NullPointerException in Soot (soot.coffi.CFG)

[John Jorgensen <jorgnsn@lcd.uregina.ca>]

>>>>> "arudys" == Algis Rudys <arudys@cs.rice.edu> writes:

    arudys> Greetings --
    arudys> This was reported earlier on this list; here's a concrete case: 

    >> From Sun JDK for Linux build 1.4.1_01-b01, method

    arudys> <sun.rmi.transport.proxy.RMIMasterSocketFactory$AsyncConnector: void run()>

    arudys> I get: 

    arudys> Exception in thread "main" java.lang.NullPointerException
    arudys>         at java.util.Hashtable.get(Hashtable.java:329)
    .
    .
    .
    arudys> The exception table entry that triggers it is the
    arudys> first one added (the below is the list of exception table
    arudys> entries as they are processed by adjustExceptionTable()). 
    .
    .
    .
    arudys> null     144     34
    arudys> ^^^^

    arudys> Oddly, the startpc associated with this entry is 0.

Coincidentally, I sent a proposed patch to the first reporter of
the bug last night (the patch is appended).  He has yet to tell
me if it fixes the problem he encountered.

That null you spotted is indeed the key to the problem. I
introduced this bug last summer, when I modified soot.coffi.CFG
to fix another bug that manifested itself when the protected area
of an exception partially overlaps an inlined subroutine. I dealt
with the problem by comparing the bytecode indexes of the
subroutine being inlined with the bytecode indexes of the
protected area (seems pretty obvious in retrospect), but I made
the mistake of taking the index for the beginning of the inlined
code from the first instruction cloned for inlining, which
doesn't work when the inlined subroutine is empty, as it is for
sun.rmi.transport.proxy.RMIMasterSocketFactory$AsyncConnector.run()

Here's the patch. 

 --- soot-2.1.0/src/soot/coffi/CFG.java  2003-12-18 11:43:05.000000000 -0600
 +++ soot-2.1.0-patched/src/soot/coffi/CFG.java  2004-02-16 23:22:55.000000000 -0600
 @@ -735,7 +735,7 @@

	     LinkedList newentries = new LinkedList();

 -           int orig_start_of_subr = headbefore.next.originalIndex; // inclusive
 +           int orig_start_of_subr = astore.next.originalIndex; // inclusive
	     int orig_end_of_subr = ret.originalIndex; // again, inclusive

	     for (int i=0; i<ca.exception_table_length; i++)