Expose a function to get the path to a DLL.

chrome/installer/util/module_util_win.cc

+// Copyright (c) 2015 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 <windows.h>
+
+#include "chrome/installer/util/module_util_win.h"
+
+#include "base/file_version_info.h"
+#include "base/files/file.h"
+#include "base/logging.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/strings/utf_string_conversions.h"
+#include "base/version.h"
+
+namespace installer {
+
+namespace {
+
+// Returns the directory in which the currently running executable resides.
+base::FilePath GetExecutableDir() {
+  base::char16 path[MAX_PATH];
+  ::GetModuleFileNameW(nullptr, path, MAX_PATH);
+  return base::FilePath(path).DirName();
+}
+
+// Returns the version in the current module's version resource or the empty
+// string if none found.
+base::string16 GetCurrentModuleVersion() {
+  scoped_ptr<FileVersionInfo> file_version_info(
+      CREATE_FILE_VERSION_INFO_FOR_CURRENT_MODULE());
+  if (file_version_info.get()) {
+    base::string16 version_string(file_version_info->file_version());
+    if (Version(base::UTF16ToASCII(version_string)).IsValid())
+      return version_string;
+  }
+  return base::string16();
+}
+
+// Indicates whether a file can be opened using the same flags that
+// ::LoadLibrary() uses to open modules.
+bool ModuleCanBeRead(const base::FilePath file_path) {
+  return base::File(file_path, base::File::FLAG_OPEN | base::File::FLAG_READ)
+      .IsValid();
+}
+
+}  // namespace
+
+base::FilePath GetModulePath(const base::StringPiece16& module_name,
+                             base::string16* version) {
+  DCHECK(version);
+
+  base::FilePath module_dir = GetExecutableDir();
+  base::FilePath module = module_dir.Append(module_name);
+  if (ModuleCanBeRead(module))
+    return module;
+
+  base::string16 version_string(GetCurrentModuleVersion());
+  if (version_string.empty()) {
+    LOG(ERROR) << "No valid Chrome version found";
+    return base::FilePath();
+  }
+  *version = version_string;
+  return module_dir.Append(version_string).Append(module_name);
+}
+
+}  // namespace installer