""" Objective-C runtime wrapper for use by LLDB Python formatters Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. See https://llvm.org/LICENSE.txt for license information. SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception """ import lldb import lldb.formatters.cache import lldb.formatters.attrib_fromdict import functools import lldb.formatters.Logger class Utilities: @staticmethod def read_ascii(process, pointer, max_len=128): logger = lldb.formatters.Logger.Logger() error = lldb.SBError() content = None try: content = process.ReadCStringFromMemory(pointer, max_len, error) except: pass if content is None or len(content) == 0 or error.fail: return None return content @staticmethod def is_valid_pointer(pointer, pointer_size, allow_tagged=0, allow_NULL=0): logger = lldb.formatters.Logger.Logger() if pointer is None: return 0 if pointer == 0: return allow_NULL if allow_tagged and (pointer % 2) == 1: return 1 return ((pointer % pointer_size) == 0) # Objective-C runtime has a rule that pointers in a class_t will only have bits 0 thru 46 set # so if any pointer has bits 47 thru 63 high we know that this is not a # valid isa @staticmethod def is_allowed_pointer(pointer): logger = lldb.formatters.Logger.Logger() if pointer is None: return 0 return ((pointer & 0xFFFF800000000000) == 0) @staticmethod def read_child_of(valobj, offset, type): logger = lldb.formatters.Logger.Logger() if offset == 0 and type.GetByteSize() == valobj.GetByteSize(): return valobj.GetValueAsUnsigned() child = valobj.CreateChildAtOffset("childUNK", offset, type) if child is None or child.IsValid() == 0: return None return child.GetValueAsUnsigned() @staticmethod def is_valid_identifier(name): logger = lldb.formatters.Logger.Logger() if name is None: return None if len(name) == 0: return None # technically, the ObjC runtime does not enforce any rules about what name a class can have # in practice, the commonly used byte values for a class name are the letters, digits and some # symbols: $, %, -, _, . # WARNING: this means that you cannot use this runtime implementation if you need to deal # with class names that use anything but what is allowed here ok_values = dict.fromkeys( "$%_.-ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz1234567890") return all(c in ok_values for c in name) @staticmethod def check_is_osx_lion(target): logger = lldb.formatters.Logger.Logger() # assume the only thing that has a Foundation.framework is a Mac # assume anything < Lion does not even exist try: mod = target.module['Foundation'] except: mod = None if mod is None or mod.IsValid() == 0: return None ver = mod.GetVersion() if ver is None or ver == []: return None return (ver[0] < 900) # a utility method that factors out code common to almost all the formatters # takes in an SBValue and a metrics object # returns a class_data and a wrapper (or None, if the runtime alone can't # decide on a wrapper) @staticmethod def prepare_class_detection(valobj, statistics): logger = lldb.formatters.Logger.Logger() class_data = ObjCRuntime(valobj) if class_data.is_valid() == 0: statistics.metric_hit('invalid_pointer', valobj) wrapper = InvalidPointer_Description( valobj.GetValueAsUnsigned(0) == 0) return class_data, wrapper class_data = class_data.read_class_data() if class_data.is_valid() == 0: statistics.metric_hit('invalid_isa', valobj) wrapper = InvalidISA_Description() return class_data, wrapper if class_data.is_kvo(): class_data = class_data.get_superclass() if class_data.class_name() == '_NSZombie_OriginalClass': wrapper = ThisIsZombie_Description() return class_data, wrapper return class_data, None class RoT_Data: def __init__(self, rot_pointer, params): logger = lldb.formatters.Logger.Logger() if (Utilities.is_valid_pointer(rot_pointer.GetValueAsUnsigned(), params.pointer_size, allow_tagged=0)): self.sys_params = params self.valobj = rot_pointer #self.flags = Utilities.read_child_of(self.valobj,0,self.sys_params.uint32_t) #self.instanceStart = Utilities.read_child_of(self.valobj,4,self.sys_params.uint32_t) self.instanceSize = None # lazy fetching offset = 24 if self.sys_params.is_64_bit else 16 #self.ivarLayoutPtr = Utilities.read_child_of(self.valobj,offset,self.sys_params.addr_ptr_type) self.namePointer = Utilities.read_child_of( self.valobj, offset, self.sys_params.types_cache.addr_ptr_type) self.valid = 1 # self.check_valid() else: logger >> "Marking as invalid - rot is invalid" self.valid = 0 if self.valid: self.name = Utilities.read_ascii( self.valobj.GetTarget().GetProcess(), self.namePointer) if not(Utilities.is_valid_identifier(self.name)): logger >> "Marking as invalid - name is invalid" self.valid = 0 # perform sanity checks on the contents of this class_ro_t def check_valid(self): self.valid = 1 # misaligned pointers seem to be possible for this field # if not(Utilities.is_valid_pointer(self.namePointer,self.sys_params.pointer_size,allow_tagged=0)): # self.valid = 0 # pass def __str__(self): logger = lldb.formatters.Logger.Logger() return \ "instanceSize = " + hex(self.instance_size()) + "\n" + \ "namePointer = " + hex(self.namePointer) + " --> " + self.name def is_valid(self): return self.valid def instance_size(self, align=0): logger = lldb.formatters.Logger.Logger() if self.is_valid() == 0: return None if self.instanceSize is None: self.instanceSize = Utilities.read_child_of( self.valobj, 8, self.sys_params.types_cache.uint32_t) if align: unalign = self.instance_size(0) if self.sys_params.is_64_bit: return ((unalign + 7) & ~7) % 0x100000000 else: return ((unalign + 3) & ~3) % 0x100000000 else: return self.instanceSize class RwT_Data: def __init__(self, rwt_pointer, params): logger = lldb.formatters.Logger.Logger() if (Utilities.is_valid_pointer(rwt_pointer.GetValueAsUnsigned(), params.pointer_size, allow_tagged=0)): self.sys_params = params self.valobj = rwt_pointer #self.flags = Utilities.read_child_of(self.valobj,0,self.sys_params.uint32_t) #self.version = Utilities.read_child_of(self.valobj,4,self.sys_params.uint32_t) self.roPointer = Utilities.read_child_of( self.valobj, 8, self.sys_params.types_cache.addr_ptr_type) self.check_valid() else: logger >> "Marking as invalid - rwt is invald" self.valid = 0 if self.valid: self.rot = self.valobj.CreateValueFromData( "rot", lldb.SBData.CreateDataFromUInt64Array( self.sys_params.endianness, self.sys_params.pointer_size, [ self.roPointer]), self.sys_params.types_cache.addr_ptr_type) # self.rot = self.valobj.CreateValueFromAddress("rot",self.roPointer,self.sys_params.types_cache.addr_ptr_type).AddressOf() self.data = RoT_Data(self.rot, self.sys_params) # perform sanity checks on the contents of this class_rw_t def check_valid(self): logger = lldb.formatters.Logger.Logger() self.valid = 1 if not( Utilities.is_valid_pointer( self.roPointer, self.sys_params.pointer_size, allow_tagged=0)): logger >> "Marking as invalid - ropointer is invalid" self.valid = 0 def __str__(self): logger = lldb.formatters.Logger.Logger() return \ "roPointer = " + hex(self.roPointer) def is_valid(self): logger = lldb.formatters.Logger.Logger() if self.valid: return self.data.is_valid() return 0 class Class_Data_V2: def __init__(self, isa_pointer, params): logger = lldb.formatters.Logger.Logger() if (isa_pointer is not None) and (Utilities.is_valid_pointer( isa_pointer.GetValueAsUnsigned(), params.pointer_size, allow_tagged=0)): self.sys_params = params self.valobj = isa_pointer self.check_valid() else: logger >> "Marking as invalid - isa is invalid or None" self.valid = 0 if