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Showing content from http://svn.python.org/projects/python/branches/import_unicode/Tools/gdb/libpython.py below:

#!/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. ''' from __future__ import with_statement import gdb import locale import sys # Look up the gdb.Type for some standard types: _type_char_ptr = gdb.lookup_type('char').pointer() # char* _type_unsigned_char_ptr = gdb.lookup_type('unsigned char').pointer() # unsigned char* _type_void_ptr = gdb.lookup_type('void').pointer() # void* _type_size_t = gdb.lookup_type('size_t') SIZEOF_VOID_P = _type_void_ptr.sizeof Py_TPFLAGS_HEAPTYPE = (1L << 9) Py_TPFLAGS_LONG_SUBCLASS = (1L << 24) Py_TPFLAGS_LIST_SUBCLASS = (1L << 25) Py_TPFLAGS_TUPLE_SUBCLASS = (1L << 26) Py_TPFLAGS_BYTES_SUBCLASS = (1L << 27) Py_TPFLAGS_UNICODE_SUBCLASS = (1L << 28) Py_TPFLAGS_DICT_SUBCLASS = (1L << 29) Py_TPFLAGS_BASE_EXC_SUBCLASS = (1L << 30) Py_TPFLAGS_TYPE_SUBCLASS = (1L << 31) MAX_OUTPUT_LEN=1024 hexdigits = "0123456789abcdef" ENCODING = locale.getpreferredencoding() class NullPyObjectPtr(RuntimeError): pass def safety_limit(val): # Given a 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(val)) class StringTruncated(RuntimeError): pass class TruncatedStringIO(object): '''Similar to cStringIO, 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 a 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 " ", line 1, in 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, 'instance': PyInstanceObjectPtr, 'NoneType': PyNoneStructPtr, 'frame': PyFrameObjectPtr, 'set' : PySetObjectPtr, 'frozenset' : PySetObjectPtr, 'builtin_function_or_method' : PyCFunctionObjectPtr, } 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 old-style and new-style 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): return ( ( typeobj.field('tp_basicsize') + nitems * typeobj.field('tp_itemsize') + (SIZEOF_VOID_P - 1) ) & ~(SIZEOF_VOID_P - 1) ).cast(_type_size_t) 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 new-style 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() # New-style 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 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 " " % 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 (' ' % (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

 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, analagous to dict.iteritems() ''' for i in safe_range(self.field('ma_mask') + 1): ep = self.field('ma_table') + 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): # 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('}') class PyInstanceObjectPtr(PyObjectPtr): _typename = 'PyInstanceObject' def proxyval(self, visited): # Guard against infinite loops: if self.as_address() in visited: return ProxyAlreadyVisited('<...>') visited.add(self.as_address()) # Get name of class: in_class = self.pyop_field('in_class') cl_name = in_class.pyop_field('cl_name').proxyval(visited) # Get dictionary of instance attributes: in_dict = self.pyop_field('in_dict').proxyval(visited) # Old-style class: return InstanceProxy(cl_name, in_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()) # Old-style class: # Get name of class: in_class = self.pyop_field('in_class') cl_name = in_class.pyop_field('cl_name').proxyval(visited) # Get dictionary of instance attributes: pyop_in_dict = self.pyop_field('in_dict') _write_instance_repr(out, visited, cl_name, pyop_in_dict, self.as_address()) 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 0L ob_digit = self.field('ob_digit') if gdb.lookup_type('digit').sizeof == 2: SHIFT = 15L else: SHIFT = 30L 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 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): 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)' with open(self.filename(), 'r') as 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(')') class PySetObjectPtr(PyObjectPtr): _typename = 'PySetObject' 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 = [] table = self.field('table') for i in safe_range(self.field('mask')+1): setentry = table[i] key = setentry['key'] if key != 0: key_proxy = PyObjectPtr.from_pyobject_ptr(key).proxyval(visited) if key_proxy != ' ': members.append(key_proxy) 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 table = self.field('table') for i in safe_range(self.field('mask')+1): setentry = table[i] key = setentry['key'] if key != 0: pyop_key = PyObjectPtr.from_pyobject_ptr(key) key_proxy = pyop_key.proxyval(visited) # FIXME! if key_proxy != ' ': if not first: out.write(', ') first = False pyop_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)[0] not in ("C", "Z") 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): # From unicodeobject.h: # Py_ssize_t length; /* Length of raw Unicode data in buffer */ # Py_UNICODE *str; /* Raw Unicode buffer */ field_length = long(self.field('length')) field_str = self.field('str') # Gather a list of ints from the Py_UNICODE array; these are either # UCS-2 or UCS-4 code points: Py_UNICODEs = [int(field_str[i]) for i in safe_range(field_length)] # Convert the int code points to unicode characters, and generate a # local unicode instance: result = u''.join([unichr(ucs) 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 orig_ucs = None if self.char_width() == 2: # Get code point from surrogate pair if (i < len(proxy) and 0xD800 <= ord(ch) < 0xDC00 \ and 0xDC00 <= ord(proxy[i]) <= 0xDFFF): ch2 = proxy[i] code = (ord(ch) & 0x03FF) << 10 code |= ord(ch2) & 0x03FF code += 0x00010000 orig_ucs = ucs ucs = unichr(code) i += 1 else: ch2 = None printable = _unichr_is_printable(ucs) if printable: try: ucs.encode(ENCODING) except UnicodeEncodeError: printable = False if orig_ucs is not None: ucs = orig_ucs i -= 1 # Map Unicode whitespace and control characters # (categories Z* and C* except ASCII space) if not printable: # Unfortuately, Python 2's unicode type doesn't seem # to expose the "isprintable" method 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 self.char_width() == 2 and (ch2 is not None): out.write(ch2) out.write(quote) def int_from_int(gdbval): return int(str(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: type = type.target().unqualified() t = str(type) if t in ("PyObject", "PyFrameObject", "PyUnicodeObject"): 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 == 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 def is_evalframeex(self): '''Is this a PyEval_EvalFrameEx frame?''' if self._gdbframe.name() == 'PyEval_EvalFrameEx': ''' 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_EvalFrameEx frame: return True return False def get_pyop(self): try: f = self._gdbframe.read_var('f') return PyFrameObjectPtr.from_pyobject_ptr(f) 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 code in the selected frame, or None''' frame = cls.get_selected_frame() while frame: if frame.is_evalframeex(): return frame frame = frame.older() # Not found: return None def print_summary(self): if self.is_evalframeex(): pyop = self.get_pyop() if pyop: sys.stdout.write('#%i %s\n' % (self.get_index(), pyop.get_truncated_repr(MAX_OUTPUT_LEN))) sys.stdout.write(pyop.current_line()) else: sys.stdout.write('#%i (unable to read python frame information)\n' % self.get_index()) else: sys.stdout.write('#%i\n' % self.get_index()) 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()) frame = Frame.get_selected_python_frame() if not frame: print 'Unable to locate python frame' return pyop = frame.get_pyop() if not pyop: print 'Unable to read information on python frame' return filename = pyop.filename() lineno = pyop.current_line_num() if start is None: start = lineno - 5 end = lineno + 5 if start<1: start = 1 with open(filename, 'r') as 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() while frame: if move_up: iter_frame = frame.older() else: iter_frame = frame.newer() if not iter_frame: break if iter_frame.is_evalframeex(): # 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 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() while frame: if frame.is_evalframeex(): frame.print_summary() 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()

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