add ymake export to ydb

12 files changed, 5370 insertions, 0 deletions

diff --git a/contrib/tools/cython/Cython/Debugger/Cygdb.py b/contrib/tools/cython/Cython/Debugger/Cygdb.py
new file mode 100644
index 0000000000..45f31ce6f7
--- /dev/null
+++ b/contrib/tools/cython/Cython/Debugger/Cygdb.py
@@ -0,0 +1,158 @@
+#!/usr/bin/env python
+
+"""
+The Cython debugger
+
+The current directory should contain a directory named 'cython_debug', or a
+path to the cython project directory should be given (the parent directory of
+cython_debug).
+
+Additional gdb args can be provided only if a path to the project directory is
+given.
+"""
+
+import os
+import sys
+import glob
+import tempfile
+import textwrap
+import subprocess
+import optparse
+import logging
+
+logger = logging.getLogger(__name__)
+
+def make_command_file(path_to_debug_info, prefix_code='', no_import=False):
+    if not no_import:
+        pattern = os.path.join(path_to_debug_info,
+                               'cython_debug',
+                               'cython_debug_info_*')
+        debug_files = glob.glob(pattern)
+
+        if not debug_files:
+            sys.exit('%s.\nNo debug files were found in %s. Aborting.' % (
+                                   usage, os.path.abspath(path_to_debug_info)))
+
+    fd, tempfilename = tempfile.mkstemp()
+    f = os.fdopen(fd, 'w')
+    try:
+        f.write(prefix_code)
+        f.write(textwrap.dedent('''\
+            # This is a gdb command file
+            # See https://sourceware.org/gdb/onlinedocs/gdb/Command-Files.html
+
+            set breakpoint pending on
+            set print pretty on
+
+            python
+            # Activate virtualenv, if we were launched from one
+            import os
+            virtualenv = os.getenv('VIRTUAL_ENV')
+            if virtualenv:
+                path_to_activate_this_py = os.path.join(virtualenv, 'bin', 'activate_this.py')
+                print("gdb command file: Activating virtualenv: %s; path_to_activate_this_py: %s" % (
+                    virtualenv, path_to_activate_this_py))
+                with open(path_to_activate_this_py) as f:
+                    exec(f.read(), dict(__file__=path_to_activate_this_py))
+
+            from Cython.Debugger import libcython, libpython
+            end
+            '''))
+
+        if no_import:
+            # don't do this, this overrides file command in .gdbinit
+            # f.write("file %s\n" % sys.executable)
+            pass
+        else:
+            path = os.path.join(path_to_debug_info, "cython_debug", "interpreter")
+            interpreter_file = open(path)
+            try:
+                interpreter = interpreter_file.read()
+            finally:
+                interpreter_file.close()
+            f.write("file %s\n" % interpreter)
+            f.write('\n'.join('cy import %s\n' % fn for fn in debug_files))
+            f.write(textwrap.dedent('''\
+                python
+                import sys
+                try:
+                    gdb.lookup_type('PyModuleObject')
+                except RuntimeError:
+                    sys.stderr.write(
+                        'Python was not compiled with debug symbols (or it was '
+                        'stripped). Some functionality may not work (properly).\\n')
+                end
+
+                source .cygdbinit
+            '''))
+    finally:
+        f.close()
+
+    return tempfilename
+
+usage = "Usage: cygdb [options] [PATH [-- GDB_ARGUMENTS]]"
+
+def main(path_to_debug_info=None, gdb_argv=None, no_import=False):
+    """
+    Start the Cython debugger. This tells gdb to import the Cython and Python
+    extensions (libcython.py and libpython.py) and it enables gdb's pending
+    breakpoints.
+
+    path_to_debug_info is the path to the Cython build directory
+    gdb_argv is the list of options to gdb
+    no_import tells cygdb whether it should import debug information
+    """
+    parser = optparse.OptionParser(usage=usage)
+    parser.add_option("--gdb-executable",
+        dest="gdb", default='gdb',
+        help="gdb executable to use [default: gdb]")
+    parser.add_option("--verbose", "-v",
+        dest="verbosity", action="count", default=0,
+        help="Verbose mode. Multiple -v options increase the verbosity")
+
+    (options, args) = parser.parse_args()
+    if path_to_debug_info is None:
+        if len(args) > 1:
+            path_to_debug_info = args[0]
+        else:
+            path_to_debug_info = os.curdir
+
+    if gdb_argv is None:
+        gdb_argv = args[1:]
+
+    if path_to_debug_info == '--':
+        no_import = True
+
+    logging_level = logging.WARN
+    if options.verbosity == 1:
+        logging_level = logging.INFO
+    if options.verbosity >= 2:
+        logging_level = logging.DEBUG
+    logging.basicConfig(level=logging_level)
+
+    logger.info("verbosity = %r", options.verbosity)
+    logger.debug("options = %r; args = %r", options, args)
+    logger.debug("Done parsing command-line options. path_to_debug_info = %r, gdb_argv = %r",
+        path_to_debug_info, gdb_argv)
+
+    tempfilename = make_command_file(path_to_debug_info, no_import=no_import)
+    logger.info("Launching %s with command file: %s and gdb_argv: %s",
+        options.gdb, tempfilename, gdb_argv)
+    with open(tempfilename) as tempfile:
+        logger.debug('Command file (%s) contains: """\n%s"""', tempfilename, tempfile.read())
+        logger.info("Spawning %s...", options.gdb)
+        p = subprocess.Popen([options.gdb, '-command', tempfilename] + gdb_argv)
+        logger.info("Spawned %s (pid %d)", options.gdb, p.pid)
+        while True:
+            try:
+                logger.debug("Waiting for gdb (pid %d) to exit...", p.pid)
+                ret = p.wait()
+                logger.debug("Wait for gdb (pid %d) to exit is done. Returned: %r", p.pid, ret)
+            except KeyboardInterrupt:
+                pass
+            else:
+                break
+        logger.debug("Closing temp command file with fd: %s", tempfile.fileno())
+    logger.debug("Removing temp command file: %s", tempfilename)
+    os.remove(tempfilename)
+    logger.debug("Removed temp command file: %s", tempfilename)
diff --git a/contrib/tools/cython/Cython/Debugger/DebugWriter.py b/contrib/tools/cython/Cython/Debugger/DebugWriter.py
new file mode 100644
index 0000000000..876a3a2169
--- /dev/null
+++ b/contrib/tools/cython/Cython/Debugger/DebugWriter.py
@@ -0,0 +1,72 @@
+from __future__ import absolute_import
+
+import os
+import sys
+import errno
+
+try:
+  from lxml import etree
+  have_lxml = True
+except ImportError:
+    have_lxml = False
+    try:
+        from xml.etree import cElementTree as etree
+    except ImportError:
+        try:
+            from xml.etree import ElementTree as etree
+        except ImportError:
+            etree = None
+
+from ..Compiler import Errors
+
+
+class CythonDebugWriter(object):
+    """
+    Class to output debugging information for cygdb
+
+    It writes debug information to cython_debug/cython_debug_info_<modulename>
+    in the build directory.
+    """
+
+    def __init__(self, output_dir):
+        if etree is None:
+            raise Errors.NoElementTreeInstalledException()
+
+        self.output_dir = os.path.join(output_dir or os.curdir, 'cython_debug')
+        self.tb = etree.TreeBuilder()
+        # set by Cython.Compiler.ParseTreeTransforms.DebugTransform
+        self.module_name = None
+        self.start('cython_debug', attrs=dict(version='1.0'))
+
+    def start(self, name, attrs=None):
+        self.tb.start(name, attrs or {})
+
+    def end(self, name):
+        self.tb.end(name)
+
+    def add_entry(self, name, **attrs):
+        self.tb.start(name, attrs)
+        self.tb.end(name)
+
+    def serialize(self):
+        self.tb.end('Module')
+        self.tb.end('cython_debug')
+        xml_root_element = self.tb.close()
+
+        try:
+            os.makedirs(self.output_dir)
+        except OSError as e:
+            if e.errno != errno.EEXIST:
+                raise
+
+        et = etree.ElementTree(xml_root_element)
+        kw = {}
+        if have_lxml:
+            kw['pretty_print'] = True
+
+        fn = "cython_debug_info_" + self.module_name
+        et.write(os.path.join(self.output_dir, fn), encoding="UTF-8", **kw)
+
+        interpreter_path = os.path.join(self.output_dir, 'interpreter')
+        with open(interpreter_path, 'w') as f:
+            f.write(sys.executable)
diff --git a/contrib/tools/cython/Cython/Debugger/Tests/TestLibCython.py b/contrib/tools/cython/Cython/Debugger/Tests/TestLibCython.py
new file mode 100644
index 0000000000..13560646ff
--- /dev/null
+++ b/contrib/tools/cython/Cython/Debugger/Tests/TestLibCython.py
@@ -0,0 +1,274 @@
+
+import os
+import re
+import sys
+import shutil
+import warnings
+import textwrap
+import unittest
+import tempfile
+import subprocess
+#import distutils.core
+#from distutils import sysconfig
+from distutils import ccompiler
+
+import runtests
+import Cython.Distutils.extension
+import Cython.Distutils.old_build_ext as build_ext
+from Cython.Debugger import Cygdb as cygdb
+
+root = os.path.dirname(os.path.abspath(__file__))
+codefile = os.path.join(root, 'codefile')
+cfuncs_file = os.path.join(root, 'cfuncs.c')
+
+with open(codefile) as f:
+    source_to_lineno = dict((line.strip(), i + 1) for i, line in enumerate(f))
+
+
+have_gdb = None
+def test_gdb():
+    global have_gdb
+    if have_gdb is not None:
+        return have_gdb
+
+    have_gdb = False
+    try:
+        p = subprocess.Popen(['gdb', '-nx', '--version'], stdout=subprocess.PIPE)
+    except OSError:
+        # gdb not found
+        gdb_version = None
+    else:
+        stdout, _ = p.communicate()
+        # Based on Lib/test/test_gdb.py
+        regex = r"GNU gdb [^\d]*(\d+)\.(\d+)"
+        gdb_version = re.match(regex, stdout.decode('ascii', 'ignore'))
+
+    if gdb_version:
+        gdb_version_number = list(map(int, gdb_version.groups()))
+        if gdb_version_number >= [7, 2]:
+            have_gdb = True
+            with tempfile.NamedTemporaryFile(mode='w+') as python_version_script:
+                python_version_script.write(
+                    'python import sys; print("%s %s" % sys.version_info[:2])')
+                python_version_script.flush()
+                p = subprocess.Popen(['gdb', '-batch', '-x', python_version_script.name],
+                                     stdout=subprocess.PIPE)
+                stdout, _ = p.communicate()
+                try:
+                    internal_python_version = list(map(int, stdout.decode('ascii', 'ignore').split()))
+                    if internal_python_version < [2, 6]:
+                        have_gdb = False
+                except ValueError:
+                    have_gdb = False
+
+    if not have_gdb:
+        warnings.warn('Skipping gdb tests, need gdb >= 7.2 with Python >= 2.6')
+
+    return have_gdb
+
+
+class DebuggerTestCase(unittest.TestCase):
+
+    def setUp(self):
+        """
+        Run gdb and have cygdb import the debug information from the code
+        defined in TestParseTreeTransforms's setUp method
+        """
+        if not test_gdb():
+            return
+
+        self.tempdir = tempfile.mkdtemp()
+        self.destfile = os.path.join(self.tempdir, 'codefile.pyx')
+        self.debug_dest = os.path.join(self.tempdir,
+                                      'cython_debug',
+                                      'cython_debug_info_codefile')
+        self.cfuncs_destfile = os.path.join(self.tempdir, 'cfuncs')
+
+        self.cwd = os.getcwd()
+        try:
+            os.chdir(self.tempdir)
+
+            shutil.copy(codefile, self.destfile)
+            shutil.copy(cfuncs_file, self.cfuncs_destfile + '.c')
+            shutil.copy(cfuncs_file.replace('.c', '.h'),
+                        self.cfuncs_destfile + '.h')
+
+            compiler = ccompiler.new_compiler()
+            compiler.compile(['cfuncs.c'], debug=True, extra_postargs=['-fPIC'])
+
+            opts = dict(
+                test_directory=self.tempdir,
+                module='codefile',
+            )
+
+            optimization_disabler = build_ext.Optimization()
+
+            cython_compile_testcase = runtests.CythonCompileTestCase(
+                workdir=self.tempdir,
+                # we clean up everything (not only compiled files)
+                cleanup_workdir=False,
+                tags=runtests.parse_tags(codefile),
+                **opts
+            )
+
+
+            new_stderr = open(os.devnull, 'w')
+
+            stderr = sys.stderr
+            sys.stderr = new_stderr
+
+            optimization_disabler.disable_optimization()
+            try:
+                cython_compile_testcase.run_cython(
+                    targetdir=self.tempdir,
+                    incdir=None,
+                    annotate=False,
+                    extra_compile_options={
+                        'gdb_debug':True,
+                        'output_dir':self.tempdir,
+                    },
+                    **opts
+                )
+
+                cython_compile_testcase.run_distutils(
+                    incdir=None,
+                    workdir=self.tempdir,
+                    extra_extension_args={'extra_objects':['cfuncs.o']},
+                    **opts
+                )
+            finally:
+                optimization_disabler.restore_state()
+                sys.stderr = stderr
+                new_stderr.close()
+
+            # ext = Cython.Distutils.extension.Extension(
+                # 'codefile',
+                # ['codefile.pyx'],
+                # cython_gdb=True,
+                # extra_objects=['cfuncs.o'])
+            #
+            # distutils.core.setup(
+                # script_args=['build_ext', '--inplace'],
+                # ext_modules=[ext],
+                # cmdclass=dict(build_ext=Cython.Distutils.build_ext)
+            # )
+
+        except:
+            os.chdir(self.cwd)
+            raise
+
+    def tearDown(self):
+        if not test_gdb():
+            return
+        os.chdir(self.cwd)
+        shutil.rmtree(self.tempdir)
+
+
+class GdbDebuggerTestCase(DebuggerTestCase):
+
+    def setUp(self):
+        if not test_gdb():
+            return
+
+        super(GdbDebuggerTestCase, self).setUp()
+
+        prefix_code = textwrap.dedent('''\
+            python
+
+            import os
+            import sys
+            import traceback
+
+            def excepthook(type, value, tb):
+                traceback.print_exception(type, value, tb)
+                sys.stderr.flush()
+                sys.stdout.flush()
+                os._exit(1)
+
+            sys.excepthook = excepthook
+
+            # Have tracebacks end up on sys.stderr (gdb replaces sys.stderr
+            # with an object that calls gdb.write())
+            sys.stderr = sys.__stderr__
+
+            end
+            ''')
+
+        code = textwrap.dedent('''\
+            python
+
+            from Cython.Debugger.Tests import test_libcython_in_gdb
+            test_libcython_in_gdb.main(version=%r)
+
+            end
+            ''' % (sys.version_info[:2],))
+
+        self.gdb_command_file = cygdb.make_command_file(self.tempdir,
+                                                        prefix_code)
+
+        with open(self.gdb_command_file, 'a') as f:
+            f.write(code)
+
+        args = ['gdb', '-batch', '-x', self.gdb_command_file, '-n', '--args',
+                sys.executable, '-c', 'import codefile']
+
+        paths = []
+        path = os.environ.get('PYTHONPATH')
+        if path:
+            paths.append(path)
+        paths.append(os.path.dirname(os.path.dirname(
+            os.path.abspath(Cython.__file__))))
+        env = dict(os.environ, PYTHONPATH=os.pathsep.join(paths))
+
+        self.p = subprocess.Popen(
+            args,
+            stdout=subprocess.PIPE,
+            stderr=subprocess.PIPE,
+            env=env)
+
+    def tearDown(self):
+        if not test_gdb():
+            return
+
+        try:
+            super(GdbDebuggerTestCase, self).tearDown()
+            if self.p:
+                try: self.p.stdout.close()
+                except: pass
+                try: self.p.stderr.close()
+                except: pass
+                self.p.wait()
+        finally:
+            os.remove(self.gdb_command_file)
+
+
+class TestAll(GdbDebuggerTestCase):
+
+    def test_all(self):
+        if not test_gdb():
+            return
+
+        out, err = self.p.communicate()
+        out = out.decode('UTF-8')
+        err = err.decode('UTF-8')
+
+        exit_status = self.p.returncode
+
+        if exit_status == 1:
+            sys.stderr.write(out)
+            sys.stderr.write(err)
+        elif exit_status >= 2:
+            border = u'*' * 30
+            start  = u'%s   v INSIDE GDB v   %s' % (border, border)
+            stderr = u'%s   v STDERR v   %s' % (border, border)
+            end    = u'%s   ^ INSIDE GDB ^   %s' % (border, border)
+            errmsg = u'\n%s\n%s%s\n%s%s' % (start, out, stderr, err, end)
+
+            sys.stderr.write(errmsg)
+
+        # FIXME: re-enable this to make the test fail on internal failures
+        #self.assertEqual(exit_status, 0)
+
+
+if __name__ == '__main__':
+    unittest.main()
diff --git a/contrib/tools/cython/Cython/Debugger/Tests/__init__.py b/contrib/tools/cython/Cython/Debugger/Tests/__init__.py
new file mode 100644
index 0000000000..fa81adaff6
--- /dev/null
+++ b/contrib/tools/cython/Cython/Debugger/Tests/__init__.py
@@ -0,0 +1 @@
+# empty file
diff --git a/contrib/tools/cython/Cython/Debugger/Tests/cfuncs.c b/contrib/tools/cython/Cython/Debugger/Tests/cfuncs.c
new file mode 100644
index 0000000000..ccb42050bf
--- /dev/null
+++ b/contrib/tools/cython/Cython/Debugger/Tests/cfuncs.c
@@ -0,0 +1,8 @@
+void
+some_c_function(void)
+{
+    int a, b, c;
+
+    a = 1;
+    b = 2;
+}
diff --git a/contrib/tools/cython/Cython/Debugger/Tests/cfuncs.h b/contrib/tools/cython/Cython/Debugger/Tests/cfuncs.h
new file mode 100644
index 0000000000..3b21bc2d5f
--- /dev/null
+++ b/contrib/tools/cython/Cython/Debugger/Tests/cfuncs.h
@@ -0,0 +1 @@
+void some_c_function(void);
diff --git a/contrib/tools/cython/Cython/Debugger/Tests/codefile b/contrib/tools/cython/Cython/Debugger/Tests/codefile
new file mode 100644
index 0000000000..6b4c6b6add
--- /dev/null
+++ b/contrib/tools/cython/Cython/Debugger/Tests/codefile
@@ -0,0 +1,50 @@
+cdef extern from "stdio.h":
+    int puts(char *s)
+
+cdef extern from "cfuncs.h":
+    void some_c_function()
+
+import os
+
+cdef int c_var = 12
+python_var = 13
+
+def spam(a=0):
+    cdef:
+        int b, c
+
+    b = c = d = 0
+
+    b = 1
+    c = 2
+    int(10)
+    puts("spam")
+    os.path.join("foo", "bar")
+    some_c_function()
+
+cpdef eggs():
+    pass
+
+cdef ham():
+    pass
+
+cdef class SomeClass(object):
+    def spam(self):
+        pass
+
+def outer():
+    cdef object a = "an object"
+    def inner():
+        b = 2
+        # access closed over variables
+        print a, b
+    return inner
+
+
+outer()()
+
+spam()
+print "bye!"
+
+def use_ham():
+    ham()
diff --git a/contrib/tools/cython/Cython/Debugger/Tests/test_libcython_in_gdb.py b/contrib/tools/cython/Cython/Debugger/Tests/test_libcython_in_gdb.py
new file mode 100644
index 0000000000..bd7608d607
--- /dev/null
+++ b/contrib/tools/cython/Cython/Debugger/Tests/test_libcython_in_gdb.py
@@ -0,0 +1,496 @@
+"""
+Tests that run inside GDB.
+
+Note: debug information is already imported by the file generated by
+Cython.Debugger.Cygdb.make_command_file()
+"""
+
+from __future__ import absolute_import
+
+import os
+import re
+import sys
+import trace
+import inspect
+import warnings
+import unittest
+import textwrap
+import tempfile
+import functools
+import traceback
+import itertools
+#from test import test_support
+
+import gdb
+
+from .. import libcython
+from .. import libpython
+from . import TestLibCython as test_libcython
+from ...Utils import add_metaclass
+
+# for some reason sys.argv is missing in gdb
+sys.argv = ['gdb']
+
+
+def print_on_call_decorator(func):
+    @functools.wraps(func)
+    def wrapper(self, *args, **kwargs):
+        _debug(type(self).__name__, func.__name__)
+
+        try:
+            return func(self, *args, **kwargs)
+        except Exception:
+            _debug("An exception occurred:", traceback.format_exc())
+            raise
+
+    return wrapper
+
+class TraceMethodCallMeta(type):
+
+    def __init__(self, name, bases, dict):
+        for func_name, func in dict.items():
+            if inspect.isfunction(func):
+                setattr(self, func_name, print_on_call_decorator(func))
+
+
+@add_metaclass(TraceMethodCallMeta)
+class DebugTestCase(unittest.TestCase):
+    """
+    Base class for test cases. On teardown it kills the inferior and unsets
+    all breakpoints.
