From 9f83a87b68ca066f32c1bcd1688db3a5640ba64c Mon Sep 17 00:00:00 2001
From: Patrick Ferris <patrick@sirref.org>
Date: Wed, 20 Nov 2024 19:54:49 +0000
Subject: [PATCH 1/8] Support chown in Eio_posix

Adds support for fchownat to eio.unix and then calls this from
eio_posix.
---
 lib_eio/fs.ml               |  1 +
 lib_eio/path.ml             |  8 ++++++
 lib_eio/path.mli            |  3 ++
 lib_eio/unix/eio_unix.mli   |  3 ++
 lib_eio/unix/primitives.h   |  1 +
 lib_eio/unix/private.ml     | 10 +++++++
 lib_eio/unix/stubs.c        | 21 ++++++++++++++
 lib_eio_posix/fs.ml         |  3 ++
 lib_eio_posix/low_level.ml  |  7 +++++
 lib_eio_posix/low_level.mli |  4 +++
 tests/fs.md                 | 56 +++++++++++++++++++++++++++++++++++++
 11 files changed, 117 insertions(+)

diff --git a/lib_eio/fs.ml b/lib_eio/fs.ml
index 34505c9f1..47196239c 100644
--- a/lib_eio/fs.ml
+++ b/lib_eio/fs.ml
@@ -71,6 +71,7 @@ module Pi = struct
     val rename : t -> path -> _ dir -> path -> unit
     val read_link : t -> path -> string
     val symlink : link_to:path -> t -> path -> unit
+    val chown : follow:bool -> uid:int64 -> gid:int64 -> t -> path -> unit
     val pp : t Fmt.t
     val native : t -> string -> string option
   end
diff --git a/lib_eio/path.ml b/lib_eio/path.ml
index 37cd5ff09..f59961e09 100644
--- a/lib_eio/path.ml
+++ b/lib_eio/path.ml
@@ -238,3 +238,11 @@ let read_link t =
   with Exn.Io _ as ex ->
     let bt = Printexc.get_raw_backtrace () in
     Exn.reraise_with_context ex bt "reading target of symlink %a" pp t
+
+let chown ~follow ~uid ~gid t =
+  let (Resource.T (dir, ops), path) = t in
+  let module X = (val (Resource.get ops Fs.Pi.Dir)) in
+  try X.chown ~follow ~uid ~gid dir path
+  with Exn.Io _ as ex ->
+    let bt = Printexc.get_raw_backtrace () in
+    Exn.reraise_with_context ex bt "chowing file %a" pp t
diff --git a/lib_eio/path.mli b/lib_eio/path.mli
index d147f5454..8e5473b6f 100644
--- a/lib_eio/path.mli
+++ b/lib_eio/path.mli
@@ -217,3 +217,6 @@ val symlink : link_to:string -> _ t -> unit
     {[
       Eio.Path.symlink (dir / "current") ~link_to:"version-1.0"
     ]} *)
+
+val chown : follow:bool -> uid:int64 -> gid:int64 -> _ t -> unit
+(** [chown ~follow ~uid ~gid t] changes the ownership of [t] to be [uid, gid]. *)
diff --git a/lib_eio/unix/eio_unix.mli b/lib_eio/unix/eio_unix.mli
index 774ba5f6b..af3315ebb 100644
--- a/lib_eio/unix/eio_unix.mli
+++ b/lib_eio/unix/eio_unix.mli
@@ -107,6 +107,9 @@ module Private : sig
 
   val read_link : Fd.t option -> string -> string
   val read_link_unix : Unix.file_descr option -> string -> string
+
+  val chown : flags:int -> uid:int64 -> gid:int64 -> Fd.t option -> string -> unit
+  val chown_unix : flags:int -> uid:int64 -> gid:int64 -> Unix.file_descr option -> string -> unit
 end
 
