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llvm-project/lldb/source/Plugins/LanguageRuntime/ObjC/AppleObjCRuntime/AppleObjCRuntimeV2.cpp

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//===-- AppleObjCRuntimeV2.cpp --------------------------------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include <string>
#include <vector>
#include <memory>
#include <stdint.h>
#include "lldb/lldb-enumerations.h"
#include "lldb/Core/ClangForward.h"
#include "lldb/Symbol/ClangASTType.h"
#include "lldb/Breakpoint/BreakpointLocation.h"
#include "lldb/Core/ClangForward.h"
#include "lldb/Core/ConstString.h"
#include "lldb/Core/Error.h"
#include "lldb/Core/Log.h"
#include "lldb/Core/Module.h"
#include "lldb/Core/PluginManager.h"
#include "lldb/Core/Scalar.h"
#include "lldb/Core/StreamString.h"
#include "lldb/Core/ValueObjectConstResult.h"
#include "lldb/Expression/ClangFunction.h"
#include "lldb/Expression/ClangUtilityFunction.h"
#include "lldb/Symbol/ClangASTContext.h"
#include "lldb/Target/ExecutionContext.h"
#include "lldb/Target/Process.h"
#include "lldb/Target/RegisterContext.h"
#include "lldb/Target/StopInfo.h"
#include "lldb/Target/Target.h"
#include "lldb/Target/Thread.h"
#include "AppleObjCRuntimeV2.h"
#include "AppleObjCTrampolineHandler.h"
#include <vector>
using namespace lldb;
using namespace lldb_private;
static const char *pluginName = "AppleObjCRuntimeV2";
static const char *pluginDesc = "Apple Objective C Language Runtime - Version 2";
static const char *pluginShort = "language.apple.objc.v2";
const char *AppleObjCRuntimeV2::g_find_class_name_function_name = "__lldb_apple_objc_v2_find_class_name";
const char *AppleObjCRuntimeV2::g_find_class_name_function_body = " \n\
extern \"C\" \n\
{ \n\
extern void *gdb_class_getClass (void *objc_class); \n\
extern void *class_getName(void *objc_class); \n\
extern int printf(const char *format, ...); \n\
} \n\
\n\
struct __lldb_objc_object { \n\
void *isa; \n\
}; \n\
\n\
extern \"C\" void *__lldb_apple_objc_v2_find_class_name ( \n\
__lldb_objc_object *object_ptr, \n\
int debug) \n\
{ \n\
void *name = 0; \n\
if (debug) \n\
printf (\"\\n*** Called in v2_find_class_name with object: 0x%p\\n\", object_ptr); \n\
// Call gdb_class_getClass so we can tell if the class is good. \n\
void *objc_class = gdb_class_getClass (object_ptr->isa); \n\
if (objc_class) \n\
{ \n\
void *actual_class = (void *) [(id) object_ptr class]; \n\
if (actual_class != 0) \n\
name = class_getName((void *) actual_class); \n\
if (debug) \n\
printf (\"\\n*** Found name: %s\\n\", name ? name : \"<NOT FOUND>\"); \n\
} \n\
else if (debug) \n\
printf (\"\\n*** gdb_class_getClass returned NULL\\n\"); \n\
return name; \n\
} \n\
";
const char *AppleObjCRuntimeV2::g_objc_class_symbol_prefix = "OBJC_CLASS_$_";
const char *AppleObjCRuntimeV2::g_objc_class_data_section_name = "__objc_data";
AppleObjCRuntimeV2::AppleObjCRuntimeV2 (Process *process, ModuleSP &objc_module_sp) :
lldb_private::AppleObjCRuntime (process),
m_get_class_name_args(LLDB_INVALID_ADDRESS),
m_get_class_name_args_mutex(Mutex::eMutexTypeNormal)
{
m_has_object_getClass = (objc_module_sp->FindFirstSymbolWithNameAndType(ConstString("gdb_object_getClass")) != NULL);
}
bool
AppleObjCRuntimeV2::RunFunctionToFindClassName(lldb::addr_t object_addr, Thread *thread, char *name_dst, size_t max_name_len)
{
// Since we are going to run code we have to make sure only one thread at a time gets to try this.
