Re: binary-or-shlib-defines-rpath

[Kjetil Torgrim Homme <kjetilho@linpro.no>]

Hamish Moffatt <hamish@debian.org> writes:

> On Mon, Feb 11, 2002 at 07:01:09PM +0100, Kjetil Torgrim Homme wrote:
> > Aha, I didn't realize there was that kind of black magic in ld.so
> > (documented in ldconfig).  Well, then I'd venture that ld.so is
> > imperfect.  If it knows to ignore certain paths in ld.so.conf, it
> 
> When does it ignore paths in ld.so.conf?

ldconfig tags the directories in the cache, so that ld.so knows which
paths should be consider for a given program.

>From ldconfig(1):

       ldconfig will attempt to deduce the type of ELF libs (ie.  libc
       5.x or libc 6.x (glibc)) based on what C libraries if any the
       library was linked against, [...]

       Some existing libs do not contain enough information to allow
       the deduction of their type, therefore the /etc/ld.so.conf file
       format allows the specification of an expected type.  This is
       only used for those ELF libs which we can not work out. The
       format is like this "dirname=TYPE", where type can be libc4,
       libc5 or libc6.

> If your binary contains a hard path to /lib/libc.so.6,

What do you mean by a hard path?  dlopen()?  Sure, it won't work.
Usually, /lib/ld-linux.so.2 is hard coded, libc is not.

> and then we move that library to /usr/i386-glibc2-linux/lib instead
> because libc.so.7 is available, your binary will no longer work.

If I understand the above excerpt correctly, ldconfig would need to be
extended to know about "libc7", but then it'd work.


Kjetil T.