clang 10.0.0git

PointerSortingChecker.cpp
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1 //== PointerSortingChecker.cpp --------------------------------- -*- C++ -*--=//
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 PointerSortingChecker which checks for non-determinism
10 // caused due to sorting containers with pointer-like elements.
11 //
12 //===----------------------------------------------------------------------===//
13
14 #include "clang/ASTMatchers/ASTMatchFinder.h"
15 #include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h"
16 #include "clang/StaticAnalyzer/Core/Checker.h"
17 #include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
18
19 using namespace clang;
20 using namespace ento;
21 using namespace ast_matchers;
22
23 namespace {
24
25 // ID of a node at which the diagnostic would be emitted.
26 constexpr llvm::StringLiteral WarnAtNode = "sort";
27
28 class PointerSortingChecker : public Checker<check::ASTCodeBody> {
29 public:
30 void checkASTCodeBody(const Decl *D,
31 AnalysisManager &AM,
32 BugReporter &BR) const;
33 };
34
35 static void emitDiagnostics(const BoundNodes &Match, const Decl *D,
36 BugReporter &BR, AnalysisManager &AM,
37 const PointerSortingChecker *Checker) {
38 auto *ADC = AM.getAnalysisDeclContext(D);
39
40 const auto *MarkedStmt = Match.getNodeAs<CallExpr>(WarnAtNode);
41 assert(MarkedStmt);
42
43 auto Range = MarkedStmt->getSourceRange();
44 auto Location = PathDiagnosticLocation::createBegin(MarkedStmt,
45 BR.getSourceManager(),
46 ADC);
47 std::string Diagnostics;
48 llvm::raw_string_ostream OS(Diagnostics);
49 OS << "Sorting pointer-like elements "
50 << "can result in non-deterministic ordering";
51
52 BR.EmitBasicReport(ADC->getDecl(), Checker,
53 "Sorting of pointer-like elements", "Non-determinism",
54 OS.str(), Location, Range);
55 }
56
57 auto callsName(const char *FunctionName) -> decltype(callee(functionDecl())) {
58 return callee(functionDecl(hasName(FunctionName)));
59 }
60
61 // FIXME: Currently we simply check if std::sort is used with pointer-like
62 // elements. This approach can have a big false positive rate. Using std::sort,
63 // std::unique and then erase is common technique for deduplicating a container
64 // (which in some cases might even be quicker than using, let's say std::set).
65 // In case a container contains arbitrary memory addresses (e.g. multiple
66 // things give different stuff but might give the same thing multiple times)
67 // which we don't want to do things with more than once, we might use
68 // sort-unique-erase and the sort call will emit a report.
69 auto matchSortWithPointers() -> decltype(decl()) {
70 // Match any of these function calls.
71 auto SortFuncM = anyOf(
72 callsName("std::is_sorted"),
73 callsName("std::nth_element"),
74 callsName("std::partial_sort"),
75 callsName("std::partition"),
76 callsName("std::sort"),
77 callsName("std::stable_partition"),
78 callsName("std::stable_sort")
79 );
80
81 // Match only if the container has pointer-type elements.
82 auto IteratesPointerEltsM = hasArgument(0,
83 hasType(cxxRecordDecl(has(
84 fieldDecl(hasType(hasCanonicalType(
85 pointsTo(hasCanonicalType(pointerType()))
86 )))
87 ))));
88
89 auto PointerSortM = stmt(callExpr(allOf(SortFuncM, IteratesPointerEltsM))
90 ).bind(WarnAtNode);
91
92 return decl(forEachDescendant(PointerSortM));
93 }
94
95 void PointerSortingChecker::checkASTCodeBody(const Decl *D,
96 AnalysisManager &AM,
97 BugReporter &BR) const {
98 auto MatcherM = matchSortWithPointers();
99
100 auto Matches = match(MatcherM, *D, AM.getASTContext());
101 for (const auto &Match : Matches)
102 emitDiagnostics(Match, D, BR, AM, this);
103 }
104
105 } // end of anonymous namespace
106
107 void ento::registerPointerSortingChecker(CheckerManager &Mgr) {
108 Mgr.registerChecker<PointerSortingChecker>();
109 }
110
111 bool ento::shouldRegisterPointerSortingChecker(const LangOptions &LO) {
112 return LO.CPlusPlus;
113 }
ento
clang::ast_matchers::callExpr
const internal::VariadicDynCastAllOfMatcher< Stmt, CallExpr > callExpr
Matches call expressions.
