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[PseudoObjC] Improve how [super ...] calls are displayed #6903

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[PseudoObjC] Improve how [super ...] calls are displayed #6903

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11 changes: 9 additions & 2 deletions lang/c/pseudoc.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -618,8 +618,11 @@ void PseudoCFunction::GetExprTextInternal(const HighLevelILInstruction& instr, H
needSeparator = hasBlocks;

// Emit the lines for the statement itself
GetExprTextInternal(*i, tokens, settings, TopLevelOperatorPrecedence, true);
tokens.NewLine();
if (!ShouldSkipStatement(*i))
{
GetExprTextInternal(*i, tokens, settings, TopLevelOperatorPrecedence, true);
tokens.NewLine();
}
}
}();
break;
Expand Down Expand Up @@ -2848,6 +2851,10 @@ string PseudoCFunction::GetAnnotationEndString() const
return " */";
}

bool PseudoCFunction::ShouldSkipStatement(const BinaryNinja::HighLevelILInstruction& instr)
{
return false;
}

PseudoCFunctionType::PseudoCFunctionType(): LanguageRepresentationFunctionType("Pseudo C")
{
Expand Down
1 change: 1 addition & 0 deletions lang/c/pseudoc.h
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Expand Up @@ -52,6 +52,7 @@ class PseudoCFunction: public BinaryNinja::LanguageRepresentationFunction
void EndLines(
const BinaryNinja::HighLevelILInstruction& instr, BinaryNinja::HighLevelILTokenEmitter& tokens) override;

virtual bool ShouldSkipStatement(const BinaryNinja::HighLevelILInstruction& instr);
virtual void GetExpr_CALL_OR_TAILCALL(const BinaryNinja::HighLevelILInstruction& instr,
BinaryNinja::HighLevelILTokenEmitter& tokens, BinaryNinja::DisassemblySettings* settings,
BNOperatorPrecedence precedence, bool statement);
Expand Down
86 changes: 78 additions & 8 deletions lang/c/pseudoobjc.cpp
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Expand Up @@ -97,6 +97,17 @@ std::optional<std::pair<uint64_t, Ref<Symbol>>> GetCallTargetInfo(const HighLeve
return std::make_pair(constant, symbol);
}

Ref<Type> TypeResolvingNamedTypeReference(Ref<Type> type, const Function& function)
{
if (!type || !type->IsNamedTypeRefer())
return type;

if (auto resolvedType = function.GetView()->GetTypeByRef(type->GetNamedTypeReference()))
return resolvedType;

return type;
}

struct RuntimeCall
{
enum Type
Expand Down Expand Up @@ -187,6 +198,42 @@ std::optional<RuntimeCall> DetectRewrittenDirectObjCMethodCall(const HighLevelIL
return RuntimeCall {RuntimeCall::MessageSend, constant, true};
}

bool VariableIsObjCSuperStruct(const Variable& variable, Function& function)
{
auto variableName = function.GetVariableName(variable);
if (variableName != "super")
return false;

const auto variableType = TypeResolvingNamedTypeReference(function.GetVariableType(variable), function);
if (!variableType || variableType->GetClass() != StructureTypeClass)
return false;

if (variableType->GetStructureName().GetString() != "objc_super")
return false;

return true;
}

bool IsAssignmentToObjCSuperStructField(const HighLevelILInstruction& assignInstr, Function& function)
{
// Check if this is an assignment to a field of the objc_super struct
// Pattern: HLIL_ASSIGN { dest = HLIL_STRUCT_FIELD { source = HLIL_VAR { super }, }, field = ... }

if (assignInstr.operation != HLIL_ASSIGN)
return false;

const auto destExpr = assignInstr.GetDestExpr();
if (destExpr.operation != HLIL_STRUCT_FIELD)
return false;

const auto sourceExpr = destExpr.GetSourceExpr();
if (sourceExpr.operation != HLIL_VAR)
return false;

auto variable = sourceExpr.GetVariable<HLIL_VAR>();
return VariableIsObjCSuperStruct(variable, function);
}

} // unnamed namespace

PseudoObjCFunction::PseudoObjCFunction(LanguageRepresentationFunctionType* type, Architecture* arch, Function* owner,
Expand All @@ -212,7 +259,8 @@ void PseudoObjCFunction::GetExpr_CALL_OR_TAILCALL(const BinaryNinja::HighLevelIL
{
case RuntimeCall::MessageSend:
case RuntimeCall::MessageSendSuper:
if (GetExpr_ObjCMsgSend(objCRuntimeCall->address, objCRuntimeCall->isRewritten, destExpr, tokens, settings, parameterExprs))
if (GetExpr_ObjCMsgSend(objCRuntimeCall->address, objCRuntimeCall->type == RuntimeCall::MessageSendSuper,
objCRuntimeCall->isRewritten, destExpr, tokens, settings, parameterExprs))
{
if (statement)
tokens.AppendSemicolon();
Expand Down Expand Up @@ -259,7 +307,7 @@ void PseudoObjCFunction::GetExpr_CALL_OR_TAILCALL(const BinaryNinja::HighLevelIL
return PseudoCFunction::GetExpr_CALL_OR_TAILCALL(instr, tokens, settings, precedence, statement);
}

