contrib/llvm/tools/clang/lib/StaticAnalyzer/Checkers/UndefCapturedBlockVarChecker.cpp

   1 // UndefCapturedBlockVarChecker.cpp - Uninitialized captured vars -*- 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 checker detects blocks that capture uninitialized values.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "ClangSACheckers.h"
  15 #include "clang/StaticAnalyzer/Core/Checker.h"
  16 #include "clang/StaticAnalyzer/Core/CheckerManager.h"
  17 #include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
  18 #include "clang/StaticAnalyzer/Core/PathSensitive/ExprEngine.h"
  19 #include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
  20 #include "llvm/ADT/SmallString.h"
  21 #include "llvm/Support/raw_ostream.h"
  22
  23 using namespace clang;
  24 using namespace ento;
  25
  26 namespace {
  27 class UndefCapturedBlockVarChecker
  28   : public Checker< check::PostStmt<BlockExpr> > {
  29  mutable OwningPtr<BugType> BT;
  30
  31 public:
  32   void checkPostStmt(const BlockExpr *BE, CheckerContext &C) const;
  33 };
  34 } // end anonymous namespace
  35
  36 static const DeclRefExpr *FindBlockDeclRefExpr(const Stmt *S,
  37                                                const VarDecl *VD) {
  38   if (const DeclRefExpr *BR = dyn_cast<DeclRefExpr>(S))
  39     if (BR->getDecl() == VD)
  40       return BR;
  41
  42   for (Stmt::const_child_iterator I = S->child_begin(), E = S->child_end();
  43        I!=E; ++I)
  44     if (const Stmt *child = *I) {
  45       const DeclRefExpr *BR = FindBlockDeclRefExpr(child, VD);
  46       if (BR)
  47         return BR;
  48     }
  49
  50   return NULL;
  51 }
  52
  53 void
  54 UndefCapturedBlockVarChecker::checkPostStmt(const BlockExpr *BE,
  55                                             CheckerContext &C) const {
  56   if (!BE->getBlockDecl()->hasCaptures())
  57     return;
  58
  59   ProgramStateRef state = C.getState();
  60   const BlockDataRegion *R =
  61     cast<BlockDataRegion>(state->getSVal(BE,
  62                                          C.getLocationContext()).getAsRegion());
  63
  64   BlockDataRegion::referenced_vars_iterator I = R->referenced_vars_begin(),
  65                                             E = R->referenced_vars_end();
  66
  67   for (; I != E; ++I) {
  68     // This VarRegion is the region associated with the block; we need
  69     // the one associated with the encompassing context.
  70     const VarRegion *VR = *I;
  71     const VarDecl *VD = VR->getDecl();
  72
  73     if (VD->getAttr<BlocksAttr>() || !VD->hasLocalStorage())
  74       continue;
  75
  76     // Get the VarRegion associated with VD in the local stack frame.
  77     const LocationContext *LC = C.getLocationContext();
  78     VR = C.getSValBuilder().getRegionManager().getVarRegion(VD, LC);
  79     SVal VRVal = state->getSVal(VR);
  80
  81     if (VRVal.isUndef())
  82       if (ExplodedNode *N = C.generateSink()) {
  83         if (!BT)
  84           BT.reset(new BuiltinBug("uninitialized variable captured by block"));
  85
  86         // Generate a bug report.
  87         SmallString<128> buf;
  88         llvm::raw_svector_ostream os(buf);
  89
  90         os << "Variable '" << VD->getName()
  91            << "' is uninitialized when captured by block";
  92
  93         BugReport *R = new BugReport(*BT, os.str(), N);
  94         if (const Expr *Ex = FindBlockDeclRefExpr(BE->getBody(), VD))
  95           R->addRange(Ex->getSourceRange());
  96         R->addVisitor(new FindLastStoreBRVisitor(VRVal, VR));
  97         // need location of block
  98         C.EmitReport(R);
  99       }
 100   }
 101 }
 102
 103 void ento::registerUndefCapturedBlockVarChecker(CheckerManager &mgr) {
 104   mgr.registerChecker<UndefCapturedBlockVarChecker>();
 105 }