Thanks for the PR! Hardcoding 128 as the byte size of this struct seems error-prone and likely to cause additional issues. Could we perhaps instead do a return string() and disable the extended error message in this situation?

@Mytherin If you or someone is sure that gonna work, we could. gnulib does use 128 there for some reason: https://github.com/coreutils/gnulib/blob/37fa6373a3fcac65ab3500ff65868650f9782cba/lib/get_ppid_of.c#L240-L275
Specifically in this line: https://github.com/coreutils/gnulib/blob/37fa6373a3fcac65ab3500ff65868650f9782cba/lib/get_ppid_of.c#L269

Looks like it was originally introduced that way: coreutils/gnulib@015fe7c
And then modified a bit to support < 10.5: coreutils/gnulib@119622a (however hardcoding to 128 remained).

P. S. Provided this is correct for specific macOS versions (< 10.7), it is safe – or can be made so by extra macros specifying macOS versions explicitly. As long as the fallback sits inside, it cannot affect anything else (if that is your concern).
I cannot really make a judgement whether gnulib upstream used the optimal code – I can only say it does fix the build on my system.

That's fair - but since we are not running tests on older MacOS versions I would be more comfortable just returning string() - this is not a critical component of the system, it just returns a more detailed error message which could be skipped on older systems.

That's fair - but since we are not running tests on older MacOS versions I would be more comfortable just returning string() - this is not a critical component of the system, it just returns a more detailed error message which could be skipped on older systems.

@Mytherin Okay, sure, let’s do that. Could you either add a commit here or make a code suggestion for me to commit?

Done - could you check if this resolves the issue for you on the older MacOS box? I don't have access to one.

@Mytherin Thank you! Will confirm tomorrow once back to the machine.

@Mytherin I cannot run tests at the moment, but yes, this works to fix the build, so all good for now.