clang-tools 10.0.0

StringConstructorCheck.cpp
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1 //===--- StringConstructorCheck.cpp - clang-tidy---------------------------===//
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 #include "StringConstructorCheck.h"
10 #include "clang/AST/ASTContext.h"
11 #include "clang/ASTMatchers/ASTMatchFinder.h"
12 #include "clang/Tooling/FixIt.h"
13
14 using namespace clang::ast_matchers;
15
16 namespace clang {
17 namespace tidy {
18 namespace bugprone {
19
20 namespace {
21 AST_MATCHER_P(IntegerLiteral, isBiggerThan, unsigned, N) {
22 return Node.getValue().getZExtValue() > N;
23 }
24 } // namespace
25
26 StringConstructorCheck::StringConstructorCheck(StringRef Name,
27 ClangTidyContext *Context)
28 : ClangTidyCheck(Name, Context),
29 WarnOnLargeLength(Options.get("WarnOnLargeLength", 1) != 0),
30 LargeLengthThreshold(Options.get("LargeLengthThreshold", 0x800000)) {}
31
32 void StringConstructorCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
33 Options.store(Opts, "WarnOnLargeLength", WarnOnLargeLength);
34 Options.store(Opts, "LargeLengthThreshold", LargeLengthThreshold);
35 }
36
37 void StringConstructorCheck::registerMatchers(MatchFinder *Finder) {
38 if (!getLangOpts().CPlusPlus)
39 return;
40
41 const auto ZeroExpr = expr(ignoringParenImpCasts(integerLiteral(equals(0))));
42 const auto CharExpr = expr(ignoringParenImpCasts(characterLiteral()));
43 const auto NegativeExpr = expr(ignoringParenImpCasts(
44 unaryOperator(hasOperatorName("-"),
45 hasUnaryOperand(integerLiteral(unless(equals(0)))))));
46 const auto LargeLengthExpr = expr(ignoringParenImpCasts(
47 integerLiteral(isBiggerThan(LargeLengthThreshold))));
48 const auto CharPtrType = type(anyOf(pointerType(), arrayType()));
49
50 // Match a string-literal; even through a declaration with initializer.
51 const auto BoundStringLiteral = stringLiteral().bind("str");
52 const auto ConstStrLiteralDecl = varDecl(
53 isDefinition(), hasType(constantArrayType()), hasType(isConstQualified()),
54 hasInitializer(ignoringParenImpCasts(BoundStringLiteral)));
55 const auto ConstPtrStrLiteralDecl = varDecl(
56 isDefinition(),
57 hasType(pointerType(pointee(isAnyCharacter(), isConstQualified()))),
58 hasInitializer(ignoringParenImpCasts(BoundStringLiteral)));
59 const auto ConstStrLiteral = expr(ignoringParenImpCasts(anyOf(
60 BoundStringLiteral, declRefExpr(hasDeclaration(anyOf(
61 ConstPtrStrLiteralDecl, ConstStrLiteralDecl))))));
62
63 // Check the fill constructor. Fills the string with n consecutive copies of
64 // character c. [i.e string(size_t n, char c);].
65 Finder->addMatcher(
66 cxxConstructExpr(
67 hasDeclaration(cxxMethodDecl(hasName("basic_string"))),
68 hasArgument(0, hasType(qualType(isInteger()))),
69 hasArgument(1, hasType(qualType(isInteger()))),
70 anyOf(
71 // Detect the expression: string('x', 40);
72 hasArgument(0, CharExpr.bind("swapped-parameter")),
73 // Detect the expression: string(0, ...);
74 hasArgument(0, ZeroExpr.bind("empty-string")),
75 // Detect the expression: string(-4, ...);
76 hasArgument(0, NegativeExpr.bind("negative-length")),
77 // Detect the expression: string(0x1234567, ...);
78 hasArgument(0, LargeLengthExpr.bind("large-length"))))
79 .bind("constructor"),
80 this);
81
82 // Check the literal string constructor with char pointer and length
83 // parameters. [i.e. string (const char* s, size_t n);]
84 Finder->addMatcher(
85 cxxConstructExpr(
86 hasDeclaration(cxxMethodDecl(hasName("basic_string"))),
87 hasArgument(0, hasType(CharPtrType)),
88 hasArgument(1, hasType(isInteger())),
89 anyOf(
90 // Detect the expression: string("...", 0);
91 hasArgument(1, ZeroExpr.bind("empty-string")),
92 // Detect the expression: string("...", -4);
93 hasArgument(1, NegativeExpr.bind("negative-length")),
94 // Detect the expression: string("lit", 0x1234567);
95 hasArgument(1, LargeLengthExpr.bind("large-length")),
96 // Detect the expression: string("lit", 5)
97 allOf(hasArgument(0, ConstStrLiteral.bind("literal-with-length")),
98 hasArgument(1, ignoringParenImpCasts(
99 integerLiteral().bind("int"))))))
100 .bind("constructor"),
101 this);
102
103 // Check the literal string constructor with char pointer.
