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							372 lines
						
					
					
						
							12 KiB
						
					
					
				# -*- 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()
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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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    try:
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        tb_set_next = _init_ugly_crap()
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    except:
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        pass
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    del _init_ugly_crap
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