Re: [PATCH] scripts/kallsyms: Fix build failure by setting errno before calling getline()

[Miguel Ojeda]

On Tue, Jul 25, 2023 at 10:55 AM James Clark <james.clark@xxxxxxx> wrote:
>
> But I just checked now and it's just bear [1] that causes the issue.
> Maybe it sets errno before forking and that persists in the child
> processes? Not 100% sure how it works. I did debug scripts/kallsyms and
> errno was already set on the first line of main(), so it's not some
> other library call in kallsyms that is setting it but not being checked.

I think this is https://github.com/rizsotto/Bear/issues/469: bear
preloads a library which was setting it to non-zero.

Now, even if bear was breaking a guarantee C programs have (`errno`
for the initial thread at program startup is meant to be 0 according
to the C standard), it is still a good idea to set `errno` to zero
here in case something else happens to change `errno` within
`kallsyms` in the future.

With the repro and the `bear` link issue added:

    Reviewed-by: Miguel Ojeda <ojeda@xxxxxxxxxx>

Cheers,
Miguel