Fork non-command nodes for background jobs, fix interactive flag in child processes, and add empty variable test for [ builtin

src/builtin/autocmd.rs

@@ -250,7 +250,7 @@ mod tests {
       "pre-mode-change", "post-mode-change",
       "on-history-open", "on-history-close", "on-history-select",
       "on-completion-start", "on-completion-cancel", "on-completion-select",
-      "on-exit",
+      "on-exit"
     ];
     for kind in kinds {
       test_input(format!("autocmd {kind} 'true'")).unwrap();

src/main.rs

@@ -130,6 +130,15 @@ fn main() -> ExitCode {
     return ExitCode::SUCCESS;
   }
 
+	// Increment SHLVL, or set to 1 if not present or invalid.
+	// This var represents how many nested shell instances we're in
+	if let Ok(var) = env::var("SHLVL")
+	&& let Ok(lvl) = var.parse::<u32>() {
+		unsafe { env::set_var("SHLVL", (lvl + 1).to_string()) };
+	} else {
+		unsafe { env::set_var("SHLVL", "1") };
+	}
+
   if let Err(e) = if let Some(path) = args.script {
     run_script(path, args.script_args)
   } else if let Some(cmd) = args.command {
@@ -240,7 +249,7 @@ fn shed_interactive(args: ShedArgs) -> ShResult<()> {
       // may have moved it during resize/rewrap
       readline.writer.update_t_cols();
       readline.mark_dirty();
-    }
+		}
 
     if JOB_DONE.swap(false, Ordering::SeqCst) {
       // update the prompt so any job count escape sequences update dynamically

src/parse/execute.rs

@@ -258,6 +258,9 @@ impl Dispatcher {
     Ok(())
   }
   pub fn dispatch_cmd(&mut self, node: Node) -> ShResult<()> {
+		let (line, _) = node.get_span().clone().line_and_col();
+		write_vars(|v| v.set_var("LINENO", VarKind::Str((line + 1).to_string()), VarFlags::NONE))?;
+
     let Some(cmd) = node.get_command() else {
       return self.exec_cmd(node); // Argv is empty, probably an assignment
     };
@@ -764,8 +767,16 @@ impl Dispatcher {
     self.job_stack.new_job();
     if cmds.len() == 1 {
       self.fg_job = !is_bg && self.interactive;
-      let cmd = cmds.into_iter().next().unwrap();
-      self.dispatch_node(cmd)?;
+      let mut cmd = cmds.into_iter().next().unwrap();
+      if is_bg && !matches!(cmd.class, NdRule::Command { .. }) {
+        self.run_fork(&cmd.get_command().map(|t| t.to_string()).unwrap_or_default(), |s| {
+          if let Err(e) = s.dispatch_node(cmd) {
+            e.print_error();
+          }
+        })?;
+      } else {
+        self.dispatch_node(cmd)?;
+      }
 
       // Give the pipeline terminal control as soon as the first child
       // establishes the PGID, so later children (e.g. nvim) don't get
@@ -1100,6 +1111,7 @@ impl Dispatcher {
     match unsafe { fork()? } {
       ForkResult::Child => {
         let _ = setpgid(Pid::from_raw(0), existing_pgid.unwrap_or(Pid::from_raw(0)));
+        self.interactive = false;
         f(self);
         exit(state::get_status())
       }
@@ -1398,4 +1410,15 @@ mod tests {
 		assert_eq!(state::get_status(), 0);
 		assert_eq!(g.read_output(), "yes\n");
 	}
+
+	#[test]
+	fn empty_var_in_test() {
+		let _g = TestGuard::new();
+		// POSIX specifies that a quoted unset variable expands to an empty string, so the shell actually sees `[ -n "" ]`, which returns false
+		test_input("[ -n \"$EMPTYVAR_PROBABLY_NOT_SET_TO_ANYTHING\" ]").unwrap();
+		assert_eq!(state::get_status(), 1);
+		// Without quotes, word splitting causes an empty var to be removed entirely, so the shell actually sees `[ -n ]`, testing the value of ']', which returns true
+		test_input("[ -n $EMPTYVAR_PROBABLY_NOT_SET_TO_ANYTHING ]").unwrap();
+		assert_eq!(state::get_status(), 0);
+	}
 }

src/readline/linebuf.rs

@@ -3489,6 +3489,9 @@ impl LineBuf {
 impl Display for LineBuf {
   fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
     let mut full_buf = self.buffer.clone();
+    if full_buf.is_empty() {
+      return write!(f, "{}", full_buf);
+    }
     if let Some((start, end)) = self.select_range() {
       let mode = self.select_mode.unwrap();
       let start_byte = self.read_idx_byte_pos(start);
@@ -3497,7 +3500,7 @@ impl Display for LineBuf {
       match mode.anchor() {
         SelectAnchor::Start => {
           let mut inclusive = start_byte..=end_byte;
-          if *inclusive.end() == full_buf.len() {
+          if *inclusive.end() >= full_buf.len() {
             inclusive = start_byte..=end_byte.saturating_sub(1);
           }
           let selected = format!(

