March 2012 | The Old New Thing

How do I perform shell file operations while avoiding shell copy hooks?

Raymond ChenMarch 30, 2012Mar 30, 201203/30/12

Okay, the subject line of the article gives away the answer to the puzzle, but here's the puzzle anyway: A customer reported a problem with the SHFileOperation function: Consider the following program: If "a" is a file, then everything works fine, but if it's a directory, then Application Verifier raises the following error: Heap...

Why can't I delete a file immediately after terminating the process that has the file open?

Raymond ChenMarch 29, 2012Mar 29, 201203/29/12

A customer discovered a bug where terminating a process did not close the handles that the process had open, resulting in their emergency cleanup code not working: Their workaround was to insert a call to WaitForSingleObject(processHandle, 500) before deleting the file. The customer wanted to know whether they ...

Converting to Unicode usually involves, you know, some sort of conversion

Raymond ChenMarch 28, 2012Mar 28, 201203/28/12

A colleague was investigating a problem with a third party application and found an unusual window class name: L"整瑳整瑳". He remarked, "This looks quite odd and could be some problem with the application." The string is nonsense in Chinese, but I immediately recognized what was up. Here's a hint: Rewrite the ...

Amusing message on a whiteboard in the hallway

Raymond ChenMarch 27, 2012Mar 27, 201203/27/12

It is common to see whiteboards mounted in hallways. Sometimes they have official purposes; other times they are just placed for the convenience of hallway conversations or impromptu meetings. One of the hallways near my office has a very large whiteboard, completely blank, save for one note clearly written in the corner. DO NOT ERASE...

Why does a maximized window have the wrong window rectangle?

Raymond ChenMarch 26, 2012Mar 26, 201203/26/12

Commenter configurator wonders why the maximum size for a form is the screen size plus (12,12). Somebody else wonders why it's the screen size plus (16,16). Let's start by rewinding the clock to Windows 3.0. When you maximize a window, the default position of the window is such that all the resizing borders hang "off the edges of the ...

Beverage Gas Division of Central Welding Supply

Raymond ChenMarch 23, 2012Mar 23, 201203/23/12

The other day, I saw a van which was labeled Beverage Gas Division of Central Welding Supply. This odd juxtaposition was created by the acquisition of Compressed Gas Western by Central Welding Supply in 2009. I sure hope they don't get their tanks confused...

Why is the Heap32Next function incredibly slow on Windows 7?

Raymond ChenMarch 23, 2012Mar 23, 201203/23/12

A customer observed that the Heap32Function runs much slower on Windows 7 compared to previous versions of Windows. What happened? Set the wayback machine to 1992. The product is Windows 3.1. One of the new components available in Windows 3.1 went by the name TOOLHELP. It let you snoop around the low-level guts of the Windows&...

Why does my window style change when I call SetWindowText?

Raymond ChenMarch 22, 2012Mar 22, 201203/22/12

A customer observed some strange behavior with window styles: We ran some weird behavior: Calling the SetWindowText function causes a change in window styles. Specifically, calling SetWindowText results in the WM_STYLECHANGING and WM_STYLECHANGED messages, and sometimes the result is that the WS_TABSTOP ...

Isn't there a race condition in GetFileVersionInfoSize?

Raymond ChenMarch 21, 2012Mar 21, 201203/21/12

In response to my explanation of what the lpdwHandle parameter in GetFileVersionInfoSize is used for, Steve Nuchia wonders if there's a race condition between the time you get the size and the time you ask for the data. Yes, there is a race condition, but calling the function in a loop won't help because the GetFile...

In 1993, Microsoft stole my colleague's car

Raymond ChenMarch 20, 2012Mar 20, 201203/20/12

I remember walking between buildings at Microsoft back in the 1990's and seeing a moss-covered, rusted-out jalopy in one of the parking spaces. It clearly hadn't moved in ages. The person I was with said, "Oh, yeah, Microsoft owns that car. They stole it from Bob." (Bob is my generic name for a Microsoft employee.) The Inaugural Day Storm of...

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