Merge nucleic/sleek-thistle-egret-fyej into dev

NUCLEIC_FORK.md

@@ -18,6 +18,10 @@ Every fork change is marked with a `// nash:` comment. Current patches:
 | `brush-core/src/commands.rs` | `SimpleCommand::execute` split into gate wrapper + `execute_inner`: `on_exec` before dispatch (Deny short-circuits), completion correlated through all three spawn-result variants |
 | `brush-core/src/processes.rs` | `ChildProcess.gate_token` + `on_exit` reporting from `wait()`/`poll()` (128+signal for signal deaths) |
 | `brush-shell/src/entry.rs` | `set_exit_hook` seam so nash can flush its event buffer before `process::exit` |
+| `brush-core/src/gate.rs` | M2 (docs/NASH.md §5.2–5.3): `RedirectRecord`/`RedirectReadback` + `ExecStart.redirects` + `Gate::on_cmdsub` default hook |
+| `brush-core/src/interp.rs` | `ExecutionParameters.nash_redirects` accumulator; `setup_redirect` records file (`>`,`>>`,`<`,`2>`,`&>`,`<>`), heredoc, and here-string redirects |
+| `brush-core/src/commands.rs` | gate wrapper drains `nash_redirects` into `ExecStart` for post-run read-back |
+| `brush-core/src/expansion.rs` | command-substitution arm calls `gate().on_cmdsub` with the trimmed output |
 
 Verification (this container): brush compat suite `2067 ran: 1684 succeeded, 6
 failed, 377 known to fail, 38 skipped` — the 6 failures are identical to a
@@ -26,8 +30,11 @@ pristine `brush-shell-v0.4.0` baseline run (environmental: ANSI-C quote and
 zero fork-caused regressions; +3 successes vs baseline are the repaired IFS
 tests. nash corpus: 94/94.
 
-Planned (M2, per docs/NASH.md §5.2–5.3): redirect/pipe tap hooks on the `Gate`
+Planned (M2 remainder, per docs/NASH.md §5.3): inline tees on the pipe wiring
-trait (`on_redirect`/`on_pipe`) in `interp.rs`/`openfiles.rs`.
+in `interp.rs::spawn_pipeline_processes` (the `std::io::pipe()` links between
+`a | b` stages) — the one data-flow channel not yet tapped. Deferred as the most
+invasive change (async copier + backpressure + SIGPIPE); regular-file
+redirections, heredoc/here-string, and command substitution are all captured.
 
 Updating: diff against the upstream tag, re-vendor, re-apply `// nash:` patches
 (grep for the marker), then re-run `shell/corpus/replay.py` and the brush compat

brush-core/src/commands.rs

@@ -353,7 +353,7 @@ impl<'a, SE: extensions::ShellExtensions> SimpleCommand<'a, SE> {
     /// command passes through the process-global [`crate::gate::Gate`] before
     /// dispatch; completion is reported back with the issued token, however the
     /// command runs (inline, spawned process, or spawned task).
-    pub async fn execute(self) -> Result<ExecutionSpawnResult, error::Error> {
+    pub async fn execute(mut self) -> Result<ExecutionSpawnResult, error::Error> {
         use std::io::Write;
 
         let gate = crate::gate::gate();
@@ -362,9 +362,12 @@ impl<'a, SE: extensions::ShellExtensions> SimpleCommand<'a, SE> {
         if argv.is_empty() {
             argv.push(self.command_name.clone());
         }
+        // nash: hand this command's redirects to the observer for post-run read-back.
+        let redirects = std::mem::take(&mut self.params.nash_redirects);
         let start_event = crate::gate::ExecStart {
             argv,
             cwd: self.shell.working_dir().to_path_buf(),
+            redirects,
         };
         let token = match gate.on_exec(start_event) {
             crate::gate::Verdict::Allow(token) => token,

brush-core/src/expansion.rs

@@ -999,6 +999,12 @@ impl<'a, SE: extensions::ShellExtensions> WordExpander<'a, SE> {
                 let trimmed_len = cmd_output.trim_end_matches('\n').len();
                 cmd_output.truncate(trimmed_len);
 
+                // nash: capture command-substitution output (docs/NASH.md §5.3) —
+                // invisible to the transcript, often carries decisions/secrets.
+                if !self.disable_command_substitutions {
+                    crate::gate::gate().on_cmdsub(cmd_output.as_str());
+                }
+
                 Expansion::from(ExpansionPiece::Splittable(cmd_output))
             }
             brush_parser::word::WordPiece::EscapeSequence(s) => {

brush-core/src/gate.rs

@@ -18,6 +18,41 @@ pub struct ExecStart {
     pub argv: Vec<String>,
     /// The shell's working directory at execution time.
     pub cwd: PathBuf,
+    /// 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>,
+}
+
+/// How a redirection's data is captured after the command runs (docs/NASH.md §5.2).
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub enum RedirectReadback {
+    /// A truncating write (`>`, `>|`, `&>`): read the head of the final file.
+    Truncate,
+    /// An append (`>>`): read the bytes added after `size_before`.
+    Append,
+    /// An input (`<`): read the head of the source file.
+    Input,
+    /// Inline data known at setup (heredoc / here-string): no file read-back.
+    Inline,
+}
+
+/// One redirection observed on a command. For regular files nash hands the child
+/// the *real* fd (semantics untouched) and reads back a bounded range afterward;
+/// for heredoc/here-string the body is captured inline at setup.
+#[derive(Clone, Debug)]
+pub struct RedirectRecord {
+    /// The operator as written (`>`, `>>`, `<`, `2>`, `&>`, `<<`, `<<<`).
+    pub op: String,
+    /// The affected file descriptor number.
+    pub fd: u32,
+    /// The regular-file target, if any (`None` for heredoc/here-string).
+    pub path: Option<PathBuf>,
+    /// How to read the data back.
+    pub readback: RedirectReadback,
+    /// The file's size at setup time (for append ranges); 0 otherwise.
+    pub size_before: u64,
+    /// Inline body for heredoc/here-string (already known at setup).
+    pub inline: Option<String>,
 }
 
