[Mailman-Developers] Python 1.5 compatible ? no!

Barry A. Warsaw bwarsaw@cnri.reston.va.us (Barry A. Warsaw)
Thu, 3 Sep 1998 16:26:38 -0400 (EDT)

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>>>>> "CT" == Christian Tismer <tismer@appliedbiometrics.com> writes:

    CT> I could not find an attachment, just the line above.

I'll try again below as plaintext.

    CT> How do I get at the CVS tree?



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#! /usr/bin/env python
# Copyright (C) 1998 by the Free Software Foundation, Inc.
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License
# as published by the Free Software Foundation; either version 2
# of the License, or (at your option) any later version.
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# GNU General Public License for more details.
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software 
# Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.

# This better succeed.  If this fails, Python is royally screwed so we might
# as well let the Web server give us a fatal and obtrusive error.
import sys

# From here on we are as bulletproof as possible!

# This function is useful for debugging.  When an error occurs, this attaches
# the file name to the exception string and re-raises.  This will be
# unnecessary in Python 1.5.2, which also does sensible things to most os
# module functions.

realopen = open
def open(filename, mode='r', bufsize=-1, realopen=realopen):
        return realopen(filename, mode, bufsize)
    except IOError, e:
        strerror = e.strerror + ': ' + filename
        e.strerror = strerror
        e.filename = filename
        e.args = (e.args[0], strerror)
        # Python 1.5
        raise e, None, sys.exc_info()[2]
        # Python 1.5.1
import __builtin__
__builtin__.__dict__['open'] = open

# This standard driver script is used to run CGI programs, wrapped in code
# that catches errors, and displays them as HTML.  This guarantees that
# (almost) any problems in the Mailman software doesn't result in a Web server
# error.  It is much more helpful to generate and show a traceback, which the
# user could send to the administrator, than to display a server error and
# have to trudge through server logs.

# Note: this isn't 100% perfect!  Here are some things that can go wrong that
# are not caught and reported as traceback-containing HTML:
# - This file could contain a syntax error.  In that case, you would indeed
#   get a Web server error since this file wouldn't even compile, and there's
#   no way to catch that.
# - The sys module could be royally screwed, probably we couldn't import it.
#   Both those would indicate serious problems in the Python installation.
#   These won't generate Web server errors, but neither will they give
#   meaningful tracebacks.
# I consider these pretty unlikely.

def run_main():
        # These will ensure that even if something between now and the
        # creation of the real logger below fails, we can still get
        # *something* meaningful
        logger = None
        # insert the relative path to the parent of the Mailman package
        # directory, so we can pick up the Utils module
        import os
        # sys gets imported at module level below
        sys.path.insert(0, os.pardir)
        # map stderr to a logger, if possible
        from Mailman.Logging.StampedLogger import StampedLogger
        logger = StampedLogger('error',
        # The name of the module to run is passed in argv[1].  What we
        # actually do is import the module named by argv[1] that lives in the
        # Mailman.Cgi package.  That module must have a main() function, which
        # we dig out and call.
        scriptname = sys.argv[1]
        # See the reference manual for why we have to do things this way.
        # Note that importing should have no side-effects!
        pkg = __import__('Mailman.Cgi', globals(), locals(), [scriptname])
        module = getattr(pkg, scriptname)
        main = getattr(module, 'main')
        except SystemExit:
            # this is a valid way for the function to exit

# We are printing error reporting to two places.  One will always be stdout
# and the other will always be the log file.  It is assumed that stdout is an
# HTML sink and the log file is a plain text sink.

def print_traceback(logfp=None):
    if logfp is None:
        logfp = sys.__stderr__

        import traceback
    except ImportError:
        traceback = None

    # write to the log file first
    logfp.write('[----- Traceback ------]\n')
    if traceback:
        logfp.write('[failed to import module traceback]\n')
        logfp.write('[exc: %s, var: %s]\n' % sys.exc_info()[0:2])

    # print to the HTML sink
    print """\
Content-type: text/html

<p><h3>We're sorry, we hit a bug!</h3>

<p>If you would like to help us identify the problem, please
email a copy of this page to the webmaster for this site with
a description of what happened.  Thanks!

    if traceback:
        print '[failed to import module traceback]'
        print '[exc: %s, var: %s]' % sys.exc_info()[0:2]
    print '\n\n</pre>'

def print_environment(logfp=None):
    if logfp is None:
        logfp = sys.__stderr__

        import os
    except ImportError:
        os = None

    # write to the log file first
    logfp.write('[----- Environment Variables -----]\n')
    if os:
        for k, v in os.environ.items():
            logfp.write('\t%s: %s\n' % (k, v))
        logfp.write('[failed to import module os]\n')

    # write to the HTML sink
    if os:
        print '''\
<p><hr><h4>Environment variables:</h4>

        for k, v in os.environ.items():
            print '<tr><td>', k, '</td><td>', v, '</td></tr>'
        print '</table>'
        print '<p><hr>[failed to import module os]'

    # Python 1.5 doesn't have these by default.  Let's make our lives easy
    if not hasattr(sys, '__stderr__'):
        sys.__stderr__ = sys.stderr
    if not hasattr(sys, '__stdout__'):
        sys.__stdout__ = sys.stdout

    # Some exception percolated all the way back up to the top.  This
    # generally shouldn't happen because the run_main() call is similarly
    # wrapped, but just in case, we'll give it one last ditch effort to report 
    # problems to *somebody*.  Most likely this will end up in the Web server
    # log file.
        # Nope, we're quite screwed
        print """\
Content-type: text/html

<p><h3>We're sorry, we hit a bug!</h3>

Mailman experienced a very low level failure and could not even generate a
useful traceback for you.  Please report this to the Mailman administrator at
this site.
        sys.__stderr__.write('[Mailman: low level unrecoverable exception]\n')