Current File : //usr/share/gdb/python/gdb/FrameDecorator.py
# Copyright (C) 2013-2024 Free Software Foundation, Inc.
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
import gdb
class _FrameDecoratorBase(object):
"""Base class of frame decorators."""
# 'base' can refer to a gdb.Frame or another frame decorator. In
# the latter case, the child class will have called the super
# method and _base will be an object conforming to the Frame Filter
# class.
def __init__(self, base):
self._base = base
@staticmethod
def __is_limited_frame(frame):
"""Internal utility to determine if the frame is special or
limited."""
sal = frame.find_sal()
if (
not sal.symtab
or not sal.symtab.filename
or frame.type() == gdb.DUMMY_FRAME
or frame.type() == gdb.SIGTRAMP_FRAME
):
return True
return False
def elided(self):
"""Return any elided frames that this class might be
wrapping, or None."""
if hasattr(self._base, "elided"):
return self._base.elided()
return None
def function(self):
"""Return the name of the frame's function or an address of
the function of the frame. First determine if this is a
special frame. If not, try to determine filename from GDB's
frame internal function API. Finally, if a name cannot be
determined return the address. If this function returns an
address, GDB will attempt to determine the function name from
its internal minimal symbols store (for example, for inferiors
without debug-info)."""
# Both gdb.Frame, and FrameDecorator have a method called
# "function", so determine which object this is.
if not isinstance(self._base, gdb.Frame):
if hasattr(self._base, "function"):
# If it is not a gdb.Frame, and there is already a
# "function" method, use that.
return self._base.function()
frame = self.inferior_frame()
if frame.type() == gdb.DUMMY_FRAME:
return "<function called from gdb>"
elif frame.type() == gdb.SIGTRAMP_FRAME:
return "<signal handler called>"
func = frame.name()
if not isinstance(func, str):
func = "???"
return func
def address(self):
"""Return the address of the frame's pc"""
if hasattr(self._base, "address"):
return self._base.address()
frame = self.inferior_frame()
return frame.pc()
def frame_args(self):
"""Return an iterable of frame arguments for this frame, if
any. The iterable object contains objects conforming with the
Symbol/Value interface. If there are no frame arguments, or
if this frame is deemed to be a special case, return None."""
if hasattr(self._base, "frame_args"):
return self._base.frame_args()
frame = self.inferior_frame()
if self.__is_limited_frame(frame):
return None
args = FrameVars(frame)
return args.fetch_frame_args()
def frame_locals(self):
"""Return an iterable of local variables for this frame, if
any. The iterable object contains objects conforming with the
Symbol/Value interface. If there are no frame locals, or if
this frame is deemed to be a special case, return None."""
if hasattr(self._base, "frame_locals"):
return self._base.frame_locals()
frame = self.inferior_frame()
if self.__is_limited_frame(frame):
return None
args = FrameVars(frame)
return args.fetch_frame_locals()
def line(self):
"""Return line number information associated with the frame's
pc. If symbol table/line information does not exist, or if
this frame is deemed to be a special case, return None"""
if hasattr(self._base, "line"):
return self._base.line()
frame = self.inferior_frame()
if self.__is_limited_frame(frame):
return None
sal = frame.find_sal()
if sal:
return sal.line
else:
return None
def inferior_frame(self):
"""Return the gdb.Frame underpinning this frame decorator."""
# If 'base' is a frame decorator, we want to call its inferior
# frame method. If '_base' is a gdb.Frame, just return that.
if hasattr(self._base, "inferior_frame"):
return self._base.inferior_frame()
return self._base
class FrameDecorator(_FrameDecoratorBase):
"""Basic implementation of a Frame Decorator
This base frame decorator decorates a frame or another frame
decorator, and provides convenience methods. If this object is
wrapping a frame decorator, defer to that wrapped object's method
if it has one. This allows for frame decorators that have
sub-classed FrameDecorator object, but also wrap other frame
decorators on the same frame to correctly execute.
