The Old New Thing

August 2006 - Page 2 of 4 - The Old New Thing

Environment variable expansion occurs when the command is read

August 23, 2006 Aug 23, 2006 08/23/06
Raymond Chen
On the command line (and in batch files), environment variable expansion occurs when the command is read. This sounds obvious at first, but it has its own consequences. In the online documentation for SET, one such consequence is spelled out: would never display the message, since the %VAR% in both "if" statements is substituted when the...
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Raymond's excursions into East Asian pop music, episode 2: China Dolls (中國娃娃)

August 22, 2006 Aug 22, 2006 08/22/06
Raymond Chen
The wife of one of my colleagues took a trip through the Far East as part of her work. One of the things she did was buy a bunch of music CDs from the various countries she visited. But not just any CDs. To decide which ones to get, she used a very scientific method that didn't require knowing how to read or speak the local language: She would...

Who says there's only one? There can be more than one logon session

August 22, 2006 Aug 22, 2006 08/22/06
Raymond Chen
An extension of the "What if two programs did this?" thought experiment is the "Who says there's only one?" question. A common question I see is, "From a service, how do I do X with the currently logged-on user?" (Where "X" can be a variety of things such as interact with them or impersonate them.) But who says that there's only one? With ...
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[6] days since last monorail breakdown

August 21, 2006 Aug 21, 2006 08/21/06
Raymond Chen
It's soon going to come to the point where this is no longer news. The Seattle monorail broke down again, just six days since the previous breakdown, which was in turn just two days after operations resumed. I think they need to put up a big sign at the Monorail station at Seattle Center that reads 6 days since last breakdown. Well...

Sucking the exception pointers out of a stack trace

August 21, 2006 Aug 21, 2006 08/21/06
Raymond Chen
Often, you find yourself staring at a stack trace for a caught exception and want to see the original exception. (You too can get symbols for operating system binaries, either by using the symbol server to get the symbols on-demand or, if you have a gigabyte of disk space, you can download symbol packages to get them all at one go. Even ...
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Applications and DLLs don't have privileges; users do

August 18, 2006 Aug 18, 2006 08/18/06
Raymond Chen
I can't believe you people are actually asking for backdoors. If an end user can do it, then so can a bad guy. In response to the requirement that all drivers on 64-bit Windows be signed, one commenter suggested adding a backdoor that permits unsigned drivers, using some "obscure registry key". Before somebody can jump up and shouts "...

A modest proposal: On allowing mobile phones on airplanes

August 17, 2006 Aug 17, 2006 08/17/06
Raymond Chen
Ever since the FAA decided to reconsider its ban on the use of cellular phones on airplanes during flight, there has been quite a reaction over whether this is a good thing. To resolve this issue, I present this modest proposal. Remember back in the days when smoking was permitted on airplanes? When you bought a ticket, you were asked ...

Don't trust the return address, no really

August 17, 2006 Aug 17, 2006 08/17/06
Raymond Chen
In the discussion of how to prevent non-"trusted" DLLs from using private OS resources, more than one person suggested having the LoadLibrary or FindResource function behave differently depending on who the caller is. But we already saw that you can't trust the return address and that you definitely shouldn't use the return address to make ...
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Computer monitors float, screen upwards

August 16, 2006 Aug 16, 2006 08/16/06
Raymond Chen
Oceanographer Curtis Ebbesmeyer made another appearance on my local public radio station. Among the ocean garbage trivia is the fact that computer monitors float screen upwards (timecode 4:00). Other fascinating facts...