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//===--- SizeofExpressionCheck.cpp - clang-tidy----------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "SizeofExpressionCheck.h"
#include "../utils/Matchers.h"
#include "clang/AST/ASTContext.h"
#include "clang/ASTMatchers/ASTMatchFinder.h"
using namespace clang::ast_matchers;
namespace clang::tidy::bugprone {
namespace {
AST_MATCHER_P(IntegerLiteral, isBiggerThan, unsigned, N) {
return Node.getValue().ugt(N);
}
AST_MATCHER_P2(Expr, hasSizeOfDescendant, int, Depth,
ast_matchers::internal::Matcher<Expr>, InnerMatcher) {
if (Depth < 0)
return false;
const Expr *E = Node.IgnoreParenImpCasts();
if (InnerMatcher.matches(*E, Finder, Builder))
return true;
if (const auto *CE = dyn_cast<CastExpr>(E)) {
const auto M = hasSizeOfDescendant(Depth - 1, InnerMatcher);
return M.matches(*CE->getSubExpr(), Finder, Builder);
}
if (const auto *UE = dyn_cast<UnaryOperator>(E)) {
const auto M = hasSizeOfDescendant(Depth - 1, InnerMatcher);
return M.matches(*UE->getSubExpr(), Finder, Builder);
}
if (const auto *BE = dyn_cast<BinaryOperator>(E)) {
const auto LHS = hasSizeOfDescendant(Depth - 1, InnerMatcher);
const auto RHS = hasSizeOfDescendant(Depth - 1, InnerMatcher);
return LHS.matches(*BE->getLHS(), Finder, Builder) ||
RHS.matches(*BE->getRHS(), Finder, Builder);
}
return false;
}
CharUnits getSizeOfType(const ASTContext &Ctx, const Type *Ty) {
if (!Ty || Ty->isIncompleteType() || Ty->isDependentType() ||
isa<DependentSizedArrayType>(Ty) || !Ty->isConstantSizeType())
return CharUnits::Zero();
return Ctx.getTypeSizeInChars(Ty);
}
} // namespace
SizeofExpressionCheck::SizeofExpressionCheck(StringRef Name,
ClangTidyContext *Context)
: ClangTidyCheck(Name, Context),
WarnOnSizeOfConstant(Options.get("WarnOnSizeOfConstant", true)),
WarnOnSizeOfIntegerExpression(
Options.get("WarnOnSizeOfIntegerExpression", false)),
WarnOnSizeOfThis(Options.get("WarnOnSizeOfThis", true)),
WarnOnSizeOfCompareToConstant(
Options.get("WarnOnSizeOfCompareToConstant", true)),
WarnOnSizeOfPointerToAggregate(
Options.get("WarnOnSizeOfPointerToAggregate", true)) {}
void SizeofExpressionCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
Options.store(Opts, "WarnOnSizeOfConstant", WarnOnSizeOfConstant);
Options.store(Opts, "WarnOnSizeOfIntegerExpression",
WarnOnSizeOfIntegerExpression);
Options.store(Opts, "WarnOnSizeOfThis", WarnOnSizeOfThis);
Options.store(Opts, "WarnOnSizeOfCompareToConstant",
WarnOnSizeOfCompareToConstant);
Options.store(Opts, "WarnOnSizeOfPointerToAggregate",
WarnOnSizeOfPointerToAggregate);
}
void SizeofExpressionCheck::registerMatchers(MatchFinder *Finder) {
// FIXME:
// Some of the checks should not match in template code to avoid false
// positives if sizeof is applied on template argument.
const auto IntegerExpr = ignoringParenImpCasts(integerLiteral());
const auto ConstantExpr = ignoringParenImpCasts(
anyOf(integerLiteral(), unaryOperator(hasUnaryOperand(IntegerExpr)),
binaryOperator(hasLHS(IntegerExpr), hasRHS(IntegerExpr))));
const auto IntegerCallExpr = ignoringParenImpCasts(callExpr(
anyOf(hasType(isInteger()), hasType(hasCanonicalType(enumType()))),
unless(isInTemplateInstantiation())));
const auto SizeOfExpr = sizeOfExpr(hasArgumentOfType(
hasUnqualifiedDesugaredType(type().bind("sizeof-arg-type"))));
const auto SizeOfZero =
sizeOfExpr(has(ignoringParenImpCasts(integerLiteral(equals(0)))));
// Detect expression like: sizeof(ARRAYLEN);
// Note: The expression 'sizeof(sizeof(0))' is a portable trick used to know
// the sizeof size_t.
