Add TempFileManager and tests

Bug: chromium:757625
Change-Id: I0f68e43c7f9700d3d02d640d36c2d9a4523b4495
Reviewed-on: https://chromium-review.googlesource.com/894167Reviewed-by: Zentaro Kavanagh <zentaro@chromium.org>
Commit-Queue: Allen Vicencio <allenvic@chromium.org>
Cr-Commit-Position: refs/heads/master@{#534811}

chrome/browser/chromeos/BUILD.gn

@@ -1512,6 +1512,8 @@ source_set("chromeos") {
     "smb_client/smb_service.h",
     "smb_client/smb_service_factory.cc",
     "smb_client/smb_service_factory.h",
+    "smb_client/temp_file_manager.cc",
+    "smb_client/temp_file_manager.h",
     "status/network_menu.cc",
     "status/network_menu.h",
     "system/automatic_reboot_manager.cc",
@@ -1980,6 +1982,7 @@ source_set("unit_tests") {
     "settings/shutdown_policy_handler_unittest.cc",
     "settings/stub_cros_settings_provider_unittest.cc",
     "smb_client/smb_service_unittest.cc",
+    "smb_client/temp_file_manager_unittest.cc",
     "system/automatic_reboot_manager_unittest.cc",
     "system/device_disabling_manager_unittest.cc",
     "system_logs/single_debug_daemon_log_source_unittest.cc",

chrome/browser/chromeos/smb_client/temp_file_manager.cc

+// Copyright 2017 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 "chrome/browser/chromeos/smb_client/temp_file_manager.h"
+
+#include <stdlib.h>
+#include <unistd.h>
+
+#include <memory>
+#include <string>
+#include <vector>
+
+#include "base/files/file_util.h"
+
+namespace chromeos {
+namespace smb_client {
+
+TempFileManager::TempFileManager() {
+  CHECK(temp_dir_.CreateUniqueTempDir());
+}
+
+TempFileManager::~TempFileManager() = default;
+
+const base::FilePath& TempFileManager::GetTempDirectoryPath() const {
+  return temp_dir_.GetPath();
+}
+
+base::ScopedFD TempFileManager::CreateTempFile(
+    const std::vector<uint8_t>& data) {
+  base::ScopedFD temp_fd = CreateTempFile();
+
+  // Write the data into the newly created file.
+  if (!base::WriteFileDescriptor(temp_fd.get(),
+                                 reinterpret_cast<const char*>(data.data()),
+                                 data.size())) {
+    LOG(ERROR) << "Error writing to temporary file";
+    temp_fd.reset();
+    return temp_fd;
+  }
+
+  // Seek the file descriptor to the start of the file in preparation for
+  // reading.
+  if (lseek(temp_fd.get(), 0, SEEK_SET) < 0) {
+    LOG(ERROR) << "Error seeking to beginning of temporary file";
+    temp_fd.reset();
+    return temp_fd;
+  }
+
+  return temp_fd;
+}
+
+base::ScopedFD TempFileManager::CreateTempFile() {
+  const std::string str = temp_dir_.GetPath().Append("XXXXXX").value();
+  // Make sure that the string we are passing is null-terminated.
+  std::unique_ptr<char[]> file_path = std::make_unique<char[]>(str.size() + 1);
+  memcpy(file_path.get(), str.c_str(), str.size());
+  file_path[str.size()] = '\0';
+
+  // mkstemp() modifies the passed in array.
+  base::ScopedFD temp_fd(HANDLE_EINTR(mkstemp(file_path.get())));
+  if (!temp_fd.is_valid()) {
+    LOG(ERROR) << "mkstemp failed to create a temporary file";
+    temp_fd.reset();
+    return temp_fd;
+  }
+
+  // Unlink causes the file to be deleted when the file descriptor is closed.
+  if (unlink(file_path.get()) != 0) {
+    LOG(ERROR) << "Failed to unlink temporary file: " << file_path.get();
+    temp_fd.reset();
+    return temp_fd;
+  }
+
+  return temp_fd;
+}
+
+}  // namespace smb_client
+}  // namespace chromeos

