1 //=- NSAutoreleasePoolChecker.cpp --------------------------------*- C++ -*-==//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 //  This file defines a NSAutoreleasePoolChecker, a small checker that warns
11 //  about subpar uses of NSAutoreleasePool.  Note that while the check itself
12 //  (in its current form) could be written as a flow-insensitive check, in
13 //  can be potentially enhanced in the future with flow-sensitive information.
14 //  It is also a good example of the CheckerVisitor interface.
15 //
16 //===----------------------------------------------------------------------===//
17 
18 #include "ClangSACheckers.h"
19 #include "clang/StaticAnalyzer/Core/Checker.h"
20 #include "clang/StaticAnalyzer/Core/CheckerManager.h"
21 #include "clang/StaticAnalyzer/Core/BugReporter/BugReporter.h"
22 #include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
23 #include "clang/StaticAnalyzer/Core/PathSensitive/ExprEngine.h"
24 #include "clang/StaticAnalyzer/Core/PathSensitive/ObjCMessage.h"
25 #include "clang/AST/DeclObjC.h"
26 #include "clang/AST/Decl.h"
27 
28 using namespace clang;
29 using namespace ento;
30 
31 namespace {
32 class NSAutoreleasePoolChecker
33   : public Checker<check::PreObjCMessage> {
34 
35   mutable Selector releaseS;
36 
37 public:
38   void checkPreObjCMessage(ObjCMessage msg, CheckerContext &C) const;
39 };
40 
41 } // end anonymous namespace
42 
43 void NSAutoreleasePoolChecker::checkPreObjCMessage(ObjCMessage msg,
44                                                    CheckerContext &C) const {
45 
46   const Expr *receiver = msg.getInstanceReceiver();
47   if (!receiver)
48     return;
49 
50   // FIXME: Enhance with value-tracking information instead of consulting
51   // the type of the expression.
52   const ObjCObjectPointerType* PT =
53     receiver->getType()->getAs<ObjCObjectPointerType>();
54 
55   if (!PT)
56     return;
57   const ObjCInterfaceDecl *OD = PT->getInterfaceDecl();
58   if (!OD)
59     return;
60   if (!OD->getIdentifier()->getName().equals("NSAutoreleasePool"))
61     return;
62 
63   if (releaseS.isNull())
64     releaseS = GetNullarySelector("release", C.getASTContext());
65   // Sending 'release' message?
66   if (msg.getSelector() != releaseS)
67     return;
68 
69   SourceRange R = msg.getSourceRange();
70   BugReporter &BR = C.getBugReporter();
71   const LocationContext *LC = C.getPredecessor()->getLocationContext();
72   const SourceManager &SM = BR.getSourceManager();
73   const Expr *E = msg.getMsgOrPropExpr();
74   PathDiagnosticLocation L = PathDiagnosticLocation::createBegin(E, SM, LC);
75   C.getBugReporter().EmitBasicReport("Use -drain instead of -release",
76     "API Upgrade (Apple)",
77     "Use -drain instead of -release when using NSAutoreleasePool "
78     "and garbage collection", L, &R, 1);
79 }
80 
81 void ento::registerNSAutoreleasePoolChecker(CheckerManager &mgr) {
82   if (mgr.getLangOptions().getGC() != LangOptions::NonGC)
83     mgr.registerChecker<NSAutoreleasePoolChecker>();
84 }
85