encrypted powerpoint and minifilter

Hi,
I implemented a minifilter driver that add headers to office files.
I hide the headers when the application read the file and play with the offsets.
My driver works fine but I have a problem with powerpoint 2007 when the files are encrypted (password protected).
The file open OK but when you save the file I get an error from power-point “There was an error accessing file 1.pptx”
This only happen 30% of file save. In other cases the file save finish correctly.
I know that the file is actually saved every time because if I close power-point (tell it not to save) and reopen the file the content is changed.

I tried to use procmon to see if some request failed but I didn’t see any failure that was not there when the error message doesn’t appear.

This doesn’t happen at all in other office applications.
Any idea?
Any idea how can I know what failed in power-point? What was the exact action that failed.

Regards,
Sagi

> The file open OK but when you save the file I get an error from

power-point “There was an error accessing file 1.pptx”

I tried to use procmon to see if some request failed but I didn’t see any
failure that was not there when the error message doesn’t >appear.

These are the worst bugs to track down. Unfortunately no one is likely to be
able to give you anything concrete to look for, the Office apps are complex
and there’s no way to tell you exactly what you’re doing wrong from your
description. I’ve had quite a few of these though so here are some things
that might help in your search:

  1. Process Monitor doesn’t show everything, so just because you’re not
    getting an error there doesn’t mean there isn’t one (had an issue once that
    was caused by ReadFileScatter which didn’t show up). I like to go to the
    trick outlined here under “Application X No Longer Works Properly” in those
    cases:

http://www.osronline.com/article.cfm?article=522

Sometimes that exposes something interesting.

  1. With the error dialog up, attach a debugger to the PowerPoint process and
    find the stack of the thread displaying the dialog (usually it’s pretty
    obvious). See if the stack tells you anything about the offending call
    chain, maybe there’s an obvious routine still on the stack that might give
    you a clue.

  2. Even if there are no errors, pay close attention to the *information*
    returned in the Process Monitor output. An incorrect size or attribute could
    cause a problem (just tracked down an issue with the Briefcase on Windows XP
    that was caused by not properly propagating the read only attribute).

Good luck! I definitely feel your pain.

-scott


Scott Noone
Consulting Associate
OSR Open Systems Resources, Inc.
http://www.osronline.com

wrote in message news:xxxxx@ntfsd…
> Hi,
> I implemented a minifilter driver that add headers to office files.
> I hide the headers when the application read the file and play with the
> offsets.
> My driver works fine but I have a problem with powerpoint 2007 when the
> files are encrypted (password protected).
> The file open OK but when you save the file I get an error from
> power-point “There was an error accessing file 1.pptx”
> This only happen 30% of file save. In other cases the file save finish
> correctly.
> I know that the file is actually saved every time because if I close
> power-point (tell it not to save) and reopen the file the content is
> changed.
>
> I tried to use procmon to see if some request failed but I didn’t see any
> failure that was not there when the error message doesn’t appear.
>
> This doesn’t happen at all in other office applications.
> Any idea?
> Any idea how can I know what failed in power-point? What was the exact
> action that failed.
>
> Regards,
> Sagi
>