Wrong definition of macro paths from ~/.config/user-dirs.dirs if they are not in "$HOME".

[13ilya-old]

When I specify "blacklist ${DOCUMENTS}" in the config, I expect that the path to the documents directory assigned in my KDE will be blocked. But this only works if the path starts with $HOME. If this is not the case, for example (/Data/Documents) then "$HOME/Documents" is used instead.

cat ~/.config/user-dirs.dirs
XDG_DESKTOP_DIR="$HOME/Desktop/"
XDG_DOCUMENTS_DIR="/Data/Documents"
XDG_DOWNLOAD_DIR="$HOME/Downloads/"
XDG_MUSIC_DIR="/Data/Music"
XDG_PICTURES_DIR="/Data/Pictures"
XDG_PUBLICSHARE_DIR="$HOME/"
XDG_TEMPLATES_DIR="$HOME/"
XDG_VIDEOS_DIR="/Data/Video"

openSUSE Tumbleweed
KDE
firejail 0.9.64

[rusty-snake]

But in reality it is just hardcoded to "${HOME}/Documents" ignoring the KDE settings in the file "~/.config/user-dirs.dirs".

It's not hardcoded, user-dirs.dirs is parsed.

$ firejail --noprofile '--blacklist=${DOCUMENTS}' ls Dokumente
ls: cannot open directory 'Dokumente': Permission denied
# Edit ~/.config/user-dirs.dirs: XDG_DOCUMENTS_DIR="$HOME/DokumentenEnte"
firejail --noprofile '--blacklist=${DOCUMENTS}' ls Dokumente DokumentenEnte
Dokumente:
 foo     bar
ls: cannot open directory 'DokumentenEnte': Permission denied

However, user-dirs.dirs is not parse correctly. The code expects that the line for ${DOCUMENTS} starts with XDG_DOCUMENTS_DIR=\"$HOME/ and the part after the / is then used relative to cfg.homedir.

[13ilya-old]

Your script also works for me.
But I'm not specifying the path in $HOME, but on another partition of the disk /Data.
And this is no longer processed, and instead of "/Data/Documents", "$HOME/Documents" is blocked.