Add Eio.Vars.t to Stdenv

lib_eio/eio.ml

@@ -23,6 +23,7 @@ end
 module Buf_write = Buf_write
 module Net = Net
 module Process = Process
+module Vars = Vars
 module Domain_manager = Domain_manager
 module Time = Time
 module File = File
@@ -35,6 +36,7 @@ module Stdenv = struct
   let stderr (t : <stderr : _ Flow.sink;   ..>) = t#stderr
   let net (t : <net : _ Net.t; ..>) = t#net
   let process_mgr (t : <process_mgr : _ Process.mgr; ..>) = t#process_mgr
+  let vars (t : <vars : _ Vars.t; ..>) = t#vars
   let domain_mgr (t : <domain_mgr : _ Domain_manager.t; ..>) = t#domain_mgr
   let clock (t : <clock : _ Time.clock; ..>) = t#clock
   let mono_clock (t : <mono_clock : _ Time.Mono.t; ..>) = t#mono_clock

lib_eio/eio.mli

@@ -181,6 +181,9 @@ module Fs = Fs
 (** Managing child processes. *)
 module Process = Process
 
+(** Accessing environment variables *)
+module Vars = Vars
+
 (** {2 Time} *)
 
 (** Clocks, time, sleeping and timeouts. *)
@@ -244,6 +247,9 @@ module Stdenv : sig
   val process_mgr : <process_mgr : _ Process.mgr as 'a; ..> -> 'a
   (** [process_mgr t] allows you to manage child processes. *)
 
+  val vars : <vars : _ Vars.t as 'a; ..> -> 'a
+  (** [vars t] allows you to access environment variables. *)
+
   (** {1 Domains (using multiple CPU cores)}
 
       To use this, see {!Domain_manager}.

lib_eio/unix/eio_unix.ml

@@ -34,6 +34,7 @@ module Stdenv = struct
     net : [`Unix | `Generic] Eio.Net.ty r;
     domain_mgr : Eio.Domain_manager.ty r;
     process_mgr : Process.mgr_ty r;
+    vars : Eio.Vars.ty r;
     clock : float Eio.Time.clock_ty r;
     mono_clock : Eio.Time.Mono.ty r;
     fs : Eio.Fs.dir_ty Eio.Path.t;
@@ -45,7 +46,7 @@ module Stdenv = struct
 
   let override
     ?stdin ?stdout ?stderr ?net ?domain_mgr
-    ?process_mgr ?clock ?mono_clock ?fs ?cwd
+    ?process_mgr ?vars ?clock ?mono_clock ?fs ?cwd
     ?secure_random ?debug ?backend_id (env : <base; ..>) : base
   =
     object
@@ -55,6 +56,7 @@ module Stdenv = struct
       method net = Option.value ~default:env#net net 
       method domain_mgr = Option.value ~default:env#domain_mgr domain_mgr 
       method process_mgr = Option.value ~default:env#process_mgr process_mgr
+      method vars = Option.value ~default:env#vars vars
       method clock = Option.value ~default:env#clock clock
       method mono_clock = Option.value ~default:env#mono_clock mono_clock
       method fs = Option.value ~default:env#fs fs

lib_eio/unix/eio_unix.mli

@@ -95,6 +95,7 @@ module Stdenv : sig
     net : [`Unix | `Generic] Eio.Net.ty r;
     domain_mgr : Eio.Domain_manager.ty r;
     process_mgr : Process.mgr_ty r;
+    vars : Eio.Vars.ty r;
     clock : float Eio.Time.clock_ty r;
     mono_clock : Eio.Time.Mono.ty r;
     fs : Eio.Fs.dir_ty Eio.Path.t;
@@ -114,6 +115,7 @@ module Stdenv : sig
     ?net:[ `Generic | `Unix ] Eio.Net.ty r ->
     ?domain_mgr:Eio.Domain_manager.ty r ->
     ?process_mgr:Process.mgr_ty r ->
+    ?vars:Eio.Vars.ty r ->
     ?clock:float Eio.Time.clock_ty r ->
     ?mono_clock:Eio.Time.Mono.ty r ->
     ?fs:Eio.Fs.dir_ty Eio.Path.t ->
@@ -156,6 +158,8 @@ module Private : sig
 
