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Diffstat (limited to 'src/jinja2/debug.py')
| -rw-r--r-- | src/jinja2/debug.py | 261 |
1 files changed, 261 insertions, 0 deletions
diff --git a/src/jinja2/debug.py b/src/jinja2/debug.py new file mode 100644 index 00000000..5cac28ba --- /dev/null +++ b/src/jinja2/debug.py @@ -0,0 +1,261 @@ +import platform +import sys +from types import CodeType + +from . import TemplateSyntaxError +from .utils import internal_code +from .utils import missing + + +def rewrite_traceback_stack(source=None): + """Rewrite the current exception to replace any tracebacks from + within compiled template code with tracebacks that look like they + came from the template source. + + This must be called within an ``except`` block. + + :param source: For ``TemplateSyntaxError``, the original source if + known. + :return: The original exception with the rewritten traceback. + """ + _, exc_value, tb = sys.exc_info() + + if isinstance(exc_value, TemplateSyntaxError) and not exc_value.translated: + exc_value.translated = True + exc_value.source = source + # Remove the old traceback, otherwise the frames from the + # compiler still show up. + exc_value.with_traceback(None) + # Outside of runtime, so the frame isn't executing template + # code, but it still needs to point at the template. + tb = fake_traceback( + exc_value, None, exc_value.filename or "<unknown>", exc_value.lineno + ) + else: + # Skip the frame for the render function. + tb = tb.tb_next + + stack = [] + + # Build the stack of traceback object, replacing any in template + # code with the source file and line information. + while tb is not None: + # Skip frames decorated with @internalcode. These are internal + # calls that aren't useful in template debugging output. + if tb.tb_frame.f_code in internal_code: + tb = tb.tb_next + continue + + template = tb.tb_frame.f_globals.get("__jinja_template__") + + if template is not None: + lineno = template.get_corresponding_lineno(tb.tb_lineno) + fake_tb = fake_traceback(exc_value, tb, template.filename, lineno) + stack.append(fake_tb) + else: + stack.append(tb) + + tb = tb.tb_next + + tb_next = None + + # Assign tb_next in reverse to avoid circular references. + for tb in reversed(stack): + tb_next = tb_set_next(tb, tb_next) + + return exc_value.with_traceback(tb_next) + + +def fake_traceback(exc_value, tb, filename, lineno): + """Produce a new traceback object that looks like it came from the + template source instead of the compiled code. The filename, line + number, and location name will point to the template, and the local + variables will be the current template context. + + :param exc_value: The original exception to be re-raised to create + the new traceback. + :param tb: The original traceback to get the local variables and + code info from. + :param filename: The template filename. + :param lineno: The line number in the template source. + """ + if tb is not None: + # Replace the real locals with the context that would be + # available at that point in the template. + locals = get_template_locals(tb.tb_frame.f_locals) + locals.pop("__jinja_exception__", None) + else: + locals = {} + + globals = { + "__name__": filename, + "__file__": filename, + "__jinja_exception__": exc_value, + } + # Raise an exception at the correct line number. + code = compile("\n" * (lineno - 1) + "raise __jinja_exception__", filename, "exec") + + # Build a new code object that points to the template file and + # replaces the location with a block name. + try: + location = "template" + + if tb is not None: + function = tb.tb_frame.f_code.co_name + + if function == "root": + location = "top-level template code" + elif function.startswith("block_"): + location = f"block {function[6:]!r}" + + # Collect arguments for the new code object. CodeType only + # accepts positional arguments, and arguments were inserted in + # new Python versions. + code_args = [] + + for attr in ( + "argcount", + "posonlyargcount", # Python 3.8 + "kwonlyargcount", + "nlocals", + "stacksize", + "flags", + "code", # codestring + "consts", # constants + "names", + "varnames", + ("filename", filename), + ("name", location), + "firstlineno", + "lnotab", + "freevars", + "cellvars", + ): + if isinstance(attr, tuple): + # Replace with given value. + code_args.append(attr[1]) + continue + + try: + # Copy original value if it exists. + code_args.append(getattr(code, "co_" + attr)) + except AttributeError: + # Some arguments were added later. + continue + + code = CodeType(*code_args) + except Exception: + # Some environments such as Google App Engine don't support + # modifying code objects. + pass + + # Execute the new code, which is guaranteed to raise, and return + # the new traceback without this frame. + try: + exec(code, globals, locals) + except BaseException: + return sys.exc_info()[2].tb_next + + +def get_template_locals(real_locals): + """Based on the runtime locals, get the context that would be + available at that point in the template. + """ + # Start with the current template context. + ctx = real_locals.get("context") + + if ctx: + data = ctx.get_all().copy() + else: + data = {} + + # Might be in a derived context that only sets local variables + # rather than pushing a context. Local variables follow the scheme + # l_depth_name. Find the highest-depth local that has a value for + # each name. + local_overrides = {} + + for name, value in real_locals.items(): + if not name.startswith("l_") or value is missing: + # Not a template variable, or no longer relevant. + 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) + + # Modify the context with any derived context. + for name, (_, value) in local_overrides.items(): + if value is missing: + data.pop(name, None) + else: + data[name] = value + + return data + + +if sys.version_info >= (3, 7): + # tb_next is directly assignable as of Python 3.7 + def tb_set_next(tb, tb_next): + tb.tb_next = tb_next + return tb + + +elif platform.python_implementation() == "PyPy": + # PyPy might have special support, and won't work with ctypes. + try: + import tputil + except ImportError: + # Without tproxy support, use the original traceback. + def tb_set_next(tb, tb_next): + return tb + + else: + # With tproxy support, create a proxy around the traceback that + # returns the new tb_next. + def tb_set_next(tb, tb_next): + def controller(op): + if op.opname == "__getattribute__" and op.args[0] == "tb_next": + return tb_next + + return op.delegate() + + return tputil.make_proxy(controller, obj=tb) + + +else: + # Use ctypes to assign tb_next at the C level since it's read-only + # from Python. + import ctypes + + class _CTraceback(ctypes.Structure): + _fields_ = [ + # Extra PyObject slots when compiled with Py_TRACE_REFS. + ("PyObject_HEAD", ctypes.c_byte * object().__sizeof__()), + # Only care about tb_next as an object, not a traceback. + ("tb_next", ctypes.py_object), + ] + + def tb_set_next(tb, tb_next): + c_tb = _CTraceback.from_address(id(tb)) + + # Clear out the old tb_next. + if tb.tb_next is not None: + c_tb_next = ctypes.py_object(tb.tb_next) + c_tb.tb_next = ctypes.py_object() + ctypes.pythonapi.Py_DecRef(c_tb_next) + + # Assign the new tb_next. + if tb_next is not None: + c_tb_next = ctypes.py_object(tb_next) + ctypes.pythonapi.Py_IncRef(c_tb_next) + c_tb.tb_next = c_tb_next + + return tb |