# -*- coding: utf-8 -*- """ jinja2.debug ~~~~~~~~~~~~ Implements the debug interface for Jinja. This module does some pretty ugly stuff with the Python traceback system in order to achieve tracebacks with correct line numbers, locals and contents. :copyright: (c) 2017 by the Jinja Team. :license: BSD, see LICENSE for more details. """ import sys import traceback from types import TracebackType, CodeType from jinja2.utils import missing, internal_code from jinja2.exceptions import TemplateSyntaxError from jinja2._compat import iteritems, reraise, PY2 # on pypy we can take advantage of transparent proxies try: from __pypy__ import tproxy except ImportError: tproxy = None # how does the raise helper look like? try: exec("raise TypeError, 'foo'") except SyntaxError: raise_helper = 'raise __jinja_exception__[1]' except TypeError: raise_helper = 'raise __jinja_exception__[0], __jinja_exception__[1]' class TracebackFrameProxy(object): """Proxies a traceback frame.""" def __init__(self, tb): self.tb = tb self._tb_next = None @property def tb_next(self): return self._tb_next def set_next(self, next): if tb_set_next is not None: try: tb_set_next(self.tb, next and next.tb or None) except Exception: # this function can fail due to all the hackery it does # on various python implementations. We just catch errors # down and ignore them if necessary. pass self._tb_next = next @property def is_jinja_frame(self): return '__jinja_template__' in self.tb.tb_frame.f_globals def __getattr__(self, name): return getattr(self.tb, name) def make_frame_proxy(frame): proxy = TracebackFrameProxy(frame) if tproxy is None: return proxy def operation_handler(operation, *args, **kwargs): if operation in ('__getattribute__', '__getattr__'): return getattr(proxy, args[0]) elif operation == '__setattr__': proxy.__setattr__(*args, **kwargs) else: return getattr(proxy, operation)(*args, **kwargs) return tproxy(TracebackType, operation_handler) class ProcessedTraceback(object): """Holds a Jinja preprocessed traceback for printing or reraising.""" def __init__(self, exc_type, exc_value, frames): assert frames, 'no frames for this traceback?' self.exc_type = exc_type self.exc_value = exc_value self.frames = frames # newly concatenate the frames (which are proxies) prev_tb = None for tb in self.frames: if prev_tb is not None: prev_tb.set_next(tb) prev_tb = tb prev_tb.set_next(None) def render_as_text(self, limit=None): """Return a string with the traceback.""" lines = traceback.format_exception(self.exc_type, self.exc_value, self.frames[0], limit=limit) return ''.join(lines).rstrip() def render_as_html(self, full=False): """Return a unicode string with the traceback as rendered HTML.""" from jinja2.debugrenderer import render_traceback return u'%s\n\n' % ( render_traceback(self, full=full), self.render_as_text().decode('utf-8', 'replace') ) @property def is_template_syntax_error(self): """`True` if this is a template syntax error.""" return isinstance(self.exc_value, TemplateSyntaxError) @property def exc_info(self): """Exception info tuple with a proxy around the frame objects.""" return self.exc_type, self.exc_value, self.frames[0] @property def standard_exc_info(self): """Standard python exc_info for re-raising""" tb = self.frames[0] # the frame will be an actual traceback (or transparent proxy) if # we are on pypy or a python implementation with support for tproxy if type(tb) is not TracebackType: tb = tb.tb return self.exc_type, self.exc_value, tb def make_traceback(exc_info, source_hint=None): """Creates a processed traceback object from the exc_info.""" exc_type, exc_value, tb = exc_info if isinstance(exc_value, TemplateSyntaxError): exc_info = translate_syntax_error(exc_value, source_hint) initial_skip = 0 else: initial_skip = 1 return translate_exception(exc_info, initial_skip) def translate_syntax_error(error, source=None): """Rewrites a syntax error to please traceback systems.""" error.source = source error.translated = True exc_info = (error.__class__, error, None) filename = error.filename if filename is None: filename = '' return fake_exc_info(exc_info, filename, error.lineno) def translate_exception(exc_info, initial_skip=0): """If passed an exc_info it will automatically rewrite the exceptions all the way down to the correct line numbers and frames. """ tb = exc_info[2] frames = [] # skip some internal frames if wanted for x in range(initial_skip): if tb is not None: tb = tb.tb_next initial_tb = tb while tb is not None: # skip frames decorated with @internalcode. These are internal # calls we can't avoid and that are useless in template debugging # output. if tb.tb_frame.f_code in internal_code: tb = tb.tb_next continue # save a reference to the next frame if we override the current # one with a faked one. next = tb.tb_next # fake template exceptions