November 2014 | The Old New Thing

A user's SID can change, so make sure to check the SID history

Raymond ChenNovember 28, 2014Nov 28, 201411/28/14

It doesn't happen often, but a user's SID can change. For example, when I started at Microsoft, my account was in the SYS-WIN4 domain, which is where all the people on the Windows 95 team were placed. At some point, that domain was retired, and my account moved to the REDMOND domain. We saw some time ago that the format of a user SID is...

Some light reading on lock-free programming

Raymond ChenNovember 27, 2014Nov 27, 201411/27/14

Today is a holiday in the United States, so I'm going to celebrate by referring you to other things to read. I'm going to start with a presentation by Bruce Dawson at GDC 2009, which is basically multiple instances of the question "Is this code correct?", and the answer is always "No!" Although the title of the talk is Lockless Programming in...

If 16-bit Windows had a single input queue, how did you debug applications on it?

Raymond ChenNovember 26, 2014Nov 26, 201411/26/14

After learning about the bad things that happened if you synchronized your application's input queue with its debugger, commenter kme wonders how debugging worked in 16-bit Windows, since 16-bit Windows didn't have asynchronous input? In 16-bit Windows, all applications shared the same input queue, which means you were permanently in the ...

What is the difference between Full Windows Touch Support and Limited Touch Support?

Raymond ChenNovember 25, 2014Nov 25, 201411/25/14

In the System control panel and in the PC Info section of the PC & Devices section of PC Settings, your device's pen and touch support can be reported in a variety of ways. Here is the matrix: The meaning of No touch and Single touch are clear, but if a device supports multiple touch points, what makes the system report it as having ...

The crazy world of stripping diacritics

Raymond ChenNovember 24, 2014Nov 24, 201411/24/14

Today's Little Program strips diacritics from a Unicode string. Why? Hey, I said that Little Programs require little to no motivation. It might come in handy in a spam filter, since it was popular, at least for a time, to put random accent marks on spam subject lines in order to sneak past keyword filters. (It doesn't seem to be popular any ...

Is it wrong to call SHFileOperation from a service? Revised

Raymond ChenNovember 21, 2014Nov 21, 201411/21/14

My initial reaction to this question was to say, "I don't know if I'd call it wrong, but I'd call it highly inadvisable." I'd like to revise my guidance. It's flat-out wrong, at least in the case where you call it while impersonating. The registry key HKEY_CURRENT_USER is bound to the current user at the time the key is first accessed by a...

A library loaded via LOAD_LIBRARY_AS_DATAFILE (or similar flags) doesn't get to play in any reindeer module games

Raymond ChenNovember 20, 2014Nov 20, 201411/20/14

If you load a library with the LOAD_LIBRARY_AS_DATAFILE flag, then it isn't really loaded in any normal sense. In fact, it's kept completely off the books. If you load a library with the LOAD_LIBRARY_AS_DATAFILE, LOAD_LIBRARY_AS_DATAFILE_EXCLUSIVE, or LOAD_LIBRARY_AS_IMAGE_RESOURCE flag (or any similar flag added in the future...

Distinguishing between normative and positive statements to help people answer your question

Raymond ChenNovember 19, 2014Nov 19, 201411/19/14

Often, we get questions from a customer that use the word should in an ambiguous way: Our program creates a widget whose flux capacitor should have reverse polarity. Attached is a sample program that shows how we create the widget with CreateWidget. However, the resulting widget still has a flux capacitor with standard polarity. Can you...

File version information does not appear in the property sheet for some files

Raymond ChenNovember 18, 2014Nov 18, 201411/18/14

A customer reported that file version information does not appear on the Details page of the property sheet which appears when you right-click the file and select Properties. They reported that the problem began in Windows 7. The reason that the file version information was not appearing is that the file's extension was .xyz. Older ...

How do I enumerate drives the same way that the NET USE command does?

Raymond ChenNovember 17, 2014Nov 17, 201411/17/14

If you use the Remote Desktop Connection client to connect to another computer, you have the option of making your local drives available to the remote computer. A customer wanted to know how to enumerate all the drives on the local machine. The were able to get the volumes mapped to drive letters, but they also wanted to get the ...

The Old New Thing