chrome/browser/chromeos/smb_client/temp_file_manager.h

+// Copyright 2017 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.
+
+#ifndef CHROME_BROWSER_CHROMEOS_SMB_CLIENT_TEMP_FILE_MANAGER_H_
+#define CHROME_BROWSER_CHROMEOS_SMB_CLIENT_TEMP_FILE_MANAGER_H_
+
+#include <vector>
+
+#include "base/files/file_path.h"
+#include "base/files/file_util.h"
+#include "base/files/scoped_temp_dir.h"
+
+namespace chromeos {
+namespace smb_client {
+
+// Helper class to handle construction and deletion of a temporary directory
+// containing temporary files.
+class TempFileManager {
+ public:
+  TempFileManager();
+  ~TempFileManager();
+
+  // Returns the path of the temporary directory.
+  const base::FilePath& GetTempDirectoryPath() const;
+
+  // Creates a temporary file in temp_dir_ path and writes in |data|. Before
+  // returning, this seeks to the beginning of the file in preparation for
+  // reading. This also calls unlink() on the created file. Returns a file
+  // descriptor which will be invalid on failure.
+  base::ScopedFD CreateTempFile(const std::vector<uint8_t>& data);
+
+ private:
+  // Creates a temporary file in temp_dir_ path. This also calls unlink() on the
+  // created file. Returns a file descriptor which will be invalid on failure.
+  base::ScopedFD CreateTempFile();
+
+  // Scoped class that handles deletion of the temporary directory.
+  base::ScopedTempDir temp_dir_;
+
+  DISALLOW_COPY_AND_ASSIGN(TempFileManager);
+};
+
+}  // namespace smb_client
+}  // namespace chromeos
+
+#endif  // CHROME_BROWSER_CHROMEOS_SMB_CLIENT_TEMP_FILE_MANAGER_H_

chrome/browser/chromeos/smb_client/temp_file_manager_unittest.cc

+// Copyright 2017 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 "chrome/browser/chromeos/smb_client/temp_file_manager.h"
+
+#include <string>
+#include <vector>
+
+#include "base/files/file_util.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace chromeos {
+namespace smb_client {
+
+namespace {
+
+// Helper method to get the current offset of a file descriptor |fd|. Returns
+// the offset from the beginning of the file.
+int64_t GetCurrentOffset(int32_t fd) {
+  return lseek(fd, 0, SEEK_CUR);
+}
+
+}  // namespace
+
+class TempFileManagerTest : public testing::Test {
+ public:
+  TempFileManagerTest() = default;
+  ~TempFileManagerTest() override = default;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(TempFileManagerTest);
+};
+
+// Should properly create a path when the object is created.
+TEST_F(TempFileManagerTest, ShouldCreatePath) {
+  TempFileManager file_manager;
+  const base::FilePath& path = file_manager.GetTempDirectoryPath();
+  EXPECT_FALSE(path.empty());
+  EXPECT_TRUE(base::PathExists(path));
+}
+
+// Path should be deleted after TempFileManager is cleaned up.
+TEST_F(TempFileManagerTest, PathShouldBeDeleted) {
+  std::string path;
+
+  {
+    TempFileManager file_manager;
+    path = file_manager.GetTempDirectoryPath().value();
+    EXPECT_TRUE(base::PathExists(base::FilePath(path)));
+  }
+
+  EXPECT_FALSE(base::PathExists(base::FilePath(path)));
+}
+
+// Should properly create a file with data and return a valid ScopedFD.
+TEST_F(TempFileManagerTest, ShouldCreateFile) {
+  std::vector<uint8_t> data = {0, 1, 2, 3, 4, 5, 6};
+  TempFileManager file_manager;
+  base::ScopedFD fd = file_manager.CreateTempFile(data);
+
+  EXPECT_TRUE(fd.is_valid());
+}
+
+// Should properly unlink directory path even if a file descriptor is open.
+TEST_F(TempFileManagerTest, FileShouldBeUnlinked) {
+  std::string path;
+
+  {
+    std::vector<uint8_t> data = {0, 1, 2, 3, 4, 5, 6};
+    TempFileManager file_manager;
+    path = file_manager.GetTempDirectoryPath().value();
+    base::ScopedFD fd = file_manager.CreateTempFile(data);
+  }
+
+  // Directory should be unlinked.
+  EXPECT_FALSE(base::PathExists(base::FilePath(path)));
+}
+
+// CreateFile should properly write the data into a file and seek back to the
+// beginning of the file.
+TEST_F(TempFileManagerTest, WriteFileSucceeds) {
+  std::vector<uint8_t> expected = {0, 1, 2, 3, 4, 5, 6};
+  TempFileManager file_manager;
+  base::ScopedFD fd = file_manager.CreateTempFile(expected);
+
+  // Expect the current offset to be at the beginning of the file.
+  EXPECT_EQ(0, GetCurrentOffset(fd.get()));
+
+  // Read back the data written and ensure that it is the same.
+  std::vector<uint8_t> actual(expected.size());
+  EXPECT_TRUE(base::ReadFromFD(fd.get(), reinterpret_cast<char*>(actual.data()),
+                               actual.size()));
+  EXPECT_EQ(expected, actual);
+}
+
+}  // namespace smb_client
+}  // namespace chromeos