ld.so slight difference Linux and FreeBSD ports/127946

[Kostik Belousov]

On Sun, Jun 14, 2009 at 08:14:57AM +0900, Maho NAKATA wrote:
> Hello Konstantin, and *
> 
> We have a longstanding OpenOffice.org porting issue for FreeBSD.
> Strange crashes.
> So I'd like to ask you about following issue. 
> http://www.openoffice.org/issues/show_bug.cgi?id=22253
> .
> There are some small difference between ld.so implementation
> between FreeBSD and Linux. Here is the test program that identify
> the difference clearly. (it also applies to NetBSD)
> 
> ------------------------------------------------
> "dlsym() search _on_the_main_program_" i.e. the handle is not the
> dlopen()ed shared library itself, but the main program (which you get
> back with dlopen(NULL, RTLD_LAZY) )
> I've modified your test program a bit:
> 
> #include <stdio.h>
> #include <stdlib.h>
> #include <dlfcn.h>
> 
> int main(int argc, char **argv) {
>   void *handle, *handlemain;
>   double (*cosine)(double);
>   char *error;
> 
>   handle = dlopen ("libm.so", RTLD_LAZY|RTLD_GLOBAL);
>   if (!handle) {
>     fprintf (stderr, "%s\n", dlerror());
>     exit(1);
>   }
> 
>   handlemain = dlopen(NULL, RTLD_LAZY);
>   cosine = dlsym(handlemain, "cos");
>   if ((error = dlerror()) != NULL)  {
>     fprintf (stderr, "%s\n", error);
>     exit(1);
>   }
> 
>   printf ("%f\n", (*cosine)(2.0));
>   dlclose(handle);
>   return 0;
> }
> 
> On Linux:
> bash-2.05b$ ./a.out 
> -0.416147
> 
> while on NetBSD:
> -bash-2.05b$ ./a.out 
> Undefined symbol "cos"
> ------------------------------------------------
> 
> It seems that this is the root cause of some issues.
> http://www.openoffice.org/issues/show_bug.cgi?id=22253
> http://www.openoffice.org/issues/show_bug.cgi?id=98781
> maybe also
> http://www.freebsd.org/cgi/query-pr.cgi?pr=128176
> 
> It seems ld.so employs same mechanism between Linux and MacOSX.
> 
> Could you please help me a bit?

According to the Solaris dlopen(3) and dlsym(3) documentation,
objects opened with RTLD_GLOBAL shall participate in any dlsym()
search. Please, try the following patch.

diff --git a/libexec/rtld-elf/rtld.c b/libexec/rtld-elf/rtld.c
index 40ed6ed..2badcfc 100644
--- a/libexec/rtld-elf/rtld.c
+++ b/libexec/rtld-elf/rtld.c
@@ -2141,6 +2141,11 @@ do_dlsym(void *handle, const char *name, void *retaddr, const Ver_Entry *ve,
 				 &donelist);
 	}
     }
+    if (def == NULL) {
+	donelist_init(&donelist);
+	def = symlook_list(name, hash, &list_global, &defobj, ve, flags,
+			   &donelist);
+    }
 
     if (def != NULL) {
 	rlock_release(rtld_bind_lock, lockstate);
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