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#!/usr/bin/python

'''

From gdb 7 onwards, gdb's build can be configured --with-python, allowing gdb

to be extended with Python code e.g. for library-specific data visualizations,

such as for the C++ STL types. Documentation on this API can be seen at:

http://sourceware.org/gdb/current/onlinedocs/gdb/Python-API.html

This python module deals with the case when the process being debugged (the

"inferior process" in gdb parlance) is itself python, or more specifically,

linked against libpython. In this situation, almost every item of data is a

(PyObject*), and having the debugger merely print their addresses is not very

enlightening.

This module embeds knowledge about the implementation details of libpython so

that we can emit useful visualizations e.g. a string, a list, a dict, a frame

giving file/line information and the state of local variables

In particular, given a gdb.Value corresponding to a PyObject* in the inferior

process, we can generate a "proxy value" within the gdb process. For example,

given a PyObject* in the inferior process that is in fact a PyListObject*

holding three PyObject* that turn out to be PyBytesObject* instances, we can

generate a proxy value within the gdb process that is a list of bytes

instances:

[b"foo", b"bar", b"baz"]

Doing so can be expensive for complicated graphs of objects, and could take

some time, so we also have a "write_repr" method that writes a representation

of the data to a file-like object. This allows us to stop the traversal by

having the file-like object raise an exception if it gets too much data.

With both "proxyval" and "write_repr" we keep track of the set of all addresses

visited so far in the traversal, to avoid infinite recursion due to cycles in

the graph of object references.

We try to defer gdb.lookup_type() invocations for python types until as late as

possible: for a dynamically linked python binary, when the process starts in

the debugger, the libpython.so hasn't been dynamically loaded yet, so none of

the type names are known to the debugger

The module also extends gdb with some python-specific commands.

'''

import gdb

import os

import sys

MAX_UNICODE = 0x10_ffff

# Look up the gdb.Type for some standard types:

# Those need to be refreshed as types (pointer sizes) may change when

# gdb loads different executables

def _type_char_ptr():

return gdb.lookup_type('char').pointer() # char*

def _type_unsigned_char_ptr():

return gdb.lookup_type('unsigned char').pointer() # unsigned char*

def _type_unsigned_short_ptr():

return gdb.lookup_type('unsigned short').pointer()

def _type_unsigned_int_ptr():

return gdb.lookup_type('unsigned int').pointer()

def _sizeof_void_p():

return gdb.lookup_type('void').pointer().sizeof

def _managed_dict_offset():

# See pycore_object.h

pyobj = gdb.lookup_type("PyObject")

if any(field.name == "ob_ref_local" for field in pyobj.fields()):

return -1 * _sizeof_void_p()

else:

return -3 * _sizeof_void_p()

_INTERP_FRAME_HAS_TLBC_INDEX = None

def interp_frame_has_tlbc_index():

global _INTERP_FRAME_HAS_TLBC_INDEX

if _INTERP_FRAME_HAS_TLBC_INDEX is None:

interp_frame = gdb.lookup_type("_PyInterpreterFrame")

_INTERP_FRAME_HAS_TLBC_INDEX = any(field.name == "tlbc_index"

for field in interp_frame.fields())

return _INTERP_FRAME_HAS_TLBC_INDEX

Py_TPFLAGS_INLINE_VALUES = (1 << 2)

Py_TPFLAGS_MANAGED_DICT = (1 << 4)

Py_TPFLAGS_HEAPTYPE = (1 << 9)

Py_TPFLAGS_LONG_SUBCLASS = (1 << 24)

Py_TPFLAGS_LIST_SUBCLASS = (1 << 25)

Py_TPFLAGS_TUPLE_SUBCLASS = (1 << 26)

Py_TPFLAGS_BYTES_SUBCLASS = (1 << 27)

Py_TPFLAGS_UNICODE_SUBCLASS = (1 << 28)

Py_TPFLAGS_DICT_SUBCLASS = (1 << 29)