Mutex::Locker (m_get_class_name_args_mutex);
StreamString errors;
LogSP log(lldb_private::GetLogIfAllCategoriesSet (LIBLLDB_LOG_STEP)); // FIXME - a more appropriate log channel?
int32_t debug;
if (log)
debug = 1;
else
debug = 0;
ValueList dispatch_values;
Value void_ptr_value;
ClangASTContext *clang_ast_context = m_process->GetTarget().GetScratchClangASTContext();
lldb::clang_type_t clang_void_ptr_type = clang_ast_context->GetVoidPtrType(false);
void_ptr_value.SetValueType (Value::eValueTypeScalar);
void_ptr_value.SetContext (Value::eContextTypeClangType, clang_void_ptr_type);
void_ptr_value.GetScalar() = object_addr;
dispatch_values.PushValue (void_ptr_value);
Value int_value;
lldb::clang_type_t clang_int_type = clang_ast_context->GetBuiltinTypeForEncodingAndBitSize(lldb::eEncodingSint, 32);
int_value.SetValueType (Value::eValueTypeScalar);
int_value.SetContext (Value::eContextTypeClangType, clang_int_type);
int_value.GetScalar() = debug;
dispatch_values.PushValue (int_value);
ExecutionContext exe_ctx;
thread->CalculateExecutionContext(exe_ctx);
Address find_class_name_address;
if (!m_get_class_name_code.get())
{
m_get_class_name_code.reset (new ClangUtilityFunction (g_find_class_name_function_body,
g_find_class_name_function_name));
if (!m_get_class_name_code->Install(errors, exe_ctx))
{
if (log)
log->Printf ("Failed to install implementation lookup: %s.", errors.GetData());
m_get_class_name_code.reset();
return false;
}
find_class_name_address.Clear();
find_class_name_address.SetOffset(m_get_class_name_code->StartAddress());
}
else
{
find_class_name_address.Clear();
find_class_name_address.SetOffset(m_get_class_name_code->StartAddress());
}
// Next make the runner function for our implementation utility function.
if (!m_get_class_name_function.get())
{
m_get_class_name_function.reset(new ClangFunction (*m_process,
clang_ast_context,
clang_void_ptr_type,
find_class_name_address,
dispatch_values));
errors.Clear();
unsigned num_errors = m_get_class_name_function->CompileFunction(errors);
if (num_errors)
{
if (log)
log->Printf ("Error compiling function: \"%s\".", errors.GetData());
return false;
}
errors.Clear();
if (!m_get_class_name_function->WriteFunctionWrapper(exe_ctx, errors))
{
if (log)
log->Printf ("Error Inserting function: \"%s\".", errors.GetData());
return false;
}
}
if (m_get_class_name_code.get() == NULL || m_get_class_name_function.get() == NULL)
return false;
// Finally, write down the arguments, and call the function. Note that we will re-use the same space in the target
// for the args. We're locking this to ensure that only one thread at a time gets to call this function, so we don't
// have to worry about overwriting the arguments.
if (!m_get_class_name_function->WriteFunctionArguments (exe_ctx, m_get_class_name_args, find_class_name_address, dispatch_values, errors))
return false;
bool stop_others = true;
bool try_all_threads = true;
bool unwind_on_error = true;
ExecutionResults results = m_get_class_name_function->ExecuteFunction (exe_ctx,
&m_get_class_name_args,
errors,
stop_others,
1000000,
try_all_threads,
unwind_on_error,
void_ptr_value);
if (results != eExecutionCompleted)
{
if (log)
log->Printf("Error evaluating our find class name function: %d.\n", results);
return false;
}
lldb::addr_t result_ptr = void_ptr_value.GetScalar().ULongLong(LLDB_INVALID_ADDRESS);
size_t chars_read = m_process->ReadCStringFromMemory (result_ptr, name_dst, max_name_len);
// If we exhausted our buffer before finding a NULL we're probably off in the weeds somewhere...
if (chars_read == max_name_len)
return false;
else
return true;
}
bool
AppleObjCRuntimeV2::GetDynamicTypeAndAddress (ValueObject &in_value,
lldb::DynamicValueType use_dynamic,
TypeAndOrName &class_type_or_name,
Address &address)
{
// The Runtime is attached to a particular process, you shouldn't pass in a value from another process.
assert (in_value.GetUpdatePoint().GetProcessSP().get() == m_process);
// Make sure we can have a dynamic value before starting...
if (CouldHaveDynamicValue (in_value))
{
// First job, pull out the address at 0 offset from the object That will be the ISA pointer.