+    """
+
+    def __init__(self, name):
+        super(DebugTestCase, self).__init__(name)
+        self.cy = libcython.cy
+        self.module = libcython.cy.cython_namespace['codefile']
+        self.spam_func, self.spam_meth = libcython.cy.functions_by_name['spam']
+        self.ham_func = libcython.cy.functions_by_qualified_name[
+            'codefile.ham']
+        self.eggs_func = libcython.cy.functions_by_qualified_name[
+            'codefile.eggs']
+
+    def read_var(self, varname, cast_to=None):
+        result = gdb.parse_and_eval('$cy_cvalue("%s")' % varname)
+        if cast_to:
+            result = cast_to(result)
+
+        return result
+
+    def local_info(self):
+        return gdb.execute('info locals', to_string=True)
+
+    def lineno_equals(self, source_line=None, lineno=None):
+        if source_line is not None:
+            lineno = test_libcython.source_to_lineno[source_line]
+        frame = gdb.selected_frame()
+        self.assertEqual(libcython.cython_info.lineno(frame), lineno)
+
+    def break_and_run(self, source_line):
+        break_lineno = test_libcython.source_to_lineno[source_line]
+        gdb.execute('cy break codefile:%d' % break_lineno, to_string=True)
+        gdb.execute('run', to_string=True)
+
+    def tearDown(self):
+        gdb.execute('delete breakpoints', to_string=True)
+        try:
+            gdb.execute('kill inferior 1', to_string=True)
+        except RuntimeError:
+            pass
+
+        gdb.execute('set args -c "import codefile"')
+
+
+class TestDebugInformationClasses(DebugTestCase):
+
+    def test_CythonModule(self):
+        "test that debug information was parsed properly into data structures"
+        self.assertEqual(self.module.name, 'codefile')
+        global_vars = ('c_var', 'python_var', '__name__',
+                       '__builtins__', '__doc__', '__file__')
+        assert set(global_vars).issubset(self.module.globals)
+
+    def test_CythonVariable(self):
+        module_globals = self.module.globals
+        c_var = module_globals['c_var']
+        python_var = module_globals['python_var']
+        self.assertEqual(c_var.type, libcython.CObject)
+        self.assertEqual(python_var.type, libcython.PythonObject)
+        self.assertEqual(c_var.qualified_name, 'codefile.c_var')
+
+    def test_CythonFunction(self):
+        self.assertEqual(self.spam_func.qualified_name, 'codefile.spam')
+        self.assertEqual(self.spam_meth.qualified_name,
+                         'codefile.SomeClass.spam')
+        self.assertEqual(self.spam_func.module, self.module)
+
+        assert self.eggs_func.pf_cname, (self.eggs_func, self.eggs_func.pf_cname)
+        assert not self.ham_func.pf_cname
+        assert not self.spam_func.pf_cname
+        assert not self.spam_meth.pf_cname
+
+        self.assertEqual(self.spam_func.type, libcython.CObject)
+        self.assertEqual(self.ham_func.type, libcython.CObject)
+
+        self.assertEqual(self.spam_func.arguments, ['a'])
+        self.assertEqual(self.spam_func.step_into_functions,
+                         set(['puts', 'some_c_function']))
+
+        expected_lineno = test_libcython.source_to_lineno['def spam(a=0):']
+        self.assertEqual(self.spam_func.lineno, expected_lineno)
+        self.assertEqual(sorted(self.spam_func.locals), list('abcd'))
+
+
+class TestParameters(unittest.TestCase):
+
+    def test_parameters(self):
+        gdb.execute('set cy_colorize_code on')
+        assert libcython.parameters.colorize_code
+        gdb.execute('set cy_colorize_code off')
+        assert not libcython.parameters.colorize_code
+
+
+class TestBreak(DebugTestCase):
+
+    def test_break(self):
+        breakpoint_amount = len(gdb.breakpoints() or ())
+        gdb.execute('cy break codefile.spam')
+
+        self.assertEqual(len(gdb.breakpoints()), breakpoint_amount + 1)
+        bp = gdb.breakpoints()[-1]
+        self.assertEqual(bp.type, gdb.BP_BREAKPOINT)
+        assert self.spam_func.cname in bp.location
+        assert bp.enabled
+
+    def test_python_break(self):
+        gdb.execute('cy break -p join')
+        assert 'def join(' in gdb.execute('cy run', to_string=True)
+
+    def test_break_lineno(self):
+        beginline = 'import os'
+        nextline = 'cdef int c_var = 12'
+
+        self.break_and_run(beginline)
+        self.lineno_equals(beginline)
+        step_result = gdb.execute('cy step', to_string=True)
+        self.lineno_equals(nextline)
+        assert step_result.rstrip().endswith(nextline)
+
+
+class TestKilled(DebugTestCase):
+
+    def test_abort(self):
+        gdb.execute("set args -c 'import os; os.abort()'")
+        output = gdb.execute('cy run', to_string=True)
+        assert 'abort' in output.lower()
+
+
+class DebugStepperTestCase(DebugTestCase):
+
+    def step(self, varnames_and_values, source_line=None, lineno=None):
+        gdb.execute(self.command)
+        for varname, value in varnames_and_values:
+            self.assertEqual(self.read_var(varname), value, self.local_info())
+
+        self.lineno_equals(source_line, lineno)
+
+
+class TestStep(DebugStepperTestCase):
+    """
+    Test stepping. Stepping happens in the code found in
+    Cython/Debugger/Tests/codefile.
+    """
+
+    def test_cython_step(self):
+        gdb.execute('cy break codefile.spam')
+
+        gdb.execute('run', to_string=True)
+        self.lineno_equals('def spam(a=0):')
+
+        gdb.execute('cy step', to_string=True)
+        self.lineno_equals('b = c = d = 0')
+
+        self.command = 'cy step'
+        self.step([('b', 0)], source_line='b = 1')
+        self.step([('b', 1), ('c', 0)], source_line='c = 2')
+        self.step([('c', 2)], source_line='int(10)')
+        self.step([], source_line='puts("spam")')
+
+        gdb.execute('cont', to_string=True)
+        self.assertEqual(len(gdb.inferiors()), 1)
+        self.assertEqual(gdb.inferiors()[0].pid, 0)
+
+    def test_c_step(self):
+        self.break_and_run('some_c_function()')
+        gdb.execute('cy step', to_string=True)
+        self.assertEqual(gdb.selected_frame().name(), 'some_c_function')
+
+    def test_python_step(self):
+        self.break_and_run('os.path.join("foo", "bar")')
+
+        result = gdb.execute('cy step', to_string=True)
+
+        curframe = gdb.selected_frame()
+        self.assertEqual(curframe.name(), 'PyEval_EvalFrameEx')
+
+        pyframe = libpython.Frame(curframe).get_pyop()
+        # With Python 3 inferiors, pyframe.co_name will return a PyUnicodePtr,
+        # be compatible
+        frame_name = pyframe.co_name.proxyval(set())
+        self.assertEqual(frame_name, 'join')
+        assert re.match(r'\d+    def join\(', result), result
+
+
+class TestNext(DebugStepperTestCase):
+
+    def test_cython_next(self):
+        self.break_and_run('c = 2')
+
+        lines = (
+            'int(10)',
+            'puts("spam")',
+            'os.path.join("foo", "bar")',
+            'some_c_function()',
+        )
+
+        for line in lines:
+            gdb.execute('cy next')
+            self.lineno_equals(line)
+
+
+class TestLocalsGlobals(DebugTestCase):
+
+    def test_locals(self):
+        self.break_and_run('int(10)')
+
+        result = gdb.execute('cy locals', to_string=True)
+        assert 'a = 0', repr(result)
+        assert 'b = (int) 1', result
+        assert 'c = (int) 2' in result, repr(result)
+
+    def test_globals(self):
+        self.break_and_run('int(10)')
+
+        result = gdb.execute('cy globals', to_string=True)
+        assert '__name__ ' in result, repr(result)
+        assert '__doc__ ' in result, repr(result)
+        assert 'os ' in result, repr(result)
+        assert 'c_var ' in result, repr(result)
+        assert 'python_var ' in result, repr(result)
+
+
+class TestBacktrace(DebugTestCase):
+
+    def test_backtrace(self):
+        libcython.parameters.colorize_code.value = False
+
+        self.break_and_run('os.path.join("foo", "bar")')
+
+        def match_backtrace_output(result):
+            assert re.search(r'\#\d+ *0x.* in spam\(\) at .*codefile\.pyx:22',
+                             result), result
+            assert 'os.path.join("foo", "bar")' in result, result
+
+        result = gdb.execute('cy bt', to_string=True)
+        match_backtrace_output(result)
+
+        result = gdb.execute('cy bt -a', to_string=True)
+        match_backtrace_output(result)
+
+        # Apparently not everyone has main()
+        # assert re.search(r'\#0 *0x.* in main\(\)', result), result
+
+
+class TestFunctions(DebugTestCase):
+
+    def test_functions(self):
+        self.break_and_run('c = 2')
+        result = gdb.execute('print $cy_cname("b")', to_string=True)
+        assert re.search('__pyx_.*b', result), result
+
+        result = gdb.execute('print $cy_lineno()', to_string=True)
+        supposed_lineno = test_libcython.source_to_lineno['c = 2']
+        assert str(supposed_lineno) in result, (supposed_lineno, result)
+
+        result = gdb.execute('print $cy_cvalue("b")', to_string=True)
+        assert '= 1' in result
+
+
+class TestPrint(DebugTestCase):
+
+    def test_print(self):
+        self.break_and_run('c = 2')
+        result = gdb.execute('cy print b', to_string=True)
+        self.assertEqual('b = (int) 1\n', result)
+
+
+class TestUpDown(DebugTestCase):
+
+    def test_updown(self):
+        self.break_and_run('os.path.join("foo", "bar")')
+        gdb.execute('cy step')
+        self.assertRaises(RuntimeError, gdb.execute, 'cy down')
+
+        result = gdb.execute('cy up', to_string=True)
+        assert 'spam()' in result
+        assert 'os.path.join("foo", "bar")' in result
+
+
+class TestExec(DebugTestCase):
+
+    def setUp(self):
+        super(TestExec, self).setUp()
+        self.fd, self.tmpfilename = tempfile.mkstemp()
+        self.tmpfile = os.fdopen(self.fd, 'r+')
+
+    def tearDown(self):
+        super(TestExec, self).tearDown()
+
+        try:
+            self.tmpfile.close()
+        finally:
+            os.remove(self.tmpfilename)
+
+    def eval_command(self, command):
+        gdb.execute('cy exec open(%r, "w").write(str(%s))' %
+                                                (self.tmpfilename, command))
+        return self.tmpfile.read().strip()
+
+    def test_cython_exec(self):
+        self.break_and_run('os.path.join("foo", "bar")')
+
+        # test normal behaviour
+        self.assertEqual("[0]", self.eval_command('[a]'))
+
+        # test multiline code
+        result = gdb.execute(textwrap.dedent('''\
+            cy exec
+            pass
+
+            "nothing"
+            end
+            '''))
+        result = self.tmpfile.read().rstrip()
+        self.assertEqual('', result)
+
+    def test_python_exec(self):
+        self.break_and_run('os.path.join("foo", "bar")')
+        gdb.execute('cy step')
+
+        gdb.execute('cy exec some_random_var = 14')
+        self.assertEqual('14', self.eval_command('some_random_var'))
+
+
+class CySet(DebugTestCase):
+
+    def test_cyset(self):
+        self.break_and_run('os.path.join("foo", "bar")')
+
+        gdb.execute('cy set a = $cy_eval("{None: []}")')
+        stringvalue = self.read_var("a", cast_to=str)
+        self.assertEqual(stringvalue, "{None: []}")
+
+
+class TestCyEval(DebugTestCase):
+    "Test the $cy_eval() gdb function."
+
+    def test_cy_eval(self):
+        # This function leaks a few objects in the GDB python process. This
+        # is no biggie
+        self.break_and_run('os.path.join("foo", "bar")')
+
+        result = gdb.execute('print $cy_eval("None")', to_string=True)
+        assert re.match(r'\$\d+ = None\n', result), result
+
+        result = gdb.execute('print $cy_eval("[a]")', to_string=True)
+        assert re.match(r'\$\d+ = \[0\]', result), result
+
+
+class TestClosure(DebugTestCase):
+
+    def break_and_run_func(self, funcname):
+        gdb.execute('cy break ' + funcname)
+        gdb.execute('cy run')
+
+    def test_inner(self):
+        self.break_and_run_func('inner')
+        self.assertEqual('', gdb.execute('cy locals', to_string=True))
+
+        # Allow the Cython-generated code to initialize the scope variable
+        gdb.execute('cy step')
+
+        self.assertEqual(str(self.read_var('a')), "'an object'")
+        print_result = gdb.execute('cy print a', to_string=True).strip()
+        self.assertEqual(print_result, "a = 'an object'")
+
+    def test_outer(self):
+        self.break_and_run_func('outer')
+        self.assertEqual('', gdb.execute('cy locals', to_string=True))
+
+        # Initialize scope with 'a' uninitialized
+        gdb.execute('cy step')
+        self.assertEqual('', gdb.execute('cy locals', to_string=True))
+
+        # Initialize 'a' to 1
+        gdb.execute('cy step')
+        print_result = gdb.execute('cy print a', to_string=True).strip()
+        self.assertEqual(print_result, "a = 'an object'")
+
+
+_do_debug = os.environ.get('GDB_DEBUG')
+if _do_debug:
+    _debug_file = open('/dev/tty', 'w')
+
+def _debug(*messages):
+    if _do_debug:
+        messages = itertools.chain([sys._getframe(1).f_code.co_name, ':'],
+                                   messages)
+        _debug_file.write(' '.join(str(msg) for msg in messages) + '\n')
+
+
+def run_unittest_in_module(modulename):
+    try:
+        gdb.lookup_type('PyModuleObject')
+    except RuntimeError:
+        msg = ("Unable to run tests, Python was not compiled with "
+                "debugging information. Either compile python with "
+                "-g or get a debug build (configure with --with-pydebug).")
+        warnings.warn(msg)
+        os._exit(1)
+    else:
+        m = __import__(modulename, fromlist=[''])
+        tests = inspect.getmembers(m, inspect.isclass)
+
+        # test_support.run_unittest(tests)
+
+        test_loader = unittest.TestLoader()
+        suite = unittest.TestSuite(
+            [test_loader.loadTestsFromTestCase(cls) for name, cls in tests])
+
+        result = unittest.TextTestRunner(verbosity=1).run(suite)
+        return result.wasSuccessful()
+
+def runtests():
+    """
+    Run the libcython and libpython tests. Ensure that an appropriate status is
+    returned to the parent test process.
+    """
+    from Cython.Debugger.Tests import test_libpython_in_gdb
+
+    success_libcython = run_unittest_in_module(__name__)
+    success_libpython = run_unittest_in_module(test_libpython_in_gdb.__name__)
+
+    if not success_libcython or not success_libpython:
+        sys.exit(2)
+
+def main(version, trace_code=False):
+    global inferior_python_version
+
+    inferior_python_version = version
+
+    if trace_code:
+        tracer = trace.Trace(count=False, trace=True, outfile=sys.stderr,
+                            ignoredirs=[sys.prefix, sys.exec_prefix])
+        tracer.runfunc(runtests)
+    else:
+        runtests()
diff --git a/contrib/tools/cython/Cython/Debugger/Tests/test_libpython_in_gdb.py b/contrib/tools/cython/Cython/Debugger/Tests/test_libpython_in_gdb.py
new file mode 100644
index 0000000000..6f34cee47b
--- /dev/null
+++ b/contrib/tools/cython/Cython/Debugger/Tests/test_libpython_in_gdb.py
@@ -0,0 +1,115 @@
+# -*- coding: UTF-8 -*-
+
+"""
+Test libpython.py. This is already partly tested by test_libcython_in_gdb and
+Lib/test/test_gdb.py in the Python source. These tests are run in gdb and
+called from test_libcython_in_gdb.main()
+"""
+
+import os
+import sys
+
+import gdb
+
+from Cython.Debugger import libcython
+from Cython.Debugger import libpython
+
+from . import test_libcython_in_gdb
+from .test_libcython_in_gdb import _debug, inferior_python_version
+
+
+class TestPrettyPrinters(test_libcython_in_gdb.DebugTestCase):
+    """
+    Test whether types of Python objects are correctly inferred and that
+    the right libpython.PySomeTypeObjectPtr classes are instantiated.
+
+    Also test whether values are appropriately formatted (don't be too
+    laborious as Lib/test/test_gdb.py already covers this extensively).
+
+    Don't take care of decreffing newly allocated objects as a new
+    interpreter is started for every test anyway.
+    """
+
+    def setUp(self):
+        super(TestPrettyPrinters, self).setUp()
+        self.break_and_run('b = c = d = 0')
+
+    def get_pyobject(self, code):
+        value = gdb.parse_and_eval(code)
+        assert libpython.pointervalue(value) != 0
+        return value
+
+    def pyobject_fromcode(self, code, gdbvar=None):
+        if gdbvar is not None:
+            d = {'varname':gdbvar, 'code':code}
+            gdb.execute('set $%(varname)s = %(code)s' % d)
+            code = '$' + gdbvar
+
+        return libpython.PyObjectPtr.from_pyobject_ptr(self.get_pyobject(code))
+
+    def get_repr(self, pyobject):
+        return pyobject.get_truncated_repr(libpython.MAX_OUTPUT_LEN)
+
+    def alloc_bytestring(self, string, gdbvar=None):
+        if inferior_python_version < (3, 0):
+            funcname = 'PyString_FromStringAndSize'
+        else:
+            funcname = 'PyBytes_FromStringAndSize'
+
+        assert b'"' not in string
+
+        # ensure double quotes
+        code = '(PyObject *) %s("%s", %d)' % (funcname, string.decode('iso8859-1'), len(string))
+        return self.pyobject_fromcode(code, gdbvar=gdbvar)
+
+    def alloc_unicodestring(self, string, gdbvar=None):
+        postfix = libpython.get_inferior_unicode_postfix()
+        funcname = 'PyUnicode%s_DecodeUnicodeEscape' % (postfix,)
+
+        data = string.encode("unicode_escape").decode('iso8859-1')
+        return self.pyobject_fromcode(
+            '(PyObject *) %s("%s", %d, "strict")' % (
+                funcname, data.replace('"', r'\"').replace('\\', r'\\'), len(data)),
+            gdbvar=gdbvar)
+
+    def test_bytestring(self):
+        bytestring = self.alloc_bytestring(b"spam")
+
+        if inferior_python_version < (3, 0):
+            bytestring_class = libpython.PyStringObjectPtr
+            expected = repr(b"spam")
+        else:
+            bytestring_class = libpython.PyBytesObjectPtr
+            expected = "b'spam'"
+
+        self.assertEqual(type(bytestring), bytestring_class)
+        self.assertEqual(self.get_repr(bytestring), expected)
+
+    def test_unicode(self):
+        unicode_string = self.alloc_unicodestring(u"spam ἄλφα")
+
+        expected = u"'spam ἄλφα'"
+        if inferior_python_version < (3, 0):
+            expected = 'u' + expected
+
+        self.assertEqual(type(unicode_string), libpython.PyUnicodeObjectPtr)
+        self.assertEqual(self.get_repr(unicode_string), expected)
+
+    def test_int(self):
+        if inferior_python_version < (3, 0):
+            intval = self.pyobject_fromcode('PyInt_FromLong(100)')
+            self.assertEqual(type(intval), libpython.PyIntObjectPtr)
+            self.assertEqual(self.get_repr(intval), '100')
+
+    def test_long(self):
+        longval = self.pyobject_fromcode('PyLong_FromLong(200)',
+                                         gdbvar='longval')
+        assert gdb.parse_and_eval('$longval->ob_type == &PyLong_Type')
+
+        self.assertEqual(type(longval), libpython.PyLongObjectPtr)
+        self.assertEqual(self.get_repr(longval), '200')
+
+    def test_frame_type(self):
+        frame = self.pyobject_fromcode('PyEval_GetFrame()')
+
+        self.assertEqual(type(frame), libpython.PyFrameObjectPtr)
diff --git a/contrib/tools/cython/Cython/Debugger/__init__.py b/contrib/tools/cython/Cython/Debugger/__init__.py
new file mode 100644
index 0000000000..fa81adaff6
--- /dev/null
+++ b/contrib/tools/cython/Cython/Debugger/__init__.py
@@ -0,0 +1 @@
+# empty file
diff --git a/contrib/tools/cython/Cython/Debugger/libcython.py b/contrib/tools/cython/Cython/Debugger/libcython.py
new file mode 100644
index 0000000000..23153789b6
--- /dev/null
+++ b/contrib/tools/cython/Cython/Debugger/libcython.py
@@ -0,0 +1,1434 @@
+"""
+GDB extension that adds Cython support.
+"""
+
+from __future__ import print_function
+
+try:
+    input = raw_input
+except NameError:
+    pass
+
+import sys
+import textwrap
+import traceback
+import functools
+import itertools
+import collections
+
+import gdb
+
+try:  # python 2
+    UNICODE = unicode
+    BYTES = str
+except NameError:  # python 3
+    UNICODE = str
+    BYTES = bytes
+
+try:
+    from lxml import etree
+    have_lxml = True
+except ImportError:
+    have_lxml = False
+    try:
+        # Python 2.5
+        from xml.etree import cElementTree as etree
+    except ImportError:
+        try:
+            # Python 2.5
+            from xml.etree import ElementTree as etree
+        except ImportError:
+            try:
+                # normal cElementTree install
+                import cElementTree as etree
+            except ImportError:
+                # normal ElementTree install
+                import elementtree.ElementTree as etree
+
+try:
+    import pygments.lexers
+    import pygments.formatters
+except ImportError:
+    pygments = None
+    sys.stderr.write("Install pygments for colorized source code.\n")
+
+if hasattr(gdb, 'string_to_argv'):
+    from gdb import string_to_argv
+else:
+    from shlex import split as string_to_argv
+
+from Cython.Debugger import libpython
+
+# C or Python type
+CObject = 'CObject'
+PythonObject = 'PythonObject'
+
+_data_types = dict(CObject=CObject, PythonObject=PythonObject)
+_filesystemencoding = sys.getfilesystemencoding() or 'UTF-8'
+
+
+# decorators
+
+def dont_suppress_errors(function):
+    "*sigh*, readline"
+    @functools.wraps(function)
+    def wrapper(*args, **kwargs):
+        try:
+            return function(*args, **kwargs)
+        except Exception:
+            traceback.print_exc()
+            raise
+
+    return wrapper
+
+
+def default_selected_gdb_frame(err=True):
+    def decorator(function):
+        @functools.wraps(function)
+        def wrapper(self, frame=None, *args, **kwargs):
+            try:
+                frame = frame or gdb.selected_frame()
+            except RuntimeError:
+                raise gdb.GdbError("No frame is currently selected.")
