Add more generic exceptions

This is to avoid depending on backend-specific exceptions in the tests.

lib_eio/eio.ml

@@ -178,6 +178,8 @@ end
 module Dir = struct
   type path = string
 
+  exception Already_exists of path * exn
+  exception Not_found of path * exn
   exception Permission_denied of path * exn
 
   type create = [`Never | `If_missing of Unix.file_perm | `Or_truncate of Unix.file_perm | `Exclusive of Unix.file_perm]

lib_eio/eio.mli

@@ -400,6 +400,8 @@ end
 module Dir : sig
   type path = string
 
+  exception Already_exists of path * exn
+  exception Not_found of path * exn
   exception Permission_denied of path * exn
 
   type create = [`Never | `If_missing of Unix.file_perm | `Or_truncate of Unix.file_perm | `Exclusive of Unix.file_perm]

lib_eio_linux/eio_linux.ml

@@ -29,6 +29,12 @@ type amount = Exactly of int | Upto of int
 
 let system_thread = Ctf.mint_id ()
 
+let wrap_errors path fn =
+  try fn () with
+  | Unix.Unix_error(Unix.EEXIST, _, _) as ex -> raise @@ Eio.Dir.Already_exists (path, ex)
+  | Unix.Unix_error(Unix.ENOENT, _, _) as ex -> raise @@ Eio.Dir.Not_found (path, ex)
+  | Unix.Unix_error(Unix.EXDEV, _, _)  as ex -> raise @@ Eio.Dir.Permission_denied (path, ex)
+
 let rec skip_empty = function
   | c :: cs when Cstruct.length c = 0 -> skip_empty cs
   | x -> x
@@ -554,13 +560,12 @@ let openfile ~sw path flags mode =
   FD.of_unix ~sw ~seekable:(FD.is_seekable fd) fd
 
 let openat2 ~sw ?seekable ~access ~flags ~perm ~resolve ?dir path =
+  wrap_errors path @@ fun () ->
   let res = enter (enqueue_openat2 (sw, access, flags, perm, resolve, dir, path)) in
   Log.debug (fun l -> l "openat2 returned");
   if res < 0 then (
     Switch.check sw;    (* If cancelled, report that instead. *)
-    let ex = Unix.Unix_error (Uring.error_of_errno res, "openat2", "") in
-    if res = -18 then raise (Eio.Dir.Permission_denied (path, ex))
-    else raise ex
+    raise @@ Unix.Unix_error (Uring.error_of_errno res, "openat2", "")
   );
   let fd : Unix.file_descr = Obj.magic res in
   let seekable =
@@ -577,6 +582,7 @@ external eio_mkdirat : Unix.file_descr -> string -> Unix.file_perm -> unit = "ca
 
 (* We ignore [sw] because this isn't a uring operation yet. *)
 let mkdirat ?sw:_ ~perm dir path =
+  wrap_errors path @@ fun () ->
   match dir with
   | None -> Unix.mkdir path perm
   | Some dir -> eio_mkdirat (FD.get "mkdirat" dir) path perm
@@ -586,7 +592,9 @@ let mkdir_beneath ?sw ~perm ?dir path =
   let leaf = Filename.basename path in
   (* [mkdir] is really an operation on [path]'s parent. Get a reference to that first: *)
   Switch.sub_opt sw (fun sw ->
-      let parent = openat2 ~sw ~seekable:false ?dir dir_path
+      let parent =
+        wrap_errors dir_path @@ fun () ->
+        openat2 ~sw ~seekable:false ?dir dir_path
           ~access:`R
           ~flags:Uring.Open_flags.(cloexec + path + directory)
           ~perm:0

tests/test_fs.md

@@ -7,6 +7,14 @@
 ```
 
 ```ocaml
+let () =
+  Printexc.register_printer (function
+    | Eio.Dir.Permission_denied (path, _) -> Some (Fmt.str "Eio.Dir.Permission_denied (%S, _)" path)
+    | Eio.Dir.Already_exists (path, _)    -> Some (Fmt.str "Eio.Dir.Already_exists (%S, _)" path)
+    | Eio.Dir.Not_found (path, _)         -> Some (Fmt.str "Eio.Dir.Not_found (%S, _)" path)
+    | _ -> None
+  )
+
 open Eio.Std
 
 let run (fn : sw:Switch.t -> Eio.Stdenv.t -> unit) =
@@ -68,9 +76,7 @@ Trying to use cwd to access a file outside of that subtree fails:
   let cwd = Eio.Stdenv.cwd env in
   write_file ~sw ~create:(`Exclusive 0o666) cwd "../test-file" "my-data";
   failwith "Should have failed"
-Exception:
-Eio.Dir.Permission_denied ("../test-file",
- Unix.Unix_error (Unix.EXDEV, "openat2", "")).
+Exception: Eio.Dir.Permission_denied ("../test-file", _)
 ```
 
 Trying to use cwd to access an absolute path fails:
@@ -79,9 +85,7 @@ Trying to use cwd to access an absolute path fails:
   let cwd = Eio.Stdenv.cwd env in
   write_file ~sw ~create:(`Exclusive 0o666) cwd "/tmp/test-file" "my-data";
   failwith "Should have failed"
-Exception:
-Eio.Dir.Permission_denied ("/tmp/test-file",
- Unix.Unix_error (Unix.EXDEV, "openat2", "")).
+Exception: Eio.Dir.Permission_denied ("/tmp/test-file", _)
 ```
 
