compilerplugins/clang/weakobject.cxx

   1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
   2 /*
   3  * This file is part of the LibreOffice project.
   4  *
   5  * This Source Code Form is subject to the terms of the Mozilla Public
   6  * License, v. 2.0. If a copy of the MPL was not distributed with this
   7  * file, You can obtain one at http://mozilla.org/MPL/2.0/.
   8  */
   9
  10 #include "check.hxx"
  11 #include "plugin.hxx"
  12
  13 /* OWeakObject::release() disposes weak references.  If that isn't done
  14  * because a sub-class improperly overrides release() then
  15  * OWeakConnectionPoint::m_pObject continues to point to the deleted object
  16  * and that could result in use-after-free.
  17  */
  18
  19 namespace {
  20
  21 class WeakObject
  22     : public clang::RecursiveASTVisitor<WeakObject>
  23     , public loplugin::Plugin
  24 {
  25
  26 public:
  27     explicit WeakObject(loplugin::InstantiationData const& rData): Plugin(rData)
  28     {}
  29
  30     void run() override {
  31         if (compiler.getLangOpts().CPlusPlus) { // no OWeakObject in C
  32             TraverseDecl(compiler.getASTContext().getTranslationUnitDecl());
  33         }
  34     }
  35
  36     bool isDerivedFromOWeakObject(CXXMethodDecl const*const pMethodDecl)
  37     {
  38         QualType const pClass(pMethodDecl->getParent()->getTypeForDecl(), 0);
  39         if (loplugin::TypeCheck(pClass).Class("OWeakObject").Namespace("cppu"))
  40         {
  41             return true;
  42         }
  43         // hopefully it's faster to recurse overridden methods than the
  44         // thicket of WeakImplHelper32 but that is purely speculation
  45         for (auto it = pMethodDecl->begin_overridden_methods();
  46              it != pMethodDecl->end_overridden_methods(); ++it)
  47         {
  48             if (isDerivedFromOWeakObject(*it))
  49             {
  50                 return true;
  51             }
  52         }
  53         return false;
  54     }
  55
  56     bool VisitCXXMethodDecl(CXXMethodDecl const*const pMethodDecl)
  57     {
  58         if (ignoreLocation(pMethodDecl)) {
  59             return true;
  60         }
  61         if (!pMethodDecl->isThisDeclarationADefinition()
  62             || pMethodDecl->isLateTemplateParsed())
  63         {
  64             return true;
  65         }
  66         if (!pMethodDecl->isInstance()) {
  67             return true;
  68         }
  69 // this is too "simple", if a NamedDecl class has a getName() member expecting it to actually work would clearly be unreasonable    if (pMethodDecl->getName() != "release") {
  70         if (auto const i = pMethodDecl->getIdentifier()) {
  71             if (i != nullptr && !i->isStr("release")) {
  72                 return true;
  73             }
  74         }
  75         if (pMethodDecl->getNumParams() != 0) {
  76             return true;
  77         }
  78         if (loplugin::TypeCheck(QualType(pMethodDecl->getParent()->getTypeForDecl(), 0)).Class("OWeakObject").Namespace("cppu"))
  79         {
  80             return true;
  81         }
  82
  83         CXXMethodDecl const* pOverridden(nullptr);
  84         for (auto it = pMethodDecl->begin_overridden_methods();
  85              it != pMethodDecl->end_overridden_methods(); ++it)
  86         {
  87             if (auto const i = (*it)->getIdentifier()) {
  88                 if (i != nullptr && i->isStr("release")) {
  89                     pOverridden = *it;
  90                     break;
  91                 }
  92             }
  93         }
  94         if (pOverridden == nullptr)
  95         {
  96             return true;
  97         }
  98         if (!isDerivedFromOWeakObject(pOverridden))
  99         {
 100             return true;
 101         }
 102         CompoundStmt const*const pCompoundStatement(
 103                 dyn_cast<CompoundStmt>(pMethodDecl->getBody()));
 104         for (auto i = pCompoundStatement->body_begin();
 105              i != pCompoundStatement->body_end(); ++i)
 106         {
 107             // note: this is not a CXXMemberCallExpr
 108             CallExpr const*const pCallExpr(dyn_cast<CallExpr>(*i));
 109             if (pCallExpr)
 110             {
 111                 // note: this is only sometimes a CXXMethodDecl
 112                 FunctionDecl const*const pCalled(pCallExpr->getDirectCallee());
 113                 if (pCalled->getName() == "release")
 114                 {
 115 //this never works  && pCalled == pOverridden
 116                     if (pCalled->getParent() == pOverridden->getParent())
 117                     {
 118                         return true;
 119                     }
 120                     // Allow this convenient shortcut:
 121                     auto td = dyn_cast<TypeDecl>(pCalled->getParent());
 122                     if (td != nullptr
 123                         && (loplugin::TypeCheck(td).Class("OWeakObject").Namespace("cppu").GlobalNamespace()
 124                             || loplugin::TypeCheck(td).Class("OWeakAggObject").Namespace("cppu").GlobalNamespace()))
 125                     {
 126                         return true;
 127                     }
 128                 }
 129             }
 130         }
 131
 132         // whitelist
 133         auto tc  = loplugin::TypeCheck(pMethodDecl->getParent());
 134         if (   tc.Class("OWeakAggObject").Namespace("cppu").GlobalNamespace() // conditional call
 135             || tc.Class("WeakComponentImplHelperBase").Namespace("cppu").GlobalNamespace() // extra magic
 136             || tc.Class("WeakAggComponentImplHelperBase").Namespace("cppu").GlobalNamespace() // extra magic
 137             || tc.Class("CDOMImplementation").Namespace("DOM").GlobalNamespace() // a static oddity
 138             || tc.Class("SwXTextFrame").GlobalNamespace() // ambiguous, 3 parents
 139             || tc.Class("SwXTextDocument").GlobalNamespace() // ambiguous, ~4 parents
 140             || tc.Class("SdStyleSheet").GlobalNamespace() // same extra magic as WeakComponentImplHelperBase
 141             || tc.Class("SdXImpressDocument").GlobalNamespace() // same extra magic as WeakComponentImplHelperBase
 142            )
 143         {
 144             return true;
 145         }
 146
 147         report(DiagnosticsEngine::Warning,
 148                 "override of OWeakObject::release() does not call superclass release()",
 149                 pMethodDecl->getLocation())
 150             << pMethodDecl->getSourceRange();
 151
 152         return true;
 153     }
 154
 155 };
 156
 157 loplugin::Plugin::Registration<WeakObject> X("weakobject");
 158
 159 } // namespace
 160
 161 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */