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Topic created on: December 24, 2010 01:01 CST by Usman .

Hello,

I need to map RVA (Relative virtual address that's taken from pdb file) to PE file(EXE) offset when reading PE file from a disk location. For this I need to convert RVA to file offset so that I can read out GUIDS(CLSID,IID's) from that location.

Regards
Usman

cseagle		December 24, 2010 11:48.20 CST
Very roughly: IMAGE_SECTION_HEADER *s; //initialize s to point to section header array //or read one section header at a time fro the file ... //n is the number of sections as specified in the //pe headers DWORD fileOffset = 0; for (int i = 0; i < n; i++) { DWORD end = s[i].VirtualAddress + s[i].Misc.VirtualSize; if (myRVA >= s[i].VirtualAddress && myRVA < end) { fileOffset = myRVA - s[i].VirtualAddress + s[i].PointerToRawData; break; } } if (fileOffset) { //do something } I leave it to you to fill in the holes. There are plenty of references on the PE file format out there.

yuansunxue		December 27, 2010 02:18.39 CST
maybe you can use LoadPE.EXE

Usman		December 28, 2010 01:53.21 CST
@cseagle: Can you please give me your mailing id so that I can give you complete detail about RVA which's I am getting in case of EXE from pdb, and GUID value that I want read from binary by reading it as binary file. Because this code is not returning correct Offset which's required, it's just returning some other arbitrary value. I have CFF explorer which' displaying different offset location in the PE file rather than this code returning.(Might be image base RVA needs to be subtracted from its given offset...?)

RabidCicada		January 6, 2011 11:29.40 CST
Hey there. There are lots of extremely good documentations of the PE file format. I suggest you read Matt Pietreks articles. RVA's are simple to calculate but getting it done right is just a matter of tedium and propper offsetting. You need to understand how a file on disk is laid out versus how it is laid out in memory. You need to pay close attention to alignment values for in-memory versus in-file. You also need to be aware that some files move code around (don't know your RE target). Resources: http://msdn.microsoft.com/en-us/magazine/cc301805.aspx http://msdn.microsoft.com/en-us/magazine/cc301808.aspx http://msdn.microsoft.com/en-us/magazine/ms809762.aspx https://www.openrce.org/reference_library/files/reference/PE%20Format.pdf

savagefarmer		August 26, 2011 10:28.28 CDT
Sorry to bump, but I found a decent article on the differences between Relative Virtual Addresses (RVAs) and PE file offsets--and how to translate between them-- that I thought I'd share. It can be found here.

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