104 // [i.e. string (const char* s);]
105 Finder->addMatcher(
106 cxxConstructExpr(hasDeclaration(cxxMethodDecl(hasName("basic_string"))),
107 hasArgument(0, expr().bind("from-ptr")),
108 hasArgument(1, unless(hasType(isInteger()))))
109 .bind("constructor"),
110 this);
111 }
112
113 void StringConstructorCheck::check(const MatchFinder::MatchResult &Result) {
114 const ASTContext &Ctx = *Result.Context;
115 const auto *E = Result.Nodes.getNodeAs<CXXConstructExpr>("constructor");
116 assert(E && "missing constructor expression");
117 SourceLocation Loc = E->getBeginLoc();
118
119 if (Result.Nodes.getNodeAs<Expr>("swapped-parameter")) {
120 const Expr *P0 = E->getArg(0);
121 const Expr *P1 = E->getArg(1);
122 diag(Loc, "string constructor parameters are probably swapped;"
123 " expecting string(count, character)")
124 << tooling::fixit::createReplacement(*P0, *P1, Ctx)
125 << tooling::fixit::createReplacement(*P1, *P0, Ctx);
126 } else if (Result.Nodes.getNodeAs<Expr>("empty-string")) {
127 diag(Loc, "constructor creating an empty string");
128 } else if (Result.Nodes.getNodeAs<Expr>("negative-length")) {
129 diag(Loc, "negative value used as length parameter");
130 } else if (Result.Nodes.getNodeAs<Expr>("large-length")) {
131 if (WarnOnLargeLength)
132 diag(Loc, "suspicious large length parameter");
133 } else if (Result.Nodes.getNodeAs<Expr>("literal-with-length")) {
134 const auto *Str = Result.Nodes.getNodeAs<StringLiteral>("str");
135 const auto *Lit = Result.Nodes.getNodeAs<IntegerLiteral>("int");
136 if (Lit->getValue().ugt(Str->getLength())) {
137 diag(Loc, "length is bigger than string literal size");
138 }
139 } else if (const auto *Ptr = Result.Nodes.getNodeAs<Expr>("from-ptr")) {
140 Expr::EvalResult ConstPtr;
141 if (!Ptr->isInstantiationDependent() &&
142 Ptr->EvaluateAsRValue(ConstPtr, Ctx) &&
143 ((ConstPtr.Val.isInt() && ConstPtr.Val.getInt().isNullValue()) ||
144 (ConstPtr.Val.isLValue() && ConstPtr.Val.isNullPointer()))) {
145 diag(Loc, "constructing string from nullptr is undefined behaviour");
146 }
147 }
148 }
149
150 } // namespace bugprone
151 } // namespace tidy
152 } // namespace clang
Loc
SourceLocation Loc
&#39;#&#39; location in the include directive
Definition: IncludeOrderCheck.cpp:37
clang::ast_matchers
Definition: AbseilMatcher.h:14
clang::tidy::bugprone::StringConstructorCheck::registerMatchers
void registerMatchers(ast_matchers::MatchFinder *Finder) override
Override this to register AST matchers with Finder.
Definition: StringConstructorCheck.cpp:37
clang::tidy::ClangTidyCheck
Base class for all clang-tidy checks.
Definition: ClangTidyCheck.h:47
clang::tidy::ClangTidyCheck::getLangOpts
const LangOptions & getLangOpts() const
Returns the language options from the context.
Definition: ClangTidyCheck.h:188
clang::tidy::ClangTidyCheck::Options
OptionsView Options
Definition: ClangTidyCheck.h:184
Ctx
Context Ctx
Definition: TUScheduler.cpp:237
StringConstructorCheck.h
clang::tidy::ClangTidyCheck::OptionsView::store
void store(ClangTidyOptions::OptionMap &Options, StringRef LocalName, StringRef Value) const
Stores an option with the check-local name LocalName with string value Value to Options.
Definition: ClangTidyCheck.cpp:58
Name
static constexpr llvm::StringLiteral Name
Definition: UppercaseLiteralSuffixCheck.cpp:27
clang::tidy::ClangTidyOptions::OptionMap
std::map< std::string, std::string > OptionMap
Definition: ClangTidyOptions.h:97
clang
===– Representation.cpp - ClangDoc Representation --------—*- C++ -*-===//
Definition: ApplyReplacements.h:27
clang::tidy::bugprone::StringConstructorCheck::check
void check(const ast_matchers::MatchFinder::MatchResult &Result) override
ClangTidyChecks that register ASTMatchers should do the actual work in here.
Definition: StringConstructorCheck.cpp:113
clang::tidy::ClangTidyContext
Every ClangTidyCheck reports errors through a DiagnosticsEngine provided by this context.
Definition: ClangTidyDiagnosticConsumer.h:77
E
const Expr * E
Definition: AvoidBindCheck.cpp:82
clang::tidy::bugprone::StringConstructorCheck::storeOptions
void storeOptions(ClangTidyOptions::OptionMap &Opts) override
Should store all options supported by this check with their current values or default values for opti...
Definition: StringConstructorCheck.cpp:32
clang::tidy::ClangTidyCheck::diag
DiagnosticBuilder diag(SourceLocation Loc, StringRef Description, DiagnosticIDs::Level Level=DiagnosticIDs::Warning)
Add a diagnostic with the check&#39;s name.
Definition: ClangTidyCheck.cpp:21
clang::tidy::readability::AST_MATCHER_P
AST_MATCHER_P(CXXMethodDecl, hasCanonicalDecl, ast_matchers::internal::Matcher< CXXMethodDecl >, InnerMatcher)
Definition: ConvertMemberFunctionsToStatic.cpp:52