you can simply use VBoxDDU.dll APIs, VDOpen, VDWrite, ... can be linked directly to your app
--- On Fri, 12/24/10, Maxim Khitrov <[email protected]> wrote: From: Maxim Khitrov <[email protected]> Subject: Re: [vbox-dev] Byte-level read/write access to vdi files through Main API To: "Achim Hasenmüller" <[email protected]> Cc: [email protected] Date: Friday, December 24, 2010, 9:00 AM 2010/12/24 Achim Hasenmüller <[email protected]>: >> >> I suspect that the answer to my question is 'no', but would like to >> get a confirmation. Is there functionality in the Main API (which I'm >> accessing through COM on Windows) for byte-level read/write access to >> vdi files? > > Hehe, of course not. That would not be good for performance. But it would be very convenient for situations where performance was not a concern :) > However, the VirtualBox storage architecture supports a filter driver model. > You can develop a simple filter driver and dynamically insert it into the > chain of storage drivers. > > Here's an example filter which we use to perform consistency tests: > > http://www.virtualbox.org/browser/trunk/src/VBox/Devices/Storage/DrvDiskIntegrity.cpp > > In its init routine drvdiskintConstruct, it will install the required > handlers so that it receives callbacks on disk read/write. If you configure > your VM to "Use Host IO cache", then it will be simpler, because there will > be no async IO which is much harder to handle. > > If you want to insert boot sectors, you want to work on the layer above VDI > as you only care about sector reads/writes and not how the actual on disk > storage looks like. > > Achim Sounds like your solution would achieve better abstraction, but I think it's much more complicated that what I actually need. Ideally, I'd like to avoid messing with VirtualBox components on the other side of the Main API. I assume that's where filter drivers, such as DrvDiskIntegrity.cpp, are located? The API gives me the ability to lock the hard drive for writing and provides information about its type and location. Given that I don't need to work with dynamic disks or those that have snapshots, it seems that the easiest solution is to parse the metadata at the beginning of the file so that I know what regions correspond to sectors 0, 1, and so on. Or is the actual representation of the data on the disk more complicated than this, even with my set of restrictions? _______________________________________________ vbox-dev mailing list [email protected] http://vbox.innotek.de/mailman/listinfo/vbox-dev
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