The Old New Thing
Practical development throughout the evolution of Windows.
Latest posts
File version information does not appear in the property sheet for some files
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 . Older versions of Windows attempted to extract file version information for all files regardless of type. I believe it was Windows Vista that changed this behavior and extracted version information only for known file types for Win32 modules, specifically , , , , , and . If the file's ex...
How do I enumerate drives the same way that the NET USE command does?
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 redirected drives injected by Terminal Services. (Mind you, these aren't volumes that are assigned drive letters, so it's not clear why they are interested in them, but whatever.) With the command, they see the Terminal Services volumes in Explorer, and they can be browsed via : ...
How to view the stack of a user-mode thread when its kernel stack has been paged out
Suppose you have a machine that has crashed, and your investigation shows that the reason is that there is a critical section that everybody is waiting for. While waiting for that critical section, work piles up, and eventually the machine keels over. Suppose further that this crash is given to you in the form of a kernel debugger. In case it wasn't obvious, by "you" I mean "me". Okay, so the critical section that is the cause of the logjam is this one: "Great," you say. "I just need to look at thread 0x4228 to see why it is stuck. Woo-hoo, there's the thread. Now I just need to switch to its context ...
When does GetTickCount consider the system to have started?
The and functions return "the number of milliseconds that have elapsed since the system was started." (The 32-bit version wraps around after around 50 days.) But when exactly is the system considered to have started? Is it when power is applied to the computer? When the BIOS completes POST? When the user picks the operating system from the boot menu? When the kernel switches to protected mode? It isn't defined exactly when the timer starts. Because that's not its purpose. The purpose of is to let you measure intervals of time. It provides a common clock source so that multiple components can coordinate their...
How can I wait until all startup applications have finished launching?
A customer wanted to know how to detect that all startup applications have finished launching. They wanted to wait until everything settled down before proceeding with some task. What if two programs did this? Suppose two programs both wanted to detect that all startup applications have finished launching. Each one would sit there waiting for the other, because this is one of those I want to be the last to do something, even laster than the other guy who wants to do something last things. If you want to wait until the system is idle to perform some task, you can use the Task Scheduler to create an idle-time t...
A little cheat in my Tiger Beat photo homage
One thing nobody has called out in my tribute to the Bill Gates Tiger Beat photo, either because it was too subtle or too obvious, is that the photo is actually a mirror image. The arrangement of furniture in the room was not correct: The big table was on the wrong side of the room. It was also too heavy to move around, so we cheated. We staged the entire picture as a mirror image, flipping the Windows screen shot. And then back in the virtual darkroom, Ariel flipped the photo to put the furniture on the correct side of the photo. Here are the clues in the photo: Chatter: The day after I put this article in...
Kicking around a function that formats stuff
Today's "Little Program" is really a "Little Puzzle" that got out of hand. This started out as a practical question: This code fragment screams out for some sort of simplification. (I've changed the names of the classes.) Clearly, the pattern is Everything here is pretty straightforward, except for the part. Can we write a function that takes a and formats it in a somewhat flexible manner? Let's start with the -and- cases. We might try something like this: But then we'd run into trouble, because there is no constraint on , so the compiler will complain, "I don't know how to get a or a from an ."...
Why does an attempt to create a SysLink control in my plug-in sometimes fail?
A customer had written a plug-in for some application, and they found that their plug-in was unable to create a SysLink control via the function. The same code in a standalone application works fine, but when the code is placed in their plug-in, the code fails. Debugging showed that the call to succeeded, but the call failed with "Cannot find window class." The customer is another victim of not keeping their eye on the activation context. They attached a manifest to their DLL so that the call to maps to the version of the common controls library that supports the SysLink control. But they did nothing to e...
Raymond, why did you stop studying Chinese? It has no grammar!
It does; you just don't realize it.