isTTY in tty_wrap.cpp

Summary: isTTY added to tty_wrap.cpp.

Reviewed By: avp

Differential Revision: D29746445

fbshipit-source-id: cd19d71b950c7f4cdb4f4ab3293f2f292c38b5c7

tools/node-hermes/InternalBindings/tty_wrap.cpp

@@ -52,12 +52,29 @@ static jsi::Value TTY(
   return jsi::Value(rt, thisValue);
 }
 
+/// Checks whether the stream handle is a tty handle.
+static jsi::Value isTTY(
+    RuntimeState &rs,
+    const jsi::Value &,
+    const jsi::Value *args,
+    size_t count) {
+  jsi::Runtime &rt = rs.getRuntime();
+  if (count < 1) {
+    throw jsi::JSError(
+        rt, "Not enough arguments being passed into isTTY call.");
+  }
+  int fd = args[0].asNumber();
+  bool rc = uv_guess_handle(fd) == UV_TTY;
+  return rc;
+}
+
 /// Adds the 'tty_wrap' object as a property of internalBinding.
 jsi::Value facebook::ttyBinding(RuntimeState &rs) {
   jsi::Runtime &rt = rs.getRuntime();
   jsi::Object tty_wrap{rt};
 
   rs.defineJSFunction(TTY, "TTY", 2, tty_wrap);
+  rs.defineJSFunction(isTTY, "isTTY", 1, tty_wrap);
 
   rs.setInternalBindingProp("tty_wrap", std::move(tty_wrap));
   return rs.getInternalBindingProp("tty_wrap");