280 lines
9.0 KiB
Python
280 lines
9.0 KiB
Python
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import platform
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import sys
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import typing as t
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from types import CodeType
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from types import TracebackType
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from .exceptions import TemplateSyntaxError
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from .utils import internal_code
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from .utils import missing
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if t.TYPE_CHECKING:
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from .runtime import Context
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def rewrite_traceback_stack(source: t.Optional[str] = None) -> BaseException:
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"""Rewrite the current exception to replace any tracebacks from
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within compiled template code with tracebacks that look like they
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came from the template source.
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This must be called within an ``except`` block.
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:param source: For ``TemplateSyntaxError``, the original source if
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known.
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:return: The original exception with the rewritten traceback.
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"""
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_, exc_value, tb = sys.exc_info()
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exc_value = t.cast(BaseException, exc_value)
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tb = t.cast(TracebackType, tb)
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if isinstance(exc_value, TemplateSyntaxError) and not exc_value.translated:
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exc_value.translated = True
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exc_value.source = source
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# Remove the old traceback, otherwise the frames from the
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# compiler still show up.
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exc_value.with_traceback(None)
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# Outside of runtime, so the frame isn't executing template
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# code, but it still needs to point at the template.
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tb = fake_traceback(
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exc_value, None, exc_value.filename or "<unknown>", exc_value.lineno
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)
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else:
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# Skip the frame for the render function.
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tb = tb.tb_next
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stack = []
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# Build the stack of traceback object, replacing any in template
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# code with the source file and line information.
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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 that aren't useful in template debugging 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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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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fake_tb = fake_traceback(exc_value, tb, template.filename, lineno)
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stack.append(fake_tb)
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else:
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stack.append(tb)
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tb = tb.tb_next
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tb_next = None
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# Assign tb_next in reverse to avoid circular references.
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for tb in reversed(stack):
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tb_next = tb_set_next(tb, tb_next)
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return exc_value.with_traceback(tb_next)
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def fake_traceback( # type: ignore
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exc_value: BaseException, tb: t.Optional[TracebackType], filename: str, lineno: int
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) -> TracebackType:
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"""Produce a new traceback object that looks like it came from the
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template source instead of the compiled code. The filename, line
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number, and location name will point to the template, and the local
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variables will be the current template context.
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:param exc_value: The original exception to be re-raised to create
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the new traceback.
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:param tb: The original traceback to get the local variables and
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code info from.
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:param filename: The template filename.
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:param lineno: The line number in the template source.
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"""
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if tb is not None:
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# Replace the real locals with the context that would be
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# available at that point in the template.
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locals = get_template_locals(tb.tb_frame.f_locals)
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locals.pop("__jinja_exception__", None)
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else:
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locals = {}
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globals = {
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"__name__": filename,
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"__file__": filename,
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"__jinja_exception__": exc_value,
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}
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# Raise an exception at the correct line number.
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code = compile("\n" * (lineno - 1) + "raise __jinja_exception__", filename, "exec")
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# Build a new code object that points to the template file and
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# replaces the location with a block name.
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try:
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location = "template"
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if tb is not None:
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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 = f"block {function[6:]!r}"
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# Collect arguments for the new code object. CodeType only
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# accepts positional arguments, and arguments were inserted in
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# new Python versions.
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code_args = []
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for attr in (
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"argcount",
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"posonlyargcount", # Python 3.8
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"kwonlyargcount",
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"nlocals",
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"stacksize",
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"flags",
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"code", # codestring
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"consts", # constants
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"names",
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"varnames",
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("filename", filename),
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("name", location),
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"firstlineno",
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"lnotab",
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"freevars",
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"cellvars",
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"linetable", # Python 3.10
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):
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if isinstance(attr, tuple):
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# Replace with given value.
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code_args.append(attr[1])
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continue
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try:
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# Copy original value if it exists.
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code_args.append(getattr(code, "co_" + t.cast(str, attr)))
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except AttributeError:
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# Some arguments were added later.
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continue
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code = CodeType(*code_args)
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except Exception:
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# Some environments such as Google App Engine don't support
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# modifying code objects.
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pass
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# Execute the new code, which is guaranteed to raise, and return
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# the new traceback without this frame.
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try:
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exec(code, globals, locals)
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except BaseException:
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return sys.exc_info()[2].tb_next # type: ignore
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def get_template_locals(real_locals: t.Mapping[str, t.Any]) -> t.Dict[str, t.Any]:
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"""Based on the runtime locals, get the context that would be
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available at that point in the template.
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"""
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# Start with the current template context.
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ctx: "t.Optional[Context]" = real_locals.get("context")
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if ctx is not None:
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data: t.Dict[str, t.Any] = ctx.get_all().copy()
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else:
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data = {}
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# Might be in a derived context that only sets local variables
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# rather than pushing a context. Local variables follow the scheme
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# l_depth_name. Find the highest-depth local that has a value for
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# each name.
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local_overrides: t.Dict[str, t.Tuple[int, t.Any]] = {}
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for name, value in real_locals.items():
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if not name.startswith("l_") or value is missing:
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# Not a template variable, or no longer relevant.
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continue
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try:
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_, depth_str, name = name.split("_", 2)
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depth = int(depth_str)
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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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# Modify the context with any derived context.
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for name, (_, value) in local_overrides.items():
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if value is missing:
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data.pop(name, None)
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else:
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data[name] = value
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return data
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if sys.version_info >= (3, 7):
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# tb_next is directly assignable as of Python 3.7
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def tb_set_next(
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tb: TracebackType, tb_next: t.Optional[TracebackType]
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) -> TracebackType:
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tb.tb_next = tb_next
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return tb
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elif platform.python_implementation() == "PyPy":
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# PyPy might have special support, and won't work with ctypes.
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try:
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import tputil # type: ignore
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except ImportError:
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# Without tproxy support, use the original traceback.
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def tb_set_next(
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tb: TracebackType, tb_next: t.Optional[TracebackType]
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) -> TracebackType:
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return tb
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else:
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# With tproxy support, create a proxy around the traceback that
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# returns the new tb_next.
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def tb_set_next(
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tb: TracebackType, tb_next: t.Optional[TracebackType]
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) -> TracebackType:
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def controller(op): # type: ignore
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if op.opname == "__getattribute__" and op.args[0] == "tb_next":
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return tb_next
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return op.delegate()
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return tputil.make_proxy(controller, obj=tb) # type: ignore
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else:
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# Use ctypes to assign tb_next at the C level since it's read-only
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# from Python.
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import ctypes
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class _CTraceback(ctypes.Structure):
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_fields_ = [
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# Extra PyObject slots when compiled with Py_TRACE_REFS.
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("PyObject_HEAD", ctypes.c_byte * object().__sizeof__()),
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# Only care about tb_next as an object, not a traceback.
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("tb_next", ctypes.py_object),
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]
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def tb_set_next(
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tb: TracebackType, tb_next: t.Optional[TracebackType]
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) -> TracebackType:
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c_tb = _CTraceback.from_address(id(tb))
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# Clear out the old tb_next.
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if tb.tb_next is not None:
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c_tb_next = ctypes.py_object(tb.tb_next)
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c_tb.tb_next = ctypes.py_object()
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ctypes.pythonapi.Py_DecRef(c_tb_next)
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# Assign the new tb_next.
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if tb_next is not None:
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c_tb_next = ctypes.py_object(tb_next)
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ctypes.pythonapi.Py_IncRef(c_tb_next)
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c_tb.tb_next = c_tb_next
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return tb
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