With the changes in 20ec8f534f, we would sort
entries with sort-key as expected (higher versions earlier, i.e. at the top of
the menu), but entries without the sort-key as before, with higher versions
later.
When we have a bunch of boot entries grouped by machine-id (or even in the
typical case of all boot entries having the same machine id), sorting by id
should generally give good results. Entries will be grouped by installation,
and then newer entries should generally be at the top of the menu.
The code is quite different from the rest of bootspec.c, with different
deps and stuff. There's even a /***/ line to separate the two parts.
Given how large the file already is, let#s just split it into two.
No code changes, just some splitting out.
This allows snippet generators to explicitly order entries: any string
can be set as an entry's "sort key". If set, sd-boot will use it to sort
entries on display.
New logic is hence (ignore the boot counting logic)
sort-key is set → primary sort key: sort-key (lexicographically increasing order)
→ secondary sort key: machine-id (also increasing order)
→ tertiary sort key: version (lexicographically decreasing order!)
sort-key is not set → primary sort key: entry filename (aka id), lexicographically increasing order)
With this scheme we can order OSes by their names from A-Z but then put
within the same OS still the newest version first. This should clean up
the order to match expectations more.
Based on discussions here:
https://github.com/systemd/systemd/pull/22391#issuecomment-1040092633
We should treat ./some.service and $PWD/some.service as equivalent. But we'd
try to send the relative paths over dbus, which can't work well:
$ sudo systemctl enable ./test2.service
Failed to look up unit file state: Invalid argument
$ sudo systemctl enable $PWD/test2.service
Created symlink /etc/systemd/system/multi-user.target.wants/test2.service → /home/zbyszek/src/systemd/test2.service.
Created symlink /etc/systemd/system/test2.service → /home/zbyszek/src/systemd/test2.service.
Now both are equivalent.
Most of the codebase does this. Here we were using 'p' or 'paths'
instead. Those names are very generic and not good for a "global-like"
object like the LookupPaths instance. And we also have 'path' variable,
and it's confusing to have 'path' and 'paths' in the same function that
are unrelated.
Also pass down LookupPaths* lower in the call stack, in preparation for
future changes.