+
+            if err and frame.name() is None:
+                raise NoFunctionNameInFrameError()
+
+            return function(self, frame, *args, **kwargs)
+        return wrapper
+    return decorator
+
+
+def require_cython_frame(function):
+    @functools.wraps(function)
+    @require_running_program
+    def wrapper(self, *args, **kwargs):
+        frame = kwargs.get('frame') or gdb.selected_frame()
+        if not self.is_cython_function(frame):
+            raise gdb.GdbError('Selected frame does not correspond with a '
+                               'Cython function we know about.')
+        return function(self, *args, **kwargs)
+    return wrapper
+
+
+def dispatch_on_frame(c_command, python_command=None):
+    def decorator(function):
+        @functools.wraps(function)
+        def wrapper(self, *args, **kwargs):
+            is_cy = self.is_cython_function()
+            is_py = self.is_python_function()
+
+            if is_cy or (is_py and not python_command):
+                function(self, *args, **kwargs)
+            elif is_py:
+                gdb.execute(python_command)
+            elif self.is_relevant_function():
+                gdb.execute(c_command)
+            else:
+                raise gdb.GdbError("Not a function cygdb knows about. "
+                                   "Use the normal GDB commands instead.")
+
+        return wrapper
+    return decorator
+
+
+def require_running_program(function):
+    @functools.wraps(function)
+    def wrapper(*args, **kwargs):
+        try:
+            gdb.selected_frame()
+        except RuntimeError:
+            raise gdb.GdbError("No frame is currently selected.")
+
+        return function(*args, **kwargs)
+    return wrapper
+
+
+def gdb_function_value_to_unicode(function):
+    @functools.wraps(function)
+    def wrapper(self, string, *args, **kwargs):
+        if isinstance(string, gdb.Value):
+            string = string.string()
+
+        return function(self, string, *args, **kwargs)
+    return wrapper
+
+
+# Classes that represent the debug information
+# Don't rename the parameters of these classes, they come directly from the XML
+
+class CythonModule(object):
+    def __init__(self, module_name, filename, c_filename):
+        self.name = module_name
+        self.filename = filename
+        self.c_filename = c_filename
+        self.globals = {}
+        # {cython_lineno: min(c_linenos)}
+        self.lineno_cy2c = {}
+        # {c_lineno: cython_lineno}
+        self.lineno_c2cy = {}
+        self.functions = {}
+
+
+class CythonVariable(object):
+
+    def __init__(self, name, cname, qualified_name, type, lineno):
+        self.name = name
+        self.cname = cname
+        self.qualified_name = qualified_name
+        self.type = type
+        self.lineno = int(lineno)
+
+
+class CythonFunction(CythonVariable):
+    def __init__(self,
+                 module,
+                 name,
+                 cname,
+                 pf_cname,
+                 qualified_name,
+                 lineno,
+                 type=CObject,
+                 is_initmodule_function="False"):
+        super(CythonFunction, self).__init__(name,
+                                             cname,
+                                             qualified_name,
+                                             type,
+                                             lineno)
+        self.module = module
+        self.pf_cname = pf_cname
+        self.is_initmodule_function = is_initmodule_function == "True"
+        self.locals = {}
+        self.arguments = []
+        self.step_into_functions = set()
+
+
+# General purpose classes
+
+class CythonBase(object):
+
+    @default_selected_gdb_frame(err=False)
+    def is_cython_function(self, frame):
+        return frame.name() in self.cy.functions_by_cname
+
+    @default_selected_gdb_frame(err=False)
+    def is_python_function(self, frame):
+        """
+        Tells if a frame is associated with a Python function.
+        If we can't read the Python frame information, don't regard it as such.
+        """
+        if frame.name() == 'PyEval_EvalFrameEx':
+            pyframe = libpython.Frame(frame).get_pyop()
+            return pyframe and not pyframe.is_optimized_out()
+        return False
+
+    @default_selected_gdb_frame()
+    def get_c_function_name(self, frame):
+        return frame.name()
+
+    @default_selected_gdb_frame()
+    def get_c_lineno(self, frame):
+        return frame.find_sal().line
+
+    @default_selected_gdb_frame()
+    def get_cython_function(self, frame):
+        result = self.cy.functions_by_cname.get(frame.name())
+        if result is None:
+            raise NoCythonFunctionInFrameError()
+
+        return result
+
+    @default_selected_gdb_frame()
+    def get_cython_lineno(self, frame):
+        """
+        Get the current Cython line number. Returns 0 if there is no
+        correspondence between the C and Cython code.
+        """
+        cyfunc = self.get_cython_function(frame)
+        return cyfunc.module.lineno_c2cy.get(self.get_c_lineno(frame), 0)
+
+    @default_selected_gdb_frame()
+    def get_source_desc(self, frame):
+        filename = lineno = lexer = None
+        if self.is_cython_function(frame):
+            filename = self.get_cython_function(frame).module.filename
+            lineno = self.get_cython_lineno(frame)
+            if pygments:
+                lexer = pygments.lexers.CythonLexer(stripall=False)
+        elif self.is_python_function(frame):
+            pyframeobject = libpython.Frame(frame).get_pyop()
+
+            if not pyframeobject:
+                raise gdb.GdbError(
+                            'Unable to read information on python frame')
+
+            filename = pyframeobject.filename()
+            lineno = pyframeobject.current_line_num()
+
+            if pygments:
+                lexer = pygments.lexers.PythonLexer(stripall=False)
+        else:
+            symbol_and_line_obj = frame.find_sal()
+            if not symbol_and_line_obj or not symbol_and_line_obj.symtab:
+                filename = None
+                lineno = 0
+            else:
+                filename = symbol_and_line_obj.symtab.fullname()
+                lineno = symbol_and_line_obj.line
+                if pygments:
+                    lexer = pygments.lexers.CLexer(stripall=False)
+
+        return SourceFileDescriptor(filename, lexer), lineno
+
+    @default_selected_gdb_frame()
+    def get_source_line(self, frame):
+        source_desc, lineno = self.get_source_desc()
+        return source_desc.get_source(lineno)
+
+    @default_selected_gdb_frame()
+    def is_relevant_function(self, frame):
+        """
+        returns whether we care about a frame on the user-level when debugging
+        Cython code
+        """
+        name = frame.name()
+        older_frame = frame.older()
+        if self.is_cython_function(frame) or self.is_python_function(frame):
+            return True
+        elif older_frame and self.is_cython_function(older_frame):
+            # check for direct C function call from a Cython function
+            cython_func = self.get_cython_function(older_frame)
+            return name in cython_func.step_into_functions
+
+        return False
+
+    @default_selected_gdb_frame(err=False)
+    def print_stackframe(self, frame, index, is_c=False):
+        """
+        Print a C, Cython or Python stack frame and the line of source code
+        if available.
+        """
+        # do this to prevent the require_cython_frame decorator from
+        # raising GdbError when calling self.cy.cy_cvalue.invoke()
+        selected_frame = gdb.selected_frame()
+        frame.select()
+
+        try:
+            source_desc, lineno = self.get_source_desc(frame)
+        except NoFunctionNameInFrameError:
+            print('#%-2d Unknown Frame (compile with -g)' % index)
+            return
+
+        if not is_c and self.is_python_function(frame):
+            pyframe = libpython.Frame(frame).get_pyop()
+            if pyframe is None or pyframe.is_optimized_out():
+                # print this python function as a C function
+                return self.print_stackframe(frame, index, is_c=True)
+
+            func_name = pyframe.co_name
+            func_cname = 'PyEval_EvalFrameEx'
+            func_args = []
+        elif self.is_cython_function(frame):
+            cyfunc = self.get_cython_function(frame)
+            f = lambda arg: self.cy.cy_cvalue.invoke(arg, frame=frame)
+
+            func_name = cyfunc.name
+            func_cname = cyfunc.cname
+            func_args = [] # [(arg, f(arg)) for arg in cyfunc.arguments]
+        else:
+            source_desc, lineno = self.get_source_desc(frame)
+            func_name = frame.name()
+            func_cname = func_name
+            func_args = []
+
+        try:
+            gdb_value = gdb.parse_and_eval(func_cname)
+        except RuntimeError:
+            func_address = 0
+        else:
+            func_address = gdb_value.address
+            if not isinstance(func_address, int):
+                # Seriously? Why is the address not an int?
+                if not isinstance(func_address, (str, bytes)):
+                    func_address = str(func_address)
+                func_address = int(func_address.split()[0], 0)
+
+        a = ', '.join('%s=%s' % (name, val) for name, val in func_args)
+        sys.stdout.write('#%-2d 0x%016x in %s(%s)' % (index, func_address, func_name, a))
+
+        if source_desc.filename is not None:
+            sys.stdout.write(' at %s:%s' % (source_desc.filename, lineno))
+
+        sys.stdout.write('\n')
+
+        try:
+            sys.stdout.write('    ' + source_desc.get_source(lineno))
+        except gdb.GdbError:
+            pass
+
+        selected_frame.select()
+
+    def get_remote_cython_globals_dict(self):
+        m = gdb.parse_and_eval('__pyx_m')
+
+        try:
+            PyModuleObject = gdb.lookup_type('PyModuleObject')
+        except RuntimeError:
+            raise gdb.GdbError(textwrap.dedent("""\
+                Unable to lookup type PyModuleObject, did you compile python
+                with debugging support (-g)?"""))
+
+        m = m.cast(PyModuleObject.pointer())
+        return m['md_dict']
+
+
+    def get_cython_globals_dict(self):
+        """
+        Get the Cython globals dict where the remote names are turned into
+        local strings.
+        """
+        remote_dict = self.get_remote_cython_globals_dict()
+        pyobject_dict = libpython.PyObjectPtr.from_pyobject_ptr(remote_dict)
+
+        result = {}
+        seen = set()
+        for k, v in pyobject_dict.items():
+            result[k.proxyval(seen)] = v
+
+        return result
+
+    def print_gdb_value(self, name, value, max_name_length=None, prefix=''):
+        if libpython.pretty_printer_lookup(value):
+            typename = ''
+        else:
+            typename = '(%s) ' % (value.type,)
+
+        if max_name_length is None:
+            print('%s%s = %s%s' % (prefix, name, typename, value))
+        else:
+            print('%s%-*s = %s%s' % (prefix, max_name_length, name, typename, value))
+
+    def is_initialized(self, cython_func, local_name):
+        cyvar = cython_func.locals[local_name]
+        cur_lineno = self.get_cython_lineno()
+
+        if '->' in cyvar.cname:
+            # Closed over free variable
+            if cur_lineno > cython_func.lineno:
+                if cyvar.type == PythonObject:
+                    return int(gdb.parse_and_eval(cyvar.cname))
+                return True
+            return False
+
+        return cur_lineno > cyvar.lineno
+
+
+class SourceFileDescriptor(object):
+    def __init__(self, filename, lexer, formatter=None):
+        self.filename = filename
+        self.lexer = lexer
+        self.formatter = formatter
+
+    def valid(self):
+        return self.filename is not None
+
+    def lex(self, code):
+        if pygments and self.lexer and parameters.colorize_code:
+            bg = parameters.terminal_background.value
+            if self.formatter is None:
+                formatter = pygments.formatters.TerminalFormatter(bg=bg)
+            else:
+                formatter = self.formatter
+
+            return pygments.highlight(code, self.lexer, formatter)
+
+        return code
+
+    def _get_source(self, start, stop, lex_source, mark_line, lex_entire):
+        with open(self.filename) as f:
+            # to provide "correct" colouring, the entire code needs to be
+            # lexed. However, this makes a lot of things terribly slow, so
+            # we decide not to. Besides, it's unlikely to matter.
+
+            if lex_source and lex_entire:
+                f = self.lex(f.read()).splitlines()
+
+            slice = itertools.islice(f, start - 1, stop - 1)
+
+            for idx, line in enumerate(slice):
+                if start + idx == mark_line:
+                    prefix = '>'
+                else:
+                    prefix = ' '
+
+                if lex_source and not lex_entire:
+                    line = self.lex(line)
+
+                yield '%s %4d    %s' % (prefix, start + idx, line.rstrip())
+
+    def get_source(self, start, stop=None, lex_source=True, mark_line=0,
+                   lex_entire=False):
+        exc = gdb.GdbError('Unable to retrieve source code')
+
+        if not self.filename:
+            raise exc
+
+        start = max(start, 1)
+        if stop is None:
+            stop = start + 1
+
+        try:
+            return '\n'.join(
+                self._get_source(start, stop, lex_source, mark_line, lex_entire))
+        except IOError:
+            raise exc
+
+
+# Errors
+
+class CyGDBError(gdb.GdbError):
+    """
+    Base class for Cython-command related errors
+    """
+
+    def __init__(self, *args):
+        args = args or (self.msg,)
+        super(CyGDBError, self).__init__(*args)
+
+
+class NoCythonFunctionInFrameError(CyGDBError):
+    """
+    raised when the user requests the current cython function, which is
+    unavailable
+    """
+    msg = "Current function is a function cygdb doesn't know about"
+
+
+class NoFunctionNameInFrameError(NoCythonFunctionInFrameError):
+    """
+    raised when the name of the C function could not be determined
+    in the current C stack frame
+    """
+    msg = ('C function name could not be determined in the current C stack '
+           'frame')
+
+
+# Parameters
+
+class CythonParameter(gdb.Parameter):
+    """
+    Base class for cython parameters
+    """
+
+    def __init__(self, name, command_class, parameter_class, default=None):
+        self.show_doc = self.set_doc = self.__class__.__doc__
+        super(CythonParameter, self).__init__(name, command_class,
+                                              parameter_class)
+        if default is not None:
+            self.value = default
+
+    def __bool__(self):
+        return bool(self.value)
+
+    __nonzero__ = __bool__  # Python 2
+
+
+
+class CompleteUnqualifiedFunctionNames(CythonParameter):
+    """
+    Have 'cy break' complete unqualified function or method names.
+    """
+
+
+class ColorizeSourceCode(CythonParameter):
+    """
+    Tell cygdb whether to colorize source code.
+    """
+
+
+class TerminalBackground(CythonParameter):
+    """
+    Tell cygdb about the user's terminal background (light or dark).
+    """
+
+
+class CythonParameters(object):
+    """
+    Simple container class that might get more functionality in the distant
+    future (mostly to remind us that we're dealing with parameters).
+    """
+
+    def __init__(self):
+        self.complete_unqualified = CompleteUnqualifiedFunctionNames(
+            'cy_complete_unqualified',
+            gdb.COMMAND_BREAKPOINTS,
+            gdb.PARAM_BOOLEAN,
+            True)
+        self.colorize_code = ColorizeSourceCode(
+            'cy_colorize_code',
+            gdb.COMMAND_FILES,
+            gdb.PARAM_BOOLEAN,
+            True)
+        self.terminal_background = TerminalBackground(
+            'cy_terminal_background_color',
+            gdb.COMMAND_FILES,
+            gdb.PARAM_STRING,
+            "dark")
+
+parameters = CythonParameters()
+
+
+# Commands
+
+class CythonCommand(gdb.Command, CythonBase):
+    """
+    Base class for Cython commands
+    """
+
+    command_class = gdb.COMMAND_NONE
+
+    @classmethod
+    def _register(cls, clsname, args, kwargs):
+        if not hasattr(cls, 'completer_class'):
+            return cls(clsname, cls.command_class, *args, **kwargs)
+        else:
+            return cls(clsname, cls.command_class, cls.completer_class,
+                       *args, **kwargs)
+
+    @classmethod
+    def register(cls, *args, **kwargs):
+        alias = getattr(cls, 'alias', None)
+        if alias:
+            cls._register(cls.alias, args, kwargs)
+
+        return cls._register(cls.name, args, kwargs)
+
+
+class CyCy(CythonCommand):
+    """
+    Invoke a Cython command. Available commands are:
+
+        cy import
+        cy break
+        cy step
+        cy next
+        cy run
+        cy cont
+        cy finish
+        cy up
+        cy down
+        cy select
+        cy bt / cy backtrace
+        cy list
+        cy print
+        cy set
+        cy locals
+        cy globals
+        cy exec
+    """
+
+    name = 'cy'
+    command_class = gdb.COMMAND_NONE
+    completer_class = gdb.COMPLETE_COMMAND
+
+    def __init__(self, name, command_class, completer_class):
+        # keep the signature 2.5 compatible (i.e. do not use f(*a, k=v)
+        super(CythonCommand, self).__init__(name, command_class,
+                                            completer_class, prefix=True)
+
+        commands = dict(
+            # GDB commands
+            import_ = CyImport.register(),
+            break_ = CyBreak.register(),
+            step = CyStep.register(),
+            next = CyNext.register(),
+            run = CyRun.register(),
+            cont = CyCont.register(),
+            finish = CyFinish.register(),
+            up = CyUp.register(),
+            down = CyDown.register(),
+            select = CySelect.register(),
+            bt = CyBacktrace.register(),
+            list = CyList.register(),
+            print_ = CyPrint.register(),
+            locals = CyLocals.register(),
+            globals = CyGlobals.register(),
+            exec_ = libpython.FixGdbCommand('cy exec', '-cy-exec'),
+            _exec = CyExec.register(),
+            set = CySet.register(),
+
+            # GDB functions
+            cy_cname = CyCName('cy_cname'),
+            cy_cvalue = CyCValue('cy_cvalue'),
+            cy_lineno = CyLine('cy_lineno'),
+            cy_eval = CyEval('cy_eval'),
+        )
+
+        for command_name, command in commands.items():
+            command.cy = self
+            setattr(self, command_name, command)
+
+        self.cy = self
+
+        # Cython module namespace
+        self.cython_namespace = {}
+
+        # maps (unique) qualified function names (e.g.
+        # cythonmodule.ClassName.method_name) to the CythonFunction object
+        self.functions_by_qualified_name = {}
+
+        # unique cnames of Cython functions
+        self.functions_by_cname = {}
+
+        # map function names like method_name to a list of all such
+        # CythonFunction objects
+        self.functions_by_name = collections.defaultdict(list)
+
+
+class CyImport(CythonCommand):
+    """
+    Import debug information outputted by the Cython compiler
+    Example: cy import FILE...
+    """
+
+    name = 'cy import'
+    command_class = gdb.COMMAND_STATUS
+    completer_class = gdb.COMPLETE_FILENAME
+
+    def invoke(self, args, from_tty):
+        if isinstance(args, BYTES):
+            args = args.decode(_filesystemencoding)
+        for arg in string_to_argv(args):
+            try:
+                f = open(arg)
+            except OSError as e:
+                raise gdb.GdbError('Unable to open file %r: %s' % (args, e.args[1]))
+
+            t = etree.parse(f)
+
+            for module in t.getroot():
+                cython_module = CythonModule(**module.attrib)
+                self.cy.cython_namespace[cython_module.name] = cython_module
+
+                for variable in module.find('Globals'):
+                    d = variable.attrib
+                    cython_module.globals[d['name']] = CythonVariable(**d)
+
+                for function in module.find('Functions'):
+                    cython_function = CythonFunction(module=cython_module,
+                                                     **function.attrib)
+
+                    # update the global function mappings
+                    name = cython_function.name
+                    qname = cython_function.qualified_name
+
+                    self.cy.functions_by_name[name].append(cython_function)
+                    self.cy.functions_by_qualified_name[
+                        cython_function.qualified_name] = cython_function
+                    self.cy.functions_by_cname[
+                        cython_function.cname] = cython_function
+
+                    d = cython_module.functions[qname] = cython_function
+
+                    for local in function.find('Locals'):
+                        d = local.attrib
+                        cython_function.locals[d['name']] = CythonVariable(**d)
+
+                    for step_into_func in function.find('StepIntoFunctions'):
+                        d = step_into_func.attrib
+                        cython_function.step_into_functions.add(d['name'])
+
+                    cython_function.arguments.extend(
+                        funcarg.tag for funcarg in function.find('Arguments'))
+
+                for marker in module.find('LineNumberMapping'):
+                    cython_lineno = int(marker.attrib['cython_lineno'])
+                    c_linenos = list(map(int, marker.attrib['c_linenos'].split()))
+                    cython_module.lineno_cy2c[cython_lineno] = min(c_linenos)
+                    for c_lineno in c_linenos:
+                        cython_module.lineno_c2cy[c_lineno] = cython_lineno
+
+
+class CyBreak(CythonCommand):
+    """
+    Set a breakpoint for Cython code using Cython qualified name notation, e.g.:
+
+        cy break cython_modulename.ClassName.method_name...
+
+    or normal notation:
+
+        cy break function_or_method_name...
+
+    or for a line number:
+
+        cy break cython_module:lineno...
+
+    Set a Python breakpoint:
+        Break on any function or method named 'func' in module 'modname'
+
+            cy break -p modname.func...
+
+        Break on any function or method named 'func'
+
+            cy break -p func...
+    """
+
+    name = 'cy break'
+    command_class = gdb.COMMAND_BREAKPOINTS
+
+    def _break_pyx(self, name):
+        modulename, _, lineno = name.partition(':')
+        lineno = int(lineno)
+        if modulename:
+            cython_module = self.cy.cython_namespace[modulename]
+        else:
+            cython_module = self.get_cython_function().module
+
+        if lineno in cython_module.lineno_cy2c:
+            c_lineno = cython_module.lineno_cy2c[lineno]
+            breakpoint = '%s:%s' % (cython_module.c_filename, c_lineno)
+            gdb.execute('break ' + breakpoint)
+        else:
+            raise gdb.GdbError("Not a valid line number. "
+                               "Does it contain actual code?")
