无法获取Windows 7 C ++上虚拟文件夹的路径（与外壳名称空间扩展有关）

Question

By using Microsoft windows SDK 7.0, explorerDataProvider, I installed a virtual folder on windows 7.

When I open the file browse dialog from an application,

CFileDialog dlg(TRUE, NULL, 0, OFN_ENABLESIZING | OFN_ALLOWMULTISELECT, L"all(*.*)|*.*||", this);

INT_PTR result = dlg.DoModal();

if (result == IDOK)
{
   .
   . 
   .
   //some actions
}

it can also display the virtual folder:

But when I select the file, like "Zero" can then clicks "Open",

I tried to add breakpoints to

INT_PTR result = dlg.DoModal();

But it seems that this error happens inside DoModal() .

I doing some research and revise the code of virtual folder:

HRESULT CFolderViewImplFolder::GetAttributesOf(UINT cidl, PCUITEMID_CHILD_ARRAY apidl, ULONG *rgfInOut)
{
// If SFGAO_FILESYSTEM is returned, GetDisplayNameOf(SHGDN_FORPARSING) on that item MUST
// return a filesystem path.
HRESULT hr = E_INVALIDARG;

DWORD dwAttribs = 0;
dwAttribs |= SFGAO_BROWSABLE;
if (1 == cidl)
{
    int nLevel = 0;
    hr = _GetLevel(apidl[0], &nLevel);
    if (SUCCEEDED(hr))
    {
        BOOL fIsFolder = FALSE;
        hr = _GetFolderness(apidl[0], &fIsFolder);
        if (SUCCEEDED(hr))
        {

            if (fIsFolder)
            {
                dwAttribs |= SFGAO_FOLDER;

                dwAttribs |= SFGAO_FILESYSANCESTOR;
            }
            else
            {
                dwAttribs |= SFGAO_SYSTEM;

                dwAttribs |= SFGAO_FILESYSTEM;
            }

            if (nLevel < g_nMaxLevel)
            {
                dwAttribs |= SFGAO_HASSUBFOLDER;
            }
        }
    }
}

*rgfInOut &= dwAttribs;

return hr;
}

And return the path in GetDisplayNameOf()

HRESULT CFolderViewImplFolder::GetDisplayNameOf(PCUITEMID_CHILD pidl, SHGDNF shgdnFlags, STRRET *pName)
{
HRESULT hr = S_OK;
if (shgdnFlags & SHGDN_FORPARSING)
{
    WCHAR szDisplayName[MAX_PATH];
    if (shgdnFlags & SHGDN_INFOLDER)
    {
        // This form of the display name needs to be handled by ParseDisplayName.
        hr = _GetName(pidl, szDisplayName, ARRAYSIZE(szDisplayName));
    }
    else
    {
        PWSTR pszThisFolder = L"Computer\\Jerry";

            StringCchCopy(szDisplayName, ARRAYSIZE(szDisplayName), pszThisFolder);
            StringCchCat(szDisplayName, ARRAYSIZE(szDisplayName), L"\\");

            WCHAR szName[MAX_PATH];
            hr = _GetName(pidl, szName, ARRAYSIZE(szName));
            if (SUCCEEDED(hr))
            {
                StringCchCat(szDisplayName, ARRAYSIZE(szDisplayName), szName);
            }
    }
    if (SUCCEEDED(hr))
    {
        hr = StringToStrRet(szDisplayName, pName);
    }
}
else
{
    PWSTR pszName;
    hr = _GetName(pidl, &pszName);
    if (SUCCEEDED(hr))
    {
        hr = StringToStrRet(pszName, pName);
        CoTaskMemFree(pszName);
    }
}
return hr;
}

But it still stats error message of "Path does not exist" in the application. I add breakpoints in GetDisplayNameOf , but it is never triggered when the application opens a file browse dialog. But if I open a regular folder just by double click "Computer", it will be triggered.

