feat(cli): allow starting a session detached (#3257)

* feat(cli): allow starting a session detached

* fix tests

7 files changed, 109 insertions, 13 deletions

diff --git a/src/commands.rs b/src/commands.rs
index d37a422a0..e0dbbdc2e 100644
--- a/src/commands.rs
+++ b/src/commands.rs
@@ -407,6 +407,7 @@ pub(crate) fn start_client(opts: CliArgs) {
         let mut config_options = config_options.clone();
         let mut opts = opts.clone();
         let mut is_a_reconnect = false;
+        let mut should_create_detached = false;
 
         if let Some(reconnect_to_session) = &reconnect_to_session {
             // this is integration code to make session reconnects work with this existing,
@@ -417,6 +418,7 @@ pub(crate) fn start_client(opts: CliArgs) {
                 opts.command = Some(Command::Sessions(Sessions::Attach {
                     session_name: reconnect_to_session.name.clone(),
                     create: true,
+                    background: false,
                     force_run_commands: false,
                     index: None,
                     options: None,
@@ -476,6 +478,7 @@ pub(crate) fn start_client(opts: CliArgs) {
         if let Some(Command::Sessions(Sessions::Attach {
             session_name,
             create,
+            background,
             force_run_commands,
             index,
             options,
@@ -487,9 +490,14 @@ pub(crate) fn start_client(opts: CliArgs) {
                 },
                 None => config_options,
             };
+            should_create_detached = background;
 
             let client = if let Some(idx) = index {
-                attach_with_session_index(config_options.clone(), idx, create)
+                attach_with_session_index(
+                    config_options.clone(),
+                    idx,
+                    create || should_create_detached,
+                )
             } else {
                 let session_exists = session_name
                     .as_ref()
@@ -497,7 +505,10 @@ pub(crate) fn start_client(opts: CliArgs) {
                     .unwrap_or(false);
                 let resurrection_layout =
                     session_name.as_ref().and_then(|s| resurrection_layout(&s));
-                if create && !session_exists && resurrection_layout.is_none() {
+                if (create || should_create_detached)
+                    && !session_exists
+                    && resurrection_layout.is_none()
+                {
                     session_name.clone().map(start_client_plan);
                 }
                 match (session_name.as_ref(), resurrection_layout) {
@@ -507,7 +518,11 @@ pub(crate) fn start_client(opts: CliArgs) {
                         }
                         ClientInfo::Resurrect(session_name.clone(), resurrection_layout)
                     },
-                    _ => attach_with_session_name(session_name, config_options.clone(), create),
+                    _ => attach_with_session_name(
+                        session_name,
+                        config_options.clone(),
+                        create || should_create_detached,
+                    ),
                 }
             };
 
@@ -541,6 +556,7 @@ pub(crate) fn start_client(opts: CliArgs) {
                 tab_position_to_focus,
                 pane_id_to_focus,
                 is_a_reconnect,
+                should_create_detached,
             );
         } else {
             if let Some(session_name) = opts.session.clone() {
@@ -555,6 +571,7 @@ pub(crate) fn start_client(opts: CliArgs) {
                     None,
                     None,
                     is_a_reconnect,
+                    should_create_detached,
                 );
             } else {
                 if let Some(session_name) = config_options.session_name.as_ref() {
@@ -595,6 +612,7 @@ pub(crate) fn start_client(opts: CliArgs) {
                                 None,
                                 None,
                                 is_a_reconnect,
+                                should_create_detached,
                             );
                         },
                         _ => {
@@ -609,6 +627,7 @@ pub(crate) fn start_client(opts: CliArgs) {
                                 None,
                                 None,
                                 is_a_reconnect,
+                                should_create_detached,
                             );
                         },
                     }
@@ -632,6 +651,7 @@ pub(crate) fn start_client(opts: CliArgs) {
                     None,
                     None,
                     is_a_reconnect,
+                    should_create_detached,
                 );
             }
         }
diff --git a/zellij-client/src/cli_client.rs b/zellij-client/src/cli_client.rs
index 6d25e21b9..30e406031 100644
--- a/zellij-client/src/cli_client.rs
+++ b/zellij-client/src/cli_client.rs
@@ -138,8 +138,8 @@ fn pipe_client(
             let mut buffer = String::new();
             let _ = stdin.read_line(&mut buffer);
             if buffer.is_empty() {
-                // TODO: consider notifying the relevant plugin that the pipe has ended with a
-                // specialized message
+                let msg = create_msg(None);
+                os_input.send_to_server(msg);
                 break;
             } else {
                 // we've got data! send it down the pipe (most common)
diff --git a/zellij-client/src/lib.rs b/zellij-client/src/lib.rs
index 2d74e0dd4..5e2f80603 100644
--- a/zellij-client/src/lib.rs
+++ b/zellij-client/src/lib.rs
@@ -29,6 +29,7 @@ use zellij_utils::{
     errors::{ClientContext, ContextType, ErrorInstruction},
     input::{config::Config, options::Options},
     ipc::{ClientAttributes, ClientToServerMsg, ExitReason, ServerToClientMsg},
+    pane_size::Size,
     termwiz::input::InputEvent,
 };
 use zellij_utils::{cli::CliArgs, input::layout::Layout};
@@ -168,7 +169,12 @@ pub fn start_client(
     tab_position_to_focus: Option<usize>,
     pane_id_to_focus: Option<(u32, bool)>, // (pane_id, is_plugin)
     is_a_reconnect: bool,
+    start_detached_and_exit: bool,
 ) -> Option<ConnectToSession> {
+    if start_detached_and_exit {
+        start_server_detached(os_input, opts, config, config_options, info, layout);
+        return None;
+    }
     info!("Starting Zellij client!");
 
