desktop-common.sh deletes XDG dirs and creates self-referential symlinks on classic snap first launch

[jardaKarlik]

Description

On first launch of the WaveTerm snap (v0.14.5, Ubuntu 26.04), desktop-common.sh destroyed all standard XDG user directories (Desktop, Documents, Downloads, Music, Pictures, Public, Templates, Videos) and replaced them with broken self-referential symlinks, making them inaccessible from the file manager.

Root cause

WaveTerm uses confinement: classic, which means $HOME is not isolated — it stays as the user's real home (e.g. /home/leeCZ). The desktop-common.sh script was written for strict confinement where $HOME = $SNAP_USER_DATA ≠ $REALHOME. With classic confinement both variables are identical.

The broken code path (around line 204–213 of desktop-common.sh):

# can_open_file uses "head -c0" which always fails on directories → sets needs_xdg_links=true

b="$(realpath "${XDG_SPECIAL_DIRS_PATHS[$i]}" --relative-to="$HOME")"
if [ -e "$REALHOME/$b" ]; then
  if [ -d "$HOME/$b" ]; then
    rmdir "$HOME/$b"          # ← DELETES the real directory
  fi
  if [ ! -e "$HOME/$b" ]; then
    ln -s "$REALHOME/$b" "$HOME/$b"   # ← ln -s /home/user/Desktop /home/user/Desktop
  fi                                  #   (points to itself — both vars are /home/user)
fi

Steps to reproduce

1. Fresh Ubuntu install, user has standard XDG directories (Desktop, Documents, etc.)
2. Install WaveTerm snap: snap install waveterm
3. Launch WaveTerm for the first time
4. Open the file manager — standard home folders are now inaccessible broken symlinks

Expected

Snap home ($SNAP_USER_DATA) gets symlinks pointing to real XDG dirs — leaving the real home untouched.

Actual

Real XDG directories are deleted and replaced with self-referential symlinks in the real home:

lrwxrwxrwx Desktop -> /home/user/Desktop
lrwxrwxrwx Documents -> /home/user/Documents
...

Suggested fix

Guard the symlink creation block so it only runs when $HOME != $REALHOME (i.e. strict confinement):

if [ $needs_xdg_links = true ] && [ "$HOME" != "$REALHOME" ]; then

Notes

The bug also re-triggers on every snap version update (when SNAP_DESKTOP_COMPONENTS_NEED_UPDATE=true), so affected users will keep hitting it after each WaveTerm upgrade until fixed.

Environment

• WaveTerm: 0.14.5 (snap revision 204, classic confinement)
• OS: Ubuntu 26.04
• Shell: bash