Definition: ASTMatchersInternal.cpp:668
clang::ast_matchers::stmt
const internal::VariadicAllOfMatcher< Stmt > stmt
Matches statements.
Definition: ASTMatchersInternal.cpp:661
clang::ast_matchers::has
const internal::ArgumentAdaptingMatcherFunc< internal::HasMatcher > has
Matches AST nodes that have child AST nodes that match the provided matcher.
Definition: ASTMatchersInternal.cpp:833
ASTMatchFinder.h
clang::ast_matchers::anyOf
const internal::VariadicOperatorMatcherFunc< 2, std::numeric_limits< unsigned >::max()> anyOf
Matches if any of the given matchers matches.
Definition: ASTMatchersInternal.cpp:820
clang::Decl
Decl - This represents one declaration (or definition), e.g.
Definition: DeclBase.h:88
clang::ast_matchers::pointerType
const AstTypeMatcher< PointerType > pointerType
Matches pointer types, but does not match Objective-C object pointer types.
Definition: ASTMatchersInternal.cpp:872
clang::ast_matchers::allOf
const internal::VariadicOperatorMatcherFunc< 2, std::numeric_limits< unsigned >::max()> allOf
Matches if all given matchers match.
Definition: ASTMatchersInternal.cpp:823
clang::ast_matchers::functionDecl
const internal::VariadicDynCastAllOfMatcher< Decl, FunctionDecl > functionDecl
Matches function declarations.
Definition: ASTMatchersInternal.cpp:657
Checker.h
clang::LangOptions
Keeps track of the various options that can be enabled, which controls the dialect of C or C++ that i...
Definition: LangOptions.h:53
clang::ast_matchers::BoundNodes::getNodeAs
const T * getNodeAs(StringRef ID) const
Returns the AST node bound to ID.
Definition: ASTMatchers.h:111
clang::ast_matchers::match
SmallVector< BoundNodes, 1 > match(MatcherT Matcher, const NodeT &Node, ASTContext &Context)
Returns the results of matching Matcher on Node.
Definition: ASTMatchFinder.h:298
clang::ast_matchers::forEachDescendant
const internal::ArgumentAdaptingMatcherFunc< internal::ForEachDescendantMatcher > forEachDescendant
Matches AST nodes that have descendant AST nodes that match the provided matcher. ...
Definition: ASTMatchersInternal.cpp:839
clang::ast_matchers::decl
const internal::VariadicAllOfMatcher< Decl > decl
Matches declarations.
Definition: ASTMatchersInternal.cpp:607
clang::ast_matchers::fieldDecl
const internal::VariadicDynCastAllOfMatcher< Decl, FieldDecl > fieldDecl
Matches field declarations.
Definition: ASTMatchersInternal.cpp:654
BuiltinCheckerRegistration.h
clang::ast_matchers::BoundNodes
Maps string IDs to AST nodes matched by parts of a matcher.
Definition: ASTMatchers.h:104
clang::ento::PathDiagnosticLocation::createBegin
static PathDiagnosticLocation createBegin(const Decl *D, const SourceManager &SM)
Create a location for the beginning of the declaration.
Definition: PathDiagnostic.cpp:564
clang::Decl::getASTContext
ASTContext & getASTContext() const LLVM_READONLY
Definition: DeclBase.cpp:377
emitDiagnostics
static void emitDiagnostics(BoundNodes &Match, const Decl *D, BugReporter &BR, AnalysisManager &AM, const ObjCAutoreleaseWriteChecker *Checker)
Definition: ObjCAutoreleaseWriteChecker.cpp:108
clang
Dataflow Directional Tag Classes.
Definition: CFGReachabilityAnalysis.h:21
ast_matchers
clang::ast_matchers::cxxRecordDecl
const internal::VariadicDynCastAllOfMatcher< Decl, CXXRecordDecl > cxxRecordDecl
Matches C++ class declarations.
Definition: ASTMatchersInternal.cpp:616
clang::ento::ObjKind::OS
Indicates that the tracking object is a descendant of a referenced-counted OSObject, used in the Darwin kernel.
clang::ast_matchers::hasName
internal::Matcher< NamedDecl > hasName(const std::string &Name)
Matches NamedDecl nodes that have the specified name.
Definition: ASTMatchers.h:2649
clang::CallExpr
CallExpr - Represents a function call (C99 6.5.2.2, C++ [expr.call]).
Definition: Expr.h:2546
CheckerContext.h