   val setsockopt : Fd.t -> 'a Eio.Net.Sockopt.t -> 'a -> unit
   val getsockopt : Fd.t -> 'a Eio.Net.Sockopt.t -> 'a
+
+  val vars : Eio.Vars.ty r
 end
 
 module Pi = Pi

lib_eio/unix/private.ml

@@ -295,3 +295,14 @@ let getsockopt : type a. Fd.t -> a Eio.Net.Sockopt.t -> a = fun fd opt ->
       | Net.Sockopt_float bo -> Unix.getsockopt_float fd bo
       | _ -> raise (Eio.Net.err Invalid_option)
     with Unix.Unix_error (code, name, arg) -> raise (Err.v code name arg)
+
+module Vars = struct
+  type t = unit
+  let get_all () = Unix.environment () |> Eio.Process.Env.of_array
+  let get_opt () name =
+    try Some (Unix.getenv name) with Not_found -> None
+end
+
+let vars =
+  let handler = Eio.Vars.Pi.vars (module Vars) in
+  Eio.Resource.T ((), handler)

lib_eio/vars.ml

@@ -0,0 +1,30 @@
+open Std
+
+type ty = [ `Vars ]
+type 'a t = ([> ty] as 'a) r
+
+module Pi = struct
+  module type VARS = sig
+    type t
+
+    val get_all : t -> Process.Env.t 
+    val get_opt : t -> string -> string option
+  end
+
+  type (_, _, _) Resource.pi +=
+    | Vars : ('t, (module VARS with type t = 't), [> ty ]) Resource.pi
+
+  let vars (type t) (module X : VARS with type t = t) =
+    Resource.handler [ H (Vars, (module X)) ]
+end
+
+let get_all t =
+  let (Resource.T (t, ops)) = t in
+  let module X = (val (Resource.get ops Pi.Vars)) in
+  X.get_all t
+
+let get_opt t name =
+  let (Resource.T (t, ops)) = t in
+  let module X = (val (Resource.get ops Pi.Vars)) in
+  X.get_opt t name
+

lib_eio/vars.mli

@@ -0,0 +1,24 @@
+open Std
+
+type ty = [ `Vars ]
+type 'a t = ([> ty] as 'a) r
+
+(** {1 Accessing environment variables} *)
+
+val get_all : _ t -> Process.Env.t 
+(** [get_all vars] gets the full list of environment variables. *)
+
+val get_opt : _ t -> string -> string option
+(** [get_opt vars name] will get the environment variable called [name].
+    Returns [None] if [name] does not exist. *)
+
+module Pi : sig
+  module type VARS = sig
+    type t
+
+    val get_all : t -> Process.Env.t 
+    val get_opt : t -> string -> string option
+  end
+
+  val vars : (module VARS with type t = 't) -> ('t, ty) Resource.handler
+end

lib_eio_linux/eio_linux.ml

@@ -84,6 +84,7 @@ let stdenv ~run_event_loop =
     method stderr = Flow.stderr
     method net = Net.v
     method process_mgr = Process.mgr
+    method vars = Eio_unix.Private.vars
     method domain_mgr = domain_mgr ~run_event_loop
     method clock = Time.clock
     method mono_clock = Time.mono_clock

lib_eio_linux/tests/spawn.md

@@ -7,8 +7,6 @@ open Eio.Std
 
 module Env = Eio.Process.Env
 module Process = Eio_linux.Low_level.Process
-
-let default_env = Unix.environment () |> Env.of_array
 ```
 
 ## Spawning processes
@@ -31,7 +29,8 @@ FOO=bar
 Changing directory:
 
