Add ?cloexec parameter to Lwt_io.pipe

CHANGES

@@ -1,5 +1,9 @@
 ===== dev =====
 
+====== Additions ======
+
+  * In the Lwt_io module, add `?cloexec:bool` optional arguments to functions that create file descriptors (`pipe`). The `?cloexec` argument is simply forwarded to the wrapped Lwt_unix function. (#872, #911, Antonin Décimo)
+
 ====== Fixes ======
 
   * Fix win32_spawn leaking dev_null fd in the parent process. (#906, Antonin Décimo)

src/unix/lwt_io.ml

@@ -1367,8 +1367,8 @@ let eprintl txt = write_line stderr txt
 let eprintf fmt = Printf.ksprintf eprint fmt
 let eprintlf fmt = Printf.ksprintf eprintl fmt
 
-let pipe ?in_buffer ?out_buffer _ =
-  let fd_r, fd_w = Lwt_unix.pipe () in
+let pipe ?cloexec ?in_buffer ?out_buffer _ =
+  let fd_r, fd_w = Lwt_unix.pipe ?cloexec () in
   (of_fd ?buffer:in_buffer ~mode:input fd_r,
    of_fd ?buffer:out_buffer ~mode:output fd_w)
 

src/unix/lwt_io.mli

@@ -86,9 +86,10 @@ val null : output_channel
 
 (** {2 Channels creation/manipulation} *)
 
-val pipe : ?in_buffer : Lwt_bytes.t -> ?out_buffer : Lwt_bytes.t -> unit ->
+val pipe : ?cloexec : bool ->
+  ?in_buffer : Lwt_bytes.t -> ?out_buffer : Lwt_bytes.t -> unit ->
   input_channel * output_channel
-  (** [pipe ?in_buffer ?out_buffer ()] creates a pipe using
+  (** [pipe ?cloexec ?in_buffer ?out_buffer ()] creates a pipe using
       {!Lwt_unix.pipe} and makes two channels from the two returned file
       descriptors *)