Make the new login button stuff more automatic

By default it'll look at your environment to try to figure out which
display manager is used in order to start a new session.  We first try
the org.freedesktop.DisplayManager dbus interface, and if that fails,
inspect XDG_SESSION_DESKTOP to try to figure out which display manager
is running.

The user can also still specify the correct display manager, or a custom
command.

Cargo.lock

@@ -318,6 +318,7 @@ dependencies = [
  "bscreensaver-util",
  "glib",
  "gtk",
+ "log",
 ]
 
 [[package]]
@@ -347,9 +348,11 @@ dependencies = [
  "humantime",
  "lazy_static",
  "libc",
+ "shell-words",
  "toml",
  "xcb",
  "xdg",
+ "zbus",
 ]
 
 [[package]]

dialog-gtk3/src/main.rs

@@ -4,9 +4,9 @@ use gethostname::gethostname;
 use glib::GString;
 use gtk::{prelude::*, Button, Entry, Label, Plug, Window};
 use log::{debug, error, warn};
-use std::{io::{self, Write}, process::{exit, Command}, rc::Rc, thread, time::Duration};
+use std::{io::{self, Write}, process::exit, rc::Rc, thread, time::Duration};
 
-use bscreensaver_util::{init_logging, settings::Configuration};
+use bscreensaver_util::{init_logging, settings::Configuration, desktop::NewLoginCommand};
 
 const DIALOG_UPDATE_INTERVAL: Duration = Duration::from_millis(100);
 const DIALOG_TIMEOUT: Duration = Duration::from_secs(60);
@@ -15,11 +15,13 @@ fn main() -> anyhow::Result<()> {
     init_logging("BSCREENSAVER_DIALOG_GTK3_LOG");
     glib::log_set_default_handler(glib::rust_log_handler);
 
-    let mut config = Configuration::load()?;
+    let config = Configuration::load()?;
-    let new_login_command = config.new_login_command
+    let new_login_command =
-        .take()
+        if config.new_login_command == NewLoginCommand::Disabled {
-        .map(|nlc| shell_words::split(&nlc))
+            None
-        .transpose()?;
+        } else {
+            Some(config.new_login_command.clone())
+        };
 
     let standalone = std::env::var("BSCREENSAVER_DIALOG_STANDALONE").is_ok();
 
@@ -245,14 +247,14 @@ fn main() -> anyhow::Result<()> {
             .label("New Login")
             .build();
         new_login_button.connect_clicked(move |_| {
-            let cmd = &new_login_command[0];
+            let new_login_command = new_login_command.clone();
-            let empty = Vec::<String>::new();
+            thread::spawn(move || {
-            let args = if new_login_command.len() > 1 { &new_login_command[1..] } else { &empty };
+                if let Err(err) = new_login_command.run() {
-            if let Err(err) = Command::new(cmd).args(args).spawn() {
+                    warn!("Failed to run new login command: {}", err);
-                warn!("Failed to run new login command: {}", err);
+                } else {
-            } else {
+                    exit(1);
-                exit(1);
+                }
-            }
+            });
         });
         hbox.pack_start(&new_login_button, false, true, 8);
     }

settings/Cargo.toml

@@ -8,3 +8,4 @@ anyhow = "1"
 bscreensaver-util = { path = "../util" }
 glib = "0.15"
 gtk = { version = "0.15", features = ["v3_20"] }
+log = "0.4"

settings/src/main.rs

@@ -1,17 +1,20 @@
 use gtk::{glib, prelude::*};
 use glib::clone;
+use log::warn;
 use std::{env, process::exit, time::Duration};
 
-use bscreensaver_util::settings::Configuration;
+use bscreensaver_util::{init_logging, settings::Configuration, desktop::NewLoginCommand};
 
 #[derive(Clone)]
 struct Widgets {
     lock_timeout: gtk::SpinButton,
     blank_before_locking: gtk::SpinButton,
-    new_login_command: gtk::Entry,
+    new_login_command_combo: gtk::ComboBoxText,
+    custom_new_login_command_entry: gtk::Entry,
 }
 
 fn main() -> anyhow::Result<()> {
+    init_logging("BSCREENSAVER_SETTINGS");
     let config = Configuration::load()?;
 
     let app = gtk::Application::builder()
@@ -122,27 +125,83 @@ fn show_ui(app: &gtk::Application, config: &Configuration) {
     label_sg.add_widget(&label);
     hbox.pack_start(&label, false, false, 0);
 
