UndefinedAssignmentChecker.cpp revision 685379965c1b105ce89cf4f6c60810932b7f4d0d 
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 OwningPtr<BugType> BT;
28
29public:
30  void checkBind(SVal location, SVal val, const Stmt *S,
31                 CheckerContext &C) const;
32};
33}
34
35void UndefinedAssignmentChecker::checkBind(SVal location, SVal val,
36                                           const Stmt *StoreE,
37                                           CheckerContext &C) const {
38  if (!val.isUndef())
39    return;
40
41  ExplodedNode *N = C.generateSink();
42
43  if (!N)
44    return;
45
46  const char *str = "Assigned value is garbage or undefined";
47
48  if (!BT)
49    BT.reset(new BuiltinBug(str));
50
51  // Generate a report for this bug.
52  const Expr *ex = 0;
53
54  while (StoreE) {
55    if (const BinaryOperator *B = dyn_cast<BinaryOperator>(StoreE)) {
56      if (B->isCompoundAssignmentOp()) {
57        ProgramStateRef state = C.getState();
58        if (state->getSVal(B->getLHS(), C.getLocationContext()).isUndef()) {
59          str = "The left expression of the compound assignment is an "
60                "uninitialized value. The computed value will also be garbage";
61          ex = B->getLHS();
62          break;
63        }
64      }
65
66      ex = B->getRHS();
67      break;
68    }
69
70    if (const DeclStmt *DS = dyn_cast<DeclStmt>(StoreE)) {
71      const VarDecl *VD = dyn_cast<VarDecl>(DS->getSingleDecl());
72      ex = VD->getInit();
73    }
74
75    break;
76  }
77
78  BugReport *R = new BugReport(*BT, str, N);
79  if (ex) {
80    R->addRange(ex->getSourceRange());
81    bugreporter::addTrackNullOrUndefValueVisitor(N, ex, R);
82  }
83  R->disablePathPruning();
84  C.EmitReport(R);
85}
86
87void ento::registerUndefinedAssignmentChecker(CheckerManager &mgr) {
88  mgr.registerChecker<UndefinedAssignmentChecker>();
89}
90