/* This file is part of cpp-ethereum. cpp-ethereum is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. cpp-ethereum is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with cpp-ethereum. If not, see . */ /** * @author Christian * @date 2015 * Component that translates Solidity code into the why3 programming language. */ #include #include using namespace std; using namespace dev; using namespace dev::solidity; bool Why3Translator::process(SourceUnit const& _source) { try { if (m_lines.size() != 1 || !m_lines.back().contents.empty()) fatalError(_source, "Multiple source units not yet supported"); appendPreface(); _source.accept(*this); } catch (NoFormalType&) { solAssert(false, "There is a call to toFormalType() that does not catch NoFormalType exceptions."); } catch (FatalError& /*_e*/) { solAssert(m_errorOccured, ""); } return !m_errorOccured; } string Why3Translator::translation() const { string result; for (auto const& line: m_lines) result += string(line.indentation, '\t') + line.contents + "\n"; return result; } void Why3Translator::error(ASTNode const& _node, string const& _description) { auto err = make_shared(Error::Type::Why3TranslatorError); *err << errinfo_sourceLocation(_node.location()) << errinfo_comment(_description); m_errors.push_back(err); m_errorOccured = true; } void Why3Translator::fatalError(ASTNode const& _node, string const& _description) { error(_node, _description); BOOST_THROW_EXCEPTION(FatalError()); } string Why3Translator::toFormalType(Type const& _type) const { if (_type.category() == Type::Category::Bool) return "bool"; else if (auto type = dynamic_cast(&_type)) { if (!type->isAddress() && !type->isSigned() && type->numBits() == 256) return "uint256"; } else if (auto type = dynamic_cast(&_type)) { if (!type->isByteArray() && type->isDynamicallySized() && type->dataStoredIn(DataLocation::Memory)) { // Not catching NoFormalType exception. Let the caller deal with it. string base = toFormalType(*type->baseType()); return "array " + base; } } else if (auto mappingType = dynamic_cast(&_type)) { solAssert(mappingType->keyType(), "A mappingType misses a keyType."); if (dynamic_cast(&*mappingType->keyType())) { //@TODO Use the information from the key type and specify the length of the array as an invariant. // Also the constructor need to specify the length of the array. solAssert(mappingType->valueType(), "A mappingType misses a valueType."); // Not catching NoFormalType exception. Let the caller deal with it. string valueTypeFormal = toFormalType(*mappingType->valueType()); return "array " + valueTypeFormal; } } BOOST_THROW_EXCEPTION(NoFormalType() << errinfo_noFormalTypeFrom(_type.toString(true))); } void Why3Translator::addLine(string const& _line) { newLine(); add(_line); newLine(); } void Why3Translator::add(string const& _str) { m_lines.back().contents += _str; } void Why3Translator::newLine() { if (!m_lines.back().contents.empty()) m_lines.push_back({"", m_lines.back().indentation}); } void Why3Translator::unindent() { newLine(); solAssert(m_lines.back().indentation > 0, ""); m_lines.back().indentation--; } bool Why3Translator::visit(ContractDefinition const& _contract) { if (m_seenContract) error(_contract, "More than one contract not supported."); m_seenContract = true; m_currentContract.contract = &_contract; if (_contract.isLibrary()) error(_contract, "Libraries not supported."); addLine("module Contract_" + _contract.name()); indent(); addLine("use import int.Int"); addLine("use import ref.Ref"); addLine("use import map.Map"); addLine("use import array.Array"); addLine("use import int.ComputerDivision"); addLine("use import mach.int.Unsigned"); addLine("use import UInt256"); addLine("exception Revert"); addLine("exception Return"); if (_contract.stateVariables().empty()) addLine("type state = ()"); else { addLine("type state = {"); indent(); m_currentContract.stateVariables = _contract.stateVariables(); for (VariableDeclaration const* variable: m_currentContract.stateVariables) { string varType; try { varType = toFormalType(*variable->annotation().type); } catch (NoFormalType &err) { string const* typeNamePtr = boost::get_error_info(err); string typeName = typeNamePtr ? " \"" + *typeNamePtr + "\"" : ""; fatalError(*variable, "Type" + typeName + " not supported for state variable."); } addLine("mutable _" + variable->name() + ": " + varType); } unindent(); addLine("}"); } addLine("type account = {"); indent(); addLine("mutable balance: uint256;"); addLine("storage: state"); unindent(); addLine("}"); addLine("val external_call (this: account): bool"); indent(); addLine("ensures { result = false -> this = (old this) }"); addLine("writes { this }"); addSourceFromDocStrings(m_currentContract.contract->annotation()); unindent(); if (!