#!/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()

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 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:
 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 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'))
 # 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,
 '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*)
 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)


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 RuntimeError:
 # >= 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'].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

 try:
 return self.co.addr2line(self.f_lasti)
 except Exception:
 # bpo-34989: addr2line() is a complex function, it can fail in many
 # ways. For example, it fails with a TypeError on "FakeRepr" if
 # gdb fails to load debug symbols. Use a catch-all "except
 # Exception" to make the whole function safe. The caller has to
 # handle None anyway for optimized Python.
 return None

 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)'

 lineno = self.current_line_num()
 if lineno is None:
 return '(failed to get frame line number)'

 filename = self.filename()
 try:
 with open(os_fsencode(filename), 'r') as fp:
 lines = fp.readlines()
 except IOError:
 return None

 try:
 # Convert from 1-based current_line_num to 0-based list offset
 return lines[lineno - 1]
 except IndexError:
 return None

 def write_repr(self, out, visited):
 if self.is_optimized_out():
 out.write('(frame information optimized out)')
 return
 lineno = self.current_line_num()
 lineno = str(lineno) if lineno is not None else "?"
 out.write('Frame 0x%x, for file %s, line %s, in %s ('
 % (self.as_address(),
 self.co_filename.proxyval(visited),
 lineno,
 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()
 lineno = self.current_line_num()
 lineno = str(lineno) if lineno is not None else "?"
 sys.stdout.write(' File "%s", line %s, in %s\n'
 % (self.co_filename.proxyval(visited),
 lineno,
 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())
 visited.add(self.as_address())

 members = (key.proxyval(visited) for key in self)
 if self.safe_tp_name() == 'frozenset':
 return frozenset(members)
 else:
 return set(members)

 def write_repr(self, out, visited):
 # Emulate Python 3's set_repr
 tp_name = self.safe_tp_name()

 # Guard against infinite loops:
 if self.as_address() in visited:
 out.write('(...)')
 return
 visited.add(self.as_address())

 # Python 3's set_repr special-cases the empty set:
 if not self.field('used'):
 out.write(tp_name)
 out.write('()')
 return

 # Python 3 uses {} for set literals:
 if tp_name != 'set':
 out.write(tp_name)
 out.write('(')

 out.write('{')
 first = True
 for key in self:
 if not first:
 out.write(', ')
 first = False
 key.write_repr(out, visited)
 out.write('}')

 if tp_name != 'set':
 out.write(')')


class PyBytesObjectPtr(PyObjectPtr):
 _typename = 'PyBytesObject'

 def __str__(self):
 field_ob_size = self.field('ob_size')
 field_ob_sval = self.field('ob_sval')
 char_ptr = field_ob_sval.address.cast(_type_unsigned_char_ptr())
 return ''.join([chr(char_ptr[i]) for i in safe_range(field_ob_size)])

 def proxyval(self, visited):
 return str(self)

 def write_repr(self, out, visited):
 # Write this out as a Python 3 bytes literal, i.e. with a "b" prefix

 # Get a PyStringObject* within the Python 2 gdb process:
 proxy = self.proxyval(visited)

 # Transliteration of Python 3's Objects/bytesobject.c:PyBytes_Repr
 # to Python 2 code:
 quote = "'"
 if "'" in proxy and not '"' in proxy:
 quote = '"'
 out.write('b')
 out.write(quote)
 for byte in proxy:
 if byte == quote or byte == '\\':
 out.write('\\')
 out.write(byte)
 elif byte == '\t':
 out.write('\\t')
 elif byte == '\n':
 out.write('\\n')
 elif byte == '\r':
 out.write('\\r')
 elif byte < ' ' or ord(byte) >= 0x7f:
 out.write('\\x')
 out.write(hexdigits[(ord(byte) & 0xf0) >> 4])
 out.write(hexdigits[ord(byte) & 0xf])
 else:
 out.write(byte)
 out.write(quote)

class PyTupleObjectPtr(PyObjectPtr):
 _typename = 'PyTupleObject'