 # Creation modes
@@ -93,7 +97,7 @@ Exclusive create fails if already exists:
   write_file ~sw ~create:(`Exclusive 0o666) cwd "test-file" "first-write";
   write_file ~sw ~create:(`Exclusive 0o666) cwd "test-file" "first-write";
   failwith "Should have failed"
-Exception: Unix.Unix_error(Unix.EEXIST, "openat2", "")
+Exception: Eio.Dir.Already_exists ("test-file", _)
 ```
 
 If-missing create succeeds if already exists:
@@ -126,7 +130,7 @@ Error if no create and doesn't exist:
   let cwd = Eio.Stdenv.cwd env in
   write_file ~sw ~create:`Never cwd "test-file" "1st-write-original";
   traceln "Got %S" @@ read_file ~sw cwd "test-file"
-Exception: Unix.Unix_error(Unix.ENOENT, "openat2", "")
+Exception: Eio.Dir.Not_found ("test-file", _)
 ```
 
 Appending to an existing file:
@@ -177,10 +181,10 @@ Creating directories with nesting, symlinks, etc:
   ()
 +mkdir "subdir" -> ok
 +mkdir "to-subdir/nested" -> ok
-+mkdir "to-root/tmp/foo" -> Eio.Dir.Permission_denied("to-root/tmp", _)
-+mkdir "../foo" -> Eio.Dir.Permission_denied("..", _)
-+mkdir "to-subdir" -> Unix.Unix_error(Unix.EEXIST, "mkdirat", "to-subdir")
-+mkdir "dangle/foo" -> Unix.Unix_error(Unix.ENOENT, "openat2", "")
++mkdir "to-root/tmp/foo" -> Eio.Dir.Permission_denied ("to-root/tmp", _)
++mkdir "../foo" -> Eio.Dir.Permission_denied ("..", _)
++mkdir "to-subdir" -> Eio.Dir.Already_exists ("to-subdir", _)
++mkdir "dangle/foo" -> Eio.Dir.Not_found ("dangle", _)
 - : unit = ()
 ```
 
@@ -196,7 +200,7 @@ Create a sandbox, write a file with it, then read it from outside:
   try_mkdir subdir "../new-sandbox";
   traceln "Got %S" @@ read_file ~sw cwd "sandbox/test-file"
 +mkdir "sandbox" -> ok
-+mkdir "../new-sandbox" -> Eio.Dir.Permission_denied("..", _)
++mkdir "../new-sandbox" -> Eio.Dir.Permission_denied ("..", _)
 +Got "data"
 - : unit = ()
 ```
@@ -221,8 +225,8 @@ Using `cwd` we can't access the parent, but using `fs` we can:
   Unix.rmdir "outside-cwd"
 +mkdir "fs-test" -> ok
 +chdir "fs-test"
-+mkdir "../outside-cwd" -> Eio.Dir.Permission_denied("..", _)
-+write "../test-file" -> Eio.Dir.Permission_denied("../test-file", _)
++mkdir "../outside-cwd" -> Eio.Dir.Permission_denied ("..", _)
++write "../test-file" -> Eio.Dir.Permission_denied ("../test-file", _)
 +mkdir "../outside-cwd" -> ok
 +write "../test-file" -> ok
 +chdir ".."

tests/test_network.md

@@ -61,7 +61,7 @@ let test_address addr ~net sw =
     (fun () ->
       run_client ~sw ~net ~addr;
       traceln "Client finished - cancelling server";
-      Switch.turn_off sw (Failure "Test is over")
+      Switch.turn_off sw Graceful_shutdown
     )
 ```
 
@@ -74,7 +74,7 @@ Handling one connection, then cancelling the server:
 +Server received: "Hello from client"
 +Client received: "Bye"
 +Client finished - cancelling server
-Exception: Failure "Test is over".
+Exception: Graceful_shutdown.
 ```
 
 Handling one connection on a Unix domain socket:
@@ -86,7 +86,7 @@ Handling one connection on a Unix domain socket:
 +Server received: "Hello from client"
 +Client received: "Bye"
 +Client finished - cancelling server
-Exception: Failure "Test is over".
+Exception: Graceful_shutdown.
 ```
 
 Handling one connection on an abstract Unix domain socket:
@@ -98,7 +98,7 @@ Handling one connection on an abstract Unix domain socket:
 +Server received: "Hello from client"
 +Client received: "Bye"
 +Client finished - cancelling server
-Exception: Failure "Test is over".
+Exception: Graceful_shutdown.
 ```
 
 Cancelling the read: