[Psi]

Hi there,

maybe this is not directly sourcemm related but anyway i found something about virtual functions in AMWiki.

To use those funcs i need to know the offset of any specific function as described in http://wiki.alliedmods.net/CCSPlayer...Strike:_Source for example.

If I am not wrong those offsets may change after any srcds update so I would like to know HOW to find out these offsets.

...would be glad if anybody can help me.

greetz
Psi

[BAILOPAN]

You need to use a disassembler that can understand symbolic information, as well as a binary that has symbolic information available (Linux binaries usually do).

The ones on the wiki were generated by IDA using an IDA script in our source tree.

[Psi]

Hi BAILOPAN,

thanks for the quick response. I have two last questions about that:

1) afaik, IDA is windows only, so the offsets i receive there are shifted by 1 in comparison to linux binaries, is that correct?

2) which file to disassemble? server.dll?

thanks for your help again

greetz
Psi

[edit]
ok, IDA is available for linux as well ;)

Disassembling "server.dll" i just get 4 exported routines, this can't be correct...

[Keeper]

Nah, load up the server_i486.so in IDA. Once the file is analyzed you will be able to find the vtable... section and export those offsets.

[Psi]

Hi Keeper,

thanks alot, I tried the windows version of IDA, I will test it with the linux one (if i find it).

greetz
Psi

[edit]
hmm, there seems to be no linux version of IDA although wikipedia says something different... any good DA for linux?

[CrimsonGT]

If you cant use windows, then install Wine. IDA is a windows only application.

[Psi]

now i know why i got confused...

IDA (a windows only DA) has to disassemle a linux shared object binary.
What i did not expect: it worked.

But now i have a new problem: i don't find a vtable. i get a list of exports that shows the addresses of the functions but not their offset. where is this ominous vtable display? neither "functions display" nor "exports" lead to a correct result OR - if they do - i have no idea on how to calculate the offset.

also the function names look a bit cryptic... no idea on how to find out the correct class::function names...

[Keeper]

The function names get mangled so that

void class::func1 ( int a )

is different from

void class::func1 ( float a )

There is an option in IDA to demangle the names. Check the Options->Demangle Names dialog.

Then if you click in the "Names" window, you can type what you want to get to the symbol you want. Start typing `vtable for'CBaseCombatWeapon( or whatever class you want ). Once it shows up in the names area, double click on it. That will bring the code up in the IDA View-A window

.data.rel.ro:00D826C0 ; `vtable for'CBaseCombatWeapon

Then you load up the script Bail was talking about and export that list to a text file. You can find the script here: http://hg.alliedmods.net/sourcemod-c...ls/ida_scripts ( URL might change due to updates in mercurial.

Load it from the File->IDC file... in the menu and click on the idc file you downloaded. A dialog should pop up that you can press one of two choices ... choose the one with the gear and it will ask you where you want to export to. That will produce the list like you saw on the wiki.

[Psi]

Very nice explanation, many thanks.

[Psi]

Hm, maybe i'm doing something wrong, but the names window does not contain any entry beginning with "vtable". also a search within the code for "vtable" returns no results.

what's my mistake?

[EDIT]
Ok i found the mistake -.- After changing the demangling settings you have to refresh the names window (i never worked with IDA that intensively). Maybe it is a product of my demangling setup, but i had to search for `vtable` (the leading ` is the difference). Anyway i now got what i was searching for, thanks to everyone here helping me.

Greetz
Psi