_contract.baseContracts().empty()) error(*_contract.baseContracts().front(), "Inheritance not supported."); if (!_contract.definedStructs().empty()) error(*_contract.definedStructs().front(), "User-defined types not supported."); if (!_contract.definedEnums().empty()) error(*_contract.definedEnums().front(), "User-defined types not supported."); if (!_contract.events().empty()) error(*_contract.events().front(), "Events not supported."); if (!_contract.functionModifiers().empty()) error(*_contract.functionModifiers().front(), "Modifiers not supported."); ASTNode::listAccept(_contract.definedFunctions(), *this); return false; } void Why3Translator::endVisit(ContractDefinition const&) { m_currentContract.reset(); unindent(); addLine("end"); } bool Why3Translator::visit(FunctionDefinition const& _function) { if (!_function.isImplemented()) { error(_function, "Unimplemented functions not supported."); return false; } if (_function.name().empty()) { error(_function, "Fallback functions not supported."); return false; } if (!_function.modifiers().empty()) { error(_function, "Modifiers not supported."); return false; } m_localVariables.clear(); for (auto const& var: _function.parameters()) m_localVariables[var->name()] = var.get(); for (auto const& var: _function.returnParameters()) m_localVariables[var->name()] = var.get(); for (auto const& var: _function.localVariables()) m_localVariables[var->name()] = var; add("let rec _" + _function.name()); add(" (this: account)"); for (auto const& param: _function.parameters()) { string paramType; try { paramType = toFormalType(*param->annotation().type); } catch (NoFormalType &err) { string const* typeName = boost::get_error_info(err); error(*param, "Parameter type \"" + (typeName ? *typeName : "") + "\" not supported."); } if (param->name().empty()) error(*param, "Anonymous function parameters not supported."); add(" (arg_" + param->name() + ": " + paramType + ")"); } add(":"); indent(); indent(); string retString = "("; for (auto const& retParam: _function.returnParameters()) { string paramType; try { paramType = toFormalType(*retParam->annotation().type); } catch (NoFormalType &err) { string const* typeName = boost::get_error_info(err); error(*retParam, "Parameter type " + (typeName ? *typeName : "") + " not supported."); } if (retString.size() != 1) retString += ", "; retString += paramType; } add(retString + ")"); unindent(); addSourceFromDocStrings(_function.annotation()); if (!m_currentContract.contract) error(_function, "Only functions inside contracts allowed."); addSourceFromDocStrings(m_currentContract.contract->annotation()); if (_function.isDeclaredConst()) addLine("ensures { (old this) = this }"); else addLine("writes { this }"); addLine("="); // store the prestate in the case we need to revert addLine("let prestate = {balance = this.balance; storage = " + copyOfStorage() + "} in "); // initialise local variables for (auto const& variable: _function.parameters()) addLine("let _" + variable->name() + " = ref arg_" + variable->name() + " in"); for (auto const& variable: _function.returnParameters()) { if (variable->name().empty()) error(*variable, "Unnamed return variables not yet supported."); string varType; try { varType = toFormalType(*variable->annotation().type); } catch (NoFormalType &err) { string const* typeNamePtr = boost::get_error_info(err); error(*variable, "Type " + (typeNamePtr ? *typeNamePtr : "") + "in return parameter not yet supported."); } addLine("let _" + variable->name() + ": ref " + varType + " = ref (of_int 0) in"); } for (VariableDeclaration const* variable: _function.localVariables()) { if (variable->name().empty()) error(*variable, "Unnamed variables not yet supported."); string varType; try { varType = toFormalType(*variable->annotation().type); } catch (NoFormalType &err) { string const* typeNamePtr = boost::get_error_info(err); error(*variable, "Type " + (typeNamePtr ? *typeNamePtr : "") + "in variable declaration not yet supported."); } addLine("let _" + variable->name() + ": ref " + varType + " = ref (of_int 0) in"); } addLine("try"); _function.body().accept(*this); add(";"); addLine("raise Return"); string retVals; for (auto const& variable: _function.returnParameters()) { if (!retVals.empty()) retVals += ", "; retVals += "!