Re: Help using elfutils to get function and line number

[Mihai Tarce <mihaitarce at yahoo dot com>]

>(We're not quite there yet, but this sort of thing will be pretty
>easy to express with systemtap, as in ...)

I hadn't heard of systemtap, but now that I looked it up, I have to say that I
think it will be a great tool. Great work!

>This is fine an encouraged if the resulting code you're producing is not
>closed source and you're trying to sell it.

As I have said in a previous post, I'm writing this application as my diploma thesis
at university. And yes, I intend to release the code under the GPL.


I looked at the eu-addr2line tool, and it does pretty much everything I need.
In order to provide it with the correct addresses, I do the following:
- get the base pointer of the main program file (dlopen(NULL), dlsym("main"))
- use dladdr() on all the stack return addresses, to determine to which
object file they belong to
- if the object file differs from the main program file (its base pointer differs),
I subtract its base pointer from it, to get its address in the object file

This works as long as I use the -rdynamic flag, but most tested programs won't
have this flag. I should be able to solve the problem by reading the information
directly from debug section (since I have the address and file name) -- I should
be able to do that with help from eu-addr2line.

There is still one problem how can I determine which object file contains the main()
function? This file will have the stack return addresses which I can process directly.
When I remove the -rdynamic flag, the dlopen/dlsym doesn't work anymore, as
expected. Any ideas?

Sorry for making this post so long, I just wanted to give you a better
image of what I am trying to do.
Thanks for your help,

Mihai