refactor: remove [Stdune.Io]

Signed-off-by: Rudi Grinberg <me@rgrinberg.com>

<!-- ps-id: b6e8b645-d9e0-4e56-bd51-78e6a26e8488 -->

Signed-off-by: Rudi Grinberg <me@rgrinberg.com>

Author: rgrinberg

ocaml-lsp-server/src/dune.ml

@@ -112,10 +112,7 @@ module Poll =
         | s -> Ok (`Mtime s.st_mtime)
       ;;
 
-      let read_file s =
-        Fiber.of_thunk (fun () ->
-          Fiber.return (Result.try_with (fun () -> Io.String_path.read_file s)))
-      ;;
+      let read_file s = Fiber.of_thunk (fun () -> Fiber.return (Io.read_file s))
     end)
 
 type config =

ocaml-lsp-server/src/import.ml

@@ -10,7 +10,6 @@ include struct
   module Table = Table
   module Tuple = Tuple
   module Unix_env = Env
-  module Io = Io
   module Map = Map
   module Monoid = Monoid
   module Pid = Pid
@@ -19,6 +18,31 @@ include struct
   let sprintf = sprintf
 end
 
+module Io = struct
+  open Base
+
+  let read_file f =
+    Base.Result.try_with (fun () ->
+      let fd = Unix.openfile f [ O_CLOEXEC; O_RDONLY ] 0 in
+      Exn.protect
+        ~finally:(fun () -> Unix.close fd)
+        ~f:(fun () ->
+          match Unix.fstat fd with
+          | { Unix.st_size; _ } ->
+            let buf = Bytes.create st_size in
+            let rec loop pos remains =
+              if remains > 0
+              then (
+                let read = Unix.read fd buf pos remains in
+                if read = 0
+                then failwith (sprintf "unable to read all of %s" f)
+                else loop (pos + read) (remains - read))
+            in
+            loop 0 st_size;
+            Stdlib.Bytes.unsafe_to_string buf))
+  ;;
+end
+
 include struct
   open Base
   module Queue = Queue

ocaml-lsp-server/src/inference.ml

@@ -79,12 +79,12 @@ let language_id_of_fname s =
 let open_document_from_file (state : State.t) uri =
   let filename = Uri.to_path uri in
   Fiber.of_thunk (fun () ->
-    match Io.String_path.read_file filename with
-    | exception Sys_error _ ->
+    match Io.read_file filename with
+    | Error _ ->
       Log.log ~section:"debug" (fun () ->
         Log.msg "Unable to open file" [ "filename", `String filename ]);
       Fiber.return None
-    | text ->
+    | Ok text ->
       let languageId = language_id_of_fname filename in
       let text_document = TextDocumentItem.create ~uri ~languageId ~version:0 ~text in
       let params = DidOpenTextDocumentParams.create ~textDocument:text_document in