1 //== CheckerContext.cpp - Context info for path-sensitive checkers-----------=//
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 file defines CheckerContext that provides contextual info for
11 // path-sensitive checkers.
12 //
13 //===----------------------------------------------------------------------===//
14
15 #include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
16 #include "clang/Basic/Builtins.h"
17 #include "clang/Lex/Lexer.h"
18
19 using namespace clang;
20 using namespace ento;
21
getCalleeDecl(const CallExpr * CE) const22 const FunctionDecl *CheckerContext::getCalleeDecl(const CallExpr *CE) const {
23 const Expr *Callee = CE->getCallee();
24 SVal L = Pred->getSVal(Callee);
25 return L.getAsFunctionDecl();
26 }
27
getCalleeName(const FunctionDecl * FunDecl) const28 StringRef CheckerContext::getCalleeName(const FunctionDecl *FunDecl) const {
29 if (!FunDecl)
30 return StringRef();
31 IdentifierInfo *funI = FunDecl->getIdentifier();
32 if (!funI)
33 return StringRef();
34 return funI->getName();
35 }
36
getDeclDescription(const Decl * D)37 StringRef CheckerContext::getDeclDescription(const Decl *D) {
38 if (isa<ObjCMethodDecl>(D) || isa<CXXMethodDecl>(D))
39 return "method";
40 if (isa<BlockDecl>(D))
41 return "anonymous block";
42 return "function";
43 }
44
isCLibraryFunction(const FunctionDecl * FD,StringRef Name)45 bool CheckerContext::isCLibraryFunction(const FunctionDecl *FD,
46 StringRef Name) {
47 // To avoid false positives (Ex: finding user defined functions with
48 // similar names), only perform fuzzy name matching when it's a builtin.
49 // Using a string compare is slow, we might want to switch on BuiltinID here.
50 unsigned BId = FD->getBuiltinID();
51 if (BId != 0) {
52 if (Name.empty())
53 return true;
54 StringRef BName = FD->getASTContext().BuiltinInfo.getName(BId);
55 if (BName.find(Name) != StringRef::npos)
56 return true;
57 }
58
59 const IdentifierInfo *II = FD->getIdentifier();
60 // If this is a special C++ name without IdentifierInfo, it can't be a
61 // C library function.
62 if (!II)
63 return false;
64
65 // Look through 'extern "C"' and anything similar invented in the future.
66 // If this function is not in TU directly, it is not a C library function.
67 if (!FD->getDeclContext()->getRedeclContext()->isTranslationUnit())
68 return false;
69
70 // If this function is not externally visible, it is not a C library function.
71 // Note that we make an exception for inline functions, which may be
72 // declared in header files without external linkage.
73 if (!FD->isInlined() && !FD->isExternallyVisible())
74 return false;
75
76 if (Name.empty())
77 return true;
78
79 StringRef FName = II->getName();
80 if (FName.equals(Name))
81 return true;
82
83 if (FName.startswith("__inline") && (FName.find(Name) != StringRef::npos))
84 return true;
85
86 if (FName.startswith("__") && FName.endswith("_chk") &&
87 FName.find(Name) != StringRef::npos)
88 return true;
89
90 return false;
91 }
92
getMacroNameOrSpelling(SourceLocation & Loc)93 StringRef CheckerContext::getMacroNameOrSpelling(SourceLocation &Loc) {
94 if (Loc.isMacroID())
95 return Lexer::getImmediateMacroName(Loc, getSourceManager(),
96 getLangOpts());
97 SmallVector<char, 16> buf;
98 return Lexer::getSpelling(Loc, buf, getSourceManager(), getLangOpts());
99 }
100
101 /// Evaluate comparison and return true if it's known that condition is true
evalComparison(SVal LHSVal,BinaryOperatorKind ComparisonOp,SVal RHSVal,ProgramStateRef State)102 static bool evalComparison(SVal LHSVal, BinaryOperatorKind ComparisonOp,
103 SVal RHSVal, ProgramStateRef State) {
104 if (LHSVal.isUnknownOrUndef())
105 return false;
106 ProgramStateManager &Mgr = State->getStateManager();
107 if (!LHSVal.getAs<NonLoc>()) {
108 LHSVal = Mgr.getStoreManager().getBinding(State->getStore(),
109 LHSVal.castAs<Loc>());
110 if (LHSVal.isUnknownOrUndef() || !LHSVal.getAs<NonLoc>())
111 return false;
112 }
113
114 SValBuilder &Bldr = Mgr.getSValBuilder();
115 SVal Eval = Bldr.evalBinOp(State, ComparisonOp, LHSVal, RHSVal,
116 Bldr.getConditionType());
117 if (Eval.isUnknownOrUndef())
118 return false;
119 ProgramStateRef StTrue, StFalse;
120 std::tie(StTrue, StFalse) = State->assume(Eval.castAs<DefinedSVal>());
121 return StTrue && !StFalse;
122 }
123
isGreaterOrEqual(const Expr * E,unsigned long long Val)124 bool CheckerContext::isGreaterOrEqual(const Expr *E, unsigned long long Val) {
125 DefinedSVal V = getSValBuilder().makeIntVal(Val, getASTContext().LongLongTy);
126 return evalComparison(getSVal(E), BO_GE, V, getState());
127 }
128
isNegative(const Expr * E)129 bool CheckerContext::isNegative(const Expr *E) {
130 DefinedSVal V = getSValBuilder().makeIntVal(0, false);
131 return evalComparison(getSVal(E), BO_LT, V, getState());
132 }
133