AddressType address_type;
lldb::addr_t original_ptr = in_value.GetPointerValue(address_type, true);
// ObjC only has single inheritance, so the objects all start at the same pointer value.
address.SetSection (NULL);
address.SetOffset (original_ptr);
if (original_ptr == LLDB_INVALID_ADDRESS)
return false;
Target *target = m_process->CalculateTarget();
char memory_buffer[16];
DataExtractor data (memory_buffer,
sizeof(memory_buffer),
m_process->GetByteOrder(),
m_process->GetAddressByteSize());
size_t address_byte_size = m_process->GetAddressByteSize();
Error error;
size_t bytes_read = m_process->ReadMemory (original_ptr,
memory_buffer,
address_byte_size,
error);
if (!error.Success() || (bytes_read != address_byte_size))
{
return false;
}
uint32_t offset = 0;
lldb::addr_t isa_addr = data.GetAddress (&offset);
if (offset == 0)
return false;
// Make sure the class address is readable, otherwise this is not a good object:
bytes_read = m_process->ReadMemory (isa_addr,
memory_buffer,
address_byte_size,
error);
if (bytes_read != address_byte_size)
return false;
// First check the cache...
SymbolContext sc;
class_type_or_name = LookupInClassNameCache (isa_addr);
if (!class_type_or_name.IsEmpty())
{
if (class_type_or_name.GetTypeSP() != NULL)
return true;
else
return false;
}
const char *class_name = NULL;
Address isa_address;
target->GetSectionLoadList().ResolveLoadAddress (isa_addr, isa_address);
if (isa_address.IsValid())
{
// If the ISA pointer points to one of the sections in the binary, then see if we can
// get the class name from the symbols.
const Section *section = isa_address.GetSection();
if (section)
{
// If this points to a section that we know about, then this is
// some static class or nothing. See if it is in the right section
// and if its name is the right form.
ConstString section_name = section->GetName();
if (section_name == ConstString(g_objc_class_data_section_name))
{
isa_address.CalculateSymbolContext(&sc);
if (sc.symbol)
{
class_name = sc.symbol->GetName().AsCString();
if (strstr (class_name, g_objc_class_symbol_prefix) == class_name)
class_name += strlen (g_objc_class_symbol_prefix);
else
return false;
}
}
}
}
char class_buffer[1024];
if (class_name == NULL && use_dynamic != lldb::eDynamicDontRunTarget)
{
// If the class address didn't point into the binary, or
// it points into the right section but there wasn't a symbol
// there, try to look it up by calling the class method in the target.
ExecutionContextScope *exe_scope = in_value.GetUpdatePoint().GetExecutionContextScope();
Thread *thread_to_use;
if (exe_scope)
thread_to_use = exe_scope->CalculateThread();
if (thread_to_use == NULL)
thread_to_use = m_process->GetThreadList().GetSelectedThread().get();
if (thread_to_use == NULL)
return false;
if (!RunFunctionToFindClassName (original_ptr, thread_to_use, class_buffer, 1024))
return false;
class_name = class_buffer;
}
if (class_name != NULL && *class_name != '\0')
{
class_type_or_name.SetName (class_name);
TypeList class_types;
uint32_t num_matches = target->GetImages().FindTypes (sc,
class_type_or_name.GetName(),
true,
UINT32_MAX,
class_types);
if (num_matches == 1)
{
class_type_or_name.SetTypeSP (class_types.GetTypeAtIndex(0));
return true;
}
else
{
for (size_t i = 0; i < num_matches; i++)
{
lldb::TypeSP this_type(class_types.GetTypeAtIndex(i));
if (this_type)
{
if (ClangASTContext::IsObjCClassType(this_type->GetClangFullType()))
{
// There can only be one type with a given name,
// so we've just found duplicate definitions, and this
// one will do as well as any other.
// We don't consider something to have a dynamic type if
// it is the same as the static type. So compare against
// the value we were handed:
clang::ASTContext *in_ast_ctx = in_value.GetClangAST ();
clang::ASTContext *this_ast_ctx = this_type->GetClangAST ();
if (in_ast_ctx != this_ast_ctx
|| !ClangASTContext::AreTypesSame (in_ast_ctx,
in_value.GetClangType(),
this_type->GetClangFullType()))
{
class_type_or_name.SetTypeSP (this_type);
}
break;
}
}
}
}
AddToClassNameCache (isa_addr, class_type_or_name);
if (class_type_or_name.GetTypeSP())
return true;
else
return false;
}
}
return false;
}
//------------------------------------------------------------------
// Static Functions
//------------------------------------------------------------------
lldb_private::LanguageRuntime *
AppleObjCRuntimeV2::CreateInstance (Process *process, lldb::LanguageType language)
{
// FIXME: This should be a MacOS or iOS process, and we need to look for the OBJC section to make
// sure we aren't using the V1 runtime.