     let mut reconnect_to_session = None;
@@ -541,6 +547,69 @@ pub fn start_client(
     reconnect_to_session
 }
 
+pub fn start_server_detached(
+    mut os_input: Box<dyn ClientOsApi>,
+    opts: CliArgs,
+    config: Config,
+    config_options: Options,
+    info: ClientInfo,
+    layout: Option<Layout>,
+) {
+    envs::set_zellij("0".to_string());
+    config.env.set_vars();
+
+    let palette = config
+        .theme_config(&config_options)
+        .unwrap_or_else(|| os_input.load_palette());
+
+    let client_attributes = ClientAttributes {
+        size: Size { rows: 50, cols: 50 }, // just so size is not 0, it doesn't matter because we
+        // immediately detach
+        style: Style {
+            colors: palette,
+            rounded_corners: config.ui.pane_frames.rounded_corners,
+            hide_session_name: config.ui.pane_frames.hide_session_name,
+        },
+        keybinds: config.keybinds.clone(),
+    };
+
+    let create_ipc_pipe = || -> std::path::PathBuf {
+        let mut sock_dir = ZELLIJ_SOCK_DIR.clone();
+        std::fs::create_dir_all(&sock_dir).unwrap();
+        set_permissions(&sock_dir, 0o700).unwrap();
+        sock_dir.push(envs::get_session_name().unwrap());
+        sock_dir
+    };
+
+    let (first_msg, ipc_pipe) = match info {
+        ClientInfo::New(name) | ClientInfo::Resurrect(name, _) => {
+            envs::set_session_name(name.clone());
+            os_input.update_session_name(name);
+            let ipc_pipe = create_ipc_pipe();
+
+            spawn_server(&*ipc_pipe, opts.debug).unwrap();
+
+            (
+                ClientToServerMsg::NewClient(
+                    client_attributes,
+                    Box::new(opts),
+                    Box::new(config_options.clone()),
+                    Box::new(layout.unwrap()),
+                    Box::new(config.plugins.clone()),
+                ),
+                ipc_pipe,
+            )
+        },
+        _ => {
+            eprintln!("Session already exists");
+            std::process::exit(1);
+        },
+    };
+
+    os_input.connect_to_server(&*ipc_pipe);
+    os_input.send_to_server(first_msg);
+}
+
 #[cfg(test)]
 #[path = "./unit/stdin_tests.rs"]
 mod stdin_tests;
diff --git a/zellij-client/src/os_input_output.rs b/zellij-client/src/os_input_output.rs
index 1bfd6666a..47dcafb09 100644
--- a/zellij-client/src/os_input_output.rs
+++ b/zellij-client/src/os_input_output.rs
@@ -317,8 +317,8 @@ impl Clone for Box<dyn ClientOsApi> {
 }
 