Py_TPFLAGS_BASE_EXC_SUBCLASS = (1 << 30)

Py_TPFLAGS_TYPE_SUBCLASS = (1 << 31)

#From pycore_frame.h

FRAME_OWNED_BY_INTERPRETER = 3

MAX_OUTPUT_LEN=1024

hexdigits = "0123456789abcdef"

USED_TAGS = 0b11

FRAME_INFO_OPTIMIZED_OUT = '(frame information optimized out)'

UNABLE_READ_INFO_PYTHON_FRAME = 'Unable to read information on python frame'

EVALFRAME = '_PyEval_EvalFrameDefault'

class NullPyObjectPtr(RuntimeError):

pass

def safety_limit(val):

# Given an integer value from the process being debugged, limit it to some

# safety threshold so that arbitrary breakage within said process doesn't

# break the gdb process too much (e.g. sizes of iterations, sizes of lists)

return min(val, 1000)

def safe_range(val):

# As per range, but don't trust the value too much: cap it to a safety

# threshold in case the data was corrupted

return range(safety_limit(int(val)))

class StringTruncated(RuntimeError):

pass

class TruncatedStringIO(object):

'''Similar to io.StringIO, but can truncate the output by raising a

StringTruncated exception'''

def __init__(self, maxlen=None):

self._val = ''

self.maxlen = maxlen

def write(self, data):

if self.maxlen:

if len(data) + len(self._val) > self.maxlen:

# Truncation:

self._val += data[0:self.maxlen - len(self._val)]

raise StringTruncated()

self._val += data

def getvalue(self):

return self._val

def _PyStackRef_AsPyObjectBorrow(gdbval):

return gdb.Value(int(gdbval['bits']) & ~USED_TAGS)

class PyObjectPtr(object):

"""

Class wrapping a gdb.Value that's either a (PyObject*) within the

inferior process, or some subclass pointer e.g. (PyBytesObject*)

There will be a subclass for every refined PyObject type that we care

about.

Note that at every stage the underlying pointer could be NULL, point

to corrupt data, etc; this is the debugger, after all.

"""

_typename = 'PyObject'

def __init__(self, gdbval, cast_to=None):

# Clear the tagged pointer

if gdbval.type.name == '_PyStackRef':

if cast_to is None:

cast_to = gdb.lookup_type('PyObject').pointer()

self._gdbval = _PyStackRef_AsPyObjectBorrow(gdbval).cast(cast_to)

elif cast_to:

self._gdbval = gdbval.cast(cast_to)

else:

self._gdbval = gdbval

def field(self, name):

'''

Get the gdb.Value for the given field within the PyObject.

Various libpython types are defined using the "PyObject_HEAD" and

"PyObject_VAR_HEAD" macros.

In Python, this is defined as an embedded PyVarObject type thus:

PyVarObject ob_base;

so that the "ob_size" field is located insize the "ob_base" field, and

the "ob_type" is most easily accessed by casting back to a (PyObject*).

'''

if self.is_null():

raise NullPyObjectPtr(self)

if name == 'ob_type':

pyo_ptr = self._gdbval.cast(PyObjectPtr.get_gdb_type())

return pyo_ptr.dereference()[name]

if name == 'ob_size':

pyo_ptr = self._gdbval.cast(PyVarObjectPtr.get_gdb_type())

return pyo_ptr.dereference()[name]

# General case: look it up inside the object:

return self._gdbval.dereference()[name]

def pyop_field(self, name):

'''

Get a PyObjectPtr for the given PyObject* field within this PyObject.

