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| 1 # -*- coding: utf-8 -*- |
| 2 """ |
| 3 jinja2.debug |
| 4 ~~~~~~~~~~~~ |
| 5 |
| 6 Implements the debug interface for Jinja. This module does some pretty |
| 7 ugly stuff with the Python traceback system in order to achieve tracebacks |
| 8 with correct line numbers, locals and contents. |
| 9 |
| 10 :copyright: (c) 2010 by the Jinja Team. |
| 11 :license: BSD, see LICENSE for more details. |
| 12 """ |
| 13 import sys |
| 14 import traceback |
| 15 from types import TracebackType |
| 16 from jinja2.utils import missing, internal_code |
| 17 from jinja2.exceptions import TemplateSyntaxError |
| 18 from jinja2._compat import iteritems, reraise, code_type |
| 19 |
| 20 # on pypy we can take advantage of transparent proxies |
| 21 try: |
| 22 from __pypy__ import tproxy |
| 23 except ImportError: |
| 24 tproxy = None |
| 25 |
| 26 |
| 27 # how does the raise helper look like? |
| 28 try: |
| 29 exec("raise TypeError, 'foo'") |
| 30 except SyntaxError: |
| 31 raise_helper = 'raise __jinja_exception__[1]' |
| 32 except TypeError: |
| 33 raise_helper = 'raise __jinja_exception__[0], __jinja_exception__[1]' |
| 34 |
| 35 |
| 36 class TracebackFrameProxy(object): |
| 37 """Proxies a traceback frame.""" |
| 38 |
| 39 def __init__(self, tb): |
| 40 self.tb = tb |
| 41 self._tb_next = None |
| 42 |
| 43 @property |
| 44 def tb_next(self): |
| 45 return self._tb_next |
| 46 |
| 47 def set_next(self, next): |
| 48 if tb_set_next is not None: |
| 49 try: |
| 50 tb_set_next(self.tb, next and next.tb or None) |
| 51 except Exception: |
| 52 # this function can fail due to all the hackery it does |
| 53 # on various python implementations. We just catch errors |
| 54 # down and ignore them if necessary. |
| 55 pass |
| 56 self._tb_next = next |
| 57 |
| 58 @property |
| 59 def is_jinja_frame(self): |
| 60 return '__jinja_template__' in self.tb.tb_frame.f_globals |
| 61 |
| 62 def __getattr__(self, name): |
| 63 return getattr(self.tb, name) |
| 64 |
| 65 |
| 66 def make_frame_proxy(frame): |
| 67 proxy = TracebackFrameProxy(frame) |
| 68 if tproxy is None: |
| 69 return proxy |
| 70 def operation_handler(operation, *args, **kwargs): |
| 71 if operation in ('__getattribute__', '__getattr__'): |
| 72 return getattr(proxy, args[0]) |
| 73 elif operation == '__setattr__': |
| 74 proxy.__setattr__(*args, **kwargs) |
| 75 else: |
| 76 return getattr(proxy, operation)(*args, **kwargs) |
| 77 return tproxy(TracebackType, operation_handler) |
| 78 |
| 79 |
| 80 class ProcessedTraceback(object): |
| 81 """Holds a Jinja preprocessed traceback for printing or reraising.""" |
| 82 |
| 83 def __init__(self, exc_type, exc_value, frames): |
| 84 assert frames, 'no frames for this traceback?' |
| 85 self.exc_type = exc_type |
| 86 self.exc_value = exc_value |
| 87 self.frames = frames |
| 88 |
| 89 # newly concatenate the frames (which are proxies) |
| 90 prev_tb = None |
| 91 for tb in self.frames: |
| 92 if prev_tb is not None: |
| 93 prev_tb.set_next(tb) |
| 94 prev_tb = tb |
| 95 prev_tb.set_next(None) |
| 96 |
| 97 def render_as_text(self, limit=None): |
| 98 """Return a string with the traceback.""" |
| 99 lines = traceback.format_exception(self.exc_type, self.exc_value, |
| 100 self.frames[0], limit=limit) |
| 101 return ''.join(lines).rstrip() |
| 102 |
| 103 def render_as_html(self, full=False): |
| 104 """Return a unicode string with the traceback as rendered HTML.""" |
| 105 from jinja2.debugrenderer import render_traceback |
| 106 return u'%s\n\n<!--\n%s\n-->' % ( |
| 107 render_traceback(self, full=full), |
| 108 self.render_as_text().decode('utf-8', 'replace') |
| 109 ) |
| 110 |
| 111 @property |
| 112 def is_template_syntax_error(self): |
| 113 """`True` if this is a template syntax error.""" |
| 114 return isinstance(self.exc_value, TemplateSyntaxError) |
| 115 |