-    let new_login_command_entry = gtk::Entry::builder()
+    let vbox = gtk::Box::builder()
-        .text(config.new_login_command.as_ref().unwrap_or(&"".to_string()))
+        .orientation(gtk::Orientation::Vertical)
-        .width_chars(30)
+        .spacing(8)
-        .activates_default(true)
         .build();
-    hbox.pack_start(&new_login_command_entry, false, false, 0);
+    hbox.pack_start(&vbox, true, true, 0);
+
+    let new_login_command_combo = gtk::ComboBoxText::builder()
+        .build();
+    new_login_command_combo.append_text(NewLoginCommand::Auto.as_str());
+    new_login_command_combo.append_text(NewLoginCommand::DisplayManagerDBus.as_str());
+    new_login_command_combo.append_text(NewLoginCommand::Gdm.as_str());
+    new_login_command_combo.append_text(NewLoginCommand::Kdm.as_str());
+    new_login_command_combo.append_text(NewLoginCommand::LightDm.as_str());
+    new_login_command_combo.append_text(NewLoginCommand::Lxdm.as_str());
+    new_login_command_combo.append_text(NewLoginCommand::Custom("".to_string()).as_str());
+    new_login_command_combo.append_text(NewLoginCommand::Disabled.as_str());
+    vbox.pack_start(&new_login_command_combo, false, false, 0);
+
+    let (custom_new_login_command_hbox, custom_new_login_command_entry, custom_new_login_command_button) = {
+        let hbox = gtk::Box::builder()
+            .orientation(gtk::Orientation::Horizontal)
+            .spacing(8)
+            .sensitive(false)
+            .build();
+        topvbox.pack_start(&hbox, false, false, 0);
+
+        let spacer = gtk::Box::builder()
+            .orientation(gtk::Orientation::Horizontal)
+            .spacing(0)
+            .build();
+        label_sg.add_widget(&spacer);
+        hbox.pack_start(&spacer, false, false, 0);
+
+        let label = gtk::Label::builder()
+            .label("Custom Command:")
+            .tooltip_text("Custom command to run when the 'New Login' button is clicked in the unlock dialog")
+            .xalign(0.0)
+            .build();
+        hbox.pack_start(&label, false, false, 0);
+
+        let entry = gtk::Entry::builder()
+            .width_chars(30)
+            .activates_default(true)
+            .build();
+        hbox.pack_start(&entry, false, false, 0);
+
+        let button = gtk::Button::from_icon_name(Some("folder-open"), gtk::IconSize::Button);
+        hbox.pack_start(&button, false, false, 0);
+
+        (hbox, entry, button)
+    };
+
+    match &config.new_login_command {
+        NewLoginCommand::Custom(cmd) => {
+            custom_new_login_command_entry.set_text(cmd.as_str());
+            custom_new_login_command_hbox.set_sensitive(true);
+        },
+        _ => (),
+    };
+    new_login_command_combo.set_active(Some(config.new_login_command.ord()));
+    new_login_command_combo.connect_changed(clone!(@strong custom_new_login_command_hbox => move |combo| {
+        let sensitive = combo.active().unwrap_or(0) == NewLoginCommand::Custom("".to_string()).ord();
+        custom_new_login_command_hbox.set_sensitive(sensitive);
+    }));
 
     let widgets = Widgets {
         lock_timeout: lock_timeout_spinbutton.clone(),
         blank_before_locking: blank_before_locking_spinbutton.clone(),
-        new_login_command: new_login_command_entry.clone(),
+        new_login_command_combo: new_login_command_combo.clone(),
+        custom_new_login_command_entry: custom_new_login_command_entry.clone(),
     };
     mainwin.connect_delete_event(clone!(@strong config, @strong widgets, @strong app, @strong mainwin => move |_,_| {
         Inhibit(!confirm_cancel(&config, &widgets, &mainwin))
     }));
-
+    custom_new_login_command_button.connect_clicked(clone!(@strong mainwin, @strong widgets => move |_| {
-    let button = gtk::Button::from_icon_name(Some("folder-open"), gtk::IconSize::Button);
-    button.connect_clicked(clone!(@strong mainwin, @strong widgets => move |_| {
         run_file_chooser(&mainwin, &widgets);
     }));
-    hbox.pack_start(&button, false, false, 0);
 
