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Misbehaving Shell Extension

Also by EldoS: CallbackRegistry
A component to monitor and control Windows registry access and create virtual registry keys.
#22805
Posted: 12/13/2012 21:32:59
by Kenny Kim (Standard support level)
Joined: 08/19/2009
Posts: 38

Hello.

I'm having problems with Overlay Icons when Virtual Disk is shared via Windows File Sharing.

Let me explain it detailly:

Virtual Disk X is mounted, and it is shared via Windows File Sharing Service.
The back-end server is a Linux system.

Other Windows Machine (XP or 7) is accessing the shared folder and copying "MyDoc.doc" to it.

The problem is appearing when a DRM (Digital Right Management) application is trying to draw its icon upon the existing icon of "MyDoc.doc" (like TortoiseSVN draws its icon when you create a repository).

The error is "An unhandled win32 exception occurred in explorer [PID]".
After the error, Explorer restarts. And if we browse to the shared folder we can see "MyDoc.doc" with the overlay icon (it was drawn anyway, even after the error).

And no exceptions are raising in my application.
I have no idea where to look in my code in order to find any clue to solve the issue.

Temporarily, I have solved the problem by disabling the DRM's shell extension.

By the way, the Mapper sample has no such issues with the DRM.
That's why I am sure that my code implementation is causing such weird behavior of DRM's Shell Extension.

Please, help.
#22806
Posted: 12/14/2012 00:20:39
by Eugene Mayevski (EldoS Corp.)

I would suggest you to contact DRM application's vendor and ask them to check why their extension crashes. There's nothing we could do on our site. It can be that you are handling some request incorrectly or not handling it, but this is what only DRM stuff authors can tell you.


Sincerely yours
Eugene Mayevski
#22807
Posted: 12/14/2012 00:34:05
by Kenny Kim (Standard support level)
Joined: 08/19/2009
Posts: 38

Thank you.

I'm aware that I'm handling some request incorrectly.
And I am not being able to locate the source of the bug by myself.

That's why I was wondering, if somebody could give me some idea about which callback's incorrect handling could result to such behavior.
Or which callback was somehow connected to icons.
#22808
Posted: 12/14/2012 00:42:46
by Volodymyr Zinin (EldoS Corp.)

Try to use Process Monitor from sysinternals.com. Mark in the menu "Filter"->"Enable advanced output" and maybe set some filter rules (like "Path"->"begins with"->"X:" and/or "Process name"->"is"->"Explorer.exe"). Then reproduce the problem and see what the latest requests were made by Explorer.
#22810
Posted: 12/14/2012 01:57:17
by Kenny Kim (Standard support level)
Joined: 08/19/2009
Posts: 38

I did as you said.

I have uploaded Process Monitor log files to the link below:
https://docs.google.com/open?id=0BzdZgHTTgVsyTzNuYUtXMFVZQ28

There are 4 logs:
1. Mapper Log with Shell Extension Enabled.
2. Mapper Log with Shell Extension Disabled.
3. MyDisk Log with Shell Extension Enabled.
4. MyDisk Log with Shell Extension Disabled.

The logs start from File Paste Operation until it finishes.

Thank you.
#22811
Posted: 12/14/2012 02:45:50
by Volodymyr Zinin (EldoS Corp.)

Seems, something is wrong with your OnRead callback. Perhaps you returned BytesRead less than requested.
#22813
Posted: 12/14/2012 03:13:18
by Kenny Kim (Standard support level)
Joined: 08/19/2009
Posts: 38

Quote
Vladimir Zinin wrote:
Seems, something is wrong with your OnRead callback. Perhaps you returned BytesRead less than requested.


Thank you a lot.

Indeed, BytesRead and BytesToRead values were not equal.

Now, at least, I know where the problem is.
Also by EldoS: CallbackFilter
A component to monitor and control disk activity, track file and directory operations (create, read, write, rename etc.), alter file data, encrypt files, create virtual files.

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