'''

return PyObjectPtr.from_pyobject_ptr(self.field(name))

def write_field_repr(self, name, out, visited):

'''

Extract the PyObject* field named "name", and write its representation

to file-like object "out"

'''

field_obj = self.pyop_field(name)

field_obj.write_repr(out, visited)

def get_truncated_repr(self, maxlen):

'''

Get a repr-like string for the data, but truncate it at "maxlen" bytes

(ending the object graph traversal as soon as you do)

'''

out = TruncatedStringIO(maxlen)

try:

self.write_repr(out, set())

except StringTruncated:

# Truncation occurred:

return out.getvalue() + '...(truncated)'

# No truncation occurred:

return out.getvalue()

def type(self):

return PyTypeObjectPtr(self.field('ob_type'))

def is_null(self):

return 0 == int(self._gdbval)

def is_optimized_out(self):

'''

Is the value of the underlying PyObject* visible to the debugger?

This can vary with the precise version of the compiler used to build

Python, and the precise version of gdb.

See e.g. https://bugzilla.redhat.com/show_bug.cgi?id=556975 with

PyEval_EvalFrameEx's "f"

'''

return self._gdbval.is_optimized_out

def safe_tp_name(self):

try:

ob_type = self.type()

tp_name = ob_type.field('tp_name')

return tp_name.string()

# NullPyObjectPtr: NULL tp_name?

# RuntimeError: Can't even read the object at all?

# UnicodeDecodeError: Failed to decode tp_name bytestring

except (NullPyObjectPtr, RuntimeError, UnicodeDecodeError):

return 'unknown'

def proxyval(self, visited):

'''

Scrape a value from the inferior process, and try to represent it

within the gdb process, whilst (hopefully) avoiding crashes when

the remote data is corrupt.

Derived classes will override this.

For example, a PyLongObjectPtr* with long_value 42 in the inferior process

should result in an int(42) in this process.

visited: a set of all gdb.Value pyobject pointers already visited

whilst generating this value (to guard against infinite recursion when

visiting object graphs with loops). Analogous to Py_ReprEnter and

Py_ReprLeave

'''

class FakeRepr(object):

"""

Class representing a non-descript PyObject* value in the inferior

process for when we don't have a custom scraper, intended to have

a sane repr().

"""

def __init__(self, tp_name, address):

self.tp_name = tp_name

self.address = address

def __repr__(self):

# For the NULL pointer, we have no way of knowing a type, so

# special-case it as per

# http://bugs.python.org/issue8032#msg100882

if self.address == 0:

return '0x0'

return '<%s at remote 0x%x>' % (self.tp_name, self.address)

return FakeRepr(self.safe_tp_name(),

int(self._gdbval))

def write_repr(self, out, visited):

'''

Write a string representation of the value scraped from the inferior

process to "out", a file-like object.

'''

# Default implementation: generate a proxy value and write its repr

# However, this could involve a lot of work for complicated objects,

# so for derived classes we specialize this

return out.write(repr(self.proxyval(visited)))

@classmethod

def subclass_from_type(cls, t):

'''

Given a PyTypeObjectPtr instance wrapping a gdb.Value that's a

(PyTypeObject*), determine the corresponding subclass of PyObjectPtr

to use

Ideally, we would look up the symbols for the global types, but that

isn't working yet:

(gdb) python print gdb.lookup_symbol('PyList_Type')[0].value

Traceback (most recent call last):

File "<string>", line 1, in <module>

NotImplementedError: Symbol type not yet supported in Python scripts.

Error while executing Python code.

For now, we use tp_flags, after doing some string comparisons on the

tp_name for some special-cases that don't seem to be visible through

flags

'''

try:

tp_name = t.field('tp_name').string()

tp_flags = int(t.field('tp_flags'))

# RuntimeError: NULL pointers

# UnicodeDecodeError: string() fails to decode the bytestring

except (RuntimeError, UnicodeDecodeError):

# Handle any kind of error e.g. NULL ptrs by simply using the base

# class

return cls

#print('tp_flags = 0x%08x' % tp_flags)

