Override leftover SDDM drop-ins so the greeter cannot land on a black screen

2026-09-20 07:06:23 -04:00
parent 8f124f47c2
commit 421c58fab0
8 changed files with 103 additions and 22 deletions
@@ -86,7 +86,9 @@ It runs these steps, in this order, and every one of them is idempotent:

 Step 8 is the one a plain Arch install cannot do without: SDDM's stock Wayland
 greeter runs on `weston`, which Blob does not install, so the greeter is pointed
-at Hyprland instead. [install.md](docs/install.md) covers each step in full.
+at Hyprland instead. It also reports any leftover drop-in that autologs into a
+session that is not installed, which is what a black screen with no login prompt
+usually is. [install.md](docs/install.md) covers each step in full.

 To back out, `./uninstall.sh` removes the session entry, the config, the user
 services, and the symlink, restoring any `.bak` the installer made. The
@@ -0,0 +1,9 @@
+misc {
+  disable_hyprland_logo = true
+  disable_splash_rendering = true
+  force_default_wallpaper = 0
+}
+
+animations {
+  enabled = false
+}
@@ -1,11 +0,0 @@
-hl.config({
-  misc = {
-    disable_hyprland_logo = true,
-    disable_splash_rendering = true,
-    force_default_wallpaper = 0,
-  },
-
-  animations = {
-    enabled = false,
-  },
-})
@@ -2,7 +2,14 @@
 DisplayServer=wayland

 [Wayland]
-CompositorCommand=start-hyprland -- --config /etc/sddm/hyprland-greeter.lua
+CompositorCommand=start-hyprland -- --config /etc/sddm/hyprland-greeter.conf
+
+[Theme]
+Current=
+
+[Autologin]
+User=
+Session=

 [Users]
 RememberLastUser=true
@@ -43,14 +43,33 @@ with `--check`.
   | File | Why |
   | --- | --- |
   | `/usr/local/share/wayland-sessions/blob.desktop` | the session SDDM offers |
-   | `/etc/sddm.conf.d/10-blob.conf` | Wayland greeter, run on Hyprland, remember the last session |
-   | `/etc/sddm/hyprland-greeter.lua` | the greeter's own tiny Hyprland config |
+   | `/etc/sddm.conf.d/zz-blob.conf` | Wayland greeter, run on Hyprland, stock theme, remember the last session |
+   | `/etc/sddm/hyprland-greeter.conf` | the greeter's own tiny Hyprland config |

   The greeter config matters more than it looks: SDDM's stock Wayland greeter
   runs on `weston`, which Blob does not install, so a default SDDM would fail
   to draw anything. `sddm.service` is enabled and the default systemd target is
   set to `graphical.target`, which an Arch install without a display manager
   does not have.
+
+   The `zz-` prefix is load-bearing. SDDM reads `/etc/sddm.conf.d` in
+   alphabetical order and the last file wins, so a leftover `10-wayland.conf`,
+   `10-theme.conf` or `autologin.conf` from another desktop would otherwise
+   override Blob's. For the same reason `zz-blob.conf` blanks `Theme` and
+   `Autologin`: a greeter pointed at an uninstalled theme, or an autologin
+   pointed at a session entry that no longer exists, leaves SDDM on a black
+   screen it never falls back from, and the only way in is a TTY.
+
+   The Omarchy ISO wrote exactly such an autologin, owned by no package, so it
+   outlives Omarchy. The installer reports it and overrides it; deleting it stops
+   the warning:
+
+   ```bash
+   sudo rm /etc/sddm.conf.d/autologin.conf
+   ```
+
+   `--autologin` writes `zzz-blob-autologin.conf`, the only file that sorts after
+   `zz-blob.conf`.
 9. **Launch.** When the installer was run from a console and nothing graphical
   is running, it starts `sddm.service` so the desktop appears without a reboot.
   `--no-launch` prints the command instead. `--autologin` writes
@@ -74,6 +74,7 @@ install_login_config
 install_session_entry
 install_autologin
 enable_display_manager
+report_login_conflicts