if (language == eLanguageTypeObjC)
{
ModuleSP objc_module_sp;
if (AppleObjCRuntime::GetObjCVersion (process, objc_module_sp) == eAppleObjC_V2)
return new AppleObjCRuntimeV2 (process, objc_module_sp);
else
return NULL;
}
else
return NULL;
}
void
AppleObjCRuntimeV2::Initialize()
{
PluginManager::RegisterPlugin (pluginName,
pluginDesc,
CreateInstance);
}
void
AppleObjCRuntimeV2::Terminate()
{
PluginManager::UnregisterPlugin (CreateInstance);
}
//------------------------------------------------------------------
// PluginInterface protocol
//------------------------------------------------------------------
const char *
AppleObjCRuntimeV2::GetPluginName()
{
return pluginName;
}
const char *
AppleObjCRuntimeV2::GetShortPluginName()
{
return pluginShort;
}
uint32_t
AppleObjCRuntimeV2::GetPluginVersion()
{
return 1;
}
void
AppleObjCRuntimeV2::SetExceptionBreakpoints ()
{
if (!m_process)
return;
if (!m_objc_exception_bp_sp)
{
m_objc_exception_bp_sp = m_process->GetTarget().CreateBreakpoint (NULL,
"__cxa_throw",
eFunctionNameTypeBase,
true);
}
else
m_objc_exception_bp_sp->SetEnabled (true);
}
ClangUtilityFunction *
AppleObjCRuntimeV2::CreateObjectChecker(const char *name)
{
char check_function_code[1024];
int len = 0;
if (m_has_object_getClass)
{
len = ::snprintf (check_function_code,
sizeof(check_function_code),
"extern \"C\" void *gdb_object_getClass(void *); \n"
"extern \"C\" void \n"
"%s(void *$__lldb_arg_obj) \n"
"{ \n"
" if ($__lldb_arg_obj == (void *)0) \n"
" return; // nil is ok \n"
" if (!gdb_object_getClass($__lldb_arg_obj)) \n"
" *((volatile int *)0) = 'ocgc'; \n"
"} \n",
name);
}
else
{
len = ::snprintf (check_function_code,
sizeof(check_function_code),
"extern \"C\" void *gdb_class_getClass(void *); \n"
"extern \"C\" void \n"
"%s(void *$__lldb_arg_obj) \n"
"{ \n"
" if ($__lldb_arg_obj == (void *)0) \n"
" return; // nil is ok \n"
" void **$isa_ptr = (void **)$__lldb_arg_obj; \n"
" if (*$isa_ptr == (void *)0 || !gdb_class_getClass(*$isa_ptr)) \n"
" *((volatile int *)0) = 'ocgc'; \n"
"} \n",
name);
}
assert (len < sizeof(check_function_code));
return new ClangUtilityFunction(check_function_code, name);
}
size_t
AppleObjCRuntimeV2::GetByteOffsetForIvar (ClangASTType &parent_ast_type, const char *ivar_name)
{
const char *class_name = parent_ast_type.GetConstTypeName().AsCString();
if (!class_name || *class_name == '\0' || !ivar_name || *ivar_name == '\0')
return LLDB_INVALID_IVAR_OFFSET;
std::string buffer("OBJC_IVAR_$_");
buffer.append (class_name);
buffer.push_back ('.');
buffer.append (ivar_name);
ConstString ivar_const_str (buffer.c_str());
SymbolContextList sc_list;
Target *target = &(m_process->GetTarget());
target->GetImages().FindSymbolsWithNameAndType(ivar_const_str, eSymbolTypeRuntime, sc_list);
SymbolContext ivar_offset_symbol;
if (sc_list.GetSize() != 1
|| !sc_list.GetContextAtIndex(0, ivar_offset_symbol)
|| ivar_offset_symbol.symbol == NULL)
return LLDB_INVALID_IVAR_OFFSET;
lldb::addr_t ivar_offset_address = ivar_offset_symbol.symbol->GetValue().GetLoadAddress(target);
Error error;
uint32_t ivar_offset = m_process->ReadUnsignedIntegerFromMemory (ivar_offset_address,
4,
LLDB_INVALID_IVAR_OFFSET,
error);
return ivar_offset;
}
// tagged pointers are marked by having their least-significant bit
// set. this makes them "invalid" as pointers because they violate
// the alignment requirements. this way, we can always know when
// we are dealing with a tagged pointer, and use the lookup approach
// that the runtime would
bool
AppleObjCRuntimeV2::IsTaggedPointer(lldb::addr_t ptr)
{
return (ptr & 0x01);
}
lldb_private::ObjCLanguageRuntime::ObjCISA
AppleObjCRuntimeV2::GetISA(ValueObject& valobj)
{
if (valobj.GetIsExpressionResult() &&
valobj.GetValue().GetValueType() == Value::eValueTypeHostAddress)
{
// when using the expression parser, an additional layer of "frozen data"
