solidity/libsolidity/analysis/ViewPureChecker.cpp

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/*
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/analysis/ViewPureChecker.h>
#include <libsolidity/ast/ExperimentalFeatures.h>
#include <libyul/AsmData.h>
#include <libyul/backends/evm/EVMDialect.h>
#include <liblangutil/ErrorReporter.h>
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#include <libevmasm/SemanticInformation.h>
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#include <functional>
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#include <utility>
#include <variant>
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using namespace std;
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using namespace solidity;
using namespace solidity::langutil;
using namespace solidity::frontend;
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namespace
{
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class AssemblyViewPureChecker
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{
public:
explicit AssemblyViewPureChecker(
yul::Dialect const& _dialect,
std::function<void(StateMutability, SourceLocation const&)> _reportMutability
):
m_dialect(_dialect),
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m_reportMutability(std::move(_reportMutability)) {}
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void operator()(yul::Literal const&) {}
void operator()(yul::Identifier const&) {}
void operator()(yul::ExpressionStatement const& _expr)
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{
std::visit(*this, _expr.expression);
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}
void operator()(yul::Assignment const& _assignment)
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{
std::visit(*this, *_assignment.value);
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}
void operator()(yul::VariableDeclaration const& _varDecl)
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{
if (_varDecl.value)
std::visit(*this, *_varDecl.value);
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}
void operator()(yul::FunctionDefinition const& _funDef)
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{
(*this)(_funDef.body);
}
void operator()(yul::FunctionCall const& _funCall)
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{
if (yul::EVMDialect const* dialect = dynamic_cast<decltype(dialect)>(&m_dialect))
if (yul::BuiltinFunctionForEVM const* fun = dialect->builtin(_funCall.functionName.name))
if (fun->instruction)
checkInstruction(_funCall.location, *fun->instruction);
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for (auto const& arg: _funCall.arguments)
std::visit(*this, arg);
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}
void operator()(yul::If const& _if)
{
std::visit(*this, *_if.condition);
(*this)(_if.body);
}
void operator()(yul::Switch const& _switch)
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{
std::visit(*this, *_switch.expression);
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for (auto const& _case: _switch.cases)
{
if (_case.value)
(*this)(*_case.value);
(*this)(_case.body);
}
}
void operator()(yul::ForLoop const& _for)
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{
(*this)(_for.pre);
std::visit(*this, *_for.condition);
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(*this)(_for.body);
(*this)(_for.post);
}
void operator()(yul::Break const&)
{
}
void operator()(yul::Continue const&)
{
}
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void operator()(yul::Leave const&)
{
}
void operator()(yul::Block const& _block)
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{
for (auto const& s: _block.statements)
std::visit(*this, s);
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}
private:
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void checkInstruction(SourceLocation _location, evmasm::Instruction _instruction)
{
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if (evmasm::SemanticInformation::invalidInViewFunctions(_instruction))
m_reportMutability(StateMutability::NonPayable, _location);
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else if (evmasm::SemanticInformation::invalidInPureFunctions(_instruction))
m_reportMutability(StateMutability::View, _location);
}
yul::Dialect const& m_dialect;
std::function<void(StateMutability, SourceLocation const&)> m_reportMutability;
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};
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}
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bool ViewPureChecker::check()
{
vector<ContractDefinition const*> contracts;
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for (auto const& node: m_ast)
{
SourceUnit const* source = dynamic_cast<SourceUnit const*>(node.get());
solAssert(source, "");
contracts += source->filteredNodes<ContractDefinition>(source->nodes());
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}
// Check modifiers first to infer their state mutability.
