hof/flow: allow to config stdin passthrough in os.Exec

flow/tasks/os/exec.go

@@ -227,6 +227,9 @@ func extractIO(ex cue.Value) (Stdin io.Reader, Stdout, Stderr io.Writer, err err
 			}
 			Stdin = bytes.NewReader(b)
 
+		case cue.BoolKind:
+			Stdin = os.Stdin
+
 		case cue.NullKind:
 			// do nothing so no Stdin is set
 
@@ -248,6 +251,9 @@ func extractIO(ex cue.Value) (Stdin io.Reader, Stdout, Stderr io.Writer, err err
 		case cue.BytesKind:
 			Stdout = new(bytes.Buffer)
 
+		case cue.BoolKind:
+			Stdin = os.Stdout
+
 		case cue.NullKind:
 			// do nothing so no Stdin is set
 
@@ -269,6 +275,9 @@ func extractIO(ex cue.Value) (Stdin io.Reader, Stdout, Stderr io.Writer, err err
 		case cue.BytesKind:
 			Stderr = new(bytes.Buffer)
 
+		case cue.BoolKind:
+			Stdin = os.Stderr
+
 		case cue.NullKind:
 			// do nothing so no Stdin is set
 

flow/tasks/os/schema.cue

@@ -19,15 +19,15 @@ Exec: {
 	// stdout captures the output from stdout if it is of type bytes or string.
 	// The default value of null indicates it is redirected to the stdout of the
 	// current process.
-	stdout?: null | string | bytes
+	stdout?: null | bool | string | bytes
 
 	// stderr is like stdout, but for errors.
-	stderr?: null | string | bytes
+	stderr?: null | bool | string | bytes
 
-	// stdin specifies the input for the process. If stdin is null, the stdin
+	// stdin specifies the input for the process. If stdin is bool (true or false), the stdin
 	// of the current process is redirected to this command (the default).
 	// If it is of typ bytes or string, that input will be used instead.
-	stdin?: *null | string | bytes
+	stdin?: *null | bool | string | bytes
 
 	// success is set to true when the process terminates with with a zero exit
 	// code or false otherwise. The user can explicitly specify the value