solidity/libsolidity/formal/SMTChecker.cpp

1489 lines
45 KiB
C++

/*
This file is part of solidity.
solidity 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.
solidity 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 solidity. If not, see <http://www.gnu.org/licenses/>.
*/
#include <libsolidity/formal/SMTChecker.h>
#include <libsolidity/formal/SMTPortfolio.h>
#include <libsolidity/formal/VariableUsage.h>
#include <libsolidity/formal/SymbolicTypes.h>
#include <libdevcore/StringUtils.h>
#include <boost/range/adaptor/map.hpp>
#include <boost/algorithm/string/replace.hpp>
using namespace std;
using namespace dev;
using namespace langutil;
using namespace dev::solidity;
SMTChecker::SMTChecker(ErrorReporter& _errorReporter, map<h256, string> const& _smtlib2Responses):
m_interface(make_shared<smt::SMTPortfolio>(_smtlib2Responses)),
m_errorReporterReference(_errorReporter),
m_errorReporter(m_smtErrors)
{
#if defined (HAVE_Z3) || defined (HAVE_CVC4)
if (!_smtlib2Responses.empty())
m_errorReporter.warning(
"SMT-LIB2 query responses were given in the auxiliary input, "
"but this Solidity binary uses an SMT solver (Z3/CVC4) directly."
"These responses will be ignored."
"Consider disabling Z3/CVC4 at compilation time in order to use SMT-LIB2 responses."
);
#endif
}
void SMTChecker::analyze(SourceUnit const& _source, shared_ptr<Scanner> const& _scanner)
{
m_variableUsage = make_shared<VariableUsage>(_source);
m_scanner = _scanner;
if (_source.annotation().experimentalFeatures.count(ExperimentalFeature::SMTChecker))
_source.accept(*this);
solAssert(m_interface->solvers() > 0, "");
// If this check is true, Z3 and CVC4 are not available
// and the query answers were not provided, since SMTPortfolio
// guarantees that SmtLib2Interface is the first solver.
if (!m_interface->unhandledQueries().empty() && m_interface->solvers() == 1)
{
if (!m_noSolverWarning)
{
m_noSolverWarning = true;
m_errorReporterReference.warning(
SourceLocation(),
"SMTChecker analysis was not possible since no integrated SMT solver (Z3 or CVC4) was found."
);
}
}
else
m_errorReporterReference.append(m_errorReporter.errors());
m_errorReporter.clear();
}
bool SMTChecker::visit(ContractDefinition const& _contract)
{
for (auto _var : _contract.stateVariables())
createVariable(*_var);
return true;
}
void SMTChecker::endVisit(ContractDefinition const&)
{
m_variables.clear();
}
void SMTChecker::endVisit(VariableDeclaration const& _varDecl)
{
if (_varDecl.isLocalVariable() && _varDecl.type()->isValueType() &&_varDecl.value())
assignment(_varDecl, *_varDecl.value(), _varDecl.location());
}
bool SMTChecker::visit(FunctionDefinition const& _function)
{
if (!_function.modifiers().empty() || _function.isConstructor())
m_errorReporter.warning(
_function.location(),
"Assertion checker does not yet support constructors and functions with modifiers."
);
m_functionPath.push_back(&_function);
// Not visited by a function call
if (isRootFunction())
{
m_interface->reset();
m_pathConditions.clear();
m_expressions.clear();
m_globalContext.clear();
m_uninterpretedTerms.clear();
m_overflowTargets.clear();
resetStateVariables();
initializeLocalVariables(_function);
m_loopExecutionHappened = false;
m_arrayAssignmentHappened = false;
}
return true;
}
void SMTChecker::endVisit(FunctionDefinition const&)
{
// If _function was visited from a function call we don't remove
// the local variables just yet, since we might need them for
// future calls.
// Otherwise we remove any local variables from the context and
// keep the state variables.
if (isRootFunction())
{
checkUnderOverflow();
removeLocalVariables();
}
m_functionPath.pop_back();
}
bool SMTChecker::visit(IfStatement const& _node)
{
_node.condition().accept(*this);
// We ignore called functions here because they have
// specific input values.
if (isRootFunction())
checkBooleanNotConstant(_node.condition(), "Condition is always $VALUE.");
auto indicesEndTrue = visitBranch(_node.trueStatement(), expr(_node.condition()));
vector<VariableDeclaration const*> touchedVariables = m_variableUsage->touchedVariables(_node.trueStatement());
decltype(indicesEndTrue) indicesEndFalse;
if (_node.falseStatement())
{
indicesEndFalse = visitBranch(*_node.falseStatement(), !expr(_node.condition()));
touchedVariables += m_variableUsage->touchedVariables(*_node.falseStatement());
}
else
indicesEndFalse = copyVariableIndices();
mergeVariables(touchedVariables, expr(_node.condition()), indicesEndTrue, indicesEndFalse);
return false;
}
// Here we consider the execution of two branches:
// Branch 1 assumes the loop condition to be true and executes the loop once,
// after resetting touched variables.
// Branch 2 assumes the loop condition to be false and skips the loop after
// visiting the condition (it might contain side-effects, they need to be considered)
// and does not erase knowledge.
// If the loop is a do-while, condition side-effects are lost since the body,
// executed once before the condition, might reassign variables.
// Variables touched by the loop are merged with Branch 2.
bool SMTChecker::visit(WhileStatement const& _node)
{
auto indicesBeforeLoop = copyVariableIndices();
auto touchedVariables = m_variableUsage->touchedVariables(_node);
resetVariables(touchedVariables);
decltype(indicesBeforeLoop) indicesAfterLoop;
if (_node.isDoWhile())
{
indicesAfterLoop = visitBranch(_node.body());
// TODO the assertions generated in the body should still be active in the condition
_node.condition().accept(*this);
if (isRootFunction())
checkBooleanNotConstant(_node.condition(), "Do-while loop condition is always $VALUE.");
}
else
{
_node.condition().accept(*this);
if (isRootFunction())
checkBooleanNotConstant(_node.condition(), "While loop condition is always $VALUE.");
indicesAfterLoop = visitBranch(_node.body(), expr(_node.condition()));
}
// We reset the execution to before the loop
// and visit the condition in case it's not a do-while.