 module Pi = Pi
diff --git a/lib_eio/unix/primitives.h b/lib_eio/unix/primitives.h
index d43166a92..cd2b81296 100644
--- a/lib_eio/unix/primitives.h
+++ b/lib_eio/unix/primitives.h
@@ -9,4 +9,5 @@ CAMLprim value eio_unix_fork_fchdir(value);
 CAMLprim value eio_unix_fork_dups(value);
 CAMLprim value eio_unix_cap_enter(value);
 CAMLprim value eio_unix_readlinkat(value, value, value);
+CAMLprim value eio_unix_fchownat(value, value, value, value, value);
 CAMLprim value eio_unix_is_blocking(value);
diff --git a/lib_eio/unix/private.ml b/lib_eio/unix/private.ml
index 961990766..01d23b339 100644
--- a/lib_eio/unix/private.ml
+++ b/lib_eio/unix/private.ml
@@ -33,3 +33,13 @@ let read_link_unix fd path =
     aux 1024
 
 let read_link fd path = Fd.use_exn_opt "readlink" fd (fun fd -> read_link_unix fd path)
+
+external eio_fchownat : Unix.file_descr -> string -> int64 -> int64 -> int -> unit = "eio_unix_fchownat"
+
+let chown_unix ~flags ~uid ~gid fd path =
+  match fd with
+  | None -> Unix.chown path (Int64.to_int uid) (Int64.to_int gid)
+  | Some fd -> eio_fchownat fd path uid gid flags
+
+let chown ~flags ~uid ~gid fd path =
+  Fd.use_exn_opt "chown" fd (fun fd -> chown_unix ~uid ~gid ~flags fd path)
diff --git a/lib_eio/unix/stubs.c b/lib_eio/unix/stubs.c
index 78572bf4f..689254476 100644
--- a/lib_eio/unix/stubs.c
+++ b/lib_eio/unix/stubs.c
@@ -52,3 +52,24 @@ CAMLprim value eio_unix_readlinkat(value v_fd, value v_path, value v_cs) {
   CAMLreturn(Val_int(ret));
   #endif
 }
+
+CAMLprim value eio_unix_fchownat(value v_fd, value v_path, value v_uid, value v_gid, value v_flags) {
+#ifdef _WIN32
+  caml_unix_error(EOPNOTSUPP, "fchownat not supported on Windows", v_path);
+#else
+  CAMLparam3(v_path, v_uid, v_gid);
+  char *path;
+  int fd = Int_val(v_fd);
+  int ret;
+  caml_unix_check_path(v_path, "fchownat");
+  path = caml_stat_strdup(String_val(v_path));
+  caml_enter_blocking_section();
+  ret = fchownat(fd, path, Int64_val(v_uid), Int64_val(v_gid), Int_val(v_flags));
+  caml_leave_blocking_section();
+  caml_stat_free_preserving_errno(path);
+  if (ret == -1)
+    caml_uerror("fchownat", v_path);
+  CAMLreturn(Val_unit);
+#endif
+}
+
diff --git a/lib_eio_posix/fs.ml b/lib_eio_posix/fs.ml
index 1a20523a0..47e397c8b 100644
--- a/lib_eio_posix/fs.ml
+++ b/lib_eio_posix/fs.ml
@@ -97,6 +97,9 @@ end = struct
   let symlink ~link_to t path =
     Err.run (Low_level.symlink ~link_to t.fd) path
 
+  let chown ~follow ~uid ~gid t path =
+    Err.run (Low_level.chown ~follow ~uid ~gid t.fd) path
+
   let open_dir t ~sw path =
     let flags = Low_level.Open_flags.(rdonly + directory +? path) in
     let fd = Err.run (Low_level.openat ~sw ~mode:0 t.fd path) flags in
diff --git a/lib_eio_posix/low_level.ml b/lib_eio_posix/low_level.ml
index 6026993d1..61e03b894 100644
--- a/lib_eio_posix/low_level.ml
+++ b/lib_eio_posix/low_level.ml
@@ -428,6 +428,13 @@ let read_link dirfd path =
   Resolve.with_parent "read_link" dirfd path @@ fun dirfd path ->
   Eio_unix.Private.read_link_unix dirfd path
 
