Exclude offline files broken with OneDrive?

[drwtsn32]

Ok, well this is interesting. It seems to be a feature of Windows. It will filter out some attributes so they aren’t visible to certain applications.

See this for more info:

RtlSetProcessPlaceholderCompatibilityMode function (ntifs.h) - Windows drivers

Relevant section:

When placeholders are exposed, characteristics such as the presence of a reparse point, the sparse bit, and the offline bit are plainly visible through directory enumeration and other types of file information queries. When placeholders are disguised, these details are completely hidden, making the file look like a normal file.

Most Windows applications see exposed placeholders by default. For compatibility reasons, Windows may decide that certain applications see disguised placeholders by default.

The good news is it is possible to override this filtering. Here’s a demonstration of the filtering and then overriding it:

Click to expand to make it easier to read…here’s a summary:

1. First test (line 2) uses PowerShell natively. Value returned is 0x501620

2. Second test (line 4) uses a custom C# program to call that same GetAttributes method. Value returned is 0x500020. 0x1000 (Offline), 0x400 (Reparse Point), and 0x200 (Sparse File) are filtered out. Duplicati also experiences this same filtering.

3. Third test (line 7) uses another custom C# program to show current “Placeholder Compatibility Mode” and the file attributes it sees. It then changes the Compatibility mode to PHCM_EXPOSE_PLACEHOLDERS per the MS link above and tests attributes again. You can see the filtering is turned off and the program now sees the Offline, Reparse, and Sparse attributes.

All I think we need to do in Duplicati is implement this same adjustment so it can see the true file attributes.