The Old New Thing
Practical development throughout the evolution of Windows.
Latest posts
Understanding the consequences of WAIT_ABANDONED
One of the important distinctions between mutexes and the other synchronization objects is that mutexes have owners. If the thread that owns a mutex exits without releasing the mutex, the mutex is automatically released on the thread's behalf. But if this happens, you're in big trouble. One thing many people gloss over is the WAIT_ABANDONED return value from the synchronization functions such as WaitForSingleObject. They typically treat this as a successful wait, because it does mean that the object was obtained, but it also tells you that the previous owner left the mutex abandoned and that the system had ...
Reading the output of a command from batch
The FOR command has become the batch language's looping construct. If you ask for help via FOR /? you can see all the ways it has become overloaded. For example, you can read the output of a command by using the for command. FOR /F "tokens=*" %i IN ('ver') DO echo %i The /F switch in conjunction with the single quotation marks indicates that the quoted string is a command to run, whose output is then to be parsed and returned in the specified variable (or variables). The option "tokens=*" says that the entire line should be collected. There are several other options that control the parsing, which I leave y...
I won’t be signing books but don’t let that stop you
Whereas Eric Carter will be signing his book (co-authored with another Eric) at the PDC. I have no book of my own to sign, but will be happy to sign the Erics' book if you ask me to! You can catch me in the Fundamentals Lounge pretty much the whole time. There have been some changes to my talk since I wrote about it last time. The lecture style is gone; the material simply didn't support it. It's just going to be a conventional talk against a series of slides. I sort of painted myself into a corner with my title, Five Things Every Win32 Developer Should Know: If you should know it, then it can't be all tha...
Why does the function WSASetLastError exist?
Why does the function exist when there is already the perfectly good function ? Actually, you know the answer too, if you sit down and think about it. Winsock was originally developed to run on both 16-bit Windows and 32-bit Windows. Notice how the classic Winsock functions are based on window messages for asynchronous notifications. In the 16-bit world, there was no function. Therefore, Winsock had to provide its own version for the 16-bit implementation. And since source code compatibility is important, there was a 32-bit version as well. Of course, the 32-bit version looks kind of stupid in retrospect...
Why aren’t low-level hooks injected?
When I described what the HINSTANCE parameter to the function is for, I neglected to mention why the low-level hooks are not injected. But then again, it should be obvious. The low-level hooks let you see input as it arrives at the window manager. At this low level of processing, the window manager hasn't yet decided what window will receive the message. After all, that's the whole point of the low-level hook: to filter the input before the window manager does anything with it. "Deciding what window should get the message" counts as "anything". Consequently, it can't inject the call into the destination wi...
Declared unsuitable for minors in Australia! Sort of.
A colleague of mine wrote to let me know Your blog is blocked as "adult content" in the internet cafe I'm currently using in Adelaide, South Australia. Other MSDN blogs show up without problem. You must have really have spiffed up the content since I left the states! Perhaps that should be my new subtitle. "The Old New Thing: Must be 18 or older to enter."
Windows Server 2003 can take you back in time
If you are running Windows Server 2003, you owe it to yourself to enable the Volume Shadow Copy service. What this service does is periodically (according to a schedule you set) capture a snapshot of the files you specify so they can be recovered later. The copies are lazy: If a file doesn't change between snapshots, a new copy isn't made. Up to 64 versions of a file can be recorded in the snapshot database. Bear this in mind when setting your snapshot schedule. If you take a snapshot twice a day, you're good for a month, but if you take a snapshot every minute, you get only an hour's worth of snapshots. You are...
Spider Solitaire unseats the reigning champion
A few months ago, the usability research team summarized some statistics they had been collecting on the subject of what people spend most of their time doing on the computer at home. Not surprisingly, surfing the Internet was number one. Number two was playing games, and in particular, I found it notable that the number one game is no longer Klondike Solitaire (known to most Windows users as just plain "Solitaire"). That title now belongs to Spider Solitaire. The top three games (Spider Solitaire, Klondike Solitaire, and Freecell) together account for more than half of all game-playing time. Personally, I'm...
Precision is not the same as accuracy
Accuracy is how close you are to the correct answer; precision is how much resolution you have for that answer. Suppose you ask me, "What time is it?" I look up at the sun, consider for a moment, and reply, "It is 10:35am and 22.131 seconds." I gave you a very precise answer, but not a very accurate one. Meanwhile, you look at your watch, one of those fashionable watches with notches only at 3, 6, 9 and 12. You furrow your brow briefly and decide, "It is around 10:05." Your answer is more accurate than mine, though less precise. Now let's apply that distinction to some of the time-related functions...