| 116 @property |
| 117 def exc_info(self): |
| 118 """Exception info tuple with a proxy around the frame objects.""" |
| 119 return self.exc_type, self.exc_value, self.frames[0] |
| 120 |
| 121 @property |
| 122 def standard_exc_info(self): |
| 123 """Standard python exc_info for re-raising""" |
| 124 tb = self.frames[0] |
| 125 # the frame will be an actual traceback (or transparent proxy) if |
| 126 # we are on pypy or a python implementation with support for tproxy |
| 127 if type(tb) is not TracebackType: |
| 128 tb = tb.tb |
| 129 return self.exc_type, self.exc_value, tb |
| 130 |
| 131 |
| 132 def make_traceback(exc_info, source_hint=None): |
| 133 """Creates a processed traceback object from the exc_info.""" |
| 134 exc_type, exc_value, tb = exc_info |
| 135 if isinstance(exc_value, TemplateSyntaxError): |
| 136 exc_info = translate_syntax_error(exc_value, source_hint) |
| 137 initial_skip = 0 |
| 138 else: |
| 139 initial_skip = 1 |
| 140 return translate_exception(exc_info, initial_skip) |
| 141 |
| 142 |
| 143 def translate_syntax_error(error, source=None): |
| 144 """Rewrites a syntax error to please traceback systems.""" |
| 145 error.source = source |
| 146 error.translated = True |
| 147 exc_info = (error.__class__, error, None) |
| 148 filename = error.filename |
| 149 if filename is None: |
| 150 filename = '<unknown>' |
| 151 return fake_exc_info(exc_info, filename, error.lineno) |
| 152 |
| 153 |
| 154 def translate_exception(exc_info, initial_skip=0): |
| 155 """If passed an exc_info it will automatically rewrite the exceptions |
| 156 all the way down to the correct line numbers and frames. |
| 157 """ |
| 158 tb = exc_info[2] |
| 159 frames = [] |
| 160 |
| 161 # skip some internal frames if wanted |
| 162 for x in range(initial_skip): |
| 163 if tb is not None: |
| 164 tb = tb.tb_next |
| 165 initial_tb = tb |
| 166 |
| 167 while tb is not None: |
| 168 # skip frames decorated with @internalcode. These are internal |
| 169 # calls we can't avoid and that are useless in template debugging |
| 170 # output. |
| 171 if tb.tb_frame.f_code in internal_code: |
| 172 tb = tb.tb_next |
| 173 continue |
| 174 |
| 175 # save a reference to the next frame if we override the current |
| 176 # one with a faked one. |
| 177 next = tb.tb_next |
| 178 |
| 179 # fake template exceptions |
| 180 template = tb.tb_frame.f_globals.get('__jinja_template__') |
| 181 if template is not None: |
| 182 lineno = template.get_corresponding_lineno(tb.tb_lineno) |
| 183 tb = fake_exc_info(exc_info[:2] + (tb,), template.filename, |
| 184 lineno)[2] |
| 185 |
| 186 frames.append(make_frame_proxy(tb)) |
| 187 tb = next |
| 188 |
| 189 # if we don't have any exceptions in the frames left, we have to |
| 190 # reraise it unchanged. |
| 191 # XXX: can we backup here? when could this happen? |
| 192 if not frames: |
| 193 reraise(exc_info[0], exc_info[1], exc_info[2]) |
| 194 |
| 195 return ProcessedTraceback(exc_info[0], exc_info[1], frames) |
| 196 |
| 197 |
| 198 def fake_exc_info(exc_info, filename, lineno): |
| 199 """Helper for `translate_exception`.""" |
| 200 exc_type, exc_value, tb = exc_info |
| 201 |
| 202 # figure the real context out |
| 203 if tb is not None: |
| 204 real_locals = tb.tb_frame.f_locals.copy() |
| 205 ctx = real_locals.get('context') |
| 206 if ctx: |
| 207 locals = ctx.get_all() |
| 208 else: |
| 209 locals = {} |
| 210 for name, value in iteritems(real_locals): |
| 211 if name.startswith('l_') and value is not missing: |
| 212 locals[name[2:]] = value |
| 213 |
| 214 # if there is a local called __jinja_exception__, we get |
| 215 # rid of it to not break the debug functionality. |
| 216 locals.pop('__jinja_exception__', None) |
| 217 else: |
| 218 locals = {} |
| 219 |
| 220 # assamble fake globals we need |
| 221 globals = { |
| 222 '__name__': filename, |
| 223 '__file__': filename, |