+
+    def _break_funcname(self, funcname):
+        func = self.cy.functions_by_qualified_name.get(funcname)
+
+        if func and func.is_initmodule_function:
+            func = None
+
+        break_funcs = [func]
+
+        if not func:
+            funcs = self.cy.functions_by_name.get(funcname) or []
+            funcs = [f for f in funcs if not f.is_initmodule_function]
+
+            if not funcs:
+                gdb.execute('break ' + funcname)
+                return
+
+            if len(funcs) > 1:
+                # multiple functions, let the user pick one
+                print('There are multiple such functions:')
+                for idx, func in enumerate(funcs):
+                    print('%3d) %s' % (idx, func.qualified_name))
+
+                while True:
+                    try:
+                        result = input(
+                            "Select a function, press 'a' for all "
+                            "functions or press 'q' or '^D' to quit: ")
+                    except EOFError:
+                        return
+                    else:
+                        if result.lower() == 'q':
+                            return
+                        elif result.lower() == 'a':
+                            break_funcs = funcs
+                            break
+                        elif (result.isdigit() and
+                                0 <= int(result) < len(funcs)):
+                            break_funcs = [funcs[int(result)]]
+                            break
+                        else:
+                            print('Not understood...')
+            else:
+                break_funcs = [funcs[0]]
+
+        for func in break_funcs:
+            gdb.execute('break %s' % func.cname)
+            if func.pf_cname:
+                gdb.execute('break %s' % func.pf_cname)
+
+    def invoke(self, function_names, from_tty):
+        if isinstance(function_names, BYTES):
+            function_names = function_names.decode(_filesystemencoding)
+        argv = string_to_argv(function_names)
+        if function_names.startswith('-p'):
+            argv = argv[1:]
+            python_breakpoints = True
+        else:
+            python_breakpoints = False
+
+        for funcname in argv:
+            if python_breakpoints:
+                gdb.execute('py-break %s' % funcname)
+            elif ':' in funcname:
+                self._break_pyx(funcname)
+            else:
+                self._break_funcname(funcname)
+
+    @dont_suppress_errors
+    def complete(self, text, word):
+        # Filter init-module functions (breakpoints can be set using
+        # modulename:linenumber).
+        names =  [n for n, L in self.cy.functions_by_name.items()
+                  if any(not f.is_initmodule_function for f in L)]
+        qnames = [n for n, f in self.cy.functions_by_qualified_name.items()
+                  if not f.is_initmodule_function]
+
+        if parameters.complete_unqualified:
+            all_names = itertools.chain(qnames, names)
+        else:
+            all_names = qnames
+
+        words = text.strip().split()
+        if not words or '.' not in words[-1]:
+            # complete unqualified
+            seen = set(text[:-len(word)].split())
+            return [n for n in all_names
+                          if n.startswith(word) and n not in seen]
+
+        # complete qualified name
+        lastword = words[-1]
+        compl = [n for n in qnames if n.startswith(lastword)]
+
+        if len(lastword) > len(word):
+            # readline sees something (e.g. a '.') as a word boundary, so don't
+            # "recomplete" this prefix
+            strip_prefix_length = len(lastword) - len(word)
+            compl = [n[strip_prefix_length:] for n in compl]
+
+        return compl
+
+
+class CythonInfo(CythonBase, libpython.PythonInfo):
+    """
+    Implementation of the interface dictated by libpython.LanguageInfo.
+    """
+
+    def lineno(self, frame):
+        # Take care of the Python and Cython levels. We need to care for both
+        # as we can't simply dispatch to 'py-step', since that would work for
+        # stepping through Python code, but it would not step back into Cython-
+        # related code. The C level should be dispatched to the 'step' command.
+        if self.is_cython_function(frame):
+            return self.get_cython_lineno(frame)
+        return super(CythonInfo, self).lineno(frame)
+
+    def get_source_line(self, frame):
+        try:
+            line = super(CythonInfo, self).get_source_line(frame)
+        except gdb.GdbError:
+            return None
+        else:
+            return line.strip() or None
+
+    def exc_info(self, frame):
+        if self.is_python_function:
+            return super(CythonInfo, self).exc_info(frame)
+
+    def runtime_break_functions(self):
+        if self.is_cython_function():
+            return self.get_cython_function().step_into_functions
+        return ()
+
+    def static_break_functions(self):
+        result = ['PyEval_EvalFrameEx']
+        result.extend(self.cy.functions_by_cname)
+        return result
+
+
+class CythonExecutionControlCommand(CythonCommand,
+                                    libpython.ExecutionControlCommandBase):
+
+    @classmethod
+    def register(cls):
+        return cls(cls.name, cython_info)
+
+
+class CyStep(CythonExecutionControlCommand, libpython.PythonStepperMixin):
+    "Step through Cython, Python or C code."
+
+    name = 'cy -step'
+    stepinto = True
+
+    def invoke(self, args, from_tty):
+        if self.is_python_function():
+            self.python_step(self.stepinto)
+        elif not self.is_cython_function():
+            if self.stepinto:
+                command = 'step'
+            else:
+                command = 'next'
+
+            self.finish_executing(gdb.execute(command, to_string=True))
+        else:
+            self.step(stepinto=self.stepinto)
+
+
+class CyNext(CyStep):
+    "Step-over Cython, Python or C code."
+
+    name = 'cy -next'
+    stepinto = False
+
+
+class CyRun(CythonExecutionControlCommand):
+    """
+    Run a Cython program. This is like the 'run' command, except that it
+    displays Cython or Python source lines as well
+    """
+
+    name = 'cy run'
+
+    invoke = CythonExecutionControlCommand.run
+
+
+class CyCont(CythonExecutionControlCommand):
+    """
+    Continue a Cython program. This is like the 'run' command, except that it
+    displays Cython or Python source lines as well.
+    """
+
+    name = 'cy cont'
+    invoke = CythonExecutionControlCommand.cont
+
+
+class CyFinish(CythonExecutionControlCommand):
+    """
+    Execute until the function returns.
+    """
+    name = 'cy finish'
+
+    invoke = CythonExecutionControlCommand.finish
+
+
+class CyUp(CythonCommand):
+    """
+    Go up a Cython, Python or relevant C frame.
+    """
+    name = 'cy up'
+    _command = 'up'
+
+    def invoke(self, *args):
+        try:
+            gdb.execute(self._command, to_string=True)
+            while not self.is_relevant_function(gdb.selected_frame()):
+                gdb.execute(self._command, to_string=True)
+        except RuntimeError as e:
+            raise gdb.GdbError(*e.args)
+
+        frame = gdb.selected_frame()
+        index = 0
+        while frame:
+            frame = frame.older()
+            index += 1
+
+        self.print_stackframe(index=index - 1)
+
+
+class CyDown(CyUp):
+    """
+    Go down a Cython, Python or relevant C frame.
+    """
+
+    name = 'cy down'
+    _command = 'down'
+
+
+class CySelect(CythonCommand):
+    """
+    Select a frame. Use frame numbers as listed in `cy backtrace`.
+    This command is useful because `cy backtrace` prints a reversed backtrace.
+    """
+
+    name = 'cy select'
+
+    def invoke(self, stackno, from_tty):
+        try:
+            stackno = int(stackno)
+        except ValueError:
+            raise gdb.GdbError("Not a valid number: %r" % (stackno,))
+
+        frame = gdb.selected_frame()
+        while frame.newer():
+            frame = frame.newer()
+
+        stackdepth = libpython.stackdepth(frame)
+
+        try:
+            gdb.execute('select %d' % (stackdepth - stackno - 1,))
+        except RuntimeError as e:
+            raise gdb.GdbError(*e.args)
+
+
+class CyBacktrace(CythonCommand):
+    'Print the Cython stack'
+
+    name = 'cy bt'
+    alias = 'cy backtrace'
+    command_class = gdb.COMMAND_STACK
+    completer_class = gdb.COMPLETE_NONE
+
+    @require_running_program
+    def invoke(self, args, from_tty):
+        # get the first frame
+        frame = gdb.selected_frame()
+        while frame.older():
+            frame = frame.older()
+
+        print_all = args == '-a'
+
+        index = 0
+        while frame:
+            try:
+                is_relevant = self.is_relevant_function(frame)
+            except CyGDBError:
+                is_relevant = False
+
+            if print_all or is_relevant:
+                self.print_stackframe(frame, index)
+
+            index += 1
+            frame = frame.newer()
+
+
+class CyList(CythonCommand):
+    """
+    List Cython source code. To disable to customize colouring see the cy_*
+    parameters.
+    """
+
+    name = 'cy list'
+    command_class = gdb.COMMAND_FILES
+    completer_class = gdb.COMPLETE_NONE
+
+    # @dispatch_on_frame(c_command='list')
+    def invoke(self, _, from_tty):
+        sd, lineno = self.get_source_desc()
+        source = sd.get_source(lineno - 5, lineno + 5, mark_line=lineno,
+                               lex_entire=True)
+        print(source)
+
+
+class CyPrint(CythonCommand):
+    """
+    Print a Cython variable using 'cy-print x' or 'cy-print module.function.x'
+    """
+
+    name = 'cy print'
+    command_class = gdb.COMMAND_DATA
+
+    def invoke(self, name, from_tty, max_name_length=None):
+        if self.is_python_function():
+            return gdb.execute('py-print ' + name)
+        elif self.is_cython_function():
+            value = self.cy.cy_cvalue.invoke(name.lstrip('*'))
+            for c in name:
+                if c == '*':
+                    value = value.dereference()
+                else:
+                    break
+
+            self.print_gdb_value(name, value, max_name_length)
+        else:
+            gdb.execute('print ' + name)
+
+    def complete(self):
+        if self.is_cython_function():
+            f = self.get_cython_function()
+            return list(itertools.chain(f.locals, f.globals))
+        else:
+            return []
+
+
+sortkey = lambda item: item[0].lower()
+
+
+class CyLocals(CythonCommand):
+    """
+    List the locals from the current Cython frame.
+    """
+
+    name = 'cy locals'
+    command_class = gdb.COMMAND_STACK
+    completer_class = gdb.COMPLETE_NONE
+
+    @dispatch_on_frame(c_command='info locals', python_command='py-locals')
+    def invoke(self, args, from_tty):
+        cython_function = self.get_cython_function()
+
+        if cython_function.is_initmodule_function:
+            self.cy.globals.invoke(args, from_tty)
+            return
+
+        local_cython_vars = cython_function.locals
+        max_name_length = len(max(local_cython_vars, key=len))
+        for name, cyvar in sorted(local_cython_vars.items(), key=sortkey):
+            if self.is_initialized(self.get_cython_function(), cyvar.name):
+                value = gdb.parse_and_eval(cyvar.cname)
+                if not value.is_optimized_out:
+                    self.print_gdb_value(cyvar.name, value,
+                                         max_name_length, '')
+
+
+class CyGlobals(CyLocals):
+    """
+    List the globals from the current Cython module.
+    """
+
+    name = 'cy globals'
+    command_class = gdb.COMMAND_STACK
+    completer_class = gdb.COMPLETE_NONE
+
+    @dispatch_on_frame(c_command='info variables', python_command='py-globals')
+    def invoke(self, args, from_tty):
+        global_python_dict = self.get_cython_globals_dict()
+        module_globals = self.get_cython_function().module.globals
+
+        max_globals_len = 0
+        max_globals_dict_len = 0
+        if module_globals:
+            max_globals_len = len(max(module_globals, key=len))
+        if global_python_dict:
+            max_globals_dict_len = len(max(global_python_dict))
+
+        max_name_length = max(max_globals_len, max_globals_dict_len)
+
+        seen = set()
+        print('Python globals:')
+        for k, v in sorted(global_python_dict.items(), key=sortkey):
+            v = v.get_truncated_repr(libpython.MAX_OUTPUT_LEN)
+            seen.add(k)
+            print('    %-*s = %s' % (max_name_length, k, v))
+
+        print('C globals:')
+        for name, cyvar in sorted(module_globals.items(), key=sortkey):
+            if name not in seen:
+                try:
+                    value = gdb.parse_and_eval(cyvar.cname)
+                except RuntimeError:
+                    pass
+                else:
+                    if not value.is_optimized_out:
+                        self.print_gdb_value(cyvar.name, value,
+                                             max_name_length, '    ')
+
+
+class EvaluateOrExecuteCodeMixin(object):
+    """
+    Evaluate or execute Python code in a Cython or Python frame. The 'evalcode'
+    method evaluations Python code, prints a traceback if an exception went
+    uncaught, and returns any return value as a gdb.Value (NULL on exception).
+    """
+
+    def _fill_locals_dict(self, executor, local_dict_pointer):
+        "Fill a remotely allocated dict with values from the Cython C stack"
+        cython_func = self.get_cython_function()
+
+        for name, cyvar in cython_func.locals.items():
+            if cyvar.type == PythonObject and self.is_initialized(cython_func, name):
+                try:
+                    val = gdb.parse_and_eval(cyvar.cname)
+                except RuntimeError:
+                    continue
+                else:
+                    if val.is_optimized_out:
+                        continue
+
+                pystringp = executor.alloc_pystring(name)
+                code = '''
+                    (PyObject *) PyDict_SetItem(
+                        (PyObject *) %d,
+                        (PyObject *) %d,
+                        (PyObject *) %s)
+                ''' % (local_dict_pointer, pystringp, cyvar.cname)
+
+                try:
+                    if gdb.parse_and_eval(code) < 0:
+                        gdb.parse_and_eval('PyErr_Print()')
+                        raise gdb.GdbError("Unable to execute Python code.")
+                finally:
+                    # PyDict_SetItem doesn't steal our reference
+                    executor.xdecref(pystringp)
+
+    def _find_first_cython_or_python_frame(self):
+        frame = gdb.selected_frame()
+        while frame:
+            if (self.is_cython_function(frame) or
+                self.is_python_function(frame)):
+                frame.select()
+                return frame
+
+            frame = frame.older()
+
+        raise gdb.GdbError("There is no Cython or Python frame on the stack.")
+
+    def _evalcode_cython(self, executor, code, input_type):
+        with libpython.FetchAndRestoreError():
+            # get the dict of Cython globals and construct a dict in the
+            # inferior with Cython locals
+            global_dict = gdb.parse_and_eval(
+                '(PyObject *) PyModule_GetDict(__pyx_m)')
+            local_dict = gdb.parse_and_eval('(PyObject *) PyDict_New()')
+
+            try:
+                self._fill_locals_dict(executor,
+                                       libpython.pointervalue(local_dict))
+                result = executor.evalcode(code, input_type, global_dict,
+                                           local_dict)
+            finally:
+                executor.xdecref(libpython.pointervalue(local_dict))
+
+        return result
+
+    def evalcode(self, code, input_type):
+        """
+        Evaluate `code` in a Python or Cython stack frame using the given
+        `input_type`.
+        """
+        frame = self._find_first_cython_or_python_frame()
+        executor = libpython.PythonCodeExecutor()
+        if self.is_python_function(frame):
+            return libpython._evalcode_python(executor, code, input_type)
+        return self._evalcode_cython(executor, code, input_type)
+
+
+class CyExec(CythonCommand, libpython.PyExec, EvaluateOrExecuteCodeMixin):
+    """
+    Execute Python code in the nearest Python or Cython frame.
+    """
+
+    name = '-cy-exec'
+    command_class = gdb.COMMAND_STACK
+    completer_class = gdb.COMPLETE_NONE
+
+    def invoke(self, expr, from_tty):
+        expr, input_type = self.readcode(expr)
+        executor = libpython.PythonCodeExecutor()
+        executor.xdecref(self.evalcode(expr, executor.Py_single_input))
+
+
+class CySet(CythonCommand):
+    """
+    Set a Cython variable to a certain value
+
+        cy set my_cython_c_variable = 10
+        cy set my_cython_py_variable = $cy_eval("{'doner': 'kebab'}")
+
+    This is equivalent to
+
+        set $cy_value("my_cython_variable") = 10
+    """
+
+    name = 'cy set'
+    command_class = gdb.COMMAND_DATA
+    completer_class = gdb.COMPLETE_NONE
+
+    @require_cython_frame
+    def invoke(self, expr, from_tty):
+        name_and_expr = expr.split('=', 1)
+        if len(name_and_expr) != 2:
+            raise gdb.GdbError("Invalid expression. Use 'cy set var = expr'.")
+
+        varname, expr = name_and_expr
+        cname = self.cy.cy_cname.invoke(varname.strip())
+        gdb.execute("set %s = %s" % (cname, expr))
+
+
+# Functions
+
+class CyCName(gdb.Function, CythonBase):
+    """
+    Get the C name of a Cython variable in the current context.
+    Examples:
+
+        print $cy_cname("function")
+        print $cy_cname("Class.method")
+        print $cy_cname("module.function")
+    """
+
+    @require_cython_frame
+    @gdb_function_value_to_unicode
+    def invoke(self, cyname, frame=None):
+        frame = frame or gdb.selected_frame()
+        cname = None
+
+        if self.is_cython_function(frame):
+            cython_function = self.get_cython_function(frame)
+            if cyname in cython_function.locals:
+                cname = cython_function.locals[cyname].cname
+            elif cyname in cython_function.module.globals:
+                cname = cython_function.module.globals[cyname].cname
+            else:
+                qname = '%s.%s' % (cython_function.module.name, cyname)
+                if qname in cython_function.module.functions:
+                    cname = cython_function.module.functions[qname].cname
+
+        if not cname:
+            cname = self.cy.functions_by_qualified_name.get(cyname)
+
+        if not cname:
+            raise gdb.GdbError('No such Cython variable: %s' % cyname)
+
+        return cname
+
+
+class CyCValue(CyCName):
+    """
+    Get the value of a Cython variable.
+    """
+
+    @require_cython_frame
+    @gdb_function_value_to_unicode
+    def invoke(self, cyname, frame=None):
+        globals_dict = self.get_cython_globals_dict()
+        cython_function = self.get_cython_function(frame)
+
+        if self.is_initialized(cython_function, cyname):
+            cname = super(CyCValue, self).invoke(cyname, frame=frame)
+            return gdb.parse_and_eval(cname)
+        elif cyname in globals_dict:
+            return globals_dict[cyname]._gdbval
+        else:
+            raise gdb.GdbError("Variable %s is not initialized." % cyname)
+
+
+class CyLine(gdb.Function, CythonBase):
+    """
+    Get the current Cython line.
+    """
+
+    @require_cython_frame
+    def invoke(self):
+        return self.get_cython_lineno()
+
+
+class CyEval(gdb.Function, CythonBase, EvaluateOrExecuteCodeMixin):
+    """
+    Evaluate Python code in the nearest Python or Cython frame and return
+    """
+
+    @gdb_function_value_to_unicode
+    def invoke(self, python_expression):
+        input_type = libpython.PythonCodeExecutor.Py_eval_input
+        return self.evalcode(python_expression, input_type)
+
+
+cython_info = CythonInfo()
+cy = CyCy.register()
+cython_info.cy = cy
+
+
+def register_defines():
+    libpython.source_gdb_script(textwrap.dedent("""\
+        define cy step
+        cy -step
+        end
+
+        define cy next
+        cy -next
+        end
+
+        document cy step
+        %s
+        end
+
+        document cy next
+        %s
+        end
+    """) % (CyStep.__doc__, CyNext.__doc__))
+
+register_defines()
diff --git a/contrib/tools/cython/Cython/Debugger/libpython.py b/contrib/tools/cython/Cython/Debugger/libpython.py
new file mode 100644
index 0000000000..fea626dd73
--- /dev/null
+++ b/contrib/tools/cython/Cython/Debugger/libpython.py
@@ -0,0 +1,2760 @@
+#!/usr/bin/python
+
+# NOTE: this file is taken from the Python source distribution
+# It can be found under Tools/gdb/libpython.py. It is shipped with Cython
+# because it's not installed as a python module, and because changes are only
+# merged into new python versions (v3.2+).
+
+'''
+From gdb 7 onwards, gdb's build can be configured --with-python, allowing gdb
+to be extended with Python code e.g. for library-specific data visualizations,
+such as for the C++ STL types.  Documentation on this API can be seen at:
+http://sourceware.org/gdb/current/onlinedocs/gdb/Python-API.html
+
+
+This python module deals with the case when the process being debugged (the
+"inferior process" in gdb parlance) is itself python, or more specifically,
+linked against libpython.  In this situation, almost every item of data is a
+(PyObject*), and having the debugger merely print their addresses is not very
+enlightening.
+
+This module embeds knowledge about the implementation details of libpython so
+that we can emit useful visualizations e.g. a string, a list, a dict, a frame
+giving file/line information and the state of local variables
+
+In particular, given a gdb.Value corresponding to a PyObject* in the inferior
+process, we can generate a "proxy value" within the gdb process.  For example,
+given a PyObject* in the inferior process that is in fact a PyListObject*
+holding three PyObject* that turn out to be PyBytesObject* instances, we can
+generate a proxy value within the gdb process that is a list of bytes
+instances:
+  [b"foo", b"bar", b"baz"]
+
+Doing so can be expensive for complicated graphs of objects, and could take
+some time, so we also have a "write_repr" method that writes a representation
+of the data to a file-like object.  This allows us to stop the traversal by
+having the file-like object raise an exception if it gets too much data.
+
+With both "proxyval" and "write_repr" we keep track of the set of all addresses
+visited so far in the traversal, to avoid infinite recursion due to cycles in
+the graph of object references.
