Finding where a symbolic link points to (Windows) - c++

Question

I use FindFirstFile() and co-functions to browse the contents of C:\example\dir. I know that a file read can be a symbolic link, a junction, etc by checking whether d.dwAttributes & FILE_ATTRIBUTE_REPARSE_POINT != 0. However, I haven't found a way to follow the link and see the location it is pointing to. Is that even possible?

Answer 1

To find the target of a symbolic link, you have to open the symbolic link. The object manager dereferences the link and returns a handle to the target location. Calling GetFinalPathNameByHandle on that handle returns the pathname of the target.
The following implementation returns the target location, given a symbolic link:
std::wstring GetLinkTarget( const std::wstring& a_Link ) {
// Define smart pointer type for automatic HANDLE cleanup.
typedef std::unique_ptr<std::remove_pointer<HANDLE>::type,
decltype( &::CloseHandle )> FileHandle;
// Open file for querying only (no read/write access).
FileHandle h( ::CreateFileW( a_Link.c_str(), 0,
FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE,
nullptr, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, nullptr ),
&::CloseHandle );
if ( h.get() == INVALID_HANDLE_VALUE ) {
h.release();
throw std::runtime_error( "CreateFileW() failed." );
}
const size_t requiredSize = ::GetFinalPathNameByHandleW( h.get(), nullptr, 0,
FILE_NAME_NORMALIZED );
if ( requiredSize == 0 ) {
throw std::runtime_error( "GetFinalPathNameByHandleW() failed." );
}
std::vector<wchar_t> buffer( requiredSize );
::GetFinalPathNameByHandleW( h.get(), buffer.data(),
static_cast<DWORD>( buffer.size() ),
FILE_NAME_NORMALIZED );
return std::wstring( buffer.begin(), buffer.end() - 1 );
}
Note: For details about the RAII wrapper based on std::unique_ptr see std::unique_ptr, deleters and the Win32 API.