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Are there any things in Linux that need to be started over from scratch? (lemmy.ca)
submitted 2 years ago by to c/linux@lemmy.ml
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I'm curious how software can be created and evolve over time. I'm afraid that at some point, we'll realize there are issues with the software we're using that can only be remedied by massive changes or a complete rewrite.

Are there any instances of this happening? Where something is designed with a flaw that doesn't get realized until much later, necessitating scrapping the whole thing and starting from scratch?

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[–] 8 points 2 years ago (2 children)

You have stderr to throw errors into. And the constants are just error codes, like HTTP error codes. Without it how computer would know if the program executed correctly.

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  • [–] 0 points 2 years ago (2 children)

    You throw an exception like a gentleman. But C doesn't support them. So you need to abuse the return type to also indicate "success" as well as a potential value the caller wanted.

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  • [–] 3 points 2 years ago* (2 children)

    Exceptionss are bad coding, and what's abusive of using the full range of an integer? 0 success, everything else, error - check the API for details or call strerror.

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  • [–] 1 point 2 years ago (1 child)

    Returning error codes in-band is the reason for a significant percentage of C bugs and security holes when the return value is used without checking. Something like Rust's Result type that forces you to distinguish the two cases is much better design here. And no, you are not working with a whole language ecosystem of "sufficiently disciplined programmers" so that nobody ever forgets to check a return value.

    Not to mention that errno is just a very broken design in the times of modern thread and event systems, signals, interrupts and all kinds of other ways to produce race conditions and overwrite the errno value before it is checked.

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  • [–] 1 point 2 years ago

    errno is not shared between threads. Also:

    signal handlers that call functions that may set errno or modify the floating-point environment must save their original values, and restore them before returning.

    There does not add more race conditions because signal handlers execute in one of regular threads. In single-threaded program signals are functions that can be called by OS at any point of execution, but they do not execute at same time with threads.

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  • [–] 3 points 2 years ago* (last edited 2 years ago)

    So you need to abuse the return type to also indicate "success" as well as a potential value the caller wanted.

    You don't need to.

    Returnung structs, returning by pointer, signals, error flags, setjmp/longjmp, using cxa for exceptions(lol, now THIS is real abuse).

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