Date: Sun, 20 Oct 1996 22:26:22 -0700 (PDT) From: John-Mark Gurney <jmg@nike.efn.org> To: Michael Smith <msmith@atrad.adelaide.edu.au> Cc: Douglas Thomas Crosher <dtc@scrooge.ee.swin.oz.au>, freebsd-current@FreeBSD.org Subject: Re: kern/1848: breakpoints in shared libraries don't fire Message-ID: <Pine.NEB.3.95.961020222007.293A-100000@nike> In-Reply-To: <199610210204.LAA04119@genesis.atrad.adelaide.edu.au>
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On Mon, 21 Oct 1996, Michael Smith wrote:
> Douglas Thomas Crosher stands accused of saying:
> >
> > > > > It's possible to set breakpoints in shared libraries, but
> > > > > executing the code doesn't cause a SIGTRACE.
> > >
> > > Setting a breakpoint in a shared library would be Bad, as you don't
> > > have any way of telling who else it is shared with. I suspect that
> > > the attempt to set the trace is silently failing.
> >
> > What about pages mmapped MAP_PRIVATE, couldn't the page be copied for
> > private use when the breakpoint is set?
>
> I'm sure it _could_, after all it's just software. However ld.so most
> likely maps pages as readonly, so you would have to make some changes
> there (to detect whether a program was being debugged etc.), or teach
> gdb to change the mappings on shared libraries.
I really don't understand all the talk about debugging shared libs... it
must be a problem with the updated gcc because under 2.6.3 w/ gdb 4.13 you
can debug share libs without a problem... just to make sure I just did it
with out a problem...
I wish I could tell you more of what I did... but all I did was compile
the lib with -g and yes.. the lib (my own cgiparse lib) is linked shared:
tmp:
-lcgiparse.1 => /usr/local/lib/libcgiparse.so.1.0 (0x801b000)
-lc.3 => /usr/lib/libc.so.3.0 (0x802b000)
hope this helps id the problem... ttyl...
John-Mark
gurney_j@efn.org
http://resnet.uoregon.edu/~gurney_j/
Modem/FAX: (541) 683-6954 (FreeBSD Box)
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