 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 = tuple(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)
 if self.field('ob_size') == 1:
 out.write(',)')
 else:
 out.write(')')

class PyTypeObjectPtr(PyObjectPtr):
 _typename = 'PyTypeObject'


def _unichr_is_printable(char):
 # Logic adapted from Python 3's Tools/unicode/makeunicodedata.py
 if char == u" ":
 return True
 import unicodedata
 return unicodedata.category(char) not in ("C", "Z")

if sys.maxunicode >= 0x10000:
 _unichr = unichr
else:
 # Needed for proper surrogate support if sizeof(Py_UNICODE) is 2 in gdb
 def _unichr(x):
 if x < 0x10000:
 return unichr(x)
 x -= 0x10000
 ch1 = 0xD800 | (x >> 10)
 ch2 = 0xDC00 | (x & 0x3FF)
 return unichr(ch1) + unichr(ch2)


class PyUnicodeObjectPtr(PyObjectPtr):
 _typename = 'PyUnicodeObject'

 def char_width(self):
 _type_Py_UNICODE = gdb.lookup_type('Py_UNICODE')
 return _type_Py_UNICODE.sizeof

 def proxyval(self, visited):
 global _is_pep393
 if _is_pep393 is None:
 fields = gdb.lookup_type('PyUnicodeObject').fields()
 _is_pep393 = 'data' in [f.name for f in fields]
 if _is_pep393:
 # Python 3.3 and newer
 may_have_surrogates = False
 compact = self.field('_base')
 ascii = compact['_base']
 state = ascii['state']
 is_compact_ascii = (int(state['ascii']) and int(state['compact']))
 if not int(state['ready']):
 # string is not ready
 field_length = long(compact['wstr_length'])
 may_have_surrogates = True
 field_str = ascii['wstr']
 else:
 field_length = long(ascii['length'])
 if is_compact_ascii:
 field_str = ascii.address + 1
 elif int(state['compact']):
 field_str = compact.address + 1
 else:
 field_str = self.field('data')['any']
 repr_kind = int(state['kind'])
 if repr_kind == 1:
 field_str = field_str.cast(_type_unsigned_char_ptr())
 elif repr_kind == 2:
 field_str = field_str.cast(_type_unsigned_short_ptr())
 elif repr_kind == 4:
 field_str = field_str.cast(_type_unsigned_int_ptr())
 else:
 # Python 3.2 and earlier
 field_length = long(self.field('length'))
 field_str = self.field('str')
 may_have_surrogates = self.char_width() == 2

 # Gather a list of ints from the Py_UNICODE array; these are either
 # UCS-1, UCS-2 or UCS-4 code points:
 if not may_have_surrogates:
 Py_UNICODEs = [int(field_str[i]) for i in safe_range(field_length)]
 else:
 # A more elaborate routine if sizeof(Py_UNICODE) is 2 in the
 # inferior process: we must join surrogate pairs.
 Py_UNICODEs = []
 i = 0
 limit = safety_limit(field_length)
 while i < limit:
 ucs = int(field_str[i])
 i += 1
 if ucs < 0xD800 or ucs >= 0xDC00 or i == field_length:
 Py_UNICODEs.append(ucs)
 continue
 # This could be a surrogate pair.
 ucs2 = int(field_str[i])
 if ucs2 < 0xDC00 or ucs2 > 0xDFFF:
 continue
 code = (ucs & 0x03FF) << 10
 code |= ucs2 & 0x03FF
 code += 0x00010000
 Py_UNICODEs.append(code)
 i += 1

 # Convert the int code points to unicode characters, and generate a
 # local unicode instance.
 # This splits surrogate pairs if sizeof(Py_UNICODE) is 2 here (in gdb).
 result = u''.join([
 (_unichr(ucs) if ucs <= 0x10ffff else '\ufffd')
 for ucs in Py_UNICODEs])
 return result

 def write_repr(self, out, visited):
 # Write this out as a Python 3 str literal, i.e. without a "u" prefix

