The Old New Thing

History - The Old New Thing

Why do member functions need to be "static" to be used as a callback?

January 9, 2004 Jan 9, 2004 01/9/04
Raymond Chen
As we learned yesterday, nonstatic member functions take a secret "this" parameter, which makes them incompatible with the function signature required by Win32 callbacks. Fortunately, nearly all callbacks provide some way of providing context. You can shove the "this" pointer into the context so you can reconstruct the source object. Here's ...

The history of calling conventions, part 3

January 8, 2004 Jan 8, 2004 01/8/04
Raymond Chen
Okay, here we go: The 32-bit x86 calling conventions. (By the way, in case people didn't get it: I'm only talking in the context of calling conventions you're likely to encounter when doing Windows programming or which are used by Microsoft compilers. I do not intend to cover calling conventions for other operating systems or that are specific...

The history of calling conventions, part 2

January 7, 2004 Jan 7, 2004 01/7/04
Raymond Chen
Foreshadowing: This information will actually be useful in a future discussion. Well, not the fine details, but you may notice something that explains... um... it's hard to describe. Just wait for it. Curiously, it is only the 8086 and x86 platforms that have multiple calling conventions. All the others have only one! Now we're going deep ...

The history of calling conventions, part 1

January 2, 2004 Jan 2, 2004 01/2/04
Raymond Chen
The great thing about calling conventions on the x86 platform is that there are so many to choose from! In the 16-bit world, part of the calling convention was fixed by the instruction set: The BP register defaults to the SS selector, whereas the other registers default to the DS selector. So the BP register was necessarily the register used ...

Why not just block the apps that rely on undocumented behavior?

December 24, 2003 Dec 24, 2003 12/24/03
Raymond Chen
Because every app that gets blocked is another reason for people not to upgrade to the next version of Windows. Look at all these programs that would have stopped working when you upgraded from Windows 3.0 to Windows 3.1. Actually, this list is only partial. Many times, the compatibility fix is made inside the core component for all programs...

When programs grovel into undocumented structures…

December 23, 2003 Dec 23, 2003 12/23/03
Raymond Chen
Three examples off the top of my head of the consequences of grovelling into and relying on undocumented structures. Defragmenting things that can't be defragmented In Windows 2000, there are several categories of things that cannot be defragmented. Directories, exclusively-opened files, the MFT, the pagefile... That didn't stop a certain ...

Sometimes, an app just wants to crash

December 19, 2003 Dec 19, 2003 12/19/03
Raymond Chen
I think it was Internet Explorer 5.0, when we discovered that a thirdparty browser extension had a serious bug, the details of which aren't important. The point was that this bug was so vicious, it crashed IE pretty frequently. Not good. To protect the users from this horrible fate, we marked the object as "bad" so IE wouldn't load it. And ...

The unsafe device removal dialog

December 16, 2003 Dec 16, 2003 12/16/03
Raymond Chen
In a comment, somebody asked what the deal was with the unsafe device removal dialog in Windows 2000 and why it's gone in Windows XP. I wasn't involved with that dialog, but here's what I remember: The device was indeed removed unsafely. If it was a USB storage device, for example, there may have been unflushed I/O buffers. If it were a ...