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