UndefinedAssignmentChecker.cpp revision 221345 
1//===--- UndefinedAssignmentChecker.h ---------------------------*- 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 defines UndefinedAssignmentChecker, a builtin check in ExprEngine that
11// checks for assigning undefined values.
12//
13//===----------------------------------------------------------------------===//
14
15#include "ClangSACheckers.h"
16#include "clang/StaticAnalyzer/Core/Checker.h"
17#include "clang/StaticAnalyzer/Core/CheckerManager.h"
18#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
19#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
20
21using namespace clang;
22using namespace ento;
23
24namespace {
25class UndefinedAssignmentChecker
26  : public Checker<check::Bind> {
27  mutable llvm::OwningPtr<BugType> BT;
28
29public:
30  void checkBind(SVal location, SVal val, CheckerContext &C) const;
31};
32}
33
34void UndefinedAssignmentChecker::checkBind(SVal location, SVal val,
35                                           CheckerContext &C) const {
36  if (!val.isUndef())
37    return;
38
39  ExplodedNode *N = C.generateSink();
40
41  if (!N)
42    return;
43
44  const char *str = "Assigned value is garbage or undefined";
45
46  if (!BT)
47    BT.reset(new BuiltinBug(str));
48
49  // Generate a report for this bug.
50  const Expr *ex = 0;
51
52  const Stmt *StoreE = C.getStmt();
53  while (StoreE) {
54    if (const BinaryOperator *B = dyn_cast<BinaryOperator>(StoreE)) {
55      if (B->isCompoundAssignmentOp()) {
56        const GRState *state = C.getState();
57        if (state->getSVal(B->getLHS()).isUndef()) {
58          str = "The left expression of the compound assignment is an "
59                "uninitialized value. The computed value will also be garbage";
60          ex = B->getLHS();
61          break;
62        }
63      }
64
65      ex = B->getRHS();
66      break;
67    }
68
69    if (const DeclStmt *DS = dyn_cast<DeclStmt>(StoreE)) {
70      const VarDecl* VD = dyn_cast<VarDecl>(DS->getSingleDecl());
71      ex = VD->getInit();
72    }
73
74    break;
75  }
76
77  EnhancedBugReport *R = new EnhancedBugReport(*BT, str, N);
78  if (ex) {
79    R->addRange(ex->getSourceRange());
80    R->addVisitorCreator(bugreporter::registerTrackNullOrUndefValue, ex);
81  }
82  C.EmitReport(R);
83}
84
85void ento::registerUndefinedAssignmentChecker(CheckerManager &mgr) {
86  mgr.registerChecker<UndefinedAssignmentChecker>();
87}
88