Allow opening a named pipe on MacOS and Linux.

runtime/bin/file_macos.cc

 // Copyright (c) 2012, 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 "bin/file.h"
 
 #include <copyfile.h>  // NOLINT
@@ skipping 140 matching lines @@
 File* File::FileOpenW(const wchar_t* system_name, FileOpenMode mode) {
   UNREACHABLE();
   return NULL;
 }
 
 
 File* File::ScopedOpen(const char* name, FileOpenMode mode) {
   // Report errors for non-regular files.
   struct stat st;
   if (NO_RETRY_EXPECTED(stat(name, &st)) == 0) {
-    // Only accept regular files and character devices.
-    if (!S_ISREG(st.st_mode) && !S_ISCHR(st.st_mode)) {
+    // Only accept regular files, character devices, and pipes.
+    if (!S_ISREG(st.st_mode) && !S_ISCHR(st.st_mode) && !S_ISFIFO(st.st_mode)) {
       errno = (S_ISDIR(st.st_mode)) ? EISDIR : ENOENT;
       return NULL;
     }
   }
   int flags = O_RDONLY;
   if ((mode & kWrite) != 0) {
     ASSERT((mode & kWriteOnly) == 0);
     flags = (O_RDWR | O_CREAT);
   }
   if ((mode & kWriteOnly) != 0) {
@@ skipping 289 matching lines @@
   return ((file_1_info.st_ino == file_2_info.st_ino) &&
           (file_1_info.st_dev == file_2_info.st_dev)) ?
       File::kIdentical :
       File::kDifferent;
 }
 
 }  // namespace bin
 }  // namespace dart
 
 #endif  // defined(TARGET_OS_MACOS)