// can be created, which is basically a byte-exact copy of the data returned
// by the expression, but in host memory. because Python code might need to read
// into the object memory in non-obvious ways, we need to hand it the target version
// of the expression output
lldb::addr_t tgt_address = valobj.GetValueAsUnsigned();
ValueObjectSP target_object = ValueObjectConstResult::Create (valobj.GetExecutionContextScope(),
valobj.GetClangAST(),
valobj.GetClangType(),
valobj.GetName(),
tgt_address,
eAddressTypeLoad,
valobj.GetUpdatePoint().GetProcessSP()->GetAddressByteSize());
return GetISA(*target_object);
}
if (ClangASTType::GetMinimumLanguage(valobj.GetClangAST(),valobj.GetClangType()) != lldb::eLanguageTypeObjC)
return 0;
// if we get an invalid VO (which might still happen when playing around
// with pointers returned by the expression parser, don't consider this
// a valid ObjC object)
if (valobj.GetValue().GetContextType() == Value::eContextTypeInvalid)
return 0;
uint32_t offset = 0;
uint64_t isa_pointer = valobj.GetDataExtractor().GetPointer(&offset);
// tagged pointer
if (IsTaggedPointer(isa_pointer))
return g_objc_Tagged_ISA;
uint8_t pointer_size = valobj.GetUpdatePoint().GetProcessSP()->GetAddressByteSize();
Error error;
lldb_private::ObjCLanguageRuntime::ObjCISA isa =
valobj.GetUpdatePoint().GetProcessSP()->ReadUnsignedIntegerFromMemory(isa_pointer,
pointer_size,
0,
error);
return isa;
}
// TODO: should we have a transparent_kvo parameter here to say if we
// want to replace the KVO swizzled class with the actual user-level type?
ConstString
AppleObjCRuntimeV2::GetActualTypeName(lldb_private::ObjCLanguageRuntime::ObjCISA isa)
{
if (!IsValidISA(isa))
return ConstString(NULL);
if (isa == g_objc_Tagged_ISA)
return ConstString("_lldb_Tagged_ObjC_ISA");
uint8_t pointer_size = m_process->GetAddressByteSize();
Error error;
lldb::addr_t rw_pointer = isa + (4 * pointer_size);
//printf("rw_pointer: %llx\n", rw_pointer);
uint64_t data_pointer = m_process->ReadUnsignedIntegerFromMemory(rw_pointer,
pointer_size,
0,
error);
if (error.Fail())
return ConstString("unknown");
data_pointer += 8;
//printf("data_pointer: %llx\n", data_pointer);
uint64_t ro_pointer = m_process->ReadUnsignedIntegerFromMemory(data_pointer,
pointer_size,
0,
error);
if (error.Fail())
return ConstString("unknown");
ro_pointer += 12;
if (pointer_size == 8)
ro_pointer += 4;
ro_pointer += pointer_size;
//printf("ro_pointer: %llx\n", ro_pointer);
uint64_t name_pointer = m_process->ReadUnsignedIntegerFromMemory(ro_pointer,
pointer_size,
0,
error);
if (error.Fail())
return ConstString("unknown");
//printf("name_pointer: %llx\n", name_pointer);
char* cstr = new char[512];
if (m_process->ReadCStringFromMemory(name_pointer, cstr, 512) > 0)
{
if (::strstr(cstr, "NSKVONotify") == cstr)
{
// the ObjC runtime implements KVO by replacing the isa with a special
// NSKVONotifying_className that overrides the relevant methods
// the side effect on us is that getting the typename for a KVO-ed object
// will return the swizzled class instead of the actual one
// this swizzled class is a descendant of the real class, so just
// return the parent type and all should be fine
return GetActualTypeName(GetParentClass(isa));
}
else
return ConstString(cstr);
}
else
return ConstString("unknown");
}
lldb_private::ObjCLanguageRuntime::ObjCISA
AppleObjCRuntimeV2::GetParentClass(lldb_private::ObjCLanguageRuntime::ObjCISA isa)
{
if (!IsValidISA(isa))
return 0;
if (isa == g_objc_Tagged_ISA)
return 0;
uint8_t pointer_size = m_process->GetAddressByteSize();
Error error;
lldb::addr_t parent_pointer = isa + pointer_size;
//printf("rw_pointer: %llx\n", rw_pointer);
uint64_t parent_isa = m_process->ReadUnsignedIntegerFromMemory(parent_pointer,
pointer_size,
0,
error);
if (error.Fail())
return 0;
return parent_isa;
}
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