UndefinedMemoryManipulationCheck.cpp

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//===----------------------------------------------------------------------===//
//
// 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 "UndefinedMemoryManipulationCheck.h"
#include "clang/AST/ASTContext.h"
#include "clang/ASTMatchers/ASTMatchFinder.h"
 
using namespace clang::ast_matchers;
 
namespace clang::tidy::bugprone {
 
namespace {
AST_MATCHER(CXXRecordDecl, isNotTriviallyCopyable) {
  // For incomplete types, assume they are TriviallyCopyable.
  return Node.hasDefinition() ? !Node.isTriviallyCopyable() : false;
}
} // namespace
 
void UndefinedMemoryManipulationCheck::registerMatchers(MatchFinder *Finder) {
  const auto HasNotTriviallyCopyableDecl =
      hasDeclaration(cxxRecordDecl(isNotTriviallyCopyable()));
  const auto ArrayOfNotTriviallyCopyable =
      arrayType(hasElementType(HasNotTriviallyCopyableDecl));
  const auto NotTriviallyCopyableObject = hasType(hasCanonicalType(
      anyOf(pointsTo(qualType(anyOf(HasNotTriviallyCopyableDecl,
                                    ArrayOfNotTriviallyCopyable))),
            ArrayOfNotTriviallyCopyable)));
 
  // Check whether destination object is not TriviallyCopyable.
  // Applicable to all three memory manipulation functions.
  Finder->addMatcher(callExpr(callee(functionDecl(hasAnyName(
                                  "::memset", "::memcpy", "::memmove"))),
                              hasArgument(0, NotTriviallyCopyableObject))
                         .bind("dest"),
                     this);
 
  // Check whether source object is not TriviallyCopyable.
  // Only applicable to memcpy() and memmove().
  Finder->addMatcher(
      callExpr(callee(functionDecl(hasAnyName("::memcpy", "::memmove"))),
               hasArgument(1, NotTriviallyCopyableObject))
          .bind("src"),
      this);
}
 
void UndefinedMemoryManipulationCheck::check(
    const MatchFinder::MatchResult &Result) {
  if (const auto *Call = Result.Nodes.getNodeAs<CallExpr>("dest")) {
    QualType DestType = Call->getArg(0)->IgnoreImplicit()->getType();
    if (!DestType->getPointeeType().isNull())
      DestType = DestType->getPointeeType();
    diag(Call->getBeginLoc(), "undefined behavior, destination object type %0 "
                              "is not TriviallyCopyable")
        << DestType;
  }
  if (const auto *Call = Result.Nodes.getNodeAs<CallExpr>("src")) {
    QualType SourceType = Call->getArg(1)->IgnoreImplicit()->getType();
    if (!SourceType->getPointeeType().isNull())
      SourceType = SourceType->getPointeeType();
    diag(Call->getBeginLoc(),
         "undefined behavior, source object type %0 is not TriviallyCopyable")
        << SourceType;
  }
}
 
} // namespace clang::tidy::bugprone