unregister crash handler on call

prevents recursive invocation of the crash handler

IPython/core/crashhandler.py

@@ -1,181 +1,186 b''
 # encoding: utf-8
 """sys.excepthook for IPython itself, leaves a detailed report on disk.
 
 Authors:
 
 * Fernando Perez
 * Brian E. Granger
 """
 
 #-----------------------------------------------------------------------------
 #  Copyright (C) 2001-2007 Fernando Perez. <[e-mail]>
 #  Copyright (C) 2008-2010  The IPython Development Team
 #
 #  Distributed under the terms of the BSD License.  The full license is in
 #  the file COPYING, distributed as part of this software.
 #-----------------------------------------------------------------------------
 
 #-----------------------------------------------------------------------------
 # Imports
 #-----------------------------------------------------------------------------
 
 import os
 import sys
 from pprint import pformat
 
 from IPython.core import ultratb
 from IPython.utils.sysinfo import sys_info
 
 #-----------------------------------------------------------------------------
 # Code
 #-----------------------------------------------------------------------------
 
 # Template for the user message.
 _default_message_template = """\
 Oops, {app_name} crashed. We do our best to make it stable, but...
 
 A crash report was automatically generated with the following information:
   - A verbatim copy of the crash traceback.
   - A copy of your input history during this session.
   - Data on your current {app_name} configuration.
 
 It was left in the file named:
 \t'{crash_report_fname}'
 If you can email this file to the developers, the information in it will help
 them in understanding and correcting the problem.
 
 You can mail it to: {contact_name} at {contact_email}
 with the subject '{app_name} Crash Report'.
 
 If you want to do it now, the following command will work (under Unix):
 mail -s '{app_name} Crash Report' {contact_email} < {crash_report_fname}
 
 To ensure accurate tracking of this issue, please file a report about it at:
 {bug_tracker}
 """
 
 
 class CrashHandler(object):
     """Customizable crash handlers for IPython applications.
 
     Instances of this class provide a :meth:`__call__` method which can be
     used as a ``sys.excepthook``.  The :meth:`__call__` signature is::
 
         def __call__(self, etype, evalue, etb)
     """
 
     message_template = _default_message_template
     section_sep = '\n\n'+'*'*75+'\n\n'
 
     def __init__(self, app, contact_name=None, contact_email=None,
                  bug_tracker=None, show_crash_traceback=True, call_pdb=False):
         """Create a new crash handler
 
         Parameters
         ----------
         app :  Application
             A running :class:`Application` instance, which will be queried at
             crash time for internal information.
 
         contact_name : str
             A string with the name of the person to contact.
 
         contact_email : str
             A string with the email address of the contact.
 
         bug_tracker : str
             A string with the URL for your project's bug tracker.
 
         show_crash_traceback : bool
             If false, don't print the crash traceback on stderr, only generate
             the on-disk report
 
         Non-argument instance attributes:
 
         These instances contain some non-argument attributes which allow for
         further customization of the crash handler's behavior. Please see the
         source for further details.
         """
         self.crash_report_fname = "Crash_report_%s.txt" % app.name
         self.app = app
         self.call_pdb = call_pdb
         #self.call_pdb = True # dbg
         self.show_crash_traceback = show_crash_traceback
         self.info = dict(app_name = app.name,
                     contact_name = contact_name,
                     contact_email = contact_email,
                     bug_tracker = bug_tracker,
                     crash_report_fname = self.crash_report_fname)
 
 
     def __call__(self, etype, evalue, etb):
         """Handle an exception, call for compatible with sys.excepthook"""
-
+        
+        # do not allow the crash handler to be called twice without reinstalling it
+        # this prevents unlikely errors in the crash handling from entering an
+        # infinite loop.
+        sys.excepthook = sys.__excepthook__
+        
         # Report tracebacks shouldn't use color in general (safer for users)
         color_scheme = 'NoColor'
 
         # Use this ONLY for developer debugging (keep commented out for release)
         #color_scheme = 'Linux'   # dbg
         try:
             rptdir = self.app.ipython_dir
         except:
             rptdir = os.getcwdu()
         if rptdir is None or not os.path.isdir(rptdir):
             rptdir = os.getcwdu()
         report_name = os.path.join(rptdir,self.crash_report_fname)
         # write the report filename into the instance dict so it can get
         # properly expanded out in the user message template
         self.crash_report_fname = report_name
         self.info['crash_report_fname'] = report_name
         TBhandler = ultratb.VerboseTB(
             color_scheme=color_scheme,
             long_header=1,
             call_pdb=self.call_pdb,
         )
         if self.call_pdb:
             TBhandler(etype,evalue,etb)
             return
         else:
             traceback = TBhandler.text(etype,evalue,etb,context=31)
 
         # print traceback to screen
         if self.show_crash_traceback:
             print >> sys.stderr, traceback
 
         # and generate a complete report on disk
         try:
             report = open(report_name,'w')
         except:
             print >> sys.stderr, 'Could not create crash report on disk.'
             return
 
         # Inform user on stderr of what happened
         print >> sys.stderr, '\n'+'*'*70+'\n'
         print >> sys.stderr, self.message_template.format(**self.info)
 
         # Construct report on disk
         report.write(self.make_report(traceback))
         report.close()
         raw_input("Hit <Enter> to quit this message (your terminal may close):")
 
     def make_report(self,traceback):
         """Return a string containing a crash report."""
 
         sec_sep = self.section_sep
 
         report = ['*'*75+'\n\n'+'IPython post-mortem report\n\n']
         rpt_add = report.append
         rpt_add(sys_info())
 
         try:
             config = pformat(self.app.config)
             rpt_add(sec_sep)
             rpt_add('Application name: %s\n\n' % self.app_name)
             rpt_add('Current user configuration structure:\n\n')
             rpt_add(config)
         except:
             pass
         rpt_add(sec_sep+'Crash traceback:\n\n' + traceback)
 
         return ''.join(report)