template = tb.tb_frame.f_globals.get('__jinja_template__') if template is not None: lineno = template.get_corresponding_lineno(tb.tb_lineno) tb = fake_exc_info(exc_info[:2] + (tb,), template.filename, lineno)[2] frames.append(make_frame_proxy(tb)) tb = next # if we don't have any exceptions in the frames left, we have to # reraise it unchanged. # XXX: can we backup here? when could this happen? if not frames: reraise(exc_info[0], exc_info[1], exc_info[2]) return ProcessedTraceback(exc_info[0], exc_info[1], frames) def get_jinja_locals(real_locals): ctx = real_locals.get('context') if ctx: locals = ctx.get_all().copy() else: locals = {} local_overrides = {} for name, value in iteritems(real_locals): if not name.startswith('l_') or value is missing: continue try: _, depth, name = name.split('_', 2) depth = int(depth) except ValueError: continue cur_depth = local_overrides.get(name, (-1,))[0] if cur_depth < depth: local_overrides[name] = (depth, value) for name, (_, value) in iteritems(local_overrides): if value is missing: locals.pop(name, None) else: locals[name] = value return locals def fake_exc_info(exc_info, filename, lineno): """Helper for `translate_exception`.""" exc_type, exc_value, tb = exc_info # figure the real context out if tb is not None: locals = get_jinja_locals(tb.tb_frame.f_locals) # if there is a local called __jinja_exception__, we get # rid of it to not break the debug functionality. locals.pop('__jinja_exception__', None) else: locals = {} # assamble fake globals we need globals = { '__name__': filename, '__file__': filename, '__jinja_exception__': exc_info[:2], # we don't want to keep the reference to the template around # to not cause circular dependencies, but we mark it as Jinja # frame for the ProcessedTraceback '__jinja_template__': None } # and fake the exception code = compile('\n' * (lineno - 1) + raise_helper, filename, 'exec') # if it's possible, change the name of the code. This won't work # on some python environments such as google appengine try: if tb is None: location = 'template' else: function = tb.tb_frame.f_code.co_name if function == 'root': location = 'top-level template code' elif function.startswith('block_'): location = 'block "%s"' % function[6:] else: location = 'template' if PY2: code = CodeType(0, code.co_nlocals, code.co_stacksize, code.co_flags, code.co_code, code.co_consts, code.co_names, code.co_varnames, filename, location, code.co_firstlineno, code.co_lnotab, (), ()) else: code = CodeType(0, code.co_kwonlyargcount, code.co_nlocals, code.co_stacksize, code.co_flags, code.co_code, code.co_consts, code.co_names, code.co_varnames, filename, location, code.co_firstlineno, code.co_lnotab, (), ()) except Exception as e: pass # execute the code and catch the new traceback try: exec(code, globals, locals) except: exc_info = sys.exc_info() new_tb = exc_info[2].tb_next # return without this frame return exc_info[:2] + (new_tb,) def _init_ugly_crap(): """This function implements a few ugly things so that we can patch the traceback objects. The function returned allows resetting `tb_next` on any python traceback object. Do not attempt to use this on non cpython interpreters """ import ctypes from types import TracebackType if PY2: # figure out size of _Py_ssize_t for Python 2: if hasattr(ctypes.pythonapi, 'Py_InitModule4_64'): _Py_ssize_t = ctypes.c_int64 else: _Py_ssize_t = ctypes.c_int else: # platform ssize_t on Python 3 _Py_ssize_t = ctypes.c_ssize_t # regular python class _PyObject(ctypes.Structure): pass _PyObject._fields_ = [ ('ob_refcnt', _Py_ssize_t), ('ob_type', ctypes.POINTER(_PyObject)) ] # python with trace if hasattr(sys, 'getobjects'): class _PyObject(ctypes.Structure): pass _PyObject._fields_ = [ ('_ob_next', ctypes.POINTER(_PyObject)), ('_ob_prev', ctypes.POINTER(_PyObject)), ('ob_refcnt', _Py_ssize_t), ('ob_type', ctypes.POINTER(_PyObject)) ] class _Traceback(_PyObject): pass _Traceback._fields_ = [ ('tb_next', ctypes.POINTER(_Traceback)), ('tb_frame', ctypes.POINTER(_PyObject)), ('tb_lasti', ctypes.c_int), ('tb_lineno', ctypes.c_int) ] def tb_set_next(tb, next): """Set the tb_next attribute of a traceback object.""" if not (isinstance(tb, TracebackType) and (next is None or isinstance(next, TracebackType))): raise TypeError('tb_set_next arguments must be traceback objects') obj = _Traceback.from_address(id(tb)) if tb.tb_next is not None: old = _Traceback.from_address(id(tb.tb_next)) old.ob_refcnt -= 1 if next is None: obj.tb_next = ctypes.POINTER(_Traceback)() else: next = _Traceback.from_address(id(next)) next.ob_refcnt += 1 obj.tb_next = ctypes.pointer(next) return tb_set_next # try to get a tb_set_next implementation if we don't have transparent # proxies. tb_set_next = None if tproxy is None: try: tb_set_next = _init_ugly_crap() except: pass del _init_ugly_crap