1 //=- NSAutoreleasePoolChecker.cpp --------------------------------*- C++ -*-==//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 //  This file defines a NSAutoreleasePoolChecker, a small checker that warns
10 //  about subpar uses of NSAutoreleasePool.  Note that while the check itself
11 //  (in its current form) could be written as a flow-insensitive check, in
12 //  can be potentially enhanced in the future with flow-sensitive information.
13 //  It is also a good example of the CheckerVisitor interface.
14 //
15 //===----------------------------------------------------------------------===//
16 
17 #include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h"
18 #include "clang/AST/Decl.h"
19 #include "clang/AST/DeclObjC.h"
20 #include "clang/StaticAnalyzer/Core/BugReporter/BugReporter.h"
21 #include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
22 #include "clang/StaticAnalyzer/Core/Checker.h"
23 #include "clang/StaticAnalyzer/Core/CheckerManager.h"
24 #include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h"
25 #include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
26 #include "clang/StaticAnalyzer/Core/PathSensitive/ExprEngine.h"
27 
28 using namespace clang;
29 using namespace ento;
30 
31 namespace {
32 class NSAutoreleasePoolChecker
33   : public Checker<check::PreObjCMessage> {
34   mutable std::unique_ptr<BugType> BT;
35   mutable Selector releaseS;
36 
37 public:
38   void checkPreObjCMessage(const ObjCMethodCall &msg, CheckerContext &C) const;
39 };
40 
41 } // end anonymous namespace
42 
43 void NSAutoreleasePoolChecker::checkPreObjCMessage(const ObjCMethodCall &msg,
44                                                    CheckerContext &C) const {
45   if (!msg.isInstanceMessage())
46     return;
47 
48   const ObjCInterfaceDecl *OD = msg.getReceiverInterface();
49   if (!OD)
50     return;
51   if (!OD->getIdentifier()->isStr("NSAutoreleasePool"))
52     return;
53 
54   if (releaseS.isNull())
55     releaseS = GetNullarySelector("release", C.getASTContext());
56   // Sending 'release' message?
57   if (msg.getSelector() != releaseS)
58     return;
59 
60   if (!BT)
61     BT.reset(new BugType(this, "Use -drain instead of -release",
62                          "API Upgrade (Apple)"));
63 
64   ExplodedNode *N = C.generateNonFatalErrorNode();
65   if (!N) {
66     assert(0);
67     return;
68   }
69 
70   auto Report = std::make_unique<PathSensitiveBugReport>(
71       *BT,
72       "Use -drain instead of -release when using NSAutoreleasePool and "
73       "garbage collection",
74       N);
75   Report->addRange(msg.getSourceRange());
76   C.emitReport(std::move(Report));
77 }
78 
79 void ento::registerNSAutoreleasePoolChecker(CheckerManager &mgr) {
80   mgr.registerChecker<NSAutoreleasePoolChecker>();
81 }
82 
83 bool ento::shouldRegisterNSAutoreleasePoolChecker(const LangOptions &LO) {
84   return LO.getGC() != LangOptions::NonGC;
85 }
86