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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/ControlFlowAnalyzer.h>
#include <liblangutil/SourceLocation.h>
#include <boost/range/algorithm/sort.hpp>
using namespace std;
using namespace langutil;
using namespace dev::solidity;
bool ControlFlowAnalyzer::analyze(ASTNode const& _astRoot)
{
_astRoot.accept(*this);
return Error::containsOnlyWarnings(m_errorReporter.errors());
}
bool ControlFlowAnalyzer::visit(FunctionDefinition const& _function)
{
if (_function.isImplemented())
{
auto const& functionFlow = m_cfg.functionFlow(_function);
checkUninitializedAccess(functionFlow.entry, functionFlow.exit);
}
return false;
}
void ControlFlowAnalyzer::checkUninitializedAccess(CFGNode const* _entry, CFGNode const* _exit) const
{
struct NodeInfo
{
set<VariableDeclaration const*> unassignedVariablesAtEntry;
set<VariableDeclaration const*> unassignedVariablesAtExit;
set<VariableOccurrence const*> uninitializedVariableAccesses;
/// Propagate the information from another node to this node.
/// To be used to propagate information from a node to its exit nodes.
/// Returns true, if new variables were added and thus the current node has
/// to be traversed again.
bool propagateFrom(NodeInfo const& _entryNode)
{
size_t previousUnassignedVariablesAtEntry = unassignedVariablesAtEntry.size();
size_t previousUninitializedVariableAccessess = uninitializedVariableAccesses.size();
unassignedVariablesAtEntry += _entryNode.unassignedVariablesAtExit;
uninitializedVariableAccesses += _entryNode.uninitializedVariableAccesses;
return
unassignedVariablesAtEntry.size() > previousUnassignedVariablesAtEntry ||
uninitializedVariableAccesses.size() > previousUninitializedVariableAccessess
;
}
};
map<CFGNode const*, NodeInfo> nodeInfos;
set<CFGNode const*> nodesToTraverse;
nodesToTraverse.insert(_entry);
// Walk all paths starting from the nodes in ``nodesToTraverse`` until ``NodeInfo::propagateFrom``
// returns false for all exits, i.e. until all paths have been walked with maximal sets of unassigned
// variables and accesses.
while (!nodesToTraverse.empty())
{
CFGNode const* currentNode = *nodesToTraverse.begin();
nodesToTraverse.erase(nodesToTraverse.begin());
auto& nodeInfo = nodeInfos[currentNode];
auto unassignedVariables = nodeInfo.unassignedVariablesAtEntry;
for (auto const& variableOccurrence: currentNode->variableOccurrences)
{
switch (variableOccurrence.kind())
{
case VariableOccurrence::Kind::Assignment:
unassignedVariables.erase(&variableOccurrence.declaration());
break;
case VariableOccurrence::Kind::InlineAssembly:
// We consider all variables referenced in inline assembly as accessed.
// So far any reference is enough, but we might want to actually analyze
// the control flow in the assembly at some point.
case VariableOccurrence::Kind::Access:
case VariableOccurrence::Kind::Return:
if (unassignedVariables.count(&variableOccurrence.declaration()))
{
if (variableOccurrence.declaration().type()->dataStoredIn(DataLocation::Storage))
// Merely store the unassigned access. We do not generate an error right away, since this
// path might still always revert. It is only an error if this is propagated to the exit
// node of the function (i.e. there is a path with an uninitialized access).
nodeInfo.uninitializedVariableAccesses.insert(&variableOccurrence);
}
break;
case VariableOccurrence::Kind::Declaration:
unassignedVariables.insert(&variableOccurrence.declaration());
break;
}
}
nodeInfo.unassignedVariablesAtExit = std::move(unassignedVariables);
// Propagate changes to all exits and queue them for traversal, if needed.
for (auto const& exit: currentNode->exits)
if (nodeInfos[exit].propagateFrom(nodeInfo))
nodesToTraverse.insert(exit);
}
auto const& exitInfo = nodeInfos[_exit];
if (!exitInfo.uninitializedVariableAccesses.empty())
{
vector<VariableOccurrence const*> uninitializedAccessesOrdered(
exitInfo.uninitializedVariableAccesses.begin(),
exitInfo.uninitializedVariableAccesses.end()
);
boost::range::sort(
uninitializedAccessesOrdered,
[](VariableOccurrence const* lhs, VariableOccurrence const* rhs) -> bool
{
return *lhs < *rhs;
}
);
for (auto const* variableOccurrence: uninitializedAccessesOrdered)
{
SecondarySourceLocation ssl;
if (variableOccurrence->occurrence())
ssl.append("The variable was declared here.", variableOccurrence->declaration().location());
m_errorReporter.typeError(
variableOccurrence->occurrence() ?
variableOccurrence->occurrence()->location() :
variableOccurrence->declaration().location(),
ssl,
string("This variable is of storage pointer type and can be ") +
(variableOccurrence->kind() == VariableOccurrence::Kind::Return ? "returned" : "accessed") +
" without prior assignment."
);
}
}
}
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