 ```ocaml
-# Eio_linux.run @@ fun _env ->
+# Eio_linux.run @@ fun env ->
+  let default_env = Eio.Stdenv.vars env |> Eio.Vars.get_all in
   Switch.run @@ fun sw ->
   let child = Process.spawn ~sw Process.Fork_action.[
     chdir "/";
@@ -47,7 +46,8 @@ Changing directory:
 Changing directory using a file descriptor:
 
 ```ocaml
-# Eio_linux.run @@ fun _env ->
+# Eio_linux.run @@ fun env ->
+  let default_env = Eio.Stdenv.vars env |> Eio.Vars.get_all in
   Switch.run @@ fun sw ->
   let root =
     Eio_linux.Low_level.openat2 ~sw "/"
@@ -71,7 +71,8 @@ Changing directory using a file descriptor:
 Exit status:
 
 ```ocaml
-# Eio_linux.run @@ fun _env ->
+# Eio_linux.run @@ fun env ->
+  let default_env = Eio.Stdenv.vars env |> Eio.Vars.get_all in
   Switch.run @@ fun sw ->
   let child = Process.spawn ~sw Process.Fork_action.[
     execve "/usr/bin/env"
@@ -85,7 +86,8 @@ Exit status:
 Failure starting child:
 
 ```ocaml
-# Eio_linux.run @@ fun _env ->
+# Eio_linux.run @@ fun env ->
+  let default_env = Eio.Stdenv.vars env |> Eio.Vars.get_all in
   Switch.run @@ fun sw ->
   Process.spawn ~sw Process.Fork_action.[
     chdir "/idontexist";
@@ -99,7 +101,8 @@ Exception: Unix.Unix_error(Unix.ENOENT, "chdir", "")
 Signalling a running child:
 
 ```ocaml
-# Eio_linux.run @@ fun _env ->
+# Eio_linux.run @@ fun env ->
+  let default_env = Eio.Stdenv.vars env |> Eio.Vars.get_all in
   Switch.run @@ fun sw ->
   let child =
     Process.spawn ~sw Process.Fork_action.[

lib_eio_posix/eio_posix.ml

@@ -33,6 +33,7 @@ let run main =
     method clock = Time.clock
     method mono_clock = Time.mono_clock
     method net = Net.v
+    method vars = Eio_unix.Private.vars
     method process_mgr = Process.mgr
     method domain_mgr = Domain_mgr.v
     method cwd = (Fs.cwd :> Eio.Fs.dir_ty Eio.Path.t)

lib_eio_posix/test/spawn.md

@@ -7,8 +7,6 @@ open Eio.Std
 
 module Env = Eio.Process.Env
 module Process = Eio_posix.Low_level.Process
-
-let default_env = Unix.environment () |> Env.of_array
 ```
 
 ## Spawning processes
@@ -31,7 +29,8 @@ FOO=bar
 Changing directory:
 
 ```ocaml
-# Eio_posix.run @@ fun _env ->
+# Eio_posix.run @@ fun env ->
+  let default_env = Eio.Stdenv.vars env |> Eio.Vars.get_all in
   Switch.run @@ fun sw ->
   let child = Process.spawn ~sw Process.Fork_action.[
     chdir "/";
@@ -47,7 +46,8 @@ Changing directory:
 Changing directory using a file descriptor:
 
 ```ocaml
-# Eio_posix.run @@ fun _env ->
+# Eio_posix.run @@ fun env ->
+  let default_env = Eio.Stdenv.vars env |> Eio.Vars.get_all in
   Switch.run @@ fun sw ->
   let root = Eio_posix.Low_level.openat ~sw ~mode:0 Fs "/" Eio_posix.Low_level.Open_flags.(rdonly + directory) in
   let child = Process.spawn ~sw Process.Fork_action.[
@@ -64,7 +64,8 @@ Changing directory using a file descriptor:
 Exit status:
 