self.valid: self.rwt = self.valobj.CreateValueFromData( "rwt", lldb.SBData.CreateDataFromUInt64Array( self.sys_params.endianness, self.sys_params.pointer_size, [ self.dataPointer]), self.sys_params.types_cache.addr_ptr_type) # self.rwt = self.valobj.CreateValueFromAddress("rwt",self.dataPointer,self.sys_params.types_cache.addr_ptr_type).AddressOf() self.data = RwT_Data(self.rwt, self.sys_params) # perform sanity checks on the contents of this class_t # this call tries to minimize the amount of data fetched- as soon as we have "proven" # that we have an invalid object, we stop reading def check_valid(self): logger = lldb.formatters.Logger.Logger() self.valid = 1 self.isaPointer = Utilities.read_child_of( self.valobj, 0, self.sys_params.types_cache.addr_ptr_type) if not( Utilities.is_valid_pointer( self.isaPointer, self.sys_params.pointer_size, allow_tagged=0)): logger >> "Marking as invalid - isaPointer is invalid" self.valid = 0 return if not(Utilities.is_allowed_pointer(self.isaPointer)): logger >> "Marking as invalid - isaPointer is not allowed" self.valid = 0 return self.cachePointer = Utilities.read_child_of( self.valobj, 2 * self.sys_params.pointer_size, self.sys_params.types_cache.addr_ptr_type) if not( Utilities.is_valid_pointer( self.cachePointer, self.sys_params.pointer_size, allow_tagged=0)): logger >> "Marking as invalid - cachePointer is invalid" self.valid = 0 return if not(Utilities.is_allowed_pointer(self.cachePointer)): logger >> "Marking as invalid - cachePointer is not allowed" self.valid = 0 return self.dataPointer = Utilities.read_child_of( self.valobj, 4 * self.sys_params.pointer_size, self.sys_params.types_cache.addr_ptr_type) if not( Utilities.is_valid_pointer( self.dataPointer, self.sys_params.pointer_size, allow_tagged=0)): logger >> "Marking as invalid - dataPointer is invalid" self.valid = 0 return if not(Utilities.is_allowed_pointer(self.dataPointer)): logger >> "Marking as invalid - dataPointer is not allowed" self.valid = 0 return self.superclassIsaPointer = Utilities.read_child_of( self.valobj, 1 * self.sys_params.pointer_size, self.sys_params.types_cache.addr_ptr_type) if not( Utilities.is_valid_pointer( self.superclassIsaPointer, self.sys_params.pointer_size, allow_tagged=0, allow_NULL=1)): logger >> "Marking as invalid - superclassIsa is invalid" self.valid = 0 return if not(Utilities.is_allowed_pointer(self.superclassIsaPointer)): logger >> "Marking as invalid - superclassIsa is not allowed" self.valid = 0 return # in general, KVO is implemented by transparently subclassing # however, there could be exceptions where a class does something else # internally to implement the feature - this method will have no clue that a class # has been KVO'ed unless the standard implementation technique is used def is_kvo(self): logger = lldb.formatters.Logger.Logger() if self.is_valid(): if self.class_name().startswith("NSKVONotifying_"): return 1 return 0 # some CF classes have a valid ObjC isa in their CFRuntimeBase # but instead of being class-specific this isa points to a match-'em-all class # which is __NSCFType (the versions without __ also exists and we are matching to it # just to be on the safe side) def is_cftype(self): logger = lldb.formatters.Logger.Logger() if self.is_valid(): return self.class_name() == '__NSCFType' or self.class_name() == 'NSCFType' def get_superclass(self): logger = lldb.formatters.Logger.Logger() if self.is_valid(): parent_isa_pointer = self.valobj.CreateChildAtOffset( "parent_isa", self.sys_params.pointer_size, self.sys_params.addr_ptr_type) return Class_Data_V2(parent_isa_pointer, self.sys_params) else: return None def class_name(self): logger = lldb.formatters.Logger.Logger() if self.is_valid(): return self.data.data.name else: