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Diffstat (limited to 'python/jinja2/debug.py')
| -rw-r--r-- | python/jinja2/debug.py | 372 |
1 files changed, 372 insertions, 0 deletions
diff --git a/python/jinja2/debug.py b/python/jinja2/debug.py new file mode 100644 index 0000000..b61139f --- /dev/null +++ b/python/jinja2/debug.py @@ -0,0 +1,372 @@ +# -*- 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<!--\n%s\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 = '<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 + 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 |