 # Get a PyUnicodeObject* within the Python 2 gdb process:
 proxy = self.proxyval(visited)

 # Transliteration of Python 3's Object/unicodeobject.c:unicode_repr
 # to Python 2:
 if "'" in proxy and '"' not in proxy:
 quote = '"'
 else:
 quote = "'"
 out.write(quote)

 i = 0
 while i < len(proxy):
 ch = proxy[i]
 i += 1

 # Escape quotes and backslashes
 if ch == quote or ch == '\\':
 out.write('\\')
 out.write(ch)

 # Map special whitespace to '\t', \n', '\r'
 elif ch == '\t':
 out.write('\\t')
 elif ch == '\n':
 out.write('\\n')
 elif ch == '\r':
 out.write('\\r')

 # Map non-printable US ASCII to '\xhh' */
 elif ch < ' ' or ch == 0x7F:
 out.write('\\x')
 out.write(hexdigits[(ord(ch) >> 4) & 0x000F])
 out.write(hexdigits[ord(ch) & 0x000F])

 # Copy ASCII characters as-is
 elif ord(ch) < 0x7F:
 out.write(ch)

 # Non-ASCII characters
 else:
 ucs = ch
 ch2 = None
 if sys.maxunicode < 0x10000:
 # If sizeof(Py_UNICODE) is 2 here (in gdb), join
 # surrogate pairs before calling _unichr_is_printable.
 if (i < len(proxy)
 and 0xD800 <= ord(ch) < 0xDC00 \
 and 0xDC00 <= ord(proxy[i]) <= 0xDFFF):
 ch2 = proxy[i]
 ucs = ch + ch2
 i += 1

 # Unfortuately, Python 2's unicode type doesn't seem
 # to expose the "isprintable" method
 printable = _unichr_is_printable(ucs)
 if printable:
 try:
 ucs.encode(ENCODING)
 except UnicodeEncodeError:
 printable = False

 # Map Unicode whitespace and control characters
 # (categories Z* and C* except ASCII space)
 if not printable:
 if ch2 is not None:
 # Match Python 3's representation of non-printable
 # wide characters.
 code = (ord(ch) & 0x03FF) << 10
 code |= ord(ch2) & 0x03FF
 code += 0x00010000
 else:
 code = ord(ucs)

 # Map 8-bit characters to '\\xhh'
 if code <= 0xff:
 out.write('\\x')
 out.write(hexdigits[(code >> 4) & 0x000F])
 out.write(hexdigits[code & 0x000F])
 # Map 21-bit characters to '\U00xxxxxx'
 elif code >= 0x10000:
 out.write('\\U')
 out.write(hexdigits[(code >> 28) & 0x0000000F])
 out.write(hexdigits[(code >> 24) & 0x0000000F])
 out.write(hexdigits[(code >> 20) & 0x0000000F])
 out.write(hexdigits[(code >> 16) & 0x0000000F])
 out.write(hexdigits[(code >> 12) & 0x0000000F])
 out.write(hexdigits[(code >> 8) & 0x0000000F])
 out.write(hexdigits[(code >> 4) & 0x0000000F])
 out.write(hexdigits[code & 0x0000000F])
 # Map 16-bit characters to '\uxxxx'
 else:
 out.write('\\u')
 out.write(hexdigits[(code >> 12) & 0x000F])
 out.write(hexdigits[(code >> 8) & 0x000F])
 out.write(hexdigits[(code >> 4) & 0x000F])
 out.write(hexdigits[code & 0x000F])
 else:
 # Copy characters as-is
 out.write(ch)
 if ch2 is not None:
 out.write(ch2)

 out.write(quote)


class wrapperobject(PyObjectPtr):
 _typename = 'wrapperobject'

 def safe_name(self):
 try:
 name = self.field('descr')['d_base']['name'].string()
 return repr(name)
 except (NullPyObjectPtr, RuntimeError, UnicodeDecodeError):
 return '<unknown name>'

