April 2007 | The Old New Thing

Everyone should have a house pianist

Raymond ChenApril 30, 2007Apr 30, 200704/30/07

Last year, a request was sent out to a social mailing list that went something like this: Hi, everybody. My girlfriend is coming to visit for a week, and she's a pianist. Does anybody have a piano they would be willing to let her practice on while she's here? I offered the piano in my living room and gave him the key to my house. I came ...

The default verb is not necessarily "open"

Raymond ChenApril 30, 2007Apr 30, 200704/30/07

If you hunt around the Internet you'll find lots of people† who hard-code the string "open" as the second parameter to the ShellExecute function, indicating that they want to open the document specified as the third parameter. While that's a nice thing to want to do, it might not be the right thing. When the user double-clicks a ...

News Flash: Not being able to watch Jay Leno is not an emergency

Raymond ChenApril 27, 2007Apr 27, 200704/27/07

The Mesa (Arizona) Police Department reminds us in a press release that 9-1-1 is for emergencies, and the inability to watch Jay Leno due to a power outage does not qualify as an emergency. (Noting, because everybody else will, that this is not the same as the unconfirmed of the woman who called 9-1-1 for a cheeseburger emergency.) Update...

Stupid debugger tricks: Calling functions and methods

Raymond ChenApril 27, 2007Apr 27, 200704/27/07

Back in the old days, if you wanted to call a function from inside the debugger, you had to do it by hand: Save the registers, push the parameters onto the stack (or into registers if the function uses fastcall or thiscall) push the address of the ntdll!DbgBreakPoint function, move the instruction pointer to the start of the function you want...

The intermediate value theory helps your table but not necessarily your beer

Raymond ChenApril 26, 2007Apr 26, 200704/26/07

An Australian mathematician applied intermediate value theory to the problem of keeping a table from wobbling: Just rotate the table and you'll eventually find a spot. A few things struck me about that article. First, that it explains that intermediate value theory "is the same principle underlying the fact that there will always be two ...

Using the "gu" debugger command to find the infinite loop

Raymond ChenApril 26, 2007Apr 26, 200704/26/07

Somebody says, "Your program is consuming 100% CPU" and hands you a debug session. Usually, this happens because one thread has gotten stuck in an infinite loop. And if you're lucky it's the type of infinite loop that's easy to diagnose because it's just one function that isn't returning. (The more complicated types are where a function does ...

There's something about Christopher Walken

Raymond ChenApril 25, 2007Apr 25, 200704/25/07

Actor Christopher Walken has such a peculiar speaking style, he's inspired a theater show: All About Walken. The run ends soon, so if you're going to see it, you'll have to act fast...

Identifying an object whose underlying DLL has been unloaded

Raymond ChenApril 25, 2007Apr 25, 200704/25/07

Okay, so I gave it away in the title, but follow along anyway. Your program chugs along and then suddenly it crashes like this: Instantly you recognize the following: This is a virtual method call. (Call indirect through register plus offset.) — Very high confidence. The vtable is in ecx. (That is the base register of...

How much time does it take for a pedestrian to cross the street?

Raymond ChenApril 24, 2007Apr 24, 200704/24/07

It sounds like the set-up to an old joke, but it's not. It's just one of the random bits of trivia that I wondered about. For intersections with both high pedestrian and high vehicle volumes, I was able to find the Federal Highway Administration recommendation, which is to give pedestrians a head start to allow them to cross one lane of ...

What is the underlying object behind a COM interface pointer?