[NaCl SDK] nacl_io: Fix utime() on directories.

native_client_sdk/src/libraries/nacl_io/kernel_handle.cc

Index: native_client_sdk/src/libraries/nacl_io/kernel_handle.cc
diff --git a/native_client_sdk/src/libraries/nacl_io/kernel_handle.cc b/native_client_sdk/src/libraries/nacl_io/kernel_handle.cc
index f7bf16313f554758a19ebbbdf70a48132edc3707..4f88bbf8c6de542164875651c7204cc97ac75a90 100644
--- a/native_client_sdk/src/libraries/nacl_io/kernel_handle.cc
+++ b/native_client_sdk/src/libraries/nacl_io/kernel_handle.cc
@@ -44,6 +44,11 @@ Error KernelHandle::Init(int open_flags) {
     return EACCES;
   }
 
+  // Directories can only be opened read-only.
+  if ((open_flags & 3) != O_RDONLY && node_->IsaDir()) {
+    return EISDIR;
+  }
+
   if (open_flags & O_APPEND) {
     Error error = node_->GetSize(&handle_attr_.offs);
     if (error)