debugging a dynamically loaded library

[Kevin Buettner]

On Aug 29,  4:07pm, H . J . Lu wrote:

> > (gdb) b main.c:23
> > Breakpoint 1 at 0x80487fc: file main.c, line 23.
> > (gdb) r
> > Starting program: /home/kev/ctests/dynlib/main 
> > 
> > Breakpoint 1, main (argc=1, argv=0xbffffa2c) at main.c:23
> > 23        init = dlsym(handle, "dso_init");
> > (gdb) b dso_init
> > Breakpoint 2 at 0x400188a2: file dso.c, line 10.
> 
> For some reason, it doesn't work for me:
> 
> GNU gdb 2001-08-29-cvs (MI_OUT)
> ....
> (gdb) b main.c:23
> Breakpoint 1 at 0x8048820: file main.c, line 23.
> (gdb) r
> Starting program: /home/hjl/bugs/gdb/dlopen/main 
> 
> Breakpoint 1, main (argc=1, argv=0xbffff804) at main.c:23
> 23        init = dlsym(handle, "dso_init");
> (gdb) b dso_init
> Cannot access memory at address 0x123
> (gdb) p dso_init
> $1 = {<text variable, no debug info>} 0x40017800 <dso_init>
> (gdb) info shared
> >From        To          Syms Read   Shared Object Library
> 0x400281d0  0x40028fc0  Yes         /lib/libdl.so.2
> 0x40047400  0x40147080  Yes         /lib/i686/libc.so.6
> 0x40001eb0  0x40012f20  Yes         /lib/ld-linux.so.2
> 0x400176d0  0x400178b0  Yes         ./dso.so
> 
> I am using glibc 2.2.4 on x86. It seems that gdb doesn't add the base
> address of ./dso.so.

H. J.,

Could you try 

    http://sources.redhat.com/ml/gdb-patches/2001-09/msg00003.html

and let me know if it fixes the above problem?

Thanks,

Kevin