// A do-while's body might have non-precise information
// in its first run about variables that are touched.
resetVariableIndices(indicesBeforeLoop);
if (!_node.isDoWhile())
_node.condition().accept(*this);
mergeVariables(touchedVariables, expr(_node.condition()), indicesAfterLoop, copyVariableIndices());
m_loopExecutionHappened = true;
return false;
}
// Here we consider the execution of two branches similar to WhileStatement.
bool SMTChecker::visit(ForStatement const& _node)
{
if (_node.initializationExpression())
_node.initializationExpression()->accept(*this);
auto indicesBeforeLoop = copyVariableIndices();
// Do not reset the init expression part.
auto touchedVariables =
m_variableUsage->touchedVariables(_node.body());
if (_node.condition())
touchedVariables += m_variableUsage->touchedVariables(*_node.condition());
if (_node.loopExpression())
touchedVariables += m_variableUsage->touchedVariables(*_node.loopExpression());
// Remove duplicates
std::sort(touchedVariables.begin(), touchedVariables.end());
touchedVariables.erase(std::unique(touchedVariables.begin(), touchedVariables.end()), touchedVariables.end());
resetVariables(touchedVariables);
if (_node.condition())
{
_node.condition()->accept(*this);
if (isRootFunction())
checkBooleanNotConstant(*_node.condition(), "For loop condition is always $VALUE.");
}
m_interface->push();
if (_node.condition())
m_interface->addAssertion(expr(*_node.condition()));
_node.body().accept(*this);
if (_node.loopExpression())
_node.loopExpression()->accept(*this);
m_interface->pop();
auto indicesAfterLoop = copyVariableIndices();
// We reset the execution to before the loop
// and visit the condition.
resetVariableIndices(indicesBeforeLoop);
if (_node.condition())
_node.condition()->accept(*this);
auto forCondition = _node.condition() ? expr(*_node.condition()) : smt::Expression(true);
mergeVariables(touchedVariables, forCondition, indicesAfterLoop, copyVariableIndices());
m_loopExecutionHappened = true;
return false;
}
void SMTChecker::endVisit(VariableDeclarationStatement const& _varDecl)
{
if (_varDecl.declarations().size() != 1)
m_errorReporter.warning(
_varDecl.location(),
"Assertion checker does not yet support such variable declarations."
);
else if (knownVariable(*_varDecl.declarations()[0]))
{
if (_varDecl.initialValue())
assignment(*_varDecl.declarations()[0], *_varDecl.initialValue(), _varDecl.location());
}
else
m_errorReporter.warning(
_varDecl.location(),
"Assertion checker does not yet implement such variable declarations."
);
}
void SMTChecker::endVisit(Assignment const& _assignment)
{
if (_assignment.assignmentOperator() != Token::Assign)
m_errorReporter.warning(
_assignment.location(),
"Assertion checker does not yet implement compound assignment."
);
else if (!isSupportedType(_assignment.annotation().type->category()))
m_errorReporter.warning(
_assignment.location(),
"Assertion checker does not yet implement type " + _assignment.annotation().type->toString()
);
else if (Identifier const* identifier = dynamic_cast<Identifier const*>(&_assignment.leftHandSide()))
{
VariableDeclaration const& decl = dynamic_cast<VariableDeclaration const&>(*identifier->annotation().referencedDeclaration);
solAssert(knownVariable(decl), "");
assignment(decl, _assignment.rightHandSide(), _assignment.location());
defineExpr(_assignment, expr(_assignment.rightHandSide()));
}
else if (dynamic_cast<IndexAccess const*>(&_assignment.leftHandSide()))
{
arrayIndexAssignment(_assignment);
defineExpr(_assignment, expr(_assignment.rightHandSide()));
}
else
m_errorReporter.warning(
_assignment.location(),
"Assertion checker does not yet implement such assignments."
);
}
void SMTChecker::endVisit(TupleExpression const& _tuple)
{
if (
_tuple.isInlineArray() ||
_tuple.components().size() != 1 ||
!isSupportedType(_tuple.components()[0]->annotation().type->category())
)
m_errorReporter.warning(
_tuple.location(),
"Assertion checker does not yet implement tuples and inline arrays."
);
else
defineExpr(_tuple, expr(*_tuple.components()[0]));
}
void SMTChecker::addOverflowTarget(
OverflowTarget::Type _type,
TypePointer _intType,
smt::Expression _value,
SourceLocation const& _location
)
{
m_overflowTargets.emplace_back(
_type,
std::move(_intType),
std::move(_value),
currentPathConditions(),
_location
);
}
void SMTChecker::checkUnderOverflow()
{
for (auto& target: m_overflowTargets)
{
if (target.type != OverflowTarget::Type::Overflow)
checkUnderflow(target);
if (target.type != OverflowTarget::Type::Underflow)
checkOverflow(target);
}
}
void SMTChecker::checkUnderflow(OverflowTarget& _target)
{
solAssert(_target.type != OverflowTarget::Type::Overflow, "");
auto intType = dynamic_cast<IntegerType const*>(_target.intType.get());
checkCondition(
_target.path && _target.value < minValue(*intType),
_target.location,
"Underflow (resulting value less than " + formatNumberReadable(intType->minValue()) + ")",
"<result>",
&_target.value
);
}
void SMTChecker::checkOverflow(OverflowTarget& _target)
{
solAssert(_target.type != OverflowTarget::Type::Underflow, "");
auto intType = dynamic_cast<IntegerType const*>(_target.intType.get());
checkCondition(
_target.path && _target.value > maxValue(*intType),
_target.location,
"Overflow (resulting value larger than " + formatNumberReadable(intType->maxValue()) + ")",
"<result>",
&_target.value
);
}
void SMTChecker::endVisit(UnaryOperation const& _op)
{
switch (_op.getOperator())
{
case Token::Not: // !