if (WarnOnSizeOfConstant) {
Finder->addMatcher(
expr(sizeOfExpr(has(ignoringParenImpCasts(ConstantExpr))),
unless(SizeOfZero))
.bind("sizeof-constant"),
this);
}
// Detect sizeof(f())
if (WarnOnSizeOfIntegerExpression) {
Finder->addMatcher(sizeOfExpr(ignoringParenImpCasts(has(IntegerCallExpr)))
.bind("sizeof-integer-call"),
this);
}
// Detect expression like: sizeof(this);
if (WarnOnSizeOfThis) {
Finder->addMatcher(sizeOfExpr(has(ignoringParenImpCasts(cxxThisExpr())))
.bind("sizeof-this"),
this);
}
// Detect sizeof(kPtr) where kPtr is 'const char* kPtr = "abc"';
const auto CharPtrType = pointerType(pointee(isAnyCharacter()));
const auto ConstStrLiteralDecl =
varDecl(isDefinition(), hasType(hasCanonicalType(CharPtrType)),
hasInitializer(ignoringParenImpCasts(stringLiteral())));
Finder->addMatcher(
sizeOfExpr(has(ignoringParenImpCasts(
expr(hasType(hasCanonicalType(CharPtrType)),
ignoringParenImpCasts(declRefExpr(
hasDeclaration(ConstStrLiteralDecl)))))))
.bind("sizeof-charp"),
this);
// Detect sizeof(ptr) where ptr points to an aggregate (i.e. sizeof(&S)).
// Do not find it if RHS of a 'sizeof(arr) / sizeof(arr[0])' expression.
if (WarnOnSizeOfPointerToAggregate) {
const auto ArrayExpr =
ignoringParenImpCasts(hasType(hasCanonicalType(arrayType())));
const auto ArrayCastExpr = expr(anyOf(
unaryOperator(hasUnaryOperand(ArrayExpr), unless(hasOperatorName("*"))),
binaryOperator(hasEitherOperand(ArrayExpr)),
castExpr(hasSourceExpression(ArrayExpr))));
const auto PointerToArrayExpr = ignoringParenImpCasts(
hasType(hasCanonicalType(pointerType(pointee(arrayType())))));
const auto StructAddrOfExpr = unaryOperator(
hasOperatorName("&"), hasUnaryOperand(ignoringParenImpCasts(
hasType(hasCanonicalType(recordType())))));
const auto PointerToStructType =
hasUnqualifiedDesugaredType(pointerType(pointee(recordType())));
const auto PointerToStructExpr = ignoringParenImpCasts(expr(
hasType(hasCanonicalType(PointerToStructType)), unless(cxxThisExpr())));
const auto ArrayOfPointersExpr = ignoringParenImpCasts(
hasType(hasCanonicalType(arrayType(hasElementType(pointerType()))
.bind("type-of-array-of-pointers"))));
const auto ArrayOfSamePointersExpr =
ignoringParenImpCasts(hasType(hasCanonicalType(
arrayType(equalsBoundNode("type-of-array-of-pointers")))));
const auto ZeroLiteral = ignoringParenImpCasts(integerLiteral(equals(0)));
const auto ArrayOfSamePointersZeroSubscriptExpr =
ignoringParenImpCasts(arraySubscriptExpr(
hasBase(ArrayOfSamePointersExpr), hasIndex(ZeroLiteral)));
const auto ArrayLengthExprDenom =
expr(hasParent(expr(ignoringParenImpCasts(binaryOperator(
hasOperatorName("/"), hasLHS(ignoringParenImpCasts(sizeOfExpr(
has(ArrayOfPointersExpr)))))))),
sizeOfExpr(has(ArrayOfSamePointersZeroSubscriptExpr)));
Finder->addMatcher(expr(anyOf(sizeOfExpr(has(ignoringParenImpCasts(anyOf(
ArrayCastExpr, PointerToArrayExpr,
StructAddrOfExpr, PointerToStructExpr)))),
sizeOfExpr(has(PointerToStructType))),
unless(ArrayLengthExprDenom))
.bind("sizeof-pointer-to-aggregate"),
this);
}
// Detect expression like: sizeof(expr) <= k for a suspicious constant 'k'.
if (WarnOnSizeOfCompareToConstant) {
Finder->addMatcher(
binaryOperator(matchers::isRelationalOperator(),
hasOperands(ignoringParenImpCasts(SizeOfExpr),
ignoringParenImpCasts(integerLiteral(anyOf(
equals(0), isBiggerThan(0x80000))))))
.bind("sizeof-compare-constant"),
this);
}
// Detect expression like: sizeof(expr, expr); most likely an error.
