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Re: gdb and shared libraries
On Wed, Feb 08, 2006 at 09:54:35PM -0800, Jim Blandy wrote:
> On 2/8/06, Patrick Alken <patrick.alken@colorado.edu> wrote:
> > So it is step #4 that I am hoping someone on the list can give me
> > details for. How do you know when all the libraries have been loaded
> > so that you can stop execution of the program while you load
> > the libs symbol tables? How do you get the pathnames of the libraries
> > after they have been loaded so you can mmap them?
>
> Well, each time it loads a shared library, the dynamic linker calls a
> specific function (I think it's _dl_debug_state on Linux), and there
> is a designated data structure for you to walk to find the current
> list of shlibs. See solib.c and solib-svr4.c.
>
> But I can't remember, nor can I Google, where this stuff is
> documented. I guess we're just depending on undocumented behavior (on
> Linux, at least). But the whole reason it's there is to help out the
> debugger, so I don't know why it'd be undocumented.
Well, that's how _we_ do it. How you're really _supposed_ to do it is
unclear, but involves the dynamic DT_DEBUG tag.
--
Daniel Jacobowitz
CodeSourcery