How can I enable my software to trigger cloud filter placeholder retrieval?

Question

How can I enable my software to trigger cloud filter placeholder retrieval?

sysadmin 40

I have a cloud filter provider which is running just fine, however I have noticed that if I programmatically traverse directories, the placeholders aren't fetched - it's only when doing it using explorer or command line.

Is there something I can do to make my software work like explorer? e.g. If I do a directory read of a folder, it should trigger the cloud filter API to actually retrieve the placeholders before returning

(Tagging you @Danny Nguyen (WICLOUD CORPORATION) because you are very knowledgeable about this subject)

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Danny Nguyen (WICLOUD CORPORATION) 5,065 Microsoft External Staff Moderator

Hi,

You don’t need any special API just to see those files. Normal directory traversal APIs do enumerate them.

For me, directory traversal should list all items the same as Explorer:

FindFirstFileW / FindNextFileW
- C++: std::filesystem::directory_iterator

If you’re not seeing some entries, check for Unicode issues (filenames with non‑ASCII chars; use wide APIs and std::wcout / WriteConsoleW).

I'm not sure I understand what you really want. Do you want to make your program make your program differentiate file types like how your explorer shows different status? If so, enumeration can give you names + attributes. You can interpret those attributes:

File attribute bits are documented here: File Attribute Constants
For Cloud Files specifically, you can use the CFAPI helper: CfGetPlaceholderStateFromAttributeTag → returns a CF_PLACEHOLDER_STATE.

I'm not sure if this is what you wanted though, let me know if you mean something else.

sysadmin 40 Reputation points

2025-12-03T23:28:24.74+00:00

I can see the files, but only after the cloud provider has retrieved the placeholders (my cloud provider is not set to "always full") - the issue is that if I programmatically traverse the directories, the fetch placeholders callback is not triggered

It seems there is special logic about things running from within C:/windows/system32/ triggering the placeholder fetching, whereas everything else will not - what I am wondering is if I can enable fetching the placeholders without being in C:/windows/system32/

e.g. if I put my software inside c:/windows/system32/ it works as I expect, if I run it from anywhere else it does not

Here is my issue on github https://github.com/microsoft/Windows-classic-samples/issues/399
Danny Nguyen (WICLOUD CORPORATION) 5,065 Reputation points Microsoft External Staff Moderator

2025-12-04T10:07:07.6+00:00

Have you tried opting in to Cloud Files placeholders using RtlSetProcessPlaceholderCompatibilityMode(PHCM_EXPOSE_PLACEHOLDERS) (or the thread variant) before calling FindFirstFileEx? That was mentioned in the stackoverflow post. That’s the documented way for a process outside %SystemRoot% to see the same placeholders/reparse points you’re seeing when you run from C:\Windows\System32.
sysadmin 40 Reputation points

2025-12-04T22:44:29.9833333+00:00

Yes, I tried that, the behavior does not change - the FindFirstFileEx call returns a cFileName with "." and no other files - the placeholders are never fetched...
sysadmin 40 Reputation points

2025-12-04T22:44:59.15+00:00

I think seeing the reparse points is not the same as being able to trigger placeholders to be fetched

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How can I enable my software to trigger cloud filter placeholder retrieval?

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