Finder->addMatcher(sizeOfExpr(has(ignoringParenImpCasts(
binaryOperator(hasOperatorName(",")))))
.bind("sizeof-comma-expr"),
this);
// Detect sizeof(...) /sizeof(...));
// FIXME:
// Re-evaluate what cases to handle by the checker.
// Probably any sizeof(A)/sizeof(B) should be error if
// 'A' is not an array (type) and 'B' the (type of the) first element of it.
// Except if 'A' and 'B' are non-pointers, then use the existing size division
// rule.
const auto ElemType =
arrayType(hasElementType(recordType().bind("elem-type")));
const auto ElemPtrType = pointerType(pointee(type().bind("elem-ptr-type")));
Finder->addMatcher(
binaryOperator(
hasOperatorName("/"),
hasLHS(ignoringParenImpCasts(sizeOfExpr(hasArgumentOfType(
hasCanonicalType(type(anyOf(ElemType, ElemPtrType, type()))
.bind("num-type")))))),
hasRHS(ignoringParenImpCasts(sizeOfExpr(
hasArgumentOfType(hasCanonicalType(type().bind("denom-type")))))))
.bind("sizeof-divide-expr"),
this);
// Detect expression like: sizeof(...) * sizeof(...)); most likely an error.
Finder->addMatcher(binaryOperator(hasOperatorName("*"),
hasLHS(ignoringParenImpCasts(SizeOfExpr)),
hasRHS(ignoringParenImpCasts(SizeOfExpr)))
.bind("sizeof-multiply-sizeof"),
this);
Finder->addMatcher(
binaryOperator(hasOperatorName("*"),
hasOperands(ignoringParenImpCasts(SizeOfExpr),
ignoringParenImpCasts(binaryOperator(
hasOperatorName("*"),
hasEitherOperand(
ignoringParenImpCasts(SizeOfExpr))))))
.bind("sizeof-multiply-sizeof"),
this);
// Detect strange double-sizeof expression like: sizeof(sizeof(...));
// Note: The expression 'sizeof(sizeof(0))' is accepted.
Finder->addMatcher(sizeOfExpr(has(ignoringParenImpCasts(hasSizeOfDescendant(
8, allOf(SizeOfExpr, unless(SizeOfZero))))))
.bind("sizeof-sizeof-expr"),
this);
// Detect sizeof in pointer arithmetic like: N * sizeof(S) == P1 - P2 or
// (P1 - P2) / sizeof(S) where P1 and P2 are pointers to type S.
const auto PtrDiffExpr = binaryOperator(
hasOperatorName("-"),
hasLHS(hasType(hasUnqualifiedDesugaredType(pointerType(pointee(
hasUnqualifiedDesugaredType(type().bind("left-ptr-type"))))))),
hasRHS(hasType(hasUnqualifiedDesugaredType(pointerType(pointee(
hasUnqualifiedDesugaredType(type().bind("right-ptr-type"))))))));
Finder->addMatcher(
binaryOperator(
hasAnyOperatorName("==", "!=", "<", "<=", ">", ">=", "+", "-"),
hasOperands(
anyOf(ignoringParenImpCasts(SizeOfExpr),
ignoringParenImpCasts(binaryOperator(
hasOperatorName("*"),
hasEitherOperand(ignoringParenImpCasts(SizeOfExpr))))),
ignoringParenImpCasts(PtrDiffExpr)))
.bind("sizeof-in-ptr-arithmetic-mul"),
this);
Finder->addMatcher(binaryOperator(hasOperatorName("/"),
hasLHS(ignoringParenImpCasts(PtrDiffExpr)),
hasRHS(ignoringParenImpCasts(SizeOfExpr)))
.bind("sizeof-in-ptr-arithmetic-div"),
this);
}
void SizeofExpressionCheck::check(const MatchFinder::MatchResult &Result) {
const ASTContext &Ctx = *Result.Context;
if (const auto *E = Result.Nodes.getNodeAs<Expr>("sizeof-constant")) {
diag(E->getBeginLoc(),
"suspicious usage of 'sizeof(K)'; did you mean 'K'?");
} else if (const auto *E =
Result.Nodes.getNodeAs<Expr>("sizeof-integer-call")) {
diag(E->getBeginLoc(), "suspicious usage of 'sizeof()' on an expression "
"that results in an integer");
} else if (const auto *E = Result.Nodes.getNodeAs<Expr>("sizeof-this")) {
diag(E->getBeginLoc(),