for (auto const& contract: contracts)
for (ModifierDefinition const* mod: contract->functionModifiers())
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mod->accept(*this);
for (auto const& contract: contracts)
contract->accept(*this);
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return !m_errors;
}
bool ViewPureChecker::visit(FunctionDefinition const& _funDef)
{
solAssert(!m_currentFunction, "");
m_currentFunction = &_funDef;
m_bestMutabilityAndLocation = {StateMutability::Pure, _funDef.location()};
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return true;
}
void ViewPureChecker::endVisit(FunctionDefinition const& _funDef)
{
solAssert(m_currentFunction == &_funDef, "");
if (
m_bestMutabilityAndLocation.mutability < _funDef.stateMutability() &&
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_funDef.stateMutability() != StateMutability::Payable &&
_funDef.isImplemented() &&
!_funDef.body().statements().empty() &&
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!_funDef.isConstructor() &&
!_funDef.isFallback() &&
!_funDef.isReceive() &&
!_funDef.overrides()
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)
m_errorReporter.warning(
2018_error,
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_funDef.location(),
"Function state mutability can be restricted to " + stateMutabilityToString(m_bestMutabilityAndLocation.mutability)
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);
m_currentFunction = nullptr;
}
bool ViewPureChecker::visit(ModifierDefinition const& _modifier)
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{
solAssert(m_currentFunction == nullptr, "");
m_bestMutabilityAndLocation = {StateMutability::Pure, _modifier.location()};
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return true;
}
void ViewPureChecker::endVisit(ModifierDefinition const& _modifierDef)
{
solAssert(m_currentFunction == nullptr, "");
m_inferredMutability[&_modifierDef] = std::move(m_bestMutabilityAndLocation);
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}
void ViewPureChecker::endVisit(Identifier const& _identifier)
{
Declaration const* declaration = _identifier.annotation().referencedDeclaration;
solAssert(declaration, "");
StateMutability mutability = StateMutability::Pure;
bool writes = _identifier.annotation().willBeWrittenTo;
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if (VariableDeclaration const* varDecl = dynamic_cast<VariableDeclaration const*>(declaration))
{
if (varDecl->isStateVariable() && !varDecl->isConstant())
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mutability = writes ? StateMutability::NonPayable : StateMutability::View;
}
else if (MagicVariableDeclaration const* magicVar = dynamic_cast<MagicVariableDeclaration const*>(declaration))
{
switch (magicVar->type()->category())
{
case Type::Category::Contract:
solAssert(_identifier.name() == "this" || _identifier.name() == "super", "");
if (!dynamic_cast<ContractType const&>(*magicVar->type()).isSuper())
// reads the address
mutability = StateMutability::View;
break;
case Type::Category::Integer:
solAssert(_identifier.name() == "now", "");
mutability = StateMutability::View;
break;
default:
break;
}
}
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reportMutability(mutability, _identifier.location());
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}
void ViewPureChecker::endVisit(InlineAssembly const& _inlineAssembly)
{
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AssemblyViewPureChecker{
_inlineAssembly.dialect(),
[&](StateMutability _mutability, SourceLocation const& _location) { reportMutability(_mutability, _location); }
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}(_inlineAssembly.operations());
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}
void ViewPureChecker::reportMutability(
StateMutability _mutability,
SourceLocation const& _location,
std::optional<SourceLocation> const& _nestedLocation
)
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{
if (_mutability > m_bestMutabilityAndLocation.mutability)
m_bestMutabilityAndLocation = MutabilityAndLocation{_mutability, _location};
if (!m_currentFunction || _mutability <= m_currentFunction->stateMutability())
return;
// Check for payable here, because any occurrence of `msg.value`
// will set mutability to payable.
if (_mutability == StateMutability::View || (
_mutability == StateMutability::Payable &&
m_currentFunction->stateMutability() == StateMutability::Pure
))
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{
m_errorReporter.typeError(
2527_error,
_location,
"Function declared as pure, but this expression (potentially) reads from the "
"environment or state and thus requires \"view\"."
);
m_errors = true;
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}
else if (_mutability == StateMutability::NonPayable)
{
m_errorReporter.typeError(
8961_error,
_location,
"Function declared as " +
stateMutabilityToString(m_currentFunction->stateMutability()) +
", but this expression (potentially) modifies the state and thus "
"requires non-payable (the default) or payable."
);
m_errors = true;
}
else if (_mutability == StateMutability::Payable)
{
// We do not warn for library functions because they cannot be payable anyway.
// Also internal functions should be allowed to use `msg.value`.
if (m_currentFunction->isPublic() && !m_currentFunction->libraryFunction())
{
if (_nestedLocation)
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m_errorReporter.typeError(
4006_error,
_location,
SecondarySourceLocation().append("\"msg.value\" or \"callvalue()\" appear here inside the modifier.", *_nestedLocation),
"This modifier uses \"msg.value\" or \"callvalue()\" and thus the function has to be payable or internal."
);
else
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m_errorReporter.typeError(
5887_error,
_location,
"\"msg.value\" and \"callvalue()\" can only be used in payable public functions. Make the function "
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"\"payable\" or use an internal function to avoid this error."
);
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m_errors = true;
}
}
else
solAssert(false, "");
solAssert(
m_currentFunction->stateMutability() == StateMutability::View ||
m_currentFunction->stateMutability() == StateMutability::Pure ||
m_currentFunction->stateMutability() == StateMutability::NonPayable,
""
);
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}
void ViewPureChecker::endVisit(FunctionCall const& _functionCall)
{
if (_functionCall.annotation().kind != FunctionCallKind::FunctionCall)
return;
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StateMutability mutability = dynamic_cast<FunctionType const&>(*_functionCall.expression().annotation().type).stateMutability();
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// We only require "nonpayable" to call a payble function.
