cruft-ng, a rewrite of Debian 'cruft' engine

cruft-ng is a program to look over your system for anything that shouldn't be there, but is; or for anything that should be there, but isn't.

Cruft was built as a main shell scripts that spawn hundreds of helper processes (other shell scripts, perl programs, C programs).

This project attempts to keep all the main functionality in one process; while output remains 100% identical to cruft's one.

The new cpigs program included provides a more analytical interface: dump to .csv or viewing with ncdu tool.

cruft-ng needs a ruleset:

/usr/libexec/explain/ : this is a set of shell scripts plugins for handling of special cases.
/usr/share/cruft/rules/* : these are glob-like files, quite like, but not totally the same than in your standard shell. This re-uses cruft' shellexp.c

These can be moved into individual Debian package (or some proprietary .deb distro in my case) using dh-cruft.

/usr/share/cruft/ruleset : this is a fallback ruleset for packages not yet providing their own rules.

We are not in 1998 anymore, this should not be a problem to keep 32 or 64mb of data in memory; so the intermediary spooling in /var/spool/cruft/ is un-needed; unless it is processed by external tools
Debian
cruft-ng used to use mlocate binary database instead of running 'find' on the whole file system, this way, it could also be setgid mlocate to be able to access the db and be run by any user; while cruft need to be run as root.
PS: nowadays mlocate has been replaced by plocate. The new binary database is in a private format without a promise of stability, so cruft-ng simply calls ou the plocate binary. This means it can run as non-root and mostly gives the same results. It of course can not list files only root can see.
cruft scan /home with find twice, only to detect files not owned by /home/$user & broken symlinks; cruft-ng never scan /home (cruft also give false positives for files created/deleted between the two 'find' runs)

cruft-ng doesn't detect broken symlinks at this time; it's a different topic and should be split in a separate tool. (and this really needs 'find' and can't be done with {m|p}locate db).
move to Salsa, enable C.I.
read the AppArmor globbing patterns (with libapparmor1)
https://www.codeproject.com/Articles/5163931/Fast-String-Matching-with-Wildcards-Globs-and-Giti
Bugs found in other Debian packages (by this tool): https://bugs.debian.org/cgi-bin/pkgreport.cgi?tag=cruft;users=cruft-ng@packages.debian.org

This is licensed GPL-2+, as cruft itself. This reuses shellexp.c, explain/* and filters-unex/* from cruft.

1998-2000 Anthony Towns 2005-2011 Marcin Owsiany 2014-2023 Alexandre Detiste