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Warn about copies in storage that might overwrite unexpectedly.

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This commit is contained in:
chriseth
2017-06-26 16:31:36 +02:00
parent 751ba701bc
commit d0b6de0b34
4 changed files with 77 additions and 0 deletions
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libsolidity/analysis/TypeChecker.cpp
+31
View File
@@ -364,6 +364,35 @@ void TypeChecker::checkLibraryRequirements(ContractDefinition const& _contract)
m_errorReporter.typeError(var->location(), "Library cannot have non-constant state variables");
}
void TypeChecker::checkDoubleStorageAssignment(Assignment const& _assignment)
{
TupleType const& lhs = dynamic_cast<TupleType const&>(*type(_assignment.leftHandSide()));
TupleType const& rhs = dynamic_cast<TupleType const&>(*type(_assignment.rightHandSide()));
bool fillRight = !lhs.components().empty() && (!lhs.components().back() || lhs.components().front());
size_t storageToStorageCopies = 0;
size_t toStorageCopies = 0;
for (size_t i = 0; i < lhs.components().size(); ++i)
{
ReferenceType const* ref = dynamic_cast<ReferenceType const*>(lhs.components()[i].get());
if (!ref || !ref->dataStoredIn(DataLocation::Storage) || ref->isPointer())
continue;
size_t rhsPos = fillRight ? i : rhs.components().size() - (lhs.components().size() - i);
solAssert(rhsPos < rhs.components().size(), "");
toStorageCopies++;
if (rhs.components()[rhsPos]->dataStoredIn(DataLocation::Storage))
storageToStorageCopies++;
}
if (storageToStorageCopies >= 1 && toStorageCopies >= 2)
m_errorReporter.warning(
_assignment.location(),
"This assignment performs two copies to storage. Since storage copies do not first "
"copy to a temporary location, one of them might be overwritten before the second "
"is executed and thus may have unexpected effects. It is safer to perform the copies "
"separately or assign to storage pointers first."
);
}
void TypeChecker::endVisit(InheritanceSpecifier const& _inheritance)
{
auto base = dynamic_cast<ContractDefinition const*>(&dereference(_inheritance.name()));
@@ -1047,6 +1076,8 @@ bool TypeChecker::visit(Assignment const& _assignment)
// Sequenced assignments of tuples is not valid, make the result a "void" type.
_assignment.annotation().type = make_shared<TupleType>();
expectType(_assignment.rightHandSide(), *tupleType);
checkDoubleStorageAssignment(_assignment);
}
else if (t->category() == Type::Category::Mapping)
{
libsolidity/analysis/TypeChecker.h
+3
View File
@@ -69,6 +69,9 @@ private:
void checkContractExternalTypeClashes(ContractDefinition const& _contract);
/// Checks that all requirements for a library are fulfilled if this is a library.
void checkLibraryRequirements(ContractDefinition const& _contract);
/// Checks (and warns) if a tuple assignment might cause unexpected overwrites in storage.
/// Should only be called if the left hand side is tuple-typed.
void checkDoubleStorageAssignment(Assignment const& _assignment);
virtual void endVisit(InheritanceSpecifier const& _inheritance) override;
virtual void endVisit(UsingForDirective const& _usingFor) override;