it is for. We've had to ask you about this more than once in the past already. If you wouldn't mind reviewing https://news.ycombinator.com/newsguidelines.html https://news.ycombinator.com/newsguidelines.html and taking the intended spirit of the site more to heart, we'd be grateful.
awinter-py 5y ago
maybe they're not identical but backblaze has discovered 20 hash collisions that are also valid executables? that would be impressive in a way
- selcuka 5y ago
  Bit-for-bit identical means that they are actually identical though.

Edit: You're talking about the Backblaze binaries? Yeah that's why I said Clang's is almost bit-for-bit identical, so it's clear to everyone it's not 100% the same as the Backblaze situation. Not sure what your complaint is about my comment though? It's still practically the same problem, and you can solve it just as well with the argv[0] tricks or whatever. Or are you saying your heuristic for determining the underlying engineering quality changes its output based on 1 bit flip? Identical executables is awful engineering, but a few bytes different (out of 90MB) is great engineering?

somehnguy 5y ago
The 'these' being referenced here are the Backblaze executables, not your clang executables.
monsieurbanana 5y ago
They're not saying the clang are bit by bit identical, but the blackblaze ones.
jfrunyon 5y ago
Not sure why you think clang having multiple not-identical executables is relevant to Backblaze having multiple identical executables.
- dataflow 5y ago
  > Not sure why you think clang having multiple not-identical executables is relevant to Backblaze having multiple identical executables. Really? You genuinely don't see why I would think a case with >99.99% identical executables might be relevant to a case with 100% identical executables?
  - 300bps 5y ago
    I genuinely don’t see why either. With 100% identical executables, there does not appear to be a good reason to have multiple copies under any circumstance. With anything < 100% identical, well, maybe there’s a good reason to have multiples. Who knows? Id probably give someone the benefit of the doubt and figure there was some engineering challenge that made it faster/easier to do it that way. So yes, 100% identical is completely different than almost 100% identical.
    - dataflow 5y ago
      > So yes, 100% identical is completely different than almost 100% identical. They're completely (!) different? And you're saying this despite the fact that the comment I replied to was discussing cases where one could "just execute one binary n times (with different argv[0] if they'd like)"... which is something you can do with different executables just as well as with identical ones? It's not just a little different but completely different? So different that not only you don't see any similarity, but you also cannot fathom why I might think there's some similarity?!
      - notthathardbro 5y ago
        No, actually. And your incredulous doubling-down is, well, making it more obvious that you seem to be missing the point. If they're 99% the same, it's generously easy to assume that there's a material difference. That assumption is completely nonsensical if they're 100% identical. So no, for the sake of every bit of context in this conversation, it does not make sense that you'd bring up an unrelated scenario of "similar" binaries.
      - dang 5y ago
        Would you please stop posting in the flamewar style to HN? It's not what this site is for, and it destroys what it is for. We've had to ask you about this more than once in the past already. If you wouldn't mind reviewing https://news.ycombinator.com/newsguidelines.html https://news.ycombinator.com/newsguidelines.html and taking the intended spirit of the site more to heart, we'd be grateful.

awinter-py 5y ago

maybe they're not identical but backblaze has discovered 20 hash collisions that are also valid executables? that would be impressive in a way

selcuka 5y ago
Bit-for-bit identical means that they are actually identical though.