#print('tp_name = %r' % tp_name)

name_map = {'bool': PyBoolObjectPtr,

'classobj': PyClassObjectPtr,

'NoneType': PyNoneStructPtr,

'frame': PyFrameObjectPtr,

'set' : PySetObjectPtr,

'frozenset' : PySetObjectPtr,

'frozendict' : PyDictObjectPtr,

'builtin_function_or_method' : PyCFunctionObjectPtr,

'method-wrapper': wrapperobject,

}

if tp_name in name_map:

return name_map[tp_name]

if tp_flags & Py_TPFLAGS_HEAPTYPE:

return HeapTypeObjectPtr

if tp_flags & Py_TPFLAGS_LONG_SUBCLASS:

return PyLongObjectPtr

if tp_flags & Py_TPFLAGS_LIST_SUBCLASS:

return PyListObjectPtr

if tp_flags & Py_TPFLAGS_TUPLE_SUBCLASS:

return PyTupleObjectPtr

if tp_flags & Py_TPFLAGS_BYTES_SUBCLASS:

return PyBytesObjectPtr

if tp_flags & Py_TPFLAGS_UNICODE_SUBCLASS:

return PyUnicodeObjectPtr

if tp_flags & Py_TPFLAGS_DICT_SUBCLASS:

return PyDictObjectPtr

if tp_flags & Py_TPFLAGS_BASE_EXC_SUBCLASS:

return PyBaseExceptionObjectPtr

#if tp_flags & Py_TPFLAGS_TYPE_SUBCLASS:

# return PyTypeObjectPtr

# Use the base class:

return cls

@classmethod

def from_pyobject_ptr(cls, gdbval):

'''

Try to locate the appropriate derived class dynamically, and cast

the pointer accordingly.

'''

try:

p = PyObjectPtr(gdbval)

cls = cls.subclass_from_type(p.type())

return cls(gdbval, cast_to=cls.get_gdb_type())

except RuntimeError:

# Handle any kind of error e.g. NULL ptrs by simply using the base

# class

pass

return cls(gdbval)

@classmethod

def get_gdb_type(cls):

return gdb.lookup_type(cls._typename).pointer()

def as_address(self):

return int(self._gdbval)

class PyVarObjectPtr(PyObjectPtr):

_typename = 'PyVarObject'

class ProxyAlreadyVisited(object):

'''

Placeholder proxy to use when protecting against infinite recursion due to

loops in the object graph.

Analogous to the values emitted by the users of Py_ReprEnter and Py_ReprLeave

'''

def __init__(self, rep):

self._rep = rep

def __repr__(self):

return self._rep

def _write_instance_repr(out, visited, name, pyop_attrdict, address):

'''Shared code for use by all classes:

write a representation to file-like object "out"'''

out.write('<')

out.write(name)

# Write dictionary of instance attributes:

if isinstance(pyop_attrdict, (PyKeysValuesPair, PyDictObjectPtr)):

out.write('(')

first = True

items = pyop_attrdict.iteritems()

for pyop_arg, pyop_val in items:

if not first:

out.write(', ')

first = False

out.write(pyop_arg.proxyval(visited))

out.write('=')

pyop_val.write_repr(out, visited)

out.write(')')

out.write(' at remote 0x%x>' % address)

class InstanceProxy(object):

def __init__(self, cl_name, attrdict, address):

self.cl_name = cl_name

self.attrdict = attrdict

self.address = address

def __repr__(self):

if isinstance(self.attrdict, dict):

kwargs = ', '.join(["%s=%r" % (arg, val)

for arg, val in self.attrdict.items()])

return '<%s(%s) at remote 0x%x>' % (self.cl_name,

kwargs, self.address)

else:

return '<%s at remote 0x%x>' % (self.cl_name,

self.address)

def _PyObject_VAR_SIZE(typeobj, nitems):

if _PyObject_VAR_SIZE._type_size_t is None:

_PyObject_VAR_SIZE._type_size_t = gdb.lookup_type('size_t')

return ( ( typeobj.field('tp_basicsize') +

nitems * typeobj.field('tp_itemsize') +

(_sizeof_void_p() - 1)

) & ~(_sizeof_void_p() - 1)

).cast(_PyObject_VAR_SIZE._type_size_t)

