February 2018 | The Old New Thing

An amusing story about a practical use of the null garbage collector

Raymond ChenFebruary 28, 2018Feb 28, 201802/28/18

Some time ago, I noted that the null garbage collector is a valid garbage collector if the amount of RAM available to the runtime is greater than the total memory requirements of the program. This insight lets us make some statements about what you can assume from garbage-collected languages. But it also can be looked at as rules for deciding...

It rather involved being on the other side of this airtight hatchway: Replacing an unsigned writable MSI package

Raymond ChenFebruary 27, 2018Feb 27, 201802/27/18

In the category of dubious security vulnerability, we have this report: I have found a security vulnerability in Windows that permits an attacker to run arbitrary code on a remote system. Prepare the system as follows: Given these starting conditions, the attacker can do the following: Okay, let's see what we have here. First, we ...

The 2018/2019 Seattle Symphony subscription season at a glance

Raymond ChenFebruary 23, 2018Feb 23, 201802/23/18

For many years, I've put together a little pocket guide to the Seattle Symphony subscription season for my symphony friends to help them decide which ticket package they want. At some point, we may start subscribing again, but for now, we pick-and-choose individual concerts. Here's the at-a-glance season guide for the 2018/2019 season, still ...

How do I make sure that my shell extension is at the top of the context menu?

Raymond ChenFebruary 23, 2018Feb 23, 201802/23/18

A customer wanted the items for their context menu shell extension to appear at the very top of the context menu. They did this by ignoring the recommended insertion point passed to the IContextMenu::QueryContextMenu function and just inserting their items at the top anyway: However, they found that this didn't work. Their ...

Why does IsPathRelative return FALSE for paths that are drive-relative?

Raymond ChenFebruary 22, 2018Feb 22, 201802/22/18

MSDN distinguishes between fully-qualified and relative paths. According to that discussion: A file name is relative to the current directory if it does not begin with one of the following: If a file name begins with only a disk designator but not the backslash after the colon, it is interpreted as a relative path to the current ...

How can I call freopen but open the file with shared access instead of exclusive access?

Raymond ChenFebruary 21, 2018Feb 21, 201802/21/18

A customer wants to redirect their program's stdout to a file. They followed the sample code which basically boils down to the line or its security-enhanced alternate version: The customer reported that this worked exactly as exepcted, but the output file is opened for exclusive access. They want another process to be able to read from the ...

We couldn’t create a new partition or locate an existing one, possible workarounds

Raymond ChenFebruary 20, 2018Feb 20, 201802/20/18

One of the consequences of being part of the Windows Insiders program is that occasionally you run into a bug so bad that your system doesn't boot. Fortunately, the kernel team was able to diagnose the problem on my machine and develop a fix. The fix was too late for me, but at least it will be useful to others. In the meantime, I had to ...

This is a race the display driver wouldn’t normally expect to lose

Raymond ChenFebruary 19, 2018Feb 19, 201802/19/18

One of my colleagues from the Windows 95 project reminded me of a problem that I was called to debug. If the floppy drive was in use, the display driver was more likely to crash. It wound up being a race condition between the floppy driver and the display driver. This is a race the display driver wouldn't normally expect to lose. The problem...

So what is a Windows “critical process” anyway?

Raymond ChenFebruary 16, 2018Feb 16, 201802/16/18

I noted some time ago that Task Manager applies three somewhat arbitrary criteria for dividing processes into three categories: App, Background Process, and Windows Process. In particular, a Windows Process is one for which IsProcessCritical reports TRUE. SimonRev quite rightly calls out the documentation for being useless due to ...

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