{
solAssert(isBool(_op.annotation().type->category()), "");
defineExpr(_op, !expr(_op.subExpression()));
break;
}
case Token::Inc: // ++ (pre- or postfix)
case Token::Dec: // -- (pre- or postfix)
{
solAssert(isInteger(_op.annotation().type->category()), "");
solAssert(_op.subExpression().annotation().lValueRequested, "");
if (Identifier const* identifier = dynamic_cast<Identifier const*>(&_op.subExpression()))
{
VariableDeclaration const& decl = dynamic_cast<VariableDeclaration const&>(*identifier->annotation().referencedDeclaration);
if (knownVariable(decl))
{
auto innerValue = currentValue(decl);
auto newValue = _op.getOperator() == Token::Inc ? innerValue + 1 : innerValue - 1;
assignment(decl, newValue, _op.location());
defineExpr(_op, _op.isPrefixOperation() ? newValue : innerValue);
}
else
m_errorReporter.warning(
_op.location(),
"Assertion checker does not yet implement such assignments."
);
}
else
m_errorReporter.warning(
_op.location(),
"Assertion checker does not yet implement such increments / decrements."
);
break;
}
case Token::Sub: // -
{
defineExpr(_op, 0 - expr(_op.subExpression()));
if (_op.annotation().type->category() == Type::Category::Integer)
addOverflowTarget(
OverflowTarget::Type::All,
_op.annotation().type,
expr(_op),
_op.location()
);
break;
}
default:
m_errorReporter.warning(
_op.location(),
"Assertion checker does not yet implement this operator."
);
}
}
void SMTChecker::endVisit(BinaryOperation const& _op)
{
if (TokenTraits::isArithmeticOp(_op.getOperator()))
arithmeticOperation(_op);
else if (TokenTraits::isCompareOp(_op.getOperator()))
compareOperation(_op);
else if (TokenTraits::isBooleanOp(_op.getOperator()))
booleanOperation(_op);
else
m_errorReporter.warning(
_op.location(),
"Assertion checker does not yet implement this operator."
);
}
void SMTChecker::endVisit(FunctionCall const& _funCall)
{
solAssert(_funCall.annotation().kind != FunctionCallKind::Unset, "");
if (_funCall.annotation().kind == FunctionCallKind::StructConstructorCall)
{
m_errorReporter.warning(
_funCall.location(),
"Assertion checker does not yet implement this expression."
);
return;
}
if (_funCall.annotation().kind == FunctionCallKind::TypeConversion)
{
visitTypeConversion(_funCall);
return;
}
FunctionType const& funType = dynamic_cast<FunctionType const&>(*_funCall.expression().annotation().type);
std::vector<ASTPointer<Expression const>> const args = _funCall.arguments();
switch (funType.kind())
{
case FunctionType::Kind::Assert:
visitAssert(_funCall);
break;
case FunctionType::Kind::Require:
visitRequire(_funCall);
break;
case FunctionType::Kind::GasLeft:
visitGasLeft(_funCall);
break;
case FunctionType::Kind::Internal:
inlineFunctionCall(_funCall);
break;
case FunctionType::Kind::External:
resetStateVariables();
resetStorageReferences();
break;
case FunctionType::Kind::KECCAK256:
case FunctionType::Kind::ECRecover:
case FunctionType::Kind::SHA256:
case FunctionType::Kind::RIPEMD160:
case FunctionType::Kind::BlockHash:
case FunctionType::Kind::AddMod:
case FunctionType::Kind::MulMod:
abstractFunctionCall(_funCall);
break;
default:
m_errorReporter.warning(
_funCall.location(),
"Assertion checker does not yet implement this type of function call."
);
}
}
void SMTChecker::visitAssert(FunctionCall const& _funCall)
{
auto const& args = _funCall.arguments();
solAssert(args.size() == 1, "");
solAssert(args[0]->annotation().type->category() == Type::Category::Bool, "");
checkCondition(!(expr(*args[0])), _funCall.location(), "Assertion violation");
addPathImpliedExpression(expr(*args[0]));
}
void SMTChecker::visitRequire(FunctionCall const& _funCall)
{
auto const& args = _funCall.arguments();
solAssert(args.size() == 1, "");
solAssert(args[0]->annotation().type->category() == Type::Category::Bool, "");
if (isRootFunction())
checkBooleanNotConstant(*args[0], "Condition is always $VALUE.");
addPathImpliedExpression(expr(*args[0]));
}
void SMTChecker::visitGasLeft(FunctionCall const& _funCall)
{
string gasLeft = "gasleft()";
// We increase the variable index since gasleft changes
// inside a tx.
defineGlobalVariable(gasLeft, _funCall, true);
auto const& symbolicVar = m_globalContext.at(gasLeft);
unsigned index = symbolicVar->index();
// We set the current value to unknown anyway to add type constraints.
setUnknownValue(*symbolicVar);
if (index > 0)
m_interface->addAssertion(symbolicVar->currentValue() <= symbolicVar->valueAtIndex(index - 1));
}
void SMTChecker::eraseArrayKnowledge()
{
for (auto const& var: m_variables)
if (var.first->annotation().type->category() == Type::Category::Mapping)
newValue(*var.first);
}
void SMTChecker::inlineFunctionCall(FunctionCall const& _funCall)
{
FunctionDefinition const* _funDef = nullptr;
Expression const* _calledExpr = &_funCall.expression();
if (TupleExpression const* _fun = dynamic_cast<TupleExpression const*>(&_funCall.expression()))
{
solAssert(_fun->components().size() == 1, "");
_calledExpr = _fun->components().at(0).get();
}
if (Identifier const* _fun = dynamic_cast<Identifier const*>(_calledExpr))
_funDef = dynamic_cast<FunctionDefinition const*>(_fun->annotation().referencedDeclaration);
else if (MemberAccess const* _fun = dynamic_cast<MemberAccess const*>(_calledExpr))
_funDef = dynamic_cast<FunctionDefinition const*>(_fun->annotation().referencedDeclaration);
else
{
m_errorReporter.warning(
_funCall.location(),
"Assertion checker does not yet implement this type of function call."
