req.add_handler/req.handler and PythonInterpPerDirective

• Key: MODPYTHON-160
• Type: Bug
• Status: Closed
• Resolution: Fixed
• Priority: Major
• Assignee: Graham Dumpleton
• Reporter: Graham Dumpleton
• Component/s: core
• Affects Version/s: 3.2.8
• Fix Version/s: 3.3.1

Description

MODPYTHON-125 made req.handler writable. Being able to now do this has uncovered a bug whereby if PythonInterpPerDirective is used mod_python can cause Apache to crash. Code to trigger the problem is:

# .htaccess

SetHandler mod_python
PythonInterpPerDirective On
PythonFixupHandler interpreter_1

# interpreter_1.py

from mod_python import apache

def fixuphandler(req):
    req.log_error("fixuphandler")
    req.log_error("interpreter=%s"%req.interpreter)
    req.log_error("directory=%s"%req.hlist.directory)
    req.handler = "mod_python"
    req.add_handler("PythonHandler","interpreter_1")
    return apache.OK

def handler(req):
    req.log_error("handler")
    req.log_error("interpreter=%s"%req.interpreter)
    req.log_error("directory=%s"%req.hlist.directory)
    req.content_type = 'text/plain'
    req.write('hello')
    return apache.OK

In summary, if PythonHandler is not used in Apache configuration to enable mod_python but it is done by assignment to req.handler in fixup phase and then req.add_handler() is used to add a handler to be called for content phase, and PythonInterpPerDirective is being used, mod_python will cause Apache to crash.

Location of crash not yet identified.

Comments

[Graham Dumpleton]

Actually, one doesn't need to set req.handler as SetHandler/AddHandler in Apache configuration will set up same scenario. Example given was actually doing both when it should have been doing one or the other. As such, this problem can be triggered in mod_python 3.2.8 as well.