October 2015 | The Old New Thing

Why does the timestamp of a file increase by up to 2 seconds when I put it in a ZIP archive, then extract it?

Raymond ChenOctober 30, 2015Oct 30, 201510/30/15

We saw some time ago that the timestamp of a file increases by up to 2 seconds when you copy it to a USB thumb drive. The underlying reason is that USB thumb drives tend to be formatted with the FAT file system, and the FAT file system records timestamps in local time to only two-second resolution. The same logic applies to ZIP archives. The ...

When you open a securable object, make sure you pass the security mask you actually want (no more, no less)

Raymond ChenOctober 29, 2015Oct 29, 201510/29/15

There are two categories of "Access denied" errors. One occurs when you attempt to create the handle, and the other occurs when you attempt to use the handle. If this call fails with Access denied, then it means that you don't have access to the object to the level you requested. In the above example, it means that you don't have SYNCHRONIZE ...

How do I create a wizard that contains none of the things that makes a wizard a wizard?

Raymond ChenOctober 28, 2015Oct 28, 201510/28/15

A customer asked We're using the PropertySheet function to create a wizard. We've been able to remove almost all of the wizard elements, but we can't figure out how to get rid of the footer area. Is there a way to get rid of that? The customer included a picture of what they were talking about, with the offending area highlighted: Um...

The Redmond Reality Distortion Field: Analogies involving high-performance cars, usually Ferraris

Raymond ChenOctober 27, 2015Oct 27, 201510/27/15

At the announcement of Windows 10, Joe Belfiore remarked, We want all these Windows 7 users to have the sentiment that yesterday they were driving a first-generation Prius... and now with Windows 10 it's like a Tesla. Well, at least it's not a Ferrari. Inside the Redmond Reality Distortion Field, everybody loves to compare their project to ...

Are there any negative consequences to having a ton of files on the desktop?

Raymond ChenOctober 26, 2015Oct 26, 201510/26/15

I tend to be a bit sloppy with my desktop folder. How bad is it to have a ton of files on your desktop? One consequence of having a ton of files on your desktop is that you're slowing down logon, because Explorer has to load up all the icons for your desktop when it starts up. Mind you, you are staring at the spinning dots while all this is ...

CoGetInterfaceAndReleaseStream does not mix with smart pointers

Raymond ChenOctober 23, 2015Oct 23, 201510/23/15

One horrible gotcha of the CoGetInterfaceAndReleaseStream function is that it releases the stream. This is a holdover from the old days before smart pointers. The function released the stream to save you from having to call Release yourself. But nowadays, everybody is using smart pointers, so you never had to type ...

What are the rules for CoMarshalInterface and CoUnmarshalInterface?

Raymond ChenOctober 22, 2015Oct 22, 201510/22/15

Last time, we looked at the rules for CoMarshalInterThreadInterfaceInStream and CoGetInterfaceAndReleaseStream, the functions you use for sharing an object with another thread in the sample case where you there is only one other thread you want to share with, and you need to share it only ...

What are the rules for CoMarshalInterThreadInterfaceInStream and CoGetInterfaceAndReleaseStream?

Raymond ChenOctober 21, 2015Oct 21, 201510/21/15

Last time, we looked at the recommended ways of marshaling objects between apartments or between processes, but what if those mechanisms are not available to you? (Or if you're simply curious about the lower-level constructions that make the recommended ways possible.) How do I share an object in one apartment with another apartment in the ...

What is COM marshaling and how do I use it?

Raymond ChenOctober 20, 2015Oct 20, 201510/20/15

COM has this concept called "marshaling", with one L. Basically, marshaling is the mechanism by which an object that is accessible to one apartment can be made accessible to another apartment. Incomplete backgrounder on apartments: In COM, an apartment is a collection of threads that are treated as equivalent from a COM standpoint. The ...

How do I get the user-customized name of a mapped network drive?

Raymond ChenOctober 19, 2015Oct 19, 201510/19/15

Last time, we displayed the names of This PC and Recycle Bin. This time, we'll look at mapped volumes, because they are a little tricky. When you map a network drive, the name in Explorer defaults to something like sharename (\\server) (Z:). But you can right-click the label, select Rename, and change it to Awesome if you like. Let's try to ...

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