);
return;
}
solAssert(_funDef, "");
if (visitedFunction(_funDef))
m_errorReporter.warning(
_funCall.location(),
"Assertion checker does not support recursive function calls.",
SecondarySourceLocation().append("Starting from function:", _funDef->location())
);
else if (_funDef && _funDef->isImplemented())
{
vector<smt::Expression> funArgs;
auto const& funType = dynamic_cast<FunctionType const*>(_calledExpr->annotation().type.get());
solAssert(funType, "");
if (funType->bound())
{
auto const& boundFunction = dynamic_cast<MemberAccess const*>(_calledExpr);
solAssert(boundFunction, "");
funArgs.push_back(expr(boundFunction->expression()));
}
for (auto arg: _funCall.arguments())
funArgs.push_back(expr(*arg));
initializeFunctionCallParameters(*_funDef, funArgs);
_funDef->accept(*this);
auto const& returnParams = _funDef->returnParameters();
if (_funDef->returnParameters().size())
{
if (returnParams.size() > 1)
m_errorReporter.warning(
_funCall.location(),
"Assertion checker does not yet support calls to functions that return more than one value."
);
else
defineExpr(_funCall, currentValue(*returnParams[0]));
}
}
else
{
m_errorReporter.warning(
_funCall.location(),
"Assertion checker does not support calls to functions without implementation."
);
}
}
void SMTChecker::abstractFunctionCall(FunctionCall const& _funCall)
{
vector<smt::Expression> smtArguments;
for (auto const& arg: _funCall.arguments())
smtArguments.push_back(expr(*arg));
defineExpr(_funCall, (*m_expressions.at(&_funCall.expression()))(smtArguments));
m_uninterpretedTerms.insert(&_funCall);
setSymbolicUnknownValue(expr(_funCall), _funCall.annotation().type, *m_interface);
}
void SMTChecker::endVisit(Identifier const& _identifier)
{
if (_identifier.annotation().lValueRequested)
{
// Will be translated as part of the node that requested the lvalue.
}
else if (_identifier.annotation().type->category() == Type::Category::Function)
visitFunctionIdentifier(_identifier);
else if (isSupportedType(_identifier.annotation().type->category()))
{
if (VariableDeclaration const* decl = dynamic_cast<VariableDeclaration const*>(_identifier.annotation().referencedDeclaration))
defineExpr(_identifier, currentValue(*decl));
else if (_identifier.name() == "now")
defineGlobalVariable(_identifier.name(), _identifier);
else
// TODO: handle MagicVariableDeclaration here
m_errorReporter.warning(
_identifier.location(),
"Assertion checker does not yet support the type of this variable."
);
}
}
void SMTChecker::visitTypeConversion(FunctionCall const& _funCall)
{
solAssert(_funCall.annotation().kind == FunctionCallKind::TypeConversion, "");
solAssert(_funCall.arguments().size() == 1, "");
auto argument = _funCall.arguments().at(0);
unsigned argSize = argument->annotation().type->storageBytes();
unsigned castSize = _funCall.annotation().type->storageBytes();
if (argSize == castSize)
defineExpr(_funCall, expr(*argument));
else
{
createExpr(_funCall);
setUnknownValue(*m_expressions.at(&_funCall));
auto const& funCallCategory = _funCall.annotation().type->category();
// TODO: truncating and bytesX needs a different approach because of right padding.
if (funCallCategory == Type::Category::Integer || funCallCategory == Type::Category::Address)
{
if (argSize < castSize)
defineExpr(_funCall, expr(*argument));
else
{
auto const& intType = dynamic_cast<IntegerType const&>(*m_expressions.at(&_funCall)->type());
defineExpr(_funCall, smt::Expression::ite(
expr(*argument) >= minValue(intType) && expr(*argument) <= maxValue(intType),
expr(*argument),
expr(_funCall)
));
}
}
m_errorReporter.warning(
_funCall.location(),
"Type conversion is not yet fully supported and might yield false positives."
);
}
}
void SMTChecker::visitFunctionIdentifier(Identifier const& _identifier)
{
auto const& fType = dynamic_cast<FunctionType const&>(*_identifier.annotation().type);
if (fType.returnParameterTypes().size() > 1)
{
m_errorReporter.warning(
_identifier.location(),
"Assertion checker does not yet support functions with more than one return parameter."
);
}
defineGlobalFunction(fType.richIdentifier(), _identifier);
m_expressions.emplace(&_identifier, m_globalContext.at(fType.richIdentifier()));
}
void SMTChecker::endVisit(Literal const& _literal)
{
Type const& type = *_literal.annotation().type;
if (isNumber(type.category()))
defineExpr(_literal, smt::Expression(type.literalValue(&_literal)));
else if (isBool(type.category()))
defineExpr(_literal, smt::Expression(_literal.token() == Token::TrueLiteral ? true : false));
else
m_errorReporter.warning(
_literal.location(),
"Assertion checker does not yet support the type of this literal (" +
_literal.annotation().type->toString() +
")."
);
}
void SMTChecker::endVisit(Return const& _return)
{
if (knownExpr(*_return.expression()))
{
auto returnParams = m_functionPath.back()->returnParameters();
if (returnParams.size() > 1)
m_errorReporter.warning(
_return.location(),
"Assertion checker does not yet support more than one return value."
