379 lines
12 KiB
Python
379 lines
12 KiB
Python
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# -*- coding: utf-8 -*-
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"""
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jinja2.debug
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~~~~~~~~~~~~
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Implements the debug interface for Jinja. This module does some pretty
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ugly stuff with the Python traceback system in order to achieve tracebacks
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with correct line numbers, locals and contents.
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:copyright: (c) 2017 by the Jinja Team.
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:license: BSD, see LICENSE for more details.
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"""
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import sys
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import traceback
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from types import TracebackType, CodeType
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from jinja2.utils import missing, internal_code
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from jinja2.exceptions import TemplateSyntaxError
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from jinja2._compat import iteritems, reraise, PY2
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# on pypy we can take advantage of transparent proxies
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try:
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from __pypy__ import tproxy
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except ImportError:
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tproxy = None
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# how does the raise helper look like?
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try:
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exec("raise TypeError, 'foo'")
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except SyntaxError:
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raise_helper = 'raise __jinja_exception__[1]'
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except TypeError:
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raise_helper = 'raise __jinja_exception__[0], __jinja_exception__[1]'
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class TracebackFrameProxy(object):
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"""Proxies a traceback frame."""
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def __init__(self, tb):
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self.tb = tb
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self._tb_next = None
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@property
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def tb_next(self):
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return self._tb_next
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def set_next(self, next):
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if tb_set_next is not None:
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try:
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tb_set_next(self.tb, next and next.tb or None)
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except Exception:
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# this function can fail due to all the hackery it does
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# on various python implementations. We just catch errors
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# down and ignore them if necessary.
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pass
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self._tb_next = next
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@property
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def is_jinja_frame(self):
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return '__jinja_template__' in self.tb.tb_frame.f_globals
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def __getattr__(self, name):
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return getattr(self.tb, name)
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def make_frame_proxy(frame):
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proxy = TracebackFrameProxy(frame)
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if tproxy is None:
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return proxy
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def operation_handler(operation, *args, **kwargs):
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if operation in ('__getattribute__', '__getattr__'):
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return getattr(proxy, args[0])
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elif operation == '__setattr__':
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proxy.__setattr__(*args, **kwargs)
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else:
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return getattr(proxy, operation)(*args, **kwargs)
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return tproxy(TracebackType, operation_handler)
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class ProcessedTraceback(object):
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"""Holds a Jinja preprocessed traceback for printing or reraising."""
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def __init__(self, exc_type, exc_value, frames):
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assert frames, 'no frames for this traceback?'
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self.exc_type = exc_type
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self.exc_value = exc_value
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self.frames = frames
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# newly concatenate the frames (which are proxies)
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prev_tb = None
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for tb in self.frames:
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if prev_tb is not None:
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prev_tb.set_next(tb)
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prev_tb = tb
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prev_tb.set_next(None)
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def render_as_text(self, limit=None):
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"""Return a string with the traceback."""
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lines = traceback.format_exception(self.exc_type, self.exc_value,
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self.frames[0], limit=limit)
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return ''.join(lines).rstrip()
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def render_as_html(self, full=False):
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"""Return a unicode string with the traceback as rendered HTML."""
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from jinja2.debugrenderer import render_traceback
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return u'%s\n\n<!--\n%s\n-->' % (
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render_traceback(self, full=full),
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self.render_as_text().decode('utf-8', 'replace')
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)
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@property
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def is_template_syntax_error(self):
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"""`True` if this is a template syntax error."""
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return isinstance(self.exc_value, TemplateSyntaxError)
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@property
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def exc_info(self):
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"""Exception info tuple with a proxy around the frame objects."""
