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
18using namespace clang;
19using namespace ento;
20
21const 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
31StringRef 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
40StringRef CheckerContext::getDeclDescription(const Decl *D) {
41 if (isa<ObjCMethodDecl, CXXMethodDecl>(D))
42 return "method";
43 if (isa<BlockDecl>(D))
44 return "anonymous block";
45 return "function";
46}
47
48bool 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 size_t start = BName.find(Name);
59 if (start != StringRef::npos) {
60 // Accept exact match.
61 if (BName.size() == Name.size())
62 return true;
63
64 // v-- match starts here
65 // ...xxxxx...
66 // _xxxxx_
67 // ^ ^ lookbehind and lookahead characters
68
69 const auto MatchPredecessor = [=]() -> bool {
70 return start <= 0 || !llvm::isAlpha(BName[start - 1]);
71 };
72 const auto MatchSuccessor = [=]() -> bool {
73 std::size_t LookbehindPlace = start + Name.size();
74 return LookbehindPlace >= BName.size() ||
75 !llvm::isAlpha(BName[LookbehindPlace]);
76 };
77
78 if (MatchPredecessor() && MatchSuccessor())
79 return true;
80 }
81 }
82
83 const IdentifierInfo *II = FD->getIdentifier();
84 // If this is a special C++ name without IdentifierInfo, it can't be a
85 // C library function.
86 if (!II)
87 return false;
88
89 // Look through 'extern "C"' and anything similar invented in the future.
90 // If this function is not in TU directly, it is not a C library function.
91 if (!FD->getDeclContext()->getRedeclContext()->isTranslationUnit())
92 return false;
93
94 // If this function is not externally visible, it is not a C library function.
95 // Note that we make an exception for inline functions, which may be
96 // declared in header files without external linkage.
97 if (!FD->isInlined() && !FD->isExternallyVisible())
98 return false;
99
100 if (Name.empty())
101 return true;
102
103 StringRef FName = II->getName();
104 if (FName.equals(Name))
105 return true;
106
107 if (FName.startswith("__inline") && FName.contains(Name))
108 return true;
109
110 if (FName.startswith("__") && FName.endswith("_chk") && FName.contains(Name))
111 return true;
112
113 return false;
114}
115
116StringRef CheckerContext::getMacroNameOrSpelling(SourceLocation &Loc) {
117 if (Loc.isMacroID())
118 return Lexer::getImmediateMacroName(Loc, getSourceManager(),
119 getLangOpts());
120 SmallString<16> buf;
121 return Lexer::getSpelling(Loc, buf, getSourceManager(), getLangOpts());
122}
123
124/// Evaluate comparison and return true if it's known that condition is true
125static bool evalComparison(SVal LHSVal, BinaryOperatorKind ComparisonOp,
126 SVal RHSVal, ProgramStateRef State) {
127 if (LHSVal.isUnknownOrUndef())
128 return false;
129 ProgramStateManager &Mgr = State->getStateManager();
130 if (!isa<NonLoc>(LHSVal)) {
131 LHSVal = Mgr.getStoreManager().getBinding(State->getStore(),
132 LHSVal.castAs<Loc>());
133 if (LHSVal.isUnknownOrUndef() || !isa<NonLoc>(LHSVal))
134 return false;
135 }
136
137 SValBuilder &Bldr = Mgr.getSValBuilder();
138 SVal Eval = Bldr.evalBinOp(State, ComparisonOp, LHSVal, RHSVal,
139 Bldr.getConditionType());
140 if (Eval.isUnknownOrUndef())
141 return false;
142 ProgramStateRef StTrue, StFalse;
143 std::tie(StTrue, StFalse) = State->assume(Eval.castAs<DefinedSVal>());
144 return StTrue && !StFalse;
145}
146
147bool CheckerContext::isGreaterOrEqual(const Expr *E, unsigned long long Val) {
148 DefinedSVal V = getSValBuilder().makeIntVal(Val, getASTContext().LongLongTy);
149 return evalComparison(getSVal(E), BO_GE, V, getState());
150}
151
152bool CheckerContext::isNegative(const Expr *E) {
153 DefinedSVal V = getSValBuilder().makeIntVal(0, false);
154 return evalComparison(getSVal(E), BO_LT, V, getState());
155}
156

source code of clang/lib/StaticAnalyzer/Core/CheckerContext.cpp