When are global objects constructed and destructed by Visual C++?, redux

Raymond ChenSeptember 30, 2016Sep 30, 201609/30/16

Today we're going to make some clarifications to this table, which came from an earlier article: It turns out that the upper right corner of the diagram actually splits into two cases. The table lists what happens if the process terminates by calling Exit­Process. The thing that makes termination with Exit­Process interesting is that...

The lackey catastrophe

Raymond ChenSeptember 29, 2016Sep 29, 201609/29/16

We encountered a real problem with global object destruction in Explorer. The object in question was an RAII container for a graphics object, so its destructor destroyed the graphics object. But the call to destroy the object was crashing. What's going on? The call to Delete­Object was occurring after GDI32 had already run its ...

When can you free the memory backing the HSTRING you created with WindowsCreateStringReference?

Raymond ChenSeptember 28, 2016Sep 28, 201609/28/16

A little while back, I posted my complete guide to HSTRING semantics (a rip-off of Eric's complete guide to BSTR semantics). A discussion of security descriptor lifetime somehow triggered the question "When can you free the memory backing the HSTRING you created with Windows­Create­String­Reference?" You can free the memory ...

It says that I should use USB usage page 1 and usage 6 to get raw keyboard data, but what if I have a PS/2 keyboard?

Raymond ChenSeptember 26, 2016Sep 26, 201609/26/16

Some time ago, I wrote about raw input and noted that if you want to receive raw keyboard input, you set the usage page to 1 and the usage to 6, noting that these numbers come from the USB HID specification. Commenter onodera asks, "Does this work for PS/2 input devices as well?" Let's try it. I happen to have a laptop within easy reach, so I...

The case of the system() call that returned before finishing

Raymond ChenSeptember 21, 2016Sep 21, 201609/21/16

A customer was having trouble with some code that copies a bunch of files and then processes the copy. Here's the code they shared (suitably redacted): The customer reported that "It appears that Find­First­FileA does not wait for system() to finish copying the files. Here's a sample log file: "Observe that Find­First­FileA ...

It’s an unfortunate choice of data type for the file system redirection cookie

Raymond ChenSeptember 19, 2016Sep 19, 201609/19/16

If you want to disable 64-bit file system redirection, you call the Wow64­Disable­Wow64­Fs­Redirection function. This function gives you a cookie. When you are finished, you call Wow64­Revert­Wow64­Fs­Redirection, passing the cookie you received from the previous call. Like this: The unfortunate thing is that ...