Re: [Mesa3d-dev] libtool (was CVS and SSE)

[Marcelo E. M. <mar...@bi...>]

>> "Sven M. Hallberg" <pe...@gm...> writes:

 > Then, if we don't know the correct filename (except in special cases
 > where there is something like an ABI) we can let libtool decide.
 > After all it's its job! If we stumble across a system with an ABI we
 > might be violating, we can still incorporate a special-case
 > treatment.

 Yes.  My guess is that each (Unix-like) vendor has (an|their own) ABI
 for OpenGL.  Linux just happens to have one that's used by more than
 one group.  A quick look arround here indicates that HP-UX's libGL is
 called libGL.2, IRIX's seems to be called libGL.so with a "MIPS
 version" of "sgi1.0" (I have never understood SGI's policy regarding
 SONAMEs, but I've never seen it break, so I guess it's ok).  The other
 Unix flavors I have access to don't have the vendor's libGL installed
 on them. 

 > Here's the pseudo-code for the install-hook, do you think this would
 > be OK to do on systems identified as Linux?

 Hmmm...  the whole ABI bussiness is about the soname *in* the library
 file.  libtool happyly ignores any -Wl,-soname,libfoo.so.1 you pass to
 it (because it's not portable).

 >         if test `find .libs/ -name libGL.so.1 | grep -c libGL.so.1` != 1; then
 if there's exactly one file named libGL.so.1 ...
 >           libfile=`find .libs/* -not -type l -not -name '*.lai'`
 look for the library files ... (note there are likely two of these, one
 libGL.so.x.y.z and one libGL.a -- you *want* the libGL.a, too)
 >           if test 'echo $libfile | grep -c $libfile` = 1; then
 I got lost here.  If there's exactly one shared library?
 >             ln -s @libdir@/$libfile @libdir@/libGL.so.1
 link libGL.so.1 to this
 >           else
 else there's a problem.

 Like I said, what's important is the SONAME contained in the library,
 what this file is called is not important.  Like this:

 soname=`readelf -d $libfile | sed -ne '/SONAME/ s/.*\[\(.*\)\]/\1/p'`
 if test $soname != libGL.so.1
     echo There's a problem ...
     exit 1
 else
     # Asuming libfile is something like libGL.so.1.2.350 (and not
     # /some/dir/.libs/libGL.so.1.2.350)
     ln -s $libfile @libdir@/libGL.so.1
 fi

 (objdump and readelf are both part of binutils, so on Linux it's safe
 to asume they are present.  I just happen to like readelf better)

 > So you mean, we should include the library depedencies in our library
 > objects?

 If possible, yes.  It makes life much simpler.  :-)

 BTW, I tried -version-info 3:350:2 on IRIX...  not good... the linker
 exits with a bus error.  Gotta love the MIPSpro tool chain...

-- 
Marcelo