Why does Internet Explorer not call DLL_PROCESS_DETACH on my DLL when I call ExitProcess?
A customer asked a question, but as is often the case, the question was much more telling than the answer.
We have an Internet Explorer plug-in which calls
ExitProcessto force Internet Explorer to exit. We found that when we do this, our plug-in does not receive a
DLL_PROCESS_DETACHnotification. What could be preventing our plug-in from receiving the
As we saw some time ago when we looked at
the way processes shut down
an important follow-up
all a process has to do to thwart proper delivery of
DLL_PROCESS_DETACH notifications is to do something
untoward during shutdown, at which point the kernel
just gives up and calls
But like I said, the answer is much less interesting than the question.
What if the user had an unsaved email message at the time you decided
to exit Internet Explorer?
plug-ins are a guest in the host process; don’t go changing the carpet.
When we asked the customer why they were exiting Internet Explorer from
their plug-in, we received the explanation,
“The reason I am calling
is that I do not know another good way to exit Internet Explorer
from a plug-in.”
In this case, the guest is doing far more than just changing the carpet. The guest called in a demolition company!
“Why did you call the demolition company to destroy my house?”
“I couldn’t think of a good way to destroy your house.”
The point isn’t that it’s bad to use a telephone call to hire a demolition company to destroy somebody’s house and that you should use some other method to contact them (like, say, a text message). The point is that it’s bad to destroy somebody else’s house in the first place.
Upon further investigation, the customer was writing a test for their plug-in. They open Internet Explorer and navigate to a page that uses the plug-in. When they are satisfied that the plug-in operated correctly, they want to exit the copy of Internet Explorer in order to conclude the test.
If you want to destroy a house, then destroy your own house.
to build a house,
navigate to your test page with
and when you’re done, you can destroy the house with
There is sample code to do exactly this in the documentation for
IWebBrowser2 interface is scriptable.
var ie = new ActiveXObject("InternetExplorer.Application"); ie.Visible = true; ie.Navigate("http://www.microsoft.com/"); WScript.Sleep(5000); // five seconds, say ie.Quit();