Report async errors when they happend, in directory listing.

runtime/bin/directory_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/directory.h"
 
 #include <dirent.h>  // NOLINT
@@ skipping 31 matching lines @@
 
 bool PathBuffer::Add(const char* name) {
   char* data = AsString();
   int written = snprintf(data + length_,
                          PATH_MAX - length_,
                          "%s",
                          name);
   data[PATH_MAX] = '\0';
   if (written <= PATH_MAX - length_ &&
       written >= 0 &&
-      static_cast<size_t>(written) == strnlen(name, PATH_MAX + 1)) {
+      static_cast<size_t>(written) == strlen(name)) {
     length_ += written;
     return true;
   } else {
     errno = ENAMETOOLONG;
     return false;
   }
 }
 
 void PathBuffer::Reset(int new_length) {
   length_ = new_length;
@@ skipping 338 matching lines @@
 bool Directory::Rename(const char* path, const char* new_path) {
   ExistsResult exists = Exists(path);
   if (exists != EXISTS) return false;
   return (TEMP_FAILURE_RETRY(rename(path, new_path)) == 0);
 }
 
 }  // namespace bin
 }  // namespace dart
 
 #endif  // defined(TARGET_OS_MACOS)