 pub fn get_client_os_input() -> Result<ClientOsInputOutput, nix::Error> {
-    let current_termios = termios::tcgetattr(0)?;
-    let orig_termios = Some(Arc::new(Mutex::new(current_termios)));
+    let current_termios = termios::tcgetattr(0).ok();
+    let orig_termios = current_termios.map(|termios| Arc::new(Mutex::new(termios)));
     let reading_from_stdin = Arc::new(Mutex::new(None));
     Ok(ClientOsInputOutput {
         orig_termios,
diff --git a/zellij-server/src/os_input_output.rs b/zellij-server/src/os_input_output.rs
index a2d9e36a8..640b6fbc9 100644
--- a/zellij-server/src/os_input_output.rs
+++ b/zellij-server/src/os_input_output.rs
@@ -221,7 +221,7 @@ fn handle_openpty(
 fn handle_terminal(
     cmd: RunCommand,
     failover_cmd: Option<RunCommand>,
-    orig_termios: termios::Termios,
+    orig_termios: Option<termios::Termios>,
     quit_cb: Box<dyn Fn(PaneId, Option<i32>, RunCommand) + Send>,
     terminal_id: u32,
 ) -> Result<(RawFd, RawFd)> {
@@ -229,7 +229,7 @@ fn handle_terminal(
 
     // Create a pipe to allow the child the communicate the shell's pid to its
     // parent.
-    match openpty(None, Some(&orig_termios)) {
+    match openpty(None, &orig_termios) {
         Ok(open_pty_res) => handle_openpty(open_pty_res, cmd, quit_cb, terminal_id),
         Err(e) => match failover_cmd {
             Some(failover_cmd) => {
@@ -279,7 +279,7 @@ fn separate_command_arguments(command: &mut PathBuf, args: &mut Vec<String>) {
 /// set.
 fn spawn_terminal(
     terminal_action: TerminalAction,
-    orig_termios: termios::Termios,
+    orig_termios: Option<termios::Termios>,
     quit_cb: Box<dyn Fn(PaneId, Option<i32>, RunCommand) + Send>, // u32 is the exit_status
     default_editor: Option<PathBuf>,
     terminal_id: u32,
@@ -418,7 +418,7 @@ impl ClientSender {
 
 #[derive(Clone)]
 pub struct ServerOsInputOutput {
-    orig_termios: Arc<Mutex<termios::Termios>>,
+    orig_termios: Arc<Mutex<Option<termios::Termios>>>,
     client_senders: Arc<Mutex<HashMap<ClientId, ClientSender>>>,
     terminal_id_to_raw_fd: Arc<Mutex<BTreeMap<u32, Option<RawFd>>>>, // A value of None means the
     // terminal_id exists but is
@@ -876,7 +876,10 @@ impl Clone for Box<dyn ServerOsApi> {
 }
 
 pub fn get_server_os_input() -> Result<ServerOsInputOutput, nix::Error> {
-    let current_termios = termios::tcgetattr(0)?;
+    let current_termios = termios::tcgetattr(0).ok();
+    if current_termios.is_none() {
+        log::warn!("Starting a server without a controlling terminal, using the default termios configuration.");
+    }
     let orig_termios = Arc::new(Mutex::new(current_termios));
     Ok(ServerOsInputOutput {
         orig_termios,
diff --git a/zellij-server/src/unit/os_input_output_tests.rs b/zellij-server/src/unit/os_input_output_tests.rs
index 7e6510835..31892525d 100644
--- a/zellij-server/src/unit/os_input_output_tests.rs
+++ b/zellij-server/src/unit/os_input_output_tests.rs
@@ -36,7 +36,7 @@ fn get_cwd() {
         termios::tcgetattr(test_terminal.slave()).expect("Could not configure the termios");
 
     let server = ServerOsInputOutput {
-        orig_termios: Arc::new(Mutex::new(test_termios)),
+        orig_termios: Arc::new(Mutex::new(Some(test_termios))),
         client_senders: Arc::default(),
         terminal_id_to_raw_fd: Arc::default(),
         cached_resizes: Arc::default(),
diff --git a/zellij-utils/src/cli.rs b/zellij-utils/src/cli.rs
index 0388e5999..ba1898439 100644
--- a/zellij-utils/src/cli.rs
+++ b/zellij-utils/src/cli.rs
@@ -125,6 +125,10 @@ pub enum Sessions {
         #[clap(short, long, value_parser)]
         create: bool,
 
+        /// Create a detached session in the background if one does not exist
+        #[clap(short, long, value_parser)]
+        background: bool,
+
         /// Number of the session index in the active sessions ordered creation date.
         #[clap(long, value_parser)]
         index: Option<usize>,