 say ""
 if [[ $check == true ]]; then
@@ -1,13 +1,21 @@
 session_entry_dir=/usr/local/share/wayland-sessions
-greeter_compositor_config=/etc/sddm/hyprland-greeter.lua
+session_entry_search_dirs=(/usr/local/share/wayland-sessions /usr/share/wayland-sessions)
+greeter_config_dir=/etc/sddm.conf.d
+greeter_compositor_config=/etc/sddm/hyprland-greeter.conf
+
+# SDDM reads /etc/sddm.conf.d in alphabetical order and the last file wins, so
+# Blob's drop-ins are named to sort after anything a distribution, an installer
+# ISO, or a previous desktop left behind.
+blob_greeter_conf="$greeter_config_dir/zz-blob.conf"
+blob_autologin_conf="$greeter_config_dir/zzz-blob-autologin.conf"

 # SDDM's stock Wayland greeter runs on weston, which Blob does not install.
 # Point it at Hyprland with a greeter-only config instead.
 install_login_config() {
-  install_root_file "$repo_dir/default/sddm/hyprland-greeter.lua" \
-    "$greeter_compositor_config" "sddm/hyprland-greeter.lua"
-  install_root_file "$repo_dir/default/sddm/10-blob.conf" \
-    /etc/sddm.conf.d/10-blob.conf "sddm.conf.d/10-blob.conf"
+  install_root_file "$repo_dir/default/sddm/hyprland-greeter.conf" \
+    "$greeter_compositor_config" "sddm/hyprland-greeter.conf"
+  install_root_file "$repo_dir/default/sddm/zz-blob.conf" \
+    "$blob_greeter_conf" "sddm.conf.d/zz-blob.conf"
 }

 install_session_entry() {
@@ -23,11 +31,54 @@ install_autologin() {
  local generated
  generated="$(mktemp)"
  printf '[Autologin]\nUser=%s\nSession=blob.desktop\n' "$USER" >"$generated"
-  install_root_file "$generated" \
-    /etc/sddm.conf.d/99-blob-autologin.conf "sddm.conf.d/99-blob-autologin.conf"
+  install_root_file "$generated" "$blob_autologin_conf" "sddm.conf.d/zzz-blob-autologin.conf"
  rm -f "$generated"
 }

+session_entry_exists() {
+  local entry="$1"
+  local dir
+
+  for dir in "${session_entry_search_dirs[@]}"; do
+    [[ -e $dir/$entry ]] && return 0
+  done
+
+  return 1
+}
+
+setting_value() {
+  local file="$1" key="$2"
+
+  sed -n "s/^[[:space:]]*$key[[:space:]]*=[[:space:]]*//p" "$file" | tail -1
+}
+
+# zz-blob.conf blanks Theme and Autologin, so a leftover drop-in cannot point the
+# greeter at a theme that was uninstalled or autolog into a session that no
+# longer exists. Either one leaves SDDM on a black screen it never falls back
+# from. Report the leftovers anyway: the file is confusing to find later, and the
+# Omarchy ISO wrote an autologin that no package owns, so it outlives Omarchy.
+report_login_conflicts() {
+  local file session
+  local found=false
+
+  for file in "$greeter_config_dir"/*.conf; do
+    [[ -e $file ]] || continue
+    [[ $file == "$blob_greeter_conf" || $file == "$blob_autologin_conf" ]] && continue
+
+    session="$(setting_value "$file" Session)"
+    [[ -n $session ]] || continue
+    session_entry_exists "$session" && continue
+
+    found=true
+    say "WARN  $file autologs into $session, which is not installed"
+  done
+
+  if [[ $found == true ]]; then
+    say "      Blob's config overrides it, so the greeter still comes up."
+    say "      Delete the file to stop it coming back."
+  fi
+}
+
 # Enabling sddm is not enough on a machine installed without a display manager:
 # its default target is multi-user.target, which never pulls in graphical.target.
 enable_display_manager() {
@@ -7,6 +7,9 @@ config_dir="$HOME/.config"
 session_entry="/usr/local/share/wayland-sessions/blob.desktop"

 root_files=(
+  /etc/sddm.conf.d/zz-blob.conf
+  /etc/sddm.conf.d/zzz-blob-autologin.conf
+  /etc/sddm/hyprland-greeter.conf
  /etc/sddm.conf.d/10-blob.conf
  /etc/sddm.conf.d/99-blob-autologin.conf
  /etc/sddm/hyprland-greeter.lua