 ```ocaml
-# Eio_posix.run @@ fun _env ->
+# Eio_posix.run @@ fun env ->
+  let default_env = Eio.Stdenv.vars env |> Eio.Vars.get_all in
   Switch.run @@ fun sw ->
   let child = Process.spawn ~sw Process.Fork_action.[
     execve "/usr/bin/env"
@@ -78,7 +79,8 @@ Exit status:
 Failure starting child:
 
 ```ocaml
-# Eio_posix.run @@ fun _env ->
+# Eio_posix.run @@ fun env ->
+  let default_env = Eio.Stdenv.vars env |> Eio.Vars.get_all in
   Switch.run @@ fun sw ->
   Process.spawn ~sw Process.Fork_action.[
     chdir "/idontexist";
@@ -92,7 +94,8 @@ Exception: Unix.Unix_error(Unix.ENOENT, "chdir", "")
 Signalling a running child:
 
 ```ocaml
-# Eio_posix.run @@ fun _env ->
+# Eio_posix.run @@ fun env ->
+  let default_env = Eio.Stdenv.vars env |> Eio.Vars.get_all in
   Switch.run @@ fun sw ->
   let child =
     Process.spawn ~sw Process.Fork_action.[
@@ -163,7 +166,8 @@ let read_all pipe =
 Swapping FDs (note: plain sh can't handle multi-digit FDs!):
 
 ```ocaml
-# Eio_posix.run @@ fun _env ->
+# Eio_posix.run @@ fun env ->
+  let default_env = Eio.Stdenv.vars env |> Eio.Vars.get_all in
   Switch.run @@ fun sw ->
   let pipe1_r, pipe1_w = Eio_unix.pipe sw in
   let pipe2_r, pipe2_w = Eio_unix.pipe sw in
@@ -208,7 +212,8 @@ Swapping FDs (note: plain sh can't handle multi-digit FDs!):
 Keeping an FD open:
 
 ```ocaml
-# Eio_posix.run @@ fun _env ->
+# Eio_posix.run @@ fun env ->
+  let default_env = Eio.Stdenv.vars env |> Eio.Vars.get_all in
   Switch.run @@ fun sw ->
   let pipe1_r, pipe1_w = Eio_unix.pipe sw in
   let child =

lib_eio_windows/eio_windows.ml

@@ -34,6 +34,7 @@ let run main =
     method cwd = (Fs.cwd :> Eio.Fs.dir_ty Eio.Path.t)
     method fs = (Fs.fs :> Eio.Fs.dir_ty Eio.Path.t)
     method process_mgr = failwith "process operations not supported on Windows yet"
+    method vars = Eio_unix.Private.vars
     method secure_random = Flow.secure_random
     method backend_id = "windows"
   end

tests/process.md

@@ -233,6 +233,16 @@ A custom environment:
 - : string = ":2"
 ```
 
+Using the parent's environment explicitly:
+
+```ocaml
+# run @@ fun mgr env ->
+  Unix.putenv "DISPLAY" ":1";
+  let env = Eio.Stdenv.vars env |> Eio.Vars.get_all in
+  Process.parse_out ~env mgr Eio.Buf_read.line ["sh"; "-c"; "echo $DISPLAY"];;
+- : string = ":1"
+```
+
 Eio's child reaping code doesn't interfere with OCaml's process spawning:
 
 ```ocaml
@@ -320,3 +330,28 @@ val e : Env.t = [""
              "c=5"
              "c=6"]
 ```
+
+Using the environment capability:
+
+```ocaml
+# run @@ fun _mgr env ->
+  Unix.putenv "DISPLAY" ":1";
+  let vars = Eio.Stdenv.vars env in
+  Eio.Vars.get_opt vars "DISPLAY";;
+- : string option = Some ":1"
+```
+
+```ocaml
+# run @@ fun _mgr env ->
+  let vars = Eio.Stdenv.vars env in
+  Eio.Vars.get_opt vars "THIS_VAR_PROBABLY_WILL_NOT_EXIST";;
+- : string option = None
+```
+
+```ocaml
+# run @@ fun _mgr env ->
+  Unix.putenv "DISPLAY" ":1";
+  let env = Eio.Stdenv.vars env |> Eio.Vars.get_all in
+  Eio.Process.Env.get_opt "DISPLAY" env;;
+- : string option = Some ":1"
+```