The error message of "Path does not exist" seems cannot be deprecated or covered. Any way that I can revise the virtual folder to return the correct path ?

---

Update : I tried IFileDialog , I copied the code from the MSDN sample, code, and add breakpoints to see what will happen. However,

// Show the dialog
hr = pfd->Show(NULL);//the breakpoint is added here
if (SUCCEEDED(hr))
{
  // Obtain the result once the user clicks 
 // the 'Open' button.
 // The result is an IShellItem object.
 IShellItem *psiResult;
 hr = pfd->GetResult(&psiResult);
 if (SUCCEEDED(hr))
 {
   //do something
 }
}

When I click "Open" button, the error message box of "Path does not exist, check the path and try again" still show up. And it never comes out of pfd->Show(NULL) after I click Open" button.

Based on the comments in the sample code, it should come out of hr = pfd->Show(NULL); and reach to the next line.but the error message happens inside the hr = pfd->Show(NULL); .

Update :

In the IFileDialog , I tried

hr = pfd->GetOptions(&dwFlags);
            if (SUCCEEDED(hr))
            {

                hr = pfd->SetOptions(dwFlags | FOS_ALLNONSTORAGEITEMS);
                if (SUCCEEDED(hr))
                {
                    // Show the dialog
                    hr = pfd->Show(NULL);
                    if (SUCCEEDED(hr))
                    {
                        // Obtain the result once the user clicks 
                        // the 'Open' button.
                        // The result is an IShellItem object.
                        IShellItem *psiResult;
                        hr = pfd->GetResult(&psiResult);
                        if (SUCCEEDED(hr))
                        {
                            // We are just going to print out the 
                            // name of the file for sample sake.
                            PWSTR pszFilePath = NULL;
                            hr = psiResult->GetDisplayName(SIGDN_FILESYSPATH,
                                &pszFilePath);
                            if (SUCCEEDED(hr))
                            {
                                TaskDialog(NULL,
                                    NULL,
                                    L"CommonFileDialogApp",
                                    pszFilePath,
                                    NULL,
                                    TDCBF_OK_BUTTON,
                                    TD_INFORMATION_ICON,
                                    NULL);
                                CoTaskMemFree(pszFilePath);
                            }
                            psiResult->Release();
                        }
                    }

                }

I also tried

hr = pfd->SetOptions(dwFlags);//delete FOS_FORCEFILESYSTEM         

And tried

DWORD dwFlags = 0;
if (SUCCEEDED(hr))
{
    // overwrite options completely
    hr = pfd->SetOptions(dwFlags | FOS_ALLNONSTORAGEITEMS);

I also tried to return the whole name in namespace extension code:

WCHAR szDisplayName[MAX_PATH];
    if (shgdnFlags & SHGDN_INFOLDER)
    {
        // This form of the display name needs to be handled by ParseDisplayName.
        hr = _GetName(pidl, szDisplayName, ARRAYSIZE(szDisplayName));
    }
    else
    {
        PWSTR pszThisFolder;// = L"Computer\\Jerry";
        hr = SHGetNameFromIDList(m_pidl, (shgdnFlags & SHGDN_FORADDRESSBAR) ? SIGDN_DESKTOPABSOLUTEEDITING : SIGDN_DESKTOPABSOLUTEPARSING, &pszThisFolder);
        if (SUCCEEDED(hr))
        {
            StringCchCopy(szDisplayName, ARRAYSIZE(szDisplayName), pszThisFolder);
            StringCchCat(szDisplayName, ARRAYSIZE(szDisplayName), L"\\");

            WCHAR szName[MAX_PATH];
            hr = _GetName(pidl, szName, ARRAYSIZE(szName));
            if (SUCCEEDED(hr))
            {
                StringCchCat(szDisplayName, ARRAYSIZE(szDisplayName), szName);
            }
            CoTaskMemFree(pszThisFolder);
        }
    }
    if (SUCCEEDED(hr))
    {
        hr = StringToStrRet(szDisplayName, pName);
    }

But the result is:

Update :

hr = pfd->SetOptions(dwFlags | FOS_ALLNONSTORAGEITEMS | FOS_NOVALIDATE);

This works for me!!