);
else if (returnParams.size() == 1)
m_interface->addAssertion(expr(*_return.expression()) == newValue(*returnParams[0]));
}
}
bool SMTChecker::visit(MemberAccess const& _memberAccess)
{
auto const& accessType = _memberAccess.annotation().type;
if (accessType->category() == Type::Category::Function)
return true;
auto const& exprType = _memberAccess.expression().annotation().type;
solAssert(exprType, "");
if (exprType->category() == Type::Category::Magic)
{
auto identifier = dynamic_cast<Identifier const*>(&_memberAccess.expression());
string accessedName;
if (identifier)
accessedName = identifier->name();
else
m_errorReporter.warning(
_memberAccess.location(),
"Assertion checker does not yet support this expression."
);
defineGlobalVariable(accessedName + "." + _memberAccess.memberName(), _memberAccess);
return false;
}
else
m_errorReporter.warning(
_memberAccess.location(),
"Assertion checker does not yet support this expression."
);
return true;
}
void SMTChecker::endVisit(IndexAccess const& _indexAccess)
{
shared_ptr<SymbolicVariable> array;
if (auto const& id = dynamic_cast<Identifier const*>(&_indexAccess.baseExpression()))
{
auto const& varDecl = dynamic_cast<VariableDeclaration const&>(*id->annotation().referencedDeclaration);
solAssert(knownVariable(varDecl), "");
array = m_variables[&varDecl];
}
else if (auto const& innerAccess = dynamic_cast<IndexAccess const*>(&_indexAccess.baseExpression()))
{
solAssert(knownExpr(*innerAccess), "");
array = m_expressions[innerAccess];
}
else
{
m_errorReporter.warning(
_indexAccess.location(),
"Assertion checker does not yet implement this expression."
);
return;
}
solAssert(array, "");
defineExpr(_indexAccess, smt::Expression::select(
array->currentValue(),
expr(*_indexAccess.indexExpression())
));
setSymbolicUnknownValue(
expr(_indexAccess),
_indexAccess.annotation().type,
*m_interface
);
m_uninterpretedTerms.insert(&_indexAccess);
}
void SMTChecker::arrayAssignment()
{
m_arrayAssignmentHappened = true;
eraseArrayKnowledge();
}
void SMTChecker::arrayIndexAssignment(Assignment const& _assignment)
{
auto const& indexAccess = dynamic_cast<IndexAccess const&>(_assignment.leftHandSide());
if (auto const& id = dynamic_cast<Identifier const*>(&indexAccess.baseExpression()))
{
auto const& varDecl = dynamic_cast<VariableDeclaration const&>(*id->annotation().referencedDeclaration);
solAssert(knownVariable(varDecl), "");
smt::Expression store = smt::Expression::store(
m_variables[&varDecl]->currentValue(),
expr(*indexAccess.indexExpression()),
expr(_assignment.rightHandSide())
);
m_interface->addAssertion(newValue(varDecl) == store);
}
else if (dynamic_cast<IndexAccess const*>(&indexAccess.baseExpression()))
m_errorReporter.warning(
indexAccess.location(),
"Assertion checker does not yet implement assignments to multi-dimensional mappings or arrays."
);
else
m_errorReporter.warning(
_assignment.location(),
"Assertion checker does not yet implement this expression."
);
}
void SMTChecker::defineGlobalVariable(string const& _name, Expression const& _expr, bool _increaseIndex)
{
if (!knownGlobalSymbol(_name))
{
auto result = newSymbolicVariable(*_expr.annotation().type, _name, *m_interface);
m_globalContext.emplace(_name, result.second);
setUnknownValue(*result.second);
if (result.first)
m_errorReporter.warning(
_expr.location(),
"Assertion checker does not yet support this global variable."
);
}
else if (_increaseIndex)
m_globalContext.at(_name)->increaseIndex();
// The default behavior is not to increase the index since
// most of the global values stay the same throughout a tx.
if (isSupportedType(_expr.annotation().type->category()))
defineExpr(_expr, m_globalContext.at(_name)->currentValue());
}
void SMTChecker::defineGlobalFunction(string const& _name, Expression const& _expr)
{
if (!knownGlobalSymbol(_name))
{
auto result = newSymbolicVariable(*_expr.annotation().type, _name, *m_interface);
m_globalContext.emplace(_name, result.second);
if (result.first)
m_errorReporter.warning(
_expr.location(),
"Assertion checker does not yet support the type of this function."
);
}
}
void SMTChecker::arithmeticOperation(BinaryOperation const& _op)
{
switch (_op.getOperator())
{
case Token::Add:
case Token::Sub:
case Token::Mul:
case Token::Div:
{
solAssert(_op.annotation().commonType, "");
if (_op.annotation().commonType->category() != Type::Category::Integer)
{
m_errorReporter.warning(
_op.location(),
"Assertion checker does not yet implement this operator on non-integer types."
);
break;
}
auto const& intType = dynamic_cast<IntegerType const&>(*_op.annotation().commonType);
smt::Expression left(expr(_op.leftExpression()));
smt::Expression right(expr(_op.rightExpression()));
Token op = _op.getOperator();
smt::Expression value(
op == Token::Add ? left + right :
op == Token::Sub ? left - right :
op == Token::Div ? division(left, right, intType) :
/*op == Token::Mul*/ left * right
);
if (_op.getOperator() == Token::Div)
{
checkCondition(right == 0, _op.location(), "Division by zero", "<result>", &right);
m_interface->addAssertion(right != 0);
}
addOverflowTarget(
OverflowTarget::Type::All,
_op.annotation().commonType,
value,
_op.location()
);
smt::Expression intValueRange = (0 - minValue(intType)) + maxValue(intType) + 1;
defineExpr(_op, smt::Expression::ite(
value > maxValue(intType) || value < minValue(intType),
value % intValueRange,
value
));
if (intType.isSigned())
{
defineExpr(_op, smt::Expression::ite(
expr(_op) > maxValue(intType),
expr(_op) - intValueRange,
expr(_op)
));
}
break;
}
default:
m_errorReporter.warning(
_op.location(),
"Assertion checker does not yet implement this operator."
