Add support for $XDG_STATE_HOME

[62832]

The most recent version of the XDG Base Directory Specification from 2021 introduces the new $XDG_STATE_HOME directory for non-essential "state" data such as history and logs.

The $XDG_STATE_HOME contains state data that should persist between (application) restarts, but that is not important or portable enough to the user that it should be stored in $XDG_DATA_HOME. It may contain:

• actions history (logs, history, recently used files, …)
• current state of the application that can be reused on a restart (view, layout, open files, undo history, …)

This PR adds support for this directory via the weechat_state_dir property, and uses this directory by default from now on to store log files. Closes #1747.

[flashcode]

Hi,

Thanks for this PR.

There's a discussion about what to move to the XDG state directory in this issue: #1747.
And I concur with @trygveaa about the fact that buffer log files (from logger plugin) are important and just not "state", and should stay in data directory.

The specification is not very clear about what should be moved anyway.

Any thoughts from other people?

[62832]

buffer log files (from logger plugin) are important and just not "state", and should stay in data directory.

No problem, the default for those can simply be changed back to ${weechat_data_dir} instead then. Although, I would personally argue that even if the log files aren't overwritten, then much like a history file, they really ought to be considered "state".

[flashcode]

By the way I'm not even sure if the weechat.log file should be in $XDG_STATE_HOME or $XDG_RUNTIME_DIR directory, as it's a temporary log file used for lock (it's used to prevent two weechat instances to use the same home directory).

[62832]

Considering that weechat.log doesn't remove itself upon exit like a regular "lock" file would, I would treat it as a regular log file for $XDG_STATE_HOME.

[flashcode]

Thanks, I squashed commits and merged without the changes in logger plugin.