_PyObject_VAR_SIZE._type_size_t = None

class HeapTypeObjectPtr(PyObjectPtr):

_typename = 'PyObject'

def get_attr_dict(self):

'''

Get the PyDictObject ptr representing the attribute dictionary

(or None if there's a problem)

'''

try:

typeobj = self.type()

dictoffset = int_from_int(typeobj.field('tp_dictoffset'))

if dictoffset != 0:

if dictoffset < 0:

if int_from_int(typeobj.field('tp_flags')) & Py_TPFLAGS_MANAGED_DICT:

assert dictoffset == -1

dictoffset = _managed_dict_offset()

else:

type_PyVarObject_ptr = gdb.lookup_type('PyVarObject').pointer()

tsize = int_from_int(self._gdbval.cast(type_PyVarObject_ptr)['ob_size'])

if tsize < 0:

tsize = -tsize

size = _PyObject_VAR_SIZE(typeobj, tsize)

dictoffset += size

assert dictoffset % _sizeof_void_p() == 0

dictptr = self._gdbval.cast(_type_char_ptr()) + dictoffset

PyObjectPtrPtr = PyObjectPtr.get_gdb_type().pointer()

dictptr = dictptr.cast(PyObjectPtrPtr)

if int(dictptr.dereference()) & 1:

return None

return PyObjectPtr.from_pyobject_ptr(dictptr.dereference())

except RuntimeError:

# Corrupt data somewhere; fail safe

pass

# Not found, or some kind of error:

return None

def get_keys_values(self):

typeobj = self.type()

has_values = int_from_int(typeobj.field('tp_flags')) & Py_TPFLAGS_MANAGED_DICT

if not has_values:

return None

obj_ptr = self._gdbval.cast(_type_char_ptr())

dict_ptr_ptr = obj_ptr + _managed_dict_offset()

dict_ptr = dict_ptr_ptr.cast(_type_char_ptr().pointer()).dereference()

if int(dict_ptr):

return None

char_ptr = obj_ptr + typeobj.field('tp_basicsize')

values_ptr = char_ptr.cast(gdb.lookup_type("PyDictValues").pointer())

values = values_ptr['values']

return PyKeysValuesPair(self.get_cached_keys(), values)

def get_cached_keys(self):

typeobj = self.type()

HeapTypePtr = gdb.lookup_type("PyHeapTypeObject").pointer()

return typeobj._gdbval.cast(HeapTypePtr)['ht_cached_keys']

def proxyval(self, visited):

'''

Support for classes.

Currently we just locate the dictionary using a transliteration to

python of _PyObject_GetDictPtr, ignoring descriptors

'''

# Guard against infinite loops:

if self.as_address() in visited:

return ProxyAlreadyVisited('<...>')

visited.add(self.as_address())

keys_values = self.get_keys_values()

if keys_values:

attr_dict = keys_values.proxyval(visited)

else:

pyop_attr_dict = self.get_attr_dict()

if pyop_attr_dict:

attr_dict = pyop_attr_dict.proxyval(visited)

else:

attr_dict = {}

tp_name = self.safe_tp_name()

# Class:

return InstanceProxy(tp_name, attr_dict, int(self._gdbval))

def write_repr(self, out, visited):

# Guard against infinite loops:

if self.as_address() in visited:

out.write('<...>')

return

visited.add(self.as_address())

pyop_attrs = self.get_keys_values()

if not pyop_attrs:

pyop_attrs = self.get_attr_dict()

_write_instance_repr(out, visited,

self.safe_tp_name(), pyop_attrs, self.as_address())

class ProxyException(Exception):

def __init__(self, tp_name, args):

self.tp_name = tp_name

self.args = args

def __repr__(self):

return '%s%r' % (self.tp_name, self.args)

class PyBaseExceptionObjectPtr(PyObjectPtr):

"""

Class wrapping a gdb.Value that's a PyBaseExceptionObject* i.e. an exception

within the process being debugged.

