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I'm Currently writing a File Replication filter for VHDs - Since I am rather new to the topic I have a few questions about the Scope of certain parameters of the IRP.
Would be great if someone had the answers - or point me to a source/google search where I can expand my understanding about the Topics.
Could I use the IOPB.TargetFileObject from the PFLT_CALLBACK_DATA for my own read needs?
1.1. If no, even If I did an FltObjectReference beforehand? Is this even a sensible question or am I completely mistaken with how I think about this?
1.2. If yes, would It make more sense to Open the File for myself? I kind of don't want to have to compete with shared Acces rights
Can I Use the Pointer Address to the IOPB.TargetFileObject to find out if further IRPs write to the same file?
2.1. Could I miss IRPs from other Processes since they might use another File Object Addres - Or does Windows use the same Address to reference the File globally and toss it if nothing is referencing to it anymore?
Am I correct in my assumption that the WriteBuffer / MDL in a writing IRP is only valid until the IRP is done?
3.1. And if I want to write the same changes to another File I have to copy said buffer?
Each write/read from any Programm etc has to Open, do, Close the File. Is there any way to know if the IRPs I'm filtering are from this Chain/transaction?
4.1 I think the FileObject Pointer from the Open till the Close should be the same. Can someone Verify that?
The MDL in the FLTWriteFile seems to be Optional? What advantages do I have if I create one for My Write?
That's it - a big Thank you in advance!
Techit GmbH @ Germany
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