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# -*- coding: utf-8 -*-
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
from __pypy__ import tproxy
except ImportError:
tproxy = None
# how does the raise helper look like?
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
def tb_next(self):
return self._tb_next
def set_next(self, next):
if tb_set_next is not None:
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.
self._tb_next = next
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)
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 = tb
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<!--\n%s\n-->' % (
render_traceback(self, full=full),
self.render_as_text().decode('utf-8', 'replace')
def is_template_syntax_error(self):
"""`True` if this is a template syntax error."""
return isinstance(self.exc_value, TemplateSyntaxError)
def exc_info(self):
"""Exception info tuple with a proxy around the frame objects."""
return self.exc_type, self.exc_value, self.frames[0]
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
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 = '<unknown>'
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
# 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,
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()
locals = {}
local_overrides = {}
for name, value in iteritems(real_locals):
if not name.startswith('l_') or value is missing:
_, depth, name = name.split('_', 2)
depth = int(depth)
except ValueError:
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)
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)
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
if tb is None:
location = 'template'
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:]
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, (), ())
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:
# execute the code and catch the new traceback
exec(code, globals, locals)
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
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
_Py_ssize_t = ctypes.c_int
# platform ssize_t on Python 3
_Py_ssize_t = ctypes.c_ssize_t
# regular python
class _PyObject(ctypes.Structure):
_PyObject._fields_ = [
('ob_refcnt', _Py_ssize_t),
('ob_type', ctypes.POINTER(_PyObject))
# python with trace
if hasattr(sys, 'getobjects'):
class _PyObject(ctypes.Structure):
_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):
_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)()
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:
tb_set_next = _init_ugly_crap()
del _init_ugly_crap