Merge nucleic/brisk-yarn-dingo-50se into dev

brush-core/src/commands.rs

@@ -368,6 +368,7 @@ impl<'a, SE: extensions::ShellExtensions> SimpleCommand<'a, SE> {
             argv,
             cwd: self.shell.working_dir().to_path_buf(),
             redirects,
+            pipeline: self.params.nash_pipeline,
         };
         let token = match gate.on_exec(start_event) {
             crate::gate::Verdict::Allow(token) => token,
@@ -835,6 +836,11 @@ pub(crate) async fn invoke_command_in_subshell_and_get_output(
     // Get our own set of parameters we can customize and use.
     let mut params = params.clone();
     params.process_group_policy = ProcessGroupPolicy::SameProcessGroup;
+    // nash: a command substitution is an *argument* to the stage, not the stage itself, and it
+    // runs during expansion — i.e. before the stage's own command. Letting it inherit the slot
+    // made `grep "$(printf x)" f | wc -l` report `printf x` as the producing stage
+    // (docs/NASH.md §5.1).
+    params.nash_pipeline = None;
 
     // Set up pipe so we can read the output.
     let (reader, writer) = std::io::pipe()?;

brush-core/src/gate.rs

@@ -22,6 +22,24 @@ pub struct ExecStart {
     /// nash: the redirections applied to this command (docs/NASH.md §5.2). The
     /// observer reads back the affected byte range after the command completes.
     pub redirects: Vec<RedirectRecord>,
+    /// nash: the pipeline stage this command occupies, when it runs as part of
+    /// `a | b | c` (docs/NASH.md §5.1). `None` for a standalone command.
+    pub pipeline: Option<PipelineSlot>,
+}
+
+/// Where a command sits in the pipeline it belongs to (docs/NASH.md §5.1).
+///
+/// Shares its `id` with the [`PipeEvent`]s of the same pipeline, which is what
+/// lets an observer name the commands either side of a link (`curl … | sh`)
+/// instead of reporting bare stage indices.
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub struct PipelineSlot {
+    /// Correlates this stage with the pipeline's links; see [`PipeEvent::pipeline_id`].
+    pub id: u64,
+    /// Zero-based position of this stage within the pipeline.
+    pub index: usize,
+    /// Total number of stages in the pipeline.
+    pub len: usize,
 }
 
 /// How a redirection's data is captured after the command runs (docs/NASH.md §5.2).

brush-core/src/interp.rs

@@ -41,6 +41,12 @@ pub struct ExecutionParameters {
     // `gate::ExecStart` for post-run read-back (docs/NASH.md §5.2). Empty unless
     // observation is active and the command has redirects.
     pub(crate) nash_redirects: Vec<crate::gate::RedirectRecord>,
+    // nash: the pipeline stage the command being built belongs to, stamped onto
+    // its `gate::ExecStart` so the observer can name the stages either side of a
+    // pipe link (docs/NASH.md §5.1). Inherited by nested commands — a command
+    // inside a stage's subshell or brace group belongs to that same stage — and
+    // overwritten only when a nested pipeline starts its own.
+    pub(crate) nash_pipeline: Option<crate::gate::PipelineSlot>,
 }
 
 impl ExecutionParameters {
@@ -488,19 +494,23 @@ async fn spawn_pipeline_processes(
     let mut spawn_results = VecDeque::new();
     let mut process_group_id: Option<i32> = None;
 
-    // Create pipes to use between commands, but only bother doing so if there's more than one
-    // command.
-    if pipeline_len > 1 {
-        // nash: when observation is active, interpose a tee on each link so the
-        // bytes flowing `a | b` are captured (docs/NASH.md §5.3). Off otherwise —
-        // no extra pipe/thread on the unobserved fast path.
-        let nash_pipeline_id = if crate::gate::is_active() {
+    // nash: when observation is active, one id per multi-stage pipeline correlates
+    // both its tapped links and the exec events of the stages either side of them
+    // (docs/NASH.md §5.3). `None` on the unobserved fast path and for a lone
+    // command, where there is no link to tap and nothing to correlate.
+    let nash_pipeline_id = if pipeline_len > 1 && crate::gate::is_active() {
         Some(crate::gate::next_pipeline_id())
     } else {
         None
     };
+
+    // Create pipes to use between commands, but only bother doing so if there's more than one
+    // command.
+    if pipeline_len > 1 {
         for link in 0..(pipeline_len - 1) {
             if let Some(pipeline_id) = nash_pipeline_id {
+                // nash: interpose a tee on the link so the bytes flowing `a | b` are
+                // captured (docs/NASH.md §5.3).
                 // Producer writes `a_write`; a copier moves bytes to `b_write`;
                 // consumer reads `b_read`. Slots stay identical to the untapped
                 // case, so the pop-ordering below is unchanged.
@@ -539,6 +549,17 @@ async fn spawn_pipeline_processes(
         // Set up parameters appropriate for this command.
         let mut cmd_params = params.clone();
 
+        // nash: stamp this stage's slot so its exec event can be joined to the links
+        // either side of it. Only when this pipeline is itself tapped — a lone command
+        // must keep any slot inherited from the stage that contains it.
+        if let Some(id) = nash_pipeline_id {
+            cmd_params.nash_pipeline = Some(crate::gate::PipelineSlot {
+                id,
+                index: current_pipeline_index,
+                len: pipeline_len,
+            });
+        }
+
         // Install pipes.
         if let Some(Some(reader)) = pipe_readers.pop() {
             cmd_params.open_files.set_fd(OpenFiles::STDIN_FD, reader);