return None def is_valid(self): logger = lldb.formatters.Logger.Logger() if self.valid: return self.data.is_valid() return 0 def __str__(self): logger = lldb.formatters.Logger.Logger() return 'isaPointer = ' + hex(self.isaPointer) + "\n" + \ "superclassIsaPointer = " + hex(self.superclassIsaPointer) + "\n" + \ "cachePointer = " + hex(self.cachePointer) + "\n" + \ "data = " + hex(self.dataPointer) def is_tagged(self): return 0 def instance_size(self, align=0): logger = lldb.formatters.Logger.Logger() if self.is_valid() == 0: return None return self.rwt.rot.instance_size(align) # runtime v1 is much less intricate than v2 and stores relevant # information directly in the class_t object class Class_Data_V1: def __init__(self, isa_pointer, params): logger = lldb.formatters.Logger.Logger() if (isa_pointer is not None) and (Utilities.is_valid_pointer( isa_pointer.GetValueAsUnsigned(), params.pointer_size, allow_tagged=0)): self.valid = 1 self.sys_params = params self.valobj = isa_pointer self.check_valid() else: logger >> "Marking as invalid - isaPointer is invalid or None" self.valid = 0 if self.valid: self.name = Utilities.read_ascii( self.valobj.GetTarget().GetProcess(), self.namePointer) if not(Utilities.is_valid_identifier(self.name)): logger >> "Marking as invalid - name is not valid" self.valid = 0 # perform sanity checks on the contents of this class_t def check_valid(self): logger = lldb.formatters.Logger.Logger() self.valid = 1 self.isaPointer = Utilities.read_child_of( self.valobj, 0, self.sys_params.types_cache.addr_ptr_type) if not( Utilities.is_valid_pointer( self.isaPointer, self.sys_params.pointer_size, allow_tagged=0)): logger >> "Marking as invalid - isaPointer is invalid" self.valid = 0 return self.superclassIsaPointer = Utilities.read_child_of( self.valobj, 1 * self.sys_params.pointer_size, self.sys_params.types_cache.addr_ptr_type) if not( Utilities.is_valid_pointer( self.superclassIsaPointer, self.sys_params.pointer_size, allow_tagged=0, allow_NULL=1)): logger >> "Marking as invalid - superclassIsa is invalid" self.valid = 0 return self.namePointer = Utilities.read_child_of( self.valobj, 2 * self.sys_params.pointer_size, self.sys_params.types_cache.addr_ptr_type) # if not(Utilities.is_valid_pointer(self.namePointer,self.sys_params.pointer_size,allow_tagged=0,allow_NULL=0)): # self.valid = 0 # return # in general, KVO is implemented by transparently subclassing # however, there could be exceptions where a class does something else # internally to implement the feature - this method will have no clue that a class # has been KVO'ed unless the standard implementation technique is used def is_kvo(self): logger = lldb.formatters.Logger.Logger() if self.is_valid(): if self.class_name().startswith("NSKVONotifying_"): return 1 return 0 # some CF classes have a valid ObjC isa in their CFRuntimeBase # but instead of being class-specific this isa points to a match-'em-all class # which is __NSCFType (the versions without __ also exists and we are matching to it # just to be on the safe side) def is_cftype(self): logger = lldb.formatters.Logger.Logger() if self.is_valid(): return self.class_name() == '__NSCFType' or self.class_name() == 'NSCFType' def get_superclass(self): logger = lldb.formatters.Logger.Logger() if self.is_valid(): parent_isa_pointer = self.valobj.CreateChildAtOffset( "parent_isa", self.sys_params.pointer_size, self.sys_params.addr_ptr_type) return Class_Data_V1(parent_isa_pointer, self.sys_params) else: return None def class_name(self): logger = lldb.formatters.Logger.Logger() if self.is_valid(): return self.name else: return None def is_valid(self): return self.valid def __str__(self): logger = lldb.formatters.Logger.Logger() return 'isaPointer = ' + hex(self.isaPointer) + "\n" + \ "superclassIsaPointer = " + hex(self.superclassIsaPointer) + "\n" + \ "namePointer = " + hex(self.namePointer) + " --> " + self.name + \ "instanceSize = " + hex(self.instanceSize()) + "\n" def is_tagged(self): return 0 def instance_size(self, align=0): logger = lldb.formatters.Logger.Logger() if self.is_valid() == 0: return None if self.instanceSize is None: self.instanceSize = Utilities.read_child_of( self.valobj, 5 * self.sys_params.pointer_size, self.sys_params.types_cache.addr_ptr_type) if align: unalign = self.instance_size(0) if self.sys_params.is_64_bit: return ((unalign + 7) & ~7) % 0x100000000 else: return ((unalign + 3) & ~3) % 0x100000000 else: return self.instanceSize # these are the only tagged pointers values for current versions # of OSX - they might change in future OS releases, and no-one is # advised to rely on these values, or any of the bitmasking formulas # in TaggedClass_Data. doing otherwise is at your own risk TaggedClass_Values_Lion = {1: 'NSNumber', 5: 'NSManagedObject', 6: 'NSDate', 7: 'NSDateTS'} TaggedClass_Values_NMOS = {0: 'NSAtom', 3: 'NSNumber', 4: 'NSDateTS', 5: 'NSManagedObject', 6: 'NSDate'} class TaggedClass_Data: def __init__(self, pointer, params): logger = lldb.formatters.Logger.Logger() global TaggedClass_Values_Lion, TaggedClass_Values_NMOS self.valid = 1 self.name = None self.sys_params = params self.valobj = pointer self.val = (pointer & ~0x0000000000000000FF) >> 8 self.class_bits = (pointer & 0xE) >> 1 self.i_bits = (pointer & 0xF0) >> 4 if self.sys_params.is_lion: if self.class_bits in TaggedClass_Values_Lion: self.name = TaggedClass_Values_Lion[self.class_bits] else: logger >> "Marking as invalid - not a good tagged pointer for Lion" self.valid = 0 else: if self.class_bits in TaggedClass_Values_NMOS: self.name = TaggedClass_Values_NMOS[self.class_bits] else: logger >> "Marking as invalid - not a good tagged pointer for NMOS" self.valid = 0 def is_valid(self): return self.valid def class_name(self): logger = lldb.formatters.Logger.Logger() if self.is_valid(): return self.name else: return 0 def value(self): return self.val if self.is_valid() else None def info_bits(self): return self.i_bits if self.is_valid() else None def is_kvo(self): return 0 def is_cftype(self): return 0 # we would need to go around looking for the superclass or ask the runtime # for now, we seem not to require support for this operation so we will merrily # pretend to be at a root point in the hierarchy def get_superclass(self): return None # anything that is handled here is tagged def is_tagged(self): return 1 # it seems reasonable to say that a tagged pointer is the size of a pointer def instance_size(self, align=0): logger = lldb.formatters.Logger.Logger() if self.is_valid() == 0: return None return self.sys_params.pointer_size class InvalidClass_Data: def __init__(self): pass def is_valid(self): return 0 class Version: def __init__(self, major, minor, release, build_string): self._major = major self._minor = minor self._release = release self._build_string = build_string def get_major(self): return self._major def get_minor(self): return self._minor def get_release(self): return self._release def get_build_string(self): return self._build_string major = property(get_major, None) minor = property(get_minor, None) release = property(get_release, None) build_string = property(get_build_string, None) def __lt__(self, other): if (self.major < other.major): return 1 if (self.minor < other.minor): return 1 if (self.release < other.release): return 1 # build strings are not compared since they are heavily platform-dependent and might not always # be available return 0 def __eq__(self, other): return (self.major == other.major) and \ (self.minor == other.minor) and \ (self.release == other.release) and \ (self.build_string == other.build_string) # Python 2.6 doesn't have functools.total_ordering, so we have to implement # other comparators def __gt__(self, other): return other < self def __le__(self, other): return not other < self def __ge__(self, other): return not self < other runtime_version = lldb.formatters.cache.Cache() os_version = lldb.formatters.cache.Cache() types_caches = lldb.formatters.cache.Cache() isa_caches = lldb.formatters.cache.Cache() class SystemParameters: def __init__(self, valobj): logger = lldb.formatters.Logger.Logger() self.adjust_for_architecture(valobj) self.adjust_for_process(valobj) def adjust_for_process(self, valobj): logger = lldb.formatters.Logger.Logger() global runtime_version global os_version global types_caches global isa_caches process = valobj.GetTarget().GetProcess() # using the unique ID for added guarantees (see svn revision 172628 for # further details) self.pid = process.GetUniqueID() if runtime_version.look_for_key(self.pid): self.runtime_version = runtime_version.get_value(self.pid) else: self.runtime_version = ObjCRuntime.runtime_version(process) runtime_version.add_item(self.pid, self.runtime_version) if os_version.look_for_key(self.pid): self.is_lion = os_version.get_value(self.pid) else: self.is_lion = Utilities.check_is_osx_lion(valobj.GetTarget()) os_version.add_item(self.pid, self.is_lion) if types_caches.look_for_key(self.pid): self.types_cache = types_caches.get_value(self.pid) else: self.types_cache = lldb.formatters.attrib_fromdict.AttributesDictionary( allow_reset=0) self.types_cache.addr_type = valobj.GetType( ).GetBasicType(lldb.eBasicTypeUnsignedLong) self.types_cache.addr_ptr_type = self.types_cache.addr_type.GetPointerType() self.types_cache.uint32_t = valobj.GetType( ).GetBasicType(lldb.eBasicTypeUnsignedInt) types_caches.add_item(self.pid, self.types_cache) if isa_caches.look_for_key(self.pid): self.isa_cache = isa_caches.get_value(self.pid) else: self.isa_cache = lldb.formatters.cache.Cache() isa_caches.add_item(self.pid, self.isa_cache) def adjust_for_architecture(self, valobj): process = valobj.GetTarget().GetProcess() self.pointer_size = process.GetAddressByteSize() self.is_64_bit = (self.pointer_size == 8) self.endianness = process.GetByteOrder() self.is_little = (self.endianness == lldb.eByteOrderLittle) self.cfruntime_size = 16 if self.is_64_bit else 8 # a simple helper function that makes it more explicit that one is calculating # an offset that is made up of X pointers and Y bytes of additional data # taking into account pointer size - if you know there is going to be some padding # you can pass that in and it will be taken into account (since padding may be different between # 32 and 64 bit versions, you can pass padding value for both, the right # one will be used) def calculate_offset( self, num_pointers=0, bytes_count=0, padding32=0, padding64=0): value = bytes_count + num_pointers * self.pointer_size return value + padding64 if self.is_64_bit else value + padding32 class ObjCRuntime: # the ObjC runtime has no explicit "version" field that we can use # instead, we discriminate v1 from v2 by looking for the presence # of a well-known section only present in v1 @staticmethod def runtime_version(process): logger = lldb.formatters.Logger.Logger() if process.IsValid() == 0: logger >> "No process - bailing out" return None target = process.GetTarget() num_modules = target.GetNumModules() module_objc = None for idx in range(num_modules): module = target.GetModuleAtIndex(idx) if module.GetFileSpec().GetFilename() == 'libobjc.A.dylib': module_objc = module break if module_objc is None or module_objc.IsValid() == 0: logger >> "no libobjc - bailing out" return None