clang-tools  5.0.0
StringConstructorCheck.cpp
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1 //===--- StringConstructorCheck.cpp - clang-tidy---------------------------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 
10 #include "StringConstructorCheck.h"
11 #include "clang/AST/ASTContext.h"
12 #include "clang/ASTMatchers/ASTMatchFinder.h"
13 #include "clang/Tooling/FixIt.h"
14 
15 using namespace clang::ast_matchers;
16 
17 namespace clang {
18 namespace tidy {
19 namespace misc {
20 
21 AST_MATCHER_P(IntegerLiteral, isBiggerThan, unsigned, N) {
22  return Node.getValue().getZExtValue() > N;
23 }
24 
25 StringConstructorCheck::StringConstructorCheck(StringRef Name,
27  : ClangTidyCheck(Name, Context),
28  WarnOnLargeLength(Options.get("WarnOnLargeLength", 1) != 0),
29  LargeLengthThreshold(Options.get("LargeLengthThreshold", 0x800000)) {}
30 
32  Options.store(Opts, "WarnOnLargeLength", WarnOnLargeLength);
33  Options.store(Opts, "LargeLengthThreshold", LargeLengthThreshold);
34 }
35 
37  if (!getLangOpts().CPlusPlus)
38  return;
39 
40  const auto ZeroExpr = expr(ignoringParenImpCasts(integerLiteral(equals(0))));
41  const auto CharExpr = expr(ignoringParenImpCasts(characterLiteral()));
42  const auto NegativeExpr = expr(ignoringParenImpCasts(
43  unaryOperator(hasOperatorName("-"),
44  hasUnaryOperand(integerLiteral(unless(equals(0)))))));
45  const auto LargeLengthExpr = expr(ignoringParenImpCasts(
46  integerLiteral(isBiggerThan(LargeLengthThreshold))));
47  const auto CharPtrType = type(anyOf(pointerType(), arrayType()));
48 
49  // Match a string-literal; even through a declaration with initializer.
50  const auto BoundStringLiteral = stringLiteral().bind("str");
51  const auto ConstStrLiteralDecl = varDecl(
52  isDefinition(), hasType(constantArrayType()), hasType(isConstQualified()),
53  hasInitializer(ignoringParenImpCasts(BoundStringLiteral)));
54  const auto ConstPtrStrLiteralDecl = varDecl(
55  isDefinition(),
56  hasType(pointerType(pointee(isAnyCharacter(), isConstQualified()))),
57  hasInitializer(ignoringParenImpCasts(BoundStringLiteral)));
58  const auto ConstStrLiteral = expr(ignoringParenImpCasts(anyOf(
59  BoundStringLiteral, declRefExpr(hasDeclaration(anyOf(
60  ConstPtrStrLiteralDecl, ConstStrLiteralDecl))))));
61 
62  // Check the fill constructor. Fills the string with n consecutive copies of
63  // character c. [i.e string(size_t n, char c);].