"""

_typename = 'PyBaseExceptionObject'

def proxyval(self, visited):

# Guard against infinite loops:

if self.as_address() in visited:

return ProxyAlreadyVisited('(...)')

visited.add(self.as_address())

arg_proxy = self.pyop_field('args').proxyval(visited)

return ProxyException(self.safe_tp_name(),

arg_proxy)

def write_repr(self, out, visited):

# Guard against infinite loops:

if self.as_address() in visited:

out.write('(...)')

return

visited.add(self.as_address())

out.write(self.safe_tp_name())

self.write_field_repr('args', out, visited)

class PyClassObjectPtr(PyObjectPtr):

"""

Class wrapping a gdb.Value that's a PyClassObject* i.e. a <classobj>

instance within the process being debugged.

"""

_typename = 'PyClassObject'

class BuiltInFunctionProxy(object):

def __init__(self, ml_name):

self.ml_name = ml_name

def __repr__(self):

return "<built-in function %s>" % self.ml_name

class BuiltInMethodProxy(object):

def __init__(self, ml_name, pyop_m_self):

self.ml_name = ml_name

self.pyop_m_self = pyop_m_self

def __repr__(self):

return ('<built-in method %s of %s object at remote 0x%x>'

% (self.ml_name,

self.pyop_m_self.safe_tp_name(),

self.pyop_m_self.as_address())

)

class PyCFunctionObjectPtr(PyObjectPtr):

"""

Class wrapping a gdb.Value that's a PyCFunctionObject*

(see Include/methodobject.h and Objects/methodobject.c)

"""

_typename = 'PyCFunctionObject'

def proxyval(self, visited):

m_ml = self.field('m_ml') # m_ml is a (PyMethodDef*)

try:

ml_name = m_ml['ml_name'].string()

except UnicodeDecodeError:

ml_name = '<ml_name:UnicodeDecodeError>'

pyop_m_self = self.pyop_field('m_self')

if pyop_m_self.is_null():

return BuiltInFunctionProxy(ml_name)

else:

return BuiltInMethodProxy(ml_name, pyop_m_self)

# Python implementation of location table parsing algorithm

def read(it):

return ord(next(it))

def read_varint(it):

b = read(it)

val = b & 63;

shift = 0;

while b & 64:

b = read(it)

shift += 6

val |= (b&63) << shift

return val

def read_signed_varint(it):

uval = read_varint(it)

if uval & 1:

return -(uval >> 1)

else:

return uval >> 1

def parse_location_table(firstlineno, linetable):

line = firstlineno

addr = 0

it = iter(linetable)

while True:

try:

first_byte = read(it)

except StopIteration:

return

code = (first_byte >> 3) & 15

length = (first_byte & 7) + 1

end_addr = addr + length

if code == 15:

yield addr, end_addr, None

addr = end_addr

continue

elif code == 14: # Long form

line_delta = read_signed_varint(it)

line += line_delta

end_line = line + read_varint(it)

col = read_varint(it)

end_col = read_varint(it)

elif code == 13: # No column

line_delta = read_signed_varint(it)

line += line_delta

elif code in (10, 11, 12): # new line

line_delta = code - 10

line += line_delta

column = read(it)

end_column = read(it)

else:

assert (0 <= code < 10)

second_byte = read(it)

column = code << 3 | (second_byte >> 4)

yield addr, end_addr, line

addr = end_addr

class PyCodeArrayPtr:

def __init__(self, gdbval):

self._gdbval = gdbval

def get_entry(self, index):

assert (index >= 0) and (index < self._gdbval["size"])

return self._gdbval["entries"][index]

class PyCodeObjectPtr(PyObjectPtr):

"""

Class wrapping a gdb.Value that's a PyCodeObject* i.e. a <code> instance

within the process being debugged.

