this post was submitted on 04 Aug 2025
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Programming

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Handling of unlikely syscall errors (programming.dev)
submitted 3 days ago by hades@programming.dev to c/programming@programming.dev
14 comments fedilink hide all child comments
 

If you were designing a standard library of a high level language (like Rust, C++, etc.) what would it do if while getting the current time of day (e.g. SystemTime::now()) it encountered a failed kernel system call (e.g. to clock_gettime) and why?

What do you think the existing implementations do?

  • Return error or raise exception
  • Return 0
  • Return undefined values (like stack garbage)
  • Panic/crash/segfault
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[–] eager_eagle@lemmy.world 6 points 3 days ago* (last edited 3 days ago) (4 children)

you should do what's idiomatic for that language, e.g.: return an error in Rust; raise an exception in Python or Java; return an integer != 0 in C; etc.

Panic/crash/segfault

probably the worst option for a library

[–] hades@programming.dev 2 points 3 days ago (1 children)

probably the worst option for a library

Even worse than returning garbage? :)

[–] eager_eagle@lemmy.world 2 points 3 days ago* (last edited 3 days ago) (1 children)

If it's garbage as in a string with a bunch of information that is hard to parse, yeah, crashing without giving the caller a way to avoid it might be worse. But what is exactly this garbage and in what cases are you considering returning it at all?

[–] hades@programming.dev 1 points 3 days ago

Uninitialized automatic variables. E.g. (in C/C++):

int get_time() {
  int time;
  syscall(/* something that fails */, &time);
  return time;
}
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