);
}
}
void SMTChecker::compareOperation(BinaryOperation const& _op)
{
solAssert(_op.annotation().commonType, "");
if (isSupportedType(_op.annotation().commonType->category()))
{
smt::Expression left(expr(_op.leftExpression()));
smt::Expression right(expr(_op.rightExpression()));
Token op = _op.getOperator();
shared_ptr<smt::Expression> value;
if (isNumber(_op.annotation().commonType->category()))
{
value = make_shared<smt::Expression>(
op == Token::Equal ? (left == right) :
op == Token::NotEqual ? (left != right) :
op == Token::LessThan ? (left < right) :
op == Token::LessThanOrEqual ? (left <= right) :
op == Token::GreaterThan ? (left > right) :
/*op == Token::GreaterThanOrEqual*/ (left >= right)
);
}
else // Bool
{
solUnimplementedAssert(isBool(_op.annotation().commonType->category()), "Operation not yet supported");
value = make_shared<smt::Expression>(
op == Token::Equal ? (left == right) :
/*op == Token::NotEqual*/ (left != right)
);
}
// TODO: check that other values for op are not possible.
defineExpr(_op, *value);
}
else
m_errorReporter.warning(
_op.location(),
"Assertion checker does not yet implement the type " + _op.annotation().commonType->toString() + " for comparisons"
);
}
void SMTChecker::booleanOperation(BinaryOperation const& _op)
{
solAssert(_op.getOperator() == Token::And || _op.getOperator() == Token::Or, "");
solAssert(_op.annotation().commonType, "");
if (_op.annotation().commonType->category() == Type::Category::Bool)
{
// @TODO check that both of them are not constant
if (_op.getOperator() == Token::And)
defineExpr(_op, expr(_op.leftExpression()) && expr(_op.rightExpression()));
else
defineExpr(_op, expr(_op.leftExpression()) || expr(_op.rightExpression()));
}
else
m_errorReporter.warning(
_op.location(),
"Assertion checker does not yet implement the type " + _op.annotation().commonType->toString() + " for boolean operations"
);
}
smt::Expression SMTChecker::division(smt::Expression _left, smt::Expression _right, IntegerType const& _type)
{
// Signed division in SMTLIB2 rounds differently for negative division.
if (_type.isSigned())
return (smt::Expression::ite(
_left >= 0,
smt::Expression::ite(_right >= 0, _left / _right, 0 - (_left / (0 - _right))),
smt::Expression::ite(_right >= 0, 0 - ((0 - _left) / _right), (0 - _left) / (0 - _right))
));
else
return _left / _right;
}
void SMTChecker::assignment(VariableDeclaration const& _variable, Expression const& _value, SourceLocation const& _location)
{
assignment(_variable, expr(_value), _location);
}
void SMTChecker::assignment(VariableDeclaration const& _variable, smt::Expression const& _value, SourceLocation const& _location)
{
TypePointer type = _variable.type();
if (type->category() == Type::Category::Integer)
addOverflowTarget(OverflowTarget::Type::All, type, _value, _location);
else if (type->category() == Type::Category::Address)
addOverflowTarget(OverflowTarget::Type::All, make_shared<IntegerType>(160), _value, _location);
else if (type->category() == Type::Category::Mapping)
arrayAssignment();
m_interface->addAssertion(newValue(_variable) == _value);
}
SMTChecker::VariableIndices SMTChecker::visitBranch(Statement const& _statement, smt::Expression _condition)
{
return visitBranch(_statement, &_condition);
}
SMTChecker::VariableIndices SMTChecker::visitBranch(Statement const& _statement, smt::Expression const* _condition)
{
auto indicesBeforeBranch = copyVariableIndices();
if (_condition)
pushPathCondition(*_condition);
_statement.accept(*this);
if (_condition)
popPathCondition();
auto indicesAfterBranch = copyVariableIndices();
resetVariableIndices(indicesBeforeBranch);
return indicesAfterBranch;
}
void SMTChecker::checkCondition(
smt::Expression _condition,
SourceLocation const& _location,
string const& _description,
string const& _additionalValueName,
smt::Expression* _additionalValue
)
{
m_interface->push();
addPathConjoinedExpression(_condition);
vector<smt::Expression> expressionsToEvaluate;
vector<string> expressionNames;
if (m_functionPath.size())
{
solAssert(m_scanner, "");
if (_additionalValue)
{
expressionsToEvaluate.emplace_back(*_additionalValue);
expressionNames.push_back(_additionalValueName);
}
for (auto const& var: m_variables)
{
if (var.first->type()->isValueType())
{
expressionsToEvaluate.emplace_back(currentValue(*var.first));
expressionNames.push_back(var.first->name());
}
}
for (auto const& var: m_globalContext)
{
auto const& type = var.second->type();
if (
type->isValueType() &&
smtKind(type->category()) != smt::Kind::Function
)
{
expressionsToEvaluate.emplace_back(var.second->currentValue());
expressionNames.push_back(var.first);
}
}
for (auto const& uf: m_uninterpretedTerms)
{
if (uf->annotation().type->isValueType())
{
expressionsToEvaluate.emplace_back(expr(*uf));
expressionNames.push_back(m_scanner->sourceAt(uf->location()));
}
}
}
smt::CheckResult result;
vector<string> values;
tie(result, values) = checkSatisfiableAndGenerateModel(expressionsToEvaluate);
string loopComment;
if (m_loopExecutionHappened)
loopComment =
"\nNote that some information is erased after the execution of loops.\n"
"You can re-introduce information using require().";
if (m_arrayAssignmentHappened)
loopComment +=
"\nNote that array aliasing is not supported,"
" therefore all mapping information is erased after"
" a mapping local variable/parameter is assigned.\n"
"You can re-introduce information using require().";
switch (result)
{
case smt::CheckResult::SATISFIABLE:
{
std::ostringstream message;
message << _description << " happens here";
if (m_functionPath.size())
{
std::ostringstream modelMessage;
modelMessage << " for:\n";
solAssert(values.size() == expressionNames.size(), "");
map<string, string> sortedModel;
for (size_t i = 0; i < values.size(); ++i)
if (expressionsToEvaluate.at(i).name != values.at(i))
sortedModel[expressionNames.at(i)] = values.at(i);
for (auto const& eval: sortedModel)
modelMessage << " " << eval.first << " = " << eval.second << "\n";
m_errorReporter.warning(_location, message.str(), SecondarySourceLocation().append(modelMessage.str(), SourceLocation()).append(loopComment, SourceLocation()));
}
else
{
message << ".";
m_errorReporter.warning(_location, message.str(), SecondarySourceLocation().append(loopComment, SourceLocation()));
}
break;
}
case smt::CheckResult::UNSATISFIABLE:
break;
case smt::CheckResult::UNKNOWN:
m_errorReporter.warning(_location, _description + " might happen here.", SecondarySourceLocation().append(loopComment, SourceLocation()));
break;
case smt::CheckResult::CONFLICTING:
m_errorReporter.warning(_location, "At least two SMT solvers provided conflicting answers. Results might not be sound.");
break;
case smt::CheckResult::ERROR:
m_errorReporter.warning(_location, "Error trying to invoke SMT solver.");
break;
}
m_interface->pop();
}
void SMTChecker::checkBooleanNotConstant(Expression const& _condition, string const& _description)
{
// Do not check for const-ness if this is a constant.
