[ python-Bugs-1075984 ] Memory fault pyexpat.so on SGI

[SourceForge.net]

Bugs item #1075984, was opened at 2004-11-30 13:13
Message generated for change (Comment added) made by kerofin
You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=105470&aid=1075984&group_id=5470

Category: XML
Group: Python 2.4
Status: Open
Resolution: None
Priority: 5
Submitted By: Maik Hertha (mhertha)
Assigned to: Nobody/Anonymous (nobody)
Summary: Memory fault pyexpat.so on SGI

Initial Comment:
I build the latest RC1 of python 2.4.
System SGI Fuel IP35, Irix 6.5.26m

cc -version
MIPSpro Compilers: Version 7.3.1.3m

- make tests passes test_pyexpat without error
- running this code leads to a core dump

-- code ---
import xml.dom.minidom
doc = xml.dom.minidom.parseString(fstream)

<<< core dump >>>
--- runing python -v test.py
#
/opt/python24c1/lib/python2.4/xml/dom/expatbuilder.pyc
matches
/opt/python24c1/lib/python2.4/xml/dom/expatbuilder.py
import xml.dom.expatbuilder # precompiled from
/opt/python24c1/lib/python2.4/xml/dom/expatbuilder.pyc
import xml.parsers # directory
/opt/python24c1/lib/python2.4/xml/parsers
#
/opt/python24c1/lib/python2.4/xml/parsers/__init__.pyc
matches
/opt/python24c1/lib/python2.4/xml/parsers/__init__.py
import xml.parsers # precompiled from
/opt/python24c1/lib/python2.4/xml/parsers/__init__.pyc
# /opt/python24c1/lib/python2.4/xml/parsers/expat.pyc
matches /opt/python24c1/lib/python2.4/xml/parsers/expat.py
import xml.parsers.expat # precompiled from
/opt/python24c1/lib/python2.4/xml/parsers/expat.pyc
dlopen("/opt/python24c1/lib/python2.4/lib-dynload/pyexpat.so",
2);
Memory fault(coredump)

- running this code from an interactive session leads
not to a coredump

I need some assistance howto provide further debug
information.

--maik./

----------------------------------------------------------------------

Comment By: Stephen Watson (kerofin)
Date: 2004-12-13 09:29

Message:
Logged In: YES 
user_id=471223

I've looked at the program that was dumping core and the
sequence is this:

1) Program imports pygtk, which links in the GTK libraries
2) Program loads SVG image which links in librsvg.so which
in turn links in /usr/local/lib/libexpat.so
3) Program imports pyexpat.
4) pyexpat calls XML_ErrorString, but as ld.so has already
linked in XML_ErrorString from /usr/local/lib/libexpat.so it
calls that version, not the one in pyexpat.so.  
5) pyexpat looks up an error defined by the later version of
expat it is expecting and gets a NULL pointer from the
earlier version it has.  It attempts to use it without
checking (strlen) and dumps core.

----------------------------------------------------------------------

Comment By: Stephen Watson (kerofin)
Date: 2004-12-10 17:01

Message:
Logged In: YES 
user_id=471223

Maybe it compiled against its own copy of expat, but pulled
in the system's copy when run?  

----------------------------------------------------------------------

Comment By: Michael Hudson (mwh)
Date: 2004-12-10 16:52

Message:
Logged In: YES 
user_id=6656

Uh, Python includes its own copy of expat, and I really
thought we were supposed to prefer our own version over
anything found on the system...

----------------------------------------------------------------------

Comment By: Stephen Watson (kerofin)
Date: 2004-12-10 16:46

Message:
Logged In: YES 
user_id=471223

I also got a core dump importing pyexpat on Solaris (SPARC)
and somebody else reported it on a *BSD system.

It appears to be a problem with older versions of expat not
being tested for.  I used gdb to trace it down to line 1972
in pyexpat.c where it attempts to define the first constant
from 1.95.8.  I had expat 1.95.7.  After upgrading to 1.95.8
it worked fine, as did the *BSD system. 

I think Python needs to check the expat version, as it does
elsewhere in the file, before defining those constants. 

I am still puzzelled over how it managed to compile
pyexpat.c in the first place...

----------------------------------------------------------------------

You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=105470&aid=1075984&group_id=5470