 def safe_tp_name(self):
 try:
 return self.field('self')['ob_type']['tp_name'].string()
 except (NullPyObjectPtr, RuntimeError, UnicodeDecodeError):
 return '<unknown tp_name>'

 def safe_self_addresss(self):
 try:
 address = long(self.field('self'))
 return '%#x' % address
 except (NullPyObjectPtr, RuntimeError):
 return '<failed to get self address>'

 def proxyval(self, visited):
 name = self.safe_name()
 tp_name = self.safe_tp_name()
 self_address = self.safe_self_addresss()
 return ("<method-wrapper %s of %s object at %s>"
 % (name, tp_name, self_address))

 def write_repr(self, out, visited):
 proxy = self.proxyval(visited)
 out.write(proxy)


def int_from_int(gdbval):
 return int(gdbval)


def stringify(val):
 # TODO: repr() puts everything on one line; pformat can be nicer, but
 # can lead to v.long results; this function isolates the choice
 if True:
 return repr(val)
 else:
 from pprint import pformat
 return pformat(val)


class PyObjectPtrPrinter:
 "Prints a (PyObject*)"

 def __init__ (self, gdbval):
 self.gdbval = gdbval

 def to_string (self):
 pyop = PyObjectPtr.from_pyobject_ptr(self.gdbval)
 if True:
 return pyop.get_truncated_repr(MAX_OUTPUT_LEN)
 else:
 # Generate full proxy value then stringify it.
 # Doing so could be expensive
 proxyval = pyop.proxyval(set())
 return stringify(proxyval)

def pretty_printer_lookup(gdbval):
 type = gdbval.type.unqualified()
 if type.code != gdb.TYPE_CODE_PTR:
 return None

 type = type.target().unqualified()
 t = str(type)
 if t in ("PyObject", "PyFrameObject", "PyUnicodeObject", "wrapperobject"):
 return PyObjectPtrPrinter(gdbval)

"""
During development, I've been manually invoking the code in this way:
(gdb) python

import sys
sys.path.append('/home/david/coding/python-gdb')
import libpython
end

then reloading it after each edit like this:
(gdb) python reload(libpython)

The following code should ensure that the prettyprinter is registered
if the code is autoloaded by gdb when visiting libpython.so, provided
that this python file is installed to the same path as the library (or its
.debug file) plus a "-gdb.py" suffix, e.g:
 /usr/lib/libpython2.6.so.1.0-gdb.py
 /usr/lib/debug/usr/lib/libpython2.6.so.1.0.debug-gdb.py
"""
def register (obj):
 if obj is None:
 obj = gdb

 # Wire up the pretty-printer
 obj.pretty_printers.append(pretty_printer_lookup)

register (gdb.current_objfile ())



# Unfortunately, the exact API exposed by the gdb module varies somewhat
# from build to build
# See http://bugs.python.org/issue8279?#msg102276

class Frame(object):
 '''
 Wrapper for gdb.Frame, adding various methods
 '''
 def __init__(self, gdbframe):
 self._gdbframe = gdbframe

 def older(self):
 older = self._gdbframe.older()
 if older:
 return Frame(older)
 else:
 return None

 def newer(self):
 newer = self._gdbframe.newer()
 if newer:
 return Frame(newer)
 else:
 return None

 def select(self):
 '''If supported, select this frame and return True; return False if unsupported

 Not all builds have a gdb.Frame.select method; seems to be present on Fedora 12
 onwards, but absent on Ubuntu buildbot'''
 if not hasattr(self._gdbframe, 'select'):
 print ('Unable to select frame: '
 'this build of gdb does not expose a gdb.Frame.select method')
 return False
 self._gdbframe.select()
 return True

 def get_index(self):
 '''Calculate index of frame, starting at 0 for the newest frame within
 this thread'''
 index = 0
 # Go down until you reach the newest frame:
 iter_frame = self
 while iter_frame.newer():
 index += 1
 iter_frame = iter_frame.newer()
 return index