+
+We try to defer gdb.lookup_type() invocations for python types until as late as
+possible: for a dynamically linked python binary, when the process starts in
+the debugger, the libpython.so hasn't been dynamically loaded yet, so none of
+the type names are known to the debugger
+
+The module also extends gdb with some python-specific commands.
+'''
+
+# NOTE: some gdbs are linked with Python 3, so this file should be dual-syntax
+# compatible (2.6+ and 3.0+).  See #19308.
+
+from __future__ import print_function
+import gdb
+import os
+import locale
+import sys
+
+if sys.version_info[0] >= 3:
+    unichr = chr
+    xrange = range
+    long = int
+
+# Look up the gdb.Type for some standard types:
+# Those need to be refreshed as types (pointer sizes) may change when
+# gdb loads different executables
+
+def _type_char_ptr():
+    return gdb.lookup_type('char').pointer()  # char*
+
+
+def _type_unsigned_char_ptr():
+    return gdb.lookup_type('unsigned char').pointer()  # unsigned char*
+
+
+def _type_unsigned_short_ptr():
+    return gdb.lookup_type('unsigned short').pointer()
+
+
+def _type_unsigned_int_ptr():
+    return gdb.lookup_type('unsigned int').pointer()
+
+
+def _sizeof_void_p():
+    return gdb.lookup_type('void').pointer().sizeof
+
+
+# value computed later, see PyUnicodeObjectPtr.proxy()
+_is_pep393 = None
+
+Py_TPFLAGS_HEAPTYPE = (1 << 9)
+Py_TPFLAGS_LONG_SUBCLASS     = (1 << 24)
+Py_TPFLAGS_LIST_SUBCLASS     = (1 << 25)
+Py_TPFLAGS_TUPLE_SUBCLASS    = (1 << 26)
+Py_TPFLAGS_BYTES_SUBCLASS    = (1 << 27)
+Py_TPFLAGS_UNICODE_SUBCLASS  = (1 << 28)
+Py_TPFLAGS_DICT_SUBCLASS     = (1 << 29)
+Py_TPFLAGS_BASE_EXC_SUBCLASS = (1 << 30)
+Py_TPFLAGS_TYPE_SUBCLASS     = (1 << 31)
+
+
+MAX_OUTPUT_LEN=1024
+
+hexdigits = "0123456789abcdef"
+
+ENCODING = locale.getpreferredencoding()
+
+EVALFRAME = '_PyEval_EvalFrameDefault'
+
+class NullPyObjectPtr(RuntimeError):
+    pass
+
+
+def safety_limit(val):
+    # Given an integer value from the process being debugged, limit it to some
+    # safety threshold so that arbitrary breakage within said process doesn't
+    # break the gdb process too much (e.g. sizes of iterations, sizes of lists)
+    return min(val, 1000)
+
+
+def safe_range(val):
+    # As per range, but don't trust the value too much: cap it to a safety
+    # threshold in case the data was corrupted
+    return xrange(safety_limit(int(val)))
+
+if sys.version_info[0] >= 3:
+    def write_unicode(file, text):
+        file.write(text)
+else:
+    def write_unicode(file, text):
+        # Write a byte or unicode string to file. Unicode strings are encoded to
+        # ENCODING encoding with 'backslashreplace' error handler to avoid
+        # UnicodeEncodeError.
+        if isinstance(text, unicode):
+            text = text.encode(ENCODING, 'backslashreplace')
+        file.write(text)
+
+try:
+    os_fsencode = os.fsencode
+except AttributeError:
+    def os_fsencode(filename):
+        if not isinstance(filename, unicode):
+            return filename
+        encoding = sys.getfilesystemencoding()
+        if encoding == 'mbcs':
+            # mbcs doesn't support surrogateescape
+            return filename.encode(encoding)
+        encoded = []
+        for char in filename:
+            # surrogateescape error handler
+            if 0xDC80 <= ord(char) <= 0xDCFF:
+                byte = chr(ord(char) - 0xDC00)
+            else:
+                byte = char.encode(encoding)
+            encoded.append(byte)
+        return ''.join(encoded)
+
+class StringTruncated(RuntimeError):
+    pass
+
+class TruncatedStringIO(object):
+    '''Similar to io.StringIO, but can truncate the output by raising a
+    StringTruncated exception'''
+    def __init__(self, maxlen=None):
+        self._val = ''
+        self.maxlen = maxlen
+
+    def write(self, data):
+        if self.maxlen:
+            if len(data) + len(self._val) > self.maxlen:
+                # Truncation:
+                self._val += data[0:self.maxlen - len(self._val)]
+                raise StringTruncated()
+
+        self._val += data
+
+    def getvalue(self):
+        return self._val
+
+class PyObjectPtr(object):
+    """
+    Class wrapping a gdb.Value that's either a (PyObject*) within the
+    inferior process, or some subclass pointer e.g. (PyBytesObject*)
+
+    There will be a subclass for every refined PyObject type that we care
+    about.
+
+    Note that at every stage the underlying pointer could be NULL, point
+    to corrupt data, etc; this is the debugger, after all.
+    """
+    _typename = 'PyObject'
+
+    def __init__(self, gdbval, cast_to=None):
+        if cast_to:
+            self._gdbval = gdbval.cast(cast_to)
+        else:
+            self._gdbval = gdbval
+
+    def field(self, name):
+        '''
+        Get the gdb.Value for the given field within the PyObject, coping with
+        some python 2 versus python 3 differences.
+
+        Various libpython types are defined using the "PyObject_HEAD" and
+        "PyObject_VAR_HEAD" macros.
+
+        In Python 2, this these are defined so that "ob_type" and (for a var
+        object) "ob_size" are fields of the type in question.
+
+        In Python 3, this is defined as an embedded PyVarObject type thus:
+           PyVarObject ob_base;
+        so that the "ob_size" field is located insize the "ob_base" field, and
+        the "ob_type" is most easily accessed by casting back to a (PyObject*).
+        '''
+        if self.is_null():
+            raise NullPyObjectPtr(self)
+
+        if name == 'ob_type':
+            pyo_ptr = self._gdbval.cast(PyObjectPtr.get_gdb_type())
+            return pyo_ptr.dereference()[name]
+
+        if name == 'ob_size':
+            pyo_ptr = self._gdbval.cast(PyVarObjectPtr.get_gdb_type())
+            return pyo_ptr.dereference()[name]
+
+        # General case: look it up inside the object:
+        return self._gdbval.dereference()[name]
+
+    def pyop_field(self, name):
+        '''
+        Get a PyObjectPtr for the given PyObject* field within this PyObject,
+        coping with some python 2 versus python 3 differences.
+        '''
+        return PyObjectPtr.from_pyobject_ptr(self.field(name))
+
+    def write_field_repr(self, name, out, visited):
+        '''
+        Extract the PyObject* field named "name", and write its representation
+        to file-like object "out"
+        '''
+        field_obj = self.pyop_field(name)
+        field_obj.write_repr(out, visited)
+
+    def get_truncated_repr(self, maxlen):
+        '''
+        Get a repr-like string for the data, but truncate it at "maxlen" bytes
+        (ending the object graph traversal as soon as you do)
+        '''
+        out = TruncatedStringIO(maxlen)
+        try:
+            self.write_repr(out, set())
+        except StringTruncated:
+            # Truncation occurred:
+            return out.getvalue() + '...(truncated)'
+
+        # No truncation occurred:
+        return out.getvalue()
+
+    def type(self):
+        return PyTypeObjectPtr(self.field('ob_type'))
+
+    def is_null(self):
+        return 0 == long(self._gdbval)
+
+    def is_optimized_out(self):
+        '''
+        Is the value of the underlying PyObject* visible to the debugger?
+
+        This can vary with the precise version of the compiler used to build
+        Python, and the precise version of gdb.
+
+        See e.g. https://bugzilla.redhat.com/show_bug.cgi?id=556975 with
+        PyEval_EvalFrameEx's "f"
+        '''
+        return self._gdbval.is_optimized_out
+
+    def safe_tp_name(self):
+        try:
+            return self.type().field('tp_name').string()
+        except NullPyObjectPtr:
+            # NULL tp_name?
+            return 'unknown'
+        except RuntimeError:
+            # Can't even read the object at all?
+            return 'unknown'
+
+    def proxyval(self, visited):
+        '''
+        Scrape a value from the inferior process, and try to represent it
+        within the gdb process, whilst (hopefully) avoiding crashes when
+        the remote data is corrupt.
+
+        Derived classes will override this.
+
+        For example, a PyIntObject* with ob_ival 42 in the inferior process
+        should result in an int(42) in this process.
+
+        visited: a set of all gdb.Value pyobject pointers already visited
+        whilst generating this value (to guard against infinite recursion when
+        visiting object graphs with loops).  Analogous to Py_ReprEnter and
+        Py_ReprLeave
+        '''
+
+        class FakeRepr(object):
+            """
+            Class representing a non-descript PyObject* value in the inferior
+            process for when we don't have a custom scraper, intended to have
+            a sane repr().
+            """
+
+            def __init__(self, tp_name, address):
+                self.tp_name = tp_name
+                self.address = address
+
+            def __repr__(self):
+                # For the NULL pointer, we have no way of knowing a type, so
+                # special-case it as per
+                # http://bugs.python.org/issue8032#msg100882
+                if self.address == 0:
+                    return '0x0'
+                return '<%s at remote 0x%x>' % (self.tp_name, self.address)
+
+        return FakeRepr(self.safe_tp_name(),
+                        long(self._gdbval))
+
+    def write_repr(self, out, visited):
+        '''
+        Write a string representation of the value scraped from the inferior
+        process to "out", a file-like object.
+        '''
+        # Default implementation: generate a proxy value and write its repr
+        # However, this could involve a lot of work for complicated objects,
+        # so for derived classes we specialize this
+        return out.write(repr(self.proxyval(visited)))
+
+    @classmethod
+    def subclass_from_type(cls, t):
+        '''
+        Given a PyTypeObjectPtr instance wrapping a gdb.Value that's a
+        (PyTypeObject*), determine the corresponding subclass of PyObjectPtr
+        to use
+
+        Ideally, we would look up the symbols for the global types, but that
+        isn't working yet:
+          (gdb) python print gdb.lookup_symbol('PyList_Type')[0].value
+          Traceback (most recent call last):
+            File "<string>", line 1, in <module>
+          NotImplementedError: Symbol type not yet supported in Python scripts.
+          Error while executing Python code.
+
+        For now, we use tp_flags, after doing some string comparisons on the
+        tp_name for some special-cases that don't seem to be visible through
+        flags
+        '''
+        try:
+            tp_name = t.field('tp_name').string()
+            tp_flags = int(t.field('tp_flags'))
+        except RuntimeError:
+            # Handle any kind of error e.g. NULL ptrs by simply using the base
+            # class
+            return cls
+
+        #print('tp_flags = 0x%08x' % tp_flags)
+        #print('tp_name = %r' % tp_name)
+
+        name_map = {'bool': PyBoolObjectPtr,
+                    'classobj': PyClassObjectPtr,
+                    'NoneType': PyNoneStructPtr,
+                    'frame': PyFrameObjectPtr,
+                    'set' : PySetObjectPtr,
+                    'frozenset' : PySetObjectPtr,
+                    'builtin_function_or_method' : PyCFunctionObjectPtr,
+                    'method-wrapper': wrapperobject,
+                    }
+        if tp_name in name_map:
+            return name_map[tp_name]
+
+        if tp_flags & Py_TPFLAGS_HEAPTYPE:
+            return HeapTypeObjectPtr
+
+        if tp_flags & Py_TPFLAGS_LONG_SUBCLASS:
+            return PyLongObjectPtr
+        if tp_flags & Py_TPFLAGS_LIST_SUBCLASS:
+            return PyListObjectPtr
+        if tp_flags & Py_TPFLAGS_TUPLE_SUBCLASS:
+            return PyTupleObjectPtr
+        if tp_flags & Py_TPFLAGS_BYTES_SUBCLASS:
+            return PyBytesObjectPtr
+        if tp_flags & Py_TPFLAGS_UNICODE_SUBCLASS:
+            return PyUnicodeObjectPtr
+        if tp_flags & Py_TPFLAGS_DICT_SUBCLASS:
+            return PyDictObjectPtr
+        if tp_flags & Py_TPFLAGS_BASE_EXC_SUBCLASS:
+            return PyBaseExceptionObjectPtr
+        #if tp_flags & Py_TPFLAGS_TYPE_SUBCLASS:
+        #    return PyTypeObjectPtr
+
+        # Use the base class:
+        return cls
+
+    @classmethod
+    def from_pyobject_ptr(cls, gdbval):
+        '''
+        Try to locate the appropriate derived class dynamically, and cast
+        the pointer accordingly.
+        '''
+        try:
+            p = PyObjectPtr(gdbval)
+            cls = cls.subclass_from_type(p.type())
+            return cls(gdbval, cast_to=cls.get_gdb_type())
+        except RuntimeError:
+            # Handle any kind of error e.g. NULL ptrs by simply using the base
+            # class
+            pass
+        return cls(gdbval)
+
+    @classmethod
+    def get_gdb_type(cls):
+        return gdb.lookup_type(cls._typename).pointer()
+
+    def as_address(self):
+        return long(self._gdbval)
+
+class PyVarObjectPtr(PyObjectPtr):
+    _typename = 'PyVarObject'
+
+class ProxyAlreadyVisited(object):
+    '''
+    Placeholder proxy to use when protecting against infinite recursion due to
+    loops in the object graph.
+
+    Analogous to the values emitted by the users of Py_ReprEnter and Py_ReprLeave
+    '''
+    def __init__(self, rep):
+        self._rep = rep
+
+    def __repr__(self):
+        return self._rep
+
+
+def _write_instance_repr(out, visited, name, pyop_attrdict, address):
+    '''Shared code for use by all classes:
+    write a representation to file-like object "out"'''
+    out.write('<')
+    out.write(name)
+
+    # Write dictionary of instance attributes:
+    if isinstance(pyop_attrdict, PyDictObjectPtr):
+        out.write('(')
+        first = True
+        for pyop_arg, pyop_val in pyop_attrdict.iteritems():
+            if not first:
+                out.write(', ')
+            first = False
+            out.write(pyop_arg.proxyval(visited))
+            out.write('=')
+            pyop_val.write_repr(out, visited)
+        out.write(')')
+    out.write(' at remote 0x%x>' % address)
+
+
+class InstanceProxy(object):
+
+    def __init__(self, cl_name, attrdict, address):
+        self.cl_name = cl_name
+        self.attrdict = attrdict
+        self.address = address
+
+    def __repr__(self):
+        if isinstance(self.attrdict, dict):
+            kwargs = ', '.join(["%s=%r" % (arg, val)
+                                for arg, val in self.attrdict.iteritems()])
+            return '<%s(%s) at remote 0x%x>' % (self.cl_name,
+                                                kwargs, self.address)
+        else:
+            return '<%s at remote 0x%x>' % (self.cl_name,
+                                            self.address)
+
+def _PyObject_VAR_SIZE(typeobj, nitems):
+    if _PyObject_VAR_SIZE._type_size_t is None:
+        _PyObject_VAR_SIZE._type_size_t = gdb.lookup_type('size_t')
+
+    return ( ( typeobj.field('tp_basicsize') +
+               nitems * typeobj.field('tp_itemsize') +
+               (_sizeof_void_p() - 1)
+             ) & ~(_sizeof_void_p() - 1)
+           ).cast(_PyObject_VAR_SIZE._type_size_t)
+_PyObject_VAR_SIZE._type_size_t = None
+
+class HeapTypeObjectPtr(PyObjectPtr):
+    _typename = 'PyObject'
+
+    def get_attr_dict(self):
+        '''
+        Get the PyDictObject ptr representing the attribute dictionary
+        (or None if there's a problem)
+        '''
+        try:
+            typeobj = self.type()
+            dictoffset = int_from_int(typeobj.field('tp_dictoffset'))
+            if dictoffset != 0:
+                if dictoffset < 0:
+                    type_PyVarObject_ptr = gdb.lookup_type('PyVarObject').pointer()
+                    tsize = int_from_int(self._gdbval.cast(type_PyVarObject_ptr)['ob_size'])
+                    if tsize < 0:
+                        tsize = -tsize
+                    size = _PyObject_VAR_SIZE(typeobj, tsize)
+                    dictoffset += size
+                    assert dictoffset > 0
+                    assert dictoffset % _sizeof_void_p() == 0
+
+                dictptr = self._gdbval.cast(_type_char_ptr()) + dictoffset
+                PyObjectPtrPtr = PyObjectPtr.get_gdb_type().pointer()
+                dictptr = dictptr.cast(PyObjectPtrPtr)
+                return PyObjectPtr.from_pyobject_ptr(dictptr.dereference())
+        except RuntimeError:
+            # Corrupt data somewhere; fail safe
+            pass
+
+        # Not found, or some kind of error:
+        return None
+
+    def proxyval(self, visited):
+        '''
+        Support for classes.
+
+        Currently we just locate the dictionary using a transliteration to
+        python of _PyObject_GetDictPtr, ignoring descriptors
+        '''
+        # Guard against infinite loops:
+        if self.as_address() in visited:
+            return ProxyAlreadyVisited('<...>')
+        visited.add(self.as_address())
+
+        pyop_attr_dict = self.get_attr_dict()
+        if pyop_attr_dict:
+            attr_dict = pyop_attr_dict.proxyval(visited)
+        else:
+            attr_dict = {}
+        tp_name = self.safe_tp_name()
+
+        # Class:
+        return InstanceProxy(tp_name, attr_dict, long(self._gdbval))
+
+    def write_repr(self, out, visited):
+        # Guard against infinite loops:
+        if self.as_address() in visited:
+            out.write('<...>')
+            return
+        visited.add(self.as_address())
+
+        pyop_attrdict = self.get_attr_dict()
+        _write_instance_repr(out, visited,
+                             self.safe_tp_name(), pyop_attrdict, self.as_address())
+
+class ProxyException(Exception):
+    def __init__(self, tp_name, args):
+        self.tp_name = tp_name
+        self.args = args
+
+    def __repr__(self):
+        return '%s%r' % (self.tp_name, self.args)
+
+class PyBaseExceptionObjectPtr(PyObjectPtr):
+    """
+    Class wrapping a gdb.Value that's a PyBaseExceptionObject* i.e. an exception
+    within the process being debugged.
+    """
+    _typename = 'PyBaseExceptionObject'
+
+    def proxyval(self, visited):
+        # Guard against infinite loops:
+        if self.as_address() in visited:
+            return ProxyAlreadyVisited('(...)')
+        visited.add(self.as_address())
+        arg_proxy = self.pyop_field('args').proxyval(visited)
+        return ProxyException(self.safe_tp_name(),
+                              arg_proxy)
+
+    def write_repr(self, out, visited):
+        # Guard against infinite loops:
+        if self.as_address() in visited:
+            out.write('(...)')
+            return
+        visited.add(self.as_address())
+
+        out.write(self.safe_tp_name())
+        self.write_field_repr('args', out, visited)
+
+class PyClassObjectPtr(PyObjectPtr):
+    """
+    Class wrapping a gdb.Value that's a PyClassObject* i.e. a <classobj>
+    instance within the process being debugged.
+    """
+    _typename = 'PyClassObject'
+
+
+class BuiltInFunctionProxy(object):
+    def __init__(self, ml_name):
+        self.ml_name = ml_name
+
+    def __repr__(self):
+        return "<built-in function %s>" % self.ml_name
+
+class BuiltInMethodProxy(object):
+    def __init__(self, ml_name, pyop_m_self):
+        self.ml_name = ml_name
+        self.pyop_m_self = pyop_m_self
+
+    def __repr__(self):
+        return ('<built-in method %s of %s object at remote 0x%x>'
+                % (self.ml_name,
+                   self.pyop_m_self.safe_tp_name(),
+                   self.pyop_m_self.as_address())
+                )
+
+class PyCFunctionObjectPtr(PyObjectPtr):
+    """
+    Class wrapping a gdb.Value that's a PyCFunctionObject*
+    (see Include/methodobject.h and Objects/methodobject.c)
+    """
+    _typename = 'PyCFunctionObject'
+
+    def proxyval(self, visited):
+        m_ml = self.field('m_ml') # m_ml is a (PyMethodDef*)
+        ml_name = m_ml['ml_name'].string()
+
+        pyop_m_self = self.pyop_field('m_self')
+        if pyop_m_self.is_null():
+            return BuiltInFunctionProxy(ml_name)
+        else:
+            return BuiltInMethodProxy(ml_name, pyop_m_self)
+
+
+class PyCodeObjectPtr(PyObjectPtr):
+    """
+    Class wrapping a gdb.Value that's a PyCodeObject* i.e. a <code> instance
+    within the process being debugged.
+    """
+    _typename = 'PyCodeObject'
+
+    def addr2line(self, addrq):
+        '''
+        Get the line number for a given bytecode offset
+
+        Analogous to PyCode_Addr2Line; translated from pseudocode in
+        Objects/lnotab_notes.txt
+        '''
+        co_lnotab = self.pyop_field('co_lnotab').proxyval(set())
+
+        # Initialize lineno to co_firstlineno as per PyCode_Addr2Line
+        # not 0, as lnotab_notes.txt has it:
+        lineno = int_from_int(self.field('co_firstlineno'))
+
+        addr = 0
+        for addr_incr, line_incr in zip(co_lnotab[::2], co_lnotab[1::2]):
+            addr += ord(addr_incr)
+            if addr > addrq:
+                return lineno
+            lineno += ord(line_incr)
+        return lineno
+
+
+class PyDictObjectPtr(PyObjectPtr):
+    """
+    Class wrapping a gdb.Value that's a PyDictObject* i.e. a dict instance
+    within the process being debugged.
