Add Locking calls to file_io.h plus implementations and test

util/file/file_io_test.cc

+// Copyright 2015 The Crashpad Authors. All rights reserved.
+//
+// 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 "util/file/file_io.h"
+
+#include "base/atomicops.h"
+#include "base/basictypes.h"
+#include "base/files/file_path.h"
+#include "gtest/gtest.h"
+#include "util/test/errors.h"
+#include "util/test/scoped_temp_dir.h"
+#include "util/test/thread.h"
+
+namespace crashpad {
+namespace test {
+namespace {
+
+enum class ReadOrWrite : bool {
+  kRead,
+  kWrite,
+};
+
+void FileShareModeTest(ReadOrWrite first, ReadOrWrite second) {
+  ScopedTempDir temp_dir;
+  base::FilePath shared_file =
+      temp_dir.path().Append(FILE_PATH_LITERAL("shared_file"));
+  {
+    // Create an empty file to work on.
+    ScopedFileHandle create(
+        LoggingOpenFileForWrite(shared_file,
+                                FileWriteMode::kCreateOrFail,
+                                FilePermissions::kOwnerOnly));
+  }
+
+  auto handle1 = ScopedFileHandle(
+      (first == ReadOrWrite::kRead)
+          ? LoggingOpenFileForRead(shared_file)
+          : LoggingOpenFileForWrite(shared_file,
+                                    FileWriteMode::kReuseOrCreate,
+                                    FilePermissions::kOwnerOnly));
+  ASSERT_NE(handle1, kInvalidFileHandle);
+  auto handle2 = ScopedFileHandle(
+      (second == ReadOrWrite::kRead)
+          ? LoggingOpenFileForRead(shared_file)
+          : LoggingOpenFileForWrite(shared_file,
+                                    FileWriteMode::kReuseOrCreate,
+                                    FilePermissions::kOwnerOnly));
+  EXPECT_NE(handle2, kInvalidFileHandle);
+
+  EXPECT_NE(handle1.get(), handle2.get());
+}
+
+TEST(FileIO, FileShareMode_Read_Read) {
+  FileShareModeTest(ReadOrWrite::kRead, ReadOrWrite::kRead);
+}
+
+TEST(FileIO, FileShareMode_Read_Write) {
+  FileShareModeTest(ReadOrWrite::kRead, ReadOrWrite::kWrite);
+}
+
+TEST(FileIO, FileShareMode_Write_Read) {
+  FileShareModeTest(ReadOrWrite::kWrite, ReadOrWrite::kRead);
+}
+
+TEST(FileIO, FileShareMode_Write_Write) {
+  FileShareModeTest(ReadOrWrite::kWrite, ReadOrWrite::kWrite);
+}
+
+TEST(FileIO, MultipleSharedLocks) {
+  ScopedTempDir temp_dir;
+  base::FilePath shared_file =
+      temp_dir.path().Append(FILE_PATH_LITERAL("file_to_lock"));
+
+  {
+    // Create an empty file to lock.
