keyfile: add helper functions to record loaded UUID files
This code will be used later. We want to remember which keyfiles are currently loaded (or hidden). With the addition or multiple keyfile directories (soon), there are two cases where this matters: - if there are multiple keyfiles which reference the same UUID, we can only load one of them. That is already a problem today with only one keyfile directory, where multiple files can reference the same UUID. The implementation will pick the file based on priorities (like the file modification date). However, the user may call explicitly call `nmcli connection load`. In that case, we cannot reload all files to find out whether the to be loaded file is hidden according to the defined priorities. We cannot do that, because we must not make decisions based on files on disk, which we are not told to reload. So, during a `nmcli connection load` we must look at unrelated files, to determine how to load the file. Instead, we do allow the user to load any file, even if it would be shadowed by other files. When we do that, we may want to persist which file is currently loaded, so that a service restart and a `nmcli connection reload` does not undo the load again. This can be later later be solved by writing a symlink "/var/run/NetworkManager/system-connections/.loaded-$UUID.nmkeyfile" which targets the currently active file. - if a profile was loaded from read-only persistant storage, the user may still delete the profile. We also need to remember the deletion of the file. That will be achieved by symlinking "/dev/null" as "/etc/NetworkManager/system-connections/.loaded-$UUID.nmkeyfile". Add helper functions to read and write these symlinks.
th/keyfile-loaded-uuid in 18 minutes and 9 seconds (queued for 117 minutes and 32 seconds)5 jobs for