Re: Use of -rpath

["Marcelo E. Magallon" <mmagallo@debian.org>]

>> Peter Eisentraut <peter_e@gmx.net> writes:

 > > As far as Debian is concerned, use of rpath is a bug.  Here's a quote from
 > > some Debian system documentation:
 > > 
 > >   libtool automatically inserts `-rpath' settings when compiling your
 > >   program.
 > 
 > I don't think so.
 
 Nowadays the situation might have changed...  let me check...  Nope,
 1.3.5 still uses -rpath whenever shared libraries are going to be
 used.

 > > But `-rpath' can cause big problems if the referenced
 > >   libraries get updated. Therefore, no Debian package should use the
 > >   `-rpath' option.
 > 
 > I'm not sure I buy that. All -rpath does is add a directory to the search
 > path that the program consults at runtime for its shared libraries. So
 > it's just an alternative in place of

 The rpath in the library tells the linker where the library is
 installed.  This is hardcoded into the linked program.  From ld.info:

 >   Add a directory to the runtime library search path.  This is used
 >   when linking an ELF executable with shared objects.  All `-rpath'
 >   arguments are concatenated and passed to the runtime linker, which
 >   uses them to locate shared objects at runtime.  The `-rpath'
 >   option is also used when locating shared objects which are needed
 >   by shared objects explicitly included in the link; see the
 >   description of the `-rpath-link' option.  If `-rpath' is not used
 >   when linking an ELF executable, the contents of the environment
 >   variable `LD_RUN_PATH' will be used if it is defined.

 This is particularly nasty when you -rpath things like /usr/lib.

 > >   libtool also refuses to link shared libraries against other shared
 > >   libraries.
 > 
 > I don't think so.

 He's right.  See (libtool.info)Inter-library dependencies.  Note
 particularly:

 >  The simple-minded inter-library dependency tracking code of libtool
 >  releases prior to 1.2 was disabled because it was not clear when it
 >  was possible to link one library with another, and complex failures
 >  would occur.  A more complex implementation of this concept was
 >  re-introduced before release 1.3, but it has not been ported to all
 >  platforms that libtool supports.  The default, conservative behavior
 >  is to avoid linking one library with another, introducing their
 >  inter-dependencies only when a program is linked with them.  

 i.e., you have to ask libtool to do this, else it won't.

 Greetings,

                                        Marcelo