+    """
+    _typename = 'PyDictObject'
+
+    def iteritems(self):
+        '''
+        Yields a sequence of (PyObjectPtr key, PyObjectPtr value) pairs,
+        analogous to dict.iteritems()
+        '''
+        keys = self.field('ma_keys')
+        values = self.field('ma_values')
+        entries, nentries = self._get_entries(keys)
+        for i in safe_range(nentries):
+            ep = entries[i]
+            if long(values):
+                pyop_value = PyObjectPtr.from_pyobject_ptr(values[i])
+            else:
+                pyop_value = PyObjectPtr.from_pyobject_ptr(ep['me_value'])
+            if not pyop_value.is_null():
+                pyop_key = PyObjectPtr.from_pyobject_ptr(ep['me_key'])
+                yield (pyop_key, pyop_value)
+
+    def proxyval(self, visited):
+        # Guard against infinite loops:
+        if self.as_address() in visited:
+            return ProxyAlreadyVisited('{...}')
+        visited.add(self.as_address())
+
+        result = {}
+        for pyop_key, pyop_value in self.iteritems():
+            proxy_key = pyop_key.proxyval(visited)
+            proxy_value = pyop_value.proxyval(visited)
+            result[proxy_key] = proxy_value
+        return result
+
+    def write_repr(self, out, visited):
+        # Guard against infinite loops:
+        if self.as_address() in visited:
+            out.write('{...}')
+            return
+        visited.add(self.as_address())
+
+        out.write('{')
+        first = True
+        for pyop_key, pyop_value in self.iteritems():
+            if not first:
+                out.write(', ')
+            first = False
+            pyop_key.write_repr(out, visited)
+            out.write(': ')
+            pyop_value.write_repr(out, visited)
+        out.write('}')
+
+    def _get_entries(self, keys):
+        dk_nentries = int(keys['dk_nentries'])
+        dk_size = int(keys['dk_size'])
+        try:
+            # <= Python 3.5
+            return keys['dk_entries'], dk_size
+        except RuntimeError:
+            # >= Python 3.6
+            pass
+
+        if dk_size <= 0xFF:
+            offset = dk_size
+        elif dk_size <= 0xFFFF:
+            offset = 2 * dk_size
+        elif dk_size <= 0xFFFFFFFF:
+            offset = 4 * dk_size
+        else:
+            offset = 8 * dk_size
+
+        ent_addr = keys['dk_indices']['as_1'].address
+        ent_addr = ent_addr.cast(_type_unsigned_char_ptr()) + offset
+        ent_ptr_t = gdb.lookup_type('PyDictKeyEntry').pointer()
+        ent_addr = ent_addr.cast(ent_ptr_t)
+
+        return ent_addr, dk_nentries
+
+
+class PyListObjectPtr(PyObjectPtr):
+    _typename = 'PyListObject'
+
+    def __getitem__(self, i):
+        # Get the gdb.Value for the (PyObject*) with the given index:
+        field_ob_item = self.field('ob_item')
+        return field_ob_item[i]
+
+    def proxyval(self, visited):
+        # Guard against infinite loops:
+        if self.as_address() in visited:
+            return ProxyAlreadyVisited('[...]')
+        visited.add(self.as_address())
+
+        result = [PyObjectPtr.from_pyobject_ptr(self[i]).proxyval(visited)
+                  for i in safe_range(int_from_int(self.field('ob_size')))]
+        return result
+
+    def write_repr(self, out, visited):
+        # Guard against infinite loops:
+        if self.as_address() in visited:
+            out.write('[...]')
+            return
+        visited.add(self.as_address())
+
+        out.write('[')
+        for i in safe_range(int_from_int(self.field('ob_size'))):
+            if i > 0:
+                out.write(', ')
+            element = PyObjectPtr.from_pyobject_ptr(self[i])
+            element.write_repr(out, visited)
+        out.write(']')
+
+class PyLongObjectPtr(PyObjectPtr):
+    _typename = 'PyLongObject'
+
+    def proxyval(self, visited):
+        '''
+        Python's Include/longobjrep.h has this declaration:
+           struct _longobject {
+               PyObject_VAR_HEAD
+               digit ob_digit[1];
+           };
+
+        with this description:
+            The absolute value of a number is equal to
+                 SUM(for i=0 through abs(ob_size)-1) ob_digit[i] * 2**(SHIFT*i)
+            Negative numbers are represented with ob_size < 0;
+            zero is represented by ob_size == 0.
+
+        where SHIFT can be either:
+            #define PyLong_SHIFT        30
+            #define PyLong_SHIFT        15
+        '''
+        ob_size = long(self.field('ob_size'))
+        if ob_size == 0:
+            return 0
+
+        ob_digit = self.field('ob_digit')
+
+        if gdb.lookup_type('digit').sizeof == 2:
+            SHIFT = 15
+        else:
+            SHIFT = 30
+
+        digits = [long(ob_digit[i]) * 2**(SHIFT*i)
+                  for i in safe_range(abs(ob_size))]
+        result = sum(digits)
+        if ob_size < 0:
+            result = -result
+        return result
+
+    def write_repr(self, out, visited):
+        # Write this out as a Python 3 int literal, i.e. without the "L" suffix
+        proxy = self.proxyval(visited)
+        out.write("%s" % proxy)
+
+
+class PyBoolObjectPtr(PyLongObjectPtr):
+    """
+    Class wrapping a gdb.Value that's a PyBoolObject* i.e. one of the two
+    <bool> instances (Py_True/Py_False) within the process being debugged.
+    """
+    def proxyval(self, visited):
+        if PyLongObjectPtr.proxyval(self, visited):
+            return True
+        else:
+            return False
+
+class PyNoneStructPtr(PyObjectPtr):
+    """
+    Class wrapping a gdb.Value that's a PyObject* pointing to the
+    singleton (we hope) _Py_NoneStruct with ob_type PyNone_Type
+    """
+    _typename = 'PyObject'
+
+    def proxyval(self, visited):
+        return None
+
+
+class PyFrameObjectPtr(PyObjectPtr):
+    _typename = 'PyFrameObject'
+
+    def __init__(self, gdbval, cast_to=None):
+        PyObjectPtr.__init__(self, gdbval, cast_to)
+
+        if not self.is_optimized_out():
+            self.co = PyCodeObjectPtr.from_pyobject_ptr(self.field('f_code'))
+            self.co_name = self.co.pyop_field('co_name')
+            self.co_filename = self.co.pyop_field('co_filename')
+
+            self.f_lineno = int_from_int(self.field('f_lineno'))
+            self.f_lasti = int_from_int(self.field('f_lasti'))
+            self.co_nlocals = int_from_int(self.co.field('co_nlocals'))
+            self.co_varnames = PyTupleObjectPtr.from_pyobject_ptr(self.co.field('co_varnames'))
+
+    def iter_locals(self):
+        '''
+        Yield a sequence of (name,value) pairs of PyObjectPtr instances, for
+        the local variables of this frame
+        '''
+        if self.is_optimized_out():
+            return
+
+        f_localsplus = self.field('f_localsplus')
+        for i in safe_range(self.co_nlocals):
+            pyop_value = PyObjectPtr.from_pyobject_ptr(f_localsplus[i])
+            if not pyop_value.is_null():
+                pyop_name = PyObjectPtr.from_pyobject_ptr(self.co_varnames[i])
+                yield (pyop_name, pyop_value)
+
+    def iter_globals(self):
+        '''
+        Yield a sequence of (name,value) pairs of PyObjectPtr instances, for
+        the global variables of this frame
+        '''
+        if self.is_optimized_out():
+            return ()
+
+        pyop_globals = self.pyop_field('f_globals')
+        return pyop_globals.iteritems()
+
+    def iter_builtins(self):
+        '''
+        Yield a sequence of (name,value) pairs of PyObjectPtr instances, for
+        the builtin variables
+        '''
+        if self.is_optimized_out():
+            return ()
+
+        pyop_builtins = self.pyop_field('f_builtins')
+        return pyop_builtins.iteritems()
+
+    def get_var_by_name(self, name):
+        '''
+        Look for the named local variable, returning a (PyObjectPtr, scope) pair
+        where scope is a string 'local', 'global', 'builtin'
+
+        If not found, return (None, None)
+        '''
+        for pyop_name, pyop_value in self.iter_locals():
+            if name == pyop_name.proxyval(set()):
+                return pyop_value, 'local'
+        for pyop_name, pyop_value in self.iter_globals():
+            if name == pyop_name.proxyval(set()):
+                return pyop_value, 'global'
+        for pyop_name, pyop_value in self.iter_builtins():
+            if name == pyop_name.proxyval(set()):
+                return pyop_value, 'builtin'
+        return None, None
+
+    def filename(self):
+        '''Get the path of the current Python source file, as a string'''
+        if self.is_optimized_out():
+            return '(frame information optimized out)'
+        return self.co_filename.proxyval(set())
+
+    def current_line_num(self):
+        '''Get current line number as an integer (1-based)
+
+        Translated from PyFrame_GetLineNumber and PyCode_Addr2Line
+
+        See Objects/lnotab_notes.txt
+        '''
+        if self.is_optimized_out():
+            return None
+        f_trace = self.field('f_trace')
+        if long(f_trace) != 0:
+            # we have a non-NULL f_trace:
+            return self.f_lineno
+        else:
+            #try:
+            return self.co.addr2line(self.f_lasti)
+            #except ValueError:
+            #    return self.f_lineno
+
+    def current_line(self):
+        '''Get the text of the current source line as a string, with a trailing
+        newline character'''
+        if self.is_optimized_out():
+            return '(frame information optimized out)'
+        filename = self.filename()
+        try:
+            f = open(os_fsencode(filename), 'r')
+        except IOError:
+            return None
+        with f:
+            all_lines = f.readlines()
+            # Convert from 1-based current_line_num to 0-based list offset:
+            return all_lines[self.current_line_num()-1]
+
+    def write_repr(self, out, visited):
+        if self.is_optimized_out():
+            out.write('(frame information optimized out)')
+            return
+        out.write('Frame 0x%x, for file %s, line %i, in %s ('
+                  % (self.as_address(),
+                     self.co_filename.proxyval(visited),
+                     self.current_line_num(),
+                     self.co_name.proxyval(visited)))
+        first = True
+        for pyop_name, pyop_value in self.iter_locals():
+            if not first:
+                out.write(', ')
+            first = False
+
+            out.write(pyop_name.proxyval(visited))
+            out.write('=')
+            pyop_value.write_repr(out, visited)
+
+        out.write(')')
+
+    def print_traceback(self):
+        if self.is_optimized_out():
+            sys.stdout.write('  (frame information optimized out)\n')
+            return
+        visited = set()
+        sys.stdout.write('  File "%s", line %i, in %s\n'
+                  % (self.co_filename.proxyval(visited),
+                     self.current_line_num(),
+                     self.co_name.proxyval(visited)))
+
+class PySetObjectPtr(PyObjectPtr):
+    _typename = 'PySetObject'
+
+    @classmethod
+    def _dummy_key(self):
+        return gdb.lookup_global_symbol('_PySet_Dummy').value()
+
+    def __iter__(self):
+        dummy_ptr = self._dummy_key()
+        table = self.field('table')
+        for i in safe_range(self.field('mask') + 1):
+            setentry = table[i]
+            key = setentry['key']
+            if key != 0 and key != dummy_ptr:
+                yield PyObjectPtr.from_pyobject_ptr(key)
+
+    def proxyval(self, visited):
+        # Guard against infinite loops:
+        if self.as_address() in visited:
+            return ProxyAlreadyVisited('%s(...)' % self.safe_tp_name())
+        visited.add(self.as_address())
+
+        members = (key.proxyval(visited) for key in self)
+        if self.safe_tp_name() == 'frozenset':
+            return frozenset(members)
+        else:
+            return set(members)
+
+    def write_repr(self, out, visited):
+        # Emulate Python 3's set_repr
+        tp_name = self.safe_tp_name()
+
+        # Guard against infinite loops:
+        if self.as_address() in visited:
+            out.write('(...)')
+            return
+        visited.add(self.as_address())
+
+        # Python 3's set_repr special-cases the empty set:
+        if not self.field('used'):
+            out.write(tp_name)
+            out.write('()')
+            return
+
+        # Python 3 uses {} for set literals:
+        if tp_name != 'set':
+            out.write(tp_name)
+            out.write('(')
+
+        out.write('{')
+        first = True
+        for key in self:
+            if not first:
+                out.write(', ')
+            first = False
+            key.write_repr(out, visited)
+        out.write('}')
+
+        if tp_name != 'set':
+            out.write(')')
+
+
+class PyBytesObjectPtr(PyObjectPtr):
+    _typename = 'PyBytesObject'
+
+    def __str__(self):
+        field_ob_size = self.field('ob_size')
+        field_ob_sval = self.field('ob_sval')
+        char_ptr = field_ob_sval.address.cast(_type_unsigned_char_ptr())
+        return ''.join([chr(char_ptr[i]) for i in safe_range(field_ob_size)])
+
+    def proxyval(self, visited):
+        return str(self)
+
+    def write_repr(self, out, visited):
+        # Write this out as a Python 3 bytes literal, i.e. with a "b" prefix
+
+        # Get a PyStringObject* within the Python 2 gdb process:
+        proxy = self.proxyval(visited)
+
+        # Transliteration of Python 3's Objects/bytesobject.c:PyBytes_Repr
+        # to Python 2 code:
+        quote = "'"
+        if "'" in proxy and not '"' in proxy:
+            quote = '"'
+        out.write('b')
+        out.write(quote)
+        for byte in proxy:
+            if byte == quote or byte == '\\':
+                out.write('\\')
+                out.write(byte)
+            elif byte == '\t':
+                out.write('\\t')
+            elif byte == '\n':
+                out.write('\\n')
+            elif byte == '\r':
+                out.write('\\r')
+            elif byte < ' ' or ord(byte) >= 0x7f:
+                out.write('\\x')
+                out.write(hexdigits[(ord(byte) & 0xf0) >> 4])
+                out.write(hexdigits[ord(byte) & 0xf])
+            else:
+                out.write(byte)
+        out.write(quote)
+
+
+class PyStringObjectPtr(PyBytesObjectPtr):
+    _typename = 'PyStringObject'
+
+
+class PyTupleObjectPtr(PyObjectPtr):
+    _typename = 'PyTupleObject'
+
+    def __getitem__(self, i):
+        # Get the gdb.Value for the (PyObject*) with the given index:
+        field_ob_item = self.field('ob_item')
+        return field_ob_item[i]
+
+    def proxyval(self, visited):
+        # Guard against infinite loops:
+        if self.as_address() in visited:
+            return ProxyAlreadyVisited('(...)')
+        visited.add(self.as_address())
+
+        result = tuple(PyObjectPtr.from_pyobject_ptr(self[i]).proxyval(visited)
+                       for i in safe_range(int_from_int(self.field('ob_size'))))
+        return result
+
+    def write_repr(self, out, visited):
+        # Guard against infinite loops:
+        if self.as_address() in visited:
+            out.write('(...)')
+            return
+        visited.add(self.as_address())
+
+        out.write('(')
+        for i in safe_range(int_from_int(self.field('ob_size'))):
+            if i > 0:
+                out.write(', ')
+            element = PyObjectPtr.from_pyobject_ptr(self[i])
+            element.write_repr(out, visited)
+        if self.field('ob_size') == 1:
+            out.write(',)')
+        else:
+            out.write(')')
+
+class PyTypeObjectPtr(PyObjectPtr):
+    _typename = 'PyTypeObject'
+
+
+def _unichr_is_printable(char):
+    # Logic adapted from Python 3's Tools/unicode/makeunicodedata.py
+    if char == u" ":
+        return True
+    import unicodedata
+    return unicodedata.category(char) not in ("C", "Z")
+
+if sys.maxunicode >= 0x10000:
+    _unichr = unichr
+else:
+    # Needed for proper surrogate support if sizeof(Py_UNICODE) is 2 in gdb
+    def _unichr(x):
+        if x < 0x10000:
+            return unichr(x)
+        x -= 0x10000
+        ch1 = 0xD800 | (x >> 10)
+        ch2 = 0xDC00 | (x & 0x3FF)
+        return unichr(ch1) + unichr(ch2)
+
+
+class PyUnicodeObjectPtr(PyObjectPtr):
+    _typename = 'PyUnicodeObject'
+
+    def char_width(self):
+        _type_Py_UNICODE = gdb.lookup_type('Py_UNICODE')
+        return _type_Py_UNICODE.sizeof
+
+    def proxyval(self, visited):
+        global _is_pep393
+        if _is_pep393 is None:
+            fields = gdb.lookup_type('PyUnicodeObject').target().fields()
+            _is_pep393 = 'data' in [f.name for f in fields]
+        if _is_pep393:
+            # Python 3.3 and newer
+            may_have_surrogates = False
+            compact = self.field('_base')
+            ascii = compact['_base']
+            state = ascii['state']
+            is_compact_ascii = (int(state['ascii']) and int(state['compact']))
+            if not int(state['ready']):
+                # string is not ready
+                field_length = long(compact['wstr_length'])
+                may_have_surrogates = True
+                field_str = ascii['wstr']
+            else:
+                field_length = long(ascii['length'])
+                if is_compact_ascii:
+                    field_str = ascii.address + 1
+                elif int(state['compact']):
+                    field_str = compact.address + 1
+                else:
+                    field_str = self.field('data')['any']
+                repr_kind = int(state['kind'])
+                if repr_kind == 1:
+                    field_str = field_str.cast(_type_unsigned_char_ptr())
+                elif repr_kind == 2:
+                    field_str = field_str.cast(_type_unsigned_short_ptr())
+                elif repr_kind == 4:
+                    field_str = field_str.cast(_type_unsigned_int_ptr())
+        else:
+            # Python 3.2 and earlier
+            field_length = long(self.field('length'))
+            field_str = self.field('str')
+            may_have_surrogates = self.char_width() == 2
+
+        # Gather a list of ints from the Py_UNICODE array; these are either
+        # UCS-1, UCS-2 or UCS-4 code points:
+        if not may_have_surrogates:
+            Py_UNICODEs = [int(field_str[i]) for i in safe_range(field_length)]
+        else:
+            # A more elaborate routine if sizeof(Py_UNICODE) is 2 in the
+            # inferior process: we must join surrogate pairs.
+            Py_UNICODEs = []
+            i = 0
+            limit = safety_limit(field_length)
+            while i < limit:
+                ucs = int(field_str[i])
+                i += 1
+                if ucs < 0xD800 or ucs >= 0xDC00 or i == field_length:
+                    Py_UNICODEs.append(ucs)
+                    continue
+                # This could be a surrogate pair.
+                ucs2 = int(field_str[i])
+                if ucs2 < 0xDC00 or ucs2 > 0xDFFF:
+                    continue
+                code = (ucs & 0x03FF) << 10
+                code |= ucs2 & 0x03FF
+                code += 0x00010000
+                Py_UNICODEs.append(code)
+                i += 1
+
+        # Convert the int code points to unicode characters, and generate a
+        # local unicode instance.
+        # This splits surrogate pairs if sizeof(Py_UNICODE) is 2 here (in gdb).
+        result = u''.join([
+            (_unichr(ucs) if ucs <= 0x10ffff else '\ufffd')
+            for ucs in Py_UNICODEs])
+        return result
+
+    def write_repr(self, out, visited):
+        # Write this out as a Python 3 str literal, i.e. without a "u" prefix
+
+        # Get a PyUnicodeObject* within the Python 2 gdb process:
+        proxy = self.proxyval(visited)
+
+        # Transliteration of Python 3's Object/unicodeobject.c:unicode_repr
+        # to Python 2:
+        if "'" in proxy and '"' not in proxy:
+            quote = '"'
+        else:
+            quote = "'"
+        out.write(quote)
+
+        i = 0
+        while i < len(proxy):
+            ch = proxy[i]
+            i += 1
+
+            # Escape quotes and backslashes
+            if ch == quote or ch == '\\':
+                out.write('\\')
+                out.write(ch)
+
+            #  Map special whitespace to '\t', \n', '\r'
+            elif ch == '\t':
+                out.write('\\t')
+            elif ch == '\n':
+                out.write('\\n')
+            elif ch == '\r':
+                out.write('\\r')
+
+            # Map non-printable US ASCII to '\xhh' */
+            elif ch < ' ' or ch == 0x7F:
+                out.write('\\x')
+                out.write(hexdigits[(ord(ch) >> 4) & 0x000F])
+                out.write(hexdigits[ord(ch) & 0x000F])
+
+            # Copy ASCII characters as-is
+            elif ord(ch) < 0x7F:
+                out.write(ch)
+
+            # Non-ASCII characters
+            else:
+                ucs = ch
+                ch2 = None
+                if sys.maxunicode < 0x10000:
+                    # If sizeof(Py_UNICODE) is 2 here (in gdb), join
+                    # surrogate pairs before calling _unichr_is_printable.
+                    if (i < len(proxy)
+                    and 0xD800 <= ord(ch) < 0xDC00 \
+                    and 0xDC00 <= ord(proxy[i]) <= 0xDFFF):
+                        ch2 = proxy[i]
+                        ucs = ch + ch2
+                        i += 1
+
+                # Unfortuately, Python 2's unicode type doesn't seem
+                # to expose the "isprintable" method
+                printable = _unichr_is_printable(ucs)
+                if printable:
+                    try:
+                        ucs.encode(ENCODING)
+                    except UnicodeEncodeError:
+                        printable = False
+
+                # Map Unicode whitespace and control characters
+                # (categories Z* and C* except ASCII space)
+                if not printable:
+                    if ch2 is not None:
+                        # Match Python 3's representation of non-printable
+                        # wide characters.