E.g
If the result of frame filters running means we have one gdb.Frame
wrapped by multiple frame decorators, all sub-classed from
FrameDecorator, the resulting hierarchy will be:
Decorator1
-- (wraps) Decorator2
-- (wraps) FrameDecorator
-- (wraps) gdb.Frame
In this case we have two frame decorators, both of which are
sub-classed from FrameDecorator. If Decorator1 just overrides the
'function' method, then all of the other methods are carried out
by the super-class FrameDecorator. But Decorator2 may have
overriden other methods, so FrameDecorator will look at the
'base' parameter and defer to that class's methods. And so on,
down the chain."""
def filename(self):
"""Return the filename associated with this frame, detecting
and returning the appropriate library name is this is a shared
library."""
if hasattr(self._base, "filename"):
return self._base.filename()
frame = self.inferior_frame()
sal = frame.find_sal()
if not sal.symtab or not sal.symtab.filename:
pc = frame.pc()
return gdb.solib_name(pc)
else:
return sal.symtab.filename
class DAPFrameDecorator(_FrameDecoratorBase):
"""Like FrameDecorator, but has slightly different results
for the "filename" method."""
def filename(self):
"""Return the filename associated with this frame, detecting
and returning the appropriate library name is this is a shared
library."""
if hasattr(self._base, "filename"):
return self._base.filename()
frame = self.inferior_frame()
sal = frame.find_sal()
if sal.symtab is not None:
return sal.symtab.fullname()
return None
def frame_locals(self):
"""Return an iterable of local variables for this frame, if
any. The iterable object contains objects conforming with the
Symbol/Value interface. If there are no frame locals, or if
this frame is deemed to be a special case, return None."""
if hasattr(self._base, "frame_locals"):
return self._base.frame_locals()
frame = self.inferior_frame()
args = FrameVars(frame)
return args.fetch_frame_locals(True)
class SymValueWrapper(object):
"""A container class conforming to the Symbol/Value interface
which holds frame locals or frame arguments."""
# The FRAME argument is needed here because gdb.Symbol doesn't
# carry the block with it, and so read_var can't find symbols from
# outer (static link) frames.
def __init__(self, frame, symbol):
self.frame = frame
self.sym = symbol
def value(self):
"""Return the value associated with this symbol, or None"""
if self.frame is None:
return None
return self.frame.read_var(self.sym)
def symbol(self):
"""Return the symbol, or Python text, associated with this
symbol, or None"""
return self.sym
class FrameVars(object):
"""Utility class to fetch and store frame local variables, or
frame arguments."""
def __init__(self, frame):
self.frame = frame
def fetch_frame_locals(self, follow_link=False):
"""Public utility method to fetch frame local variables for
the stored frame. Frame arguments are not fetched. If there
are no frame local variables, return an empty list."""
lvars = []
frame = self.frame
try:
block = frame.block()
except RuntimeError:
block = None
traversed_link = False
while block is not None:
if block.is_global or block.is_static:
break
for sym in block:
# Exclude arguments from the innermost function, but
# if we found and traversed a static link, just treat
# all such variables as "local".
if sym.is_argument:
if not traversed_link:
continue
elif not sym.is_variable:
# We use an 'elif' here because is_variable
# returns False for arguments as well. Anyway,
# don't include non-variables here.
continue
lvars.append(SymValueWrapper(frame, sym))
if block.function is not None:
if not follow_link:
break
# If the frame has a static link, follow it here.
traversed_link = True
frame = frame.static_link()
if frame is None:
break
try:
block = frame.block()
except RuntimeError:
block = None
else:
block = block.superblock
return lvars
def fetch_frame_args(self):
"""Public utility method to fetch frame arguments for the
stored frame. Frame arguments are the only type fetched. If
there are no frame argument variables, return an empty list."""
args = []
try:
block = self.frame.block()
except RuntimeError:
block = None
while block is not None:
if block.is_global or block.is_static:
break
for sym in block:
if not sym.is_argument:
continue
args.append(SymValueWrapper(None, sym))
# Stop when the function itself is seen, to avoid showing
# variables from outer functions in a nested function.
# Note that we don't traverse the static link for
# arguments, only for locals.
if block.function is not None:
break
block = block.superblock
return args
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