Answer 1

With the help of @RemyLebeau, I did some tests in my code. Finally, I found the working solution for me: I copied the code from MSDN for IFileDialog : https://msdn.microsoft.com/en-us/library/windows/desktop/bb776913.aspx#file_types and then revise it a little bit:

HRESULT BasicFileOpen()
{
// CoCreate the File Open Dialog object.
IFileDialog *pfd = NULL;
HRESULT hr = CoCreateInstance(CLSID_FileOpenDialog,
    NULL,
    CLSCTX_INPROC_SERVER,
    IID_PPV_ARGS(&pfd));
if (SUCCEEDED(hr))
{
    // Create an event handling object, and hook it up to the dialog.
    IFileDialogEvents *pfde = NULL;
    hr = CDialogEventHandler_CreateInstance(IID_PPV_ARGS(&pfde));
    if (SUCCEEDED(hr))
    {
        // Hook up the event handler.
        DWORD dwCookie;
        hr = pfd->Advise(pfde, &dwCookie);
        if (SUCCEEDED(hr))
        {
            // Set the options on the dialog.
            DWORD dwFlags = 0;
            if (SUCCEEDED(hr))
            {
                // the default flag is FOS_PATHMUSTEXIST and FOS_FILEMUSTEXIST, so I set overwrite it with these two flags.
                hr = pfd->SetOptions(dwFlags | FOS_ALLNONSTORAGEITEMS | FOS_NOVALIDATE);
                if (SUCCEEDED(hr))
                {
                    // Show the dialog
                    hr = pfd->Show(NULL);
                    if (SUCCEEDED(hr))
                    {
                        // Obtain the result once the user clicks 
                        // the 'Open' button.
                        // The result is an IShellItem object.
                        IShellItem *psiResult;
                        hr = pfd->GetResult(&psiResult);
                        if (SUCCEEDED(hr))
                        {
                            // We are just going to print out the 
                            // name of the file for sample sake.
                            PWSTR pszFilePath = NULL;
                            hr = psiResult->GetDisplayName(SIGDN_FILESYSPATH,
                                &pszFilePath);
                            if (SUCCEEDED(hr))
                            {
                                TaskDialog(NULL,
                                    NULL,
                                    L"CommonFileDialogApp",
                                    pszFilePath,
                                    NULL,
                                    TDCBF_OK_BUTTON,
                                    TD_INFORMATION_ICON,
                                    NULL);
                                CoTaskMemFree(pszFilePath);
                            }
                            psiResult->Release();
                        }
                    }

                }
            }
            // Unhook the event handler.
            pfd->Unadvise(dwCookie);
        }
        pfde->Release();
    }
    pfd->Release();
}
return hr;
}

The key point is to overwrite the options by SetOptions . Based on the MSDN: https://msdn.microsoft.com/en-us/library/windows/desktop/dn457282(v=vs.85).aspx ,

FOS_PATHMUSTEXIST
The item returned must be in an existing folder. This is a default value.
FOS_FILEMUSTEXIST
The item returned must exist. This is a default value for the Open dialog.

These flags are default values which prevent it returns. So I set it to :

hr = pfd->SetOptions(dwFlags | FOS_ALLNONSTORAGEITEMS | FOS_NOVALIDATE);

These flags mean:

FOS_NOVALIDATE
Do not check for situations that would prevent an application from opening the selected file, such as sharing violations or access denied errors.

and

FOS_ALLNONSTORAGEITEMS
Enables the user to choose any item in the Shell namespace, not just those with SFGAO_STREAM or SFAGO_FILESYSTEM attributes. This flag cannot be combined with FOS_FORCEFILESYSTEM.

Then it finally works!