This introduces $SYSTEMD_KEYMAP_DIRECTORIES environment variable to
override the hardcoded keymap directories.
I think it is not necessary to provide the first class configuration
option for controlling the keymap directories, but it is not good to
hardcode the paths. So, let's introduce an environment variable to
override that.
Prompted by #31759.
Closes#31759.
Given that ERRNO_IS_RESOURCE() also matches positive values,
make sure this macro is not called with arguments that do not have
errno semantics.
In this case the argument passed to ERRNO_IS_RESOURCE() is the value
returned by recurse_dir_at() which can legitimately return positive
values without errno semantics, so fix this by moving the ERRNO_IS_RESOURCE()
invocation to the branch where the return value is known to be negative.
In https://bugzilla.redhat.com/show_bug.cgi?id=1933873 a keymap was set without
the package that provides it being installed (it2 is in kbd-legacy, which is
not installed by default). Setting a non-installed keymap is problematic,
because it results in nasty failures afterward (*). So let's to the same as
e.g. for locale data, and refuse a setting if the definition doesn't exists in
the filesystem.
The implementation using nftw() is not the most efficient, but I think it's OK
in this case. This is definitely not in any kind of hot path, and I prefer not
to duplicate the filename manipulation logic in a second function.
(*) If the keymap is not found, vconsole-setup.service will fail.
dracut-cmdline-ask.service has Requires=vconsole-setup.service, so it will also
fail, and this breaks boot. dracut-cmdline-ask.service having a hard dependency
is appropriate though: we sadly don't display what the keymap is, and with a wrong
keymap, any attempts to enter a password are likely to fail.
We would return a real error sometimes from the callback, and FTW_STOP other
times. Because of FTW_ACTIONRETVAL, everything except FTW_STOP would be
ignored. I don't think using FTW_ACTIONRETVAL is useful.
nftw() can only be used meaningfully with errno. Even if we return a proper
value ourselves from the callback, it will be propagated as a return value from
nftw(), but there is no way to distinguish this from a value generated by
nftw() itself, which is -1/-EPERM on error. So let's set errno ourselves so the
caller can at least look at that.
The code still ignores all errors.