num_sections = module.GetNumSections() section_objc = None for idx in range(num_sections): section = module.GetSectionAtIndex(idx) if section.GetName() == '__OBJC': section_objc = section break if section_objc is not None and section_objc.IsValid(): logger >> "found __OBJC: v1" return 1 logger >> "no __OBJC: v2" return 2 @staticmethod def runtime_from_isa(isa): logger = lldb.formatters.Logger.Logger() runtime = ObjCRuntime(isa) runtime.isa = isa return runtime def __init__(self, valobj): logger = lldb.formatters.Logger.Logger() self.valobj = valobj self.adjust_for_architecture() self.sys_params = SystemParameters(self.valobj) self.unsigned_value = self.valobj.GetValueAsUnsigned() self.isa_value = None def adjust_for_architecture(self): pass # an ObjC pointer can either be tagged or must be aligned def is_tagged(self): logger = lldb.formatters.Logger.Logger() if self.valobj is None: return 0 return ( Utilities.is_valid_pointer( self.unsigned_value, self.sys_params.pointer_size, allow_tagged=1) and not( Utilities.is_valid_pointer( self.unsigned_value, self.sys_params.pointer_size, allow_tagged=0))) def is_valid(self): logger = lldb.formatters.Logger.Logger() if self.valobj is None: return 0 if self.valobj.IsInScope() == 0: return 0 return Utilities.is_valid_pointer( self.unsigned_value, self.sys_params.pointer_size, allow_tagged=1) def is_nil(self): return self.unsigned_value == 0 def read_isa(self): logger = lldb.formatters.Logger.Logger() if self.isa_value is not None: logger >> "using cached isa" return self.isa_value self.isa_pointer = self.valobj.CreateChildAtOffset( "cfisa", 0, self.sys_params.types_cache.addr_ptr_type) if self.isa_pointer is None or self.isa_pointer.IsValid() == 0: logger >> "invalid isa - bailing out" return None self.isa_value = self.isa_pointer.GetValueAsUnsigned(1) if self.isa_value == 1: logger >> "invalid isa value - bailing out" return None return Ellipsis def read_class_data(self): logger = lldb.formatters.Logger.Logger() global isa_cache if self.is_tagged(): # tagged pointers only exist in ObjC v2 if self.sys_params.runtime_version == 2: logger >> "on v2 and tagged - maybe" # not every odd-valued pointer is actually tagged. most are just plain wrong # we could try and predetect this before even creating a TaggedClass_Data object # but unless performance requires it, this seems a cleaner way # to tackle the task tentative_tagged = TaggedClass_Data( self.unsigned_value, self.sys_params) if tentative_tagged.is_valid(): logger >> "truly tagged" return tentative_tagged else: logger >> "not tagged - error" return InvalidClass_Data() else: logger >> "on v1 and tagged - error" return InvalidClass_Data() if self.is_valid() == 0 or self.read_isa() is None: return InvalidClass_Data() data = self.sys_params.isa_cache.get_value( self.isa_value, default=None) if data is not None: return data if self.sys_params.runtime_version == 2: data = Class_Data_V2(self.isa_pointer, self.sys_params) else: data = Class_Data_V1(self.isa_pointer, self.sys_params) if data is None: return InvalidClass_Data() if data.is_valid(): self.sys_params.isa_cache.add_item( self.isa_value, data, ok_to_replace=1) return data # these classes below can be used by the data formatters to provide a # consistent message that describes a given runtime-generated situation class SpecialSituation_Description: def message(self): return '' class InvalidPointer_Description(SpecialSituation_Description): def __init__(self, nil): self.is_nil = nil def message(self): if self.is_nil: return '@""' else: return '' class InvalidISA_Description(SpecialSituation_Description): def __init__(self): pass def message(self): return '' class ThisIsZombie_Description(SpecialSituation_Description): def message(self): return ''