+let chown ~follow ~uid ~gid dirfd path =
+  let flags = if follow then 0 else Config.at_symlink_nofollow in
+  in_worker_thread "chown" @@ fun () ->
+  Resolve.with_parent "chown" dirfd path @@ fun dirfd path ->
+  let dirfd = Option.value dirfd ~default:at_fdcwd in
+  Eio_unix.Private.chown_unix ~flags ~uid ~gid (Some dirfd) path
+
 type stat
 external create_stat : unit -> stat = "caml_eio_posix_make_stat"
 external eio_fstatat : stat -> Unix.file_descr -> string -> int -> unit = "caml_eio_posix_fstatat"
diff --git a/lib_eio_posix/low_level.mli b/lib_eio_posix/low_level.mli
index 69efe7207..a89a318e9 100644
--- a/lib_eio_posix/low_level.mli
+++ b/lib_eio_posix/low_level.mli
@@ -82,6 +82,10 @@ val symlink : link_to:string -> dir_fd -> string -> unit
 (** [symlink ~link_to dir path] will create a new symlink at [dir / path]
     linking to [link_to]. *)
 
+val chown : follow:bool -> uid:int64 -> gid:int64 -> dir_fd -> string -> unit
+(** [chown ~follow ~uid ~gid dir path] will change the ownership of [dir / path]
+    to [uid, gid]. *)
+
 val readdir : dir_fd -> string -> string array
 
 val readv : fd -> Cstruct.t array -> int
diff --git a/tests/fs.md b/tests/fs.md
index 446874ad3..edf705870 100644
--- a/tests/fs.md
+++ b/tests/fs.md
@@ -94,6 +94,11 @@ let try_symlink ~link_to path =
   match Path.symlink ~link_to path with
   | s -> traceln "symlink %a -> %S" Path.pp path link_to
   | exception ex -> traceln "@[<h>%a@]" Eio.Exn.pp ex
+
+let try_chown ~follow ~uid ~gid path =
+  match Path.chown ~follow ~uid ~gid path with
+  | s -> traceln "chown %a" Path.pp path
+  | exception ex -> traceln "@[<h>%a@]" Eio.Exn.pp ex
 ```
 
 # Basic test cases
@@ -905,6 +910,57 @@ Reading at the end of a file:
 - : unit = ()
 ```
 
+# Changing Ownership
+
+<!-- This test is written a little obscurely as we only want to
+     run it on macOS, but MDX only supports os_type (Unix, Win, Cygwin) -->
+```ocaml
+# run @@ fun env ->
+  let cwd = Eio.Stdenv.cwd env in
+  let everyone = try Some (Unix.getgrnam "everyone") with Not_found -> None in
+  let stat_uid_gid path =
+    let stat = Eio.Path.stat ~follow:false path in
+    stat.Eio.File.Stat.uid, stat.gid
+  in
+  match everyone with
+    | None -> ()
+    | Some entry ->
+      let everybody = Int64.of_int entry.gr_gid in
+
+      let path = cwd / "owner.txt" in
+      let link = cwd / "link.txt" in
+      let symlink = cwd / "symlink.txt" in
+
+      (* Normal chown to everyone group *)
+      Path.with_open_out path ~create:(`Or_truncate 0o644) ignore;
+      let uid_before, _gid_before = stat_uid_gid path in
+      Eio.Path.chown ~follow:false ~uid:uid_before ~gid:everybody path;
+      let uid_after, gid_after = stat_uid_gid path in
+      assert (uid_before = uid_after);
+      assert (everybody = gid_after);
+
+      (* Chowning through a symlink *)
+      Path.with_open_out link ~create:(`Or_truncate 0o644) ignore;
+      Eio.Path.symlink ~link_to:"link.txt" symlink;
+      let luid1, lgid1 = stat_uid_gid link in
+      let suid1, sgid1 = stat_uid_gid symlink in
+
+      (* Only chown the symlink, not the target *)
+      Eio.Path.chown ~follow:false ~uid:uid_before ~gid:everybody symlink;
+      let luid2, lgid2 = stat_uid_gid link in
+      let suid2, sgid2 = stat_uid_gid symlink in
+      assert (luid1 = luid2 && lgid1 = lgid2 && suid1 = suid2 && Int64.to_int sgid2 = entry.gr_gid);
+
+      (* Now chown the target too *)
+      Eio.Path.chown ~follow:true ~uid:uid_before ~gid:everybody symlink;
+      let luid3, lgid3 = stat_uid_gid link in
+      let suid3, sgid3 = stat_uid_gid symlink in
+      assert (suid3 = luid3);
+      assert (Int64.to_int lgid3 = entry.gr_gid);
+      assert (Int64.to_int sgid3 = entry.gr_gid);;
+- : unit = ()
+```
+
 # Cancelling while readable
 
