The Old New Thing

August 2014 - The Old New Thing

How can I detect that a user's SID has changed and recover their old data?

August 29, 2014 Aug 29, 2014 08/29/14
Raymond Chen
A customer maintained a database which recorded information per user. The information in the database is keyed by the user's SID. This works out great most of the time, but there are cases in which a user's SID can change. "Wait, I thought SIDs don't change." While it's true that SIDs don't change, it is also true that the SID associated ...
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Taking advantage of the fact that the handle returned when you create a kernel synchronization object has full access regardless of the actual ACL

August 28, 2014 Aug 28, 2014 08/28/14
Raymond Chen
A customer wanted some help deciding what security attributes to placeon an event object intended to be used by multiple security contexts.We have two processes, call them A and B, running in differentsecurity contexts.I have an event that process A creates and shares with process B.The only thing process A does with the event is ...
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Where does the Installed Updates control panel get the install date from?

August 27, 2014 Aug 27, 2014 08/27/14
Raymond Chen
A corporate customer wanted to know where the Installed Updates control panel gets the Installed On information from, because they found that the values were always set to the current date regardless of when the update was actually installed. The algorithm goes roughly like this: First, ask MSI what date the update was installed by calling ...

It's time we face reality, my friends: We're not rocket scientists

August 26, 2014 Aug 26, 2014 08/26/14
Raymond Chen
During the development of Windows 95, it was common for team members to pay visits to other teams to touch base and let them know what's been happening on the Windows 95 side of the project. It was during one of these informal visits that the one of my colleagues reported that he saw that one of the members of the partner team had...

How do I read the "Double-click to open an item (single-click to select)" setting in Folder Options?

August 25, 2014 Aug 25, 2014 08/25/14
Raymond Chen
Today's Little Program reports whether theDouble-click to open an item (single-click to select)option is selected in the Folder Options dialog.A customer wanted to know how to do this,presumably so that their programwould respect the setting and adjust its user interfaceto match.The flag and member name is kind of weird.The ability...
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Dispelling the myths, rumors, and innuendo surrounding the QueryPerformanceCounter function

August 22, 2014 Aug 22, 2014 08/22/14
Raymond Chen
The Query­Performance­Counter function has been the subject of much rumor and innuendo. In response to all the confusion, the kernel folks put together a page which tries to settle the controversy once and for all. It discusses the history of QPC over the ages, the problems it had on earlier versions of Windows or older firmware (...
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Some reasons not to do anything scary in your DllMain, part 3

August 21, 2014 Aug 21, 2014 08/21/14
Raymond Chen
In the same week, the shell team was asked to investigate two failures. The first one was a deadlock in Explorer. The participating threads look like this: The shell extension caused this problem because it ignored the rule against calling shell and COM functions from the Dll­Main entry point, as specifically called out in the Dll­...
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If you're looking for the code that displays a particular dialog box, the most directly way to find it is to look for the dialog box

August 20, 2014 Aug 20, 2014 08/20/14
Raymond Chen
Suppose you are working in a large or unfamiliar code base and you want to know where the code is that displays a particular dialog box or message box or something. Probably the most direct way of figuring this out is to look for the strings. Say there is a message box that asks for user confirmation. "Are you sure you want to frobulate the ...

My friend and his buddy invented the online shopping cart back in 1994

August 19, 2014 Aug 19, 2014 08/19/14
Raymond Chen
Back in 1994 or so, my friend helped out his buddy who worked as the IT department for a local Seattle company known as Sub Pop Records. Here's what their Web site looked like back then. Oh, and in case you were wondering, when I said that his buddy worked as the IT department, I mean that the IT department consisted of one guy, namely him. ...