bool PseudoObjCFunction::GetExpr_ObjCMsgSend(uint64_t msgSendAddress, bool isRewritten,
bool PseudoObjCFunction::GetExpr_ObjCMsgSend(uint64_t msgSendAddress, bool isSuper, bool isRewritten,
const HighLevelILInstruction& instr, HighLevelILTokenEmitter& tokens, DisassemblySettings* settings,
const std::vector<HighLevelILInstruction>& parameterExprs)
{
Expand All @@ -278,7 +326,10 @@ bool PseudoObjCFunction::GetExpr_ObjCMsgSend(uint64_t msgSendAddress, bool isRew

tokens.AppendOpenBracket();

GetExprText(parameterExprs[0], tokens, settings);
if (isSuper)
tokens.Append(LocalVariableToken, "super", instr.address);
else
GetExprText(parameterExprs[0], tokens, settings);

for (size_t index = 2; index < parameterExprs.size(); index++)
{
Expand Down Expand Up @@ -355,10 +406,7 @@ void PseudoObjCFunction::GetExpr_CONST_PTR(const BinaryNinja::HighLevelILInstruc
if (!hasVariable)
return PseudoCFunction::GetExpr_CONST_PTR(instr, tokens, settings, precedence, statement);

auto type = variable.type->IsNamedTypeRefer() ?
GetFunction()->GetView()->GetTypeByRef(variable.type->GetNamedTypeReference()) :
variable.type.GetValue();

auto type = TypeResolvingNamedTypeReference(variable.type, *GetFunction());
if (!type || type->GetClass() != StructureTypeClass)
return PseudoCFunction::GetExpr_CONST_PTR(instr, tokens, settings, precedence, statement);

Expand Down Expand Up @@ -427,7 +475,7 @@ void PseudoObjCFunction::GetExpr_IMPORT(const BinaryNinja::HighLevelILInstructio
BNOperatorPrecedence precedence, bool statement)
{
const auto constant = instr.GetConstant<HLIL_IMPORT>();
auto symbol = GetHighLevelILFunction()->GetFunction()->GetView()->GetSymbolByAddress(constant);
auto symbol = GetFunction()->GetView()->GetSymbolByAddress(constant);
const auto symbolType = symbol->GetType();

if (symbol && (symbolType == ImportedDataSymbol || symbolType == ImportAddressSymbol))
Expand All @@ -449,6 +497,28 @@ void PseudoObjCFunction::GetExpr_IMPORT(const BinaryNinja::HighLevelILInstructio
PseudoCFunction::GetExpr_IMPORT(instr, tokens, settings, precedence, statement);
}

bool PseudoObjCFunction::ShouldSkipStatement(const BinaryNinja::HighLevelILInstruction& instr)
{
// Skip statements that are compiler-generated artifacts of Objective-C runtime calls
// For now this is limited to the declaration / initialization of the `objc_super` variable
// used for `objc_msgSendSuper` calls.
switch (instr.operation)
{
case HLIL_VAR_DECLARE:
if (VariableIsObjCSuperStruct(instr.GetVariable<HLIL_VAR_DECLARE>(), *GetFunction()))
return true;
break;
case HLIL_ASSIGN:
if (IsAssignmentToObjCSuperStructField(instr, *GetFunction()))
return true;
break;
default:
break;
}

return PseudoCFunction::ShouldSkipStatement(instr);
}


PseudoObjCFunctionType::PseudoObjCFunctionType() : PseudoCFunctionType("Pseudo Objective-C") {}

Expand Down
4 changes: 3 additions & 1 deletion lang/c/pseudoobjc.h
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Original file line number Diff line number Diff line change
Expand Up @@ -21,8 +21,10 @@ class PseudoObjCFunction : public PseudoCFunction
BinaryNinja::HighLevelILTokenEmitter& tokens, BinaryNinja::DisassemblySettings* settings,
BNOperatorPrecedence precedence, bool statement) override;

bool ShouldSkipStatement(const BinaryNinja::HighLevelILInstruction& instr) override;

private:
bool GetExpr_ObjCMsgSend(uint64_t msgSendAddress, bool isRewritten, const BinaryNinja::HighLevelILInstruction& expr,
bool GetExpr_ObjCMsgSend(uint64_t msgSendAddress, bool isSuper, bool isRewritten, const BinaryNinja::HighLevelILInstruction& expr,
BinaryNinja::HighLevelILTokenEmitter& tokens, BinaryNinja::DisassemblySettings* settings,
const std::vector<BinaryNinja::HighLevelILInstruction>& parameterExprs);
bool GetExpr_GenericObjCRuntimeCall(uint64_t address, const BinaryNinja::HighLevelILInstruction& expr,
Expand Down