kldxref: skip .pkgsave files

[me_igalic.co]

Summary

add .pkgsave to list of skipped files, by skipping all files that
contain two '.'

Motivation: This should help people transitioning from
traditional setups to pkgbase experience a lot less friction.

Test Plan

update your system to pkgbase (using, for instance https://alpha.pkgbase.live/ ;)
or, copy .ko files in /boot/kernel to .ko.pkgsave

service kldxref onerestart
reboot, see unhappy boot messages

apply this patch
rebuild kldxref
reboot and see *no* unhappy boot messages!

[emaste]

LGTM even though we're probably close to the point where it makes sense to have a loop with a list of extensions to ignore.

[me_igalic.co]

In D27959#624564, @emaste wrote:

LGTM even though we're probably close to the point where it makes sense to have a loop with a list of extensions to ignore.

alternatively, we could say: if it has >= 2 '.', skip it

[emaste]

alternatively, we could say: if it has >= 2 '.', skip it

Yes I think that's reasonable if you're up for updating this review with that change (or I'll take this one as is).

[me_igalic.co]

In D27959#624597, @emaste wrote:

alternatively, we could say: if it has >= 2 '.', skip it

Yes I think that's reasonable if you're up for updating this review with that change (or I'll take this one as is).

naïvely, i'd implement this like,

char *first_dot  = strchr(p->fts_name, '.');
char *last_dot = strchrt(p->fts_name, '.');
if (first_dot != NULL && last_dot != NULL && first_dot != last_dot)
        continue;

assuming that .symbols and .debug files usually look like: foo.ko.debug and bar.ko.symbols like with .pkgsave files.

[me_igalic.co]

same functionality, written in C instead of python style C. thanks to RhodiumToad:

char *dot = strchr(p->fts_name, '.');
if (dot && strchr(dot+1, '.') != NULL)
        continue;

i don't suppose dot+1 will push us *past* \0, so we don't need to check if we still have enough string left

[me_igalic.co]

fix @emaste's formatting remarks from IRC

[kevans]

usr.sbin/kldxref/kldxref.c

759–762

I think we can safely drop .symbols from this list, @emaste transitioned to .debug in 05117b57a54a -- surely enough time has passed that we can stop explicitly caring about or referencing them, hopefully...

[me_igalic.co]

address @kevans' feedback.

[me_igalic.co]

address @kevans' feedback, by moving local_rc *.pkgsave skipping into the skipping of scratch files, since that issues a warning.

[me_igalic.co]

unfucked this differential, after accidentally updating with the wrong diff