_" + variable->name(); } addLine("with Return -> (" + retVals + ") |"); string reversion = " Revert -> this.balance <- prestate.balance; "; for (auto const* variable: m_currentContract.stateVariables) reversion += "this.storage._" + variable->name() + " <- prestate.storage._" + variable->name() + "; "; //@TODO in case of reversion the return values are wrong - we need to change the // return type to include a bool to signify if an exception was thrown. reversion += "(" + retVals + ")"; addLine(reversion); unindent(); addLine("end"); addLine(""); return false; } void Why3Translator::endVisit(FunctionDefinition const&) { m_localVariables.clear(); } bool Why3Translator::visit(Block const& _node) { addSourceFromDocStrings(_node.annotation()); add("begin"); indent(); for (size_t i = 0; i < _node.statements().size(); ++i) { _node.statements()[i]->accept(*this); if (i != _node.statements().size() - 1) { auto it = m_lines.end() - 1; while (it != m_lines.begin() && it->contents.empty()) --it; if (!boost::algorithm::ends_with(it->contents, "begin")) it->contents += ";"; } newLine(); } unindent(); add("end"); return false; } bool Why3Translator::visit(IfStatement const& _node) { addSourceFromDocStrings(_node.annotation()); add("if "); _node.condition().accept(*this); add(" then"); visitIndentedUnlessBlock(_node.trueStatement()); if (_node.falseStatement()) { newLine(); add("else"); visitIndentedUnlessBlock(*_node.falseStatement()); } return false; } bool Why3Translator::visit(WhileStatement const& _node) { addSourceFromDocStrings(_node.annotation()); add("while "); _node.condition().accept(*this); newLine(); add("do"); visitIndentedUnlessBlock(_node.body()); add("done"); return false; } bool Why3Translator::visit(Return const& _node) { addSourceFromDocStrings(_node.annotation()); if (_node.expression()) { solAssert(!!_node.annotation().functionReturnParameters, ""); auto const& params = _node.annotation().functionReturnParameters->parameters(); if (params.size() != 1) { error(_node, "Directly returning tuples not supported. Rather assign to return variable."); return false; } add("begin _" + params.front()->name() + " := "); _node.expression()->accept(*this); add("; raise Return end"); } else add("raise Return"); return false; } bool Why3Translator::visit(Throw const& _node) { addSourceFromDocStrings(_node.annotation()); add("raise Revert"); return false; } bool Why3Translator::visit(VariableDeclarationStatement const& _node) { addSourceFromDocStrings(_node.annotation()); if (_node.declarations().size() != 1) { error(_node, "Multiple variables not supported."); return false; } if (_node.initialValue()) { add("_" + _node.declarations().front()->name() + " := "); _node.initialValue()->accept(*this); } return false; } bool Why3Translator::visit(ExpressionStatement const& _node) { addSourceFromDocStrings(_node.annotation()); return true; } bool Why3Translator::visit(Assignment const& _node) { if (_node.assignmentOperator() != Token::Assign) error(_node, "Compound assignment not supported."); _node.leftHandSide().accept(*this); add(m_currentLValueIsRef ? " := " : " <- "); _node.rightHandSide().accept(*this); return false; } bool Why3Translator::visit(TupleExpression const& _node) { if (_node.components().size() != 1) error(_node, "Only tuples with exactly one component supported."); add("("); return true; } bool Why3Translator::visit(UnaryOperation const& _unaryOperation) { try { toFormalType(*_unaryOperation.annotation().type); } catch (NoFormalType &err) { string const* typeNamePtr = boost::get_error_info(err); error(_unaryOperation, "Type \"" + (typeNamePtr ? *typeNamePtr : "") + "\" supported in unary operation."); } switch (_unaryOperation.getOperator()) { case Token::Not: // ! add("(not "); break; default: error(_unaryOperation, "Operator not supported."); break; } _unaryOperation.subExpression().accept(*this); add(")"); return false; } bool Why3Translator::visit(BinaryOperation const& _binaryOperation) { Expression const& leftExpression = _binaryOperation.leftExpression(); Expression const& rightExpression = _binaryOperation.rightExpression(); solAssert(!!