================
@@ -696,6 +730,69 @@ struct StreamOperationEvaluator {
} // end anonymous namespace
+//===----------------------------------------------------------------------===//
+// Definition of NoStreamStateChangeVisitor.
+//===----------------------------------------------------------------------===//
+
+namespace {
+class NoStreamStateChangeVisitor final : public NoOwnershipChangeVisitor {
+protected:
+ /// Syntactically checks whether the callee is a freeing function. Since
+ /// we have no path-sensitive information on this call (we would need a
+ /// CallEvent instead of a CallExpr for that), its possible that a
+ /// freeing function was called indirectly through a function pointer,
+ /// but we are not able to tell, so this is a best effort analysis.
+ bool isFreeingCallAsWritten(const CallExpr &Call) const {
+ const auto *StreamChk = static_cast<const StreamChecker *>(&Checker);
+ if (StreamChk->FCloseDesc.matchesAsWritten(Call))
+ return true;
+
+ return false;
+ }
+
+ bool doesFnIntendToHandleOwnership(const Decl *Callee,
+ ASTContext &ACtx) override {
+ using namespace clang::ast_matchers;
+ const FunctionDecl *FD = dyn_cast<FunctionDecl>(Callee);
+
+ auto Matches =
+ match(findAll(callExpr().bind("call")), *FD->getBody(), ACtx);
+ for (BoundNodes Match : Matches) {
+ if (const auto *Call = Match.getNodeAs<CallExpr>("call"))
+ if (isFreeingCallAsWritten(*Call))
+ return true;
+ }
----------------
Szelethus wrote:
Showing that a function intended to close a stream already relies on
heuristics, and its easy to construct dumb counterexamples for it:
```c++
void absolutelyDoesntCloseItsParam(FILE *p) {
if (coin()) {
FILE *q = fopen(...);
fclose(q); // oh, we saw an fclose, this must've been intended for the
param...
}
}
```
We can surely make this smarter, maybe we should, but in finite steps we get to
the point where we start rewriting the analyzer.
Regarding the CallGraph: if we start to wander of the beaten path (meaning the
path of execution the analyzer was on), especially if we inspect non-trivial
functions in the graph, that will lead to a weaker heuristic in my view.
https://github.com/llvm/llvm-project/pull/94957
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