solidity/libsolidity/formal/CHC.h
2019-09-13 12:40:53 +02:00

212 lines
6.5 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/>.
*/
/**
* Model checker based on Constrained Horn Clauses.
*
* A Solidity contract's CFG is encoded into a system of Horn clauses where
* each block has a predicate and edges are rules.
*
* The entry block is the constructor which has no in-edges.
* The constructor has one out-edge to an artificial block named _Interface_
* which has in/out-edges from/to all public functions.
*
* Loop invariants for Interface -> Interface' are state invariants.
*/
#pragma once
#include <libsolidity/formal/SMTEncoder.h>
#include <libsolidity/formal/CHCSolverInterface.h>
#include <set>
namespace dev
{
namespace solidity
{
class CHC: public SMTEncoder
{
public:
CHC(smt::EncodingContext& _context, langutil::ErrorReporter& _errorReporter);
void analyze(SourceUnit const& _sources);
std::set<Expression const*> const& safeAssertions() const { return m_safeAssertions; }
private:
/// Visitor functions.
//@{
bool visit(ContractDefinition const& _node) override;
void endVisit(ContractDefinition const& _node) override;
bool visit(FunctionDefinition const& _node) override;
void endVisit(FunctionDefinition const& _node) override;
bool visit(IfStatement const& _node) override;
bool visit(WhileStatement const&) override;
bool visit(ForStatement const&) override;
void endVisit(FunctionCall const& _node) override;
void endVisit(Break const& _node) override;
void endVisit(Continue const& _node) override;
void visitAssert(FunctionCall const& _funCall);
void unknownFunctionCall(FunctionCall const& _funCall);
void visitLoop(
BreakableStatement const& _loop,
Expression const* _condition,
Statement const& _body,
ASTNode const* _postLoop
);
//@}
/// Helpers.
//@{
void reset();
void eraseKnowledge();
bool shouldVisit(ContractDefinition const& _contract) const;
bool shouldVisit(FunctionDefinition const& _function) const;
void pushBlock(ASTNode const* _node);
void popBlock();
//@}
/// Sort helpers.
//@{
smt::SortPointer constructorSort();
smt::SortPointer interfaceSort();
smt::SortPointer sort(FunctionDefinition const& _function);
smt::SortPointer sort(ASTNode const* _block);
//@}
/// Predicate helpers.
//@{
/// @returns a new block of given _sort and _name.
std::unique_ptr<smt::SymbolicFunctionVariable> createSymbolicBlock(smt::SortPointer _sort, std::string const& _name);
/// Constructor predicate over current variables.
smt::Expression constructor();
/// Interface predicate over current variables.
smt::Expression interface();
/// Error predicate over current variables.
smt::Expression error();
smt::Expression error(unsigned _idx);
/// Creates a block for the given _node or increases its SSA index
/// if the block already exists which in practice creates a new function.
void createBlock(ASTNode const* _node, std::string const& _prefix = "");
/// Creates a new error block to be used by an assertion.
/// Also registers the predicate.
void createErrorBlock();
void connectBlocks(smt::Expression const& _from, smt::Expression const& _to, smt::Expression const& _constraints = smt::Expression(true));
/// @returns the current symbolic values of the current function's
/// input and output parameters.
std::vector<smt::Expression> currentFunctionVariables();
/// @returns the samve as currentFunctionVariables plus
/// local variables.
std::vector<smt::Expression> currentBlockVariables();
/// Sets the SSA indices of the variables in scope to 0.
/// Used when starting a new block.
void clearIndices();
/// @returns the predicate name for a given node.
std::string predicateName(ASTNode const* _node);
/// @returns a predicate application over the current scoped variables.
smt::Expression predicate(ASTNode const* _node);
//@}
/// Solver related.
//@{
/// Adds Horn rule to the solver.
void addRule(smt::Expression const& _rule, std::string const& _ruleName);
/// @returns true if query is unsatisfiable (safe).
bool query(smt::Expression const& _query, langutil::SourceLocation const& _location);
//@}
/// Predicates.
//@{
/// Constructor predicate.
/// Default constructor sets state vars to 0.
std::unique_ptr<smt::SymbolicVariable> m_constructorPredicate;
/// Artificial Interface predicate.
/// Single entry block for all functions.
std::unique_ptr<smt::SymbolicVariable> m_interfacePredicate;
/// Artificial Error predicate.
/// Single error block for all assertions.
std::unique_ptr<smt::SymbolicVariable> m_errorPredicate;
/// Maps AST nodes to their predicates.
std::unordered_map<ASTNode const*, std::shared_ptr<smt::SymbolicVariable>> m_predicates;
//@}
/// Variables.
//@{
/// State variables sorts.
/// Used by all predicates.
std::vector<smt::SortPointer> m_stateSorts;
/// State variables.
/// Used to create all predicates.
std::vector<VariableDeclaration const*> m_stateVariables;
/// Input sorts for AST nodes.
std::map<ASTNode const*, smt::SortPointer> m_nodeSorts;
//@}
/// Verification targets.
//@{
std::vector<Expression const*> m_verificationTargets;
/// Assertions proven safe.
std::set<Expression const*> m_safeAssertions;
//@}
/// Control-flow.
//@{
FunctionDefinition const* m_currentFunction = nullptr;
/// Number of basic blocks created for the body of the current function.
unsigned m_functionBlocks = 0;
/// The current control flow path.
std::vector<smt::Expression> m_path;
/// Whether a function call was seen in the current scope.
bool m_unknownFunctionCallSeen = false;
/// Whether a break statement was seen in the current scope.
bool m_breakSeen = false;
/// Whether a continue statement was seen in the current scope.
bool m_continueSeen = false;
/// Block where a loop break should go to.
ASTNode const* m_breakDest;
/// Block where a loop continue should go to.
ASTNode const* m_continueDest;
//@}
/// CHC solver.
std::shared_ptr<smt::CHCSolverInterface> m_interface;
/// ErrorReporter that comes from CompilerStack.
langutil::ErrorReporter& m_outerErrorReporter;
};
}
}