libartbase/base/scoped_flock_test.cc

/*
 * Copyright (C) 2014 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "scoped_flock.h"

#include "base/common_art_test.h"

namespace art {

class ScopedFlockTest : public CommonArtTest {};

TEST_F(ScopedFlockTest, TestLocking) {
  ScratchFile scratch_file;
  std::string error_msg;

  // NOTE: Locks applied using flock(2) and fcntl(2) are oblivious
  // to each other, so attempting to query locks set by flock using
  // using fcntl(,F_GETLK,) will not work. see kernel doc at
  // Documentation/filesystems/locks.txt.
  {
    ScopedFlock file_lock = LockedFile::Open(scratch_file.GetFilename().c_str(),
                                             &error_msg);
    ASSERT_TRUE(file_lock.get() != nullptr);

    // Attempt to acquire a second lock on the same file. This must fail.
    ScopedFlock second_lock = LockedFile::Open(scratch_file.GetFilename().c_str(),
                                               O_RDONLY,
                                               /* block= */ false,
                                               &error_msg);
    ASSERT_TRUE(second_lock.get() == nullptr);
    ASSERT_TRUE(!error_msg.empty());
  }

  {
    // Attempt to reacquire the lock once the first lock has been released, this
    // must succeed.
    ScopedFlock file_lock = LockedFile::Open(scratch_file.GetFilename().c_str(),
                                             &error_msg);
    ASSERT_TRUE(file_lock.get() != nullptr);
  }

  {
    ScopedFlock file_lock = LockedFile::Open("/will/not/exist",
                                             &error_msg);
    ASSERT_TRUE(file_lock.get() == nullptr);
  }
}

}  // namespace art