64  Finder->addMatcher(
65  cxxConstructExpr(
66  hasDeclaration(cxxMethodDecl(hasName("basic_string"))),
67  hasArgument(0, hasType(qualType(isInteger()))),
68  hasArgument(1, hasType(qualType(isInteger()))),
69  anyOf(
70  // Detect the expression: string('x', 40);
71  hasArgument(0, CharExpr.bind("swapped-parameter")),
72  // Detect the expression: string(0, ...);
73  hasArgument(0, ZeroExpr.bind("empty-string")),
74  // Detect the expression: string(-4, ...);
75  hasArgument(0, NegativeExpr.bind("negative-length")),
76  // Detect the expression: string(0x1234567, ...);
77  hasArgument(0, LargeLengthExpr.bind("large-length"))))
78  .bind("constructor"),
79  this);
80 
81  // Check the literal string constructor with char pointer and length
82  // parameters. [i.e. string (const char* s, size_t n);]
83  Finder->addMatcher(
84  cxxConstructExpr(
85  hasDeclaration(cxxMethodDecl(hasName("basic_string"))),
86  hasArgument(0, hasType(CharPtrType)),
87  hasArgument(1, hasType(isInteger())),
88  anyOf(
89  // Detect the expression: string("...", 0);
90  hasArgument(1, ZeroExpr.bind("empty-string")),
91  // Detect the expression: string("...", -4);
92  hasArgument(1, NegativeExpr.bind("negative-length")),
93  // Detect the expression: string("lit", 0x1234567);
94  hasArgument(1, LargeLengthExpr.bind("large-length")),
95  // Detect the expression: string("lit", 5)
96  allOf(hasArgument(0, ConstStrLiteral.bind("literal-with-length")),
97  hasArgument(1, ignoringParenImpCasts(
98  integerLiteral().bind("int"))))))
99  .bind("constructor"),
100  this);
101 }
102 
103 void StringConstructorCheck::check(const MatchFinder::MatchResult &Result) {
104  const ASTContext &Ctx = *Result.Context;
105  const auto *E = Result.Nodes.getNodeAs<CXXConstructExpr>("constructor");
106  assert(E && "missing constructor expression");
107  SourceLocation Loc = E->getLocStart();
108 
109  if (Result.Nodes.getNodeAs<Expr>("swapped-parameter")) {
110  const Expr *P0 = E->getArg(0);
111  const Expr *P1 = E->getArg(1);
112  diag(Loc, "string constructor parameters are probably swapped;"
113  " expecting string(count, character)")
114  << tooling::fixit::createReplacement(*P0, *P1, Ctx)
115  << tooling::fixit::createReplacement(*P1, *P0, Ctx);
116  } else if (Result.Nodes.getNodeAs<Expr>("empty-string")) {
117  diag(Loc, "constructor creating an empty string");
118  } else if (Result.Nodes.getNodeAs<Expr>("negative-length")) {
119  diag(Loc, "negative value used as length parameter");
120  } else if (Result.Nodes.getNodeAs<Expr>("large-length")) {
121  if (WarnOnLargeLength)
122  diag(Loc, "suspicious large length parameter");
123  } else if (Result.Nodes.getNodeAs<Expr>("literal-with-length")) {
124  const auto *Str = Result.Nodes.getNodeAs<StringLiteral>("str");
125  const auto *Lit = Result.Nodes.getNodeAs<IntegerLiteral>("int");
126  if (Lit->getValue().ugt(Str->getLength())) {
127  diag(Loc, "length is bigger then string literal size");
128  }
129  }
130 }
131 
132 } // namespace misc
133 } // namespace tidy
134 } // namespace clang
SourceLocation Loc
'#' location in the include directive
void storeOptions(ClangTidyOptions::OptionMap &Opts) override
Should store all options supported by this check with their current values or default values for opti...
LangOptions getLangOpts() const
Returns the language options from the context.
Definition: ClangTidy.h:187
StringHandle Name
std::unique_ptr< ast_matchers::MatchFinder > Finder
Definition: ClangTidy.cpp:275
Base class for all clang-tidy checks.
Definition: ClangTidy.h:127
AST_MATCHER_P(IntegerLiteral, isBiggerThan, unsigned, N)
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: ClangTidy.cpp:449
std::map< std::string, std::string > OptionMap
ClangTidyContext & Context
Definition: ClangTidy.cpp:87
Every ClangTidyCheck reports errors through a DiagnosticsEngine provided by this context.
void registerMatchers(ast_matchers::MatchFinder *Finder) override
Override this to register AST matchers with Finder.
DiagnosticBuilder diag(SourceLocation Loc, StringRef Description, DiagnosticIDs::Level Level=DiagnosticIDs::Warning)
Add a diagnostic with the check's name.
Definition: ClangTidy.cpp:416
void check(const ast_matchers::MatchFinder::MatchResult &Result) override
ClangTidyChecks that register ASTMatchers should do the actual work in here.