 # We divide frames into:
 # - "python frames":
 # - "bytecode frames" i.e. PyEval_EvalFrameEx
 # - "other python frames": things that are of interest from a python
 # POV, but aren't bytecode (e.g. GC, GIL)
 # - everything else

 def is_python_frame(self):
 '''Is this a _PyEval_EvalFrameDefault frame, or some other important
 frame? (see is_other_python_frame for what "important" means in this
 context)'''
 if self.is_evalframe():
 return True
 if self.is_other_python_frame():
 return True
 return False

 def is_evalframe(self):
 '''Is this a _PyEval_EvalFrameDefault frame?'''
 if self._gdbframe.name() == EVALFRAME:
 '''
 I believe we also need to filter on the inline
 struct frame_id.inline_depth, only regarding frames with
 an inline depth of 0 as actually being this function

 So we reject those with type gdb.INLINE_FRAME
 '''
 if self._gdbframe.type() == gdb.NORMAL_FRAME:
 # We have a _PyEval_EvalFrameDefault frame:
 return True

 return False

 def is_other_python_frame(self):
 '''Is this frame worth displaying in python backtraces?
 Examples:
 - waiting on the GIL
 - garbage-collecting
 - within a CFunction
 If it is, return a descriptive string
 For other frames, return False
 '''
 if self.is_waiting_for_gil():
 return 'Waiting for the GIL'

 if self.is_gc_collect():
 return 'Garbage-collecting'

 # Detect invocations of PyCFunction instances:
 frame = self._gdbframe
 caller = frame.name()
 if not caller:
 return False

 if (caller.startswith('cfunction_vectorcall_') or
 caller == 'cfunction_call_varargs'):
 arg_name = 'func'
 # Within that frame:
 # "func" is the local containing the PyObject* of the
 # PyCFunctionObject instance
 # "f" is the same value, but cast to (PyCFunctionObject*)
 # "self" is the (PyObject*) of the 'self'
 try:
 # Use the prettyprinter for the func:
 func = frame.read_var(arg_name)
 return str(func)
 except ValueError:
 return ('PyCFunction invocation (unable to read %s: '
 'missing debuginfos?)' % arg_name)
 except RuntimeError:
 return 'PyCFunction invocation (unable to read %s)' % arg_name

 if caller == 'wrapper_call':
 arg_name = 'wp'
 try:
 func = frame.read_var(arg_name)
 return str(func)
 except ValueError:
 return ('<wrapper_call invocation (unable to read %s: '
 'missing debuginfos?)>' % arg_name)
 except RuntimeError:
 return '<wrapper_call invocation (unable to read %s)>' % arg_name

 # This frame isn't worth reporting:
 return False

 def is_waiting_for_gil(self):
 '''Is this frame waiting on the GIL?'''
 # This assumes the _POSIX_THREADS version of Python/ceval_gil.h:
 name = self._gdbframe.name()
 if name:
 return 'pthread_cond_timedwait' in name

 def is_gc_collect(self):
 '''Is this frame "collect" within the garbage-collector?'''
 return self._gdbframe.name() == 'collect'

 def get_pyop(self):
 try:
 f = self._gdbframe.read_var('f')
 frame = PyFrameObjectPtr.from_pyobject_ptr(f)
 if not frame.is_optimized_out():
 return frame
 # gdb is unable to get the "f" argument of PyEval_EvalFrameEx()
 # because it was "optimized out". Try to get "f" from the frame
 # of the caller, PyEval_EvalCodeEx().
 orig_frame = frame
 caller = self._gdbframe.older()
 if caller:
 f = caller.read_var('f')
 frame = PyFrameObjectPtr.from_pyobject_ptr(f)
 if not frame.is_optimized_out():
 return frame
 return orig_frame
 except ValueError:
 return None

 @classmethod
 def get_selected_frame(cls):
 _gdbframe = gdb.selected_frame()
 if _gdbframe:
 return Frame(_gdbframe)
 return None

