修改 7-Zip 的文件夹选择对话框

2025-05-30

背景

7-Zip 在解压文件时使用的是旧版的文件夹选择对话框 SHBrowseForFolder ，需要逐级展开树状目录，使用起来不是很好。于是就想在不改动 7-Zip 源程序的情况下，把对话框给换成现代的 IFileDialog 。

以 7-Zip 24.09 源码为例。结构初始化部分的代码在 CPP\Windows\Shell.cpp#666 附近，整理后大概如下：

bool BrowseForFolder(LPBROWSEINFO browseInfo, CSysString &resultPath)
{
  resultPath.Empty();
  NWindows::NCOM::CComInitializer comInitializer;
  LPITEMIDLIST itemIDList = ::SHBrowseForFolder(browseInfo);
  if (!itemIDList) return false;
  CItemIDList itemIDListHolder;
  itemIDListHolder.Attach(itemIDList);
  return GetPathFromIDList(itemIDList, resultPath);
}

static int CALLBACK BrowseCallbackProc(HWND hwnd, UINT uMsg, LPARAM /* lp */, LPARAM data)
{
  switch (uMsg)
  {
    case BFFM_INITIALIZED:
    {
      SendMessage(hwnd, BFFM_SETSELECTION, TRUE, data);
      break;
    }
    default:
      break;
  }
  return 0;
}

static bool BrowseForFolder(HWND owner, LPCTSTR title, UINT ulFlags, LPCTSTR initialFolder, CSysString &resultPath)
{
  CSysString displayName;
  BROWSEINFO browseInfo;
  browseInfo.hwndOwner = owner;
  browseInfo.pidlRoot = NULL;
  browseInfo.pszDisplayName = displayName.GetBuf(MAX_PATH);
  browseInfo.lpszTitle = title;
  browseInfo.ulFlags = ulFlags;
  browseInfo.lpfn = initialFolder ? BrowseCallbackProc : NULL;
  browseInfo.lParam = (LPARAM)initialFolder;
  return BrowseForFolder(&browseInfo, resultPath);
}

除了要把 SHBrowseForFolder detour 掉以外，还需要检查下 bi 的回调函数，如果存在的话说明 bi.lParam 里放了当前文件夹的路径。

DLL Proxy ：不可行

7z 的提取文件对话框由 7zG.exe 提供，检查了下导入表，发现都是 known dll ，没有什么操作空间。

COMCTL32.dll
comdlg32.dll
GDI32.dll
OLEAUT32.dll
ole32.dll
USER32.dll
ADVAPI32.dll
SHELL32.dll
msvcrt.dll
KERNEL32.dll

7z 插件方法：可行

7zG 会尝试从其目录下的 Codecs 和 Formats 下加载 dll 。（如果要 patch 7zFM 则麻烦些，因为它只在打开压缩文件时，才会去加载插件。）因此尝试写一个 dll 去 detour 一下。

static LPITEMIDLIST(WINAPI *Original_SHBrowseForFolderW)(LPBROWSEINFOW lpbi) =
    SHBrowseForFolderW;

LPITEMIDLIST WINAPI Detoured_SHBrowseForFolderW(LPBROWSEINFOW lpbi) {
  MessageBoxW(NULL, L"Hello", L"World", 0);
  return Original_SHBrowseForFolderW(lpbi);
}

BOOL APIENTRY DllMain(HMODULE hModule, DWORD ul_reason_for_call,
                      LPVOID lpReserved) {
  if (DetourIsHelperProcess()) {
    return TRUE;
  }

  switch (ul_reason_for_call) {
  case DLL_PROCESS_ATTACH:
    DetourRestoreAfterWith();
    DetourTransactionBegin();
    DetourUpdateThread(GetCurrentThread());
    DetourAttach(&(PVOID &)Original_SHBrowseForFolderW,
                 (PVOID)Detoured_SHBrowseForFolderW);
    DetourTransactionCommit();
    break;
  }
  return TRUE;
}

编译运行，报 access violation 退出了。仔细一看， 7z 如果发现插件 dll 里没有可用的 codec/format 就会主动卸载 dll 。因此在 dll 加载时，我们手动 pin 一下自己，防止被卸载。

完整代码如下：

#define WIN32_LEAN_AND_MEAN
#define UNICODE
#define _UNICODE
// clang-format off
#include <windows.h>
#include <detours.h>
#include <shlobj_core.h>
#include <comdef.h>
#include <pathcch.h>
#include <stdexcept>
// clang-format on