_binaryOperation.annotation().commonType, ""); Type const& commonType = *_binaryOperation.annotation().commonType; Token::Value const c_op = _binaryOperation.getOperator(); if (commonType.category() == Type::Category::RationalNumber) { auto const& constantNumber = dynamic_cast(commonType); if (constantNumber.isFractional()) error(_binaryOperation, "Fractional numbers not supported."); else add("(of_int " + toString(commonType.literalValue(nullptr)) + ")"); return false; } static const map optrans({ {Token::And, " && "}, {Token::Or, " || "}, {Token::BitOr, " lor "}, {Token::BitXor, " lxor "}, {Token::BitAnd, " land "}, {Token::Add, " + "}, {Token::Sub, " - "}, {Token::Mul, " * "}, {Token::Div, " / "}, {Token::Mod, " mod "}, {Token::Equal, " = "}, {Token::NotEqual, " <> "}, {Token::LessThan, " < "}, {Token::GreaterThan, " > "}, {Token::LessThanOrEqual, " <= "}, {Token::GreaterThanOrEqual, " >= "} }); if (!optrans.count(c_op)) { error(_binaryOperation, "Operator not supported."); return true; } add("("); leftExpression.accept(*this); add(optrans.at(c_op)); rightExpression.accept(*this); add(")"); return false; } bool Why3Translator::visit(FunctionCall const& _node) { if (_node.annotation().isTypeConversion || _node.annotation().isStructConstructorCall) { error(_node, "Only ordinary function calls supported."); return true; } FunctionType const& function = dynamic_cast(*_node.expression().annotation().type); switch (function.location()) { case FunctionType::Location::AddMod: case FunctionType::Location::MulMod: { //@todo require that third parameter is not zero add("(of_int (mod (Int.("); add(function.location() == FunctionType::Location::AddMod ? "+" : "*"); add(") (to_int "); _node.arguments().at(0)->accept(*this); add(") (to_int "); _node.arguments().at(1)->accept(*this); add(")) (to_int "); _node.arguments().at(2)->accept(*this); add(")))"); return false; } case FunctionType::Location::Internal: { if (!_node.names().empty()) { error(_node, "Function calls with named arguments not supported."); return true; } //@TODO check type conversions add("("); _node.expression().accept(*this); add(" state"); for (auto const& arg: _node.arguments()) { add(" "); arg->accept(*this); } add(")"); return false; } case FunctionType::Location::Bare: { if (!_node.arguments().empty()) { error(_node, "Function calls with named arguments not supported."); return true; } add("("); indent(); add("let amount = 0 in "); _node.expression().accept(*this); addLine("if amount <= this.balance then"); indent(); addLine("let balance_precall = this.balance in"); addLine("begin"); indent(); addLine("this.balance <- this.balance - amount;"); addLine("if not (external_call this) then begin this.balance = balance_precall; false end else true"); unindent(); addLine("end"); unindent(); addLine("else false"); unindent(); add(")"); return false; } case FunctionType::Location::SetValue: { add("let amount = "); solAssert(_node.arguments().size() == 1, ""); _node.arguments()[0]->accept(*this); add(" in "); return false; } default: error(_node, "Only internal function calls supported."); return true; } } bool Why3Translator::visit(MemberAccess const& _node) { if ( _node.expression().annotation().type->category() == Type::Category::Array && _node.memberName() == "length" && !_node.annotation().lValueRequested ) { add("(of_int "); _node.expression().accept(*this); add(".length"); add(")"); } else if ( _node.memberName() == "call" && *_node.expression().annotation().type == IntegerType(160, IntegerType::Modifier::Address) ) { // Do nothing, do not even visit the address because this will be an external call //@TODO ensure that the expression itself does not have side-effects return false; } else error(_node, "Member access: Only call and array length supported."); return false; } bool Why3Translator::visit(IndexAccess const& _node) { auto baseType = dynamic_cast(_node.baseExpression().annotation().type.get()); if (!baseType) { error(_node, "Index access only supported for arrays."); return true; } if (_node.annotation().lValueRequested) { error(_node, "Assignment to array elements not supported."); return true; } add("("); _node.baseExpression().accept(*this); add("[to_int "); _node.indexExpression()->accept(*this); add("]"); add(")"); return false; } bool Why3Translator::visit(Identifier const& _identifier) { Declaration const* declaration = _identifier.annotation().referencedDeclaration; if (FunctionDefinition const* functionDef = dynamic_cast(declaration)) add("_" + functionDef->name()); else if (auto variable = dynamic_cast(declaration)) { bool isStateVar = isStateVariable(variable); bool lvalue = _identifier.annotation().lValueRequested; if (isStateVar) add("this.storage."); else if (!lvalue) add("!