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executable file
·1917 lines (1583 loc) · 62.4 KB
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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.
'''
# NOTE: some gdbs are linked with Python 3, so this file should be dual-syntax
# compatible (2.6+ and 3.0+). See #19308.
from __future__ import print_function
import gdb
import os
import locale
import sys
if sys.version_info[0] >= 3:
unichr = chr
xrange = range
long = int
# 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
# value computed later, see PyUnicodeObjectPtr.proxy()
_is_pep393 = None
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)
MAX_OUTPUT_LEN=1024
hexdigits = "0123456789abcdef"
ENCODING = locale.getpreferredencoding()
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 xrange(safety_limit(int(val)))
if sys.version_info[0] >= 3:
def write_unicode(file, text):
file.write(text)
else:
def write_unicode(file, text):
# Write a byte or unicode string to file. Unicode strings are encoded to
# ENCODING encoding with 'backslashreplace' error handler to avoid
# UnicodeEncodeError.
if isinstance(text, unicode):
text = text.encode(ENCODING, 'backslashreplace')
file.write(text)
try:
os_fsencode = os.fsencode
except AttributeError:
def os_fsencode(filename):
if not isinstance(filename, unicode):
return filename
encoding = sys.getfilesystemencoding()
if encoding == 'mbcs':
# mbcs doesn't support surrogateescape
return filename.encode(encoding)
encoded = []
for char in filename:
# surrogateescape error handler
if 0xDC80 <= ord(char) <= 0xDCFF:
byte = chr(ord(char) - 0xDC00)
else:
byte = char.encode(encoding)
encoded.append(byte)
return ''.join(encoded)
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
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):
if 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, coping with
some python 2 versus python 3 differences.
Various libpython types are defined using the "PyObject_HEAD" and
"PyObject_VAR_HEAD" macros.
In Python 2, this these are defined so that "ob_type" and (for a var
object) "ob_size" are fields of the type in question.
In Python 3, 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,
coping with some python 2 versus python 3 differences.
'''
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 == long(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:
return self.type().field('tp_name').string()
except NullPyObjectPtr:
# NULL tp_name?
return 'unknown'
except RuntimeError:
# Can't even read the object at all?
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 PyIntObject* with ob_ival 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(),
long(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'))
except RuntimeError:
# 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,
'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 long(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, PyDictObjectPtr):
out.write('(')
first = True
for pyop_arg, pyop_val in pyop_attrdict.iteritems():
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.iteritems()])
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:
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 > 0
assert dictoffset % _sizeof_void_p() == 0
dictptr = self._gdbval.cast(_type_char_ptr()) + dictoffset
PyObjectPtrPtr = PyObjectPtr.get_gdb_type().pointer()
dictptr = dictptr.cast(PyObjectPtrPtr)
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 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())
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, long(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_attrdict = self.get_attr_dict()
_write_instance_repr(out, visited,
self.safe_tp_name(), pyop_attrdict, 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*)
ml_name = m_ml['ml_name'].string()
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)
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_lnotab = self.pyop_field('co_lnotab').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'))
addr = 0
for addr_incr, line_incr in zip(co_lnotab[::2], co_lnotab[1::2]):
addr += ord(addr_incr)
if addr > addrq:
return lineno
lineno += ord(line_incr)
return lineno
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')
entries, nentries = self._get_entries(keys)
for i in safe_range(nentries):
ep = entries[i]
if long(values):
pyop_value = PyObjectPtr.from_pyobject_ptr(values[i])
else:
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):
# Guard against infinite loops:
if self.as_address() in visited:
out.write('{...}')
return
visited.add(self.as_address())
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('}')
def _get_entries(self, keys):
dk_nentries = int(keys['dk_nentries'])
dk_size = int(keys['dk_size'])
try:
# <= Python 3.5
return keys['dk_entries'], dk_size
except gdb.error:
# >= Python 3.6
pass
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']['as_1'].address
ent_addr = ent_addr.cast(_type_unsigned_char_ptr()) + offset
ent_ptr_t = gdb.lookup_type('PyDictKeyEntry').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/longobjrep.h has this declaration:
struct _longobject {
PyObject_VAR_HEAD
digit ob_digit[1];
};
with this description:
The absolute value of a number is equal to
SUM(for i=0 through abs(ob_size)-1) ob_digit[i] * 2**(SHIFT*i)
Negative numbers are represented with ob_size < 0;
zero is represented by ob_size == 0.
