'''Python sys.excepthook hook to generate apport crash dumps.'''

# Copyright (c) 2006 - 2009 Canonical Ltd.
# Authors: Robert Collins <robert@ubuntu.com>
#          Martin Pitt <martin.pitt@ubuntu.com>
#
# 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.  See http://www.gnu.org/copyleft/gpl.html for
# the full text of the license.

import os
import sys

CONFIG = '/etc/default/apport'

# This doesn't use apport.packaging.enabled() because it is too heavyweight
# See LP: #528355
def enabled():
    '''Return whether Apport should generate crash reports.'''

    import re
    try:
        conf = open(CONFIG).read()
        return re.search('^\s*enabled\s*=\s*0\s*$', conf, re.M) is None
    except IOError:
        # if the file does not exist, assume it's enabled
        return True

def apport_excepthook(exc_type, exc_obj, exc_tb):
    '''Catch an uncaught exception and make a traceback.'''

    # create and save a problem report. Note that exceptions in this code
    # are bad, and we probably need a per-thread reentrancy guard to
    # prevent that happening. However, on Ubuntu there should never be
    # a reason for an exception here, other than [say] a read only var
    # or some such. So what we do is use a try - finally to ensure that
    # the original excepthook is invoked, and until we get bug reports
    # ignore the other issues.

    # import locally here so that there is no routine overhead on python
    # startup time - only when a traceback occurs will this trigger.
    try:
        # ignore 'safe' exit types.
        if exc_type in (KeyboardInterrupt, ):
            return

        # do not do anything if apport was disabled
        if not enabled():
            return

        # special handling of dbus-python exceptions
        if hasattr(exc_obj, 'get_dbus_name'):
            if exc_obj.get_dbus_name() == 'org.freedesktop.DBus.Error.NoReply':
                # NoReply is an useless crash, we do not even get the method it
                # was trying to call; needs actual crash from D-BUS backend (LP #914220)
                return

        try:
            from cStringIO import StringIO
        except ImportError:
            from io import StringIO

        import re, traceback
        from apport.fileutils import likely_packaged, get_recent_crashes

        # apport will look up the package from the executable path.
        try:
            binary = os.path.realpath(os.path.join(os.getcwdu(), sys.argv[0]))
        except (TypeError, AttributeError, IndexError):
            # the module has mutated sys.argv, plan B
            try:
                binary = os.readlink('/proc/%i/exe' % os.getpid())
            except OSError:
                return

        # for interactive python sessions, sys.argv[0] == ''; catch that and
        # other irregularities
        if not os.access(binary, os.X_OK) or not os.path.isfile(binary):
            return

        # filter out binaries in user accessible paths
        if not likely_packaged(binary):
            return

        import apport.report

        pr = apport.report.Report()
        # append a basic traceback. In future we may want to include
        # additional data such as the local variables, loaded modules etc.
        tb_file = StringIO()
        traceback.print_exception(exc_type, exc_obj, exc_tb, file=tb_file)
        pr['Traceback'] = tb_file.getvalue().strip()
        pr.add_proc_info()
        pr.add_user_info()
        # override the ExecutablePath with the script that was actually running.
        pr['ExecutablePath'] = binary
        try:
            pr['PythonArgs'] = '%r' % sys.argv
        except AttributeError:
            pass
        if pr.check_ignored():
            return
        mangled_program = re.sub('/', '_', binary)
        # get the uid for now, user name later
        user = os.getuid()
        pr_filename = '%s/%s.%i.crash' % (os.environ.get('APPORT_REPORT_DIR',
            '/var/crash'), mangled_program, user)
        crash_counter = 0
        if os.path.exists(pr_filename):
            if apport.fileutils.seen_report(pr_filename):
                # flood protection
                crash_counter = get_recent_crashes(open(pr_filename)) + 1
                if crash_counter > 1:
                    return

                # remove the old file, so that we can create the new one with
                # os.O_CREAT|os.O_EXCL
                os.unlink(pr_filename)
            else:
                # don't clobber existing report
                return

        if crash_counter:
            pr['CrashCounter'] = str(crash_counter)
        report_file = os.fdopen(os.open(pr_filename,
            os.O_WRONLY|os.O_CREAT|os.O_EXCL, 0o640), 'w')
        try:
            pr.write(report_file)
        finally:
            report_file.close()

    finally:
        # resume original processing to get the default behaviour,
        # but do not trigger an AttributeError on interpreter shutdown.
        if sys:
            sys.__excepthook__(exc_type, exc_obj, exc_tb)


def install():
    '''Install the python apport hook.'''

    sys.excepthook = apport_excepthook