Fix for Directory.exists on Windows using GetFileAttributes

runtime/bin/directory_win.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 "bin/directory.h"
 
 #include <errno.h>
 #include <sys/stat.h>
 
 #include "bin/platform.h"
@@ skipping 204 matching lines @@
     if ((attributes & FILE_ATTRIBUTE_READONLY) == FILE_ATTRIBUTE_READONLY) {
       attributes &= ~FILE_ATTRIBUTE_READONLY;
 
       if (SetFileAttributes(path, attributes) == 0) {
         return false;
       }
 
       return DeleteFile(path) != 0;
     }
   }
+
+  return false;
 }
 
 
 static bool DeleteDir(char* dir_name,
                       char* path,
                       int path_length) {
   if (strcmp(dir_name, ".") != 0 &&
       strcmp(dir_name, "..") != 0) {
     size_t written = snprintf(path + path_length,
                               MAX_PATH - path_length,
@@ skipping 76 matching lines @@
 
 bool Directory::List(const char* dir_name,
                      bool recursive,
                      DirectoryListing* listing) {
   bool completed = ListRecursively(dir_name, recursive, listing);
   return completed;
 }
 
 
 Directory::ExistsResult Directory::Exists(const char* dir_name) {
-  struct stat entry_info;
-  int stat_success = stat(dir_name, &entry_info);
-  if (stat_success == 0) {
-    if ((entry_info.st_mode & S_IFMT) == S_IFDIR) {
-      return EXISTS;
+  DWORD attributes = GetFileAttributes(dir_name);
+  if (attributes == INVALID_FILE_ATTRIBUTES) {
+    DWORD last_error = GetLastError();
+    if (last_error == ERROR_FILE_NOT_FOUND ||
+        last_error == ERROR_PATH_NOT_FOUND) {
+      return DOES_NOT_EXIST;
     } else {
-      return DOES_NOT_EXIST;
-    }
-  } else {
-    if (errno == EACCES ||
-        errno == EBADF ||
-        errno == EFAULT ||
-        errno == ENOMEM) {
-      // Search permissions denied for one of the directories in the
-      // path or a low level error occured. We do not know if the
-      // directory exists.
+      // We might not be able to get the file attributes for other
+      // reasons such as lack of permissions. In that case we do
+      // not know if the directory exists.
       return UNKNOWN;
     }
-    ASSERT(errno == ENAMETOOLONG ||
-           errno == ENOENT ||
-           errno == ENOTDIR);
-    return DOES_NOT_EXIST;
   }
+  bool exists = (attributes & FILE_ATTRIBUTE_DIRECTORY) != 0;
+  return exists ? EXISTS : DOES_NOT_EXIST;
 }
 
 
 char* Directory::Current() {
   char* result;
   int length = GetCurrentDirectory(0, NULL);
   result = reinterpret_cast<char*>(malloc(length + 1));
   GetCurrentDirectory(length + 1, result);
   return result;
 }
@@ skipping 70 matching lines @@
   // MoveFile does not allow replacing exising directories. Therefore,
   // if the new_path is currently a directory we need to delete it
   // first.
   if (new_exists == EXISTS) {
     bool success = DeleteRecursively(new_path);
     if (!success) return false;
   }
   DWORD flags = MOVEFILE_WRITE_THROUGH;
   return (MoveFileEx(path, new_path, flags) != 0);
 }