| 224 '__jinja_exception__': exc_info[:2], |
| 225 |
| 226 # we don't want to keep the reference to the template around |
| 227 # to not cause circular dependencies, but we mark it as Jinja |
| 228 # frame for the ProcessedTraceback |
| 229 '__jinja_template__': None |
| 230 } |
| 231 |
| 232 # and fake the exception |
| 233 code = compile('\n' * (lineno - 1) + raise_helper, filename, 'exec') |
| 234 |
| 235 # if it's possible, change the name of the code. This won't work |
| 236 # on some python environments such as google appengine |
| 237 try: |
| 238 if tb is None: |
| 239 location = 'template' |
| 240 else: |
| 241 function = tb.tb_frame.f_code.co_name |
| 242 if function == 'root': |
| 243 location = 'top-level template code' |
| 244 elif function.startswith('block_'): |
| 245 location = 'block "%s"' % function[6:] |
| 246 else: |
| 247 location = 'template' |
| 248 code = code_type(0, code.co_nlocals, code.co_stacksize, |
| 249 code.co_flags, code.co_code, code.co_consts, |
| 250 code.co_names, code.co_varnames, filename, |
| 251 location, code.co_firstlineno, |
| 252 code.co_lnotab, (), ()) |
| 253 except: |
| 254 pass |
| 255 |
| 256 # execute the code and catch the new traceback |
| 257 try: |
| 258 exec(code, globals, locals) |
| 259 except: |
| 260 exc_info = sys.exc_info() |
| 261 new_tb = exc_info[2].tb_next |
| 262 |
| 263 # return without this frame |
| 264 return exc_info[:2] + (new_tb,) |
| 265 |
| 266 |
| 267 def _init_ugly_crap(): |
| 268 """This function implements a few ugly things so that we can patch the |
| 269 traceback objects. The function returned allows resetting `tb_next` on |
| 270 any python traceback object. Do not attempt to use this on non cpython |
| 271 interpreters |
| 272 """ |
| 273 import ctypes |
| 274 from types import TracebackType |
| 275 |
| 276 # figure out side of _Py_ssize_t |
| 277 if hasattr(ctypes.pythonapi, 'Py_InitModule4_64'): |
| 278 _Py_ssize_t = ctypes.c_int64 |
| 279 else: |
| 280 _Py_ssize_t = ctypes.c_int |
| 281 |
| 282 # regular python |
| 283 class _PyObject(ctypes.Structure): |
| 284 pass |
| 285 _PyObject._fields_ = [ |
| 286 ('ob_refcnt', _Py_ssize_t), |
| 287 ('ob_type', ctypes.POINTER(_PyObject)) |
| 288 ] |
| 289 |
| 290 # python with trace |
| 291 if hasattr(sys, 'getobjects'): |
| 292 class _PyObject(ctypes.Structure): |
| 293 pass |
| 294 _PyObject._fields_ = [ |
| 295 ('_ob_next', ctypes.POINTER(_PyObject)), |
| 296 ('_ob_prev', ctypes.POINTER(_PyObject)), |
| 297 ('ob_refcnt', _Py_ssize_t), |
| 298 ('ob_type', ctypes.POINTER(_PyObject)) |
| 299 ] |
| 300 |
| 301 class _Traceback(_PyObject): |
| 302 pass |
| 303 _Traceback._fields_ = [ |
| 304 ('tb_next', ctypes.POINTER(_Traceback)), |
| 305 ('tb_frame', ctypes.POINTER(_PyObject)), |
| 306 ('tb_lasti', ctypes.c_int), |
| 307 ('tb_lineno', ctypes.c_int) |
| 308 ] |
| 309 |
| 310 def tb_set_next(tb, next): |
| 311 """Set the tb_next attribute of a traceback object.""" |
| 312 if not (isinstance(tb, TracebackType) and |
| 313 (next is None or isinstance(next, TracebackType))): |
| 314 raise TypeError('tb_set_next arguments must be traceback objects') |
| 315 obj = _Traceback.from_address(id(tb)) |
| 316 if tb.tb_next is not None: |
| 317 old = _Traceback.from_address(id(tb.tb_next)) |
| 318 old.ob_refcnt -= 1 |
| 319 if next is None: |
| 320 obj.tb_next = ctypes.POINTER(_Traceback)() |
| 321 else: |
| 322 next = _Traceback.from_address(id(next)) |
| 323 next.ob_refcnt += 1 |
| 324 obj.tb_next = ctypes.pointer(next) |
| 325 |
| 326 return tb_set_next |
| 327 |
| 328 |
| 329 # try to get a tb_set_next implementation if we don't have transparent |
| 330 # proxies. |
| 331 tb_set_next = None |
| 332 if tproxy is None: |
| 333 try: |
| 334 tb_set_next = _init_ugly_crap() |
| 335 except: |
| 336 pass |
| 337 del _init_ugly_crap |
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