UndefCapturedBlockVarChecker.cpp revision 8fe83e1df954d72c0f4ffc15d20a5222ec151c21 
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
23using namespace clang;
24using namespace ento;
25
26namespace {
27class UndefCapturedBlockVarChecker
28  : public Checker< check::PostStmt<BlockExpr> > {
29 mutable llvm::OwningPtr<BugType> BT;
30
31public:
32  void checkPostStmt(const BlockExpr *BE, CheckerContext &C) const;
33};
34} // end anonymous namespace
35
36static const BlockDeclRefExpr *FindBlockDeclRefExpr(const Stmt *S,
37                                                    const VarDecl *VD){
38  if (const BlockDeclRefExpr *BR = dyn_cast<BlockDeclRefExpr>(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 BlockDeclRefExpr *BR = FindBlockDeclRefExpr(child, VD);
46      if (BR)
47        return BR;
48    }
49
50  return NULL;
51}
52
53void
54UndefCapturedBlockVarChecker::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        llvm::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
103void ento::registerUndefCapturedBlockVarChecker(CheckerManager &mgr) {
104  mgr.registerChecker<UndefCapturedBlockVarChecker>();
105}
106