("); add("_" + variable->name()); if (!isStateVar && !lvalue) add(")"); m_currentLValueIsRef = !isStateVar; } else error(_identifier, "Not supported."); return false; } bool Why3Translator::visit(Literal const& _literal) { TypePointer type = _literal.annotation().type; switch (type->category()) { case Type::Category::Bool: if (type->literalValue(&_literal) == 0) add("false"); else add("true"); break; case Type::Category::RationalNumber: { auto const& constantNumber = dynamic_cast(*type); if (constantNumber.isFractional()) error(_literal, "Fractional numbers not supported."); else add("(of_int " + toString(type->literalValue(&_literal)) + ")"); break; } default: error(_literal, "Not supported."); } return false; } bool Why3Translator::visit(PragmaDirective const& _pragma) { if (_pragma.tokens().empty()) error(_pragma, "Not supported"); else if (_pragma.literals().empty()) error(_pragma, "Not supported"); else if (_pragma.literals()[0] != "solidity") error(_pragma, "Not supported"); else if (_pragma.tokens()[0] != Token::Identifier) error(_pragma, "A literal 'solidity' is not an identifier. Strange"); return false; } bool Why3Translator::isStateVariable(VariableDeclaration const* _var) const { return contains(m_currentContract.stateVariables, _var); } bool Why3Translator::isStateVariable(string const& _name) const { for (auto const& var: m_currentContract.stateVariables) if (var->name() == _name) return true; return false; } bool Why3Translator::isLocalVariable(VariableDeclaration const* _var) const { for (auto const& var: m_localVariables) if (var.second == _var) return true; return false; } bool Why3Translator::isLocalVariable(string const& _name) const { return m_localVariables.count(_name); } string Why3Translator::copyOfStorage() const { if (m_currentContract.stateVariables.empty()) return "()"; string ret = "{"; bool first = true; for (auto const* variable: m_currentContract.stateVariables) { if (first) first = false; else ret += "; "; ret += "_" + variable->name() + " = this.storage._" + variable->name(); } return ret + "}"; } void Why3Translator::visitIndentedUnlessBlock(Statement const& _statement) { bool isBlock = !!dynamic_cast(&_statement); if (isBlock) newLine(); else indent(); _statement.accept(*this); if (isBlock) newLine(); else unindent(); } void Why3Translator::addSourceFromDocStrings(DocumentedAnnotation const& _annotation) { auto why3Range = _annotation.docTags.equal_range("why3"); for (auto i = why3Range.first; i != why3Range.second; ++i) addLine(transformVariableReferences(i->second.content)); } string Why3Translator::transformVariableReferences(string const& _annotation) { string ret; auto pos = _annotation.begin(); while (true) { auto hash = find(pos, _annotation.end(), '#'); ret.append(pos, hash); if (hash == _annotation.end()) break; auto hashEnd = find_if(hash + 1, _annotation.end(), [](char _c) { return (_c != '_' && _c != '$') && !('a' <= _c && _c <= 'z') && !('A' <= _c && _c <= 'Z') && !('0' <= _c && _c <= '9'); }); string varName(hash + 1, hashEnd); if (isLocalVariable(varName)) ret += "(!_" + varName + ")"; else if (isStateVariable(varName)) ret += "(this.storage._" + varName + ")"; //@todo return variables else ret.append(hash, hashEnd); pos = hashEnd; } return ret; } void Why3Translator::appendPreface() { m_lines.push_back(Line{R"( module UInt256 use import mach.int.Unsigned type uint256 constant max_uint256: int = 0xffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff clone export mach.int.Unsigned with type t = uint256, constant max = max_uint256 end module Address use import mach.int.Unsigned type address constant max_address: int = 0xffffffffffffffffffffffffffffffffffffffff (* 160 bit = 40 f's *) clone export mach.int.Unsigned with type t = address, constant max = max_address end )", 0}); }