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if (mutability == StateMutability::Payable)
mutability = StateMutability::NonPayable;
reportMutability(mutability, _functionCall.location());
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}
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bool ViewPureChecker::visit(MemberAccess const& _memberAccess)
{
// Catch the special case of `this.f.selector` which is a pure expression.
ASTString const& member = _memberAccess.memberName();
if (
_memberAccess.expression().annotation().type->category() == Type::Category::Function &&
member == "selector"
)
if (auto const* expr = dynamic_cast<MemberAccess const*>(&_memberAccess.expression()))
if (auto const* exprInt = dynamic_cast<Identifier const*>(&expr->expression()))
if (exprInt->name() == "this")
// Do not continue visiting.
return false;
return true;
}
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void ViewPureChecker::endVisit(MemberAccess const& _memberAccess)
{
StateMutability mutability = StateMutability::Pure;
bool writes = _memberAccess.annotation().willBeWrittenTo;
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ASTString const& member = _memberAccess.memberName();
switch (_memberAccess.expression().annotation().type->category())
{
case Type::Category::Address:
if (member == "balance")
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mutability = StateMutability::View;
break;
case Type::Category::Magic:
{
using MagicMember = pair<MagicType::Kind, string>;
set<MagicMember> static const pureMembers{
{MagicType::Kind::ABI, "decode"},
{MagicType::Kind::ABI, "encode"},
{MagicType::Kind::ABI, "encodePacked"},
{MagicType::Kind::ABI, "encodeWithSelector"},
{MagicType::Kind::ABI, "encodeWithSignature"},
{MagicType::Kind::Block, "blockhash"},
{MagicType::Kind::Message, "data"},
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{MagicType::Kind::Message, "sig"},
{MagicType::Kind::MetaType, "creationCode"},
{MagicType::Kind::MetaType, "runtimeCode"},
{MagicType::Kind::MetaType, "name"},
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{MagicType::Kind::MetaType, "interfaceId"},
{MagicType::Kind::MetaType, "min"},
{MagicType::Kind::MetaType, "max"},
};
set<MagicMember> static const payableMembers{
{MagicType::Kind::Message, "value"}
};
auto const& type = dynamic_cast<MagicType const&>(*_memberAccess.expression().annotation().type);
MagicMember magicMember(type.kind(), member);
if (!pureMembers.count(magicMember))
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mutability = StateMutability::View;
if (payableMembers.count(magicMember))
mutability = StateMutability::Payable;
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break;
}
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case Type::Category::Struct:
{
if (_memberAccess.expression().annotation().type->dataStoredIn(DataLocation::Storage))
mutability = writes ? StateMutability::NonPayable : StateMutability::View;
break;
}
case Type::Category::Array:
{
auto const& type = dynamic_cast<ArrayType const&>(*_memberAccess.expression().annotation().type);
if (member == "length" && type.isDynamicallySized() && type.dataStoredIn(DataLocation::Storage))
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mutability = StateMutability::View;
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break;
}
default:
{
if (VariableDeclaration const* varDecl = dynamic_cast<VariableDeclaration const*>(
_memberAccess.annotation().referencedDeclaration
))
if (varDecl->isStateVariable() && !varDecl->isConstant())
mutability = writes ? StateMutability::NonPayable : StateMutability::View;
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break;
}
}
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reportMutability(mutability, _memberAccess.location());
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}
void ViewPureChecker::endVisit(IndexAccess const& _indexAccess)
{
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if (!_indexAccess.indexExpression())
solAssert(_indexAccess.annotation().type->category() == Type::Category::TypeType, "");
else
{
bool writes = _indexAccess.annotation().willBeWrittenTo;
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if (_indexAccess.baseExpression().annotation().type->dataStoredIn(DataLocation::Storage))
reportMutability(writes ? StateMutability::NonPayable : StateMutability::View, _indexAccess.location());
}
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}
void ViewPureChecker::endVisit(IndexRangeAccess const& _indexRangeAccess)
{
bool writes = _indexRangeAccess.annotation().willBeWrittenTo;
if (_indexRangeAccess.baseExpression().annotation().type->dataStoredIn(DataLocation::Storage))
reportMutability(writes ? StateMutability::NonPayable : StateMutability::View, _indexRangeAccess.location());
}
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void ViewPureChecker::endVisit(ModifierInvocation const& _modifier)
{
solAssert(_modifier.name(), "");
if (ModifierDefinition const* mod = dynamic_cast<decltype(mod)>(_modifier.name()->annotation().referencedDeclaration))
{
solAssert(m_inferredMutability.count(mod), "");
auto const& mutAndLocation = m_inferredMutability.at(mod);
reportMutability(mutAndLocation.mutability, _modifier.location(), mutAndLocation.location);
}
else
solAssert(dynamic_cast<ContractDefinition const*>(_modifier.name()->annotation().referencedDeclaration), "");
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}