How to handle Symbolic Links and Junction while deleting or coping a folder tree - c++

Question

I had task to copy and delete a huge folder using win32 api (C++), I am using the Code Guru recurisive directory deletion code, which works well, but there arises certain question.
RemoveDirectory
Million thanks to Lerooooy Jenkins for pointing it.
The link to CodeGuru for recursive deletes doesn't correctly handle
symbolic links/junctions. Given that a reparse point could point
anywhere (even network drives), you need to be careful when deleting
recursively and only delete the symbolic link/junction and not what it
points at. The correct way to handle this situation is to detect
reparse points (via GetFileAttributes()) and NOT traverse it as a
subdirectory.
So my question is how to actually handle Symbolic Links and Junction while deleting or coping a folder tree.
For the shake of question here is the source code of CodeGuru Directory Deletion
#include <string>
#include <iostream>
#include <windows.h>
#include <conio.h>
int DeleteDirectory(const std::string &refcstrRootDirectory,
bool bDeleteSubdirectories = true)
{
bool bSubdirectory = false; // Flag, indicating whether
// subdirectories have been found
HANDLE hFile; // Handle to directory
std::string strFilePath; // Filepath
std::string strPattern; // Pattern
WIN32_FIND_DATA FileInformation; // File information
strPattern = refcstrRootDirectory + "\\*.*";
hFile = ::FindFirstFile(strPattern.c_str(), &FileInformation);
if(hFile != INVALID_HANDLE_VALUE)
{
do
{
if(FileInformation.cFileName[0] != '.')
{
strFilePath.erase();
strFilePath = refcstrRootDirectory + "\\" + FileInformation.cFileName;
if(FileInformation.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY)
{
if(bDeleteSubdirectories)
{
// Delete subdirectory
int iRC = DeleteDirectory(strFilePath, bDeleteSubdirectories);
if(iRC)
return iRC;
}
else
bSubdirectory = true;
}
else
{
// Set file attributes
if(::SetFileAttributes(strFilePath.c_str(),
FILE_ATTRIBUTE_NORMAL) == FALSE)
return ::GetLastError();
// Delete file
if(::DeleteFile(strFilePath.c_str()) == FALSE)
return ::GetLastError();
}
}
} while(::FindNextFile(hFile, &FileInformation) == TRUE);
// Close handle
::FindClose(hFile);
DWORD dwError = ::GetLastError();
if(dwError != ERROR_NO_MORE_FILES)
return dwError;
else
{
if(!bSubdirectory)
{
// Set directory attributes
if(::SetFileAttributes(refcstrRootDirectory.c_str(),
FILE_ATTRIBUTE_NORMAL) == FALSE)
return ::GetLastError();
// Delete directory
if(::RemoveDirectory(refcstrRootDirectory.c_str()) == FALSE)
return ::GetLastError();
}
}
}
return 0;
}
int main()
{
int iRC = 0;
std::string strDirectoryToDelete = "c:\\mydir";
// Delete 'c:\mydir' without deleting the subdirectories
iRC = DeleteDirectory(strDirectoryToDelete, false);
if(iRC)
{
std::cout << "Error " << iRC << std::endl;
return -1;
}
// Delete 'c:\mydir' and its subdirectories
iRC = DeleteDirectory(strDirectoryToDelete);
if(iRC)
{
std::cout << "Error " << iRC << std::endl;
return -1;
}
// Wait for keystroke
_getch();
return 0;
}

Answer 1

Use DeleteFile to delete file symbolic links.
Use RemoveDirectory to delete directory symbolic links and junctions.
In other words, you treat them just like any other file or directory except that you don't recurse into directories that have the FILE_ATTRIBUTE_REPARSE_POINT attribute.

Answer 2

The simplest way to achieve your goal, and the recommended way to do it, is to get the system to do the work.
If you need to support XP then you use SHFileOperation with the FO_DELETE flag.
Otherwise, for Vista and later, use IFileOperation.
These APIs handle all the details for you, and use the same code paths as does the shell. You can even show the standard shell progress UI if you desire.