if (dynamic_cast<Literal const*>(&_condition))
return;
m_interface->push();
addPathConjoinedExpression(expr(_condition));
auto positiveResult = checkSatisfiable();
m_interface->pop();
m_interface->push();
addPathConjoinedExpression(!expr(_condition));
auto negatedResult = checkSatisfiable();
m_interface->pop();
if (positiveResult == smt::CheckResult::ERROR || negatedResult == smt::CheckResult::ERROR)
m_errorReporter.warning(_condition.location(), "Error trying to invoke SMT solver.");
else if (positiveResult == smt::CheckResult::CONFLICTING || negatedResult == smt::CheckResult::CONFLICTING)
m_errorReporter.warning(_condition.location(), "At least two SMT solvers provided conflicting answers. Results might not be sound.");
else if (positiveResult == smt::CheckResult::SATISFIABLE && negatedResult == smt::CheckResult::SATISFIABLE)
{
// everything fine.
}
else if (positiveResult == smt::CheckResult::UNKNOWN || negatedResult == smt::CheckResult::UNKNOWN)
{
// can't do anything.
}
else if (positiveResult == smt::CheckResult::UNSATISFIABLE && negatedResult == smt::CheckResult::UNSATISFIABLE)
m_errorReporter.warning(_condition.location(), "Condition unreachable.");
else
{
string value;
if (positiveResult == smt::CheckResult::SATISFIABLE)
{
solAssert(negatedResult == smt::CheckResult::UNSATISFIABLE, "");
value = "true";
}
else
{
solAssert(positiveResult == smt::CheckResult::UNSATISFIABLE, "");
solAssert(negatedResult == smt::CheckResult::SATISFIABLE, "");
value = "false";
}
m_errorReporter.warning(_condition.location(), boost::algorithm::replace_all_copy(_description, "$VALUE", value));
}
}
pair<smt::CheckResult, vector<string>>
SMTChecker::checkSatisfiableAndGenerateModel(vector<smt::Expression> const& _expressionsToEvaluate)
{
smt::CheckResult result;
vector<string> values;
try
{
tie(result, values) = m_interface->check(_expressionsToEvaluate);
}
catch (smt::SolverError const& _e)
{
string description("Error querying SMT solver");
if (_e.comment())
description += ": " + *_e.comment();
m_errorReporter.warning(description);
result = smt::CheckResult::ERROR;
}
for (string& value: values)
{
try
{
// Parse and re-format nicely
value = formatNumberReadable(bigint(value));
}
catch (...) { }
}
return make_pair(result, values);
}
smt::CheckResult SMTChecker::checkSatisfiable()
{
return checkSatisfiableAndGenerateModel({}).first;
}
void SMTChecker::initializeFunctionCallParameters(FunctionDefinition const& _function, vector<smt::Expression> const& _callArgs)
{
auto const& funParams = _function.parameters();
solAssert(funParams.size() == _callArgs.size(), "");
for (unsigned i = 0; i < funParams.size(); ++i)
if (createVariable(*funParams[i]))
{
m_interface->addAssertion(_callArgs[i] == newValue(*funParams[i]));
if (funParams[i]->annotation().type->category() == Type::Category::Mapping)
m_arrayAssignmentHappened = true;
}
for (auto const& variable: _function.localVariables())
if (createVariable(*variable))
{
newValue(*variable);
setZeroValue(*variable);
}
if (_function.returnParameterList())
for (auto const& retParam: _function.returnParameters())
if (createVariable(*retParam))
{
newValue(*retParam);
setZeroValue(*retParam);
}
}
void SMTChecker::initializeLocalVariables(FunctionDefinition const& _function)
{
for (auto const& variable: _function.localVariables())
if (createVariable(*variable))
setZeroValue(*variable);
for (auto const& param: _function.parameters())
if (createVariable(*param))
setUnknownValue(*param);
if (_function.returnParameterList())
for (auto const& retParam: _function.returnParameters())
if (createVariable(*retParam))
setZeroValue(*retParam);
}
void SMTChecker::removeLocalVariables()
{
for (auto it = m_variables.begin(); it != m_variables.end(); )
{
if (it->first->isLocalVariable())
it = m_variables.erase(it);
else
++it;
}
}
void SMTChecker::resetVariable(VariableDeclaration const& _variable)
{
newValue(_variable);
setUnknownValue(_variable);
}
void SMTChecker::resetStateVariables()
{
resetVariables([&](VariableDeclaration const& _variable) { return _variable.isStateVariable(); });
}
void SMTChecker::resetStorageReferences()
{
resetVariables([&](VariableDeclaration const& _variable) { return _variable.hasReferenceOrMappingType(); });
}
void SMTChecker::resetVariables(vector<VariableDeclaration const*> _variables)
{
for (auto const* decl: _variables)
resetVariable(*decl);
}
void SMTChecker::resetVariables(function<bool(VariableDeclaration const&)> const& _filter)
{
for_each(begin(m_variables), end(m_variables), [&](auto _variable)
{
if (_filter(*_variable.first))
this->resetVariable(*_variable.first);
});
}
void SMTChecker::mergeVariables(vector<VariableDeclaration const*> const& _variables, smt::Expression const& _condition, VariableIndices const& _indicesEndTrue, VariableIndices const& _indicesEndFalse)
{
set<VariableDeclaration const*> uniqueVars(_variables.begin(), _variables.end());
for (auto const* decl: uniqueVars)
{
solAssert(_indicesEndTrue.count(decl) && _indicesEndFalse.count(decl), "");
int trueIndex = _indicesEndTrue.at(decl);
int falseIndex = _indicesEndFalse.at(decl);
solAssert(trueIndex != falseIndex, "");
m_interface->addAssertion(newValue(*decl) == smt::Expression::ite(
_condition,
valueAtIndex(*decl, trueIndex),
valueAtIndex(*decl, falseIndex))
);
}
}
bool SMTChecker::createVariable(VariableDeclaration const& _varDecl)
{
// This might be the case for multiple calls to the same function.
