Add Eio_linux.Low_level.statx

Author: talex5

dune-project

@@ -42,7 +42,7 @@
   (logs (>= 0.7.0))
   (fmt (>= 0.8.9))
   (cmdliner (and (>= 1.1.0) :with-test))
-  (uring (>= 0.5))))
+  (uring (>= 0.7))))
 (package
  (name eio_posix)
  (allow_empty)  ; Work-around for dune bug #6938

eio_linux.opam

@@ -16,7 +16,7 @@ depends: [
   "logs" {>= "0.7.0"}
   "fmt" {>= "0.8.9"}
   "cmdliner" {>= "1.1.0" & with-test}
-  "uring" {>= "0.5"}
+  "uring" {>= "0.7"}
   "odoc" {with-doc}
 ]
 build: [

lib_eio_linux/eio_linux.mli

@@ -156,6 +156,12 @@ module Low_level : sig
   val fstat : fd -> Eio.File.Stat.t
   (** Like {!Unix.LargeFile.fstat}. *)
 
+  val statx : ?fd:fd -> mask:Uring.Statx.Mask.t -> string -> Uring.Statx.t -> Uring.Statx.Flags.t -> unit
+  (** [statx t ?fd ~mask path buf flags] stats [path], which is resolved relative to [fd]
+      (or the current directory if [fd] is not given).
+
+      The results are written to [buf]. *)
+
   val read_dir : fd -> string list
   (** [read_dir dir] reads all directory entries from [dir].
       The entries are not returned in any particular order

lib_eio_linux/low_level.ml

@@ -56,6 +56,15 @@ let rec enqueue_openat2 ((access, flags, perm, resolve, fd, path) as args) st ac
   if retry then (* wait until an sqe is available *)
     Queue.push (fun st -> enqueue_openat2 args st action) st.io_q
 
+let rec enqueue_statx ((fd, path, buf, flags, mask) as args) st action =
+  Ctf.label "statx";
+  let retry = Sched.with_cancel_hook ~action st (fun () ->
+      Uring.statx st.uring ?fd ~mask path buf flags (Job action)
+    )
+  in
+  if retry then (* wait until an sqe is available *)
+    Queue.push (fun st -> enqueue_statx args st action) st.io_q
+
 let rec enqueue_unlink ((dir, fd, path) as args) st action =
   Ctf.label "unlinkat";
   let retry = Sched.with_cancel_hook ~action st (fun () ->
@@ -360,6 +369,16 @@ let with_parent_dir op dir path fn =
       fn parent leaf
     )
 
+let statx ?fd ~mask path buf flags =
+  let res =
+    match fd with
+    | None -> Sched.enter (enqueue_statx (None, path, buf, flags, mask)) 
+    | Some fd ->
+      Fd.use_exn "statx" fd @@ fun fd ->
+      Sched.enter (enqueue_statx (Some fd, path, buf, flags, mask))
+  in
+  if res <> 0 then raise @@ Err.wrap_fs (Uring.error_of_errno res) "statx" path
+
 let mkdir_beneath ~perm dir path =
   (* [mkdir] is really an operation on [path]'s parent. Get a reference to that first: *)
   with_parent_dir "mkdir" dir path @@ fun parent leaf ->

lib_eio_linux/tests/test.ml

@@ -155,6 +155,47 @@ let test_expose_backend () =
   let backend = Eio.Stdenv.backend_id env in
   assert (backend = "linux")
 
+let kind_t = Alcotest.of_pp Uring.Statx.pp_kind
+
+let test_statx () =
+  let module X = Uring.Statx in
+  Eio_linux.run ~queue_depth:4 @@ fun env ->
+  let ( / ) = Eio.Path.( / ) in
+  let path = env#cwd / "test2.data" in
+  let msg = "hello" in
+  Eio.Path.save path ("!" ^ msg) ~create:(`Exclusive 0o600);
+  let buf = Uring.Statx.create () in
+  let test ~flags ?fd path =
+    Eio_linux.Low_level.statx ~mask:X.Mask.(type' + size) ?fd path buf flags;
+    Alcotest.check kind_t "kind" `Regular_file (Uring.Statx.kind buf);
+    Alcotest.(check int64) "size" 6L (Uring.Statx.size buf)
+  in
+  (* Lookup via cwd *)
+  test ~flags:X.Flags.empty ?fd:None "test.data";
+  (* Lookup via file FD *)
+  Switch.run (fun sw ->
+      let fd = Eio_linux.Low_level.openat2 ~sw
+          ~access:`R
+          ~flags:Uring.Open_flags.empty
+          ~perm:0
+          ~resolve:Uring.Resolve.empty
+          "test.data"
+      in
+      test ~flags:X.Flags.empty_path ~fd ""
+    );
+  (* Lookup via directory FD *)
+  Switch.run (fun sw ->
+      let fd = Eio_linux.Low_level.openat2 ~sw
+          ~access:`R
+          ~flags:Uring.Open_flags.path
+          ~perm:0
+          ~resolve:Uring.Resolve.empty
+          "."
+      in
+      test ~flags:X.Flags.empty_path ~fd "test.data"
+    );
+  ()
+
 let () =
   let open Alcotest in
   run "eio_linux" [
@@ -167,5 +208,6 @@ let () =
       test_case "no_sqe"        `Quick test_no_sqe;
       test_case "read_exact"    `Quick test_read_exact;
       test_case "expose_backend"    `Quick test_expose_backend;
+      test_case "statx"         `Quick test_statx;
     ];
   ]