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 #ifndef LO_CLANG_SHARED_PLUGINS
  11
  12 #include "check.hxx"
  13 #include "plugin.hxx"
  14
  15 /* OWeakObject::release() disposes weak references.  If that isn't done
  16  * because a sub-class improperly overrides release() then
  17  * OWeakConnectionPoint::m_pObject continues to point to the deleted object
  18  * and that could result in use-after-free.
  19  */
  20
  21 namespace {
  22
  23 class WeakObject
  24     : public loplugin::FilteringPlugin<WeakObject>
  25 {
  26
  27 public:
  28     explicit WeakObject(loplugin::InstantiationData const& rData): FilteringPlugin(rData)
  29     {}
  30
  31     virtual bool preRun() override {
  32         return compiler.getLangOpts().CPlusPlus; // no OWeakObject in C
  33     }
  34     void run() override {
  35         if( preRun()) {
  36             TraverseDecl(compiler.getASTContext().getTranslationUnitDecl());
  37         }
  38     }
  39
  40     bool isDerivedFromOWeakObject(CXXMethodDecl const*const pMethodDecl)
  41     {
  42         QualType const pClass(pMethodDecl->getParent()->getTypeForDecl(), 0);
  43         if (loplugin::TypeCheck(pClass).Class("OWeakObject").Namespace("cppu"))
  44         {
  45             return true;
  46         }
  47         // hopefully it's faster to recurse overridden methods than the
  48         // thicket of WeakImplHelper32 but that is purely speculation
  49         for (auto it = pMethodDecl->begin_overridden_methods();
  50              it != pMethodDecl->end_overridden_methods(); ++it)
  51         {
  52             if (isDerivedFromOWeakObject(*it))
  53             {
  54                 return true;
  55             }
  56         }
  57         return false;
  58     }
  59
  60     bool VisitCXXMethodDecl(CXXMethodDecl const*const pMethodDecl)
  61     {
  62         if (ignoreLocation(pMethodDecl)) {
  63             return true;
  64         }
  65         if (!pMethodDecl->isThisDeclarationADefinition()
  66             || pMethodDecl->isLateTemplateParsed())
  67         {
  68             return true;
  69         }
  70         if (!pMethodDecl->isInstance()) {
  71             return true;
  72         }
  73 // 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") {
  74         if (auto const i = pMethodDecl->getIdentifier()) {
  75             if (i != nullptr && !i->isStr("release")) {
  76                 return true;
  77             }
  78         }
  79         if (pMethodDecl->getNumParams() != 0) {
  80             return true;
  81         }
  82         if (loplugin::TypeCheck(QualType(pMethodDecl->getParent()->getTypeForDecl(), 0)).Class("OWeakObject").Namespace("cppu"))
  83         {
  84             return true;
  85         }
  86
  87         CXXMethodDecl const* pOverridden(nullptr);
  88         for (auto it = pMethodDecl->begin_overridden_methods();
  89              it != pMethodDecl->end_overridden_methods(); ++it)
  90         {
  91             if (auto const i = (*it)->getIdentifier()) {
  92                 if (i != nullptr && i->isStr("release")) {
  93                     pOverridden = *it;
  94                     break;
  95                 }
  96             }
  97         }
  98         if (pOverridden == nullptr)
  99         {
 100             return true;
 101         }
 102         if (!isDerivedFromOWeakObject(pOverridden))
 103         {
 104             return true;
 105         }
 106         CompoundStmt const*const pCompoundStatement(
 107                 dyn_cast<CompoundStmt>(pMethodDecl->getBody()));
 108         for (auto i = pCompoundStatement->body_begin();
 109              i != pCompoundStatement->body_end(); ++i)
 110         {
 111             // note: this is not a CXXMemberCallExpr
 112             CallExpr const*const pCallExpr(dyn_cast<CallExpr>(*i));
 113             if (pCallExpr)
 114             {
 115                 // note: this is only sometimes a CXXMethodDecl
 116                 FunctionDecl const*const pCalled(pCallExpr->getDirectCallee());
 117                 if (pCalled->getName() == "release")
 118                 {
 119 //this never works  && pCalled == pOverridden
 120                     if (pCalled->getParent() == pOverridden->getParent())
 121                     {
 122                         return true;
 123                     }
 124                     // Allow this convenient shortcut:
 125                     auto td = dyn_cast<TypeDecl>(pCalled->getParent());
 126                     if (td != nullptr
 127                         && (loplugin::TypeCheck(td).Class("OWeakObject").Namespace("cppu").GlobalNamespace()
 128                             || loplugin::TypeCheck(td).Class("OWeakAggObject").Namespace("cppu").GlobalNamespace()))
 129                     {
 130                         return true;
 131                     }
 132                 }
 133             }
 134         }
 135
 136         // whitelist
 137         auto tc  = loplugin::TypeCheck(pMethodDecl->getParent());
 138         if (   tc.Class("OWeakAggObject").Namespace("cppu").GlobalNamespace() // conditional call
 139             || tc.Class("WeakComponentImplHelperBase").Namespace("cppu").GlobalNamespace() // extra magic
 140             || tc.Class("WeakAggComponentImplHelperBase").Namespace("cppu").GlobalNamespace() // extra magic
 141             || tc.Class("CDOMImplementation").Namespace("DOM").GlobalNamespace() // a static oddity
 142             || tc.Class("SwXTextFrame").GlobalNamespace() // ambiguous, 3 parents
 143             || tc.Class("SwXTextDocument").GlobalNamespace() // ambiguous, ~4 parents
 144             || tc.Class("SdStyleSheet").GlobalNamespace() // same extra magic as WeakComponentImplHelperBase
 145             || tc.Class("SdXImpressDocument").GlobalNamespace() // same extra magic as WeakComponentImplHelperBase
 146            )
 147         {
 148             return true;
 149         }
 150
 151         report(DiagnosticsEngine::Warning,
 152                 "override of OWeakObject::release() does not call superclass release()",
 153                 pMethodDecl->getLocation())
 154             << pMethodDecl->getSourceRange();
 155
 156         return true;
 157     }
 158
 159 };
 160
 161 loplugin::Plugin::Registration<WeakObject> weakobject("weakobject");
 162
 163 } // namespace
 164
 165 #endif // LO_CLANG_SHARED_PLUGINS
 166
 167 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */