November 2015 | The Old New Thing

Enumerating all the programs that can open a particular file extension

Raymond Chen November 30, 2015 Nov 30, 2015 11/30/15

Today's Little Program enumerates all the applications which are registered for a particular file extension and lets the user choose one. We then open a file with that chosen program. As always, Little Programs do little to no error checking. The LoadHandlers function shows off the meat of the program: We use SHAssocEnum...

In order to serve you better: Charging your credit card in your home currency

Raymond Chen November 27, 2015 Nov 27, 2015 11/27/15

Dynamic currency conversion is a service provided by merchants when processing credit cards payable in a foreign currency. Say, for example, you present a credit card issued by a United States bank to a hotel in Ireland, where the Euro is the local currency. In order to serve you better, the hotel will convert the fee from Euros into dollars...

How can I append to a file and know where it got written, even if the file is being updated by multiple processes?

Raymond Chen November 27, 2015 Nov 27, 2015 11/27/15

A customer had a collection of processes, all of which are writing to a single file. Each process wants to append some data to a file and also know where the appended data was written, because the location of the appended record needed to be saved somewhere else. "We are currently using a named mutex derived from the path to the file. To add a...

The increasing urgency of a request to fill out a survey

Raymond Chen November 26, 2015 Nov 26, 2015 11/26/15

Here are some email messages I received from an automated system. October 20: "This survey must be completed no later than November 14." October 31: "Reminder, this survey must be completed no later than November 14." November 12: "Final reminder, this survey must be completed no later than November 14." November 14: "Extension, this ...

Clarifying the documentation on wildcards accepted by FindFirstFile/FindFirstFileEx

Raymond Chen November 25, 2015 Nov 25, 2015 11/25/15

A customer asked for clarification in the documentation for FindFirstFile and related functions, such as FindFirstFileEx and FindFirstFileTransacted Does FindFirstFileEx support multiple wildcards in the lpFileName parameter? The documentation is not clear. We are hoping to pass ...

We got around three

Raymond Chen November 24, 2015 Nov 24, 2015 11/24/15

In this story about Restoration Hardware's mail order extravagance, there is a little statistic: Industry surveys from groups like the Direct Marketing Association estimate that catalogues get average response rates of four to five per cent. That reminded me a story back from the days when Microsoft sold Fortran PowerStation, the development...

Playing with synchroninzation barriers

Raymond Chen November 23, 2015 Nov 23, 2015 11/23/15

A synchronization barrier is a synchronization object that works like this: A synchronization barrier knows how many threads it is managing. Each thread that calls EnterSynchronizationBarrier blocks. When the last thread enters the synchronization barrier, all threads are released. Once a thread exits the synchronization...

Investigating a problem constructing a security descriptor to deny thread-specific access rights to Everyone

Raymond Chen November 20, 2015 Nov 20, 2015 11/20/15

A customer had a question about how to set up a security access mask. How can I deny thread-specific access rights to Everyone? Specifically, I want to deny the Everyone group the following rights when I create a process: THREAD_SET_INFORMATION THREAD_SET_THREAD_TOKEN THREAD_TERMINATE PROCESS_CREATE_PROCESS PROCESS_SET_SESSIONID ...

Stupid JavaScript debugging tricks: Abusing the conditional breakpoint

Raymond Chen November 19, 2015 Nov 19, 2015 11/19/15

Your favorite JavaScript debugger may very well have a conditional breakpoint facility, and if it does, you can abuse it to do things unrelated to conditional breakpoints. Since conditional breakpoints are based on evaluating an expression, you can use an expression with side effects, like, say, logging. The console.log...

If You Are The One: The crazy Chinese dating show

Raymond Chen November 18, 2015 Nov 18, 2015 11/18/15

My wife watches 非誠勿擾, a Chinese dating game show. The title literally translates as "If not sincere, then do not bother", but that doesn't really convey what the title means. It follows in the Chinese tradition of the cryptic four-character phrase. The less cryptic version would be "If you are not sincere, then don'...

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