 /// Details about a completed simple command.
@@ -49,6 +84,9 @@ pub trait Gate: Send + Sync {
     /// Called when a simple command completes, with the token issued by
     /// `on_exec`.
     fn on_exit(&self, token: u64, ev: ExecEnd);
+    /// nash: called with the (trimmed) output of a command substitution
+    /// `$(…)` / backticks (docs/NASH.md §5.3). Default no-op.
+    fn on_cmdsub(&self, _output: &str) {}
 }
 
 struct AllowAll;

brush-core/src/interp.rs

@@ -37,6 +37,10 @@ pub struct ExecutionParameters {
     /// Whether `errexit` (exit on error) behavior should be
     /// suppressed in this execution context. Defaults to `false`.
     pub suppress_errexit: bool,
+    // nash: redirections applied to the command being built, drained into its
+    // `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>,
 }
 
 impl ExecutionParameters {
@@ -1641,6 +1645,22 @@ pub(crate) async fn setup_redirect(
             }
 
             let expanded_file_path = expanded_fields.remove(0);
+            // nash: `&>` / `&>>` writes stdout+stderr to one file — record fd 1
+            // for read-back (docs/NASH.md §5.2).
+            let abs = shell.absolute_path(Path::new(expanded_file_path.as_str()));
+            let size_before = std::fs::metadata(&abs).map(|m| m.len()).unwrap_or(0);
+            params.nash_redirects.push(crate::gate::RedirectRecord {
+                op: if *append { "&>>".to_string() } else { "&>".to_string() },
+                fd: 1,
+                path: Some(abs),
+                readback: if *append {
+                    crate::gate::RedirectReadback::Append
+                } else {
+                    crate::gate::RedirectReadback::Truncate
+                },
+                size_before,
+                inline: None,
+            });
             setup_redirect_output_and_error_to(shell, params, &expanded_file_path, *append)?;
         }
 
@@ -1717,6 +1737,10 @@ pub(crate) async fn setup_redirect(
                             )
                         })?;
 
+                    // nash: record the redirect so the observer can read back the
+                    // affected byte range after the command runs (docs/NASH.md §5.2).
+                    nash_record_file_redirect(params, fd_num, kind, &expanded_file_path);
+
                     params.open_files.set_fd(fd_num, opened_file);
                 }
 
@@ -1839,6 +1863,9 @@ pub(crate) async fn setup_redirect(
 
             let f = setup_open_file_with_contents(io_here_doc.as_str())?;
 
+            // nash: heredoc body is known at setup — capture inline (docs/NASH.md §5.2b).
+            nash_record_inline_redirect(params, fd_num, "<<", &io_here_doc);
+
             params.open_files.set_fd(fd_num, f);
         }
 
@@ -1851,6 +1878,9 @@ pub(crate) async fn setup_redirect(
 
             let f = setup_open_file_with_contents(expanded_word.as_str())?;
 
+            // nash: here-string body is known at setup — capture inline.
+            nash_record_inline_redirect(params, fd_num, "<<<", &expanded_word);
+
             params.open_files.set_fd(fd_num, f);
         }
     }
@@ -1858,6 +1888,52 @@ pub(crate) async fn setup_redirect(
     Ok(())
 }
 
+// nash: record a regular-file redirect for post-run read-back (docs/NASH.md §5.2a).
+// The child still gets the real fd; this only notes what to read back afterward.
+fn nash_record_file_redirect(
+    params: &mut ExecutionParameters,
+    fd: ShellFd,
+    kind: &ast::IoFileRedirectKind,
+    path: &Path,
+) {
+    use crate::gate::RedirectReadback;
+    let (op, readback) = match kind {
+        ast::IoFileRedirectKind::Read | ast::IoFileRedirectKind::DuplicateInput => ("<", RedirectReadback::Input),
+        ast::IoFileRedirectKind::Write | ast::IoFileRedirectKind::DuplicateOutput => (">", RedirectReadback::Truncate),
+        ast::IoFileRedirectKind::Clobber => (">|", RedirectReadback::Truncate),
+        ast::IoFileRedirectKind::Append => (">>", RedirectReadback::Append),
+        ast::IoFileRedirectKind::ReadAndWrite => ("<>", RedirectReadback::Truncate),
+    };
+    // Size at setup: append ranges start here; only regular files are read back.
+    let size_before = std::fs::metadata(path).map(|m| m.len()).unwrap_or(0);
+    let op = if fd == 2 && op == ">" { "2>".to_string() } else { op.to_string() };
+    params.nash_redirects.push(crate::gate::RedirectRecord {
+        op,
+        fd: u32::try_from(fd).unwrap_or(0),
+        path: Some(path.to_path_buf()),
+        readback,
+        size_before,
+        inline: None,
+    });
+}
+
+// nash: record an inline (heredoc / here-string) redirect — body known at setup.
+fn nash_record_inline_redirect(
+    params: &mut ExecutionParameters,
+    fd: ShellFd,
+    op: &str,
+    body: &str,
+) {
+    params.nash_redirects.push(crate::gate::RedirectRecord {
+        op: op.to_string(),
+        fd: u32::try_from(fd).unwrap_or(0),
+        path: None,
+        readback: crate::gate::RedirectReadback::Inline,
+        size_before: 0,
+        inline: Some(body.to_string()),
+    });
+}
+
 /// Sets up redirection of both stdout and stderr to the same file, given by `file_path`.
 ///
 /// # Arguments