// mini unsafe com wrapper
template <typename T>
struct com_ptr {
  T *ptr_{nullptr};

  com_ptr() = default;

  ~com_ptr() {
    if (ptr_) {
      ptr_->Release();
    }
  }

  T *get() const { return ptr_; }

  T *operator->() { return ptr_; }

  T **operator&() { return &ptr_; }
};

inline void check_hr(HRESULT hr) {
  if (FAILED(hr)) {
    _com_error err(hr);
#ifndef NDEBUG
    MessageBoxW(NULL, err.ErrorMessage(), L"Unexpected error",
                MB_ICONERROR | MB_OK);
#endif
    throw std::runtime_error("unexpected error");
  }
}

static LPITEMIDLIST(WINAPI *Original_SHBrowseForFolderW)(LPBROWSEINFOW lpbi) =
    SHBrowseForFolderW;

bool TryGetAvailableFolder(LPCWSTR pszPath, IShellItem **ppsi) {
  WCHAR szPath[MAX_PATH];
  wcscpy_s(szPath, MAX_PATH, pszPath);

  // try to parse current path
  auto hr = SHCreateItemFromParsingName(szPath, NULL, IID_PPV_ARGS(ppsi));
  if (SUCCEEDED(hr)) {
    return true;
  }

  // try to remove trailing backslash
  PathCchRemoveBackslash(szPath, MAX_PATH);

  // try to get the parent folder
  hr = PathCchRemoveFileSpec(szPath, MAX_PATH);
  if (FAILED(hr)) {
    return false;
  }
  hr = SHCreateItemFromParsingName(szPath, NULL, IID_PPV_ARGS(ppsi));
  if (SUCCEEDED(hr)) {
    return true;
  }

  return false;
}

LPITEMIDLIST ModernFolderDialog(LPBROWSEINFOW lpbi) {
  com_ptr<IFileDialog> pfd;
  check_hr(CoCreateInstance(CLSID_FileOpenDialog, NULL, CLSCTX_INPROC_SERVER,
                            IID_PPV_ARGS(&pfd)));

  DWORD dwFlags;
  check_hr(pfd->GetOptions(&dwFlags));
  dwFlags |= FOS_PICKFOLDERS | FOS_FORCEFILESYSTEM;
  check_hr(pfd->SetOptions(dwFlags));

  check_hr(pfd->SetTitle(lpbi->lpszTitle));

  if (lpbi->lpfn) {
    // lParam is LPCWSTR initialFolder
    com_ptr<IShellItem> psiFolder;
    if (TryGetAvailableFolder((LPCWSTR)lpbi->lParam, &psiFolder)) {
      check_hr(pfd->SetFolder(psiFolder.get()));
    }
  }

  auto hr = pfd->Show(lpbi->hwndOwner);
  if (hr == HRESULT_FROM_WIN32(ERROR_CANCELLED)) {
    return NULL;
  }
  check_hr(hr);

  com_ptr<IShellItem> psi;
  check_hr(pfd->GetResult(&psi));

  LPITEMIDLIST pidl = NULL;
  check_hr(SHGetIDListFromObject(psi.get(), &pidl));

  return pidl;
}

LPITEMIDLIST WINAPI Detoured_SHBrowseForFolderW(LPBROWSEINFOW lpbi) {
  try {
    return ModernFolderDialog(lpbi);
  } catch (...) {
    return Original_SHBrowseForFolderW(lpbi);
  }
}

BOOL APIENTRY DllMain(HMODULE hModule, DWORD ul_reason_for_call,
                      LPVOID lpReserved) {
  if (DetourIsHelperProcess()) {
    return TRUE;
  }

  switch (ul_reason_for_call) {
  case DLL_PROCESS_ATTACH:
    // avoid 7zip unloading the DLL
    WCHAR moduleName[MAX_PATH];
    GetModuleFileNameW(hModule, moduleName, MAX_PATH);
    HMODULE hModuleTmp;
    GetModuleHandleExW(GET_MODULE_HANDLE_EX_FLAG_PIN, moduleName,
                       &hModuleTmp);

    DetourRestoreAfterWith();
    DetourTransactionBegin();
    DetourUpdateThread(GetCurrentThread());
    DetourAttach(&(PVOID &)Original_SHBrowseForFolderW,
                 (PVOID)Detoured_SHBrowseForFolderW);
    DetourTransactionCommit();
    break;
  }
  return TRUE;
}