DeleteOnClose vs FILE_FLAG_DELETE_ON_CLOSE about dokany

[Liryna]

@suy "FILE_FLAG_DELETE_ON_CLOSE in the dwFlagsAndAttributes parameter of CreateFile. Dokan doesn't support that out of the box, but there are easy to work around."
If I remember Dokan already give you the information during CreateFile.

dokany/dokan/create.c

Line 98 in 8b7742f

if (options & FILE_DELETE_ON_CLOSE) {

This Windows 10 (= 8.1) sample give us a over view of the officiel behaviour for detecting the delete file operation.
https://github.com/Microsoft/Windows-driver-samples/tree/master/filesys/miniFilter/delete

It monitors IRP_MJ_CREATE requests for the FILE_DELETE_ON_CLOSE flag. Also, it detects IRP_MJ_SET_INFORMATION requests for setting FileDispositionInformation. The sample also illustrates how to handle racing deletes (in the form of multiple parallel IRP_MJ_SET_INFORMATION operations), and how to distinguish deletion of an entire file from deletion of just one stream of the file.

I also think that it is the application that should keep a information to handle automaticaly the delete on close.

Maybe we even should remove the flag during CloseFile for the < 8 Windows version to have a "standard" behaviour ?

[suy]

Removing the DeleteOnClose flag would be a source and binary incompatible change with old applications. That's why I was thinking of using it instead (either setting it in the application or the library/driver). That might be able to "upgrade" old applications that weren't aware of the flag, although you probably will know better if this is safe.

If you think it's the application's duty to do so, I'll implement it in mine, and update the docs.

One question remains, though: how comes that Microsoft introduced this safely? Isn't it breaking all other file system drivers as well?

[Liryna]

You are right. Remove the flag would break compatibility.

I have look how to add the flag during close event on Win > 8.
DeleteOnClose is set from the EventContext information:

dokany/dokan/dokan.c

Line 448 in 741198c

DokanFileInfo->DeleteOnClose = 1;

The EvenContext come from DeviceIoControl (dokan driver).

dokany/dokan/dokan.c

Line 291 in 741198c

status = DeviceIoControl(

I guess Windows break the compatibility :D or the officiel behaviour never was to check delete on close.

The EvenContext is a new instance for every IO call. Thats why it is impossible to store the DeleteOnClose inside.

We should find a way to store it in a clean way inside the DokanLoop

[Liryna]

Added with 770d2a7 from BenjaminKim/dokanx#45

The logic is different and more simple 😄 and it work ! 👍

Thanks @marinkobabic

[suy]

It took me some time to be able to test, but so far, yes, this seems to work. :-) Thank you!

I don't understand, though, what would change the other parts of the change that Marinko did. I see the DeleteFile operation being called before the cleanup anyway.