+                        code = (ord(ch) & 0x03FF) << 10
+                        code |= ord(ch2) & 0x03FF
+                        code += 0x00010000
+                    else:
+                        code = ord(ucs)
+
+                    # Map 8-bit characters to '\\xhh'
+                    if code <= 0xff:
+                        out.write('\\x')
+                        out.write(hexdigits[(code >> 4) & 0x000F])
+                        out.write(hexdigits[code & 0x000F])
+                    # Map 21-bit characters to '\U00xxxxxx'
+                    elif code >= 0x10000:
+                        out.write('\\U')
+                        out.write(hexdigits[(code >> 28) & 0x0000000F])
+                        out.write(hexdigits[(code >> 24) & 0x0000000F])
+                        out.write(hexdigits[(code >> 20) & 0x0000000F])
+                        out.write(hexdigits[(code >> 16) & 0x0000000F])
+                        out.write(hexdigits[(code >> 12) & 0x0000000F])
+                        out.write(hexdigits[(code >> 8) & 0x0000000F])
+                        out.write(hexdigits[(code >> 4) & 0x0000000F])
+                        out.write(hexdigits[code & 0x0000000F])
+                    # Map 16-bit characters to '\uxxxx'
+                    else:
+                        out.write('\\u')
+                        out.write(hexdigits[(code >> 12) & 0x000F])
+                        out.write(hexdigits[(code >> 8) & 0x000F])
+                        out.write(hexdigits[(code >> 4) & 0x000F])
+                        out.write(hexdigits[code & 0x000F])
+                else:
+                    # Copy characters as-is
+                    out.write(ch)
+                    if ch2 is not None:
+                        out.write(ch2)
+
+        out.write(quote)
+
+
+class wrapperobject(PyObjectPtr):
+    _typename = 'wrapperobject'
+
+    def safe_name(self):
+        try:
+            name = self.field('descr')['d_base']['name'].string()
+            return repr(name)
+        except (NullPyObjectPtr, RuntimeError):
+            return '<unknown name>'
+
+    def safe_tp_name(self):
+        try:
+            return self.field('self')['ob_type']['tp_name'].string()
+        except (NullPyObjectPtr, RuntimeError):
+            return '<unknown tp_name>'
+
+    def safe_self_addresss(self):
+        try:
+            address = long(self.field('self'))
+            return '%#x' % address
+        except (NullPyObjectPtr, RuntimeError):
+            return '<failed to get self address>'
+
+    def proxyval(self, visited):
+        name = self.safe_name()
+        tp_name = self.safe_tp_name()
+        self_address = self.safe_self_addresss()
+        return ("<method-wrapper %s of %s object at %s>"
+                % (name, tp_name, self_address))
+
+    def write_repr(self, out, visited):
+        proxy = self.proxyval(visited)
+        out.write(proxy)
+
+
+def int_from_int(gdbval):
+    return int(str(gdbval))
+
+
+def stringify(val):
+    # TODO: repr() puts everything on one line; pformat can be nicer, but
+    # can lead to v.long results; this function isolates the choice
+    if True:
+        return repr(val)
+    else:
+        from pprint import pformat
+        return pformat(val)
+
+
+class PyObjectPtrPrinter:
+    "Prints a (PyObject*)"
+
+    def __init__ (self, gdbval):
+        self.gdbval = gdbval
+
+    def to_string (self):
+        pyop = PyObjectPtr.from_pyobject_ptr(self.gdbval)
+        if True:
+            return pyop.get_truncated_repr(MAX_OUTPUT_LEN)
+        else:
+            # Generate full proxy value then stringify it.
+            # Doing so could be expensive
+            proxyval = pyop.proxyval(set())
+            return stringify(proxyval)
+
+def pretty_printer_lookup(gdbval):
+    type = gdbval.type.unqualified()
+    if type.code != gdb.TYPE_CODE_PTR:
+        return None
+
+    type = type.target().unqualified()
+    t = str(type)
+    if t in ("PyObject", "PyFrameObject", "PyUnicodeObject", "wrapperobject"):
+        return PyObjectPtrPrinter(gdbval)
+
+"""
+During development, I've been manually invoking the code in this way:
+(gdb) python
+
+import sys
+sys.path.append('/home/david/coding/python-gdb')
+import libpython
+end
+
+then reloading it after each edit like this:
+(gdb) python reload(libpython)
+
+The following code should ensure that the prettyprinter is registered
+if the code is autoloaded by gdb when visiting libpython.so, provided
+that this python file is installed to the same path as the library (or its
+.debug file) plus a "-gdb.py" suffix, e.g:
+  /usr/lib/libpython2.6.so.1.0-gdb.py
+  /usr/lib/debug/usr/lib/libpython2.6.so.1.0.debug-gdb.py
+"""
+def register (obj):
+    if obj is None:
+        obj = gdb
+
+    # Wire up the pretty-printer
+    obj.pretty_printers.append(pretty_printer_lookup)
+
+register (gdb.current_objfile ())
+
+
+
+# Unfortunately, the exact API exposed by the gdb module varies somewhat
+# from build to build
+# See http://bugs.python.org/issue8279?#msg102276
+
+class Frame(object):
+    '''
+    Wrapper for gdb.Frame, adding various methods
+    '''
+    def __init__(self, gdbframe):
+        self._gdbframe = gdbframe
+
+    def older(self):
+        older = self._gdbframe.older()
+        if older:
+            return Frame(older)
+        else:
+            return None
+
+    def newer(self):
+        newer = self._gdbframe.newer()
+        if newer:
+            return Frame(newer)
+        else:
+            return None
+
+    def select(self):
+        '''If supported, select this frame and return True; return False if unsupported
+
+        Not all builds have a gdb.Frame.select method; seems to be present on Fedora 12
+        onwards, but absent on Ubuntu buildbot'''
+        if not hasattr(self._gdbframe, 'select'):
+            print ('Unable to select frame: '
+                   'this build of gdb does not expose a gdb.Frame.select method')
+            return False
+        self._gdbframe.select()
+        return True
+
+    def get_index(self):
+        '''Calculate index of frame, starting at 0 for the newest frame within
+        this thread'''
+        index = 0
+        # Go down until you reach the newest frame:
+        iter_frame = self
+        while iter_frame.newer():
+            index += 1
+            iter_frame = iter_frame.newer()
+        return index
+
+    # We divide frames into:
+    #   - "python frames":
+    #       - "bytecode frames" i.e. PyEval_EvalFrameEx
+    #       - "other python frames": things that are of interest from a python
+    #         POV, but aren't bytecode (e.g. GC, GIL)
+    #   - everything else
+
+    def is_python_frame(self):
+        '''Is this a _PyEval_EvalFrameDefault frame, or some other important
+        frame? (see is_other_python_frame for what "important" means in this
+        context)'''
+        if self.is_evalframe():
+            return True
+        if self.is_other_python_frame():
+            return True
+        return False
+
+    def is_evalframe(self):
+        '''Is this a _PyEval_EvalFrameDefault frame?'''
+        if self._gdbframe.name() == EVALFRAME:
+            '''
+            I believe we also need to filter on the inline
+            struct frame_id.inline_depth, only regarding frames with
+            an inline depth of 0 as actually being this function
+
+            So we reject those with type gdb.INLINE_FRAME
+            '''
+            if self._gdbframe.type() == gdb.NORMAL_FRAME:
+                # We have a _PyEval_EvalFrameDefault frame:
+                return True
+
+        return False
+
+    def is_other_python_frame(self):
+        '''Is this frame worth displaying in python backtraces?
+        Examples:
+          - waiting on the GIL
+          - garbage-collecting
+          - within a CFunction
+         If it is, return a descriptive string
+         For other frames, return False
+         '''
+        if self.is_waiting_for_gil():
+            return 'Waiting for the GIL'
+
+        if self.is_gc_collect():
+            return 'Garbage-collecting'
+
+        # Detect invocations of PyCFunction instances:
+        frame = self._gdbframe
+        caller = frame.name()
+        if not caller:
+            return False
+
+        if caller in ('_PyCFunction_FastCallDict',
+                      '_PyCFunction_FastCallKeywords'):
+            arg_name = 'func'
+            # Within that frame:
+            #   "func" is the local containing the PyObject* of the
+            # PyCFunctionObject instance
+            #   "f" is the same value, but cast to (PyCFunctionObject*)
+            #   "self" is the (PyObject*) of the 'self'
+            try:
+                # Use the prettyprinter for the func:
+                func = frame.read_var(arg_name)
+                return str(func)
+            except RuntimeError:
+                return 'PyCFunction invocation (unable to read %s)' % arg_name
+
+        if caller == 'wrapper_call':
+            try:
+                func = frame.read_var('wp')
+                return str(func)
+            except RuntimeError:
+                return '<wrapper_call invocation>'
+
+        # This frame isn't worth reporting:
+        return False
+
+    def is_waiting_for_gil(self):
+        '''Is this frame waiting on the GIL?'''
+        # This assumes the _POSIX_THREADS version of Python/ceval_gil.h:
+        name = self._gdbframe.name()
+        if name:
+            return 'pthread_cond_timedwait' in name
+
+    def is_gc_collect(self):
+        '''Is this frame "collect" within the garbage-collector?'''
+        return self._gdbframe.name() == 'collect'
+
+    def get_pyop(self):
+        try:
+            f = self._gdbframe.read_var('f')
+            frame = PyFrameObjectPtr.from_pyobject_ptr(f)
+            if not frame.is_optimized_out():
+                return frame
+            # gdb is unable to get the "f" argument of PyEval_EvalFrameEx()
+            # because it was "optimized out". Try to get "f" from the frame
+            # of the caller, PyEval_EvalCodeEx().
+            orig_frame = frame
+            caller = self._gdbframe.older()
+            if caller:
+                f = caller.read_var('f')
+                frame = PyFrameObjectPtr.from_pyobject_ptr(f)
+                if not frame.is_optimized_out():
+                    return frame
+            return orig_frame
+        except ValueError:
+            return None
+
+    @classmethod
+    def get_selected_frame(cls):
+        _gdbframe = gdb.selected_frame()
+        if _gdbframe:
+            return Frame(_gdbframe)
+        return None
+
+    @classmethod
+    def get_selected_python_frame(cls):
+        '''Try to obtain the Frame for the python-related code in the selected
+        frame, or None'''
+        try:
+            frame = cls.get_selected_frame()
+        except gdb.error:
+            # No frame: Python didn't start yet
+            return None
+
+        while frame:
+            if frame.is_python_frame():
+                return frame
+            frame = frame.older()
+
+        # Not found:
+        return None
+
+    @classmethod
+    def get_selected_bytecode_frame(cls):
+        '''Try to obtain the Frame for the python bytecode interpreter in the
+        selected GDB frame, or None'''
+        frame = cls.get_selected_frame()
+
+        while frame:
+            if frame.is_evalframe():
+                return frame
+            frame = frame.older()
+
+        # Not found:
+        return None
+
+    def print_summary(self):
+        if self.is_evalframe():
+            pyop = self.get_pyop()
+            if pyop:
+                line = pyop.get_truncated_repr(MAX_OUTPUT_LEN)
+                write_unicode(sys.stdout, '#%i %s\n' % (self.get_index(), line))
+                if not pyop.is_optimized_out():
+                    line = pyop.current_line()
+                    if line is not None:
+                        sys.stdout.write('    %s\n' % line.strip())
+            else:
+                sys.stdout.write('#%i (unable to read python frame information)\n' % self.get_index())
+        else:
+            info = self.is_other_python_frame()
+            if info:
+                sys.stdout.write('#%i %s\n' % (self.get_index(), info))
+            else:
+                sys.stdout.write('#%i\n' % self.get_index())
+
+    def print_traceback(self):
+        if self.is_evalframe():
+            pyop = self.get_pyop()
+            if pyop:
+                pyop.print_traceback()
+                if not pyop.is_optimized_out():
+                    line = pyop.current_line()
+                    if line is not None:
+                        sys.stdout.write('    %s\n' % line.strip())
+            else:
+                sys.stdout.write('  (unable to read python frame information)\n')
+        else:
+            info = self.is_other_python_frame()
+            if info:
+                sys.stdout.write('  %s\n' % info)
+            else:
+                sys.stdout.write('  (not a python frame)\n')
+
+class PyList(gdb.Command):
+    '''List the current Python source code, if any
+
+    Use
+       py-list START
+    to list at a different line number within the python source.
+
+    Use
+       py-list START, END
+    to list a specific range of lines within the python source.
+    '''
+
+    def __init__(self):
+        gdb.Command.__init__ (self,
+                              "py-list",
+                              gdb.COMMAND_FILES,
+                              gdb.COMPLETE_NONE)
+
+
+    def invoke(self, args, from_tty):
+        import re
+
+        start = None
+        end = None
+
+        m = re.match(r'\s*(\d+)\s*', args)
+        if m:
+            start = int(m.group(0))
+            end = start + 10
+
+        m = re.match(r'\s*(\d+)\s*,\s*(\d+)\s*', args)
+        if m:
+            start, end = map(int, m.groups())
+
+        # py-list requires an actual PyEval_EvalFrameEx frame:
+        frame = Frame.get_selected_bytecode_frame()
+        if not frame:
+            print('Unable to locate gdb frame for python bytecode interpreter')
+            return
+
+        pyop = frame.get_pyop()
+        if not pyop or pyop.is_optimized_out():
+            print('Unable to read information on python frame')
+            return
+
+        filename = pyop.filename()
+        lineno = pyop.current_line_num()
+
+        if start is None:
+            start = lineno - 5
+            end = lineno + 5
+
+        if start<1:
+            start = 1
+
+        try:
+            f = open(os_fsencode(filename), 'r')
+        except IOError as err:
+            sys.stdout.write('Unable to open %s: %s\n'
+                             % (filename, err))
+            return
+        with f:
+            all_lines = f.readlines()
+            # start and end are 1-based, all_lines is 0-based;
+            # so [start-1:end] as a python slice gives us [start, end] as a
+            # closed interval
+            for i, line in enumerate(all_lines[start-1:end]):
+                linestr = str(i+start)
+                # Highlight current line:
+                if i + start == lineno:
+                    linestr = '>' + linestr
+                sys.stdout.write('%4s    %s' % (linestr, line))
+
+
+# ...and register the command:
+PyList()
+
+def move_in_stack(move_up):
+    '''Move up or down the stack (for the py-up/py-down command)'''
+    frame = Frame.get_selected_python_frame()
+    if not frame:
+        print('Unable to locate python frame')
+        return
+
+    while frame:
+        if move_up:
+            iter_frame = frame.older()
+        else:
+            iter_frame = frame.newer()
+
+        if not iter_frame:
+            break
+
+        if iter_frame.is_python_frame():
+            # Result:
+            if iter_frame.select():
+                iter_frame.print_summary()
+            return
+
+        frame = iter_frame
+
+    if move_up:
+        print('Unable to find an older python frame')
+    else:
+        print('Unable to find a newer python frame')
+
+class PyUp(gdb.Command):
+    'Select and print the python stack frame that called this one (if any)'
+    def __init__(self):
+        gdb.Command.__init__ (self,
+                              "py-up",
+                              gdb.COMMAND_STACK,
+                              gdb.COMPLETE_NONE)
+
+
+    def invoke(self, args, from_tty):
+        move_in_stack(move_up=True)
+
+class PyDown(gdb.Command):
+    'Select and print the python stack frame called by this one (if any)'
+    def __init__(self):
+        gdb.Command.__init__ (self,
+                              "py-down",
+                              gdb.COMMAND_STACK,
+                              gdb.COMPLETE_NONE)
+
+
+    def invoke(self, args, from_tty):
+        move_in_stack(move_up=False)
+
+# Not all builds of gdb have gdb.Frame.select
+if hasattr(gdb.Frame, 'select'):
+    PyUp()
+    PyDown()
+
+class PyBacktraceFull(gdb.Command):
+    'Display the current python frame and all the frames within its call stack (if any)'
+    def __init__(self):
+        gdb.Command.__init__ (self,
+                              "py-bt-full",
+                              gdb.COMMAND_STACK,
+                              gdb.COMPLETE_NONE)
+
+
+    def invoke(self, args, from_tty):
+        frame = Frame.get_selected_python_frame()
+        if not frame:
+            print('Unable to locate python frame')
+            return
+
+        while frame:
+            if frame.is_python_frame():
+                frame.print_summary()
+            frame = frame.older()
+
+PyBacktraceFull()
+
+class PyBacktrace(gdb.Command):
+    'Display the current python frame and all the frames within its call stack (if any)'
+    def __init__(self):
+        gdb.Command.__init__ (self,
+                              "py-bt",
+                              gdb.COMMAND_STACK,
+                              gdb.COMPLETE_NONE)
+
+
+    def invoke(self, args, from_tty):
+        frame = Frame.get_selected_python_frame()
+        if not frame:
+            print('Unable to locate python frame')
+            return
+
+        sys.stdout.write('Traceback (most recent call first):\n')
+        while frame:
+            if frame.is_python_frame():
+                frame.print_traceback()
+            frame = frame.older()
+
+PyBacktrace()
+
+class PyPrint(gdb.Command):
+    'Look up the given python variable name, and print it'
+    def __init__(self):
+        gdb.Command.__init__ (self,
+                              "py-print",
+                              gdb.COMMAND_DATA,
+                              gdb.COMPLETE_NONE)
+
+
+    def invoke(self, args, from_tty):
+        name = str(args)
+
+        frame = Frame.get_selected_python_frame()
+        if not frame:
+            print('Unable to locate python frame')
+            return
+
+        pyop_frame = frame.get_pyop()
+        if not pyop_frame:
+            print('Unable to read information on python frame')
+            return
+
+        pyop_var, scope = pyop_frame.get_var_by_name(name)
+
+        if pyop_var:
+            print('%s %r = %s'
+                   % (scope,
+                      name,
+                      pyop_var.get_truncated_repr(MAX_OUTPUT_LEN)))
+        else:
+            print('%r not found' % name)
+
+PyPrint()
+
+class PyLocals(gdb.Command):
+    'Look up the given python variable name, and print it'
+    def __init__(self, command="py-locals"):
+        gdb.Command.__init__ (self,
+                              command,
+                              gdb.COMMAND_DATA,
+                              gdb.COMPLETE_NONE)
+
+
+    def invoke(self, args, from_tty):
+        name = str(args)
+
+        frame = Frame.get_selected_python_frame()
+        if not frame:
+            print('Unable to locate python frame')
+            return
+
+        pyop_frame = frame.get_pyop()
+        if not pyop_frame:
+            print('Unable to read information on python frame')
+            return
+
+        namespace = self.get_namespace(pyop_frame)
+        namespace = [(name.proxyval(set()), val) for name, val in namespace]
+
+        if namespace:
+            name, val = max(namespace, key=lambda item: len(item[0]))
+            max_name_length = len(name)
+
+            for name, pyop_value in namespace:
+                value = pyop_value.get_truncated_repr(MAX_OUTPUT_LEN)
+                print('%-*s = %s' % (max_name_length, name, value))
+
+    def get_namespace(self, pyop_frame):
+        return pyop_frame.iter_locals()
+
+PyLocals()
+
+
+##################################################################
+## added, not in CPython
+##################################################################
+
+import re
+import warnings
+import tempfile
+import textwrap
+import itertools
+
+class PyGlobals(PyLocals):
+    'List all the globals in the currently select Python frame'
+
+    def get_namespace(self, pyop_frame):
+        return pyop_frame.iter_globals()
+
+
+PyGlobals("py-globals")
+
+
+class PyNameEquals(gdb.Function):
+
+    def _get_pycurframe_attr(self, attr):
+        frame = Frame(gdb.selected_frame())
+        if frame.is_evalframeex():
+            pyframe = frame.get_pyop()
+            if pyframe is None:
+                warnings.warn("Use a Python debug build, Python breakpoints "
+                              "won't work otherwise.")
+                return None
+
+            return getattr(pyframe, attr).proxyval(set())
+
+        return None
+
+    def invoke(self, funcname):
+        attr = self._get_pycurframe_attr('co_name')
+        return attr is not None and attr == funcname.string()
+
+PyNameEquals("pyname_equals")
+
+
+class PyModEquals(PyNameEquals):
+
+    def invoke(self, modname):
+        attr = self._get_pycurframe_attr('co_filename')
+        if attr is not None:
+            filename, ext = os.path.splitext(os.path.basename(attr))
+            return filename == modname.string()
+        return False
+
+PyModEquals("pymod_equals")
+
+
+class PyBreak(gdb.Command):
+    """
+    Set a Python breakpoint. Examples:
+
+    Break on any function or method named 'func' in module 'modname'
+
+        py-break modname.func
+
+    Break on any function or method named 'func'
+
+        py-break func
+    """
+
+    def invoke(self, funcname, from_tty):
+        if '.' in funcname:
+            modname, dot, funcname = funcname.rpartition('.')
+            cond = '$pyname_equals("%s") && $pymod_equals("%s")' % (funcname,
+                                                                    modname)
+        else:
+            cond = '$pyname_equals("%s")' % funcname
+
+        gdb.execute('break PyEval_EvalFrameEx if ' + cond)
+
+PyBreak("py-break", gdb.COMMAND_RUNNING, gdb.COMPLETE_NONE)
+
+
+class _LoggingState(object):
+    """
+    State that helps to provide a reentrant gdb.execute() function.
+    """
+
+    def __init__(self):
+        f = tempfile.NamedTemporaryFile('r+')
+        self.file = f
+        self.filename = f.name
+        self.fd = f.fileno()
+        _execute("set logging file %s" % self.filename)
+        self.file_position_stack = []
+
+    def __enter__(self):
+        if not self.file_position_stack:
+            _execute("set logging redirect on")
+            _execute("set logging on")
+            _execute("set pagination off")
+
+        self.file_position_stack.append(os.fstat(self.fd).st_size)
+        return self
+
+    def getoutput(self):
+        gdb.flush()
+        self.file.seek(self.file_position_stack[-1])
+        result = self.file.read()
+        return result
+
+    def __exit__(self, exc_type, exc_val, tb):
+        startpos = self.file_position_stack.pop()
+        self.file.seek(startpos)
+        self.file.truncate()
+        if not self.file_position_stack:
+            _execute("set logging off")
+            _execute("set logging redirect off")
+            _execute("set pagination on")
+
+
+def execute(command, from_tty=False, to_string=False):
+    """
+    Replace gdb.execute() with this function and have it accept a 'to_string'
+    argument (new in 7.2). Have it properly capture stderr also. Ensure
+    reentrancy.
