Chromium 加载chrome.dll过程分析c++

chrome.exe加载同级版本号目录-》chrome.exe和chrome.dll同级目录。

一、优先从chrome.exe同级版本号目录下加载

例如：chrome.exe [版本号:129.0.6668.101] 从129.0.6668.101\chrome.dll下加载

发布版大多数都是以此种办法，主要是方便升级时候，防止不同版本号chrome.exe加载错误的chrome.dll。 

二、 chrome.exe和chrome.dll在同目录直接加载。

三、看下代码逻辑：

   F:\code\google\src\chrome\app\main_dll_loader_win.cc

// Returns the full path to |module_name|. Both dev builds (where |module_name|
// is in the current executable's directory) and proper installs (where
// |module_name| is in a versioned sub-directory of the current executable's
// directory) are supported. The identified file is not guaranteed to exist.
base::FilePath GetModulePath(std::wstring_view module_name) {
  base::FilePath exe_dir;
  const bool has_path = base::PathService::Get(base::DIR_EXE, &exe_dir);
  DCHECK(has_path);

  // Look for the module in a versioned sub-directory of the current
  // executable's directory and return the path if it can be read. This is the
  // expected location of modules for proper installs.
  const base::FilePath module_path =
      exe_dir.AppendASCII(chrome::kChromeVersion).Append(module_name);
  if (ModuleCanBeRead(module_path))
    return module_path;

  // Othwerwise, return the path to the module in the current executable's
  // directory. This is the expected location of modules for dev builds.
  return exe_dir.Append(module_name);
}

 1、 在base::FilePath GetModulePath(std::wstring_view module_name)函数中优先获取chrome.exe所在路径：F:\code\google\src\out\Debug

2、版本号目录F:\code\google\src\out\Debug\122.0.6224.0\chrome.dll

3、如果122.0.6224.0\chrome.dll目录下没有crome.dll直接返回F:\code\google\src\out\Debug

4、最终结果是加载F:\code\google\src\out\Debug\chrome.dll

// Prefetches and loads |module| after setting the CWD to |module|'s
// directory. Returns a handle to the loaded module on success, or nullptr on
// failure.
HMODULE LoadModuleWithDirectory(const base::FilePath& module,
                                const base::CommandLine& cmd_line) {
  ::SetCurrentDirectoryW(module.DirName().value().c_str());
  if (!cmd_line.HasSwitch(switches::kNoPreReadMainDll)) {
    base::PreReadFile(module, /*is_executable=*/true);
  }
  HMODULE handle = ::LoadLibraryExW(module.value().c_str(), nullptr,
                                    LOAD_WITH_ALTERED_SEARCH_PATH);
  return handle;
}

// Prefetches and loads the appropriate DLL for the process type
// |process_type_|. Populates |module| with the path of the loaded DLL.
// Returns a handle to the loaded DLL, or nullptr on failure.
HMODULE Load(base::FilePath* module, const base::CommandLine& cmd_line) {
  *module = GetModulePath(installer::kChromeDll);
  if (module->empty()) {
    PLOG(ERROR) << "Cannot find module " << installer::kChromeDll;
    return nullptr;
  }
  HMODULE dll = LoadModuleWithDirectory(*module, cmd_line);
  if (!dll)
    PLOG(ERROR) << "Failed to load Chrome DLL from " << module->value();
  return dll;
}

总结：end