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return self.exc_type, self.exc_value, self.frames[0]
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@property
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def standard_exc_info(self):
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"""Standard python exc_info for re-raising"""
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tb = self.frames[0]
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# the frame will be an actual traceback (or transparent proxy) if
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# we are on pypy or a python implementation with support for tproxy
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if type(tb) is not TracebackType:
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tb = tb.tb
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return self.exc_type, self.exc_value, tb
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def make_traceback(exc_info, source_hint=None):
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"""Creates a processed traceback object from the exc_info."""
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exc_type, exc_value, tb = exc_info
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if isinstance(exc_value, TemplateSyntaxError):
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exc_info = translate_syntax_error(exc_value, source_hint)
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initial_skip = 0
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else:
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initial_skip = 1
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return translate_exception(exc_info, initial_skip)
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def translate_syntax_error(error, source=None):
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"""Rewrites a syntax error to please traceback systems."""
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error.source = source
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error.translated = True
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exc_info = (error.__class__, error, None)
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filename = error.filename
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if filename is None:
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filename = '<unknown>'
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return fake_exc_info(exc_info, filename, error.lineno)
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def translate_exception(exc_info, initial_skip=0):
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"""If passed an exc_info it will automatically rewrite the exceptions
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all the way down to the correct line numbers and frames.
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"""
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tb = exc_info[2]
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frames = []
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# skip some internal frames if wanted
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for x in range(initial_skip):
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if tb is not None:
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tb = tb.tb_next
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initial_tb = tb
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while tb is not None:
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# skip frames decorated with @internalcode. These are internal
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# calls we can't avoid and that are useless in template debugging
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# output.
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if tb.tb_frame.f_code in internal_code:
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tb = tb.tb_next
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continue
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# save a reference to the next frame if we override the current
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# one with a faked one.
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next = tb.tb_next
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# fake template exceptions
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template = tb.tb_frame.f_globals.get('__jinja_template__')
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if template is not None:
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lineno = template.get_corresponding_lineno(tb.tb_lineno)
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tb = fake_exc_info(exc_info[:2] + (tb,), template.filename,
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lineno)[2]
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frames.append(make_frame_proxy(tb))
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tb = next
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# if we don't have any exceptions in the frames left, we have to
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# reraise it unchanged.
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# XXX: can we backup here? when could this happen?
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if not frames:
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reraise(exc_info[0], exc_info[1], exc_info[2])
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return ProcessedTraceback(exc_info[0], exc_info[1], frames)
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def get_jinja_locals(real_locals):
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ctx = real_locals.get('context')
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if ctx:
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locals = ctx.get_all().copy()
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else:
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locals = {}
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local_overrides = {}
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for name, value in iteritems(real_locals):
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if not name.startswith('l_') or value is missing:
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continue
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try:
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_, depth, name = name.split('_', 2)
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depth = int(depth)
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except ValueError:
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continue
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cur_depth = local_overrides.get(name, (-1,))[0]
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if cur_depth < depth:
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local_overrides[name] = (depth, value)
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for name, (_, value) in iteritems(local_overrides):
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if value is missing:
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locals.pop(name, None)
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else:
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locals[name] = value
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return locals
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def fake_exc_info(exc_info, filename, lineno):
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"""Helper for `translate_exception`."""
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exc_type, exc_value, tb = exc_info
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# figure the real context out
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if tb is not None:
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locals = get_jinja_locals(tb.tb_frame.f_locals)
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# if there is a local called __jinja_exception__, we get
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# rid of it to not break the debug functionality.