 Ensure reads can be cancelled promptly, even if there is no need to wait:

From 2c64c019c1eb74159b6206f7a4ba26b41c6b917b Mon Sep 17 00:00:00 2001
From: Patrick Ferris <patrick@sirref.org>
Date: Wed, 20 Nov 2024 20:09:27 +0000
Subject: [PATCH 2/8] Support chown in Eio_linux

---
 lib_eio_linux/eio_linux.ml  | 3 +++
 lib_eio_linux/low_level.ml  | 9 +++++++++
 lib_eio_linux/low_level.mli | 6 ++++++
 3 files changed, 18 insertions(+)

diff --git a/lib_eio_linux/eio_linux.ml b/lib_eio_linux/eio_linux.ml
index ec9c8eb07..da9db4a42 100644
--- a/lib_eio_linux/eio_linux.ml
+++ b/lib_eio_linux/eio_linux.ml
@@ -400,6 +400,9 @@ end = struct
 
   let read_link t path = Low_level.read_link t.fd path
 
+  let chown ~follow ~uid ~gid t path = 
+    Low_level.chown ~follow ~uid ~gid t.fd path
+
   let close t =
     match t.fd with
     | FD x -> Fd.close x
diff --git a/lib_eio_linux/low_level.ml b/lib_eio_linux/low_level.ml
index 42e72bfa3..94add8b51 100644
--- a/lib_eio_linux/low_level.ml
+++ b/lib_eio_linux/low_level.ml
@@ -524,6 +524,15 @@ let read_link fd path =
     Eio_unix.run_in_systhread ~label:"read_link" (fun () -> Eio_unix.Private.read_link (Some parent) leaf)
   with Unix.Unix_error (code, name, arg) -> raise @@ Err.wrap_fs code name arg
 
+let chown ~follow ~uid ~gid fd path =
+  let module At = Uring.Linkat_flags in
+  let follow = if follow then At.empty_path else At.(empty_path + symlink_follow) in
+  let flags = (follow :> int) in
+  try
+    with_parent_dir_fd fd path @@ fun parent leaf ->
+    Eio_unix.run_in_systhread ~label:"chown" (fun () -> Eio_unix.Private.chown ~flags ~uid ~gid (Some parent) leaf)
+  with Unix.Unix_error (code, name, arg) -> raise @@ Err.wrap_fs code name arg
+
 (* https://www.iana.org/assignments/protocol-numbers/protocol-numbers.xhtml *)
 let getaddrinfo ~service node =
   let to_eio_sockaddr_t {Unix.ai_family; ai_addr; ai_socktype; ai_protocol; _ } =
diff --git a/lib_eio_linux/low_level.mli b/lib_eio_linux/low_level.mli
index a3736e161..4de75685d 100644
--- a/lib_eio_linux/low_level.mli
+++ b/lib_eio_linux/low_level.mli
@@ -153,6 +153,12 @@ val rename : dir_fd -> string -> dir_fd -> string -> unit
 val symlink : link_to:string -> dir_fd -> string -> unit
 (** [symlink ~link_to dir path] creates a new symlink at [dir / path] pointing to [link_to]. *)
 
+val chown : follow:bool -> uid:int64 -> gid:int64 -> dir_fd -> string -> unit
+(** [chown ~follow ~uid ~gid dir path] changes the ownership of [dir / path] to [uid, gid].
+
+    If [follow = true] and [dir / path] is a symlink, then the ownership of the {e target} is
+    changed. If it is [false] then the ownership of the symlink itself is changed. *)
+
 val pipe : sw:Switch.t -> fd * fd
 (** [pipe ~sw] returns a pair [r, w] with the readable and writeable ends of a new pipe. *)
 

