November 2015 | The Old New Thing

Enumerating all the programs that can open a particular file extension

Raymond ChenNovember 30, 2015Nov 30, 201511/30/15

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 ChenNovember 27, 2015Nov 27, 201511/27/15

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 ChenNovember 27, 2015Nov 27, 201511/27/15

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 ChenNovember 26, 2015Nov 26, 201511/26/15

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 ChenNovember 25, 2015Nov 25, 201511/25/15

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 ChenNovember 24, 2015Nov 24, 201511/24/15

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 ChenNovember 23, 2015Nov 23, 201511/23/15

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 ChenNovember 20, 2015Nov 20, 201511/20/15

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 ChenNovember 19, 2015Nov 19, 201511/19/15

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 ChenNovember 18, 2015Nov 18, 201511/18/15

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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