The Old New Thing

Issues related to forcing a stub to be created for an imported function

July 25, 2006 Jul 25, 2006 07/25/06

Raymond Chen

I noted last time that you can concoct situations that force the creation of a stub for an imported function. For example, if you declare a global function pointer variable: then the C compiler is forced to generate the stub and assign the address of the stub to the variable. That's the best it can do, since the loader will patch up only...

How a less naive compiler calls an imported function

July 24, 2006 Jul 24, 2006 07/24/06

Raymond Chen

If a function is declared with the declaration specifier, this instructs the Visual Studio C/C++ compiler that the function in question is an imported function rather than a normal function with external linkage. With this additional information, the compiler generates slightly different code when it needs to reference an imported function, ...

Calling an imported function, the naive way

July 21, 2006 Jul 21, 2006 07/21/06

Raymond Chen

An import library resolves symbols for imported functions, but it isn't consulted until the link phase. Let's consider a naive implementation where the compiler is blissfully unaware of the existence of imported functions. In the 16-bit world, this caused no difficulty at all. The compiler generated a far call instruction and left an external...

Rethinking the way DLL exports are resolved for 32-bit Windows

July 20, 2006 Jul 20, 2006 07/20/06

Raymond Chen

Over the past few days we've learned how 16-bit Windows exported and imported functions from DLLs and that the way functions are exported from 32-bit DLLs matches the 16-bit method reasonably well. But the 16-bit way functions are imported simply doesn't work in the 32-bit world. Recall that in 16-bit Windows, the fixups for an imported ...

Exported functions that are really forwarders

July 19, 2006 Jul 19, 2006 07/19/06

Raymond Chen

Last time, we saw how the way Win32 exports functions is pretty much the same as the way 16-bit Windows exports functions, but with a change in emphasis from ordinal-based exports to name-based exports. This change in emphasis is not expressed anywhere in the file format; both 16-bit and 32-bit DLLs can export either by name or by ordinal (...

How are DLL functions exported in 32-bit Windows?

July 18, 2006 Jul 18, 2006 07/18/06

Raymond Chen

The designers of 32-bit Windows didn't have to worry quite so much about squeezing everything into 256KB of memory. Since modules in Win32 are based on demand-paging, all you have to do is map the entire image into memory and then run around accessing the parts you need. There is no distinction between resident and non-resident names; the ...

Glass houses are great places to throw stones

July 13, 2006 Jul 13, 2006 07/13/06

Raymond Chen

Whenever I write an article explaining that programs should avoid doing X, I can confidently rely on a comment saying, "Well, Microsoft Product Q does this!" as if to say, "Gotcha, you hypocrite!" But they're saying "gotcha" to the wrong person. Because, and I'm sure it's a shock to many people to read this, I did not ...

Pidls and monikers do roughly the same thing, just backwards

July 12, 2006 Jul 12, 2006 07/12/06

Raymond Chen

When operating with the Windows shell, you will almost certainly find yourself at some point working with a pointer to an item ID list, known also as a "pidl" (rhymes with "middle"). On the other hand, when working with OLE you may find yourself having do deal with monikers. In a sense, they both do the same thing. They let you refer to some ...

Not everybody with a non-Windows partition type is a geek

July 11, 2006 Jul 11, 2006 07/11/06

Raymond Chen

In the discussions following why Windows setup lays down a new boot sector, some commenters suggested that Windows setup could detect the presence of a non-Windows partition as a sign that the machine onto which the operating system is being installed belongs to a geek. In that way, the typical consumer would be spared from having to deal ...

Look who bought my name

June 26, 2006 Jun 26, 2006 06/26/06

Raymond Chen

Commenter Pavel Vozenilek noticed that if you type my name into Google, there is only one sponsored link, and it's from Google themselves, inviting you to apply for a job there. (Maybe I should sue. Perhaps I can get a settlement.) When I mentioned this to some other people at Microsoft, they started hunting around to see what sort of ...