Re: A patch for binutils (Re: the setrlimit changes in glibc 2.1.3)

["H . J . Lu" <hjl at lucon dot org>]

On Thu, Jan 13, 2000 at 03:21:29PM -0500, Ian Lance Taylor wrote:
>    Date: Thu, 13 Jan 2000 11:23:31 -0800
>    From: "H . J . Lu" <hjl@lucon.org>
> 
>    Thanks. Here is a patch for binutils 2.9.5.0.22. Ian, what do you
>    think?
> 
>    Thu Jan 13 11:03:29 2000  H.J. Lu  <hjl@gnu.org>
> 
> 	   * elflink.h (elf_link_add_object_symbols): Bound the external
> 	   references to the default version to the hidden version.
> 
> There is something odd about this case.  libtest.so has an external
> reference to symbol foo in version FOO_1.0.  Why are we looking up
> foo@@FOO_1.0?  Why aren't we looking up foo@FOO_1.0?  If I understand

It is because libtest.so is linked against the older libfoo.so,
libfoo.so.1.0, where the FOO_1.0 of foo is the default. You got the
reference to foo@@FOO_1.0. The new libfoo.so, libfoo.so.1.1, has
the FOO_1.1 of foo as default and foo@FOO_1.0 is hidden.

> your patch, the latter is defined while the former is not.  That also
> matches my intuition.
> 
> We use the double @ to indicate the default version of a symbol.  But
> that is only applicable to a definition.  It does not make sense to
> refer to the default version of a symbol and to simultaneously specify
> a specific version.  When we do use the double @, we also set up a
> reference from the unqualified symbol name, and from the symbol name
> with a single @.

Please remember a specific version may change from default to hidden.
However, foo@FOO_1.0 will always be 100 binary compatible with
foo@@FOO_1.0.

> 
> So I suspect that your patch, which sets up an indirection from
> foo@@FOO_1.0 to foo@FOO_1.0, is fixing the wrong thing.  We should be
> asking why there would ever be a reference to foo@@FOO_1.0.
> 
> Perhaps the fix is as simple as changing the code to not add a second
> ELF_VER_CHR if sym.st_shndx is SHN_UNDEF.
> 

You are right. Here is the new patch. Please ignore my previous one.

Thanks.

H.J.
--
Index: elflink.h
===================================================================
RCS file: /work/cvs/gnu/binutils/bfd/elflink.h,v
retrieving revision 1.14
diff -u -p -r1.14 elflink.h
--- elflink.h	1999/11/01 22:47:51	1.14
+++ elflink.h	2000/01/13 20:45:07
@@ -1293,7 +1442,13 @@ elf_link_add_object_symbols (abfd, info)
 		  strcpy (newname, name);
 		  p = newname + namelen;
 		  *p++ = ELF_VER_CHR;
-		  if ((iver.vs_vers & VERSYM_HIDDEN) == 0)
+		  /* For the undefined versioned symbol, we always
+		     reference the hidden version. The default version
+		     will resolve the reference to the hidden one. It
+		     solves the problem where a version changes from
+		     default to higgen. */
+		  if ((iver.vs_vers & VERSYM_HIDDEN) == 0
+		      && sym.st_shndx != SHN_UNDEF)
 		    *p++ = ELF_VER_CHR;
 		  strcpy (p, verstr);