org.xml.* not in libgcj but libgij

[Michael Matz]

Hi,

I've not opened a bug yet, because I don't understand everything, and 
because we need a local patch to make it happen.

So, first we have the problem, that the org.xml.* and 
org.w3c.* classes (exactly those from the external/ subdir in libjava) are 
not in libgcj anymore.  Reading the archives it seems that they were 
supposed to be provided by a different mean (endorsed dirs), but this 
didn't work that well, so Tom partly reverted his initial patch in
  http://gcc.gnu.org/ml/java-patches/2005-q1/msg00881.html

I think that revert itself was broken, because it did this:

-libgij_la_LIBADD = -L$(here)/.libs libgcj.la
+libgij_la_LIBADD = -L$(here)/.libs libgcj.la \
+       external/sax/libsax-gcj.la \
+       external/w3c_dom/libw3c-gcj.la

Note how it adds the external convenience libs to libgij, instead of 
libgcj (like the mail, but not the changelog says).  This break compiling 
trang with gcj, as those classes can't be found anymore (and there are 
also no jars or shared libs installed for them, as they are built only as 
convenience libs).  I think what Tom meant was to add them back to 
libgcj_la_LIBADD (patch below).  Note that this all is about natively 
compiling, not to class files.

With that patch we get a little further, in that trang links.  But it 
doesn't work, for the same reasons for that also this testcase breaks to 
run:
------------------------
import org.xml.sax.helpers.DefaultHandler;

public class A extends DefaultHandler {

    public static void main (String[] args) {
        System.out.println ("Hello.");
        System.exit(0);
    }

}
------------------------

(this testcase also can't be compiled without the patch btw).

The error message when running this is:
Exception in thread "main" java.lang.LinkageError: unexpected exception 
duringlinking: A
   at java.lang.VMClassLoader.transformException(java.lang.Class, java.lang.Throwable) (/usr/lib/libgcj.so.6.0.0)
   at java.lang.VMClassLoader.resolveClass(java.lang.Class) (/usr/lib/libgcj.so.6.0.0)
   at java.lang.Class.initializeClass() (/usr/lib/libgcj.so.6.0.0)
   at A.main(java.lang.String[]) (Unknown Source)
   at gnu.java.lang.MainThread.call_main() (/usr/lib/libgcj.so.6.0.0)
   at gnu.java.lang.MainThread.run() (/usr/lib/libgcj.so.6.0.0)
Caused by: java.lang.NullPointerException
   at java.lang.VMClassLoader.resolveClass(java.lang.Class) (/usr/lib/libgcj.so.6.0.0)
   ...4 more

We debugged this a bit, and the actuall segfault which causes the 
NullPointerException is in _Jv_Linker::prepare_constant_time_tables at:
519           has_interfaces += klass0->interface_count;

because klass0 is 0x1, i.e. invalid pointer.  This is because:
(gdb) p klass->superclass->superclass
$2 = 0x1

The actuall superclass with the broken superclass member is:
(gdb) p (char*)klass->superclass->name->data
$6 = 0x40abcf8a "org.xml.sax.helpers.DefaultHandler"
(gdb) p (char*)klass->name->data
$7 = 0x80493ee "A"

So, it seems that org.xml.sax.helpers.DefaultHandler is not correctly 
initialized, although it is used in the internal structures.  I tried to 
set a breakpoint on _Jv_InitClass and 
java::lang::VMClassLoader::resolveClass to see when exactly the org.xml.* 
class is loaded/initialized, but it never happened.

So except the inclusion of the convenience libs into libgij also something 
else must have been broken.  I don't know enough about the java runtime to 
move muc forward.  I can't at least find something like a "go though all 
classes and initialize them", or a class list, or something similar.  So 
my theory is that someone is responsible for initializing all classes in 
one DSO, and for some reason this is forgotten for the org.xml (and w3c) 
classes, even if the are now in the libgcj DSO.


Ciao,
Michael.
-- 
Index: libjava/Makefile.am
===================================================================
RCS file: /cvs/gcc/gcc/libjava/Makefile.am,v
retrieving revision 1.455.2.10
diff -u -r1.455.2.10 Makefile.am
--- libjava/Makefile.am	6 Apr 2005 21:38:10 -0000	1.455.2.10
+++ libjava/Makefile.am	18 Apr 2005 11:51:50 -0000
@@ -232,9 +232,7 @@
 libgij_la_SOURCES = gij.cc
 libgij_la_DEPENDENCIES = libgcj.la libgcj.spec
 ## See jv_convert_LDADD.
-libgij_la_LIBADD = -L$(here)/.libs libgcj.la \
-	external/sax/libsax-gcj.la \
-	external/w3c_dom/libw3c-gcj.la
+libgij_la_LIBADD = -L$(here)/.libs libgcj.la
 ## The mysterious backslash in the grep pattern is consumed by make.
 libgij_la_LDFLAGS = -rpath $(toolexeclibdir) \
         -version-info `grep -v '^\#' $(srcdir)/libtool-version` $(LIBGCJ_LD_SYMBOLIC)
@@ -272,6 +270,8 @@
 	-version-info `grep -v '^\#' $(srcdir)/libtool-version`
 libgcj_la_LIBADD = \
 	libgcj0_convenience.la \
+	external/sax/libsax-gcj.la \
+	external/w3c_dom/libw3c-gcj.la
 	$(LIBFFI) $(ZLIBS) $(GCLIBS) $(propertyo_files)
 libgcj_la_DEPENDENCIES = libgcj-$(gcc_version).jar \
 	java/lang/fdlibm.h java/lang/ieeefp.h java/lang/mprec.h \