1)
What function(s) do I use to toggle the "Better performance (default)" "Enable write caching" and "Turn off Windows write-cache buffer flushing" storage device options? I want to make a program that automatically disables them when the UPS battery is low and enables them again when it is no longer low.

2)
What function(s) do I use to directly read from the screen, in userland? There are a lot of APIs for taking screenshots and stuff, but the only ones I've found are really inconsistent; e.g. they don't work with certain full screen 3D applications, and very slow..

1) AFAIK you can't, those are just parameters you put into WriteFile, so if the app doesn't have it, then you can't.

I can change them in the GUI.. so doesn't the GUI call a function that can set them?



I know I should try to disassemble explorer.exe to see how it does it, but I thought it would be easier if someone could just tell me, since there's a lot of stuff in it..

Oh, you mean on the entire device. I don't know how to use device API, I'm not sure you're even allowed without a driver, are you? But then I'm no Windows internal guru, sorry

Azu, use sysinternals' ProcMon to see what registry values are modified when changing the settings - I reckon that should be enough.

PS: you really don't want the "turn off windows write-cache buffer flushing on the device" (known in previous versions as "advanced performance") - what it does is make FlushFileBuffers() do absolutely nothing, which totally ruins applications' chance of ensuring safe write operations.

also keep in mind: some of such changes can be applied only after system restart

!?!?


Gah!!





It never said anything to me about restarting. But it does with some other things (like the pagefile).

Damn confusing Windows. X_X

i'm just supposing, can be wrong about particular feature

I didn't really gave a good look around it, but I suppose that you may call the driver directly, through ioctl call, and then pass IOCTL_DISK_SET_CACHE_INFORMATION as a flag (or kind of operation), filling a DISK_CACHE_INFORMATION structure.

Well, I guess that now you will have enough to google and figure out the rest by yourself.

Good Luck

Obs: The function used for this purpose is DeviceIoControl

Thanks