     let button_box = gtk::ButtonBox::builder()
         .spacing(8)
@@ -177,7 +236,7 @@ fn show_ui(app: &gtk::Application, config: &Configuration) {
 
 fn run_file_chooser(mainwin: &gtk::ApplicationWindow, widgets: &Widgets) {
     let file_chooser = gtk::FileChooserNative::new(
-        Some("New Login Command"),
+        Some("Custom New Login Command"),
         Some(mainwin),
         gtk::FileChooserAction::Open,
         Some("Select"),
@@ -187,7 +246,7 @@ fn run_file_chooser(mainwin: &gtk::ApplicationWindow, widgets: &Widgets) {
     file_chooser.hide();
     if response == gtk::ResponseType::Accept {
         if let Some(filename) = file_chooser.filename() {
-            widgets.new_login_command.set_text(&filename.to_string_lossy());
+            widgets.custom_new_login_command_entry.set_text(&filename.to_string_lossy());
         }
     }
 }
@@ -243,7 +302,19 @@ fn build_new_configuration(old_config: &Configuration, widgets: &Widgets) -> (Co
     let mut new_config = old_config.clone();
     new_config.lock_timeout = Duration::from_secs(widgets.lock_timeout.adjustment().value() as u64 * 60);
     new_config.blank_before_locking = Duration::from_secs(widgets.blank_before_locking.adjustment().value() as u64 * 60);
-    new_config.new_login_command = Some(widgets.new_login_command.text()).filter(|s| !s.is_empty()).map(|s| s.to_string());
+
+    new_config.new_login_command = match NewLoginCommand::try_from(widgets.new_login_command_combo.active().unwrap_or(0) as u32) {
+        Ok(NewLoginCommand::Custom(_)) => Some(widgets.custom_new_login_command_entry.text())
+            .filter(|s| !s.is_empty())
+            .map(|s| NewLoginCommand::Custom(s.to_string()))
+            .unwrap_or(NewLoginCommand::Auto),
+        Ok(nlc) => nlc,
+        Err(_) => {
+            warn!("BUG: couldn't figure out new login command type from combo box");
+            NewLoginCommand::Auto
+        },
+    };
+
     let changed = old_config != &new_config;
     (new_config, changed)
 }

util/Cargo.toml

@@ -12,6 +12,8 @@ env_logger = "0.9"
 humantime = "2"
 lazy_static = "1"
 libc = "0.2"
+shell-words = "1"
 toml = "0.5"
 xcb = { git = "https://github.com/rust-x-bindings/rust-xcb", rev = "d09b5f91bc07d56673f1bc0d6c7ecd72b5ff7b3e", features = ["randr", "screensaver", "xfixes"] }
 xdg = "2"
+zbus = "2"