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locals.pop('__jinja_exception__', None)
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else:
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locals = {}
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# assamble fake globals we need
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globals = {
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'__name__': filename,
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'__file__': filename,
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'__jinja_exception__': exc_info[:2],
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# we don't want to keep the reference to the template around
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# to not cause circular dependencies, but we mark it as Jinja
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# frame for the ProcessedTraceback
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'__jinja_template__': None
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}
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# and fake the exception
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code = compile('\n' * (lineno - 1) + raise_helper, filename, 'exec')
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# if it's possible, change the name of the code. This won't work
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# on some python environments such as google appengine
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try:
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if tb is None:
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location = 'template'
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else:
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function = tb.tb_frame.f_code.co_name
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if function == 'root':
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location = 'top-level template code'
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elif function.startswith('block_'):
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location = 'block "%s"' % function[6:]
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else:
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location = 'template'
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if PY2:
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code = CodeType(0, code.co_nlocals, code.co_stacksize,
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code.co_flags, code.co_code, code.co_consts,
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code.co_names, code.co_varnames, filename,
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location, code.co_firstlineno,
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code.co_lnotab, (), ())
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else:
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code = CodeType(0, code.co_kwonlyargcount,
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code.co_nlocals, code.co_stacksize,
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code.co_flags, code.co_code, code.co_consts,
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code.co_names, code.co_varnames, filename,
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location, code.co_firstlineno,
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code.co_lnotab, (), ())
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except Exception as e:
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pass
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# execute the code and catch the new traceback
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try:
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exec(code, globals, locals)
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except:
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exc_info = sys.exc_info()
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new_tb = exc_info[2].tb_next
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# return without this frame
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return exc_info[:2] + (new_tb,)
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def _init_ugly_crap():
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"""This function implements a few ugly things so that we can patch the
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traceback objects. The function returned allows resetting `tb_next` on
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any python traceback object. Do not attempt to use this on non cpython
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interpreters
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"""
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import ctypes
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from types import TracebackType
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if PY2:
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# figure out size of _Py_ssize_t for Python 2:
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if hasattr(ctypes.pythonapi, 'Py_InitModule4_64'):
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_Py_ssize_t = ctypes.c_int64
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else:
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_Py_ssize_t = ctypes.c_int
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else:
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# platform ssize_t on Python 3
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_Py_ssize_t = ctypes.c_ssize_t
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# regular python
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class _PyObject(ctypes.Structure):
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pass
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_PyObject._fields_ = [
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('ob_refcnt', _Py_ssize_t),
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('ob_type', ctypes.POINTER(_PyObject))
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]
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# python with trace
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if hasattr(sys, 'getobjects'):
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class _PyObject(ctypes.Structure):
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pass
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_PyObject._fields_ = [
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('_ob_next', ctypes.POINTER(_PyObject)),
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('_ob_prev', ctypes.POINTER(_PyObject)),
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('ob_refcnt', _Py_ssize_t),
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('ob_type', ctypes.POINTER(_PyObject))
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]
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class _Traceback(_PyObject):
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pass
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_Traceback._fields_ = [
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('tb_next', ctypes.POINTER(_Traceback)),
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('tb_frame', ctypes.POINTER(_PyObject)),
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('tb_lasti', ctypes.c_int),
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('tb_lineno', ctypes.c_int)
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]
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def tb_set_next(tb, next):
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"""Set the tb_next attribute of a traceback object."""
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if not (isinstance(tb, TracebackType) and
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(next is None or isinstance(next, TracebackType))):
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raise TypeError('tb_set_next arguments must be traceback objects')
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obj = _Traceback.from_address(id(tb))
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if tb.tb_next is not None:
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old = _Traceback.from_address(id(tb.tb_next))
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old.ob_refcnt -= 1
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if next is None:
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obj.tb_next = ctypes.POINTER(_Traceback)()
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else:
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next = _Traceback.from_address(id(next))
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next.ob_refcnt += 1
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obj.tb_next = ctypes.pointer(next)
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return tb_set_next
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# try to get a tb_set_next implementation if we don't have transparent
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# proxies.
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tb_set_next = None
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if tproxy is None:
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# traceback.tb_next can be modified since CPython 3.7
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if sys.version_info >= (3, 7):
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def tb_set_next(tb, next):
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tb.tb_next = next
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else:
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# On Python 3.6 and older, use ctypes
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try:
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tb_set_next = _init_ugly_crap()
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except Exception:
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pass
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del _init_ugly_crap
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