solidity/libsolidity/formal/Why3Translator.cpp
2016-07-13 11:16:00 +02:00

798 lines
20 KiB
C++

/*
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 <http://www.gnu.org/licenses/>.
*/
/**
* @author Christian <c@ethdev.com>
* @date 2015
* Component that translates Solidity code into the why3 programming language.
*/
#include <libsolidity/formal/Why3Translator.h>
#include <boost/algorithm/string/predicate.hpp>
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 (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>(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<IntegerType const*>(&_type))
{
if (!type->isAddress() && !type->isSigned() && type->numBits() == 256)
return "uint256";
}
else if (auto type = dynamic_cast<ArrayType const*>(&_type))
if (!type->isByteArray() && type->isDynamicallySized() && type->dataStoredIn(DataLocation::Memory))
{
string base = toFormalType(*type->baseType());
if (!base.empty())
return "array " + base;
}
return "";
}
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 = toFormalType(*variable->annotation().type);
if (varType.empty())
fatalError(*variable, "Type 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 = toFormalType(*param->annotation().type);
if (paramType.empty())
error(*param, "Parameter type 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 = toFormalType(*retParam->annotation().type);
if (paramType.empty())
error(*retParam, "Parameter type 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 = toFormalType(*variable->annotation().type);
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 = toFormalType(*variable->annotation().type);
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)
{
if (toFormalType(*_unaryOperation.annotation().type).empty())
error(_unaryOperation, "Type not 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<RationalNumberType const&>(commonType);
if (constantNumber.isFractional())
error(_binaryOperation, "Fractional numbers not supported.");
add("(of_int " + toString(commonType.literalValue(nullptr)) + ")");
return false;
}
static const map<Token::Value, char const*> 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.");
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<FunctionType const&>(*_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<ArrayType const*>(_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<FunctionDefinition const*>(declaration))
add("_" + functionDef->name());
else if (auto variable = dynamic_cast<VariableDeclaration const*>(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<RationalNumberType const&>(*type);
if (constantNumber.isFractional())
error(_literal, "Fractional numbers not supported.");
add("(of_int " + toString(type->literalValue(&_literal)) + ")");
break;
}
default:
error(_literal, "Not supported.");
}
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<Block const*>(&_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
)", 0});
}