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jimingham
e2e8caf51f
This is a scripted equivalent of the "trampoline handler" that lldb uses to run to the target of a dynamic dispatch stub, or to the target of std::function, or an objc message send.
120 lines
4.0 KiB
Python
120 lines
4.0 KiB
Python
from abc import ABCMeta
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from typing import Optional
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import lldb
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class ScriptedStackFrameRecognizer(metaclass=ABCMeta):
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"""
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The base class for a scripted stack frame recognizer.
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A frame recognizer inspects a stack frame at stop time and can:
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- attach recognized arguments to it (surfaced the same way as args
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for unrecognized frames);
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- hide the frame from backtraces;
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- override the stop description reported for it;
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- expose an exception object associated with it (e.g. a runtime's
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thrown value);
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- redirect auto-selection to a more relevant frame (e.g. bounce past
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a language-runtime trampoline).
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Register the recognizer with `frame recognizer add -l <ClassName> ...`.
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Every method is optional: a recognizer only implements the ones it
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cares about. A recognizer that just hides frames can implement only
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`should_hide`; one that surfaces exception info can implement only
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`get_exception` and `get_stop_description`.
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"""
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def __init__(self):
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"""Construct a scripted stack frame recognizer.
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Recognizers are constructed with no arguments and are shared across
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every frame they're asked to recognize.
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"""
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pass
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def get_recognized_arguments(self, frame: lldb.SBFrame) -> list:
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"""Get the arguments recognized for this frame.
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Args:
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frame (lldb.SBFrame): The frame to inspect.
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Returns:
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list of lldb.SBValue: The recognized arguments, or an empty list
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if none could be recognized.
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"""
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return []
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def should_hide(self, frame: lldb.SBFrame) -> bool:
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"""Whether this frame should be hidden when displaying backtraces.
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Args:
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frame (lldb.SBFrame): The frame to inspect.
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Returns:
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bool: `True` if this frame should be hidden, `False` otherwise.
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Defaults to `False`.
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"""
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return False
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def select_most_relevant_frame(self, frame: lldb.SBFrame) -> Optional[lldb.SBFrame]:
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"""Pick a different frame to auto-select when the process stops in
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this recognized frame. Useful when the recognized frame is trampoline
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code that the user probably didn't want to land in (e.g. a language
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runtime's exception-throw path).
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Args:
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frame (lldb.SBFrame): The recognized frame.
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Returns:
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lldb.SBFrame: The frame to select instead, or `None` to keep
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the default selection.
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"""
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return None
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def get_exception(self, frame: lldb.SBFrame) -> Optional[lldb.SBValue]:
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"""Get the exception value associated with this recognized frame,
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if any (e.g. the exception object at a language runtime's throw
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site).
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Args:
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frame (lldb.SBFrame): The recognized frame.
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Returns:
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lldb.SBValue: The exception value, or `None` if this frame
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doesn't correspond to an exception.
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"""
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return None
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def get_stop_description(self, frame: lldb.SBFrame) -> str:
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"""Get the stop description to surface for this recognized frame,
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replacing whatever description lldb would have printed.
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Args:
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frame (lldb.SBFrame): The recognized frame.
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Returns:
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str: The stop description, or the empty string to keep the
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default.
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"""
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return ""
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def get_step_through_plan(self, thread):
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"""Provide a 'step through' plan from the stopped frame.
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Args:
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thread (lldb.SBThread): passed in is the one to step. You
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will only be asked to step through from the zeroth frame of that
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thread.
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Returns:
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Python dictionary with two keys:
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class_name : name of a class implementing a ScriptedThreadPlan.
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extra_args : a dictionary that will be passed to the
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__init__ of your scripted thread plan. The extra_args is optional.
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"""
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return None
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