"suspicious usage of 'sizeof(this)'; did you mean 'sizeof(*this)'");
} else if (const auto *E = Result.Nodes.getNodeAs<Expr>("sizeof-charp")) {
diag(E->getBeginLoc(),
"suspicious usage of 'sizeof(char*)'; do you mean 'strlen'?");
} else if (const auto *E =
Result.Nodes.getNodeAs<Expr>("sizeof-pointer-to-aggregate")) {
diag(E->getBeginLoc(),
"suspicious usage of 'sizeof(A*)'; pointer to aggregate");
} else if (const auto *E =
Result.Nodes.getNodeAs<Expr>("sizeof-compare-constant")) {
diag(E->getBeginLoc(),
"suspicious comparison of 'sizeof(expr)' to a constant");
} else if (const auto *E =
Result.Nodes.getNodeAs<Expr>("sizeof-comma-expr")) {
diag(E->getBeginLoc(), "suspicious usage of 'sizeof(..., ...)'");
} else if (const auto *E =
Result.Nodes.getNodeAs<Expr>("sizeof-divide-expr")) {
const auto *NumTy = Result.Nodes.getNodeAs<Type>("num-type");
const auto *DenomTy = Result.Nodes.getNodeAs<Type>("denom-type");
const auto *ElementTy = Result.Nodes.getNodeAs<Type>("elem-type");
const auto *PointedTy = Result.Nodes.getNodeAs<Type>("elem-ptr-type");
CharUnits NumeratorSize = getSizeOfType(Ctx, NumTy);
CharUnits DenominatorSize = getSizeOfType(Ctx, DenomTy);
CharUnits ElementSize = getSizeOfType(Ctx, ElementTy);
if (DenominatorSize > CharUnits::Zero() &&
!NumeratorSize.isMultipleOf(DenominatorSize)) {
diag(E->getBeginLoc(), "suspicious usage of 'sizeof(...)/sizeof(...)';"
" numerator is not a multiple of denominator");
} else if (ElementSize > CharUnits::Zero() &&
DenominatorSize > CharUnits::Zero() &&
ElementSize != DenominatorSize) {
diag(E->getBeginLoc(), "suspicious usage of 'sizeof(...)/sizeof(...)';"
" numerator is not a multiple of denominator");
} else if (NumTy && DenomTy && NumTy == DenomTy) {
diag(E->getBeginLoc(),
"suspicious usage of sizeof pointer 'sizeof(T)/sizeof(T)'");
} else if (PointedTy && DenomTy && PointedTy == DenomTy) {
diag(E->getBeginLoc(),
"suspicious usage of sizeof pointer 'sizeof(T*)/sizeof(T)'");
} else if (NumTy && DenomTy && NumTy->isPointerType() &&
DenomTy->isPointerType()) {
diag(E->getBeginLoc(),
"suspicious usage of sizeof pointer 'sizeof(P*)/sizeof(Q*)'");
}
} else if (const auto *E =
Result.Nodes.getNodeAs<Expr>("sizeof-sizeof-expr")) {
diag(E->getBeginLoc(), "suspicious usage of 'sizeof(sizeof(...))'");
} else if (const auto *E =
Result.Nodes.getNodeAs<Expr>("sizeof-multiply-sizeof")) {
diag(E->getBeginLoc(), "suspicious 'sizeof' by 'sizeof' multiplication");
} else if (const auto *E =
Result.Nodes.getNodeAs<Expr>("sizeof-in-ptr-arithmetic-mul")) {
const auto *LPtrTy = Result.Nodes.getNodeAs<Type>("left-ptr-type");
const auto *RPtrTy = Result.Nodes.getNodeAs<Type>("right-ptr-type");
const auto *SizeofArgTy = Result.Nodes.getNodeAs<Type>("sizeof-arg-type");
if ((LPtrTy == RPtrTy) && (LPtrTy == SizeofArgTy)) {
diag(E->getBeginLoc(), "suspicious usage of 'sizeof(...)' in "
"pointer arithmetic");
}
} else if (const auto *E =
Result.Nodes.getNodeAs<Expr>("sizeof-in-ptr-arithmetic-div")) {
const auto *LPtrTy = Result.Nodes.getNodeAs<Type>("left-ptr-type");
const auto *RPtrTy = Result.Nodes.getNodeAs<Type>("right-ptr-type");
const auto *SizeofArgTy = Result.Nodes.getNodeAs<Type>("sizeof-arg-type");
if ((LPtrTy == RPtrTy) && (LPtrTy == SizeofArgTy)) {
diag(E->getBeginLoc(), "suspicious usage of 'sizeof(...)' in "
"pointer arithmetic");
}
}
}
} // namespace clang::tidy::bugprone
|
