Fix a number of issues with determining the type of stdio

runtime/bin/socket_macos.cc

 // Copyright (c) 2013, 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.
 
 #include "platform/globals.h"
 #if defined(TARGET_OS_MACOS)
 
 #include <errno.h>  // NOLINT
 #include <stdio.h>  // NOLINT
 #include <stdlib.h>  // NOLINT
@@ skipping 125 matching lines @@
              SOL_SOCKET,
              SO_ERROR,
              &errno,
              reinterpret_cast<socklen_t*>(&len));
   os_error->SetCodeAndMessage(OSError::kSystem, errno);
 }
 
 
 int Socket::GetType(intptr_t fd) {
   struct stat buf;
-  if (isatty(fd)) return File::kTerminal;
   int result = fstat(fd, &buf);
   if (result == -1) return -1;
+  if (S_ISCHR(buf.st_mode)) return File::kTerminal;
   if (S_ISFIFO(buf.st_mode)) return File::kPipe;
   if (S_ISREG(buf.st_mode)) return File::kFile;
   return File::kOther;
 }
 
 
 intptr_t Socket::GetStdioHandle(int num) {
   return static_cast<intptr_t>(num);
 }
 
@@ skipping 118 matching lines @@
 bool Socket::SetNoDelay(intptr_t fd, bool enabled) {
   int on = enabled ? 1 : 0;
   return TEMP_FAILURE_RETRY(setsockopt(fd,
                                        IPPROTO_TCP,
                                        TCP_NODELAY,
                                        reinterpret_cast<char *>(&on),
                                        sizeof(on))) == 0;
 }
 
 #endif  // defined(TARGET_OS_MACOS)