"""

_typename = 'PyCodeObject'

def addr2line(self, addrq):

'''

Get the line number for a given bytecode offset

Analogous to PyCode_Addr2Line; translated from pseudocode in

Objects/lnotab_notes.txt

'''

co_linetable = self.pyop_field('co_linetable').proxyval(set())

# Initialize lineno to co_firstlineno as per PyCode_Addr2Line

# not 0, as lnotab_notes.txt has it:

lineno = int_from_int(self.field('co_firstlineno'))

if addrq < 0:

return lineno

addr = 0

for addr, end_addr, line in parse_location_table(lineno, co_linetable):

if addr <= addrq and end_addr > addrq:

return line

assert False, "Unreachable"

def items_from_keys_and_values(keys, values):

entries, nentries = PyDictObjectPtr._get_entries(keys)

for i in safe_range(nentries):

ep = entries[i]

pyop_value = PyObjectPtr.from_pyobject_ptr(values[i])

if not pyop_value.is_null():

pyop_key = PyObjectPtr.from_pyobject_ptr(ep['me_key'])

yield (pyop_key, pyop_value)

class PyKeysValuesPair:

def __init__(self, keys, values):

self.keys = keys

self.values = values

def iteritems(self):

return items_from_keys_and_values(self.keys, self.values)

def proxyval(self, visited):

result = {}

for pyop_key, pyop_value in self.iteritems():

proxy_key = pyop_key.proxyval(visited)

proxy_value = pyop_value.proxyval(visited)

result[proxy_key] = proxy_value

return result

class PyDictObjectPtr(PyObjectPtr):

"""

Class wrapping a gdb.Value that's a PyDictObject* i.e. a dict instance

within the process being debugged.

"""

_typename = 'PyDictObject'

def iteritems(self):

'''

Yields a sequence of (PyObjectPtr key, PyObjectPtr value) pairs,

analogous to dict.iteritems()

'''

keys = self.field('ma_keys')

values = self.field('ma_values')

has_values = int(values)

if has_values:

values = values['values']

if has_values:

for item in items_from_keys_and_values(keys, values):

yield item

return

entries, nentries = self._get_entries(keys)

for i in safe_range(nentries):

ep = entries[i]

pyop_value = PyObjectPtr.from_pyobject_ptr(ep['me_value'])

if not pyop_value.is_null():

pyop_key = PyObjectPtr.from_pyobject_ptr(ep['me_key'])

yield (pyop_key, pyop_value)

def proxyval(self, visited):

# Guard against infinite loops:

if self.as_address() in visited:

return ProxyAlreadyVisited('{...}')

visited.add(self.as_address())

result = {}

for pyop_key, pyop_value in self.iteritems():

proxy_key = pyop_key.proxyval(visited)

proxy_value = pyop_value.proxyval(visited)

result[proxy_key] = proxy_value

return result

def write_repr(self, out, visited):

tp_name = self.safe_tp_name()

is_frozendict = (tp_name == "frozendict")

# Guard against infinite loops:

if self.as_address() in visited:

if is_frozendict:

out.write(tp_name + '({...})')

else:

out.write('{...}')

return

visited.add(self.as_address())

if is_frozendict:

out.write(tp_name + '(')

out.write('{')

first = True

for pyop_key, pyop_value in self.iteritems():

if not first:

out.write(', ')

first = False

pyop_key.write_repr(out, visited)

out.write(': ')

pyop_value.write_repr(out, visited)

out.write('}')

if is_frozendict:

out.write(')')

@staticmethod

def _get_entries(keys):

dk_nentries = int(keys['dk_nentries'])

dk_size = 1<<int(keys['dk_log2_size'])

if dk_size <= 0xFF:

offset = dk_size

elif dk_size <= 0xFFFF:

offset = 2 * dk_size

elif dk_size <= 0xFFFFFFFF:

offset = 4 * dk_size

else:

offset = 8 * dk_size

ent_addr = keys['dk_indices'].address

ent_addr = ent_addr.cast(_type_unsigned_char_ptr()) + offset

if int(keys['dk_kind']) == 0: # DICT_KEYS_GENERAL

ent_ptr_t = gdb.lookup_type('PyDictKeyEntry').pointer()

else:

ent_ptr_t = gdb.lookup_type('PyDictUnicodeEntry').pointer()

ent_addr = ent_addr.cast(ent_ptr_t)

return ent_addr, dk_nentries

class PyListObjectPtr(PyObjectPtr):

