Adds blocking file locks.

runtime/bin/file_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 "platform/globals.h"
 #if defined(TARGET_OS_WINDOWS)
 
 #include "bin/file.h"
 
 #include <fcntl.h>  // NOLINT
@@ skipping 120 matching lines @@
   }
   int32_t length_low = Utils::Low32Bits(length);
   int32_t length_high = Utils::High32Bits(length);
 
   BOOL rc;
   switch (lock) {
     case File::kLockUnlock:
       rc = UnlockFileEx(handle, 0, length_low, length_high, &overlapped);
       break;
     case File::kLockShared:
-    case File::kLockExclusive: {
-      DWORD flags = LOCKFILE_FAIL_IMMEDIATELY;
-      if (lock == File::kLockExclusive) {
+    case File::kLockExclusive:
+    case File::kLockBlockingShared:
+    case File::kLockBlockingExclusive: {
+      DWORD flags = 0;
+      if ((lock == File::kLockShared) || (lock == File::kLockExclusive)) {
+        flags |= LOCKFILE_FAIL_IMMEDIATELY;
+      }
+      if ((lock == File::kLockExclusive) ||
+          (lock == File::kLockBlockingExclusive)) {
         flags |= LOCKFILE_EXCLUSIVE_LOCK;
       }
       rc = LockFileEx(handle, flags, 0,
                       length_low, length_high, &overlapped);
       break;
     }
     default:
       UNREACHABLE();
   }
   return rc;
@@ skipping 539 matching lines @@
     return kIdentical;
   } else {
     return kDifferent;
   }
 }
 
 }  // namespace bin
 }  // namespace dart
 
 #endif  // defined(TARGET_OS_WINDOWS)