 @classmethod
 def get_selected_python_frame(cls):
 '''Try to obtain the Frame for the python-related code in the selected
 frame, or None'''
 try:
 frame = cls.get_selected_frame()
 except gdb.error:
 # No frame: Python didn't start yet
 return None

 while frame:
 if frame.is_python_frame():
 return frame
 frame = frame.older()

 # Not found:
 return None

 @classmethod
 def get_selected_bytecode_frame(cls):
 '''Try to obtain the Frame for the python bytecode interpreter in the
 selected GDB frame, or None'''
 frame = cls.get_selected_frame()

 while frame:
 if frame.is_evalframe():
 return frame
 frame = frame.older()

 # Not found:
 return None

 def print_summary(self):
 if self.is_evalframe():
 pyop = self.get_pyop()
 if pyop:
 line = pyop.get_truncated_repr(MAX_OUTPUT_LEN)
 write_unicode(sys.stdout, '#%i %s\n' % (self.get_index(), line))
 if not pyop.is_optimized_out():
 line = pyop.current_line()
 if line is not None:
 sys.stdout.write(' %s\n' % line.strip())
 else:
 sys.stdout.write('#%i (unable to read python frame information)\n' % self.get_index())
 else:
 info = self.is_other_python_frame()
 if info:
 sys.stdout.write('#%i %s\n' % (self.get_index(), info))
 else:
 sys.stdout.write('#%i\n' % self.get_index())

 def print_traceback(self):
 if self.is_evalframe():
 pyop = self.get_pyop()
 if pyop:
 pyop.print_traceback()
 if not pyop.is_optimized_out():
 line = pyop.current_line()
 if line is not None:
 sys.stdout.write(' %s\n' % line.strip())
 else:
 sys.stdout.write(' (unable to read python frame information)\n')
 else:
 info = self.is_other_python_frame()
 if info:
 sys.stdout.write(' %s\n' % info)
 else:
 sys.stdout.write(' (not a python frame)\n')

class PyList(gdb.Command):
 '''List the current Python source code, if any

 Use
 py-list START
 to list at a different line number within the python source.

 Use
 py-list START, END
 to list a specific range of lines within the python source.
 '''

 def __init__(self):
 gdb.Command.__init__ (self,
 "py-list",
 gdb.COMMAND_FILES,
 gdb.COMPLETE_NONE)


 def invoke(self, args, from_tty):
 import re

 start = None
 end = None

 m = re.match(r'\s*(\d+)\s*', args)
 if m:
 start = int(m.group(0))
 end = start + 10

 m = re.match(r'\s*(\d+)\s*,\s*(\d+)\s*', args)
 if m:
 start, end = map(int, m.groups())

 # py-list requires an actual PyEval_EvalFrameEx frame:
 frame = Frame.get_selected_bytecode_frame()
 if not frame:
 print('Unable to locate gdb frame for python bytecode interpreter')
 return

 pyop = frame.get_pyop()
 if not pyop or pyop.is_optimized_out():
 print('Unable to read information on python frame')
 return

 filename = pyop.filename()
 lineno = pyop.current_line_num()
 if lineno is None:
 print('Unable to read python frame line number')
 return

 if start is None:
 start = lineno - 5
 end = lineno + 5

 if start<1:
 start = 1

 try:
 f = open(os_fsencode(filename), 'r')
 except IOError as err:
 sys.stdout.write('Unable to open %s: %s\n'
 % (filename, err))
 return
 with f:
 all_lines = f.readlines()
 # start and end are 1-based, all_lines is 0-based;
 # so [start-1:end] as a python slice gives us [start, end] as a
 # closed interval
 for i, line in enumerate(all_lines[start-1:end]):
 linestr = str(i+start)
 # Highlight current line:
 if i + start == lineno:
 linestr = '>' + linestr
 sys.stdout.write('%4s %s' % (linestr, line))


