Add debug handler to print a stacktrace on Ctrl-C in debug mode.

bin/spack

@@ -93,6 +93,10 @@ def main():
     tty.set_debug(args.debug)
     spack.debug = args.debug
 
+    if spack.debug:
+        import spack.util.debug as debug
+        debug.register_interrupt_handler()
+
     spack.spack_working_dir = working_dir
     if args.mock:
         from spack.packages import PackageDB

lib/spack/spack/util/debug.py

@@ -0,0 +1,52 @@
+##############################################################################
+# Copyright (c) 2013-2015, Lawrence Livermore National Security, LLC.
+# Produced at the Lawrence Livermore National Laboratory.
+#
+# This file is part of Spack.
+# Written by Todd Gamblin, tgamblin@llnl.gov, All rights reserved.
+# LLNL-CODE-647188
+#
+# For details, see https://scalability-llnl.github.io/spack
+# Please also see the LICENSE file for our notice and the LGPL.
+#
+# 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) version 2.1 dated February 1999.
+#
+# This program is distributed in the hope that it will be useful, but
+# WITHOUT ANY WARRANTY; without even the IMPLIED WARRANTY OF
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the terms and
+# conditions of the GNU General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser 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
+##############################################################################
+"""Debug signal handler: prints a stack trace and enters interpreter.
+
+``register_interrupt_handler()`` enables a ctrl-C handler that prints
+a stack trace and drops the user into an interpreter.
+
+"""
+import os
+import code
+import traceback
+import signal
+
+def debug_handler(sig, frame):
+    """Interrupt running process, and provide a python prompt for
+    interactive debugging."""
+    d = {'_frame':frame}         # Allow access to frame object.
+    d.update(frame.f_globals)    # Unless shadowed by global
+    d.update(frame.f_locals)
+
+    i = code.InteractiveConsole(d)
+    message  = "Signal received : entering python shell.\nTraceback:\n"
+    message += ''.join(traceback.format_stack(frame))
+    i.interact(message)
+    os._exit(1)  # Use os._exit to avoid test harness.
+
+
+def register_interrupt_handler():
+    """Register a handler to print a stack trace and enter an interpreter on Ctrl-C"""
+    signal.signal(signal.SIGINT, debug_handler)