From 961f3770d0032ce649eadd1195fe667c8ba35db2 Mon Sep 17 00:00:00 2001
From: Patrick Ferris <patrick@sirref.org>
Date: Wed, 20 Nov 2024 20:32:20 +0000
Subject: [PATCH 3/8] Stub out chown on Eio_windows

---
 lib_eio_windows/fs.ml         | 4 ++++
 lib_eio_windows/low_level.ml  | 4 ++++
 lib_eio_windows/low_level.mli | 1 +
 3 files changed, 9 insertions(+)

diff --git a/lib_eio_windows/fs.ml b/lib_eio_windows/fs.ml
index d877b6fb5..939e4c256 100755
--- a/lib_eio_windows/fs.ml
+++ b/lib_eio_windows/fs.ml
@@ -164,6 +164,10 @@ end = struct
     with_parent_dir t path @@ fun dirfd path ->
     Err.run (Low_level.read_link ?dirfd) path
 
+  let chown ~follow ~uid ~gid t path =
+    with_parent_dir t path @@ fun dirfd path ->
+    Err.run (fun () -> Low_level.chown ?dirfd ~follow ~uid ~gid path) ()
+
   let rename t old_path new_dir new_path =
     match Handler.as_posix_dir new_dir with
     | None -> invalid_arg "Target is not an eio_windows directory!"
diff --git a/lib_eio_windows/low_level.ml b/lib_eio_windows/low_level.ml
index 85f25cd26..64ecbfbab 100755
--- a/lib_eio_windows/low_level.ml
+++ b/lib_eio_windows/low_level.ml
@@ -138,6 +138,10 @@ let read_link ?dirfd path =
   in_worker_thread @@ fun () ->
   Eio_unix.Private.read_link dirfd path
 
+let chown ?dirfd ~follow:_ ~uid ~gid path =
+  in_worker_thread @@ fun () ->
+  Eio_unix.Private.chown ~flags:0 ~uid ~gid dirfd path
+
 external eio_readv : Unix.file_descr -> Cstruct.t array -> int = "caml_eio_windows_readv"
 
 external eio_preadv : Unix.file_descr -> Cstruct.t array -> Optint.Int63.t -> int = "caml_eio_windows_preadv"
diff --git a/lib_eio_windows/low_level.mli b/lib_eio_windows/low_level.mli
index e2ec400bd..77b26d431 100755
--- a/lib_eio_windows/low_level.mli
+++ b/lib_eio_windows/low_level.mli
@@ -43,6 +43,7 @@ val lstat : string -> Unix.LargeFile.stats
 
 val realpath : string -> string
 val read_link : ?dirfd:fd -> string -> string
+val chown : ?dirfd:fd -> follow:bool -> uid:int64 -> gid:int64 -> string -> unit
 
 val mkdir : ?dirfd:fd -> ?nofollow:bool -> mode:int -> string -> unit
 val unlink : ?dirfd:fd -> dir:bool -> string -> unit

From 85ffd3d7b1a2cb368894f514eea93c1e40700ac3 Mon Sep 17 00:00:00 2001
From: Patrick Ferris <patrick@sirref.org>
Date: Wed, 20 Nov 2024 20:53:54 +0000
Subject: [PATCH 4/8] Make Eio_unix.Private.chown require a file descriptor

---
 lib_eio/unix/eio_unix.mli  | 4 ++--
 lib_eio/unix/private.ml    | 6 ++----
 lib_eio_linux/low_level.ml | 2 +-
 lib_eio_posix/low_level.ml | 2 +-
 4 files changed, 6 insertions(+), 8 deletions(-)

diff --git a/lib_eio/unix/eio_unix.mli b/lib_eio/unix/eio_unix.mli
index af3315ebb..5f05259b3 100644
--- a/lib_eio/unix/eio_unix.mli
+++ b/lib_eio/unix/eio_unix.mli
@@ -108,8 +108,8 @@ module Private : sig
   val read_link : Fd.t option -> string -> string
   val read_link_unix : Unix.file_descr option -> string -> string
 