# ...and register the command:
PyList()

def move_in_stack(move_up):
 '''Move up or down the stack (for the py-up/py-down command)'''
 frame = Frame.get_selected_python_frame()
 if not frame:
 print('Unable to locate python frame')
 return

 while frame:
 if move_up:
 iter_frame = frame.older()
 else:
 iter_frame = frame.newer()

 if not iter_frame:
 break

 if iter_frame.is_python_frame():
 # Result:
 if iter_frame.select():
 iter_frame.print_summary()
 return

 frame = iter_frame

 if move_up:
 print('Unable to find an older python frame')
 else:
 print('Unable to find a newer python frame')

class PyUp(gdb.Command):
 'Select and print the python stack frame that called this one (if any)'
 def __init__(self):
 gdb.Command.__init__ (self,
 "py-up",
 gdb.COMMAND_STACK,
 gdb.COMPLETE_NONE)


 def invoke(self, args, from_tty):
 move_in_stack(move_up=True)

class PyDown(gdb.Command):
 'Select and print the python stack frame called by this one (if any)'
 def __init__(self):
 gdb.Command.__init__ (self,
 "py-down",
 gdb.COMMAND_STACK,
 gdb.COMPLETE_NONE)


 def invoke(self, args, from_tty):
 move_in_stack(move_up=False)

# Not all builds of gdb have gdb.Frame.select
if hasattr(gdb.Frame, 'select'):
 PyUp()
 PyDown()

class PyBacktraceFull(gdb.Command):
 'Display the current python frame and all the frames within its call stack (if any)'
 def __init__(self):
 gdb.Command.__init__ (self,
 "py-bt-full",
 gdb.COMMAND_STACK,
 gdb.COMPLETE_NONE)


 def invoke(self, args, from_tty):
 frame = Frame.get_selected_python_frame()
 if not frame:
 print('Unable to locate python frame')
 return

 while frame:
 if frame.is_python_frame():
 frame.print_summary()
 frame = frame.older()

PyBacktraceFull()

class PyBacktrace(gdb.Command):
 'Display the current python frame and all the frames within its call stack (if any)'
 def __init__(self):
 gdb.Command.__init__ (self,
 "py-bt",
 gdb.COMMAND_STACK,
 gdb.COMPLETE_NONE)


 def invoke(self, args, from_tty):
 frame = Frame.get_selected_python_frame()
 if not frame:
 print('Unable to locate python frame')
 return

 sys.stdout.write('Traceback (most recent call first):\n')
 while frame:
 if frame.is_python_frame():
 frame.print_traceback()
 frame = frame.older()

PyBacktrace()

class PyPrint(gdb.Command):
 'Look up the given python variable name, and print it'
 def __init__(self):
 gdb.Command.__init__ (self,
 "py-print",
 gdb.COMMAND_DATA,
 gdb.COMPLETE_NONE)


 def invoke(self, args, from_tty):
 name = str(args)

 frame = Frame.get_selected_python_frame()
 if not frame:
 print('Unable to locate python frame')
 return

 pyop_frame = frame.get_pyop()
 if not pyop_frame:
 print('Unable to read information on python frame')
 return

 pyop_var, scope = pyop_frame.get_var_by_name(name)

 if pyop_var:
 print('%s %r = %s'
 % (scope,
 name,
 pyop_var.get_truncated_repr(MAX_OUTPUT_LEN)))
 else:
 print('%r not found' % name)

PyPrint()

class PyLocals(gdb.Command):
 'Look up the given python variable name, and print it'
 def __init__(self):
 gdb.Command.__init__ (self,
 "py-locals",
 gdb.COMMAND_DATA,
 gdb.COMPLETE_NONE)


 def invoke(self, args, from_tty):
 name = str(args)

 frame = Frame.get_selected_python_frame()
 if not frame:
 print('Unable to locate python frame')
 return

 pyop_frame = frame.get_pyop()
 if not pyop_frame:
 print('Unable to read information on python frame')
 return

 for pyop_name, pyop_value in pyop_frame.iter_locals():
 print('%s = %s'
 % (pyop_name.proxyval(set()),
 pyop_value.get_truncated_repr(MAX_OUTPUT_LEN)))

PyLocals()