""" Objective-C runtime wrapper for use by LLDB Python formatters part of The LLVM Compiler Infrastructure This file is distributed under the University of Illinois Open Source License. See LICENSE.TXT for details. """ 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 ''