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 338
