add popen2 to anoia.fs

pkgs/anoia/fs.fnl

@@ -65,6 +65,29 @@
     unknown
     (error (.. "can't remove " pathname " of mode \"" unknown "\""))))
 
+(fn popen2 [pname argv envp]
+  (case (ll.pipe2)
+    (cin-s cin-d)
+    (match (ll.pipe2)
+      (cout-s cout-d)
+      (let [(pid err) (ll.fork)]
+        (if (not pid) (error (.. "error: " err))
+            (= pid 0)
+            (do
+              (ll.close cin-d)
+              (ll.close cout-s)
+              (ll.dup2 cin-s 0)
+              (ll.dup2 cout-d 1)
+              (ll.dup2 cout-d 2)
+              (ll.execve pname argv envp)
+              (error "execve failed"))
+            (> pid 0)
+            (do
+              (ll.close cin-s)
+              (ll.close cout-d)))
+        (values pid cin-d cout-s))
+      (nil err) (error (.. "popen pipe out: " err)))
+    (nil err) (error (.. "popen pipe in: " err))))
 
 {
  : mktree
@@ -72,5 +95,6 @@
  : directory?
  : dir
  : file-type
+ : popen2
  :symlink (fn [from to] (ll.symlink from to))
  }