+    """
+    if to_string:
+        with _logging_state as state:
+            _execute(command, from_tty)
+            return state.getoutput()
+    else:
+        _execute(command, from_tty)
+
+
+_execute = gdb.execute
+gdb.execute = execute
+_logging_state = _LoggingState()
+
+
+def get_selected_inferior():
+    """
+    Return the selected inferior in gdb.
+    """
+    # Woooh, another bug in gdb! Is there an end in sight?
+    # http://sourceware.org/bugzilla/show_bug.cgi?id=12212
+    return gdb.inferiors()[0]
+
+    selected_thread = gdb.selected_thread()
+
+    for inferior in gdb.inferiors():
+        for thread in inferior.threads():
+            if thread == selected_thread:
+                return inferior
+
+
+def source_gdb_script(script_contents, to_string=False):
+    """
+    Source a gdb script with script_contents passed as a string. This is useful
+    to provide defines for py-step and py-next to make them repeatable (this is
+    not possible with gdb.execute()). See
+    http://sourceware.org/bugzilla/show_bug.cgi?id=12216
+    """
+    fd, filename = tempfile.mkstemp()
+    f = os.fdopen(fd, 'w')
+    f.write(script_contents)
+    f.close()
+    gdb.execute("source %s" % filename, to_string=to_string)
+    os.remove(filename)
+
+
+def register_defines():
+    source_gdb_script(textwrap.dedent("""\
+        define py-step
+        -py-step
+        end
+
+        define py-next
+        -py-next
+        end
+
+        document py-step
+        %s
+        end
+
+        document py-next
+        %s
+        end
+    """) % (PyStep.__doc__, PyNext.__doc__))
+
+
+def stackdepth(frame):
+    "Tells the stackdepth of a gdb frame."
+    depth = 0
+    while frame:
+        frame = frame.older()
+        depth += 1
+
+    return depth
+
+
+class ExecutionControlCommandBase(gdb.Command):
+    """
+    Superclass for language specific execution control. Language specific
+    features should be implemented by lang_info using the LanguageInfo
+    interface. 'name' is the name of the command.
+    """
+
+    def __init__(self, name, lang_info):
+        super(ExecutionControlCommandBase, self).__init__(
+                                name, gdb.COMMAND_RUNNING, gdb.COMPLETE_NONE)
+        self.lang_info = lang_info
+
+    def install_breakpoints(self):
+        all_locations = itertools.chain(
+            self.lang_info.static_break_functions(),
+            self.lang_info.runtime_break_functions())
+
+        for location in all_locations:
+            result = gdb.execute('break %s' % location, to_string=True)
+            yield re.search(r'Breakpoint (\d+)', result).group(1)
+
+    def delete_breakpoints(self, breakpoint_list):
+        for bp in breakpoint_list:
+            gdb.execute("delete %s" % bp)
+
+    def filter_output(self, result):
+        reflags = re.MULTILINE
+
+        output_on_halt = [
+            (r'^Program received signal .*', reflags|re.DOTALL),
+            (r'.*[Ww]arning.*', 0),
+            (r'^Program exited .*', reflags),
+        ]
+
+        output_always = [
+            # output when halting on a watchpoint
+            (r'^(Old|New) value = .*', reflags),
+            # output from the 'display' command
+            (r'^\d+: \w+ = .*', reflags),
+        ]
+
+        def filter_output(regexes):
+            output = []
+            for regex, flags in regexes:
+                for match in re.finditer(regex, result, flags):
+                    output.append(match.group(0))
+
+            return '\n'.join(output)
+
+        # Filter the return value output of the 'finish' command
+        match_finish = re.search(r'^Value returned is \$\d+ = (.*)', result,
+                                 re.MULTILINE)
+        if match_finish:
+            finish_output = 'Value returned: %s\n' % match_finish.group(1)
+        else:
+            finish_output = ''
+
+        return (filter_output(output_on_halt),
+                finish_output + filter_output(output_always))
+
+    def stopped(self):
+        return get_selected_inferior().pid == 0
+
+    def finish_executing(self, result):
+        """
+        After doing some kind of code running in the inferior, print the line
+        of source code or the result of the last executed gdb command (passed
+        in as the `result` argument).
+        """
+        output_on_halt, output_always = self.filter_output(result)
+
+        if self.stopped():
+            print(output_always)
+            print(output_on_halt)
+        else:
+            frame = gdb.selected_frame()
+            source_line = self.lang_info.get_source_line(frame)
+            if self.lang_info.is_relevant_function(frame):
+                raised_exception = self.lang_info.exc_info(frame)
+                if raised_exception:
+                    print(raised_exception)
+
+            if source_line:
+                if output_always.rstrip():
+                    print(output_always.rstrip())
+                print(source_line)
+            else:
+                print(result)
+
+    def _finish(self):
+        """
+        Execute until the function returns (or until something else makes it
+        stop)
+        """
+        if gdb.selected_frame().older() is not None:
+            return gdb.execute('finish', to_string=True)
+        else:
+            # outermost frame, continue
+            return gdb.execute('cont', to_string=True)
+
+    def _finish_frame(self):
+        """
+        Execute until the function returns to a relevant caller.
+        """
+        while True:
+            result = self._finish()
+
+            try:
+                frame = gdb.selected_frame()
+            except RuntimeError:
+                break
+
+            hitbp = re.search(r'Breakpoint (\d+)', result)
+            is_relevant = self.lang_info.is_relevant_function(frame)
+            if hitbp or is_relevant or self.stopped():
+                break
+
+        return result
+
+    def finish(self, *args):
+        "Implements the finish command."
+        result = self._finish_frame()
+        self.finish_executing(result)
+
+    def step(self, stepinto, stepover_command='next'):
+        """
+        Do a single step or step-over. Returns the result of the last gdb
+        command that made execution stop.
+
+        This implementation, for stepping, sets (conditional) breakpoints for
+        all functions that are deemed relevant. It then does a step over until
+        either something halts execution, or until the next line is reached.
+
+        If, however, stepover_command is given, it should be a string gdb
+        command that continues execution in some way. The idea is that the
+        caller has set a (conditional) breakpoint or watchpoint that can work
+        more efficiently than the step-over loop. For Python this means setting
+        a watchpoint for f->f_lasti, which means we can then subsequently
+        "finish" frames.
+        We want f->f_lasti instead of f->f_lineno, because the latter only
+        works properly with local trace functions, see
+        PyFrameObjectPtr.current_line_num and PyFrameObjectPtr.addr2line.
+        """
+        if stepinto:
+            breakpoint_list = list(self.install_breakpoints())
+
+        beginframe = gdb.selected_frame()
+
+        if self.lang_info.is_relevant_function(beginframe):
+            # If we start in a relevant frame, initialize stuff properly. If
+            # we don't start in a relevant frame, the loop will halt
+            # immediately. So don't call self.lang_info.lineno() as it may
+            # raise for irrelevant frames.
+            beginline = self.lang_info.lineno(beginframe)
+
+            if not stepinto:
+                depth = stackdepth(beginframe)
+
+        newframe = beginframe
+
+        while True:
+            if self.lang_info.is_relevant_function(newframe):
+                result = gdb.execute(stepover_command, to_string=True)
+            else:
+                result = self._finish_frame()
+
+            if self.stopped():
+                break
+
+            newframe = gdb.selected_frame()
+            is_relevant_function = self.lang_info.is_relevant_function(newframe)
+            try:
+                framename = newframe.name()
+            except RuntimeError:
+                framename = None
+
+            m = re.search(r'Breakpoint (\d+)', result)
+            if m:
+                if is_relevant_function and m.group(1) in breakpoint_list:
+                    # although we hit a breakpoint, we still need to check
+                    # that the function, in case hit by a runtime breakpoint,
+                    # is in the right context
+                    break
+
+            if newframe != beginframe:
+                # new function
+
+                if not stepinto:
+                    # see if we returned to the caller
+                    newdepth = stackdepth(newframe)
+                    is_relevant_function = (newdepth < depth and
+                                            is_relevant_function)
+
+                if is_relevant_function:
+                    break
+            else:
+                # newframe equals beginframe, check for a difference in the
+                # line number
+                lineno = self.lang_info.lineno(newframe)
+                if lineno and lineno != beginline:
+                    break
+
+        if stepinto:
+            self.delete_breakpoints(breakpoint_list)
+
+        self.finish_executing(result)
+
+    def run(self, args, from_tty):
+        self.finish_executing(gdb.execute('run ' + args, to_string=True))
+
+    def cont(self, *args):
+        self.finish_executing(gdb.execute('cont', to_string=True))
+
+
+class LanguageInfo(object):
+    """
+    This class defines the interface that ExecutionControlCommandBase needs to
+    provide language-specific execution control.
+
+    Classes that implement this interface should implement:
+
+        lineno(frame)
+            Tells the current line number (only called for a relevant frame).
+            If lineno is a false value it is not checked for a difference.
+
+        is_relevant_function(frame)
+            tells whether we care about frame 'frame'
+
+        get_source_line(frame)
+            get the line of source code for the current line (only called for a
+            relevant frame). If the source code cannot be retrieved this
+            function should return None
+
+        exc_info(frame) -- optional
+            tells whether an exception was raised, if so, it should return a
+            string representation of the exception value, None otherwise.
+
+        static_break_functions()
+            returns an iterable of function names that are considered relevant
+            and should halt step-into execution. This is needed to provide a
+            performing step-into
+
+        runtime_break_functions() -- optional
+            list of functions that we should break into depending on the
+            context
+    """
+
+    def exc_info(self, frame):
+        "See this class' docstring."
+
+    def runtime_break_functions(self):
+        """
+        Implement this if the list of step-into functions depends on the
+        context.
+        """
+        return ()
+
+
+class PythonInfo(LanguageInfo):
+
+    def pyframe(self, frame):
+        pyframe = Frame(frame).get_pyop()
+        if pyframe:
+            return pyframe
+        else:
+            raise gdb.RuntimeError(
+                "Unable to find the Python frame, run your code with a debug "
+                "build (configure with --with-pydebug or compile with -g).")
+
+    def lineno(self, frame):
+        return self.pyframe(frame).current_line_num()
+
+    def is_relevant_function(self, frame):
+        return Frame(frame).is_evalframeex()
+
+    def get_source_line(self, frame):
+        try:
+            pyframe = self.pyframe(frame)
+            return '%4d    %s' % (pyframe.current_line_num(),
+                                  pyframe.current_line().rstrip())
+        except IOError:
+            return None
+
+    def exc_info(self, frame):
+        try:
+            tstate = frame.read_var('tstate').dereference()
+            if gdb.parse_and_eval('tstate->frame == f'):
+                # tstate local variable initialized, check for an exception
+                inf_type = tstate['curexc_type']
+                inf_value = tstate['curexc_value']
+
+                if inf_type:
+                    return 'An exception was raised: %s' % (inf_value,)
+        except (ValueError, RuntimeError):
+            # Could not read the variable tstate or it's memory, it's ok
+            pass
+
+    def static_break_functions(self):
+        yield 'PyEval_EvalFrameEx'
+
+
+class PythonStepperMixin(object):
+    """
+    Make this a mixin so CyStep can also inherit from this and use a
+    CythonCodeStepper at the same time.
+    """
+
+    def python_step(self, stepinto):
+        """
+        Set a watchpoint on the Python bytecode instruction pointer and try
+        to finish the frame
+        """
+        output = gdb.execute('watch f->f_lasti', to_string=True)
+        watchpoint = int(re.search(r'[Ww]atchpoint (\d+):', output).group(1))
+        self.step(stepinto=stepinto, stepover_command='finish')
+        gdb.execute('delete %s' % watchpoint)
+
+
+class PyStep(ExecutionControlCommandBase, PythonStepperMixin):
+    "Step through Python code."
+
+    stepinto = True
+
+    def invoke(self, args, from_tty):
+        self.python_step(stepinto=self.stepinto)
+
+
+class PyNext(PyStep):
+    "Step-over Python code."
+
+    stepinto = False
+
+
+class PyFinish(ExecutionControlCommandBase):
+    "Execute until function returns to a caller."
+
+    invoke = ExecutionControlCommandBase.finish
+
+
+class PyRun(ExecutionControlCommandBase):
+    "Run the program."
+
+    invoke = ExecutionControlCommandBase.run
+
+
+class PyCont(ExecutionControlCommandBase):
+
+    invoke = ExecutionControlCommandBase.cont
+
+
+def _pointervalue(gdbval):
+    """
+    Return the value of the pointer as a Python int.
+
+    gdbval.type must be a pointer type
+    """
+    # don't convert with int() as it will raise a RuntimeError
+    if gdbval.address is not None:
+        return int(gdbval.address)
+    else:
+        # the address attribute is None sometimes, in which case we can
+        # still convert the pointer to an int
+        return int(gdbval)
+
+
+def pointervalue(gdbval):
+    pointer = _pointervalue(gdbval)
+    try:
+        if pointer < 0:
+            raise gdb.GdbError("Negative pointer value, presumably a bug "
+                               "in gdb, aborting.")
+    except RuntimeError:
+        # work around yet another bug in gdb where you get random behaviour
+        # and tracebacks
+        pass
+
+    return pointer
+
+
+def get_inferior_unicode_postfix():
+    try:
+        gdb.parse_and_eval('PyUnicode_FromEncodedObject')
+    except RuntimeError:
+        try:
+            gdb.parse_and_eval('PyUnicodeUCS2_FromEncodedObject')
+        except RuntimeError:
+            return 'UCS4'
+        else:
+            return 'UCS2'
+    else:
+        return ''
+
+
+class PythonCodeExecutor(object):
+
+    Py_single_input = 256
+    Py_file_input = 257
+    Py_eval_input = 258
+
+    def malloc(self, size):
+        chunk = (gdb.parse_and_eval("(void *) malloc((size_t) %d)" % size))
+
+        pointer = pointervalue(chunk)
+        if pointer == 0:
+            raise gdb.GdbError("No memory could be allocated in the inferior.")
+
+        return pointer
+
+    def alloc_string(self, string):
+        pointer = self.malloc(len(string))
+        get_selected_inferior().write_memory(pointer, string)
+
+        return pointer
+
+    def alloc_pystring(self, string):
+        stringp = self.alloc_string(string)
+        PyString_FromStringAndSize = 'PyString_FromStringAndSize'
+
+        try:
+            gdb.parse_and_eval(PyString_FromStringAndSize)
+        except RuntimeError:
+            # Python 3
+            PyString_FromStringAndSize = ('PyUnicode%s_FromStringAndSize' %
+                                               (get_inferior_unicode_postfix(),))
+
+        try:
+            result = gdb.parse_and_eval(
+                '(PyObject *) %s((char *) %d, (size_t) %d)' % (
+                            PyString_FromStringAndSize, stringp, len(string)))
+        finally:
+            self.free(stringp)
+
+        pointer = pointervalue(result)
+        if pointer == 0:
+            raise gdb.GdbError("Unable to allocate Python string in "
+                               "the inferior.")
+
+        return pointer
+
+    def free(self, pointer):
+        gdb.parse_and_eval("free((void *) %d)" % pointer)
+
+    def incref(self, pointer):
+        "Increment the reference count of a Python object in the inferior."
+        gdb.parse_and_eval('Py_IncRef((PyObject *) %d)' % pointer)
+
+    def xdecref(self, pointer):
+        "Decrement the reference count of a Python object in the inferior."
+        # Py_DecRef is like Py_XDECREF, but a function. So we don't have
+        # to check for NULL. This should also decref all our allocated
+        # Python strings.
+        gdb.parse_and_eval('Py_DecRef((PyObject *) %d)' % pointer)
+
+    def evalcode(self, code, input_type, global_dict=None, local_dict=None):
+        """
+        Evaluate python code `code` given as a string in the inferior and
+        return the result as a gdb.Value. Returns a new reference in the
+        inferior.
+
+        Of course, executing any code in the inferior may be dangerous and may
+        leave the debuggee in an unsafe state or terminate it altogether.
+        """
+        if '\0' in code:
+            raise gdb.GdbError("String contains NUL byte.")
+
+        code += '\0'
+
+        pointer = self.alloc_string(code)
+
+        globalsp = pointervalue(global_dict)
+        localsp = pointervalue(local_dict)
+
+        if globalsp == 0 or localsp == 0:
+            raise gdb.GdbError("Unable to obtain or create locals or globals.")
+
+        code = """
+            PyRun_String(
+                (char *) %(code)d,
+                (int) %(start)d,
+                (PyObject *) %(globals)s,
+                (PyObject *) %(locals)d)
+        """ % dict(code=pointer, start=input_type,
+                   globals=globalsp, locals=localsp)
+
+        with FetchAndRestoreError():
+            try:
+                pyobject_return_value = gdb.parse_and_eval(code)
+            finally:
+                self.free(pointer)
+
+        return pyobject_return_value
+
+
+class FetchAndRestoreError(PythonCodeExecutor):
+    """
+    Context manager that fetches the error indicator in the inferior and
+    restores it on exit.
+    """
+
+    def __init__(self):
+        self.sizeof_PyObjectPtr = gdb.lookup_type('PyObject').pointer().sizeof
+        self.pointer = self.malloc(self.sizeof_PyObjectPtr * 3)
+
+        type = self.pointer
+        value = self.pointer + self.sizeof_PyObjectPtr
+        traceback = self.pointer + self.sizeof_PyObjectPtr * 2
+
+        self.errstate = type, value, traceback
+
+    def __enter__(self):
+        gdb.parse_and_eval("PyErr_Fetch(%d, %d, %d)" % self.errstate)
+
+    def __exit__(self, *args):
+        if gdb.parse_and_eval("(int) PyErr_Occurred()"):
+            gdb.parse_and_eval("PyErr_Print()")
+
+        pyerr_restore = ("PyErr_Restore("
+                            "(PyObject *) *%d,"
+                            "(PyObject *) *%d,"
+                            "(PyObject *) *%d)")
+
+        try:
+            gdb.parse_and_eval(pyerr_restore % self.errstate)
+        finally:
+            self.free(self.pointer)
+
+
+class FixGdbCommand(gdb.Command):
+
+    def __init__(self, command, actual_command):
+        super(FixGdbCommand, self).__init__(command, gdb.COMMAND_DATA,
+                                            gdb.COMPLETE_NONE)
+        self.actual_command = actual_command
+
+    def fix_gdb(self):
+        """
+        It seems that invoking either 'cy exec' and 'py-exec' work perfectly
+        fine, but after this gdb's python API is entirely broken.
+        Maybe some uncleared exception value is still set?
+        sys.exc_clear() didn't help. A demonstration:
+
+        (gdb) cy exec 'hello'
+        'hello'
+        (gdb) python gdb.execute('cont')
+        RuntimeError: Cannot convert value to int.
+        Error while executing Python code.
+        (gdb) python gdb.execute('cont')
+        [15148 refs]
+
+        Program exited normally.
+        """
+        warnings.filterwarnings('ignore', r'.*', RuntimeWarning,
+                                re.escape(__name__))
+        try:
+            int(gdb.parse_and_eval("(void *) 0")) == 0
+        except RuntimeError:
+            pass
+        # warnings.resetwarnings()
+
+    def invoke(self, args, from_tty):
+        self.fix_gdb()
+        try:
+            gdb.execute('%s %s' % (self.actual_command, args))
+        except RuntimeError as e:
+            raise gdb.GdbError(str(e))
+        self.fix_gdb()
+
+
+def _evalcode_python(executor, code, input_type):
+    """
+    Execute Python code in the most recent stack frame.
+    """
+    global_dict = gdb.parse_and_eval('PyEval_GetGlobals()')
+    local_dict = gdb.parse_and_eval('PyEval_GetLocals()')
+
+    if (pointervalue(global_dict) == 0 or pointervalue(local_dict) == 0):
+        raise gdb.GdbError("Unable to find the locals or globals of the "
+                           "most recent Python function (relative to the "
+                           "selected frame).")
+
+    return executor.evalcode(code, input_type, global_dict, local_dict)
+
+
+class PyExec(gdb.Command):
+
+    def readcode(self, expr):
+        if expr:
+            return expr, PythonCodeExecutor.Py_single_input
+        else:
+            lines = []
+            while True:
+                try:
+                    line = input('>')
+                except EOFError:
+                    break
+                else:
+                    if line.rstrip() == 'end':
+                        break
+
+                    lines.append(line)
+
+            return '\n'.join(lines), PythonCodeExecutor.Py_file_input
+
+    def invoke(self, expr, from_tty):
+        expr, input_type = self.readcode(expr)
+        executor = PythonCodeExecutor()
+        executor.xdecref(_evalcode_python(executor, input_type, global_dict, local_dict))
+
+
+gdb.execute('set breakpoint pending on')
+
+if hasattr(gdb, 'GdbError'):
+     # Wrap py-step and py-next in gdb defines to make them repeatable.
+    py_step = PyStep('-py-step', PythonInfo())
+    py_next = PyNext('-py-next', PythonInfo())
+    register_defines()
+    py_finish = PyFinish('py-finish', PythonInfo())
+    py_run = PyRun('py-run', PythonInfo())
+    py_cont = PyCont('py-cont', PythonInfo())
+
+    py_exec = FixGdbCommand('py-exec', '-py-exec')
+    _py_exec = PyExec("-py-exec", gdb.COMMAND_DATA, gdb.COMPLETE_NONE)
+else:
+    warnings.warn("Use gdb 7.2 or higher to use the py-exec command.")