Copying behavior changes depending on file type and size

[nponsard]

Hello,

I am writing a custom file system driver in rust with dokan-rust. I have the latest version of Dokany installed on my computer.

When I try to copy a file to this drive, the behavior changes depending on the file type and size.

• pdf : windows explorer displays an error File too large
• jpg : Copying files over ~500kB works, with smaller files windows explorer displays a file too large error
• exe : works with any size

I noticed that the function called changes. When it will end up in an error, it doesn't call set_file_attributes after the write but directly calls delete_file.

My guess would be that I don't do the right thing in write_file or don't return the right informations in get_file_information.
But I can't seem to find what.

Has anyone experienced this ?

Thanks

[nponsard]

Oh I found the difference between files that work and files that don't, it's not related to type or size.

It doesn't work when the original file has this in the properties

[LTRData]

That attribute is stored as an alternate data stream to the file. Could it be that your GetVolumeInformation sets a flag indicating that you support named alternate data streams, but then have not implemented them correctly? As far as I know, when copying such files to file systems that do not support alternate data streams at all, such as FAT32, Windows simply ignores this information and just copies the main data stream of the file.

[nponsard]

Sorry for not updating this discussion. I found what I did wrong, I did not set the mount flag ALT_STREAM when mounting my file system. I thought the flag present meant that the filesystem supports alternate streams but apparently it's the inverse.