From 8933bf5f77417d557ad6e5b8d0caaccf29fcbc46 Mon Sep 17 00:00:00 2001
From: Patrick Ferris <patrick@sirref.org>
Date: Sun, 1 Feb 2026 00:40:55 +0100
Subject: [PATCH] Built-in redirection

---
 src/lib/eunix.ml |  2 +-
 src/lib/eval.ml  | 10 ++++++++--
 test/simple.t    |  2 +-
 3 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/src/lib/eunix.ml b/src/lib/eunix.ml
index 99cf020..4afc2a0 100644
--- a/src/lib/eunix.ml
+++ b/src/lib/eunix.ml
@@ -48,7 +48,7 @@ let with_redirections (rdrs : Types.redirect list) fn =
     (function
       | Types.Redirect (i, fd, _) ->
           Eio_unix.Fd.use_exn "with_redirections" fd @@ fun fd ->
-          Unix.dup2 fd (fd_of_int i)
+          if (Obj.magic fd : int) <> i then Unix.dup2 fd (fd_of_int i)
       | Types.Close fd -> Eio_unix.Fd.close fd)
     rdrs;
   Fun.protect
diff --git a/src/lib/eval.ml b/src/lib/eval.ml
index b83d029..c2c4c7c 100644
--- a/src/lib/eval.ml
+++ b/src/lib/eval.ml
@@ -428,6 +428,9 @@ module Make (S : Types.State) (E : Types.Exec) = struct
                               let ctx =
                                 handle_built_in ~rdrs ~stdout:some_write ctx bi
                               in
+                              let ctx =
+                                ctx >|= fun ctx -> clear_local_state ctx
+                              in
                               close_stdout ~is_global some_write;
                               let built_in = ctx >|= fun _ -> () in
                               let job = handle_job job (`Built_in built_in) in
@@ -479,6 +482,7 @@ module Make (S : Types.State) (E : Types.Exec) = struct
                                       loop ctx job some_read rest)))))
               | Some (Ok bi) ->
                   let ctx = handle_built_in ~rdrs ~stdout:some_write ctx bi in
+                  let ctx = ctx >|= fun ctx -> clear_local_state ctx in
                   close_stdout ~is_global some_write;
                   let built_in = ctx >|= fun _ -> () in
                   let job = handle_job job (`Built_in built_in) in
@@ -989,7 +993,10 @@ module Make (S : Types.State) (E : Types.Exec) = struct
       (ctx, []) swc
 
   and handle_built_in ~rdrs ~(stdout : Eio_unix.sink_ty Eio.Flow.sink)
-      (ctx : ctx) = function
+      (ctx : ctx) v =
+    let rdrs = ctx.rdrs @ rdrs in
+    Eunix.with_redirections rdrs @@ fun () ->
+    match v with
     | Built_ins.Cd { path } ->
         let cwd = S.cwd ctx.state in
         let+ state =
@@ -1009,7 +1016,6 @@ module Make (S : Types.State) (E : Types.Exec) = struct
         { ctx with state }
     | Pwd ->
         let () =
-          Eunix.with_redirections rdrs @@ fun () ->
           Eio.Flow.copy_string
             (Fmt.str "%a\n%!" Fpath.pp (S.cwd ctx.state))
             stdout
diff --git a/test/simple.t b/test/simple.t
index f4635e6..39e7e4c 100644
--- a/test/simple.t
+++ b/test/simple.t
@@ -179,7 +179,7 @@ Simple appending example
 
 Redirection of fds
 
-  $ msh -c "echo hello 3>out.txt >&3"
+  $ msh -c "echo hello 789>out.txt >&789"
   $ cat out.txt
   hello
 
-- 
2.51.2