-  val chown : flags:int -> uid:int64 -> gid:int64 -> Fd.t option -> string -> unit
-  val chown_unix : flags:int -> uid:int64 -> gid:int64 -> Unix.file_descr option -> string -> unit
+  val chown : flags:int -> uid:int64 -> gid:int64 -> Fd.t -> string -> unit
+  val chown_unix : flags:int -> uid:int64 -> gid:int64 -> Unix.file_descr -> string -> unit
 end
 
 module Pi = Pi
diff --git a/lib_eio/unix/private.ml b/lib_eio/unix/private.ml
index 01d23b339..afbad2869 100644
--- a/lib_eio/unix/private.ml
+++ b/lib_eio/unix/private.ml
@@ -37,9 +37,7 @@ let read_link fd path = Fd.use_exn_opt "readlink" fd (fun fd -> read_link_unix f
 external eio_fchownat : Unix.file_descr -> string -> int64 -> int64 -> int -> unit = "eio_unix_fchownat"
 
 let chown_unix ~flags ~uid ~gid fd path =
-  match fd with
-  | None -> Unix.chown path (Int64.to_int uid) (Int64.to_int gid)
-  | Some fd -> eio_fchownat fd path uid gid flags
+  eio_fchownat fd path uid gid flags
 
 let chown ~flags ~uid ~gid fd path =
-  Fd.use_exn_opt "chown" fd (fun fd -> chown_unix ~uid ~gid ~flags fd path)
+  Fd.use_exn "chown" fd (fun fd -> chown_unix ~uid ~gid ~flags fd path)
diff --git a/lib_eio_linux/low_level.ml b/lib_eio_linux/low_level.ml
index 94add8b51..1eec23ffb 100644
--- a/lib_eio_linux/low_level.ml
+++ b/lib_eio_linux/low_level.ml
@@ -530,7 +530,7 @@ let chown ~follow ~uid ~gid fd path =
   let flags = (follow :> int) in
   try
     with_parent_dir_fd fd path @@ fun parent leaf ->
-    Eio_unix.run_in_systhread ~label:"chown" (fun () -> Eio_unix.Private.chown ~flags ~uid ~gid (Some parent) leaf)
+    Eio_unix.run_in_systhread ~label:"chown" (fun () -> Eio_unix.Private.chown ~flags ~uid ~gid parent leaf)
   with Unix.Unix_error (code, name, arg) -> raise @@ Err.wrap_fs code name arg
 
 (* https://www.iana.org/assignments/protocol-numbers/protocol-numbers.xhtml *)
diff --git a/lib_eio_posix/low_level.ml b/lib_eio_posix/low_level.ml
index 61e03b894..066875544 100644
--- a/lib_eio_posix/low_level.ml
+++ b/lib_eio_posix/low_level.ml
@@ -433,7 +433,7 @@ let chown ~follow ~uid ~gid dirfd path =
   in_worker_thread "chown" @@ fun () ->
   Resolve.with_parent "chown" dirfd path @@ fun dirfd path ->
   let dirfd = Option.value dirfd ~default:at_fdcwd in
-  Eio_unix.Private.chown_unix ~flags ~uid ~gid (Some dirfd) path
+  Eio_unix.Private.chown_unix ~flags ~uid ~gid dirfd path
 
 type stat
 external create_stat : unit -> stat = "caml_eio_posix_make_stat"

From 9808d1310dd205baa69dccfae2f3e21585d1a8d7 Mon Sep 17 00:00:00 2001
From: Patrick Ferris <patrick@sirref.org>
Date: Wed, 20 Nov 2024 21:16:21 +0000
Subject: [PATCH 5/8] Fix eio_windows