where SHIFT can be either:
#define PyLong_SHIFT 30
#define PyLong_SHIFT 15
'''
ob_size = long(self.field('ob_size'))
if ob_size == 0:
return 0
ob_digit = self.field('ob_digit')
if gdb.lookup_type('digit').sizeof == 2:
SHIFT = 15
else:
SHIFT = 30
digits = [long(ob_digit[i]) * 2**(SHIFT*i)
for i in safe_range(abs(ob_size))]
result = sum(digits)
if ob_size < 0:
result = -result
return result
def write_repr(self, out, visited):
# Write this out as a Python 3 int literal, i.e. without the "L" suffix
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.co = PyCodeObjectPtr.from_pyobject_ptr(self.field('f_code'))
self.co_name = self.co.pyop_field('co_name')
self.co_filename = self.co.pyop_field('co_filename')
self.f_lineno = int_from_int(self.field('f_lineno'))
self.f_lasti = int_from_int(self.field('f_lasti'))
self.co_nlocals = int_from_int(self.co.field('co_nlocals'))
self.co_varnames = PyTupleObjectPtr.from_pyobject_ptr(self.co.field('co_varnames'))
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
f_localsplus = self.field('f_localsplus')
for i in safe_range(self.co_nlocals):
pyop_value = PyObjectPtr.from_pyobject_ptr(f_localsplus[i])
if not pyop_value.is_null():
pyop_name = PyObjectPtr.from_pyobject_ptr(self.co_varnames[i])
yield (pyop_name, pyop_value)
def iter_globals(self):
'''
Yield a sequence of (name,value) pairs of PyObjectPtr instances, for
the global variables of this frame
'''
if self.is_optimized_out():
return ()
pyop_globals = self.pyop_field('f_globals')
return pyop_globals.iteritems()
def iter_builtins(self):
'''
Yield a sequence of (name,value) pairs of PyObjectPtr instances, for
the builtin variables
'''
if self.is_optimized_out():
return ()
pyop_builtins = self.pyop_field('f_builtins')
return pyop_builtins.iteritems()
def get_var_by_name(self, name):
'''
Look for the named local variable, returning a (PyObjectPtr, scope) pair
where scope is a string 'local', 'global', 'builtin'
If not found, return (None, None)
'''
for pyop_name, pyop_value in self.iter_locals():
if name == pyop_name.proxyval(set()):
return pyop_value, 'local'
for pyop_name, pyop_value in self.iter_globals():
if name == pyop_name.proxyval(set()):
return pyop_value, 'global'
for pyop_name, pyop_value in self.iter_builtins():
if name == pyop_name.proxyval(set()):
return pyop_value, 'builtin'
return None, None
def filename(self):
'''Get the path of the current Python source file, as a string'''
if self.is_optimized_out():
return '(frame information optimized out)'
return self.co_filename.proxyval(set())
def current_line_num(self):
'''Get current line number as an integer (1-based)
Translated from PyFrame_GetLineNumber and PyCode_Addr2Line
See Objects/lnotab_notes.txt
'''
if self.is_optimized_out():
return None
f_trace = self.field('f_trace')
if long(f_trace) != 0:
# we have a non-NULL f_trace:
return self.f_lineno
else:
#try:
return self.co.addr2line(self.f_lasti)
#except ValueError:
# return self.f_lineno
def current_line(self):
'''Get the text of the current source line as a string, with a trailing
newline character'''
if self.is_optimized_out():
return '(frame information optimized out)'
filename = self.filename()
try:
f = open(os_fsencode(filename), 'r')
except IOError:
return None
with f:
all_lines = f.readlines()
# Convert from 1-based current_line_num to 0-based list offset:
return all_lines[self.current_line_num()-1]
def write_repr(self, out, visited):
if self.is_optimized_out():
out.write('(frame information optimized out)')
return
out.write('Frame 0x%x, for file %s, line %i, in %s ('
% (self.as_address(),
self.co_filename.proxyval(visited),
self.current_line_num(),
self.co_name.proxyval(visited)))
first = True
for pyop_name, pyop_value in self.iter_locals():
if not first:
out.write(', ')
first = False
out.write(pyop_name.proxyval(visited))
out.write('=')
pyop_value.write_repr(out, visited)
out.write(')')
def print_traceback(self):
if self.is_optimized_out():
sys.stdout.write(' (frame information optimized out)\n')
return
visited = set()
sys.stdout.write(' File "%s", line %i, in %s\n'
% (self.co_filename.proxyval(visited),
self.current_line_num(),
self.co_name.proxyval(visited)))
class PySetObjectPtr(PyObjectPtr):
_typename = 'PySetObject'
@classmethod
def _dummy_key(self):
return gdb.lookup_global_symbol('_PySet_Dummy').value()
def __iter__(self):
dummy_ptr = self._dummy_key()
table = self.field('table')
for i in safe_range(self.field('mask') + 1):
setentry = table[i]
key = setentry['key']
if key != 0 and key != dummy_ptr:
yield PyObjectPtr.from_pyobject_ptr(key)
def proxyval(self, visited):
# Guard against infinite loops:
if self.as_address() in visited:
return ProxyAlreadyVisited('%s(...)' % self.safe_tp_name())