util/src/desktop.rs

@@ -0,0 +1,171 @@
+use std::{env, fmt, process::Command};
+
+const GDM_CMD: &[&str] = &[ "gdmflexiserver", "-ls" ];
+const KDM_CMD: &[&str] = &[ "kdmctl", "reserve" ];
+const LIGHTDM_CMD: &[&str] = &[ "dm-tool", "switch-to-greeter" ];
+const LXDM_CMD: &[&str] = &[ "lxdm", "-c", "USER_SWITCH" ];
+
+#[derive(Debug, Clone, PartialEq)]
+pub enum NewLoginCommand {
+    Auto,
+    DisplayManagerDBus,
+    Gdm,
+    Kdm,
+    LightDm,
+    Lxdm,
+    Custom(String),
+    Disabled,
+}
+
+impl NewLoginCommand {
+    pub fn run(&self) -> anyhow::Result<()> {
+        match self {
+            Self::Auto => auto_run(),
+            Self::DisplayManagerDBus => call_dbus(),
+            Self::Gdm => run(GDM_CMD),
+            Self::Kdm => run(KDM_CMD),
+            Self::LightDm => run(LIGHTDM_CMD),
+            Self::Lxdm => run(LXDM_CMD),
+            Self::Custom(cmd) => shell_words::split(cmd.as_str())
+                .map_err(|err| err.into())
+                .and_then(|argvec| {
+                    let argv: Vec<&str> = argvec.iter().map(|s| s.as_str()).collect();
+                    run(&argv).map_err(|err| err.into())
+                }),
+            Self::Disabled => Ok(()),
+        }
+    }
+
+    pub fn as_str(&self) -> &'static str {
+        match self {
+            Self::Auto => "Auto",
+            Self::DisplayManagerDBus => "DBus (desktop-agnostic)",
+            Self::Gdm => "GDM (GNOME)",
+            Self::Kdm => "KDM (KDE)",
+            Self::LightDm => "LightDM",
+            Self::Lxdm => "LXDM (LXDE)",
+            Self::Custom(_) => "Custom",
+            Self::Disabled => "Disabled",
+        }
+    }
+
+    pub fn ord(&self) -> u32 {
+        match self {
+            Self::Auto => 0,
+            Self::DisplayManagerDBus => 1,
+            Self::Gdm => 2,
+            Self::Kdm => 3,
+            Self::LightDm => 4,
+            Self::Lxdm => 5,
+            Self::Custom(_) => 6,
+            Self::Disabled => 7,
+        }
+    }
+}
+
+impl fmt::Display for NewLoginCommand {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "{}", self.as_str())
+    }
+}
+
+impl TryFrom<u32> for NewLoginCommand {
+    type Error = anyhow::Error;
+    fn try_from(value: u32) -> Result<Self, Self::Error> {
+        match value {
+            0 => Ok(Self::Auto),
+            1 => Ok(Self::DisplayManagerDBus),
+            2 => Ok(Self::Gdm),
+            3 => Ok(Self::Kdm),
+            4 => Ok(Self::LightDm),
+            5 => Ok(Self::Lxdm),
+            6 => Ok(Self::Custom("".to_string())),
+            7 => Ok(Self::Disabled),
+            other => Err(anyhow::anyhow!("Unknown ordinal for NewLoginCommand: {}", other)),
+        }
+    }
+}
+
+impl TryFrom<&toml::Value> for NewLoginCommand {
+    type Error = anyhow::Error;
+    fn try_from(value: &toml::Value) -> Result<Self, Self::Error> {
+        if let Some(s) = value.as_str() {
+            return match s {
+                "auto" => Ok(Self::Auto),
+                "dbus" => Ok(Self::DisplayManagerDBus),
+                "gdm" => Ok(Self::Gdm),
+                "kdm" => Ok(Self::Kdm),
+                "lightdm" => Ok(Self::LightDm),
+                "lxdm" => Ok(Self::Lxdm),
+                "disabled" => Ok(Self::Disabled),
+                other => Err(anyhow::anyhow!("Unknown value '{}' for new login command", other)),
+            };
+        }
+
+        if let Some(arr) = value.as_array() {
+            let argv = arr.into_iter()
+                .map(|v| v.as_str().map(|s| s.to_string()).ok_or_else(|| anyhow::anyhow!("Custom command must be made of strings")))
+                .collect::<anyhow::Result<Vec<String>>>()?;
+            return Ok(Self::Custom(shell_words::join(argv)))
+        }
+
+        Err(anyhow::anyhow!("Unknown value for new login command"))
+    }
+}
+
+impl TryInto<toml::Value> for NewLoginCommand {
+    type Error = anyhow::Error;
+    fn try_into(self) -> Result<toml::Value, Self::Error> {
+        match self {
+            Self::Auto => Ok(toml::Value::String("auto".to_string())),
+            Self::DisplayManagerDBus => Ok(toml::Value::String("dbus".to_string())),
+            Self::Gdm => Ok(toml::Value::String("gdm".to_string())),
+            Self::Kdm => Ok(toml::Value::String("kdm".to_string())),
+            Self::LightDm => Ok(toml::Value::String("lightdm".to_string())),
+            Self::Lxdm => Ok(toml::Value::String("lxdm".to_string())),
+            Self::Custom(cmd) => shell_words::split(cmd.as_str())
+                .map_err(|err| err.into())
+                .map(|words| toml::Value::Array(words.into_iter().map(|s| toml::Value::String(s)).collect())),
+            Self::Disabled => Ok(toml::Value::String("disabled".to_string())),
+        }
+    }
+}
+
+fn auto_run() -> anyhow::Result<()> {
+    if let Ok(_) = call_dbus() {
+        return Ok(())
+    }
+
+    if let Some(session_desktop) = env::var("XDG_SESSION_DESKTOP").map(|s| s.to_lowercase()).ok() {
+        match session_desktop.as_str() {
+            "gnome" | "gdm" => run(GDM_CMD),
+            "kde" | "kdm" => run(KDM_CMD),
+            "lightdm-session" => run(LIGHTDM_CMD),
+            "lxde" | "lxdm" => run(LXDM_CMD),
+            other => Err(anyhow::anyhow!("Couldn't determine how to start a new login session for session type {}", other)),
+        }
+    } else {
+        Err(anyhow::anyhow!("Couldn't determine how to start a new login session"))
+    }
+}
+
+fn call_dbus() -> anyhow::Result<()> {
+    let seat_path = env::var("XDG_SEAT_PATH")
+        .unwrap_or_else(|_| "/org/freedesktop/DisplayManager/Seat0".to_string());
+    let bus = zbus::blocking::Connection::system()?;
+    let proxy = zbus::blocking::Proxy::new(
+        &bus,
+        "org.freedesktop.DisplayManager",
+        seat_path,
+        "org.freedesktop.DisplayManager.Seat"
+    )?;
+    proxy.call("SwitchToGreeter", &())?;
+    Ok(())
+}
+
+fn run(argv: &[&str]) -> anyhow::Result<()> {
+    Command::new(argv[0])
+        .args(if argv.len() > 1 { &argv[1..argv.len()-1] } else { &[] })
+        .spawn()?;
+    Ok(())
+}

