[dart:io] Adds Stdin.hasTerminal to mirror Stdout.hasTerminal

fixes #29083

Change-Id: I5f4d7ac2a5df9600fd3ad12abc2dd6068d9980af
Reviewed-on: https://dart-review.googlesource.com/23145
Reviewed-by: Ryan Macnak <rmacnak@google.com>

CHANGELOG.md

@@ -54,7 +54,7 @@
     `ascii`, `base64`, `base64Uri`, `json`, `latin1` and `utf8`.
   * Renamed the `HtmlEscapeMode` constants `UNKNOWN`, `ATTRIBUTE`,
     `SQ_ATTRIBUTE` and `ELEMENT` to `unknown`, `attribute`, `sqAttribute` and
-    `elements.
+    `elements`.
 
 * `dart:developer`
   * `Timeline.startSync` and `Timeline.timeSync` now accept an optional
@@ -69,6 +69,8 @@
     methods are now supported on iOS and OSX.
   * Deprecated `SecurityContext.alpnSupported` as ALPN is now supported on all
     platforms.
+  * Added `withTrustedRoots` named optional parameter to `SecurityContext`
+    constructor, which defaults to false.
   * Added a `timeout` parameter to `Socket.connect`, `RawSocket.connect`,
     `SecureSocket.connect` and `RawSecureSocket.connect`. If a connection attempt
     takes longer than the duration specified in `timeout`, a `SocketException`
@@ -81,6 +83,7 @@
     decompression routines.
   * Added `IOOverrides` and `HttpOverrides` to aid in writing tests that wish to
     mock varios `dart:io` objects.
+  # Added `Stdin.hasTerminal`.
 
 * `dart.math`
   * Renamed `E`, `LN10`, `LN`, `LOG2E`, `LOG10E`, `PI`, `SQRT1_2` and `SQRT2`

sdk/lib/io/stdio.dart

@@ -167,6 +167,20 @@ class Stdin extends _StdStream implements Stream<List<int>> {
    * If at end of file, -1 is returned.
    */
   external int readByteSync();
+
+  /**
+   * Returns true if there is a terminal attached to stdin.
+   */
+  bool get hasTerminal {
+    try {
+      return stdioType(this) == StdioType.TERMINAL;
+    } on FileSystemException catch (_) {
+      // If stdioType throws a FileSystemException, then it is not hooked up to
+      // a terminal, probably because it is closed, but let other exception
+      // types bubble up.
+      return false;
+    }
+  }
 }
 
 /**

tests/standalone_2/io/stdin_has_terminal_test.dart

@@ -0,0 +1,26 @@
+// Copyright (c) 2017, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import "dart:io";
+
+import "package:expect/expect.dart";
+
+void fiddleWithEchoMode() {
+  final bool echoMode = stdin.echoMode;
+  stdin.echoMode = false;
+  stdin.echoMode = true;
+  stdin.echoMode = echoMode;
+}
+
+void main() {
+  Expect.isNotNull(stdin.hasTerminal);
+  Expect.isTrue(stdin.hasTerminal is bool);
+  if (stdin.hasTerminal) {
+    fiddleWithEchoMode();
+  } else {
+    Expect.throws(() {
+      fiddleWithEchoMode();
+    }, (e) => e is StdinException);
+  }
+}