I have an ActiveX control that is delivered as a CAB. I have an HTML page that is just an OBJECT tag with the cab name and clsid (so nothing else on the page yet).
This causes IE to ask about installing the ActiveX control, which I allow. It downloads the CAB, extracts the installer and starts to run it.
While MSIEXEC is running and trying to install the control, IE decides to delete the files in the temp directory where the .MSI file is. Sometimes, the file is locked by the process and deleting fails and then installing succeeds, but most of the time deleting succeeds and then MSIEXEC logs an error that the MSI file isn’t there.
I can see all of this happening in PROCMON, but I have no idea why. It is reproducible in multiple versions of Windows and IE. It’s not just deleting the MSI — it’s deleting the files in the temp directory.
The only clue I have is that the modified date of the file is the date it was created on the build machine. This isn’t something that I can keep updating though (it’s inside of a CAB on a webserver) — I can’t just build this CAB every five minutes to keep the modified dates fresh — so, I don’t think that’s it, but wanted to mention it as a clue.
Why is IE deleting the files in the temp and is there any way to stop it from doing that?
Finally figured this out. If you have a hook in your CAB to start apps, they must not return back to the caller until they exit. Console apps do this by default — GUI apps do not.
Our installer is a normal setup.exe GUI inside the CAB — so it returns immediately to IE right after it starts running. IE then starts cleaning up the temp files of the CAB.
We made a console app that takes a command-line argument for a system call to make and then doesn’t exit until the process started by the system call exits. This stops IE from cleaning up until the setup.exe is completely done.