1 //== CheckerContext.cpp - Context info for path-sensitive checkers-----------=//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file defines CheckerContext that provides contextual info for
10 // path-sensitive checkers.
11 //
12 //===----------------------------------------------------------------------===//
13
14 #include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
15 #include "clang/Basic/Builtins.h"
16 #include "clang/Lex/Lexer.h"
17
18 using namespace clang;
19 using namespace ento;
20
getCalleeDecl(const CallExpr * CE) const21 const FunctionDecl *CheckerContext::getCalleeDecl(const CallExpr *CE) const {
22 const FunctionDecl *D = CE->getDirectCallee();
23 if (D)
24 return D;
25
26 const Expr *Callee = CE->getCallee();
27 SVal L = Pred->getSVal(Callee);
28 return L.getAsFunctionDecl();
29 }
30
getCalleeName(const FunctionDecl * FunDecl) const31 StringRef CheckerContext::getCalleeName(const FunctionDecl *FunDecl) const {
32 if (!FunDecl)
33 return StringRef();
34 IdentifierInfo *funI = FunDecl->getIdentifier();
35 if (!funI)
36 return StringRef();
37 return funI->getName();
38 }
39
getDeclDescription(const Decl * D)40 StringRef CheckerContext::getDeclDescription(const Decl *D) {
41 if (isa<ObjCMethodDecl>(D) || isa<CXXMethodDecl>(D))
42 return "method";
43 if (isa<BlockDecl>(D))
44 return "anonymous block";
45 return "function";
46 }
47
isCLibraryFunction(const FunctionDecl * FD,StringRef Name)48 bool CheckerContext::isCLibraryFunction(const FunctionDecl *FD,
49 StringRef Name) {
50 // To avoid false positives (Ex: finding user defined functions with
51 // similar names), only perform fuzzy name matching when it's a builtin.
52 // Using a string compare is slow, we might want to switch on BuiltinID here.
53 unsigned BId = FD->getBuiltinID();
54 if (BId != 0) {
55 if (Name.empty())
56 return true;
57 StringRef BName = FD->getASTContext().BuiltinInfo.getName(BId);
58 if (BName.find(Name) != StringRef::npos)
59 return true;
60 }
61
62 const IdentifierInfo *II = FD->getIdentifier();
63 // If this is a special C++ name without IdentifierInfo, it can't be a
64 // C library function.
65 if (!II)
66 return false;
67
68 // Look through 'extern "C"' and anything similar invented in the future.
69 // If this function is not in TU directly, it is not a C library function.
70 if (!FD->getDeclContext()->getRedeclContext()->isTranslationUnit())
71 return false;
72
73 // If this function is not externally visible, it is not a C library function.
74 // Note that we make an exception for inline functions, which may be
75 // declared in header files without external linkage.
76 if (!FD->isInlined() && !FD->isExternallyVisible())
77 return false;
78
79 if (Name.empty())
80 return true;
81
82 StringRef FName = II->getName();
83 if (FName.equals(Name))
84 return true;
85
86 if (FName.startswith("__inline") && (FName.find(Name) != StringRef::npos))
87 return true;
88
89 if (FName.startswith("__") && FName.endswith("_chk") &&
90 FName.find(Name) != StringRef::npos)
91 return true;
92
93 return false;
94 }
95
getMacroNameOrSpelling(SourceLocation & Loc)96 StringRef CheckerContext::getMacroNameOrSpelling(SourceLocation &Loc) {
97 if (Loc.isMacroID())
98 return Lexer::getImmediateMacroName(Loc, getSourceManager(),
99 getLangOpts());
100 SmallString<16> buf;
101 return Lexer::getSpelling(Loc, buf, getSourceManager(), getLangOpts());
102 }
103
104 /// Evaluate comparison and return true if it's known that condition is true
evalComparison(SVal LHSVal,BinaryOperatorKind ComparisonOp,SVal RHSVal,ProgramStateRef State)105 static bool evalComparison(SVal LHSVal, BinaryOperatorKind ComparisonOp,
106 SVal RHSVal, ProgramStateRef State) {
107 if (LHSVal.isUnknownOrUndef())
108 return false;
109 ProgramStateManager &Mgr = State->getStateManager();
110 if (!LHSVal.getAs<NonLoc>()) {
111 LHSVal = Mgr.getStoreManager().getBinding(State->getStore(),
112 LHSVal.castAs<Loc>());
113 if (LHSVal.isUnknownOrUndef() || !LHSVal.getAs<NonLoc>())
114 return false;
115 }
116
117 SValBuilder &Bldr = Mgr.getSValBuilder();
118 SVal Eval = Bldr.evalBinOp(State, ComparisonOp, LHSVal, RHSVal,
119 Bldr.getConditionType());
120 if (Eval.isUnknownOrUndef())
121 return false;
122 ProgramStateRef StTrue, StFalse;
123 std::tie(StTrue, StFalse) = State->assume(Eval.castAs<DefinedSVal>());
124 return StTrue && !StFalse;
125 }
126
isGreaterOrEqual(const Expr * E,unsigned long long Val)127 bool CheckerContext::isGreaterOrEqual(const Expr *E, unsigned long long Val) {
128 DefinedSVal V = getSValBuilder().makeIntVal(Val, getASTContext().LongLongTy);
129 return evalComparison(getSVal(E), BO_GE, V, getState());
130 }
131
isNegative(const Expr * E)132 bool CheckerContext::isNegative(const Expr *E) {
133 DefinedSVal V = getSValBuilder().makeIntVal(0, false);
134 return evalComparison(getSVal(E), BO_LT, V, getState());
135 }
136