+    ScopedFileHandle create(
+        LoggingOpenFileForWrite(shared_file,
+                                FileWriteMode::kCreateOrFail,
+                                FilePermissions::kOwnerOnly));
+  }
+
+  auto handle1 = ScopedFileHandle(LoggingOpenFileForRead(shared_file));
+  ASSERT_NE(handle1, kInvalidFileHandle);
+  EXPECT_TRUE(LoggingLockFile(handle1.get(), FileLocking::kShared));
+
+  auto handle2 = ScopedFileHandle(LoggingOpenFileForRead(shared_file));
+  ASSERT_NE(handle1, kInvalidFileHandle);
+  EXPECT_TRUE(LoggingLockFile(handle2.get(), FileLocking::kShared));
+
+  EXPECT_TRUE(LoggingUnlockFile(handle1.get()));
+  EXPECT_TRUE(LoggingUnlockFile(handle2.get()));
+}
+
+class LockingTestThread : public Thread {
+ public:
+  LockingTestThread()
+      : file_(), lock_type_(), iterations_(), actual_iterations_() {}
+
+  void Init(FileHandle file,
+            FileLocking lock_type,
+            int iterations,
+            base::subtle::Atomic32* actual_iterations) {
+    ASSERT_NE(file, kInvalidFileHandle);
+    file_ = ScopedFileHandle(file);
+    lock_type_ = lock_type;
+    iterations_ = iterations;
+    actual_iterations_ = actual_iterations;
+  }
+
+ private:
+  void ThreadMain() override {
+    for (int i = 0; i < iterations_; ++i) {
+      EXPECT_TRUE(LoggingLockFile(file_.get(), lock_type_));
+      base::subtle::NoBarrier_AtomicIncrement(actual_iterations_, 1);
+      EXPECT_TRUE(LoggingUnlockFile(file_.get()));
+    }
+  }
+
+  ScopedFileHandle file_;
+  FileLocking lock_type_;
+  int iterations_;
+  base::subtle::Atomic32* actual_iterations_;
+
+  DISALLOW_COPY_AND_ASSIGN(LockingTestThread);
+};
+
+void LockingTest(FileLocking main_lock, FileLocking other_locks) {
+  ScopedTempDir temp_dir;
+  base::FilePath shared_file =
+      temp_dir.path().Append(FILE_PATH_LITERAL("file_to_lock"));
+
+  {
+    // Create an empty file to lock.
+    ScopedFileHandle create(
+        LoggingOpenFileForWrite(shared_file,
+                                FileWriteMode::kCreateOrFail,
+                                FilePermissions::kOwnerOnly));
+  }
+
+  auto initial = ScopedFileHandle(
+      (main_lock == FileLocking::kShared)
+          ? LoggingOpenFileForRead(shared_file)
+          : LoggingOpenFileForWrite(shared_file,
+                                    FileWriteMode::kReuseOrCreate,
+                                    FilePermissions::kOwnerOnly));
+  ASSERT_NE(initial, kInvalidFileHandle);
+  ASSERT_TRUE(LoggingLockFile(initial.get(), main_lock));
+
+  base::subtle::Atomic32 actual_iterations = 0;
+
+  LockingTestThread threads[20];
+  int expected_iterations = 0;
+  for (size_t index = 0; index < arraysize(threads); ++index) {
+    int iterations_for_this_thread = static_cast<int>(index * 10);
+    threads[index].Init(
+        (other_locks == FileLocking::kShared)
+            ? LoggingOpenFileForRead(shared_file)
+            : LoggingOpenFileForWrite(shared_file,
+                                      FileWriteMode::kReuseOrCreate,
+                                      FilePermissions::kOwnerOnly),
+        other_locks,
+        iterations_for_this_thread,
+        &actual_iterations);
+    expected_iterations += iterations_for_this_thread;
+
+    ASSERT_NO_FATAL_FAILURE(threads[index].Start());
+  }
+
+  base::subtle::Atomic32 result =
+      base::subtle::Release_Load(&actual_iterations);
+  EXPECT_EQ(0, result);
+
+  ASSERT_TRUE(LoggingUnlockFile(initial.get()));
+
+  for (auto& t : threads)
+    t.Join();
+
+  result = base::subtle::Release_Load(&actual_iterations);
+  EXPECT_EQ(expected_iterations, result);
+}
+
+TEST(FileIO, ExclusiveVsExclusives) {
+  LockingTest(FileLocking::kExclusive, FileLocking::kExclusive);
+}
+
+TEST(FileIO, ExclusiveVsShareds) {
+  LockingTest(FileLocking::kExclusive, FileLocking::kShared);
+}
+
+TEST(FileIO, SharedVsExclusives) {
+  LockingTest(FileLocking::kShared, FileLocking::kExclusive);
+}
+
+}  // namespace
+}  // namespace test
+}  // namespace crashpad