Improve dinit service files (#3193)

* Improve dinit service files and niri-session

Two main changes were made:
 - After a discussion in davmac314/dinit#496, 2 dinit services are now
   provided. The first one is 'niri', which runs niri itself, and the
   second one is 'niri.target' which brings up all the dependences from
   user configuration.
 - Made the behaviour of 'niri-session' when running under dinit closer
   to the behaviour when running under systemd. In particular, now the
   script wait for service completion, because some login managers shut
   the session down the moment the startup script completes.

* Update paths in docs

resources/dinit/niri

@@ -1,8 +1,7 @@
-type              = process
-command           = niri --session
-restart           = false
-working-dir       = $HOME
-depends-on        = dbus
-after             = niri-shutdown
-chain-to          = niri-shutdown
-options:          always-chain
+type               = process
+command            = niri --session
+restart            = false
+working-dir        = $HOME
+ready-notification = pipevar:NOTIFY_FD
+logfile            = $HOME/.local/share/niri/niri.log
+depends-on:        dbus

resources/dinit/niri-shutdown

@@ -1,3 +0,0 @@
-type               = scripted
-command            = dinitctl -u setenv WAYLAND_DISPLAY= XDG_SESSION_TYPE= XDG_CURRENT_DESKTOP= NIRI_SOCKET=
-restart            = false

resources/dinit/niri.target

@@ -0,0 +1,6 @@
+type           = internal
+restart        = false
+depends-on:    niri
+waits-for.d:   $XDG_CONFIG_HOME/dinit.d/niri.d/
+waits-for.d:   $HOME/.config/dinit.d/niri.d/
+waits-for.d:   /etc/dinit.d/user/niri.d/

resources/niri-session

@@ -59,13 +59,37 @@ elif hash dinitctl >/dev/null 2>&1; then
     fi
 
     # Make sure there's no already running session.
-    if dinitctl --user is-started niri >/dev/null 2>&1; then
+    if dinitctl --quiet --user is-started niri 2>/dev/null; then
       echo 'A niri session is already running.'
       exit 1
     fi
 
+    # Import the login manager environment into dinit
+    # Might not work correctly for multiline variable names, but
+    # it is reasonable to assume there are none
+    awk 'BEGIN{for(v in ENVIRON) if (v != "AWKPATH" && v != "AWKLIBPATH") print v}' 2>/dev/null | xargs dinitctl --quiet --user setenv 2>/dev/null
+
+    # Usually the dbus service would start as niri's dependency and inherit
+    # environment from dinit, but in case it has already started we need
+    # to update its environment.
+    if hash dbus-update-activation-environment >/dev/null 2>&1; then
+        dbus-update-activation-environment --all >/dev/null 2>&1
+    fi
+
+    # Create the directory for the logfile, if doesn't exist
+    mkdir --parents $HOME/.local/share/niri
     # Start niri
-    dinitctl --user start niri
+    dinitctl --quiet --user start niri.target 2>&1
+
+    # Wait for termination
+    dinit-monitor --user --initial -c $'sh -c " 
+        if [ "%s" = "stopped" ] || [ "%s" = "failed" ]; then
+            ppid=$(ps -o ppid= -p $$)
+            kill $ppid
+        fi"' niri >/dev/null 2>&1
+
+    # Unset environment that we've set.
+    dinitctl --quiet --user unsetenv WAYLAND_DISPLAY DISPLAY XDG_SESSION_TYPE XDG_CURRENT_DESKTOP NIRI_SOCKET 2>/dev/null
 else
     echo "No systemd or dinit detected, please use niri --session instead."
 fi