src/readline/tests.rs

@@ -225,5 +225,6 @@ vi_test! {
 	vi_dollar_single     : "h"                  => "$"            => "h", 0;
 	vi_caret_no_ws       : "hello"              => "$^"           => "hello", 0;
 	vi_f_last_char       : "hello"              => "fo"           => "hello", 4;
-	vi_r_on_space        : "hello world"        => "5|r-"         => "hell- world", 4
+	vi_r_on_space        : "hello world"        => "5|r-"         => "hell- world", 4;
+	vi_vw_doesnt_crash   : ""        						=> "vw"           => "", 0
 }

src/state.rs

@@ -315,6 +315,34 @@ impl ScopeStack {
     };
     scope.set_var(var_name, val, flags)
   }
+	pub fn get_magic_var(&self, var_name: &str) -> Option<String> {
+		match var_name {
+			"SECONDS" => {
+				let shell_time = read_meta(|m| m.shell_time());
+				let secs = Instant::now().duration_since(shell_time).as_secs();
+				Some(secs.to_string())
+			}
+			"EPOCHREALTIME" => {
+				let epoch = std::time::SystemTime::now()
+					.duration_since(std::time::UNIX_EPOCH)
+					.unwrap_or(Duration::from_secs(0))
+					.as_secs_f64();
+				Some(epoch.to_string())
+			}
+			"EPOCHSECONDS" => {
+				let epoch = std::time::SystemTime::now()
+					.duration_since(std::time::UNIX_EPOCH)
+					.unwrap_or(Duration::from_secs(0))
+					.as_secs();
+				Some(epoch.to_string())
+			}
+			"RANDOM" => {
+				let random = rand::random_range(0..32768);
+				Some(random.to_string())
+			}
+			_ => None
+		}
+	}
   pub fn get_arr_elems(&self, var_name: &str) -> ShResult<Vec<String>> {
     for scope in self.scopes.iter().rev() {
       if scope.var_exists(var_name)
@@ -440,7 +468,9 @@ impl ScopeStack {
   pub fn try_get_var(&self, var_name: &str) -> Option<String> {
     // This version of get_var() is mainly used internally
     // so that we have access to Option methods
-    if let Ok(param) = var_name.parse::<ShellParam>() {
+		if let Some(magic) = self.get_magic_var(var_name) {
+			return Some(magic);
+		} else if let Ok(param) = var_name.parse::<ShellParam>() {
       let val = self.get_param(param);
       if !val.is_empty() {
         return Some(val);
@@ -463,6 +493,9 @@ impl ScopeStack {
     var
   }
   pub fn get_var(&self, var_name: &str) -> String {
+		if let Some(magic) = self.get_magic_var(var_name) {
+			return magic;
+		}
     if let Ok(param) = var_name.parse::<ShellParam>() {
       return self.get_param(param);
     }
@@ -1305,8 +1338,11 @@ impl VarTab {
 }
 
 /// A table of metadata for the shell
-#[derive(Clone, Default, Debug)]
+#[derive(Clone, Debug)]
 pub struct MetaTab {
+	// Time when the shell was started, used for calculating shell uptime
+	shell_time: Instant,
+
   // command running duration
   runtime_start: Option<Instant>,
   runtime_stop: Option<Instant>,
@@ -1331,6 +1367,25 @@ pub struct MetaTab {
   pending_widget_keys: Vec<KeyEvent>,
 }
 
+impl Default for MetaTab {
+	fn default() -> Self {
+		Self {
+			shell_time: Instant::now(),
+			runtime_start: None,
+			runtime_stop: None,
+			system_msg: vec![],
+			dir_stack: VecDeque::new(),
+			getopts_offset: 0,
+			old_path: None,
+			old_pwd: None,
+			path_cache: HashSet::new(),
+			cwd_cache: HashSet::new(),
+			comp_specs: HashMap::new(),
+			pending_widget_keys: vec![],
+		}
+	}
+}
+
 impl MetaTab {
   pub fn new() -> Self {
     Self {
@@ -1338,6 +1393,9 @@ impl MetaTab {
       ..Default::default()
     }
   }
+	pub fn shell_time(&self) -> Instant {
+		self.shell_time
+	}
   pub fn set_pending_widget_keys(&mut self, keys: &str) {
     let exp = expand_keymap(keys);
     self.pending_widget_keys = exp;