tools: Migrate changed overrides settings

While the new per-desktop overrides in GIO are easier to use for
both developers and users, it is still inconvenient for everyone
who changed the defaults using the old overrides hack to lose
their settings. Address this by running a small script on startup
that migrates existing settings.

https://bugzilla.gnome.org/show_bug.cgi?id=786496

data/gnome-shell-overrides-migration.desktop.in

@@ -0,0 +1,5 @@
+[Desktop Entry]
+Type=Application
+Name=GNOME settings overrides migration
+NoDisplay=True
+Exec=@libexecdir@/gnome-shell-overrides-migration.sh

data/meson.build

@@ -94,6 +94,15 @@ schema = configure_file(
 )
 install_data('00_org.gnome.shell.gschema.override', install_dir: schemadir)
 
+overrides_migration_conf = configuration_data()
+overrides_migration_conf.set('libexecdir', libexecdir)
+overrides_migration = configure_file(
+  input: 'gnome-shell-overrides-migration.desktop.in',
+  output: 'gnome-shell-overrides-migration.desktop',
+  configuration: overrides_migration_conf,
+  install_dir: autostartdir
+)
+
 if have_systemd
   unitconf = configuration_data()
   unitconf.set('bindir', bindir)

meson.build

@@ -44,10 +44,12 @@ datadir = join_paths(prefix, get_option('datadir'))
 libdir = join_paths(prefix, get_option('libdir'))
 libexecdir = join_paths(prefix, get_option('libexecdir'))
 mandir = join_paths(prefix, get_option('mandir'))
+sysconfdir = join_paths(prefix, get_option('sysconfdir'))
 
 pkgdatadir = join_paths(datadir, meson.project_name())
 pkglibdir = join_paths(libdir, meson.project_name())
 
+autostartdir = join_paths(sysconfdir, 'xdg', 'autostart')
 convertdir = join_paths(datadir, 'GConf', 'gsettings')
 desktopdir = join_paths(datadir, 'applications')
 ifacedir = join_paths(datadir, 'dbus-1', 'interfaces')
@@ -203,6 +205,7 @@ subdir('src')
 subdir('po')
 subdir('data')
 subdir('tests')
+subdir('tools')
 
 if get_option('gtk_doc')
   subdir('docs/reference')

tools/gnome-shell-overrides-migration.sh

@@ -0,0 +1,38 @@
+#!/bin/sh
+
+PKG_DATA_DIR=${XDG_DATA_HOME:-$HOME/.local/share}/gnome-shell
+
+MIGRATION_GUARD=$PKG_DATA_DIR/gnome-overrides-migrated
+OVERRIDE_SCHEMA=
+
+if [ -f $MIGRATION_GUARD ]; then
+  exit # already migrated
+fi
+
+# Find the right session
+if echo $XDG_CURRENT_DESKTOP | grep -q -v GNOME; then
+  exit # not a GNOME session
+fi
+
+if echo $XDG_CURRENT_DESKTOP | grep -q Classic; then
+  OVERRIDE_SCHEMA=org.gnome.shell.extensions.classic-overrides
+else
+  OVERRIDE_SCHEMA=org.gnome.shell.overrides
+fi
+
+mkdir -p $PKG_DATA_DIR
+
+for k in `gsettings list-keys $OVERRIDE_SCHEMA`
+do
+  if [ $k = button-layout ]; then
+    orig_schema=org.gnome.desktop.wm.preferences
+  else
+    orig_schema=org.gnome.mutter
+  fi
+
+  oldValue=`gsettings get $OVERRIDE_SCHEMA $k`
+  curValue=`gsettings get $orig_schema $k`
+  if [ $oldValue != $curValue ]; then
+    gsettings set $orig_schema $k $oldValue
+  fi
+done && touch $MIGRATION_GUARD

tools/meson.build

@@ -0,0 +1,4 @@
+install_data('gnome-shell-overrides-migration.sh',
+  install_dir: libexecdir,
+  install_mode: 'rwxr-xr-x'
+)