if (knownVariable(_varDecl))
return true;
auto const& type = _varDecl.type();
solAssert(m_variables.count(&_varDecl) == 0, "");
auto result = newSymbolicVariable(*type, _varDecl.name() + "_" + to_string(_varDecl.id()), *m_interface);
m_variables.emplace(&_varDecl, result.second);
if (result.first)
{
m_errorReporter.warning(
_varDecl.location(),
"Assertion checker does not yet support the type of this variable."
);
return false;
}
return true;
}
bool SMTChecker::knownVariable(VariableDeclaration const& _decl)
{
return m_variables.count(&_decl);
}
smt::Expression SMTChecker::currentValue(VariableDeclaration const& _decl)
{
solAssert(knownVariable(_decl), "");
return m_variables.at(&_decl)->currentValue();
}
smt::Expression SMTChecker::valueAtIndex(VariableDeclaration const& _decl, int _index)
{
solAssert(knownVariable(_decl), "");
return m_variables.at(&_decl)->valueAtIndex(_index);
}
smt::Expression SMTChecker::newValue(VariableDeclaration const& _decl)
{
solAssert(knownVariable(_decl), "");
return m_variables.at(&_decl)->increaseIndex();
}
void SMTChecker::setZeroValue(VariableDeclaration const& _decl)
{
solAssert(knownVariable(_decl), "");
setZeroValue(*m_variables.at(&_decl));
}
void SMTChecker::setZeroValue(SymbolicVariable& _variable)
{
smt::setSymbolicZeroValue(_variable, *m_interface);
}
void SMTChecker::setUnknownValue(VariableDeclaration const& _decl)
{
solAssert(knownVariable(_decl), "");
setUnknownValue(*m_variables.at(&_decl));
}
void SMTChecker::setUnknownValue(SymbolicVariable& _variable)
{
smt::setSymbolicUnknownValue(_variable, *m_interface);
}
smt::Expression SMTChecker::expr(Expression const& _e)
{
if (!knownExpr(_e))
{
m_errorReporter.warning(_e.location(), "Internal error: Expression undefined for SMT solver." );
createExpr(_e);
}
return m_expressions.at(&_e)->currentValue();
}
bool SMTChecker::knownExpr(Expression const& _e) const
{
return m_expressions.count(&_e);
}
bool SMTChecker::knownGlobalSymbol(string const& _var) const
{
return m_globalContext.count(_var);
}
void SMTChecker::createExpr(Expression const& _e)
{
solAssert(_e.annotation().type, "");
if (knownExpr(_e))
m_expressions.at(&_e)->increaseIndex();
else
{
auto result = newSymbolicVariable(*_e.annotation().type, "expr_" + to_string(_e.id()), *m_interface);
m_expressions.emplace(&_e, result.second);
if (result.first)
m_errorReporter.warning(
_e.location(),
"Assertion checker does not yet implement this type."
);
}
}
void SMTChecker::defineExpr(Expression const& _e, smt::Expression _value)
{
createExpr(_e);
solAssert(smtKind(_e.annotation().type->category()) != smt::Kind::Function, "Equality operator applied to type that is not fully supported");
m_interface->addAssertion(expr(_e) == _value);
}
void SMTChecker::popPathCondition()
{
solAssert(m_pathConditions.size() > 0, "Cannot pop path condition, empty.");
m_pathConditions.pop_back();
}
void SMTChecker::pushPathCondition(smt::Expression const& _e)
{
m_pathConditions.push_back(currentPathConditions() && _e);
}
smt::Expression SMTChecker::currentPathConditions()
{
if (m_pathConditions.empty())
return smt::Expression(true);
return m_pathConditions.back();
}
void SMTChecker::addPathConjoinedExpression(smt::Expression const& _e)
{
m_interface->addAssertion(currentPathConditions() && _e);
}
void SMTChecker::addPathImpliedExpression(smt::Expression const& _e)
{
m_interface->addAssertion(smt::Expression::implies(currentPathConditions(), _e));
}
bool SMTChecker::isRootFunction()
{
return m_functionPath.size() == 1;
}
bool SMTChecker::visitedFunction(FunctionDefinition const* _funDef)
{
return contains(m_functionPath, _funDef);
}
SMTChecker::VariableIndices SMTChecker::copyVariableIndices()
{
VariableIndices indices;
for (auto const& var: m_variables)
indices.emplace(var.first, var.second->index());
return indices;
}
void SMTChecker::resetVariableIndices(VariableIndices const& _indices)
{
for (auto const& var: _indices)
m_variables.at(var.first)->index() = var.second;
}