util/src/lib.rs

@@ -1,6 +1,7 @@
 use std::{ffi::CStr, io};
 use xcb::x;
 
+pub mod desktop;
 pub mod settings;
 
 pub const BSCREENSAVER_WM_CLASS: &[u8] = b"bscreensaver\0Bscreensaver\0";

util/src/settings.rs

@@ -2,6 +2,8 @@ use anyhow::anyhow;
 use std::{fmt, fs::{self, File}, io::{Read, Write}, path::PathBuf, time::Duration};
 use toml::Value;
 
+use crate::desktop::NewLoginCommand;
+
 const CONFIG_FILE_RELATIVE_PATH: &str = "bscreensaver/bscreensaver.toml";
 
 const LOCK_TIMEOUT: &str = "lock-timeout";
@@ -51,7 +53,7 @@ pub struct Configuration {
     pub lock_timeout: Duration,
     pub blank_before_locking: Duration,
     pub dialog_backend: DialogBackend,
-    pub new_login_command: Option<String>,
+    pub new_login_command: NewLoginCommand,
 }
 
 impl Configuration {
@@ -80,7 +82,7 @@ impl Configuration {
             };
             config.new_login_command = match config_toml.get("new-login-command") {
                 None => config.new_login_command,
-                Some(val) => val.as_str().map(|s| s.to_string()),
+                Some(val) => val.try_into().unwrap_or(NewLoginCommand::Auto),
             };
         }
 
@@ -99,9 +101,7 @@ impl Configuration {
         config_map.insert(LOCK_TIMEOUT.to_string(), Value::String(format_duration(self.lock_timeout).to_string()));
         config_map.insert(BLANK_BEFORE_LOCKING.to_string(), Value::String(format_duration(self.blank_before_locking).to_string()));
         config_map.insert(DIALOG_BACKEND.to_string(), Value::String(self.dialog_backend.to_string()));
-        if let Some(new_login_command) = &self.new_login_command {
+        config_map.insert(NEW_LOGIN_COMMAND.to_string(), self.new_login_command.clone().try_into()?);
-            config_map.insert(NEW_LOGIN_COMMAND.to_string(), Value::String(new_login_command.clone()));
-        }
 
         let config_path = xdg::BaseDirectories::new()?.place_config_file(CONFIG_FILE_RELATIVE_PATH)?;
         let mut tmp_filename = config_path.file_name().unwrap().to_os_string();
@@ -122,7 +122,7 @@ impl Default for Configuration {
             lock_timeout:  Duration::from_secs(60 * 10),
             blank_before_locking: Duration::ZERO,
             dialog_backend: DialogBackend::Gtk3,
-            new_login_command: None,
+            new_login_command: NewLoginCommand::Auto,
         }
     }
 }