HID : read-only device access fallback when read/write fails

device/hid/hid_connection_win.cc

 // Copyright (c) 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "device/hid/hid_connection_win.h"
 
 #include <cstring>
 
 #include "base/message_loop/message_loop.h"
 #include "base/stl_util.h"
@@ skipping 84 matching lines @@
   Release();
 }
 
 void PendingHidTransfer::WillDestroyCurrentMessageLoop() {
   watcher_.StopWatching();
   connection_->OnTransferCanceled(this);
 }
 
 HidConnectionWin::HidConnectionWin(const HidDeviceInfo& device_info)
     : HidConnection(device_info) {
   DCHECK(thread_checker_.CalledOnValidThread());

[Ken Rockot(use gerrit already), 2014/04/21 20:33:25]

nit: Remove extra vertical whitespace.

[jracle (use Gerrit), 2014/04/23 07:38:09]

sure, sorry. Thought DCHECK(...) was the only line impacted (cause it is after
an opening '{')

+
   file_.Set(CreateFileA(device_info.device_id.c_str(),
                         GENERIC_WRITE | GENERIC_READ,
                         FILE_SHARE_READ | FILE_SHARE_WRITE,
                         NULL,
                         OPEN_EXISTING,
                         FILE_FLAG_OVERLAPPED,
                         NULL));
+
+  if (!file_.IsValid() &&
+      file_.error_details() == base::File::FILE_ERROR_ACCESS_DENIED) {
+    file_.Set(CreateFileA(device_info.device_id.c_str(),
+                          GENERIC_READ,
+                          FILE_SHARE_READ,
+                          NULL,
+                          OPEN_EXISTING,
+                          FILE_FLAG_OVERLAPPED,
+                          NULL));
+  }
 }
 
 bool HidConnectionWin::available() const {
   return file_.IsValid();
 }
 
 HidConnectionWin::~HidConnectionWin() {
   DCHECK(thread_checker_.CalledOnValidThread());
   CancelIo(file_.Get());
 }
@@ skipping 156 matching lines @@
   }
 }
 
 void HidConnectionWin::OnTransferCanceled(
     scoped_refptr<PendingHidTransfer> transfer) {
   transfers_.erase(transfer);
   transfer->callback_.Run(false, 0);
 }
 
 }  // namespace device