_typename = 'PyListObject'

def __getitem__(self, i):

# Get the gdb.Value for the (PyObject*) with the given index:

field_ob_item = self.field('ob_item')

return field_ob_item[i]

def proxyval(self, visited):

# Guard against infinite loops:

if self.as_address() in visited:

return ProxyAlreadyVisited('[...]')

visited.add(self.as_address())

result = [PyObjectPtr.from_pyobject_ptr(self[i]).proxyval(visited)

for i in safe_range(int_from_int(self.field('ob_size')))]

return result

def write_repr(self, out, visited):

# Guard against infinite loops:

if self.as_address() in visited:

out.write('[...]')

return

visited.add(self.as_address())

out.write('[')

for i in safe_range(int_from_int(self.field('ob_size'))):

if i > 0:

out.write(', ')

element = PyObjectPtr.from_pyobject_ptr(self[i])

element.write_repr(out, visited)

out.write(']')

class PyLongObjectPtr(PyObjectPtr):

_typename = 'PyLongObject'

def proxyval(self, visited):

'''

Python's Include/cpython/longinterpr.h has this declaration:

typedef struct _PyLongValue {

uintptr_t lv_tag; /* Number of digits, sign and flags */

digit ob_digit[1];

} _PyLongValue;

struct _longobject {

PyObject_HEAD

_PyLongValue long_value;

};

with this description:

The absolute value of a number is equal to

SUM(for i=0 through ndigits-1) ob_digit[i] * 2**(PyLong_SHIFT*i)

The sign of the value is stored in the lower 2 bits of lv_tag.

- 0: Positive

- 1: Zero

- 2: Negative

The third lowest bit of lv_tag is set to 1 for the small ints and 0 otherwise.

where SHIFT can be either:

#define PyLong_SHIFT 30

#define PyLong_SHIFT 15

'''

long_value = self.field('long_value')

lv_tag = int(long_value['lv_tag'])

size = lv_tag >> 3

if size == 0:

return 0

ob_digit = long_value['ob_digit']

if gdb.lookup_type('digit').sizeof == 2:

SHIFT = 15

else:

SHIFT = 30

digits = [int(ob_digit[i]) * 2**(SHIFT*i)

for i in safe_range(size)]

result = sum(digits)

if (lv_tag & 3) == 2:

result = -result

return result

def write_repr(self, out, visited):

# Write this out as a Python int literal

proxy = self.proxyval(visited)

out.write("%s" % proxy)

class PyBoolObjectPtr(PyLongObjectPtr):

"""

Class wrapping a gdb.Value that's a PyBoolObject* i.e. one of the two

<bool> instances (Py_True/Py_False) within the process being debugged.

"""

def proxyval(self, visited):

if PyLongObjectPtr.proxyval(self, visited):

return True

else:

return False

class PyNoneStructPtr(PyObjectPtr):

"""

Class wrapping a gdb.Value that's a PyObject* pointing to the

singleton (we hope) _Py_NoneStruct with ob_type PyNone_Type

"""

_typename = 'PyObject'

def proxyval(self, visited):

return None

class PyFrameObjectPtr(PyObjectPtr):

_typename = 'PyFrameObject'

def __init__(self, gdbval, cast_to=None):

PyObjectPtr.__init__(self, gdbval, cast_to)

if not self.is_optimized_out():

self._frame = PyFramePtr(self.field('f_frame'))

def iter_locals(self):

'''

Yield a sequence of (name,value) pairs of PyObjectPtr instances, for

the local variables of this frame

'''

if self.is_optimized_out():

return

return self._frame.iter_locals()

def iter_globals(self):

'''

View remainder of file in raw view

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