Merge pull request #690 from talex5/fd-bits

Minor file-descriptor improvements

lib_eio/unix/fd.ml

@@ -77,6 +77,8 @@ let is_seekable t =
     t.seekable <- if seekable then Yes else No;
     seekable
 
+let is_open t = Rcfd.is_open t.fd
+
 let rec use_exn_list op xs k =
   match xs with
   | [] -> k []

lib_eio/unix/fd.mli

@@ -55,6 +55,12 @@ val remove : t -> Unix.file_descr option
 
     Returns [None] if [t] is closed by another fiber first. *)
 
+val is_open : t -> bool
+(** [is_open t] returns [true] until [t] has been marked as closing, after which it returns [false].
+
+    This is mostly useful inside the callback of {!use}, to test whether
+    another fiber has started closing [t] (in which case you may decide to stop early). *)
+
 (** {2 Flags} *)
 
 val is_blocking : t -> bool

lib_eio_posix/include/discover.ml

@@ -8,7 +8,7 @@ let optional_flags = [
 
 let () =
   C.main ~name:"discover" (fun c ->
-      let c_flags = ["-D_LARGEFILE64_SOURCE"; "-D_XOPEN_SOURCE=700"; "-D_DARWIN_C_SOURCE"] in
+      let c_flags = ["-D_LARGEFILE64_SOURCE"; "-D_XOPEN_SOURCE=700"; "-D_DARWIN_C_SOURCE"; "-D_GNU_SOURCE"] in
       let includes = ["sys/types.h"; "sys/stat.h"; "fcntl.h"] in
       let extra_flags, missing_defs =
         C.C_define.import c ~c_flags ~includes

tests/fs.md

@@ -519,6 +519,45 @@ Create a sandbox, write a file with it, then read it from outside:
 - : unit = ()
 ```
 
+```ocaml
+# run ~clear:["foo"] @@ fun env ->
+  let fs = env#fs in
+  let cwd = env#cwd in
+  Path.mkdirs (cwd / "foo/bar") ~perm:0o700;
+  let test ?(succeeds=true) path =
+    Eio.Exn.Backend.show := succeeds;
+    try
+      Switch.run @@ fun sw ->
+      let _ : _ Path.t = Path.open_dir ~sw path in
+      traceln "open_dir %a -> OK" Path.pp path
+    with ex ->
+      traceln "@[<h>%a@]" Eio.Exn.pp ex
+  in
+  let reject = test ~succeeds:false in
+  test (cwd / "foo/bar");
+  reject (cwd / "..");
+  test (cwd / ".");
+  reject (cwd / "/");
+  test (cwd / "foo/bar/..");
+  test (fs / "foo/bar");
+  Unix.symlink ".." "foo/up";
+  test (cwd / "foo/up/foo/bar");
+  Unix.symlink "/" "foo/root";
+  reject (cwd / "foo/root/..");
++open_dir <cwd:foo/bar> -> OK
++Eio.Io Fs Permission_denied _, opening directory <cwd:..>
++open_dir <cwd:.> -> OK
++Eio.Io Fs Permission_denied _, opening directory <cwd:/>
++open_dir <cwd:foo/bar/..> -> OK
++open_dir <fs:foo/bar> -> OK
++open_dir <cwd:foo/up/foo/bar> -> OK
++Eio.Io Fs Permission_denied _, opening directory <cwd:foo/root/..>
+- : unit = ()
+
+# Eio.Exn.Backend.show := false
+- : unit = ()
+```
+
 # Unconfined FS access
 
 We create a directory and chdir into it.
@@ -684,7 +723,7 @@ let try_rename t =
 Confined:
 
 ```ocaml
-# run ~clear:["tmp"; "dir"] @@ fun env -> try_rename env#cwd;;
+# run ~clear:["tmp"; "dir"; "foo"] @@ fun env -> try_rename env#cwd;;
 +mkdir <cwd:tmp> -> ok
 +rename <cwd:tmp> to <cwd:dir> -> ok
 +write <cwd:foo> -> ok