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Linux is a family of open source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991 by Linus Torvalds. Linux is typically packaged in a Linux distribution (or distro for short).

Distributions include the Linux kernel and supporting system software and libraries, many of which are provided by the GNU Project. Many Linux distributions use the word "Linux" in their name, but the Free Software Foundation uses the name GNU/Linux to emphasize the importance of GNU software, causing some controversy.

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Are there any things in Linux that need to be started over from scratch? (lemmy.ca)

submitted 7 months ago by [email protected] to c/[email protected]

274 comments fedilink hide all child comments

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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[–] [email protected] 0 points 7 months 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.

[–] [email protected] 3 points 7 months ago* (last edited 7 months 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.

[–] [email protected] 1 points 7 months ago

errno is bad programming.

[–] [email protected] 1 points 7 months ago (1 children)

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.

[–] [email protected] 1 points 7 months 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.

[–] [email protected] 3 points 7 months ago* (last edited 7 months 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).