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- import platform
- import sys
- import typing as t
- from types import CodeType
- from types import TracebackType
- from .exceptions import TemplateSyntaxError
- from .utils import internal_code
- from .utils import missing
- if t.TYPE_CHECKING:
- from .runtime import Context
- def rewrite_traceback_stack(source: t.Optional[str] = None) -> BaseException:
- """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()
- exc_value = t.cast(BaseException, exc_value)
- tb = t.cast(TracebackType, tb)
- 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( # type: ignore
- exc_value: BaseException, tb: t.Optional[TracebackType], filename: str, lineno: int
- ) -> TracebackType:
- """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: CodeType = 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.
- 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}"
- if sys.version_info >= (3, 8):
- code = code.replace(co_name=location)
- else:
- code = CodeType(
- code.co_argcount,
- code.co_kwonlyargcount,
- code.co_nlocals,
- code.co_stacksize,
- code.co_flags,
- code.co_code,
- code.co_consts,
- code.co_names,
- code.co_varnames,
- code.co_filename,
- location,
- code.co_firstlineno,
- code.co_lnotab,
- code.co_freevars,
- code.co_cellvars,
- )
- # 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 # type: ignore
- def get_template_locals(real_locals: t.Mapping[str, t.Any]) -> t.Dict[str, t.Any]:
- """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: "t.Optional[Context]" = real_locals.get("context")
- if ctx is not None:
- data: t.Dict[str, t.Any] = 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: t.Dict[str, t.Tuple[int, t.Any]] = {}
- 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_str, name = name.split("_", 2)
- depth = int(depth_str)
- 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: TracebackType, tb_next: t.Optional[TracebackType]
- ) -> TracebackType:
- 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 # type: ignore
- except ImportError:
- # Without tproxy support, use the original traceback.
- def tb_set_next(
- tb: TracebackType, tb_next: t.Optional[TracebackType]
- ) -> TracebackType:
- return tb
- else:
- # With tproxy support, create a proxy around the traceback that
- # returns the new tb_next.
- def tb_set_next(
- tb: TracebackType, tb_next: t.Optional[TracebackType]
- ) -> TracebackType:
- def controller(op): # type: ignore
- if op.opname == "__getattribute__" and op.args[0] == "tb_next":
- return tb_next
- return op.delegate()
- return tputil.make_proxy(controller, obj=tb) # type: ignore
- 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: TracebackType, tb_next: t.Optional[TracebackType]
- ) -> TracebackType:
- 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
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