为什么我在递归删除目录时遇到问题？

Question

我编写了一个使用WIN32 api创建临时目录层次结构的应用程序.现在,当想要在关闭应用程序时删除目录时,我遇到了一些问题.

所以假设我有一个目录层次结构:C:\ temp\directory\subdirectory \

我正在使用这个递归函数:

bool Dir::deleteDirectory(std::string& directoryname, int flags)
{
    if(directoryname.at(directoryname.size()-1) !=  '\\') directoryname += '\\';

    if ((flags & CONTENTS) == CONTENTS)
    {
        WIN32_FIND_DATAA fdata;
        HANDLE dhandle;

        directoryname += "\\*";
        dhandle = FindFirstFileA(directoryname.c_str(), &fdata);

        // Loop through all the files in the main directory and delete files & make a list of directories
        while(true)
        {
            if(FindNextFileA(dhandle, &fdata))
            {
                std::string filename = fdata.cFileName;
                if(filename.compare("..") != 0)
                {
                    std::string filelocation = directoryname.substr(0, directoryname.size()-2) + StringManip::reverseSlashes(filename);

                    // If we've encountered a directory then recall this function for that specific folder.
                    if(!isDirectory(filelocation))  DeleteFileA(filename.c_str());
                    else deleteDirectory(filelocation, DIRECTORY_AND_CONTENTS);
                }
            } else if(GetLastError() == ERROR_NO_MORE_FILES)    break;
        }
        directoryname = directoryname.substr(0, directoryname.size()-2);
    }

    if ((flags & DIRECTORY) == DIRECTORY)
    {
        HANDLE DirectoryHandle;
        DirectoryHandle = CreateFileA(directoryname.c_str(),
                                FILE_LIST_DIRECTORY,
                                FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE,
                                NULL,
                                OPEN_EXISTING,
                                FILE_FLAG_BACKUP_SEMANTICS | FILE_FLAG_OVERLAPPED,
                                NULL);
        bool DeletionResult = (RemoveDirectoryA(directoryname.c_str()) != 0)?true:false;
        CloseHandle(DirectoryHandle);
        return DeletionResult;
    }

     return true;
}

该函数迭代临时目录的目录内容; 并且对于临时目录中的每个目录,它会一直调用自己,直到它位于最低目录; 示例中的子目录.

还定义了3个标志

 enum DirectoryDeletion
 {
    CONTENTS = 0x1,
    DIRECTORY = 0x2,
    DIRECTORY_AND_CONTENTS = (0x1 | 0x2)
 };

使用此函数时,它只删除最低的子目录,我无法删除层次结构中较高的子目录,因为它表示该目录不为空.当我去查看目录'子目录'时,仅在应用程序结束后删除.但是,当我尝试将其封装在非递归的简单主应用程序中时,我完全没有删除目录的问题.

Answer 1

有一个Windows API,SHFileOperation,它将为您执行递归文件夹删除.

LONG DeleteDirectoryAndAllSubfolders(LPCWSTR wzDirectory)
{
    WCHAR szDir[MAX_PATH+1];  // +1 for the double null terminate
    SHFILEOPSTRUCTW fos = {0};

    StringCchCopy(szDir, MAX_PATH, wzDirectory);
    int len = lstrlenW(szDir);
    szDir[len+1] = 0; // double null terminate for SHFileOperation

    // delete the folder and everything inside
    fos.wFunc = FO_DELETE;
    fos.pFrom = szDir;
    fos.fFlags = FOF_NO_UI;
    return SHFileOperation( &fos );
}

Answer 2

您没有从所有这些FindFirstFile调用中关闭dhandle ,因此当您尝试删除它时,每个目录都有对它的引用.

而且,你为什么需要创造DirectoryHandle？它不是必需的,也可能会阻止删除目录.

当你的应用程序关闭时,这些句柄被强制关闭,并且(我猜)最后一次尝试删除然后成功.

Answer 3

SHFileOperations在Windows 7上运行良好.事实上在IFileOperation文档中说

IFileOperation只能应用于单线程单元(STA)情况.它不能用于多线程公寓(MTA)情况.对于MTA,您仍然必须使用SHFileOperation.

但是我的SHFileOperations问题是它似乎不支持超过260个字符的路径,并且不支持长文件名的\？\前缀.

这真是一个痛苦......但是如果你想要处理超过260个字符的路径(NTFS支持的路径 - 但不是Windows资源管理器,命令提示命令等),仍然需要一个递归函数

Answer 4

好吧,我在这段代码中发现了几个错误..这就是我找到的

bool Dir::deleteDirectory(std::string& directoryname, int flags)
{
 if(directoryname.at(directoryname.size()-1) !=  '\\') directoryname += '\\';

 if ((flags & CONTENTS) == CONTENTS)
 {
  WIN32_FIND_DATAA fdata;
  HANDLE dhandle;
  //BUG 1: Adding a extra \ to the directory name..
  directoryname += "*";
  dhandle = FindFirstFileA(directoryname.c_str(), &fdata);
  //BUG 2: Not checking for invalid file handle return from FindFirstFileA
  if( dhandle != INVALID_HANDLE_VALUE )
  {
      // Loop through all the files in the main directory and delete files & make a list of directories
   while(true)
   {
    if(FindNextFileA(dhandle, &fdata))
    {
     std::string     filename = fdata.cFileName;
     if(filename.compare("..") != 0)
     {
      //BUG 3: caused by BUG 1 - Removing too many characters from string.. removing 1 instead of 2
      std::string filelocation = directoryname.substr(0, directoryname.size()-1) + filename;

      // If we've encountered a directory then recall this function for that specific folder.

      //BUG 4: not really a bug, but spurious function call - we know its a directory from FindData already, use it.
      if( (fdata.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY) == 0)  
       DeleteFileA(filelocation.c_str());
      else 
       deleteDirectory(filelocation, DIRECTORY_AND_CONTENTS);
     }
    } else if(GetLastError() == ERROR_NO_MORE_FILES)    break;
   }
   directoryname = directoryname.substr(0, directoryname.size()-2);
   //BUG 5: Not closing the FileFind with FindClose - OS keeps handles to directory open.  MAIN BUG
   FindClose( dhandle );
  }
 }
 if ((flags & DIRECTORY) == DIRECTORY)
 {
  HANDLE DirectoryHandle;
  DirectoryHandle = CreateFileA(directoryname.c_str(),
   FILE_LIST_DIRECTORY,
   FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE,
   NULL,
   OPEN_EXISTING,
   FILE_FLAG_BACKUP_SEMANTICS | FILE_FLAG_OVERLAPPED,
   NULL);
  //BUG 6: Not checking CreateFileA for invalid handle return.
  if( DirectoryHandle != INVALID_HANDLE_VALUE )
  {

   bool DeletionResult = (RemoveDirectoryA(directoryname.c_str()) != 0)?true:false;
   CloseHandle(DirectoryHandle);
   return DeletionResult;
  }
  else
  {
   return true;
  }
 }

 return true;
}