how to redefine _start ?

how to redefine _start ?

[Yannick PERRET]

Hi,

I'm working on a profiler based on the 'instrument-functions'
gcc feature (functioncheck on sourceforge).

For performance reasons, I want to make some inits
before any program execution (before main). In addition
I want to perform these inits before static constructors in
C++ program (which start before main).

I tried to give my own _start, _init and _fini functions by
removing the crt1 ones (-nostartlibs). The problem is
that I cannot figure what _start is supposed to do before
calling main() (return value, args...). The problem is the
same for _fini function.

I checked the gcc source, but crt1 seems to only be ASM
code.


Is it possible to write _start and stuff in C properly ?
If yes, where to find some documentation/exemples ?
If no, anybody got an idea to perform "before-main" treatments
(and of course "after-main") ?


Thank you for any help.

Regards
--
Yannick

Re: how to redefine _start ?

[Hans-Peter Nilsson]

On Tue, 8 Jan 2002, Yannick PERRET wrote:
> Is it possible to write _start and stuff in C properly ?

Short answer: no.

> If yes, where to find some documentation/exemples ?
> If no, anybody got an idea to perform "before-main" treatments
> (and of course "after-main") ?

See docs on the linker option --wrap, as in "--wrap main".
You will also want "--wrap exit".

brgds, H-P