---
 lib_eio_windows/low_level.ml | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/lib_eio_windows/low_level.ml b/lib_eio_windows/low_level.ml
index 64ecbfbab..eb925364e 100755
--- a/lib_eio_windows/low_level.ml
+++ b/lib_eio_windows/low_level.ml
@@ -140,7 +140,9 @@ let read_link ?dirfd path =
 
 let chown ?dirfd ~follow:_ ~uid ~gid path =
   in_worker_thread @@ fun () ->
-  Eio_unix.Private.chown ~flags:0 ~uid ~gid dirfd path
+  match dirfd with
+  | None -> failwith "Chown is unsupported on Windows"
+  | Some dirfd -> Eio_unix.Private.chown ~flags:0 ~uid ~gid dirfd path
 
 external eio_readv : Unix.file_descr -> Cstruct.t array -> int = "caml_eio_windows_readv"
 

From 4dd28632ee994b875900c8350996687cd08a8d02 Mon Sep 17 00:00:00 2001
From: Patrick Ferris <patrick@sirref.org>
Date: Fri, 22 Nov 2024 09:54:27 +0000
Subject: [PATCH 6/8] Better chown exception message

Co-authored-by: Thomas Leonard <talex5@gmail.com>
---
 lib_eio/path.ml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib_eio/path.ml b/lib_eio/path.ml
index f59961e09..6e57e8e93 100644
--- a/lib_eio/path.ml
+++ b/lib_eio/path.ml
@@ -245,4 +245,4 @@ let chown ~follow ~uid ~gid t =
   try X.chown ~follow ~uid ~gid dir path
   with Exn.Io _ as ex ->
     let bt = Printexc.get_raw_backtrace () in
-    Exn.reraise_with_context ex bt "chowing file %a" pp t
+    Exn.reraise_with_context ex bt "changing ownership of %a" pp t

From 510c2a693fb0479fdd5cacb9382521ccfb353442 Mon Sep 17 00:00:00 2001
From: Patrick Ferris <patrick@sirref.org>
Date: Fri, 22 Nov 2024 10:13:24 +0000
Subject: [PATCH 7/8] Fix eio_linux chown follow symlinks

---
 lib_eio_linux/low_level.ml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib_eio_linux/low_level.ml b/lib_eio_linux/low_level.ml
index 1eec23ffb..e4da16a4e 100644
--- a/lib_eio_linux/low_level.ml
+++ b/lib_eio_linux/low_level.ml
@@ -526,7 +526,7 @@ let read_link fd path =
 
 let chown ~follow ~uid ~gid fd path =
   let module At = Uring.Linkat_flags in
-  let follow = if follow then At.empty_path else At.(empty_path + symlink_follow) in
+  let follow = if follow then At.(empty_path + symlink_follow) else At.empty_path in
   let flags = (follow :> int) in
   try
     with_parent_dir_fd fd path @@ fun parent leaf ->

From 04364c5470366a12eead8f2f210b42eb908077b6 Mon Sep 17 00:00:00 2001
From: Patrick Ferris <patrick@sirref.org>
Date: Fri, 22 Nov 2024 10:15:15 +0000
Subject: [PATCH 8/8] Fix C stubs for chown

Don't call Int64_val inside a blocking section.
---
 lib_eio/unix/stubs.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/lib_eio/unix/stubs.c b/lib_eio/unix/stubs.c
index 689254476..b5788ac0e 100644
--- a/lib_eio/unix/stubs.c
+++ b/lib_eio/unix/stubs.c
@@ -60,11 +60,13 @@ CAMLprim value eio_unix_fchownat(value v_fd, value v_path, value v_uid, value v_
   CAMLparam3(v_path, v_uid, v_gid);
   char *path;
   int fd = Int_val(v_fd);
+  uid_t uid = Int64_val(v_uid);
+  gid_t gid = Int64_val(v_gid);
   int ret;
   caml_unix_check_path(v_path, "fchownat");
   path = caml_stat_strdup(String_val(v_path));
   caml_enter_blocking_section();
-  ret = fchownat(fd, path, Int64_val(v_uid), Int64_val(v_gid), Int_val(v_flags));
+  ret = fchownat(fd, path, uid, gid, Int_val(v_flags));
   caml_leave_blocking_section();
   caml_stat_free_preserving_errno(path);
   if (ret == -1)